US EPA RECORDS CENTER REGION 5

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FOURTH FIVE-YEAR REVIEW REPORT FOR TWIN CITIES AIR FOI{CE RESERVE BASE, S~LARMSRANGELANDnLL HENNEPIN COUNTY, MINNESOTA

Prepared by

934th Airlift , U.S. Air Force Reserve Minneapolis-St. Paul International Airport Air Reserve Station Minneapolis, Minnesota

Approved by: . lJIlAi /3 R Date I

~ J ar . rl, i eet r ./ CSupe nd Division U.S. Environmental Protection.Agency, Region 5 TABLE OF CONTENTS

List of Acronyms 3 Executive Summary 4 Five Year Review Summary Form 4 I. Introduction 6 II. Site Chronology 8 III. Background 8 Physical Characteristics 8 Land and Resource Use 9 History ofContaluination 9 Initial Response 10 Basis for Taking Action 10 IV. Remedial Actions 11 Remedy Selection 11 Remedy Implementation 11 Institutional Controls 13 System Operations/Operation and Maintenance (O&M) 15 V. Progress Since the Last Review .15 Status of Recommendations and Follow-up Actions from Last Review 15 Status ofOther Prior Issues 15 VI. Five-Year Review Process 16 Administrative COluponents 16 Community Notification and Involvement 16 Document Review 16 Data Review 17 Site Inspection 18 VII. Technical Assessment 18 Question A: Is the remedy functioning as intended by the decision documents? 18 Question B: Are the exposure assumptions, toxicity data, cleanup levels, and remedial action objectives used at the time of the remedy selection still valid? 20 Question C: Has any other information come to light that could call into question the protectiveness of the remedy? 22 YIn. Issues 22 IX. Recommendations and Follow-up Actions 22 X. Protectiveness Statement 23 XI. Next Review 23

Appendices

Appendix A - Figures Figure 1 - Location Map Figure 2 - Site Map

Appendix B - Tables Table 1 - Groundwater Contaminants ofConcern and Applicable or Relevant and Appropriate Requirements Table 2 - Surface Water Contaminants ofConcern and Applicable or Relevant and Appropriate Requirements Table 3 - Soil Contaminants of Concern Table 4 - Institutional Controls Summary Table 5 - History of Monitoring Results for Inorganic Contaminants of Concern ­ Monitoring Wells MW06, MW8A, MW9A

Appendix C - Public and State Regulatory Agency Notifications Notification Letter to Minnesota Pollution Control Agency Public Notice

2 LIST OF ACRONYMS

ARARs Applicable or Relevant and Appropriate Requirements ARS Air Reserve Station CERCLA Comprehensive Environmental Response, Compensation and Liability Act CL Compliance Level COC Contaminant ofConcern EOD Explosive Ordnance Disposal FFA Federal Facility Agreement FS Feasibility Study HRL Health Risk Limit IC Institutional Control ICIAP Institutional Controls Implementation and Assurance Plan MAC Metropolitan Airports Commission MCL Maximum Contaminant Level MSP lAP Minneapolis-St. Paul International Airport MSPIAP ARS Minneapolis-St. Paul International Airport Air Reserve Station MPCA Minnesota Pollution Control Agency MW Monitoring Well NCP National Contingency Plan NGVD National Geodetic Vertical Datum -NPL National Priorities List O&M Operation and Maintenance RAL Recommended Allowable Limit ROD Record of Decision R1 Remedial Investigation SARL Small Arms Range Landfill SVOC Semi-volatile Organic Compound SWRAU Site-Wide Ready for Anticipated Use TL Trigger Level USAF Air Force USAFR Reserve USEPA United States Environmental Protection Agency UUIUE Vnlimited Use or Unrestricted Exposure VOC Volatile Organic Compound 934AW 934th Airlift Wing

3 EXECUTIVE SUMMARY

This report documents the fourth Five-Year Review for the "Twin Cities 'Air Force Reserve Base, Small Arms Range Landfill," a former National Priorities List site located on the Snelling Small Arms Range Annex property at the Minneapolis-St. Paul International Airport Air Force Reserve Station. In May 2012, Pace Analytical Services, Inc. completed confirmatory sampling and analysis of groundwater at the Small Arms Range Landfill. , Representatives of U.S. Environmental Protection Agency Region 5 Superfund Division and the U.S. Air Force Reserve's 934th Airlift Wing performed a site inspection in May 2012 to evaluate the site access restrictions and site maintenance. Based on the analytical results and the observed conditions during the site inspection, the remedial actions implemented at the Small Anns Range Landfill remain protective of human health and the environment.

FIVE-YEAR REVIEW SUMMARY FORM

SITE IDENTIFICATION .

Site Name: Twin Cities Air Force Reserve Base Small Arms Firing Range Landfill (SARL)

EPA 10: MN8570024275

NPL Status: Deleted

Multiple OUs? Has the site achieved construction completion? No Yes : REVIEW STATUS

Lead agency: Other Federal Agency If "Other Federal Agency" was selected above, enter Agency name: U.S. Air Force

Author name (Federal or State Project Manager): Douglas Yocum

Author affiliation: 934th Airlift Wing, U.S. Air Force Reserve

Review period: 07/29/2008 - 07/28/2013

Date of site inspection: OS/22/2012

Type of review: Statutory Review number: 4

Triggering action date: 07/28/2008

Due date (five years after triggering action date): 07/28/2013

4 FIVE-YEAR REVIEW SUMMARY FORM (CONTINUED)

I Issues/Recommendations ' I QU(s) without Issues/Recommendations Identified in the Five-Year Review: SARL Issues and Recommendations Identified in the Five-Year Review: Not applicable I

Sitewide Protectiveness Statement I Protectiveness Determination: Protective Protectiveness Statement: Institutional Controls (ICs) for the site property and groundwater, which are required to ensure no inappropriate use of the site or use of groundwater, are in-place and effective. The remedy is functioning as intended because no inappropriate site uses are occurring, and no groundwater use is occurring. Long term protectiveness requires compliance with effective ICs. Compliance with effective ICs will be ensured through long-term stewardship by maintaining and monitoring effective ICs as well as maintaining the site remedy components. Because the remedial actions at the SARL are protective, the site is protective of human health and the environment.

5 Fourth Five-Year Review Report

I. Introduction

The Small Anns Range Landfill (SARL) site is a two-acre site located on an Air Force-owned parcel of property known as the Snelling Small Anns Range Annex, within the "Fort Snelling Unorganized Territory" of Hennepin County, Minnesota. The property is south-southeast of the Minneapolis-St. Paul International Airport (MSP lAP), and is bordered by Fort Snelling State Park to the north; the Minnesota River to the east; Interstate 494 and the Minnesota Valley National Wildlife Refuge to the south; and Minnesota Highway 5 to the west. A location map is presented in Appendix A, Figure I. The Snelling Small Arms Range Annex property is a geographically-separated unit of the Minneapolis-St. Paul International Airport Air Reserve Station (MSP lAP ARS), fonnerly known as the "Twin Cities Air Force Reserve Base." The 934th Airlift Wing (934 AW), U.S. Air Force Reserve, has control and oversight of the Snelling Small Anns Range Annex property, including the SARL. The SARL is within the 100 year flood plain for the Minnesota River and is prone to flooding, according to data produced in 2004 by the U.S. Anny Corps of Engineers and the U.S. Geological Survey. There is no residential property located within a one mile radius of the SARL.

The SARL site was used as an unpermitted landfill/dump site for approximately nine years. The site Record of Decision (ROD) identified contaminants of concern (COCs) for groundwater, surface water, and soils at the site. Groundwater COCs included twelve metals, five volatile organic compounds (YOCs), and one semivolatile organic compound (SYOC). Surface water COCs included six metals and one YOC. Soil COCs included five metals and one YOc.

The ROD signed by the U.S. Air Force (USAF) and U.S. Environmental Protection Agency (USEPA) established Contaminant-Specific Applicable or Relevant and Appropriate Requirements (ARARs) for the site as federal drinking water Maximum Contaminant Levels (MCLs) and State of Minnesota Recommended Allowable Limits (RALs) for groundwater COCs, and Federal Ambient Water Quality Criteria for surface water COCs. COCs for groundwater, surface water and soil, as well as Contaminant-Specific ARARs, are identified in Appendix B, Tables 1, 2 and 3. There were no Contaminant-Specific ARARs established for soil COCs. Location-specific ARARs and Action-Specific ARARs were not identified in the ROD.

The selected remedy for the SARL consisted of natural attenuation of groundwater contamination, access restrictions, site maintenance and monitoring, and institutional controls.

The Purpose of the Review

The purpose of the Statutory Five-Year Review is to detennine whether the remedy selected and implemented for the SARL continues to be protective of human health and the environment. This Five-Year Review report identifies issues found during the review, if any, and provides recommendations to address them. Previous Five-Year Reviews were documented in 1998, 2003, and 2008.

6 Authority for Conducting the Five-Year Review

This statutory Five-Year Review is conducted pursuant to Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Section 121(c) (42 USC § 9621(c)) and the National Contingency Plan (NCP). CERCLA Section 121 states:

Ifthe President selects a remedial action that results in any hazardous substances, pollutants, or contaminants remaining at the site, the President shall review such remedial action no less often than each jive years after the initiation of such remedial action to assure that human health and the environment are being protected by the remedial action being implemented. In addition, if upon such review it is the judgment of the President that action is appropriate at such site in accordance with section 104 or 106, the President shall take or require such action. The President shall report to the Congress a list offacilities for which such review is required, the results ofall such reviews, and any actions taken as a result ofsuch reviews.

USEPA interpreted this requirement further in the NCP. Title 40, Code of Federal Regulations (CFR), Section 300.430(f)(4)(ii) states:

If a remedial action is selected that results in hazardous substances, pollutants, or contaminants remaining at the site above levels that allow for the unlimited use and unrestricted exposure, the lead agency shall review such action no less often than every jive years after the initiation of/he selected remedial action.

Who Conducted the Five-Year Review

The 934 AW conducted this Five-Year Review on behalf of the USAF. Groundwater sampling and laboratory analysis, and monitoring well condition evaluations, were accomplished by Pace Analytical, Inc., under contract to the 934 AW. Methods and results are documented in a May 2012 analytical and field data report. The USEPA Region 5 Remedial Project Manager, Mr. Tom Barounis, inspected site conditions at the SARL during a site visit on May 22, 2012. The Air Force Installation Restoration Program Manager, Mr. Douglas Yocum, 934 AW Environmental Flight, participated in the May 22, 2012 site visit; reviewed relevant documents; analyzed monitoring data; and prepared this statutory Five-Year Review based upon the information obtained from these sources and activities.

Other Review Characteristics

This is the fourth Five-Year Review for the SARL site. The triggering action for this review is the USEPA concurrence signature date on the latest previous Five-Year Review.

7 II. Site Chronology

Event Date Phase I Installation Restoration Program Records Search 3/3111983 National Priorities List Listing 7/22/1987 Federal Facility Agreement 1110611989 Minnesota Request for Response Action 11128/1989 Remedial Investigation/Feasibility Study complete 3/3111992 Record of Decision signature 3/3111992 Remedial Design start 4/0111992 Remedial Design complete 8/2511992 Remedial Action stm1 8/3111992 Remedial Action complete/Preliminary Close-out Report 9/2411992 Final Closeout Rep0l1 8/2911996 Deletion from National Priorities List 1211611996 First Five-Year Review 4/0211998 Deletion from Minnesota Permanent List of Priorities 6/3011998 Second Five-Year Review 7/3112003 SWRAU Completion 1129/2008 Third Five-Year Review 7128/2008

III. Background

Physical Characteristics

The SARL is located within the Mississippi Valley outwash plain of the Outwash Valley Physiographic Region. Two distinct topographic areas dominate the relief: an upland area and a bottomland (floodplain) area. The upland area is relatively flat, sloping gently eastward toward the Mississippi and Minnesota Rivers, with ground surface elevations ranging from approximately 800 to 850 feet National Geodetic Vertical Datum (NGVD). Locally, the topographic relief between the upland area and the floodplain is marked by an 80-foot escarpment in the area west of the SARL. The floodplain area ranges in elevation from approximately 690 to 730 feet NGVD. The SARL lies within the floodplain of the Minnesota River which overlies a buried bedrock valley.

The site is underlain by an unconsolidated surficial aquifer comprised of a shallow and deep aquifer. The shallow aquifer extends from the area beneath the SARL to the Minnesota River, and consists of a gravelly sand layer underlain by heterogeneous unconsolidated materials comprised of silty sand, peat, clay, silty sandy clay, and sandy clay, which generally exhibit low pern1eability. These low permeability materials combine to fonn a confining stratum that separates the underlying deep aquifer from the shallow aquifer. Depth to shallow groundwater at the site is approximately 22-25 feet below ground surface. An apparent discontinuity exists in the lateral extent of the confining layer and underlying materials to the west of the site. This discontinuity is due to the presence of the St. Peter Sandstone bedrock formation in this western

8 portion of the site. The St. Peter Sandstone has been eroded away east of the SARL, resulting in a bedrock valley that has been filled primarily by fluvial depositional processes.

Land and Resource Use

The SARL is located on an Air Force-owned parcel ofproperty known as the Fort Snelling Small Arms Range Annex, within the "Fort Snelling Unorganized Territory," in the southeast quarter of the southwest quarter of Section 32, Township 28 North, Range 23 West, Hennepin County, Minnesota. Air Force Reserve personnel assigned to the 934 AW commonly refer the Fort Snelling Small Arms Range Annex as "Area 8." This 27-acre parcel of property is south­ southeast ofMSP lAP, and is bordered to the north by Fort Snelling State Park; to the east by the Minnesota River (reach 07020012-505, River Mile 22 to mouth); to the south by Interstate 494 and the Minnesota Valley National Wildlife Refuge; and to the west by Minnesota Highway 5. The SARL is within the 100 year flood plain for the Minnesota River and is prone to flooding, according to data produced in 2004 by the U.S. Army Corps of Engineers and the U.S. Geological Survey. The Metropolitan Airports COlmnission (MAC) maintains a storm water retention basin (South Retention Basin #3, 494 Pond) on Air Force property between the SARL and the Minnesota River. The pond functions as a high flow bypass detention pond, receiving storm water flow from MAC's MSP Pond I when stonn runoff rates exceed 300 cubic feet per second.

The SARL is currently used as the "Off-Range Training Area," or "Tool Range," for the 934 AW's Explosive Ordnance Disposal (EOD) Flight. The tenn "off-range training" refers specifically to training with materials, equipment, tools, and techniques that are used to identify and isolate explosive ordnance in an emergency response situation, as well as training on procedures to prepare for the safe destruction of explosive ordnance. Off-range training consists exclusively of simulation; it does not include any detonation or destruction of actual ordnance. Use of the SARL for this purpose by the 934 AW EOD Flight began in 2011. A 2400-square foot concrete slab was placed on the surface of the landfill area, for training on use of remotely­ operated robotic equipment. A site map is presented in Appendix A, Figure 2. Future land use of the site is anticipated to remain the same as long as the property remains under Air Force ownership and control.

All underground waters of the state of Minnesota are, by state regulation, classified as Class 1 waters, i.e., domestic consumption. The Minnesota River, from River Mile 22 to mouth, is classified as Class 2C (aquatic life and recreation); 3C (industrial consumption); 4A/4B (agriculture and wildlife); 5 (aesthetic enjoyment and navigation), and 6 (other uses/protection of border waters). These use designations are not anticipated to change.

History of Contamination

The property on which the SARL is located was acquired by the USAF in 1951. The SARL site was used as the main landfill for the Air Force Reserve from approximately 1963 to 1972. General refuse and industrial wastes fonned the bulk of waste materials deposited at the SARL. The industrial wastes are believed to have included approximately 100 gallons of paint sludge,

9 800 pounds of paint filters and 100 to 200 gallons of leaded aviation gasoline sludge. Between 1963 and 1969, all refuse was burned in a pit located at the southwestern edge of the landfill. The SARL was closed in 1972, with native soil used to cover the fill area. The SARL was first identified as a possible hazardous waste site in 1983 in the Phase I Installation Restoration Program Records Search report. Preliminary studies of the site indicated the presence of low concentrations of groundwater contaminants, which were possibly migrating from the SARL. Based upon these preliminary studies, the site was placed on the National Priorities List (NPL) in 1987. A remedial investigation (RI) was conducted in 1988 and 1989 to further characterize the site and obtain the data necessary for an evaluation of remedial alternatives. The RI determined that depth of the landfill at the site is approximately 10 to 12 feet below ground surface, and indicated that low levels of inorganic contaminants had been released from the SARL to the soil and groundwater.

A Federal Facility Agreement (FFA) signed by the USAF and USEPA in 1989 established the procedural framework for remedial action at the site. A feasibility study (FS) was completed in 1991 and a ROD selecting the FS preferred alternative of natural attenuation of groundwater contaminants in conjunction with access restrictions, site maintenance and monitoring, was signed by the USAF and USEPA in 1992. The Minnesota Pollution Control Agency (MPCA) concurred with the ROD.

The ROD stipulated that, at a mmnnum, monitoring of site groundwater and surface water quality would take place every two months for a minimum two-year period. The ROD also stated that the monitoring program could be modified, or an alternative remedial action enacted, to reflect the first year sampling results. After completing the second year of sampling, the analytical data were to be reviewed to detennine requirements for future sampling work.

Initial Response

Neither USAF nor USEPA perfonned removal actions or other initial remedial measures at the site.

Basis for Taking Action

As previously noted, the RI indicated that low levels of inorganic contaminants (metals in particular) had been released from the SARL to the soil and groundwater. Based on the results of the RI, ARARs were established in the ROD for groundwater COCs and surface water COCs. COCs for groundwater included twelve metals, five volatile organic compounds, and one semi­ volatile organic compound. COCs for surface water included six metals and one volatile organic compound. There were no ARARs established for soil COCs. The COCs identified in the ROD are listed in Appendix B, Tables 1,2 and 3.

The purpose of the remedy selected in the ROD was to prevent risk to human health and the environment through direct contact with landfill contaminants and to prevent risk from exposure to contaminants in the groundwater. .

10 IV. Remedial Actions

Remedy Selection

The Remedial Action selected for the SARL was natural attenuation of groundwater contaminants in conjunction with access restrictions, site maintenance and monitoring. The remedial action objectives were to prevent risk to humans or the environment through contact with landfill contaminants and to prevent risk to humans or enviromnental receptors from contaminants in groundwater.

The selected remedy established cleanup levels for the COCs in groundwater based upon the Safe Drinking Water Act MCLs and State of Minnesota RALs for drinking water contaminants. State of Minnesota RALs have been superseded by Minnesota Health Risk Limits (HRLs). The selected remedy was also intended to ensure groundwater recharge from the landfill through the stonnwater pond or directly to the Minnesota River does not exceed federal or state Water Quality Criteria for freshwater species or potential drinking water sources.

The ROD also established "trigger levels" (TLs) to be used to evaluate the need for additional action for specific contaminants that were at or above compliance levels (Le., ARARs) prior to the ROD. The trigger levels were set at twice the value of the ARAR for seven metals (arsenic, beryllium, cadmium, lead, nickel, selenium, and vanadium) and one VOC (trichloroethene). TLs were not established for surface water.

Remedy Implementation

Site access restrictions specified in the ROD and installed in 1992 included access control, fencing with locked gates around the entire site, and warning signs.

The first year of monitoring was completed in 1993 with the results presented in the Final 1993 Annual Water Quality Report, which concluded that natural attenuation was serving as an effective remedial action at the SARL. It also concluded that the decreasing concentrations of VOCs, SVOCs and metals justified a modification of the monitoring program. USEPA and MPCA approved the following modifications in 1994:

• Monitoring MW3R and MW05 for water level only; • Designating MW06 as the background well for the SARL; • Reducing the sampling frequency from bi-monthly to quarterly; and • Reducing the analyte list by eliminating five indicator parameters (calcium, magnesium, potassium, sodium and total dissolved solids.

The second year of monitoring was completed in 1994 with the results presented in the Final 1994 Annual Monitoring Report. Conclusions in this report were consistent with the prior year's report. After reviewing groundwater monitoring and historical contaminant trends, the USAF concluded that the selected remedy had effectively achieved remedial action objectives and requested that USEPA initiate procedures to remove the SARL from the NPL.

11 Three additional rounds of groundwater monitoring were conducted in 1995. All monitoring results were consistent with the 1993 and 1994 annual monitoring results. The recommendations of the 1995 Annual Monitoring Report were consistent with those presented in the 1994 Annual Monitoring Report. The SARL was deleted from the NPL in 1996.

In 1997 confinnatory monitoring was completed as part of the first Five-Year Review. Monitoring results presented in the 1997 Five-Year Review Report indicated that concentrations of COCs in groundwater continued to decrease and that surface water concentrations continued to fall below detection limits. The 1997 Five-Year Review Report concluded that all contaminant concentrations in groundwater were in compliance with ARARs, except for one side-gradient well in which selenium was detected at a concentration of 11.7 ppb. This exceeded the Minnesota Department of Health RAL (10.0 ppb). However, it did not exceed the Minnesota HRL value of 30 ppb, which was promulgated in 1995 and superseded the RAL. The first Five­ Year Review recommended that groundwater and surface water monitoring be discontinued until the next Five-Year Review. USEPA subsequently concurred with abandonment and sealing of five of the site monitoring wells (MWO 1, MW02, MW3R, MW04, MW05).

In 2002 confinuatory monitoring was completed as part of the second Five-Year Review. The monitoring results showed that beryllium and nickel were the only inorganic COCs detected at concentrations above an ARAR during 2002. The beryllium concentrations did not exceed the CL established in the ROD, and all of the detected beryllium concentrations were qualified as blank contaminated. Nickel concentrations detected in two wells (73 ppb at MW06 and 300 ppb at MW8A) exceeded the 70 ppb CL established in the ROD. All surface water analyte concentrations were less than the ARARs, with the exception of beryllium in both surface water samples. These beryllium results were also qualified as blank contaminated. The second Five­ Year Review Report concluded that the 2002 sampling results confinued the results of the previous monitoring program, which established that natural attenuation had proven to be an effective remedial agent at the SARL.

In 2007 confinnatory monitoring was completed as part of the third Five-Year Review. The monitoring results showed that all ARARs and CLs had been met for surface water sampled from the retention pond adjacent to the SARL, as well as for groundwater sampled from monitoring wells MW06, MW7A, MW7B, MW8B, and MW9B. The results from shal.low aquifer well MW8A showed nickel above the CL, and the results from shallow aquifer well MW9A showed arsenic above the CL. Both parameters were also detected at lower concentrations in samples from background well MW06. The third Five-Year Review Report included recommendations for discontinuation of surface water sampling of the retention pond adjacent to the SARL; discontinuation of groundwater monitoring of shallow well MW7A and deep wells MW7B, MW8B, and MW9B; abandonment and sealing of these wells; and reducing the scope of future groundwater monitoring of background well MW06 and shallow wells MW8A and MW9A by eliminating VOC and SVOC parameters, and including only inorganic parameters. The third Five-Year Review Report concluded that the 2007 sampling results confinued the results of the original monitoring program and previous five-year reviews, and that natural attenuation remained an effective remedial agent at the SARL. USEPA concurred.

12 Institutional Controls

ICs are non-engineered instruments, such as administrative and/or legal controls, that help minimize the potential for exposure to contamination and protect the integrity of the remedy. Compliance with ICs is required to assure long-term protectiveness for any areas which do not allow for unlimited use or unrestricted exposure (UUIVE). The entire site consists of a landfill covered with soil as part of the final remedy. The cleanup goals for the landfill were based on limited commercial or industrial use (containment) and restrictions on groundwater use at the site. Therefore, the entire site does not support UUIVE. Institutional controls for the restricted area are summarized in Appendix B, Table 4.

ROD Requirements: The 1992 ROD selected Alternative 4, which' included the need for site access restrictions and ICs. The ROD for the site required that the necessary deed restrictions required by CERCLA, Section 120 (h)(3) would be implemented if and when the property is placed under the ownership of a person or other entity of federal government because a deed does not currently exist for the property. The ROD also stated the following:

"Other restrictions to be imposed will be institutional, such as deed restrictions limitingfuture development ofthis site,_ijthe property is relinquished by the USAF, and deed restrictions limiting future groundwater usage. These deed restrictions will be imposed in the eventuality that USAF releases the property once a deed is prepared. Additionally, all requirements ofSection 120 ofCERCLA for notification and deed notation will be met. These requirements are imposed on f<;deral facilities relinquishing property on which hazardous substances were storedfor more than 1 year or where they were disposed of or released. Included in the requirements is provision ofa description ofhazardous substances stored, disposed of, or released, the general time frame of the activity, and the type and quantity of materials and any remedial action taken. The Air Force must also warrant in the deed notation that remedial action necessary to protect public health and the environment has been taken and any additional remedial action found to be necessary in the future will be conducted by the federal government."

Site Ownership and ICs: The property on which the SARL is located has been under continuous federal government ownership since acquisition by the U.S. Army in 1905, and currently remains in federal government ownership with administration and control under the USAF. No deed exists for the property. To ensure that the ICs prescribed for the SARL remain known to future USAF personnel and are considered in any land use planning or real property disposal decisions concerning the SARL, copies of the ROD and 1989 FFA between the USAF and USEPA have been incorporated in the installation's Real Property file for the tract of property containing the SARL. The requirement to implement deed restrictions, limiting future development and groundwater usage if the property is ever placed under the ownership of a person or other entity of federal government, is also annotated within the USAF "Automated Civil Engineer System­ Real Property" database record for the property. Additionally, documentation of the ROD requirement for a deed restriction is included in the Minneapolis-St. Paul Air Reserve Station General Plan. The General Plan is a document prepared as a guide for the station's long-range

13 development, which provides USAF decision-makers with a concise assessment of on-station conditions; recommendations for improvements and future development of the station as a whole; and identification of constraints on development and land use. It is not a land use plan solely for the SARL site, nor is it an operational plan. In addition to documenting the requirement for a deed restriction limiting future development and groundwater usage if the property is ever transfelTed to another owner, the General Plan also documents the need for access restriction and fence at the SARL site as a constraint to future land use and development.

Transfer of MSP lAP ARS property, from federal ownership and USAF control to state ownership and control, has been proposed by the USAF as part of the "Air Force Strategy and Force Structure Overview," announced in March 2012 to comply with the president's defense strategy and the 2011 Budget Control Act's requirements to cut $487 billion from the defense budget over 10 years. These USAF proposals are cUlTently undergoing congressional review. If the USAF Force Structure changes are congressionally approved and implemented as proposed, transfer of MSP lAP ARS property could possibly occur as early as Fiscal Year 2014. Detailed property transfer plans have not yet been developed by the USAF.

Current Compliance: Access controls, in the fonn of fencing and warning signs, are in place at the SARL. These controls, along with regular site patrol by USAF security personnel, are effective measures to limit public access to the SARL. There are no drinking water wells installed within the groundwater restricted area, nor are there any site uses which are inconsistent with management of the site in a manner that restricts access to the fornler landfill area. The access restrictions and ICs are functioning as intended.

Long Tenn Stewardship: Long ternl protectiveness at the site requires compliance with land and groundwater use restrictions. Compliance with effective ICs will be ensured through long-tenn stewardship by maintaining and monitoring effective lCs as well as maintaining the site remedy components. The requirement for continued periodic inspections and site maintenance was generally stated in the Superfund Final Closeout Report, Twin Cities Air Force Reserve Base Small Anns Landfill, NPL #054L, Section V, USEPA, August 29, 1996. The frequency of "periodic" inspections was not specified. The USAF will continue to conduct site maintenance activities, and document an annual evaluation of site conditions for the SARL, as long as the property remains in federal ownership and under USAF control. USAF will notify USEPA if any situation or activity is discovered that is inconsistent with the IC objectives or use restrictions, or that would interfere with the land use controls. Also, the USAF will notify USEPA and MPCA ofany anticipated changes in land use.

Site Reuse Assessment: In 2010, as part of its "Superfund Redevelopment Initiative," USEPA Region 5 contracted E2 Inc. to conduct a "reuse assessment that engages site owners and other stakeholders in evaluating future use options for a site," in order to "help facilitate site stewardship and support the long-term effectiveness ofremedy." A final report issued by P Inc. in June 2010 documented that the Minnesota Department of Natural Resources maintains long­ standing interest in establishing a public access trail in the vicinity of the SARL, to connect with trail networks to the north and south. The report also documented that USAF, together with MAC and the Minnesota Department of Transportation which both have access easements for use of property adjacent to the SARL, have public safety concerns and secUlity concerns about

14 trail networks to the north and south. The report also documented that USAF, together with MAC and the Minnesota Department of Transportation which both have access easements for use of property adjacent to the SARL, have public safety concerns and security concerns about such a trail. The report concluded that if site stakeholders eventually determine that a public access trail alignment through the SARL site is preferable to other trail alignment alternatives, the current institutional controls for the SARL would need to be revised to allow for such reuse, and that USEPA Region 5 would be willing to determine what may be required to adapt the legal restrictions for the site while protecting the remedial components ofthe site.

ICs are In-Place and Effective: IC evaluation activities conducted by the USAF have determined that the ICs are in-pl<:tce anq effective. All non-UUIVE areas are addressed effectively by rcs as determined by IC evaluation activities. The objective(s) of the ICs (e.g. prohibit interference with the landfill soil cap, prohibit residential use, and restrict groundwater use at the site) are being met. A mechanism and party responsible for inspecting and monitoring compliance with land use restrictions and, groundwater restrictions exists at the site.

System Operations/Operation and Maintenance (O&M)

The remedy for the SARL does not include any operating systems other than access controls, and monitoring wells used during five-year reviews. O&M for the SARL site consists of: a) annual site inspection to assess the integrity of the fence and the cover above the landfill materials, and identify need for repairs; and b) maintenance of the monitoring wells. v. Progress Since the Last Review

Status of Recommendations and Follo~-up Actions from Last Review

The last Five-Year Review, completed in 2008, did not identify any issues that prevented the selected remedy from being determined protective at that time. Recommendations stated in the last Five-Year Review included sediment removal and redevelopment of monitoring well MW06; and abandonment/sealing of wells MW7A, MW7B, MW8B, and MW9B. These actions were completed in September 2008. The last Five-Year Review also recommended that the next Five-Year Review should include confirmatory water quality monitoring ofonly inorganic COCs at background well MW06 and shallow wells MW8A and MW9A, and that surface water sampling of the retention pond adjacent to the SARL should be discontinued due to the consistent, long-term attainment of ARARs for the surface water COCs. These recommendations have been implemented.

Status of Other Prior Issues

Access· restrictions enacted as part of the remedial action have been maintained. A site maintenance program has been used to ensure that the integrity of the existing soil cover, fence and monitoring system are maintained.

15 VI. Five-Year Review Process

Administrative Components

Community and state regulatory agency notification of five-year review initiation was accomplished during June 2012..

The Five-Year Review team consisted ofDouglas Yocum, 934 AW Environmental Flight, USAF, and Tom Barounis, USEPA Region 5 Remedial Project Manager.

Review components included: Community Notification and Involvement; Document Review; Data Review; Site Inspection; and Five-Year Review Report Development and Review.

The schedule extended from May 2012 through December 2012.

Community Notification and Involvement

Via letter dated June 14,2012, MPCA was notified of the Five-Year Review and was offered the opportunity to participate. MPCA made no telephonic, email or written response to the notification letter. A copy of the notification letter is provided in Appendix C.

A public notice was placed in the Minneapolis Star-Tribune, the primary local newspaper serving Hennepin County, on June 17,2012, announcing the preparation of this Five-Year Review. The public notice identified the 934 AW point of contact for more infonnation about the review process; provided an opportunity to request inclusion on a distribution list to receive a copy of the draft version of this report; and invited public participation through reviewing and commenting on the draft report. No telephonic, email or written inquiries or responses of any kind were received from the public. A copy of the public notice is provided in Appendix C.

Document Review

The fol1owing documents were reviewed in preparing this Five-Year Review Report:

Federal FacilWes Agreement Under CERCLA Section 120, Small Arms Range Landfill; Minneapolis-St. Paul International Airport Base; November 6, 1989

Record ofDecision, Small Arms Range Landfill, Minneapolis-St. Paul International Airport; Air Force Reserve; March 31, 1992

Superfund Final Close-Out Report, Twin Cities Air Force Reserve Base, Small Arms Range

16 Landfill. NPL #054L; Minneapolis-St. Paul International Airport, Minnesota, USEPA; August 29, 1996

Comprehensive Five-Year Review Guidance; USEPA, Office of Emergency and Remedial Response, EPA 540-R-01-007, OSWER No. 9355.7-03B-P; June 2001

Third Five-Year Review Report fOr Twin Cities Air Force Reserve Base. Small Arms Range Landfill. Minneapolis. Minnesota; 934th Airlift Wing, U.S. Air Force Reserve, Minneapolis­ St. Paul International Airport Air Reserve Station, Minnesota; July 28, 2008

Situation Assessment. Twin Cities Air Force Reserve Base Small Arms Range Landfill; USEPA Region 5, Chicago, Illinois; June 2010

Recommended Evaluation ofInstitutional Controls: Supplement to the "Comprehensive Five-Year Review Guidance "; USEPA, OSWER Directive 9355.7-18; September 13,2011

Data Review

Groundwater sampling was conducted at the three remaining monitoring wells (MW06, MW8A, MW9A) during May 2012. Condition of each of the three wells was evaluated in conjunction with this monitoring event. All well casings and surface seals were visually observed to be in good condition. Groundwater samples were analyzed for the twelve groundwater inorganic COCs. Results are presented below, followed by a briefdiscussion ofresults from each well.

ARAR MW06 MW8A MW9A Inorganic COC (ggLIJ. Result (ug/L) Result (ug/L) Result (ug/L) Arsenic 10 2.2 Not detected 4.9 Beryllium 4 Not detected Not detected Not detected Cadmium 0.08 Not detected Not detected Not detected Chromium 100 2.4 2.7 1.2 Copper 1300 Not detected 1.6 Not detected Lead 15 Not detected Not detected Not detected Mercury 2 Not detected Not detected Not detected Nickel 100 10.9 113 Not detected Selenium 30 Not detected 7.2 Not detected Silver 30 Not detected Not detected Not detected Vanadium 50 0.1 0.56 0.2 Zinc 2000 Not detected Not detected Not detected

Monitoring Well MW06: MW06 is a side-gradient well that was identified as the background monitoring well in 1994. The 2012 results do not indicate any trend of contaminant increase. Four of twelve COCs were detected during the 2012 monitoring event, all below the applicable ARARs, which is consistent with results in the previous Five-Year Reviews.

17 Monitoring Well MW8A: MW8A is a down-gradient shallow aquifer well. The 2012 results do not indicate any trend of contaminant increase. Five of twelve COCs were detected during the 2012 monitoring event. Only one COC was detected above its applicable ARAR. Nickel was detected at a concentration of 113 Ilg/L, slightly above the current ARAR of 100 Ilg/L but well below the current Trigger Level of 200 Ilg/L. The detected concentration was lower than concentrations detected in the previous two Five-Year Reviews.

Monitoring Well MW9A: MW9A is a down-gradient shallow aquifer well. The 2012 results do not indicate any trend of contaminant increase. Three of twelve COCs were detected during the 2012 monitoring event, all below the applicable ARARs, which is consistent with results in the previous Five-Year Reviews.

Histories of monitoring results for inorganic COCs at these three wells are presented in Appendix 2, Table 5.

Site Inspection

The SARL was inspected by Tom Barounis, USEPA Region 5 Superfund Division, and Douglas Yocum, 934 AW Environmental Flight, USAF, on May 22, 2012. Site conditions observed during the 2012 inspection verified that the soil cover and fencing around the site have been adequately maintained. Well casings and surface seals were visually observed to be in good condition.

VII. Technical Assessment

Question A: Is the remedy functioning as intended by the decision documents?

Yes. The remedy is functioning as intended with regard to ICs. The soil cover over the former waste areas remains intact, and access to the site continues to be restricted. The site remains under the control of the USAF, and the USAF has documented the requirement for deed restrictions in the event of property transfer to another owner.

Remedial Action Performance

Remedial actions continue to function as designed. Natural attenuation of groundwater contaminants is generally perfonning as expected, and previously achieved cleanup levels are predominantly being maintained. Site access restrictions are in place and are being maintained. In summary, data gathered during this five-year review indicates that, overall, the remedy continues to function as designed and is perfom1ing as expected.

System Operation and Maintenance

The remedy for the SARL does not include any operating systems other than access controls, and

18 monitoring wells used during five-year reviews. O&M for the SARL site consists of: a) annual site inspection to assess the integrity of the fence and the cover above the landfill materials, and identify need for repairs; and b) maintenance of the monitoring wells.

The site inspection conducted during 2012 concluded that integrity has been adequately maintained for both the soil covering the site and the fence surrounding the site. Future site inspections will continue to be used to ensure the effectiveness of the maintenance and access restrictions required by the remedy.

Condition of each of the three monitoring wells was evaluated in conjunction with- the 2012 monitoring event. Well casings and surface seals were visually observed to be in good condition, and no maintenance actions were recommended.

Opportunities for Optimization

Based on the data review perfonned during this Five-Year Review, an opportunity exists to reduce the periodic cost of monitoring activities, with no detrimental impact to the site remedy. Groundwater sampling and analysis at the site could be discontinued, and the three remaining monitoring wells (MW06, MW8A, and MW9A) could be abandoned and sealed in accordance with state code. The rationale for abandonment and sealing of these wells is the consistent, long­ tenn attainment of ARARs for groundwater inorganic COCs at the site. A single COC parameter (nickel) was detected at a concentration slightly exceeding the ARAR at one well (MW8A) during this review. The detected concentration of nickel was significantly decreased from results at well MW8A during the two previous Five-Year Reviews. The data does not indicate that consideration of additional remedial actions for the site is warranted, and there appears to be no benefit to be gained from continuing groundwater monitoring in future Five-Year Reviews.

Early Indicators of Potential Issues

Since there are no operating systems at the site, the only early indicators of potential issues would be obvious maintenance issues such as damage to the landfill fence or soil cover, or upward trends in ground water contaminant concentrations. The soil cover and fence condition remain acceptable. Ground water data during this Five-Year Review did not demonstrate any increasing concentration contaminants, so there are currently no indicators of potential issues.

Implementation of Institutional Controls and Other Measures

Access controls, in the fonn of fencing and warning signs, remain in place at the site. IC evaluation activities conducted by the USAF have detennined that the ICs are in-place and effective. All non-UU/UE areas are addressed effectively by ICs as detennined by IC evaluation activities. The objective(s) of the ICs (e.g. prohibit interference with the landfill soil cap, prohibit residential use, and restrict groundwater use at the site) are being met. A mechanism and party responsible for inspecting and monitoring compliance with land use restrictions and groundwater restrictions exists at the site. These controls, along with the continued USAF control of the property on which the SARL is located and regularly scheduled inspections of the site, are effective measures to limit access to the site and to maintain the integrity of the remedy.

19 Question B: Are the exposure assumptions, toxicity data, cleanup levels, and remedial action objectives used at the time of the remedy still valid?

No. Although the exposure assumptions and remedial action objectives used at the time of the remedy remain valid, cleanup levels have changed.

Changes in Standards and To Be Considered Criteria

Minnesota RALs specified in the ROD have been replaced by promulgated HRLs. The HRLs for nickel, selenium, silver, vanadium and zinc are all higher than corresponding RALs in effect at the time of the ROD in 1992. There is no HRL for arsenic, copper, lead, or mercury. Federal drinking water MCLs have been reduced for arsenic (from 50 Ilg/L to 10 Ilg/L) and beryllium (from 5 Ilg/L to 4 Ilg/L). Although the Federal MCL for beryllium was lowered, the 1992 ROD set the then-current RAL of 0.08 Ilg/L as the cleanup level for beryllium. The net effect of these changes is that the current ARARs for groundwater inorganic COCs for the site are all equal or greater than the ARARs established in 1992. To Be Considered Criteria were not identified in the ROD for the SARL.

Changes in Exposure Pathways

The 1992 ROD documented that a baseline risk assessment indicated that air, soil, groundwater, and surface pathways were not complete because of the lack of release of volatile organic compounds, lack of surficial soil contamination, the location of the site within a semi-restricted area, limited access to the stonn water pond, no significant surface water contamination, and no current users of groundwater at the site or down-gradient of the site. As part of the selected remedy, a fence was constructed around the site in 1992 to limit access to the landfill and stonn water pond. There have been no changes in the potential exposure pathways at the site since the implementation of the remedy for the site. The site remains restricted from public access, with fencing and locked gates in place. In 2011, the 934 AW EOD Flight began use of the SARL area for "Off-Range Training." The training operations do not involve any excavation below the soil cover. A 2400-square foot concrete slab in place on the surface of the landfill area further diminishes any potential for contact with landfill components.

Changes in Toxicity and Other Contaminant Characteristics

Based on a review of toxicity data in the USEPA Integrated Risk Infonnation System as of June 2012, toxicity factors for the contaminants of concern have not changed in any way that could affect the protectiveness of the remedy. There was no data indicating that there have been any changes in the understanding or knowledge of other contaminant physical or chemical characteristics (e.g., sorption characteristics, ability to bioaccumulate, bioavailability).

Changes in Risk Assessment Methods

Standardized risk assessment methods have not changed 10 a way that could affect the protectiveness of the remedy.

20 Expected Progress toward Meeting Remedial Action Objectives

Two remedial action objectives were established in the ROD: 1) Prevent risk to humans or the environment through direct contact with landfill contaminants, and 2) prevent risk to humans or environmental receptors from contaminants in groundwater. The selected remedy addressed these objectives by limiting contact with landfill contaminants through access restrictions and deed restrictions; and reducing risks from groundwater contaminants through natural attenuation and deed restrictions.

Achievement of the first objective was documented in the August 1996 Superfund Final Closeout Report for the site. Fencing and warning signs installed at the site remain in place. Regularly scheduled inspections of the site are conducted to confirm the adequacy of the fence condition, and to ensure that landfill components do not become exposed from erosive action by wind or surface runoff. To date, erosion of the soil cover has not been observed on the SARL site, and landfill components have not become exposed.

Achievement of the second objective was also documented in the August 1996 Superfund Final Closeout Report for the site. This determination was based on the results of groundwater and surface water monitoring conducted over a two year monitoring period. Subsequent monitoring conducted in 1997, 2002, and 2007 for the three prior Five-Year reviews confmned that natural attenuation had been an effective remedial agent. During monitoring conducted in 2012 for use in this Five-Year Review, groundwater contaminant results continued to be lower than the groundwater ARARs, with one exception: nickel at down-gradient shallow aquifer monitoring well MW8A. Sporadic results above the original ARARs for various COCs have been documented over the twenty years of site monitoring since the ROD, including a result for nickel at background well MW06 during the 2002 monitoring event. There are no potable water wells using shallow groundwater on-site or down-gradient of the site, and no other complete pathways of human exposure for the SARL. Vertical and horizontal gradients of groundwater have previously been used to demonstrate that groundwater at the SARL site discharges to the Minnesota River. As noted in the ROD, groundwater seepage to the river is unlikely to contribute detectable contamination due to the low concentration of compounds detected in groundwater and attenuation of any concentrations released to the river due to mixing, natural degradation, and dispersion processes. Therefore, a single result exceeding an ARAR at one well in 2012 does not represent failure of the selected remedy to prevent risk to humans or environmental receptors from contaminants in groundwater.

Regarding deed restrictions, the ROD specified that the deed restrictions required by CERCLA Section 120 (h)(3) must be implemented if the property is placed under the ownership of a person or other entity of federal government, because a deed does not currently exist for the property. The property currently remains under federal government ownership, with administration and control by the USAF. Documentation of the requirement for deed restrictions has been incorporated into USAF Real Property records and management systems, and deed restrictions would be implemented in the event of future release or transfer of the property out of USAF control. Additionally, in the event that the Minnesota Department of Natural Resources formally requests a Real Property instrument (i.e., lease, license, or permit) allowing development and maintenance of a public access trail in the vicinity ofthe SARL, the USAF will

21 document full disclosure of the condition of the land within the Real Property instrument with the State ofMinnesota.

Considering the access restrictions that continue to remain in place, site maintenance, monitored results of ongoing natural attenuation, and documented requirements for future deed restrictions in the event of property transfer, the remedy for the site continues to perfonn as expected. Recalculation or re-assessment of risks is not currently necessary.

Question C: Has any other information come to light that could call into question the protectiveness of the remedy?

No. No new infonnation has come to light that could call into question the protectiveness of the remedy. There are no newly identified human health risks or ecological risks associated with the SARL. The SARL has not been inundated by flood waters since the previous five-year review. Although significant flooding of the Minnesota River occurred in both March 2010 and March 2011, the SARL was above the flood crest during both events. There have been no impacts from any other natural disasters. No other infonnation has been identified that could affect the protectiveness of the remedy for the site.

VIII. Issues

The last Five-Year Review Report for the SARL, completed in 2008, concluded that the selected remedial action, consisting of natural attenuation of groundwater contamination, physical access restrictions, site maintenance and monitoring, had achieved the remediation goals set forth in the 1992 ROD. Since the last five-year review, no issues have arisen which currently prevent the remedy from being protective, and there are no current contamination issues at the site. Analytical results from samples collected since 1988 indicate that groundwater monitoring is no longer necessary at the site. At MW06, 2012 results for inorganic COCs were either not detectable or were detected at concentrations below the applicable ARARs, which was consistent with results during the previous Five-Year Reviews. At MW8A, only one inorganic COC (nickel) was detected above its applicable ARAR in 2012. The detected concentration was lower than concentrations detected in the previous two Five-Year Reviews. At MW9A, 2012 results for inorganic COCs were either not detectable or were detected at concentrations below the applicable ARARs, which was consistent with results during the previous Five-Year Reviews.

IX. Recommendations and Follow-up Actions

Remediation goals identified in the ROD were 1) institute measures to mitigate the potential for landfill components to be exposed directly to potential human receptors or local fauna from erosional action by wind or surface runoff; and 2) reduce the levels of contaminants in the groundwater to below MCLs and ensure groundwater recharge from the landfill through the stonnwater pond or directly to the Minnesota River does not exceed federal or state Water

22 Quality Criteria for freshwater species or potential drinking water sources. The USAF has maintained, and will continue to maintain the established site maintenance program and site access restrictions. As a result, the remediation goal of mitigating the potential for landfill components to be exposed directly to potential human receptors or local fauna has been met. The 2012 groundwater monitoring results confinned the results of groundwater monitoring conducted from 1993 through 2007, which established that natural attenuation had proven to be an effective remedial agent at the SARL. The next Five-Year Review should include confinnation of site access restrictions and site maintenance.

X. Protectiveness Statement

ICs for the site property and groundwater, which are required to ensure no inappropriate use of the site or use of groundwater, are in-place and effective. The remedy is functioning as intended because no inappropriate site uses are occurring, and no groundwater use is occurring. Long tenn protectiveness requires compliance with effective ICs. Compliance with effective ICs will be ensured through long-tenn stewardship by maintaining and monitoring effective ICs as well as maintaining the site remedy components. Because the remedial actions at the SARL are protective, the site is protective ofhuman health and the environment.

XI. Next Review

Evaluation of access restrictions and site maintenance for the next five-year review for the SARL is expected to be perfonned no later than 2017, with the fifth Five-Year Review Report due five years from the date of signature on this fourth Five-Year Review Report.

23 APPENDIX A - FIGURES FIGURE 1- LOCATION MAP Composite from U.S. SMALL ARMS RANGE LANDFILL Geological Survey 7.5 Minutes Series, s Snelling Small Arms Range Annex St. Paul West and St. Paul SW Quadrangles Minneapolis-St. Paul International Airport Air Reserve Station Hennepin County, Minnesota U.S. Interstate H" h Ig WaY494

FIGURE 2 - SITE MAP LEGEND • Monitoring Well SMALL ARMS RANGE LANDFILL - X - Security Fence Snelling Small Arms Range Annex s _ Locked Gate Minneapolis-St. Paul International Airport Air Reserve Station Hennepin County, Minnesota APPENDIX B - TABLES Table 1. Groundwater Contaminants ofConcern and Applicable or Relevant and Appropriate Requirements Twin Cities Air Force Reserve Base Small Arms Range Landfill 1992 ARARs 2012 ARARs 1 2 3 4 Contaminants RAL Cllg/L) MCL CllglL) HRL Cllg/L) MCL Cllg/L) Inorganics Arsenic 0.2 50 - 10 Beryllium 0.08 5 0.08 4 Cadmium 4 5 4 5 Chromium 100 100 100 100 Copper) 1000 1300 - 1300 Lead) 20 15 - 15 Mercury 1 2 - 2 Nickel 70 - 100 - Selenium 10 50 30 50 Silver 10 - 30 - Vanadium 20 - 50 - Zinc 700 - 2000 - Volatile Organics Benzene 10 5 N/A N/A 2-butanone (MEK) 300 - N/A N/A 1,2-dichloroethene (total) 70 70 N/A N/A Toluene 1000 1000 N/A N/A Trichloroethene 30 5 N/A N/A Semi-Volatile Organics Di-n-butylphthalate 700 - N/A N/A

I Minnesota RAL (as of 1992) 2 USEPAMCL (as of 1992) 3 Minnesota HRL (as of2012) 4 USEPA MCL (as of2012) 5 Copper and Lead MCLs are "treatment technique action levels" - = No requirement established N/A = Not applicable; no longer monitored at site Table 2. Surface Water Contaminants of Concern and Applicable or Relevant and Appropriate Requirements Twin Cities Air Force Reserve Base Small Anns Range Landfill 1992 ARARs Federal Water Quality Criteria Freshwater Acute Concentration' Minnesota Water Standards2 Contaminants (Ilg/L) (/.lg/L) Inorganics Beryllium - - Iron - 300 Lead 82 50 Silver 4.1 50 Vanadium - - Zinc 700 2000 Volatile Organics Toluene - -

I ARARs Q's and A's; Compliance with Federal Water Quality Criteria. USEPA Office of Solid Waste and Emergency Response. June, 1990. (cited in 1992 ROD) 2 Minnesota Water Standards, "Specific Standards ofQuality and Purityfor Designated Classes ofWaters ofthe State." Minnesota Rules 7050:220, November 1990.(cited in 1992 ROD) - = No requirement established

ARARs for'20 12 are not listed, since surface water monitoring for the site has been discontinued.

Table 3. Soil Contaminants of Concern Twin Cities Air Force Reserve Base Small Anus Range Landfill Inorganic Contaminants: Volatile Organic Contaminants: Antimony 2-butanone (MEK) Arsenic Magnesium Nickel Selenium Note: ARARs for soil contaminants were not established in the 1992 ROD Table 4. Institutional Controls Summary Media, Remedy Components & Areas that do not Support UU/UE Title of Institutional Control Based on Current Conditions Objectives of IC Instrument Implemented Small Arms Range Landfill Prohibit interference - Federal Government ownership Property - approximately two-acre with landfill cap and and control; soil cover other remedial - Restrictions documented in components, and USAF installation General Plan; prohibit residential - ROD and FFA incorporated into uses. USAF Real Property file and management systems, documenting deed restriction requirement upon transfer of land Groundwater under Small Anus Prohibit groundwater - Federal Government ownership Range Landfill Property - current usage and control; area that exceeds groundwater - Restrictions documented in cleanup standards. USAF installation General Plan; - ROD and FFA incorporated into USAF Real Property file and management systems, documenting deed restriction requirement upon transfer of land Table S. History of Monitoring Resull. for Inorganic Contami..... ofConccm- MOnitoring Wells MW06, MW8A. MW9A 1no'pnic 2012 Trigger Contaminants ARAR Lev,1 ""'-88 Oct-89 Feb-9] Jun-9] Au ·93 0<\·.3 Doc-.3 Feb-94 AM.9< Jul-94 0<\.9< Jan·9S Aor-9S 1ul-95 Mo,,'7 Mav-G2 JUlI-01 May·ll egwell~~ 20 NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO S.Rt 2.2 o.~ 0.16 NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO 0.248 NO NO 8 NO 23 NO NO NO NO NO NO NO NO NO NO NO NO 3.6BR NO NO NO Chmmium 100 NO NO •.. •.3 NO 21.4 7.• 8.IJ NO '7 •.0 NO 3. 16.9 NO 3.68 NO 2.' C 1300 NO NO 3.8 3 NO 9.4 J .3 2.8 NO NO NO NO NO NO NO 2.28 1,1 L NO 1.<'" 'S 30 NO NO NO NO NO NO NO NO NO NO NO NO NO NO NDUJ NO NO NO M"""", 2 NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO ND NO Nickel '00 200 22.7 NO .3 NO NO 8.3 12.9 NO NO NO NO NO 27 NO NO 73 33.2L 10.9 Selenium 30 60 NO NO NO NO ],8J NO 1.41 NO NO NO NO NO NO ... NO NDUJ NOS NO Silver 30 NO NO NO NO NO NO NO NO .0 NO NO NO NO NO NO NO NO NO Vanadium SO '00 NO ND NO NO NO NO 3.' NO NO 2J NO NO • NO NO NO O.68L 0.' Zinc 2000 18.8 NO J3,9 12.1 2.7 '.7 73 NO NO NO NO NO NO NO 11.8 BJ :-JD NO NO Monitoring Well MW8A '0 20 NO '0 1.2 NO I.' 2.0 NO NO NO NO NO 3.0 NO NO NO 7.0 l NO 0.08 0.16 NO NO NO NO NO NO NO" NO NO NO NO NO NO NO NO 0.309 NO NO • 8 NO '.7 NO NO NO NO NO •.2 NO 1.0J NO 1.4 J O.SJ O.ISJ 24.8 R NO NO NO '00 NO NO 20.0 8.' 11.1 4.9J 15.8 50.6 36.1 NO 1.7 S' 8. 113 6.08 5.3 n NO 2.7 1300 NO NO 15.4 NO 13.9 7.$J 11.5 19.3 J4.J NO NO 23 NO NO NO NO 3.SL I.. ltJ IS 30 NO .0 NO NO 3.• NO NO NO NO NO NO NO NOUJ NO NO NO 1.<'" ..• 3.' M"""", 2 NO 0.28 NO NO NO NO NO NO 0.11 J NO NO NO NO NO NO NO NO NO Nickel '00 200 32.9 NO 20.1 NO 15.5 10.3 17.6 50.5 30A NO NO 24 32 49.9 59.2 R 300 m 113 Selenium 30 60 NO NO NO NO UJ NO 0.75 0.6J NO NO NO NO NO NO NO 1.88J I·US 7.2 Silver 30 NO NO NO NO NO NO NO NO NO 2J 2J NO NO NO NO NO NO NO Vanadium 30 100 NO 22.2 •.8 NO 10.l 3.8 '.7 10.9 IS.7J .J 10J 10 NO NO NO O.49L 0.$6 ))• Zinc 2000 60.' NO 27.9 13.7 22.2 28.8 13.6 92.7 19.5 .. NO NO NO NO NO O.17l NO Monitoring Well MW9A '0 20 8.• 3 2.7 NO 6.4J 83 7.0 NO NO NO NO NO NO NO NO NO 17.6 ..• 0.08 0.16 1.3 NO NO NO I.' 1.2 1.I NO NO NO NO NO NO NO NO 0.408 NO NO • 8 NO 0 3.1 NO 1.7 NO NO NO NO NO NO NO NO NO NOR NO NO NO R 100 NO 0 29.6 NO 41.6 31.7 45.1 IS.S NO NO NO NO 84J 3.3 NO 2.00 NO L2 C 1300 '.2 NO 22.1 '.8 33.4 24.SJ 27.4 7.7 NO NO NO NO NO NO 3.2 DJ 8.40 NO NO L,'" 13 30 133 0 NO ... 16.81 II NO NO NO NO NO NO NO NO NOUJ ~'D NO NO M"" 2 NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO NO ~ickcl 100 200 49.S NO 20J NO 30.' 28.8 35.1 NO NO NO NO NO JI NO NO NO NO NO Selenium 30 60 12.1 0 NO NO 2.8J 1.9J 2" NO NO NO NO NO NO NO NO ~D 6.2N NO Silver 30 NO NO NO NO NO NO NO NO NO 2J NO NO NO NO NO NO NO NO Vanadium SO 100 S6.l 26.7 8.• 12.1 58.7 36.2 .... NO NO NO NO • SJ NO 7.7 DJ 2.29 J..4L 0.2 Zinc 2000 113 NO 34.9 20 98.3 93.4 67.5 14.4 NO NO 3S NO NO NO '.8 DJ NO NO NO Notes: All numerical values Ind resuJu are in mjcroarams per liter (\oIgIL). 2012 AltARs for eacb Contaminant of Concern arc the lesser of Minnesota Health Risk Limiu and USEPA Maximum Contaminant Levels. promulgated IS of 201 2.

ND-NocDetcceod. 9 • Compound detected in the associ,ted field blank. L - PataI1leter was lnalyz.od fer and me reponed value was oblaincd from I reading thOt wu k:M than the CRDL but ~au:f than or aqualla lhc IOL. J • Estimated value dlK! 10 minor QC deviation. R • Unusable value due to mljor QC deviation. S - S&mp'e spike recovery oulSide of conltollimil& APPENDIX C - PUBLIC AND REGULATORY AGENCY NOTIFICATIONS DEPARTMENT OF THE AIR FORCE

AIR FORCE RESERVE COMMAND

14 June 2012 934 MSG/CEV 760 Military Highway Minneapolis, MN 55450-2100

Minnesota Pollution Control Agency Remediation Division/Closed Landfill and Superfund Section Attn: Jeff Lewis 520 Lafayette Road St. Paul, MN 55155-4194

RE: Five-Year Review, Twin Cities Air Force Reserve Base Small Arms Range Landfill Site

Dear Mr. Lewis,

This letter provides notice to the Minnesota Pollution Control Agency (MPCA) that a statutory five-year review is being prepared for a former National Priorities List (NPL) site identified as the "Twin Cities Air Force Reserve Base - Small Arms Range Landfill Site." This site was also formerly on the Minnesota Permanent List of Priorities (PLP) as Subsite I of the "Twin Cities Air Force Reserve Base Site," MPCA Site ill SR73 (350). The site was an unpermitted disposal site located on property owned by the U.S. Air Force in Hennepin County, Minnesota. It was deleted from the NPL in December 1996, and deleted from the Minnesota PLP in June 1998. Five-year reviews of the site are required by Section 121 of the Comprehensive Environmental Response, Compensation, and Liability Act/Superfund Amendments and Reauthorization Act, and by the National Contingency Plan (Code of Federal Regulations, Title'40, Section 300.430(f)(4)(ii).

The 934th Airlift Wing, U.S. Air Force Reserve, will prepare the five-year review report. This will be the fourth five-year review. During the two previous five-year reviews, MPCA was given the opportunity to participate through document review and comri1ent. In both cases, MPCA declined to participate. A draft report for the fourth five-year review is anticipated to be available to the public and external agencies before the end of October 2012. We again extend to MPCA the opportunity to participate in the five-year review process. If MPCA would like to receive a copy of the draft report for review and comment, please notify me via letter, or telephone (612-713-1955), or e-mail to [email protected].

~~s.y~~

DOUGLAS S. YOCUM. Chief, Environmental Flight Ad ID~13505752 Date 1106/14/2012 J Time 11 :05 PM :J

PUBLIC NOTICE Five-Year Review Twin Cities Air Force Reserve Small Arms Range Landfill Hennepin County, Minnesota The 934th Airlift Wing, U.S. Air Force Reserve, is conducting a five-year review of the Twin Cities Air Force Reserve Base Small Arms Range Landfill site. The site was placed on the National. Priorities List (NPL) in 1987. In 1992, the Air Force and U.S. Environmental Protection Agency (EPA) selected natural attenuation, site maintenance, access restrictions, and groundwater and surface water monitoring as the cleanup remedy for the site. Monitoring conducted through 1995 determined that natural attenuation was an effective remedy. The site was deleted from the NPL in 1996. The remedy allows landfilled materials to remain on-site after the remedy is complete. Five-year reviews are required to ensure that the site remains protective of human health and the environment. During the review, the Air Force and EPA study information on the site, including monitoring data, and inspect the site. The public is invited to participate by reviewing and commenting on the Draft Report. Requests for additional information or for inclusion on a distribution list for the Draft Report may be made by contacting: Douglas Yocum 934th Airlift Wing 612-713-1955 [email protected]

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Karen Greenhoe, being duly sworn, on oath says she is and during all times herein stated has been an employee of Star Tribune Media Company LLC, a Delaware limited liability company with offices at 425 Portland Avenue, Minneapolis, Minnesota 55488, publisher and printer of the Star Tribune newspaper (the ~'Newspaper"), published 7 days a week, and has full knowledge of the facts herein stated as follows: I. The Newspaper meets the following qualifications: (a) The Newspaper is printed in the English language in newspaper format and in column and sheet form equivalent in printed space to at least) ,000 square inches; (b) The Newspaper is printed daily and distributed at least five days each week; (c) In at least halfofits issues each year, the Newspaper has no more than 75 percent of its printed space comprised of advertising material and paid public notices. In all of its issues each year, the Newspaper has not less than 25 percent of its news columns devoted to news of local interest to the community that it purports to serve. Not more than 25 percent of the Newspaper's non-advertising column inches in any issue duplicates any other publication; (d) The Newspaper is circulated in the local public corporation which it purports to serve, and has at least 500 copies regularly delivered to paying subscribers; (e) The Newspaper has its known office of issue established in either the county in which it lies, in whole or in part, the local public corporation which the Newspaper purports to serve, or in an adjoining county; (f) The Newspaper files a copy ofeach issue immediately with the state historical society; (g) The Newspaper is made available at single or subscription prices to any person, corporation, partnership, or other unincorporated association requesting the Newspaper and making the applicable payment; (h) The Newspaper has complied with all the foregoing conditions for at least one year immediately preceding the date of the notice publication which is the subject of the Affidavit; and (i) Between September I and December 31 ofeach year, the Newspaper publishes and submits to the secretary of state, along with a filing fee of$25, a sworn United States Post Office periodical class statement of ownership and cirCUlation. 2. The printed copy of the matter attached hereto (the "Notice") was copied from the columns of the Newspaper and was printed and published in the English language on the following days and dates: Sunday, June 17,2012. 3. Except as otherwise directed by a particular statute requiring publication ofa public notice, the Notice was printed in a typeface no smaller than six point with a lowercase alphabet of 90 point. 4. The Newspaper's lowest classified rate paid by commercial users for space comparable to the space in which the Notice was published is $231.00.

Subscribed and sworn to before me on June i8, 2012 ~~j &&&l:#uM'\