Rocky Mountain Arsenal Offpost Operable Unit Final Record of Decision Rocky Mountain Arsenal Commerce City, Colorado
Prepared for Program Manager for Rocky Mountain Amenal Building 111, Rocky Mountain Arsenal Commerce City. Colorado 80022-2180
HLA Project No. 21905 402010 Contract No. DAAA05-92-D-0003 Delivery Order No. 0005
TIUS DOCUMENT IS IN7LNDED TO COMPLY WITH THE NATIONAL ENVIRONMENTAL POLICY ACT OF 1969.
THE INFORMATION AND CONCLUSIONS PRESENTED IN TFUS REPORT REPRE- SENT THE OFFICIAL POSITION OF THE DEPARTMENT OF THE ARMY UNLESS EXPRESSLY MODIFMD BY A SUBSEQUENT DOCUMENT. TMS REPORT CONSTI- TUTES THE RELEVAN7 PORTION OF THE ADMINISTRATIVE RECORD FOR TIES CERCLA OPERABLE
December 19, 1995
Harding Lawson Associates z 11.= 1z Engineering and Environmental Services 707 Seventeenth Street, Suite 2400 Denver, CO 80202 - (303) 292-5365 M9604811
Recycled Paper CONTENTS
**'-**-*- DS-1 DECLARATION STATEMENT ......
I.o SITE NAME, LOCATION, AND DESCRIPTION ...... 1-1 ... 1-2 1.1 Environmental Setting ...... 1-2 1.2 Geology ...... 1-3 1.3 Hydrogeology ...... 2-1 2.0 SIIT HISTORY AND ENFORCEMENT ACTIVITIES ...... 2-1 2.1 Operational History ...... * * * * 2-2 2.2 Previous Investigations ...... 2-2 2.2.1 U.S. Environmental Protection Agency Study Area ...... 2-3 2.2.2 U.S. Department of the Army Investigation ...... - - 2-4 2.3 Boundary Containment Systems ...... 2-5 2.3.1 North Boundary Containment System ...... 2-6 2.3.2 Northwest Boundary Containment System ...... 2-6 2.3.3 Irondale Containment System ...... * * 2-7 2.4 Interim Response Actions ...... 2-7 2.4.1 Offpost Interim Response Action ......
2.5 History of CERCLA Enforcement Activities ...... 2-8 3-1 3.0 HIGHLIGM OF COMmUNrff PARTICIPATION ...... 4-1 4.0 SCOPE AND ROLE OF THE OFFPOST OPERABLE UNIT ......
s.o SUINIMARY OF SIT`E CHARACTERISTICS ...... 5-1
5.1 Sources of Contam ination ...... 5-1
5.2 Nature of Contam ination ...... 5-1-
5.3 Contamination Migration Pathways ...... 5-2
5.4 Extent of Contam ination ...... 5-3 5.4.1 Groundw ater ...... 5-3 5.4.2 Surface W ater ...... 5-4 5.4.3 Stream-bottom Sediments ...... 5-5 5.4.4 Surface and Subsurface Soil ...... 5-5 5.4.5 Biota ...... 5-6
5.5 Potential Routes of Human and Environmental Exposure ...... 5-7
'21905 402010 Harding Lawson Associates 1107121895 R02 6-1 6.0 SUMMARY OF SrM RISKS ...... 6-2 ...... 6.1 Human Health Risks 6-2 of Chemicals of Concern ...... 6.1.1 Identification ... 6-3 6.1.2 Exposure Assessment ...... 6-3 Offpost Study Area Exposure Assessment Zones 6.1.2.1 6-5 Offpost Study Area Potential Exposure Points ...... 6.1.2.2 6-6 potential Exposure Pathways and Routes ...... 6.1.2.3 6-8 6.1.2.4 Estimation of Chemical Intake ...... 6-8 6.1.3 Toxicity Assessment ...... *,*** .... 6-9 6.1.4 Risk Characterization ...... 6-9 6.1.4.1 Carcinogenic Risks ...... 6-10 6.1.4.2 Noncarcinogenic Effects ...... 6-11 of Potential Ecological Effects ...... 6.2 Estimation 6-11 M ethod ...... 6.2.1 6-13 6.2.2 Results ...... ****'*** .... 6-14 6.3 Conclusion ...... ALTERNATIVES ...... 7-1 7.0 DESCRIPTION OF GROUNDWATER REMMIATION 7-4 7.1 Common Elements of Alternatives ...... 7-6 identification of Groundwater Alternatives: North Plume Group 7.2 7-6 7.2.1 Alternative N-1: No Action ...... 7.2.2 Alternative N-2: Continued Operation of the North ...... 7-6 Boundary Containment System With Improvements as Necessary System 7-7 7.2.3 Alternative N-4: Offpost Groundwater Intercept and Treatment 7.2.4 Alternative N-5: Expansion of the Offpost Groundwater Intercept and Treatment System ...... 7-10
...... 7-12 7.3 identification of Groundwater Alternatives: Northwest Plume Group 7-12 7.3.1 Alternative N-1: No Action ...... 7.3.2 Alternative NW-2: Continued Operation of the Northwest Boundary Containment System With Improvements as Necessary ..... 7-13 8-1 8.o COMPARATIVE ANALYSIS OFALTERNATWES ...... 8-2 8.1 Comparative Analysis of Remedial Alternatives ...... 8-3 8.1.1 Overall Protection of Human Health and the Environment ...... 8.1.2 Compliance With AppLcable or Relevant and Appropriate Requirements - 8-4 8.1.3 Long-term Effectiveness and Permanence ...... 8-5 8.1.4 Reduction in Toxicity. Mobility. or Volume ...... 8-6 8.1.5 Short-term Effectiveness ...... 8-6 8.1.6 Im plementability ...... 8-7 8.1.7 Cost ...... 8-9 8.1.8 State Acceptance ...... 8-10 8.1.9 Community Acceptance ...... 8-11
8.2 Conclusions of the Comparative Analysis of Alternatives ...... 8-11
ii Harding Lawson Associates 21905 402010 1107121895 R02 9-1 9.o IDENTIFICATION OF THE SELECT REMEDY ...... System ...... 9-1 9.1 Alternative N-4: Offpost Groundwater Intercept and Treatment
9.2 Alternative NW-2: Continued Operation of the Northwest Boundary 9-3 Containment System with Improvements as Necessary ...... 9-5 9.3 Additional Components of the Selected Remedy ...... 9-6 9.4 Cost of Selected Remedy ...... 9-6 9.5 Lim itations ......
9.6 Criteria for Shutting Down Boundary and Offpost. Containment Groundwater 9-7 System s ...... 10-1 10.0 STATUTORY DETERMINATIONS ...... 10-1 10.1 Consistency with the Statutory Requirements of CERCLA in Section 121 10-1 10.1.1 Protection of Hinnan. Health and the Environment ...... 10-2 10-1.2 Compliance With Applicable or Relevant and Appropriate Requirements 10-3 10.1.3 Cost Effectiveness ...... 10-4 10-1.4 Utilization cf Permanent Solutions to the Maximum Extent Practicable . 10-4 10.2 Consistency with the National Contingency Plan ...... 10-5 10.3 Sum m ary ...... 11-1 11.0 DOCUMENTATION OF SIGNIFICANT CHANGES ...... 12-1 12.0 G LO SSARY ...... 13-1 13.0 BIBU OGRALPHY ......
TABLES
6.1 Offj--551 ();-'rdble Urlit Groundwater Chemicals of Concern 6.2 Offt"m ()I--rdble Unit Surface-Water Chemicals of Concern 6.3 DI--r-Alle Unit Sediment Chemicals of Concern in First Creek 6.4 0ifix,st ()I--rable Unit Sod Chemicals of Concern 6.5 Suruman of Ldnd-Use Scenarios and Exposure Routes by Zone 6.6 R- 1--r--n, - I)-,u-s and Slope Factors for Chemicals of Concern Route 6.7 Surrinjar% of Rt-asonable Maximum Exposure Carcinogenic Risks by Zone and Exposure 6.8 Sunimar% of Adult Reasonable Maximum Exposure Noncarcinogenic Han d. Indices by Target Orgd,l dn I Lxposure Assessment Zone Treatment 7.1 COntdinnient System Remediation Coals for the Offpost Groundwater Intercept and S,.,stem 7.2 Containment Svstem Remediation Goals for the North Boundary Containment System 7.3 Containment System Remediation Coals for the Northwest Boundary Containment System 7.4 Groundwater Alternatives for the North and Northwest Plume Groups 8.1 Summarv of the Detailed Analysis and Ranking of Groundwater Alternatives for the North Plume Group 8.2 Summary of the Detailed Analysis and Ranking of Groundwater Alternatives for the Northwest Plume Group
iii '21905 402010 Harding Lawson Associates 1107121995 R02 Remedy 9.1 Estimated Costs of the Offpost Operable Unit Selected and Other Applicable -or Relevant and Appropriate 10.1 Summary Evaluation of Chemical-specific Requirements for the Offpost Operable Unit Applicable or Relevant and Appropriate Requirements 10.2 Summary Evaluation of Action-specific for the Offpo'st Operable Unit or Relevant and Appropriate 10.3 Summary Evaluation of Location-specificApplicable Requirements for the Oftpost Operable Unit
FIGURES
and Offpost Study Area 1.1 Rocky Mountain Arsenal Operable Units 2.1 Locations of Contaminant Source Areas 5.1 Contaminant Migration Pathways Zones 6.1 Offpost Study Area Exposure Assessment Area 6.2 Site Conceptual Model for the Offpost Study Study Area 6.3 Ecological Site Conceptual Model for the Offpost 7.1 Alternative N-4 Remedial System Components 7.2 Alternative N-5 Remedial System Components 9.1 Offpost Area of Revegetation
APPENDIXES
A RESPONSWENESS SUMMARY B INSTITUTIONAL CONTROLS C WELL CLOSURE CRITERIA
402010 Harding Lawson Associates '21905 iv 1107121995 R02 DECLARATION STATEMENT
Rocky Mountain Arsenal Offpost Operable Unit Commerce City, Colorado DECLARATION FOR THE RECORD OF DECISION
SITE NAME AND LOCATION
Rocky Mountain Arsenal Offpost Operable Unit Commerce City, Adams County, Colorado
STATEMENT OF BASIS AND PURPOSE Mountain Arsenal (RMA) This decision document presents the selected remedial action for the Rocky Colorado, chosen in Offpost Operable Unit (OU) in southern Adams County, east of Commerce City, Uability Act accordance with the Comprehensive Environmental Response, Compensation, and Act (SARA) of (CERCLA) of 19 80, as amended by the Superfund Amendments and Reauthorization practicable, the National 1986, and the National Environmental Policy Act (NEPA), and, to the extent is based on the Oil and Hazardous Substances Pollution Contingency Plan (NCP). This decision and purpose of administrative record file for the Offpo--t OU. and this document explains the basis
the selected remedy for the Offpost OU.
ASSESSMENT OF THE SITE
The Offpost Study Area risk assessment showed that even without remedial action, the baseline are cumulative cancer risks from contamination in surface water, soil, sediment, air, and groundwater
within the acceptable cancer risk range established by the U.S. Environmental Protection Agency
(EPA). However, several site-specific factors suggest that remedial alternatives for groundwater
should be developed. These site-specific factors are: (1) groundwater contributes a maximum of
2 x 10'4. or approximately 75 percent of the total carcmogenic risk, (2) maximum contaminant levels
(MCLs). maximum contaminant level goals (NICLCs). and Colorado Basic Standards for Groundwater
(CBSGs) are exceeded for some groundwater contaminants. and (3) hazard indices (HIs) for children
exceed 1.0 in Zones 2, 3. and 4. Although the haziud indices exceed 1.0 in Zones 2, 3, and 4, the
bulk of the HI value is contributed through an assumed domestic use of alluvial groundwater, which
is not presently occurring and under tlus remedy is not intended to occur in the future. The elevated
'21905 402010 Harding Lawson Associates DS-1 0711121895 R02 Declaration for the Record of Decision
groundwater contami- Ms occur only when considering the contribution of groundwater. Therefore, nation is the focus of this decision document.
this site, if not addressed by imple- Actual or threatened releases of hazardous substances from a potential threat to public health, menting the response action selected in this ROD, may present welfare, or the environment.
DESCRIPTION OF THE REMEDY addresses the contamination within the The Offpost OU is one of two OUs at RMA. The Onpost OU contamination north of RMA that 27 square miles of RMA. The Offpost OU addresses groundwater and treatment systems were installed, migrated (1) before the RMA boundary groundwater extraction The selected remedy described and (2) around the boundary systems prior to recent improvements. at the site through in this Record of Decision (ROD) will permanently address contaminants Groundwater containment treatment to reduce the toxicity, mobility, or volume of contaminants. Safe Drinking Water Act system remediation goals are based on the risk assessment and on federal meet those state drinking MCLs, proposed MCLs, nonzero MCLGs, and CBSGs. Action levels also (ARARs). water standards found to be applicable or relevant and appropriate requirements
The major components of the selected remedy are as follows:
Operation of the Offpost Groundwater Intercept and Treatment System
Removal of contaminated groundwater from the alluvial and the weathered upper portion of the Denver Formation J hereafter called the unconfined flow system [UFSI) north of the RMA boundary Ln the First Creek and northern paleochannels using groundwater extraction wells
Treatment of the organic chemicals of concern (CoCs) present in the groundwater using carbon adsorption
Recharge of treated groundwater to the UFS using wells and trenches
Natural attenuation of inorganic chloride and sulfate concentrations to meet applicable standards for groundwater in a manner consistent with the Onpost remedial action
DS-2 Harding Lawson Associates '21905 402010 0711121895 R02 Declaration for the Record of Decision
(NBCS) and the Northwest Continued operation of the North Boundary Containment System Contaminant System Boundary Containment System (NWBCS) - In addition, the Irondale with the (ICS) will continue to operate, as required, for onpost contaminants consistent will be operated to the Irondale Interim Response Action (IRA). These containment systems Remedy for the requirements of Section 2.7 of the FFA, the Agreement for a Conceptual and the onpost Cleanup of the Rocky Mountain Arsenal (Conceptual Remedy Agreement), 35.3 and 35.4 of the ROD, when it is signed. Cessation may occur as provided in Sections FFA and paragraph 20 of the Conceptual Remedy Agreement.
0 Improvements to the NBCS, NWBCS, ICS, and the Offpost Groundwater Intercept and Treatment System as necessary
0 Long-term groundwater monitoring (including monitoring after groundwater treatment has system remedia- ceased to assure continued compliance with the groundwater containment tion goals )
& Five-year site reviews
0 Exposure control/provision of alternate water supply as follows: detec- As of the date of the Onpost ROD, and based on a .392 parts per billion (ppb) to tion limit, the U.S. Army will use the last available quarterly monitoring results determine the DIMP plume footprint for the As part of the Onpost ROD, the U.S. Army and Shell Oil company will pay extension of, and hook-up to, the current distribution system for all existing well owners within the DR-AP plume footprint referenced above.
Existing domestic well owners outside of the DlMP plume footprint as of the date of the Onpost ROD where it is later determined that levels of DR" are eight ppb or greater (or other relevant CBSG at the time) will be hooked up at the U.S. Army and Shell Oil Company's expense to the SACWSD distribution system or provided a deep well or other permanent solution.
For new domestic wells with DMIP levels of eight ppb or greater (or other relevant CBSG at the time), the Offpost ROD institutional controls will provide that the U.S. Army and Shell Oil Company will pay for hook-up to the distribution system or provided a deep well or other permanent solution.
Any user of a domestic well within the Offpost Operable Unit that contains ground- water contaminants denved from RMA at concentrations that exceed the greater of the remediation goals in Tables 7.1 through 7.3 or the ARARs in Table im win be provided an altemative water supply. Bottled water will be provided for cooking and dnnkmg until a permanent alternative water supply is provided. Permanent alter- native water supplies could include installation of a deep uncontaminated wen or connection to a municipal potable water-supply system. This commitment applies to both users of existing domestic wells and users of wells that are lawfully drilled in the future.
Institutional controls to prevent the use of groundwater exceeding remediation goals.
Closure of poorly constructed wells within the Offpost Study Area that could be acting as migration pathways for contaminants found in the Arapahoe Aquifer.
'21905 402010 Harding Lawson Associates DS-3 0711121895 R02 Declaration for the Record of Decision
and to complete an The U.S. Army and Shell Oil Company agree to continue monitoring ppt method detection limit assessment of the NDMA plume by June 13, 1996, using a 20 study of potential U.S. Army and Shell Oil Company agree to prepare a feasibility The in order to achieve actions, both onpost and at the boundary, or adjacent to the boundary PRG or a certified NDMA remediation goals at the RMA boundary and to use 7.0 ppt laboratory (currently alytical detection level readily available at a certified commercial 33 ppt). IL60 acres located in The U.S. Army and Shell Oil Company agree to revegetate approximately Section 13 as depicted in the southeast portion of Section 14 and the southwest portion of will be conducted 9.1. Revegetation will involve tilling and seeding. No sampling Figure fall within EPA;s before or after revegetation. Existing soil. risks in the are to be revegetated However, the U.S. Army establish acceptable risk range and revegetation is not necessary. the offpost settlement. and Shell Oil Company agree to the revegetation program as part of or reinjection Army will treat any contaminated extracted groundwater prior to discharge The Basic that it meets the current water quality standards established in the Colorado so for Surface Standards for Groundwater and the Colorado Basic Standards and Methodologies Water. pay for and As part of the Onpost remedy, the U.S. Army and Shell Oil Company will provide, or arrange for the provision, of 4000 acre-feet of water to SACWSD.
STATUTORY DETERNINATIONS with federal and The selected remedy is protective of human health and the environment, complies remedial action, and state requirements that are legally applicable or relevant and appropriate to the technologies to the is cost-effective. The remedy uses permanent solutions and alternative treatment that employ maximum extent practicable. The remedy satisfies the statutory preference for remedies
treatment that reduces toxicity, mobility, or volume as a principal element
of the Offpost Because this remedy may result in hazardous substances remaining in the groundwater
OU for more than five years, a review will be conducted within five years after commencementof health and the remedial action to ensure that the remedy contmues to adequately protect human
environment.
Harding Lawson Associates '21905 402010 DS-4 0711121995 R02 Declaration for the Record of Decision
SIGNATURE PACE
am P. Yellowtau /Re)kional Mministrator, Region VM Protection Agency (/1111ited States Environmental
Raymb'aFatz Acting Deputy Assistant Secretary of the Army (Environment, Safety and Occupational Health)
STATE OF COLORADO CONCURRENCE
Tom Loob Director, Office of Environmzý4 Colorado Department of Public Health and Environment
'21905 402010 Harding Lawson Associates DS-5 0711121895 R02 DECISION SUMMARY FOR THE RECORD OF DECISION 1.0 SITE NAME, LOCATION, AND DESCRIPTION
of two Operable The Rocky Mountain Arsenal (RMA) National Priorities List (NPL) site is comprised occupies approxi- Units (OUs): Onpost and Offpost. As shown in Figure 1.1, the Offpost Study Area the Denver metropo- mately 27 square miles in southern Adams County, Colorado, and lies north of as the area litan area and east of Commerce City, Colorado. The Offpost Study Area is defined Creek, and north of southeast of the South Platte River, north of 80th Avenue, southwest of Second includes the the north and northwest boundaries of RMA. Additionally, the Offpost Study Area Creek to surface waters of O'Brian Canal and Burlington Ditch as they extend northeast from Second shown in Barr Lake and the surface waters of First Creek and Barr Lake. The Offpost OU (also
Figure 1.1) is defined by the RMA Federal Facility Agreement (FFA) as that portion of the Offpost and are Study Area where hazardous substances, pollutants, or contaminants from RMA are found commercial subject to remediation. The Offpost OU encompasses rural residential, agricultural, and
and industrial areas located north and northwest of RMA.
Areas within the Offpost OU are used for rangeland, dryland farming, and irrigated farming with OU some rural residential areas and scattered areas of intensive agricultuxal use. Parts of the Offpost
are currently zoned and developed for commercial/industrial activities. Commerce City, located west
of RMA, is the only urban area in the immediate vicinity of the Offpost OU and has recently ann exed
lands within the Offpost OU.
On the basis of an evaluation of planning information provided by the Adams County Planning
Commission, it is projected that areas of commercial. industrial, and urban residential land use will
increase in the Offpost OU (Adams County Planrung Commission, 1987). Rural residential (including
agricultural) land use is expected to decrease in the Offpost OU because anticipated increases in
property values are expected to preclude increased traditional crop and livestock production land
use, including hobby farming as discussed in the Airport Environs Plan (Adams County, City of
Aurora, City of Brighton, City of Commerce City, 1990).
'21905 402010 Harding Lawson Associates 0711121495 R02 Site Harn*, Locationg and Description
1.1 Environmental Setting lowlands separated by gently The topography of the Offpost Study Area consists of stream-valley Study Area is approximately rolling uplands. The maximum local topographic relief in the Offpost 5140 feet at the northern 100 feet. The elevation above mean sea level ranges from approximately the South Platte River. and northwestern boundary of RMA to approximately 5030 feet at
Lake and wetland areas at Cropland and rangeland provide habitat for numerous animal species. and endangered species, Barr Lake provide feeding, breeding, and roosting areas for waterfowl by sunny, semiarid including the bald eagle. The climate of the Offpost Study Area is characterized conditions.
River. Suxface water The regional surface drainage is to the northwest toward the South Platte toward the South Platte River. originating south of RMA, on RMA, or in the Offpost Study Area flows ditches flow from Two major canals, O'Brian Canal and Burlington Ditch, and several smaller Canal receives some southwest to northeast between RMA and the South Platte River. O'Brian Creek. Burlington drainage from the Offpost Study Area and RNIA where the canal intercepts First
Ditch mav receive surface water infrequently from First Creek.
1.2 Geology and eohan Sediment at the land surface in the Offpost Study Area consists of unconsolidated alluvial gravels, and deposits. The composition of the unconsolidated sediment varies from clays to coarse of the thickness varies from less than 10 feet to approximately 100 feet. The thickest deposits
unconsolidated sediment occur in paleochannels eroded into the underlying Denver Formation.
The Denver Formation consists of 250 to 300 feet of interbedded shale, claystone, siltstone, and
sandstone, with a regional dip of 1/2 to 1 degree to the southeast. The presence of paleoch;;nnels in the Denver Formation surface impacts groundwater flow in the unconsolidated sediment and the upper weathered portion of the Denver Formation. Three such paleochannels, the First Creek,
1-2 Harding Lawson Associates '21905402010 0711121495 R02 Site Name, Location, and Description
Coarse, unconsoli- northern, and northwestern paleochannels, are present in the Offpost Study Area.
pathways for dated materials commonly found within these paleochannels provide preferential
migrated across the groundwater movement. Groundwater contaminant plumes that have historically
in and near RMA boundaries to the Offpost OU contain the highest concentrations of contaminants
at depths of 230 to these paleochannels. The Arapahoe Formation lies beneath the Denver Formation
southeast. The 300 feet at the RMA north boundary and has a regional dip of 1/2 to 1 degree to the
and shale. formation consists of 400 to 700 feet of interbedded conglomerate, sandstone, siltstone,
of blue to The upper portion of the Arapahoe Formation consists predominantly of 200 to 300 feet
largely of gray shale with some conglomerate and sandstone beds. The lower portion consists
a source zone for sandstone and conglomerate with less prevalent beds of shale. The lower portion is
to many water-supply wells in the area. A thick, impermeable claystone unit is variously assigned
the the lower Denver formation and the upper Arapahoe Formation. The claystone unit is called
Arapahoe -Buffer Zone" and is approximately 50-ft. thick. This unit further isolates the underlying aquifer from any localized contamination in the Denver confined flow system. The Arapahoe
Formation is the oldest geologic unit present beneath the Offpost Study Area that was investigated durLn7, the Offpost Remedial Investigation program.
Aliuviai and eolian deposits form the ground surface in the Offpost Study Area. The Denver
Formation and Arapahoe Formation are not prest-rit at the ground surface anywhere in the Offpost
Study Area.
1.3 Hydrogeology
Tiie two principal water-bearing units in th- Of1post Stu,i%- Area that have been impacted by
contaminants originating from RMA are th,- unconsolidated alluvial deposits and the underlying
Denver Formation. The hydraulic propert ies of thf!se t wo units. including hydraulic conductivity,
porosity, and associated groundwater flow velocities. are distinctly different. The low permeability of
the Denver Formation and upper Arapahoe Formation limit contaminant transport into the lower
'21905 402010 Harding Lawson Associates .1-3 0711121495 R02 Site Ham*, Location, and Description
as two distinct hydrostrati- Arapahoe Formation. Hydraulically, the two units generally behave flow system (CFS). graphic units: the unconfined flow system (UFS) and the confined
overlying the Denver The UFS includes groundwater present in the unconsolidated materials where the Denver Formation Formation, the weathered upper portion of the Denver Formation, and, of the Arapahoe Formation. The is missing near the South Platte River, the weathered upper portion underlying Arapahoe Formation. CFS includes the deeper portions of the Denver Formation and the in the Offpost Study Area, On the basis of an evaluation of the distribution of contaminant plumes contaminants from RMA to the the UFS is considered the principal migration route for groundwater Although low-level Offpost Study Area, although some contaminant are present in the CFS. CFS, this formation has contamination may be present in isolated portions of the Denver Formation low productivity as a groundwater resource.
1-4 Harding Lawson Associates P21905 402010 0711121495 R02 2.0 SITE HISTORY AND ENFORCEMENT ACTIVMES
2.1 Operational History
Congress established RMA in 1942. The United States acquired land included within the boundaries of the Arsenal for chemical weapons manufacturing, constructed a base, and corn m enced Army weapons production and ancillary activities in 1943. From 1945 to 1950, RMA distilled available stocks of mustard, demilitarized several million rounds of mustard-filled shells and incendiarv munitions, and test-fired mortar rounds filled with smoke and high explosives. Also, many different types of obsolete World War II ordnance were destroyed by detonation or burning.
After the conclusion of World War H, selected surplus facilities were leased to nongoverrunent entities as warehouses and for the manufacture of agricultural chemicals. Colorado Fuel and lron
(CF&I) leased facilities at RMA in 1946. Julius Hyman & Company (Hyman) first leased facilities in
1947 and succeeded to the CF&I leasehold interest, with some modifications and additions in 1949.
Shell Oil Companv (Shell) acquired a majority interest in Hyman in 1952 and operated the plant as the Julius H%-man Company until 1954. when the operation became the Shell Chemical Company -
Den%-er Plant.
R.\L-% %,6-as selected as the site for construction0f d facility to produce Sarin, a nerve agent. The facility was completed in 1953. with the manufac4uring operation continuing until 1957 and the murutions-filling operations continuing un.1 lat- 1969 From 1970 until 1984, the primary operation at RNL-% was the disposal of chemical warfar- nijt-,ria! Disposal practices included incinerating TX anticrop agent and mustard agent explos;%,-(, compon-nlS drid destroying Sarin and related munitions casings by caustic neutralization.
Chemicals were introduced to the RNUN envuonment primarily by the burial or surface disposal of solid wastes, discharge of wastewater to basins. and leakage of wastewater and industrial fluid from
chemical and sanitary sewer systems. Munitions were destroyed and disposed in trenches.
'21905 402010 Harding Lawson Associates 2-1 0711121495 R02 Site History and Enforcement Activities
in the South Wastewater generated by the U.S. Department of the Army (Army) and private industry and holding basins Plants and North Plants areas was discharged to a series of unlined evaporation the history of (Basins A, B, C, D, and E) and to asphalt-lined Basin F at various times throughout
RMA operations. The locations of these source areas are shown in Figure 2.1.
include (1) former The primary areas that have contributed to groundwater contamination at RMA areas, (4) the manufacturing facilities, (2) former waste storage basins, (3) solid waste disposal (6) the motor pool area. chemical sewer system, (5) locations within the rail classification yard, and
2.2 Previous Investigations conducted at RMA, From 1975 to the present, numerous groundwater monitoring programs have been (EPA) has also both onpost and offpost, by the Army. The U.S. Environmental Protection Agency programs conducted several offpost investigations. The Army designed and implemented monitoring to monitor regional groundwater and surface-water quality. The Army also designed and implemented the boundary system monitoring program to support the operation of the boundary groundwater containment systems.
2.2.1 U.S. Environmental Protection Agency Study Area
Several orgaruc chemicals were detected in South Adams County Water and Sanitation District
(SACIVSD) wells in 1981. as part of a random national survey of drinking water systems conducted
bv EPA. Additional sampling in 1982 and 1985 confirmed these initial findings. As a result, EPA
began a remedial investigatiori,'feasibility stud%- (RLTS I of an area west of RNIA and south of the
Offpost Studv Area (Figure 1.1).
RNIA was suspected as one of the possible sources of contaminants in the EPA study area because of
RNiA*s historical waste disposal practices. To mitigate the groundwater contamination problem, the
Army and EPA built a water-supply system for SACWSD. Further investigation by EPA's Field
Investigation Team indicated that source areas in addition to RMA contributed to groundwater
2-2 Harding Lawson Associates '21905 402010 0711121495 R02 Sift History and Enforcement Activities
wells installed on the contamination detected within the EPA study area. Groundwater monitoring source of Chemical Sales Company (CSQ property have since identified CSC as a significant EPA and the Army have groundwater contamination in the EPA study area. Recent investigations by 9, Township 3S, . detected the presence of a trichloroethene plume entering RMA at Section Western Tier Report, the Range 67W along the southern boundary of RMA, as described in the and the CSC ROD Stapleton Airport Environmental Assessment (Camp Dresser & McKee, Inc., 1993),
(EPA, 1991a, 1991b, 1992). (Ebasco Services, Inc., 1988),
2.2.2 U.S. Department of the Army Investigation a regional hydro- Because chemicals were detected in the Offpost Study Area, the Army initiated of samples from more geologic surveillance program requiring the quarterly coliection and analysis carried out under than 100 onpost and offpost wells and surface-water stations. The program was to ensure compliance the direction of the RMA Contamination Control Program, established in 1974 evaluate the with federal and state environmental laws. The objectives of the program were to (1) contaminant nature and extent of contamination and (2) develop response actions to control migration migration. Potential and actual contaminant sources were assessed, and contaminant pathways -,vere evaluated.
From 1975 to the present, numerous groundwater morutoring programs have been conducted at RMA.
The Army designed and implemented the 360 DegeeMorutoring Program to monitor regional groundwater and surface water. The Army designed and implemented a boundary system monitoring program to support the operation of the boundary groundwater containment systems. Studies
conducted at RMA to assess groundwater and suffdC+--Wdter conditions are discussed below.
The RMA Offpost Contamination Assessment Report (CAR) (Environmental Science and Engineering,
Inc. [ESE], 1987a) incorporated data from several studies to define the concentrations and distri-
bution of offpost contamination north and northwest of RMA. The scope of the CAR investigation
2-3 '21905 402010 Harding Lawson Associates 0711121495 R02 Site History and Enforcement Activities
a comprehensive set of multimedia was intended to address critical data gaps required to evaluate exposure pathways.
the mid-1980s during the Con- The potential for contamination of private wells was investigated in Phases I and 11 studies addressed the sumptive Use (Cq Studies, Phases 1, 11, and M. The CU an inventory of privately-owned Offpost Study Area. In the CU Phase III study, the Army conducted on the south, East 96th Avenue on the drinking water wells in an area bound by East 80th Avenue east. The objectives of the CU Phase III north, the South Platte River on the west, and RMA on the
study were as follows:
Offpost Study Area. Locate all shallow domestic wells (less than 100 feet) in the
Sample a representative number of the located wells.
Assess the groundwater quality of the shallow alluvial aquifer.
a long-term multimedia The Army developed the Comprehensive Monitoring Program (CMP), of response actions, in the mid- monitoring program designed to provide data to facilitate evaluation and is continuing as the Groundwater 1980s. Sample collection under the CMP commenced in 1987
Momtoring Program (GMP). The primary objectives of the An RI was initiated in 1985 by the Armv in the Offpost Study Area.
Offpost RI were as follows: flow and surface- Collect additional data to refine the current understanding of groundwater water patterns and the nature and extent of contaminants offpost of RMA. in various environ- Evaluate the potential for chemical migration to the Offpost Study Area biota. mental media, such as groundwater. surface water. sediment, air, and
before evaluation Following completion of the RI, it was apparent that additional data were needed was initiated in 1988 to and selection of a remedial alternative could occur. Therefore, a second RI (plants and animals). collect additional data for groundwater, surface water, soil, sediment, and biota Investigation, Final The results of the second RI are reported in the Offpost Operable Unit Remedial
Addendum (HLA, 1992b).
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2.3 Boundary Containment Systems
Concurrent with and as a result of the EPA and Army investigations, the Army constructed three boundary containment systems (the North Boundary Containment System [NBCS], the Northwest at the north, Boundary Containment System [NVVBCS), and the Irondale Containment System [ICSI of RMA northwestern, and western boundaries of RMA, respectively) to minimize offpost discharge in Figure 1.1. All chemicals via groundwater. The locations of these containment systems are shown to three svstems currently intercept and treat contaminated groundwater and recharge treated water the UTS.
2.3.1 North Boundary Containment System of The NBCS is just south of the RMA north boundary in Sections 23 and 24. The NBCS consists
(1) a svstem of extraction wells that remove contaminated groundwater from the UFS, (2) a soil-
bentorute barrier that impedes migration of contaminated groundwater to the Offpost Study Area,
(3) a carbon-adsorption treatment system that removes organic contaminan from extracted
Sroundwatpr. and (4) a system of recharge wells and trenches that return treated groundwater to the
UTS.
Tii, Nli(--S ; ii-,I svst-ým became operational in 1978. The pilot system was expanded approximately
1400 1-4 1 in. %%-st and 3840 feet to the east in 1981 during the second phase of construction.
Sý.-veral imp: -%-*:*.--:jI5 have been made to the NBCS smce 1981: ten recharge trenches were added to
I I!i-- svs1em and became operational in December 1988, and five additional recharge
i. : if) the east end oi th,ý systeni in 1 q90. Currentlv, the soil-bentonite barrier is
I-' I i \ttiidtelv 3 feet widt:. and varies in depth from 20 feet at the western end to
more thin 40 1-1 ilong the eastern extension. The barrier is anchored in the Deaver Formation.
Review of groundwater contaminant distribution patterns indicates that the NBCS is having a
significant effect on the distribution of organic compounds in the Offpost Study Area. Monitoring
program data indicate that contaminant concentrations doomgradient of the NBCS are decreasing.
'21905 402010 Harding Lawson Associates 2-5 0711121495 R02 Site History and Enforcement Activities
from the extracted Activated carbon is being used to effectively remove the organic contaminants concentrations are groundwater to meet contain- ent system remediation goals. Organic contaminant generally below certified reporting limits (CRLs) in system effluent
2.3.2 Northwest Boundary Containment System of Section 22. The NVVBCS is along the northwest boundary of RMA in the southeast quarter in 1984. The NWBCS Constructon of the NWBCS began in 1983, and the system became operational approximately 1600 feet in originally consisted of (1) 15 extraction wells, (2) a soil-bentonite-barrier recharge wells. length, (3) a carbon adsorption treatment system, and (4) a system of 21 downgradient and The carbon adsorption system was designed to intercept and remove dibromochloropropane onpost. other organic compounds from a plume of contaminated groundwater originating 1988. . pass was observed at the southwest and northeast ends of the NV%rBCS in An Contaminant by 1990, the interim resonse action (IRA) to improve the NWBCS was initiated in 1989. in April ER.A and NWBCS Improvements IRA was divided into two phases: NMCS Short-term Improvements IRA, which was NWBCS Long-term Improvements IRA. Under the NWBCS Short-term Improvements
completed in 1991, the existing slurry wall was extended 665 feet to the northeast to prevent of the contaminant bypass. and two additional extraction wells were added at the northeast end were extraction well alignment. Three additional extraction wells and four additional recharge wells
installed in Section 27. southwest of the NWBCS in August 1991. The NWBCS Long-term Improve-
ments IRA is being used to assess the NV%BCS and its short-term improvements by reviewing
groundwater monitoring data.
2.3.3 Irondale Containment System
The ICS, which became operational in 1981. is at the southern end of the RMA northwest boundary
within Section 33 and consists of (1) a hvdraulic control system of extraction and recharge wells, and
(2) a carbon adsorption treatment system. The ICS was originally developed to intercept the
migration of dib romochloropro pane (DBCP) at the RNIA boundary. There have been no downgradient
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of the area downgradient of detections of DBCP after the first two years of operation. The majority downgradient area are the ICS is contained within the EPA study area, although portions of the operation of the ICS was within the confines of the Offpost Study Area. Therefore, the design and operation of the ICS, as not included in the evaluation of alternatives; however, the continued an integral part of the required, for onpost contaminants consistent with the Irondale 1R.A remains in the Irondale Army's offpost contaminant reduction program to meet onpost cleanup goals defined 35.2 and 35.4 of the IRA. Cessation of operation of the ICS will be in accordance with paragraphs
FFA and paragraph 20 of the Conceptual Remedy Agreement.
2.4 Interim Response Actions Environmental As part of the Army's compliance with the requirements of the Comprehensive FFA, the Army has Response, Compensation, and Liability Act (CERCLA), and as described in the onpost and offpost instituted several IRAs that have been performed concurrently with the ongoing actions taken RI programs. IRAs, which are designed to be compatible with the final remedy, are measures to contain, before the signing of the Record of Decision (ROD) and are expedited remedial been implemented remove. or treat wastes before the final remedv is selected. Numerous IRAs have some to mitigate contamination both onpost and offpost. As indicated in the previous sections, IRA is portions of the boundary containment systems have been constructed as IR.As. The Offpost discussed in the following section.
2.4.1 Offpost Interim Response Action of The Offpost IRA addresses groundwater contaminant migration north of RMA and downgradient
the NBCS along two primary contamindnt pathwai-s. defined by the First Creek and northern
paleocharinels.
Evaluation and selection of the collection and treatment system components that comprise IRA A,
referred to as the Offpost Groundwater Intercept and Treatment System, began in 1988. The Offpost for Groundwater Intercept and Treatment System Decision Document (HLA, 1989) presents the basis
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alluvial groundwater in the First Creek system placement to address remediation of contamination in and extract contaminated and northern paleoch-annels. The system was designed to intercept recharge treated water to the UFS. groundwater from the UFS, treat the groundwater for organics, and System began in November 1991 Construction of the Offpost Groundwater Intercept and Treatment through a network of and was completed in June 1993. Groundwater extraction is accomplished are treated using activated extraction wells. The organic contaminants in extracted groundwater using a combination of carbon adsorption, and the treated water is then recharged to the UFS recharge wells and trenches.
to be flexible and to be The Offpost Groundwater Intercept and Treatment System was designed
compatible with the final remedy, consistent with EPA guidance and the FFA.
2.5 History of CERCLA Enforcement Activilties F was added in 1989. As Most of RMA was added to the National Priorities List (NPL) in 1987; Basin A facility is subject to such. RMA is subject to compliance w4th CERCLA (also known as Superfimd). substances from the compli.iric,- woh CERCLA when a release or a threat of a release of hazardous cases, the potentially facilit%- ha% and when response costs have been incurred. In some for the response responsibl. parti-- 1PRPs) either cannot respond or cannot be found, so funding were identified as como,s irr.n. It. 6:, %.rnment fund called Superfund. At RMA, the Army and Shell
PRPs an.] v- Itin 1m; the cleanup.
Company On Ft-h.jar% I viAh. -i proposed Consent Decree was filed in the case of U.S. v. Shefl Oil
the Consent Decree was filed ,.%-ith th. t ' S D;V71 ". Court in Denver. Colorado. A modified version of 12, 1993. on June 7. 1 IM8, T1w Consent Decree was entered by the U.S. District Court on February the On Februan- 17. 1989. an FFA was executed by the Army. Shell, EPA, the U.S. Department of and Interior (DOI), the U.S. Department of Justice (DOJ). and the U.S. Agency for Toxic Substances
Disease Registry (ATSDR). The FFA sets forth the procedures to be followed by the Organizations
(i.e., signatories to the FFA) to cooperate in the assessment, selection, and implementation of
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response actions resulting from the release or threat of release of contaminants from Rlý.IA. The FFA designates the Army as the lead agency.
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process to fulfill Community participation opportunities were provided during the remedy selection the requirements of CERCLA Sections 113(k)(2)(B)(i-v) and 117.
and Proposed Plan for The RI, RI Addendum, Endangerment Assessment/Feasibility Study (EA/FS), were made available the Offpost OU were released to the public on March 21, 1993. The documents Record Document to the public in the Administrative Record (located at the joint Administrative in an information Facilitv at the west entrance to RMA at 72nd Avenue and Quebec Street), the Adams County, Aurora, repository maintained at the EPA Docket Room in Region VM, and at The notice of Commerce City, Denver, Lakewood, Montbel.lo, and Thornton Public Libraries. and Rocky Mountain News availabilitv for these four documents was published in the Denver Post
newspapers.
members had An expanded Community Relations outreach was implemented to ensure community Community outreach started the opportunity to comment on the Proposed Plan for the Offpost CU. Proposed Plan in lanuarv 1993 wýith the announcement that all documents supporting an impending citizens was werp available for review in local libraries. A direct mailing to more than 1200 local
made.
that a public In March 1993, a press release was made and a legal notice was published announcing Colorado, meetingwas scheduled for April 28. 1993. at Dupont Elementary School, Commerce City, documents to address the Proposed Plan. A separate letter was sent to citizens informing them of the Proposed availabilitv in the libraries. The letter also included a brief fact sheet summarizing the received Plan. Originally. the ý)Iblic meetingwas scheduled for April 21, 1993, at RMA. The Army
requests to hold the meeting on a different day and offpost. Because of these factors and Earth Day
events in Denver for April 21, the meeting was moved to April 28, 1993.
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provide local media information on the A Media Day was held the day of the public meeting to attended. Army's proposal. Both print and video media representatives
was expanded to include display Knowing the importance of the public meeting, the Announcement metropolitan area. This was in advertising in 12 local and weekly newspapers in the Denver event. addition to the normal press release and Media Day
concerning the official comment period, the As a result of comments received at the public meeting announcing that the comment period was Army published a legal notice and sent letters to citizens
extended to June 21, 1993.
from the Army, EPA, and the State of Colorado At the April 28, 1993, public meeting, representatives the remedial alternatives under consideration. answered questions regarding issues at the site and comment period are included in the Responsive- Responses to comments received during the public A). This decision document presents the ness Summary, which is part of this ROD (Appendix in Adams County, Colorado, chosen in accordance selected remedial action for the RMA Offpost OU and Reauthorization Act (SARA), and with CERCL.,%, as amended by the Supe-fund Amendments the National Oil and Hazardous Substances with the NEPA. and, to the extent practicable. with this site is based on the Administrative Record PoUution Contingency Plan (NCP). The decision for
for the Offpost OU.
local health departments, special Additionaliv. settlement discussions involving municipalities. until April 1, 1995, to discuss the final districts, and citizen groups were held from Idle 1q94 Final ROD (December 7, 1993) was revised remedies for both Onpost and Offpost OUs. The Draft local communities, and the Parties. taking into account comments presented by the public.
'21905 402010 3-2 Harding Lawson Associates 0711121495 R02 4.0 SCOPE AND ROLE OF THE OFFPOST OPERABLE UNIT
treat, and recharge groundwater at Three RMA boundary containment systems currently intercept, systems, along with the physical the RMA north, northwest, and west boundaries. These boundary Therefore, the FFA divided the work boundaries of RMIA, provide a logical dehneation between OUs.
into the following two OUs:
Area (within RM.A Onpost OU: Media requiring remediation within the Onpost Study boundaries) Area (outside RMA Offpost OU: Media requiring remediation within the Offpost Study boundaries)
and northwest of RMA. As The Offpost OU addresses contamination in the groundwater north in the UFS poses the principal discussed in Section 6.0 of this ROD, groundwater contamination exposure to groundwater. potential threat to human health because of the risks from possible the acceptable risk range Although health risks are possible, the estimated risk levels are within groundwater contaminant concen- established bv EPA. The purpose of the remedv is to (1) reduce reduce the potential human tiations. (2) reduce risk to human health and the environment, and (3)
exposure to contaminated LJFS grouMwater.
are not exposed to contami- The potential risks to ecological receptors were also evaluated. Wildlife exposure. Wildlife nated groundwater: therefore. there are no risks to wildlife from the groundwater groundwater exposures to soil and surface water and pot--ntial livesiock exposure to contaminated shown to be were evaluated. However, the potential risLs a%snriat--d with these exposures were of potential negligible. Therefore. the selected remedy for the Offpost OU addresses the reduction
human exposure to contaminated UFS groundwater.
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soil, surface water, Six media were evaluated in the RI for the Offpost Study Area: groundwater, respect to (1) the sediment, air, and biota. Each medium was evaluated in the Offpost EA with associated risk to nature and extent of contamination and (2) potential exposure pathways and Study Area is humans and the environment. A map delineating the boundaries of the Offpost the Offpost Operable Unit included as Figure 1.1. The site characteristics are more fully described in Investigation, Remedial Investigation Report (ESE, 1988a) and the Offpost Operable Unit Remedial
Final Addend= (HLA, 1992b).
5.1 Sources of Contamination primarily by the As described in Section 2.1, chemicals were introduced to the RMA environment leakage of waste- burial or surface disposal of solid wastes, discharge of wastewater to basins, and migrated to the water and industrial fluid from chemical and sanitary sewer systems. Chemicals and airborne Offpost Study Area primarily by shallow (i.e., shallow or unconfined) groundwater been 'controlled by pathways. Contaminant transport in the shallow or unconfined groundwater has (completed as construction of the boundary containment systems and improvements to these systems with IRAs). Offpost Studv Area surface water was contaminated primarily by the natural interaction airborne offpost groundwater. Offpost Study Area surface soil was contaminated by the deposition of
contaminants, non-RNIA-related agricultural application of pesticides, and irrigation practices. Air Agricultural sources of pesticides are discussed in the Final Offpost RI Addendum (HIA, 1992b).
morutoring data indicate that the air pathway does not contribute to human exposure.
5.2 Nature of Contamination and Several chemicals of concern (COCs) are present in offpost groundwater, surface water, sediment,
soil (see Tables 6.1 through 6.4). COCs include organochlorine pesticides (OCPs), halogenated
aliphatics, aromatic hydrocarbons. diisopropylmethyl phosphonate (DINT), sulfur-containing organic
chemicals, arsenic, and dissolved salts.
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environmental media. OCPs The COCs exhibit great variability in their mobility and persistence in with soil and sediment are less mobile than the other COCs and more persistent, tending to associate mobile in groundwater, and and to biomagnify in the food chain. Most of the remaining COCs are properties of the COCs tend to the aromatics and aliphatics are volatile in surface water. The fate were detected in groundwater, but determme their distribution in the Offpost Study Area. All COCs are virtually the only COCs the more mobile chemicals are more widely distributed. The OCPs The volatile compounds detected at concentrations above background levels in soil and sediment. and, in fact, were rarely were not significantly elevated above background levels in surface water detected.
S.3 Contamination Migration Pathways pathways in the Offpost The RI programs have shown that there are three groundwater migration to as the northern Study Area. These migration pathways (shown in Figure 5.1) are referred paralleling First paleochannel, due north of the RMA north boundary; the First Creek paleochannel, northwest of Creek to the northwest from the RNIA north boundary; and the northwest paleochannel, compose the North the RNIA northwest boundary. The northern and First Creek paleochannels Group. These two Plume Group. and the northwest paleochannel composes the Northwest Plume Area. The alluvial plume groups encompass an area of approximately 590 acres in the Offpost Study
flow system transports most of the contamination in paleochannels characterized by coarser discharges to sediment. Some of the groundwater traveling through the First Creek paleochannel
FLrst Creek, probably seasonally, resulting in transfer of contaminants to First Creek.
is Figure 5.1 also presents the offpost surface-water ieatures. The primary surface-water pathway into First Creek. wtuch flows northwest from the northern RMA boundary. First Creek empties parallels O'Brian Canal, which flows northeast and empties into Barr Lake. Burlington Ditch, which is located O'Brian Canal, also flows into Barr Lake. The majority of the surface-water contamination
in First Creek, with some contamination in O'Brian Canal do%rnstream of the confluence with First
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with RMA-related Creek and Burlington Ditch. Barr Lake has not been shown to be contaminated chemicals greater than naturally occurring background levels.
and surface water, prevailing In addition to the contaminant migration pathways of groundwater provides a potential contami- winds transport onpost surface soil to offpost locations, and sediment nant source for aquatic species.
5.4 E)ctent of Contamination Offpost OU: groundwater, Varying levels of contamination exist in the following five media in the More detailed surface water, stream-bottom sediment, surface and subsurface soil, and biota. showing concentration discussions of the offpost contaminant concentrations, along with figures RI Addendum (HLA, distributions are found in Sections 3.0, 4.0, 5.0, and 6.0 of the Final Offpost
1992b).
5.4.1 Groundwater used in the Table 6.1 presents the groundwater COCs and the exposure point concentrations in the Offpost Endangerment Assessment. The most widespread RMA-related groundwater COC from the west Studv Area is DIMP, which is present in the UFS at varyin concentrations in a band boundaries end of the NIVBCS to the east end of the NBCS. and from the RMA north and northwest are chdoro- to the South Platte River. The other primary contaminants present in the offpost UFS dieldrin, form, chlorobenzene, trichloroethene, tetrachloroethene, dibromochloropropane (DBCP),
endrin. dicyclopentadiene (DCPD), arseruc, chloride. fluoride and sulfate.
paleo- The fughest concentrations of DIMP observed in the past three years are in the First Creek
channel. Concentrations of DIMP are lower in the northern paleochannel and lower still in the
northwestern paleochannel. The maximum concentrations of DIMP in the Offpost Study Area have and decreased by approximately 50 percent over the past 10 years. The NBCS is currently operating
has been operated in the past to remove multiple contaminants. DIMP concentrations are being
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of the reduced to less than 8 ppb. Cut-off of groundwater contaminants at. the NBCS and recharge as treated groundwater has resulted in the observed decrease in DMEP concentrations specifically, well as the other contaminants found offpost.
Canal. The highest contaminant levels downgradient from the NBCS occur upgradient of the O'Brian have been Certain volatile compounds such as chlorobenzene, chloroform, trichloroethene, and DBCP exist in detected at low concentrations downgradient from the canals, but well-defined plumes do not this area and these detections may be anomalous. Semivolatile organic compounds such as dieldrin of and other OCPs are present almost exclusively upgradient of the canals. Maximum concentrations and the OCPs (i.e., aldrin, isodrin, chlordane, 2,2-bis[p-chlorophenyl]-1,1-dichloroethene[DDE], paleochannel 2.2-bis[p-chlorophenyl]-1,1,1-trichloroethane[DDII) generally occur in the First Creek observed witlun 500 to 1000 feet of the NBCS. Only sporadic and isolated occurrences of OCPs are northwest of the RMA northwestern boundary.
DMEP, Contaminants found downgradient from the NWBCS are primarily chlorobenzene, chloroform, and dieldrin. The highest concentrations of chloroform occur downgradient of the RMA boundary.
Detections of chlorobenzene near the NVVBCS maybe anomalous. In 1989, semivolatile compounds such as dieldrin and possibly DINIP appeared to have bypassed the NWBCS at the northeast and southwest ends. Subsequently, the N%VBCS IRA was initiated that included improvements and operational changes to correct the bypass. Recent modifications to the NBCS and NWBCS, in addition to the remedial action selected in this ROD. are expected to further reduce contaminant
levels dowrigradient of the RMA boundaries.
S.4.2 Surface Water
Table 6.2 presents the surface water COCs and the exposure point concentrations used in the
Endangerment Assessment. The principal organic compounds identified in Offpost Study Area
surface-water samples are DIMP and dieldrin. In general, the highest concentrations of the organic
and inorganic analytes were detected in First Creek. DIMP concentrations in First Creek were highest
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groundwater discharges to First Creek. in the area 100 to 200 feet upstream of O'Brian Canal where
Canal upstream of the confluenceurith First DIMP was not detected in Burlington Ditch or O'Brian
of 20 samples collected from 1985 to 1990 and Creek. DIMP was detected in Barr Lake in only one
the same time. This one detection is anoma- was not detected in the duphcate sample collected at
Barr Lake. lous and not considered representative of conditions at
Creek near the northern RMA boundary. The highest concentrations of arsenic were detected in First
the onpost sewage treatment plant. These detections are likely associated with discharge from
Canal upstream of the confluence Mercury and arsenic were detected in surface water in O'Brian
other than RNIA probably exist. %,ýith First Creek, suggesting that sources of these contaminants
Ditch may originate from the Some contaminants identified in O'Brian Canal and Burlington
diversion of treated sewage effluent from Denver.
5.4.3 Stream-bottom Sediments
concentrations used in the Endanger- Table 6.3 presents the sediment COCs and the exposure point
in stream-bottom sediment in the meni Assessment. The most commo-n-1v detected contaminants
concentration of dieldrin was Offpost Study Area were dieldrin, arsenic, and mercury. The highest
Additional contaminants found in First Creek immediately north of the northern RMA boundary.
confluence with First Creek, were detected in O'Brian Canal and Burlington Ditch upstream of the
exist such as diversion of suggesting that sources of these contaminants other than RMA probably
treated sewage effluent from Denver.
5.4.4 Surface and Subsurface Soil
used in the Endangerment Table 6.4 presents the soil COCs and the exposure point concentrations
RI Addendum investi- Assessment. Approximately 100 soil samples were collected as part of the
most frequently detected gation and were analyzed for OCPs, arsenic. and mercury. Dieldrin was the
located approxi- OCP (in approximately 90 percent of the samples) with a maximum concentration
Associates S-5 '21905 402010 Harding Lawson 0711121495 R02 Summary of Site Characteristics
DDE, aldrin, endrin, and mately 100 to 200 feet north of the northern RMA boundary. DDT, chlordane were detected less frequently.
correlate with the dominant wind The distribution of OCPs in Offpost Study Area soil appears to are observed in patterns at RMA. The greatest number and highest contaminant concentrations consistent with the prevalent samples collected immediately north of the northern RMA boundary, OCPs observed between the wind direction of south to north. Isolated elevated concentrations of residential and/or commercial northern RMA boundary and O'Brian Canal may be the result of local high concentrations of use of pesticides and not related to migration from RMA. Anomalously of RMA. These dieldrin, DDE, and DDT were also detected approximately 1.5 miles northwest because the area is currently detections are considered to be agricultural-related and not RMA-related - and has historically been a farming community.
soil suggests that the The uneven distribution of arsenic and mercury in Offpost Study Area surface
occurrence of these inorganic contaminants is not related to RMA activities.
5.4.5 Biota the potential impacts The RI Addendum biota monitoring program provided additional data to assess biota samples on plants and arumals in the Offpost Study Area. During the RI Addendum study, Dieldrin, the were analyzed for aldrin, dieldrin. endrin. DDE. DDT. DBCP. arsenic, and mercury. in contaminant most often found in Offpost Study Area biota (36 percent of samples), was detected and cattle, chicken, fish, earthworm. deer mouse. prairie dog. and pheasant samples. Arsenic only mercury were detected less frequently (19 and 14 percent. respectively). DDE was detected Offpost once, and aldrin, endrin, DDT, and DBCP were not detected in any biota samples from the those Studv Area. Contaminants identified in the Offpost Study Area biota survey are similar to
found onpost, although the concentrations detected in the Offpost Study Area biota are considerably
lower than concentrations detected in the onpost biota.
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for endangered species such as the bald The Offpost Study Area is known to contain suitable habitat activities. Contaminants eagle. A nesting pair of eagles was identified during offpost assessment collected in 1988 from a nest at Barr (mercury, dieldrin, and DDE) were detected in a bald eagle egg of these contaminants Lake. According to the U.S. Fish and Wildlife Service, the concentrations States. were tvpical of bald eagle egg contamination throughout the United
Exposure S.S Potential Routes of Human and Environmental local city and county planning Based on the current land uses in the Offpost Study Area, a review of three primary land uses and zoning ordinances, and consultation with local planning authorities, uses are urban residential, rural were considered in estimating the risks to human health. These land pathways considered for the residential, and commercial and industrial. The exposure routes and
Offpost Study Area include the following:
Ingestion of groundwater
Ingestion of soil
Ingestion of sediment
Ingestion of vegetables
Ingestion of dairy products
Ingestion of eggs
Ingestion of meat
Ingestion of surface water
Inhalation of volatile chemicals in groundwater
Inhalation of dust
Dermal contact with soil
Dermal contact with sediment
Dermal contact with surface water
Dermal contact with groundwater
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risks corresponding to The risks estimated in the EA and siimmarized in this section are baseline of the selected current conditions and are, therefore, pre-remediation risk estimates. Implementation maximum cumulative remedy presented (Section 9.0) will lower the potential risks. The estimated
10-4 3 in 10,000 people) on the potential cancer risk to humans in the Offpost Study Area is 3 x (or Final EA (Volume M, basis of the reasonable maximum exposure (RNE) risks presented in the level is within the accept- Section 4.0, and Volume IV, Appendix G). This estimated potential risk dated February 21, able risk range established by EPA (1 x 10-'*to 5 x 101; letter from EPA to Army of risk. Actual cancer 1992). A cancer risk estimate of 3 in 10,000 indicates an upperbound estimate carcinogenic risks are risks are likelv to be below this level and may be as low as zero. These chance of an usuallv termed "excess lifetime cancer risks," which means there is an increased in excess of the individual developing cancer over 70 years of exposure to the carcinogenic chemicals Society is normal cancer rate. The background cancer rate determined by the American Cancer about 1 in 3.
by EPA, Because the Offpost Study Area cumulative risk is less than the upper risk level established that remedial action in the Offpost Study Area is not requLred. The Army, nevertheless, recognizes no action in several site-specific factors suggest that remediation of the groundwater is preferable to risk of the Offpost OU. These site-specific factors are: (1) groundwater contributes a maximum contaminant levels 2 x 10'. or approximately 75 percent of the 101di carcinogenic risk, (2) maximum for Groundwater (NICLs), maximum contaminant level goals (MCI.Gs). and Colorado Basic Standards children (CBSGs) are exceeded for some groundwater contaminants, and (3) hazard indices (1-11s) for 2, exceed 1.0 in Zones 2. 3, and 4. Although the estimated child hazard indices exceed 1.0 in Zones
3, and 4, the bulk of the HI value is contributed through an assumed domestic use of alluvial
groundwater, which is not presently occurring in the Offpost OU. Treatment of groundwater to the
containment svstem remediation goals will reduce (1) the total estimate risk to less than 1 x 10' and
6-1 '21905 402010 Harding Lawson Associates 0711121495 R02 summary of Sit* Risks
3, and 4. Soil, surface water, and toward I x 10" and (2) the lUs to less than 1.0 in Zones 2,
risk attributable to these media. Air was not sediment do not require remecliation because of the low
data and initial risk screening. identified as a medium of concern on the basis of air monitoring
exposure criteria for the Protection of biota was evaluated through development of ecological
indicated that the potential for protection of species potentially at rislr- The ecological assessment
adverse ecological effects is minimal.
6.1 Human Health Risks
in four steps: identification of COCs, Human health risks in the Offpost Study Area were calculated
It should be noted that many of exposure assessment, toxicity assessment, and risk characterization.
not represent existing exposures. the exposures evaluated do not currently exist and therefore do
6.1.1 Identification of Chemicals of Concern
air, and biota data collected A data set consisting of groundwater, surface water, sediment, soil,
concern to human health and betwPen 1985 dnd 1991 was used to evaluate wtuch chemicals were of
since 1985 was the envirnnniýnt. A trend of declining contaminant concentrations in groundwater
boundary of RMA and noted in pomions of the Offpost Study Area. particularly near the north
This trend is due to the operation and improvement of the boundary
the most recent groundwater systoriv. iii i ii.st-iral attenuation processes. Considering this trend, only
exposure point concentrations. data h -- . Ir. n. 11IM" through 1991) were used to estimate groundwater
from analytical methods Daia for ili. 1 1. 1 nW fid were also considered. and only the data resulting
statistically with sensitive vir-ug', ti, d-tect low concentrations were used. Data were also compared
Guidance for background concentrations consistent with EPA guidance presented in Risk Assessment
and the Method Superfund (EPA. 1989a). Statistical procedures included the Wilcoxon rank sum test
of Proportions. These procedures are discussed in Section 1.2 of the Final Offpost EA/FS (HIA,
1992a).
6.2 Harding Lawson Associat" '21905 402010 0711121495 R02 Summary of Site Risks
at locations of The primary criterion for identifying COCs was that the chemical concentrations than expected maximum concentration (i.e., near the RMA borders) must be significantly greater By concentrations found at background locations (i.e., no RMA-related contamination present). to applying statistical methods, Offpost Study Area contaminant concentrations were compared Offpost Study background concentrations at reference locations. If statistical analysis indicated that presence of Area concentrations were significantly higher than the background concentrations, the chemical was the chemical in the Offpost Study Area was considered to be RMA-related and the 6.1 designated as a COC. This procedure was followed for each environmental medium. Tables The through 6.4 list the COCs for groundwater, surface water, sediment, and soil, respectively. exposure point concentration associated with each COC is also shown in the tables.
biota RI were To select COCs for biota (plants and animals), analytical data obtained from the onpost
compared to background chemical concentrations available in the scientific literature. This may procedure was less precise but nonetheless indicated that two chemicals (dieldrin and arsenic)
be elevated. although in low concentrations. in the tissues of animals located in the Offpost OU.
6.1.2 Exposure Assessment
6.1.2.1 Ottpost Study Area Exposure Assessment Zones
The Offpost Study Area is a large. heterogeneousarea with a variety of characteristics that can affect
exposure levels. Specifically. distinct zc;nes of the Offpost Study Area exhibit different exposure
concentrations of COCs in groundwater. surfacp and surface soil, including hot spots where
contaminant levels are higher than the average for the entire Offpost Study Area. In addition,
population density, land use. and water use varies throughout the Offpost Study Area. Therefore, to
avoid diluting or averaging contaminant concentrations over the entire Offpost Study Area, the
Offpost Study Area was subdivided into six zones (Figure 6.1) with different exposure conditions.
The primary factor used to define the exposure zones was the pattern of COC concentrations in
6-3 '21905 402010 Harding Lawson Associates 0711121495 R02 Summary of S1 to Risks
within each zone, are groundwater. The six zones, and the land use and populations evaluated
described below.
soil. Rural Zone 1 is an area with relatively low levels of COCs in groundwater and surface milk, meat, and eggs, is residential land use, which includes consumption of homegrown vegetables,
the current and potential future population characteristic.
of COCs in surface soil, Zone 2 is an area of relatively high levels of COCs in groundwater, low levels identical to Zone 1, and no permanent surface-water features. A rural residential land-use scenario,
was evaluated.
COCs in ground- Zones 3 and 4 are similar. Zone 3 is an area of relatively high levels of pesticide in water. surface water, and surface soil. Zone 4 is an area of relatively high levels of COCs Zones 3 and 4 groundwater and surface water. but relatively low levels of COCs in surface soil. Both at least until have recently been purchased by Shell Dil Company and are expected to be unoccupied road for the completion of offpost remediation. Plans for improvement of 96th Avenue as an access land use in new Denver International Airport may -esult in predominantly commercial and industrial was these zones. An urban residential land use for Zones 3 and 4 is considered possible and current land selected for evaluation because this land use would result in higher exposures than the local use. Urban land use assumes that exposure to meat. dairy, and eggs would not occur, but that
planting and consumption of vegetables are possible.
Zone 5 is an area with moderate levels of COCs in groundwater and relatively low levels of COCs in
surface soil. A commercial and industrial land use for Zone 5 was evaluated. Zone 5 is zoned for
industrial use over the majority of its area. is currently developed for industrial use, and is projected
as industrial land use for the future.
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groundwater and -relatively low levels of COCs in Zone 6 is an area with moderate levels of COCs in
in Zone 6, a rural residential land use was surface soil. Because farm residences currently exist
in Zones 1 and 2. evaluated that is identical to the land use (rural residential)
Points 6.1.2.2 Ottpost Study Area Potential Exposure
Study Area. The most significant routes of There are several potential exposure points iia the Offpost
in areas with the highest groundwater exposure have already been mitigated by exposure controls
in Zones 3 and 4). Exposure to COCs in surface COC concentrations (e.g., the UFS is no longer used
the area near the intersection of soil has also been mitigated by relocating residents from are highest. Additionally, the 96th Avenue and Peoria Street where soil contaminant concentrations
approximately 160 acres located in Armv and Shell Oil Company have agreed to till and revegetate
portion of Section 13 in accordance with the southeast portion of Section 14 and the southwest
Figure 9.1). Shell Oil Company and the U.S. Paragraph 22 of the Conceptual Remedy Agreement (see
falls within EPA's established acceptable Army believe that existing soil risk in the revegetated area
Shell Oil company and the U.S. Army risk range and that remediation is not necessary. However, aigree to the revegetation program as part of the remedy.
in First Creek than other surface-water Concentrations of surface-water contaminants were lugher
point for nonhuman receptors and a bodies during 1986 through 1990, creating a potential exposure
Creek does not support a recreational direct-contact human pathway associated with wading. First
to bioaccumulated residues in fish fisherv: Barr Lake is the most likelY point of human exposure
exception of a single DIMP detection tissue. Because COCs are not elevated in Barr Lake. with the
of contaminated fish was not that was not verified in duplicate or later sdmpling events, consumption
evaluated.
Harding Lawson Associates 6-S '21905 402010 0711121495 R02 summary of -Site Risks
6.1.2.3 Potential Exposure Pathways and Routes and mechanism of release, (2) a An exposure pathway consists of four elements: (1) a source contaminated medium, and (4) an transport medium, (3) a point of potential contact with the
exposure route, such as ingestion, at the contact point.
exposure pathways identified in the The Site Conceptual Model (Figure 6-2) presents the potential which exposure routes were Offpost Study Area. The Site Conceptual Model also indicates land use and the presence or absence quantitatively evaluated for risk. Because of the variations in to all zones. Table 6.5 of surface water in the six zones, not all exposure routes are applicable the exposure routes quantified in summarizes the exposure zones by land-use category and identifies
each zone.
Inhalation Route the release of On the basis of risk screening evaluations conducted according to EPA guidance, showering, dishwashing, volatile chemicals from groundwater used in the home for all purposes (e.g., by the inhalation route. laundry, toilets) was determined to result in potentially significant exposures Other Therefore. inhalation of volatile chemicals resulting from domestic use was quantified. and inhalation potential sources of exposure, such as the inhalation of contaminated dust particles, very minor of vapors resulting from volatilization from underlying groundwater, were found to be
contributors to the overall exposure potential.
Dermal Route Dermal Dermal contact with surface soil is likely and was quantified for all potential land uses. of Barr Lake is contact with sediment in First Creek was quantified. Dermal contact with sediment
not feasible. considering the depth of the water and the prohibition of swimming.
with Dermal contact with surface water in First Creek was quantified. However, dermal contact
canal water is expected to be unlikely and. in the worst case. infrequent; therefore, dermal contact
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in Barr Lake; therefore, the was not quantified for the canals. Direct contact recreation is prohibited dermal contact pathway was not quantified for Barr Lake-
intake during Dermal contact with groundwater used domestically is likely. However, dermal
ingestion of groundwater. showering is approximately 0.15 percent of the intake resulting from
higher than from dermal Potential exposures from direct ingestion and inhalation will be much
use was not quantified. EPA guidance contact. Therefore, the dermal intake resulting from domestic
evaluation if other pathways have (EPA, 1989a) allows for certain pathways to be eliminated from much higher exposure.
Ingestion Route
uses; therefore, this pathway was Incidental ingestion of surface soil is likely under all potential land
in association with wading or quantified. Incidental ingestion of First Greek sediment is possible
quantified. recreational activities; therefore, this pathway was also
COCs from (1) surface Cattle and other livestock raised for human consumption may bioaccumulate
contaminated surface soil or water or igroundwater used for watering livestock, (2) forage grown in
and (3) direct ingestion of soil while grazing. irrigated by contaminated surface water or groundwater,
species for development of a Tfus pathway was quantified, using cattle as the representative
in dieldrin contamination of biodccumulat ion model. Additionallv. b i oaccumu lat ion resulting
chicken eggs was quantified in the EA.
because of uptake of COCs from Vegetable crops grown for human consumption may contain COCs
irrigation. Ingestion of vegetable contaminated surface soil and surface water or groundwater for
crops was quantified.
pathway was quantified. It Although ingestion of the shallow groundwater is unlikely, this exposure
might occur even has been conservativelv assumed that ingestion of untreated alluvial groundwater
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contain- though there is insufficient water in portions of the UFS contaminated above groundwater ment system remediation goals to supply a municipal water system.
6.1.2.4 Estimation of Cbemical Intake (Section 6.1.2.1) Analytical data from each media within each of the six exposure assessment zones an RME was identified. Exposure point concentrations were selected such that they represent 95 percent concentration. The RME exposure point concentrations were calculated as the upper in each media confidence limit on the arithmetic mean of the data. The RNE values for the COCs with are presented in Tables 6.1 through 6.4. Exposure point concentrations were combined by each exposuxe standard EPA intake assumptions and variables to estimate the intake of each COC
route.
vegetables), several To estimate the exposure point concentration for food products (e.g., meat, eggs, or water and the models were used to estimate the plant and animal uptake of a chemical from soil and parti- resultant concentration in the edible portion of the plant or animal. All of the uptake also tiorung coefficients were selected so that the resultant COC concentration in the food would is represent an RME value. A complete discussion of the plant and animal chemical uptake models
provided in the Offpost EA/FS.
6.1.3 Toxicity Assessment Cancer The toxicity of chemicals is evaluated in terms of carcinogenic and noncarcinogenic effects.
slope factors and reference doses are used to evaluate potential risks posed by the exposure to
carcinogeruc and noncarcinogeruc chemicals. respectively.
EPA-established slope factors for inhalation and ingestion exposures to COCs are presented in
Table 6.6. The slope factor for a given compound is multiplied by the estimated intake to obtain the
carcinogenic risk estimate. The individual risks from each compound in a particular exposure
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risk for each pathway pathway are then summed to obtain an estimate of the overall carcinogenic and for all pathways combined.
exposures are presented in The reference doses (RfDs) used in the EA for inhalation and ingestion
to obtain its hazard Table 6.6. The estimated intake is divided by the RfD for a given compound
by their target organ. For quotient (HQ). For each exposure pathway, chemicals were segregated
to obtain a hazard index (HI) each target organ group, the HQs for each chemical were then summed
the HI exceed 1.0, there may for each pathway and for all pathways comb4ned. When the HQ and/or be concern for potential noncarci.nogenic health effects.
6.1.4 Risk Characteriza-lion
intakes, the slope factors Follo,ýving the estimation of exposure point concentrations and chemical
for noncarcinogenic effects. The and RfDs are used to estimate carcinogenic risks and the potential
folio-wing sections discuss the results of this procedure.
6.1.4.1 Carcinogenic Risks
existing exposures Table 6.7 summarizes the estimated current carcinogenic risks correspondingto
range from 1 X 104 to by exposure assessment zone and exposure route. The total carcinogenic risks
5, and 7 x 10-' (7 in 3 x 10' (1 to 3 in 10.000) in Zones 1 through 4. 3 x 10-5 (3 in 100,000) in Zone
assessment zones are 100.000) in Zone 6. The total carcinogeruc risks for each of the six exposure
Zones 3 and 4 are within the acceptable risk range established by EPA. The hypothetical risks in
and there are no h.ighly conservative in that they are based on an urban residential land-use scenario
a portion of Zone 1 humans currently living in Zones 3 and 4. Additionally. the risks estimated for
groundwater for and Zone 2 are not current risks, because resvients in these areas do not use UFS
residents in domestic use. Because there are no current residents in Zones 3 and 4, and the current
use in Zone 5 have water supplies other than shdlIOW wells. the estimated risks from residential
these zones are conservative because they do not represent existing exposures.
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to carcinogenic Groundwater usage (either domestic arid/or agricultural) is the primary contributor zone. This indicates the risk, accounting for 45 to 99 percent of the total risk estimated for each to chemicals in soil are less major role of the groundwater-related exposure pathways. Risks related and sediment exposure than 1 in 10,000 (1 x 10'), and the risks resulting from the surface-water of the groundwater pathways are less than 1 in 100,000 (1 x 10"). Because of the importance potential offpost pathway, the remediation of groundwater will have the greatest effect in reducing risks.
chloroform, and Dieldrin contributes the most to the total carcinogenic risk, followed by arsenic, dieldrin concentrations atrazine. All of the estimated risks from dieldrin are conservative in that the reduction in were considered to be constant throughout the exposure period (30 years). The natural the total carcinogenic dieldrin concentrations over time was not considered. Additionally, not all of of clieldrin in soil risks for each zone are attributable to RMA activities. Background concentrations risk in attributable to agricultural practices may contribute up to 50 percent of the total carcinogenic Naturally some zones based on a background concentration for dieldrin of approximately 8 mg/kg. 100,000 occurring arsenic in groundwater may be responsible for a risk of approximately 4 in
(4 x 10"). based on a background concentration of arsenic in groundwater of approximately 3 Jig./l.
6.1.4.2 Honcarcinogenic Effects intake to As presented in Section 6.1.3, HIs are derived by comparing the estimated daily chemical because the estimated acceptable intake. Acute. or short-term. effects were evaluated for children be the children would have the highest chemical intake per body weight and would be expected to health most sensitive to the chemical. The EA concluded that there is a low potential for adverse 2, 3, effects in children from hypothetical short-term exposures to dieldrin in groundwater in Zones is the and 4. The HI exceeds 1 in Zones 2, 3. and 4. with a maximum HI of 4 in Zone 3. Dieldrin
primary contributor to the HI.
Harding Lawson Associates '21905 402010 6-10 0711121495 R02 Summary of Site Risks
both children and adults. The risk characteri- HIs were also estimated for long-term exposures for
of ingestion of Duvip in groundwater in zation presented in the EA found that, with the exception
in an M greater than 1. 111s were also Zone 4, no single chemical or exposure pathway resulted
of toxic action. For children, both calculated on the basis of target organ effects and the mechanism
to exceed an III of 1. For liver liver and central nervous system (CNS) toxicants were found
maximum HI of 2 in Zone 2, predominately toxicants, the HI exceeds 1 in Zones 2, 3, and 4, with a
FU for CNS effects exceeds 1 in Zones 2 attxibutable to inhalation and ingestion of chloroform. The
to the estimation of CNS and 4, with a maximum 1-H of 3.7 in Zone 4. The primary contributors
and ingestion of vegetable crops effects are DIMP and manganese. Direct ingestion of groundwater
for DIMP and manganese. irrigated .%rith groundwater are the two primary exposure pathways
the adult IUs segregated by Adult future Hls are all less than the child HIs. Table 6.8 summarizes
is 1.3 in Zone 3. The HI for CNS target organ. When segregated for liver toxicants, the highest FIl
to an HI of 2.4 in Zone 4. effects also eXCI-'eLIS 1.0, where DIMP is the major contributor
6.2 Estimation of Potential Ecological Effects
6.2.1 Method
potential adverse effects An Oft jr,-t St - i% Ar,-,i ecological risk assessment was performed to evaluate
exposure to chemicals migrating to t -nf- -rix i: dMi nonhuman receptors as a result of potential
are terrestrial and from otil - .%I-ý tirr-s The two natural ecosvs1ems occurring in the Offpost OU
the potential exposure dquat r: f i.:m pr.-sents the ecological site conceptual model and presents
and pathwa,.. % The chemic,-Is selected for evaluation of potential effects on the terrestrial
suxface soil, and aouatic r, w.-r-- limited to RMA-related chemicals found in surface water,
receptors (e.g., sediment. Ch-littý:.jls identified in ground%vaterwere used to evaluate agricultural
watering. The crops, livestock) because of the potential for exposure through irrigation and livestock
endrin, DDE, DDT, chemicals evaluated for potential ecological effects were aldrin, arsenic, dieldrin,
and mercury.
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and biomagaification. Direct exposure is Two methods of exposure were evaluated: direct exposure (e.g., ingestion of surface water or soil, a result of contact with the original source of the chemical surface water). Biomagnification occurs ingestion of groundwater, or fish swimming in contaminated progression up the food chain. Over when the tissue concentrations of a chemical increase with a level detrimental to the organism's time, the concentrations of chemicals in tissues may reach
health.
analogous to the evaluation of human The evaluation of ecological effects via direct exposure is daily intake of a receptor to the effects. Direct toxicity was evaluated by comparing the estimated reference values are similar to human estimated toxicity reference value for a receptor. The toxicity values were animal- and chemical-specific RfDs in their derivation and use. These toxicity reference Quality Criteria values established to values, or, in the case of aquatic life, federal Ambient Water
protect aquatic life.
tissue concentrations resulting To evaluate the potential effects of biomagrafication. the estimated known to be without deleterious from biomagnification were compared to residue concentrations effects of biomagnification. effects. On1v the top indicator species were selected to evaluate the
These species were the bald eagle, great blue heron, and mallard duck.
screening levels, In coordination with the U.S, Fish and Wildlife Service. it was agreed that would meet the requirements of developed to ensure compliance with enforceable remediation levels, the Bald and Golden Eagle the federal Endangered Species Act, the Migratory BLrd Treaty Act, and OU. These levels are Protection Act. These screening levels were not exceeded m the Offpos.t Study in presented in the Final Offpost Operable Unit Endangerment Assessment/Feasibility of Concern Table 3.3.3-1 (Toxicity Reference Values for Avian and Terrestrial Vertebrate Species AJlowable Tissue Identified at Rocky Mountain Arsenal) of Volume 11 and Table H5-1 (Maximum Appendix H in Concentration [M.ATC] Values for the Offpost EA Ecological Assessment) of
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in the future, enforceable Volume rV. If the screening levels are exceeded or effects are observed Species Act, the remediation levels will be developed consistent with CERCLA, the Endangered
Migratory Bird Treaty Act, and the Bald and Golden Eagle Protection Act.
assessment is presented Potential effects on wetlands and critical habitats were also evaluated. This Wildlife Service in Appendix B of the Final Offpost EA/FS (H1A, 1992a). The U.S. Fish and along First Creek (USFWS) National Wetlands Office identified approximately 300 acres of wetlands of the Offpost from the north boundary of RMA to O'Brian Canal. Potential effects of construction during excavation of Groundwater Intercept and Treatment System included temporary dewatering recharge trenches and pipelines near First Creek.
6.2.2 Results water concen- Underwater aquatic life was evaluated on the basis of direct toxicity by comparing appeared to trations to aquatic reference concentrations. Chlordane, dieldrin, fluoride, and DDT First Creek present a potential for an adverse effect to aquatic life in First Creek. However, because adverse effects to is dr%- much of the year and does not support a stable and ongoing fish population, and First Creek, acu a! ic Iife are expected to be minimal. Because of interaction between groundwater
the NBCS will also reduce remedial actions taken to reduce the concentration of COCs north of concentrations of COCs in First Creek.
of the direct Agricultural life was evaluated in Zones 1. 2. and 6 (rural residential). The results
or to toxicitv P%*aluation indicated no potentidl ai%-,-rs-- impdcts to poultry from soil contaminants
cattle from ingestion of contaminated soil arid groundwater.
aquatic food webs, The ecological risk assessment concluded that for animals in the terrestrial and
have there is mirumal potential for adverse effects- However, the Armv and Shell Oil Company
of Section 14 agreed to till and revegetate approximately 160 acres located in the southeast portion
Army and the south,.%,est portion of Section 13 (see Figure 9.1). Shell Oil Company and the U.S.
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EPA's established acceptable risk believe that existing soil risk in the revegetated area falls within
Oil Company and the U.S. Army agree range and that remediation is not necessary. However, Shell to the revegetation program as part of the remedy.
System was coordinated with Construction of the Offpost Groundwater Intercept and Treatment
habitat. Although the wetlands area has USFWS to minimize the potential impacts on wetlands and
area, the wetlands still exist, dewatering been slightly altered because of construction of roads in the
is equal to the amount of extracted is no longer occurring, and the amount of recharged groundwater
area. groundwater. thereby maintaining the stability of the wetlands
6.3 Conclusion
this site, if not addressed by imple- Actual or threatened releases of hazardous substances from
a potential threat to public health, menting the response action selected in this ROD, may present
welfare. or the environment.
'21905 402010 6-14 Harding Lawson Associates 0711121495 R02 7.0 DESCRIPTION OF GROUNDWATER REMEDIATION ALTERNATIVES
the Offpost OU. The first An FS was conducted to develop and evaluate remedial alternatives for action and correspondingly task performed during the FS was to identify media that require remedial calculated in the EA were require development and evaluation of remedial alternatives. Risks and other guidance. The Army compared to acceptable risk levels established by EPA in the NCP regarding the use of the has closely followed EPA guidance and the National Contingency Plan (NCP) is necessary. Guidance states that if the cumulative 10-4 risk threshold to assess whether remediation warranted unless certain cancer risk to an individual is less than 10', remedial action may not be
riskrangemust be site-specific conditions exist. If remedial action is warranted, then the 10-4 to 10-' states that the upper achieved, with an initial preference foi the 10' end. EPA guidance further risk range can boundary of the risk range is not an absolute at I x 10', but rather, the acceptable x 10', which is within the extend to 5 x 10-4. The cumulative offpost cancer risk is a maximum of 3
acceptable risk range.
to the NCP, states In explaining the use of the point of departure. the EPA. in the preamble
risks at the more The use of 10' expresses EPA's preference for remedial actions that result in that the final remedial protective end of the risk range, but does not reflect a presumption action should attain such a risk level (55 FR 8718).
the Army's goal of The operation of the Offpost Groundwater Intercopi and Treatment System reflects including further reducing the potential risks toward -,he 10' levpl. Using conservative assumptions, risk in the several exposure pathways that do nct currenIly exist. the maximum cumulative cancer established by Offpost OU was estimated to be 3 in 10,000. wfuch is within the acceptable risk range
EPA.
risk level, Although the maximum offpost cumulative carcinogenic risk is below the acceptable
remediation of groundwater is preferable to no action for the following reasons:
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Water Standards maximum Groundwater concentrations exceed National primary Drinking OU. contaminant levels (MCLs) and CBSGs; in some areas of the Offpost and contributes a maximum risk of 2 in Groundwater is the greatest contributor to cancer risk risk in zones 2, 3, and 4. 10,000 (or approximately 75 percent) to the cumulative that lEs calculated for ground- Evaluation of potential noncarcinogenic health effects indicate slightly greater than 1.0. water contarninant concentrations in zones 2, 3, and 4 are
cancer risks less than 1 in 10,000 in Soil, surface water, sediment, and air contribute maximum do not require remediation because of the zones 1 through 6. Soil, surface water, sediment, and air alternatives were developed and low risks contributed by these media to the total risk. Remedial OU North and Northwest Plunie evaluated to address contaminated groundwater in the Offpost the Army and Shell Oil Groups. Additionally, as part of the Conceptual Remedy Agreement, acres located in the southeast portion Company have agreed to till and revegetate approximately 160 of Section 14 and southwest portion of Section 13.
groundwater containment Remedial alternatives for groundwater were developed by (1) establishing exceedances of containment svstem remediation goals (2) identifying the areas of groundwater process options into svstem remediation goals and (3) assembling combinations of remedial
remedial alternatives.
on the basis of Contai=ent system remediation goals (Tabie 7.1.. 7.2. and 7.3 were established (ARARs), health-based criteria chemical-specific applicable or relevant and appropriate requirements 121 of CERCIA. ARA.Rs (HBQ. exposure factors, and the statutory rwiuaf-ments stated in Section contaminants with promulgated were used as groundwater containment system remediation goals for were used for standards. and HBC based on a risk of I x 10' caiCUldied using RME assumptions to the point of carcinogensurithout ARARs. A risk level of 1 x 10 " was selected to correspond system departure as defined in the NCP. The promulgated standards adopted as containment addition, containment remediation goals for Offpost OU groundwater include MCLs and CBSGs. In were adjusted svstem remediation goals for several contaminants with promulgated standards
402010 7-2 Harding Lawson Associatos '21905 0711121495 R02 Description of Groundwater Rernediation Alternatives
goals. For some downward to reduce risk corresponding to the containment system remediation limit (PQL) are higher than analytes, the certified reporting limit (CRL) or the practical quarititation the lower practical limit for the containment system remediation goal- The CRL and PQL represent quantitation.
goals developed for the site will Attainment of the groundwater containment system remediation
1 x 10-4 toward the 1 x 10' level. reduce the estimated total hypothetical cancer risks to less than in groundwater at all locations, Because the total cancer risk assumes that all chemicals are present the estimated risk reduction and since groundwater contamination is variable throughout the OU, remediation goals developed for may be greater. Attainment of the groundwater containment system all target organ groups and the site will also reduce HIs discussed in Section 6.1.4.2 to below 1.0 for may increase the estimated risk receptors. Again, variability in contaminants present in groundwater assessment reduction from that estimated by extrapolating directly from the risk
by comparing ground- Groundwater requiring remediation in the Offpost Study Area was identified contamination. water containment svstem remediation goals to the areal extent of groundwater arsenic, chloro- Groundwater containment system remediation goals are exceeded for the carcinogens containment system form. DBCP. tetrachloroethviene. LrichJoroethylene. and dieldrin. Groundwater dicyclopentadiene, and remediation goals are also exceeded for the noncarcinogens chlorobenzene, goals (and thus the DIMP. The area of groundwater exceeding containment system remediation
Offpost 012.) encompasses approximately 5qO acres of the Offpost Study Area.
The models Groundwater alternatives were developed and evaluated using two groundwater models. Plume Groups. simulated groundwater flow and contaminant transport for the North and Northwest for Groundwater modeling was used for the following purposes: developing conceptual designs future sizing and locating groundwater extraction, recharge, and treatment systems; estimating the contaminant transport, evaluating the relative merits of remediation alternatives; and estimating
Associates 7-3 '21905 301040 Harding Lawson 0711121495 R02 Description of Groundwater Romodlation Alternatives
the approximate nature and time required to clean up the contaminated groundwater. Because of be interpreted as an accurate inherent uncertainties of the models, none of the model results should are estimates. Accordingly, prediction of future conditions. The predicted remediation time frames effectiveness of the ground- estimated remediation time frames were only used to assess the relative water alternatives.
cost, Remedial alternatives were initially screened on the basis of effectiveness, implementability, then evaluated on the and attainment of ARARs. The alternatives passing the initial screening were the NCP requires that basis of nine criteria required by the NCP. In addition to remedial alternatives, primarily as a a No Action alternative be considered at every site. The No Action alternative serves
point of comparison for other alternatives.
for the Northwest A total of six alternatives for the North Plume Group and four remedial alternatives FS, Plume Group were developed for analysis. Following the initial screening analysis in the two remedial four remedial alternatives for the North Plume Group (N-1, N-2, N-4, and N-5) and during the alternatives for the Northwest Plume Group (NW-1 and NW-2) remained for evaluation alternative detailed analysis of alternatives. These alternatives are described below with the original
numbering sequence from the FS report.
7.1 Common Elements of Alternatives
All of the alternatives developed included the foliowing elements:
Groundwater and surface-water monitoring: Samples will be collected periodically from groundwater monitoring wells and surface-water locations throughout the Offpost Study Area and analyzed to assess changes in groundwater and surface-water quality during and after remediation.
0 Site review: In accordance with CERCLA. a site review will be conducted at least every five years until groundwater contai=ent system remediation goals are achieved to assure that human health and the environment are protected during and after remediation. The site review will use monitoring program data to assess whether additional remedial action would be warranted.
Harding Lawson Associates '21905 402010 7-4 0711121495 R02 Description of Groundwater Rernediation Alternatives
the following activities: Except for the No Action alternative, each alternative also includes below: Exposure control/provision of alternate water supply as described billion (ppb) As of the date of the Onpost ROD, and based on a .392 parts per monitoring results detection limit, the U.S. Army %%,illuse the last available quarterly to determine the DRAP plume footprint. pay for the As part of the Onpost ROD, the U.S. Army and Shell Oil Company will well extension of, and hook-up to, the current distribution system for all existing owners within the DRAP plume footprint referenced above. the date of Existing domestic well owners outside of the DROP plume footprint as of eight ppb or the On-post ROD where it is later determined that levels of DRVIP are Army and greater (or other relevant CBSG at the time) will be hooked up at the U.S. a deep Shell Oil Company's expense to the SACWSD distribution system or provided well or other permanent solution. relevant CBSG at For new domestic wells with levels of eight ppb or greater (or other U.S. Army and the time), the Offpost ROD institutional controls will provide that the a deep Shell Oil Company will pay for hook-up to the distribution system or provided well or other permanent solution. ground- Any user of a domestic well within the Offpost Operable Unit that contains greater of water contaminants derived from RMA at concentrations that exceed the 1 will be the remediation goals in Tables 7.1 through 7.3 or the ARARs in Table 10. cooking and provided an alternative water supply. Bottled water will be provided for alter- drinking until a permanent alternative water supply is provided. Permanent well or native water supplies could include installation of a deep uncontaminated applies to connection to a municipal potable water-supply system. This commitment in both users of existing domestic wells and users of wells that are lawfully drilled the future. for, As part of the Onpost ROD, the U.S. Army and Shell Oil Company agree to pay of and provide or arrange for the provision of 4,000 acre feet of water, the details which .vill be worked out between the U.S. Armv, Shell Oil Company, and SACWSD. If such water is not available. the U.S. ,Vmv and Shell Oil Company will provide payment of an agreed upon amount of money in lieu of water. remediation Use of institutional controls to prevent the future use of groundwater exceeding pals. Institutional controls are reflected in Appendix B. NVVBCS Continued operation of tEo existing boundary containment systems - The NBCS and that offpost will continue to operate and improvements will be made, as necessary, to assure ICS groundwater containment system remediation goals are not exceeded. In addition, the Irondale will continue to operate, as required. for onpost contaminants consistent with the the IRA. These containment svstems will be operated to the requirements of Section 2.7 of FFA. the Conceptual Remedy Agreement, and the Onpost ROD, when it is signed. Cessation may occur as provided in Sections 35.3 and 35.4 of the FFA and paragraph 20 of the Conceptual Remedy Agreement. Currently, approximately 125 million gallons per year are treated at the NBCS, 450 million gallons per year are treated at the N`VVBCS, and 45 minion gallons per vear are treated at the ICS.
-7-5 '21905 301040 Harding Lawson Associates 0711121495 R02 Description of Groundwater Rem*diatlon Alternatives
- Wells that could be Closure of poorly constructed wells within the Offpost Study Area Aquifer wiU be closed using acting as migration pathways for contaminant in the Arapahoe Appendix C - Well Closure approved methods. The pertinent criteria are presented in Criteria.
North Plume Group 7.2 Identification of Groundwater AlternatWes: North Plume Group are described Alternatives developed for remediation. of groundwater in the North Plume Group and identifies below. Table 7.4 presents the alternatives corresponding to the remediation time frames, process options, numbers of wells and trenches, flow rates, estimated treatment facility location, and process residuals generated.
7.2.1 - Alternative N-1: No Action Alternative N-1 would Under Alternative N-1, the operation of the NBCS would be discontinued. within the North Plume Group. therefore not provide for active remediation of affected groundwater contaminant concentrations within Ceasing operation of the NBCS -would likely cause an increase in and attenuation, would be the the North Plume Group. Natural fate processes. including degradation groundwater within the North onh, mechanisms that would reduce contaminant concentrations in following: Plume Group. The major components of Alternative N-1 include the
Long-term groundwater and surface-water monitoring
Site re,.-iews
implemented. The A long-term groundwater and surface-water morutonng program would be and surface-water purpose of the monitoring program is to assess changing UFS and CFS aquifer a site review would be conditions during and after remedial action. As parl of Alternative N-1, goals are achieved. conducted at least every five years until containment system remediation
to $6,102,000. This The total present worth cost estimate for Alternative N-1 ranges from $4,061,000 groundwater and includes long-term operation and maintenance costs for performing site reviews,
surface-water monitoring, and regulatory oversite activities.
Lawson Associates '21905 402010 7-6 Harding 0711121495 R02 Description of Groundwater Remediation Alternatives
the North Boundary 7.2.2 Aftemative N-2: Continued Operation of Containment System With Improvements as Necessary
groundwater approaching the north Alternative N-2 would provide for active remediation of affected at the NBCS. The major compo- boundary of RMA through continued remediation of groundwater nents of Alternative N-2 are as follows:
Continued operation of the NBCS
Improvements to the NBCS as necessary
Long-term groundwater and surface-water monitoring
Site reviews 7.1 Exposure control/provision of alternate water supply as described in Section
Well closure in conformance with criteria listed in Appendix C, pages C-1 and C-2
Institutional controls as described in Appendix B
recharge approxi- Under Alternative N-2, the NBCS would continue to contain, extract, treat, and to the NBCS if it matelv 125 million gallons of groundwater per year. Improvements would be made was determined that the system was allowing groundwater containing COCs at concentrations exceed ing off post groundwater containment system remediation goals to mi atefromRMAtothe
North Plume Group.
As part of Alternative N-2, an alternative water supply would be provided to any user of a domestic and well in accordance with the provisions described in Section 7.1. The long-term groundwater
surface -xvat er monitoring and site review remedial components under Alternative N-2 would be
identical to those proposed under Alternative N-1.
The total present worth cost estimate for Alternative N-2 ranges from $30,600,000 to $32,500,000.
This incudes long-term operation and maintenance costs for the NBCS and the cost of long-term
groundwater monitoring and site review components included under Alternative N-1.
'21905 301040 Harding Lawson Associates 7-7 0711121495 R02 Description of Groundwater Rem*diation Alternatives
Intercept and Treatment System 7.2.3 Alternative N-4: Offpost Groundwater the Offpost Groundwater Intercept Under Alternative N-4, the NBCS would continue to operate, and remove, treat, and recharge and Treatment System would be constructed and operated to contain, Creek and northern groundwater exceeding containment system remediation goals in the First the Offpost Groundwater paleochannels downgradient of the NBCS. Detailed information concerning Document for the Intercept and Treatment System is presented in the Final Implementation Arsenal (HLA, 1991). The Groundwater Intercept and Treatment System North of Rocky Mountain since early 1993. The Offpost Groundwater Intercept and Treatment System has been in operation
major components of Alternative N-4 are as follows:
the First Creek Removal of contaminated UFS groundwater north of the RMA boundary in System and northern paleoch-annels using Offpost Groundwater Intercept and Treatment groundwater extraction wells adsorption Treatment of organic contaminants in extracted groundwater using carbon and Recharge of treated groundwater to the UFS using Offpost Groundwater Intercept Treatment System recharge wells and trenches
Continued operation of the NBOS System as Improvements to the NBCS and Offpost Groundwater Intercept and Treatment necessary
Long-term groundwater and surface-water monitoring
Site reviews
Exposure control/provision of alternate water supply as described in Section 7.1
Well closure in conformance with cnteria listed in Appendix C, pages C-1 and C-2
Institutional controls as described in Appendix B
Alternative N-4 would remediate UFS groundwater in the First Creek and northern paleochannels
that is contaminated with organic COCs at concentrations exceeding groundwater containment
system remediation goals.
Harding Lawson Associates '21905 402010 7-8 0711121495 R02 Description of Groundwater Rernediation Alternatives
and Treatment System to Extraction wells would be used in the Offpost Groundwater Intercept be conveyed to the treatment remove contaminated groundwater. Extracted groundwater would facility via double-contained polyvinyl chloride (PVC) pipelines.
of five extraction wells and six Based on the results of the groundwater modeling, the configuration contaminants axially in the First recharge trenches shown in Figure 7.1 would capture and remove of the extraction Creek paleochannel. The recharge trenches would be placed both downgradient In this manner, the recharge wells and along the outer boundaries of the First Creek paleochannel. Creek paleochannel and water trenches would provide both lateral hydraulic containment of the First be attained using a transverse flushang for enhancing the removal of contaminants. Capture would of the extraction wells in the svstem of 12 extraction and 24 recharge wells directly downgradient and Treatment System would northern paleochannel system. The Offpost Groundwater Intercept (gpm). Construction of contain, extract, treat, and recharge approximately 480 gallons per minute this system began in November 1991 and was completed in June 1993.
would be conveyed by Extracted groundwater from both the First Creek and northern paleochannels Area that was pipeline to a central carbon adsorption treatment facility on land in the Offpost Study technology that is previously purchased by Shell. Activated carbon adsorption is a well-developed and offgas ,widelv used in removing organic contaminants from liquid hazardous waste streams (GAC) by flowing airstreams. The waste stream comes in contact with granular activated carbon inorganic through one or more packed-bed reactors. Organic chemicals and, to some degree,
chemicals. are adsorbed onto the internal pores of the carbon granules by surface-attractive and is most phenomena. Activated carbon removes many nondegradable organic compounds
effective for nonpolar, slightly soluble compounds.
techno- Carbon adsorption is readily implementable. Carbon adsorption is a demonstrated, proven
logy documented to be effective at the NIVBCS, NBCS, and ICS. Activated carbon treatment would
7-9 '21905 301040 Harding Lawson Associates 0711121495 R02 Description of Groundwater Remediation Alternatives
organic contarninan before achieve groundwater containment system remediation goals for discharge via the recharge systems.
in Alternative N-4 as part of the An intensive short-term monitoring component would be included consist of monitoring long-term monitoring program. The intensive short-term program would of the altern- approximately 60 wells in a network that would be finalized through implementation with Offpost Ground- ative. Two years of data would be collected during the period commencing is necessary to evaluate water Intercept and Treatment System operations start-up. Such a program System and the performance of the NBCS and the Offpost Groundwater Intercept and Treatment time to achieve would provide an increased understanding of contaminant transport, an estimated improvements to the groundwater containment system remediation goals, and to determine whether
Offpost Groundwater Intercept and Treatment System are warranted.
to $63,100,000. The total present worth cost estimate for Alternative N-4 ranges from $56,500,000 operation, This includes the capital and long-term operation and maintenance cost for construction, This cost and performance monitoring of the Offpost Groundwater Intercept and Treatment System. monitoring, site estimate also includes the continued operation of the NBCS, long-term groundwater review, and exposure control components of Alternative N-2.
and 7.2.4 Alternative N-5: Expansion of the Oftpost Groundwater Intercept Treatment System
Similar to Alternative N-4. this alternative would remediate the First Creek paleochannel and the northern paleochannel groundwater do%-.-ngradient of the NBCS. Based on the results of under groundwater modeling. the configuration of extraction wells and recharge systems proposed
Alternative N-5 would place additional extraction wells in locations where the hmiting hydrogeologic
and contaminant characteristics are controlling remediation time frames. Two additional extraction
wells and four recharge trenches would be installed in the area of relatively slower groundwater
velocity and high dieldrin concentrations in the First Creek paleochannel. One additional extraction
7-10 Harding Lawson Associates '21905 402010 0711121495 R02 Description of Groundwater Rernodiation Alternatives
an area of low hydraulic conductivity in the well and two recharge trenches would be installed in are as follows: northern paleochannel. The major components of Alternative N-5
boundary in the First Creek Removal of contaminated UFS groundwater north of the RMA Intercept and Treatment System and northern paleochannels, using Offpost Groundwater groundwater extraction wells System extraction and Expansion of the Offpost Groundwater Intercept and Treatment recharge systems
Treatment of extracted groundwater using carbon adsorption wells and trenches Recharge of treated groundwater to the UFS, using recharge
Continued operation of the NBCS
Improvements to the NBCS as necessary
Long-term groundwater and surface-water monitoring
Site reviews in Section 7.1 Exposure control/provision of alternate water supply as described pages C-1 and C-2 Well closure in conformance with criteria listed in Appendix C,
Institutional controls as described in Appendix B
System is shown in Figure 7.2. The expansvin (,f thf, Offpost Groundwater Intercept and Treatment additional), and the The thro-- d I lit iorwl extraction wells would each pump 30 gpm (90 gpm N-5 would extract and treat additional ir. !,.-% would recharge the same volume. Thus, Alternative remedial components under a total (,I in ý.t,nipared to 480 gpm for Alternative N-4. Other N-4. Alternat i%- % %,-,,ulJbe identical to those proposed under Alternative
$56,200,000 to $63,000,000. The total %vorthcost estimate for Alternative N-5 ranges from systems to the This includ--s th- rdpital and operation and maintenance costs of the expansion of Alternative N-4. Offpost Groundwater Intercept and Treatment Svstem and the cost components
Lawson Associates 7-11 '21905 301040 Harding 0711121495 R02 Description of Groundwater Rernediation Alternatives
Northwest Plume Group 7.3 Identification of Groundwater Altematives: Plume Group. The following subsections identify the alternatives developed for the Northwest Group and identifies Table 7.4 preseýts the alternatives corresponding to the Northwest Plume time frames, process options, numbers of wells and trenches, flow rate, estimated remediation
treatment facility location, and process residuals generated.
7.3.1 Altemative N-1: No Action Alternative NW-1 Under Alternative NW-1, the operation of the NWBCS would be discontinued. Northwest Plume Group. would not provide for active remediation of affected groundwater within the concentrations Ceasing operation of the NWBCS would likely cause an increase in contaminant and attenuation, within the Northwest Plume Group. Natural fate processes, including degradation within would be the only mechanisms that would reduce contaminant concentrations in groundwater as follows: the Northwest Plume Group. The major components of Alternative NW-1 are
Long-term groundwater monitoring
Site reviews
the monitor- A long-termpgroundwater monitoring program would be implemented. The purpose of
ing program would be to assess changing UFS and CIFS aquifer conditions during and after remedial
action. As part of Alterriative NW-1. a site review would be conducted at least every five years until
contairizient svstem remediation goals are achieved.
This The total present worth cost estimate for Allernative NW-1 ranges from $608,000 to $1,260,000.
includes long-term operation and maintenance costs for performing site reviews, groundwater
morutoring. and regulatory oversite activities.
7.12 Harding Lawson Associates '21905 402010 0711121495 R02 Description of Groundwater Rernediation Alternatives
of the Northwest Boundary 7.3.2 Altemative NW-2: Continued Operation Containment System With Improvements as Necessary
affected groundwater approaching the Alternative NW-2 would provide for active remediation of groundwater at the NWBCS. The northwest boundary of RMA through continued remediation of major components of Alternative NW-2 are as follows:
Continued operation of the NWBCS
Improvements to the NWBCS as necessary
Long-term groundwater monitoring
Site reviews in Section 7.1 Exposure control/provision of alternate water supply as described pages C-1 and C-2 Well closure in conformance %rith criteria listed in Appendix C,
Institutional controls as described in Appendix B
extract, treat, and recharge Under Alternative NW-2. the NT"rBCS would continue to contain, would be made to the approximately 450 million gallons of groundwater per year. Improvements containing COCs at N'1%7'BCS if it was determined that the system was allowing groundwater remediation goals to migrate from concentrations exceeding offpost groundwater containment svstern
RINUN to the Northwest Plume Group.
to any user of a As pail of Alternative NRV-2, an alternatwe water supply would be provided containment domestic well that contains groundwater contaminants at concentrations exceeding would be identical to svstem remediation goals . Other retneital : zipont-nis under Alternative NW-2
those proposed under Alternative N%V-1.
to $13,100,000. The total present worth cost estimate for Allerndli%-e NIV-2 ranges from $12,400,000 long-term This includes long-term operation and maintenance costs for the MVBCS and the
groundwater monitoring, site reviews. and exposure control components of Alternative NW-1.
Associates 7-13 '21905 301040 Harding Lawson 0711121495 R02 8.0 COMPARATIVE ANALYSIS OF ALTERNATIVES
and The remedial alternatives were evaluated with respect to nine threshold, primary balancing, modifying criteria as required by the NCP. The criteria are as follows:
Threshold Criteria
Overall protection of human health and the environment
Compliance with ARARs
PrimaryBalancing Criteria
Long-term effectiveness and permanence
Reduction of toxicity, mobility, or volume
Short-term effectiveness
Implementability
Cost
Modifying Criteria
State acceptance
Community acceptance
to Threshold criteria must be satisfied by the selected alterative. Primary balancing criteria are used
,veigh trade-offs among alternatives. Modifying criteria may be used to alter a proposed remedial alternative. Brief descriptions of the evaluation criteria and the items considered when assessing alternatives with respect to each criterion are presentpd in the summary of the comparative analysis
of alternatives.
The models simulating UFS groundwater flo-,%- and dissolved chemical transport were prepared for
the analysis of alternatives and are approximate in nature. Because detailed models were not needed
to compare the benefits of each remedial alternative, attempts were made to produce models that
incorporate general features of groundwater flow and associated transport phenomena in the Offpost
'21905 301040 Harding Lawson Associates 0711121495 R02 comparative Analysis of Alternatives
phenomena Study Area. Nonetheless, the resulting models predicted flow and chemical transport distributions. that agree with historical and current hydrogeologic data and observed contarninan uncertainty in the conceptual Because of the approximate nature of the models and the considerable be construed as accurate model and hydrogeologic parameters, none of the modeling results should modeling results should be predictions of future contaminant distribution. Rather, the models and there are inherent viewed as tools for assessing the relative merits of remedial alternatives. Although the alternatives, and uncertainties in the groundwater model, it is the tool being used to evaluate to evaluating alternative predicted differences in remediation time frames are considered with respect
effectiveness.
(1) continued For the North Model, the following remedial action scenarios were simulated: Groundwater operation of the NBCS with improvements as necessary (Alternative N-2), (2) Offpost Groundwater Intercept and Treatment System (Alternative N-4), and (3) expansion of the Offpost were evaluated Intercept and Treatment System (Alternative N-5). The results of these simulations versus time on the basis of estimated remediation times measured on maximum concentrations
graphs. The range of estimated remediation times was based on attainment of the groundwater
cleanup standards for DIMP, chloroform. and dieldrin, using a range of retardation factors. Although the some remediation goals have changed since modelling was performed, these changes do not affect
assessment of the relative merits of the remedial alternatives.
For the Northwest Model, the remedial action scenario for continued operation of the NWBCS with
improvements as necessary (Alternative NRV-2) was simulated.
8.1 Comparative Analysis of Remedial Alternatives
The purpose of the comparative analysis is to identify the advantages and disadvantages of each
alternative relative to the others. Critical tradeoffs were identified and used to assist in selection of
the preferred remedy. Summaries of the detailed analysis of the North Plume Group and Northwest
Plume Group alternatives are presented in Tables 8.1 and 8.2, respectively. A brief description of the
8-2 Harding Lawson Associates '21905 402010 0711121495 R02 Comparative Analysis of Alternatives
the evaluation criteria is evaluation criteria and a comparison of each alternative with respect to in the presented below. Components common to all of the alternatives were not evaluated comparative analysis.
8.1.1 Overall Protection of Human Health and the Environment as a final check in The criterion of overall protection of human health and the environment serves and the environ- assessing whether each alternative provides adequate protection of human health reduced, or controlled ment. This criterion was also used to evaluate how risks would be eliminated, activities. through treatment, engineering, institutional controls, or other remedial
North Plume Group Alternatives by all alternatives with Overall protection of human health and the environment would be provided greater protection than the exception of Alternative N-1. Alternatives N-4 and N-5 would provide North Plume Group Alternative N-2 because extraction, truatment, and recharge systems within the within a shorter time would decrease organic contaminant concentrations and reduce potential risks achieve containment period. Although groundwater modeling estimates that Alternative N-5 would for Alternatives svstein remediation goals in a shorter time period than Alternative N-4 (10-20 years with N-5 versus 15-30 vears for Alternative N-4), the two alternatives are essentially equivalent reasons: respect to providing protection of human health and the environment for the following
Alternatives N-4 and N-5 both provide for active remediation of the First Creek and Northern paleochannel groundwater in approximately the same time period through removal of contaminated UFS groundwater. treatment of the organics in the contaminated groundwater and using carbon absorption, and recharge of the treated groundwater using recharge wells trenches. the Both alternatives also provide a sigruf icant reduction in potential risk in approximately same time period through orgaruc contaminant removal and treatment by the Offpost Ground- water Intercept and Treatment System.
Northwest Plume Group Alternatives NWBCS Alternative NW-1 would not be protective of human health and the environment because the provided would cease operation. Overall protection of human health and the environment would be
8-3 '21905 301040 Harding Lawson Associates 0711121495 R02 Comparative AnalyAs of Alternatives by Alternative NW-2. Alternative NW-2 would decrease contaminant concentrations and reduce potential risks associated with groundwater entering the Offpost Study Area north of the NWBCS.
Recharge of groundwater treated at the NWBCS would reduce contaminant concentrations in the
Northwest Plume Group through flushing with treated groundwater. Groundwater modeling estimates that Alternative NW-2 would achieve groundwater containment system remediation goals in approximately three to eight years. Alternative NW-1 would not likely achieve groundwater containment system remediation goals because operation of the NWBCS would cease.
8.1.2 Compliance With Applicable or Relevant and Appropriate Requirements
The criterion of compliance with ARARs is used to assess whether each alternative will attain
ARARs. The comparative analysis describes how each alternative exceeds, attains, or does not attain these requirements. Other information such as advisories, criteria, or guidance documents have been considered where appropriate during the ARARs analysis (see Section 10.0).
North Plume Group Alternatives
Compliance with chemical-specific ARARs would be achieved by all alternatives with the exception of Alternative N-1 - Cleanup standards for Offpost OU groundwater include Safe Drinking Water Act
MCLs and CBSGs. Groundwater modeling estimates that chemical-specificARARs would be aclueved in the shortest time bv Alternative N-5. followed by Alternative N-4, followed by
.AJternative N-2.
Compliance with location-specific and action-specific ARARs will be achieved by all treatment
alternatives. Because no remediation would take place under Alternative N-1, there would be no
federal and state location- or action-specific ARARs. Inorganic standards for chloride and sulfate will be met bv natural attenuation consistent with the onpost remedial action.
Northwest Plume Group Alternatives
Compliance with chemical-specific ARARs would be achieved only by Alternative NW-2. Ground-
water modeling indicates that Alternative NIV-2 would achieve chemical-specificARARs in approxi-
8-4 Harding Lawson Associates '21905 402010 0711121895 R02 Comparative Analysis of Alternatives
and action-specific mately three to eight years. Alternative NW-2 would comply with location-
ARARs.
8.1.3 Long-term Effectiveness and Permanence risk remaining at the site after The long-term effectiveness and permanence criterion addresses the addressed for each response objectives have been met. Components of the criterion that were
alternative are as follows:
Magnitude of residual risk at the end of remedial activities residuals or Adequacy and reliability of controls that are used to manage either treatment untreated materials that remain at the site
North Piume Group Aftematives effectiveness and perma- Comparison of North Plume Group alternatives with respect to long-term a high degree of effectiveness nence indicates that each alternative, Except Alternative N-1, provides because using full-scale and permanence. However, Alternative N-4 is superior to Alternative N-5
additional wells and trenches and operating dald as the basis for identifying the need for placing
performance. A.11 of the alterna- identifYin; lb- oplimum locations will enhance long-term system
potential risk and address tives %vill.it,.. - xf:--ption of the No Action alternative would reduce
Group. UndertheNo expostir- pallma%-- I-%- reducing COC concentrations in the North Plume
operation of the NBCS. Action all. ,t, %I;%- 11,,lential risks would likely increase after ceasing
Northwest Plume Group Alternatives
effectiveness and Compari% i. I t:.- N rth%%-est Plume Group alternatives with respect to long-term
addresses exposure pathways permaiwi, - it, ii it.-s that Alternative NW-2 reduces potential risk and
No Action alternative, by reduciti;z C(K: t.oncentrations in the North%vesl Plume Group. Under the
potential risks would likely increase afte.- ceasing operation of the NWBCS.
Lawson Associates 8-5 '21905 30IG40 Harding 0711121495 R02 Comparative Analysis of Alternatives
8.1.4 Reduction in Toxicity, Mobility, or Volume for The reduction of toxicity, mobility, or volume criterion addresses the statutory preference mobility, or volume of selecting remedial actions that permanently and significantly reduce toxicity, used to reduce hazardous materials at the site. This preference is satisfied when treatment is and/or volume. principal risks through destruction or irreversible reductions of toxicity, mobility,
North Plume Group Alternatives reduce the All North Plume Group alternatives with the exception of the No Action alternative would north of the toxicity, mobility, and volume of contaminated groundwater entering the Offpost OU likely NBCS. Groundwater contaminant concentrations under the No Action alternative would and increase. Alternatives N-4 and N-5 would provide the greatest reduction in toxicity, mobility, the North volume of contaminated groundwater, through extraction, treatment, and recharge within frames Plume Group. As stated previously, the uncertainty associated with the remediation time estimated by the groundwater modeling suggests that. in practical terms, the estimated time frames for both Alternatives N-4 and N-5 are essentially equivalent. Further, the intensive short-term groundwater monitoring component of Alternative N-4 would allow for full-scale performance data regarding the reduction of contaminant concentrations. Such data would be necessary to assess the need for and optimum location of any modifications to Alternative N-4.
Northwest Plume Group Alternatives
Alternative N'W-2 would reduce the toxicity. mobility. and volume of contaminated groundwater
entering the Offpost OU northwest of the NWBCS through extraction, treatment, and recharge.
Groundwater contaminant concentrations under the No Action alternative would likely increase; thus
toxicity, mobility, or volume would not be reduced.
8.1.5 Short-term Effectiveness
The short-term effectiveness criterion addresses the protection of human health and the environment
during the construction and implementation phase. The following factors were addressed during the
evaluation process:
6_6 Harding Lawson Associates '21905 402010 0711121495 R02 Comparative Analysis of Alternatives
Protection of the community during remedial actions - This factor addresses any risk that dust from results from implementation cf the proposed remedial alternative, such as excavation or transportation of hazardous material. that may be Protection of the workers during remedial actions - This factor assesses threats taken. posed to workers and the effectiveness and reliability of measures to be adverse Environmental impacts of the remedial action - This factor addresses the potential of a remedial environmental impacts that may result from construction and implementation or alternative and evaluates the reliability of mitigation measures, if necessary, to prevent reduce potential impacts. estimate of Time lapse before achievement of response objectives - This factor includes an the time required to achieve protection for the site.
North Plume Group Alternatives the community and Assessment of the North Plume Group alternatives with respect to protection of that the No workers, short-term adverse environmental impacts, and implementation period indicates active remediation Action alternative and Alternative N-2 are slightly better than the alternatives with would be able to components. However, during the implementation period, Alternatives N-4 and N-5 to mirumize adverse short-term impacts through standard engineering controls and adherence
standard health and safety practices.
Northwest Plume Group Alternatives
The assessment of the two Northwest Plume Group alternatives with respect to protection of the
community and workers, short-term adverse environmental impacts, and implementation period
shows that the No Action alternative and Alternative NIV-2 are essentially equivalent except that the
discontinued operation of the NWBCS, as part of the No Action alternative, has an adverse environ-
mental impact. Neither alternative. %%"Lth the exception noted above, has significant short-term
effectiveness issues.
8.1.6 Implementability
The implementability criterion evaluates the techmcal and administrative feasibility of implementing
each alternative, and it addresses the availability of required services and materials during
'21905 301040 Harding Lawson Associates 8-7 0711121495 R02 Comparadv* Analysis of Alternativets
during the evaluation implementation of the alternative. The following factors were addressed process:
and the Construction and operation - This factor considers the technical difficulties unknowns associated with the technology. that problems associated Reliability of the technology - This factor considers the likelihood with implementation may result in schedule delays. to the alternatives Implementing additional remedial action - This factor is not applicable developed because the alternatives considered are not interim measures. to evaluate the Monitoring the effectiveness of the remedy - This factor addresses the ability exposure should effectiveness of the remedy and includes an evaluation of the risks of monitoring be insufficient to detect a system failure. alternatives (e.g., Coordination with other offices and agencies needed to implement remedial obtainmS necessary permits for offsite activities) and adequate offsite Availabilitv of necessary equipment, specialists, services and materials, treatment. storage, and dispcýsal services
North Plume Group Afternatives implement. The No All North Plume Group alternatives evaluated would be technically feasible to to technical Action ili,-mat 1%-4-and Alternative N-2 would be the easiest to implement with respect
and the NBCS system is feasibilit% b-rdUSIý the monitoring wells have already been installed
currenfly (,I---tdii()ndl. Alternative N-4 is constructed and is fully operational. However,Altema- use tive N-5 we,ul- I i-.juise additional design and construction. All treatment alternatives would systems to carbon. -it tro-alment. which has been demonstrated at the boundary containment all be d re-hat... p, im ]waier treatment process option. Groundwater monitoringis a componentof alternative. foLL- -m,l would provide information regarding the effectivenessof each
It All allernati%---s with the exception of tht! No Action alternative would be administratively feasible.
of the NBCS as is unlikely 1hdt the regulatory agencies or the public would accept shutdown
proposed under the No Action alternative. Additionally, the Army will not cease operating the NBCS
until cleanup certification. Each of the three treatment alternatives would meet federal and state
substantive requirements for recharging the treated groundwater to the UFS.
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additional equipment and services. The No Action alternative and Alternative N-2 would not require respect to availability of services The implementation of Alternative N-5 would not be limited with and implement this and materials. Contractors with the equipment and knowledge to construct were completed in June alternative are readily available. The remedial systems of Alternative N-4
1993.
Northwest Plume Group Alternatives feasible to implement. The Both Northwest Plume Group alternatives evaluated would be technically with respect to technical No Action alternative and Alternative NW-2 would be implementable and the NWBCS is currently feasibility because the monitoring wells have already been installed which has been demonstrated operational. Alternative NW-2 would use carbon adsorption treatment, treatment process option. at the boundarv containment svstems to be a reliable groundwater provide information regard- Groundwater monitoring is a component of both alternatives and would ing the effectiveness of each alternative.
that the regulatory The No Action alternative would not be admirustrativelv feasible. It is unlikely the No Action agencies or the public would accept shutdown of the NVVBCS as proposed under alternative. Additionallv, the Armv does not intend to cease operating the NWBCS. the treated .AJternat ive N-W-2 would meet federal and state substantive requirements for recharging services. groundwater to the UFS. Neither alternative would require additional equipment and
8.1.7 Cost and The cost criterion evaluates both c-ipital costs and any long-term costs required to operate cost maintain an alternative. Cost estimates for each alternative were based on vendor information, maintenance estimating guides, review of published cost data at previous sites, and operation and
costs at the boundarv containment sN,stems.
Associates 8-9 '21905 301040 Harding Lawson 0711121495 R02 Comparative Analysis of Alternaffivos
North Plume Group Alternatives
N-1 to $56.5 to The total present worth costs range from $4.1 to $6.0 million for Alternative
for Alternatives N-4 $63.1 million for Alternative N-4. The present worth costs are nearly identical
are balanced by the and N-5 because the additional capital expenditures required for Alternative N-5
10-year additional operation and maintenance (O&M) costs incurred through the estimated
differences in remediation timeframe for Alternative N-4.
compared to The additional capital expenditure of approximately $2.7 million for Alternative N-5 as
to aid in Alternative N-4 points out the importance of collecting additional full-scale operating data
and decision-making regarding any necessary expansion of the Offpost Groundwater Intercept
Treatment System. Collection of full-scale data on contaminant transport and actual plume
remediation time frames through the intensive short-term monitoring program is cuxrently being
conducted. This monitoring program will provide data for use in any system expansion decision-
making regarding the potential need for and placement of improvements to Alternative N-4 to reduce
the remediation timeframe and/or efficiencv.
Northwest Plume Group Alternatives
The total present worth costs rant,ze from $0.6 to $1.3 million for Alternative NW-1 to $12.4 to $13.1
million for Alternative NW-2.
8.1.8 State Acceptance
State acceptance evaluates technical and admirustrative concerns the State may communicate in its
Comments concerrung each alternative. The State has been actively involved throughout the RI/FS
and remedv selection process for the Offpost OU. The State was provided the opportunity to
comment on the RVFS document and proposed plan. and took part in the public meeting held to
inform the public on the proposed plan. Written comments from the state received during the public
comment period indicate that the State prefers Alternative N-5 or a slightly modified version of
Alternative N-5 over Alternative N-4 because of the addition of several wells and trenches for
8-10 Harding Lawson Associatos '21905 402010 0711121495 R02 Comparative Analysis of Alternatives
issues are enhanced contaminant removal. Responses to the State's concerns on this and other provided in Appendix A - Responsiveness Summary.
of Colorado, Additional discussions were held between the U.S. Army, Shell Oil Company, the State the U.S. EPA, and the US. Fish and Wildlife Service following the issuance of the Offpost proposed the plan regarding the remedy for both the Offpost and Onpost OUs. As a result of these discussions, a State of Colorado and the other parties have agreed to the remedy as described in Agreement for
ConceptualRemedyfor the Cleanup of the Rocky Mountain Arsenal (ConceptualRemedy Agreement). and to Each party has agreed to support the conceptual remedy as the preferred remedial alternative support the proposed plan based on the elements of the conceptual remedy.
8.1.9 Community Acceptance
The preferred alternative for the Offpost OU was presented to the public in a Proposed Plan, which provides a brief summary of all of the alternatives evaluated during the detailed analysis of alterna- tives in the FS. In accordance with the NCP, the public had an opportunity to review and comment on the selected remedial alternatives presented in the Proposed Plan. The concerns expressed included (1) soil remediation issues. (2) DIMP groundwater cleanup standard, (3) why expansion of the Offpost Groundwater Intercept and Treatment System was not selected, (4) the presence of DIMP immediately do%%mgraclient of the Off4post Groundwater Intercept and Treatment System in the First
Creek area, and (5) the classification of potential future land use. The public's comments are addressed in the attached responsiveness summary (Appendix A). Community participation was also
included during the Conceptual Remedy Agreement negotiations.
8.2 Conclusions of the Comparative Analysis of Alternatives
The conclusions of the comparative analysis of groundwater alternatives for the North and Northwest
Plume Groups are summarized below.
'21905 402010 Harding Lawson Associates 8-11 0711121895 R02 Comparative Analysis of Altema6v*s
In terms of overall protection of human health and the environment,comphance with ARARs, superior to effectiveness, and reduction of toxicity, mobility, or volume, Alternatives N-4 and N-5 are
Alternatives N-1 and N-2. Alternative N-4 is equal to Alternative N-2 in implementability.
Alternative N-4 is more readily implementable than Alternatives N-1 and N-5 because Alterna- tive N-1 would not be administratively feasible, and Alterative N-5 would require a second design and construction phase. Alternatives N-4 and N-5 are approximately equal in cost when compared to each other and higher in cost when compared to Alternatives N-1 and N-2. Therefore, Alternatives
N-4 and N-5 were identified as being superior to Alternatives N-1 and N-2. Alternatives N-4 and N-5 are essentially equivalent with respect to evaluation of compliance with ARARs, short-term effective- ness, and reduction in toxicity, mobility, or volume.
Alternative N-4 was demonstrated to be superior to Alternative N-5 with respect to the detailed
analvsis criteria for the following reasons:
The remedial system in Alternative N-4 is designed to effectively address groundwater contamination within the North Plume Group on the basis of all available data. The Offpost Groundwater Intercept and Treatment System is designed similar to the existing boundary containment systems in that monitoring data is being evaluated to assess whether any improvements are necessary. The intensive short-term groundwater monitoring program included under Alternative N--%. adds flexibility through providing information that will be used to identify any necessary or beneficial improvements to the Offpost Groundwater Intercept and Treatment Svstem and provides information about the optimal location of additional wells or trenches. Because the estunates of remediation time frames developed for the groundwater alternatives are uncertain. additional capital expenditures are not justified until actual full-scale data is available.
Alternative N-4 is superior to Alternative N-5 with respect to long-term effectiveness and permanence. The combination of full-scdle operational data from the Offpost Groundwater Intercept and Treatment System and future possible system modifications will result in an optimized treatment system. Immediate pldcement of additional wells and trenches in Alternative N-5, baseý on groundwater modeling results, would not be based on the more accurate empirical data.
Alternative N-4 is more readily implementable than Alternative N-5 because implementation of Alternative N-5 would require additional remedial design and construction. Operation of Alternative N-4 would start immediateiv.
Alternative MV-2 ranks above Alternative NW-1 in all criteria except cost; however, the additional
costs are not prohibitive in light of the reduction in time for remediation.
8-12 Harding Lawson Associates '21905 402010 0711121495 R02 9.0 IDENTIFICATION OF THE SELECTED REMEDY
remediation of The selected remedy for the Offpost OU consists of implementing Alternative N-4 for of groundwater in the groundwater in the North Plume Group, Alternative NW-2 for remediation System consistent Northwest Plume Group, and continued operation of the Irondale Containment Section 7 and the with the Irondale IRA. The selected alternatives are described in detail in
Declaration to the ROD.
Treatment System 9.1 Alternative N-4: Oftpost Groundwater Intercept and in November 1991 Construction of the Offpost Groundwater Intercept and Treatment System began specifics is and full-scale system operation began in June 1993. Additional detail concerning design and Treatment contained in the Final Implementation Document for the Groundwater Intercept as follows: System North of RMA (HLA, 1991). The major components of this alternative are
Operation of the Offpost Groundwater Intercept and Treatment System - Removal of contarninated UFS groundwater north of the RMA boundary in the First Creek and northern paleochannels, using Offpost Groundwater Intercept and Treat- ment System groundwater extraction wells
- Treatment of the extracted groundwater, using carbon adsorption
- Recharge of treated groundwater to the UFS, using Offpost Groundwater Intercept and Treatment System recharge wells and trenches - Natural attenuation of inorganic chloride and sulfate concentrations to meet applicable standards for groundwater in a manner consistent with the on-Post remedial action
Continued operation of the NBCS
Improvements to Offpost Groundwater Intercept and Treatment System and the NBCS, as necessary
Long-term groundwater and surface-water morutonng
Site reviews
Exposure control/provision of alternate water supply as described in Section 7.1
Well closure in conformance with criteria listed in Appendix C, pages C-1 and C-2
9-1 '21905 402010 Harding Lawson Associates 1107121895 R02 Idontification of the SoWeted Rornody
Appendix B. These institutional institutional controls for the selected remedy are reflected in exceeding remediation goals. controls are intended to prevent the future use of groundwater
array of extraction wells and The Offpost Groundwater Intercept and Treatment System is an . The system is configured to extract recharge trenches in the northern and First Creek paleorhannel goals and to recharge the and treat UFS groundwater that exceeds containment system remediation wells and recharge wells in the treated groundwater. Figure 7.1 presents the placement of extraction recharge trenches in the First Creek northern paleochannel and the placement of extraction wells and Figure 7.1. The northern paleo- paleochannel. The location of the treatinent facility is also shown in 200 feet apart across channel collection system consists of 12 extraction wells spaced approximately The recharge system in the the paleochannel, perpendicular to the direction of groundwater flow. and placed parallel to and northern paleochannel consists of 24 recharge wells spaced 100 feet apart paleochannel approximately 300 feet downgradient of the collection system. The First Creek along the axis of the collection system consists of 5 extraction wells spaced 200 to 500 feet apart parallel to the flow paleochannel. Recharge trenches are placed such that four of the six trenches are located axis and located on the margins of the paleochannel, with the remaining two trenches axis. downgradient of the extraction well system and oriented perpendicular to the flow
paleochan- The system is designed to extract and treat an average flow of 300 gpm from the northern
nel, an average flow of 180 gpm from the First Creek paleochannel, and a peak flow of 1.5 times the
average flow. The treatment facility basic process flow includes influent storage, pumping, bag
filtration for particulate removal. carbon adsorption. multimedia filtration, treated water storage,
treated water pumping, and final bag filtration.
A total of approximately 250 million gallons per year would be treated by the Offpost Groundwater
Intercept and Treatment System at the average flows. In addition, operation of the NBCS component
of this alternative will treat approximately 125 milhon gallons per year. Thus, a total of approxi-
9-2 Harding Lawson Associate5 '21905 402010 0711121895 R02 Identification of the Selected Remedy
mately 375 million gallons of UFS groundwater will be treated annually to attain Offpost OU containment system remediation goals (Tables 7.1, 7.2, and 7.3) under this alternative.
An intensive short-term monitoring component will be included in Alternative N-4 as part of the consist of a long-term monitoring program. For costing purposes, it is assumed that this program will with network of approximately 60 wells to be sampled semiannually for two to three years, beginning the Offpost Groundwater Intercept and Treatment System start-up. The intensive monitoring program will allow the collection and subsequent interpretation of performance data for the full-scale operation of both the Offpost Groundwater Intercept and Treatment System and the NBCS. The data will also be used to assess the need for any improvements to the systems. The acquisition of such data will allow for increased accuracy in assessing the response of the UFS groundwater to the NBCS and Offpost Groundwater Intercept and Treatment System remediation systems.
In addition, the preferred alternative includes long-term monitoring of offpost groundwater and surface water to assess contaminant ccncentration reduction and remedy performance. Groundwater monitoring will continue utilizing both monitoring wells and private drinking water wells. Selected surface-water monitoring locations will be included to evaluate the effect of groundwater treatment on surface water quahty. Monitoring will continue after system shut-off to assure continued compliance with containment system remediation goals. The Army will present the scope of these ongoing monitoring programs in an Implementation Plan to be submitted within 90 days following issuance of the ROD. A schedule for compliance with the containment system remediation goals will be included in the Implementatior Plan.
9.2 Alternative NW-2: Continued Operation of the Northwest Boundary Containment System with Improvements as Necessary
This section summarizes Alternative NW-2, the continued operation of the NWBCS with improve-
ments as necessary. For additional details of the extraction/recharge systems, the recent upgrades to
the system, and the treatment facility at the NWBCS, the reader is referred to the following reports:
'21905 402010 Harding Lawson Associates 9-3 1107121895 R02 Identification of the Selected Remedy
IRA (Morrison-Knudsen Final implementation Document for NWBCS Short-term Improvements IRA B(ii) Final Assess- Environmental Services [MKES], 1990a); NVVBCS Long-term Improvements NWBCS RMA Long- ment Document (Woodward-Cayde [wwq, 1991a); Proposed Decision Document and Final term Improvements IRA (WWC, 1991b); Report of Field Investigations, Assessment, Implementation Decision Document for the NWBCS Short-term Improvements IRA (NflCES, 1990b); Report (MKES, Document for the Northwest Boundary System long-term Improvements IRA Final One-year 1992); and Northwest Boundary Containment System Long-term Improvements IRA
Evaluation Report (MKES, 1993). The major components of this alternative are as follows:
Continued operation of the NWBCS
Improvements to the NWBCS as necessary
Long-term groundwater monitoring
Site reviews
Exposure control/provision of alternate water supply as described in Section 7.1
Well closure in conformance with criteria listed in Appendix C, pages C-1, and C-2
Institutional controls as described in Appendix B
In addition. the preferred alternative 4.ncludes long-term monitoring to assess contaminant concentra- tion reduction and remedy performance. After attainment of groundwater containment system
remediation goals and system shut-off, groundwater monitoring will continue to assure continued
compliance with containment system remediation goals. The Army will present the scope of these
monitoring programs in implementation plans to be submitted following issuance of the ROD.
The MVBCS began operation in 1984. The NWBCS collection system consists of 20 extraction wells
and a sod bentonite barrier approximately 2300 feet in length. The recharge system consists of 25
downgradient recharge wells.
9-4 Harding Lawson Associates '21905 402010 0711121895 R02 Identification of the Selected Remedy
9.3 Additional Components of the Selected Remedy the selected In accordance with the NCP, the public had an opportunity to review and comment on remedial alternatives presented in the Proposed Plan. In response, the Parties held additional in discussions to determine how best to address these comments. These discussions resulted clarifications and minor technical changes -that do not significantly alter the overall scope, perfor- mance, or cost of the Offpost preferred alternative.
Because the main focus of the Offpost preferred alternative is unchanged, and the additional actions only clarify and enhance the preferred alternative, the changes were not considered to be significant.
The discussions also involved broader issues which were resolved in a document entitled "Agreement
for a Conceptual Remedy for the Cleanup of the Rocky Mountain Arsenal,' dated June 13, 1995.
With regard to the Offpost area, the Pzrties agreed to several additional components which are an
integral part of the overall remedy but are proposed for inclusion in the Onpost ROD. Many of these
components are in the Onpost Proposed Plan, which is available for public comment from
October 16, 1995, through January 19, 1995.
The additional components added in response to public comment and as part of the Conceptual
Remedy Agreement discussions include:
The U.S. Army and Shell Oil Company agree to continue monitoring and to complete an assessment of the NDMA plume by June 13, 1996, using a 20 ppt method detection limit.
The U.S. Army and Shell Oil Company agree to prepare a feasibility study of potential actions, both onpost and at the boundary. or ad)acent to the boundary in order to achieve NDMA remediation goals at the RMA boundary and to use 7.0 ppt PRG or a certified analyti- cal detection level readily available at a certified commercial laboratory (currently 33 ppt).
The U.S. Army and Shell Oil Company agree to revegetate approximately 160 acres located in the southeast portion of Section 14 aný the southwest portion of Section 13 as depicted in Figure 9.1. Revegetationwill involve tilling and seeding. No sampling will be conducted before or after revegetation. Existing soil risks in the area to be revegetated fall within EPA's established acceptable risk range and revegetation is not necessary. However, the U.S. Army and Shell Oil Company agree to the revegetation program as part of the Offpost settlement.
'21905 402010 Harding Lawson Associates 9-5 1107121995 R02 identification of the Selected Remedy
or reinjection The Army will treat any contaminated extracted groundwater prior to discharge the Colorado Basic so that it meets the current water quality standards established in Methodologies for Surface Standards for Groundwater and the Colorado Basic Standards and Water. (ppb) detection As of the date of the Onpost ROD, and based on a 0.392 parts per billion to determine the limit, the U.S. Army will use the last available quarterly monitoring results DRAP plume footprint to, the current The Army and Shell Oil Company will pay for the extension of, and hook-up water distribution system for all existing well owners within the DRAP plume footprint referenced above. of the Existing domestic well owners outside of the DIMP plume footprint as of the date (or Onpost ROD where it is later determined that levels of DMV are eight ppb or greater Oil Com- other relevant CBSG at the time) will be hooked up at the U.S. Army and Shell well or other pany's expense to the SACWSD distribution system or provided a deep permanent solution. at the For new domestic wells with levels of eight ppb or greater for other relevant CBSG Oil time), the Offpost ROD institutional controls will provide that the U.S. Army and Shell Company will pay for hook-up to the distribution system or provided a deep well or other permanent solution.
The parties to the Conceptual Remedy Agreement commit to good faith best efforts to establish a trust fund for the operations and maintenance of the remedy, including habitat and surficial soil. The parties recognize. however, that establishment of such a trust fund requires special legislation and there are restrictions on the actions federal agencies can take with respect to proposing legislation and supporting proposed legislation.
As part of the Onpost remedy, the U.S. Army and Shell Oil Company will pay for and provide. or arrange for the provision, of 4000 acre-feet of water to SACWSD.
9.4 Cost of Selected Remedy
A detailed cost summary for the selected remedy is presented in Table 9.1. The total estimated cost
ranges from approximately $69 to $76 million. This cost does not include implementation of the
additional components discussed in Section 9.3. However, these additional components would be
included in all the alternatives evaluated (except the No Action alternative); therefore, the relative
relationship of the cost of the various alternatives will not change.
9.5 Limitations
It should be recognized that U.S. Environmental Protection Agency (EPA) studies (EPA, 1988b) have
indicated that it may not always be possible to reach MCJs or proposed MCIs through currently
available technology. If it becomes apparent during implementation or operation of the selected
9-6 Harding Lawson Associates '21905 402010 Identification of the Selected Remedy
for a significant amount of time at levels remedy that contaminant levels are remaining constant goals delineated in the ROD, the higher than the groundwater containment system remediation be reevaluated. Further, the NCP containment system remediation goals and the remedy will remedy at least every five years. As requires a formal review of the effectiveness of the selected reviewed to achieve the groundwater needed, the operational design of the selected remedy will be containment system remediation goals .
Offpost Containment 9.6 Criteria for Shutting Down Boundary and Groundwater Systems can be removed from produc- Existing wells within the boundary and offpost containment systems less than applicable or relevant and tion when concentrations of constituents detected in the well are it can be demonstrated that appropriate requirements (ARARs) established in the ROD and/or of the systems. Wells discoiatinumg operation of a well mill not jeopardize the containment objective of the boundary and removed from production, and monitoring wells upgradient and downgradient five years to determine if offpost containment systems, will be monitored quarterly for a period of be subject to the quarterly contaminants reappear. Wells turned aff for hydraulic purposes will not wells removed from morutoring requirements. Boundary and offpost containment system extraction concentra- production for water quality reasons will be placed back into production if contaminant ARARs tions exce--d tia- AFLALRs established in the ROD. Wells with concentrations less than
established in the ROD can remain in production if additional hydraulic control is required.
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compliance with the A description of how the selected remedy meets statutory requirements, in this section. requirements of CERCLA, and consistency with the NCP is presented
of CERCLA in Section 121 10.1 Consistency with the Statutory Requirements below, and the statutory preference The statutory requirements of CERCLA Section 121, as described remedy. for treatment are met through implementation of the selected
Environment 10.1.1 Protection of Human Health and the Offpost OU groundwater consistent with The selected remedy will result in the remediation of the goals established for the site. remedial action objectives and containment system remediation Plume Groups will be addressed by Contaminated groundwater in the North and Northwest extraction, treatment, and recharge. implementing the selected remedy through groundwater
N-4 and NW-2 will permanently The groundwater remedial actions proposed under Alternatives for the Offpost Study Area through address the primary threat to human health and the environment and volume of contaminated ground- ca.rbon adsorption treatment to reduce the toxicity. mobility. wil-l be reduced to or below ground- water Contaminant levels in Offpost Study Area groundwater Reduction of groundwater water containment svstem remediation goals foliowing treatment. the groundwater cumulative excess contaminant concentrations to these goals %%-ill further reduce the M for noncarcinogens will be cancer risk toward 10'. Following groundwater remedial action,
less than 1.
sites (by EPA and others) have It should be recognized, however, that studies con3ucted at other containment system remediation indicated that it may not always be possible tn reach groundwater groundwater hydrogeological. goals because of the limitations of the technology used to assess frames, and the technologyused properties. the technology used to estimate aquifer remediation time operation of the groundwater to extract and recharge groundwater. If it becomes apparent during
Harding Lawson Associates 10-1 '21905 402010 Statutory Determinations
constant at levels higher than treatment systems that groundwater contaminant levels are remaining goals , the selected remedy provides for the Offpost OU groundwater containment system remediation An alternative water supply will be improvements to the proposed remeclial systems as necessary. provisions in Section 7.1. Institu- provided to any user of a domestic well in accordance with the the future domestic use of tional controls that are part of this remedy are intended to prevent groundwater exceeding the containment system remediation goals.
selected remedy provides the Of the alternatives evaluated for cleaning up the groundwater, the to the environment. No highest degree of protection of human health without adverse impact remedy. unacceptable short-term risks will be caused by implementing this
Maintenance of Potential ecological impacts duxing remediation will be continually evaluated. Endangered Species Act, the existing habitats and ecosystems are important. Although the Federal not considered as ARARs, the FFA Migratory Bird Treaty Act, and the Bald Eagle Protection Act were requirements of these requLres their application. Remediation goals consistent with the substantive U.S. Fish and Wildlife Acts are being met and will be assured through close interaction with the agreed that screening levels, Service. In coordination with the U.S. Fish and Wildlife Service, it was requirements ofthe developed to ensure compliance with enforceable remediation levels, meet the and Golden Eagle federal Endangered Species Act. the Migratory Bud Treaty Act, and the Bald levels are Protection Act. These screening levels were not exceeded in the Offpost OU. These Study in presented in the Final Offpost Operable Unit Endangerment Assessment/Feasibility of Concern Table 3.3.3-1 (Toxicity Reference Values for Avian and Terrestrial Vertebrate Species Tissue Identified at Rocky Mountain Arsenal) of Volume 11 and Table 1-15-1 (Maximum Allowable in Concentration [1AATC] Values for the Offpost E.A. Ecological Assessment) of Appendix H
Volume I'V. If the screening levels are exceeded or effects are observed in the future, enforceable
remediation levels urill be developed consistent with CERCLA, the Endangered Species Act, the
Migratory Bird Treaty Act, and the Bald and Golden Eagle Protection Act.
10-2 Harding Lawson Associates '21905 402010 1107121495 R02 Statutory Determinations
and Appropriate Requirements 10.1.2 Compliance With Applicable or Relevant standards, requirements, limita- Under Section 121(d)(1) of CERCLA, remedial actions must attain under the circumstances of the tions, or criteria that are applicable or relevant and appropriate of the selected remedy at the release at a site. ARARs would be met or exceeded upon completion
Offpost OU.
Chernicai-specific ARARs on chemical-specific ARARs for those Groundwater containment system remediation goals are based without ARARs chemicals having promulgated standards and on HBC for those chemicals expected to attain or exceed (Tables 7.1, 7.2, and 7.3). The preferred site%ide alternative is other ARARs that have been chemical-specificARARs. A summary of the chemical-specific and in Table 10.1. assessed to be applicable or relevant and appropriate is presented
Action-specific ARARs summary of the action-specific The selected remedywill comply witý action-specific ARARs. A is presented in AR.ALRs that have been assessed to be applicable or relevant and appropriate
Table 10.2.
Location-specific ARAPIS of the location-specific The selected remedy xvill comply %%ith location-specific AFkRs. A summary presented in ARARs that have been assessed to be applicable or reievant and appropriate is
Table 10.3.
10.1.3 Cost Effectiveness by contaminated The selected remedv is cost-effective in mitiv,,it inz the risks posed at the site criteria to groundwater. Cost-effectiveness is determined b% evaluating three of the five balancing of toxicity, determine overall effectiveness: long-term eftecuveness and permanence; reduction is then mobility, or volume through treatment. and short-term effectiveness. Overall effectiveness
compared to cost to ensure that the remedy is cost-effective.
Lawson Associates 1-0.3 '21905 402010 Harding 1107121495 R02 Statutory Determinations
best overall effectiveness of al.1 alternatives The selected remedy for groundwater provides the will greatly reduce the toxicity, mobility, considered proportional to its cost. The selected remedy remediation goals. Also the implementa- and volume of groundwater exceeding containment system by reducing residual carcinogenic risks tion of this remedy wW result in long-term effectiveness through permanent treatment.
can more accurately assess the contaminant Through the groundwater monitoring program, the Army data available during operation of the Offpost removal rates as a function of time, using the full-scale and the NVVBCS. The analysis of this data Groundwater Intercept and Treatment System, the NBCS, improvements that may be required for the will allow for cost-effective decisions regarding any future
remedial systems.
to the Maximum Extent Practicable 10.1.4 Utilization of Permanent Solutions extent to which permanent The selected remedy for the Offpost OU represents the maximum manner to remediate ground- solutions and treatment technologies can be used in a cost-effective health and the environment and water at the site. Of those alternatives that are protective of human and NW-2) will provide the best balance comply,with ARARs, the selected remedy (Alternatives N-4 reduction of toxicity, mobility, or of trade-offs in terms of long-term effectiveness and permanence; cost; the statutory preference volume through treatment. short-term effectiveness: implementability; acceptance. for treatment as a principal element. and state and community
Plan 10.2 Consistency with the National Contingency in the remedy selection process: The NCP requires that the following two features b-ý present
are used to select a The nine criteria used to evaluate alternatives Ln the detailed analysis remedy. fol.lowing four Selected Superfund remedies must employ the rune criteria to make the determinations: the environ- Each remedial action selected shall be protective of human health and ment.
Lawson Associates '21905 402010 10-4 Harding 1107121495 R02 Statutory Determinations
or provide grounds for Onsite remedial actions selected in a ROD must attain ARARs invoking a waiver. that it first satisfies the Each remedial action selected shall be cost effective, provided threshold criteria (defined in Section 8.0). extent Each remedial action shall use permanent solutions to the maximum practicable.
the NCP, as is the selection process used to The preferred sitewide alternative is fully consistent with and screened, and the detailed arrive at the preferred alternative. Alternatives were developed with the NCP. analysis of alternatives was performed in a manner consistent
10.3 Summary Offpost OU is the combination of Alterna- The preferred sitewide alternative for iemediation of the in accordance with the requirements of tives N-4 and NW-2. The preferred alternative was selected the sitewide preferred alternative will CERCLA and the NCP. The remedial actions that compose extraction and treatment to reduce permanently address the principal threats through groundwater of human health and the environ- the toxicity. mobility, or volume of contaminants for protection
ment.
supply and hookup to the SACWSD Although the requirements for provision of an alternate water reduce the potential for exposure are part of the Onpost remedy. these actions will also significantly
to offpost groundwater.
Harding Lawson Associates 10-5 '21905 402010 1107121495 R02 11.0 DOCUMENTATION OF SIGNIFICANT CHANGES
was released for public The Proposed Plan for the Rocky Mountain Arsenal Offpost Operable Unit N-4 (Offpost Groundwater comment in March 1993. The Proposed Plan identified Alternative in the North Plume Intercept and Treatment System) as the preferred alternative for groundwater Boundary Containment System Group and Alternative NW-2 (Continued Operation of the Northwest groundwater in the Northwest With Improvements as Necessary) as the preferred alternative for Environmental Protection Plume Group. The Army received written comments from the U.S. governments, Agency, the State of Colorado, the Tri-County Health Department, city and county it was determined that environmental action groups, and citizens. After review of these comments, identified in the Proposed no sigruficant changes to the preferred alternative, as it was originally
Plan, were necessary.
Proposed Plan, additional As indicated earlier in Section 8.1.8. following the issuance of the Offpost of the preferred alternative discussions were held between the Parties regarding the implementation of the preferred for the Offpost OU and the remedies for the Onpost OU. The main components alternative for the Offpost OU remain intact. These components are:
and Operation (and improvement. if necessary) of the Offpost Groundwater Intercept Treatment Svstem
Continued operation (and impmvern,,nt. if ri-ý:--ssarv) of the NBCS and NWBCS
Long-term groundwater and surface-wat-,r nionooring
Five-year site review
Well closure intended to Provision of alternate water suppli-i. -in,l iniplnuentation of institutional controls prevent future use of contaminatt-d groun iwater.
The Conceptual Remedy Agreement pro, -ides more specific criteria for the provision of alternate of and water supplies to current and future well owners. specific criteria for continued operation for requirements for shutdown of the groundwater treatment systems, and additional requirements
Associates 11-1 '21905 402010 Harding Lawson 1107121495 R02 Documentation of Significant Changes
of surface soil and additional study the Army and Shell Oil Company such as tiffing and revegetation is unchanged by the Conceptual requirements. Because the main focus of the preferred alternative Conceptual Remedy Agreement only Remedy Agreement, and the additional actions specified in the Remedy Agreement was not considered clarify and enhance the preferred alternative, the Conceptual as presented in the Proposed Plan, to be a significant change. Therefore, the preferred alternative in the Conceptual Remedy and additional actions to enhance the preferred alternative as outlined
Agreement, is the selected remedy.
11-2 Harding Lawson Associates '21,005 402010 1107121895 R02 12.0 GLOSSARY
requirement ARAR Applicable or relevant and appropriate
Army U.S. Department of the Army . Disease Registry ATSDR U.S. Agency for Toxic Substances and
CAR Cont-ination Assessment Report
CBSG Colorado Basic Standards for Groundwater for Surface Water CBSM Colorado Basic Standards and Methodologies and Liability Act CERCLA Comprehensive Environmental Response, Compensation,
CF&I Colorado Fuel and lron
CFS Confined flow system
CNIP Comprehensive Monitoring Program
CNS Central nervous system
COC Chemicals of concern
CRL Certified reporting limit
CSC Chemical Sales Company
CU Consumptive use
DBCP Dibro mochl oropro pane
DCPD Dicyclopentadiene
DDE 2.2-bis(p-Chlorophenvl)-1.1 -dick-Joroethene
DDT 2.2-bis(p-Chlorophenvi)- I.I. I -trichloroethane
DINIP Diisopropy1methyl j:h otrh,)nit,-
DOI U.S. Department of InIvrirr
DOJ U.S. Department of justic--
FATS Endangerment dSSeSSm,-nL f-asibilitv study
EPA U.S. Envuoranental I'vPtection Agency
ESE Environmental Science and Engineering, Inc.
FFA Federal FacilitN. Agreement
12-1 '21905 402010 Harding Lawson Associates 1107121495 R02 Glossary
GMT Groundwater M3nitoring Program
gpm Gallons per minute
HBC Health-based criteria
HI Hazard index
HQ Hazard quotient
Hyman Julius Hyman & Company
ICS Irondale Containment System
IRA Interim response action
MCL Maximum contaminant level
MCLC Maximum contaminant level goal
MKES Morrison-Knudsen Enviro=ental Services
NBCS North Boundary Containment System
NDMA N-nitrosodimetliylamine Plan NCP National 00 and Hazardous Substances Pollution Contingency
NEPA National Environmental Policy Act
NT L National Priorities List
NR%'BCS Northwest Boundary Containment System
OW Operation and maintenance
OCP Organochlorine pesticide
ou Operable unit
PRP Potentially responsible party
PVC Polyvinyl chloride
RfD Reference dose
RWFS Remedial invest igat io rx/feas ib ility study
RM.A Rocky Mountain Arsenal
R11v1E Reasonable maximum exposure
ROD Record of Decision
12-2 Harding Lawson Associates '21905 402010 1107121495 R02 Glossary
and Sanitation District SACWSD South Adams County Water
and Reauthorization Act SARA Superfund Amendments
Shell Shell Oil Company
UFS Unconfined flow system
WWC Woodward-Clycie
per liter ,vg/I Micrograms jjgýkg Micrograms per kilogram
Lawson Associates 12-3 '21905 402010 Harding 1107121495 R02 13.0 BIBLIOGRAPHY
City of Commerce City. 1990. Airport Environs Adams County, City of Aurora, City of Brighton, Concept Plan, Brighton, Colorado. County Future Land Use Plan, Brighton, CO. Adams County Planning Cominission. 1987. Adams Airport Environmental Assessment, Camp Dresser & McKee, Inc. 1993. Stapleton International Airport, City and County of Denver. June 15. Northern Zone. Prepared for Stapleton International Gas Investigation, Final Summary Report. Ebasco Services, Inc. 1988. Western Tier TCE Soil January. Arsenal Draft Final Water Inc. 1989. Technical Support for Rocky Mountain Ebasco Services, and DAAA15-88-DO024. Remedial Investigation Report. Contract Nos. DAAK11-84-DO016 Denver. CO. Rocky Mountain Arsenal Offpost Assessment: Environmental Science and Engineering, Inc. 1985. 1) for Sampling Period December 1984 Ground Water Quality Report (Consumptive Use - Phase and Hazardous Materials Agency. Denver, CO. through January 1985. Prepared for U.S. Army Toxic Rocky Mountain Arsenal Offpost Assessment: Environmental Science and Engineering, Inc. 1986. II) for Sampling Period September through Ground Water Quality Report (Consumptive Use - Phase Order 0006. Denver, CO. October 1985. Contract No. DAAK-11-D-007, Task Rocky Mountain Arsenal Offpost Assessment, Environmental Science and Engineering, Inc. 1987a. prepared for the Office of the Program Contamination Assessment Report: Draft Final, Denver Manager. Rocky Mountain Arsenal. Mountain Arsenal Offpost Assess-ment: Enviroruxiental Science and Engineering, Inc. 1987b. Rocky Sampling Period September through Ground Water Qualitv Report (Domestic Use - Phase III) for 1-83-D-007, Task Order 0006. October 1986 and Februarv 1987. Contract No. DAAK-1 Operable Unit Remedial Investigation Enviro=,ýntal Science and Engineering. Inc. 1988a. Offpost Requirements, Final Report. Prepared and Chemical Specific Applicable or Relevant and Appropriate Lawson Associates; and Applied Environ- bv Environmental Science and Engineering. Inc.. Harding 3 volumes. mental. Inc.. Rockv Klountain Arsenal. Commerce City. CO. Remedial Investigation Report, Final. Environmental Science and Engineering. Inc. 1988b. Air Prepared frr Office of the Program Manager. Denver. CO. Final Endangerment Assessment/ Environmental Science and Engineering. Inc. 1989. Draft Requirements. Prepared for Office of Fe,isibility Study and Applicable or Relevant and Appropriate the Program Manager. Denver. CO. 120, Docket No. CERCLA VIII-89-13, Federal Facility Agreement. 1989. Pursuant v, CERCLA, Section Protection Agency, U.S. Environmental signed by U.S. Department of the Arm\-. U.S. Environmental Fish and Wildlife Service, Agency Protection Agency Region VIII, U.S. Department of Interior, U.S. Justice, and Shell Oil Company. for Toxic Substances and Disease Registry. U.S. D-partment of the Groundwater Intercept and Harding Lawson Associates 1989. Final Decision Document for Response Action. Treatment Svstem North of Rocky hlountain Arsenal, Interim
Harding Lawson Associates 13-1 '21905 402010 1107121495 R02 Bibliography
Document for the Groundwater Intercept Harding Lawson Associates. 1991. Final Implementation Arsenal, Interim Response Action. and Treatment System North of Rocky Mountain Operable Unit, Endangerment Assessment/Feasibility Harding Lawson Associates. 1992a. Offpost Study, Final Report, 8 volumes. Addendum, Operable Unit Remedial Investigation, Final Harding Lawson Associates. 1992b. Offpost 2 volumes. 1990a. Implementation Document for Northwest Morrison-Knudsen Environmental Services. June. Boundary System Short-term Improvements IRA. Report of Field Investigations, Assessment, and Morrison-Knudsen Environmental Services. 1990b. System Short-term Improvements Interim Final Decision Document for the Northwest Boundary Response Action, RMA. June. Implementation Document for the Northwest Morrison-Knudsen Environmental Services. 1992. Final Report. January Boundary System Long-term Improvements ERA Northwest Boundary Containment System Long- Morrison-Knudsen Environmental SerArices. 1993. July. term Improvements IRA One-year Evaluation Report. Persistence of Organoclorine Insecticide Residues Mullins, D.E., Johnsen, R.E., and Starr, R.I. 1971. 5: 268-275. in Agricultural Soils of Colorado. Pest. Monit. J. Monitoring Program; Air Quality Data Assess- R.L. Stollar & Associates, Inc. 1990. Comprehensive Prepared for U.S. Army Program ment Report for 1989. Contract Number DAAA15-87-0095. CO. Manager for Rocky Mountain Arsenal. Commerce City. Compliance with Other Laws Manual Draft, U.S. Environmental Protection Agency. 1988a. CERCLA OSWER DLrective 9234.1-01, August. on Remedial Actions for Contaminated U.S. Envi:onmental Protection Agency. 1988b. Guidance August. Grcundwater at Superfund Sites. OSWER Directive 9283.1-2. for Conducting Remedial Investigations and U.S. En-.-Lro=ental Protection Agency. 1988c. Guidance October. Feasibility Studies Under CERCLA. Interim Final. EPA/540/G-89004. Guidance for Superfund, Volume 1., U.S. Environmental Protection Agency. 1989a. Risk Assessment Human Health Evaluation Manual (Part A). Interim Final. EPA/540/1-89/002. Handbook. Final Report, Office of U.S. Environmental Protection Agency. 1989b Exposure Factors Health and Environmental Assessment. EPk/600/8-89/043. for Chemical Sales Company, U.S. Environmental Protection Agency. 1991 a. Record of Decision Operable Unit 2. June 27, 1991. for Chemical Sales Company, U.S. Environmental Protection Agency. 1991b. Record of Decision Operable Unit 3, June 27. 1991. for Chemical Sales Company, U.S. Environmental Protection Agency. 1992. Record of Decision Operable Unit 2, December 29. 1992.
Harding Lawson Associates '21905 402010 13-2 1107121495 R02 Sibliograph
Improvements Interim Response Woodward-Clyde. 1991a. Northwest Boundary System Long-term Action B(ii) Final Assessment Document. June.
Boundary System Rocky Woodward-Clyde. 1991b. Proposed Decision Document Northwest Action. June. Mountain Arsenal Long-term Improvements Interim Response
Associates 13-3 '21905 402010 Harding Lawson 1107121495 R02 of Concern Table 6.1: Offpost Operable Unit Groundwater Chemicals
Exposure Point Concentration ("011 3 Zone 4 Zone 5 Zone 6 Chemicals of Concern Zone 1 Zone 2 Zone 0.050* 0.12* 0.039* 0.030* Aldrin 0.029* 0.045* --- 2.15 1.63 - 2.78* 2.68* Arsenic 4.48* 2.87 5.31* 12.9* 7.36* - Atrazine 0.75 0.93 ------Benzene 0.61 0.64 0.76* --- - Carbon tetrachloride ------0.18* 0.19* 0.54* -- Chlordane --- 660,000* 262,000* 191,000 Chloride 120,000 205,000 487,000* 1.77 4.51 1.09 1.27 Chlorobenzene 1.02 1.78 5.01 1.51 12.0* 3.33 Chloroform 0.68 67.5* --- 14.5 10.4 7.68 --- CPMSCI ------4.35 6.63 5.09 --- CPMSO, 0.14 0.15 0.10 Dibromochloropropane --- 0.44* --- 0.77* 0.92* 7.32* --- 1,2-Dichloroethane ------3.64 163* 66.6* --- Dicyclopentadiene ------0.029 0.029 0.22* 0.085 DDi --- 0.037 0.033 0.11* 0.10 DDT --- 2.9 ------Dichlorobenzene --- 5.1 590* 4950* 7.68 4.67 DIMP 63.3* 713* 0.034* 0.035* 0.21* 0.055* 0.071* 0.039* Dieldrin 1.97 4.22 ------Dithiane - - 0.058 Endrin 0.033 0.037 0.73* - --- 0.57 --- -- Eth,.,Ibenzene -- 1810 2230* 1830 2210* 3510* 3290* Fluoride --- 0.029 0.033 0.044 0.043 0.035 Hexach.lorocyclopentadiene --- 0.040 Isodrin 0.028 0.035 0.047 0.057 0.38 0.32 ------Nlalati-uon --- 0.26 1580 --- 1250 670 --- Nlanganese --- 1.32 2.21 ------Oxathaane --- - 340.000' 636.000* 909.000' 1,118,000* 148,000 213,000 Sulfate 0.75 1.67 Tetrachioroethene 0.70 10.1 20.7* 6.09* 1.28 1.18 ------Toluene ------0.64 0.51 2.70 --- 4.04* Trichloroethene --- 1.11 --- Xvlene 0.75 ---
Not a chemical of concern in this zone CPMSCI 4-chlorophenylmethyl sulfoxide CPMSCI, 4-chlorop henylm ethyl sulfone DDE 2,2-bis(p-chlorophenyl)-I,l -dichloroethene DDT 2.2-bis(p-clilorophenyl)-1,1.1 -trichloroethane DIMP Diisopropylmethyl phosphonate Pg/1 Micrograms per fiter
Exceeds groundwater containment system remediation goal listed in Tables 7.1, 7.2, and 7.3. mean of All exposure point concentrations represent the upper 95 percent confidence limit on the arithmetic measured concentrations in monitoring and private wells. Associates '21905 402010 Harding Lawson 1107121895 R02 of Concern Table 6.2: Of1post Operable Unit Surface-Water Chemicals
Exposure Point Concentration (ugjj)' CAnAl Chemicals of Concem Fftst Creek lnig&tion
Arsenic 18 NE Chlordane 0.18 NE Chloride 206,000 NE Dicyclopentadiene 10 NE DDE 0.089 NE NE DDT 0.046 Dieldrin 2.6 NE 20 DRvfP 230 Fluoride 2550 970 Sulfate 438,000 NE
DDE 2,2-bis(p-chlorophenyl)-1,1-clichloroethene DDT 2,2-bis(p-chlorophenyl)-1,1.1-trichloroethane DIMP Diisopropy1methyl phosphonate in the irrigation canals NE Chemical not significantly elevated above background levels JjS!1 Micrograms per liter limit on the All exposure point concentrations represent the upper 95 percent confidence samples. arithmetic mean of measured concentrations in unfiltered surface-water
Associates '21905 402010 Harding Lawson 1107121495 R02 of Concern in First Creek Table 6.3: Offpost Operable Unit Sediment Chemicals
Exposure Point (mg/kg )a Chemicals of Concern Concentration
Aldrin 0.011 Dibromochloropropane 0.099 Dieldrin 0.134 Endrin 0.0038 DDE 0.0005 DDT 0.0084
DDE 2,2-bis(p-chlorophenyl)-1,1-clichloroethene DDT 2,2-bis(p-chlorophenvl)-1,1,1-tricWoroethane mg!l-,g Milligrams per kilogram limit on the All exposure point concentrations represent the upper 95 percent confidence arithmetic mean of measured concentrations in sediment.
Associates '21905 402010 Harding Lawson 1107121495 R02 of Concern Table GA: Offlaost Operable Unit Soil Chemicals
Exposure Point Concentration fm-ARIý- Chemicals of Concern Zone 3 Outside Zone 3
Aldrin 0.014 0.0021 Chlordane 0.049 ND Dieldrin 0.112 0.018 Endrm 0.032 0.0042 DDE 0.024 0.015 0.030 DDT 0.063
DDE 2,2-bis(p-chlorophenyl)-1,1-dichloroethene DDT 2.2-bis(p-chlorophenyl)-1,1,1-trichloroethane mg/kg Milligrams per kilogram ND Chlordane not detected in soil outside zone 3 confidence hmit on the All exposure point concentrations represent the upper 95 percent arithmetic mean of measured concentrations in sod.
'21905 402010 Harding Lawson Associates 1107121495 R02 Exposure Routes by Zone Table 6.5: Summary of Land-Use Scenarios and
Quantified Scenario Zone Exposure Routes
soil Rural residential 1,2,6 Dermal, inhalation, groundwater Oral, dairy Oral, eggs Oral, groundwater Oral, meat Oral, soil Oral, vegetables
Urban residential 3,4 Dermal, soil Dermal, sediment Dermal, surface water Inhalation, groundwater Oral, groundwater Oral, sediment Oral, soil Oral, vegetables
Commercial and industrial 5 Dermal, soil Inhalation, groundwater Oral, groundwater Oral, soil
Associates '21905 402010 Harding Lawson 1107121495 R02 of Concern Table 6.6: Reference Doses and Slope Factors for Chemicals
Noncarcinogenic Carcinogenic Chronic RMD Slope Factor sL (myAxLday)' fmp-/k dayl Carcinogenic Chemicals Weight-of-Evidence of Concern Oral Inhalation Oral Inhalation 1.7E+1 B2 Aldrin 3E-5 NE 1.7E+1 5.0E+1 A Arsenic 3E-4 NE 1.75 NE C Atrazine 5E-3 NE 2.2E-1 2E-2 NE 2.9E-2 2.9E-2 A Benzene B2 Carbon tetrachloride 7E-4 NE 1.3E-1 5.313-2 1.3 B2 Chlordane 6E-5 NE 1.3 NA NA Chloride 7.1 NE NA NA NA Chlorobenzene 2E-2 5E-3 NA 8.iE-2 B2 Chloroform 1E-2 NE 6.1E-3 NA NA CP?VlS0 2E-2" NE NA 2E-2a-b NE NA NA NA CPNIS02 B2 5E-3 5.7E-5 -1.4 2AE-3 Dibromochloropropane C 1,2-) 9E-2 4E-2 2AE-2 NE Dichloroberizenes (as B2 5E-4 NE 3AE-1 3-4E-1 DDE B2 5E-4 NE 3AE-1 3-4E-1 DDT B2 7E-2 NE 9.1E-2 9.1E-2 1,2-Dichloroethane NA Dicyclopentadiene 3E-2 6E-5 NA NA 1 B2 Dieldrin 5E-5 NE 1.6E-i 1.6E+ 8E-2' NE NA NA NA DIMP NA 1.4-Dittuane 3E-16 NE NA NA 3E-4 NIE NA NA NA Endrin NA Ethvlbenzene iE-1 3E-i NA NA 6E-2 N-E NA NA NA Fluoride NA HexacWorocyclopentadiene 7E-3 NE NA NA 7E-5' NE NA NA NA Isodrin NA Malath.ion 2E-2 NT NA NA 1E-1 1 1F-4 NA NA NA Manganese NA 1,4-Oxathiane 3E-1' NE NA NA 1-1E+1 \E NA NA NA Sulfate B2 Tetrachloroethene 1E-2 IE-2 5 iE-2 1.8E-3 2E-1 1-ff-i NA NA NA Toluene B2 Trichloroethene 4E-14 4F.1 i iE-2 1.7E-2 NA Xvlene 2 8.6E-21 NA NA
Weight of Evidence Classification A = Human carcinogen are available. B2 Bi or B2 = Probable human carcinogen. B1 indi::al"s that limited human data indicates sufficient evidence in animals and inadequate or no evidence in humans. C Possible human carcinogen
Associates I of 2 '21905 402010 Harding Lawson 1107121495 R02 Table 6.6 (continued)
CPMSO 4-chlorophenvimethyl sulfoxide CPMS02 4-chlorophenylmethyl sulfone DDE 2,2-bis(p-chlorophenyl)-1,1-dichloroethene DDT 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane DIMP Diisopropylmethvi phosphonate mg/kg/day Milligrams per Idiogram. per day NA Not applicable NE Not established RfD Reference dose other than EPA. a. Derived from scientific literature or obtained from agencies was issued (see letter dated b. Subsequent to this assessment, a Region VIII Health Advisory the other parties. The other januarv 27, 1994). This Health Advisory has not been reviewed by Reference to these values parties may provide comments to this Health Advisory in the future. constitute agreement by other from EPA Region VIII's Health Advisory in this document does not parties. The Region VIII Health Advisory values are as follows:
10-Dav Longer-term
Child 0.2 nigil 0.02 mg/1 Adult 0.6 ni&I 0-06 mo
c. This RFD is taken from the 1989 EPA Health Advisory for DIMP.
2 Harding Lawson Associates '21905 402010 2 of 1107121495 R02 Carcinogenic Risks Table 6.7: Summary of Reasonable Maximum Exposure by Zone and Exposure Route
Exposure Route Exposure Assessment Zone Ingestion Inhalation Dermal Total
1A* 1.1E-4 8.7E-7 1.OE-7 1.1E-4 1B* 1.3E-4 8.7E-7 1-OE-7 1.3E-4 1C* mE-4 8.7E-7 1.OE-7 1.113-4 2 1.6E-4 6.6E-5 1.OE-7 2.3E-4 3 2.5E-4 6.5E-6 1.3E-6 2.613-4 4 2.1E-4 1.OE-5 7.3E-7 2.2E-4 5 2AE-5 3AE-6 6.7E-8 2.7E-5 6 6.9E-5 4.OE-6 1.OE-7 7.3E-5
whether the ditch water Zone 1 is subdivided on the basis of the presence of surface water and First Creek. used for irrigation is collected upstream or downstream of the mouth of
'21905 402010 Harding Lawson Associates 1107121495 R02 of Adult Reasonable Maximum Exposure Noncarcinogenic Table 6.8: Summary Zone Hazard Indices by Tarqet Organ and Exposure Assessment
Exposure Assessment Zone Target 3 4 5 6 Organ 1A 1B ic 2
1.7E-3 1.8E-3 1.7E-3 1.9E-3 2AE-3 2.9E-3 Blood --- 2.5E-2 1.6E-2 2.OE-2 1.6E-2 3.8E-2 9.OE-2 5-4E-2 Cardiovasculax 6.6E-2 1.6E-3 2.4E-2 2.6E-2 2.3E-2 8.4E-1 2.4E-1 2.4E+O CNS 4.9E-5 --- 1.5E-4 3.1E-4 1.5E-4 3.5E-4 4.3E-4 4.2E-4 Gastrointestinal 7.2E-2 2.OE-1 1.8E-1 2.1E-1 1.8E-1 1.1E+0 1.3E+o q.oE-1 Hepatic 3.1E-4 2.8E-4 ------Ocular ------8.1E-2 1.1E-1 2.OE-2 8.8E-1 Renal 7.OE-3 7.4E-3 7.OE-3 2.3E-1 5.8E-4 2.8E-3 RespLratory 2.4E-4 2.4E-4 2.4E-4 2.3E-4 2. 3E-2 3.1E-1 8.7E-2 --- Skin 2.OE-1 2.3E-1 2.OE-1 1.7E-1
--- Chemicals for this target organ not detected in this zone CNS Central nervous system
Lawson Associates '21905 402010 Harding 1107121495 R02 Goals for the Table 7.1: Containment System Remediation Offpost Groundwater Intercept and Treatment System
Rural Residential Hypothetical CSRG PQLa Cancer Risk b Analyte Ujg/l) Source
0.4 CBSG 1.Or 9.1 x 10-1 1,2-Dichloroethane NA 1,3-Dichlorobenzene 6.5 HBC 1,4-Oxathiane 160 HBC NA 10-7 0.002 CBSG 0.05d 4.0 x Aldrin NA Atrazine 3 MCL, CBSG HBC 2.0 x 10" Benzene 3 7.9 x 10-7 0.3 CBSG 0.99d Carbon tetrachloride 5.7 x 10*7 0.03 CBSG 0.095 d Chlordane NA Chlorobenzene 25 HIBC 6.4 x 10-6 Chloroform 6 CBSG HBC NA CPMS 30 36 HBC NA CPMSO NA CPMS02 36 HBC 0.2 MCL, CBSG 3.8 x 10'6 DBCP NA DCPD 46 HBC 0.1 CBSG 8.5 x 10-7 DDE CBSG 4.1 x 10,7 DDT 0.1 d 1.2 x 104 Dieldrin 0.002 CBSC 0.05 8 CBSC NA DIMP NA Dithiane 18 HBC 0.2 CBSC NA Endrin NA EthN-lbenzene 200 HBC NA Hexachl-orocyclopentadiene 0.23 HBC 0.06 HBC NA lsod-rin NA Nialathion 100 HBC 1*,) 0.033 1.0 X 10-5 N'D NtA 0.007 4.0 x 104 TeLrachloroethylene 5 MCL. CBSC NA Toluene 1.000 %1CL. CBSC fiRC 9.9 X 10,7 Trichloroethviene 3 NA XvIenes 1.000 lific 5.6 x 10" Arseruc 2.35 1IBC NA Cli.loride 250.000' CBS(" NA Fluoride 2.000 CBSG NA Sulfate 250.OOV CH.SG Totalh 8.8 x 10*'
Lawson Associates '21905 402010 Harding 1107121495 R02 Table 7.1 (continued)
to reduce overall risk: arsenic The following chemical have ARARs that were adjusted downward and xylene. benzene, chlorobenzene, 1,3-dichlorobenzene, trichloroethylene,
CBSG Colorado Basic Standards for Groundwater CPMS 4-chlorophemylmethvl sulfide CPMSO 4-chlorophenvlmethyl sulfoxide CPMS02 4-chiorophenvimethyl sulfone CSRG Containment system remediation goal DBCP Dibromochloropropane DCPD Dicyclopentadiene DDE 2,2-bis(p-chlorophenyl)-1,1-dichloroethene DDT 2.2-bis(p-chlorophenyl)-l .1,1-trichloroethane DIMP Diisopropy1methyl phosphonate HBC Health-based criteria NICL Maximum containment level NA Not applicable NDMA N-nitrosodimethylamine PQL Practical quantitation limit .us/, Micrograms per liter than the CSRG. a. Practical quantitation limit; presented only when the PQL is greater b. Based on the CSRG. c. PQL listed in the CBSG standards d. PQL attainable by the U.S. Army per trillion (ppt) in the e. The remediation goal for NDNtA was established at 0.007 parts 0.033 ppt. The estimated Conceptual Remedy Agreement. The current PQL readilv available is risk associated with NI)MA is based on a 70-year residential exposure duration. with the onpost f. Inorganic standard for chloride wi!I be met bv natural attenuation consistent remedial action. which will be S. Inorgaruc standard for sulfate may be the natural background concentration, established and met by natural attenuation consistent with onpost remedial action. maximum risk Because of the variability in contaminant distribution and concentration, the h. at any one associated with the groundwater cleanup concentrations is not expected to occur location.
Harding Lawson Associates '21905 402010 2 of 2 1107121495 R02 Goals for the Table 7.2: Containment System Remedlation North Boundary Containment System
Rural Residential CSRG Hypothetical PQV Cancer Risk' Analyte (119/1) Source I.Oc 9.1 x 10-1 1,2-Dichloroethane 0.4 CBSG 70 CBSG NA 1,2-Dichloroethylene NA 1,4-Oxathiane 160 H13C 0.002 CBSG 0.05d 4.0 x 10-' Aldrin NA Atrazine 3 MCL CBSG BBC 2.0 x 10'6 Benzene 3 10-7 CBSG 0 .99d 7.9 x Carbon tetrachloride 0.3 6 CBSG 6.4 x 10-6 Chloroform NA CPMS 30 HBC 36 HBC NA CPMSO NA CPMS02 36 HBC 0.2 MCL CBSG 3.8 x 10-6 DBCP NA DCPD 46 HBC 0.002 CBSC 0.05 d 1.2 x 10-6 Dieldrin NA DIMP 8 CBSC 18 HBC NA Dithiane NA Endrin 0.2 CBSC 0.06 KBC NA Isodrin NA - Malath.ion 100 HBC 5.0 MCL. CBSC NA MethvIene chloride 1.0 x 10" 0.007 (e) 0.033 NDNL-% 4.0 x 10-6 Tet.rachloroethvlene 5 MCL. CBSC MCL. CBSC NA Toluene 1.000 9.9 X 10.7 3 HBC Trichloroethvlene NA XvIenes 1.000 IIBC 5.6 x 10-' Arsenic 2.35 IIBC NA Chloride 250.00W C.BSC. 2.000 CBSG NA Fluoride NA Sulfate 250.0001 CBS(; Totalh 8.0 x 10-'
anomalies are anticipated Nlethvlene chloride is a common laboraton, cn.-.Iiminant and analytical during compliance monitoring. overall risk: arsenic The following chemical have ARARs that wpre at] justed downward to reduce benzene, chlorobenzene, trichloroethylene.,ind xylene.
Associates '21905 402010 Harding Lawson 1107121495 R02 Table 7.2 (continued)
CBSG Colorado Basic Standards for Groundwater CPMS 4-chlorophenylmethyl sulfide CPMSO 4-chlorophenylmethyl sulfoxide CPMS02 4-chlorophenylmethyl sulfone CSRG Containment system remediation goal DBCP Dibromochloropropane DCPD Dicyclopentadiene DIMP Diisopropylmethyl phosphonate HBC Health-based criteria MCL Maximum containment level NA Not applicable NIDMA N-rutrosodimethylamine PQL Practical quantitation limit ilg1l Micrograms per liter than the CSRG. a. Practical quantitation limit; presented only when the PQL is greater b. Based on the CSRG c. PQL listed in the CBSG standards PQL attainable by the U.S. Army d. (ppt) in the remediation goal for NDMA was established at 0.007 parts per trillion e. The The estimated Remedy Agreement. The current PQL readily available is 0.033 ppt. Conceptual duration. risk associated witfi NDMA is based on a 70-year residential exposure consistent with the onpost f. Inorganic standard for chloride -will be met by natural attenuation remedial action. which will be g. Inorganic standard for sulfate may be the natural background concentration, remedial action. established and met bv natural attenuation consistent with onpost the maximum risk h. Because of the variabilitv in contaminant distribution and concentration, to occur at any one associated -with the groundwater cleanup concentrations is not expected location.
Lawson Associates '21905 402010 2 of 2 Harding 1107121495 R02 Table 7.3: Containment System Remediation Goals for the Northwest Boundary Containment System
Rural Residential CSRG Hypothetical Analyte Rg/l Source POLa Cancer Risk b
Chloroform 6 CBSG 6,4 x 10-6 DIMP 8 CBSG NA Dieldrin 0.002 CBSG 0.050 1.2 x 10-6 Endrin 2.0 CBSG NA Isodrin 0.06 HBC NA NDMA 0.007 (d) 0.033 1.0 x 10-5 Trichloroethylene 3 HBC 9.9 x 10-7
Arsenic 2.35 HBC 5.6 x 10-5
Totale 7.5 x 10-5
The following chemicals have ARARs that were adjusted downward to reduce overall risk. arsenic and trichloroethene
CBSG Colorado Basic Standards for Groundwater DIMP Diisopropylmethyl phosphonate HBC Health-based criteria MCL Maximum contaminant level NA Not applicable NDMA N-nitrosodimethylarnine PQL Practical quanititation limit j.tg/l Micrograms per liter a. Practical quanititation limit; presented only when the PQL is greater than CSRG. b. Based on on the CSRG c. PQL attainable by the U.S. Army d. The remediation goal for NDMA was established at 0.007 ttg/l (7 parts per trillion (ppt)) in the Conceptual Remedy Agreement. The current PQL readily available is 0.033 l.Lg/l (33 ppt). The estimated risk associated with NDMA is based on a 70-year residential exposure duration. e. Because of the variability in contaminant distribution and concentration, the maximum risk associated with the groundwater cleanup concentrations is not expected to occur at any one location.
21905 402010 1107121495 R02 Revised 4/23/01
G9900667 Table 7.4: Groundwater Alternatives for the North and Northwest Plume Groups
Rochargo ExIniclions Wolls/1'renchos Roniodiolion Troalmont Wells (tolal onoilior/ Flow Role Tiniefriinio Facility Residuals Gonorntool 14111111longl1i) (gliIII) (years) Location AlInrualiva' l1rocaq.-i ()pIhmq Ilidmiclionnol (lotal numbor)
NOTIII 111mim (;rotili NIA Norio N Norio Norio N/A Unknown N-1 No aclloii NI(Illiloillig still I-(:, Flivillws
to 30+ NBCS No additional N No adilitloital No addillonal 240 15 N-2 Coillilmod o1mratism (if lho NBCS Nll(:s olintalloo FC. W illi 11111IFovolikoills as 1111cossary (%4,111141111olillo 1'.1111or. catboll ad'I'l III loo)
carbon 1; trovichos/15I)o foot 180 15 to 30 T2S, R67W, Spent 0-1.1.11ill 1,111.111114.111 Call'oo Ailsorlillon R" 5 N 4 ()fflloýl 300 Sec. 14, NII(.S opol,1111111 N 12 SYS111111 NE 1/4 Sec.
10to 20 T2S, ROM Sprint carbon H; 7 10 trenches/ 240 N. 5 Expalisloll of 1111%0111,05t IIIIIIII-01.1 Callioll nikorl,11,111 2700 foot Sec. 14, lid I Svýlmo NIICS oliot,01(m a NE 1/4 Sec. N 13 2 Irmichos/600 foot 330
Nor Ihwost I'limin Grolill Unknown N/A Norio NW Norio Norio N/A NW-1 No aclioo Moniloring silo ravlows
3 to 8 NWBCS No additional NW No additional No additional 850 NW-2 Con(iound oparallon of tire NW13CS NWBCS operation Willi I Inprovoll 1011Is as iiricossary
M First Crook 81)111 Gallons per minuto N/A Not applicable N Noriliorn NBCS North Botindary Contalieniont System NW Norlliwost NWBCS Nor(liwest Boundary Cooldilluio"t Syste",
and site reviews. * All n1tornatives inchido gromidwator monitoring
'21905 402010 1107121495 R02 for the Horth Plume Group Table 8.1: Summary of the Detailed Analysis and Ranking of Groundwater Alternatives
Alloritioliva N-2 co-Aiinuail olipernflion Alternative N-5 if( Iloo Ncirlit Hoostoodatery Allarnistiva N-4 Offloost Intercept And Expansion 1 to Interim Alloruntivoli N- I cionininniont System Willi Response Acliun A &t%Nocnspinry Tronituant Systant CrIlarla Nip Acllf)n
polontial risk This alternative rodiices potontial risk Tl&; alitimativii loriMiliv; 11milod ovorall loioloc- This allornalive reduces Ovorall proloclimi of I'llis alloillativ(W %voillilllill protection of both human fillet life$ flilvitiollifloill by Rill] provides prollicilon of both 1111111an still provides I I a I I (I provillo piroloclion of 1111111nil 11(111of 1111111all 111talill II I I of I it f 1 1141.1It by remedla- health anti ilia environment by pinvolitills Illigiallon of Collin 11111131115 flout health and ilia environment fill, AlIvirollninill lillidill atoll title folivilmlilloild. romedialing North Plunin Groiire MKIA lie dole I Mlifi%l Stiffly Atom n(irth of title thig North Mallon Group gromidwalor RMA to groundwater anti groundwator NOCS. llointillal risk nssiocialml with and groundwater migrating front Arna. migrating from RMA to ilia Offroost FtIO411111W.11411' lit Ilin Nonl1i I'limait Gamilp wmild Ilin Offliost Study Sliidy Area. (IM-roa%" oval 1111611.
wnuld 110 GI- Chomical-specific ARARs wotil(i be C.6-iiiii oil pecific ARAIN wootild lie allahind lit ChninicnI-sporicific ARARs 011111111.111(ol lVith 1111,6 dil-.111.011v" 1, $fill Approximately 10 to 20 ye- Vents. As asilinalatl laino(l In approximately 15 to 30 years. Attained In 4.%l I-I I., Al 4111,1(11411114114V 15 to :11111111"1 ARAM% by grourldwalor modeling. ars, as estimated by groundwater AKARý I.v as estimated i lipAiii it 1-. Ill. otiodeling.
rOduCn residual Through treatment. this allernnilve 1111% 4110111.111vis %V11111.11414111111 146,14111ill THA 'rills n1loornallve woidd Linig-torin MI'm live- 1111-t All-111411va in's-11.1 Iva residual risk Associated Ontilp risk associated with North Plume Group would reduce Allot 1-111. 0 Ilia 1-1,11141 0.11 4-opf 141pol witli Nuilli Pitima 114154 throtigh operation of do" with North Plume Group groundwater .11-f 1111-1161111w4l"t 11V 11111viosill"R groundwalor, is5 -.1." 1.110.1 %.11 Is of ...IlA% through operation of Ilia NBCS, ilia wilitiAlinot at Ilin NIICS Allot c(toillotooliog toichargo Nll('.S slid ilia Olfpost Intercept anti to Offposl Intercept and Treatment off Ill'.114,11 Ftollioll.1wallit lit 1111%11 Tr6alment System and Improvolmonts System. and file Expansion I system. lie lhop Mollie ['fifteen Giciiiii. both systems as necessary.
treatment, this alternative Through treatment, this alternative wollIll not 'rills all(Itilillivo wollid radlice I(Imicity, Thl-ough l1whicilon of inobil- 'rills allorlinlivo toxicity, mobility. groundwater migrating would reduce toxicity, mobility, still would reduce the Ity, toxicity, or 01111110Y ally lefoatillout mobility, still volume of the volume of groundwater within the North and volume of groundwater within procoss Options Allot woltill front RMA to Ilia Offposl Study Area. volumn Plume Group said groundwater migrating North Plume Group and groundwater nol rediice toxicity, mobility, Offp- front RMA to ilia Offposl Study Area. migrating from RMA to the or volmno of gromidwah,r cest Study Area. within (lie North Illume Grnulo or gioundwalor migrating from RMA to Ilia Offliost Study Area.
1 of '21909 402010 1107121495 R02 Table 8.1 (continued)
Allitrowlive N-2 01111illund ()IOnrilli(In oil thit Notrilt Ilsoustilory Allornalivii N-4 Alternative N-5 Expansion. I tooInterins Allpritiolivo N- I 0111111iiIIII0111 SY-111311 Willi Offliost Intercept and Trovillin"DI System Response Action A Criteria No At lime n% Npcot%siory
workors wore protected Community and workers would be pro- Ito 14,111(illial ;it lifill %voidilIm titi shmi-itirot Impacts bocalis" C0111111111111y and Sholl-torin Offoclivoo- 1141callsil through Thoro would by adhering to standard health and locled during construction 11OSS WO%11(1bn polfolinfid. 111olo Iliff NOCS 1,; alinativ (iiiiiialitig. The Implementation adhering to standard health and safety woldil Im 114)"11(ill Wrill III) Ito iIIIIII(IIII"Illilliou polioll. safety practices. and the sysiont is practices. The Implementation period Impacts. There would 1111Ito porlool Is coinpliflo would be approximately 14 months. hoplonlolitatioll 111111o.l. fully operational. Is readily inijilmotaiiiahlo. TLIS alternative Is readily This alternative 11111114.111flolabilliv '141,1111ir'll fol.1sillilliv %V"111.1 This n1fortintivo ii roashly Technical and imploutentablo. However, Ilia I...Itifth I ho itivo '14whilical aild .111111illklialivo folasibillty woul4l IInp 101110111 abio. would be high. construction would be conductod it) f".1'Ohilliv %Volilil 1.0 110%v. 110 111811. adukinisli-1111VO feasibility Iwo time perlods due to the design phass far the expansion. Technical atid administrative feasibility wmild be high.
Total Capital Cost = $16.7 million 'rotal capital cost - $19.4 million I"SlItIvilod cOft 11 Tiptal Capilal Cost = S -D.
Long-term O&M Cost = $39.8 to Total Long-term O&M Cost uoog two, ()&M Total Long-term O&M Cost - $30.6 to 32.5 Total 46.4 million $36.9 to 43.6 million Cost = $4.1 to (HI milhou million
Total Present Worth Total Present Worth 'rotal Ptosent Worth Total Prosoul Worth Cost = $56.5 to 63.1 million Cost = S.96.2 to 63 millinn Cost = $4.1 to 6.0 milliou Cost = $30.6 to 32.5 million
ARAR Applicable or relevant and appropriate requirement NBCS North Boundary Containment SYSIOIII 0& M Operation and maintenance RMA Rocky Mountain Arsenal
2 of 2 '21905 402010 1107121495 R02 for the Northwest Plume Group Table 8.2: Summary of the Detailed Analysis and Ranking of Groundwater Alternatives
Allarunfivoi NW-2 Continued Oporalitin (if the Northwest AlIntitalivo N%V-I 1114oundary Ciontninniont System With Improvements as Necassnry Crilorin Nov Actitin I
This would provide protection of human health and Ilia anvi- This .1111orlialivoi %voillilloot liToV1110 prolection of allooriiative M niall Pr(Ilecti(pli rof 1111111all 1111,11111 of coutnuil na tits from RMA to the Offpost Immaii health aitil 0sn 4invirimmmil. riviiiiiiiiii by preventing migration and Ibe 1-1,11VII0111110111 Sludy Area north of ilia NWHCS. Poloinlini risks associate(] with ilia North- west I'linno Group groundwater would be substantially reduced through coidbitiod operation of Ilia NWB(;S and finprovotmovids as necessary. Intl toosublown TIM allarlinliviv Is OX1100041 to innal or exceed chnnilcal-specific ARARs In Coempli.m(p Mob ARAR-t 'I111,ollolljoilve 1, ejoii w4pa, modelltie. . lwiow.ol qlww iflo- ARAR-%. approxinialoly flegs to eight years, as ost!uialod by groundwater alternative would reduce residual risk associated wilh groundwater AllefetAllve W40061.1 1111111111114 a lite sn.14111al This F114" .111.1 11.1, preventing conlantinant migration It.&4-ft 1.01...I wilh 114DIO-1111.11ItI41411141walell OXIHI- williles ilia Nc)rlltwosi I'linnot Gump throtigh 114-01.01 nt tits NWBCS and recharging Iroolod gromadwalor to Rush conlainhianig Its Ilm Northwest I'luato Group. would reduce toxicity, mobility, and volume or groundwater 111vil. liv. 11.1-411-1 16.111vto S."0111.1 11411101111DIVIV.111V Ign.111110111 This alternative 16(11101011 f)f from RMA to Ilia Offliost Study Area. Groundwater conlaudsiont 1-1- 0'. 411alloplis 41141 w(pilld lifol r1141114-0 ilia migrating V4111111141 Group by JIV. V1111111141lif FtI41111146.11tif concentrations would be reduced within ilia Northwest Plume at lite NWBCS. wilhin lite Noilliwesl I'llinin (4111111 (if Itill"Itil- flushing provided by recharge of treated water waint sisilltalhig fitim KNIA to Ilia Offilost Study Alan. Implementation be performed. There would be no short-term luipacls. There would he no Shorl-lorui E.11roiclivoinoss Because no remedial action wotild there would be no shriti-Intin Impacts. There period. would be no Implementation parind. This alternative Is readily implemontablov. Technical and administrative luiplonientability The technical feasibility would he high. The administrative feasibility would be low. feasibility would be high. Total Caplial Cost - $ -0- Estimated cost Total Capital Cost = $ -0- million Total Long-term O&M Cost = $0.6 to 1.3 million Total Lmig-torm O&M Cost = $12.4 to 13.1 million Total F'Fosont Worth Cost = $0.6 to 1.3 million Total Present Worth Cost = $12.4 to 13.1
1of2 '21905 402010 1107121495 R02 Table 8.2 (continued)
...... ARAR Applicaldo 1), NWIICS NoillmwA hollo-1-11 %,C-11-oll-11-1-1 (A m ()IIIII-al loll a Iol lo. RMA Rocky Momilalo Aiýno.sl
2 of 2 '21905 402010 1107121495 R02 Remedy Table 9.1: Estimated Costs of the offpost Operable Unit Selected
Cost'Component Alternative N-4 Alternative NW-2'
Capital Costs NA Monitoring well system $ 908,000 Offpost Intercept and Treatment 4,593,000 NA System extractionJrecharge system 4,106,000 NA Treatment facility NA Startup costs 341,000 NA Indirect costs 6.715.000 Total estimated capital costs $ 16,663,000 $0
Annual Operation and Maintenance Costs $ 352.000 $ 134,000 Groundwater monitoring 150,000 150,000 Site reviews and northwest boundary system North 769,000 operations 1,724,000 Offpost Intercept and Treatment 522.000 NA System facility O&M Offpost Intercept and Treatment System carbon replacementb 0 to 315 vears 817.000 NA 3/5 vears to system shutdown 227.000 NA Total estimated Annual O&M Costs 0 to 3/5 vears S 4.618.000 3,15 vears to svstem shutdown S 4.028.000 $ 1,053,000 Nonconservative' Conservative' Total remedv costs S 68.911,000 $ 76,143,000
Dl1,,1P Dusopropylinethyl phosphonate NA Not applicable O&M Operation and maintenance currently a. There are no capital costs for Alternative %NV-2 because the remedial systems are operational. decreases in b. The carbon usage rate is assumed to (i., '.rvas- %*,,r time ds a result of expected rate is influent DINIP concentration. Th-- duralr,n tJ It.ris- bofore a decrease in carbon usage expected to occur witiun three t(, t i,-- C. A range of total costs has been -islimai---l , ii 1b. basis of the range of expected remediation. tirueframes as estimated by the Sroun-i%%-.i1--r ruo-W r'-sults.
Associates '21905 402010 Harding Lawson 1107121495 R02 or Relevant and Table 10.1: Summary Evaluation of Chemical-specif Ic and Other Applicable Appropriate Requirements for the Off post Operable Unit
Applicable/ Relovank and Appropriate Roiluiraninot Slandliril, D"Scriplion Requirement Comment Critnria, or Hinihilloo
Ch"Inical-spocific AKAK% Grousidwalor fit the vicinity of ilia site 1-:,iablishos lotlotary M(.I.s for public walor- No/Yos Safn Dtinkitig Walsit Act 411 CFI( Is holng used or may he used as a Pail 141 source of water far puhlic water sysioul or privalo supply wells. Therefore, those pritnary MCI.s that are inore stringont than ilia Colorado Primary Drinklug Water Rogulations (hecause, Colorado has primary ouforcomont authority) are rolevald and appropriate.
Gromidwalor fit ilia vichilty of ilia silo l-'%talillhos (iionntifutconhle health guals) No[Yes 411( If( Is heing used or may he used as a S... 141 '-it im ImIslic %valo,rsvshimi. source of water for n public water A 11-1 14 1 .1 system or private supply wells. There- foro, fit accordance with the NCP, nonzoro MCLG9 are considered to he relevant and appropriate.
other AKARs State standards that are more siringoat I-Istalillshes slatowido standards for waters of ilia Yos/No Colorado Basic Standards 5 CGR 1002-8 than federal slandards are considorod state. for Gromidwater: Soclimi 3.11.0 at soq-1. applicablo. Colorado Basic Standards Socilon 3.1.0 at so(l. and Molhodologios for Surface Water
'21905 402010 1107121495 R02 Table 10.2: Summary Evaluation of Action-specific Applicable or Relevant and Appropriate Requirements for the Off post Operable Unit
Applicable/ Rolovoill and AppropFlolo Adion-spocific Siondoril, Roydrooov,"I riplion Comment cirlinrlit. or I-loolhill--n 4 iWom IJP%o
Federal ARARq Safo Drinking Wiloi Art 42 1 ISC Sol lillivi 111111iIn :111111,7
and Yos/No Applicable If reinjection wells/Ironclios are loloOlost 411 C FR Pa I 1 14 .1 lo 14 7 Foislillsheit ilidudards (fir construction discliargn of treated water: will IS/l g onc.bos usod for Kiiiiiiintion-i III it( 1110".111111 Coultul rolovai.1 and appropriate if some ollier ineiliod of reinjection is used.
I Indor tbo provisions of 40 CFR 144.13(l.). EPA lins doloruilned that Ilia reinjection wolls/itenclios used In conjunction wilb Ilia barrier Irealmen( system do not endanger underground sources of drinking walor. Tlio level of treatment prior to reinjection, offliost alinirnativo water supplies, and otbor remedies are sufficient to meal ilia requirements of Ilia UIC program.
Colfitailo Air Quailly CHS Sni-Iiiiii,; 25-7-101 In Slall(InFds 25-7-800 Yos/No Applicable to remedial action for tbe Offpost Colorado Ali Qiiallty Sots IIIIIIIS oil emission of odorous air Wor Emission 0U. Rogulallons Control Rogidallon No. 2 contaminants
ARAR Applicable or relevant and appropriate requirement CFR Code of Foderal Regulations CRS Colorado Revised Statues oti Operable unit EPA U.S. Environmental Protection Agoncy UIC . USC United States Code voc Volatile organic compound
'21905 402010 1107121495 R02 and Appropriate Table 10.3: Summary Evaluation of Location-specific Applicable or Relevant Requirements for the Offpost Operable Unit
Applicnidn/ Relovant and Appropriula Location-specific Roquiromouts Slandord, Rniluirmoont Description Comment Crilorlit, fir I.Indlislion Citalifill
Foilaral ARARx to be Idenliflod agnitclos to avold long- of short- Yes/No Requires a Soo-year floodplain EXIOCIIING 01,10F I ORR 4 11C FH I'a II 11. D114" 1,41`4111111,11 nod and considorod In scoping any remedial Alplitiodix A l"1111 11111141I's OýV)4.11116641 wilh of-1:11111111cy Flood P1.011 1`61.111.1g"1110111 ad lons. 08,40.11114 4111111 fir 4 (ICH1411114ill.
Yos/No Roquirninoos associated with this order 411 C IN hliwini7ws ilip dostioction. Ifiss. or dogradailoii of F110" Illiva 01016.1 1 Prul wotild ho applicabla to niq remedial actions If. Apl-e..hs A 1'4et that cmild affod lho exisliog wellands.
ARAR Applicallin for folow-lol .111-1 CFR Codel of 1`4116141 Holtol-Ili"11%
'21905 402010 1107121495 R02 8
Explanation Offpost Study Area
Offpost Operable Unit
......
......
......
P110
......
-"'NorthBoundary containment System
Northwest Bounder Containment System Onpost Operable nit Mfl Ave. Irondal* containment system
EPA Study Rocky Mountain Area Arsenal
CoffrMce Cey
RWA-Wo-u;ýda;;
owww
70 ScW* in
Stapleton International Airport
Figure 1.1
Rocky Mountain Arsenal Operable Units and Offpost Study Area North Boundary Containment System 8 ------
North Bog .22 Northwest Boundary Containrnent S am 23 /24 19 20
0, lmndaie Containment North System 27 Plants 25 29
//28
......
32 33 34 35 36 31
A I
6 5 4 3 Lake If RWI I I ciassirication t.. JL Lax@ ;:4ý _J Yard Malyll Suned Lake Buned Lake ow., ludge Area Sluage Area ýfj7ý Owby Rod and Gun Club 9 10 12 Poncr 7
------......
Explanation
Mapt potentW contaminant source area
Sanstary sewer system
...... Chemocai sewer system
0 0. 1.0
Scale in miles
Figure 2.1
Locations of Contaminant Source Areas 8
Barr Lake
N st =dya
0 1 2 ScWe in mHes
First Creek Pakmhannel Cc? Northern Paleochannei
rthwest Pakiochannel ýh Boundary Containment System
Northwest Bounds Containment System Onpost Study Area 80th Ave. Irondale Containment System
Explanation
Groundwaler flow cfrecbm
E]Northwest plume group
North plume group
Rgure 5.1 Contaminant Migration Pathways 0 3500 7000 Scale in teet
% % %% Sul .109
North Boundary Containment System
Northwest % Boundary Containment System
%P-Q
ExpLarurtion Zone I ;kosw tewcoma. iand use Zone 2 Rurw resecwcai Land use Zone 3 urimn resadiencaj land use
Zone 4 Urban residential land use
Zone 5 Commercial and industrial Land use
Zone 6 Rural residential land use
OtfPost Study area boundary Figure 6.1
Otipost Study Area Exposure Assessment Zones Secondary Medium Receptor Primary Primary Primary Secondury Secondary Transport Sources Release Transport Sources Release Processes Mechanism Processes Mechanism Exposure Residents Commercial- Houto Child Adult Industrial
Particular** Dispersion NO NO NO Ale and/or lion Inhalation Vapors Dogrodo I
0 Sell Ingestion a 0 ollpoel Deposition AMA Depoollion sell Degradation Dermal 0 Sail Blois Ingestion 0 0 NO Vagelables Ingestion NO NO NQ Blois
slocon- Egot Ingestion 0 a NO I.Wealso 30 cooliallon Ingestion a a NQ
Beal Ingestion 0 a NO
Lagoons Wildids Ingestion NO NO NO
Ingestion a Q
Dispersion c1loundwolor Dermal NO NO NO Irrigation lailliestion 4E ý ] Degradation 10 Inhalation a 0 t 0lioundwolov Dispersion Ground- Discharge Ingestion NO NO NO surface Wale( to Surface Sorption jýý Sorption Well IF Water Degradation Degradation Dermal Q a NO Deposition AMA Aunoll Rosusponsion Inge tion Cl a NO Surface Wale, and Sedinve., Deposill:1 III A p 5,19nil W.I.,Su"4::d 3111 i :ýH JA - a :nsorption Sediment Dermal NO -- qS.rroaurA -AU-0,fj
EXPLANATION
a Quantified
NO Not quantilied
Figure 6.2
Site Conceptual Model Offpost Study Area Receptors Quantified? Secondary Secondary Exposure Exposure Secondary Routes Source Release Transport Media Mechanism Process
Ingestion 11--NJ Livestock Yes From Ollsile Flow,Groundwal Disc Pumping Groundwater Onpost Groundwater to Surface Watera(ge Sorption Plant Uptake Crops Yes
Ingestion L1, tock Yes Fugitive Dermal Crops No From Ollsile Dust -)o Deposition Soil Onpost Soils Entrainmeni Inhalation erresiriaLlWildlif;Ir Wi No Cr sj
Ingestion Livestock Yes Plant 0-plake Crops Yes From Ollsile Oeposillon] H I Yes Wale( Runoll Sorption1110 Surface Wale Direct Contact Aauallc Life Onpost --)0 SurlaceSediment Ingestion Terrestrial Wildlife Yes
Ingestion Aquatic Life Yes Sediment De mal errestrial Wildlife Yes L
Biola Terrestrial Wildlile Yes " Plants Ingestion " Animals 0 LAquatic Life Yes
Figure 6.3 Ecological Site Conceptual Model for the 011post Study Area .V
RC-111
4; 0
'CNE4
RC-24
NE-121 ......
Norftm Paleochannel
-J,
p N, N :'First Creek Paleochannell E-3 -4A T., ý-ýTreatment A FE-2 Facdi T-6 FE-S .&FF-.i ty T-3 T
N
,-ýNortll Boundary Contmnment System
Explanation
Otfpost intercept and Treatment System extracton well
Oftpost Intercept and Treatment System recharge well
Offpost intercept and Treatmen: System recharge trench
Pipeline
Unsaturated alluvium 0 ISOO M Scaw in lost
Figure 7.1
Aftemative N-4 Remedial System Components C
......
......
:IX AP-3
AT-6 I AT-5 Northern Paleochannel V ...... -
1---.-;ýirst Creek PaleochanneU Treatrnent Facility
AT-4
Ir AT-3 AT-2 AP-1
N ,, ýN.M Bounaary Containment System
Explanation
M Additional extraction well unoe, Alternative N-5
Additonal recharge trencn ur-oef Afternative N-5
Otfpost Intercept and Treat-nent Sys-zern extraction well
Offpost Intercept and Treanent Systern recharge well
Offpost Intercept anc Treatment System recharge trench 0 1500 Pipeline SaMe in1"t Unsaturated allu%nurn
Figure 7.2
Afterrialive N-5 Remedial System Components SHELL OFTPOST PROPERTIES VEGETAUON CLASSHICATION with 1"5 EMMATED SURFACE SOM DIELDRIN DlSrRUlUTloN ými 21850M 2ý Nafive PeftIUtial ýaUland 1 Wetland Tme Gmve ýeckU ýea HomUWad SOW 13 Baý dOrý
UWJatiUfiUl SM[ ýýIllcs Die[IkcOI>-.Wug/g(1"5)
ýItW Bý
1616`ý
ýJ,U IOU ýFWIUm 224 49'Ol U6,jUsI T.c;,,OU 476
ToiwIIwstMU 4 LOP
1995 BOMAUIUUUIUd
MOHWN INUDO COMMON hiýmw ýicm Wpm
SCý 1 7," 0 I= IOU Figurg 9.1 Offpost AfimI of RevegMation Appendix A
RESPONSIVENESS SUMMARY
500920-2
M9800112 Appendix A
PREFACE
relevant information submitted in ThLis appendix contains the Army's responses to comments and new
Assessment/Feasibility Study, regard to the Proposed Plan, the Remedial Investigation, the Endangerment
Arsenal. Comments were and the selected remedy for the Offpost Operable Unit at Rocky Mountain
Region VIE, city and county received from the State of Colorado, U.S. Environmental Protection Agency governments, environmental action groups, and private citizens.
Appendix A Introduction. A glossary of acronyms used in Appendix A is provided at the end of the
A-1 21905 402010 Harding Lawson Associates 1108121495 R02 Appendix A
RESPONSIVENESS SUMMARY FOR THE ROCKY MOUNTAIN ARSENAL
Offpost Operable Unit regarding the The Program Manager for Rocky Mountain Arsenal (PM1UAA) solicited comments Plan and the U.S. Department of the Army's (Army's) findings in the Offpost Operable Unit Proposed
Endangerment Assessment/Feasibility Study (EA/FS) during a public comment period from March 21,
1993 through June 21, 1993. Both the Proposed Plan and the EANS were made available to the public for the entirety of the public comment period. These documents were available at various city and county libraries in the area as well as at the U.S. Environmental Protection Agency (EPA) Region VIE the RMA library. These documents, as well as the complete administrative record, were also available at joint Administrative Record Document Facility. A public meeting was held in Commerce City, Colorado, and on April 28, 1993, to present and discuss the Proposed Plan and the EA/FS report with citizens or public officials. This Responsiveness Summary has been prepared to respond to written questions concerns received by the Army during the public comment period.
28, The public meeting was held at the Dupont Elementary school in Commerce City, Colorado, on April the 1993 from 7:00 p.m. to approximately 11:00 p.m. Those in attendance included representatives from
A.rmv. the -L-m%.'s contractor (Harding Lawson Associates), EPA, State of Colorado (State), Tri-County
Health Department. city and county officials. public interest groups, and citizens. Also, a Court Reporter
and Notary Public reported the proceedings of the meeting in a stenographic transcript, available for
review in the site administrative record. An agenda was prepared for the meeting and provided to
attendees along with a copy of the Proposed Plan. A copy of the State's concerns regarding the Proposed
Plan was ilso made available to attend".es The Army presented a review of the Superfund process, a
video of the existing Offpost Groundwater Intercept and Treatment Svstem, a brief review of the history
of the Offpost Study Area, a review of the endangerment assessment results, a description of the altema-
tives evaluation process, information on the remedy selection process, and a presentation of the preferred
alternative.
A-2 Harding Lawson Associates 21905 402010 1108121495 R02 Appendix A
History of Community Relations Activities
Plan for the Offpost OU were made The Remedial Investigation (RI), RI Addendum, EA/FS, and Proposed
at the joint Administrative Record available to the public in the Administrative Record (located
Avenue and Quebec Street), in an information Document Facility at the west entrance to RMA at 72nd
VIII, and at the Adams County, Aurora, repository maintained at the EPA Docket Room in Region
Public Libraries. The notice of availabilitv Commerce Citv, Denver, Lakewood, Montbello, and Thornton
Post and Rocky Mountain News newspapers. for these four documents was published in the Denver
to ensure community members had An expanded Community Relations outreach was implemented
OU. Community outreach started in opportunity to comment on the Proposed Plan for the Offpost
supporting an impending Proposed Plan were January 1993 with the announcement that all documents
mailing of the announcement to more than available for review in local libraries. PMRNUk sent a direct
1200 local citizens.
was published announcing that a public In Nlarch 1993. a press release was made and a legal notice
School, Commerce City, Colorado, to meeting was scheduled for April 28. 1993. at Dupont Elempritary
informing them of the documents aýdress the Proposed Plan. A separate letter WdS sent to citizens
sheet summarizing the Proposed Plan. availdbiloy in the libraries. Thp 1-olor als:, iri,:Iu-iý! a b.-ip: iact
at RMA. The Army received requests to Originally. the public meeting was sch-dul.-.1 f-: April 21. 1993.
factors and Earth Day events in Denver hold the meetinS on a different day and ofit w b.- aus.. of these
for April 21, the meeting was mo%-4-d ir, Al r.. 28. 1111411
information on the Army's proposal to a A Media Day was held the day of th., :,i.- i - pruvide
local media. Both print and videri ru-:ii.! r. attended.
Lawson Associates A-3 21905 402010 Harding 1108121495 R02 Appendix A
the meeting announcement to Recognizing the importance of the public meeting, PMRMA expanded area in include display advertising in 12 local and weekly newspapers in the Denver metropolitan addition to the normal press release and Media Day event.
to written questions and The remainder of this Responsiveness Summary will consist of Army responses and replies comments received during the public comment period. Specific questions, comments,
received during the public meeting may be reviewed in the meeting transcript.
accordance with a Since 1989, all remedial investigation activities at the RMA have been performed in U.S. Department of the Federal Facility Agreement (FFA) signed by the Army, EPA, Shell Oil Company, and Disease Registry. By Interior. U.S. Department of Justice, and the U.S. Agency for Toxic Substances Mountain Arsenal. signing the FFA, these parties were made part of all decision processes at the Rocky involvement in the It is significant to note that the State elected not to sign the FFA, thereby declining Offpost Offpost Operable Unit decision-makLng processes. However, during the development of the and E-AvTS. the State has been involved in the entire process and provided comments on the RI, EANS, as they Proposed Plan to the Army. Accordingly. the Army has provided responses to these comments
have been received (e.g., Volume VIII of the Final Offpost Operable Unit EA/FS).
the Responsps to comments are presented in the following order, based on the originator of comment:
State of Colorado. Region VIII EPA. city and county governments, the Farmers Reservoir and Irrigation
Company. environmental action groups. and citizen comments. Three sets of comments from the State
are dddressed in this Responsiveness Summary The f Lrst two sets were received by the Army prior to
the official comment period on the Proposed Plan. and the third was received during the public comment
period.
In the following comments and responses. text printed in italics is verbatim text of comments received
regarding the Proposed Plan and EA/FS as received from the commentor. The response from the Army
A-4 Harding Lawson Associates 21905 402010 1108121495 R02 AppendixA
State of Colorado, Region VIII EPA, and the follows each comment. This format is followed for the
Farmers Reservoir and Irrigation Company.
governments, and from environmental action For responses to comments received from city and county
provided followed by a response to each groups, a copy of the comments as received by the Army is issue raised. numbered as appropriate.
Harding Lawson Associates A-5 21905 402010 1108121495 R02 Appendix A
This Appendix is organized as follows:
Section T'opic February 19, 1993 A-1 Responses to State of Colorado Commentsdated dated March 16, 1993 A-2 Responses to State of Colorado Comments dated June 21, 1993 A-3 Responses to State of Colorado Comments
A-4 Responses to Region VIII U.S. EPA Comments Comments A-5 Responses to City and County Government " Tri-County Health Department " Commerce City " City of Brighton " City of Thornton " City and County of Denver " Adams County " City of Aurora
Company Comments A-6 Responses to Farmers Reservoir and Irrigation
A-7 Responses to Environmental Action Group Comments " Sierra Club " Citizens Against Contamination " Arsenal Action Alliance " Colorado Pesticide Network " Environmental Information Network " Denver Audubon Society " We the People " League of Women Voters " Denver Region Greens
A-8 Responses to Citizen Comments
A-6 Harding Lawson Associates 21905 402010 1108121495 R02 Appendix A
GLOSSARY
ADI Acceptable daily intake
ARAR Applicable or relevant and appropriate requirement
Army U.S. Department of Army
ATSDR Agency for Toxic Substances and Disease Registry
AWQC Ambient water quality criteria
BDL Below detection limit
CBSG Colorado Basic Standards for Ground Water for Surface Water CBSNI Colorado Basic Standards and Methodologies
CCR Code of Colorado Regulations
CDH Colorado Health Department and Liability Act of 1980 CERCLA Comprehensive Environmental Response, Compensation,
CFR Code of Federal Regulations
COC Chemical of concern
CRL Certified reporting limit
CRS Colorado Revised Statutes
DIMP Diisopropyl methylphosphon-atp
EA.Ts Endangerment Ass.!ssmenl,'F-asitýi"it%-Stu(i%-
F-AL Dndangerment issessnioal,
EPA U.S. Environmental Ac--n
ESD E>.planation of SiSnifiran,
FEL Frank- effect levul
FFA Federal Facilit%, Agr--ri.-tv
FR Federal Register
FRICO Farmers Reservoir and lr-.igali :, G,mpany
FS Feasibility stud%
Elk Health advisory
Lawson Associates A-7 21905 402010 Harding 1108121495 R02 Appendix A
EBCS Irondale Boundary Containment System
IMPA Isopropyl methylphosphonic acid
IRA Interim response action
IRIS Integrated Risk Information System
kg Kilogram
I/day Liters per day
LOAEL Lowest observed adverse effect level
NbkTC Maximum allowable tissue concentration
NICL Maximum contaminant level
inglk-giday Milligrams per kilogram per day
Mg/l Milligrams per liter
NCP National Oil and Hazardous Substances -Pollution Contingency Plan
NOAEL No observed adverse effect level
OSIVER Office of Solid Waste and Emergency Response
ou Operable unit
PSIRMA Program Manager for Rocky Mountain Arsenal
P-0 Parts per billion
PF"al Parts per million
PQL Practical quantitation limit
PRG Preliminary remediation goal
RA Risk assessment
RAGS Risk Assessment Guidince f,).- Sup-rtund
RCF-,k Resource Conservat 1011 and Recovery Act
RfD Reference dose
Rl Remedial investigation
RNIA Rocky Mountain Arsenal
RME Reasonable maximum exposure
A-8 Harding Lawson Associatos 21905 402010 1108121495 R02 Appendix A
ROD Record of Decision
SQI Submerged quench incinerator
TBC 'To be considered
TCE Trichloroethene
TCHD Tri-County Health Department
TRV Toxicity reference value
UF Uncertainty factor
Agency USATHANiA United States Army Toxic and Hazardous Materials
USC United States Code
USFAIVS U.S. Fish and Wildlife Service
pgý Micrograms per liter
UST Underground storage tank
Lawson Associates A-9 21905 402010 Harding 1108121495 R02 Appendix A-1
RESPONSES TO STATE OF COLORADO COMMENTS DATED FEBRUARY 19, 1993 U.S. DEPARTMENT OF THE ARMY RESPONSES TO STATE OF COLORADO COMMMNrrS REGARDING THE ROCKY MOUNTAIN ARSENAL OFFPOST PROPOSED PLAN FEBRUARY 19,1993
GENERAL COMMENTS Comment No. 1. DIMP Contamination in Groundwate as a safe level of The State continues to disagree with the Army's use of 600 parts per billion (ppb) DIMP in groundwater. in excess plans on remediating only areas of groundwater with concentrations of DIMP The Army pose a threat to human of 600 ppb. The State believes that DIMP at much lower concentrations may the State, since 1990, has been providing free bottled water for health. For that reason, a 600 residents with DIMP in their wells. The State is concerned, furthermore, that approximately by portion of a plume of DIMP may have already passed the of/post intercept system constructed the Army. leaving high concentrations of this chemical, possibly greater than 600 ppb, unremediated. Response The U.S. Environmental Protection Agency (EPA) developed the Health Advisory for diisopropyl (DIMP) in 1989 on the basis of an extensive review of more thin 30 existing methylphosphonate Water re- toxicology studies involving a variety of animal species. EPA's Office of Drinking the Health Advisory, in light of the State's concern, and concluded on March 28, 1990, reviewed scientific that "the existing Health Advisory values and the basis for the values represent the best position for the protection of human health." In accordance with EPA's Risk Assessment Guidance for Superfund (RAGS), the Army used EPA's Health Advisory and information contained in the Integrated Risk Information System (IRIS) to evaluate risk to human health. The Of fpost Groundwater Intercept and Treatment System is located in areas of highest contam- inant concentrations. The Army is aware that concentrations of DIMP greater than 600 parts per billion (Ppb) have been reported north of the Off post Groundwater Intercept and Treatment System. In that regard, the offpost remedial action groundwater monitoring program will be coordinated with the three existing groundwater monitoring programs active in the Offpost Study Area. These three programs are (1) the Groundwater Monitoring Program, (2) the Interim Response Action A monitoring program, and (3) the private well monitoring program. Addition- ally, in the area north of the Off post Groundwater Intercept and Treatment System where DIMP has been reported to exceed 600 ppb, three monitoring wells will be replaced and three new monitoring wells will be installed. Replacement wells are being installed for three wells originally in the monitoring network that were found to be damaged or destroyed. Two new monitoring wells will be installed downgradient of the First Creek Pathway, and one new monitoring wen will be installed downgradient of the northern Pathway. The purpose of the three new monitoring wells is to aid in assessing the extent of contamination downgradient of the Offpost Groundwater Intercept and Treatment System. Data collected from these wells and existing wells win be used to further define the extent of contamination greater than the remediation goals in this area and assist in determining whether modifications to the design of the Offpost Groundwater Intercept and Treatment System are necessary.
21905,402010 - CR-05 0621110895 Comment No. 2. IMPA Contamination in Groundwate per billion (ppb) as a safe The State continues to be concerned with the Army's use of 7W parts level of IMPA in groundwater. IMPA contamination in the The State is concerned that the Army has not adequately characterized An understandirgof where IMPA exists in groundwater,both onpost and offpost groundwater. methodology. In has been hindered because of a lack of an acceptable Army analytical offpost, than 700 ppb, the acceptable addition. the State believes that IMPA at a much lower concentration level recommended by EPA. may pose a threat to human health. Response acid basis of toxicity information summarized in EPA's isopropyl methylphosphonic On the to indicate that INTA (IMPA) Health Advisory and the IRIS database, there is no information concentrations lower than 700 ppb may pose a threat to human health. ground- that toxicologically significant concentrations of IMPA win occur in It is highly unlikely conditions in the because the abiotic formation of IMPA from DIMP occurs under alkaline water DIMP and excreted in presence of heat. IMPA is primarily formed as a biological metabolite of data on the metabolism of DIMP indicates that the formation of the urine. The toxicological is a the metabolic elimiDation process and not a bioactivation reaction. IMPA IMPA is part of than reabsorbed by very polar metabolite that is most likely readily eliminated in the urine rather the kidneys and redistributed throughout the body. study; however, EPA The EPA reference dose for IMPA was based on a simple IMPA subchronic that the DIMP database can be used to support the toxicological conclusions indicates in IRIS 24 hours) IMPA because more than 90 percent of the ingested DIMP is rapidly (within regarding relatively nontoxic converted to IMPA. EPA states tha: the DIMP studies showed that DIMP was because DIMP is rapidly and mostly metabolized to IMPA, it is to all species. Additionally, to to conclude that the DIMP administered to mammals in the studies was metabolized reasonable an absence IMPA, therefore, the absence of effects from DIMP also may be considered to indicate of effects from IMPA. IMPA Analytical data collected to date in the Offpost Study Area for IMPA has not indicated that is present at or above the certified reporting limit (CRL) in groundwater or tap water samples. Army's current CRL for IMPA is 25 ppb. From 1989 through 1992, the IMPA analytical The ppb. In method used by the Army for analysis of groundwater and tap water had a CRL of 100 additional method development. the CRL was reduced to 25 ppb. The 1993 1993, following 700 ppb. reporting limit of 25 ppb is 28 times less than the EPA health advisory concentration of For this reason, the Army believes it has adequately characterized the extent of IMPA in the Offpost Study Area in a manner sufficient to conclude that potential health effects from IMPA are minimal. The Army has vigorously pursued the development of more sensitive methods for the identifica- tion of IMPA in RMA groundwater. The Army ts cuff ently unaware of a standard EPA method capable of attaining a reliable reporting limit near 6 ppb, the concentration proposed tiý the State. The Army has reviewed the State's evaluation of IMPA toxicity and will be providing additional comments.
21905,402010 - CR-05 0621110895 2 Comment No, 3. More Aggressive Treatment of Groundwater- the Arsenal can be achieved in a The State believes that the cleanup of groundwaterto the north of more timely manner without a significant increase in costs. different different alternativesfor the northern plume group, and four The Army evaluated six the Army estimates that for the northwest plume group. For the northern plume group, alternatives State believes that the Army signifi- it will take 15 to 30 years to clean up the groundwater. The to clean the groundwater in this area to a safe level. cantly underestimatedthe actual time necessary model, out an alternative that, according to the Armys groundwater In addition, the Army screened would have their estimated remedialion lime to 10 to 20 years, because it would have lessened in the Proposed Plan, would an additional year to implement. This alternative, called N-5 required it would not have to be operated as actually cost less than the Army's selected alternative, N-4 since long. take a shorter that a more aggressive alternative is preferable because it would The State contends effective. The State is to remediate the groundwater plume, and is therefore more cost time period a proposal as to how a more waiting for additional information from the Army prior to making aggressive remediation of groundwater could be achieved. Ktoonse because Alternative N-4 selected Alternative N-4 instead of Alternative N-5 primarily The Army are found to be necessary based includes potential future modifications, only if such modifications the Offpost Groundwater Intercept and Treatment System. Selection on actual operating data, to effective instead of Alternative N-4 will not necessarily provide a more cost of Alternative N-5 The Army based its alternative because of a slightly shorter estimated remediation timeframe. differences between the groundwater alternatives and estimates of assessment of the relative thus, the timeframes on groundwater models that are very general in nature; remediation predictions. Use of actual estimated remediation timeframes should not be construed as precise data is preferable to selecting additional components for the Offpost full-scale operating modeling data (i.e., Groundwater Intercept and Treatment System using the more speculative Alternative N-5). Intercept and The Army is committed to efficient operation of the Off post Groundwater and will evaluate operating data to assess the need for system modification. Treatment System the installation to the onpost boundary treatment systems, it is difficult to assess whether Similar full-scale operating of additional wells will provide more efficient operation without collecting Groundwater Intercept and Treatment System. The Army has included an data for the Off post in the monitoring component as part of the preferred alternative, Alternative N-4, intensive and subsequent Proposed Plan. This intensive monitoring program will allow the collection of performance data for the full-scale operation of both the Offpost Groundwater interpretation will be used to assess Intercept and Treatment System and the onpost boundary systems. The data to the systems and will provide increased accuracy in assessing the need for any improvement wells cleanup. Acquisition of this operational data is preferable to adding extraction contaminant data are required and recharge trenches without the benef It of operational data, because additional necessity and placement of any additional extraction wells or trenches. If operational to assess the a significant data supports the conclusion that the cleanup timeframe can be shortened without long-term costs, modifications to Alternative N-4 will be implemented. By taking this increase in based on approach, improvements to the system will be more effective than improvements made computer modeling data. that a more aggressive alternative is preferable because it would shorten The State's contention use timeframes and thus would result in a more cost-affective alternative relies on the remediation data from of modeling data to make the assessment. The Army proposes to use actual operations
21905,402010 - CR-05 0621110895 3 N-4 to make the same assessment. Modification of the Offpost Groundwater Alternative on field operations and monitoring Intercept and Treatment System, if necessary, would be based data.
Comment No.A. Selection of the Anpropriate Risk Leve in the offpost concerned that the Army's selected risk level for excess cancer incidence The State is Plan does not state what is not protective and is contrary to federal law. In addition, the Proposed level of health protection will be achieved. Plan (NCP). state that The regulations that implement the Superfund law, the National Contingency designed to prevent excess risk to human health greater than a remediation plan should be of in a million (lx]0-6). This number, or cancer risk level, is called the point approximately one remediation is EPA, because risk levels are sometimes difficult to predict, and because departure. thousand (IxIO-4) sometimes impractical, has allowed the risk level to be approximately one in ten At the Rocky Mountain Arsenal, the Army is assuming that a risk level of 5 in in certain instances. made no showing ten thousand OxIO-4), or one in two thousand is acceptable, even though it has of departure could not be achieved. Because the risk level is higher than the that the NCP's point soils in parts accepiable risk level provided for in :he NCP. the Army has been able to avoid cleanup of the offposi operable unit. Response has closely followed EPA guidance and the NCP regarding the use of the 10" risk The Army cumulative threshold to assess whether remediation is necessary. Guidance states that if the an individual is less than 10'. remedial action may not be warranted unless certain cancer risk to must be site-specific conditions exist. If remedial action is warranted, the 10-4 to 10'6 risk range with an initial preference for the 104 end. EPA guidance further states that the upper achieved, risk range can of the risk range is not an absolute at I x 10,4, but rather, the acceptable boundary is within extend to 5 x 10'. The cumulative offpost cancer risk is a maximum of 3 x 10', which the acceptable risk range. The Army's goal. through operation of the Offpost Groundwater Intercept and Treatment System, is to further reduce offpost risk toward the 10,6 level. Potential risk attributable to soil is a maximum of 8 x 10'. This risk would only be realized for a population exposed at reasonable maximum exposure (RME) levels for all pathways. Because this scenario is unlikely and because maximum cancer risks are within the EPA risk range, offpost soil does not require remediation.
Comment No. 5- Acknowledging the State Groundwater Restulations as Leizal Standards The state disagrees with the Army's decisions to ontit State environmental regulationswhen defining cleanup levels. Under CERCLA. State environmental laws and retulations which set standards for cleanup, fulfill certain statuzory criteria.and are more stringent than the comparable federal standards, must be used as the appropriatecleanup standards at Superfund sites. The Colorado Basic Standards for Groundwater have been acknowledged as the appropriatecleanup standard at other Superfund sites in Colorado. In fact, the Army itself has recognz:ed these regulations as the governing standards for Interim Response Actions at the Rock). Mountain Arsenal. For the Offpost Operable Unit, however. the Army has refused to use the Coloradoregulations as a remedial standard. It is important to the State of Coloradothat our lawi and regulations be obeyed. The State therefore maintains that Colorado law must be recognaed as providing appropriatecleanup standards for the Offpost Operable Unit at the Rocky Mountain Arsenal.
21905,402010 - CR-05 0621110895 4 Resnonse and laws and regulations that meet the applicable or relevant The Army has recognized all state Response, (ARARs) criteria under the Comprehensive Environmental appropriate requirements discussion with all the and Liability Act (CERCLA) and the NCP. After extensive Compensation, for Groundwater (CBSGs) do the Army has concluded that the Colorado Basic Standards parties, and ambiguous language. not meet the ARARs criteria because of inconsistent application federal drinking water standards and are ARARs for the Offpost Operable Unit are based on goals for the offpost and boundary protective of human health. In most cases, the treatment treatment systems exceed the drinking water standards. only those provides that state standards can be ARARs at a site. However, CERCLA expressly In addition, the that are more Stringent than federal requirements may be considered. standards general applicability and must be promulgated (i.e., the requirement must be of state standards in a timely manner by the enforceable). Finally, the requirements must be identified legally 300.400[gl4l). particular state (40 Code of Federal Regulations [CFR] Section Quality Control Act, Colorado Revised Regulations promulgated pursuant to the Colorado Water for groundwater (5 Code of Colorado Statutes (CRS) Sections 25-8-101, et seq., establish standards of the regulation is that Tables I Regulations [CCR] 1002-8, Section 3.11.0). A key aspect groundwater (Section 3.11.7[Al), but apply through 4 standards are not automatically applicable to Section 3.11.4. only if the aquifer has been classified in accordance with the Water Quality Control Commission Most aquifers in the state are unclassified. Consequently, (Section 3.12.5) for five specified (Commission) promulgated the interim narrative standard to aquifer classification. Each of the aquifer systems to avoid degradation of water quality prior I through 4 or the ambient quality as of five identified aquifers must meet the standards in Tables are classified and numerical standards October 30, 1991, if it was less restrictive, until the aquifers are adopted. that are applied different- Comm lssion promulgated a second group of groundwater standards The (Section 3.11.5[C]) include the standards in Tables I through 4. These statewide standards ly than for organic pollutants water quality standards for radioactive materials and interim standards the standards in Tables I through (Table A), including chloroform. Table A standards differ from to all state groundwater an important way: Table A standards are automatically applicable 4 in of Table A (Section 3.11.71AI). The Commission recognized that the automatic application impracticable results at standards can lead to unnecessarily overprotective and technically activities at CERCLA contaminated sites and added exceptions to the regulation for remediation underground storage tank sites, Resource Conservation and Recovery Act (RCRA) sites, and the following: (UST) sites. The CERCLA exception, Section 3.11.5(C)(5Xa), states
Nothing in this regulation shall be interpreted to preclude ...[a]n agency responsible for implementation of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA). 42 U.S.C. 9601, et seq., as amended, or less from selecting a remedial action and a point of compliance that are more numerical stringent than would be achieved by compliance with the statewide established in this subsection, or alternative site specific standards standards is adopted by the Commission, when a determination is made that such a variation authorized pursuant to the applicable provisions of CERCLA.
under RCRA Sections 3.11.5(C)(5)(b) and (c) provide similar exceptions for corrective actions Subtitle C (hazardous waste treatment, storage, and disposal facilities) and Subtitle I (UST sites), respectively.
21905,402010 - CR-05 0621110895 5 the is internally consistent only if the Commission intended not to impose Section 3.11.5(C)(5) regulations, the organic standards in Table A as cleanup standards. According to the interim except at CERCLA, RCRA, interim organic standards automatically apply on a statewide basis, regulatory determinations regarding groundwater quality and UST sites where Rcertain federal the be superseded by the Commission's standards" (Section 3.11.10[B]). In promulgating would not are more familiar Table A exceptions, the Commission recognized that implementing agencies and are in a better position to determine the appropriate cleanup with site-specific conditions the not imposing unnecessarily stringent application of the Table A standards, standards. By programs, which may Commission sought to show "explicit deference to certain federal regulatory apply different standards" (Section 3.1 1.10[H]). that the CBSG interim organic standards are not ARARs for several reasons. The Army concludes authorized under The CERCLA exception in Section 3.11.5(C)(5Xa) applies to remedial actions more or less stringent than would be achieved by compliance with the statewide CERCLA that are exceptions standards. As a result, the overall effect of the statewide standard and accompanying that is only sometimes more stringent than a federal requirement. CERCLA is a state regulation Therefore, by only considers state standards that are stricter at all times as potential ARARs. definition, the interim organic standards are not ARARs at Superfund sites. CBSG interim organic standards cannot be ARARs because they are not generally Second, the to be applicable or legally enforceable. A requirement in CERCLA for state requirements that they must be promulgated standards, which means they must be generally ARARs is meet this test applicable and legally enforceable. Clearly, the interim organic standards do not at CERCLA sites. By definition, the interim organic standards are applicable when applied the relevance throughout the state, except at CERCLA, RCRA, and UST sites. In those instances, is determined by the remedial sites. It is hard to understand how the standard of the standards that the could be legally enforceable when the Commission added language specifically ensuring standards may or may not be met at CERCLA sites.
Comment No. 6. Future Land Use exposure The State believes that the Army failed to consider all reasonable land uses, and therefore pathways. when it defined risks to human health. The NCP requires the Army to consider current and reasonable potential land use in evaluating the risk to human health and the environment posed by contamination. The Army has decided that zones 3 and 4 of the operable unit should be analyzed assuming an urban residential scenario. The land in question is currently unoccupied because it is owned by Shell Oil Company. It was being used a rural residential property before Shell bought it. and is presently zoned for rural residential use. The Army justifies its classification of this property by relying on future land use projections which have been made by Adams County. The State contends that the rural residential scenarios should be used since it is currently permitted and there is no assurance that the land will not be used in this manner in the future. This is important because using the urban residential scenario results in elimination of exposure pathways of consumption of homegrown meat, milk, and eggs in estimating risk. thereby allowing the Army to leave higher levels of contamination in the soils. Resr>onse The land use designations and plans were established by the appropriate jurisdictional agencies, not by EPA or the Army, and were used to establish land use scenarios for use in the risk assessment within each risk assessment zone. Evaluation of current zoning regulations, discussions with local planning officials, examination of future land use master plans for the city and county, and visual surveys were used to establish land use scenarios. These designations are supported by established zoning, planning maps, and planning documents. The future land use scenarios used
21905,402010 - CR-05 0652111089S 6 ------
are highly conservative. For example, the rural residential by the Army in the rLsk assessment to potential risk, zones 1, 2, and 6 includes all pathways contributing substantially scenario used in exposure pathways most of the total population is not exposed to the agricultural even though the land in zones 3 and 4 for in the risk assessment. Shell Oil Company purchased described and Treatment System. It is not use in constructing the Offpost Groundwater Intercept Army as rural residential is not applicable. presently occupied; therefore, the current zoning designation of 96th Avenue, future development along Given the probability of the realignment and widening urban residential. The Army selected an 96th Avenue will likely be commercial/industrial or in more conservative (e.g., urban residential land use for the risk evaluation as this would result land use. higher) estimated risks than the likely commercial/industrial
Comment No. 7. Institutional Controls: problems may purchase property The State is concerned that people unaware of the contamination and be exposed to unacceptablerisks. in Zones 2. 3, or 4. Plan does not include active remediation of soils or groundwater The Proposed level. Shell Oil contaminationin these areas exceeds state and federal cleanup Groundwater State is concerned that owns portions of these areas. the rest is privately owned. The Company and sinking domestic wells, is nothing to prevent people from developing land in these areas, there preferring active remediation which would contain contaminated groundwater. The State. although and well restrictionsmust be these areas. maintains that institutional controls such as deed in risk in the future. imposed to ensure that people will not be exposed to unacceptable
Rtwmn-u Appendix B of the controls have been added as a component of the selected remedy. Institutional controls available and their Record of Decison (ROD) provides an evaluation of the institutional remediation of soil in the applicablilaN. See the response to State Comment No. 4 regarding Offpost Study A rea.
Comment No. 9- Hum n Health Risk Characterization to human health. The State has several concerns with how she Army defined potential risks risk to human health The State haj several concerns with the method the Army has used to evaluate were not considered in the ollpost Several pathways. which the State considers important, in during bathing or evaluaiinK risk. for example. dermal absorption of contaminated groundwater wading, and ingestion of showering inh.:1wion of dust. incidental ingestion of surface water during The State also has fruits grown irr contaminated soil or irrigated with contaminated groundwater. people eating eggs n ith the fact that the Army concluded that only dieldrin posed a risk to concerm on the sampling of from chickens raised in the offpost operable unit. This conclusions was based to draw such a onl 'v one egg The State believes that these are insufficient data from which to it by the State conclusion. 4nJ perhaps most importanil*y. that Army ignored data presented that this behavior regarding soil intestion rates and pica behavior (children who eat dirt). which should be eraluwed in assessing risk caused by contaminants in soil.
Resvonse basis of EPA The Army considered all of the exposure pathways listed by the State and, on the in the risk guidance presented in RAGS, the pathways were eliminated from further evaluation to EPA, the U.S. assessment. The Army presented the human health risk assessment pathways After Fish and Wildlife Service (USFWS), Shell Oil Company, and the State for discussion.
21905,402010 - CR-05 0621110895 7 guidance in RAGS all potential complete exposure pathways, the Army followed EPA identifying assessment. Guidance (page 6-17) to select those pathways to be evaluated further in the exposure justification, such as: allows for the elimination of some complete pathways if there is sound another pathway 1. 'ne exposure resulting from the pathway is much less than that from involving the same medium at the same exposure point.
2. The potential magnitude of the exposure from the pathway is low. with the 3. The probability of the exposure occurring is very low, and the risks associated occurrence are not high.
bathing or The Army did consider dermal absorption of contaminated groundwater during however, this showering (see page 11-2-61, Volume U of the Endangerment Assessment [EA]); small when pathway's contribution to the overall intake and risk was considered to be very The inhalation compared to the intake of groundwater contaminants via ingestion and inhalation. IV of the of dust is addressed on pages U-2-59 and 11-2-60, Volume U and Appendix B, Volume B EA. The conservative screening level model of exposure to dust presented in Appendix direct soil indicated that the contact rate via this route is very small compared to incidental of the EA). ingestion. The incidental ingestion of surface water was considered (see page U-2-63 to However, it is highly unlikely that this route for exposure would be a significant contributor of the overall risk because of the low frequency of occurrence, ingestion rate, and concentration contaminants in surface water. The ingestion of homegrown fruit was considered (see were page 11-2-62 of the EA); however, fcr the purpose of the offpost risk assessment, tomatoes considered as a vegetable. Fruit production is such a minor contributor to the agricultural economists. economy of the area that fruit production statistics are not kept by local agricultural Therefore, fruit ingestion was not evaluated. Intake via the consumption of eggs was only evaluated for dieldrin because dieldrin was the only contaminant detected in the egg sample.
The Army has previously responded to the State's request that soil ingestion rates related to pica behavior be considered. The Army followed EPA's guidance in RAGS to evaluate the soil ingestion pathway and the soil ingestion rate. The rate used accounts for both outdoor soil and indoor dust ingestion by children and is considered by EPA to represent an upperbound value (a conservative value that is highly unlikely to result in an underestimation of risk). EPA is aware of the information presented by the State. EPA guidance specific to CERCLA risk assessments is the most reliable and authoritative source for the soil ingestion exposure parameter.
Comment No. 9. Ecological Risk Characterizatio
The State does not agree with how the Army defined potential risks to vegetation and wildlife offpost of the Arsenal.
The State continues to have significant concerns with the methodology used by the -Army in defining ecologically based cleanup levels. The State contends that the Army has made assumptions based on insufficient data and that the Ecological Risk Assessment will likely allow levels of contamina- iion to remain in the offpost that maY not be protective of biora.
Response
The State has not presented any evidence to support its contention that assumptions made for the ecological risk assessment (RA) will result in levels of contamination remaining in the Offpost Study Area that may not be protective of blom. The Army presented the ecological RA assump- tions and approaches to the USFWS, EPA. Shell Oil Company, and the State at meetings through-
21905,402010 - CR-05 062111089S 8 meetings and subsequent the ecological RA study period. The Army considered these out guidance on conducting a dose-based feedback critical because of the lack of formalized EPA of Army believes that the findings of the ecological RA are protective ecological assessment. The effects are more wildlife because many aspects of the approaches used to estimate potential assessment methodologies currently followed by EPA and other conservative than other hazard being devel- agencies. Because the approaches to conducting an ecological RA are continually parameters used by the Army for the final ecological RA were oped, the assumptions and RA process, and the thoroughly discussed with the parties and modified throughout the ecological and professional judgement were used. The USFWS participated in best available methodology the potential the ecological RA process and supported the final methodologies used to evaluate ecological hazards.
Comment No..10. Hot Spots in Soils Soils off The State is concerned that the Army has not met the burden of proof that contaminated the Arsenal are not RMA related. several spots in zones 3 and 4. and along Buckley road, The soil sampling program identified These where concentrations of dieldrin. a pesticide, exceeded the Army's proposed cleanup goals. from remediation based on the Army's assumption that these "hot spots" were eliminated There are no concentrations were due to agriculturalpractices. and it was therefore not responsible. source of these contaminants in the EAIFS. The State requests additional data indicating the correct. sampling in the area, so that is can better determine if the Army's assumptions are Resr)onse on the potential The Army did not base conclusions regarding the assessment of soil contamination for contamination attributable to agricultural practices in certain offpost areas. of onpost and offpost surface soil data to interpret Rocky The Army used a large amount offpost data Mountain Arsenal (RMA)-related soil contamination. The combination of onpost and demonstrates that detected concentrations of contaminants offpost are attributable to windblown transport from RMA and to offpost activities, including agricultural application of pesticides. Further, risks corresponding to offpost soil concentrations are within EPA's acceptable risk range. As discussed in response to the State's Comment No. 4, remediation of offpost soil is not required.
Comment No. 11. Contamination of Barr Lake: The State is concerned that the Proposed Plan does not include remediation of surface water and sediments. The Army has decided not to activel- v remediaie surface water in the offpost operable unit. First Creek. which flows from the Rocky Mountain Arsenal to O'Brian Canal and ultimately into Barr Lake. is contaminated with RMA-related chemicals. The Army's position is that First Creek will be cleaned over time. as uncontaminatedgroundwater flows info it, and flushes out the contamination. This could take several decades. During this period of time, small quantities of contamination will continue to flow into Barr Lake. The State believes that the First Creek water should be remediated. so that no further degradation of Barr Lake occurs. Resr)onse Remediation of offpost groundwater will reduce contaminant concentrations in First Creek. Surface-water monitoring will continue as part of the offpost monitoring plan. A surface-water
21905,402010 - CR-05 0621110895 9 selected remedy. An offpost monitoring program has been included as a component of the of the ROD. implementation document will be prepared following approval
Comment No. 12. Closinp. Poorly Constructed Domestic Wel groundwater into the The State remains concerwd with the continued migration of contaminated deeper aquifer. either in poor condition, or are The State has identified approximately 20 domestic wells that are for allowing RMA screened through more than one aquifer. These wells are responsible The Proposed Plan does not contamination to migrate to the Arapahoe Formation, a deeper aquifer. Army close these wells to prevent address these wells. The State has repeatedly requested that the further degradation of the deeper aquifers.
Response remedy. The criteria for The Army has incorporated well closure as a component of the selected well closure are presented in Appendix C of the ROD.
21905,402010 - CR-05 0621110895 10 Appendix A-2
RESPONSES TO STATE OF COLORADO COMMENTS DATED MARCH 16,1993 U.S. DEPARTMENT OF THE ARMY RESPONSES TO THE STATE OF COLORADO COMMENTS REGARDING THE ROCKY MOUNTAIN ARSENAL OFFPOST PROPOSED PLAN MARCH 16,1993
SPECIFIC COMMENTS Comment No. 1. vage 2. 2nd paragraph, Ist sentence National The State does not agree that the Proposed Plan is consistent with CERCLA 121 and the Contingency Plan (NCP). Among other issues, the Plan does not conform to ARARS, is not sufficiently protective of human health and the environment, and does not follow NCP guidance relating to institutional controls. ResE)onse Section 121 of the Comprehensive Environmental Response, Compensation, and Liability Act pertains to cleanup standards, specifically (1) selection of remedial actions, (2) general (CERCLA) and rules for selection of remedial actions, (3) five-year review, (4) degree of cleanup, (5) permits enforcement, and (6) state involvement. The Offpost Proposed Plan is fully consistent with the above- referenced CERCLA Section 121. Selection of the remedial actions described in the Proposed Plan's preferred altemative is necessary in accordance with CERCT-.4L Section 121, is consistent with the National Oil and Hazardous Substances Pollution Contingency Plan (NCP), and provides for a cost-effective response, per the requirements of item I above. Consistent with item 2 above, the Proposed Plan's preferred alternative is protective of human health and the environment, is cost- effective, and uses permanent solutions and alternative treatment technologies to the maximum extent practica- ble. Provisions for a periodic review of site conditions are specifically incorporated into the Proposed Plan's preferred alternative per item 3 above. The Proposed Plan's preferred alternative incorporates those standards, requirements. criteria, or limitations resulting from a complete analysis of applicable or relevant and appropriate requirements (ARARs) per item 4 above. The U.S. Department of the Army (Army) has recognized all state and federal laws and regulations that meet the ARARs criteria under CERCLA. Item 5 above is met by the preferred alternative through substantive compliance with federal, state, and local permitting requirements in the implementation of remedial components. Item 6 above requires involvement of the state in decisions regarding initiation, development. and selection of remedial actions to be undertaken and, specifically, provides the opportunity for the State of Colorado (State) to review and comment on the remedial investigation (RI) and feasibility study (FS), the planned remedial action identified in the RI/FS, the engineering design, and other technical data and reports relating to implementation of the remedy. The State has had opportunity to comment on the RI/FS, technical data, and other offpost reports. In addition, item 6 above requires that the State have the opportunity to comment on the Proposed Plan for remedial action and that responses to the State's comments are provided. The State has also commented on the Proposed Plan, and the Army has provided responses. All comments and repsonses are part of the offpost administrative record. The preferred alternative presented in the Proposed Plan is fully protective of human health and the environment. The components of the preferred alternative provide for reduced potential risk and protection of human health and the environment through remediation of offpost groundwater that exceeds cleanup standards. Cumulative potential risks in the Offpost Study Area are within health standards established by the U.S. Environmental Protection Agency (EPA) and will be reduced further through remediation associated with the preferred alternative.
21905,402010 - CR-06 0709110895 alternative. Appendix B controls have been added as a component of the preferred institutional of institutional controls that may be of the Record of Decision (ROD) provides a discussion implemented for the Offpoist Study Area.
Comment No. 2-vaee 2. Figure I in the operable unit are misleading. It implies that the only areas of contamination This figure is the area between the plumes. There is soil and groundwater contamination in the groundwater depicted on the map. The State is as well as east, west, northwest and north of the plumes plumes, north of 88th Avenue, and west of concerned about concentrations of trichloroethylene in wells also for that contamination, and some Street. Although the Army may not be solely responsible Quebec the EPA study area, there are no the contamination may be from other superfund sites within of as part of the offpost study, should in the EAIFS analyzing this contamination. The Army, data it is a result of either bypasses of the investigated this contamination, and the possibility that have on RMA. Irondale Boundary Control System, or from other sources
Rest)onse of the Offpost Operable Unit according to Figure I of the Proposed Plan delineates the boundaries (FFA). The FFA defines the Operable definitions provided by the Federal Facility Agreement the substances are subject to as that portion of the Offpost Study Area where hazardous Unit present in media (e.g., groundwa- remediation. On the basis of the risk assessment, contamination unit boundaries was shown to result in ter, soil, surface water, sediment, air) outside the operable the acceptable risk range specified in the risk levels that meet EPA's health guidelines and within NCP. in groundwater within the evaluated the risks associated with trichloroethene (TCE) The Army 88th Avenue and east of of the designated study zones. Zone 6, which is north of boundaries However, this value, which Street, had the highest exposure point concentration for TCE. Quebec Act maximum contaminant level is 4 micrograms per liter (jug/1), is below the Safe Drinking Water 3 jug/l (based on a residential exposure (MCL) of 5 pg/l and near the I x 10' cancer risk level of scenario).
Comment No. 3. paize I- Ist r)araprar)h. 6th sentence of RMA was added to sentence is incorrect. This sentence should be revised to read, "...most This F was listed in 1989. the National PrioritiesList in 1987.' As the Army is well aware. Basin
Rest)onse
The Record of Decision (ROD) has been revised accordingly.
Comment No. 4. t)age 3. 5th twurar)h. 2nd_yu= are not contaminated by The State disagrees with the statement that the areas east of the RMA have been detected. The RMA-related chemicals. Concentrationsof dieldrin as high as 99 ppb determine if contamination was State has requested additional onpost and offpost soil sampling to that RMA has not transportedfrom the Arsenal. Additionally. although it is probably correct Proposed Plan is misleading significantly contaminated the areas to the south. the statement in the would be more it implies that sampling was conducted to support that conclusion. It because prevailing winds and appropriateto state that. because of the north and northwest direction of the
21905,402010 - CR-D6 07D9110895 2 areas south of RMA the low concentrali.ons along the southern tier, there is no reason to believe that have been significantly affected by contamination at the Arsenal.
Response east of the of the extensive agricultural activities that have occurred in areas north and Because pesticides that are a Rocky Mountain Arsenal (RMA) boundaries and the application of registered residues in soil. Examina- consequence of agricultural activities, it is not unusual to find dieldrin does not support tion of organochlorine pesticide data obtained from onpost surface soil samples the source for organochlorine pesticide transport east of RMA. In addition, RMA as being to collected east of RMA have dieldrin concentrations ranging from nondetectable five samples one 25 parts per billion (ppb). On this basis, it is the Army's position that the approximately activities. Soil sample with dieldrin detected at 99 ppb east of RMA is not related to onsite of contami- samples collected at the southern boundary of RMA did not contain concentrations nants above levels that pose a health risk.
Comment No. 5. t)aRe L Figure 2 are of This map is misleading. The Army should make it clear that the plumes shown contamination in excess of federal ARARS, but that other areas are contaminated as well.
Resr)onse locations in the As stated in the Proposed Plan, Figure 2 shows plume groups corresponding to cleanup goals Of fpost Study Area where shallow groundwater contaminant concentrations exceed Study (EA/FS) presented in the Feasibility Study (FS). The Endangerment Assessment/Feasibility outside the provides additional discussion regarding contaminant concentrations in the areas Operable Unit.
Comment No 6- nage 5. 6th pgragraph- 7th sentence The The text staies thaj soil. surface water. and sediment are within the acceptable risk range. risks shoulJ he specifically stated for each medium in addition to the cumulative risk for all exposures,
Resvon5c and to The purpose of the Proposed Plan is to briefly summarize the risk assessment findings all present. In some detail. the remediation alternatives to clean up the site. The inclusion of media-specif ic f isks and cumulative risks for all exposure pathways is beyond the recommen- dations set forth b% EPA guidance and would result in a more complicated document. Interested individuals are referred to the EA/FS for 3 complete discussion of the media-specific and pathwaý -Spec if IZ risks.
Comment So -_ page 6. 2nd bullet- Site Revie-
The text should be clarified that the five 'year review is required under CERCLA §121(c), because ha:ardous substances. pollutants, or contaminants will be left in place. The public should be informed that the purpose of this review is to ensure that the remedy remains sufficiently protective of human health and the environment. In addition. the remedy may be amended at that time, if EPA decides that the remedy is not sufficientlY protective.
21905,402010 - CR-06 0709110895 3 Response
The State's comment that contaminantss will be left in place is misleading in that active remedial of the measures that result in contaminant removal and treatment are the primary components a site review will preferred alternative. As stated in the reference section of the Proposed Plan, during and after the be performed to ensure that human health and the environment are protected remediation.
Comment No. S. r)age 6. 4th bullet. Continued Overation the onpost This bullet implies that the remedy selected is an offpost remedy. In fact, this is remedy.
Response standards is The continued operation of the onpost boundary systems to meet the offpost cleanup an integral component of the offpost preferred alternative.
Comment No. 9. r)aee 6- Alternative N- I by the Army. 'No The State disagrees with the preseniction of the 'no-action' alternative described status quo. action." as defined by NEPA and incorporated in CERCLA, means maintenance of the 40 CFR 300.430(a)(6) slates that. among other alternatives. the lead agency must develop "[t)he has no-action alternative. which may be no further action if some removal or remedial action already occurred at the site.* (55 Fed. Reg. 8849. March 8. 1990; emphasis added.) This alternative is not. as the Army states, a shutdown and dismantling of preexisting remedial measures. A true "no action alternative.' as envisioned by the NCP. would include continued operation of the boundary control systems without modifications or additions. See State's comments on EAIFS. December 13. 1991 at pages 4-5.
Response
The Army has included in its evaluation or ofrpost alternatives both a no-action alternative (NW- I and N - I) and a no further action alternative (NW-2 and N-2), as defined by the State. The no further action alternative presented in the EA/FS meets the NCP requirement specified at 40 Code of Federal Regulations 430(eX6).
Comment No. 10, page 8. Definitions or Crit
The State disagrees with the statements regarding State Acceptance The Army is disingenuous when it implies that the State's positions on the proposed remedy are unknown. The State's views on the selected remedy and other issues have been conveyed in extensive comments on prior drafts of the EAIFS. The NCP provides, moreover. that as part of the Proposed Plan the lead -agencyshall assess "0) The state's position and key concerns related to the preferred alternative and other alternatives: and (2) State comments on ARARs or the proposed use of waivers' NCP § 300.430(a)(iii)(9)(H). In addition. the Proposed Plan shall 'provide a summary of any comments received from the support agency.' NCP J 300.430(f)(2)(iii); emphasis added. The Army has failed to include these matters in the Proposed Plan.
21905,402010 - CR-06 0709110895 4 Resoonse The NCP, Section 430(eX9)(iii)(H), states: Assessment of state concerns may not be completed until comments on State Acceptance. plan the RI/FS are received but may be discussed, to the extent possible, in the proposed issued for public comment. (emphasis added). were still being Because many of the issues regarding the EA/FS and the preferred alternative the Army, EPA, and the State at the time the Proposed Plan was issued, the discussed between regarding believed that these issues should be resolved before making a definitive statement Army public meeting, State acceptance. A handout detailing the State's concerns was provided at the and the State was provided time to present its concerns orally at the public meeting.
Comment No. I I -Tables 2 and 3 The State requests that all of the action alternatives be contained within these summaries. Resnonse with EPA guidance, the Army has included those alternatives passing initial screening Consistent are presented of alternatives conducted in the FS. Alternatives that did not pass initial screening in the EA/FS.
Comment- o-1-2-G-19mary The following term should be redefined: a. Federal Facility Agreement: The definition was corrected in the body of the text, but remains incorrect in the Glossary. The FFA formalizes the parties' responsibilitiesfor cleanup at RMA. The framework is set by CERCLA and the NCP.
Resvonse The definition of the FFA has been corrected in the ROD.
Comment No. 13. Glossary- The following word should be defined: a. Contamination: The Army appears to use the word solely to mean levels of contamination above federal ARARs. The dictionary defines contamination as "the state of being impure or corrupt.- The Army is therefore implying to the public that the "uncontaminated"areas are clean. In fact. the 'uncontaminated' areas are not pristine, but are not sufficiently contaminated. according to the Army. to warrant remediation.
Response Most of the contaminants found in the Off post Study Area are not unique to RMA. Many of these substances have been used in crop and livestock production, including areas north and east of RMA, and others are naturally occurring. The Army frequently qualifies its use of the word
21905,402010 - CR-06 0709110895 5 "contamination" as being above or below levels that would pose a threat to human health or the environment. On this basis, no further definition is necessary.
21905,402010 - CR-06 0709110895 6 Appendix A-3
RESPONSES TO STATE OF COLORADO COMMENTS DATED JUNE 21,1993 U.S. DEPARTMENT OF THE ARMY TO STATE OF COLORADO COMMENTS REGARDING RESPONSES PLAN THE ROCKY MOUNTAIN ARSENAL OFFPOST PROPOSED JUNE 21, 1993
GENERAL COMMENTS
Comment No. I - Risk Assessment a. Point of Departure range from I X 10' in The Proposed Plan states that the cumulative potential cancer risks OSWER directive, dated I to 3 X 10-d in Zone 3. In the Final EAIFS, the Army cites an Zone a 10-4 risk 1991. which it claims authorizes no action at sites that do not exceed April 22, goals at the NCP, however. clearly states that EPA's preference is for remediation level. The the express more protective end of the range. that is 10t The Army is clearly disregarding C.F.R. language of the NCP which sets the Point of Departure at 10'. SeL 40 §300.430(e)(2)(i)(A)(2) (1991). Army, dated February 21, This issue was specifically addressed in a letter from EPA to the VIII set down the criteria 1992. In that letter. in which the State did not concur, EPA Region point of departure of that it would consider in allowing the Army to deviate from the NCPs have to develop PRGs for 10'. Specifically, EPA stated: "We agree that the Army would not for those cases, the Army those media where the cumulative risk was not greater than 10-4, LL, added). The could adequately document that the 10-4 PRGs were appropriate.' (Emphasis 104 is appropriatefor the Arm ,v has not been able to demonstrate that a point of departure of Army was required to show: off post operable unit. Among other requirements. the total additive risk a) Thai all of the media had been evaluated so as to demonstrate "that the does not exceed the 10' risk level or a hazard index of one." the b) Thai sample sizes for all media were sufficiently large to statistically represent sitelreceptor conditions.
c) That all potential exposure routes were evaluated. that d) Thai sensitive subpopulations. especially pica children, had been evaluated to ensure the risks to these groups do not exceed 10'. unknowns e) Thai all contaminants of concern (COCs) tentatively identified compounds and are evaluated and do not contribute to risk or hazard. example, The Army has failed to comply with the requirements contained in EPA's letter. For the hazard index exceeds one in three of the six zones and part of Zone 1. In Zone 4, the were long term exposure HI is 4, four times the EPA accepted limit. Potential exposure routes not fully evaluated: for example. all COCs except dieldrin were eliminated from consider- ation in the soillegg pathway because dieldrin was the only COC found in the one egg that the Army sampled. Other pathways were excluded entirely, including dermal absorption due
21905 402010 - CR-02 0808110895 ingestion Of surface water to direct contact with groundwater.inhalation of dust, incidental of fruits grown in contaminated soil or irrigatedwith during wading, and consumption with or surface water. The State also believes that the Army's data contaminated groundwater on the a sensitive subpopulation. is inadequate. &&, state comments respect to pica children, other 6. 1992 at pages 2-3. The EA has also not sufficiently considered EAIFS, April area for 30 years or subpopulations such as people who might reside in the offpost sensitive a day of water; or sufferers of diabetes who are known to consume up to 8 liters longer; sensitivity syndrome. of predisposed sensitivity such as victims of multiple chemical people Related to the Human See, state comments on the EAIFS, January 27, 1992, Comments Health Endanzerment Assessmgnt. at pages 2-3. were not sufficiently its letter, EPA specifically noted that a number of uncertainties In point of departure if these addressed in the Risk Assessment. and that 10-6was the required estimates for develop- issues were not addressed. These concerns include lack of toxicity contaminants, the fact that mental toxicants, no consideration of synergism1antagonismof lack of considerationof the the monitoring data may not represent actual site conditions, and The State contends that soil type and climate present offpost relative to soil ingestion rates. therefore use of 10' as these uncertaintieshave not been adequately addressed in the EA, and the target risk level for cleanup is not appropriate. not including several of For some zones, accordingto the Army. the risk is as high 3 X 101 is not justified on the basis the important pathways described above. This relatively high risk unacceptable to the State. of technical impracticabilityor any other rationale. It is therefore of Departure at 10' State urges the Army to comply with the NCP. which sets the Point The of this level is risk level. 40 C.F.R. J300.430(e)(2)(i)(A)(2) (1991). Only if achievement impracticable.may the Army adopt a less protective cleanup level.
Resr)onse (EPA) guidance and the The Army his closely followed US. Environmental Protection Agency regarding the use of the National Oil and Hazardous Substances Pollution Contingency Plan (NCP) that if the 10' risk threshold to assess whether remediation is necessary. Guidance states not be warranted cumulative cancer risk to an individual is less than 10', remedial action may the 10' to 10' risk unless certain site-specific conditions exist. If remedial action is warranted, further states range must be achieved, with an initial preference for the 10' end. EPA guidance. the acceptable that the upper boundary of the risk range is not an absolute at I x 10', but rather, of 3 x 10', risk range can extend to 5 x 10'. The cumulative offpost cancer risk is a maximum which is within the acceptable risk range. NCP, states In explaining the use of the point of departure. the EPA, in the preamble to the
The use of 10' expresses EPA's preference for remedial actions that result in risks at the more protective end of the risk nange, but does not reflect a presumption that the final remedial action should attain such a risk level (55 Federal Register 8718).
The operation of the Off post Groundwater Intercept and Treatment System reflects the Army's goal of further reducing the potential risk toward the 10'6 level.
21905402010 - CR-02 0908110895 2 considered all of the In addition to the pathways retained in the risk assessment, the Army presented in Risk exposure pathways listed by the State and, on the basis of EPA guidance were eliminated from further Assessment Guidance for Superfund (RAGS), the latter pathways health risk assessment pathways evaluation in the risk assessment. The Army presented the human and the State for to EPA, the U.S. Fish and Wildlife Service (USFWS), Shell Oil Company, the Army followed EPA discussion. After identifying all potential complete exposure pathways, further in the exposure guidance in RAGS (page 6-16) to select those pathways to be evaluated pathways if there is sound assessment. Guidance allows for the elimination of some complete justification, such as: from another pathway I . The exposure resulting from the pathway is much less than that involving the same medium at the same exposure point. low. 2. The potential magnitude of the exposure from the pathway is associated with the 3. The probability of the exposure occurring is very low, and the risks occurrence are not high. during bathing or The Army did consider dermal absorption of contaminated groundwater [EA]); however, this showering (see page 11-2-61, Volume H of the Endangerment Assessment to be very small when pathway's contribution to the overall intake and risk was considered The inhalation compared to the intake of groundwater contaminants via ingestion and inhalation. B, Volume IV of the of dust is addressed on pages 11-2-59 and 11-2-60, Volume 11 and Appendix in Appendix B EA. The conservative screening level model of exposure to dust presented incidental direct soil indicated that the contact rate via this route is very small compared to 11-2-63 of the EA). ingestion. The incidental ingestion of surface water was considered (see page contributor to However, it is highly unlikely that this route for exposure would be a significant rate, and concentration of the overall risk because of the low frequency of occurrence, ingestion (see contaminants in surface water. The ingestion of homegrown fruit was considered tomatoes were page 11-2-62 of the EA); however, for the purpose of the offpost risk assessment, considered as a vegetable. Fruit production is such a minor contributor to the agricultural economists. economy of the area that fruit production statistics are not kept by local agricultural was only Therefore, fruit ingestion was not evaluated. Intake via the consumption of eggs in the egg sample. evaluated for dieldrin because dieldrin was the only contaminant detected pica The Army has previously responded to the State's request that soil ingestion rates related to soil behavior be considered. The Army followed EPA's guidance in RAGS to evaluate the and ingestion pathway and the soil ingestion rate. The rate used accounts for both outdoor soil value (a indoor dust ingestion by children and is considered by EPA to represent an upperbound is aware of conservative value that is highly unlikely to result in an underestimation of risk). EPA is the the information presented by the State. EPA guidance specific to CERCLA risk assessments most reliabie and authoritative source for the soil Ingestion exposure parameter.
The use of a water consumption rate of 8 liters per day (1/day) would not be representative of the majority of individuals in the area. The EPA does not consider worst case risk assessments to be was beneficial in evaluating the overall potential risk at a site. A water ingestion rate of 2 I/day used as the adult water ingestion rate in accordance with EPA guidance. While multiple chemical sensitivities may exist for some individuals, the evaluation of this potential effect is difficult
21905 402010 - CR-02 0908110895 3 believes that the because of the lack of comprehensive scientific information. The Army account for this possible effect. conservative uncertainties in the risk assessment more than likely of concern (COCs), the Army When evaluating the potential noncarcinogenic effects of chemicals according to their toxicological followed EPA guidance in identifying and segregating constituents was done on the basis of endpoints, including mechanisms of action. This categorization available at the time the risk toxicological information provided in the toxicology databases System [ER.IS] and the Health assessment was conducted (e.g., EPA's Integrated Risk Information lists the target organ or system Effects Assessment Summary Tables). Table 4.0-1 in the EA was unavailable from these databases categories identified for the COCs evaluated. Information information was available from on the developmental effects of these COCs. If chemical-specific concern for developmental effects. these sources, it would have been used to evaluate the potential scientific literature describing It is possible that some information is available in the open has not been peer-reviewed potential developmental effects; however, this information apparently assessment databases. EPA specifi- by EPA toxicologists for inclusion in the recommended risk sources to be consulted when perform- cally recommends a hierarchy of toxicological information sources of information are the ing a baseline risk assessment, and nonpeer- reviewed scientific least preferred. evaluating the potential synergistic The Army followed accepted practice and EPA guidance when number of possible toxicologi- and antagonistic interactions of the COCs. Because of the infinite interactions, EPA guidance cal outcomes. most of them unknown, resulting from chemical and noncarcinogenic recommends a cautious assumption of dose additivity for both carcinogenic specified in EPA's RAGS and health effects. The Army applied this widely accepted practice as application of dose additivity Guidelines for Health Risk Assessment of Chemical Mixtures. The general and on the mix of is prudent because of the lack of information on chemical mixtures in chemicals present in the Offpost Ope:able Unit specifically. not represent actual The Army disagrees with the State's assertion that "the monitoring data may measured soil, ground- site conditions.' The State has provided no supportive evidence that the of actual site water, surface water. sediment, or air concentrations are not indeed representative have been obtained condition.s. Over the last decade, tens of thousands of analytical data points its monitoring from the Offpost Study Area. The Army is continuing to refine and enhance The Army is programs to provide the most representative data for all areas under investigation. environmental confident that it his adequately monitored and will continue to adequately monitor conditions in the Of fpost Study Area.
b. Hazard Indeit and The Final Endangerment Assessment IFeasibility Study indicates that for both chronic 4: the acute resiJential child non-cancer risks. the Hazard Index exceeds I in Zones 2, 3. and Ha:ard Index for Zone 4 is four ttme3 the acceptable limit. In Zone IB, the child acute Ha:crd Index exceeds 1. In other words. children exposed to existing contamination in the manner described in the EA would be expected to suffer adverse effects. (See Tables 4.1.1-2. -3). This is contrary to the NCP. &C NCP. 40 C.F.R. §300.430(e)(2)(i)(A)(1) (1991). See also: EPA guidance. Risk Assessment Guidance for Superfund RAGs). Volume 1. Part A which states that the Hazard Indices may not exceed I and still be considered consistent with the remedial goals of the NCP.
21905 402010 - CR-02 08N110895 4 Response to existing contamination in the The Army disagrees with the assertion that "children exposed effects," and that a Hazard Index manner described in the EA would be expected to suffer adverse Assessment Guidance for Superfund of I represents the "acceptable limit." According to the Risk indicator of adverse effects nor (RAGS), exceedance of a haza d index of I is neither an absolute greater than I does not indicate an indication of probability of adverse effects. A h2za d index 8-13) states w[w]hen the hazard that anyone is expected to suffer adverse effects. RAGS (page effects" (emphasis added). index exceeds unity, there may be concern for potential health FR 34019, Similarly, the Guidelines for the Health Risk Assessment of Chemical Mixtures (51 measure of likely toxicity and September 24, 1986) state that "(t)he haza d index provides a rough hazard index exceeds I depends requires cautious interpretation." The degree of concern when the used in the risk assessment, the on several issues including the conservativeness of the assumptions index from specific likelihood of exposure occurring, and the contributions to the hazard environmental media. intake by the reference The hazard index is calculated by dividing the estimated daily chemical the derivation of both the dose (RfD). The hazard index is thus subject to uncertainties from to understand the basis and estimated intake and the reference dose. Therefore, it is important defined by the EPA in the interpretation of both the reference dose and hazard index. As 1987, the reference dose Integrated Risk Information System, Supportive Documentation, March is: of the An estimate (with uncertainty spanning perhaps an order of magnitude) that is daily exposure to the human population (including sensitive subgroups) likely to be without appreciable risk of deleterious effect during a lifetime. in concept to the The reference dose (from which the hazard indices are calculated) is similar was changed because of acceptable daily intake (ADI). the term previously used. The term ADI interpretation of the connotation that any dose above the ADI was *unaccepmble.' The general the ADI. at the time of its use. was: to A 'ballpark figure" which represents a level of exposure which is not likely result in adverse effects in humans. It is viewed as a soft estimate in that exposures somewhat higher than the ADI are generally not expected to result in adverse effects; only if the ADI is significantly exceeded would one expect such negative consequences (50 FR 46936. November 13, 1985). manager to The IRIS Supportive Documentation further states '(0t is generally useful to the risk media." In have information regarding the contribution to the RrD from various environmental in the this context, it is important to recognize two issues. First, the hazard indices summarized in the EA tables are representative of the reasonable maximum exposure (RME). As presented and uncertainty analysis discussion in the EA. the estimated RME exposure concentrations resultant hazard indices may be overestimated by a factor as high as 5. Secondly, although in the risk domestic use of alluvial groundwater is not a complete exposure pathway, its inclusion contributes assessment contributes significantly to the estimated risks. For example, this pathway exposure to 56 percent of the child chronic hepatic hazard index even though it is not a current are pathway. Therefore, it is likely that the estimated hazard indices presented in the EA conservative and overestimated.
21905 402010 - CR-02 0808110895 5 The cited section of the NCP smtes: concentration For systemic toxicants, acceptable exposure levels shall represent may be levels to which the human population, including sensitive subgroups, lifetime, incor- exposed without adverse effect during a lifetime or part of a porating an adequate margin of safety. contains several safety factors, The methodology for the derivation of the reference dose itself of magnitude. The hazard index and, as indicated, is associated with an uncertainty of an order value of I and therefore should not value of 4 is within an order of magnitude of a hazard index stated that there is uncertainty be viewed as connoting unacceptability. Because the EPA has a hazard index value of I as a associated with the ha" d index values, it is inappropriate to use definitive cutoff value. in the derivation of the The Army believes that the uncertainties and safety factors inherent of the hazard index, the reference dose, the statements by EPA regarding the interpretation and recognition that several probable overestimation of the hazard index by the EA methodology, not currently exist, indicate that exposure pathways associated with the alluvial groundwater do In fact, the hazard index of 4 should not be viewed as absolute indicator of unacceptability. index of 4 should be viewed as because of the conservative nature of the risk assessment, a hazard supporting a conclusion of minimal risk. than I are unacceptable. RAGS, Volume 1, Part A does not state that hazard indices greater for an exposed individual or Rather, page 8-16 of RAGS states that "(w)hen the total hazard index effects* (emphasis group exceeds unity, there may be concern for potential noricancer health efforts added). On page 8-25 of RAGS, the guidance on summarizing the risk characterization of the cancer risks and states that the summary should include, among other things, the magnitude in the NCP. noncancer hazard indices relative to the Superfund site remediation goals goal of 10'6, needs The attainment of the hazard index goal of 1.0. like the cancer risk remediation to be tempered with the purpose of the goal and the site-specific and risk-assessment-specific 1.0, contami- issues reflected in the final risk estimates. In the areas where hazard index exceeds the Offpost nants in groundwater contribute the majority of the hazard index. Operation of haza d Groundwater Intercept and Treatment System will result in a reduction in the estimated indices.
C. Endangerment Assessment
The State remains concerned with the methods used by the Army in defining cleanup levels thaz are protective of biota. We believe that levels of contaminationremaining in the offpost in may pose potential health threats to wildlife. The State was not allowed to participate several dispute resolution meetings where issues such as defining maximum allowable tissue concentralions (MATCs) were discussed and formalized. In addition, on 4119193, the State provided the Parties with a report. 'State of Colorado Proposal on How to Conduct a Site of Specific Ecological Risk Assessment at the Rocky Mountain Arsenal.' While the timing and this report made it difficult to incorporate into the offpost EA, a majority of the concerns ERC methodologies identified in the report were provided to the Army orally through EA subcommittee meetings and by written comments prior to finalization of the offpost EAIFS
21905 402010 - CR-02 0808110895 6 Army on our report. We report. To date, we have yet to receive any comments from the biota is well-justified and believe this approach to defining cleanup levels protective of should be used for both the on and offpost Endangerment Assessments.
Response that assumptions made for the The State has not presented any evidence to support its contention remaining in the Offpost ecological risk assessment (RA) will result in levels of contamination presented the ecological RA assump- Study Area that may not be protective of biota. The Army EPA, Shell Oil Company, and tions and approaches to the U.S. Fish and Wildlife Service (USFWS), The Army considered these the State at meetings throughout the ecological RA study period. of formalized EPA guidance on meetings and subsequent feedback critical because of the lack that the findings of the conducting a dose-based ecological assessment. The Army believes of the approaches used to estimate ecological RA are protective of wildlife because many aspects methodologies currently potential effects are more conservative than other haza d assessment conducting an ecological RA are followed by EPA and other agencies. Because the approaches to used by the Army for the final continually being developed, the assumptions and parameters throughout the ecological ecological RA were thoroughly discussed with the parties and modified professional judgement were used. RA process, and the best available methodology and informed the final methodologies used The USFWS participated in the ec:)Iogical RA process and supported to evaluate the potential ecological haza d to the FederalFacility Dispute resolution meetings were open for attendance by all signatories Comments, the State of Colorado Agreement. As indicated in the introduction to the Response to and issue resolution declined to sign the FFA and become an official party to all proceedings States's comments (both verbal meetings pertaining to RMA activities. The Army is aware of the risk assessment. These and written) regarding the methodologies used to conduct the ecological was reached by the issues were discussed at the dispute resolution meetings and agreement tissue concentrations involved parties. The Army believes that the final maximum allowable to define the (MATCs) agreed to by the EPA, USFWS, and Shell Oil Company are sufficient cleanup levels protective of offpost biota.
Comment No. 2 - State Groundwater ConceM a. Selected Groundwater Cleanup Alternative implemented The Army has chosen Alternative No. N-4. essentially continuation of an already that interim response action. as its preferred alternative for the offpost. The State believes the NCP this remed 'v is not sufficiently justified in accordance with the selection criteriain and CERCLA and that a more aggressive groundwater cleanup alternative is appropriate. of Items I through 3 below explain why the State does not agree with the Army's selection and Alternative N-4. The State has obtained and reviewed the groundwater model created used by the Army to evaluate groundwater cleanup alternativesfor the north and northwest plume groups, and has concluded that a more efficient alternative could be selected for the north plume group based on this analysis (see item 4).
21905 402010 - CR-02 0808110895 7 1. Cost Considerations they would require Alternatives N-5 and N-6 were eliminated based mostly on the fact that failed to consider greater initial capital outlay than the selected alternative. This decision the environment and the fact that the rejected alternatives would be more protective of though it is more cost remediation time frame. N-5 was eliminated even provide ashorter less than N-4, since effective than N-4, given that its total present worth costs are actually N-5 has a shorter predicted remedial time frame. Response of Alternatives N-5 and N-6. The State has incorrectly stated the Army's rationale for elimination 4.2.1, Screening of Alterna- As presented in the Final Offpost EA/FS report Volume V1, Section criteria were explicitly tives - North Plume Group, effectiveness, implementability, and cost of the EA/FS, it was evaluated consistent with the requirements of the NCP. In this section in toxicity, mobility, concluded that Alternatives N-4, N-5, and N-6 afford the best reduction remediation goals. and volume, the best long-term protection, and the best compliance with in comparison Alternative N-6 was screened out at this point on the basis of shmila performance volume, yet it afforded with Alternative N-5 with respect to reduction in toxicity, mobility, and cost. no benefit in terms of remediation timeframe (10 to 20 years) and at higher because Alternative N-4 The Army selected Alternative N-4 instead of Alternative N-5 primarily to be necessary based includes potential future modifications, only if such modifications are found System. Selection on actual operating data, to the Offpost Groundwater Intercept and Treatment a more cost effective of Alternative N-5 instead of Alternative N-4 will not necessarily provide The Army based its alternative because of a slightly shorter estimated remediation timeframe. and estimates of assessment of the relative differences between the groundwater alternatives thus, the remediation timeframes on groundwater models that are very general in nature; Use of actual estimated remediation timeframes should not be construed as precise predictions. Offpost full-scale operating data is preferable to selecting additional components for the (i.e., Groundwater Intercept and Treatment System using the more speculative modeling data Alternative N-5). and The Army is committed to efficient operation of the Off post Groundwater Intercept Treatment System and will evaluate operating data to assess the need for system modification. Similar to the onpost boundary treatment systems, it is difficult to assess whether the installation of additional wells will provide more efficient operation without collecting full-scale operating an data for the Offpost Groundwater Intercept and Treatment System. The Army his included the intensive monitoring component as pan of the preferred alternative, Alternative N-4, in Proposed Plan. This intensive monitoring program will allow the collection and subsequent interpretation of performance data for the full-scale operation of both the Offpost Groundwater assess Intercept and Treatment System and the onpost boundary systems. The data will be used to the need for any improvement to the systems and will provide increased accuracy in assessing wells contaminant cleanup. Acquisition of this operational data is preferable to adding extraction and recharge trenches without the benefit of operational data, because additional data are required to assess the necessity and placement of any additional extraction wells or trenches. If operational data supports the conclusion that the cleanup timeframe can be shortened without a significant increase in long-term costs, modifications to Alternative N-4 will be implemented. By taking tbLis approach, improvements to the system will be more effective than improvements made based on computer modeling data.
21905 402010 - CR-02 0908110895 8 2. Cleanup Time Frames own projected cleanup time Alternative N-4 was selected over N-5 even though the Army's remediation. The Army show N-5 requiring one-third less time for groundwater frames be viewed as a tool for has cautioned that its time frames are only estimates and should used its model for the comparison between alternatives. Apparently, the Army has not by the Army are 15-30 years for for which it was designed. Estimates provided purpose Based on our understanding N-4 and 10-20 years for N-5. This is a substantial reduction. the State believes that of groundwater flow, and the contaminants of concern in the offpost, Army estimates, and in the actual remedial time frames will be significantly longer than important in terms of that case. a one-third reduction in cleanup time would be even more reduced cleanup costs. protection for human health and the environment, as well as
Resr)onse based on use of actual field The Army's basis for selection of Alternative N-4 over N-5 is (NBCS) and the Offpost operating data from both the North Boundary Containment System an integrated set of offpost Groundwater Intercept and Treatment System in combination with decisions about the need for groundwater monitoring programs (as in Alternative N-4) to make This approach is fundamen- an Offpost Groundwater Intercept and Treatment System upgrades. which would proceed with tally superior to the methodology structured in Alternative N-5, System, based on groundwater modifications to the Offpost Groundwater Intercept and Treatment modeling results alone. that predict a slightly The State claims that the Army should have relied on the model simulations an approach that would shorter cleanup time for Alternative N-5 as compared to N-4 to select however, has selected install additional wells and trenches based on modeling. The Army, used to optimize any required Alternative N-4 because actual field operating data can be better system modifications.
3. Short-term Monitoring intensive The Army has stated that N-4 is superior to N-5 because N-4's short-term of all, monitoring will '.. identify any necessary improvements to the system..." First to determine short-term performance monitoring should logically be a part of any remedy whether the system is functioning as planned. Second. it appears from the detailed In the analysis of alternatives that N-5 does include a similar monitoring scenario. for both Feasibility Study. the Army describes how performance would be monitored both plans alternatives (Offpost EAIFS. Final Report. pgs. VI-3-14 and VI-5-21). Since for coniain provisions for short term intensive monitoring, this is not a proper basis selection of N-4 over N-3.
Resi)onse of Alterna- The Army has not relied on the short-term intensive monitoring program component is tive N-4 in selecting Alternative N-4 over N-5. The rationale and basis for this selection presented in responses to parts I and 2 of State Comment No. 2.
21905 402010 - CR-02 0808110895 9 the Final Offpost In addition, the State has incorrectly stated that the referenced sections of program. In fact, the State's EA/FS report describe the same short-term intensive monitoring 5.4.1, which evaluates the remedial citation, Offpost EA/FS report Vol. VI pg. 5 - 14 is in Section health and the environ- alternatives with respect to the criterion of overall protection of human monitoring component of Alternative N-4 is explicitly referenced ment. The intensive short-term (Final while it is not referenced for Alternative N-5. The States second citation in this section, to monitor- EA/FS report Vol. VI pg. 5-21 in Section 5.4.3) contains a general reference Offpost alternatives and ing for both Alternatives N-4 and N-5 in the context of evaluating both for either Alternative permanence. There is no reference to the short-term monitoring component N-4 or N-5.
N-5A and N-5B 4. Optimizing Selected Groundwater Remedial Alternative - Alternatives they the Army states that Alternatives N-4 and N-5 are essentially equivalent, Though b) select Alternative N-4 because: a) it is claimed to be more readily implementable. data, and therefore, is system modification is based on operation data. rather than modeled more effective, and c) the additionalcapital expenditures of N-5 are not considered is justified until performance monitoring data are available. The Army's justification N-4. This, in based on the premise that Alternative N-5 is an enhancement to Alternative the Feasibility part, is a fault of the range of alternatives considered by the Army during Study. to Using the Army's model, the State has been able to improve on N-5. Two modifications as Alternative N- Alternative N-5 are presented. The first modification will be referred to center of 5A. The main improvement comes by relocating extraction wells closer to the due to this mass of the dieldrin plume. The dieldrin plumes are located further upgradient. dieldrin is contaminant's lower relative mobility. The simulated cleanup times indicate that cleanup the limiting constituent (i.e. the one taking the most amount of time to reach the the goals). Therefore. the first modification focusses on this contaminant to decrease overall remedial duration.
Alternative N-5 consists of an expansion to Alternative N-4 (IRA A). In the North Paleochannel,however. the expansion well is located very near the IRA and results in only a 15% reduction of the cleanup time for dieldrin compared to N-4. Alternative N-5A consists of modifying Alternative N-5 by relocating the extraction wells and reinjection trenches to reduce the cleanup time of the dieldrin plume by containing it within its current boundaries thereby preventing further degradationof the aquifer. Alternative N-5A uses the same number of pumping wells pumping at the same rate (30 gallons per minute). However. the number of recharge trenches is reduced from the six used for N-5 to three used for N-5A thus reducing capital costs.
Simulating Alternative N-5A with the Army's model. the Slate was able to decrease the time estimated to achieve ARARs for dieldrin by approximately 30% compared to the time estimated for Alternative N-5. The cleanup time for chloroform increases by about 15%. However. due to chloroform's greater mobility compared to dieldrin, the cleanup time for chloroform is still less than that of dieldrin. This decrease in the operationalperiod, combined with lower capital costs than N-5. results in a present worth cost of alternative N-5A of S53.5 to 59.3 million compared to the present worth cost of Alternative N-4 ($56.5
21905 402010 - CR-02 0908110895 10 combined to 63.1 million) and N-5 (S56.2 to 63 million). The improvement in total cost Alternative N-5A. with the decrease in the time of the remediation shows the benefit of
modification to Alternative N-5 is referred to as N-5B. Though simulation The second it that Alternative N-5A was superior to Alternative N-5 (and N-4) since revealed cleanup the cleanup time for dieldrin, it also resulted in a slight increase in the decreased Alternative for the rest of the plume, in particular,chloroform as compared to N-5. time trench near the N-5B builds on N-5A by placing an additional extraction well and recharge All wells center of mass of the limiting compound for the rest of the plume, chloroform. receives the each injection well-pair constitutes a recharge trench and pump at 30 gpm; near the water from one pumping well. The addition of the extraction well and trench chloroform chloroform center of mass results in a decrease in the cleanup time for are (approximately 8% faster than N-5). The simulated cleanup times for dieldrin on the predicted approximately the same as cleanup times for Alternative N-5A. Based that the cleanup time frames for chloroform and dieldrin in Alternative N-5B, it's possible portion of the Alternative (the N-5 wells and the additionalN-5B well-pair) downgradient portion could be turned off when the chloroform plume is remediated while the upgradient would continue to operate. reduction The present worth cost of Alternative N-5B would be S53.9 to 60.0 million. The remediation time in total cost compared with N-4 coupled with an even further decrease in The State will for the chloroform plume over N-5A shows this alternativeto be superior. analysis within the next 10 days. provide the Army with a more detailed description of this
Response alternatives in the The Army's offpost groundwater modeling study used in evaluating remedial from the Off post EA/FS report was based on hydraulic and contaminant distribution data have 1989/1990 time period. Since that time, significant changes in contaminant distribution continuation of occurred, apparently resulting from recent improvements with the NBCS and the approxi- reduced contaminant concentration trends from past NBCS improvements. In addition, and mately 85 new monitoring wells have been installed offpost in the past two years. Geologic conceptual hydraulic data from these new wells have greatly improved the Army's hydrogeologic offpost prior to model off post. Baseline groundwater sampling episodes of new and existing wells contaminant operating the Off post Groundwater Intercept and Treatment System indicated smaller definition plumes than were present in 1989/1990. The new wells have resulted in more precise of the plumes. With the wealth of new information resulting from the implementation and and monitoring of the Offpost Groundwater Intercept and Treatment System, it is illogical inappropriate to base potential expansion of the Offpost Groundwater Intercept and Treatment System on data that does not include full-scale operation.
Selection of Alternative N-4 over N-5, N-5A. and N-513 is based only in part on modeling results. The State has failed to consider other factors in the selection process and the dynamic nature of the contaminant distribution off post due to the continuing effects on contaminant distribution and concentration in the off post from NBCS modifications. The State has also placed or too much emphasis on the modeling results alone for recommending either Alternative N-5A N-513 over Alternative N-4 . Given the fact that the Offpost Groundwater Intercept and Treatment System has been fully operational since June 1993 and a wealth of new information is becoming available for evaluating the Off post Study Area, it makes little sense to rely heavily
21905 402010 - CR-02 0808110895 full-scale data. upon the FS modeling results for selection of the preferred alternative and ignore Altemative N-4 fits this goal It is the Army's goal to select the most technically sound alternative. as a basis for potential system by considering the most current information on plume distribution expansion. b. Dieldrin Certified Reporting Limit by its certified The Army's characterizationof the dieldrin groundwater plumes is limited the state's reporting limit (CRL) of 0.05 pg1l. This is unacceptable because it is above objected to the health-basedARAR of 0.002 pg1l. Since 1987, the State has repeatedly are higher than Army's use of its CRL methodology because it results in detection limits that This issue EPA method detection limits and. in some instances. exceed health-based levels. The Army was again raised in the state comments on the RIIEAIFS Workplan, 1126190. and promised to get its CRLs down in the Final Decision Document Groundwater Intercept Trearment System North of RMA, July. 1989. pp. 37-38.
Remonse Army does not First, as discussed in the response to State Comment No. 4 in this section, the ARARs. consider the Colorado Basic standards for Groundwater to be chemical-specific CCR 1002-8), Secondly, Table A, Section 3.11.5(C) of the Basic Standards for Groundwater (5 of 0.1 pg/l. lists the standard for dieldrin as 0.002 pg/l, with a practical quantitation limit (PQL) Furthermore, Section 3.11.5(CX4) states:
Whenever the current detection level (PQL) for a pollutant is higher (less strin- gent) than a standard listed in Subsection 2 or 3 above, the detection level shall be used as the performance standard in regulating specific activities. The detection levels (PQL's) identified in Table A shall apply, unless and until they are mod- if ied as the result of a subsequent rulemaking hearing. (emphasis added) 0.1 Thus, the State's enforceable numerical performance standard for dieldTin in groundwater is gg/l because the detection limit is higher than the health-based standard. The most recent proposed update of EPA's pesticide method 8081 (in Proposed Update Il to SW- 846, 3rd edition, Revision 0, November. 1"2) lists a method detection limit of 0.044 ;sg/l. Because the Army's CRL of 0.05 jAgIl is less than the Table A PQL (0.1 jig/1) obtainable by the Colorado Department of Health, and almost identical to the proposed EPA method detection limit of 0.044 ;jg/l,the Army believes its current CRL is adequate to characterize the dieldrin plume.
C. Northwest Plume
The Army has proposed no active remediation of groundwater downgradient of the northwest boundary system. Instead it is relying on flushing and dilution of the contaminants by reinjecting treated water on the downgradient (northwest) side of the boundary system. Its modeling results predict that PRGs (chloroform: 15 pg1l. dieldrin: 0.05 ;&g1l) will be achieved in approximately 3 to 8 years by this method. This is unacceptable because it does not consider remediation of the aquifer to state ARARs (chloroform: 6 Pg1l, dieldrin: 0.002
2190S 402010 - CR-02 0809110895 12 to the aquifer at concen- ug.11). Moreover, water treated at the boundary is being reinjected improve the boundary trations above the state ARARs. Therefore, the Army must first to levels below the state treatment process whereby the effluent concentrationsare lowered leading edge of the dieldrin ARARs. Additional data should be obtained to determine the standard of .002 plume based on detection limits at or approachingthe state's health-based should evaluate containment pg1l. Once the plume has been adequately evaluated. the Army of the dieldrin plume.
Response Basic Standards for Groundwater As described in response to State Comment No. 4, Colorado were not found to be chemical-specific ARARs. (NWBCS) being recharged Treated water from the Northwest Boundary Containment System meets the remediation goals set forth in the ROD. characterized by the Army. The dieldrin plume downgradient of the NWBCS has been adequately limit. Response to State Comment No. 2b addresses the dieldrin detection d. State DIMP Standard and the Provision of Bottled Water (DIMP)" The report entitled "Human Effects Assessment of Diisopropyl Methylphosphonale the Army and EPA for by Edward J. Calabrese (1990 Report) has been in the possession of As more fully several years and is hereby incorporated into these comments by reference. the EPA DIMP explained in that report and as stated previously, the Stale cannot accept we believe that Health Advisory of 600 ug/I as being protective of human health. Therefore. below that level, the Arm 'Vs remedy, which does not attempt to prevent exposures to DIMP NCP which violates section 121(b) of CERCLA and section 300.430(e)(9)(iii)(a) of the establish protectiveness as a threshold criterion for all CERCLA remedies. DIMP Health To brieflY summarize Dr. Calabrese's report. the State believes that the EPA AdvisorY is unsupportable because it incorrectly disregardsthe 1979 Aulerich reproductive the Aulerich study on mink in which the authurs noted treatment-related deaths. EPA rejected estimates was study for two reasons: (1) the extrapolative relevance of mink to human toxicity of adverse unknown: and (2) the background mortality of mink confounded any findings by Dr. effects in the treated groups. Both of these concerns have been thoroughly explored reflected Calabrese's research which has been communicated to the EPA and the Army and is in the 1990 Report at pages 8-51. control Because mink have been demonstrated to be an appropriateanimal model; because the control in the Aulerich study was demonstrated to have behaved consistently with the historical constructed from relevant studies conducted at Michigan State University, and therefore should be used: and because the mink demonstrated a clear, statistically significant dose- response relationshipto DIMP. it must be adopted as the critical study from which to derive an acceptable drinking water standard. Such an approach is consistent with the rules established by EPA and set forth in its Iniegrated Risk Information System (IRIS) which establishes the general methodology to be used to establish reference doses or "acceptable daily intake" values and, ultimately. water quality standards. A copy of that methodology is
21905 402010 - CR-02 0808110895 13 the most sensitive species attached. IRIS mandates that health-based standards be based on were noted in EPA's selected investigated. Since no statistically significant adverse effects to exposure to critical study using beagles and since mink experienced death in response base a standard. DIMP, the mink study is clearly the appropriatestudy upon which to documentation is Rejection of the mink study in the face of Dr. Calabrese'scompelling arbitraryand capricious. of IRIS to the To further explain the application of the generally accepted methodology Aulerich study: in the appropriateanimal 1. identify the Lowest Observed Adverse Effect Level (LOAEL) study As LOAELs are based upon two considerations,biological and statisticalsignificance. in Dr. Calabrese's report the lowest does. 11 mglkglday, is the LOAEL demonstrated that the based upon regression analysis of the data. The State agrees with Dr. Calabrese or trend more appropriatestatistical analysis to apply in this instance is regression. control. This analysis rather than pair-wise comparison between each dose group and the as a result of is because pair-wise comparisons can mask treatment-relatedeffects insufficient statistical power due to relatively small sample size.
2. Apply appropriateuncertainty factors (UFs)
IRIS recognized four fundamental areas of uncertainty:
a. LOAEL to NOAEL (no observed adverse effect level) b. interspecies extrapolation c. intraspecies variation d. less than lifetime study duration
The scope of these factors is described in Dr. Calabrese's 1990 Report at pages 66-69. the Each of the factors is given a default value of 10. and all of them must be applied to LOAEL identified in the Aulerich study.
In addition. IRIS recognaes that problems with available data may indicate a need for further reduction of a dose in certain instances. Dr. Calabresebelieves that because death is a frank effect level (FEL). not a LOAEL. the factor of 10 for LOAEL to NOAEL extrapolation is insufficiently protective. and therefore recommends an additional modify- ing factor of 5. The State has elected not to adopt this recommendation because, although ioxicologists may legitimaiely disagree it is the professional judgement of CDH that application of the other four uncertaint) factors In this instance results in a sufficiently conservative exposure level.
3. Calculation of Drinking Water Equivalent Level
Once an adjusted 'NOAEL' is established it remains necessary to calculate an appropriate drinking water concentration which would ensure that exposure over a 70 year life-span would not result in an exceedance of that NOAEL. This is done based upon certain exposure assumptions adopted by EPA and explained in the 1990 Report. Dr. Calabrese
21905 402010 - CR-02 0908110895 14 recommends that has deviated from standard IRIS methodology in two respects: (1) he is the average of the average body weight of women, be used instead of 70 kg. which 65 kg, be employed and female body weights; (2) he recommends that surface area scaling male have merit, to adjust the mink dose to a human dose. Although these recommendations been incorporated into CDH is not adopting them at this time because they have not yet above descriptions, an state and federal regulatory programs. Accordingly, based on the be: appropriatecalculation of a arinking water level for DIMP would
(1) 11 mzlkrlday (LOAEL) - 0.0011 mglkglday 10,000 pgll (2) 0.00 11 me Ag Iday x- 70 kr x 0.2 = 0.0077 mg1l = 7.7 2 IiiersIday = 8.0,ugll
(0.2 is the source contribution from groundwater) of standard selection of the Aulerich mink study as the critical study, and application In conclusion. This level to that study results in a drinking water equivalent level of 8 14g1l. IRIS methodology The treatment be incorporatedas a remediation goal by the Army into its Proposed Plan. should and the Army should be operated to achieve a level of no more than 8 pgll in its effluent, facility exceed 8 pg1l. should evaluate the feasibility of containing the DIMP plume where concentrations of public health by Where active remediation is impracticable.the Army could ensure the protection unknowing use of the providing an alternative water supply, and institutionalcontrols to prevent water in contaminated areas.
Resoonse diisopropyl The U.S Environmental Protection Agency (EPA) developed the Health Advisory'for than 30 existing methylphosphonate (DIMP) in 1989 on the basis of an extensive review of more Drinking Water re- toxlcologý studies involving a variety of animal species. EPA's Office of on March 28, 1990, reviewed the Health Advisory, in light of the State's concern, and concluded the best scientific that *the existing Health Advisory values and the basis for the values represent 121(b) of position for the protection of human health." The Army is not in violation of Section standard proposed by CERCLA and Section 300.430 (eX9)(iii)(a) of the NCP because the DIMP the State has not been promulgated. mink study as The Arm) contends that the EPA acted appropriately when rejecting the Aulerich on the basis of the critical stuJ) on which to establish a human health drinking water advisory mortality in extrapol2iii-e relevance to humans and the confounding influences of background mink. The Arm% disagrees with the State's statement that IRIS mandates that health-based "concept paper" standards be bawd on the most sensitive species tested. IRIS describes through a in Health Risk (IRIS Background Document IA - Reference Dose (RfD): Description and Use implies Assessment) the recommended approach to select the most appropriate critical study and when the use of informed professional judgment when making that selection, particularly high-level identifying the animal model that is most rele%ant to humans. EPA uses a panel of of a single peer scientists to make the critical stud% selection rather than relying on the opinions individual.
21905 402010 - CR-02 0808110895 15 flaws in the health-based DIMP standard The CDH apparently recognizes some of the additional application of an additional Dr. Calabrese. The State is correct that Dr. Calabrese's proposed by use of some exposure overall uncertainty is inappropriate as wen as the modifying factor of 5 to health- as described by Dr. Calabrese illustrates how unrealistic parameters. In fact, the approach arbitrary guidelines recommended by EPA are followed as an based standards are derived when and "yes or no paradigm, ignoring informed professional judgment (peer review) on biological toxicologi:al relevance. for Superfund (RAGS), the Army used In accordance with EPA's Risk Assessment Guidance the IRIS database to evaluate risk to human EPA's Health Advisory and information contained in health.
System e. DIMP Exceedances; Past the First Creek Intercept DIMP plume has already passed the The State is concerned that a portion of the concentrated chemical, greater than 600 ppb, offpost intercept system, leaving concentrations of the the Army is unaware of the extent unremediazed. This concern is compounded by the fact that downgradientof the intercept of this plume. Additional characterizationof the groundwater be evaluated to attempt to capture system is necessary. Additional alternatives should then affects a larger number of this plume before this high concentrationof DIMP contamination domestic wells.
Resr)onse is located in areas of highest contam- The Off post Groundwater Intercept and Treatment System of DIMP greater than 600 parts per inant concentrations. The Army is aware that concentrations Intercept and Treatment billion (ppb) have been reported north of the Offpost Groundwater monitoring program will be System. In that regard, the offpost remedial action groundwater active in the Offpost Study coordinated with the three existing groundwater monitoring programs Program, (2) the Interim Area. These three programs are (1) the Groundwater Monitoring monitoring program. Addition- Response Action A monitoring program. and (3) the private well Treatment System where DIMP ally, in the area north of the Offpost Groundwater Intercept and be replaced and three new has been reported to exceed 600 ppb, three monitoring wells will for three wells originally monitoring wells will be installed. Replacement wells are being installed Two new monitoring in the monitoring network that were found to be damaged or destroyed. and one new monitoring well will wells will be installed downgmdient of the First Creek Pathway, of the three new monitoring be installed downgradient of the northern Pathway. The purpose of the Offpost Groundwater wells is to aid in assessing the extent of contamination downgradient existing wells will be used to Intercept and Treatment System. Data collected from these wells and in this area and further define the extent of contamination greater than the remediation goals Groundwater Intercept assist in determining whether modifications to the design of the Offpost and Treatment System are necessary.
f. The Army's Definition of the DIMP Plume assess potential According to the Proposed Plan. 'The Offposi Study Area was defined to basis of north and effects of RMA-related contamination beyond the RMA boundary. On the
21905 402010 - CR-02 080911089S 16 of the Offpost northwesterly flow directions of groundwater and surface water. the boundary the South Platte River, Study Area was defined to include the area bounded by 80th Avenue, The State believes the Second Creek and the north and northwest boundaries of RMA.' reasons: Army's definition of the Offpost Study Area is insufficient for two own definition of the the Army has defined the Offpost Study Area based largely on its First. only Army extent of the DIMP plume in the alluvial aquifer. These data include areal domestic alluvial and monitoring well data and does not take into considerationnumerous to CDH data. Arapahoe wells that have consistently contained levels of DIMP, according by the South Platte River Second, the Offpost Study Area was geographically limited in part Second Creek on the east. Historically,the South Platte River has been on the west and to the as a hydrologic barrier which prevented contaminant plumes from migrating regarded on the west side west side of the river. More recent Army data reveals DIMP contamination by two CDH samples of the Platte present since 1989. This was confirmed in April of 1993 addition, detections of taken west of the Platte River, near the Army monitoring well. In Creek fall well outside DIMP in both the alluvial and Arapahoe aquifer adjacent to Second not restricted by the the Army's plume interpretation,suggesting that the DIMP "plume" is definition of the 'study area". geographic area that The State believes that the Study Area be expanded to include a larger of DIMP. includes all domestic-use and monitoring wells that contain concentrations
Response agreed to of the Offpost Study Area in the Federal Facility Agreement (FFA) was The delineation and the Army, Shell, U.S. Department of the Interior, U.S. Department of Justice, by EPA, cleanup for Toxic Substances Disease Registry (the signatories to the FFA). Groundwater Agency an expansion of standards are not exceeded in the areas outside the Offpost Study Area; therefore, the study area is unnecessary. offpost The Army has used and continues to include data from the various Army-sponsored which areas are monitoring programs and the private well monitoring programs to evaluate plume maps. impacted by RMA contamination. All available data is used in developing the data and to include, The Army will continue to use all available domestic use and monitoring well events. as appropriate, locations outside of the Offpost Study Area in future monitoring
g. Degradation of the Arapahoe Aquifer
The Army does not address the continued degradation of the deeper Arapahoe Aquifer. Since 1990. testing by the Army and the Colorado Department of Health has revealed widespread were contamination of this aquifer. Of the 70 wells so far tested for DIMP in this aquifer, 42 below detection levels (BDL). 8 samples contained Trace amounts (defined as <0.5 ppb), and 20 had measurable amounts ranging from 0.3 to 39.7 ppb. This is of concern to the State because there are a large number of domestic Arapahoe wells in the Offpost area, most of which have not yet been sampled for DIMP.
21905 402010 - CR-02 0808110895 17 CDH has presented to the Army evidence of wells known to be conduits On several occasions, into from the alluvial aquifer to the Arapahoe aquifer and consequently of contamination the State pointed neighboring Arapahoe wells. For example, at a December 11. 1991 meeting, than one water bearing out that well *985 (TCHD ID) was known to be completed over more Based on testing of zone consistent with completion practices of the time of its construction. respect to the several downgradient Arapahoe wells and their geographicallocation with acting as a conduit DIMP plume in the alluvial aquifer, it was determined that well *985 was for inter aquifer communication. Arapahoe Aquifer. State believes that the Proposed Plan must protect the integrity of the The all wells To this end, the State believes that it is essential to close, as they are identified, by evaluating each which are known to be pathways of contamination to the deeper aquifers history. geographic domestic well on a case by case basis, taking into account the completion location and geology of each candidate. violates the Colorado The State is concerned that further degradationof the Arapahoe Aquifer narrative Basic Standards for groundwater,5 CCR 1002-8. §3.12.5(2)(a). This interim system and standard specifically applies to RMA. which lies within the Denver Basin Aquifer as of provides that groundwater quality shall be maintained at either the ambient quality Since there is no October 31. 1991, or the Table Value Standards, whichever is less restrictive. that the Arapahoe fable value standard applicable to DIMP, and the Army has maintained In addition, Aquifer is clean. no degradationof the aquifer is permissible under this section. further degradation must be prevented to comply with the CBSG 5 CCR 1002-8 at the f 3.11.5(c)(1)(b). This section requires that organic pollutants must be 'maintained lowest practicablelevel.'
Remonse The The Army has incorporated well closure as a component of the offpost selected remedy. criteria for %kellclosure are presented in Appendix C of the ROD. h. lsopropýlmethyl Phosphonic Acid (IMPA) in Groundwater and Surface Water Isopropy1methyl In 1990 the EPA completed a health advisory (HA) for the compound photphonic acid (IMPA). The EPA's HA concluded that a concentration of 700 ppb is an allowahle lifetime exposure level. The Colorado Department of Health (CDH) recently finali:ed its review of EPA's HA to ensure that it is protective of human health. This review identified several areas of concern with the EPA's report and recommends a lifetime HA for /Af P A o f 6 0 ppb. CDH's review will be distributed to the Parties in the near future.
The Stair ii concerned that based on EPA's HA of 700 ppb. the Proposed Plan may not be protectite of human health and the environment. The State is primarily concerned that the Arm 'i has not adequately characteri:edIMPA contamination in the Offpost Study Area. The chemical characteristicsof IMPA indicate that the likelihood of IMPA contamination in off Post soils is small. However. Iff PA contamination in the groundwaterand surface water may be inevitable due to the compound's long half-life. its low partition coefficient, and the high concentrations of IMPA detected in groundwater onpost. Moreover, it is likely, due to its
21906 402010 - CR-02 0808110895 18 a groundwater plume similar chemical characteristics,the compound may have developed typical of DIMP. plume and the The Army has been unable to properly characterize the IMPA groundwater limit. The Army's current levels of IMPA in surface watcr due to its analytical detection number of 6 ppb. detection limit of 150 ppb is more than 20 times the state's HA provides adequate IMPA The State urges the Army to certify an analytical methodology that are not exposed to characterizationto ensure that residents in the Offpost Study Area in a timely manner, the unacceptable risks, If USATHAMA certification cannot be achieved characterizationof IMPA Army should resort to using EPA analytical methodology in its study area has been contamination. Once the characterizationof IMPA in the offpost need to be modified to completed. the endangerment assessment and feasibility study may include these data.
Rest)onse methylphosphonic acid On the basis of toxicity information summarized in EPA's isopropyl (IRIS) database, there is no (IMPA) Health Advisory and the Integrated Risk Information System may pose a threat to human information to indicate that IMPA concentrations lower than 700 ppb health. will occur in ground- unlikely that toxicologically significant concentrations of IMPA It is highly (DIMP) occurs because the abiotic formation of IMPA from diisopropyl methylphosphonate water biological conditions in the presence of heat. IMPA is primarily formed as a under alkaline of DIMP of DIMP and excreted iu the urine. The toxicological data on the metabolism metabolite and not a that the formation of IMPA is part of the metabolic elimination process indicates readily eliminated in bioactivation reaction. IMPA is a very polar metabolite that is most likely the body. the urine rather than reabsorbed by the kidneys and redistributed throughout study; however, EPA The EPA reference dose for IMPA was based on a simple IMPA subchronic conclusions indicates in IRIS that the DIMP database can be used to support the toxicological (within 24 hours) regarding IMPA because more than 90 percent of the ingested DIMP is rapidly relatively nontoxic converted to IMPA. EPA states that the DIMP studies showed that DIMP was to IMPA, it is to all species. Additionally, because DIMP is rapidly and mostly metabolized was metabolized to reasonable to conclude that the DIMP administered to mammals in the studies to indicate an absence IMPA; therefore, the absence of effects from DIMP also may be considered of effects from IMPA. indicated that IMPA Analytical data collected to date in the Offpost Study Area for IMPA has not tap water samples. is present at or above the certified reporting limit (CRL) in groundwater or 1992, the IMPA The Army's current CRL for IMPA is 25 ppb. not 150 ppb. From 1989 through a CRL of analytical method used by the Army for analysis of groundwater and tap water had to 25 ppb. 100 ppb. In 1993, following additional method development, the CRL was reduced concentration of The 1993 reporting limit of 25 ppb is 28 times less than the EPA health advisory of IMPA in 700 ppb. For this reason, the Army believes it has adequately characterized the extent from the Offpost Study Area in a manner sufficient to conclude that potential health effects IMPA are minimal.
2190S 402010 - CR-02 0808110895 19 more sensitive methods for the identifica- The Army his vigorously pursued the development of unaware of a standard EPA method tion of IMPA in RMA groundwater. The Army is currently ppb. capable of attaining a reliable reporting limit near 6 and will be providing additional The Army has received the State's evaluation of IMPA toxicity comments. i. Point of Compliance upgradient of O'Brian The Proposed Plan relies on intercept systems located immediately The Preamble to the Canal and some distance from the RMA boundary as the remedy. and TBCs pertaining to Proposed NCP provides that 'EPA's policy is to attain ARARs potential exposure 53- Fed. contaminant levels ...so as to ensure protection at all points of states that "remediationlevels Reg. 51440 (Emphasis added). The NCP, furthermore, clearly EPA acknowledges. should generally be attained throughout the contaminated plume.' be protective in some circumstances. however. that an alternative point of compliance may also has not demonstrated that it will See NCP C.F.R. §300.430(f)(5)(iii)(A) (1991). The Army nor has it made the achieve protectiveness and ARAR compliance throughout the plume, Therefore, the Proposed Plan requi.site findings to support an alternative point of compliance. to the NCP. The State is in violation of the groundwaterpolicy set forth in the preamble the Army can demonstrate contends that ARARs must be met throughout the plume unless technical impracticability or justify an alternative point of compliance.
Response within the contaminated plume, The Army intends to achieve the remediation goals at all points Army in support of the consistent with the NCP. The groundwater modeling conducted by the of remediation goals remedial alternatives evaluation in the Offpost EA/FS report used attainment alternatives. This as a primary criterion in assessing time to cleanup for the various remedial VI, Section 3.2 of the information is presented in summary form in the Proposed Plan and Volume of concern to the State EA/FS and in detail in Volume VII, Appendix E of the EA/FS. The area Containment System appears to be the portion of the plume that lies between the North Boundary The NBCS has been '(NBCS) and the Offpost Groundwater Intercept and Treatment System. at the RMA boundary to demonstrated to be effective in reducing the contaminant concentrations and Treatment meet remediation goals. The purpose of the Offpost Groundwater Intercept past the RMA boundary System is to extract and treat that portion of the plume that has migrated monitoring and that contains contaminants exceeding the remediation goals. The groundwater necessary to evaluate program implemented as part of the selected remedy will provide the dam to the attainment of treatment goals within the plume and to assess and design modifications treatment system, if necessary.
Comment No. 3 - Land Use
a. Classification of Land Use the predom- Zones 3 and 4 are currently zoned as agriculturallruralresidential. This was has inant use until Shell Oil Company purchased the land in 1991. The Army, however, this designated the land use for these zones as urban residential. The Army justifies
21905 402010 - CR-02 0808110895 20 planning documents, the expected classificationon two grounds. According to Adams County to the Army, is the fact that the future use is presumed to be urban. The other basis, according which allegedly will not sell majority of this land is presently owned by Shell Oil Company future use is urban residential,the that land except for commercial use. By assuming that the meats, milk, and eggs from the baseline Army has eliminated the consumption of homegrown remediation. The NCP risk assessment, thereby reducing the calculated risk and avoiding must be considered in the provides that both current and reasonable potential exposures The Army has eliminated the baseline risk assessment. 40 C.F.R. §300.430(d)(4) (1991). current land use, agricultural,in its evaluation. measure, or final response Land use controls should be considered as an interim response should not be considered in action where a more aggressive remedy is impracticable.but Directive 9355.0-30, dated conducting a cumulative site baseline risk assessment. OSWER with this guidance or NCP April 22. 1991 at page 4. The Proposed Plan does not comply no provisions to ensure that preamble language to the same effect; furthermore, it contains future. The State therefore agriculturallruralresidential uses are not allowed to occur in the residentialscenario, which more maintains that the risk assessment should include the rural accurately reflects current land use.
Resr)onse assessment are highly conservative. The future land use scenarios wsed by the Army in the risk 2, and 6 includes all pathways For example, the rural residential sc,!nario used in zones 1, of the total population is not exposed contributing substantially to potential risk, even though most Shell Oil Company to the agricultural exposure pathways described in the risk assessment. the Offpost Groundwater purchased the land in zones 3 and 4 for Army use in constructing therefore, the current zoning intercept and Treatment System. It is not presently occupied; of the realignment and designation as rural residential is not applicable. Given the probability will likely be commercial/ widening of 96th Avenue, future development along 96th Avenue documents, the Army selected an industrial or urban residential. Based on local agency planning (e.g., urban residential land use for the risk evaluation as this would result in more conservative higher) estimated risks than the likely co m mercial/ industrial land use. as a type of "land use The Army disagrees with the interpi-emtion of land use designations controls." The referenced OSWER Directive, on page 4 states: that the Whe cumulative site baseline risk assessment should include all media combine and reasonable maximum exposure scenario indicates are appropriate to for risk should not assume that institutional controls or fences will account reduction.
as, nor was it intended to The future land use designation of urban residential was not presented these properties by Shell Oil be interpreted as, an institutional control. Following the purchase of currently reside in Company, the current land use is vacant, not rural residential, as no individuals exposure these zones. The land use designation is made only to assess the types of potential Plan, which pathways. These designations are made in accordance with the National Contingency use. The Army states that the baseline risk assessment must look at a reasonable future land In accordance with believes that urban residential is a reasonable future land use designation.
21905 402010 - CR-02 0808110895 21 key factors in determining potential future Risk Assessment Guidance for Superfund, one of the The land use designations and plans land use is an evaluation of planning and zoning documents. not by EPA or the Army. Evaluation were established by the appropriate jurisdictional agencies, officials, examination of future land of current zoning regulations, discussions with local planning were used to establish land use use master plans for the city and county, and visual surveys zoning, planning maps, and planning scenarios. These designations are supported by established documents. b. Institutional Controls study area. Because risks Zones 2. 3, and 4 are the most contaminated zones in the Offpost in these zones, either from soil and groundwater contamination exceed acceptable levels to comply with CERCLA's remediazion or institutional controls are necessary in order responsible party not to sell the prescriptionthat remedies be protective. A mere promise by a and therefore does not ensure property until the remedy is complete would not be enforceable during the remediation protectiveness. Institutionalcontrols could be used toprevent exposure the construction of any period. For example, restrictions may need to be imposed to prevent aquifers. The Slate wells for the purpose of supplying drinking water from contaminated located "closer than 100 feet Engineer, for instance, has the authority to deny well permits from the source of contaminants...' 2 CCR -2. Rule 10.2.1 (1988). and deed restrictions as a The NCP specifically encourages the use of institutional controls long-term management to supplement to 'engineering conirolsas appropriatefor short-and 40 C.F.R. prevent or limit exposure to hazardous substances, pollutants, or contaminants." institutionalcontrols are not §300.430 (a)(1)(iii)(D). This section emphasizes. however, that treatment andlor containment appropriateas a substitute for active response measures such as of source material. and remediation of groundwaters. Id. to comply with the Thus. the State continues to urge that aggressive cleanup be undertaken that such prescriptionsof section 121 of CERCLA. as well as the NCP. To the extent in the interim, remedies are impracticableor do not ensure protection of human health remedy. Otherwise, however, institutional controls must be adopted to supplement the selected the Proposed Plan will not meet the NCP's threshold criterion of protectiveness.
Response Appendix B of the Institutional controls have been added as a component of the selected remedy. applicability. ROD provides an evaluation of the institutional controls available and their
(ARARS) Comment No. 4 - Applicable. Relevant and Anpronriate Reouirements Groundwater The State of Colorado has consistently identified the Colorado Basic Standardsfor and Methodol- (CBSG). 5 C.C.R. 1002-8, Section 3.11.0 cL =.. and the Colorado Basic Standards were ogies for Surface Water, (CBSM). 5 C.C.R. 3.1.0 cL =. as ARARs. These standards has previously identified in a timely manner. as is required by the NCP. Although the Army recognized the CBSG as ARARs at interim response actions at the Rocky Mountain Arsenal (RMA), CBSM as ARARs for (See footnote 2. in fra. the Army has failed to acknowledge the CBSG or the
21905 402010 - CR-02 0808110895 22 AssessmenilFeasibility the offpost operable unit at RMA according to the offpost Endangerment Study (EAIFS).' several that in order to be recognized as ARARs, state standards must fulfill The NCP provides comparable federal must be promulgated; they must be more stringent than the requirements: they NCP, 40 C.F.R. they must be either "applicable"or 'relevant and appropriate". standards;and is clear that these Applying these criteriato the CBSG and the CBSM, it §300.400(g)(4) (1991). to the six criteriaset are ARARs. and that unless they are explicitly waived according standards the basis for the cleanup of the forth in §121(d)(4) of CERCLA. these regulations should form offpost operable unit at the Rocky Mountain Arsenal.
Resvonse meet the applicable or relevant and The Army has recognized all state laws and regulations that Environmental Response, appropriate requirement (ARAR) criteria under the Comprehensive extensive discussion with all the Compensation, and Liability Act (CERCLA) and the NCP. After for Groundwater (CBSGs) do parties, the Army has concluded that the Colorado Basic Standards and ambiguous language. not meet the ARARs criteria because of inconsistent application water standards and are ARARS for the Offpost Operable Unit are based on federal drinking for the offpost and boundary Protective of human health. In most cases, the treatment goals treatment systems exceed the drinking water standards. at a site. However, only those CERCLA expressly provides that state standards can be ARARs be considered. In addition, the standards that are more stringent than federal requirements may be of general applicability and state standards must be promulgated (i.e., the requirement must in a timely manner by the legally enforceable). Finally, the requirements must be identified particular state (40 Code of Federal Regulations [CFR] Section 300.400[g][4]). Colorado Revised promulgated pursuant to the Colorado Water Quality Control Act, Regulations (5 Code of Colorado (CRS) Sections 25-8- 101, et seq., establish standards for groundwater Statutes is that Tables I Regulations [CCRI 1002-8, Section 3.11.0). A key aspect of the regulation 3.11.7[A]), but apply through 4 standards are not automatically applicable to groundwater (Section only if the aquifer has been classified in accordance with Section 3.11.4.
near the Arsenal The Army states in the EAIFS that the CBSG are not ARARs because the water apply to the has not been classified. The Army ignores the fact that the Table Value Standards Value Standards to all aquifer near the Arsenal pursuant to an interim rule which applies the Table dismisses the statewide unclassified aquifers. See. CBSG. 5 C.C.R. 1002-8. §3.12.5 (1). The Army ARARs because interim organic standards by stating. without further explanation, that they are not the State how these they are ambiguous and inconsistently applied. The Army has not indicated to also states that standards are ambiguous. or given examples of inconsistent application. The Army This analysis the CBSM are not ARARs because the remedy does not discharge to surface water. ARARs: fails to recognize that the CBSM are chemical -specific ARARs as well as action-specific human health they are therefore used to determine whether remedial actions are necessary to protect State and the environmeni from unacceptable risks due to exposures to concentrations exceeding standards. Such an evaluation should be conducted for offpost surface water bodies.
21905 402010 - CR-02 0808110895 23 Control Commission Most aquifers in the state are unclassified. Consequently, the Water Quality 3.12.5) for five specified (Commission) promulgated the interim narrative standard (Section to aquifer classification. Each of the aquifer systems to avoid degradation of water quality prior I through 4 or the ambient quality as of five identified aquifers must meet the standards in Tables are classified and numerical standards October 30, 199 1, if it was less restrictive, until the aquifers are adopted. standards that are applied different- The Commission promulgated a second group of groundwater standards (Section 3.11.5[CI) include ly than the standards in Tables I through 4. These statewide standards for organic pollutants water quality standards for radioactive materials and interim from the standards in Tables I through (Table A), including chloroform. Table A standards differ applicable to all state groundwater 4 in an important way: Table A standards are automatically application of Table A (Section 3.11.7[A]). The Commission recognized that the automatic impracticable results at standards can lead to unnecessarily overprotective and technically for remediation activities at CERCLA contaminated sites and added exceptions to the regulation and underground storage tank sites, Resource Conservation and Recovery Act (RCRA) sites, states the following: (UST) sites. The CERCLA exception, Section 3.11.5(C)(5Xa), agency respon- Nothing in this regulation shall be interpreted to preclude..4a)n Response, Com- sible for implementation of the Comprehensive Environmental amended, pensation and Liability Act (CERCLA), 42 U.S.C. 9601, et seq., as are more or less from selecting a remedial action and a point of compliance that numerical stringent than would be achieved by compliance with the statewide standards standards established in this subsection, or alternative site specific a variation is adopted by the Commission. when a determination is made that such authorized pursuant to the applicable provisions of CERCLA.
actions under RCRA Sections 3.11.5(C)(5)(b) and (c) provide similar exceptions for corrective and Subtitle I (UST sites), Subtitle C (hazardous waste treatment, storage, and disposal facilities) respectively.
intended not to impose the Section 3.11.5(C)(5) is internally consistent only if the Commission According to the regulations, the interim organic standards in Table A as cleanup standards. RCRA, interim organic standards automatically apply on a statewide basis, except at CERCLA, regarding groundwater quality and UST sites where 'certain federal regulatory determinations (Section 3.1 1.10[BI). In promulgating the would not be superseded by the Commission's standards* agencies are more familiar Table A exceptions, the Commission recognized that implementing the appropriate cleanup with site-specific conditions and are in a better position to determine of the Table A standards, the standards. By not imposing unnecessarily stringent application regulatory programs, which may Commission sought to show 'explicit deference to certain federal apply different standards' (Section 3.1 1.10[HI).
not ARARs for two reasons. The Army concludes that the CBSG interim organic standards are actions authorized First, the CERCLA exception in Section 3.l1.5(CX5Xa) applies to remedial by compliance with the under CERCLA that are more or less stringent than would be achieved standard and accompanying statewide standards. As a result, the overall effect of the statewide a federal requirement. exceptions is a state regulation that is only sometimes more stringent than
21905 402010 - CR-02 080811089S 24 at all times as potential ARARs. CERCLA only considers state standards that are stricter are not ARARs at Superfund sites. Therefore, by definition, the interim organic standards ARARs because they are not generally Second, the CBSG interim organic standards cannot be for state requirements to be applicable or legally enforceable. A requirement in CERCLA means they must be generally applica- ARARs is that they must be promulgated standards, which do not meet this test when ble and legally enforceable. Clearly, the interim organic standards standards are applicable throughout applied at CERCLA sites. By definition, the interim organic instances, the relevance of the the state, except at CERCLA, RCRA, and UST sites. In those how the standard could be standards is determined by the remedial sites. It is hard to understand ensuring that the standards legally enforceable when the Commission added language specifically may or may not be met at CERCLA sites. a. Promulgated by State legislative bodies "Promulgated"state requirements include those which are enacted rulemaking proceedings, as is or adopted as regulationsby State agencies pursuant to formal standards must also be the case with the CBSM and the CBSG. According to the NCP, the (1991). generally applicable. and legally enforceable. 40 C.F.R. § 300.400(g)(4)
1. Legally Enforceable: to the proposed NCP State standards are "legally ?nforceable'. according to the preamble enforceable under if they "contain either specific enforcement provisions, or are otherwise accordance with proce- state law." 53 Fed. Reg. 51437-38. They must also be-issued in dural rules. 40 C.F.R. §§300.400(g)(4) and (5) (1991). it clear that the The enabling statute for the Water Quality Control Commission makes CBSM, are regulations promulgated by the Commission. including the CBSG and the enforceable standards to be applied throughout the State of Colorado. Lee 25-8-102,25-8- are 204(4) C.R.S.. (1989 Repl. Vol.). The regulations promulgated by the Commission "implementing used not only by the Division of Water Quality Control, but also by the other the Oil and agencies' such as the Office of Mined Land Reclamation, the State Engineer, as well as by Gas Conservation Commission. agencies responsible for RCRA enforcement, other state agencies. 23-S-202. C.R.S.. (1992 Supp.).
These regulations are formally promulgated pursuant to an "on the record" administrative of rulemaking proceeding. which includes notice and comment. according to the provisions the rules of the Water Quality Control Commission and the Colorado Administrative Procedure Act. 24-4-101 er, sea.. C.R.S..(1988 Repl. Vol.. and 1992 Supp.). S§e renerallv. CERCLA Compliance with other Laws Manual. Part 11. pages 7-2 through 7-4.
Resoonse
See response to Comment No. 4, part 1, given above.
21905 402010 - CR-02 0808110895 25 2. Generally Applicable: applicable"means The preamble to the proposed NCP explains that the term Ogenerally described in the that potential state ARARs must be applicable to all remedial situations and the CBSG requirement,not just CERCLA sites. 53 Fed. Reg. 51437-38. The CBSM actions, as used as the appropriatecleanup standards in state cleanup and enforcement are therefore well as at other CERCLA sites within the State of Colorado. The regulations fulfill the 'general applicability"requirement set out in the NCP!
Response Court for Colomdo held The state claims in its November 20, 1992, letter that the US. District v. Idarado Mining Co. that the CBSG are applicable requirements under CERCLA (Colorado not hold that the interim 707 F. Supp. 1227 [D. Colo. 1989]). In its proper context, the case does State of Colorado organic standards are ARARs. First, the case merely points out that the the case did not identified the CBSG as an ARAR in its Record of Decision (ROD). Second, Section 3.11.5(C)(5) address the Table A interim organic standards or the CERCLA exception in Therefore, the Idarado because those provisions were promulgated A_fg_r the case was decided. to the Offpost OU. case has very little relevance to the zpplication of the Table A standards b. More Stringent CBSG and the A comparison of the numeric chemical- specific standardscontained in the instances CBSM, as well as the narrative standards in both regulations, reveals that in many The the Colorado Basic Standards cre morestringent than the comparable federal standards. contam- State has iimely identified the more stringent state standards applicable to specific inants at the Rocky Mountain Arsenal that are to be recognized and applied as ARARS!
Resvonse for many The Army disagrees with the State's contention that CBSG standards are more stringent 1,2- of the chemicals listed by the State. These include aldrin. carbon tetrachloride, chloroform,
There are numerous state compliance actions as well as CERCLA sites in which the CBSG have been used as a cleanup standard. &C. letter from Paul R. Tourangeau (AGO), to Elizabeth T. Wald (EPA). daied November 20. 1992. for some of these examples. This letter is hereby incorporated into these comments by reference. EPA recentlY affirmed that the CBSG are ARARs at the to CERCLA Wastewater Interim Response Action at the A rsenal. ýa, Comments on Shell's Request Modify CERCLA Wastewater IRA ARARs. atiached to letter from Connally Mears (EPA) to Charles F. Scharmann (Army). also Incorporated by reference. The State does not understand how EPA can ignore the ARARs for the off post operable unit while simultaneously recognizing these standards as ARARs at another action at the same site.
' The chemicals for which the State standards are more stringent include: aldrin, carbon tetra- chloride, chloroform. 1.2-Dichloroeihane.dieldrin and manganese.
2190S 402010 - CR-02 0808110895 26 standards are the dichloroethane, and dieldrin. For these compounds, the Army's cleanup respective certified reporting limits (CRLs).
C. Applicable Requirements
According to the NCP, 'Applicable Requirements" environ- means those cleanup standards, standards of control, or other substantive federal mental protection requirements, criteria or limitations promulgated under environmental or state environmental or facility siting law (sic) that specifically or address a hazardous substance, pollutant, contaminant, remedial action, location, other circumstance at a CERCLA size.
40 C.F.R. §300.5 and 300.400(g)(1)(1991). further In determining if a requirement is applicable, the Proposed NCP offers some guidance. Several jurisdictionalprerequisites must be considered:
a. Who. as specified by thestatute or regulation, is subject to its authority;
b. The activities the statute or regulationrequires. directs or prohibits.
c. The substances or places within the authority of the requirement; and
d. The time period for which the statute is in effect.
53 Fed. Reg. 31436 of The CBSG and CBSM are state standards which specifically address the majority for those chemicals of concern at the Rocky Mountain Arsenal. The regulations set standards of concern chernica./s on groundwater and surface water. the former being the primary medium anti- in the of1post operable unit. These standards have been applied as both cleanup and over the de1rraJrjtonstandards. and must be complied with by any person exercisIng control are reiewant i b pe of water. The regulations are currently in effect. The CBSG and CBSM for the there"i-e arritcableto the Arsenal. and must be adopted as the appropriatestandards rerne.Iial "tion
The rreapnIl-le to the Proposed NCP also makes it clear that there is no discretion in the 3electsoov of ARARS when a standard is applicable. 'Applicable requirements are identified bi a largris ohjective comparison to the circumstances at the site; if there is a one-to-one correslvnJence between the requirement and the circumstances at the site, then the requirement is applicat-le.' 53 Fed. Reg. 51436-37.
Response
The Army has reviewed the regulator), language of the CERCLA exception in Section A careful 3.11.5(C)(5)(a) and the accompanying Basis and Purpose, published by the Commission.
21905 402010 - CR-02 0808110895 27 the CBSG interim reading of both sources indicates that the Commission did not promulgate utilized by remedial organic standards as mandatory cleanup standards, but rather as levels to be authorities when appropriate. the Army) from The regulation states that it does not preclude an implementing agency (e.g., OU) that is less stringent selecting a remedial action (e.g., the selected remedy for the Offpost determination must be made than would be achieved by the interim organic standard. Further, a important points can be that the selected remedial action is authorized by CERCLA. Several drawn from the regulation. merely preemption First, the remedial site exceptions in Section 3.11.5(CX5) are more than states the statements. In its November 20, 1992, letter, the State suggests that the provision the State that the obvious, that the CBSG does not preempt CERCLA. The Army agrees with is only the starting point Commission did not intend for the CBSG to preempt CERCLA. But that of the regulatory for interpreting the regulation. The state appears to have ignored the remainder language in Section 3.11.5(C)(5)(a). at remedial sites. Second, compliance with the CBSG interim organic standards is not required standards. The regulation does not state that the implementing agency must use the statewide choosing to use the Instead, the regulation is written not to preclude an implementing agency from The Commission is statewide standards. This is a critical distinction not addressed by the State. sites, but emphasizing that the interim organic standards are not mandatory at certain remedial is that the can be used if the implementing agency elects to use them. The logical conclusion UST sites, where interim organic standards do not apply automatically to CERCLA, RCRA, and their use is ultimately determined by the remedial authority at the site. the CBSG Third, the CERCLA waiver provision is not the sole mechanism for not implementing not a interim organic standards. The regulation explicitly states that the remedial action, chemical -specific standard, selected by the implementing agency can be more or less stringent than a remedial action that achieves the CBSG interim organic standard. By referring to the authority of the implementing agency to select the remedy, the Commission is obviously giving the exception a broader application than just the statutory waivers in CERCLA. Rather, the Commission is leaving the decision to apply the Table A standards to the agency authorized under CERCLA to select the remedial action. This logically leads to the conclusion that the interim organic standards are not cleanup standards, but merely guidance levels that may or may not be met at CERCLA, RCRA, and UST sites where statutory standards protective of the environment are already incorporated into the remedial process.
Section 3.11.5(C)(5) is internally consistent only if the Commission intended not to impose the interim organic standards in Table A as cleanup standards. According to the regulations, the interim organic standards automatically apply on a statewide basis, except at CERCLA, RCRA, and UST sites where "certain federal regulatory determinations regarding groundwater quality would not be superseded by the Commissions's smndards* (Section 3.1 1.10[B]). In promulgating the Table A exceptions, the Commission recognized that implementing agencies are more familiar with site-specific conditions and are in a better position to determine the appropriate cleanup standards. By not imposing unnecessarily stringent application of the Table A standards, the Commission sought to show "explicit deference to certain federal regulatory programs, which may apply different standards' (Section 3.11. 1OJHJ).
21905 402010 - CR-02 0909110895 28 standards are not ARARS for two reasons. The Army concludes that the CBSG interim organic applies to remedial actions authorized First, the CERCLA exception in Section 3.11.5(C)(5)(a) would be achieved by compliance with the under CERCLA that are more or less stringent than of the statewide standard and accompanying statewide standards. As a result, the overall effect more stringent than a federal requirement. exceptions is a state regulation that is only sometimes stricter at all times as potential ARARs. CERCLA only considers state standards that are are not ARARs at Superfund sites. Therefore, by definition, the interim organic standards be ARARs because they are not generally Second, the CBSG interim organic standards cannot CERCLA for state requirements to be applicable or legally enforceable. A requirement in which means they must be generally applica- ARARs is that they must be promulgated standards, organic standards do not meet this test when ble and legally enforceable. Clearly, the interim organic standards are applicable throughout applied at CERCLA sites. By definition, the interim sites. In those instances, the relevance of the the state, except at CERCLA, RCRA, and UST to understand how the standard could be standards is determined by the remedial sites. It is hard specifically ensuring that the standards legally enforceable, when the Commission added language may or may not be met at CERCLA sites.
d. Relevant and Appropriate applicable to the Rocky Mountain The State contends that the CBSG and the CBSM are a minimum, 'relevant and appropri- Arsenal offpost operable unit. Regardless. they are. at ate.' The NCP defines *relevant and appropriate' as substantive requirements, those cleanup standards. standards of control. and other or state environ- criteria. or limitations promulgated under federal environmental to a hazardous substance, menial or facility sizing laws that. while not 'applicable" circumstance at a pollutant. confaminani. remedial action. location. or other similar to those encoun- CERCLA site. address problems or situations sufficiently particularsite. tered at the CERCLA site that their use is wellsuited to the
40 C.F.R. §300.5(1991). ARARs because they do not It has been suggested that the CBSG and the CBS.4f are not are being used by the specifically state that they are cleanup standards. These standards agencies as cleanup Water Quality Control Division. as *ell as by the other implementing are "relevant and appropri- standards.thereby leading to the conclusion that the regulations aze'.'
standards. This It has also been suggested that the regulations are "merely' anti-degradazion Both the NCP and EPA guidance label. however, does not mean that the regulations are not ARARs. ARARS. Se Pre mble make it very clear that anti- degradation statutes ace frequently 11, pages 7-28, and 7-30. Reg. 8746. and CERCLA Compliance with Other Laws Manual: Part
21905 402010 - CR-02 0808110895 29 relevance and appropriate- The NCP includes eight factors to be considered in determining ness: action; i. The purpose of the requirement and the purpose of the CERCLA medium contaminated or ii. The medium regulated or affected by the requirement and the affected at the CERCLA site; action contemplated at the iii. The substances regulated by the requirement and the remedial CERCLA site; action contem- iv. The actions or activities regulated by the requirement and the remedial plated by the CERCLA action: availability at the v. Any variances, waivers, or exemption of the requirement and their CERCLA site: or CERCLA vi. The type of place regulated and the type of place affected by the release action: size of structure or vii. The type and size of structure or facility regulated and the type and facility affected by the release or contemplated by the CERCLA action; requirement and the viii. Any consideration of use or potential use of affected resources in the use or potential use of the affected resource at the CERCLA site.
40 C.F.R. J300.400(g) (2) (1991). CBSM An examination of these eight factors leads to the conclusion that the CBSG and the Place, the use are relevant and appropriate. The media. the substances, the actions, the type of are and potential use of the affected resources which are covered by the CBSG and the CBSM idenucal to those at the Rocky Mountain Arsenal. These regulations are therefore "relevant and arrropriate.' They Thus. the CBSG and the CBSM fulfill all the prerequisites to be ARARs under the NCP. they are are promuljrxed state standards.both generally applicable and legally enforceable; and more stringent than the relevant federal standards:and they are applicable or relevant as appro,rriaje It is therefore contrary to CERCLA and the NCP to fail to identify them AR AR s anJ to appl), the less stringent federal standards as the basis for cleanup at RMA's of 1pos: operaNe unit.'
The Army has previousl'y raised the question of whether 5 C.C.R.1002-8. §3.11.5 (C)(5)(a), CBSG constitutes a 'CERCLA exemption' from the provisions of the CBSG. That section of the in the merely states the obvious. that when CERCLA dictates a standard other than that prescribed (AGO), regulations. CERCLA is not preempted by the CBSG. $ec, Leiter from Paul R. Tourangeau to Eli:abeth T. Wald (EPA). dated November 20. 1992. responding to a request for clarificationof the general applicability and legal enforceability of the CBSG.
21905 402010 - CR-02 0808110895 30 Responie-
See response to comment to Comment No. 4 Part c given above. e. Secondary Maximum Contaminant Levels MCLs as ARARs. The The Army in its Proposed Plan has failed to acknowledge secondary Act, 42 U.S.CJ00g-I(c) secondary MCLs, promulgated pursuant to the Safe Drinking Water odor or appearanceof such (1992), address a contaminant '(A) which adversely affect the served by the public water and consequently may cause a substantialnumber of the persons adversely affect the public water supply to discontinue its use, or (B) which may otherwise not federally enforce- welfare." 42 U.S.C. 300(f)(2) (1992). The secondary MCLs, while the States.' 40 C.F.R. 143.3 able. are nevertheless relevant and appropriateas 'guidelines for drinking water (1992). The State of Colorado. moreover, has promulgated secondary Standards for Ground- standards. and incorporated those standards in the Colorado Basic in Colorado's regulations water. 5 C.C.R. 1002-8. Table 2. The numeric standards contained that these standards are are the same as in the federal regulations. The State maintains Plan. Specifically, chloride ARARs, and must be addressed by the Army in the Proposed of 250 ppm during the samples since June 1992 show exceedances of the secondary standard illustrate a history of 3rd and 4th quarters of 1992. Likewise. fluoride and manganese data exceedances of their secondary MCLs of 2 and 500 ppm, respectively.
Response Act, Colorado Revised Regulations promulgated pursuant to the Colorado Water Quality Control groundwater (5 Code of Colorado Statutes (CRS) Sections 25-8-101, et seq., establish standards for a system for classifying Regulations [CCR] 1002-8, Section 3.11.0). These regulations create and potential beneficial uses groundwater and adopting water quality standards to protect existing on the basis of use (Tables I through 4). Groundwater is categorized into five classifications to the classified aquifer (Section 3.11.4[A]). Standards specified in the regulation are then applied standards, agricul- (Tables I through 4; e.g., human health standards, secondary drinking water A key aspect of the tural standards, and total dissolved solids [TDSI water quality standards). to groundwater regulation is that Tables I through 4 standards are not automatically applicable accordance with (Section 3.11.7[Al), but apply only if the aquifer has been classified in State, Tables 1 through 4 Section 3.11.4. Since the offpost aquifers have not been classified by the are not automatically applicable. narrative The Water Quality Control Commission (Commission) also promulgated the interim degradation of water standard (Section 3.12.5) for five specified aquifer systems in order to avoid meet the Tables I quality prior to aquifer classification. Each of the five identified aquifers must restrictive, until through 4 standards or the ambient quality as of October 30, 1991, if it was less Study Area the aquifers are classified and numerical standards are adopted. However, the Off post through 4 does not fall within any of the five specif led aquifer systems; consequently, Tables I (including the secondary drinking water standards in Table 2) do not apply.
21905 402010 - CR-02 0809110895 31 Comment No. 5 - Surface Water is Planned for surface The Army's Offpost Proposed Plan indicates that no active remediation water offpost; the Army maintains that surface water willbe cleaned up as a result of groundwater this will take: nor is any remediation. The Army has not provided any estimation of how long water quality. future sampling planned to verify this expected improvement of surface of concern suchas According to the surface water data available for First Creek, contaminants standards. As the Army chlordane, dieldrin, endrin and DDT exceed the state aquatic life chronic Study Final Report, page III- readily admits in the Offpost Endangerment AssessmentIFeasibility for an adverse effect to 5-30. "chlordane,dieldrin. fluoride and DDT appear to present a potential in surface water aquatic life in First Creek, based on a comparison of exposure point concentrations these contaminants to TRV's (chronic AWQC values) for aquatic life.' The State believes that should be addressed in the Offpost Proposed Plan. 'The Army has not The State agrees with the position that EPA took on this issue a year ago. of the contaminated provided an objective evaluation of possible alternatives for the remediation would remediate the surface water other than concluding that the remediation of the groundwater not identified, even surface water. The timeframe and costs for reinediationof surface water are these elements reside in within the context of the remediation of the groundwater. since a portion of not yet been the remediation costs and time frame for the Onpost OU. for which the FS has dated May 6. 1992). prepared." (See. letter from Connally Mears, EPA, to Kevin Blose, U.S. Army, offpost mainly The Arm), has justified its failure to examine alternatives for surface water cleanup will be by stating that because First Creek is a gaining stream in the offpost area, the Creek System. eventually cleaned up as the groundwater is flushed by the North Boundary Containment Study, In the Army's response to a state comment (Offpost Endangerment AssessmentlFeasibility First Creek Proposed Final Report. Vol. 8. pg.78) the Army states: 'Groundwater interaction with the surface water is known to occur in First Creek between the northern RMA boundary and with First confluence of First Creek with O'Brian Canal. This interaction of offpost groundwater Creek surface water is quite complex. Seasonal fluctuations in the water table and seasonal that vary fluctuations in First Creek flow rate result in gaining and losing stretches of First Creek, temporally. Further.slight variations in the water table elevation and in the First Creek stream elevation along the length of First Creek result in spacial variations in stretches identified as gaining or losing independent of the season.' The Army also states on pg. 76 of the same volume: -The secondary source of surface water in First Creek offpost is watershed runoff." The State agrees that remediation of groundwater should have a positive net effect on surface water quality offpost. Given the complexity of groundwater/ surface water interaction offpost and the potential contribution of contamination resulting from overland flow during storm events, however, the State remains concerned with the lack of consideration given to the surface water medium by the Army. The State believes the Army should evaluate remedial alternatives in order to meet state surface water qualit'y standards in First Creek. In addition. we urge the Army to commit to future sampling to ensure these standards are achieved.
Rest)onse
Given that the following three factors point to continuing beneficial impacts to offpost water quality, the Army is committing to an ongoing surface-water monitoring program to track the cleanup of offpost surface water (1) remediation of groundwater should have a beneficial effect
21905 402010 - CR-02 0908110895 32 are lower during storm event on offpost surface-water quality, (2) contaminant concentrations Annual Report for 1989 [R.L. runoff periods (Surface Water Comprehensive Monitoring Program committed to closing the onpost Stollar & Associates, and others, 1990]), and (3) the Army has in the First Creek sewage treatment plant, thus eliminating a possible source of contaminants surface water drainage. will be contained in a report to The components of the offpost surface-water monitoring program the Army commitment to be completed following completion of the ROD. The ROD contains area as a component of both surface-water and groundwater monitoring programs in the offpost the selected remedy.
21905 402010 - CR-02 0808110895 33 Appendix A-4
RESPONSES TO REGION Vill U.S. ENVIRONMENTAL PROTECTION AGENCY COMMENTS U.S. DEPARTMENT OF THE ARMY AGENCY RESPONSES TO REGION V]aI U.S. ENVIRONMENTAL PROTECTION COMMENTS REGARDING THE ROCKY MOUNTAIN ARSENAL OFFPOST PROPOSED PLAN JUNE 17, 1993
GENERAL COMMENTS
Comment No. I - Irondale Boundary Control System (IBCS) also be committed by Along with the north and northwest boundary control system. the IBCS must in the Federal Facilities the Offpost Record of Decision (ROD) to continue to operate as required to be unintentional. Agreement (FFA). We understand this omission from the Proposed Plan
Resvonse included as a Continued operation of the Irondale Boundary Containment System has been (ROD). component of the selected remedy in the Offpost Record of Decision
Comment No. 2 - Continued Operation of Three Boundary Systems at Section 2.7 The Offpost ROD will have to select the Federal FacilitiesAgreement requirement systems must be required to (regarding ground water quality flowing offpost). The three boundary continue operation, as necessary to accomplish that obligation.
Response as part of the selected Continued operation of the three boundary containment systems is required remedy in the Offpost ROD.
Standards: Comment No. 3 - Acknowledzinst the State Ground Water Regulations as Legal Specific EPA considers the Colorado Basic Standards for Ground Water (CBSGs) to be Action EPA's use of ARARs (and has adopted them on other Superfund sites. as well as for RMA IRAs). the this regulation as an Action Specific ARAR is to require that cleanup activities do not degrade such ARARs as quality of existing ground wajer during response activities. This is consistent with selling Section 7020 of RCRA. which are established to improve ground water quality without specific specific standards. EPA also believes that the CBSGs should be used to establish chemical for remediaiton levels. The clear language of the regulation allows for the establishment, set forth in the CERCLA. RCRA. and UST siies, of cleanup levels which differ from the standards CERCLA Tables. therefore. those tables do not provide a chemical specific numerical standard for actions. Nevertheless. chemical specific cleanup levels should be derived using the site specific cleanup. exemption language and the procedure provided bi, the CBSGs to set protective levels for
Remonse and The Army has recognized all state laws and regulations that meet the applicable or relevant appropriate requirement (ARAR) criteria under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and the National Oil and Hazardous Substances Army has Pollution Contingency Plan (NCP). After extensive discussion with all the parties, the ARARs concluded that the Colorado Basic Standards for Groundwater (CBSGs) do not meet the
21905 402010 - CR-01 0908110895 for the Offpost criteria because of inconsistent application and ambiguous language. ARARs protective of human health. Operable Unit are based on federal drinking water standards and are systems are more In most cases, the treatment goals for the offpost and boundary containment protective than the drinking water standards. only those expressly provides that state standards can be ARARs at a site. However, CERCLA In addition, the standards that are more stringent than federal requirements may be considered. applicability and state standards must be promulgated (i.e., the requirement must be of general manner by the legally enforceable). Finally, the requirements must be identified in a timely particular state (40 Code of Federal Regulations [CFR] Section 300.400[g][4]). Colorado Revised Regulations promulgated pursuant to the Colorado Water Quality Control Act, of Colorado Statutes (CRS) Sections 25-8-101, et seq., establish standards for groundwater (5 Code Tables I Regulations [CCR] 1002-8, Section 3.11.0). A key aspect of the regulation is that but apply through 4 standards are not automatically applicable to groundwater (Section 3.11.7[A]), only if the aquifer has been classified in accordance with Section 3.11.4. Commission Most aquifers in the state are unclassified. Consequently, the Water Quality Control specified (Commission) promulgated the interim narrative standard (Section 3.12.5) for five Each of the aquifer systems to avoid degradation of water quality prior to aquifer classification. ambient quality as of five identified aquifers must meet the standards in Tables I through 4 or the standards October 30, 199 1. if it was less re3trictive, until the aquifers are classified and numerical are adopted. different- The Commission promulgated a second group of groundwater standards that are applied include ly than the standards in Tables I through 4. These statewide standards (Section 3.11.5[C]) water quality standards for radioactive materials and interim standards for organic pollutants in Tables I through (Table A). including chloroform. Table A standards differ from the standards 4 in an important way: Table A standards are automatically applicable to all state groundwater A (Section 3.11.71AI). The Commission recognized that the automatic application of Table standards can lead to unnecessarily overprotective and technically impracticable results at contaminated sites and added exceptions to the regulation for remediation activities at CERCLA sites, Resource Conservation and Recovery Act (RCRA) sites, and underground storage tank (UST) sites. The CERCLA exception, Section 3.11.5(C)(5Xa), states the following:
Nothing in this regulation shall be interpreted to preclude.-.[a]n agency responsible for implementation of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), 42 U.S.C. 9601. et seq., as amended, from selecting a remedial action and a point of compliance that are more or less stringent than would be achieved by compliance with the statewide numerical standards established in this subsection, or alternative site specific standards adopted by the Commission, when a determina- tion is made that such a variation is authorized pursuant to the applicable provisions of CERCLA.
Sections 3.11.5(C)(5Xb) and (c) provide similar exceptions for corrective actions under RCRA Subtitle C (hazardous waste treatment. storage. and disposal facilities) and Subtitle I (UST sites), respectively.
Section 3.11.5(CX5) is internally consistent only if the Commission intended not to impose the interim organic standards in Table A as cleanup standards. According to the regulations, the interim organic standards automatically apply on a statewide basis, except at CERCLA, RCRA,
21905 402010 - CR-01 OWSI10895 2 quality sites where "certain federal regulatory determinations regarding groundwater and UST promulgating the not be superseded by the Commission's standards' (Section 3.11. 1 O[B]). In would familiar exceptions, the Commission recognized that implementing agencies are more Table A cleanup with site-specific conditions and are in a better position to determine the appropriate A standards, the standards. By not imposing unnecessarily stringent application of the Table programs, which may Commission sought to show "explicit deference to certain federal regulatory apply different standards" (Section 3.11. 1O[H]). reasons. concludes that the CBSG interim organic standards are not ARARs for several The Army under exception in Section 3.1 I.S(C)(5)(a) applies to remedial actions authorized The CERCLA statewide that are more or less stringent than would be achieved by compliance with the CERCLA exceptions standards. As a result, the overall effect of the statewide standard and accompanying CERCLA a state regulation that is only sometimes more stringent than a federal requirement. is Therefore, by only considers state-standards that are stricter at all times as potential ARARs. definition, the interim organic standards are not ARARs at Superfund sites. are not generally Second, the CBSG interim organic standards cannot be ARARs because they to be applicable or legally enforceable. A requirement in CERCLA for state requirements is that they must be promulgated standards, which means they must be generally applica- ARARs test when and legally enforceable. Clearly, the interim organic standards do not meet this ble throughout applied at CERCLA sites. By definition, the interim organic standards are applicable the relevance of the the state, except at CERCLA, RCRA, and UST sites. In those instances, the standard could be standards is determined by the remedial sites. It is hard to understand how that the standards legally enforceable, when the Commission added language specifically ensuring may or may not be met at CERCLA fites.
Comment No. 4 - Institutional Controls
Use of Institutional Controls presently exists in the Offpost in the form of permitting and of development laws. etc. This concept is not limited to deed restrictions or prohibitions on use propert 'y. The Proposed Plan could have acknowledged that Institutional Controls will be consi- health and dered; however, the ROD should select them. as necessary. to ensure protection of human anytime on the environment. They can be refined in the design and remedial activity phases, or data review. vi. a an appropriateprocess (e.g.. a ROD Amendment or Explanation of Significant Difference (ESD)).
Response
Institutional controls have been included as a component of the selected remedy in the Offpost ROD.
Comment No. 5 - Co in the Deeper Acuifer must The Abandoned Well Closure IRA was expanJeJ to aJJress offpost wells, and such activities be required in the Offposi ROD. The partoei neeJ to discuss the criteriathat will be used to trigger such activities.
However. the Army's draft response to the State's concern does not specifically address the issue. Given Mai some twenty wells are currently identified and informalion exists on them, a more detailed response should be given. The Arm 'i acknowledges its current well closure plan but does not describe it: therefore. there is no information on closure to apply to the specific conditions of the wells. Since such information exists. it should be provided in that response.
21905 402010 - CR-01 0808110895 3 Response
Well closure activities have been included as a component of the selected remedy. Appendix C of the ROD provides the criteria for closure of abandoned wells.
Comment-No. 6 - Flexible Implementation of the Remedy
EPA's final concern is to ensure expeditious implementation of the flexibility for change in the Army's preferred alternative, in light of recent information received indicating that DIMP exists above health based levels north of (i.e. beyond) the Offpost IRA Intercept and Treatment System for the ground water plumes. Discussions have begun on the first step, which is to obtain additional sampling data to better characterizethe area beyond the current intercept location. EPA expects thai. to the maximum extent possible. such information will be used to evaluate potential modifica- tion of the current system, prior to the Offpost ROD. EPA, at this time, concurs with the Army's preferred remedy (pending evaluation of State and public concerns), due to its inherent flexibility. If information cannot be timely developed before the ROD, the option will still be available to later select and implement change. via an appropriateprocess (e.g., ROD amendment or ESD). The parties need to discuss this matter further.
Response
In the area north of the Offpost Groundwater Intercept and Treatment System, the Army intends to replace three groundwater monitoring wells and install three new groundwater monitoring wells. The Army has provided this information to the Organizations and State in a letter report with accompanying map showing proposed monitoring well locations. The purpose of the three new monitoring wells is to aid in assessing the extent of contamination downgradient of the Offpost Groundwater Intercept and Treatment System. Data collected from these wells and existing wells will be used to further define the extent of contamination greater than the remediation goals in this area and to evaluate whether modifications to the Offpost Groundwater Intercept and Treatment System are necessary.
Comment No. 7 - Exr)osure Pathway of Dermal Contact with Ground water
On page 3. Column 1. of the Proposed Plan. when discussing Exposure Pathways. the word 'Ground waier' was omated from the first bullet of the "Dermal' section. The omission of the word ground water is not consistent with the Dispute Resolution Agreements of May 5, 1992, which exclude only Zones 3 & 4 from using ground water for domestic purposes.
Response
The omission of "groundwater' was inadvertent. Dermal contact with groundwater was evaluated in the Endangerment Assessment.
21905 402010 - CR-01 0808110895 4 Appendix A-5
RESPONSES TO CITY AND COUNTY GOVERNMENT COMMENTS RESPONSES TO TRI-COUNTY HEALTH DEPARTMENT COMMENTS U.S. DEPARTMENT OF THE ARMY RESPONSES TO TRI-COUNTY HEALTH DEPARTMENT COMMENTS REGARDING THE ROCKY MOUNTAIN ARSENAL OFFPOST PROPOSED PLAN JUNE 21, 1993
Comment I - Preferred Alternative
We concur that Alternative N-4, Offpost Intercept and Treatment Systems, presents an appropriate treatment system to reduce shallow alluvial unconfined aquifer contamination. Since much of the excess risk in the offpost area is from the groundwater, limiting this exposure and pathway is of primary importance. Along with the operation of this system an aggressive tap monitoring well surveillance program should be maintained to evaluate success of this treatment system and to identify any other areas of concern. the Enhancement of N-4, such as is Proposed in N-5 to provide more aggressive treatment within same cost parameters should be evaluated with implementation reconsidered, if determined to be feasible and effective. We are concerned, however that more aggressive treatment within the same cost parameters should be evaluated with implementation reconsidered, if determined to be feasible and effective. We are concerned, however that more aggressive treatment may alter the groundwater flow such that it will be more difficult to predict the effectiveness of the remedy and the time required for completion. If such alternatives are reconsidered the Army should verify the reliability of the assumptions used in the model from which the cleanup time is calculated. Based on continued monitoring of domestic water supplies and assurance that exposure pathways for consumption of contaminated groundwater are not complete, the time required to implement the alternative becomes less critical particularly if it increases the complexity and uncertainty associated with implementation.
Tri-county also endorses the continued operation and expansion, as necessary, of the North Boundary, Northwest Boundary and the Irondale Groundwater intercept and treatment systems to prevent further offpost migration of the contaminated unconfined/alluvial groundwater.
Response I
The Army agrees that an evaluation of the potential need to enhance Alternative N-4 is appropri- ate. Collection and evaluation of site-specific operational data during the initial phases of operation of the Offpost Groundwater Intercept and Treatment System will be the basis for assessing the need for design modifications. Continued operation of the three existing boundary containment systems is a part of the selected alternative. A tap water and groundwater monitoring program is included as a component of the preferred alternative.
Comment 2 - DIMP
We are concerned about the repeated detection of high concentrations of DIMP in the well identified as TCHD Well 1178B, downgradient of the proposed intercept system described in N-4. Although there is historical evidence of a high concentration of DIMP in this well, this anomaly has not been adequately explained. We are particularly interested in whether further characterization of the problem with that well will impact the anticipated effectiveness of Alternative N-4 and what additional action will be taken to remediate the shallow alluvial unconfined aquifer in that area.
930423A.enc Resvonse 2
The Offpost Groundwater Intercept and Treatment System is located in areas of highest contami- nant concentrations. The Army is aware that concentrations of diisopropyl methylphosphonate (DIMP) greater than 600 parts per billion (ppb) have been reported north of the Offpost Intercept and Treatment System. In that regard, the offpost remedial action groundwater monitoring program will be coordinated with the three existing groundwater monitoring programs active in the Offpost Study Area. These three programs are (1) the Groundwater Monitoring Program, (2) the Interim Response Action A Monitoring Program, and (3) the private well monitoring -program. Additionally, in the area north of the Offpost Groundwater Intercept and Treatment System where DIMP has been reported to exceed 600 ppb, three monitoring wells will be replaced and three new monitoring wells will be installed. Replacement wells are being installed for wells originally in the monitoring network that were found to be damaged or destroyed. Two new monitoring wells will be installed downgradient of the First Creek Pathway and one new monitoring well will be installed downgradient of the Northern Pathway. The Army has provided information regarding the additional monitoring wells to the Organizations, State, and Tri-County Health Department in a letter report and accompanying map showing the locations of the proposed monitoring well locations. The purpose of the three new monitoring wells is to aid in assessing the extent of contamination downgradient of the Offpost Groundwater Intercept and Treatment System. Data collected from these wells and existing wells will be used to further define the extent of contamination greater than the remediation goals in this area and assist in determining whether modifications to the Offpost Groundwater Intercept and Treatment System are necessary.
Comment 3 - Risk Levels Used To Initiate Cleanup
We are aware of some discussion concerning the risk level that should initiate the need for cleanup action. If I x 10-4 were used to trigger cleanup what additional offpost areas would require attention? It is our opinion that the National Contingency Plan guidelines should be followed. We also understand that there may be different interpretations of NCP guidance. The overriding issue to Tri-County is what is the likelihood o guidance. The overriding issue to Tri-county is what is the likelihood of exposure to Arsenal contaminants and the risk associated with that exposure. Based on our analysis of the available information we see no need, at this time, to consider a change in the proposed plan based on the risk level trigger utilized. We would request further discussion concerning this issue which may result in additional comment.
Response
The Army has closely followed U.S. Environmental Protection Agency (EPA) guidance and the National Oil and Hazardous Substances Pollution Contingency Plan (NCP) regarding the use of the 10' risk threshold to assess whether remedtation is necessary. Guidance states that if the cumulative cancer risk to an individual is less than 10'. remedial action may not be warranted unless certain site-specific conditions exist. If remedial action is warranted, the 10' to 10' risk range must be achieved, with an initial preference for the 10' end. EPA guidance further states that the upper boundary of the risk range Is not an absolute at I x 10', but rather, the acceptable risk range can extend to 5 x 10'. The cumul2ti%e offpost cancer risk is a maximum of 3 x 10', which is within the acceptable risk range. The Army's goal, through operation of the Offpost Groundwater Intercept and Treatment System. is to further reduce offpost risk toward the 10' level.
The Offpost Study Area risk assessment showed that, even without remedial action, the baseline cumulative risks from contamination in surface water, soil. sediment, air, and groundwater are within the acceptable risk range established by the EPA. However, several site-specific factors
93N23A.enc 2 suggest that remedial alternatives for groundwater should be considered. These site-specific factors consider (1) that groundwater contributes approximately 73 percent of the total baseline risk, (2) maximum contaminant levels (MCLs) and maximum contaminant level goals (MCLGs) are exceeded for some groundwater contaminants, and (3) hazard indices (Hls) for children slightly exceed 1.0 in zones 2, 3, and 4. Through operation of the Offpost Groundwater Intercept and Treatment System and attainment of the cleanup standards specified in the Record of Decision (ROD), the Army intends to further reduce risks toward the 10' level.
Comment 4 - Inter-aouifer Mieration
To prevent contamination of the Arapahoe aquifer from the migration of shallow groundwater containing Arsenal contaminants and to assure the long term quality and safety of the Arapahoe aquifer as a drinking water source we urge the Army to close/seal all wells that penetrate more than one aquifer and are poorly constructed or otherwise damaged or abandoned. This action should be taken in accordance with Rule I I -Abandonment Standard of the State of Colorado, Office of the Engineer. A list of the known wells that present a threat, as described, is available as a result of our ongoing Offpost Private Well Inventory. The prevention of interaquifer migration should be identified as a high priority by the Army in order to avoid degradation of the Arapahoe aquifer.
Resoonse 4
Well closure has been added as a component of the selected remedy. Appendix C of the ROD describes criteria for well closure. Table CA in Appendix C presents the wells identified by the Colorado Department of Health (CDH) and the Tri-County Health Department (TCHD) as candidate wells for closure. The Army will review the information available for the candidate wells for closure and present recommendations for closure to CDH, TCHD, and EPA. Several of these wells have been identified as no longer in use. As noted in the comment, Rule 11. 1. 1 of the Abandonment Standards states that it is the responsibility of the well owner to plug and abandon unused wells properly.
Comment 5 - Control of New Well Construction
We recommend the use of institutional controls to prevent the construction of wells allowing use of the unconfined alluvial groundwater that may contain Arsenal contaminants. It is our understanding that the State Engineer's office is responsible for issuing well permits and has, to date, not established a policy preventing, or at least controlling, the construction of new wells in the offpost area. The Army, EPA. the Colorado Department of Health and Tri-County Health Department should meet with the State Engineer and insist that action be taken to assure that future exposure to Arsenal contaminants cannot take place through consumption of water from new wells that are constructed.
Further, those agencies should work with the State Engineer to assure adequate oversight of the construction of all new water wells in the offpost areas to control the potential for future aquifer contamination.
Respon2e 5
Institutional controls have been added as a component of the selected remedy. Appendix B of the ROD provides an evaluation of the institutional controls available and their applicability. These controls include prohibitions on well construction in areas where groundwater contaminant concentrations exceed cleanup standards and potential well bans in larger areas.
930423A.enc 3 Comment 6
The Army should commit to review of the Proposed Plan in view of future changes in zoning and land use that are proposed for offpost areas 3 and 4. The Army should work with Adams County and/or Commerce City to ensure that any proposed change in land use designation for the offpost areas 3 and 4 will require consideration, with opportunity for public input, of the potential for an increase or decrease in risk to health associated with exposure to Arsenal contaminants. Further clean-up may then be required based on the risk that is calculated and the land use designation proposed. Changes by County or City in land use designation should not result in increased risk to the public. Although all feasible land uses should be considered in the Endangerment Assessment it is Tri-county's opinion that the remedy should also be based on a realistic scenario with a clear commitment to re-evaluate, as necessary, not one that is unduly speculative.
Response 6
The Army is committed to working with Adams County and/or Commerce City to assure that human health is protected in the event that offpost zoning and/or land use changes in the future. The land use scenarios studied in the final Offpost Endangerment Assessment are extremely conservative and provide protectiveness for a range of future land uses. Given the probability of the realignment and widening of 96th Avenue, future development along 96th Avenue will likely be commercial/ industrial or urban residential. Based on local agency planning documents the Army has selected an urban residential land use for the risk evaluation as this would result in more conservative (e.g., higher) estimated risks than the likely commerciaI/industrial land use. In addition, the institutional controls described in Appendix B of the ROD provide additional protection of the public in the event of future land use changes.
Comment 7 - Colorado Standards As ARAR's
We request that the Army provide an explanation of what Colorado standards were not designated as ARAR's and why. Based on this response we may have further questions or comments on the subject of ARAR's.
Response 7
The Army has recognized all state laws and regulations that meet the applicable or relevant and appropriate requirement (ARAR) criteria under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and the NCP. After extensive discussion with the Organizations and State the Army has concluded that the Colorado Basic Standards for Ground- water (CBSGs) do not meet the ARARs criteria because of inconsistent application and ambiguous language. ARARs for the Offpost Operable Unit are based on federal drinking water standards and are protective of human health. In most cases. the treatment goals for the offpost and boundary treatment systems exceed the drinking water standards.
CERCLA expressly provides that state standards can be ARARs at a site. However, only those standards that are more stringent than federal requirements may be considered. In addition, the state standards must be promulgated (i.e.. the requirement must be of general applicability and legally enforceable). Finally, the requirements must be identified in a timely manner by the particular state (40 Code of Federal Regul3tions (CFRI Section 300.400[g][4]).
The Army concludes that the CBSG interim organic standards are not ARARs for two reasons. First, the CERCLA exception in Section 3.11.5(CX5Xa) applies to remedial actions authorized under CERCLA and allows the selection of a remedy that is more or less stringent than would be
930423A.ene 4 achieved by compliance with the statewide standards. As a resulL the overall effect of the statewide standard and accompanying exceptions is a state regulation that is only sometimes more stringent than a federal requirement. CERCLA only considers state standards that are stricter at all times as potential ARARs. Therefore, by definition, the interim organic standards are not ARARs at Superfund sites.
Second, the CBSG interim organic standards cannot be ARARs because they are not generally applicable or legally enforceable. A requirement in CERCLA for state requirements to be ARARs is that they must be promulgated standards, which means they must be generally applicable and legaUy enforceable. Clearly, the interim organic standards do not meet this test when applied at CERCLA sites. By definition, the interim organic standards are applicable throughout the state, except at CERCLA, RCRA, and UST sites. In those instances, the relevance of the standards is determined by the remedial sites. It is hard to understand how the standard could be legally enforceable when the Commission added language specifically ensuring that the standards may or may not be met at CERCLA sites.
For additional discussion, see response to State comment No. 4 in Appendix A-3 of the ROD.
Comment 8 - Soil Contamination In Zones 3 and 4
There was a wide range of results from surficial soil sampling for pesticides in Zones 3 & 4. The risk for each area was calculated based on an average of all samples in that area. We are concerned that the risk for selected areas, in which the highest concentrations of dieldrin were found, may be understated through the averaging process. Has the Army evaluated what risk is associated with each "hot spot?" What is the potential for completing the pathway for exposure of current or future residents or others to that increased risk? We are concerned that there has not been adequate characterization of* the risk in those Zones, both of the concentration and source of dieldrin contamination.
Response 8
The Army used a large amount of onpost and offpost surface soil data to interpret Rocky Mountain Arsenal (RMA)-related soil contamination. ne combination of onpost and offpost data demonstrates that detected concentrations of contaminants offpost are attributable to windblown transport from RMA and to offpost activities, including agricultural application of pesticides. Localized areas of high dieldrin concentrations are unlikely to result from windblown contami- nants. Windblown contamination would more likely result in a uniform deposition.
Because of the extensive agricultural activities that have occurred in areas north and east of the RMA boundaries and the application of registered pesticides that are a consequence of agricul- tural activities, it is not unusual to find dieldrin residues in soil. Examination of organochlorine pesticide data obtained from onpost surface soil samples does not support RMA as being the source for organochlorine pesticide transport east of RMA. In addition, five samples collected east of RMA have dieldrin concentrations ranging from nondetectable to approximately 25 ppb. On this basis, it is the Army's position that the dieldrin detected at 99 ppb east of RMA is not related to onsite activities. This value is at the lower end of EPA's acceptable risk range as specified in the NCP. Therefore, the incorporation of this single value would not have affected the final results of the risk assessment.
930423A.ene Comment 9 - Public Water SUDDIv
Arsenal contaminants, regardless of concentration, have impacted the quality of alluvial ground water, in the offpost area, which is used for domestic purposes. There are also other potential sources of such contamination within the same aquifer for which the Army is not responsible. Whereas there may not be a violation of existing drinking water standards or health advisories and, therefore, no imminent public health ha-rd, the Army should work with other agencies, residents and elected officials that are considering alternative strategies to secure a higher quality and possibly safer domestic water supply for residents in the area.
Resnonse 9
The Army has committed, as part of the Preferred Alternative, that anyone who is drinking water with Arsenal related contaminants above applicable, relevant, and appropriate drinking water standards will be provided an altern3tive water supply. At this time, the Army is not planning to provide a public water supply to residents offpost and cannot unless drinking water standards are being exceeded over a large area.
930423A.enc 6 Office of the Program Manager
Mr. Chris Wiant, M.A., M.P.H. Director of Environmental Health Services Tri-County Health Department 4301 East 72nd Avenue Commerce City, Colorado 80022-1488
Dear Mr. Wiant:
Enclosed are responses to your comments on the Offpost Proposed Plan for the Rocky Mountain Arsenal. The Army appreciates the large number of comments submitted on the Offpost Proposed Plan. I hope these responses increase your understanding of the offpost cleanup.
If you have any further questions please contact Mr. Tim Kilgannon of my staff at (303) 289-0201.
Sincerely,
Eugene H. Bishop Colonel, U.S. Army Program Manager
Enclosure
Copies Furnished:
Captain Jonathan Potter, Litigation Attorney. Rocky Mountain Arsenal Building ill, Commerce City. Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of justice, 999-18th Street, Suite 501, North Tower, Denver. Colorado 80202 Document Tracking Center, AMXRNI-IDT, Room 132, Building ill, Rocky Mountain Arsenal, Commerce City. Colorado 80022 RESPONSES TO CITY OF COMMERCE CITY COMMENTS U.S. DEPARTMENT OF THE ARMY RESPONSES TO CITY OF COMMERCE CITY COMMENTS REGARDING THE ROCKY MOUNTAIN ARSENAL OFFPOST PROPOSED PLAN JUNE 21, 1993
The City of Commerce City (City) submitted comments dated June 21, 1993, on the Offpost Proposed Plan. Attached to the City's comments were two sets of comments from the State of Colorado: The first set of comments was a copy of the State of Colorado's draft formal comments dated May 4, 1993. The State's comments were later submitted, in a slightly reorganized format but essentially verbatim from the draft, as official comments on June 21, 1993. The Army's responses to the State's official comments are provided in Appendix A-3. The second set of State comments attached to the City's comments is identical to the State's comments on the Proposed Plan dated February 19, 1993. The Army's responses to the State's February 19, 1993, comments are provided in Appendix A-1.
The City expressed agreement with the State's comments and offered additional comments on particular issues. The Army's responses are provided below.
Comment I - Apolicable, Relevant and Appropriate Reauirements
(ARARS) CERCLA Section 121(d)(2)(A) (ii) which specifically states, "Any promulgated standard, requirement criteria or limitation under a State environmental or facility siting law that is more stringent than Federal standard, requirement, criteria or limitation, including each such State standard. requirement, criteria or limitation contained in a program approved, authorized or delegated by the Administration under a statute cited in sub-paragraph (A), and that has been identified to the president by the State in a timely manner..." is an 'Applicable, Relevant and Appropriate Requirement,' i.e., (ARAR).
It's believed that this section clearly demonstrates that Congress intended for the states to be pro- active participants in CERCLA actions and allows for stricter state environmental control standards. The city holds that the Army and the U.S. Environmental Protection Agency (EPA) have failed to demonstrate any formal evidences to waive the applicability of the Colorado Basic Standards for Ground Water or the Methodologies of Surface Waters, as is required under Section 121(d)(4) of CERCLA. Furthermore, one of the Army's arguments to dismiss these as ARARs centers on the State purportedly faifing to consistently apply these standards. Now where can one discern any examples offered by the Army or the EPA to substantiate this conclusion. The City finds it paradoxical that the Army would recognize some of these stricter State requirements as ARARs for the remediation of uninhabited Arsenal land and deny their applicability for residential and commercially inhabited off -post areas. Ironically, if the State allows the presently planned rernediation to proceed. it would establish the very precedent the Army is attempting to use in foregoing these State standards.
Response I - Applicable, Relevant 3nd Appropriate Reguirements
The Army has recognized all state laws and regulations that meet the applicable or relevant and appropriate requirement (ARAR) criteria under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). After extensive discussion with all the parties, the Army has concluded that the Colorado Basic Standards for Groundwater (CBSGs) do not meet the ARARs criteria because of inconsistent application and anibiguous language. ARARs for the Offpost Operable Unit are based on federal drinking water standards and are protective of human health.
930423B.ent I in most cases, the treatment goals for the offpost and boundary treatment systems exceed the drinking water standards.
The Army concludes that the CBSG interim organic standards are not ARARs for two reasons. First, the CERCLA exception in Section 3.11.5(C)(5)(a) applies to remedial actions authorized under CERCLA and allows for a remedy that is more or less stringent than would be achieved by compliance with the statewide standards. As a resultý the overall effect of the statewide standard and accompanying exceptions is a state regulation that is only sometimes more stringent thin a federal requirement. CERCLA only considers state standards that are stricter at all times as potential ARARs. Therefore, by definition, the interim organic standards are not ARARs at Superfund sites.
Second, the CBSG interim organic standards cannot be ARARs because they are not generally applicable or legally enforceable. A requirement in CERCLA for state requirements to be ARARs is that they must be promulgated standards, which means they must be generally applicable and legally enforceable. Clearly, the interim organic standards do not meet this test when applied at CERCLA sites. By definition, the interim organic standards are applicable throughout the state, except at CERCLA, RCRA, and Underground Storage Tank sites. In those instances, the relevance of the standards is determined by the remedial sites. It is hard to understand how the standard could be legally enforceable when the Commission added language specifically ensuring that the standards may or may not be met at CERCLA sites. For additional discussion, see response to State comment No. 4 in Appendix A-3 of the ROD.
Comment 2 - Risk Assessment
It perceives the risk assessment as inadequate and not in compliance with the spirit and the intent of the National Contingency Plan (NCP). It is clear that the Army's Risk Assessment is lacking in the following required assessment parameters.
a. Thorough understanding of all possible hazardous constituents (especially DIMP & IMPA) their basic toxicology, routes of exposure, synergistic and antagonistic effects.
b. Thorough delineation of both the vertical and horizontal migration of the contami- nants.
C. Failure to address the levels and effects the contaminants would have on receptors who are predisposed to health problems.
d. Failure to adequately address why the Army departed from the NCPs acceptable basic cancer risk level of one In a million.
Resvonse 2a - Risk Assessment - Ql%jP and IMPA
The U.S. Environmental Protection Agency (EPA) developed the Health Advisory for diisopropyl methylphosphonate (DIMP) in 1989 on the basis of an extensive review of more than 30 existing toxicology studies involving a variety of animal species. EPA's Office of Drinking Water re- reviewed the Health Advisory, in light of the State's concern, and concluded on March 28, 1990, that "the existing Health Advisory values and the basis for the values represent the best scientific position for the protection of human health.* On the basis of toxicity information summarized in EPA's isopropyl methylphosphonic acid (IMPA) Health Advisory and the Integrated Risk
930423B.enc 2 Information System database, there is no information to indicate that IMPA concentrations lower than 700 ppb may pose a threat to human health.
In accordance with EPA's Risk Assessment Guidance for Superfund (RAGS), the Army used EPA's Health Advisory and information contained in the IRIS database to evaluate risk to human health.
For additional discussion of DIMP and IMPA, see response to State comment Nos. 2d and 2h in Appendix A-3 of the ROD.
Response 2b - Risk Assessment - Vertical and Horizontal Extent of Contamination
The Army believes that it has adequately defined the vertical and horizontal extent of contamina- tion in a manner sufficient to allow definition of those areas requiring remediation. However, additional monitoring wells are being installed to enhance the assessment of the locations and concentrations of contaminants in the Offpost Study Area. The performance of the Offpost Groundwater Intercept and Treatment System will be evaluated based on the results of the monitoring program and the system will be modified, if necessary.
Response 2c - Risk Assessment - Individuals Predisposed to Health Problems
The purpose of the baseline risk assessment is to provide estimated risks on the basis of exposures to a normal population. Many of the safety factors built into the assessment of noncarcinogenic and carcinogenic risks are intended to result in the protection of sensitive individuals. While individuals may have specific sensiti-ities, an assessment of these individuals, as well as the particular type of sensitivity or predisposition, is beyond the scope of CERCLA and NCP requirements for a baseline risk assessment.
Response 2d - Risk Assessment - Departure from one in a million risk level
The Army has closely followed EPA guidance and the NCP regarding the use of the 10' risk threshold to assess whether remediation is necessary. Guidance states that if the cumulative cancer risk to an individual is less than 10'. remedial action may not be warranted unless certain site-specific conditions exist. If remedial action is warranted, the 10-4 to 10' risk range must be achieved. uith an initial preference for the 10' end. EPA guidance further states that the upper boundar% of the risk range is not an absolute at I x 10', but rather, the acceptable risk range can extend to 5 x 10'. The cumulative offpost cancer risk is a maximum of 3 x 10', which is within the acceptibie risk range.
In expl2ining the use of the point of departure. the EPA, in the preamble to the NCP, states
77he use of 10' expresses EPA's preference for remedial actions that result in risks at the more protective end of the risk range, but does not renect a presumption that the final remedial action should attain such a risk level (55 Federal Register 8718).
The operation of the Offpost Groundwater Intercept and Treatment System reflects the Army's goal of further reducing the potential risks toward the 10' level.
9SM23B.ene 3 Comment 3 - Point of Compliance be Ile NCP is clear on the issue of ensuring that all poi nts of exposure to a contaminant alternative creates addressed in the risk assessment and any resulting remediation. Essentially, this a no-man's land that is unavailable for development and/or other uses.
Response 3 - Point of Comoliance Army The results of the risk assessment do not preclude development or other land uses. The. intends to achieve the remediation goals at all points within the contaminated plume, consistent with the NCP. The groundwater modeling conducted by the Army in support of the remedial report alternatives evaluation in the Offpost Endangerment Assessment/Feasibility Study (EA/FS) for the used attainment of remediation goals as a primary criterion in assessing time to cleanup Plan various remedial alternatives. This information is presented in summary form in the Proposed of the EA/FS. and Volume VI, Section 3.2 of the EA/FS and in detail in Volume VII, Appendix E the The area of concern to the State appears to be the portion of the plume that lies between and North Boundary Containment System (NBCS) and the Offpost Groundwater Intercept Treatment System. The NBCS has been demonstrated to be effective in reducing the contaminant concentrations at the RMA boundary to meet remediation goals. The purpose of the Offpost plume that Groundwater Intercept and Treatment System is to extract and treat that portion of the and had migrated past the RMA boundary (prior to installation of the North Boundary System) contains contaminants exceeding the remediation goals. The groundwater monitoring program attainment implemented as part of the selected remedy will provide the data necessary to evaluate to of treatment goals within the plume and provide data necessary for assessment of modifications the treatment system, if necessary.
Comment 4 - Land Use a. Classification of Land Use
The assessment process fails to use proper and correct demographics, zoning and land use data. The City is of the opinion that the Army failed to consider that the City has and is currently in the process of annexing properties to the north and west of the Arsenal. It appears that the current remediation plan was based solely upon land use information provided by Adams county, and thereby neglects the future land use plans of Commerce City.
b. Institutional Controls
The use of institutional controls are only useful temporary procedures and by themselves offer a loop hole to responsible parties to negate CERCLA's main purpose: the thorough restoration of contaminated environments. The Army should seek whatever institutional controls are necessary to prevent any possible adverse health effects to residents and businesses in the affected area. The City also believes that it is the responsibility of the Army to provide water taps as emergency institutional controls to negate any possible adverse health effects to the areas citizens during remediation of the ground water.
Response 4a - Classification of Land Use
The future land use scenarios used by the Army in the risk assessment are highly conservative. For example, the rural residential scenario used in zones 1, 2, and 6 includes all pathways contributing substantially to potential risk. even though most of the total population is not exposed to the agricultural exposure pathways described in the risk assessment. Shell Oil Company
9W423B.enc 4 purchased the land in zones 3 and 4 for Army use in constructing the Offpost Groundwater Intercept and Treatment System. It is not presently occupied; therefore, the current zoning designation as rural residential is not applicable. Given the probability of the realignment and widening of 96th Avenue, future development along 96th Avenue will likely be commercial/ industrial or urban residential. Based on local agency planning documents, the Army selected an urban residential land use for the risk evaluation as this would result in more conservative (e.g., higher) estimated risks than the likely commercial/industrial land use.
The Army did not neglect land use plans of Commerce City. Section 2.2.2, Volume II, of the Endangerment Assessment (EA) discusses the master plans, zoning, and planning documents from Commerce City that were utilized. Figure 2.2.2.1.2-2 of the EA presents those areas immediately north and west of RMA that have been zoned by Commerce City.
For additional discussion, see response to State comment No. 3a in Appendix A-3 of the ROD.
Rest)onse 4b - Institutional Controls
Institutional controls have been added as a component of the selected remedy. Appendix B of the ROD provides an evaluation of the institutional controls available and their applicability.
Comment I and 2 - DIMP and IMPA Contamination in GroundWater.
This appears to be another instance where the Army and EPA are ignoring CERCLA's Section 121(d)2(A) mandating the use of State environmental standards and/or criteria as legal ARARs. Both the Army and the EPA have failed to produce any convincing scientific evidence to make use of the waiver from these under Section 121(d)(4). While the Army, EPA and the State Health Department disagree over what levels of these substances may be safe, the City is of the opinion that additional toxicological information is needed before proceeding with any remediation choice. Therefore, the City feels it is incumbent upon the Army to provide funding for an independent toxicological study to ascertain the actual hazards of these two substances.
Response I and 2 - DIMP and TMPA Contamination in Groundwater
See response to State comment Nos. 2d and 2h in Appendix A-3 of the ROD.
In accordance with EPA guidance on conducting risk assessments, the Army has used the EPA's Health Advisory levels for both DIMP and IMPA. The Army believes that the State has not provided sufficient or scientifically defensible evidence that the EPA's Health Advisory levels are not sufficiently protective of human health. The EPA and the Army believe that there is sufficient toxicological information available to support the Health Advisory levels. The Army is currently evaluating the applicability of the 8 parts per billion level for DIMP that the Water Quality Control Commission may promulg3te in a few months.
The Offpost Groundwater Intercept and Treatment System is located in areas of highest contam- inant concentrations. The Army is aware that concentrations of DIMP greater than 600 parts per billion (ppb) have been reported north of the Offpost Groundwater Intercept and Treatment System. In that regard, the offpost remed13l action groundwater monitoring program will be coordinated with the three existing groundwater monitoring programs active in the Offpost Study Area. These three programs are (1) the Groundwater Monitoring Program, (2) the Offpost Groundwater Intercept and Treatment System monitoring program, and (3) the private well monitoring program. Additionally, in the area north of the Intercept and Treatment System where DIMP has been reported to exceed 600 ppb, three monitoring wells will be replaced and three new
930423B.enc 5 monitoring wells will be installed. Replacement wells are being installed for three wells originally in the monitoring network that were found to be damaged or destroyed. Two new monitoring wells will be installed downgradient of the First Creek Pathway, and one new monitoring well will be installed downgradient of the northern Pathway. The purpose of the three new monitoring wells is to aid in assessing the extent of contamination downgradient of the Offpost Groundwater Intercept and Treatment System. Data collected from these wells and existing wells will be used to further define the extent of contamination greater than the remediation goals in this area and assist in determining whether modifications to the design of the Offpost Groundwater Intercept and Treatment System are necessary.
Comment 3 - More Aggressive Treatment of Ground water
If the final remediation includes a "pump and Treat System." At the present, the City holds that the selection of the current preferred remediation plan was based upon inconclusive scientific studies and unfounded assumptions. In view of these inadequacies, and the lack of local public support, it is hoped that the Army and EPA will re-examine its reasons for selecting this alternative, with a focus on a more realistic remediation time frame.
Although the City has no problem with the pump and treat technology for some remediation objectives, it is now of the opinion that the Army and EPA appear determined to foist what was once originally intended to be an interim remedial measure as a permanent solution. Although the City supported the interim use of the proposed alternative action, it did so with the understanding that it was an auxiliary plan to prevent future migration of the contaminants. Now that it appears that the Army is relying upon this supposed interim action as a permanent solution, the City must now question the wisdom of commenting favorably upon this as well as other interim Arsenal actions.
Response 3 - More Aggressive TM-31ment of Groundwater
The Army selected Alternative N-4 instead of Alternative N-5 primarily because Alternative N-4 includes potential future modifications, only if such modifications are found to be necessary based on actual operating data. to the Offpost Groundwater Intercept and Treatment System. Selection of Alternati%e N-5 instead of Alternative N-4 will not necessarily provide a more cost effective alternatt%e because or a slightly shorter estimated remediation timeframe. The Army based its assessment of the relative differences between the groundwater alternatives and estimates of remediation timeframes on groundwater models that are very general in nature; thus, the estimated remediation timeframes should not be construed as precise predictions. Use of actual full-scale operating data is preferable to selecting additional components for the Offpost Ground%ater Intercept and Treatment System using the more speculative modeling data (i.e., Alternatt%e N-5). The Offpost Proposed Plan culminates approximately 10 years of study. The Army belir%ei that the alternative chosen combines exceptional protection of human health and the environment with the common sense approach of improving the groundwater systems if post- ROD monitoring results determine it necessary.
For additional discussion, see response to State comment No. 2a in Appendix A-3 of the ROD.
Comment 8 - Human Health Risk characterization, 9 - Ecological Risk Characterization, 10 - Hot Spots in Soils. and I I - Contamination of Barr Lake
Because of the lack of toxicological and assessment sampling data, it appears that the Army (with the approval of the EPA) has selected a premature remedial action plan that fails to sufficiently
93G423B.enc 6 address all contaminated environs. Further, there is still the unresolved question of what particular ARARs apply. It's hoped that the Army and EPA broaden the scope of the remediation study to cover all the off-post contamination areas and contaminates.
Response 8 - Human Health Risk Characterization
The Army considered all of the exposure pathways listed by the State and, on the basis of EPA guidance Presented in Risk Assessment Guidance for Superfund (RAGS), the pathways were eliminated from further evaluation in the risk assessment. The Army presented the human health risk assessment pathways to EPA, the U.S. Fish and Wildlife Service (USFWS), Shell Oil Company, and the State for discussion. After identifying all potential complete exposure pathways, the Army followed EPA guidance in RAGS (page 6-16) to select those pathways to be evaluated further in the exposure assessment. Guidance allows for the elimination of some complete pathways if there is sound justification, such as:
1. The exposure resulting from the pathway is much less than that from another pathway involving the same medium at the same exposure point.
2. The potential magnitude of the exposure from the pathway is low.
3. The probability of the exposure occurring is very low, and the risks associated with the occurrence are not high.
For additional discussion, see response to State comment No. 8 in Appendix A- I of the ROD.
Resr)onse 9 - Ecoloeical Risk Assessment
The State has not presented any evidence to support its contention that assumptions made for the ecological risk assessment (RA) will result in levels of contamination remaining in the Offpost Study Area that may not be protective of biota. The Army presented the ecological RA assump- tions and approaches to the USFWS, EPA, Shell Oil Company, and the State at meetings through- out the ecological RA study period. The Army considered these meetings and subsequent feedback critical because of the lack of formalized EPA guidance on conducting a dose-based ecological assessment. The Army believes that the findings of the ecological RA are protective of wildlife because many aspects of the approaches used to estimate potential effects are more conservative than other hazard assessment methodologies currently followed by EPA and other agencies. Because the approaches to conducting an ecological RA are continually being devel- oped, the assumptions and parameters used by the Army for the final ecological RA were thoroughly discussed with the parties and modif led throughout the ecological RA process, and the best available methodology and professional judgement were used. The USFWS participated in the ecological RA process and supported the final methodologies used to evaluate the potential ecological hazards.
Resr)onse 10 - Hot Spots in Soil
Background sampling indicated that pesticides are present throughout the Offpost Study Area. Agricultural application of pesticides is a contributing source. Agricultural application of a registered pesticide is exempt from CERCLA. However, the risk associated with the dieldrin concentrations in these hot spots do not exceed a lifetime caner risk of 5 x 10', which is at the lower end of the acceptable risk range defined by the U.S. Environmental Protection Agency (EPA). Therefore, specific cleanup of these soil areas is not required. Cleanup of offpost groundwater will provide the greatest benefit of risk reduction.
930423B.ene 7 Response I I - Contamination-of Barr La-ke
Remediation of offpost groundwater well reduce contaminant concentrations on First Creek. Surface-water monitoring will continue as part of the offpost monitoring program. A surface- water monitoring program has been included as a component of the selected remedy. An offpOst implementation document will be prepared following the approval of the Record of Decision, which will include a monitoring program for surface water and groundwater.
Comment 12 - Closine Poorly Constructed -Domestic Wells
The City strongly agrees with the State on this issue. It is incumbent upon the Army to stop the migration of the contaminants to the deeper Arapahoe Formation aquifer, and at the same time provide fresh water to affected area residents and businesses. CERCLA and the NCP both emphasize the importance of preventing the spread of contamination during emergency and long- term removal and remediation actions. Given the lack of thorough understanding of al possible contamination, routes of exposure, toxicological effects, and ARA applicability, the Army should take the prudent move to close these wells regardless of what particular remediation plan is instituted.
Rest)onse 12 - Closine of Pooriv Constructed Domestic WellI
The Army his incorporated well closure as a component of the selected remedy. The criteria for well closure are presented in Appendix C of the Record of Decision.
930423B.enc 8 Office of the Program Manager
Mr. Steven S. Crowell, Sr. City Manager of Commerce City 5291 East 60th Avenue P.O. Box 40 Commerce City, Colorado 80037
Dear Mr. Crowell:
Enclosed are responses to your comments on the Offpost Proposed Plan for the Rocky Mountain Arsenal. The Army appreciates the large number of comments submitted on the Offpost Proposed Plan. I hope these responses increase your understanding of the offpost cteanup.
If you have any further questions please contact Mr. Tim Kilgannon of my staff at (303) 289-0201.
Sincerely,
Eugene H. Bishop Colonel, U.S. Army Program Manager
Enclosure
Copies Furnished:
Captain Jonathan Potter, Litigation Attorney, Rocky Mountain Arsenal Building ill, Commerce City, Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of justice, 999-18th Street, Suite 501, North Tower, Denver. Colorado 80202 Document Tracking Center, ANLXRNI-DDT, Room 132, Building 111, Rocky Mountain Arsenal, Commerce City, Colorado 80022 RESPONSES TO CITY OF BRIGHTON COMMENTS OF A CITYBRIGHTON V June 17, 1993
Colonel Eugene H. Bishop Program Manager for the Rocky Mountain Arsenal United States Army Attn. AMXRM-PM Bldg. 111 RMA Commerce City, Colorado 80022-2180
Dear Colonel Bishop:
The City of Brighton wishes to comment on the off post plan proposed by the U.S. Army for the Rocky Mountain Arsenal.
The City has been harmed by the presence of DIMP and possibly other Arsenal contaminants In our growth area. We feel that this limits our ability to access new water supplies locally for future growth and poses a threat to our existing wells since DIMP has been found as close to Brighton as 136th Avenue. T- 4-Our Southern growth area is located in the Northern reaches of the DIMP influence area.-1 Because of this the City feels that we should be guaranteed an--'uncontaminated water supply for the present and future.
Installing a municipal supply to the DIMP areas should not be the only answer. We must insure that the contamination from the past does not come back to haunt the future residents of this area. If many years down the road we f Ind that there Is a very serious problem with DIMP or any other Arsenal contaminants then it would cause an even more monumental problem than what we have now.
The U.S. Army should meet the primary drinking water standards for groundwater within a ten year program.
Sincerely,
James Ed Burke Dir. of Utilities Operations
cc: Hank Brown, U.S. Senator Mayor Hamstra and City Council Members Ted Anderson, City Manaqer NA qs- U
22 South 4th Avenue - Br4ghton, Cýolorndo 8080-1 - 13031 659-4050 U.S. DEPARTMENT OF THE ARMY RESPONSES TO CITY OF BRIGHTON COMMENTS REGARDING THE ROCKY MOUNTAIN ARSENAL OFFPOST PROPOSED PLAN JUNE 17, 1993
GENERAL COMMENTS
Comment 1. Contam inat ion -Problems in the Future
The Army does not anticipate that increased concentrations of contaminants will occur in the future. The purpose of the long-term monitoring program to be implemented as part of the selected remedy is to assess the performance of both the existing boundary containment systems and the Offpost Groundwater Intercept and Treatment System. If monitoring data indicate that these systems can be improved with little or no change in long-term cost and thus result in a quicker remediation of offpost groundwater, modifications to the system will be made. The Army remains committed to long-term monitoring of Rocky Mountain Arsenal (RMA)-related contami- nants.
21905 301020 - CR-04 0808120193 RESPONSES TO CITY OF THORNTON COMMENTS Akkm City Of fop Thornton 9500 Civic Center Drive PO. Box 291M Thorriton. Coloraw 80229-12M
April 19, 1993
Program Manager for Arsenal Attn: AmxRM-PM/CoL E gene H. Bishop Building Ill-RMA Commerce City, CO -2180
Dear Col. Bishop:
On behalf of the Thornton City Council and the residents of Thornton, I would like to express our concerns about the Rocky Mountain Arsenal Offpost Proposed Plan. Based on staff's review of the Proposed Plan and comments we have received from the Colorado Department of Health, we feel the Colorado Department of Health has expressed legid=te concerns with which we concur. For example, regulations that implement Superfund law state that a remediation plan should be designed to prevent excess risk to human health greater than one in one million (carcinogen risk). The Army proposes a carcinogen exposure level as high as three in 10,000 (Area I, Zone 3). We oppose special standards for the Army.
The City would like to see the Army work cooperatively with the Colorado Department of Health to determine an acceptable level of DRAP (a byproduct of nerve gas) in the groundwater and/or an alternative to providing bottled water to over 600 residents. Finally, we feel that state standards for groundwater cleanup should be used for offpost cleanup. It is important that the Army comply with Superfund cleanup regulations for offpost areas as well as within the gates.
To summarize, we feel it is important that the Army adhere to regulations established by Superiund regulations. The Army is not above the law and should ensure that State and Superfund regulations are being met in order to provide safe drinking water to the residents of Colorado.
Thank you for your time and consideration. If you have any questions or comments, please contact Doug Lewis at 538-7692.
Sincerely,
Mar t Carpenter ayor; 5-ary M
CC:- Hank Brown, United States Senate Ben Nighthorse Campbell, United States Senate David Skaggs, Urdted States House of Representatives Wayne Allard, United States House of Representatives ýrAk Qs4414 "The City of Planned Progress" U.S. DEPARTMENT OF THE ARMY RESPONSES TO THE CITY OF THORNTON COMMENTS REGARDING THE ROCKY MOUNTAIN ARSENAL OFFPOST PROPOSED PLAN APRIL 19, 1993
GENERAL COMMENTS
Comment 1. Acceptable Risk Level and Departure from One in a Million
The Army has closely followed U.S. Environmental Protection Agency (EPA) guidance and the National Oil and Hazardous Substances Pollution Contingency Plan (NCP) regarding the use of the 10' risk threshold to assess whether remediation is necessary. Guidance states that if the cumulative cancer risk to an individual is less than 10'. remedial action may not be warranted unless certain site-specific conditions exist. If remedial action is warranted, the 10' to 10' risk range must be achieved, with an initial preference for the 10' end. EPA guidance further states that the upper boundary of the risk range is not an absolute at I x 10". but rather, the acceptable risk range can extend to 5 x 10'. The cumulative offpost cancer risk is a maximum of 3 x 10', which is within the acceptable risk range.
In explaining the use of the point of departure, the EPA, in the preamble to the NCP, states
The use of 10' expresses EPA's preference for remedial actions that result in risks at the more protective end of the risk range, but does not reflect a presumption that the final remedial action should attain such a risk level (55 Federal Register 8718).
The operation of the Offpost Groundwater Intercept and Treatment System reflects the Army's goal of further reducing the potential risks toward the 10' level.
Comment :. Accemable LeNel of DI%1P
The L:.S. Environmental Protection Agency (EPA) developed the Health Advisory for diisopropyl meth%lphosphonate (DVAP) in 1989 on the basis of an extensive review of more than 30 existing toxicologý studies involving a variety of animal species. EPA's Office of Drinking Water re- reviewed the Health Advisory, In ;Ight of the State's concern. and concluded on March 28. 1990, that "the existing Health Advisory values and the basis for the values represent the best scientific position for the protection of human health.'
In accordance with EPA's Risk- Assessment Guidance for Superfund. the Army used EPA's Health Advisor%- and information contained in the IRIS database to evaluate risk to human health.
For additional discussion of DIMP. see response to State comment No. 2d in Appendix A-3 of this ROD.
21905 301020 - CR-04 0808120193 Comment 3. Alternatives to Bottled Water
The Army will continue to work with EPA, the Colorado Department of Health (CDH), and the Tri-Counry Health Department (TCHD) in evaluating the performance of the Offpost Ground- water Intercept and Treatment System. Although drinking water standards-are not exceeded for private residences, CDH is providing bottled to many residents.
Comment 4. Use of State Standards for Cleanup Goals
The Army has recognized all state laws and regulations that meet the applicable or relevant and appropriate requirement (ARAR) criteria under the CERCLA and the NCP. After extensive discussion with all the parties, the Army has concluded that the Colorado Basic Standards for Groundwater (CBSGs) do not meet the ARARs criteria because of inconsistent application and ambiguous language. ARARs for the Offpost Operable Unit are based on federal drinking water standards and are protective of human health. In most cases, the treatment goals for the offpost and boundary treatment systems exceed the drinking water standards.
CERCLA expressly provides that state standards can be ARARs at a site. However, only those standards that are more stringent than federal requirements may be considered. In addition, the state standards must be promulgated (i.e.. the requirement must be of general applicability and legally enforceable). Finally, the requirements must be identified in a timely manner by the particular state (40 Code of Federal Regulations [CFRI Section 300.400[g][4)). -
The Army concludes that the CBSG interim organic standards are not ARARs for two reasons. First, the CERCLA exception in Section 3.1 I.S(C)(5)(a) applies to remedial actions authorized under CERCLA that are more or less stringent than would be achieved by compliance with the statewide standards. As a result, the overall effect of the statewide standard and accompanying exceptions is a state regulation that is only sometimes more stringent than a federal requirement. CERCLA only considers state standards that are stricter at all times as potential ARARs. Therefore. b% definition. the interim organic standards are not ARARs at Superfund sites.
Second. the CBSG interim organic standards cannot be ARARs because they are not generally applicable or legally enforceable. A requirement in CERCLA for state requirements to be ARARs is that they must be promulgated standards, which means they must be generally applicable and legally enforceable. Clearly. the interim organic standards do not meet this test when applied at CERCLA sites. By definition. the interim organic standards are applicable throughout the state. except at CERCLA. RCRA. and UST sites. In those instances, the relevance of the standards is determined b% the remedial sites It is hard to understand how the standard could be legally enforceable when the Commission added language specifically ensuring that the standards may or may not be met at CERCLA sites
For additional discussion. see response to State comment No. 4 in Appendix A-3 of this ROD.
Comment 5. Compliance with Superfund Restulations
The Arm), is meeting all applicable Superfund regulations.
21905 301020 - CR-04 0908120193 RESPONSES TO CffY AND COUNTY OF DENVER COMMENTS CrrY AND COUNTY OF DENVER
DEpA=WMOFMALIzAni&OmTM5 WSUNNOMST= DENVM COLORADO 8020"507 0 RN; 896 ;96 FRONE: MW) 436--,3W EDMRONNg"NTAL HEALTH WELUNGTON L WEBO FAX-(303) 436-59074 mum
,7une 21, 1993
offpost Proposed Plan Comments Program Manager for Rocky Kountain Arsenal Bisnop Attn: ANXRX-PM/Col. Eugene K. Building 111-M co- rce City, Colo. 80022-2180 Plan Cc=ents on The Proposed RE: City and county of Denver Arsenal Offpost Study Area For The Rocky Mountain
the proposed plan city and County of Denver on bahalf of the this office. We appreciate has been revieved by this comments. opportunity to provide may be construed as that the Offpost Plan We are concerned offpost necessary to address all the final resolution no offpost, question the decision that contýazination. We east, dnd south for soils to the vast, response is necessary (or, in some the absence of sufficient of the Arsenal in that a sa=le data. we think areaz, any) offpost soil vatter in of soil, surface and ground thorough investigation The offpost to the Arsenal is essential. all areas adjacent these areas, be expanded to include study area should eithex De for these areas should or a second offpost study undertaken. assist in ensuring a remedy We hope that our input vill health and the environment. protective of human
Sinc
N r Thomas L Stauch, Chief Division Environmental Protection
Health oirector, Denver Public Cr-: Franklyn aud3on, Office Chief of Staff, Mayor's Theresa Donahue, Deputy U.S. DEPARTMENT OF THE ARMY RESPONSES TO THE CITY AND COUNTY OF DENVER COMMENTS REGARDING THE ROCKY MOUNTAIN ARSENAL OFFPOST PROPOSED PLAN JUNE 21, 1993
GENERAL COMMENTS
Comment 1, Additional Offr)ost Remedial Actions mav be Necessarv
The preferred alternative identified in the Record of Decision (ROD) is "final" in the context that it is based on currently available information. Because of the flexibility in implementation, if additional concerns are identified in the Offpost Study Area, an amendment to the ROD may be issued to address additional remediation actions. Although the Offpost Groundwater Intercept and Treatment System was originally developed as an Interim Response Action (IRA). the evaluation of alternatives for the Offpost Operable Unit (OU) indicated that this IRA is the most effective alternative studied in the Feasibility Study and, thus. is the selected remedy for the Offpost OU. The Army has adequately evaluated the soils to the west, east, and south of the Arsenal and determined that either 1) contaminant concentrations identified are typical of background or 2) the risks associated with the contamination are within the acceptable risk range defined by the U.S. Environmental Protection Agency. Based on these factors, remediation of soil is not necessar\.
21905 301020 - CR-04 0808120193 RESPONSES TO ADAMS COUNTY COMMENTS A 0 A M S C 0 U N T Y, C 0 L 0 It A ID 0
Am== AM Aye= ARKOOOK COLMADO @=I Q= a@-2723 FALI C= 6st-OW May 19. 1993 r= OW Is
CoIonel Eugene EL Bishop pmgram blanager for Rocky Mount= Arsenal jUý2 5 Buildin 111-1;SKA' APý Commerce L-Ity. CO 800=-2180
Dear colonel Bishop: Adam county bas reviewed the Proposed Plan fm the RMkY Mountain has generated the Arsenal Offpost Study Area (the Plan). That review following comments made on behaLf of the Cotintr.
1 - The Plan fails to address the potential of sumface water runon/runoff tn the Irondale Gulch. and FI= Creek drainageways. These dralz%agewaYs ftýý the Arsenal pmpertjr in a nortirwestm-ty dLrection and drain into the South Mver. Developznent In the Denver Gateway plann area and Aurora Platte of impervious to the southeast of the Arsemal wdl add signiAcant amounts surfaces within theýe dratnagemLY& The Plazi. should address the potmbal for carrying pollutants off the Arsenal property through surface water intrusion and necessary niftigation of that potentiaL 2- The options .anabzed appear somewhat limited. p2rticulady as they rehft to the northwest pb=e group. For rtmediation of that r plume operation. of the there are two afternadves advanced: do notbing or contame containment system. -Are there no other options feasible to analyze PertaIMIng to MMediation of this plume? the vidnity Of 3. Them fs an nrea just north of the Arsenal botmdary in which is containinated with pesticides suspected to have been Peoria Street of this wind-deposited. The Plan does not address itself to & diation. probiern arta. The County c=.-Ader3 this ov=-sight, to be a ftw in, the Plan which the Dep2ranent, of the Army should address.
Although not a considern an made by the Department of ihe Army in the s=ngly urges the Fedcral Gcvemme= to adopt tbLe State of Plan. the County State.' standard for DIM? when that standard is adopted by the Colorado Departmemt, of Considerable analysis has been undemý by the Colorado in order to adopt a reasanable st=d=-d forbuTnaw cz;MurC to this Health urges compound. Although not yet formalty adopted by the State. the County As acceptance and adoption by the Fedcral Gvvenixnent after adOPtIOn bY the State.
N^MW L am aAMT- VALRM GUMUXMO A. DOMMMA BOAM OF CCU%nY O=Cr2 DSMCr3
MML PME AM MKMRM 7tank you for the opportunItY to caccanent an the Proposed Plan for the P4)cky Mountain Arsenal Ofipost Study Area. The Cmnxty kx*s firward to the COGU=Cd rem xilation, of tbj3 facility and elfraination of ift to off-post properties and the citi= of Ada= County.
Sincerely,
Chak=am *BoardHarold cfa CmmtyEhe. Cam-LssjCnCr3
copies: 7he Honarable David R.D. BU3by. Mayor of Cm=erce City Xs- Mamon G21ZOt CDOH
TOTRL PAGE.003 3Fx-- U.S. DEPARTMENT OF THE ARMY RESPONSES TO ADAMS COUNTY COMMENTS REGARDING THE ROCKY MOUNTAIN ARSENAL PROPOSED PLAN MAY 19,1993
Resvonse 1. Surface Water Runon/runoff
An evaluation of additional surface-water flow through and beyond Rocky Mountain Arsenal (RMA) as a result of increased development southeast of RMA is beyond the scope of the Endangerment Assessment/Feasibility Study (EA/FS). The surface-water monitoring program, a component of the selected remedy in the Record of Decision (ROD) that will be developed after finalizing the ROD, will aid in assessing the potential impacts from any additional surface water runon and runoff.
Resvonse 2. Remedial Alternatives for the Northwest Plume Grout)
The groundwater northwest of RMA contains concentrations of contaminants slightly exceeding the remediation goals. Evaluation of remedial alternatives in the EA/FS showed that alternatives consisting of extraction wells in this dilute plume did not appreciably accelerate clean up imef rames as compared to continued operation of the Northwest Boundary Containment System (NWBCS). Continued operation of the NWBCS will further reduce the concentrations of contaminants in the Offpost Study Area north and northwest of the boundary system. Approxi- mately three to eight years would b,ý required to achieve remediation goals in this area.
Response 3. Pesticide-Contaminated Soil near Peoria Street
The estimated risks associated with the measured concentrations of pesticides in soil in this area are within the acceptable risk range established by the EPA and therefore clean up of these soils is not required.
Resr)onse 4. DIMP Standard
The U.S. Environmental Protection Agency (EPA) developed the Health Advisory for diisopropyl methylphosphonate (DIMP) in 1989 on the basis of an extensive review of more than 30 existing toxicology studies involving a variety of animal species. EPA's Office of Drinking Water re- reviewed the Health Advisory. in light of the State's concern, and concluded on March 28, 1990, that "the existing Health Advisory values and the basis for the values represent the best scientific position for the protection of human health.'
The EPA acted appropriately when rejecting the Aulerich mink study as the critical study on which to establish a human health drink-Ing water advisory on the basis of extrapolative relevance to humans and the confounding influences of background mortality in mink. The Army disagrees with the State's statement that the Integrated Risk Information System (IRIS) mandates that health-based standards be based on the most sensitive species tested. IRIS describes through a .concept paper" (IRIS Background Document IA - Reference Dose (RfD): Description and Use in Health Risk Assessment) the recommended approach to select the most appropriate critical study and implies the use of informed professional judgment when making that selection, particularly when identifying the animal model that is most relevant to humans. The EPA uses a panel of high-level scientists to make the critical study selection rather than relying on the opinions of a single individual.
930423F.enc I Health In accordance with EPA's Risk Assessment Guidance for Superfund, the Army used EPA's human health. Advisory and information contained in the IRLS database to evaloate risk to
The Water Quality Control Commission may adopt an 9 parts per billion (ppb) level in a few to the months. The Army is currently evaluating the applicability of the 8 ppb level for DIMP Offpost area. Appendix A-3 For additional discussion regarding DIMP, see response to State comment No. 2d in of this ROD.
930423F.enc 2 Office of the Program Manager
Mr. Harold E. Kite Chairman, Board of Adams County Commissioners 450 South 4th Avenue' Brighton, Colorado 80601
Dear Mr. Kite: for Enclosed are responses to your comments on the Offpost Proposed Plan of comments the Rocky Mountain Arsenal. The Army appreciates the large number your submitted on the Offpost Proposed Plan. I hope these responses increase understanding of the Offpost cleanup.
If you have any further questions please contact Mr. Tim Kilgannon of my staff at (303) 289-0201. Sincerely,
Eugene H. Bishop Colonel, U.S. Army Program Manager
Enclosure
Copies Furnished:
Captain Jonathan Potter, Litigation Attorney, Rocky Mountain Arsenal Building ill, Commerce City, Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of justice, 999-18th Street, Suite 501, North Tower, Denver, Colorado 80202 Document Tracking Center, ANLXRNI-DDT. Room 132, Building 111, Rocky Mountain Arsenal, Commerce Citv, Colorado 80022 RESPONSES TO THE CITY OF AURORA COMMENTS PhUL & TAUES
Mayff 1470 South Hrruna Street Aurom Coloraco OW12 303-GW7015 July 19, 1993
Off Post Proposed Plan Comments Program Mwiager for Rocky Mountain Arsenal Attn: AMXRM-PM/CoI. Euqene H. Bishop Building 111 -RMA Commerce City, Colorado 80022-2180
Dear Colonel Bishop,
While we are aware that the public comment period for the Offoost Proposed Plan has closed. the City of Aurora still wishes to express some concerns relative to the various posfflon3 assumed by the Colorado Department of Health and the Army an proposed clean-up acdvWes. In particular, the City concurs with two of the State's concerns: 1) State environmental laws and regulations should be observed as appropriate clean-up standards for local Superfund Sites. such as the Colorado Basic Standards for Groundwater, and 2) assumptions of appropriate risk levels for cancer 0 x 104) under National Contingency Plan provisions should apply, undess deviation from this Opoint of daparturen can be demonstrmd. It doewlt appear that the State's objections with regard to these iS3U83 have been adequately addressed by the Army.
In addition to our continuing participation an the Technical Review Committee, we appreciate tha OPPOMmity to comment on trd3 and other upcoming remediation programs of interest at the Arsenal.
Sincerely,
Paul E. Tauar Mayor U.S. DEPARTMENT OF THE ARMY RESPONSES TO CITY OF AURORA COMMENTS REGARDING THE ROCKY MOUNTAIN ARSENAL OFFPOST PROPOSED PLAN JULY 19, 1993
GENERAL COMMENTS
Response to Comment No. I
The Army has recognized all state laws and regulations that meet the applicable or relevant and appropriate requirement (ARAR) criteria under the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and the NCP. After extensive discussion with the Organizations and State the Army has concluded that the Colorado Basic Standards for Ground- water (CBSGs) do not meet the ARARs criteria because of inconsistent application and ambiguous language. ARARs for the Offpost Operable Unit are based on federal drinking water standards and are protective of human health. In most cases, the treatment goals for the offpost and boundary treatment systems exceed the drinking water standards.
CERCLA expressly provides that state standards can be ARARs at a site. However, only those standards that are more stringent than federal requirements may be considered. In addition, the state standards must be promulgated (i.e.. the requirement must be of general applicability and legally enforceable). Finally, the requirements must be identified in a timely manner by the particular state (40 Code of Federal Regulations [CFRj Section 300.400[g][4]).
The Army concludes that the CBSG interim organic standards are not ARARs for two reasons. First. the CERCLA exception in Section 3.11.5(C)(5)(a) applies to remedial actions authorized under CERCLA that are more or less stringent than would be achieved by compliance with the statewide standards. As a result, the overall effect of the statewide standard and accompanying exceptions is a state regulation that is only sometimes more stringent than a federal requirement. CERCLA only considers state standards that are stricter at all times as potential ARARs. Therefore. by definition, the interim organic standards are not ARARs at Superfund sites.
Second. the CBSG interim organic standards cannot be ARARs because they are not generally applicable or legally enforceable. A requirement in CERCLA for state requirements to be ARARs is that they must be promulgated standards. which means they must be generall\ applicable and legally enforceable. Cle3rl\, the interim organic standards do not meet this test v,-hen applied at CERCLA sites. B-, definition. the interim organic standards are applicable throughout the state. except at CERCLA. RCRA. and UST sites. In those instances, the relevance of the standards is determined by the remedial sites It is hard to understand how the standard could be legally enforceable when the Commission added language specifically ensuring that the standards may or may not be met at CERCLA sites
Response to Comment No. 7.
The Army has closely followed U.S. En%ironment3l protection Agency (EPA) guidance and the National Oil and Hazardous Substances Pollution Contingency Plan (NCP) regarding the use of the 10" risk threshold to assess whether remediation is necessary. Guidance states that if the
21905 301020 - CR-04 0808120193 cumulative cancer risk to an individual is less than 10', remedial action may not be warranted unless certain site-specific conditions exist. If remedial action is warranted, the 10-4 to 10'6 risk range must be achieved, with an initial preference for the 10' end. EPA guidance further states that the upper boundary of the risk range is not an absolute at I x 10 4 , but rather, the acceptable risk range can extend to 5 x 10'. The cumulative offpost cancer risk is a maximum of 3 x 101, which is within the acceptable risk range. The Army's goal, through operation of the Offpost Groundwater Intercept and Treatment System, is to further reduce offpost risk toward the 10,6 level.
The Offpost Study Area risk assessment showed that, even without remedial action, the baseline cumulative risks from contamination in surface water, soil, sediment, air, and groundwater are within the acceptable risk range esmblished by the EPA. However, several site-specific factors suggest that remedial alternatives for groundwater should be considered. These site-specific factors consider (1) that groundwater contributes approximately 73 percent of the total baseline risk, (2) maximum contaminant levels (MCLs) and maximum contaminant level goals (MCLGs) are exceeded for some groundwater contaminants, and (3) hazard indices (His) for children slightly exceed 1.0 in zones 2, 3, and 4. Through operation of the Offpost Groundwater Intercept and Treatment System attainment of the cleanup standards specified in the Record of Decision (ROD), the Army intends to further reduce potential carcinogenic risks toward the 10-, level and reduce His to less than 1.0.
2190S 301020 - CR-04 0808120193 Appendix A-6
RESPONSES TO FARMERS RESERVOIR AND IRRIGATION COMPANY COMMENTS US. DEPARTMENT OF THE ARMY RESPONSES TO THE FARMERS RESERVOIR AND IRRIGATION COMPANY COMMENTS REGARDING THE ROCKY MOUNTAIN ARSENAL OFFPOST PROPOSED PLAN APRIL 20, 1993
GENERAL COMMENT Comment No. I The companies divert water from First Creek on their decrees into tilhff the Burlington -O'brian canal which continues to Barr Lake or to the "Little Burlington" canal which delivers water directly to the shareholder's lands wi-thout entering Barr Lake. The offpost study area delineated in the Citizen's Summary refers only to consideration of the surface waters of Barr Lake and the Burlington -O'Brian canal. It does not appear as if the area served directly by the Little Burlington canal as been specifically identified as a study area. During the irrigation season, First Creek is diverted into the Little Burlington Canal. In relation to the amount of water diverted through the main Burlington Canal, flows in the Little Burlington canal are very small. The amount of dilution of First Creek flows in the Little Burlington Canal is quite small. At times, the only flow in the canal will be First Creek water- -undiluted by any other flows. Tle Little Burlington canal provides irrigation water for a significant amount (approximately 10,000 total acres) of vegetables and other crops in the Burlington area. It does not appear whether this direct and undiluted use of First Creek water for vegetable irrigation his been adequately considered. From the exposure zone mapping and exposure pathway analysis presented in the plan synopsis, it does not appear that interception and transport by the Little Burlington canal system has been adequately assessed. Resoonse Although Little Burlington Canal was not specifically evaluated for the Endangerment Assess- ment/Feasibility Study (EA/FS). the U.S. Department of the Army (Army) believes that all potential impacts that may result from the direct and undiluted use of First Creek water in Little Burlington Canal, especially for irrigation purposes, are addressed by the EA. Generally, the concentrations of constituents detected in First Creek surface water are lower than the concentra- tions detected in groundwater. (Arsenic is an exception, however, the arsenic levels may be attributed to naturally occurring sources.) Also. samples taken from the Little Burlington Canal indicate that RMA contaminants. when detected. are at lower concentrations than those found in First Creek. Therefore, the potential risks resulting from use of surface water are less than the potential risks resulting from use of groundwater. The EA quantitatively evaluated the uptake of constituents by vegetables irrigated with groundwater and/or surface water. For study zones IA, IC, and 6, the EA assumed irrigation water was primarily surface water (more than 92 percent). For zones I B. 2. 3. 4, and 5. the EA assumed shallow groundwater provided more than 90 percent of the irrigation water. On the basis of the trr i1t2t ton /plant uptake modeling effort, the lowest estimated concentrations of constituents in %eget3bles occurred in the zones irrigated primarily with surface water. The plant uptake model and exposure equations used very conservative or cautious assumptions; therefore, it is highl% unlikel%- that the potential plant concentrations and associated risks were underestimated. The Army believes, on the basis of the findings of the EA, that any Rocky Mountain Arsenal (RMA i-rel2ted constituents that may be transported to Little Burlington Canal via First Creek do not pose a health threat to humans and the environment.
Comment No. 2 Water from Barr Lake presently forms a portion of the physical municipal supply for the City of Brighton. Use of Barr Lake for potable municipal water purposes is anticipated to significantly increase in response to the new airport and related urbanization. The Barr Lake "plan" to integrate
9SU24A.enc I Barr Lake into a metropolitan water use system has gained recognition from the State of Colorado as one of the primary municipal water supply plans which can provide for increasing demands into the next century. Any discharge into First Creek or any groundwater which is otherwise intercepted by the Burlington ditch system must take into account the existing and proposed future domestic water uses. It is not apparent whether the domestic water quality requirements have been adequately considered in the remediation plan. Response Based on existing monitoring data, the concentrations of constituents (RMA or from other sources) in Barr Lake are not statistically elevated above background. The low concentration of constituents indicates that any potential health risk from the surface water pathway would be very small compared to other possible pathways of exposure (e.g., domestic use of groundwater). EPA risk assessment guidance allows for the elimination of pathways of exposure for quantitative risk evaluation if the potential risks associated with the pathway are likely to be very small. Addition- ally, it is anticipated that any contribution of contaminants to First Creek and ultimately to Barr Lake from RMA-related sources will be decreased because of the operation of the groundwater intercept and treatment systems. Comment No. 3 Reference is made to identification of various constituents in soils and groundwater. The offpost study area identification referred only to surface waters in Barr Lake (in which some RMA substances were found). Sediment accumulation in the Burlington Canal and Barr Lake does not appear to have been sufficiently considered. No quantification of the metals (arsenic and manganese) appears in the Citizen's Summary. The experience of the company in one of its other lakes (Standley lake) with regard to these metals may be applicable to Barr. In Standley lake, seasonal variations in the dissolved oxygen levels of the lake has resulted in re- solution of metals from the bottom sediments by a factor of more than 10 to 1. The impact of metals transported to the lake sediment may thus vary with time, season and eutrophic conditions. no consideration of these conditions appears in the plan.
Response Because of the historic input of constituents from other sources (e.g., Denver sewage effluent and agricultural runoff) into Barr Lake and ultimately into the lake sediment, it is nearly impossible to differentiate the percent contribution from RMA. Inorganic constituents, such as arsenic and manganese, complicate the issue further because these constituents also occur naturally-, the levels found in Barr Lake may be unrelated to RMA activities. The Army agrees that physical, chemical. and biological conditions present at any given moment may influence the distribution of metals in sediments and in surface water. However, the EA evaluated constituent concentrations on the basis of available sediment and surface-water analytical data and showed that the concentrations of constituents in Barr Lake were not signifi- cantly elevated above background concentrations. Comment No. 4 Various of the substances identified appear to be persistent or are bio- accumulated. There does not appear to have been any consideration of these issues as applied to the Barr Lake sediments in the offpost study plan.
930424A.enc 2 Resiponse The concentrations of the persistent and bioaccumulative constituents found in the sediment of Barr Like are below background concentrations. The EA evaluated the potential impact of constituents found in First Creek sediment (elevated above background) on human health and the environment. The findings of the EA indicated that even under this "worst case scenario" in First Creek (as compared to the potential risk posed by lower level constituents in Barr Lake), the contribution from the sediment to overall risk was very small, even for ecological receptors. Conclusion These comments have been submitted to insure that the present and future uses of Barr Lake, the Burlington Canal and waters transported through the system have been adequately considered. Various of these uses do not appear to have been considered in the existing plan. The companies do not have the technical or financial resources to adequately assess the past and future impact of contamination into and through the companies' systems. The companies' irrigation system is the recipient of all First Creek flows, as well as groundwater migration to the creeks and the canals themselves. As such the companies believe that at a minimum an ongoing water and sediment monitoring program is required to adequately assess past contamination and the efficacy of the proposed remediation. Until continued assessment of present conditions, taking into account all existing and proposed uses of the waters in the companies' system, has been undertaken delineation of the companies specific concerns cannot be made. Resvonse The Army is committed to an ongoing surface-water and groundwater monitoring program to ensure that the preferred alternative continues to meet the remedial action goals and to ensure the protection of human health and the environment. The Army would be glad to discuss the monitoring program with the Farmers Reservoir and irrigation Company (FRICO) in the future.
930424A.enc 3 Office of the Program Manager
Mr. Albert F. Sack President Farmers Reservoir and h-rigation Company 80 South 27th Avenue Brighton, Colorado 80229-1220
Dear Mr. Sack:
Enclosed are responses to your comments on the Offpost Proposed Plan for the Rocky Mountain Arsenal. The Army appreciates the large number of comments submitted on the Offpost Proposed Plan. I hope these responses increase your understanding of the Offpost cleanup.
Also enclosed is information your group requested at a meeting held with the Army on May 18, 1993.
If you have any further questions please contact Mr. Tim Kilgannon of my staff at 289-0201.
Sincerely,
Eugene H. Bishop Colonel, U.S. Army Program Manager
Enclosure Copies Furnished:
Captain Jonathan Potter, Litigation Attorney, Rocky Mountain Arsenal Building ill, Commerce City, Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of justice, 999-18th Street, Suite 501, North Tower, Denver, Colorado 80202 Document Tracking Center, ANfXRM-IDT, Room 132, Building ill, Rocky Mountain Arsenal, Commerce City, Colorado 80022 Appendix A-7
RESPONSES TO ENVIRONMENTAL ACTION GROUP COMMENTS RESPONSES TO SIERRA CLUB COMMENTS U.S. DEPARTMENT OF THE ARMY RESPONSES TO SIERRA CLUB COMMENTS REGARDING THE ROCKY MOUNTAIN ARSENAL OFFPOST PROPOSED PLAN RECEIVED JUNE 21, 1993
Comment A - Air auality,
1. Why wasn't air quality addressed more specifically? We are particularly concerned about the reference to the widening of 96th Ave. which would increase traffic, air current flow from the location of the SQI on the Arsenal, and increased airport activity following the opening of the new airport. The only reference we have seen in the study to air is the inhalation of particulates from soil and dust.
2. Ref. Vol.1, ES-3: How can it be stated that air exposure to chemicals of concern does not contribute to human exposure to these chemicals? Even if the concentrations are very low, it is not accurate to say that exposure does not contribute even slightly to increasing the total doses of chemicals to which residents of the offpost area are exposed.
3. When considering total solid Particulates (TSP) in air, the Plan states that concentrations at the RMA boundaries are lower that those found in metro Denver's air, and that metals are proportional to the same. Again, we are concerned that the activation of the SQI and the possibility of the widening of the road along the northern border of RMA will increase the TSP above the levels in metro Denver.
Response A I
Air emissions from the submerged quench incinerator (SQI) have been addressed as part of the SQI risk assessment and were determined to be within federal and state health guidelines. Potential air emissions resulting from widening 96th Avenue will be addressed by the appropriate regulatory agencies when that construction activity occurs.
Response A2:
The Rocky Mountain Arsenal (RMA) Comprehensive Air Quality Data Assessment Report by R.L. Stollar and others, 1990, presented data that indicated air quality within the Offpost Operable Unit (OU) was not impacted by contaminants related to RMA. Additional information is presented in the "Nature and Extent* subsection of Volume I of the Final Offpost Endangerment Assessment/Feasibility Study report. The evaluation of exposure to dusts presented in Appendix B of the Endangerment Assessment (EA) indicates that the potential exposures through inhalation of chemicals in dust are much less than exposures that could be received through other routes. The Risk Assessment Guidanc.! for Superfund allows for the elimination of a route of exposure if the contribution to exposure from that route is small compared to other routes.
Resr)onse A3:
See Response Al above.
930425A.ene Comment B - Chemicali of Concern:
1. We question the validity of 4 of the twelve background sites used in the study as being agricultural areas. Although these sites would have increased levels of pesticides present from crop applications, how does this site relate to what a residential area concentration of Dieldrin should be, for example? We feel that these sites may be biasing the background reference data to appear higher in chemical concentrations. than would normally be present without agricultural practices.
2. When analyzing the degradation charts for Dieldrin and Aldrin in zones 3 and 4, it is evident that these COC's will not be down to *background* levels within their boundaries for 25 and 15 years respectively. We would like to see a moratorium on development in these zones for the amount of time it would take to achieve the background levels for these COC's.
3. Ref. Vol. 2053: It wps stated here that the COCs are diluted 130:1 after O'Brian Canal. this would seem to indicate that the authors feel the "solution to pollution is dilution." We are supposed to be cleaning things up here, not dilution the problem. The COC's are still present in relative quantities, particularly in the sediments.
Response B I:
Generally, the concentration of dieldrin would be- lower in residential areas compared to agricul- tural areas; however, it is impossible to make a definitive statement without knowing anything about the residential area and whether historical domestic applications of dieldrin occurred. The soil samples collected from the background sites in the predominately agricultural area did not bias the pesticide reference data. Table 1.3.3-1 (Volume 11, Section 1.0 of the EA) shows that soil samples collected within the designated locations where the highest concentrations of RMA- related chemicals occur, or are expected to occur. had pesticide detections that were significantly elevated above the background soil samples, except for isodrin. All of the pesticides were evaluated in the risk assessment. including isodrin. Additionally, the risk assessment estimated risk on the basis of total risk rather than incremental risk (i.e., the Army did not subtract background residue contributions from the computation of exposure concentrations).
Response B2
The estimated potential risks associated with the soil in zones 3 and 4 are presented in the Final Offpost EA report and are within the acceptable risk range as defined by U.S. Environmental Protection Agency (EPA). Based on this evaluation. potential risks due to contamination should not limit rural residents or commercial /industrial development in these areas, although the Army is not aware of any plans for such development at this time.
Response B3
The reference to dilution of contaminants in surf3ce -ater flowing from First Creek into O'Brian Canal is not made in the context of remediation. It Is simply a statement of fact. The Army evaluated the potential risks associated with the contaminant concentrations in First Creek without regard to potential dilution for both human and animal receptors and showed the overall risks to be very small.
9UM25A.enc 2 Comment C - Water
1. Since the proposed clean-up for the Off-Post area is currently planned for groundwater only at the plume peripheries, but since readings for certain COC's have been found beyond where the original plume borders had been determined, we cannot support option N-4 of the Plan. We would prefer to see option N-5 enacted.
2. Ref. Vol 2-1-6: it states in reference to groundwater contamination that "inorganic chemical background concentrations are substantially different (and generally higher) in the Arapaho Formation when compared to the alluvium and upper Denver." We are concerned that this matter is not being addressed.
In addition we have been made aware that some wells on the other side of the Platte have yielded traces of certain COCs, and that the South Platte may not be acting as the hydrological barrier that it once was thought to be. Has this been considered in the clean-up effort and how will it be addressed?
3. Ref. Vol. 2, Table 1.3.2-7" In analyzing the sediment samples from Barr Lake, only 5 samples were used. We do not consider this to be a representative sample for the lake. Perhaps more sampling is necessary to adequately evaluate lake contamination.
4. Ref. Vol. 2, 1-19- Sediments form First Creek were poorly studied. Only 2 samples were listed for the reference data, while I I samples were collected for RMA-tainted samples. According to proper risk assessment protocol, an n=3 is the minimum number acceptable for samples. An n=2 is not valid for accurate statistical analysis.
Because one of the two reference samples had high levels of several COC's, the background level is high, therefore leading RMA samples to appear statistically insignificant from controls. There was reference to "other data" which was used in evaluating the samples. but no mention was made as to what it was. Consequently, we believe more sediment samples are required from First Creek to obtain an adequate reference database.
Also, an assumption has been made that metals are not COC's in First Creek based on the background data. We think that this assumption was inappropriate since the reference samplinC was not complete.
5. Ref. Vol. 2-2-53: In reference to groundwater contamination by chemicals, the study states that 'hydrophobic chemicals are absorbed by aquifer materials". Please clarify which materials COC*s are absorbed by and where they deposit to?
Can you also clarify the following statements:
aliphatic COC's undergo dechlorination under anaerobic conditions" What anaerobic conditions? What is the relevance of this statement?
930425A.enc 3 Maromatic COC's (i.e. benzene, etc.) are readily biodegraded under aerobic conditions". However, for aliphatic chemicals an anaerobic degradation was stated. Which condition prevails? What are the degradative products which are referred to ...phenols, quiriones, etc.? Which may be potentially more toxic?
6. We would like to see a surface water monitoring program established in the Off- Post area including:
- South Platte River - O'Brian Canal - Burlington Canal - Barr Lake - First Creek - Second Creek - Fulton Ditch.
Response C I
The Commenter has incorrectly stated the Army's rationale for elimination of Alternatives N-5 of and N-6. As presented in the Final Offpost EA/FS report Volume VI, Section 4.2.1, Screening Alternatives - North Plume Group, effectivenessý implementability, and cost criteria were explicitly evaluated consistent with the requirements of the National Oil and Hazardous Sub- stances Pollution Contingency (NCP). In this section of the EA/FS, it was concluded that Alternatives N-4, N-5, and N-6 afford the best reduction in toxicity, mobility, and volume, the best long-term protection, and the best compliance with remediation goals. Alternative N-6 was screened out at this point on the basis of similar performance in comparison with Alternative N-5 of with respect to reduction in toxicity, mobility. and volume, yet it afforded no benefit in terms remediation timeframe (10 to 20 vears) and at higher cost.
The Army selected Alternative N-4 instead of Alternative N-5 primarily because Alternative N-4 uses actual operating data as a basis for system modifications, if necessary. This is considered to be more effective than expanding the system based on more speculative modeling data.
The Army is committed to efficient operation of the Offpost Groundwater Intercept and Treatment System and will evaluate operating data to assess the need for system modification. Similar to the onpost boundary treatment systems, at is difficult to assess whether the installation of additional wells will provide more efficient oper3tion without collecting full-scale operating data for the Offpost Groundwater Intercept and Treatment System. The Army has included an intensive monitoring component as part of the preferred alternative, Alternative N-4, in the Proposed Plan. This intensive monitoring progr3m will allow the collection and subsequent interpretation of performance data for the full-scale operation of both the Offpost Groundwater Intercept and Treatment System and the onpost boundary systems. The data will be used to assess the need for any improvement to the systems and will provide increased accuracy in assessing contaminant cleanup. Acquisition of this operational data is preferable to adding extraction wells and recharge trenches without the benefit of operational data, because additional data are required to assess the necessity and placement of any additional extraction wells or trenches. If operational data supports the conclusion that the cleanup timeframe can be shortened without a significant increase in long-term costs, modifications to Alternative N-4 will be implemented. By taking this
9NM25A.ene 4 approach, improvements to the system will be more effective than improvements made based on computer modeling dam.
The selected remedy does notaddress groundwater only at the periphery of the plume. The Offpost Groundwater Intercept and Treatment System is located in the middle of the North Plume Group in the area of highest concentration.
For additional discussion, see response to State comment No. 2a in Appendix A-3 of the ROD.
Response C2
The background concentrations of certain inorganic compounds in the Arapahoe Formation are naturally occurring and are not addressed by the offpost clean up.
As defined by the Federal Facility Agreement (FFA), the areas requiring remediation.are those areas where concentrations of contaminants exceed the remediation goals. These remediation goals were developed to be protective to both human and ecological receptors and are within the acceptable risk range defined by EPA. The diisopropyl methylphosphonate (DIMP) detections west of the South Platte River are approximately 100 times less than the concentration recom- mended by EPA to be protective of human health. Continued groundwater monitoring will ensure that all areas will not exceed the remediation goals established to be protective of human health.
Response C3
Chemicals of concern in the canals were not present above background concentrations in the sediments of Barr Lake. Additionally, the absence of elevated concentrations in Barr Lake surface water indicate that sediments are unlikely to be contaminated. Sampling locations for Barr Lake sediments included locations near the inlet to Barr Lake, expected to have the highest sediment concentrations.
The Army acknowledged that intensive statistical analysis of the sediment at Barr Lake was hampered by the small sample size; however, on the basis on the sampling locations, the Army contends that the samples are representative of sediment at Barr Lake. Additional sampling is not warranted.
Response C4
The ArmN indicated that the reference data set was not sufficient to adequately address whether First Creek sediment was elevated for chlorinated hydrocarbon pesticides; therefore, as indicated, other criteria %ere used. These 'other criteria" are specified in the EA and included the detection frequency of the constituent in First Creek sediment, status of the constituent as a surface-water chemical of concern (COQ, and the organic partition coefficient for the constituent. The assumption -- as made that if a constituent concentration was elevated in the surface water, it would also be eievated in the sediment. Although a statistical comparison of the chlorinated hydrocarbon pesticides in First Creek sediment compared to background was not possible, all detected pesticides in the sediment were e%aluated in the risk assessment (see Table 2.4.2.6-9 in the Final Offpost EA).
Although the background (reference) dam set is small, the concentrations of metals present in the First Creek sediment samples (n=1 1) are low by any standard and are unlikely to pose an adverse effect to human and ecological receptors.
930425A.ene 5 Resnonse C5_ to clay The hydrophobic COCs, such as the chlorinated hydrocarbon pesticides, may be adsorbed mobile; particles and organic matter present in the aquifer. These particles are not likely to be thus significant desorption is unlikely to occur. of the Anaerobic conditions indicate a lack of oxygen. Such conditions may be present in portions saturated areas of an aquifer and may be ideal conditions for the biological transformation (i.e., biodegradation) of some chlorinated hydrocarbon pesticides by anaerobic microorganisms. or Aerobic conditions may be present in the unsaturated zones of an aquifer. Either aerobic or anaerobic conditions may be present at any given time. The type of biotransformation (aerobic nature anaerobic) depends on the type of microbial population present in the aquifer as well as the of the chemical substrate (aliphatic or aromatic) and the presence of any microbial nutrients. usual Although some degradation products may be more toxic than the parent compound, the and condition is to produce less toxic and more soluble products. Most of the products (toxic and nontoxic), if present above detection levels are measured using standard analytical methods would have been included in the risk assessment.
Response C6
A surface-water monitoring program is a component of the selected remedy in the Record of Decision (ROD). The specifics of the program will be developed after the ROD is finalized.
Comment D - Soil:
1. Ref. Vol. 2-1-21: Regarding surficial soil, comparison was made between RMA- tainted samples and regional reference data instead of reference data obtained at the Off -Post sites. We cannot understand how rules can be changed in the middle of the game. As such, we believe that comparisons should be made between all RMA-tainted samples and reference data from the Off-Post sites. A comparison of RMA-tainted data for copper. lead and zinc would have been statistically elevated compared to the reference data. This is not acceptable, and we would like the surficial soil data re-evaluated.
Z. Ref. Vol. 2-2-49 and 2-2-74: Why haven't the vegetables been analyzed for COC's? Because the produce is grown in soil on the Off -Post area and irrigated with groundwater contamin3ted with COCs. it would seem logical to sample the vegetables grown there. They are a relevant source of exposure for humans inhabiting the Off-Post area 13 well as for local residents purchasing the goods.
3. We are concerned about localized soil contamination hot spots in the Off-Post area which we don't see being addressed b% any of the clean-up proposals. We would like these areas Identified to the IOC31 residents and the contamination addressed.
Response DI
The extension of the background data set to include regional data is appropriate and allows for a more realistic anaINsis of the significance of site-relved metal concentrations. There can be tremendous variability in metal concentration as a result of natural geologic phenomena at a site, particularly a site the size of the Offpost Studv Area. Thus. it is important to evaluate site data with all available appropriate information The 'rules' did not change. Reference to Shacklette
930425A.enc 6 and Boemgen's soil data, as well as other soil databases, is common accepted practice in risk assessment.
Rest)onse D2
The Army recognizes the value of actual site-specific data when performing a risk assessment. Vegetables were not analyzed because no clear guidance exists on which kinds of plants are the most appropriate and because of seasonal availability during the scheduled soil sampling events. The Army's modeling approach uses conservative input parameters to predict potential plant tissue concentrations; thus, it is highly likely that potential risks associated with vegetable ingestion by local residents have been overestimated.
Response D3
The estimated risks associated with the areas of elevated pesticide concentrations in soil are within the acceptable risk range as established by the EPA. However, particularly with regard to the distribution of pesticides, it is apparent that localized areas of higher concentrations may not be attributable to simple windblown erosion from onpost soil. Because of the widespread use of pesticides in agricultural practices, pesticide residues are widespread and are found in nearly all soil samples in the offpost area. The general nature of windblown soil indicates that localized offpost areas of high soil pesticide concentrations are unlikely. Intentional pesticide application is believed to be at least partly responsible for the high concentrations of pesticides in certain soil areas.
However, the estimated risks (approximately 5 x 10') associated with these higher concentrations of pesticides found offpost are well within the EPA health guidelines.
Comment E - Land Usage:
1. Have the Army and Shell been communicating with Commerce City and the Adams County Board of Commissioners with regards to master plans and future zoning requirements for the Off-Post area? We are particularly concerned about zones 2, 3, and 4.
Response E I
As discussed in Volume 11, Section 2.2.2 of the EA. master plans, future use forecasts, and zoning information from both Commerce City and Adams County were utilized in establishing the reasonable future land use for the Offpost Study Area.
Comment F - Testinp, Procedures:
1. Ref. Vol. 2-2-74: Why are samples form agricultural products considered insufficient for exposure determinations of eggs, meat and milk? When evaluation sediment samples in /first Creek. an n-2 for control samples was considered adequate.
2. Ref. Vol. 2-2-76: Why --as modeling conducted for vegetable exposure? Wouldn't it have been much more relevant to sample actual produce? We don't understand why so much time and money was wasted modeling egg, meat and vegetable contamination when samples were readily available and would have been
93G425A.enc 7 more reliable. Vol. 2-2-85 indicated the limited monitoring data showed higher Dieldrin levels than the model's predicted value for meat and eggs.
3. Ref. Vol. 2-2-90: Why is age 0-30 considered a lifetime risk? We realize that 30 years is considered average for the U-S. due to population movement statistics. However, much of the Adams County area in question his a very stable population which often resides on a site for a lifetime. Many residents have already lived with high exposure rates for over 40 years and may live in this area for another 30 years. We feel that the risk values would change if residency were considered for a longer time.
4. Ref. Vol. 2-2-90: Please justify how and increased length of lifetime exposure would result in a reduced estimate of COC intake. How is it presumed that soil exposure and dairy product consumption would be lower for an adolescent than an adult? Anyone who has observed, or been, a teenager can attest to the fact that they play a variety of sports in the dirt, and will drink quantities of milk.
5. Relating to the risk management decision by the Army to use I in 2000 as the acceptable cancer risk, the Sierra Club feels that this is unacceptable. We feel that the clean-up should be to I in 1,000,000 as set by the EPA.
Response Fl
There is a greater potential for sample variability to occur when evaluating biological samples from a population rather than abiotic samples, such as sediment, from a limited area; therefore, a larger sample size is critical for meaningful interpretation of results. Each animal may have unique individual biological characteristics that are not readily apparent but that can influence chemical residue and toxicity evELLiations. It is difficult to address the influence of individual variability when an evaluation is limited to a very small data set.
Resz)onse F1_
See Response DZ above.
Response F!
A time sp2n of thirt% years is used as the estimated reasonable maximum lifetime exposure in accordince *ith risk assessment guidance documents from EPA. The basis of this value is that 90 out or 100 people will live 30 %ears or less at one residence. Hence, 30 years is the expected duration of potential exposure to cont3min3nts Although some people will exceed 30 years at one residence. the intent of this value is not to represent the absolute maximum number of years that would be represented bv a very limited number of people, but rather a value that encompasses the majority of people. EPA does not advocate utilizing absolute "worst-case" values in risk assess- ments. Use of the standard EPA default factors provides for more consistent risk assessments. A statistical evaluation of the Army's risk assessment exposure parameters actually indicated that the reasonable maximum exposure intake used by the Army approaches the 99th percentile, meeting and exceeding the definition for a reasonable maximum exposure (RME) estimate.
930-425A.enc 8 Response F4
The basis of the comment, the refeýence to page 11-2-90 of Volume II, is unclear. The risk assessment estimated potential risk on the basis of a reasonable maximum exposure as defined in the response to comment F3 for all populations evaluated.
As shown in Tables 2.4.3.2-1 and 2.4.3.2-la of the Final Offpost EA report, the intake rates for soil and water used in the risk assessment are greater for an adolescent/child than for an adult.
Response F5
The Army has closely followed EPA guidance and the National Oil and Hazardous Substances Pollution Contingency Plan (NCP) :egarding the use of the 10-4 risk threshold to assess whether remediation is necessary. Guidance states that if the cumulative cancer risk to an individual is less than 10', remedial action may not be warranted unless certain site-specific conditions exist. If remedial action is warranted, the 10' to 10' risk range must be achieved, with an initial prefer- ence for the 10' end. EPA guidance further states that the upper boundary of the risk range is not an absolute at I x 10", but rat.her, the acceptable risk range can extend to 5 x 10'. The cumulative offpost cancer risk is a maximum of 3 x 10'. which is within the acceptable risk range. The risk was calculated without operations of the Offpost Groundwater Intercept and Treatment System being considered.
In explaining the use of the point of departure, the EPA, in the preamble to the NCP, states
The use of 10' expresses EPA's preference for remedial actions that result in risks at the more protective end of the risk range. but does not reflect a presumption that the final remedial action should atmin such a risk level (55 Federal Register 8717).
The operation of the Offpost Groundwater Intercept and Treatment System reflects the Army's goal of further reducing the potential risk toward the 10' level.
Also, refer to the NCP and EPA risk assessment guidance documents, including Office of Solid Waste and Emergency Response Directive 9355.0-30 (Role of the Baseline Risk Assessment in Superfund Remedy Selection Decisions, April Z2, 1991). for clarification of this issue.
Comment Q Legal Reguirements-
1. Ref. Vol. 7-A-6: This ARAR analysis section states that the Federal Endangered Species Act, Migratory Bird Treaty Act, and Bald Eagle Protection Act apply to RMA. This section further states that remediation goals have been established for Off-Post contamination in conformity with the requirements of these three statutes. It further states that these remediation goals will be included as enforceable remediation levels in the proposed plan and record of decision. However, on page A-7. it is specifically stated that these three statutes are not ARAR's, but that they will be complied with for purposes of implementing an alternative remedy.
The Sierra Club is concerned that as the requirements of these three statutes regarding wildlife protection are not ARAR's, there may be some conflict between complying with these statutes and meeting the remediation goals for the Off-Post OU. Specifically, how will conflicts between the requirements of these three statutes and established ARAR's be resolved in the Off-Post remediation?
930425A.ene 9 Additionally, how can it be anticipated that remediation goals for the Off-Post OU can be achieved along with the requirements of those statutes for protection of wildlife?
The Sierra Club has concerns that there will be conflicts due to the presence of bald eagles in and around the Arsenal. To the greatest extent possible, the proposed plan and record of decision for the Off-Post OU should set forth how any potential conflicts are to be resolved to assure that remediation goals will be met, while at the same time protecting the wildlife included under the three statutes.
2. Ref. Vol. 7-A-20: Section 4.9 raises the question of protection of the wetlands in the remediation process. This section specifically states the requirements of Executive Order 11990 for protection of wetlands. This executive order directs federal agencies to take action to minimize the destruction, loss, or degradation of wetlands. The EA/FS states that because wetlands have been identified at the Arsenal, the requirements of this executive order may be potential location specific ARAR's
We are also concerned that there may be conflicts between wetlands protection and meeting required remediation levels. To the greatest extent possible, existing wetlands at the Arsenal should be protected in the Off-Post remediation process. Moreover, any contamination of wetlands areas should be remedied to a IxIO -6 localized risk of cancer.
3. Ref. Vol. 7-A-22: Section 4.12 deals with the Colorado Non-Game Endangered or Threatened Species Conservation Act. This section states that because remedial alternatives anticipated for the Off -Post OU are primarily sub-surface, and do not detail harassing, taking or possession of non-game species, these regulations are not applicable or relevant to the Off-Post OU.
While remedial alternatives may be primarily sub-surface in nature, they may never-the-less involve some harassment or destruction of non-game, endangered or threatened species. For this reason. the Colorado Non-Game Endangered or Threatened Species Conservation Act should apply in evaluating alternatives for the Off-Post OU.
Response Q I
The EA/FS (vol. 7. pg. A-6) does state that these three statutes apply to RMA and are applicable to the offpost remedy. In itself, the FFA requirement is not an ARAR because it is not a promulgated standard. However. the FFA requirement is legally binding on RMA activities. Language has been added to the ROD indicating that all appropriate actions will be taken during the operation of the preferred alternative to ensure compliance with these statutes.
Response G2
Protection of wetlands will be an integral part of !he operation of the preferred alternative. Presently, the Army does not anticipate any connict between operation of the Offpost Ground- water Intercept and Treatment System and protection of wetlands. If modifications to the Offpost Groundwater Intercept and Treatment System are necessary, protection of wetlands will be one of the issues evaluated.
930-425A.enc 10 Rest)onse G3
Colorado non-game endangered or threatened species will be protected during the operation and modification (if necessary) of the Offpost Groundwater Intercept and Treatment System.
Comment H
Our last question does not fall under a particular heading, but we would like you to answer it
Why can't the Army and Shell take the lead in developing new techniques for chemical clean-up using both the Off -Post area and RMA to do this? This would be an excellent money-making opportunity for Shell. It would also give both the Army and Shell Oil Company a more positive image in the eyes of the community and ultimately the nation.
Resnonse H
The Army and Shell Oil Company have evaluated a number of new and emerging technologies for use at RMA. Both bench- and pilot-scale tests of several technologies have been or will be conducted. The biggest problem, when evaluating new technologies, is their application to large scale clean up activities. If data becomes available indicating potential applications of new technology at RMA, the Army and Shell will evaluate and apply these technologies to the cleanup program at RMA.
930425A.enc Office of the Program Manager
Ms. Sandra A. Horrocks Subcommittee Chairperson Rocky Mountain Chapter, Sierra Club 1452 East Northcrest Drive Highlands Ranch, Colorado 80126
Dear Ms. Horrocks:
Thank you for providing comments on the Offpost Proposed Plan for Rocky Mountain Arsenal. The Army appreciates the large number of comments submitted on the Offpost Proposed Plan. I hope the enclosed responses increase your understanding of the offpost cleanup. Also included are the comments you submitted on the Offpost Proposed Plan for easier reference to the response.
If you have any further questions please contact Mr. Tim Kilgannon of my staff at (303) 289-0201.
Sincerely,
Eugene H. Bishop Colonel, U.S. Army Program Manager
Enclosure
Copies Furnished:
Captain Jonathan Potter, Litigation Attorney, Rocky Mountain Arsenal Building ill, Commerce City, Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of justice, 999-18th Street, Suite 501, North Tower, Denver. Colorado 80202 Document Tracking Center, AM]XR3,1-DDT, Room 132, Building 111, Rocky Mountain Arsenal, Commerce City, Colorado 80022 RESPONSES TO CMZENS AGAINST CONTAMINATION COMMENTS R OUR
CITIZENS AGAINST CONTAMINATION MAY I T 6 8 2 1" E. 61 ST PLACE 88 COMMERCE CrTY. COLORADO 80022 892-1158 E: ýjl FAX 8934LW
Jkm Haswg .S"yJaqutth May 13, 1993 J"n Mw&m Tom WC4mft Dwro Tnomm PU Thomm L40rift 71 A,"
Offpost Proposed Plan Comments Program Manager for the Rocky Mountain Arsenal Attn: AMXRM-PM/ Col. Eugene H. Bishop Bldg. 111 - RMA Commerce City, CO 80022-2180
Dear Col. Bishop;
Please accept this correspondence as our comments regarding the Offpost Proposed Plan by the Army:
" cancer risks - the excess cancer risks of approximately 3 in 10,000 or potential risks as high as 1 in 2,0000 are unacceptable. 1 in 1,000,000 is a number we can accept.
" we would like to see some soil cleanup planned in zone 2 and an articulated plan dealing with prevention of exposure to ground water in zones 2,3, and 4.
" we would like to see the residents who are exposed to DIMP in their wells hooked up to S. Adams County Water District and paid for by the Army and Shell.
" we would like the Army to comply with State regulations for surface water.
Thank you for this opportunity to comment on this plan.
Very truly yours,
CITIZENS AGAINST CONTAMINATION
Beth Gallegos cc: CDH EPA
TTM W U.S. DEPARTMENT OF THE ARMY RESPONSES TO CITIZENS AGAINST CONTAMINATION COMMENTS REGARDING THE ROCKY MOUNTAIN ARSENAL OFFPOST PROPOSED PLAN MAY 13,1993
GENER L COMMENTS
First bullet
The Army has closely followed U.S. Environmental Protection Agency (EPA) guidance and the National Oil and Hazardous Substances Pollution Contingency Plan (NCP) regarding the use of the 10-4 risk threshold to assess whether remediation is necessary. Guidance states that if the cumulative cancer risk to an individual is less than 10'. remedial action mav not be warranted unless certain site-specific conditions exist. If remedial action is warranted, the 10 -4 to 10 -6 risk range must be achieved, with an initial preference for the W, end. EPA guidance further states that the upper boundary of the risk range is not an absolute at I x 10,4, but rather, the acceptable risk range can extend to 5 x 10'. The cumulative offpost cancer risk is a maximum of 3 X 10', which is within the acceptable risk range.
In explaining the use of the point of departure. the EPA, in the preamble to the NCP, states
The use of 10' expresses EPA's preference for remedial actions that result in risks at the more protective end of the risk range, but does not reflect a presumption that the final remedial action should attain such a risk level (55 Federal Register 8718).
The operation of the Offpost Groundwater Intercept and Treatment System reflects the Army's goal of further reducing the potential risk toward the 10" level.
Second bullet
The Arm% used a large amount of onpost and offpost surface soil data to interpret Rocky Niountain Arsenal (RMA)-related soil contamination The combination of onpost and offpost data demonstr3teS that detected concentrations of contaminants offpost are attributable to windblown transport from RM A and to offpost acts%ities. including agricultural application of pesticides. Further. risks corresponding to offpost scial concentrations are within EPA's acceptable risk range. Therefore. remediation of offpost soil is not required
For additional discussion. see resronse to State comment No. 4 in Appendix A- I of this ROD.
Third bullet
The Army will continue to work with EPA. the Colorado Department of Health, and the Tri- County health Department in assessing the effecti%eness of one Offpost Groundwater Intercept and Treatment Svstem in e%'31uating the need for alternati%,e water supplies where remediation goals are exceeded.
21905.301020 - CR-08 0817120193 Fourth bullet
The Army has recognized all state laws and regulations that meet the applicable or relevant and appropriate requirement (ARAR) criteria under CERCLA and the NCP. After extensive discussion with all the parties, the Army has concluded that the Colorado Basic Standards for Groundwater (CBSGs) do not meet the ARARs criteria because of inconsistent application and ambiguous language. ARARs for the Offpost Operable Unit are based on federal drinking water standards and are protective of human health. In most cases, the treatment goals for the offpost and boundary treatment systems exceed the drinking water standards.
CERCLA expressly provides that state standards can be ARARs at a site. However, only those standards that are more stringent than federal requirements may be considered. In addition, the state standards must be promulgated (i.e., the requirement must be of general applicability and legally enforceable). Finally, the requirements must be identified in a timely manner by the particular state (40 Code of Federal Regulations [CFR] Section 300.400[gl4l).
The Army concludes that the CBSG interim organic standards are not ARARs for two reasons. First, the CERCLA exception in Section 3.11.5(C)(5)(a) applies to remedial actions authorized under CERCLA that are more or less stringent than would be achieved by compliance with the statewide standards. As a result, the overall effect of the statewide standard and accompanying exceptions is a state regulation that is only sometimes more stringent than a federal requirement. CERCLA only considers state standards that are stricter at all times as potential ARARs. Therefore, by definition, the interim organic standards are not ARARs at Superfund sites.
Second, the CBSG interim organic standards cannot be ARARs because they are not generally applicable or legally enforceable. A requirement in CERCLA for state requirements to be ARARs is that they must be promulgated standards, which means they must be generally applicable and legally enforceable. Clearly, the interim organic standards do not meet this test when applied at CERCLA sites. By definition. the interim organic standards are applicable throughout the state, except at CERCLA, RCRA, and UST sites. In those instances, the relevance of the standards is determined by the remedial sites. It is hard to understand how the standard could be legally enforceable when the Commission added language specifically ensuring that the standards may or may not be met at CERCLA sites.
For additional discussion, see response to State comment No. 4 in Appendix A-3 of this ROD.
21905,301020 - CR-08 0817093093 ------
RESPONSES TO ARSENAL ACTION ALLIANCE COMMENTS US. DEPARTMENT OF THE ARMY RESPONSES TO ARSENAL ACTION ALLIANCE COMMENTS REGARDING THE ROCKY 14OUNTAIN ARSENAL OFFPOST PROPOSED PLAN JUNE 21, 1993
GENERAL COMMENTS
Comment I
The proposed plan for groundwater clean-up is completely inadequate.
The Army fails to propose a plan for the clean-up and/or replacement of domestic water supplies that are currently contaminated with by-products of chemical warfare agents, solvents and other Arsenal-related compounds which have been identified in over a hundred wells spanning miles at varying levels.
The boundary system plan in its current form will do nothing to suck up or treat the contaminant plume that has already spread for miles past the interceptor points.
Resnonse I
The proposed plan includes a requirement for providing alternate domestic water supplies at locations where domestic water currently contains contaminants above applicable relevant and appropriate drinking water standards. These standards have been established to be protective of human health. The Army will continue to monitor groundwater contaminant concentrations during cleanup activities and will provide an alternate domestic water supply for any locations identified in the future where RMA contaminants exceed groundwater cleanup standards.
As indicated in the proposed plan, the North Boundary Contaminant System is not designed to capture contamination that has migrated past the RMA north boundary. Capture and treatment of groundwater downgradient of the North Boundary Contaminant System is the basis for the construction and operation of the Offpost Groundwater Intercept and Treatment System. Additional monitoring wells have been installed in this area to help define the extent of contamination and to aid in monitoring the effectiveness of the treatment system. The Offpost Groundwater Intercept and Treatment System is designed to extract and treat groundwater in order to attain groundwater cleanup standards.
Comment 2
The proposed plan fails altogether to address soil contamination in the offpost area, with no plan to remove toxins in yards where children and pets play, and track contaminants to indoor living areas. Rest)onse 2
Remediation of soil is not necessary because the estimated risk from exposure pathways relating to soil is within EPA health guidelines. Extraction and treatment of offpost groundwater will reduce the total potential risk through all pathways toward the IxIO* level.
Comment 3
The plan fails to base its assessment of human health risks on actual conditions and the history of prior Arsenal-related exposures.
930435.enc I While the Army is aware that elevated rates of at least one cancer type were demonstrated in the population for a period of time studied, the Army and EPA have based the 'risk assessment* on projections that falsely assume a previously healthy population.
The Army ignores the fact that a significant number of offpost residents, especially in the Irondale area, were literally "gassed" by seven months of virtually uncontrolled toxic fumes including high levels of deadly Shell pesticides and other toxic Arsenal compounds during the Basin F excavation in 1988 and '89, causing significantly high levels of risk for cancers and other diseases, according to some independent medical experts.
The Army ignores the fact that human beings in some sectors of the offpost area already have elevated risk from Atsenal poisons, having consumed levels of TCE and other toxins exceeding federal health guidelines in their drinking water through South Adams County's Water system for years prior to charcoal filtration, and even at times since.
Response 3
The Army followed EPA guidance in the conduct of the risk assessment for the Offpost Study Area. These guidelines do not account for existing health conditions, which may or may not be present in a population. However, the EPA risk assessment procedures include sufficient safety factors to be protective for sensitive populations.
The risk assessment conducted for the Offpost Study Area does not, by definition, assess whether adverse health effects have occurred or will occur and cannot identify particular individuals likely to suffer health problems because of contamination at a site. The Agency for Toxic Substances and Disease Registry (ATSDR), in cooperation with the Colorado Department of Health, have ongoing epidemiological studies near RMA to address the occurrence of health effects and assess whether these effects may be attributable to exposure to contaminants from a hazardous waste site. To date, the health study completed by the Colorado Department of Health and ATSDR has given no proof of a cause-effect relationship between Arsenal contamination and health problems in the offpost area.
Questions regarding violation of federal drinking water standards by the South Adams County Water and Sanitation District (SACA'SD) should be addressed directly to SACWSD. The Army is not involved in the operation or mainten3nce or th2t facility.
CITIZEN RECOMMENDATIONS FOR TtiE U-S ARMY AND SHELL
Recommendation I
All domestic wells currently contamin3ted by DIMP, IMPA and/or any other Arsenal- related toxins. found at any level should immediately be replaced with an alternative source of water, to eliminate ;LU current routes of toxics exposure, including dermal exposure and steam inhalation %hile bathing and showering.
930436.enc 2 Response to Recommendation I
The Army will continue to work with the U.S. Environmental Protection Agency (EPA), the Colorado Department of Health, and the Tri-County Health Department in assessing the effec- tiveness of the Offpost Groundwater Intercept and Treatment System and in evaluating the need for alternative water supplies where cleanup standards are exceeded.
Recommendation 2
Cap all shallow groundwater wells, to prevent continuing migration of Arsenal poisons to the deeper aquifer, as was recommended by the US. Public Health Service in 1959, over 30 years ago.
Response to Recommendation 2
Well closure of offpost wells has been included as a component of the selected remedy. See Appendix C of the Record of Decision (ROD). Specifics, relating to the criteria for individual well closures, are being discussed with the EPA, Colorado Department of Health and Tri-county Health Department.
Recommendation 3
Install groundwater interceptor systems along the leading edge of the plume, to the west of the South Platte River, to the north near or above Brighton, and east where the plume has not been adequately characterized, to date.
Response to Recommendation 3
The Offpost Groundwater Intercept and Treatment System is located such that the groundwater will be tre.ated to meet or exceed the remediation goals established to be protective of human health. Diisopropyl methylphosphonate (DIMP) concentrations at the leading edge are approxi- matelN 100 times less than the concentration established by the EPA to be protective of hu an health. The National Oil and Hazardous Substance Pollution Contingency Plan (NCP) does not require cleanup to a concentration of zero.
Re-commend3tinn 4
Dei-elop a comprehensive contaminated soil removal and clean-up plan for any and all offpo-st areas (including areas to the east and elsewhere, not currently included in the offpcnt study area") where RMA chemicals -- including Shell's dieldren, aldrin, endrin and other poisons -- have been identified.
Resonnse to Rtcor.-mend3tion 4
Background sampling indicated that pesticides are present throughout the Offpost Study Area. Agricultur2l application of pesticides is a contributing source. Agricultural application of a registered pesticide is exempt from CERCLA. However, the risk associated with the dieldrin concentration in these hot spots do not exceed a lifetime cancer risk of 5 x 10', which is at the lower end of the acceptable risk range defined by the U.S. Environmental Protection Agency (EPA). Therefore, specific cleanup of these soil areas is not required. Cleanup of offpost groundwater will provide the greatest benefit of risk reduction.
930435.enc 3 Recommendation 5
Develop a plan that includes analysis for compounds in offpost soil and surface waters associated with the RMA's onsite haza dous waste incineration and mechanisms for clean- up of heavy metals, dioxins and other toxins released to offpost area yards, farms and/or businesses in conjunction with the Army's two-year incineration activities.
Response to Recommendation 5
Monitoring plans will be developed following completion of the ROD. See Response to Comment 4, regarding the Submerged Quench Incinerator, following the Offpost Proposed Plan Responses.
Recommendation 6
Postpone the wRecord of Decision' on the offpost clean-up until the State of Colorado enacts groundwater standards for currently unregulated, Arsenal-related toxic compounds, based on independent medical opinion without conflicts of interest with the Army or its agents. Once those standards are adopted, set clean-up levels that meet -- or preferably exceed -- the standard.
Resr)onse to Recommendation 6
The Army is not required to postpone the ROD in order to wait until a standard is promulgated. Flexibility is inherent in the Army's selected alternative, and if a standard changes and subse- quently applies to the offpost program, the selected alternative will be modified.
Health advisories developed for DIMP and isopropyl methylphosphonic acid (IMPA) by the EPA and its Office of Drinking Water represent an evaluation by independent organizations that have no conflict of interest with the Army.
Recommendation 7
Abandon risk assessment for the offpost based on *zones," and clean up all contaminated soil and water areas to the maximum extent considered safe for residential use, since there are no mechanisms in place whereby land uses are to be restricted on private property, and cannot be projected in perpetuity.
Response to Recommendation 7
The NCP does not assume that unrestricted residential use will be the overriding consideration in cleanup efforts. In fact, the NCP states that the amumption of residential use is not a requirement. only that future land use be evaluated Section 104(i) of Comprehensive Environ- mental Response, Compensation. and I labilit% Act (CERCLA) states that health risk assessments should evaluate the potential risk to human health posed by "individual sites," based on such site- specific factors as the "nature and extent or contamination. and the "existence of potential pathways of human exposure." Clearly. this 12ngu3ge indicates that the EPA recognizes that all areas of a site are not equal in terms of potential itsk. Because the guidelines for determining which areas require remediation are risk-b2wd. it is important and essential to establish exposure areas (e.g., zones) with differing chemical concentrations and potential exposure patterns. This allows identification of those areas that pose the greatest concern (by virtue of higher risk) and that will require remediation. In addition. Institutional Controls have been added to the ROD to further protect the public from potentially contaminated areas.
930435.enc 4 Recommendation 8
Amend the plan to reflect clean up standards that meet -- or preferably exceed -- the EPA's National Contingency Plan level of "acceptable" risks, which clearly states no more that I excess cancer per million is considered safe. The Army's plan to allow a level of I excess cancer per 10,000 is outrageous, inconsistent with Superfund clean-up levels at other sites around the country, and which we believe to be overt environmental discrimination, whereby the U.S. Army would intentionally subject citizens in predominantly low-income communities to dramatically higher risks of death from its cleanup actions alone, on top of already elevated risks due to previous water, air and soil contamination from the Arsenal.
Response to Recommendation 8
The Army has closely followed EPA guidance and the NCP regarding the use of the 10' risk threshold to assess whether remediation is necessary. Guidance states that if the cumulative cancer risk to an individual is less than 10-4, remedial action may not be warranted unless certain site-specific conditions exist. If remedial action is warranted, the 10-4 to 10'6 risk range must be achieved, with an initial preference for the 10'6 end. EPA guidance further states that the upper boundary of the risk range is not an absolute at I x 10-4, but rather, the acceptable risk range can extend to 5 x 10'. The cumulative off post cancer risk is a maximum of 3 x 10', which is within the acceptable risk range. This risk was calculated without considering operations of the Offpost Groundwater Intercept and Treatment System.
In explaining the use of the point of departure, the EPA, in the preamble to the NCP, states
The use of 10' expresses EPA*s preference for remedial actions that result in risks at the more protective end of the risk range, but does not reflect a presumption that the final remedial action should attain such a risk level (55 Feder-al Register 8718).
The operation of the Offpost Groundwater Intercept and Treatment System reflects the Army's goal of further reducing the potential risk toward the 10" level.
Additionally, the Army is followirg EPA regulations and does not practice environmental discrimination, as implied in the comment.
Recommendation 9
Abandon so-called "clean-up* plans that allow people to be exposed to known dangerous toxic compounds, in addition to an arra% of unknown hazards from the negligent actions at the Rocky Mountain Arsenal o%er the 12st half century, which continue to sacrifice public health, homeowners' investments. the en%ironment. and the viability of whole communities.
Resvonse to Recommendation 9
The Army will not abandon the cleanup plan identified in the Proposed Plan. The selected alternative for offpost cleanup will not be determined until the Final ROD is accepted by the U.S. EPA and issued (now scheduled for early 1994). The Army believes its preferred alternative will protect human health and the environment and benefit property values offpost.
930435.enc 5 Office of the Program Manager
Ms. Adrienne Anderson P.O. Box 512 1200 Madison Street Denver, CO 80206
Mrs. Bennie Muniz P.O. Box 261 Henderson, CO 80640
Mrs. Mary Daigle 8810 E. 88th Ave. #40 Henderson, CO 80640
Dear Madams:
Thank you for providing comments on the Offpost Proposed Plan for Rocky Mountain Arsenal. The Army appreciates the large number of comments submitted on the Offpost Proposed Plan. Also included are responses to comments you submitted on the Submerged Quench Incinerator (SQI). I hope these responses increase vour understanding of the SQI and offpost cleanup.
Please Contact Mr. Bill Thomas, Public Affairs Office, at (303) 289-0136 if you have any questions regarding the SQI and Mr. Tim Kilgannon at (303) 289-0201, if vou have any questions regarding the Offpost Proposed Plan.
Sincerely,
Eugene H. Bishop Colonel, U.S. Army Program Manager
Enclosure Copies Furnished:
Captain Jonathan Potter, Litigation Attorney, Rocky Mountain Arsenal Building ill, Commerce City, Colorado 80022 Mr. Bradley Bridgewater, U.S. Departeaent of justice, 999-18th Street, Suite 501, North Tower, Denver, Colorado 80202 Document Tracking Center, AMXRM-DDT, Room 132, Building ill, Rocky Mountain Arsenal, Commerce City, Colorado 80022 RESPONSES TO COLORADO PESTICIDE NETWORK COMMENTS mc C one T Don a
We support the N-5 cLeanup a Lternative because it wi LL give a more E -pectel P-ss---ure-c f -,r deveLoping the area because of the new Denver International. Airport necessitate giving attention to the cLeanup.
We wouLd Like the dieLdrin hot spots and other contaminated areas t be remediated. CERCLA estabLished a strict joint and several. LiabiLity S cheme. If other parties aLso contributed to the contamination, the cLeanu remedy is a contribution suit. we have not seen any evidence which wouLd P rove that the arsena L did not at Least contribute to the excess di eLdri n contamination.
DIMP shouLd be cLeared from ground and surface water to at Least 8 ,::t T L ivp'. -4 Alln - 6- e 1-00 kýqh because - different criteria are used to determine nutrient needs in human and te a n i ma Ls ; the average American diet (USDA 1977) does not even suppLy the recommended daiLy doses for nutrients; test animaLs were given extra suppLements to meet their nutrient. needs off oost dweLLers may not take any suoDLements. The 1990 mink study onLy solicits further questions about the impacts DIMP and sudden deaths of mink reLated to DIMP. The former mink study show 5 jdden deatm shouLd be given top consideration in considering DIMP toxicity
Submitted by,
:igeLa Medbery ýC' Colorado Pesticide Network c/o 2205 Meade Street Denver, CO 80211 v rwa- 3
'13 051 U.S. DEPARTMENT OF THE ARMY RESPONSES TO COLORADO PESTICIDE NETWORK COMMENTS REGARDING THE ROCKY MOUNTAIN ARSENAL OFFPOST PROPOSED PLAN JUNE 21, 1993
Resvonse to Comment No. I - Preference for Alternative N-5,
The Army selected Alternative N-4 rather than N-5 on the basis of the evaluation criteria specified by the National Oil and Hazardous Substances Pollution Contingency Plan (NCP) as described in the Record of Decision (ROD). The slightly shorter time frame for cleanup estimated for Alternative N-5 was not the overriding issue in the selection process. The Army believes that the immediate operation of the existing Offpost Groundwater Intercept and Treatment System with later evaluation (Alternative N-5) is preferable to incurring increased construction costs for Alternative N-5 based on results of computer modeling. After review of actual operational data (which includes an evaluation of the change in chemical concentrations in groundwater), if improvements or modifications to the existing system are necessary, they can be implemented more effectively. These improvements would be based on actual data and would therefore be more effective than Alternative N-5 based on computer modeling results.
For additional discussion, see response to State comment No. 2a in Appendix A-3 of the ROD.
Response to Comment No. 2 - Dieldrin Hot Spots.
Based on our evaluation, isolated areas of increased dieldrin concentration (i.e., hot spots) in offpost soil are not a result of transport from Rocky Mountain Arsenal. Windblown soil would be deposited in a more uniform pattern and would not result in a deposition of high concentrations of dieldrin in one area. Additionally, background sampling indicated that pesticides are present throughout the Offpost Study Area. Agricultural application of pesticides is a contributing source. Agricultural application of a registered pesticide is exempt from CERCLA. However, the risks associated with the dieldrin concentrations in these hot spots do not exceed a lifetime cancer risk of 5 x 10', which is at the lower end of the acceptable risk range defined by the U.S. Environmental Protection Agency (EPA). Therefore, specific cleanup of these soil areas is not required. Cleanup of offpost groundwater will provide the greatest benefit of risk reduction.
Resvonse to Comment No. 3 - DINIP Qe3nun Stand3rd and Studies
The Army is using the EPA's Health Advisory value for diisopropyl methylphosphonate (DIMP) of 600 parts per billion (ppb) to determine which areas of DIM P- contaminated groundwater require remediation. This value represents a determination concurred by many EPA scientists and toxicologists. As stated in the Operation and Maintenance Manual for the Offpost Groundwater Intercept and Treatment Svstem, the treatment system is designed such that the treated water contains no more than 10 ppb of DIMP. Because the treatment system is located in the area of highest groundwater contamination, treatment of the groundwater to a level of 10 ppb DIMP should have a significant impact on the regional DISIP concentrations.
Because humans and animals are different. their nutrient needs are also different. All EPA animal testing guidelines indicate that animals should be properly fed with a diet that includes the appropriate nutrients. Although the 3%,er3ge human diet may be lacking in some nutrients, there are no procedures currently being used by EPA or state agencies to specifically account for this. There are, however, a number of safety factors built into the determination of the health advisory that the EPA believes are sufficient to account for potential variation among human sensitivities.
930425C.enc The EPA has recommended that the mink DIMP study not be used for human health effect studies because of the high natural annual mortality in mink, the general lack of information on the mink, and uncertainties concerning the reievance of mink to human health assessment.
For additional discussion of the DIMP standard, see response to State comment No. 2d in Appendix A-3 of the ROD.
930425C.enc 2 Office of the Program Manager
Ms. Angela Medbery Colorado Pesticide Network 2205 Meade Street Denver, Colorado 80211
Dear Ms. Medbery:
Thank you for your comments on the Offpost Proposed Plan for Rocky Mountain Arsenal. The Armv appreciates the large number of comments submitted on the Offpost Proposed Plan. I 6pe the enclosed responses increase your understanding of the Offpost cleanup. Also included are the comments YOU submitted for easier reference to the Armys response.
If you have any further questions please contact Mr. Tim Kilgannon of my staff at (303) 289-0201.
Sincerely,
Eugene H. Bishop Colonel, U.S. Army Program Manager
Enclosure
Copies Furnished:
Captain Jonathan Potter, Litigation Attorney. Rocky Mountain Arsenal Building ill, Commerce City. Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of justice, 999-18th Street, Suite 501, North Tower, Denver. Colorado 80202 Document Tracking Center, AMXRM-IDT, Room 132, Building ill, Rocky Mountain Arsenal, Commerce City, Colorado 80022 RESPONSES TO ENVIRONMENTAL INFORMATION NETWORK COMMENTS U.S. DEPARTMENT OF THE ARMY RESPONSES TO ENVIRONMENTAL INFORMATION NETWORK COMMENTS REGARDING THE ROCKY MOUNTAIN ARSENAL OFFPOST PROPOSED PLAN
Comment I
The preferred option cites Barr Lake and Burlington Ditch as offpost study areas, yet it appears that a comprehensive characterization has not occurred as yet. Are there current plans for extensive sediments and sediment core samples to be done throughout these areas?
Response 1:
The Army believes that the sampling activities conducted at Barr Lake and Burlington Ditch have been sufficient to adequately characterize these areas and to evaluate the need for remediation. In addition, a surface-water monitoring program will be implemented as a component of the preferred alternative.
Comment 2:
Have sufficient 3-dimensional plume maps been generated to answer the following questions: have the plume heads been defined in such a manner that the locations are identified? Have the plume heads reached and dispersed in the local tributaries, canals, and lakes?
Respons- 2:
Through the combination of data collected from an extensive system of offpost and onpost monitoring wells and use of groundwater modeling techniques, the areal extent of Rocky Mountain Arsenal (RMA)-related contaminants is well-defined. As discussed in the Final Remedial Investigation report, contaminant detections in local tributaries, canals, and lakes are generally not above background levels.
Comment 3
The Ground%,ater monitoring alternative cited states the samples will be collected periodically. Will these be grab or composite samples? What exactly will be monitored? What are the target analytes' How long will it take to get results from this testing? How frequently will the samples be taken. and at what locations?
Respome 3
Specifics of the groundwater monitoring program to be implemented as part of the offpost selected remed% have not vet been developed. The Record of Decision (ROD) states that the monitoring plan will be developed following finalization of the ROD.
Comment 4
A site review will be conducted at least e,,er% five years according to the U.S. Army brochures. A site of this complexity and severe nature of contamination dictates a much more aggressive review time line. Everv 5 years therefore is not acceptable. This should be brought forward for further public discussion. Please explain why the Army feels that a 5 year parameter is sufficient.
930376.enc Response 4:
As stated in the Proposed Plan and the ROD, Section 121(c) of the Comprehensive Environmental Response, Liability, and Compensation Act (CERCLA) mandates that a formal site review be conducted at least every five years to assUTe that human health and the environment are Protected during and after remediation. However, informal reviews of the efficiency, effectiveness, and environmental impacts of the treatment systems will be a continuous process. A large part of these informal reviews will be an assessment of the groundwater and surface-water monitoring data - collected as part of the long-term monitoring program. These informal reviews will be performed as often as long-term monitoring is performed. Based on the information obtained during operation of the treatment systems, a formal review may be conducted sooner than five years following implementation of the remedy, but no later.
Comment 5:
Alternate Water Supply is cited as being provided if domestic wells are identified as containing concentrations that exceed remediation goals. Please specify exactly what those concentrations consist of, and whether they are protective of chronic exposures and synergistic accumulative uptake in small children, and pregnant women.
Response _;ý7
Remediation goals (i.e., cleanup standards) are listed in Table 7.1 of the ROD. Based on U.S. Environmental Protection Agency (EPA) guidance on risk assessment methodology, these concentrations are expected to be protective of adverse health effects for sensitive individuals and for chronic exposures.
Comment 6:
The RMA boundary containment systems may not be adequate systems for ground water recharge pump-and-treat containment if they are relying solely on carbon adsorption units for removal of organics only. Other contaminants at the RNIA include metals, which are not affected by carbon adsorption units. Other processes such as precipitation may be required to address this.
Response 6:
Concentrations of metals and other inorganics approaching the RMA boundaries were determined to meet all applicable groundwater standards , If ongoing groundwater monitoring results show that other chemicals are approaching the. RNIA boundaries above standards, the Army will revise the treatment systems as necessary.
930376.enc 2 Office of the Program Manager
Ms. Paula Elofson-Gardine Executive Director Environmental Information Network (EIN), Inc. P.O. Box 280087 Lakewood, CO 80228
Dear Ms. Elofson-Gardine:
Thank you for providing comments on the Offpost Proposed Plan for Rocky Mountain Arsenal. The Army appreciates the large number of comments submitted on the Offpost Proposed Plan. Also included are responses to comments you submitted on the Submerged Quench Incinerator (SQ1). I hope these responses increase your understanding of the SQI and offpost cleanup.
Please contact Mr. Bill Thomas, Public Affairs Office, at (303) 289-0136 if you have any questions regarding the SQ1. and Mr. Tim Kilgannon at (303) 289-0201, if you have any questions regarding the Offpost Proposed Plan.
Sincerely,
Eugene H. Bishop Colonel, U.S. Army Program Manager
Enclosure
Copies Furnished:
Captain Jonathan Potter, Litigation Attomey. Rocky Mountain Arsenal Building ill, Commerce City, Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of justice, 999-18th Street, Suite 501, North Tower, Denver. Colorado 80202 Document Tracking Center, AMXRNI-IDT. Room 132, Building 111, Rocky Mountain Arsenal, Commerce City, Colorado 80022 RESPONSES TO DENVER AUDUBON SOCIETY COMMENTS DENVER AUDUBON 24 SOCIETY to#&I 8751 E. Hampden Ave., Suite A-1 Denver, CO 80231 (303) 696-0877 21 June, 1993 Offpost Proposed Plan Comments Program Manager for Rocky Mountain Arsenal Attn: AMXRM-PM/ Col. Eugene H. Bishop Building Ill-RMA Commerce City, CO 80022-2180 Dear Sir:
We would like to endorse the recommendation from CDH that option N-5 be selected in preference to N-4, because it provides a more aggressive treatment . The tradeoff, by which both plans are estimated to cost the same, is for N-5 more immediate expenses for construction of wells and trenches, in place of more expense for intensive monitoring over two years indicated for N-4. The additional monitoring would provide data for improved modeling of groundwater movements. It would not of itself provide improvement in protection of the environment. on the other hand, N-5 would provide a more rapid reduction In concentrations of groundwater contaminants, which in our view would be a reassurance for environmental protection.
In support of this view, we would direct attention to the large uncertainties in any risk assessment. This is not to fault the methods used by the Army in its decision making. Nor are we taking issue with the reasoning for rejecting some insights on the possiblle impact of contaminants which are not at present fully supported by. experimental data. But in this instance we have a tradeoff which involves no change in estimated cost. This seems to be the logical time to give the benefit of the doubt to impacts of contaminants, which, while not "Proven", at least are considered believable by many qualified observers.
In rejecting CDH arguments concerning ecological risk characterization which might involve multiple chemical interactions as documented in a monograph by Calabrese, the Army said (VIII- p.60) "...because of its early investigational stages and lack of scientific concensus, acceptable quidellnes for use in ecological assessment are lacking." This no doubt is a compelling argument for the practice of risk assessment, but it does nothing to quiet the uneasiness of observers who find evidence of adverse impacts on blota, necessarily without being able to pinpoint the agents responsible. Again, we do not dispute the risk assessment, but accept it as a necessary though imperfect tool. Our argument in this instance is that with costs being equal, the more aggressive clean-up is more desirable.
The same considerations apply to surface runoff In First Creek. No attempt is being made to intercept and filter this water, because th7e concentrations are low, and the water is hydrologically interrelated with the ground water. However, higher concentrat-ions are episodic, and it would again seem desirable to favor a more aggressive- cleanup option.
PAXWWCW AECYC=PAflVV In justifying the selection of N-4 as the favored option, the Army observes (5.4.1.4) that "the potential for exposure in the timeframe is reduced by the Army committment to provide alternative water to any future identified ground water users." While this seems prudent, we are concerned that the uncertainties in ecological risk might be ignored.
The Army has emphasized that the 2-year Intensive monitoring proposed under option N-4 is needed for decision-making regarding potential Improvements to the treatment installations. They have not made clear the compelling need. On the other hand there seems to be clear justification for expecting more rapid cleanup for the treatment plans under N-5. The real tradeoff seems to be more accurate modeling for risk assessment as opposed to more aggressive removal of groundwater contaminants, which might not be optimal, but is sure to work.
Sincerely yours,
Frank Clough Pesticide Representative for Denver Audubon Conservation Committee c: Polly Reetz 7 C, U.S. DEPARTMENT OF THE ARMY RESPONSES TO DENVER AUDUBON SOCIETY COMMENTS REGARDING THE ROCKY MOUNTAIN ARSENAL OFFPOST PROPOSED PLAN JUNE 21, 1993
GENERAL COMMENTS
Comment 1: Selection of N-4 instead of N-5
As presented in the Final Offpost EA/FS report Volume VI, Section 4.2.1, Screening of Alterna- tives - North Plume Group, effectiveness, implementability, and cost criteria were explicitly evaluated consistent with the requirements of the NCP. In this section of the EA/FS, it was concluded that Alternatives N-4, N-5, and N-6 afford the best reduction in toxicity, mobility, and volume, the best long-term protection, and the best compliance with remediation goals. Alternative N-6 was screened out at this point on the basis of similar performance in comparison with Alternative N-5 with respect to reduction in toxicity, mobility, and volume, yet it afforded no benefit in terms of remediation timeframe (10 to 20 years) and at higher cost.
The Army selected Alternative N-4 instead of Alternative N-5 primarily because Alternative N-4 includes potential future modifications, if such modifications are found to be necessary based on actual operating data, to the Offpost Groundwater Intercept and Treatment System and because use of actual full-scale operating data is preferable to selecting additional components for the Off post Intercept and Treatment System using the more speculative modeling data (i.e., Alterna- tive N-5).
The Army is committed to efficient operation of the Offpost Groundwater Intercept and Treatment System and will evaluate operating data to assess the need for system modification. Similar to the onpost boundary treatment systems, it is difficult to assess whether the installation of additional wells will provide more efficient operation without collecting full-scale operating data for the Offpost Groundwater Intercept and Treatment System. The Army has included an intensive monitoring component as part of the preferred alternative, Alternative N-4, in the Proposed Plan. This intensive monitoring program will allow the collection and subsequent interpretation of performance data for the full-scale operation of both the Offpost Groundwater Intercept and Treatment Svstem and the onpost boundary systems. The data will be used to assess the need for an), improvement to the systems and will provide increased accuracy in assessing contaminant cleanup. Acquisition of this operational data is preferable to adding extraction wells and recharge trenches without the benefit of operational data, because additional data are required to assess the necessity and placement of any additional extraction wells or trenches. If operational data supports the conclusion that the cleanup timeframe can be shortened without a significant increase in long-term costs, modifications to Alternative N-4 will be implemented. By taking this approach, improvements to the system will be more effective than improvements made based on computer modeling data.
For additional discussion, see response to State comment No. 2a in Appendix A-3 of this ROD.
21905,301020 - CR-08 0817120193 Comment 2: Cleanup of Surface Water
Given that the following three factors point to continuing beneficial impacts to offpost water quality, the Army is committing to an ongoing surface water monitoring program to track the cleanup of offpost surface water. (1) remediation of groundwater should have a beneficial effect on offpost surface water quality, (2) contaminant concentrations are lower during storm event runoff periods (Surface Water Comprehensive Monitoring Program Annual Report for 1989 JR.L. Stollar & Associates, and others, 1990]), and (3) the Army has committed to closing the onpost sewage treatment plant, thus eliminating a possible source of contaminants in the First Creek surface water drainage.
The components of the offpost surface water monitoring program will be contained in a report to be completed following completion of the ROD. The ROD contains the Army commitment to both surface wateTand groundwater monitoring programs in the offpost area as a component of the selected remedy.
21905,301020 - CR-08 0817120193 RESPONSES TO WE THE PEOPLE COMMENTS U.S. DEPARTMENT OF THE ARMY RESPONSES TO WE THE PEOPLE COMMENTS REGARDING THE ROCKY MOUNTAIN ARSENAL OFFPOST PROPOSED PLAN
GENERAL COMMENTS
Comment 1:
The plan and its alternatives are based on suspect or manipulated data. This was evidenced at the April 28, 1993 public meeting by comments regarding DIMP levels in wells showing levels exceeding what is often broadly and publicly reported.
Resr)onse 1:
The Army has not based the selection of the preferred alternative on suspect DIMP data, nor has the Army engaged in manipulating DIMP data. If the commentor is referring to the State of Colorado's statement regarding levels of DIMP exceeding 600 ppb north (downgradient) of the Offpost Groundwater Intercept and Treatment System, the Army is aware of these data. A component of the preferred alterative involves installation of three new monitoring wells. Two new monitoring wells will be installed downgradient of the First Creek Pathway and one new monitoring well will be installed downgradient of the Northern Pathway. The purpose of the three new monitoring wells is to aid in assessing the extent of contamination downgradient of the Offpost Groundwater Intercept and Treatment System. Data collected from these wells and existing wells will be used to further define the extent of contamination greater than the cleanup goals in this area and assist in determining whether modifications to the Offpost Groundwater Intercept and Treatment System are necessary.
Comment 3:
The offpost plan and its alternatives are so inadequate in their remediation and ongoing monitoring of; water, soils, the air basin. existing and ongoing harm to the public health, offpost wild and domestic animal life; plus the very limited scope of the offpost area itself, that the only possibility is to start over.
Response 3:
The selection of the preferred alternative in the Record of Decision was based on the evaluation criteria established in the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). The results of the EA/FS indicated th3t groundwater is the major contributor to potential risks. Treatment of groundwater with the Offpost Groundwater Intercept and Treatment System will reduce the estimated risk toward the level of one excess cancer per one million people (I x 10-).
Part of the preferred alternative involves extensive monitoring of offpost groundwater conditions throughout the operation of the Offpost Groundwater Intercept and Treatment System. Results of the Comprehensive Air Monitoring Program for RMA indicated that the air quality is not a health concern in the offpost area. The results of the risk assessment conducted for the Offpost Study Area indicated that potential harm to wildlife is minimal, and that potential harm to domestic animals is nonexistent. However, the Army will continue to monitor offpost groundwater surface water, and soil as needed as part of the preferred alternative. The Agency for Toxic Substances and Disease Registry (ATSDR) and the Colorado Department of Health (CDH) have ongoing
930377.ene I epidemiological studies near RMA to evaluate the occurrence of health effects. The Army believes that the Offpost Study Area and the investigations conducted to date are not of "limited scope." The studies conducted for the offpost area have been done with the approval of the U.S. Environmental Protection Agency (EPA) and with review and comment by CDH. The Army does not intend to start over, rather, the Army intends to proceed with implementation of the preferred alternative so that potential offpost risks will be reduced.
SPECIFIC COMMENTS
Comment 1:
The offpost study area is too limited in scope to be meaningful. The following scope areas and the way they are addressed are inadequate in the proposed plan and its alternatives:
Comment lb: Soil monitoring and remediation is inadequate. The idea that other sources are responsible for the contamination of soils in the surrounding area is an unacceptable premise to make from any organizations that have openly, blatantly, willfully, and; who without any regard whatsoever for environmental, health, and social harms, freely polluted surrounding communities for 40 years. A soils remediation plan needs to be developed, and in such a way as to not create additional risk exposure to the environment and the public.
Response Ib:
The Army has adequately characterized the extent of contamination in the offpost soil. The Army has not stated that other sources are entirely responsible for the offpost soil contamination. However, particularly with regard to the distribution of pesticides, it is apparent that localized areas of higher concentrations may not be attributable to simple windblown erosion from onpost soil. Because of the widespread use of pesticides in agricultural practices, pesticide residues are widespread and are found in neatly all soil samples in the offpost area. The general nature of windblown soil indicates that localized off post areas of high soil pesticide concentrations are unlikely. Intentional pesticide application is believed to be at least partly responsible for the high concentrations of pesticides in certain soil areas.
However. the estimated risks (approximately 5 x 10-'S)associated with these higher concentrations of pesticides found offpost are well within the EPA health guidelines.
Comment I c-, The lack of establishing a thorough baseline health study of the affected areas and the deviation or lack of de-- iation from the health of unaffected areas. This must include the evaluation of hum3n. wildlife, and domestic animal populations.
Response lc-,
The baseline risk assessment performed for the Offpost study area is not based on knowledge or information regarding the current health st2tus of potentially exposed individuals. The risk assessment is based on estimating the current and potential future exposures. A comprehensive epidemiological study is not required by either CERCLA or the NCP. While this information may be useful, the EPA does not require it as pan of the risk assessment process or as a factor in the selection of the remedy. Rather, the EPA has consistently used the results of the site-specific risk
930377.enc 2 assessment as a basis for determination of the need for cleanup.
A risk assessment, like the one performed for the Offpost Operable Unit, is a scientific evaluation of the probability that adverse effects will occur if people, wildlife, or domestic animals are exposed to contaminants present at the site. The risk assessment considers the ways humans and animals may be exposed (pathways of exposure), the likelihood of adverse health effects, the expected types of health effects, and the toxicity of individual chemicals. A risk assessment does not, by definition, determine whether adverse health effects have occurred or Will Occur and cannot identify particular individuais likely to suffer health problems because of contamination at a site.
However, separate from the risk assessment process, the ATSDR in cooperation with CDH may conduct a health assessment and, on the basis of their findings, institute a full-scale epidemio- logical study to address the actual occurrence of health effects and determine if these effects may be attributable to exposure to contaminants from a hazardous waste site. The ATSDR and CDH have ongoing epidemiological studies near RMA.
Comment Id: The lack of ongoing monitoring of health harms; and provisions for harm(s) done or yet to be done to the health of human, wildlife and domestic (including pets, farm, and ranch) populations.
Response Id:
See response to comment I c above.
Comment If: In an information meeting at the Montbello library it was revealed that water coming back to the RMA from the Montbello area was contaminated. The assumption stated was, that this contamination was generated by industrial sources within the Montbello community. Once again, the idea that other sources are responsible for the contamination of water or soils in the surrounding area is an unacceptable premise to make from any organizations that have openly, blatantly, willfully, and, who without any regard whatsoever for environmental, health, and social harms, freely polluted surrounding communities for 40 years. An in-depth determination must be made to determine that this contamination is not from prior exposure to pollutants from RMA ground and air pathways to Montbello soils and water, and further if other Pollution generators are discovered that they and the appropriate commun3tv. authorities and governmental regulators be notified. Further, if the contaminants were possible products from RMA activities, with no present day generators then remediation and ongoing monitoring plans should be established.
Response If:
The commentor has misinterpreted the statement made at the informational meeting. Water does not "come back" to RMA from the Montbello area. Groundwater flow direction is from the south to the north. Groundwater contaminants present beneath RMA would therefore be transported to the north. If contaminated groundwater is identified at the southern boundary of RMA, the source of this contamination is most likely located south of RMA, perhaps within the Montbello area. The Army has not stated that other sources are responsible for the contamination. The Army is stating that in some areas, it is apparent that some contamination appears to have originated from sources other than RNIA activities. The Army is in full agreement with the statement that if the contaminants are possible products from RMA activities, remediation and
93037-i.enc 3 ongoing monitoring plans should be established. This is the purpose of the Remedial Investiga- tion, Endangerment Assessment/Feasibility Study (EA/FS), the Proposed Plan, and selection of the preferred alternative in the Record of Decision.
Comment 2:
The offpost study area is too limited in size to be meaningful. The following areas need to be added to the study area along with the pertinent scope that including them would necessitate:
Comment 2a: The entire western boundary of the RMA needs to be part of the plan even if there is another superfund site along part of it. Pollution was done to the whole, the plan needs to address in detail the whole.
Response 2a:
The entire western boundary of RMA was included initially in the evaluation of the offpost area. Soil and groundwater samples were collected and analyzed from the area included in the EPA Study Area. Concentrations of contaminants in this area do not exceed offpost cleanup goals. As defined in the Federal Facility Agreement, the offpost areas requiring cleanup are those areas where RMA-related chemical concentrations exceed EPA standards or cleanup goals. Conse- quently, this area was not included in further offpost studies. Additionally, the groundwater migration direction indicates that sources other than RMA are responsible for the contamination in this area. Because it is part of another study area, other parties are responsible for the cleanup.
Comment 2c- Include the communities of Montbello and Green Valley Ranch. They are downwind of RMA and therefore were exposed to definite pollution via air pathways. They mzy have also been exposed via heavy rains and blowing snow.
Response 2c:
The claim of "definite pollution via air pathwayso cannot be substantiated. Results of the Comprehensive Air Monitoring Program (CAMP) for RMA indicate that potential exposures at the boundaries of RMA through the air pathway are negligible, if not unmeasurable. However, the CAMP will monitor air qualivy at the RNIA boundaries as long as cleanup continues onpost.
Response 2d: Expand the northern boundaries to include leaching areas on both sides of the shown waterways and the area to and including the perimeter of Barr lake. Additionally, add the Brighton area water supply area for ongoing monitoring and a remediation contingency plan if plumes of pollution continue their creep towards their water suppl%
Response 2d:
The boundaries of the Offpost Study Area were defined to include those areas of groundwater known to contain RMA-related chemicals and surface water bodies that may be affected. The land adjacent to the streams was not shown to contain elevated concentrations of contaminants. Similarly, the land surrounding Barr Lake would not be expected to contain chemicals in concentrations exceeding other land areas Included in the Offpost Study Area. Therefore, the land adjacent to the waterways and Barr Lake were not included as part of the Offpost Study Area.
930377.enc 4 The Army has many groundwater monitoring wells downgradient of the Offpost Groundwater Intercept and Treatment System, including wells upgradient of the Brighton area water supply wells. The monitoring program implemented as part of the preferred alternative will adequately identify potential plume migration before reaching the Brighton water supply wells. If such migration is identified and is a threat to the safety of the drinking water, the Army will modify the offpost cleanup plan to protect the Brighton water supply wells.
Comment 2g: A minimum of 5 kilometers in all directions from each stack of the north plant and south plant.
Rest)onse 22:
Neither the North Plants or the South Plants are currently operating or involved in any manufact- uring processes. There are no emissions from the stacks at either location. RMA-related contamination has not been detected at locations other than north of the RMA boundary (the Offpost Study Area). Therefore, it is not appropriate to include a 5 kilometer 360-degree radius around the RMA onpost area as the Off post Study area.
Comment 3:
We would request that the Army respect the Colorado Department of Health's recommended Standard for DIMP in ground water at 8 ppb. Further the Army, Shell, its agents Holme Roberts and Owen, and the EPA should not further interfere with or lobby the Colorado Water Quality Commission (WQCC) to set a higher standard in order to benefit the RMA parties at the risk of Public Health and the ENVIRONMENT. We feel these activities undermine Public confidence in the WQCC and will dilute the sovereignty of the State of Colorado.
Response 3:
The Army did not interfere with or lobby the Colorado Water Quality Commission to set a higher standard for DIMP in groundwater. The Army has presented its position to the Commission as part of the public hearing process. The Army stated that in was in agreement with the EPA's position which has the support of many top-level scientists, both from within the EPA and other national organizations. The Army believes it is inappropriate to set a standard based on the opinions of one scientist when that opinion is not shared by the scientific peer group.
T'he Colorado Water Quality Control Commission recently set an 8 parts per billion standard for DINIP in groundwater. The Army is currently evaluating the applicability of this standard to the preferred alternative.
Comment 4:
In reviewing the various DIMP data and after talking with personnel from EPA and the State of Colorado we find it incomprehensible for the EPA to have not considered the Mink study with a great deal more importance than they did. Their assumptions on the controls seem to be greatly flawed and suspect. We feel there exists a significant difference of opinion between the State and the EPA. Therefore:
Comment 4a- DIMP only affected the area around the RMA. It does not exist anywhere else in the country, nor does it affect any other ongoing production activity. Since it is only a product of SERAN production which is not now or will be manufactured, no ongoing industry will be affected.
930377.enc 5 Rew oýns 4x
No specific comment or recommendation made.
Comment 4b: Humans using DIMP contaminated water wells are being exposed daily via direct and indirect Pathways and are therefore exposed to significant health risk.
Response 4b:
Based on the EPA health advisory for DIMP, which has been peer-reviewed by many nongovern- mental scientists, the results of the endangerment assessment indicate that the concentrations of DIMP in groundwater do not correspond to a significant health risk. However, treatment efficiency data for the Offpost Groundwater Intercept and Treatment System indicate that concentrations of DIMP in the treated groundwater are reduced to less than iO to 15 parts per billion on average, thereby reducing the potential risks from DIMP to an insignificant level.
Comment 4c: Further study and manipulation of the regulatory process should be no longer considered. Reasonable responsibility for providing a alternatives for water in the DIMP affected area should be undertaken by the Army as soon as possible.
Response 4c-
The Army has not manipulated the regulatory process. All investigative and interpretive efforts have been conducted in accordance with the NCP and with the cooperation and approval of the EPA. The Army has provided an alternative water supply to all residents where private well water exceeds the cleanup goals established in the Record of Decision. See response to Comment 3.
Comment 4d: Further the parties should step up to their responsibility to monitor and provide for health contingencies of affected people who have had Prolonged exposure to DIMP.
Response 4d:
The Army is not in the position to monitor the health of all people in the Offpost Study Area. The Army is committed to operation of the Offpost Groundwater Intercept and Treatment System to reduce the concentrations of ground-ater contaminants to meet or exceed the cleanup goals. As indicated in the response to comment Ic above. the ATSDR is currently conducting an epidemiological study of the health status of offpost residents.
Response 4e: No offpost plan or alternati%e is acceptable without providing for alternative water for DIMP affected wells.
Response 4e:
The Army continues to support and provide alternative water supplies to individuals where private drinking water wells contain concentrations of RMA-related contaminants above the EPA health guidelines. See response to Comment 3.
930377.enc 6 Comment 5:
Rationalizing which ARARs the Federal Government agencies and Shell are willing to live with is unacceptable. Standards set by the State of Colorado should unconditionally be followed (i.e. Chloroform). Also in that same spirit, the parties should conform to Colorado's Sunshine act and open up all proceedings without exception.
Response 5:
The Army has followed all applicable federal regulatory guidance for Superfund in determining which standards apply to the offpost cleanup effort. Neither CERCLA nor the NPL require that meetings between the Army, Shell, CDH, EPA, and contractors be open to the public. CERCLA, however, does provide for specific public involvement opportunities as part of the overall Superfund process. The Army has provided these opportunities to the public. Additionally, all documents relating to the offpost program are available for your review at the Joint Administra- tive Records Facility at the Security building at the west gate of RMA. Also, RMA's Technical Review Committee meeting monthly and is open to the public. You are welcome to call the RMA Public Affairs Office at 289-0136 for more information.
Comment 6:
Further planning and alternatives should be based on human health and animal health studies in place of risk assessments. Moreover the actual baseline health of the area should be established prior to determining possible risk exposure. Conventional risk assessments are not respected or believed by the public and, as we have found, most non -governmental professionals. These health studies must account for all health and reproductive risks, not just carcinogenic. We recognize that hazard quotient and hazard index were used, but this we view as risk art and definitely no risk science. Based on information that we believe, risk assessments have a very high degree of fallibility and are not in the least reassuring. We have often heard and seen it written that risk assessments can be made to say almost anything.
Resvonse 6:
See response to comment Ic regarding the establishment of baseline health. Many of the risk assessment procedures and methodologies recommended by the EPA were originally developed by nongovernmental professionals. The Army is legally bound to use EPA-approved procedures and to follo- the requirements listed in the NCP. The risk assessment procedures used by the EPA have been developed to be conservative. and final risk estimates are interpreted to be a worst case estimate of risk, meaning that the true risk is likely to be much less.
Comment 7:
Various financial trusts should be established for the care of harms due to exposure of health risks caused by activities connected to past. present and future activities at the RMA. In connection to these trusts, ongoing human and animal health monitoring must be established. This may need to last several generations due to the hormonal nature of some toxics and the saturation levels in the environment.
Response 7:
The EPA, CERCLA, and NCP do not require the establishment of financial trusts specific for potential health effects caused by exposure, nor is the establishment of such a trust appropriate
930377.ene 7 for RMA. No offpost health effects have ever been documented from RMA activities. The Army is committed to providing adequate funding for both the present and future operation of the Offpost Groundwater Intercept and Treatment Facility until the cleanup goals established in the ROD are achieved. With regard to ongoing human and animal health monitoring, see response to comment Ic above.
Comment 8:
By its very nature clean-up says something is wrong. Even in terms of the proposed plan offpost cleanup could take 15 to 30 years. This and of course prior activities has a very depressing effect on the value of all property in the surrounding area. Therefore a plan needs to be established as part of the offpost proposal for the immediate and ongoing rehabilitation of property values and the real value of the affected communities. None of the alternatives address this.
Response 8:
Implementation of the preferred alternative will further reduce contamination in the offpost area. Contamination has already been reduced offpost through the operation of the boundary treatment systems. By implementing the preferred alternative, the offpost area will experience quicker reduction of contamination, which should protect property values offpost.
Comment 9:
We have heard many anecdotal stories of the stress and strain experienced on a day to day basis by residents of these communities who worry about their health, the affect on their communities, the affect on their property values, and the RMA unknowns. As part of the proposed plan, psychotherapy alternatives should be established and funded to clean-up this most insidious kind of offense against the people.
Response 9:
The Army does not intend to establish a regional outpatient psychotherapy center. The Army has based its offpost cleanup program on the most current and peer-reviewed information regarding chemical toxicity. The Army believes that the procedures followed by the Army, and instituted at other Superfund cleanup sites, are protective of human and ecological health.
Comment 10:
All areas need to be remediated to the highest standards. It is unacceptable for the artificial manipulation of standards by predetermining use. particularly zones 3 and 4 whose designation as urban residential appears to be completely arbitrary since it is zoned rural. Moreover, the established designations don't renect the value that the community applies to these areas. This is procedurally and bureaucratically tyrannical.
Response 10:
The Army has not predetermined use for zones 3 and 4. The selection of an urban residential land use was made in accordance with local governmental planning documents from Commerce City and Adams County. Based on these planning documents, the likely future use along 96th Avenue is either commercial/industrial or urban residential. Selection of an urban residential scenario is
930377.enc more conservative (e.g., results in higher estimated risks) than selection of a commercial/industrial scenario.
Comment 11:
The EPA, USFWS and Shell invoked dispute resolution concerning the MATC values used in the ecological risk assessment. Initially, the value of the MATC for both aldrin.and dieldrin in birds of prey was set at 1.6 ppm. The EPA pointed out that 1.6 pprn was the average concentration in the carcasses of 101 bald eagles found dead between 1971 and 1974 (p. VIII-13), and thus could hardly be considered a "protective" level. Furthermore, the EPA wrote that a carcass concentration as low as 0.66 has been associated with deaths from dieldrin poisoning. How is the MATC of 1.1 established by the dispute resolution process protective of the birds' health? The MATC for Endrin; for the Great Horned Owl and for the American Kestrel = 4 (p. 11-5-27); can we expect some birds to die as a result of endrin poisoning? How were the synergistic effects of contaminants taken into account? How do you understand the fact that "only a fraction of the eagles who visited the RMA roosting sites during the 1988-1989 season (possibly 100) only 7 returned form the previous year?" (p. 111-5-33).
Response 11:
As discussed in Volume VIII of the EA/FS, the Army does not agree with the conclusions drawn by the EPA regarding the literature studies reviewed for dieldrin toxicity. The Army believes that the literature cited by the EPA does not support their contention that dieldrin concentrations of 0.66 ppm were associated with death. These concentrations were present in dead animals but, according to the research authors, were not responsible for the animals' death. As part of the dispute resolution process, several articles published on dieldrin toxicity were reviewed by the dispute resolution parties. Following review and discussion, including input from the scientist whose study was cited by EPA, a dieldrin concentration of 1.1 ppm was agreed to by the Army, EPA. U.S. Fish and Wildlife Service, and Shell.
The Army does not expect birds to die from endrin poisoning. While the ratio value of 4 does exceed I for the great horned owl and the american kestrel, this is only an indication of potential concern and not an absolute indication of the severity of a potential effect. The maximum allo,aable tissue concentration (,NIA-;C) does not represent a lethal concentration. The interpreta- tion of the MATC is that this concentration is expected to be protective against health effects much less se%ere than death. Similar to the 3pplication of a reference dose in humans, exceedance of the MATC does not indicate unacceptability. only that an increased potential for adverse health effects (not including death) may Occur. Additionally, measured tissue concentrations in wildlife were less thin those Predicted by the food %16ebmodel. indicating that the modeled tissue concentration% may be overly conserv3ti%e.
Synergistic effects in wildlife were not evalu3ted because adequate scientific literature is not avall3ble for reference. and EPA has not de%eloped specific guidance on appropriate methods to use in evaluating these effects in wildlife 3nd ecosystems.
With respect to the comment on the number of eagles returning from the previous year, the commentor has apparently misinterpreted the information presented in the EA/FS, which is itself slightlN misleading. The EA/FS (vol Ill. page 5-33) states 'The (U.S. Fish and Wildlife) report states that possibly 100 or more eagles %isited the RMA roost during the 1988-1989 wintering season and that casual observation of the e3gles in early November suggests that up to seven of the eagles may have returned from the previous %ear.' Eagle populations at RMA do not peak until earlv January. In early November, it is likely that there were only seven eagles at the roosting
930377.enc 9 area at that time. The population continues to increase until January. Over the years, the number of eagles using the RMA roosting sites has increased. It is important to understand that although as many as 100 eagles may use the roosting site during any given season, the number of eagles present on any given day may only be 30 to 40. Eagles do not use the same roost continuously but instead migrate to different areas (sometimes on a daily basis) depending on where the food supply is located. Banding, capture, znd observation efforts by the USFWS in recent years have demonstrated that the number of eagles using and returning to the RMA roost sites is at least stable and possibly increasing.
Comment 12:
What is the "hot spot of surficial soil contamination" (p. 11-2-56) located within 1/2 mile of the intersection of 96th and Peoria street? Is it located on the property Shell recently purchased? To what extent does it contribute to the high cancer and liver toxicity risks associated with zone 3 and 4? To what extent does it contribute to the contamination of First Creek? What assurances do we have that no homes will be built on top of this wHot Spot?" Are there any plans to remediate the soil contamination here? If not, please explain.
Resvonse 12:
The NCP requires an evaluation of future land use that is both reasonable, from land use develop- ment patterns, and may be associated with the highest (most significant) risk. The Army believes that designation of these zones as rural residential is inappropriate for 1) current use, because these zones are not currently used as such, or 2) future use, because of the probability of develop- ment along 96th Avenue.
The hot spot of surf l,:ial contamination near 96th and Peoria Street is an area of localized higher pesticide concentrations. Concentrations of these pesticides contribute approximately 50 percent of the carcinogenic risks and 25 percent of the noncarcinogenic hazard indices in zones 2 and 3. This area of surficial contamination is not expected to have a significant effect on the pesticide concentrations identified in First Creek. At the present time, there are no cleanup plans for the soil in this area. Estimated risks associated with this soil are within EPA's health guidelines. If it becomes apparent that future land use in this area will be different from the land use evaluated in the EA, the Army will reevaluate the risks in this area and coordinate discussions with the EPA and CDH regarding land use.
930377.enc 10 Office of the Program Manager
Mr. Dan Mulqueen Project Leader RMA We The People 661 Pennsylvania Street Denver, CO 80203
Dear Mr. Mulqueen:
Thank you for providing comments on the Offpost Proposed Plan for Rocky Mountain Arsenal. The Army appreciates the large number of comments submitted on the Offpost Proposed Plan. Also included are responses to comments you submitted on the Submerged Quench Incinerator (SQI). I hope these responses increase your understanding of both the SQI and the offpost cleanup.
Please contact Mr. Bill Thomas. Public Affairs Office, at (303) 289-0136 if you have any questions regarding the SQI. and Mr. Tim Kilgannon at (303) 289-0201, if you have any questions regarding the Offpost Proposed Plan.
Sincerely,
Eugene H. Bishop Colonel. U.S. Army Program Manager
Enclosure
Copies Furnished:
Captain Jonathan Potter. Litigation Attornev. Rocky Mountain Arsenal Building III, Commerce City. Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of justice, 999-18th Street, Suite 501. North Tower. Denver. Colorado 80202 Document Tracking Center, ANLMNi-MT, Room 132, Building ill, Rocky Mountain Arsenal, Commerce City. Colorado 80022 RESPONSES TO LEAGUE OF WOMEN VOTERS COMMENTS THE LEAGUE OF WOMEN VOTEM OF COLORADO
1410 Grant. B-204 Denver. Colorado 80203 303*863*0437
June 21, 1993
Offpost Proposed Plan Comments Program Manager for Rocky mountain Arsenal Attn: AHXRH-PM\Col. Eugene H. Bishop Building 111-RHA Commerce City, CO 80022-2180
The League of Women Voters of Colorado commends you for your efforts at citizen involvement in the Offpost Proposed Plan* The "Citizens' Summary" was one of the most useful such documents we have encountered4 We are, however, not completely satisfied with the PROCESS. We believe that the intent of CERCLA was to involve citizens in all stages of the decision-making process. We believe that a CITIZEN ADVISORY COMMITTEE or possibly a SITE SPECIFIC ADVISORY BOARD should be in place before any more decisions are made, including the Offpost Plan.
We feel comfortable with the current off-post operations as an INTERIM measure, but request that ALL LONG TERM DECISIONS BE and POSTPONED UNTIL THERE IS ADEQUATE CITIZEN INVOLVEMENT 0 evaluation of cumulative effects.
Since the Cleanup of Rocky Mountain Arsenal is, in a sense, serving as a pilot for the cleanup of many Federal Facilities, there is increased scrutiny of the process. Last year there was speculation that the SQI project was in jeopard because of neighborhood perceptions. We submit that the root cause was a failure to involve that group of stakeholders in the decision- making process.
At the public meeting on the Offpost Propose Plan it was announced that no public hearing was to be held. The role of a public hearing is to include all concerns in the official record and thus require an official response. Public Hearings arer in effect, an insurance policy that you did, indeed, listen to the concerns of stakeholders. Public Perception is an important element in the success or failure of any cleanup project. -
Some issues which still must be addressed in the public realm are: *Levels of dieldrin, DIMP, and chloroform in the groundwater as well as locations. *Lab results from samples taken in November, 1992. *Future Land Use, including possible restrictions on use. *A satisfactory substitute for the failed mink studies *Justification for decision making before the Final Record of Decision A q37 o 5?1- The League of Women Voters of Colorado continues to request that an ADVISORY COMMITTEE, with attendance open to the public, be created, at least for the Final Record of Decision. The stakes are high and the Army's continual refusal to have an Advisory Committee is seen as an effort to hold back information. We are not advocating replacing the Technical Review Committee. That body can continue to serve by reviewing information being prepared for public distribution and be a first line conduit for dissemination of information between their various constitutiencies and the decision-makers.
We would suggest that a process be put in place which would include workshops, public meetings and public hearings leading up to the Final Record of Decision (ROD). The work already dome on the Proposed Offpost Plan is the kind of work we would support for each of the components of the Final Plan, and we commend you for making studies available as they are produced, but we would recommend that NO FURTZER DECISIONS be made until the Final Record of Decision.
There are those who feel that the Interim Response Action process has been abused in order to bypass public involvement and the creation of an adequate database. Many studies which have been suggested in the past have not been completed. It is time to stop, look at the total project, bring in an advisory committee and proceed with the caution needed to guarantee that the Cleanup of Rocky Mountain Arsenal will, indeed, be a model to be emulated.at other Federal Facilities.
Sincerely,
Betsy McBride, President U.S. DEPARTMENT OF THE ARMY RESPONSES TO LEAGUE OF WOMEN VOTERS COMMENTS REGARDING THE ROCKY MOUNTAIN ARSENAL OFFPOST PROPOSED PLAN JUNE 21, 1993
Resvonse to Geneýral Comment Regarding Citizen Involvement
The Army has provided for appropriate citizen involvement in the selection of the remedy as required by the National Oil and Hazardous Substances Pollution Contingency Plan (NCP) and the Comprehensive Environmental Response, Liability, and Compensation Act (CERCLA). The design and conduct of offpost investigative activities have been carried out with input and cooperation of the Colorado Department of Health, the U.S. Environmental Protection Agency, and the U.S. Fish and Wildlife Service. All documents relating to the offpost program are available for your review at the Joint Administrative Records Facility (JARDF) at the Security building at the west gate of RMA and local libraries. You are welcome to call the RMA Public Affairs Office at 289-0136 for more information.
A public hearing was not held. However, all comments made at the public meeting are part of the official record and a transcript is part of the Administrative Record. In addition, all public comments sent to the Army were responded to personally and are included as an appendix to the Record of Decision.
The Army has implemented an Interim Response Action (operation of the Offpost Groundwater Intercept and Treatment System) X begin cleanup of groundwater offpost. The Army will conduct groundwater and surface-water monitoring during operation of the treatment system to ensure compliance with the groundwater cleanup standards. If monitoring data suggest that the system is not performing as expec-ed, the Army will modify the treatment system to achieve the cleanup standards.
The Department of Defense is currently evaluating its role in the Site Specific Advisory Board (SSAB) concept at cleanup sites. The RMA has not created an overall plan for participating in a SSAB. should one be established. and cannot until the Department of Defense and the Department of the Army complete their evaluatlo7ýs. The Armv is, as vou know, expanding the role of the Technical Review Committee to implement some of the SSAB philosophies. As always we encourage any ideas or comments you may have on the Technical Review Committee.
ISSUES RAISED IN LETTER
I The Dieldrin, DIMP. and Chloroform concentrations in groundwater are well defined. An extensive monitoring effort continues in the offpost area to track these and other compounds. The locations of highest concentrations can be found in the Remedial Investigation Addendum for the Offpost Study Area. This document can be found at the JARDF as mentioned in the above comment.
2) All Lab results taken in November. 1992 were sent to the owners offpost. The Army has taken steps to correct the poor turnaround time. the time from when the wells are sampled to when results are available, it had experienced in the past.
3) Future land use is summarized in the Final Endangerment Assessment/Feasibility Study based on planning information from Adams County and Commerce City. Institutional Controls
930425E.enc I have been added to the Record of Decision (ROD) to further preclude the possibility of shallow drinking water wells being drilled in areas of higher contaminant concentrations.
4) The Army completed a 90 day mink study with DIMP that concluded that the 600 parts per billion Health Advisory set by the EPA is protective of Human Health and the Environment. The Army is currently evaluating the applicability of the 8 parts per billion level that the Water Quality Control Commission is expected to promulgate in a few months.
5) The Final Decision for cleanup of the Offpost Operable Unit will not be made until the Final ROD is released in early 1994. No final cleanup decisions have been made Offpost, to date.
93N25E.enc 2 Office of the Program Manager
Ms. Betsy McBride President, League of Women Voters 1410 Grant, B-204 Denver, CO 80203
Dear Ms. McBride:
Thank you for providing comments on the Offpost Proposed Plan for Rocky Mountain Arsenal. The Army appreciates the large number of comments submitted on the Offpost Proposed Plan. I hope the enclosed responses increase your understanding of the offpost cleanup. Also included are the comments you submitted on the Offpost Proposed Plan for easier reference to the response.
If you have any further questions please contact Mr. Tim Kilgannon of my staff at (303) 289-0201.
Sincerely,
Eugene H. Bishop Colonel, U.S. Army Program Manager
Enclosure
Copies Furnished:
Captain Jonathan Potter, Litigation Attorney. Rocky Mountain Arsenal Building Ill. Commerce City. Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of justice, 999-18th Street, Suite 501. North Tower, Denver. Colorado 80202 Document Tracking Center, ANLXP-M-IDT, Room 132, Building ill, Rocky Mountain Arsenal, Commerce City, Colorado 80022 RESPONSES TO DENVER REGION GREENS COMMENTS U.S. DEPARTMENT OF THE ARMY RESPONSES TO DENVER REGION GREENS COMMENTS REGARDING THE ROCKY MOUNTAIN ARSENAL OFFPOST PROPOSED PLAN JUNE 21, 1993
Comment 1:
The OSA is not large enough. The limiting of the offpost plan to just the area north of 90th Ave. between the South Platte River and Second Creek, with Barr Lake included, does not make sense, since the Colorado Department of Health (CDH) has found diisopropyl methyl phosphonate (DIMP) west of the South Platte, and has stated it has not conducted adequate testing northeast of Second Creek. We question the criteria used to determine what constitutes "acceptable" and .unacceptable" risk (see comment *5 below) used to rule out inclusion of the other offpost areas east, south, and west of the RMA in the OSA.
Response 1:
The Offpost Study Area was defined as those areas where RMA-related contaminants could be identified in soil, surface water, groundwater, or sediments. The general areas east, west, and south of RMA were not found to contain contaminants that could be directly attributable to RMA activities. The major factor in this finding is the direction of groundwater flow, which is toward the northwest. T'he Army is cooperating with the Colorado Department of Health with regard to additional sampling in certain areas. If the results from these sampling activities indicate that conclusions of the Endangerment msessment/Feasibility Study are no longer correct, the Army will evaluate the need to expand the area encompassed by the selected remedy.
Comment 2:
The OSA plan does not address remediation of ground water contamination that has already occurred beyond the current and proposed contaminated ground water intercept and treatment systems. At a minimum. residents who might be exposed to contamination from non-intercepted contamination plumes should be provided with a safe. non -contaminated alternative water supply, not just bottled drinking water.
Respons- 2:
The Army is aware that contamination exists do%ngradient of the Offpost Groundwater Intercept and Treatment System. Two new moratoring wells will be installed downgradient of the First Creek Pathway and one new monitoring %%ellwdi be installed downgradient of the Northern Pathway. The purpose of the three new monitoring -ells; is to aid in assessing the extent of contamination downgradlent of the Offporst Groundwater Intercept and Treatment System. Data collected from these and existing v el!s uill be used to further define the extent of contamination greater than the remediation goals in this area and &uist in determining whether modifications to the design of the Offpost Groundwater Intercept and Treatment System are necessary.
The Army is committed to providing alternati--e water supplies to residents whose drinking water exceeds groundwater cleanup standards as defined in the Record of Decision.
930425F.enc I Comment 3:
The OSA plan does not deal with other forms of offriost contamination such as air, surface water, and soil contamination by RMA sources. Assessment of air contamination to offpost areas was made before the Submerged Quench Incinerator (SQI) went into operation; the same for surface water and soil contamination. Again, we also question the criteria used to determine what constitutes "acceptable" health and environmental risk (see #5 below).
Response 3:
The three media mentioned (air, surface water, and soil) were addressed in the Endangerment Assessment/Feasibility Study. The air pathway was determined to be a negligible contributor to potential risks in the Offpost area. Potential health hazards associated with soil contamination are within the acceptable range as defined by the U.S. Environmental Protection Agency. Following implementation of the selected remedy, the water quality of First Creek will improve. The Army will implement a long-term surface water monitoring program to ensure the effectiveness of the remedy on surface water quality. The Army has also committed to closing the onpost sewage treatment plant, thus eliminating a possible source of contaminants in the First Creek surface water drainage.
Comment 4:
The OSA plan does not deal with compensation of residents living near the RMA for
a) negative health effects due to current and past exposures to RMA offpost contaminants;
b) continuing expenses to rear-by residents for past, present and future health care and health monitoring costs due to exposure to RMA offpost contamination;
c) losses in property values to near-by residents due to contamination of air, soil, and water by the RMA.
Any plan to deal with RMA offpost contamination needs to address these very critical compensation and continuing health care issues.
Response 4:
The risk assessment conducted for the Off post Study Area does not, by definition, determine whether adverse health effects have occurred or will occur and cannot identify particular individuals likely to suffer health problems because or contamination at a site. The Agency for Toxic Substances and Disease Control. in cooperation with the Colorado Department of Health, have ongoing epidemiological studies near RMA to address the occurrence of health effects and determine if these effects may be attributable to exposure to contaminants from a hazardous waste site. To date, no adverse health effects have been attributed to RMA.
The Army continues to conduct comprehensive monitoring programs in the Offpost area. If data is obtained indicating that chemical concentrations exceed (1) the cleanup standards established for the Of fpost OU, or (2) other EPA health standards, the Army will institute appropriate action to reduce the health threat.
930-42SF.enc Comment 5:
The levels of "acceptable" health risks in offpost areas, as high as five (5) excess cancers per ten thousand (10,000) people, using an Environmental Protection Agency (EPA) suggested level, is obscenely high, and should be raised to Lt least only one excess cancer per one million (1,000,000) people, and we strongly urge a human health risk factor of no more than one excess cancer per ten million (10,000,000) people. We hold that no one should involuntarily be subjected to health risks on the order of 5 excess cancers per 2,ODO people. People living in such conditions are living in environmentally toxic circumstances which should be viewed as repugnant by the EPA or any other regulatory or responsible agency or entity (business, federal facility, etc.). We also point out that there exist different opinions between the CDH and the EPA on what levels of exposure to certain chemicals are "acceptable' or not, e.g., DIMP standards. We support the most protective standards.
Response 5:
Operation of the Offpost Groundwater Intercept and Treatment System will reduce the estimated risks toward I x 10', the lower end of the acceptable risk range defined by the EPA. It is important to realize that the estimated risks presented in the EA/FS are most likely overestimated, in that several exposure pathways considered do not now occur and may not occur in the future. The army is aware of the recent Water Quality Control Commission standard of 8 ppb DIMP in groundwater. The Army is evaluating the applicability of this standard to the offpost remedial actions.
Comment 6:
There has been no epidemiological study of the residents living near-by the RMA for a range of possible health problems that could reasonably be expected from exposure to RMA contaminants. A limited study by the CDH found elevated levels of certain cancers in some near-by RMA residents. A comprehensive epidemiological study. including former residents who have since moved. should be conducted as p?rt of the OSA plan to assess the possible extent of negative health effects due to RMA contamination. and as a basis for compensation issues.
Response 67
The Cancer Incidence Study completed by CDH found no conclusive evidence that cancer rates in nearby residences were increased due to RMA contamination. For additional information see
Response No. 4.
Comment ":
The Record of Decision (ROD) reg3rding the OSA plan should be delayed until the State of Colorado has determined the State stand3rds for RNIA %katerand air contaminants, e.g., a DIMP groundwater standard.
Comment 8:
The ROD should be delayed until the leg3l status of the recent 10th Circuit Court of Appeals ruling given the State of Colorado increased standards setting and other authority over RMA clean up activities has been clarified.
93G425F.enc 3 Comment 9-
'ne ROD should be delayed until any legal and implementation questions regarding the applicability of the 1992 Federal Facilities Compliance Act to the RMA have been clarified. RMA Provisions of this ACT bear directly on actions the State of Colorado can take regarding clean up.
Response 7. 8- and 9- of The Army is not required to delay the issuance of the ROD pending State promulgation imple- standards or court interpretations on various issues. The Army intends to proceed with mentation of the selected remedy to begin Offpost cleanup as soon as possible.
Comment 10: in The ROD regarding the OSA should be delayed until the other outstanding issues mentioned comments * I through #6 above have been resolved through a process of negotiation which at this time. includes all interested and affected parties, a process which has not been developed interest Such a process would include representatives of citizens' groups, environmental and public boards, groups, neighborhood associations, city and county and state governments, special district health unions, and any other organizations that have an interest in such a decision, e.g., public associations, etc.
Response 10:
The Army has provided for public involvement opportunities for the public as required by the National Contingency Plan and the Comprehensive Environmental Responsibility, Compensation, review at and Liability Act. All documents relating to the offpost program are available for your west gate the Joint Administrative Record and Document Facility at the Security building at the of RMA. You are welcome to call the RMA Public Affairs Office at 289-0136 for more information.
9W425F.ene 4 Office of the Program Manager
Mr. T. Philip Hufford Denver Region Greens 1071 Madison Street Denver, CO 80206
Dear Mr. Hufford:
Thank you for providing comments on the Offpost Proposed Plan for Rocky Mountain Arsenal. The Army appreciates the large number of comments submitted on the Offpost Proposed Plan. I hope the enclosed responses increase your understanding of the offpost cleanup. Also included are the comments you submitted on the Offpost Proposed Plan for easier reference to the response.
If you have any further questions please contact Mr. Tim Kilgannon of my staff at (303) 289-0201.
Sincerely,
Eugene H. Bishop Colonel, U.S. Army Program Manager
Enclosure
Copies Furnished:
Captain Jonathan Potter. Litigation Attorney, Rocky Mountain Arsenal Building ill, Commerce City, Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of Justice, 999-18th Street, Suite 501. North Tower, Denver, Colorado 80202 Document Tracking Center, AM.)CR-M-rDT, Room 132, Building ill, Rocky Mountain Arsenal, Commerce Cih,. Colorado 80022 Appendix A-8
RESPONSES TO CMZEN COMMENTS it t wgt PUBLIC OOMMENT U.S. Army's "Proposed Plan for the Offpost Study Area" Colonel Eugene H. Bishop, Rik Bldg. 111, Camwce CitY, Colorado 80022-2180 ------
I am a resident of the "Offpost Study Area" and am directly affected by contamination from the Rocky Mountain Arsenal. I join with others in my cmTminity in opposing the Army's proposed plan. We urge that it be xTended to address broad canminity concerns with a carprehensive solution to widespread contamination problems that the ArnV and She] I Chemical CaTpany have failed to address, to date, and wt0ch currently poison domestic water supplies and private property for miles to the north and northwest of the Rocky Mountain Arsenal. Contaminants include deadly pesticides that were banned by the EPA years ago, by-products of chemical warfare agents, and other toxic substances.
I demv)d that the U.S. Army and Shell Chemical Ccrrvany develop and implement a plan to: 1) el iminate al I current sources of toxic exposure to citizens af f ected by of f -site poisons from the Rocky Mountain Arswial; 2) provide a pernwent, alternative, uncontaminated source of water to residents with any level of RKA toxins in their water; 3) conduct a caqx-ehensive offpost soil and water clean-up that meets all applicable federal and state guidelines, including RCRA; 4) that no final "Record of Decision" be issued until the Colorado Water Qua) ity Oontro I OaTmission adopts standards for unique, unregulated, Arsenal -related poisons, such as "DI MP"; and 5) that the ArnV wi I I mimt or exceed those standard(3) in al I grpurxiwater C)ean-up actions on and offpost.
MY additional ccmnents about the Army's inadequate cleart-up plan are these:
(see reverse side for continued commnts)
Please send written caments in resocnse to the urwt concerns raised in my caTments before a "recordof Decision" is issued regarding offpost Rocky Mountain Arsenal poisom. fi 0 _C_ (S i gnature) f-S NAME 5Pri -4 q Z 14--- ADDRESS TCWN ZIP PHME cc: Los Aspin, Secretary of Defwkse, Vice President A] Gore, Carol Browrwv-, U.S. EPA, Colorado Congressional delegation, chair3 of key Congressional oversight comnittees; Colorado Governor Roy Romer, Attorney General Gale Norton, CDH Director Patricia Nolan; public aadia DEPARTMENT OF THE APMY I -ý ARSENAL *1: PROGRAM MANAGER FOR ROCKY MOLWTAN 50' comm=E CrrY. COLORADO SWZ24 748
December 9, 1993
REPLY TO AMMON OF: Office of the Program Manager
Mr. and Mrs. Owen Bakes 11460 Peoria Street Henderson, Colorado 80640
Dear Mr. and Mrs. Bakes:
the many comments received on Thank you for your comments. The Army appreciates (RMA). Public input is a key part of the Offpost Proposed Plan for Rocky Mountain Arsenal the cleanup process at RMA.
Unit will clean up contamination that The preferred alternative for the Offpost Operable studying the best possible way to eliminate came from RMA. The Army has spent nine years Preferred Alternative goes beyond what potential health threats offpost. We believe the Offpost Agency (EPA). In addition, the Army cannot is required by the U.S. Environmental Protection supply because legal legally provide offpost residents with a new water The Army will, as it has in the past, provide chemical health guidelines are not being exceeded. applicable EPA health guidelines are not being offpost residents an alternative water supply if believes that all applicable federal and met in their private well water. Finally, the Army state guidelines are being met for soil and water offpost.
contamination in groundwater One of the major concerns to offpost residents is the DIMP to make sure the Army would further study offpost. Since my tenure began at RMA, I wanted Health Advisory of 600 parts per billion is the DIMP tests to evaluate whether the EPA DIMP 30 separate animal studies with DIMP, safe. Overall, the Army has conducted more than National Academy of Sciences evaluated including one study with humans. The EPA and the 600 parts per billion Health Advisory is all health studies and concluded that the EPA's addition, the Army evaluated all possible protective of human health and the environment. In body. These tests again showed that the ways Dr.%fP and other chemicals could enter the human environment. As an additional protective water offpost is protective of human health and the Boundary System will treat the measure, the Offpost Treatment System and the North is currently evaluating the applicability groundwater to less than 10 parts per billion. The Army Control Commission is expected of the 8 parts per billion level that the Colorado Water Quality to promulgate in the next several months.
Readiness is our PTofession Any other questions I hope this information has helped to alleviate your concerns. at regarding the Offpost Proposed Plan may be directed to Mr. Tim Kilgannon of this office 289-0201. Thank you again for your comments. Sincerely,
gene Bishop Colonel, U.S. Army program Manager
Copies Furnished: Captain Jonathan Potter, Litigation Attorney, Rocky Mountain Arsenal Building 111, Commerce City, Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of Justice, 999-18th Street, Suite 501, North Tower, Denver, Colorado 80202 Rocky Document Tracking Center, AMX.RM-IDT, Room 132, Building 111, Mountain Arsenal, Commerce City, Colorado 80022 -Z
Jack E. Clancy 12220 Peoria Henderson, Co. 80601
Col. Eugene H. Bishop United States Army/ Building III-Rmx Commerce City/Co. 80022
Dear Col. Bishop:
As owner- of property north of the Rocky Mountain Arsenal that has a DI2'YT contaminated well on it, I urge the Army to take action above and beyond what it is now doing to remedy the ground water contamination problem faced by me and my 600 neighbors.
We use the bottled water for drinking and cooking, but we still bathe in DIMP water every day, we water our vegetable garden with DIMP water, we give our livestock DINT water and we still don't know what the eventual effect on our health will be.
From a risk management viewpoint, it would be wise for the Army to spend the $7 million now to provide a clean water system to the area and protect the health of residents rather than to wait 10 to 20 yea?s and face the possibility of numerous lawsuits or a class action suit if it is proved that DIMP has-damaged the health of residents.
We cannot wait the 10 to 20 years that it will take to clean up the ground water using the current methods. WE NEED AND ARE EYMIF-D TO HAVE CLEA.N, WATER. WEN.= IT NOW AND WE WILL NOT SETTLE FOR ANYTI]ING LESS!
Sincerely,
Jack E. Clancy Office of the Program Manager
Mr. Jack E. Clancy 12220 Peoria Henderson, Colorado 80601
Dear Mr. Clancy:
Thank you for your comments. The Army appreciates the many comments received on the Offpost Proposed Plan for the Rocky Mountain Arsenal (RMA). your Public feedback is a key part of the cleanup process at RMA. I will respond to comments in the order we received them.
One of the major concerns to offpost residents is the DIMP contamination in groundwater offpost. Since my tenure began at RMA, I have ensured that the Army would further study the DEMP tests to evaluate whether the U.S. Environmental Protection Agency (EPA) DIMP Health Advisory of 600 parts per billion is safe. Overall, the Army has conducted more than 30 separate animal studies with DEVIP, including one study with humans. The EPA and the National Academy of Sciences evaluated all health studies and concluded that the EPA's 600 parts per billion Health Advisory is protective of human health and the environment. In addition, the Army evaluated all possible ways DIMP and other chemicals could enter the human bodv. These tests again showed that the water offpost is safe for consumption and for the environment As an additional protective measure, the Offpost Treatment System and the North Boundary System treats the groundwater to less than 10 parts per billion. The Army is currently evaluating the applicability of the 8 parts per billion level that the Colorado Water Quality Control Commission is expected to promulgate in the next several months.
Based on our current data. all residents in the offpost study area are drinking water that meets all applicable or relevant and appropriate federal and state regulations. Army continues to extensively monitor drinking water wells in the offpost area. If levels of Arsenal-Related ýhemicals were to rise above health guidelines in the drinking water for anv resident. the Army will provide an alternate water supply to that resident Any other questions regarding the Offpost Proposed Plan may be directed to Iýft. Tim Kilgannon of this office at 289-0201. Thank you again for your comments. Sincerely,
Eugene H. Bishop Colonel, U.S. Army Program Manager
Copies Furnished:
Captain Jonathan Potter, litigation Attorney, Rocky Mountain Arsenal Building ill, Commerce City, Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of justice, 999-18th Street, Suite 501, North Tower, Denver, Colorado 80202 Document Tracking Center, AM)MM-IDT. Room 132, Building 111, Rocky Mountain Arsenal. Commerce City, Colorado 80022 t PUBLIC COMMENT Area" U.S. Army's "Proposed Plan for the Offpost Study Colorado 80022-2180 Colonel Eugene H. Bishop, RMA Bldg. 111, Comnerce City,
fr= of the "Offpost Study Area" and wn directly affected by contamination I am a resident the Army's mountain Arsenal. I join with others in my cowminity in opposing the Rocky with a proposed plan. We urge that it be amended to address broad ommunity concerns that the Army and She] I Chemical caTprehensive solution to widespread contamination problems poison domestic water supplies Ccrrpany have failed to address, to date, and which currentl of the Rocky Mountain Arsenal. and private property for miles to the north and northwest EPA years ago, by-products of Contaminants include deadly pesticides that were banned by the chenical warfare agents, and other toxic substances.
and impleTant a plan to: 1) I demand that the U.S. Army and Shell Chemical Ccmpany develop by off-site poisons from eliminate all current sources of toxic exposure to citizens affected uncontaminated source of the Rocky Mountain Arsenal; 2) provide a permanent, alternative, 3) conduct a comprehensive water to residents with ALiy leXel of RmA toxins in their water; federal and state guidelines, offpost soil and water clean-up that meats all applicable unti I the Colorado Water including RCRA; 4) that no final "Record of Decision" be issued Arsena I -re I ated po i sons, Qua I i ty Contro I Ccmi ss i on adopts standards f or un i quo, unrequ I ated, standard(s) in a] I 9gourAvater such as "D IMP"; and 5) that the Army wi I I meet or exceed those clean-up actions on and offpost.
are these: My additional carmBnts about the Army's inadequate clean-up plan
(see reverse side for continued ccmTents)
my carments before Please send written ca ...m ts in response to the urgent concerns raised in a d ojýýision'W issued regarding offpost Rocky Mountain Arsenal poisons.
'týE (Signature)
Ve tZ V,"N 0 JC;
NAM (Printed) 17
ADDRESS TCWN ZIP PHONE
U.S. EPA, cc: Les Aspin, Secretary of Defense, Vice President Al Gore, Carol Browner, ocumittees; Colorado. Colorado Congressional delegation, chairs of key Congressional oversight Governor Roy Romer, Attorney General Gals Norton, COH Director Patricia Nolan; pub] ic media Office of the Program Manager
Mr. and Mrs. Steve Evanoff 11890 Peoria Street Henderson, Colorado 80640
Dear Mr. and Mrs. Evanoff:
Thank you for your comments. The Army appreciates the many comments received on the Offpost Proposed Plan for Rocky Mountain Arsenal (RMA). Public input is a key part of the cleanup process at RMA.
The preferred alternative for the Offpost Operable Unit will clean up contamination that came from RMA. The Army has spent nine years studying the best possible way to eliminate potential health threats offpost. We believe the Offpost Preferred Alternative goes beyond what is required by the U.S. Environmental Protection Agency (EPA). In addition, the Army cannot legally provide offPost residents with a new water supply because legal chemical health guidelines are not being exceeded. The Army will, as it has in the past, provide offpost residents an alternative water supply if applicable EPA health guidelines are not being met in their private well water. Finally, the Army believes that all applicable federal and state guidelines are being met for soil and water offpost
One of the major concerns to offpost residents is the DIMY contamination in groundwater offpost. Since my tenure began at FZMA, I wanted to make sure the Army would further studv the DL\fP twts to evaluate whether the EPA DEMY Health Advisory of 600 parts per billion is safe. Overall. the Army has conducted more than 30 separate animal studies with DINIP. including one study with humans. The EPA and the National Academy of Sciences evaluated all health studies and concluded that the EPA's 600 parts per billion Health Advisory is protective of human health and the environment. In addition. the Army evaluated all possible ways DR" and other chemicals could enter the human body. These tests again showed that the water offpost is protective of human health aný the environment. As an additional protective measure. the Offpost Treatment Systern and the North Boundary System will treat the groundwater to less than 10 parts per billion. The Army is currently evaluating the applicability of the 8 parts per billion level that the Colorado Water Quality Control Commission is expected to promulgate in the next several months. I hope this information has helped to alleviate your concerns. Any other questions regarding the Offpost Proposed Plan may be directed to Mr. Tim Kilgannon of this office at 289-0201. Thank you again for your comments. Sincerely,
Eugene H. Bishop Colonel, U.S. Army Program Manager
Copies Furnished: Captain Jonathan Potter, Litigation Attorney, Rocky Mountain Arsenal Building ill, Commerce City, Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of justice, 999-18th Street, Suite 501, North Tower, Denver, Colorado 80202 Document Tracking Center, AM)CRM-IDT, Room 132, Building ill, Rocky Mountain Arsenal, Commerce City. Colorado 80022 Offpost Proposed Plan Comments Program Manager for Rocky Mountain Arsenal Attn: AMXRM-PM\Col. Eugene H. Bishop Building 111-RMA Commerce City, CO 80222-2180
Colonel Bishop,
I feel there are still some unresolved issues related to the Of fpost Proposed Plan. First, however, is the issue of the appropriateness of the Plan at this time. I submit that the intent of the FINAL RECORD OF DECISION is to include all long-term decisions under one process. I would, therefore, request that no further action be taken on the Of fpost Plan. Continue operation of the of fpost water treatment facility and use the next year or so to gather data as to what contaminants are still getting past it, where else contaminants are showing up, and how best to handle the land use issues.
Here is a list of the issues I feel should be addressed bef ore a final decision is made:
1. CITIZEN INVOLVEMENT: There is a significant difference between a Technical Review Committee and an Advisory Committee or- Board, both in function and in makeup. I would like to see bothl The inf ormation I have seen so f ar about Site Specif ic Advisory Boards leads me to suggest you explore that type of approach for the final ROD.
2. CUMULATIVE EFFECTS: By looking at each action as a separate unit, there is a good chance that the cumulative ef fect of all actions will be much more detrimental to human health and the environament than is being suggested by the current approach. I'll be more comfortable with the Final Decision after I've seen some more data on long-term, cumulative effects of such things as DIMP, dieldrin and chloroform. Saw much of each is added to the life- time exposure for people by the combination of all actions at Rocky Mountain Arsenal and what are the risks?
3. DATAMSE: Until all of the data is in about the health effects of some of the chemicals of note, it is premature to decide on the fizuLl level of cleanup. My reading of the preferred alternative for the Off Post Plan is that further monitoring and upgrades would be expected, just as they have been for the NN Boundary System. Since mink studies did not work out, there must- be some way to test for harm. Without proof that there is no harm, I would recommend total cleanup. My guess is that it would be less expensive to conduct further studies than to remove all contaminants. Even one person able to win a suit that he or she has been harmed by the Dimp (for instance) would hurt the Army's credibility at all of its cleanup sitesl Better safe than sorry.
YJ Before a final decision is madef I would recommend retesting all of the wells in and near the study area to verify that the current system is working as designed. Public availability of the data would add to the credibility of the Army and Shell. Also, the levels And types of contaminants an the soil could be verified on a smaller scale, perhaps even lot by lot, before final land use restrictions and decisions are agreed to by Adams County, Commerce City and any other land use decisionmakers. 4. ARARs: Given the historical propensity to sue, someone is bound to push for State standards and/or guidelines, especially when they are more stringent than those of EPA. It seems to me to be a better use of taxpayer money to try to meet the most stringent levels as a part of the Final Plan, rather than to spend years defending the decision in court.
S. LAND USE: There seen to be legitimate concerns for the future land use of the area. By postponing the final decision on the Of fpost area, you will have more tijne to work with the appropriate land use decisionmaking bodies in order to guarantee safe use of the land and/or adequate cleanup for the allowed land Use.
You have done a good job 'so far and the cleanup is at a critical point. Peopla are not nearly as easy to predict as chemical compounds, but it is a safe bet that support is more likely when stakeholders have "bought into the decisions."
None of these comments should come as a great surprise to you, but I want then in the official record, in part because my experiences with both public participation and the planning process lead me to hope that you will do everything possible to prevent embarrassing problems 1^ter. I have been a member of the Technical Review Committee since 1988 and, honestly, want to be proud of what is accomplished at Rocky Mountain Arsenal.
Sincerelyr
Clara Lou Humphrey Office of the Program Manager
Ms. Clara Lou Humphrey 93 90 W. I st Avenue Lakewood, Colorado 80226
Dear Ms. Humphrey:
Thank you for your comments. The Army appreciates the many comments received on the Offpost Proposed Plan for Rocky Mountain Arsenal (RMA). Public input is an integral part of the cleanup process at Rocky Mountain Arsenal. I will respond to your comments in the order we received them.
I appreciate your request to delay the Offpost Final Record of Decision until monitoring of the Offpost Treatment System has been completed for one year. The Amy will be constantly reevaluating the Offpost Treatment System through our ongoing monitoring program to examine whether modifications are necessary. The Final Record of Decision does not include the details of the monitoring programs and modifications to the Offpost Groundwater Treatment System. The Final Record of Decision states the selected alternative for cleanup of the Offpost Operable Unit This selected alternative is based on nine years of study Subsequent documents. including an implementation plan, will be completed detailing the offpost monitoring to be conducted and anv changes to the selected alternative that are based on monitoring data Listed below are responses to vour numbered comments:
I The Department of Defense is cuffently evaluating its role in the Site Specific Advisory Board (SS.A.B) concept at cleanup sites The R-MA has not created an overall plan for participating in a SSAB, should one be established. and cannot until the Department of Defense and the Department of the Arm% complete their evaluations. The Army is, as you know. expanding the role of the Technical Re%ic%h Committee to implement some of the SSAB philosophies. As alwavs %%c encoura4e an% ideas or comments you may have on the Technical Review Committee
2. The Armv evaluated the lone-term and t;umuljtj%,e health effects of the chemicals offpost. These effects were analvzed in the Offpost Risk Assessment. In fact, the Offpost Risk .-'Lssessment evaluated the cumulati%c risks vi contamination offpost over a 70- year period, which is stipulated bv U.S. En%ironmentil Protection Agency (EPA) guidance. The risks presented in the Offpost Proposed Plan are the Iong-term risks of the contamination offpost without considering the benefit of OiTpost Treatment System operations.
3. One of the major concerns to offpost residents is the DINT contamination in groundwater offpost. Since my tenure began at RMA. I have ensured that the Army complete additional DINIP tests to evaluate whether the L: S Environmental Protection Agency (EPA) DRVT Health Advisory of 600 parts per billion is safe Overall, the Aimy has conducted more than 30 separate animal studies with DMIP, including one study with humans. The EPA and the National Academy of Sciences evaluated all health studies and concluded that the EPA's 600 parts per billion Health Advisory is protective of human health and the environment. In addition, the Army evaluated all possible ways DIM? and other chemicals could enter the human body. These tests again showed that the water offpost is protective of human health and the environment. As an additional protective measure, the Offpost Treatment System and the North Boundary System will treat the groundwater to less than 10 parts per billion. The Army is currently evaluating the applicability of the 8 parts per billion level that the Colorado Water Quality Control Commission is expected to promulgate in the next several months.
The land use projections were used for the Offpost Risk Assessment. The Offpost Risk Assessment analyzes potential risks from chemicals to the human body. These land use projections in no way mean that the offpost area has been or will be zoned in a particular fashion. The land use projections we established for the Offpost Risk Assessment are the most conservative for the zone studied in the Proposed Plan. Conservative land use projections are the human health problems that could possibly develop and pose the highest potential risk. Say, for instance, that in zones 3 and 4 the Army projected urban residential land use According to Adams County and Commerce City projections, the land in these two zones will most likely be industrial /commercial in the future, but the actual land use won't be decided until the land is developed. The Army decided that by using urban residential land use for the Offpost Risk Assessment, we were examining the worst-case risk assessment and thus providing the best cleanup alternative
Soil contamination was evaluated in the Remedial Investigation and subsequently in the Offpost Risk Assessment. After evaluating wind patterns at the Arsenal and concentrations of contaminants a-. they travel from onpost to offpost, the Army concluded that offpost soils are %%ell within EPA's health euidelines Over 70 percent of the risk calculated offpost (prior to construction of the Offpost Treatment System) was due to groundwater contamination. thus surface water. soil. and sediment are minor contributors to the overall risk- Institutional controls have been incorporated into the Offpost Preferred Alternative based on State EP-% and public comments These institutional controls will prevent offpost residents from drilline new dfinkine water wells in groundwater that does not meet applicable federal and state standards.
4 First. human health and the environment are not impacted by the fact that the Army has not adopted state standards as Armv standards Second, the "y does not believe that the state standards are drinking water standards Even though the Army does not believe the state standards are drinking water standards. the differences between federal and state standards are described below
For the chemicals of concern for the Offpost Study Area, only two chemical standards within the state standards are more stringent than the federal standards. Dieldrin, a pesticide, has both federal and state standards that are below the chemical detection limit, which means, with current technology, the Army cannot measure to the federal or state standard. When a chemical standard is below the detection limit, treatment must be made to that detection limit. The other chemical where the state regulations differ is chloroform. The Colorado standard for chloroform is 6 parts per billion. The Army treats chloroform in the Groundwater Trea=ent Systems to approximately 12 parts per billion. Municipal water supplies for drinking water in the Denver Metro Area typically have chloroform concentrations of 10-50 parts per billion as a result of the chlorination process, which kills bacteria living in the water supplies.
Again, the Army believes that the federal drinking water standards are protective of human health.
5. See response to comment number 3.
I hope this information helps to alleviate your concerns. I appreciate your continued support of the RMA program and the input you give the Army with the Technical Review Committee. Any other questions regarding the Off'post Proposed Plan may be directed to Mr. Tim Kilea-nnon of this office at 289-0201. Thank you again for your comments.
Sincerely,
Eugene H. Bishop Colonel, U.S. Army Program Manager
Copies Furnished
Captain Jonathan Potter. Litigation Anomev. Rockv %Iountain Arsenal Buildinz I 11, Commerce City. Colorado 800:: %Ir Bradley Bridgewater. U S Department of Justice, 999-18th Street, Suite 501 , North Tower, Den%-er. Colorado 80202 Document Tracking Center, AMMCNI-IDT. Room 132. Building I 11, Rocky .Mountain Arsenal, Commerce Cit\. Colorado 800:' Fýg r:ýý
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Do You Want to be Involved Protecting This Coýwnity and Your Future? Please take the time to complete the following information to help us compile a community comment that we can submit to the US Army. N=e: T614V tXERBI& 1WUMR14,e6kk5 Address:-1/690 P6QfZQo+ Sr. Phone: 9/ 1)- Are there any unusual. health conditions being experienced by anyone in your home? What?
What do you want the Army to do for the area that Is contaminated?
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RESIDENT 11690 PEORIA ST HENDERSON , CO 80640 Office of the Program Manager
Mr. and Mrs. John Humphreys 11690 Peoria Street Henderson, Colorado 80640
Dear Mr. and Mrs. Humphreys:
Thank you for your comments. The Army appreciates the many comments received on the Offpost Proposed Plan for the Rocky Mountain Arsenal (RMA). Public input is a key part of the cleanup process at RMA.
The Army, as stated in the Proposed Plan, will spend more than 70 miffion dollars cleaning up the groundwater (water beneath the ground surface) at the north and northwest boundaries of RMA and offpost during the next 15 to 30 years. The Army has already spent over 15 million dollars to treat the groundwater offpost. Groundwater offýost, even though within the U.S. Environmental Protection Agency health guidelines, contributes approximately 70 percent of the health risk offpost For this reason, the Army decided to clean up the groundwater to further reduce the possible risk.
The Army, in cooperation with Tri-County Health Depart33aent, samples private wells offpost on a quarterly basis. The Army will notify Tri-County Health Department about your well so that it can be sampled as soon as possible.
If you have any questions regarding the sampling procedures of your private well(s), please contact Tri-County Health Department at (303) 288-6816. Questions regarding the Offpost Proposed Plan may be directed to Mr. Tim Kilgannon of this office at (303) 289-0201. Thank you again for your comments.
Sincerely,
Eugene H. Bishop Colonel, U.S. Army Program Manager Copies Furnished:
Captain Jonathan Potter, Litigation Attorney, Rocky Mountain Arsenal Building ill, Commerce City, Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of justice, 999-18th Street, Suite 501, North Tower, Denver, Colorado 80202 Document Tracking Center, ANEXRM-IDT, Room 132, Building ill, Rocky Mountain Arsenal, Commerce City, Colorado 80022 T6
t PUBLIC COMMENT U.S, Army's "Proposed Plan for the Offpost Study Area"' Colonel Eugene H. Bishop, RMA Bldg. ill, Cammrce City, Colorado 80022-2180
I am a resident of the "Offpost Study AroC and am directly affected by contamination frcin the Rocky Mountain Arsenal. I join with others in n?/ community in opposing the Army's proposed plan. We urge that it be amended to address broad camiunity concerns with a ccnprehensive solution to widespread contamination problem that the " and Shel I Chemical Company have f a i I ad to address, to date, and wh i ch 'currently poison domestic water supplies and private property for miles to the north and northwest of the Rocky Mountain Arsenal. Contaminants include deadly pesticides that were banned by the EPA years ago, by-products of chemical warfare agents, and other toxic substances.
I demwid that the U.S. Army and Shell Chemical Carpany develop and implement a plan to: 1) eliminate all current sources of toxic exposure to citizens affected by off-site poisons from the Rocky Mountain Arsenal; 2) provide a pemw-,ent, alternative, uncontaminated source of water to residents with any level of RMA toxins in their water; 3) conduct a comprehensive offpost soil and water clean-up that meats all applicable federal and state guidelines, including RCRA; 4) that no fin&] "Record of Decision" be issued until the Colorado Water Oua I i ty Contro I 0ami ss i on adopts standards for un i qua, Ln-requ I ated, Arsena I -re I ated po i sons, such as "D I MP-; and 5) that the Army w i I I meet or exceed those standard(s) in al I groundwater clean-im actions on and offpost.
My additional comm ts abcxit the Army's inadequate clam-up plan are these:
(see reverse side for cm inued comments)
Please send w-Itten comrants in response to tho urgent concerns raised in my comments before a "Record of Decision- is issued regarding of fpost Rocky mountain Arsenal poisons. V0:4, (Signature) R_ T NAME (Printed) P0 64/6 :2 -7 61 7_2 4- L 10, ADDRESS TOAN ZIP PHONE
CC: LOS Aspin, Secretary of Defense, vice President Al Gore, Carol Browner, U.S. EPA, Colorado C*ngressional delegation, chairs of key Congressional oversight caTmitteers; Colorado Govwyxx- Roy Romet -PAttorney General Gals Norton, COH Director Patricia Nolan; public media Office of the Program Manager
Mr. J.H. Irthum 1123) 0 Peoria Street Henderson, Colorado 80640
Dear Mr. Irthum:
Thank you for your comments. The Army appreciates the many comments received on the Offpost Proposed Plan for Rocky Mountain Arsenal (RMA). Public input Is a key part of the cleanup process at RMA.
The preferred alternative for the Offpost Operable Unit will clean up contamination that came from RMA. The Army has spent nine years studying the best possible way to eliminate potential health threats offpost. We believe the Offpost Preferred Alternative goes beyond what is required by the U.S. Environmental Protection Agency (EPA). In addition, the Army cannot legally provide offpost residents with a new water supply because legal chemical health guidelines are not being exceeded. The Army will, as it has in the past, provide offpost residents an alternative water supply if applicable EPA health guidelines are not being met in their private well water. Finally, the Army believes that all applicable federal and state guidelines are being met for soil and water offpost.
One of the major concerns to offpost residents is the DI1VT contamination in groundwater offpost Since my tenure beg-an at RINLA, I wanted to make sure the Army would further study the DIMP tests to evaluate whether the EPA DINIP Health Advisory of 600 parts per billion is s afe 0-,,erall, the Army has conducted more than 30 separate animal studies with DIMP, includinu one studv with humans. The EPA and the National Academy of Sciences evaluated all health studies and concluded that the EPA's 600 parts per billion Health Advisory is protective of human health and the environment In addition, the Army evaluated all possible ways DUVT and other chemicals could enter the human body These tests again showed that the water offpost is protective of human health and the en%-Ironment. As an additional protective measure, the Offpost Treatment System and the North Boundary System will treat the groundwater to less than 10 parts per billion. The Amy is currently evaluating the applicability of the 8 parts per billion level that the Colorado Water Quality Control Commission is expected to promulgate in the next several months I hope this information has helped to alleviate your, concerns. Any other questions regarding the Offpost Proposed Plan may be directed to Mr. Tim Kilgannon of this office at 289- 0201. Thank you again for your comments.
Sincerely,
Eugene H. Bishop Colonel, U.S. Army Program Manager
Copies Furnished:
Captain Jonathan Potter, Litigation Attorney, Rocky Mountain Arsenal Building I 11, Commerce City, Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of Justice, 999-18th Street, Suite 501, North Tower, Denver, Colorado 80202 Document Tracking Center, ANEXRM-IDT, Room 132, Building I 11, Rocky NIountain Arsenal, Commerce City, Colorado 80022 STEVEN L. JANSSEN, P.C. CommUm A Attorney at Law 745 Walnut Street Boulder, CO 8MO2 tckpbo= (303) 443-4337 fammile: (30) "3-IV7
I - 11@9 OUR June 18, 1993 JUN 2 8 =
Off-Post Proposed Comments Program Manager for Rocky Mountain Arsenal ATTN - Colonel Eugene H. Bishop Building I 11 Rocky Mountain Arsenal Commerce City, CO 80022-2180
Dear Colonel Bishop:
This office represents the Henrylyn Irrigation District, comprising approximately 33,000 Colorado. 0 acres of irrigated farm land in southern Weld County,
Our District derives the majority of water from the South Platte River through the Burlington Ditch.
My client has reviewed the proposed plan for the Rocky Mountain Arsenal Off-Post Study Area and is principally concerned that the proposed plan for study does not address the possibility oL and regular scientific investigation for, contamination to my client's numerous and various water rights which pass through the Burlington Ditch. My client's users udlize said water for many purposes, including the irrigation of crops and the watering of livestocL
Our review of the previous scientific investigation shows that there has been a detection of DIMP at Barr Lake. My client also owns a significant portion of the water stored in Barr Lake. Because DIMP has travelled to Barr Lake, it is entirely possible that it will travel to other reservoirs in my client's system-
Therefore, my client requests that you consider a revision to this proposed plan for study, incorporating a periodic (suggested one year intervals) scientific study (suggested to be completed by experts selected by my client but paid for by the Dept. of the Army) to determine whether contamination has migrated to my client's facilities or is present in my client's water supply.
nean Rwyde Off-Post Proposed Comments Program Manager for Rocky Mountain Arsenal ATIN - Colonel Eugene EL Bishop June 18, 1993 Page 2
We would request that this additional investigation be maintained for the 30 year life expectancy of the plan. It is our understanding that the Dept. of the Army has cooperated with other entities on similar matters in the past. My client believes the additional cost of this requested monitoring wiU be minimal as compared to the increase in safety of the people utilizing my client's water storage facilities and irrigation water rights. Of course, if you have any questions in this matter, or wish to discuss this ftu-ther, do not hesitate to contact me.
Very Truly Yours, STEVE SSEN, P.C
en L J;knq Q _--Sftv iI ans-si I_J/VE SSEN, PC U/mtm
CC*. Board enrylyn Irrigation District
rmm Rftryck Office of the Program Manager
Mr. Steven L. Janssen, P.C. 745 Walnut Street Boulder, Colorado 80302
Dear Mr. Janssen:
Thank you for your comments. The Army appreciates the many comments received on & Offpost Proposed Plan for Rocky Mountain Arsenal (RMA). Public input is a key part of the cleaniýp process at RMA. I will respond to your comments in the order we received them.
The Offpost Proposed Plan outlines a preferred alternative.that is based on nine years of study. Followin3 selection of a final alternative, the Army will produce an Implementation Plan that will address the monitoring of offpost groundwater and surface water. This document will be available for review in the joint Administrative Record and Document Facility.
Over the vears the Army has documented a decrease of contaminants offpost, primarily due to the Boundarv Groundwater Treatment Systems. With the addition of the Offpost Treatment System. which was fully operational in June 1993, contaminant concentrations will be reduced even further. The Treatment Systems are also important in impro%ing the quality of water in First Creek as groundwater discharges into First Creek in some areas. including just north of the RMA boundary.
The DafP contamination you are referring to in Barr Lake was detected only once. approximately 100 times below the U.S. Environmental Protection Agency's (EPA's) Health Advisory level No detections of Dl]W were found in the many other water and sediment samples taken in Barr Lake. In addition, samples taken in the canals and creeks that eventually discharge to Barr Lake have shown only sporadic detections of DMfP at verv low concentrations (more than 100 times below EPA's Health Advisory level).
Because chemical standards are being met in the canals and Barr Lake, the Army cannot provide funds to your client. As mentioned above, the Army will produce monitoring plans and will make these available for public review. The Army looks forward to working with you in the future. I hope this information helps to alleviate your concerns. Any other questions regarding the Offpost Proposed Plan may be directed to Mr. Tim Kilgannon of this office at 289-0201. Thank you again for your comments. Sincerely,
Eugene H. Bishop Colonel, U.S. Army Program Manager
Copies Furnished:
Captain Jonathan Potter, Litigation Attorney, Rocky Mountain Arsenal Building ill, Commerce City, Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of justice, 999-18th Street, Suite 501, North Tower, Denver, Colorado 80202 Document Tracking Center, ANfXRM-H)T. Room 132, Building 111, Rocky Mountain Arsenal, Commerce Citv. Colorado 80022 FirstChristian Assembly of God-
12505 E3mendorf Place Denver, Colorado 80239 Pamr Madlyn Tombs (3W) 3M-5200
JUN 2 2 ýW
June 21. 1993
Program Manager RMA AMCRM PM/Colonel Eugene H. Bishop Building 111 Commerce City, Colorado 80022-2180
DeAr Colonel Bishop,
I am writing in regards to the off post clean-up plan of the Rocky Mountain Arsenal. I am an Associate minister of First Christian Assembly of r-od Montbello a representative of the Montbello Cooperative Ministries and a member of the Far Northeast Neinhbors. 0
I am Part of the process to ýreep eac-h one of these organiza- r1ons informed of r.he various aspects of clean-up on the RMA its-1.9.' : would like to also bp a part of the off post site clean-up in regards ý-o meetings and information. There are many corcerns "hat nas,ýd to be Addressed in regards to the Monttello Community and tie contamination it has recieved from the RMA.
3ý cna be reached at (303)-(373-5200), from 8:30 AM to 5:00 PM ON Monday thru Friday.
Thank You,
Jeffery D. Kanost
cc/pf Office of the Program Manager
Mr. Jeffery D. Kanost 12505 Elmendorf Place Denver, Colorado 80239
Dear Mr. Kanost:
Thank you for your comments. The Army appreciates the many comments received on the Offpost Proposed Plan for Rocky Mountain Arsenal (RMA). Public input is a key part of the cleanup process at RMA.
The Army will continue to keep you informed about RMA activities and meetings. If you wish to discuss your concerns in more detail, please contact Mr. Tim Kilgannon at the number listed below.
The Offpost Proposed Plan identified only two-areas to the north and northwest of the Arsenal boundary that require cleanup. In these north and northwest areas, only groundwater, which is water beneath the ground surface, requires cleanup. Montbello is not affected by RMA groundwater because groundwater travels to the north and northwest from the Arsenal and not south toward Montbello.
Any other questions regarding the Offpost Proposed Plan may be directed to Mr. Tim Kilgannon of this office at 289-0201. Thank you again for your cornments.
Sincerely,
Eugene H. Bishop Colonel, U.S. Army Program Manager Copies Furnished:
Captain Jonathan Potter, Litigation Attorney, Rocky Mountain Arsenal Building ill, Commerce City, Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of justice, 999-18th Street Suite 501, North Tower, Denver, Colorado 80202 Document Tracking Center, AMXRM-IDT, Room 132, Building 111, Rocky Mountain Arsenal, Commerce City, Colorado 80022 May 19. 1997.
Col. Euaene H. Bishop Procram Manaaer for the Rock:y Mountain "Arsenal Building 111-RMA Commerce City. Colo
Dear Col. Bishop
Concerninq the oi+post oroposal plan for arOUndwater clean-uo of the north boundary containment system. NSCS.
I have reviewed the prooosed plan and understand that the army nlaris to treat the arounowater thru evtraction *IsUsing plan treatment ei _. N-4; 0++post InterceDt and Systems. I believe that there is +our major problems with this olan.
First the length of time to perform the clean-up In N-4 the time frame is 15 to 7_0 years. Yet in -.your proposal N- 5: Expansion of o+fpost Intercept and Treatment System plans onlv 10 to 20 years. After reading both proposals they basically are the same , with N-5 has an increase of croundwater being cleaned-Up at a rate of 90 gpin more. Thank to the increase of ex-traction wells and additional recharge trenches. Tt is my belief that the groundwater may be cleaned uo by use of N-5 with additional potential future moaification as needed to Insure a complete clean-uo . There is no reason that the Army can*t clean-up the groundwater off the Roci.y Mountain Arsenal.
Second is the Army's position that 600 ppb of DIMP is the cnly guidelines needed. I have a personnel believe that 6('(.) ppb of DIMP is not adequate number. This number is inaceauate do to the increase on cancer and k-idney problems of residents within the boundaries of the o+ipost study areas's. Being a +irefighter within the area known as the of4post study area, I have witnessed an increase of cancer, 1-icney or liver problems within this area. Personally my family has been subjected to the Arffo,-*s contamination . either tv air containments. or Oy our water supply for over 77 years watched my Father having to have a 1-1-idney removed and obtain leui.emia cancer and die. My belief is that the standards for DIMP znd tne other chemicals listed in your information sheet ( Table I ) is set to high. If DIMP was the only problem I would still be opposed to the 600 ppb rating. However by the Army*s own determination there are chemicals that have contaminated the land /air/ water leaving the Rocky Mountain Arsenal . EPA's figures are inadequate Third is the Armyý's commItment to continued monitoring program +or private wells. I ast-l-ed both Tri-County and the Army why analytical reports from November 925 we not released. Mr. Charlie Scharmann stated that it taizes months to obtain analytical reports. I find this unacceptable. I know that analytical become unstabie if not properly cared for and most have a period of time when the material being analyzed become unusable. Most analytical laboratories are able to complete -esults within in a period of ten days to two (2) month . Why does it tak-es the Army over eiant -*;B) months to obtain a report, this is beyond me.
Forth is my belie+ that the Army and Shell Oil should provide adequate water supplv to all oi the residents who have had their water contaminated . This does not mean just bottled water . but water service front a South A-dams Water District. The Army has createa a monster for families . there property values have becoi-ne on nonexistence. Their lives have been changed for the worst . And the Army and Shell Oil has not offered to assist the residents who they have effected.
As a final statement and Questions to the Army / Shell Oil Co. 1 would like to know why the Army chose N-4, a system that cost more (by their own determination), takes more time to complete and jeopardizes the residents of Adams County My second Question is why does the Army believe that it is above legal regulations . If the company I work for contaminated groundwater. it would be sued for the clean-up and any hardshio that the residents may have endured and pay fines and Penalties . The last Question is what does the Army / Shell Oil Co. plan to cue for the residents who's ground water they nave effected. 1 believe that the Army must start the clean-up . But using only N-4 plan is only half a plan. Since N-5 follows the same guidelines as N-4 The Army should add additional systems listed in N-5 to remediate the proolem of groundwater .
If there is any addition communication. feel free to call me at the phone number iist below or write to the address listed below.
Sincerely
Carl P. Kern 10020 Havana Henderson. Colorado 8064(i-84Zý,9 70Z-288-06506 Office of the Program Manager
Mr. Carl P. Kern - 10020 Havana Henderson, Colorado 80640-8439
Dear Mr. Kern:
Thank you for your comments. The Army appreciates the many comments received on the Offpost Proposed Plan for Rocky Mountain Arsenal (RMA). Public input is a key part of the cleanup process at RMA. I will respond to your comments in the order we received them.
Alternative N-4 was chosen as the Army's preferred alternative over Alternative N-5, an expansion to the Offpost Treatment System, for two major reasons. The Offpost Treatment System, a major component of Alternative N-4,is already in operation has been for five months. Secondly, the most important component of the preferred alternative, N-4, is the flexibility of improving the Offpost Treatment System as the Army evaluates its performance. For these reasons, the Army selected the use of operational data as a basis for any future expansion of the Offpost Treatment System (Alternate N-4) instead of using a computer model as a basis for any expansion as called for in alternative N-5. With the flexibility of N-4, water monitoring results will show the Army how best to shorten and improve the cleanup time frame in the offpost area. which may include the addition of more extraction and recharge wells or trenches. Finally, the Offpost Treatment System was designed with extra capacity so that additional wells can be connected if determined necessary.
One of the major concerns to offpost residents is the DIMP contamination in offpost groundwater. Since my tenure began at RMA, I have made sure that the Army conducted further assessment of the DL%IP tests to evaluate whether the U.S. Environmental Protection Agency (EPA) DMIP Health Advisory of 600 parts per billion is safe. Overall. Army has conducted more than 30 separate animal studies with DRYIP, including one studv with humans. The EPA and the National Academy of Sciences evaluated all health studies and concluded that the EPA's 600 parts per billion Health Advisory is protective of human health and the environment In addition, the Army evaluated all possible ways DUvIP and other chemicals could enter the human body. These tests again showed that the water offpost is protective of human health and the environment- As an additional protective measure, the Offpost Treatment System and the North Boundary System will. treat the groundwater to less than 10 parts per billion.
The Army is currently evaluating the applicability of the 8 parts per billion level that the Colorado Water Quality Control Commission is expected to promulgate in the next several months.
The EPA conducts extensive analyses before setting safe chemical standards. The Army, like other Superfund cleanup sites, must follow the guidance and regulations the EPA has selected. If you have further questions regarding EPA's standard-setting criteria, I suggest calling the Denver Office (EPA. Region VIM at (303) 294-7559 for information.
I apologize for the poor turnaround time on the private well results. Since the beginning of this year, the Army has refined the sampling and analysis process so that well results can be given to each homeowner more quickly. The turnaround time from well sampling to well results will still take approximately three months to complete because of the laboratory quality control and quality assurance that is done for each chemical sample. The laboratory quality control and quality assurance ensures that the chemical results are correct. The turnaround time, from well sampling to chemical results, will be much improved than it has in the past.
The Army has committed to treating groundwater offpost with Alternative N- 4. with improvements as necessary. This alternative will achieve clean up levels that are more strict than EPA's own health guidelines, based on the Offpost Risk Assessment The Army believes that this will benefit offpost residents for many years to come. As the groundwater aquifer becomes cleaner, everyone offpost will benefit. The Offpost Risk Assessment evaluated all ways of exposure through water, soil. sediment, and air, and showed that residents offpost are living well within EPA's safe health guidelines.
Finally. the Army is required to follow all applicable federal and State of Colorado regulations, as any other Superfund site must do. Any other questions regarding the Offpost Proposed Plan may be directed to Mr. Tim Kilgannon of this office at 289-0201. Thank you again for vour comments. Sincerely, Eugene I-L Bishop Colonel, U.S. Army Program Manager
Copies Furnished:
Captain Jonathan Potter, Litigation Attorney, Rocky Mountain Arsenal Building ill, Commerce City, Colorado 80022 Mr. Bradley Bridgewater, U.S. Depart3nent of justice, 999-18th Street, Suite 501, North Tower, Denver, Colorado 80202 Document Tracking Center, ANORM-IDT, Room 132, Building ill, Rocky Mountain Arsenal, Commerce City, Colorado 80022 AA7**t7ýý x9
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Mr. Jess Masunaga 10730 Brighton Road Henderson, Colorado 80640
Dear Mr. Masunaga:
Thank you for your comments. The Army appreciates the many comments received on the Offpost Proposed Plan for Rocky Mountain Arsenal (RMA). Public input is a key part of the cleanup process at RMA. I will respond to your comments in the order we received them.
One of the major concerns to offpost residents is the DIM? contamination in groundwater. Since my tenure began at RMA, I have ensured that the Army would- further study the DRAP tests to evaluate whether the U.S. Environmental Protection Agency (EPA) DIMP Health Advisory of 600 parts per billion is safe. Overall, the Army has conducted more than 30 separate animal studies with DIMP, including one studv with humans. The EPA and the National Academy of Sciences evaluated all health studies and concluded that the EPA's 600 parts per billion Health Advisory is protective of human health and the environment. In addition, the Army evaluated all possible ways DDAP and other chemicals could enter the human body. These tests again showed that the water offpost is safe for consumption and for the environment. As an additional protective measure, the Offpost Treatment System and the North Boundary System will treat the groundwater to less than 10 parts per billion. The Army is currently evaluating the applicability of the 8 parts per bfllion level that the Colorado Water Quality Control Commission is expected to promulgate in the next several months.
Based on our current data, all residents in the offpost study area are drinking water that meets all applicable or relevant and appropriate federal and state regulations. The Army continues to extensively monitor drinking water wells in the offpost area. If levels of Arsenal-related chemicals were to rise above health guidelines in the drinking water for any resident. the Army will provide an alternative water supply to that resident. ------
Any other questions regarding the Offpost Proposed Plan may be directed to Mr. Tim Kilgannon of this office at 289-0201. Thank you again for your comments. Sincerely,
Eugene H. Bishop Colonel, U.S. Army Program Manager
Copies Furnished:
Captain Jonathan Potter, Litigation Attorney, Rocky Mountain Arsenal Building ill, Commerce City, Colorado-80022 Mr. Bradley Bridgewater, U.S. Department of justice, 999-18th Street, Suite 501, North Tower, Denver. Colorado 80202 Document Tracking Center, ANDORM-Mr, Room 132, Building ill, Rocky Mountain Arsenal, Commerce Citv, Colorado 80022 lb
pro~ ..A PUBLIC COMMENT U. S, Army s "Proposed P I an f or the Of fpost Study Airea" Colonel Eugene H. Bishop, RMA Bldg. 111, Cmmerce City, Colorado 8002.2-2180
I am a resident of the "Offpost Study Area" and am directly affected by contamination frcm the Rocky Mountain Arsenal. I join with others in my =nmAnity in opposing the AMR/ , 3 proposed plan. We urge that it be amended to address broad =miunity concerns with a caTyrahensive solution to widespread contamination problem that the Army and She] I Chemical ocnipany have failed to address, to date, and which.currently poison domestic water supplies and private property for miles to the north and northwest of the Rocky mountain Arsenal. Contaminants include deadly pesticides that were banned by the EPA years ago, by-products of chemical warfare agents, and other toxic substances.
I dwvu*od that the U.S. " and She]] Chemical CaTpany develop and implement a plan to: 1) aliminateall current sources of toxic exposurato citizens affected by off-site poisons fran the Rocky Mountain Arsenal; 2) provide a permanent, alternative, uncontaminated source of water to residents with any level of RMA toxins in their water; 3) oonduct a owwahansive offpost soil and water clean-up that meats all applicable federal and state guidelines, including RCRA; 4) that no final "Record of Decision" be issued until the Colorado Water Quality Control Ocnmission adopts standards for unique, unregulated, Arsenal-related poisons, such as "D IMP-; and 5) that the Army wi I I meet or axes" those standard(s) in a] I groundwater clean-up actions on and offpost.
My additional oam-ents about the Army's iruLdequate clew-up plan are these: Men f- C0e\Ce_r-,15 C;
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Vn d LA .,4-%ýC " r- C L.- 1%CL 0 - C'I .56'_ (Cý el 6+ b o A a 5 -Ston e 5 r LA i A _A3 f _-C (sap reverse side for contl*nued c-a=--TrnwB-nr Y, L 4-A e SQ w P I ease send wr i tten ca ...Nx ts in rei-Portseho Z4 urgen4ýý a /, - raised in my oa ...mi ts before a "Record of Decision" is issued regarding offpost Rocky mountain Arsenal poisons.
NNS (Signature)
NMIE (Printed) S2 -,I 19y ADDRESS TCWN ZIP PHONE cc: Les Aspin, Secretary of Defense, vice President Al Gore, Carol Browner, U.S. EPA, Colorado Congressional delegation, chairs of key Congressional oversight caTmittees; Colorado (bvix or Roy Ramr, Attorney General Gale Norton, C[)H Director Patricia Nolan; publ ic madia, DEPARTMENT OF THE ARMY njoopAX MANAM FOR ROCKY MCILMAIN ARSSIAL Commx= CM, O0UXMW WU2-1748 5W
December 9, 1993
AJTPITMC& Office Of the progr:am MAW=
mr. Bennie Muniz P.O. Box 261 E[enderson, C4orado 90640
Dear Mr. Muni=
nank you for your comments. The Army appreciates the many commects recedved on the Oflpost Proposed Plan for Rodq Mountain A=aI MU). Public inpW is a key part of the cleanup process at RMA.
ne prefwed alternative for the Offpost Operable Unit will clean up contamination that came from RMA. The Army Ms spent nine yam stuilymg the bft pomblo way to elimmme potential haft threats offpost. we believe the offpcot P=fixred Alternative goes beyond what is required by the U.S. Environmeatal Protection Agamy (EPA). In 3dditims the Army cannot legally provide offpost residents with a now water zupply because Lng ch=cal health guidelines ae not being exceeded. Ilm Army wilL as it bal In the W4 provi& residents offpost an alternadn water supply, if applicable EPA health pWelim are not being met in their private well water. Finally, the Army bdivw that ag applicable federal and state guidelines are being nut for soil W water oftpost.
One of the major conce= to offpost residents is the D2" contamination in groundwater offpost. Since my tenure bnan at RMA, I wanted to make sure the Army would hirther study ft Me =M to evaluate whether the EPA DIMP Health A&iSOrY Of 600 parts per bffim is safe- Overall, the Army bas Wnducted more than 30 separate aniM21 studies with DEMP, including one study with humans. The EPA Mid the Nadmd Academy of Sciences evaluated all bealth studies and concluded that ft EPA s 6(* part3 per billion Health Advismy is pmectin of hurnan halth and ft enYirontaft. In &Mdm,the Army evaluated all pozible ways DnO and ather chemicals could enter dn human body. Then teas again showed that the water off1post is protective of human halth and the environraent. As an Witional protwtive measure, the Offpost Treat:ment Systm and the North Boundary System will treat the groundwater to less dw 10 puu per billion. The Army is cunwdy evaluating the applicability of the 8 parts per billion level that the Colorado Water Quality Control Comniission is agected to promulgaw in ft next several months. ?IM A 9 J - / 2, ý',3
Readinm u our Profession I hope this inform=on has helped to amm your ==rns- Any odw qwstion, of this office at reprding the Oflpost Proposed Plan may be directed to Mr. Tim Kilgannon 289-Mi. Thank you agdn for your commentL
Sincerlelyt
ene ý,.BishopkL-4- IJ.S. St Army Manaw
Copies Furnished:
Captain Jonathan Po=, Lftation Attomey, Rocky Mountan Arsend Building 111, Commerce City, Colorado W= Mr. Bradley Wdgmaw. U.S. Department of Jus&cý 999-18th Stree4 Suite 50 1, North Tower, Denver, Colorado SM Document Tracldng CentCr, AbMM-WT, Room 132, Building 111, Rocky Mountain Arsenal, Comma= City, Colorado WM Do You Want to be Involved in Protecting This Community and Your Future?
Please take the time to complete the following information to help us compile a community comment that we can submit to the US Army. Name: r 1 f9 167 jv,, s7- Address: V Phone:- 30-3-1wq -01 Are there any unusual health conditions being experienced by anyone in your home? What?
What do you want the Army to do for the area that is contaminated? r-ft Lt-ky '. c- Jý )a& ý4,s re r, n T' 1,
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4. 1 40% ttA%l !FWjLyFARMS E lo,gni AVE 11-295 , CO 90601 13RIGIATON Office of the Program Manager Mr. Glen Murray I 10 10 Havana Street Brighton, Colorado 80601 Dear Mr. Murray: Thank you for your comments. The Army appreciates the many comments received on the Offpost Proposed Plan for Rocky Mountain Arsenal (RMA). Public input is a key part of the cleanup process at RMA. The preferred alternative for the Offpost Operable Unit will clean up contamination that came from RMA. The Army has spent nine years studying the best possible way to eliminate potential health threats offpost. We believe the Offpost Preferred Alternative goes beyond what is required by the U.S. Environmental Protection Agency (EPA). In addition, the Army cannot lecally provide offpost residents with a new water supply because legal chemical health guidelines are not being exceeded. The Army will, as it has in the past, provide offpost residents an alternative water supply if applicable EPA health guidelines are not being met in their private well %vater Finally, the Army believes that all applicable federal and state guidelines are being met for soil and water offpost. One of the major concerns to offpost residents is the DrNT contamination in groundwater offpost Since my tenure began at RNt-V I wanted to make sure the Army would further study the DIMP tests to evaluate whether the EPA DINIP Health Advisory of 600 parts per billion is safe Overall. the Arm% has conducted more than 30 separate animal studies with DRVT, includiniz, one studv with humans The EPA and the National Academy of Sciences evaluated all health studies and concluded that the EPA's 600 parts per billion Health Advisory is protective of human health and the environment In addition. the Army evaluated all possible ways DUVIP and other chemicals could enter the human bod% These tests ap-ain showed that the water offpost is protecti%e of human health and the environment As an additional protective measure, the Offpost Treatment System and the Norih Boundar-, S%stem will treat the groundwater to less than 10 paris per billion The Army is curTent!% e%aluiting the applicability of the 8 parts per billion le%el that the Colorado Water Qualit% Control Commission is expected to promulgate in the next several months I hope this information has helped to alleviate your_concerns. Any other questions regarding the Offpost Proposed Plan may be directed to Mr. Tim Kilgannon of this office at 289- 0201. Thank you again for your comments. Sincerely, Eugene H. Bishop Colonel, U.S. Amy Program Manager Copies Fumished: Captain Jonathan Potter, Litigation Attorney, Rocky Mountain Arsenal Building I 11, Commerce City, Colorado 80022 W. Bradley Bridgewater, U.S. Department of Justice, 999-18th Street, Suite 501, North Tower, Denver, Colorado 80202 Document Tracking Center, ANUMM-IDT, Room 132, Building I 11, Rocky Mountain Arsenal, Commerce City, Colorado 80022 Do You Want to be rnvolved in Protecting This Community and Your Future'i IN 2 us C,:Rafe n rnymm on' Please take the time to complete the following information to help comment that we can submit to the US Army. Name: i-nrn(ý-n Address: 11"C91r) 24s-ý- Phone: -74164-jAer,so v Co. 'KG 6 14 0 What? Are there any unusual health conditions being experienced by anyone in your home? A_Acs I X) v AV, a 5S E -b-- . a Aý t A&Z-1 I/ g #A VI-r- a or, 'ýQ owt (fAKI.5G- A & -f-, tý t lef /6 s A the area that is contaminated? IE4A) Ujo What do you1 want the Arm for I 4& i,ý, b Nct "iv 67 t17" IA W,-, " 1",4 0,/v I*f rAjjý- / 't / 1,qu /9 0 DZi 4=7ý_r a.Z 71yv- e -/ S _& /So A Concerns and or Commsnts fzPC-,M %J,_;// Za ,Ut JV475 III&AE at tir- ý21&L)s ew -7*ý I&M-4 ?444.,1 le ZO q -M lie 4w 5 v 6U67t1,? 7e_11 -/7,e A, 0 1511'e.1 '/AZ4y MAY-7*93 AY-7-93 0. I;/ ro "Vr 7- _ ;?ýkl-016b ýýrL C 631-^lot Mtt / ýý //ý_r A,, , 4, fum. NELS ON jAMES 118 10 E 124TH AVE 80640 HENDERSON, CO Office of the Program Manager Mr. James E. Nelson 11810 East 124th Avenue Henderson, Colorado 80640 Dear b&. Nelson: Thank you for your comments. The Army appreciates the many comments received on tlýe Offpost Proposed Plan for Rocky Mountain Arsenal (RMA). Public input is a key part of the cleanup process at RMA. The preferred alternative for the Offpost Operable Unit will clean up contamination that came from on-post contaminants, including the pesticides you reference in your letter. The Army has spent nine years studying the best possible way to eliminate potential health threats offpost We believe the Offpost Preferred Alternative goes beyond what is required by the U.S. Environmental Protection a Agencv (EPA). In addition, the Army cannot legally provide residents offpost with new water supply because health guidelines are not being exceeded. The Army will, as it has in the past, provide offpost residents an alternative water supply if applicable health guidelines are not being met in their private well water. Finally, the Army believes that all applicable or relevant and appropriate requirements federal and state are being met for soil and water offpost. One of the major concerns to offpost residents is the DRAP contamination in groundwater offpost. Since my tenure began at RMA, I wanted to make sure the Army would further study the DL\EP tests to evaluate whether the EPA DRYT Health Advýisory of 600 parts per billion is safe. Overall, the Army has conducted more than 30 separate animal studies with DINiF. including one study with humans. The EPA and the National Academy of Sciences evaluated all health studies and concluded that the EPA's 600 parts per billion Health Advisory is protective of human health and the environment. In addition. the Army evaluated all possible wavs DINIP and other chemicals could enter the human body. These tests again showed that the water offpost is protective of human health and the environment As an additional protective measure, the Offpost Treatment System and the North Boundarv Svstem will treat the groundwater to less than 10 parts per billion. The Armv is currentlv evaluating the applicability of the 8 parts per billion level that the Colorado Water ýualitv Control Commission is expected to promulgate in the next several months. I hope this information has helped to alleviate your concerns. Any other questions regarding the Offpost Proposed Plan may be directed to Mr. Tim Kilgannon of this office at 289-0201. Thank you again for your comments. Sincerely, Eugene FL Bishop Colonel, U.S. Army Program Manager Copies Furnished: Captain Jonathan Potter, Litigation Attorney, Rocky Mountain Arsenal Building ill, Commerce City. Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of justice, 999-18th Street, Suite 501. North Tower. Denver. Colorado 80202 Document Tracking Center. ANtXRNI-IDT. Room 132, Building ill, Rocky Mountain Arsenal, Commerce City. Colorado 80022 MAY 2 4 May 20, 1993 Col. Eugene H. Bishop Program Manager Rocky Mountain Arsenal Building 111-RMA Commerce City, Colo 80022-2180 Attention: Col. Eugene H. Bishop AMXRM-PM Reference: Proposed Plan For The Rocky Mountain Arsenal OffPost Study Area Citizen Comment The Army has presented a proposed plan on the Offpost in great detail with studies to support their position. The following are areas of comment, question, and concern. The Army has proposed land uses. The Army has proposed land use for development in the future, defining future as now and development as residential and or industrial. "The "Shell" Property on the north side of 96th along Peoria Street and properties at approximately 100th Avenue." Rezoned to 1-2. May 1992 This land was rezoned without public notice as required by zoning practices. Why is this land already rezoned when this proposal is still in the proposed stage? Please explain. The defined zones along E. 96th Avenue to Peoria are already zoned industrial as above thus making the evaluations of land use within these zones incorrect. Industrial zoned land on the north side of the Arsenal places people working in an environment between two treatment plant systems and in some instances less than one mile from the Submerged Quench Incinerator. we are unable to find documentation of industrial development of Army Bases. Please explain why the Army has chosed to develope land-:-on this particular base. Please outline the plan and time frame for development of land north of the Arsenal on E. 96th Avenue from Peoria Street to Highway 2. We are unable to find any information explaining how contaminated land is rendered ready for development. In the offpost study area the only visible changes we have been able to observe is the demolition of homes/buildings and in some areas the planting of anti-contaminate grass. Please explain and clarify. Housing foundations and sidewalks were left in place on properties north of the Arsenal along E. 96th Avenue between Highway 2 and Peoria Street. Please explain and clarify. The Army has proposed health risks and assessment. The Army has identified chemicals of concern in this offpost area. We think based on our own knowledge and exposure that these chemicals are cnly the tip of the iceberg ot in this case' the tip of the plume. As advanced as the testing methods are we think that more research and accurate technology is needed in this area. We now know that we have been exposed to numerous known and unknown chemicals, metals, pesticides, and by products of over a twenty year period. We do not wish at this time to speculate as to which statistic we may be classified as. The Army has proposed remedial alternatives. We feel that measures should be taken to clean up contaminants identified in the ground water. Summary W4 feel that the Army has devoted a great deal of time, manpowert and money in preparing this proposal and in creating an illusion of well-being. Albert M. Ohle/Rarnara Onle P.O.Box 129 Dupont,Colo 80024/0129 333-4510 Office of the Program Manager Albert H. and Barbara Ohle P.O. Box 129 Dupont, Colorado 80024-0129 Dear Mr. and Mrs. Ohle: Thank you for your comments. The Army appreciates the many number of comments received on the Offpost Proposed Plan for Rocky Mountain Arsenal. Public input is an integral pait of the cleanup process at Rocky Mountain Arsenal. I will respond to your comments in the order we received them. I hope my responses to your comments will relieve some of the concerns you both have regarding the Army's Proposed Plan for the Offpost Study Area and treatment of groundwater offpost. Your first comments are in regard to the land use the Army projected for the future in the offpost area. The Army did not rezone areas offpost. The land use projections were used in the Human Health Risk Assessment only. The Human Health Risk Assessment analyzes potential risks from chemicals to the human body. These land use projections in no way mean that the offpost area has been or will be zoned in a particular fashion. The land use projections we established for the Human Health Risk Assessment are the most conservative for every zone we studied in the Proposed Plan. Conservative land use projections are the human health scenarios that could conceivably develop in a certain zone and that could pose the highest risk. Say, for instance. that in zones 3 and 4, where you use to live, the Army projected urban residential land use. According to Adams County and Commerce City projections, the land in these two zones will most likely be industrial/commercial in the future. but the actual land use won't be decided until the land is developed. The Army decided that by using urban residential land use for the Human Health Risk Assessment. we were examining the worst-case risk assessment and thus providing the best cleanup alternative. The Army and the U.S. Fish and Wildlife Service are working cooperatively to cleanup the Arsenal so that it can become a wildlife refuge. No industrial development of the Arsenal will occur. Also, only Commerce City and/or Adams Countv can outline a timeframe for development of land offpost. The Army, through its Preferred Alternative, is cleaning up the offpost area. During the cleanup timeframe, development of land by Commerce City or Adam County may occur as long as complete safety of human health and the environment is ensured. The Army studies supported by the Environmental Protection Agency, show that people residing offpost will be safe. Demolition of homes was completed to install the Offpost Treatment System. The Army is not aware of an anti-contaminate grass. The Army did plant native grass seed offpost, once the demolition of buildings and the offoost groundwater treatment system were completed. This planting was done in order to restore the areas damaged by construction activities. Once residents vacated the premises, the above-ground structures were demolished to avoid potential safety hazards with the abandoned buildings. Since the sidewalks and foundations pose no safety haza d, they were left in place. The health risks presented in the Offpost Proposed Plan are present-day risks. in the offpost area without accounting for cleanup that is being accomplished by the Offpost Treatment System. The Army has committed to the Offpost Groundwater Treatment System, any necessary moýifications to the system, and continued monitoring offpost as part of the Preferred Alternative. As the groundwater treatment svstems; continue to operate. risks to human health and the environment will further decrease. The Army believes that evaluation of the contaminants and associated human and environmental risks was very detailed. I hope this information has helped to alleviate your concerns. Any other questions regarding the Offpost Proposed Plan may be directed to Mr. Tim Kilgannon of this office at 289-0239. Thank you again for your comments. Sincerely, Eugene H. Bishop Colonel, U.S. Army Program Manager Copies Furnished: Captain Jonathan Potter, Litigation Attorney, Rocky Mountain Arsenal Building ill, Commerce City, Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of justice, 999-18th Street, Suite 501, North Tower, Denver, Colorado 80202 Document Tracking Center, ANfXRM-=, Room 132, Building ill, Rocky Mountain Arsenal, Commerce City, Colorado 80022 2 Office of the Program Manager Ms. Annie R. Redmond 5331 Troy Street Denver, Colorado 80239 Dear Nis. Redmond: Thank you for your comments. The Army appreciates the many comments received on the Offpost Proposed Plan for Rocky Mountain Arsenal (RMA). Public input is a key part of the cleanup process at RMA. The Offpost Proposed Plan identified only two areas to the north and northwest of the Arsenal boundary that require cleanup. In these areas, only groundwater. which is water beneath the surface, requires cleanup. Monthello is not affected by RMA groundwater because groundwater from RMA travels north and northwest and not south toward Montbello. In addition. the Offpost Proposed Plan summarizes the Offpost Health Risk Assessment that was completed. The Offpost Health Risk Assessment showed that Montbello residents are not affected by offpost contamination. Also, an Onpost Health Fisk Assessment will be completed before cleanup begins on RMA. The Onpost Ilealth Risk Assessment will evaluate the health risks to the onpost and offpost plants. animals. and humans before cleanup begins. The Army will not begin cleanup unless it determines that the public's health is protected. An%- other questions regarding the Offpost Proposed Plan may be directed to Mr. Tim Kilgannon of this office at 289-0201. Thank you again for your comments. Sincerely, Eugene H. Bishop Colonel, U.S. Army Program Manager Copies Furnished: Captain Jonathan Potter, Iltigation Attorney, Rocky Mountain Arsenal Building ill, Commerce City, Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of justice, 999-18th Street, Suite 501, North Tower, Denver, Colorado 80202 Document Tracking Center, AMXRM-IDT, Room 132, Building ill, Rocky Mountain Arsenal, Commerce City, Colorado 80022 Mav 8, Offpost Proposed Comments Program Manager for Rocxy Mountain Arsenal Attention: Colonel Eugene H. Bishop Building 111 Rocky Mountain Arsenal Commerce City, Colorado 80022-2180 Dear Colonel Bishop, You have asked me to write a letter exoressing my concern about your water cleanup policies. I greatly admire your cesire and efforts to clean up the Arsenal problem, however in the process, you have practically destroyed an excellent, small, minority owned business. I represent The Fountain of Health. I have been seilino natural artesian water now for 13 years. I sell it for 25 cents per gallon. I have followed all of the rules of the Colorado Deoartment of Health. Because of the ourxtv, the State Deoartment has issued a special waiver saying I DO NOT HAVE TO CHLORINATE. FILTER OR TREAT THE WATER. I was never contacted when you started the program to deliver free water to my customers. The reouirement that this water be delivered to people's homes, should not have been considered one of the reauirements of the orogram. The conly consideration to deliver it to people's home would be, if they are elderly, disabled and cannot drive. The rest of the people should be issued food stamos or some kinc of coumon redeemable anywhere. This would save the tax oayers, literally Millions and millions of wasted Collars. Why should the customers drive here and pay $0.25, when they can have it delivered to their Coor for notnino. This policy has had a devastaing affect on my business. In the winter time I have driven around and taken pictures of piles and piles of frozen and busted Caeorock bottles. I have seen many bottles in o2g owns and horse corrals. This does not seem like a sensible way to handle the proolem. 0 I am a 65 year old American Indian woman. I am too old to start over. I was enjoying my retirement years until you started this program. Now I am devastated. I cannot wait another 30 years for you to clean up your moss. Si77C ýerel Grace Russ I Fountain of Health 13185 Brighton Road Brighton, CO. 130601 659-0800 AM -3 04// 3 Office of the Program Manager Ms. Grace Russell 13185 Brighton Road Brighton, Colorado 80601 Dear Ms. Russell: Thank you for your comments. The Army appreciates the many comments received on the Offpost Proposed Plan for Rocky Mountain Arsenal (RMA). Public input is a key part of the cleanup process at RMA. The Army was not responsible for providing residents with bottled water offpost. The State of Colorado provided bottled water to offpost residents, even though all drinking water from private wells meets e3dsting drinking water regulations. Any other questions regarding the Offpost Proposed Plan may be directed to Mr. Tim Kilgannon of this office at 289-0201. Thank you again for your comments. Sincerely, Eugene IFL Bishop Colonel, U.S. Army Program Manager Copies Furnished: Captain Jonathan Potter, Litigation Attorney. Rocky Mountain Arsenal Building ill, Commerce City, Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of justice, 999-18th Street, Suite 501, North Tower, Denver. Colorado 80202 Document Tracking Center, AN0RNI-IDT. Room 132, Building 111, Rocky Mountain Arsenal, Commerce City, Colorado 80022 tow PUBLIC OOMMENT U.S, Amy's "Proposed Plan for the Offpost Study Area" Colonel Eugene H. Bishop, RMA Bldg. 111, Oormierce City, Colorado 80022-2180 ------_ ___ I am a resident of the "Offpost Study Area" and am directly affected by contamination fran the Rocky mountain Arsenal. I join with others in ny omTminity in opposing the Army's proposed plan. we urge that it be arrwxied to address broad comminity concerns with a ccrivrehensive solution to widespread contamination problems that the Army and She] I Chemical Ompany have f a i Ied to address, to date, and wh i ch current Iv po i son domest i c water supp I i as and private property for miles to the north and northwest of the Rocky mountain Arsenal. Contaminants include deadly pesticides that were banned by the EPA years ago, by-products of chemical warfare agents, and other toxic substances. I demand that the U.S. Army and Shell Chemical Cmpany develop and implement a plan to: 1) el iminata a] I current sources of toxic exposure to citizeris affected by off-site poisons fran the Rocky Mountain Arsenal; 2) provide a pernw-tant, alternative, uncontaminated source of water to residents with any level of RK4 toxins in their water; 3) conduct a compi shensive offpost soil and water clean-up that masts all applicable federal and state guidelines, including RCRA; 4) that no final "Record of Decision" be issued until the Colorado Water Quality Control Ocrrmission adopts standards for unique, unregulated, Arsanal-related poisons, such as "DIMP"; and 5) that the Amy wi I I niest or exceed those standard(s) in a] I gropuiwater cleary-up actions on and offpost. My additional oaments abo4 the Army's inaulaquate clean-up plan are these: 1,0ý 0, 0 ab P &MS LA.; LCZ-1 &-pmS S azz a- k6 (see reverse side for con inued caý... a Please send written camients in responss to tk* urgent concerns raised in my owments before a -R d of Decision" is issued regarding offpost Rocky Mountain Arsenal poisons. NAME (Signature) k__3 KAM (Printed) 7ýV 069 vo ADDRESS TOWN ZIP PHONE cc: Los Aspin, Secretary of Defense, Vice President A] Gore, Carol Browner, U.S. EPA, Colorado Congressional delegation, chairs of key Congressional oversight corrmittees; Colorado Goya . Kx Ray Romer, Attorney General Gale Norton, COH Director Patricia Nolan; pub] ic media L W a.A- ýJ6 /OxJ DEPARTMENT OF THE ARMY PROGRAM MANAGER FOR ROCKY MOUNTAIN ARSENAL 50* COMMERCE CrrY. COLORADO 8X22-1748 December 9, 1993 RVLY TO ATTVMON OF: Office of the Program Manager Mr. and Mrs. Roger Sable 12270 Brighton Rd. P.O. Box 161 Henderson, Colorado 80640 Dear Ms. Sable: many comments received Thank you for your comments. The Army appreciates the Public input is a key on the Offpost Proposed Plan for Rocky Mountain Arsenal (RMA). comments in the order we part of the cleanup process at RMA. I will respond to your received them. contamination in groundwater One of the major concerns to offpost residents is the DIMP sure the Army would further offpost. Since my tenure began at RMA, I wanted to make Protection Agency (EPA) study the DIMP tests to evaluate whether the U.S. Environmental Army has conducted more DIMP Health Advisory of 600 parts per billion is safe. Overall, study with humans. The EPA and than 30 separate animal studies with DIMP. including one and concluded that the EPA's the National Academy of Sciences evaluated all health studies health and the environment. In 600 parts per billion Health Advisory is protective of human chemicals could enter the addition, the Army evaluated all possible ways DIMP and other is protective of human health human body. These tests again showed that the water offpost Offpost Treatment System and the environment. As an addiLonal protective measure, the than 10 parts per billion. and the North Boundary System will treat the groundwater to less billion level that the The Army is currently evaluating the applicability of the 8 parts per in the next several Colorado Water Quality Control Commission is expected to promulgate months. water that Based on curTent data, all residents in the offpost study area are drinking requirements. The Army meets all applicable or relevant and appropriate federal and state area. If levels of continues to extensively monitor dnrJang water wells in the offpost the drinking water for any Arsenal-related chemicals were to rise above health guidelines in resident, the Army %%,Ill provide an altemate water supply to that resident. Readiness is our PTofession to Mr. Tim Any other questions regarding the Offpost Proposed Plan may be directed Scharmann both Kilgannon of this office at 289-0201. Mr. Kilgannon and Mr. Charles listed above. Thank spoke at the Public Meeting. They can both be reached at the number you again for your comments. Sincerely? Eugene . Bishop Colonel, U.S. Army Program Manager Copies Furnished: Captain Jonathan Potter, Litigation Attorney, Rocky Mountain Arsenal Building 111, Commerce City, Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of Justice, 999-18th Street, Suite 501, North Tower, Denver, Colorado 80202 Document Tracking Center, AM)GM-IDT, Room 132, Building 111, Rocky Mountain Arsenal, Commerce City, Colorado 80022 June 21,1993 Leif R. Southwell 11355 N'Racine CT Henderson Co, 80640 Proposed Plan Comments Offpost Arsenal Program Manager For Rocky Mountain Attn: AMXRM/ Col. Eugene Bishop Building 111-RMA Commerce City, Co 80022-2180 Re: Comments Dear Sir, BACKGROUND people by Congress and therefore the American The Army is authorized nation. None of the above develop weapons for the defense of our to nation. authorizes the Army to pollute our addiction for weapons which has The Army has pursued a cocaine like for the environment. In the case of resulted in a blatant disregard of and haphazardly dumped the by-products RKA the Army casually the contents were warfare into evaporation pond(s) where chemical table. allowed to leak directly into the water 1980' operation from the 1940's to the mid Since the Arsenal was in full gailons remediation was to pump 110 million the Army's only act of crust by-product 5 miles deep into the earth's of the weapons earthquake. causing the first and only known man-made to protect the environment Army has never had a viable plan either The discovered by an outside. or tne surrounding residents until it was entity that drinking water was contaminated. FIND:NGS per EPA refer to scientific levels of parts The Army and the contaminated testing for some 34 chemicals which have billion when are guesses only, as: residents drinking water but these standards on the effects of A. Thor* are no long term health studies chemicals such as DIMP. effect on humans of B. There have been no studies done on the the combination of these chemical. constantly changing as an example during the Scientific data is "down wind" in the bomb the military told residents testing of Atomic false the bomb would not harm them. This was totally Utah that some 40 years later. as the military admitted this was inaccurate on TV during the 1950's advocated school children Advertisments of an Atomic Bomb attack. to hide under their desks in the event Another totally false assumption. w4s - to the RMA and projections once again many of these chemicals are unique not acceptable. from recent labratory tests on rats are CONCLUSION have somehow decided that current unsubstantiated The Army's and EPA efforts. pollution are acceptable for offsite remediation levels of not been is not comprehensible considering the Army has This 51 years at the RMA. subject to any rules or laws during the last Why -are guidelines suddenly being invoked now? from the RMA Short term health studies on chemicals leaked be accurately which only exist at this site cannot possibly determined. impacted area The Army has an obligation to the citizens of the water as it was before the pollutants were to make the drinking water to leak from the RHA and to infiltrate the ground allowed cannot be and aquifers. Since the goal of safe drinking water even for deep wells the only alternative remaining safely achieved is never would be a municipal type water supply. This alternative the proposed plan since the Army and the EPA have considered in as seriously erred in their methodology by'accepting "guesses" scientific fact. Leif R. Southwell DEPARTMENT OF THE ARMY PROGRAM RANAGER FOR ROCKY MOLN"rAIN ARSENAL 50* COMMERCE CTTY, COLORADO SX22-1748 December 9, 1993 REM TO A7ITv,-no,4 c)f. Office of the Program Manager Mr. Leif R. Southwell 11355 North Racine Court Henderson, Colorado 80640 Dear Mr. Southwell: Thank you for your comments. The Army appreciates the many cominents Public received on the Offpost Proposed Plan for Rocky Mountain Arsenal (RMA). to your comments in input is a key part of the cleanup process at RMA_ I will respond the order we received them. chemicals The Army evaluated the long-term and cumulative health effects of the In fact, the offpoSL These effects were anal)zed in the Offpost Risk Assessment. offpost to Offpost Risk Assessment evaluated the cumulative risks of contamination Plan are the humans over a 70-year period. The risks presented in the Offpost Proposed of operating the long-term risks of the chemicals offpost without considering the benefits Offpost Treatment System. One of the major concerns expressed by offpost residents is the DIMP to conLurlination in gToundwater offpost. Since my tenure began at RMA, I wanted U.S. make sure the Army would further study the DIMP tests to evaluate whether the Environmental Protection Agency (EPA) DINIP Health Advisory of 600 parts per billion is safe. Overall, the Army has conducted more than 30 separate animal studies with D1114P, including one study with humans. The EPA and the National Academy of Sciences evaluated all health studies and concluded that the EPA's 600 parts per billion Health Advisory is protective of human ýealth and the environment. In addition, the Army evaluated all possible ways Dl.%fP and other chemicals could enter the human bodv. These tests again sho%%-ed that the %Lweroff.post is protective of human health and the enviro=ent. As an additional protecu%e measure, the Offpost Treatment System and the North Boundary System will treat the groundwater to less than 10 parts per bil.lion. The Army is currently evaluating the applicability of the 8 parts per billion level that the Colorado Water Quality Control Commission is expected to promulgate in the next several months. Readiness is o-ur PTofession other questions regarding the hope this information alleviates your concerns. Any Kilgannon of this office at Offpost Proposed Plan may be directed to Mr. Tim (303) 289-0201. Thank you again for your comments. Sincerely, Eugene . Bishop Colonel, U.S. Army Program Manager Copies Furnished: Arsenal Captain Jonathan Potter, Litigation Attorney, Rocky Mountain Building 111, Commerce City, Colorado 80022 Street, Mr. Bradley Bridgewater, U.S. Department of Justice, 999-18th Suite 501, North Tower, Denver, Colorado 80202 111, Rocky Document Tracking Center, A.MX?,14-IDT, Room 132, Building ?4ountain Arsenal, Commerce City, Colorado 80022 MAY20M May 14, 1993 Offpost Proposed Plan Comments Program Manager for Rocky Mountain Arsenal Attn: AMXRM-PM/Col. Eugene H. Bishop Building 111-RHA commerce city, Colorado 80022-2180 Dear Sirs: I am submitting these comments on behalf of my mother, Irma L. Temmer, who resides at and owns the property at 16250 E. 104th 0 Avenue, Commerce City, Colorado 80022. 1 have enclosed a copy of a document entitled "State Concerns" prepared by the Colorado- Department of Health, dated April 1993. We agree with the concerns stated in this document and adopt it as part of our comments. In addition we believe the Army should be responsible for all clean up, even if poor well construction or maintenance may have contributed. The pollution would not have occurred if- the chemicals would not have been allowed to migrate off the Arsenal. The state tests show that this has happened, so the Army should clean it up. /Robert E. TeLmar For: Irma L. Temmer .C0 3tate Concerns **0. 1876 .6 Colorado On the Rocky Mountain Arsenal Department Offpost Proposed Plan of Health April 1993 1. What is the Offpost Proposed Plan? the cleanup method selected. Federal Superfund law The plan was created by the U.S. Army to describe requires the Army to provide this plan to the public so risks associated with contamination to the north and that you have a chance to give your opinion. You northwest of the Rocky Mountain Arsenal, explain the may have recently received a fact sheet from the Army cleanup alternatives that were considered, and identify which is a summary of the Proposed Plan. To review a copy of the entire 12-page Proposed Plan, contact the - EVLAmnoN Army, the Colorado Depart- ment of Health, EPA, or local libraries. If you would ewý; like your own copy of the plan, please call the Colo- rado Department df Health M! (CDH) at 692-34 10 and leave a message. We will send you a copy. 2. What area does the Offpost Proposed Plan Zone 4 cover? The figure below shows the area covered. This area was Zone 3 defined in 1989 based on zone 6 known areas of contamina- tion and the predominant ground water and surface water flow patterns. No additional offpost investiga- tion related to the Arsenal is ;-Nava &.-a" %Cky moumain expected. 3. Does the state s p_ WNW port theplan? Why or aw" LW& why not - The state has many con- Loom Lava cerns. *Below are the most 1- significant: Protectiveness of the Proposed Remedy Rocky Mountain Arsenal According to federal law, 'n'd Offposi Study Areas appropriate clean-up levels .)n existing state and federal environmental Eke the Army to evaluate active remediation of the ,s, if they exist. In addition, risk assessments soil and at the very least initiate estimate measures which cancer and non-cancer risks are used would preveirit exposures to ground water until it is -jetermine clean-up levels when environmental laws cleaned up. ather do not exist or are not considered to be protec- tive at a particular site. A risk assessment compares DIMP in GroundW2ter the levels of contamination to EPA-established num- In 1990 bers to determine the state requested that the Water hazard indices for non-cancer risk. Quality Control Commission set Cancer risk is established through a ground water excess cancer risk standard for DRAP (diisopropylmethylphosphonate), a predictions. An "excess" cancer means a cancer in byproduct of nerve addition gas production at Rocky Mountain to the predicted cancer risk. According to Arsenal. A current EPA Health the American Cancer Society, Advisory Level of one in three of us will 600 ppb has been used by the Army to determine what develop a cancer sometime in our lives. The state has areas of ground water concerns with what should be cleaned up. The the Army considers acc:ptable Army will consider cleanup only in risk. These concerns are explained those areas where below: DEMP levels are greater than the EPA Advisory Level. The state believes that a more conservative figure CancerRisk should be used. Zones 2, 3 and 4, as depicted on the illustra- The Army has asserted that the part of the tion, are the most highly contaminated are2s of the ground of1post water plume Aith DIW concentrations above study area. Contamination has been found in 600 ppb has not moved ground water, soil, and past their Offpost Intercept surface water. At current and Treatment System. The most recent concentrations such contamination, according testing done to the by CDH has found 800 ppb DD-4P in a private well at Army's studies, could pose excess cancer risks of approximately least 1/2 mile past the proposed intercept system, 3 in 10,000. The Army states that indicating that DIM? potential risks as high well above EPA's Health Advi- as I in 2,000 are acceptable. sory Level is already in private drinking However, the state believes that federal water sup- law requires plies. The-well owner was already receiving bottled Superfund cleanups to aim for an excess cancer risk of not water from the state. The state believes the Army more than I in 1,000,000, unless that number should address cannot be achieved. the significantly elevated level of DIMP contamination which has moved beftind the offpcist intercept and treatment systtcrn. Non-Cancer Risk Bottled water Federal law states has been provided since July that hazard indices refleirting IM to more than 600 residents with non-cancer risk should not exceed one. The DUO in their Proposed well water. This water has been paid for by the state Plan 'ndicates that the hazard index exceeds one in of Colorado, ZoQ1 2, 3 and with costs shared the first year with 4 and a portion of Zone I Tlus means EPA. Due to the widespread that people exposed to existing nature of DEW con- contarrunation in those tarnination in the offpost, the state believes areas could suffer adverse health effects otýer than that the Army should provide all residents in the study area a cancer, ranging from short-term effects such as eye pcrmanent, and skin municipal water supply. imitation to long-term effects such as asthma, liver or kidney damage. The state believes that the Cont2mination of the Deeper Aquifer risk should be reduced at least to the hazard index one. of Since 1990, testing by the state has revealed that DIMP is present in the deeper Arapahoe aquifer ai depths greater than 100 feet. The Access and Use levels found range fror; a trace to 39 *7 ppb. The state Zones 3 and 4 are owned by Shell Od Com- has identi- pany; fied approximately 20 domestic use wells that should Zone 2 is mostly privately owned. The Pro- be closed posed Plin does because they may be allowing contamination not include active cleanup of sod in to move down to these three zones. In addition. ground the deeper aquifer. The Army has water contam- not closed any of these wells, and nationwill likely remain there for decades wtWe It the Proposed Plan gradually u does not address this problem. The Army has argued flushed by water treated at the North that contamination Boundary System. The Proposed of the deep aquifer is a localized Plan does not occurrence, that it is due to poor private provide any mechanism for preventing people from well con- drinking ground struction and is therefore not its responsibility. The water while it is being cleaned up. Army believes Nor is ýhere a comraitment to that only wells with more than 600 ppb provide access and use should be closed, while D&EP controls (like deed and well restrictions) to in lesser, but signifi- exposure prey= cant, quantities continues to move into to water or soils. Therefore, the state would the Arapahoe aquifer. The state would like the Army to close Page 2 ells to protect the Arapahoe aquifer from 4. What role does the state have in the .Itamination. Proposed Plan? The state and the public have a similar role at this Ground Water Cleanup Action stage of the process. The Army must consider state, The Proposed Plan states that it will take local government and community comments to the ,jroximately 15 to 30 years to cleaiNp the ground Proposed Plan before the Record of Decision (ROD) .rater in the northern plume. However, the Army's is issued. The state has reviewed and commented on supporting documents state that it is not actually aH the supporting documents which led up to the known how long it %%9take; the time estimates are Proposed Plan; the Army is therefore very familiar only for comparing relative timeframes between with the state's concerns. To date, however, the alternatives. The state believes that the Army has Army has not I-Wriaged the Proposed Plan to address significantly underestimated the actual time that will the state's concerns. It is therefore essential for the be required. Also, the Army eliminated a cleanup public to contribute its views during this review. alternative (Alternative N-5 in their Proposed Plan) that it estimated would reduce the cleanup time to 10 5. What happens next? to 20 years, a one-third reduction. This was based on All comments received will be reviewed by the Army the fact that this alternative would require one more and EPA. Responses to all comrnents%ý,rill appear in a year to put into place. In addition, the Army states it document called the ROD. The Army plans to release prefers Alternative N-4 because it allows the Army to this document October 3 0, 1993. This ROD an- make improvements to the ground water cleanup nounces the selection of the final clean-up alternative. system as needed; but according to the Army's Feasi- This will be the "final word" on cleanup for the bility study, so does Afternative N-5. Alternative N-5 offpost; no public comment period or public meetings would actually cost less because it would clean up the are required on that document. ground water more quickly. The state believes that the Army should design a more aggressive system that 6. How can I voice my opinion? will clean up the ground water faster. The public comment period on the Proposed Plan is from March 21, 1993 through May 21, 1993. Please State Ground Water Standards mail your comments to: Offpost Proposed ?Ian Com- Under federal law, state environmental stan- ments, Program Manager for the Rocky Mountain dards which meet certain criteria must be used at A.-s=al, Attn: A_NCQkM-PN4/ Col. Eugene H. Bishop, Superfund sites. The Army does not plan to use state Bldg. I II -RMA, Commerce City, CO 80022-2180. ;tandards in the offpost cleanup, saying there is The state would appreciate copies of written com- 'inconsistent application and ambiguous language". ments submitted on the Proposed Plan which are These standards, however, are enforced at all other submitted to the Army. We urge the public to attend Superfund sites in Colorado. and have been used by a meeting on the Proposed Plan to be held April 28, he Armv Itself for earlier ground water cleanup at the 1993ý 7 v.m.. at the DuRont Elementary Scýh_-ool. 7970 RNiA- the state wants the Army to recogruz these Kimberly Street. Commerce Ci . This comment standards for cleanup in the of1post. penod is your only opportunity to comment on the Army's proposed plan. Surface Water The surface water in First Creek currently has ontamination that exceeds several state surface water tandards. The Proposed Plan does not address surface water because the Amy maintains that if More Information -round water is clearied up as it leaves RMA, it %krill For a copy of the 12-page Proposed Plan, or to ask ventually cleanse First Creek. The state agrees that additional quemions or express concerns related to the trýs action will have a beneficial effect on First Creek Proposed Plan, call the CDH RMA Team at 692-34 10 water quality since ground water seeps into First Ireek during part of the year, but there and leave a message, and appropriate team member is no clear will respond. Or you can call Marion Galant, Commu- -Stimate as to how long this cleansing process will nity Relations Manager, at 692-3304. take. In the meantime, the contamination will con- nue to migrate into O'Brian Canal and ultimately into arr Lake. The state wants the Army to commi't to further water sampling and to attempt to -.Irface water standards. meet state Page 3 Office of the Program Manager Mr. and Mrs. Robert E. Temmer 16250 E. 104th Avenue Commerce City, Colorado 80022 Dear Mr. and Mrs. Temmer: Thank you for your comments. The Army appreciates the many comments received on the Offpost Proposed Plan for Rocky Mountain Arsenal (RMA). Public input is a key part of the cleanup process at RMA. I will respond to your comments in the order we received them. Enclosed is a copy of the Army responses to State comments. The State's comments are also included with the responses for easier reading. The State's comments include the items listed in their fact sheet titled "State Concerns". The Army continues to monitor offpost wells and will do so until the groundwater (water beneath the ground surface) is cleaned to applicable federal and state regulations. Currently, the Armys criteria for well closure, which was approved by the U.S. Environmental Protection Agency (EPA), provides for closure of wells under sppcific conditions. The first condition requires that a poorly constructed or damaged well be identified. Second, the upper groundwater aquifer must be exceeding EPA standards for one or more chemicals. Third, the upper aquifer must be leaking into the lower aquifer because of the poorly constructed or damaged well. If all of these conditions are met, the Army will close the offpost well. Additionally. many wells offpost are no longer being used. The Army is currentlv working with the State of Colorado and Tri-County Health Department to discuss how we will work together to close abandoned wells offpost. Any other questions regarding the Offpost Proposed Plan may be directed to Mr. Tim Kilgannon of this office at 289-0201. Thank you again for your comments. Sincerely, Eugene H. Bishop Colonel, U.S. Army Program Manager Enclosure Copies Furnished: Captain Jonathan Potter, Litigation Attorney, Rocky Mountain Arsenal Building ill, Commerce City, Colorado 80022 Mr. Bradley Bridgewater, U.S. Department of justice, 999-18th Street, Suite 501, North Tower, Denver, Colorado 80202 Document Tracking Center, ANiXRM-IDT, Room 132, Building ill, Rocky Mountain Arsenal, Commerce City, Colorado 80022 Appendix 0 INSTITUTIONAL CONTROLS M9800113 500920-3 1.0 OFFPOST INSTITUTIONAL CONTROLS Operable Unit (OU) Record of Tlus Appendix to the Rocky Mountain Arsenal (RMA) Final Offpost OU selected remedy. The combination Decision (ROD) presents the institutional controls for the Offpost in the ROD and the Final Offpost of Alternative N-4 and NW-2 is identified as the selected remedy Offpost OU and is described fully in Endangerment Assessment/Feasibility Study (EA/FS) for the RMA the following objective for institutional the Section 9.0 of the ROD and in the EA/FS. The ROD identifies of the use of the ground water controls as a component of remedial action in the Offpost OU: prevention system remediation goals . underlying areas of the Offpost OU exceeding groundwater containment regulatory authority over certain The State of Colorado and the local S wernmental agencies that have that significantly limit or prevent activities in the Offpost OU land area have several current regulations of Alluvial [Unconfined] use of the groundwater from the alluvial aquifer. Attachment 1 (Controls Water Use, Management, and Aquifer Use, RMA Offpost Operable UrUt) drid Atldchment 2 (Land and the current regulations Approval Processes - Adams County. City of Brighton. Commerce City) provide requirements. Attach- applicable to groundwater use. well coristruzlion. build.-nS permits, and zoning objectives for institutional ment I parlicularly describes tbe, institutional controls relied upon to meet the controls woablishei in the selev,-d remed%- Th.is appendLx identifies the authont%- f-)r u%ý r,f ins'itutional controls under the Comprehensive 42 U.S.C. Environm-2ntal Response. Componsxi, rn in I [.;.it,ih1% Act of 1980, as amended (CERCLA), E9601 I s,-q ind the National Con%nc-n -. P1 in (V__P1. 40 CFR Part 300. Associates B-1-1 '21905 402010 Harding Lawson 1007121495 R02 UNDER CERCLA 2.0 THE USE OF INSTITUTIONAL CONTROLS actions that assure protection of human health Section 121 of CERCLA requires that EPA select remedial that this protection can be achieved and the enviroriment. 42 U.S.C. § 9621. EPA has recognized (Preamble to the NCP, 55 Fed. Reg. 8666, through a variety of methods, including institutional controls [C]). Institutional controls may be an integral 8703 [March 8, 1990]; 40 C.F.R. § 300.430[al [1] [iiij to achieve CERCLA's protectiveness mandate. component of a remedy that is necessary for such remedy 8706, 8711, and 8734). Additionallv, (See for example, Preamble to the NCP, 55 Fed. Reg. at 8703, to protect human health and the institutional controls may be a component of a completed remedy (40 C.F.R. § 360.430[a] [11 [IIIJ [C)-[DI). environment from treatment residuals and untreated wastes. waste is left in place, as it is in most Institutional controls are a necessary supplement when some response actions (Preamble to the NCP, 55 Fed. Reg. at 8706). Preamble, and expressly acknowledges that EPA identifies examples of institutional controls in the NCP institutional controls have a valid role in CERCL-\ cleanups: activities at or near facilities Examples of institutional controls. which generally limit human remain on-site, include where hazardous substances. pollutants. or contaminants exist or will prohibitions, building land and resource (e.g. water) use and deed restrictions. well-drilling however, that institutional permits. and well use advisories and deed notices. EPA believes, CERCLA (e.g., 55 Fed. Reg. at controls have a valid role in remediation and are allowed under 8706. section 121jdjj2j[B]!kkj). issue an Implementation Plan Within runety days of the issuance of the Offpost ROD. the Army will provided for in the ROD. That which %villcontain a schedule for finalization of the Institutional Controls than September 1, 1996. All plan %villprovide that all Institutional Controls w-.11 be in place not later 310 and the FFA. dates contained in that Plan will be enforceable as provided in CERCLA Section Lawson Associates B-2.1 '21905 402010 Harding 1107121895 R02 3.0 SITE DESCRIPTION 1.0 of the ROD and in the A detailed description of the Offpost Study Area is presented in Section by 80th Avenue, the South EA/FS. The Offpost Study Area was defined to include the area bounded of RMA. The Offpost Study Area Platte River, Second Creek, and the north and northwest boundaries and Burlington Ditch from 80th Avenue also includes the surface waters of Barr Lake, the O'Brian Canal, to Barr Lake. of RMA. The Offpost OU consists of the The Offpost OU is a portion of the Offpost Study Area north specifically, the groundwater containment area within the Offpost Study Area that requires remediation; svstem remediation goals exceeding cleanup standards. Harding Lawson Associates B-3-1 '21905 402010 1107113095 R02 Aftachment 1 CONTROLS OF ALLUVIAL (UNCONFINED) AQUIFER USE RUA OFFIXOST OPERABLE UNIT Attachment I U.S. Department of the Army Telephone No: (303) 289-0202 of Colorado, with a map identifying 1. The Army will provide the Office of the State Engineer, State exceed containment those areas in the Offpost Study Area where groundwater could potentially sampling round. system remediation goals. Thi; map will be updated based on each notification program is operating 2. The Army will establish procedures to ensure that the well construction activity to effectively. The Army will inspect, or oversee inspection, of ali well moaitor conformance with the State Board of Examiners well drilling regulations. well constructed in the area of 3. The Army wffl fund analytical sampling of any future domestic contamination, if requested. and Adams County officials with 4. The Army will provide Commerce City, the City of Brighton, State Engineer. The the same map (as described in item No. 1) provided to the Office of the that the map is used Army will make arrangements with these governmental agencies to ensure in the most effective manner possible to reduce exposure to potentially contaminated groundwater. other relevant CBSG at the 5. For new domestic wells with DIMP levels of eight ppb or greater (or SACWSD distribution time), the U.S. Army and Shell Oil Company will pay for hook-up to the SN'stem or provided deep well or other permanent solution. water supply are 6 Additional elements of exposure control and requirements for alternate presented in Section 7.1 of the mam text. SheU Oil Company Telephone No.: (303) 860-8621 under the Shell Oil Company 1 Tc) -liminatp potential exposure to contaminated groundwater (e.g., covenant/ pu,ji-nies. Sh-41 Oil Couipany wil: -x-ý7ui--.ind r--cord proper documentation groundwater wells into any no-cative easement) tor its prnperiws to lij preclude drdling of all such groundwater no longer dliuviai aquifer water undor Shell*s prol--riv for tuture use until remediation goals contains contamination in excPP.idnc- of grnundwater containment system water (e.g., Denver Basin) established in the ROD. ani I ii I dr.% us- of any deeper aquifer remediation goals in containing contamination in in ý*- I c(lun,iwater containment system the U.S. Armv, and the the ROD. The recorded docuw-ni% %h ill I... --:iI,.rceable bv the U.S. EPA, Staip of Colorado, and shill i-," it .;- n ci i r,,;:. with the land. than forty-five days after the 2. D--ýd restrictions on the Sh-!',I vi-ill t,- ti. place no later issuance of the ROD. AI-1 '21905 402010 Harding Lawson Associates 1107121495 R02 Attachment I Colorado Department of Natural Resources Office of the State Engineer - Contact: Steve Lautenschlader is part of the South Platte River Flow System (which 1. Alluvial groundwater in the Operable Unit (uses) will not be approved without is over appropriated). Therefore new large appropriations to be used with water from another aquifer appropriate augmentation plans (replacing the water often quite expensive and hard to get or another off site source). Augmentation plans are approved due to the associated requirements. June, 1972 - One permit for a well. is allowed under 2. On parcels less than 35 acres created prior to [CRS 37-92-602(3)(b)(U)(Afl. This a presumption of no injury to other holders of water rights may be from any aquifer. well is allowed for used inside of one dwelling only and to June, 1972 - This land would only come into 3. On parcels less than 35 acres not created prior to go through the County or City existence by being subdividedZd would therefore have 30-28-101 - a.ka. SB 35). Prior to subdivision process and meet applicable regulations (CRS plan would have to be submitted issuance of any permit a water rights and/or an augmentation seq. and/or CRS 37-92-302(2), et seq.). and approved by "water court." (CRS 37-90-137(1) et issued serve up to 3 homes, irrigation of up to 4. On parcels greater than 35 acres - Permits may be of domestic animals and/or one acre of home gardea and lawn (person use) and watering of no injury to other holders of water livestock. This use is also ailowed under a presumption rights [CRS 37-92-602(3)(b)(U)(A)]. aquifer) of currently permitted or adjudi- 5. Permits will be issued for replacement (into the same cated wells as requested. (CRS 37-90-137(l). US 37-92-602(3).) State of Colorado, Office of the State 6. All wells installation must be done in compliance with and Pump Installation Contrac- Engineer. State Board of Examiners of Water Well Construction or Examiners of Water Well tors. Revised and Amended Rules & Regulations of the Board current version). Construction and Pump Installation Contractors (2 CCR 402-2) (most notice on each well permit application 7. The Office of the State Engineer will include a distinctive The area included in this require- correspondence. each well permit. and each drilling permit. groundwater could potentially exceed ground- ment IS dny part of the Offpost Study Area where the applicant to contact water containment system remedidtion Soals. This notice would require regarding groundwater quality the Tri-County Health Department and the EPA for information groundwater. drid the options provided by the Armv vi avoid use of potentially contaminated Department, EPA, and the 8. Th- Office of the State Engin----r %vill :(,nIa I th- Tri-County Health Army regarding any application cr fwrmit issu-,i with the notice. South Adams County Water & Sanitation District (SACWSD) Water & VVistewater - Contact: Larry Ford District - New Service Area - I. Rules & Regulations - South Adams County Water & Sanitation within the Boundaries February 1992. Application for Service. as well as, Petition for Inclusion Harding Lawson Associates '21905 402010 Al -2 1107121495 R02 Attachment I groundwater for of the District both require that the Property/Parcel owner convey all rights to & 5.0 (5.1.3)]. The each Parcel or Subdivision Parcel to the District upon inclusion 14.0 (4.1.3) abandon the wells District may at its sole discretion abandon right conveyed to it and physically [5.0 (5.1.4)]. in accordance with the above referenced state Water Well Regulations District - E)dsting Service Area - 2. Rules & Regulations - South Adams County Water & Sanitation well as, Petition for Inclu- January 1992 (Updated February 24, 1993). Application for Service, as owner convey all sion within the Boundaries of the District both require that the Property/Parcel inclusion 14.1 rights to groundwater for each Parcel or Subdivision Parcel to the District upon to it and (4.1.3) & 5.0 (5.1.3)]. The District may at its sole discretion abandon rights conveyed of Colorado Water Physically abandon the wells in accordance with the above referenced State Well Regulations [5.1 (5.1.4)]. water service and vice 3. It is the policy of SACWSD not to serve wastewater without providing versa. By-Laws) Adams County Water Quahty Association Management Agency (see attached (Wastewater (DRCOG) Clean Water Plan Amendment, 1991) South Adams County Momber Agencies: City of Commerce City. Adams County, City of Brighton, Water & Sdrutation District. Contact: Board President Harry Tate (Commerce City Councilman) to sewer lines, lift stations Thvý reviews and may approve or rvl-ýct all maior additions or changes is intended an:! F-.1dnI improvements. Essentially any new lin- is considered a major line. This Agency I ---%-- nl hti-- overlap and enCOUrdge Lritergovernmerildl cooperation. Tri-County Health Department C )-itj:i1v T, ni ti,i-% ,r %%'arTen Brown R-- 'culalion NO I-W In fi%i iii-ol S--%%-ave Disposal Systems promulgated by th-- Bomd f 11-alit, ,I Ih- Tri-Countv Health Department FJi.- 1) it.. F-týriarv 1. 1988 l'ursuant to Title 25. Articl- 10. it; t. 104 ('.RS"& Guidelines Adopted by the Colorado li.;. wti, t., I If-dlth Tio. li-dith Officer may refuse to S:Tdll! t .- V.- - tistruction of an individual sewage disposal line and S%st-L wnoro a SP%Vdpe treatment wnrLs i% % ;I it A Wan 400 f+-et of the nearest property t:cjnn-cI;on can be made thereto. S-ct.on III: J 141 i.k.h 30- 1 -1006(i)(a) (Special Districts), 31-35-601 (munizipaloies). 30-20-416 (counti.-O Cjtv of Commerce City Contact: Sl--.-- llausý. Conimuruty Planning Director Lands currently -within the Citv ,I Commerce City -South of 120th Avenue whil,- li.ghway 2 and then further north to the east. '21905 402010 Harding Lawson Associates Al -3 1107121495 F02 Attachment I - Water Facilities (a) General require- "Commerce City Code - Article V. Subdivisions". Section 17-105 SACWSD for either connection to the ments. This section essentially defers water service issues to use of individual wells or community public water supply system immediately or in some cases allows is then required. (see SACWSD above) water systems until lines reach the subdivision when connection and sewer taps (or well permit & approved Building Code (UBC & UPC 1991) - Requires proof of water septic system application) prior to issuance of building permit. City of Brighton Contact(s): Chief Building Official, City Planner between Peoria and State High- - Areas north of 1 20th Avenue including the triangular area way 51, north of 112th/Highway 2 Regulations) "Land Use and Development Regulations and Guidelines" (Zoning is required to provide and connect the "Subdivision Regulations" Section V, (B.) The subdivider lines, ... ) to existing public systems. following utilities (Water lines and fire hydrants, Sanitary sewer and sewer taps (or well permit and approved Building Code (UBC & UPC 1991) - Requires proof of water septic system application prior to issuance of building permit. within the City. Connection to the Water & Sewer service are provided by Brighton Utilities Department within two miles of the current City. murucipal water system may be recommended for developments the final approval by the City Council. However, staff recommendations may not be included as part of Adams County Building Dept. Contact(s): Planning Dept., Director of Planning and Development, Remainder of Lands in the Offpost OU not in Brighton or Commerce City Se(- attached *Development Review Overviewý' Adams County Zorung Regulations Adams County Subdivision Regulations taps (or well permit and approved Builling Code (UBC & UPC 1991) - Requires proof of water and sewer sýp!r: system application) prior to issuance of building permit. distance, however, these Staft r-commends connection to public water and sewer if with a reasonable or Board of County r-c,,rumendai ions ma% not be retained by either the Planning Commission Commissioners. Lawson Associates '21905 402010 Al -4 Harding 1107121495 R02 Attachment 2 LAND AND WATER USE, MANAGEMENT, AND APPROVAL PROCESSES ADAMS COUNTY, CITY OF BRIGHTON, COMMERCE CITY Ads= CountY Lmd =d Water Uqcý Management and Approvid Proe"M Is the yroperm R=gft =ied fnrbR im=ded use? ya Ahneaw No* (U30 by Ri&) Seek approval for C=Wif=d SeekR=m3ing Tbis, n== do -&mad use use This requir a soffmview; a is appropriate based an the Ibis req=vs a staffreview. a PL=cmg ComnnsPon hewmg currem =mmg of dw properw PL==g Conzmmm h=m and an Rvmvg by ft Board zod an mnoval by Ilm Board ofCounly Cn=ý MrS ofCOUMyr "Mic6m.-M ProceedtotheBlArN DeparunemifApproveid Coaddians may be pla=d ar removed as pat of zbe approval of &e use at the PI Coamnssim or Baud of Couiny Cam:miwiwers levels. Comm=n am schcrted fmm odw Agamews; (local and sme) Buildin Deparcmm= Budcfmg permit process (UBC 1991, UPC 1991) A ,za= wzz= md mcd3od of sewage doposal we required pEiar to Lnum= of a Bmldmg ftmait Waxer Sewer Public Wa= Supply Public Sewer Cuatudy u%-;,ble ca =e Curremly wivilable an s:ýz Yes Yes Mgbmm or SACWSD Bdgh= or SACWSD No NO CziocadD DaPmrmu= of Nzwral Rcsourom Sepdc system(TCMD) Off= Ct ft SM: Fn Weil pCM= wia be &=md if ;ssucd CQMIm=Mrty Weil system Pfivwx We7d City of Brighten Land and Water Um Management and Approval Proce&vs is the gm= jzMaly zoned for the intended use? yes Au"e No& (Use by Ri&) Seek approval for Seek Rezoning This m=w the intended use Conditional Use This requires a staff review, isapprapdin based onthe Tbisequiz astaffreview, a Pl*-rin C . .on cumut zming of the a Plzrzoing Cornmi3sion hearing and an approval by property hearin and an approval by the city Council the Cirv C uncil Proceed to the BuDdiag Department if Approved Coniftoot may be placed or removed on the property use at the Planning Commission or city Council level& C are solicited ftm other Ageti-as (local and state) Bdkrmg Department Building permit proce= (UBC 1991, UPC 1991) A wuw source and nxdwd of wwage disposal are required prior to im,- of a Building Permit Water Sm" Public Water SW* Public Sewcr Curready available an site Currently available m site Yes Yes Bfigh= Uu-Bf= Br*l=n Urflities No No Brighton UtII;t;M Brigbion UtiW= Frtmd mains after &pprvv&l Ruendxmin after approval by the Ads= Counry Water Quality Association No Czkuzdo Department of'Nimra I No Resources, Septic. System (TCHD) Office of the State Fzgýnacr WcU perwat will be fiagged if kstwd Conmwnity Wel Syst= or Priv= WcI Commerce (3ty LandAnd Water Use, Lru,6 and ApproW Procenes Isthe 2M2= 2Tq=fy zaced fm the kaeuded we Y" ALr me* (UwbyRi&) Seek ýVoval for SGIk P,=D=g This meam the intended use ise Thu requaw a Stiff review, is qMropnge basedOU ft This =Wýs a staffrwhew, a Planning Cmnzwlion Carrew Zoning Ofthe a P C;onnnhabon beedn and an approval by Property hcuiwzýgý w q*wval by the City C=noil the Council Prooeed to the icr Departmesn if Approved rV,.fiti may be placed or rcmoyed ol the propany un at the Plx=ing r-wranissino or city Council levelL am solicited from othm ASeo =es (local and s=) Bundiag n I BUUdi33g permit proýiw (6BC 1991, upc 1991) A water sow-ce and moth )d of smage disposal art rcqx&-ad of a. Buffifin Perzah x prior to U*Muad'= Watcr er Public Walcr Supply Public Sewer Currenity avzilable on site Cwrenfly availaW on ske Yes Yes SACWSD SACWSD No No SACWSD SACWSD Extend mains after approval by SACWSD Extend ma= after approval by the Adams County Wala Quabty kwmmon No Colomdo Depar== of'N&"=' No R.esources, Scpdc Sysum. (rC:HD) Offi= of the Stale Engineer Well permit wM be flagned if isnLed Conmnunity Well Syst= or Private WeR until SACWSD i3 &Vl&blC C=T j 27-204 w,,== bmd as domed neceswry by shaRR oxchdijisionshaIlbeap- su= =tcb to ensure a po=)Ie wazer Mov draiaap will be ý_Mucuzly, to an adequate SUPPIY_ provided. wateccuuMse or regional indffitv. (2) The applicant zbzIl agree, as a cOudition Of aVproval for au individual well or central (7) The ciL7 X-Einy, WIMM it CoUsiders it to a =1;41ir ktb sah!ty, or weifare Water SYSOM96 that necess;uT for lim imm WE= TnRFM VV .-MaRy shall be zrovide& of the hl ic; ;V"4"A Couc rVation of ge:n== for ATrivm and smi- The ME-yrt Sh&U waCer fin r WSM MrVice at the tune the Plat %aryfacl-Ittim F J;; the subdivision, Of romm final approval. C4nemal =RY be any pardon. oL-the proper-CY whicil lieB requiz to ensure C=qffiance- within the B jjým of any screm or ca==.:FIx4plain =cas shall bee (Ord- No. 1MS, § 3, 6-21-93) prem ft==_=7 and all destro:tion or Asung resubiztg fr= AV-Prinz fMM3'6c& or oLearth or oth nzazeriaLs- Sec. 17-10& SeWCM98 (Ore- No. 1026, § L-6-21-93) (a) Gourd FRP*=z0z= (3.) The Suph-=ut Shan ingan samicary sewer SM r-IM waterfad'HEM& fa,,,,it!ieS = a -mrm pres:=R)ed by the S=:tb Adms C=MtY Water and San:iza- (a) G=crci rw-zdrm%czr"-- and tinn J)iStriCt CoustruCtinn S='42rds (1) 7he =uiic=t shall eX=Md CL- a2m ' P' - AIL Plans shall be demgned =hie wa= SUFPIY SYSU= ==-'- of pro- M acwrd=m with the rules and regula- "=Mg =aes= Water use and fire Pro tions and st=dar& of the South Ada=s tion, a=ardixLg to approval by the Cunty Water and qMM±aI3 u District a= avprg-,,_-=ze fire districz and the South the Tri-countY EEM'++' Depar=FMt Plans Ad=as Cam=y Water and Smdýrm Dis- shallbegpp, by-theseagen=wsPM=t0 approval ofthe finalpIstby the =y ==C31- [2) Where a pubbr- w8le! 'Ma" is 'Ess:ffilp (2) The wpplicant ShAll elten-4 the sanitarY the Mioc_ rivui 2*er ZiIRII iTTM11 aciecruxt" vra= sewer =&Ut Sysw= for the purpose of fam-Fitipq duJjUdi=g fire hydran= sub*= ... WWerage &M-lib to the sunch- to the Sucificaticyn of the SouZJI AdZZCS visioý =bjed to the provisions of para- caunzy Wet= and Razzirminan a= gzph (b) below. the appýZe f1re dilý= (3) All vr=Cý T"Rin shall be a yn of (b) Co=zcci= to So=* Ad== C==Y W011 . . (81, in ch . and shall be and s=izcý Disvict s=jea to approval of the Scuth Adz= (1) If South Ada= Camcjz7 Water 2nd 512nil- Cao=_ý W mid DL== ana tim DLc=im fnrni+i are a=essfiAe and a fire dis==- týie amxrophate S===Y sewer is claced in a = PPI or esso' Me= ==mgup= the =pen7, the owner (b) Jndiriý ZDeU-s. c=M=1 =,zr "=,2ns- thereof shall be required to connect to the M At the &=e==of South Ad=,s CouutY -ewer for the purpose of AiSPOsin Of wasm W =d _q on Dis=.r- =AivLdu3I I it shall be unbwful for SPY SUCn Own"' webs Do used or a cm=-?j W=M' SYSU= or occupant to innintain an individual am M such 2L =m= th= an a&- sewage disposai quate s=pM of potable waL,-vnU be avail- Adazas Co=ty Water and able to eveiy lot in the saodivLsic= Water (2) Where S=th ;.mta,3= Dntrzct sr=e= are not reason- s== s=a be s===,ed to the TTz-cmmxrY Heait.;,De==ne=andther.ar wa='Can- nly =essible, but wM be=ne avMIZdle 117;; PLANNING AND JJZV =d shall be ready for C=nw areas=ahle, tilm the =0jimt nzay Dis=i= tilt within tion to the public sewer -"rm wD'= me a) of the fonownig 2h==Uives: =ain avagabl& (R-1) arms a- Cezgral, sewerage syscmm- the =xinte- b. 'For low-deDdkY resident='systens or centraJ rimmee cost to be assessed against each . I j* jr,"ga drzsposaj use&sMZb.*!d propaty hmmatted- Vbgwe plans for ww,,zp systms=rybe South AAmnS C=n7 hefl*= provideforthesouthAda=s to mmvval afthe Co=UY Water and nn THstrict Wniýr and Samitatiom Dlstri&- to Tnftan the Mwer lines the laterals Yvbmm individmal Aismml are pro- and of the dzvelop==z shall,be (4) posed, lot areas sWM caniam to in cmg==Vmm with the plans of the the y vy"musts of the ZOEdM OrdiS33COM Aismi and shall. be reac Rtim tests and test hoks =allbe tiozi to the sewer of the anýp" efted by the Txi-CountY Health hs mxhmi=ed to di=icL and the resu= b- In&vi&2A1 dimassi syscm= =.vvided dqn=mnt of com=cnity devel0P==L the =phc=t shall The individual 6512,0801 sYmm, inckading seý -6nmm, laterals and inizin &= tanks and =L- of the Sub& the s=e of the septic the spy P , cmrb -to a Point in the tile fields or oth= m==jary umamme= de- ViSi=bommd=ywhffea.fkz- vim chmn be approved by Tri-CountY tz= with the Sciuth P- D==Ct Bmitki Depzrý ýPrior tO final --qqý shanbe..mde sewer hzm shall be laid of the plat by the CMY cu=-'- fr= the buJiddingto the cry 11 # line and (or&No. 1026, 11, s-21-93) arýftm shall. be zvafi&We in the ===toc:c=ec:tfr=thejný al, sm 17-207. SidewaEks; and UWE& disoosal By to the South Adz= W Remared C==ry Water and -S Disteict (1) Sidewalks and crisabled ra:=rp access shall sy==when it be==es&vzilable, Thee be imýmried witbin the dedicated numPzve- sewer system shall be czp;, * until =.e= rje=.dwxy of an roa& as described ready fiL- use and shall =zdw= to All in riesi= standards of the city. u-1 re- plams for i"stan2zirms of South Adzms Vri"Vea. , by the cfty C=Mril as not being C=MT Water, Minn, Sz==u:i= Discn= rmý ' forthe public health safety,andwel- ,.hm tbey yxist- and shall, be fare of the inhabitants of the citY- for ccxc2ec:d= to the sewer (2) ConcreM cUrbs md yrTp we required for (3) Where Smxth A d s Ca=nzY Water and u where sidewalks am recpximd by S=t=rm Di== fmcd-U14 are not rtzs=- tbis,rdr4 orwhererequiredatthediscre- ably aft-male. and will, not h - avail- ti= of the city cnncil for the public health able w=Lm a reasonable == of tz= the saiety, and weUme ofthe inhýbitantS of the aupu== =zy, at the dimi=v= of SoUZ), city. Ada= C==cy Water and S===icm DL-,- In residential, sub&visizms, a Tnedism == and with the apprum of TnZo=7 .3 _ - --1or landscaped area at least five Dq==wmT- izistall, sewerage sys- 01 grzssm Health wide shall sqmmte all sidewalks fimaws: (5) feet te= as fr= -dia CLUbs, irml vraiv by the a. Forzcedix= and hi0t-densiW rezideý =y =acil as mot being required for the tud (R-2, R-3) 2MA "rM--V!S36erTn21 areMM, pu]mUc healt], safetY, =d wtUam Of the iu- a ce==aj sewerage sy=mn shaU be in- linbitarmr, Of the city. smi-,ed- The =Djj=t shall i-sra" all (b) Pedcm-ic= cccem lines iýý and to be sewer access fr= in cod==ance with ph= of the South (1) In ord= to fa peaescrzan ds Ad= CcmrM-vW2=and -S1rni=rirr% the strefts to schools. park't- P1231ý Sap;L No. 10 1171 .REG7U,L.ý'T TION NO 1-88 rqDWMU.kL SEWAGE: DISPOSAL SYSTE-"vIS PromuJL7ated by thi! Board of Health of the Tri-Counry Health Department Effective Date February 1. 1988 Purs=t to Title 25. Artide 10, paraLrrapn jo4. Colorado Revised Statutes and Guidelines Adopted. by the Colorado Department of He21th de=.ns-..--ar.e =at hazard Cr nuisa-mce exiz=s Cn ProperCIV.- .13 Denials of P=- ts shall be zade in Writi=q bY the Health fcz officer stat4_9 reasons xer the dexLia.1 and re=.,_4_-eManr-s reconsidexaltien of the aPP14=t; n- q=nt. a Pe=i" #_ f=- tte c=n- :.:.4 The Health cj':f-4r-P-r =aY refuse to sevaqe disposal svs=e= Vnere a struct-ion af an the a trea=en- 400 f eet cg sevaq works is available within be made theretc. ne.arrst p==ex_,ýy liýna and can ar anv -. 15 Any app-1-4-cant wac 4s denied a corst_-mc-4cn me=4t, ;ssuan-e cf person who is adversely affected by tIN& denial cr -- a pe=it, (30) daYi fC"'CW`:L'%9 su='denJal, Y c--a Heal't-'. request Lnd rece-,ve a Imeari=g before the Board 4 c'-'g 3.16 The State P--ocedisre Act (Ar---';=Ie the ;"je=m_-=enz 24, C.R.S.) shal'! qvver= any heari=qs held by Sewaae =14s-Wosal Syszams Ac--.- of taz--s and The ;Cm?2_'jr_e --f a and spec_4_-O_-;cat_,;ons conditions t--eze_4-. stall ncz ass==pt_4cn ar =a--=e =av ýme a pres=3:-..-cn =a= tte :)eoa--=e-,%t cr --;ts emmIlove-as a liable f=r tte c! a=v system nor act- as a_-_,Iznent ti= ti:at the used .-;- the syste= or any 11-hareof Used -4:: its czera-_4= or that the sysz= ftr wi.=- t.1-ie per_-.i= -wras 12sued _--.suras ==i=uous liance 'b_'Ifte ---,---as and provision cf 7-41-1,'e :!. ;6=_4=!e 10, C.R.S. !973, C! recrmIat_';c=.s ad_-,.-ad ar any te---s and c=rdit_-;cns a Pre-P-;4.. ZZ'=N =7d. daza, =,ans, The ap=2.4azr_-;cn sý%-!:. sx!c;n :Lr.±c-_- zion, NNW 61ý. AC. --Adams county, Colorado D evelopment Review. Overview A Citzen's Guideto the PrOCeSS Of Revie Ap-Dlication for Land Development and 121--; Use Permitang, for Adams CO1MtY SuTn nary This document is designed to ar a de a brief overview of the process for mnldn land use decisions in Atimm Couxxty and who partickpate-q in the procew. Its purpose is to give ci=:ens the backgmund they need to effectivelY participate in that decision-makin process and influence decisions that affect their The term -12nd developmenC Is intended to be general and includes rezonings. conditional uses. subdivisions a ex=D.tions froni subdividing. variances. special uses and certificates of designation- E=ept for differences between which board or commission mnkes the ultimate decision. the szens that are rnken to Tnnke the particular decision are very simila . Aei=m Countv has land use jurisdiction over all public and private property located in the unincorporated portions of the County, 7he County does not have land use jurisdiction over any proDerrv located in a Citv. The Process, The steps that are taken when an application for land development is made are the following: L A potential applicant calls or visits the Planning and Development Department and discusses thezr land development idea. The staff aýdvises what action would need to be rnken to achieve the end result that is desired. 2. A "ure-armfi cation meetng- is scheduled. For simple and straight- forward an lirnt'rynn. tL-e pre-applicatian meeting =y take place during the initiai contnet by a poteattal applicant - An example of such an applicati n could be a var=ce fi= the side yard setba& to ' cmstruct a garag,r-, More CQ=pIJC2rM a=hcazons. such as the pint" of land for a new rwo-hundred acre subdii==L would require research by the staff to be Imawiedge:ahl about a giv area or praperty so tk= aTne2nmaft!d pre- application meeting could be c=riu=ed. Pre-application mettings bave tw purposes: a) to advise potentini aI)Piic3nr wi= theY need to subr=t in order for their applicat1cm to be piaLCed an the appropriate agf-nmn and b) to advise applicants what the staff reac:tion to an appW== is likeiv to be. what we know about the issues that are likeh- to affec: th= ipplicah n. 3. An appiicari n is subrmami. The staff reviews it for camDieteness and if' it is complete. it is plac---J on the next aNrailable agenda for the aD'Drorriate board or cormnission which meets the notice and referral tLie requiremetnts. 4. CODies of the a=licanon materials-are mailed out to a number of gavernýn rnral ag encle-s- ' ancl any ==r-n*s grour)s that have e=ressed a being =rm asks for cmnmen within a deadlim and Prowdes the- n2TnF-- Of;, ut=louzu per-sm who can answer questu= about th e 2pplimtfrrrr- 5. Le =stt-ý&e m2iled out to property own=s near the sne of the ITJ)J3lJC2:dCM 9Etbý case of Board of Adjustment bezUngs abutting PrM-=Tr ers are-rri2fled letters. In the case of Planning Coznzaission and Board of County t"Marrmussioner hearings. property owners withm at least 500 feet are -nuaded letters. These distances -may be exparlded at the dmcretion of the Coum:r.=i*_F_;",_ 6. The ;kevievs the and wMes a written report with consider2rWiE being F-riven i6' the criteria for review of the particular- application-.;E&Ihe comrnFmrn received from citb= and naeortes. The report Is siditfo the appropriate Board or for their prior to 7. The PIzhIic:-he2rJng is held and a decisirm is made an the application. The Board cEA41ustment rnn a final demsion on variances and speciaL uses. The -PEknrdng Commission rankes a rem wmenri2tion to the Board of Commi-,Monjý.ý- who. in tur= mair a final dem--:;-;.on -.n r=ozzing confiffirm-2173SIs subdivisions and catificates of flesuerny,"!--m. Mmment for- minor HiMý the Board,of Commissioners. the COEMMISS3012 and the Bbaiýd of Adjustment conduct thm bearm in a very-simil in==. First the staff intraduces the case wx a brief summary of what 'Is bemg applied for and provides the staff re ---12tion Next. the applicant rym a presentation of the application, and responds to the staffs lý%C[1132CZ=dationanaanvcmditinn beingrecom aded. After the applicant has made the preseiimnon. the public is invited to be he2rd- The Cbairman will ask for pubhc comment in favm of the a=licabon. In OPPOsLU= to IL-and any questiozi that the public b2s for tnkiýnation only. Often- questions. are isied by those who am spe2k-tng in favor or in opposition o=Just, for infa=ation- At the conclusion Of the public input portion of th= heartn& the :e persons (umally the 2ppha= but also staff =-a.board or member) wM answer the questions v7hich have been asked. At any tIm dnrtn the Ihe2rtna a board or an mPm er mav be remanized bv the chmrmnin in order to ask questions or get cLanfic=on of the iliformation being given. 112e aDPhcatkm is th= discussed bv the board or connnin-Mon members and a. motion for action on the appli;zrion is mnri by one of the members. A majoritv vxme of the board'or commission is reautred for the motion to pass. with one ==Mtion (see Glossary of Terms. Appeals of Adminic! rative Decmions). The Phmning Cam=issicm PL'Mnlng Commi ioners are cirizen aD.pomted by the Board of County Comm' sioners. -Mhev have three basic duties: 3. 1. To adopt and mnend. as appropriate. the County C p rehensive Plan "bis Plan Is. the officiai pahcy of the County for how the County should grow and develop (or rediveioip) m, the faturr- --The Plan provides guidance for -ed-zlem to be xnade on development a=ficatiffas and public CM=Ital prcjects. 7he Plan is not 9 it is a sta === of cy. The Planning Commissionfiincti-_ s as a legmLadive, body when they perform this duLy. 2. To review . . " ' - ns'for land use changes and land subdivisiori and recommend 2r-,"on an those applications to the Board of Commissioners. In rnnIctn thpi decision. the Planning Commission considers the cons-, tency between the application and the Comprehensive Plan the compatibility between the requested development and r-risting deveiapment in the area- and the ability of the proposed d opment to meet the requirements of the Zoning Regulations or SuSdivision Regilthati ns. as appropriate- The Planning Commission fimcbm as a cruasi-jud:icial. body when they peribrm this duty. 3. To recommend adoption of the County Zoning Regulations and Subdivision Regulations. The Planning Commission may recommend amendment to the Zordng Pieg"b4tions and S egulations but the Board of I'mrmnissioners has the final decision-m2king authority on regulatory arnentimen . The Planning Commission functions-as a legm,12trye body when theT perform this duty. The Bo=-d of Ckn=ty Ca=missi=ers 7he Counry Commissioners are the elected representauves of the cittzen lbý perform many duties other thnn those rel;attng to Land deveiapment applications and only their duties concerning land development a=licazons are til-,q- S-ew-A here 7he County Camraissioners r=k the hiial dryngirm an all change of use I.WPHentirms- subdivisionl_q and -- Y nmiownrimenrn- They hold public he2nngs in a stimila n=Tmf-r to those of the Planning Cam=Jss:iozL Tbe Ctu= Commissioners consider all the irrput that the Planning Camymsman does 2Lua the Planning Commission LUZ 111111=d2tifm in rnnktn -0 the:r dectmon an an arqgicatiotL M2e Board of County Commissioners f=c=ns as a qUaSi-judiclk body when they hea Change in use or subdtvtsl= applic3rians and as a legininttye, body vhM they hear proposed reguia=7 2rMrnejrnr=_n The Board of Ading=e= Board of Adjustment me=bers. Wce the Plarmin Commisrjoners. are c=zcns appointed by the Board of Countv Ca=nismoners. -Me Board of Adtustment hears applim-mons far va:riances. special uses and appeals of aditýstratrve d i ions. UaWce the Planning Cnmrnj sion. however. the decmons of the Board of Adjusanent are final and not appealable to the Board of Couarv Co, onexs. The Board of Ad*justment functions as a Mia-ISi-judicial body. 4. PlamminV9 8=14M_ a e=t Demtment Stsff The s ers of the Planning and D ousnerrt D wit (staff) are employees=uf the County. Me DU-ec= of tbLe reports to the Cou:ntyLeA89dnistrator -i'vho. in turn. repor:ts to the Board of County isst I~ ý Staff administers the processes fOr'12nd development- apphC2t'on-0tjjjov1des public infarmkiarL andmnbmsman "Intenri2tions to the _I-ropTia-reboard or commission on ti2e ;2THCz-viar. 2=iie2tions. 00-sSarr OfIrerms Appeal of air-A&M Decisicm-The Zwung Regulations delegat authority twmebunty staff to zmairp aciministrative decisions. These St2ff M&M nzay.=ý* be the Direý of PL=njng and Development. the Chief Building OMW: or other County staff. An appeal =ay be made to the Board of el -- ent bv an applic= an interpretation of the Zoning R - ams. deni-al of a building permit aue to a zonin standard. or some odm= ecision r..-hich is not agreed withL bv the appilcant_ The Board Of AMbStlnent rmews the decision ruari 21Ld =ay uphold ltýor- reverse it 1xrPv*fble or in Dart- For a decision to be Levex ed. four of the- ftve Board WAdjustm - vote :for the- reversal -of the decLsion- ent members must Certfficat -.oMesignaticn-A tvpe of use approval tb2t is limited to waste T= T12 PreMPT7t_operations such as 12neifill or waste irk er3,tors. Certtficate of is a State of Colorado review proce that requires a rec d2tiOn Of approval by the Colorado Deoartment: of Health before the County--m2y grant a cernficam The &2:te'review involves tecbnical considerations . concerning whether a proposed operation PVM be I C Sr'stent wffh: the State's wane rrmnn en== regtflntims. The County Irnew involves- land use considerations such as compatibility with a erris"no us=-'effect an theCmixprehensive Plan objecthres for aa area and traffic impacts. Compatibillty-A condition tb= exists. or is believed to be possible- betweeri two ar"IMOre uses whaebY the conduct of one use does not togure the abilitV to conduct another use It does not rnf,_,4n that the uses are the -s=e or evan,--stmila . It does Tmenn that if uses are compatible property owne:s may use their prcpeemes withmn being !asonably affected by the other use(s). Conditlonal Us-e-An additional use of land within a given 7,-nn district. not otherwise allowed as a use-bv-ngtit. ttm mav be I by the County and May be zestr cted bv con'diti-ons tc) estalilish dlity between the use aný adjact=t uses.' Coadr=nal uses may oniv 'be authorized by the BoRrd nf (ýnMmiq,.rnnnerc nftsw .- Vorw by the siaff anti tbo rn*nnincr Commis ion nir'ýa due process review. Due Proemm-A method of makin dedslon that is based on following previously adopted rules of procedure- In the context of land develo fmt review. It rn"mn a process for making those dedslans that enstwes thatall parties have an opportunity to provide info=,avem =2n equal ham winch is intended to influence thýe outcome of the decisl=-making process. Ex Parte legal pr=mVle thylt, =eans contact by a decision- In -quasi-Judicial decisinn-m-gkin pro with a party or parties to an ap "cattnn outside the public h=rmer- A party to an cati-ri is the appliamt,_. affected citizems. or any other person who will po -tal be benefitted or-inJured b-,,-, the action taken on the application- Ex Fýarte contacts shcn-Ari be avoided so that all Darties to an application may have an equal opportuLuity to provide information in the public hearing and imhuence the ultimate dedsioný Ve Process-A decision-mak-ing process that seeks information from all r-f"7-,en on a matter of coramunity-wide interest. Citizens are encouraged to Contact their elected or appointed representatives and provide their viewpoint on such matters on a formal or informal hasi guasi-judidal Promms.-A decision-making process that bases a decision on PrmOusIY-eSt2bliShed criteria for ronkin the decision. Citizen i=ut is encouraged that po des rn =arion concerning how an application-does. or does ncrtý meet those., cnteria. The input *is restricted to a public hearmg where the irtout is made and decisions are reached. SPecial Use-Any use of land. not prohibited within the zone district. autharized by the Board of Adjustment aft a due process review. for a Denod not to exceed frve vears. Subdivision. Regulations-The document approved by the Board of Comm, ssioners that prtnades for the standards by which land is divided into smaller parcels or co=med into larger parcels and haw the descri:otion of these pa=eýs ts made a Tnzttt of public record. It also provides c andards for me confignuatLon of parcels. access puovLýsicmss and roadway and dra=3age standards. Subdivision-A legally recovn=.ed parcel of land. or collection of parcels of land that is dpfine,ýfi br a n ranve and grapbic descripticm- The document that denicts a subdraýion Ls a piaL T, mr, orarr Use-Anv use of land. not pmbibited within the zon districL author=ed by the DirecLor oiI M--anning and Development but for a period not to exceed niriety days. H grading and fiauling operations may be author=ed urider a Temporarr Use permit for a period -of up to one- irundred-eiszhty days on proper--ts W ten acres or less. V"rignee-A vm=ce is authar:zed by the Board of Adjustment. Variances reiate to the physical re-cra:rt--ents of the Zonmg Regulations onlyý not to use of property. In theory. all prorteirv in the s=rne zone district is the 6. same-m practice. lots are not alike but the standards of a given 2rm to all lots in the zon distoct- The vmance process allows the Board of Adjustment to -adjust- the z=jn Standards to odate for differences between the physical la:r= of lots so th2t all PrOP=tY May by able to enjoy their propertl In2nequitablemanner- Zoning-The practice of P-q hmqd7f"g distdcts within a J that allow specific uses to be conducted - under standards. in order-to establish separation between uses which otherwise would conflict- Zon4?VV Map-The official map of the Co=ty that shows the b of all zone distrtcts. The map is adopted by the Board of CO bv EM and each change to the map is also adopted by 11y"nn - BodL the nmp (whdch is really a collection of appr " "ixnately 80 sheets to cover- the entire Co=tv) and the resolution are recorded in the office of the Counrv Clerk and Recorder. Zoning Regulations-The document approved by the Board of Cnmmismonens that defines all z= districts and the standards expected of all uses within zone districts. These regulations alssz- ;3.Luv de for the process by which zoning., is changed. t procedures, and general stimclards that apply to any land use in All zone districts. 7- BY-LANS OF ADAMS COU= WATER QUAL= ASSOCMTMON A = I O=C:ES Section 1. The Office of the Ada-m Co=ty Water Quality Association ("Associ atJ on") shat I I be at- the office of Scnz*.-.h Adirms- County Water and Sanitztton 6595 East 70th Avenue, Colorado- Co=e--r--- city, 90037-0597 or such other place the board of directors may time=tc-time dete--=j-ne. A== 2 DIRECTORS Section 1. 'he board of d--;-ec--crs for the Association nhall consist one x-eip--mesentat-,ve of e-lected by each participating entity, consisting of the Cityýof Cc=ez--e City, Colorado: City of Brighton, Colorado; Colorado; and South Adams County Water and Sanitat.ion Dist--ict. Section 2. In the- absence of the appointed director, the alte--na,te appointed director =ay act. in place of the absent dizvctor. A== 3 OMMMS Section 1. '"he officex-s of --!Le Assoc:.ation sha 11 be a president, a vice- president and a secretary. ARTIZ= 4 ==ON OF OFFICEEM, Section 1. Officers shall be elected by a majority vote of the directors at the organiZationa-I meeting held in 1991. Section 2. Beginning in 1992, 'and every year tbP--ea.,-F-te=, off4cers election of. 4gh.:411 be held at the first annual meeting of the Ass;clatiom,- Section 3. There shall be no prohibition against an office succeeding him or herself in any of the of-ofices Of the Association. ARTI= 5 1ý=S Section 1. Unlabs othexVise noted, regular cluarter1y meetings of -,he Association shall be held on the second Thursday of January, April, July and October as set forth in the Memorand,.:m of Understanding ber-ween mwm e=s of t!xe Association. Section 2. Im the event there shall be no business to conduct at such quarterly meeting, the =resident may cance-I such meeting in Vriting to all directors set:--:-*ng forth t!:Le reason for such cance-Ilation. A== 6 SPE=-IT .1Fn Sec-tion 1. A request for a sDe=ial meeting of the board of directors may be requested by a di-:ec=o= i--I writing to the president of the Associ ation with c--=ies to all member di=eczors. Such request shP22. set forth the Pu=POse of such request- for a special meeiing. 2 Section 2 After-- receii:t Of a request for a special meeting, the presiderzt7--shm 11 set a special meeting of the board of directors with J n twenty days a,.16.1-er receint of such request and --ha I I give the ,mmm ers; c:E7-tha board of dlrectý'zrs notice in vrit-inq of the date and time of sucb-special meeting and the F= ose of'such meeting. such notice =hall also include copies of any remor"Its, exhi its, or other material that may have been smtmittted -io the president by the requesting-4irect==- A== 7 C Section-1. Mie president shmIl aw..-sci3it such cozimittees as he or she deems necessary to- caz--y out the purposes and the activities of the M=Oranrirm- Of UnAp tanding between the mem er entities of the Asso=iat-ion. ARTI= 8 RECC22CENDATMONS Sec=ion 1. JLU recfam-endatior-s c= decisions of the board of directors on all Clean Watear Plar. Azexutments, 201 Facility Plans, proposals or c--I,er zitt-ittal sha.:l be by =a)oritty vote., each director ss-hall have. one vv--&. Im the amsence of a ;Llector, his or her duly appointed a-'--e--Aata shall be e--t=--:tled to vcrtp-. Section 2. Tts rwzu.'It Of such votes shall be submi=-ed by the pre ident an all Clean water p'ýAn Az&m----m4nLs, 201 Facility Plans or such Ot!:Lex ;-'A=o, 5- d-es or remcr--z su=itted by the Association or one of -4=s er.t-4tie-S -.ýtz Denver Regional Council of Government or to =4 Cclora=o Watez Cua-Ilt-jr Cont---ol Division or to any other requ" at agrancy. 3 Section 1. The Associat-ion may appoint a Recording Se=vtary to take all of the minutes of the board of and to condnct such crther activities deemed necessary by the Association. Section 2. '- The Association may employ such other employees it deems necessary to carry out the purposes and the activities of the Association. Section 3. Compensation fcz, =cb eamloyees shall be t and allocated between the inay, ers of the Association in such a manner as may be detexmined by the Associat-ion. A== 10 CONZ-=L-r Section 1. In the event a conflict develops between the mravisions of the v..LemoranCLI= of tIndex-StandIng entered into between the member enzitiets and these By-laws, the provisions of *the Morm rand= of Understandin will =nt--ol. IMF= BY-L&WS ADOPT= THT DAY OF 1991. 4 Clarification of Requirements for the Rocky Mountain Arsenal Offpost Operable Unit Final Record of Decision Rocky Mountain Arsenal Superfund Site Commerce City, Colorado June 1996 Rocky Mountain Arsenal Superfund Site Clarification of Requirements for the Rocky Mountain Arsenal Off Post Operable Unit Final Record of Decision June 1996 The purpose of this document is to clarify certain requirements contained on page Al-1, Appendix B of the Rocky Mountain Arsenal Off Post Operable Unit Final Record of Decision (Off Post ROD), which was signed on December 19, 1995. Page Al-1, Appendix B of the Off Post ROD requires Shell Oil Company (Shell) to execute and record restrictive covenants to eliminate potential exposure to contaminated groundwater underlying certain land owned by Shell in Adams County, Colorado. On June 11, 1996, Shell executed and recorded the Declaration of Covenants attached hereto as Exhibit B of Appendix B, Attachment 3. On June 11, 1996, the United States Department of the Army, Shell Oil Company, the State of Colorado, the United States Environmental Protection Agency, and the United States Fish and Wildlife Service entered into an Agreement, attached hereto as Appendix B, Attachment 3. The Agreement provides clarification regarding the operation of the covenants placed on the Land, including provisions for release of the covenants when certain conditions contained in the Agreement are met. The Agreement was presented at meetings of the Site Specific Advisory Board of the Rocky Mountain Arsenal on May 28, 1996, and the Restoration Advisory Board of the Rocky Mountain Arsenal on June 6, 1996. The Agreement is hereby attached to the Off Post ROD as Appendix B, Attachment 3. Affirmation of Statutory Determinations This Clarification of Requirements does not represent significant change to the selected remedy. The selected remedy remains protective of human health and the environment, complies with Federal and State requirements that are applicable or relevant and appropriate to this remedial action, and is cost-effective. APPENDIX B ATTACHMENT 3 THE AGREEMENT CONTAINED WITHIN THIS ATTACHMENT, dated as of February 2, 1996, is among the UNITED STATES DEPARTMENT OF THE ARMY (the "Army"), SHELL OIL COMPANY ("Shell"), the STATE OF COLORADO (the "State"), the UNITED STATES ENVIRONMENTAL PROTECTION AGENCY ("EPA"), and the UNITED STATES FISH AND WILDLIFE SERVICE (11USFWS11). Recitals A. Shell owns the land in Adams County, Colorado described in Exhibit A attached hereto and forming a part hereof (the IlLand"). B. A portion of the Land is subject to Revised License dated effective December 3, 1991 (the "License"), from Shell to the Army, notice of which was given by Memorandum of License dated effective as of December 3, 1991, between Shell and the Army, filed for recording June 25, 1992 at 8 a.m., and recorded under Reception No. 1074181 in Book 3920 at page 351 of the real property records of Adams County, Colorado. C. The Army, Shell, the State, EPA, and USFWS entered into Agreement for a Conceptual Remedy,for the Cleanup of the Rocky Mountain Arsenal dated June 13, 1995 (the "Conceptual Remedy .Agreement"). D. Paragraph 23 of the Conceptual Remedy Agreement requires Shell to execute and record covenants to eliminate potential exposure to contaminated groundwater underlying the Land. E. The Land is included within the Offpost Operable Unit (the "Offpost OU11) of Rocky Mountain Arsenal, a National Priorities List site under the Comprehensive Environmental Response, Compensation, and Liability Act. F. A Record of Decision for the Offpost OU (the "Offpost ROD") was signed on December 19, 1995. G. Page Al-1 of Appendix B to the Offpost ROD also requires Shell to execute and record covenants to eliminate potential exposure to contaminated groundwater underlying the Land. H. By Declaration of Covenants dated as of February 2, 1996 (the "Declaration"), filed for recording June 11, 1996, and recorded under Reception No. C0183385 in Book No. 4769 at Page No. 297-308 of the real property records of Adams County, Colorado, Shell declared covenants for the benefit of the United States of America (the "United States") and the State to satisfy its obligations under paragraph 23 of the Conceptual Remedy Agreement and under page Al-1 of Appendix B to the Offpost ROD. A copy of the Declaration is attached hereto as Exhibit B. I. The restrictive covenants set forth in the Declaration are enforceable by the United States, through the Army and EPA, and by the State. Agreement In consideration of the foregoing and other good and valuable consideration, the receipt and sufficiency of which all the parties acknowledge, they hereby agree as follows: 1. Consent. The Army consents to the restrictive covenants set forth in the Declaration and this Agreement. 2. Satisfaction of Obligations. The Army, the State, EPA, and USFWS acknowledge that recordation of the Declaration and the signing of this Agreement fully satisfy Shell's obligations under paragraph 23 of the Conceptual Remedy Agreement and under page Al-1 of Appendix B to the Offpost ROD. 3. Prohibition Against Alluvial Wells. No groundwater well for future use may be constructed on the Land if it is screened in the unconfined flow system (the 11UFS11), which is defined as the alluvial aquifer and the weathered upper portion of the Denver Formation, until no analyte listed in Schedule 1 is present in excess of the appropriate standard listed in Schedule 1 in any well listed in Schedule 2 attached hereto (or replacements for those wells) during a 5-year period that includes the following sampling events: 5 consecutive annual samples analyzed for all analytes listed in Schedule 1; 3 quarterly samples analyzed only for DIMP and dieldrin between the third and fourth annual samples; and 3 quarterly samples analyzed only for DIMP and dieldrin between the fourth and fifth annual samples. This prohibition does not apply to wells for groundwater sampling, wells for groundwater level measurements, wells for extraction for treatment of contaminated groundwater, and wells for reinjection of treated groundwater. 4. Prohibition Against Use of Deeper Groundwater. No groundwater may be used from any well on the Land that is screened in any aquifer beneath the UFS so long as that well contains any of the analytes listed in Schedule 1 in excess of the appropriate standards listed in Schedule 1. In addition, any well screened in any aquifer beneath the UFS may be closed pursuant to the Offpost ROD if the criteria for well closure set forth in Appendix C to the Offpost ROD are satisfied. 5. Covenants Run With Land; Enforcement. Paragraphs 3 and 4 above govern the implementation of the covenants in paragraphs 1 and 2, respectively, of the Declaration, which touch and concern, run with, and burden the Land, and benefit the Onpost OU. The covenants of paragraphs 1 and 2 of the Declaration are granted for the benefit of the United States and the State to protect, preserve and enhance the property values of the Onpost 2 OU, as well as contribute to the overall remedy of RMA, and are enforceable by the United States, through the Army and EPA, and by the State. If there is a violation of either of those covenants that remains uncured after 30 day's prior written notice of the violation to Shell (or other owner of the Land or portion thereof whose action constitutes the violation), the United States and the State, or either of them, may institute a suit against the person violating the covenants to enjoin the violation by temporary or permanent injunction; provided, however, that for an irreparable ongoing or imminent violation the 30-day notice is not required. No failure by the United States or the State to institute such a suit shall be deemed to be a waiver or a forfeiture of the right to enforce any covenant in this instrument. 6. Release. When the conditions to allow construction of groundwater wells for future use on the Land that are screened in the UFS, as described in paragraph 3 of this Agreement, have been satisfied, Shell shall so notify the Army, the State, and EPA. If the Army, the State, and EPA agree, (a) the Army, the State, and EPA shall acknowledge that the conditions have been satisfied and (b) the United States, through the Army, and the State, in consultation with EPA, shall execute, acknowledge, and deliver to Shell a Release of Restrictive Covenants in the form of Exhibit C attached hereto to evidence of record that the covenant in paragraph 1 of the Declaration, as implemented by paragraph 3 above, no longer burdens the Land. 7. Notices. All notices given under this Agreement shall be in writing, shall be given by certified mail, return receipt requested, overnight courier service, telecopy, or hand delivery, and, (a) if mailed, shall be deemed received three business days after mailing with postage prepaid, (b) if delivered by overnight courier service shall be deemed received one business day after having been deposited with the courier service, with delivery fees paid by the sender, and (c) if delivered by facsimile or hand delivery, shall be deemed received on the day the notice is sent if the sender makes reasonable efforts to confirm the receipt thereof; in each case addressed as follows: If to the Army: Program Manager Office of the Program Manager Building ill Rocky Mountain Arsenal ATTN: AMXRM-PM Commerce City, Colorado 80022-1748 3 If to EPA: EPA Coordinator for RMA (8EPR-F) U. S. Environmental Protection Agency Region VIII 999 18th Street, Suite 500 Denver, Colorado 80202-2466 If to USFWS: Regional Director U.S. Fish and Wildlife Service Region 6 P.O. Box 25486 Denver, Colorado 80225 If to the State: Rocky Mountain Arsenal Project Manager Hazardous Materials & Waste Management Division Colorado Department of Public Health and Environment 4300 Cherry Creek Drive South Denver, Colorado 80222-1530 with a copy to: Colorado Department of Law CERCLA Litigation Unit 1525 Sherman Street Denver, Colorado 80203 If to Shell: Manager of Denver Site Project Shell Denver Site Project c/o Holme Roberts & Owen LLC 1700 Lincoln, Suite 4100 Denver, Colorado 80203 Any party may, by written notice so delivered to the others, change the address or facsimile number to which delivery shall thereafter be made. 8. Further Assurances. The parties shall execute and deliver or cause to be executed and delivered such other instruments, and take such other actions, as may be reasonably necessary or advisable to carry out the purposes of this Agreement. 9. Integration. This Agreement and the Declaration constitute the entire understanding among the parties with respect to the subject matter hereof, superseding all 4 negotiations, prior discussions, and prior agreements or understandings with respect to the subject matter. 10. Parties in Interest. This Agreement shall be binding upon and inure to the benefit of the parties hereto and their respective successors and assigns. Nothing in this Agreement, express or implied, is intended to confer upon any other person or entity any benefit, right, or remedy. 11. Counterpart Execution. This Agreement may be executed in any number of counterparts, each of which shall be deemed an original instrument for all purposes. EXECUTED as of the date first above written. UNITED STATES DEPARTMENT OF THE ARMY eýL y , KayfiiondT J. Fatz Acting Deputy Assistant Secretary of the Army (Environment, Safety and Occupational Health) SHELL OIL COMPANY B R.N. Shulman Vice President HS&E Shell Chemical Company FOR THE STATE OF COLORADO By- Tom Looby Director, OffTýbf Environment Colorado Department of Public Health and Environment STATES ENVIRONMENTAL PROTECTION AGENCY B McGr5C" AJ ingW Regional Director ETilronmental Protection Agency UNITED STATES FISH AND WILDLIFE SERVICE rry Terýrell D put Regional Director, Mountain-Prairie Region U.S. Fish and Wildlife Service 5 EXHIBIT A The following described land in Adams County, Colorado: Adams County Joint Venture Tract The land conveyed by Warranty Deed dated February 26, 1991, from the Adams County Joint Venture to Shell Oil Company and more particularly described as follows: Southwest Quarter of Section 13, Township 2 South, Range 67 West, excluding therefrom those tracts of land described in the following deeds: 1) Book 771 at Page 234 2) Book 1003 at Page 527 3) Book 1037 at Page 479 but including the east 60 feet of the tract of land described in said Book 771 at Page 234, all being in records of said Adams County. Commerce City Tragt The land conveyed by Warranty Deed dated October 15, 1991, from the City of Commerce City, Colorado, to Shell Oil Company, recorded in Book 3839, Page 873, and more particularly described as follows: A parcel of land situated in a portion of Lots 3. 4 and 6, Block 1, ADCO Industrial Park Subdivision, being a portion of the Southwest one-quarter of Section 14, Township 2 South, Range 67 West of the Sixth Principal Meridian, County of Adams, State of Colorado, more particularly described as follows: Commencing at the center one-quarter corner of said Section 14, said point also being the Northeast corner of said Lot 6, said point being the TRUE POINT OF BEGINNING; thence South 00*071250 West along the East line of said Lots 6 and 3 and along the East line of the Southwest one-quarter of the Southwest one-quarter of said Section 14 a distance of 1058.92 feet; thence North 62*321171 West a distance of 824.60 feet to a point on the Northwesterly line of said Lot 6, said point also being on the Southeasterly right of way line of Colorado State Highway No. 2 and U.S. Highway No. 6; thence the following three courses along the Northwesterly line of said Lot 6 and the Southeasterly right of way line of said Colorado State Highway No. 2 and U.S. Highway No. 6; thence North 45'001480 East a distance of 396.72 feet; thence North 46'111030 East a distance of 299.95 feet; thence North 43*071400 East a distance of 261.54 feet to the Northwest corner of said Lot 6; thence South 89*521350 East along the North line of said Lot 6 a distance of 58.15 feet to the TRUE POINT OF BEGINNING, County of Adams, State of Colorado. A-1 Fischer Tract The land conveyed by Warranty Deed dated January 30, 1991, from Peggy Nadine Fischer, n/k/a Peggy Nadine Hits, to Shell Oil Company recorded in Book 3748, Page 724, and more particularly described as follows: Block 1, Fischer-Hoffman Tract Adams County, Colorado also known by street and number as 9955 and 9961 Peoria Hickey Tract The land conveyed by Warranty Deed dated January 17, 1991, from Michael E. Hickey and Charles E. Hickey to Shell Oil company recorded in Book 3746, Page 328 and more particularly described as follows: PARCEL A: The SE 1/4 of Section 14, Township 2 South, Range 67 West of the 6th P.M. EXCEPT the South 30 feet thereof; EXCEPT that portion thereof lying within Peoria Street, 96th Avenue and East 100th Avenue; EXCEPT that portion thereof lying within the Subdivision of Fischer-Hoffman Tract; EXCEPT that portion thereof described in deeds recorded December 19, 1960 in Book 883 at Page 558, August 21, 1969 in Book 1539 at Page 239 and August 28, 1973, in Book 1884 at Page 850 and EXCEPT any portion thereof that may lie Westerly of the West line of that tract of land described in deed recorded December 9, 1960 in Book 882 at Page 335. County of Adams, State of Colorado. Note: Land referred to in deed recorded in Book 883 at Page 558 described as follows: A parcel of land located in the SE 1/4 Section 14, Township 2 South, Range 67 West, 6th P.M., described as follows: BEGINNING at a point which is 2640 feet South and 30 feet West of the Northeast corner NE 1/4 Section 14, Township 2 South, Range 67 West; thence West 960 feet, thence South 1320 feet, thence West 1220 feet, thence South 1290 feet, thence East 2180 feet, thence North 2610 feet to the POINT OF BEGINNING; NOTE: Land referred to in deed recorded in Book 1539 at Page 239 described as follows: That part of the Southeast quarter of Section 14, Township 2 South, Range 67 West of the 6th Principal Meridian, Adams County, Colorado, described as follows: A-2 BEGINNING at the Southeast corner said Section 14; thence North 90 deg. 00 min. 00 sec. West on an assumed bearing along the South line said Southeast one-quarter a distance of 1013.00 feet to the TRUE POINT OF BEGINNING; thence continuing North 90 deg. 00 min. 00 sec. West along said South line Southeast one-quarter a distance of 1188.57 feet to a point 430.00 feet Easterly of the Southwest corner said Southeast one-quarter; thence North 00 deg. 06 min. 30 sec. East along a line parallel to the West line said Southeast one-quarter a distance of 1320.00 feet; thence North 90 deg. 00 sec. 00 min. East, 1189.14 feet to a point which is 1013.00 feet West of the East line said Southeast one-quarter; thence South 00 deg. 08 min. 00 sec. West along a line parallel to the East line said Southeast one-quarter a distance of 1320.00 feet to the TRUE POINT OF BEGINNING, EXCEPT the South 30.00 feet thereof. NOTE: Land referred to in Book 1884 at Page 850 described as follow: BEGINNING at a point 30 feet North and 669 feet West of the Southeast corner of the Southeast quarter of Section 14, Township 2 South, Range 67 West of the Sixth P.M., County of Adams, State of Colorado; thence North, a distance of 1290 feet, thence West, a distance of 344 feet to an existing pin; thence South a distance of 1290 feet more or less, to a point 30 feet North of the South line of the Southeast quarter of Section 14; thence East and parallel with the said South line, a distance of 344 feet to the POINT OF BEGINNING. PARCEL 8: That part of the NE 1/4 of Section 14, Township 2 South, Range 67 West of the 6th P.M., lying Southeasterly of U.S. Highway No. 6 and Southerly of the South lines of those tracts of land described in deeds recorded November 5, 1967 in Book 1361 at Page 76 and June 3, 1982 in Book 2649 at Page 750, EXCEPT that portion thereof lying within Peoria Street and EXCEPT that portion thereof described in deed recorded December 19, 1960 in Book 883 at Page 556, County of Adams, State of Colorado. A-3 NOTE: Land referred to in Book 1361 at Page 76, described as follows: That part of the HE 1/4 of Section 14, Township 2 South, Range 67 West of the 6th P.M., described as follows: BEGINNING at the East Quarter Corner of said Section; thence Northerly, along the East line of said Section, 450 feet; thence Westerly, on an angle to the left of 89 deg. 40 min. 08 sec., parallel with the South line of said HE 1/4, a distance of 990 feet to the TRUE POINT OF BEGINNING; thence Westerly, parallel with said South line, 1298.14 feet to the Easterly right of way line of Colorado State Highway No. 2; thence on an angle to the right of 131 deg. 46 min. 08 sec. and along said Easterly right of way line 1313.94 feet to a point 1430 feet North of the South line of said HE 1/4; thence Easterly on an angle to the right of 48 deg. 13 min. 52 sec., parallel with the South line of said HE 1/4, a distance of 417.23 feet to a point 990 feet West of the East line of said HE 1/4; thence Southerly, on an angle to the right of 89 deg. 40 min. 08 sec. and parallel with said East line, 980 feet to the TRUE POINT OF BEGINNING. NOTE: Land referred to in Book 883 at Page 556 described as follows: A parcel of land located in the HE 1/4 Section 14, Township 2 South, Range 67 West, 6th P.M. described as follows: BEGINNING at a point which is 2190 feet South and 30 feet West of the Northeast corner HE 1/4 Section 14, Township 2 South, Range 67 West, thence West 630 feet; thence South 450 feet; thence East 630 feet; thence North 450 feet; to the POINT OF BEGINNING. NOTE: Land referred to in Book 2649 at Page 753 described as follows: A parcel of land in the Northeast 1/4 of Section 14, Township 2 South, Range 67 West of the 6th Principal Meridian, Adams County, Colorado, described as: BEGINNING at the East 1/4 corner of said Section 14; thence North 00 deg. 00 min. 00 sec. East, on an assumed oearing along the East line of said Northeast 1/4, a distance of 520.00 feet; thence North 89 deg. 40 min. 08 sec. West, parallel with the South line said Northeast 1/4 a distance of 30.00 feet to the TRUE POINT OF BEGINNING; thence continuing North 89 deg. 40 min. 08 sec. West, a distance of 960.00 feet; thence North 00 deg. oo min. 00 sec. East parallel with the East line of said A-4 Northeast 1/4 a distance of 910.00 feet; thence North 89 deg. 40 min. 08 sec. West a distance of 417.23 feet to a point on the Easterly right of way line of Colorado State Highway No. 2; thence North 42 deg. 04 min 00 sec. East along said Easterly right of way line a distance of 250.85 feet; thence North 42 deg. 24 min. 20 sec. East continuing along said Easterly right of way line a distance of 204.10 feet to a point an the South line of the Public Service Company right of way; thence South 89 deg. 32 min. 10 sec. East along said South right of way line a distance of 1071.55 feet to a point on the West right of way line of Peoria Street; thence South 00 deg. 00 min. 00 sec. West along said West right of way line and parallel with the East line said Northeast 1/4 a distance of 1246.21 feet to the TRUE POINT OF BEGINNING. Hoffman T act The land conveyed by Warranty Deed dated January 30, 1991, from Clifford R. Hoffman and Joan Hoffman to Shell Oil Company recorded in Book 3748, Page 201, and more particularly described as follows: Block 2, Fischer-Hoffman Tract Adams County, Colorado as known by street and number as 9925 Peoria. A. Maul Tract The land conveyed by Warranty Deed dated January 24, 1991, from Albert L. Maul and Evelyn F. Maul to Shell Oil Company recorded in Book 3747, Page 424, and more particularly described as follows: That part of the Northeast 1/4 of Section 14, Township 2 South, Range 67 West of the 6th P.M., described as follows: BEGINNING at a point which is located 2190 feet South and 30 feet West of the Northeast corner of said NE 1/4; thence West a distance of 630 feet; thence South a distance of 450 feet; thence East a distance of 630 feet; thence North a distance of 450 feet to the POINT OF BEGINNING Adams County, Colorado as known by street and number as 10021 Peoria Ohle Tract The land conveyed by Warranty Deed dated February 21, 1991, from Albert H. Ohle and Barbara J. Ohle to Shell Oil Company recorded in Book 3755, Page 441, and more particularly described as follows: A tract of land located in the SE 1/4 of Section 14, Township 2 South, Range 67 West of the 6th P.M., described as follows: A-5 Beginning at a point 30 feet North and 669 feet West of the Southeast corner of the SE 1/4 of said Section 14, thence North, a distance of 1290 feet; thence West, a distance of 344 feet to an existing pin; thence South, a distance of 1290 feet; more or less, to a point 30 feet North of the South line of the SE 1/4 of said section 14; thence East and parallel with the said South line, a distance of 344 feet to the Point of Beginning, County of Adams, State of Colorado, as known by street and number as 11841 E. 96th Avenue. Werth Tract The land conveyed by Warranty Deed dated January 30, 1991, from Ronald J. Werth and Virginia A. Werth to Shell oil Company recorded in Book 3749, Page 985, and more particularly described as follows: All of Block 2, Wagner Tract Adams County, Colorado as known by street and number as 9755 Peoria Street. HolstinieL-Txranat The land conveyed by Warranty Deed dated February 22, 1990, from Byron W. Holstine to Shell Oil Company, recorded in Book 3650, Page 425, and more particularly described as follows: THAT PART OF THE SOUTHEAST 1/4 OF SECTION 14# TOWNSHIP 2 SOUTH* x4m= 67 WEST OF THE 6rK PRINCIPAL MERIDIANt ADAMS CaUNTY# COLORADO DESCRINED AS: BEGINNING AT THe SOUTHEAST CORNER OF SAID SECTION 14, THENCE NORýH vo oceptces DO mINvTZS oo SECONDS biCST ON AN ASGUMCD REARING ALONQý THE SOUTH LINE SAID SOUTHEAST 2/4 A 0 taT^NCZ OF 1300. 67 FEET TO THE TRUE POINT OF 86GINNrNQi THENCE CONTINUING NORTH TO DEGREES 00 MZNVTCS 00 SECONDS WC3T ALONG SAID SOUTH LINE SOUTHEAST 114 A DISTANCE OF 313. 23 PCET TO A P13 I NT 767. 47 r I-C I EASTERLY OF THE SOUTHWEST CORNN3t SAID SOUTHEAST 1/4j THENCE NORTH 00 DEGREES 04 MINUTES 30 89CON08 rANT ALO" A LINE PARALLEL To THE bffST LINE SAID ZOUTW-AST 1/4 A DISTANCE OF 1320. 00 FIEZTJ THENCE NORTH- 90 DECREES 00 MINUTES 00 SECONDS EAST# 313.90 FEET TO A POINT WHICH go 1330.67 FEET WEST OF THE EAST LINE SAID SOUTHEAST 1/41 THENCE SOUTH 00 DIFORCES 08 MINUTZ5 00 SECONDS, WEST ^LONQ A LINE PARALLEL IV THE EAST LINE SAID SOUTHEAST t/4& A DISTANCE .OF 1320.00 FEET TO THE TRUE POINT OF SZOINNING EXCEPT SOUTH 39.00 FEET THEREOF. Lambert Tract That land conveyed by Warranty Deed dated August 17, 1989, from Markus H. Lambert and Myra D. Lambert to Shell Oil Company, recorded in Book 3594, Page 10, and more particularly described as follows: A-6 THAT PART OF THE SOUTHEAST 1/4 SOUTHEAST 1/4 OF SECTION 14a TOWNSHIP 2 SOUTH, RANGE 47 WEST OF THE 6TH PRINCIPAL MERIDIANa MORE PARTICULARLY DESCRIBED AS FOLLOWS: COMMENCING AT THE SOUTHEAST CORNER OF SAID SECTION 14; THENCE NORTH ALONG THE EAST LINE OF SAID SECTION 14, A DISTANCE OF 30 FEETj THENCE NORTH 89 DEGREES 18 MINUTES WEST, A DISTANCE OF 669 FEET TO THE TRUE POINT OF BEGINNINQj THENCE NORTH, A DISTANCE OF 340-31 FE9T; THENCE SOUTH 89 DEGREES 18 MINUTES EAST, A DISTANCE OF 320 FEETj THENCE SOUTH. A -DISTANCE OF 340.31 FEETj THENCE NORTH-89 DEGREES 18 MINUTES WEST, A DISTANCE OF 320 FEET TO THE TRUE POINT OF BEGINNING, COUNTY OF ADAMS. STATE OF COLORADO. AND THAT PART OF THE SOUTHEAST 1/4 SOUTHEAST 1/4 OF SECTION 14, TOWNSHIP 2 SOUTH, RANGE 67 WEST OF THE &TH PRINCIPAL MERIDIAN. MORE PARTICULARLY DESCRIBED AS FOLLOWS: COMMENCING AT THE SOUTHEAST CORNER OF SAID SECTION 141 THENCE NORTH ALONG THE EAST LINE OF SAID SECTION 14, A DISTANCE OF 30 FEET'i THENCE WEST, A DISTANCE OF 30 FEET TO THE TRUE POINT OF BEGINNINGj THENCE NORTH 89 DEGREES is MINUTES WEST. A DISTANCE OF 329 FEETj THENCE NORTH# A DISTANCE OF 340.31 FEET; THENCE NORTH 69 DEGREES 18 MINUTES WEST, A DISTANCE OF 320 FEETj THENCE NORTH# A DISTANCE OF 410. 10 FEETj THENCE SOUTHEASTERLY, A DISTANCE OF 653. 2 FEEI TO A POINT WHICH IS 30 FEET WEST OF THE EAST LINE OF SAID SECTION 14 AND NORTH 01 DEGREES 01 MINUTES EAST A DISTANCE OF 613 FEET FROM THE TRUE' POINT OF BEGINNINGj THENCE SOUTH 01 DEGREES 01 MINUTES WEST, A DISTANCE OF 615 FEET TO THE TRUE POINT OF BEGINNING, COUNTY OF ADAMS, STATE OF COLORADO. also known by street and number as 11921 East 96th Avenue, Commerce City, Colorado Maul Tract That land conveyed by Warranty Deed dated October 19, 1989, from Ronald J. Maul to Shell oil Company, recorded in Book 3615, Page 7, and more particularly described as follows; PARCEL A: THAT PORTION OF THE SOUTHWEST 1/4 OF SECTION 13, TOWNSHIP 2 SOUTH, RANGE 67 WEST OF THE 6TH PRI14CIPAL MERIDIAN, ADAMS COUNTY. COLORADO. "ORE PARTICULARLY DESCRIBED AS: COMMENCING AT THE SOUTHWEST CORNER OF SAID SECTION 131 THENCE NORTH ALONG TIHE WEST LINE OF SAID SECTION 13, A DISTANCE OF 1364. 0 FEETs THENCE DEFLECTING RIGHT 90 DEGREES A DISTANCE OF 30. 0 FEET TO THE TRUE POINT OF BEGINNINGi THENCE DEFLECTING RIGHT 40 DECREES 7 MINUTES. A DISTANCE OF 605.0 FEETi THENCE DEFLECTING LEFT 20 DECREES 48 MINUTES. A DISTANCE OF 575. 0 FEET# THENCE DEFLECTING LEFT 9 DEGREES 03 MINUTES, A DISTANCE A OF 150. 0 FEETs THENCE DEFLECTING LEFT J0 DEGREES 20 MINUTES, DtSTANCE OF 79. 0 FEET, THENCE DEFLECTING LEFT L37 DEGREES 6 MINUTES 49 SECONDS. A DISTANCE OF t353.89 FEETi THENCE DEFLECTING LEFT 42 DEGREES 49 MINUTES 11 SECONDS, A DISTANCE OF 3oo. 0 FEE I i THEME DEFLECTING LEFT 90 DEGREES. A DISTANCE OF 262.0 FEET TO THE TRUE POINT OF BEGINNING. A-7 PARCEL B: THAT PART OF THE SOUTHWEST 1/4 OF SECTIO14 13. TOWNSHIP 2 SOUTH, RANGE 67 WEST OF THE 6TH PRINCIPAL MERIDIAN# ADAMS COUNTY COLORADOj DESCRIBED AS BEGINNING AT A POINT ON THE WEST LINE SAID SECTION 13. SAID POINT BEING 1136.4 FEET NORTH OF THE SOUTHWEST CORNER OF SAID SECTION M THENCE EAST AT RIGHT ANGLES TO SAID WEST LINE OF SECTION 13, 330.0 FEETi THENCE DEFLECTING RIGHT 90 DEGREES 10.4 FEET; THENCE DEFLECTING RIGHT 90 DEGREES 330.0 FEET MORE OR LESS TO A POINT ON THE WEST LINE OF SAID SECTION 131 THENCE NORTH ALONG THE WEST LINE OF SAID SECTION 13# 10.4 FEET MORE OR LESS TO THE POINT OF BEGINNING, EXCEPT THE WEST 30. 0 FEET OF THE ABOVE DESCRIBED PROPERTY. also known by street and number as 9760 Peoria AinalAone Tract That land conveyed by Warranty Deed dated August 17, 1989, from Thomas J. Smaldone to Shell Oil Company, recorded in Book 3594, Page 14, and more particularly described as follows: THAT PART OF THE SOUTHWEST 1/4 OF SECTION 13, TOWNSHIP 2 SOUTH, RANGE 67 WEST OF THE 6TH PRINCIPAL MERIDIAN, DESCRIBED AS FOLLOWS: BECINNING AT THE SOUTHWEST CORNER OF SAID SECTION 131 THEME EAST 2633.3 FEET ALONC THE SOUTH LINE OF SAID SECTION 13 TO THE SOUTH QUARTER CORNER OF SAID SECTION 131 THENCE NORTH 00 DEGREES 05 MINUTES EAST ALONG THE NORTH-SOUTH CENTERLINE OF SAID SECTION A DISTANCE OF 227 FEETj THENCZ*NORTH 63 DEGREES 33 MINUTES WEST A DISTANCE OF 199.6 FEETj THF14CE NORTH 72 DECREES 33 MINUTES WEST, A'DISTANCE OF 122 FEETo THENCE SOUTH 64 DECREES 58 MINUTES WEST A DISTANCE OF 344 FEETj THENCE NORTH 89 DEGREES 32 MINUTES WEST A DISTANCE OF 744 FEETj THENCE NORTH 79 DEGREES 32 MINUTES WEST, A. DISTANCE OF 150 FEETi THENCE NORTH 70 DEGREES 29 MINUTES WEST A DISTANCE OF 573 FEETj THENCIt NORTH 49 DEGREES 41 MINUTES WEST, A DISTANCE OF 6a3 FEETj THENCE NORTH 89 DECREES 48 MINUTES WEST, A DISTANCE OF 30 FEET TO THE WEST LINE OF SAID SECTIONi THENCE SOUTH 00 DEGREES 12 MINUTES WEST, A DISTANCE OF 864 FEET, MORE OR LESS, TO THE POINT OF BEGINNING. EXCEPT THAT PART OF THE SOUTHWEST 1/4 OF SCCTION 13, TOWNSHIP 2 SOUTH, RANGE 67 WEST OF THE &TH PRINCIPAL MERIDIAN, DESCRIBED AS FOLLOWS: BEGINNING AT THE SOUTH QUARTER CORNER OF SAID SECTION 131 THEME NORTH 00 DEGREES 05 MINUTES EAST ALONG THE NORTH-SOUTH CENTERLINE OF SAID SECTION 13 A DISTANCE OF 227 FEETi THENCE NORTH 63 DEGREES 3:3 MINUTES WEST TO A POINT THAT 19 EXACTLY 60 FEET WEST OF SAID NORTH-SOUTH CENTERLINE OF SAID SECTION 13; THENCE SOUTH TO A POINT ON THE SOUTH LINE OF SAID SECTION 13 WHICH IS EXACTLY 60 FEET WEST OF SAID SOUTH QUARTER CORNER OF SAID SECTION 131 THENCE EAST ALONG SAID SOUTH LINE OF SAID SECTION 13 A DISTANCE OF 60 FEET TO THE POINT OF BEGINNING, COUNTY OF ADAMS. STATE OF COLORADO. also known by street and number as 9610 Peoria Spencer Tract That land conveyed by Warranty Deed dated August 17, 1989, from Dennis I. Spencer and Patricia L. Spencer to Shell Oil Company, recorded in Book 3594, Page 12, and more particularly described as follows; A-8 THAT PART OF THE SOU?HfAST 1/4 OF SECTION 14, TOWNSHIP 2 SOUTH, RANGE 67 WEST OF THE &TH PRINCIPAL MERIDIAN, DESCRIBED AS FOLL13WS: BEGINNING AT THE SOUTHEAST CORNER OF SAID SECTION 141 THENCE NORTH 90 DECREES 00 MINUTES 00 SECONDS WEST ON AN ASSUMED - BEARING ALONG THE SOUTH LINE OF SAID SOUTHEAST 1/4, A DISTANCE OF 1013. 00 FEET TO THE TRUE POINT OF BrEOINNINGj THENCE CONTINUING NORTH 90 DECREES 00 MINUTES 00 SECONDS WEST ALONG SAID SOUTH LINE SOUTHEAST 1/4, A DISTANCE OF 237.67 FEET TO A POINT L290. 90 FEET EASTERLY OF THE SOUTHWEST CORNER OF SAID SOUTHEAST 1/4j THENCE NORTH 00 DECREES 00 MINUTES 00 SECONDS EAST ALONG A LINE PARALLEL TO THE EAST LINE OF SAID SOUTHEAST 114o A DISTANCE OF 1320. 00 FEETj THENCE NORTH 90 DECREES 00 MINUTES 00 SECONDS EAST. 337.67 FEET TO A POINT WHICH IS 1013. 00 FEET WEST OF THE EAST LINE OF SAID SOUTHEAST 1/4j THENCE SOUTH 00 DECREES 08 MINUTES 00 SECONDS WEST ALONG A LINE PARALLEL TO THE EAST LINE OF SAID SOUTHEAST 1/4o A' DISTANCE OF 1320. 00 FEET TO THE TRUE POINT OF VEGINNINQi EXCEPT THE SOUTH 30. 00 FEET THEREOF, COUNTY OF ADAMS* STATE OF COLORADM A-9 EXHMIT B ADAMS COUNTY STATE OF COLORADO CERTIFICATION 1, Robert Sack-, Clerk and Recorder of the Couno, ofAdants, State of Colorado, do herety cerrifi, that the attached is afull. true, and co e copof as appears upon the records of ntv office. Reception No. C) __I Book,)Vo. Page No. -3 I have hereunto-set np, hand and affixed the Seal of the CounV ofAdams, State of Colorado, this day of "ýýtLA/k-k-A.D., 19'7 ý-at S, 70 o'clock 4m Robert Sack Clerk and Recorder RECEPTION NO. C0183385 61. 00. BK: 4769 IS1 PG: 0297-0308 ROBERT SACK, ADAMS COUNTY;--'COLORADO 6/11/96 8:10 DECLARATION OF COVENANTS THIS DECLARATION OF COVENANTS, dated as of February 2, 1996, is made by SHELL OIL COMPANY, a Delaware corporation ("Shell"), for the benefit of the UNITED STATES OF AMERICA (the "United States") and the STATE OF COLORADO (the "State"). Recitals A. Shell owns the land in Adams County, Colorado described in Exhibit A attached hereto and forming a part hereof (the "Land"). B. A portion of the Land is subject to Revised License dated effective December 3, 1991 (the "License"), from Shell to the United States Department of the Army (the "Army"), notice of which was given by Memorandum of License dated effective as of December 3, 1991, between Shell and the Army, filed for recording June 25, 1992 at 8 a.m., and recorded under Reception No. 1074181 in Book 3920 at page 351 of the real property records of Adams County, Colorado. C. The Army, Shell, the State, the United States Environmental Protection Agency ("EPA"), and the United States Fish and Wildlife Service (11USFWS11) entered into Agreement for a Conceptual Remedy for the Cleanup of the Rocky Mountain Arsenal dated June 13, 1995 (the "Conceptual Remedy Agreement"). D. Paragraph 23 of the Conceptual Remedy Agreement requires Shell to execute and record covenants to preclude use of groundwater underlying the Land until certain conditions are satisfied. E. The Land is included within the Offpost Operable Unit (the "Offpost OU") of Rocky Mountain Arsenal, a National Priorities List site under the Comprehensive Environmental Response, Compensation, and Liability Act. F. A Record of Decision for the Offpost OU (the "Offpost ROD") was signed on December 19, 1995. G. Page Al-1 of Appendix B to the Offpost ROD also requires Shell to execute and record covenants to preclude use of groundwater underlying the Land until certain conditions are satisfied. H. Shell desires to grant the covenants set forth below in full satisfaction of its obligations under paragraph 23 of the Conceptual Remedy Agreement and under page Al-1 of Appendix B to the Offpost ROD. These covenants will protect, preserve and enhance the value of the adjacent land owned by the United States and known as Rocky Mountain Arsenal (the "Onpost OU"), as well as contribute to the overall remedy for Rocky Mountain Arsenal. Declaration In consideration of the foregoing and other good and valuable consideration, the receipt and sufficiency of which Shell acknowledges, Shell hereby covenants for itself and its successors and assigns as follows: 1. Use of Alluvial Groundwater Underlying the Land. No groundwater well for future use may be constructed on the Land if it is screened in the unconfined flow system ("UFS"), which is defined as the alluvial aquifer and the weathered upper portion of the Denver Formation, without the express written consent of the State and the United States for such period as this covenant remains in effect. Review and approval of any request for the construction of any such groundwater well shall be governed by the provisions of Appendix B, Attachment 3 of the Offpost ROD. Copies of the Offpost ROD are available at the following locations: Joint Administrative Record Document Facility ("JARDF") Rocky Mountain Arsenal 72nd Avenue and Quebec Street Commerce City, Colorado 80022-1748 EPA Region VIII Superfund Records Center 999 18th Street Denver, Colorado 80202-2466 Records Center Hazardous Materials & Waste Management Division Colorado Department of Public Health and Environment 4300 Cherry Creek Drive South Denver, Colorado 80222-1530 2. Use of Deeper Groundwater No groundwater may be used from any well on the Land that is sýreened in any aquifer beneath the UFS except as set forth in paragraph 4 of Appendix B, Attachment 3 of the Offpost ROD. 3. Exceptions. Notwithstanding the foregoing, no such approval shall be required for wells for groundwater sampling, wells for groundwater level measurements, wells for extraction for treatment of contaminated groundwater, and wells for reinjection of treated groundwater. 4. Covenants Run with Land; Enforcement. The covenants in paragraphs 1 and 2 touch and concern, run with, and burden the Land, and benefit the Onpost OU. They are granted for the benefit of the United States and the State to preserve the property values of the Onpost OU, and are enforceable by the United States, through the Army and EPA, and by the State. If there is a violation of either of those covenants that remains uncured after 30 day's prior written notice of the violation to Shell (or other owner of the Land or portion thereof whose action constitutes the violation), the United States and the State, or either of them, may institute a suit against the person violating the covenants to enjoin the violation by temporary or permanent injunction; provided, however, that for an irreparable ongoing or imminent violation the 30-day notice is not required. No failure by the United States or the State to institute such a suit shall be deemed to be a waiver or a forfeiture of,the right to enforce any covenant in this instrument. S. Notice. In every instrument conveying any interest in any portion of the Land, including without limitation deeds, leases, and mortgages, Shell shall include a notice in substantially the following form: NOTICE: THE INTEREST CONVEYED HEREBY IS SUBJECT TO DECLARATION OF COVENANTS DATED AS OF FEBRUARY 2, 1996, RECORDED UNDER RECEPTION NO. IN BOOK AT PAGE OF THE REAL PROPERTY RECORDS OF ADAMS COUNTY, COLORADO, IN FAVOR OF AND ENFORCEABLE BY THE UNITED STATES OF AMERICA AND THE STATE OF COLORADO. 6. Title. Shell represents to the United States and the State that Shell's title to the Land is free and clear of all liens, encumbrances, and burdens arising by, through, or under Shell, but not otherwise, except for the lien for taxes not yet due and except for the License; and Shell will forever warrant and defend title to the Land against all persons claiming an interest therein by, through, or under Shell, but not otherwise, except for the interest created by the License. 7. Release. The covenants contained herein shall be released in accordance with the procedures outlined in paragraph 6 of Appendix B, Attachment 3 of the Offpost ROD. -2- Se Kincellaneous. (a) No Aditission of Liability. The execution and delivery of this instrument and Appendix B, Attachment 3 of the Offpost ROD by Shell shall not be construed as an admission of any liability on its part. Neither this instrument nor Appendix B, Attachment 3 of the Offpost ROD may be offered in evidence in any administrative or judicial proceeding, except for a proceeding to enforce its provisions. (b) No Warranty. Except as specifically set forth in paragraph 6, this instrument is executed without any representation or warranty, express or implied. (c) Readings. The 'headings in this instrument are for guidance and convenience of reference only and do not limit or otherwise affect the meanings of any of its provisions. (d) Further Assurances. 'Shell, EPA, the State, the Army, and USFWS shall execute and deliver or cause to be executed and delivered such other instruments, and take such other actions, as may be reasonably necessary or advisable to carry out the purposes of this instrument. (9) Entire Agreement. This instrument and Appendix B, Attachment 3 of the Offpost ROD constitute the entire understanding among Shell, EPA, the State, the Army, and USFWS with respect to the subject matter hereof, superseding all negotiations, prior discussions, and prior agreements or understandings with respect to the subject matter. (g) No Assignment. Neither the United States nor the State may assign any of their respective rights under this instrument without the prior written consent of Shell. (h) Parties in Interest. This instrument shall be binding upon and inure to the benefit of the parties hereto and their respective successors and assigns. Nothing in this instrument, express or implied, is intended to confer upon any other person or entity any benefit, right, or remedy. EXECUTED as of the date first above written. SHELL OIL COMPANY By Vice President HS&E Shell Chemical Company STATE OF COLORADO CITY AND ss. COUNTY OF DFJPM The foregoing instrument was acknowledged before me this 10th day of June, 1996,by Rand Shulman, as Vice President HS&E, Shell Chemical Company, a subsidiary of Shell Oil Company, a Delaware corporation, on behalf of the corporation. Witness my hand and official seal. Notýfry Public My commission expires: April 9, 2000 -3- EXHIBIT A The following described land in Adams County, Colorado: Adams County Joint Ventuge Tract The land conveyed by Warranty Deed dated February 26, 1991, from the Adams County Joint Venture to Shell Oil Company and more particularly described as follows: Southwest Quarter of Section 13, Township 2 South, Range 67 West, excluding therefrom those tracts of land described in the following deeds: 1) Book 771 at Page 234 2) Book 1003 at Page 527 3) Book 1037 at Page 479 but including the east 60 feet of the tract of land described in said Book 771 at Page 234, all being in records of said Adams County. Commerce City Tract The land conveyed by Warranty Deed dated October 15, 1991, from the City of Commerce City, Colorado, to Shell Oil Company, recorded in Book 3839, Page 873, and more particularly described as follows: A parcel of land situated in a portion of Lots 3,' 4 and 6, Block 1, ADCO Industrial Park:Subdivision, being a portion of the Southwest one-quarter of Section 14, Township 2 South, Range 67 West of the Sixth Principal Meridian, County of Adams, State of Colorado, more particularly described as follows: Commencing at the center one-quarter corner of said Section 14, said point also being the Northeast corner of said Lot 6, said point being the TRUE POINT OF BEGINNING; thence South 00*071250 West along the East line of said Lots 6 and 3 and along the East line of the Southwest one-quarter of the Southwest one-quarter of said Section 14 a distance of 1058.92 feet; thence North 62*321170 West a ýdistance of 824.60 feet to a point on the Northwesterly line of said Lot 6, said point also being on the Southeasterly right of way line of Colorado State Highway No. 2 and U.S. Highway No. 6; thence the following three courses along the Northwesterly line of said Lot 6 and the Southeasterly right of way line of said Colorado State Highway No. 2 and U.S. Highway No. 6; thence North 45*001480 East a distance of 396.72 feet; thence North 46*111031 East a distance of 299-95 feet; thence North 430071400 East a distance of 261.54 feet to the Northwest corner of said Lot 6; thence South 89*521350 East along the North line of said Lot 6 a distance of 58.15 feet to the TRUE POINT OF BEGINNING, County of Adams, State of Colorado. Fischer Tract The land conveyed by Warranty Deed dated January 30, 1991, from Peggy Nadine Fischer, n/k/a Peggy Nadine Hite, to Shell oil Company recorded in Book 3748, Page 724, and more particularly described as follows: Block 1, Fischer-Hoffman Tract Adams County, Colorado also known by street and number as 9-955 and -9961 Peoria Hickey Tract The land conveyed by Warranty Deed dated January 17, 1991, from Michael E. Hickey and Charles E. Hickey to Shell Oil company recorded in Book 3746, Page 328 and more particularly described as follows: PARCEL A: The SE 1/4 of Section 14, Township 2 South, Range 67 West of the 6th P.M. EXCEPT the South 30 feet thereof; EXCEPT that portion-thereof lying within Peoria Street, 96th Avenue and East 100th Avenue; EXCEPT that portion thereof lying within the Subdivision of Fischer-Hoffman Tract; EXCEPT that portion thereof described in deeds recorded December 19, 1960 in Book 883 at Page 558, August 21, 1969 in Book 1539 at Page 239 and August 28, 1973, in Book 1884 at Page 850 and EXCEPT any portion thereof that may lie Westerly of the West line of that tract of land described in deed recorded December 9, 1960 in Book 882 at Page 335. County of Adams, State of Colorado. Note: Land referred to in deed recorded in Book 883 at Page 558 described as follows: A parcel of land located in the SE 1/4 Section 14, Township 2 South, Range 67 West, 6th P.M., described as follows: BEGINNING at a point which is 2640 feet South and 30 feet West of the Northeast corner NE 1/4 Section 14, Township 2 South, Range 67 West; thence West 960 feet, thence South 1320 feet, thence West 1220 feet, thence South 1290 feet, thence East 2180 feet, thence North 2610 feet to the POINT OF BEGINNING; NOTE: Land referred to in deed recorded in Book 1539 at Page 239 described as follows: That part of the Southeast quarter of Section 14, Township 2 South, Range 67 West of the 6th Principal Meridian, Adams County, Colorado, described as follows: -2- BEGINNING at the Southeast corner said Section 14; thence North 90 deg. 00 min. 00 sec. West on an assumed bearing along the South line said Southeast one-quarter a distance of 1013.00 feet to the TRUE POINT OF BEGINNING; thence continuing North 90 deg. 00 min. 00 sec. West along said South line Southeast one-quarter a distance of 1188.57 feet to a point 430.00 feet Easterly of the Southwest corner said Southeast one-quarter; thence North 00 deg. 06 min. 30 sec. East along a line parallel to the West line said Southeast one-quarter a distance of 1320.00 feet; thence North 90 deg. 00 sec. 00 min. East, 1189.14 feet to a point which is 1013.00 feet West of the East line said Southeast one-quarter; thence South 00 deg. 08 min. 00 sec. West along a line parallel to the East line said Southeast one-quarter a distance of 1320.00 feet to the TRUE POINT OF BEGINNING, EXCEPT the South 30.00 feet thereof. NOTE: Land referred to in Book 1884 at Page 850 described as follow: BEGINNING at a point 30 feet North and 669 feet West of the Southeast corner of the Southeast quarter of Section 14, Township 2 South, Range 67 West of the Sixth P.M., County of Adams, State of Colorado; thence North, a distance of 1290 feet, thence West, a distance of 344 feet to an existing pin; thence South a distance of 1290 feet more or less, to a point 30 feet North of the South line of the Southeast quarter of Section 14; thence East and parallel with the said South line, a distance of 344 feet to the POINT OF BEGINNING. PARCEL B: That part of the NE 1/4 of Section 14, Township 2 South, Range 67 West of the 6th P.M., lying Southeasterly of U.S. Highway No. 6 and Southerly of the South lines of those tracts of land described in deeds recorded November 5, 1967 in Book 1361 at Page 76 and June 3, 1982 in Book 2649 at Page 750, EXCEPT that portion thereof lying within Peoria Street and EXCEPT that portion thereof described in deed recorded December 19, 1960 in Book 883 at Page 556, County of Adams, State of Colorado. -3- NOTE: Land referred to in Book 1361 at Page 76, described as follows: That part of the NE 1/4 of Section 14, Township 2 South, Range 67 West of the 6th P.M., described as follows: BEGINNING at the East Quarter Corner of said Section; thence Northerly, along the East line of said ' Section, 450 feet; thence Westerly, on an angle to the left of 89 deg. 40 min. 08 sec., parallel with the South line of said NE 1/4, a distance of 990 feet to the TRUE POINT OF BEGINNING; thence Westerly, parallel with said South line, 1298.14 feet to the Easterly right of way line ofColorado State Highway No. 2; thence on an angle to the right of 131 deg. 46 min. 08 sec. and along said Easterly right of way line 1313.94 feet to a point 1430 feet North of the South line of said NE 1/4; thence Easterly on an angle to the right of 48 deg. 13 min. 52 sec., parallel with the South line of said NE 1/4, a distance of 417.23 feet to a point 990 feet West of the East line of said NE 1/4; thence Southerly, on an angle to the right of 89 deg. 40 min. 08 sec. and parallel with said East line, 980-feet to the TRUE POINT OF BEGINNING. NOTE: Land referred to in Book'883 at Page 556 described as follows: A parcel of land located in the NE 1/4 Section 14, Township 2 South, Range 67 West, 6th P.M. described as follows: BEGINNING at a point which is 2190 feet South and 30 feet West of the Northeast corner NE 1/4 Section 14, Township 2 South, Range 67 West, thence West 630 feet; thence South 450 feet; thence East 630 feet; thence North 450 feet; to the POINT OF BEGINNING. NOTE: Land referred,to'--in Book 2649.at Page 753 described as followsi" A parcel of land in the Northeast 1/4 of Section 14, Township 2 South, Range 67 West of the 6th Principal Meridian, Adams County, Colorado, described as: BEGINNING at the East 1/4 corner of said Section 14; thence North 00 deg. 00 min. 00 sec. East, on an assumed bearing along the East line of said Northeast 1/4, a distance of 520.00 feet; thence North 89 deg. 40 min. 08 sec. West, parallel with the South line said Northeast 1/4 a distance of 30.00 feet to the TRUE POINT OF BEGINNING; thence continuing North 89 deg. 40 min. 08 sec. West, a distance of 960.00 feet; thence North 00 deg. 00 min. 00 sec. East parallel with the East line of said -4- Northeast 1/4 a distance of 910.00 feet; thence North 89 deg. 40 min. 08 sec. West a distance of 417.23 feet to a point on the Easterly right of way line of Colorado State Highway No. 2: thence North 42 deg. 04 min 00 sec. East along said Easterly right of way line a distance of 250.85 feet; thence North 42 deg. 24 min. 20 sec. East continuing along said Easterly right of way line a distance of 204.10 feet to a point on the South line of the Public service Company right of way; thence South 89 deg. 32 min. 10 sec. East along said South r ight of way line a distance of 1071.55 feet to a point on the West right of way line of Peoria Street; thence South 00 deg. 00 min. 00 sec. West along said West right of way line and parallel with the East line said Northeast 1/4 a distance of 1246.21 feet to the TRUE POINT OF BEGINNING. Hoffman Tract The land conveyed by Warranty Deed dated January 30, 1991, from Clifford R. Hoffman and Joan Hoffman to Shell Oil Company recorded in Book 3748, Page 201, and more particularly described as follows: Block 2, Fischer-Hoffman Tract Adams County, Colorado as known by street and number as 9925 Peoria. A, Maul Tract The land conveyed by Warranty Deed dated January 24, 1991, from Albert L. Maul and Evelyn F. Maul to Shell Oil Company recorded in Book 3747, Page 424, and more particularly described as follows: That part of the Northeast 1/4 of Section 14, Township 2 South, Range 67 West of the 6th P.M., described as follows: B EGINNING at a point which is located 2190 feet South and 30 feet West of the Northeast corner of said NE 1/4; thence West a distance of 630 feet; thence South a distance of 450 feet; thence East a distance of 630 feet; thence North a distance of 450 feet to the POINT OF BEGINNING Adams County, Colorado as known by street and number as 10021 Peoria Ohle Tract The land conveyed by Warranty Deed dated February 21, 1991, from Albert H. Ohle and Barbara J. Ohle to Shell Oil Company recorded in Book 3755, Page 441, and more particularly described as follows: A tract of land located in the SE 1/4 of Section 14, Township 2 South, Range 67 West of the 6th P.M., described as follows: -5- Beginning at a point 30 feet North and 669 feet West of the Southeast corner of the SE 1/4 of said Section 14, thence North, a distance of 1290 feet; thence West, a distance of 344 feet to an existing pin; thence South, a distance of 1290 feet; more or less, to a point 30 feet North of the South line of the SE 1/4 of said Section 14; thence East and parallel with the said South line, a distance of 344 feet to the Point of Beginning, County of Adams, State of Colorado, as known by street and number as 11841 E. 96th Avenue. Werth Tract The land conveyed by Warranty Deed dated January 30, 1991, from Ronald J. Werth and Virginia A. Werth to Shell oil Company recorded in Book 3749, Page 985, and more particularly described as follows: All of Block 2, Wagner Tract Adams County, Colorado as known by street and number as 9755 Peoria Street. Holstine Tract The land conveyed by Warranty Deed dated February 22, 1990, from Byron W. Holstine to Shell Oil Company, recorded in Book 3650, Page 425, and more particularly described as follows: TnAT PART OF THE SOVTHE^ST 1/4 OF SECTION 14, TOWNSHIP 2 SOVTH# RANGE 67 WC9T Or THE 6TH PRINCIPAL MERIDIAN* ADAMS CCKONTY@ COLORADO DESCRIBED AS: NEVINNING AT THE SOVTHEAST CORNER OF 3^10 SECTION 24, TH9WC6 NOR+H VO DECREES 00 MINUTES 00 SECONDS WCST 004 AN ASGWWV RCARtNQ ^LONQ* THE 30VTM LINE SAID SOUTHEAST If4 A DISTANCE OF 12SO.&7 FIMT TO THE TRUR-POINT OF NEGINNING1 THENCE CONTINUING NORTH TO DEGREES 00 M:NUTE$ 00 SECON03 WEST ^LONQ 6^90 SOUTH LINE SOUTHEAST 114 A DISTANCE OF 313.23 F9*T TO A POINT 767.67 FELT EASTERLY OF THE 8OVTHWE6T CORNER SAID SOUTHEAST 1/4j THENCE NORTH 00 DECREES 04 MINUTES 30 8ECONDS CAST ALONs A LINE PARALLEL To THE WEST LINE SAID SOUTHEAST 1/4 A DISTANCE OF 1320.00 FEET1 THENC9 PMTH-90 DECREES 00 MINUTES 00 SECONDS EAST, 013.90 FEET TO A POINT WHICH 15 1330.4p7 FEET WEST OF THE CAST LINE SAID SOUTHEAST 1/41 THENCE SOUTH 00 DECREES 08 MINUTEG 00 SECONDS WEST ALONQ A LINE PARALLEL TO THE EAST LINE 0^10 SOUTHEAST Jf4s A DISTANCE -OF 1320-00 r=T TO THE TRUE POINT OF NEGINNING EXCEPT SOUTH 30.00 FEET THEREOF. Lambert Tract That land conveyed by Warranty Deed dated August 17, 1989, from Markus H. Lambert and Myra D. Lambert to Shell Oil Company, recorded in Book 3594, Page 10, and more particularly described as follows: -6- THAT PART OF THE SOUTHEAST 1/4 SOUTHEAST 1/4 OF TOWNSHIP 2 SOUTH, SECTION 14, RANGE 67 WUT OF THE 6TH PRINCIPAL PWAIDIANO MORE PARTICULARLY DESCRIBED AS FOLLOWS: COMMENCING AT THE SOUTHEAST CORNER OF SAID SECTION 14; THENCE NORTH ALONG THE EAST LINE OF SAID SECTION OF 30 FEETj 14, A DISTANCE THENCE NORTH 89 DEGREES IS MINUTES WEST# A DISTANCE OF 669 FEET TO THE TRUE POINT OF BEGINNINGj THENCE NORTH, A DISTANCE OF 340.31 FEETj THENCE SOUTH 89 DEGREES 18 MINUTES EASTo A DISTANCE FEETj OF 320 THENCE SOUTH. A-DISTANCE OF 340.31 FEETi THENCE NORTH.89 DEGREES IS MINUTES WEST, A DISTANCE TO THE OF 320 FEET TRUE POINT OF BEGINNING, COUNTY OF ADAMS, COLORADO. STATE OF AND THAT PART OF THE SOUTHEAST 1/4 SOUTHEAST 1/4 OF SECTION 140 TOWNSHIP 2 SOUTH, RANGE 67 WEST OF THE 6TH PRINCIPAL MERIDIAN. MORE PARTICULARLY DESCRIBED AS FOLLOWS; COMMENCING AT THE SOUTHEAST CORNER OF SAID SECTION 141 THENCE NORTH ALONG THE EAST LINE OF SAID SECTION OF 30 FEETi 14, A DISTANCE THENCE WEST, A DISTANCE OF 30 FEET TO THE BEGINNINGj TRUE POINT OF THENCE NORTH 89 DEGREES 18 MINUTES WEST, A DISTANCE FEETj OF 319 THENCE NORTH, A DISTANCE OF 340-31 FEETj THENCE NORTH 89 DECREES 18 MINUTES WEST, A DISTANCE FEETj OF 320 THENCE NORTH* A DISTANCE OF 410.10 FEETj THENCE SOUTHEASTERLY, A DISTANCE OF 653. 2 FEET TO A POINT WHICH 15 30 FEET WEST OF THE EAST LINE OF SAID SECTION 01 DECREES 14 AND NORTH 01 MINUTES EAST A DISTANCE OF 615 POINT OF BEGINNINGi FEET FROM THE TRUE' THENCE SOUTH 01 DEGREES 01 MINUTES WEST, A DISTANCE OF 615 FVXT TO THE TRUE POINT OF BEGINNING, COUNTY COLORADO. OF ADAK8o STATE OF also known by street and number as 11921 East 96th Avenue, Commerce City, Colorado Maul Tract That-land conveyed by Warranty Deed dated October 19, 1989, from Ronald - J. Maul -fo'-Miell- Oil Company, recorded in Book 3615, Page 7, and more -particularly described as follows: PARCEL A: THAT PORTION OF THE SOUTHWEST 1/4 OF SECTION 13, TOWNSHIP 2 SOUTH, RANGE 67 WEST OF THE 6TH PRINCIPAL MERIDIAN# ADAMS COUNTY, COLORADO- "ORE PARTICULARLY DESCRIBED AS: COMPENC IINC AT THE SOUTHWEST CORNER OF SAID SECTION 131 THENCE NORTH ALONG.THE WEST LINE OF SAID SECTION 13# A DISTANCE OF 864.0 FEETj THENCE DEFLECTING RIGHT 90 DEGREES A DISTANCE OF 30.0 FEET M THE TRUE POINT OF BECINNINGi THENCE DEFLECTING RIGHT 40 DECREES 7 MINUTES,'.A DISTANCE OF 685.0 FEETj THENCE DEFLECTING LEFT 20 DECREES 40 MINUTES. A DISTANCE OF 575.0 FEETi THENCE DEFLECTING LEFT 9 DEGREES 03 MINUTES, A DISTANCE OF 150.0 FEET# THENCE DEFLECTING LEFT 10 DEGREES 20 MINUTES, A DISTANCE OF 79.0 FEETJ THENCE DEFLECTING LEFT 137 DECREES MINUTES 49 SECONDS. A DISTANCE OF 1353.89 FEETj THEME DEFLECTING LEFT 42 DEGREES 49 MINUTES 11 SECONDS# A DISTANCE OF 300.0 FEED THENCE DEFLECTINC LEFT 90 DEGREES, A DISTANCE OF 262.0 FEET TO THE TRUE POINT OF BEGINNING. -7- PARCEL 9: THAT PART OF THE SOUTHWEST 1/4 OF SECTION 13, TOWNSHIP 2 SOUTH, RANGE 67 WEST OF THE 6TH PRINCIPAL MERIDIAN# ADAMS COUNTY COLORADOj DESCRIBED AS BEGINNING AT A POINT ON THE WEST LINE SAID SECTION 13, SAID POINT BEING 1136.4 FEET NORTH OF THE SOUTHWEST CORNER OF SAID SECTION L3, THENCE EAST AT RIGHT ANGLES TO SAID WEST LINE OF SECTION 13, 330.0 FEETj THENCE DEFLECTING RIGHT 90 DEGREES 10.4 FEETs THENCE DEFLECTING RIGHT 90 DEGREES 330.0 FEET "ORE OR LESS TO A POINT ON THE WEST LINE OF SAID SECTION 131 THENCE NORTH ALONG THE WEST LINE OF SAID SECTION t3o 10.4 FEET MORE OR LESS TO THE POINT OF BEGINNINGe EXCEPT THE WEST 30.0 FEEI OF THE ABOVE DESCRIBED PROPERTY. also known by street and number as 9760 Peoria Smaldone Tract That land conveyed by Warranty Deed dated August 17, 1989, from Thomas J. Smaldone to Shell Oil Company, recorded in Book 3594, Page 14, and more particularly described as follows: THAT PART OF THE SOUTHWEST 1/4 OF SECTION 13, TOWNSHIP 2 SOUTH, RANGE 67 WEST OF THE 6TH PRINCIPAL MERIDIAN,ý DESCRIBED AS FOLLOWS: BEGINNING AT THE SOUTHWEST CORNER OF SAID SECTION 131 THEME EAST 2633.3 FEET ALONC THE SOUTH LINE OF SAID SECTION 13 TO THE SOUTH QUARTER CORNER OF SAID SECTION 131 THENCE NORTH 00 DEGREES 03 MINUTES EAST ALONG THE NORTH-SOUTH CENTERLINE OF 8AI1D SECTION A DISTANCE OF 227 FEETj TWENCE'NORTH 63 DEGREES 33 MINUTES WEST A DISTANCE OF 199. 6 FEETo THENCE NORTH 72 DECREES 33 MINUTES WEST, A'DISTANCE OF 122 FEETi THENCE SOUTH 64 DECREES 58 MINUTES WEST A DISTANCE OF 344 FEETi THENCE NORTH 89 DEGREES 52 mrNUTES WEST A DISTANCE OF 764 FEETi THFENCE NORTH 79 DEGREES 32 MINUTES WEST, A. DISTANCE OF 150 FEETi THENCE NORTH 70 DECREES 29 miNuTEs WEST A DISTANCE OF 573 FEETi THENCIt NORTH 49 DECREES 41 MINUTES WEST, A DISTANCE OF 683 FEE1j THENCE NORTH 139 DEGREES 48 MINUTES WESTs A DISTANCE OF 30 FEET TO THE WEST LINE Or $AID SECTION; THENCE SOUTH 00 DEGREES 12 MINUTES WEST, A DISTANCE OF 864 FEET, MORE OR LESS, TO THE POINT OF BEGINNINGs EXCEPT THAT PART OF THE SOUTHWEST 1/4 OF SECTION 13, TOWNSHIP 2 SOUTH, RANGE 67 WEST OF THE 6TH PRINCIPAL MERIDIAN, DESCRIBED AS FOLLOWS: BEGINNING AT THE SOUTH QUARTER CORNER OF SAID SECTION 13) THENCE NORTH 00 DECREES 05 MINUTES EAST ALONG THE NORTH-SOUTH CENTERLINE OF SAID SECTION 13 A DISTANCE OF 227 FEETi THENCE NORTH 63 DEGREES 33 MINUTES WEST TO A POINT THAT 13 EXACTLY 60 FEET WEST OF SAID NORTH-SOUTH CENTERLINE OF SAID SECTION 131 THENCE SOUTH TO A POLNT ON THE SOUTH LINE OF SAID SECTION 13 WHICH IS EXACTLY 60 FEET WEST OF SAID SOUTH QUARTER CORNER OF SAID SECTION 13; THENCE EAST ALONG SAID SOUTH LINE OF SAID SECTION 13 A DISTANCE OF 60 FEET TO THE POINT OF BEGINNING, COUNTY OF ADAMS, STATE OF COLORADO. also known by street and number as 9610 Peoria SRencer Iract That land conveyed by Warranty Deed dated August 17, 1989, from Dennis i. Spencer and Patricia L. Spencer to Shell Oil Company, recorded in Book 3594, Page 12, and more particularly described as follows: -8- THAT PART OF THE SOUTHEAST 1/4 OF SECTION 14, TOWNSHIP 2 SOUTH, RANCE 67 WEST OF THE 6TH PRINCIPAL MERIDIAN, DESCRIBED AS FOLLOWS: BEGINNING AT THE SOUTHEAST CORNER OF SAID SECTION-14i THENCE NORTH 90 DEGREES 00 MINUTES 00 SECONDS WEST ON AN ASSUMED - BEARING ALONG THE SOUTH LINE OF SAID SOUTHEAST 1/4, A DISTANCE OF 1013.00 FEET TO THE TRUE POINT OF BEGINNINGs THENCE CONTINUING NORTH 90 DEGREES 00 MINUTES 00 SECONDS WEST ALONG SAID SOUTH LINE SOUTHEAST 1/4, A DISTANCE OF 337.67 FEET TO A POINT L290-90 FEET EASTERLY OF THE SOUTHWEST CORNER OF SAID SOUTHEAST 1/4s THENCE N13RTH 00 DEGREES 08 MINUTES 00 SECONDS EAST ALONG A LINE PARALLEL TO THE EAST LINE OF SAID SOUTHEAST 1/4v A DISTANCE OF 1320.00 FEET; THENCE NORTH 90 DECREES 00 MINUTES 00 SECONDS EAST, 337.67 FEET TO A POINT WHICH IS 1013.00 FEET WEST OF THE EAST LINE OF SAID SOUTHEAST 1/4; THENCE SOUTH 00 DEGREES 09 MINUTES 00 SECONDS WEST ALONG A LINE PARALLEL TO THE EAST LINE OF SAID SOUTHEAST 1/4, A' DISTANCE OF 1320.00 FEET TO THE TRUE POINT OF VEGINNINGi EXCEPT THE SOVTH 30.00 FEET THEREOF# COUNTY OF ADAMS# STATE OF COLORADO. -9- EXHIBIT C RELEASE OF RESTRICTIVE COVENANTS By paragraph 1 of Declaration of Restrictive Covenants dated as of February 2, 1996 (the "Declaration"), filed for recording A, 1996, and recorded under Reception No. in Book at page of the real property records of Adams County, Colorado, Shell Oil Company, a Delaware corporation ("Shell"), granted a restrictive covenant for the benefit of the United States of America and the State of Colorado (the "State"), prohibiting the construction of groundwater wells on the land in Adams County, Colorado described in Exhibit A attached to the Declaration (the "Land") and screened in the unconfined flow system, all as more fully described therein. Neither the United States of America nor the State have assigned any of their rights under the Declaration. The Army, the State, and EPA have all acknowledged that the conditions specified in paragraph 6 of Appendix B, Attachment 3 of the offpost Record of Decision for release of the covenant in paragraph 1 of the Declaration have been satisfied. IN CONSIDERATION of the foregoing and of other good and valuable consideration, the receipt and sufficiency of which the parties acknowledge, the United States of America, through the United States Department of the Army, and the State hereby release and quitclaim to Shell and its successors and assigns all their right, title, and interest, if any, in and to the Land insofar as they relate to paragraph 1 of the Declaration. The covenant granted under paragraph 2 of the Declaration is in full force and effect and is not affected by this instrument. EXECUTED this day of 11 20_. FOR THE UNITED STATES OF AMERICA By the Department of the Army By Title: C-1 FOR THE STATE OF COLORADO By the Colorado Department of Public Health and Environment B --- Title: STATE OF ss. COUNTY OF The foregoing instrument was acknowledged before me this day of - 11 20-, by 11 as of the United States Department of the Army, on behalf of the United States of America. Witness my hand and official seal. Notary Public My commission expires: STATE OF ss. COUNTY OF The foregoing instrument was acknowledged before me this day of - 1 20 by I as of E-he Co-lorado Department of Public Health and Environment, on behalf.of the State of Colorado. Witness my hand and official seal. Notary Public My commission expires: C-2 SCHEDULE 1 CSRG PQL Analyte (ppb) (ppb) Aldrin 0.002 0.05 Arsenic 2.35 Atrazine 3 Benzene 3 Carbon tetrachloride 0.3 0.99 Chlordane 0.03 0.095 Chloride 250,000 Chlorobenzene 25 Chloroform 6 CPMS 30 CPMSO 36 CPMS02 36 DBCP 0.2 DCPD 46 DDE 0.1 - DDT 0.1 1,2-Dichloroethane 0.4 1.0 1,3-Dichlorobenzene 6.5 Dieldrin 0.002 0.05 DIMP 8 Dithiane 18 Endrin 0.2 Ethylbenzene 200 Fluoride 2,000 Hexachlorocyclopentadiene 0.23 Isodrin 0.06 Malathion 100 NDMA 0.007 0.033 1,4-Oxathiane 160 Sulfate 540,000 Tetrachloroethylene 5 Toluene 1,000 Trichloroethylene 3 Xylenes 1,000 CSRG Containment System Remediation Goals for the Offpost Groundwater Intercept and Treatment System PQL Practical Quantitation Limit (presented only when the PQL is greater than the CSRG) For purposes of the covenants in paragraphs 1 and 2 of the Declaration of Restrictive Covenants, the appropriate standard for a given analyte is its CSRG or its PQL if the PQL is greater than the CSRG. 1-1 SCHEDULE 2 WELLS 37062 37065 37071 37076 37081 37083 37085-Den 37106 37116 37319 37338 37369 37370 37377 37378 37390-Den 37391 37392 2-1 Appendix C WELL CLOSURE CRITERIA 500920-4 M9800114 Appendix C In June 1988, the Final Decision Document for the Interim Response Action for the Closure of Aban- doned Wells at Rocky Mountain Arsenal was issued by the U.S. Department of the Army (Army). This final document was issued following review and comment by Region VIII U.S. Environmental Protection Agency (EPA) and the Colorado Department of Health. This Interim Response Action (IRA) included only onpost wells in its coverage. EPA proposed modification of this IRA to include offpost wells in a letter to the Army dated March 15, 1990. EPA proposed criteria for the selection of wells to be abandoned and closed in the Offpost Study Area. In a letter dated June 13, 1991 (U.S. Army, 1991) to the Colorado Department of Public Health and Environment (CDPHE), the Army agreed in principle with the EPA request to modify the Well Closure IRA to include wells meeting the criteria in the Offpost Studv Area. The following set of criteria were developed to identify wells to be abandoned in the Offpost Study Area. I . Oftpost wells will be abandoned according to the regulations set forth by the Office of the State Engineer a. if the well is completed in one or more aquifers below the alluvial aquifer, and b. if the well is judged to be of improper construction or is in deteriorating condition such that it is leaking from the alluvial aquifer to lower aquifers as indicated by physical parameters (such as hardness and conductivity measurements), and C. if the well contains contaminants which originated from RMA in excess of the remedia- tion goals. 2. Offpost wells will be monitored a minimum of annually a. if the well is completed in one or more aquifers below the alluvial aquifer, and b. if the well is within 500 feet of a groundwater plume which originated from the RMA, or C. if the well is judged to be of improper construction or is in deteriorating condition such that it is leaking from the alluvial aquifer to lower aquifers as indicated by physical parameters (such as hardness and conductivity measurements), and d. if the well contains contaminants originating from the RMA at any level. 3. If, based on current water table data, the well is located in an area of dry alluvium, the well will not be considered a candidate for closure. 4. Wells located on the property currently owned by Shell are included in this well closure plan. 21905 402010 Harding Lawson Associates C-1 0805121495 R02 Appendix C 5. Well closure will be at the expense of the United States. 6. Well closure methods will be identical to those used for the closure of onpost wells. 7. The United States and the Department of the Army are removed from liability for dealing with unpermitted wells. 8. Following identification of wells meeting all of the criteria listed in item 2 above, the Tri-County Health Department (TCHD) will notify individual well owners informing them of suspected faulty construction and request permission to enter the property and abandon the well. THCD will inform the Army if and when permission has been received from the well owner to close the well. 9. Well closure expenses will not be borne by the United States in the event that unused wells are listed for closure and the well owner is known. Pursuant to Rule 11.1.1, Abandonment Stan- dards (2 Code of Colorado Regulations 402-2), it is the responsibility of the well owner to have an unused well properly plugged and abandoned. A list of wells meeting the closure criteria will be compiled at a meeting of the parties' technical staff. A list of wells to be monitored will also be compiled. A consensus will be reached on guidelines to be used to evaluate the hardness and conductivity data. At the time of the five year review the monitoring information will be reviewed and it will be determined by the par-ties if a continued monitoring of wells in the deeper aquifers is warranted. C-2 Harding Lawson Associates '21905 402010 0805121495 R02 Appendix C REFERENCES Shell Oil Company, 1991, Letter to U.S. Department of the Army, July 3. U.S. Department of the Army, 1991, Letter to Colorado Department of Health, June 13. U.S. Environmental Protection Agency, 1991, Letter to U.S. Department of the Army and Shell Oil Company, January 6. 21905 402010 Harding Lawson Associates C-3 0805121495 R02