SEMS-RM DOCID # 1166269
THE UNITED STATES NAVY INSTALLATION RESTORATION PROGRAM
FINAL
RECORD OF DECISION FOR INSTALLATION RESTORATION PROGRAM SITES 10, 13, 15, 26, AND 27
ANDERSEN AIR FORCE BASE, GUAM
January 2011
THE UNITED STATES NAVY INSTALLATION RESTORATION PROGRAM
FINAL
RECORD OF DECISION FOR INSTALLATION RESTORATION PROGRAM SITES 10, 13, 15, 26, AND 27
ANDERSEN AIR FORCE BASE, GUAM
January 2011
Table of Contents
Contents ...... iii Acronyms ...... v 1.0 Declaration ...... 1-1 1.1 Site Name and Location ...... 1-1 1.2 Statement of Basis and Purpose ...... 1-1 1.3 Selected Remedy and Statutory Determinations ...... 1-2 1.4 Authorizing Signatures ...... 1-3 1.4.1 U.S. Navy ...... 1-3 1.4.2 U.S. Environmental Protection Agency ...... 1-5 1.4.3 Guam Environmental Protection Agency ...... 1-7 2.0 Decision Summary ...... 2-1 2.1 Site Name, Location, and Description ...... 2-1 2.2 Site History and Enforcement Activities ...... 2-2 2.2.1 Base Operational History ...... 2-2 2.2.2 Site 10 History ...... 2-19 2.2.3 Site 13 History ...... 2-19 2.2.4 Site 15 History ...... 2-19 2.2.5 Site 26 History ...... 2-20 2.2.6 Site 27 History ...... 2-20 2.2.7 Previous Investigations and Response Actions ...... 2-20 2.2.8 Enforcement Activities ...... 2-46 2.3 Community Participation ...... 2-46 2.4 Scope and Role of Operable Unit or Response Action ...... 2-50 2.5 Site Characteristics ...... 2-51 2.5.1 Physiography and Climate ...... 2-51 2.5.2 Geology ...... 2-51 2.5.3 Hydrogeology ...... 2-52 2.5.4 Ecology ...... 2-53 2.5.5 Nature and Extent of Contamination ...... 2-54 2.6 Current and Potential Future Land and Resource Uses ...... 2-67 2.6.1 Land Use ...... 2-67 2.6.2 Groundwater and Surface Water Uses ...... 2-69 2.7 Summary of Site Risks ...... 2-70 2.7.1 Summary of Human Health Risk Assessment ...... 2-70 2.7.2 Summary of Ecological Risk Assessment ...... 2-98 2.8 Documentation of Significant Changes ...... 2-105 3.0 Responsiveness Summary ...... 3-1 3.1 Stakeholder Comments and Lead Agency Responses ...... 3-1 3.2 Technical and Legal Issues ...... 3-1 4.0 References ...... 4-1
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 iii Andersen AFB, Guam January 2011
Tables 2-1 Public Notification of Document Availability ...... 2-49 2-2 Public Comment Period Requirements ...... 2-49 2-3 Exposure Point Concentrations for COCs Detected at Sites 10, 13, 15, 26, and 27 .. 2-72 2-4 Carcinogenic Toxicity Information for the Ingestion, Dermal Pathway ...... 2-81 2-5 Carcinogenic Toxicity Information for the Inhalation Pathway ...... 2-82 2-6 Non-Cancer Toxicity Information for the Ingestion, Dermal Pathway ...... 2-83 2-7 Non-Cancer Toxicity Information for the Inhalation Pathway ...... 2-85 2-8 Summary of Incremental Lifetime Cancer Risks and Cumulative Non-Cancer Hazard Indices at the Seven Sites on Andersen AFB ...... 2-88 2-9 Assessment and Measurement Endpoints for Step 3a BERA Considerations for Sites 10, 13, 15, 26, and 27 ...... 2-100 2-10 Tier 2 COPECs that Failed the Tier 2 LTL Screening Process ...... 2-101
Figures 1 Location of Guam in the Pacific Ocean ...... 2-3 2 Andersen AFB Location Map ...... 2-5 3 Site Location Map ...... 2-7 4 Location Map IRP Site 10...... 2-9 5 Location Map IRP Site 13...... 2-11 6 Location Map of IRP Site 15 ...... 2-13 7 Location Map of IRP Site 26 ...... 2-15 8 Location Map IRP Site 27...... 2-17 9 Site 10 Sampling Locations ...... 2-23 10 Excavation Boundaries and Soil Confirmation Sampling Locations IRP Site 10 ..... 2-25 11 Sampling Locations at Site 13 – Original Site ...... 2-29 12 Sampling Locations at Site 13 – Expansion Site ...... 2-31 13 Site 15 Sampling Locations ...... 2-35 14 Site Excavation Boundaries, Site 15 Soil Removal Action ...... 2-37 15 Site 26 Sampling Locations ...... 2-41 16 Site 27 Sampling Locations ...... 2-47 17 Soil Sample Results Above Screening Levels, IRP Site 10 ...... 2-55 18 Soil Sample Results Above Screening Levels, IRP Site 13 (Original Site) ...... 2-57 19 Soil Sample Results Above Screening Levels, IRP Site 13 (Expansion Site) ...... 2-59 20 Post-Removal Soil Sample Results Above Screening Levels at IRP Site 15 ...... 2-63 21 Surface and Shallow Subsurface Soil Sample Results Above Screening Levels Locations at IRP Site 27 ...... 2-65 22 Generalized Conceptual Site Model ...... 2-79
Appendices A Federal Facility Agreement Notice Letters B Responsiveness Summary and Response to Regulatory Comments C Risk Characterization Tables
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 iv Andersen AFB, Guam January 2011
Acronyms
°F degree Fahrenheit µg/dL microgram per deciliter g/L microgram per liter % percent 36 ABW 36th Air Base Wing AFB Air Force Base AR Administrative Record AST aboveground storage tank BCO Base Commanding Officer BERA baseline ecological risk assessment BGP Base General Plan bgs below ground surface Bldg. Building BTV background threshold value Cal/EPA California Environmental Protection Agency CDI chronic daily intake CERCLA Comprehensive Environmental Response, Compensation, and Liability Act CFR Code of Federal Regulations COC contaminant of concern COPC contaminant of potential concern COPEC contaminant of potential ecological concern CSM conceptual site model DDD dichlorodiphenyldichloroethane (rhothane) DDE dichlorodiphenyldichloroethylene DDT dichlorodiphenyltrichloroethane DERP Defense Environmental Restoration Program DoD Department of Defense DRO diesel range organics DSI detailed site inventory EE/CA engineering evaluation/cost analysis EM electromagnetic EPA Environmental Protection Agency, United States EPC exposure point concentration ERA ecological risk assessment ERP Environmental Restoration Program FFA Federal Facilities Agreement FS feasibility study ft foot or feet ft/day feet per day GC/MS gas chromatography/mass spectrometry
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 v Andersen AFB, Guam January 2011
GEPA Guam Environmental Protection Agency GRO gasoline range organics ha hectares HARM Hazard Assessment Rating Methodology HHRA human health risk assessment HI hazard index HQ hazard quotient ILCR incremental lifetime cancer risk IRP Installation Restoration Program K hydraulic conductivity lbs/day pound per day LTL lower trophic level MCL maximum contaminant level MDL method detection limit mg milligram mg/day milligram per day mg/kg milligram per kilogram mg/kg-day milligram per kilogram per day MMS Munitions Maintenance Squadron mph miles per hour NCP National Oil and Hazardous Substances Pollution Contingency Plan NFA no further action NFRAP no further remedial action planned NGL Northern Guam Lens No. number NPL National Priorities List OU operable unit PAH polynuclear aromatic hydrocarbon PCB polychlorinated biphenyl PCE tetrachloroethylene pH hydrogen ion concentration PP proposed plan PRG preliminary remediation goal RAB Restoration Advisory Board RCRA Resource Conservation and Recovery Act RFA RCRA facility assessment RfD reference dose RI remedial investigation RME reasonable maximum exposure ROD Record of Decision RSL regional screening level SARA Superfund Amendments and Reauthorization Act SBC soil benchmark concentrations
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 vi Andersen AFB, Guam January 2011
SF slope factor SUF site use factor SVOC semivolatile organic compound TPH total petroleum hydrocarbons TRV toxicity reference value U.S. United States UCL upper confidence limit USAF United States Air Force USDA United States Department of Agriculture USFWS United States Fish and Wildlife Service UST underground storage tank VES vapor extraction system VOC volatile organic compound yd3 cubic yard
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 vii Andersen AFB, Guam January 2011
1.0 Declaration
1.1 Site Name and Location Facility Name: Installation Restoration Program (IRP) Sites 10, 13, 15, 26, and 27
Site Location: Andersen Air Force Base (AFB), Guam
CERCLIS ID Number: GU6571999519
Operable Unit/Site: IRP Sites 10, 13, 15, 26, and 27
1.2 Statement of Basis and Purpose This Record of Decision (ROD) presents the Selected Remedy for IRP Sites 10, 13, 15, 26, and 27 at Andersen AFB, Guam, which was chosen in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980, as amended by the Superfund Amendments and Reauthorization Act (SARA) of 1986, and to the extent practicable, the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). This document is issued by the Navy1, as the lead agency. The Navy is managing remediation of contamination at IRP Sites 10, 13, 15, 26, and 27 in accordance with CERCLA as required by the Defense Environmental Restoration Program (DERP).
This decision is based on all the previous work conducted at the sites, which is documented in the Administrative Record (AR) file for the sites. The primary documents supporting this decision are listed below and are included in the AR:
Final Remedial Investigation Report for IRP Sites 03, 10, 13, 15, 21, 26, and 27 Andersen Air Force Base, Guam (AECOM 2010)
1 The Department of Defense (DoD) is in the process of realigning installation management functions at Andersen AFB. On 1 October 2009, pursuant to the 2005 Defense Base Closure and Realignment Commission Report (DBCRC 2005), administrative custody of all real property on Andersen AFB and responsibility for installation support functions, including Environmental Restoration Program responsibilities, transferred within the DoD from the Department of the Air Force to the Department of the Navy. Title to Andersen AFB real property will remain with the United States (U.S.), and the Air Force will continue to utilize the Base. The Navy will also utilize portions of the Base. In accordance with the Environmental Supplemental Guidance for Implementing and Operating a Joint Base (DoD 2008), at the time of property transfer, the Navy, as the new property manager at the Base, assumed responsibility "for all existing and future environmental permits, requirements, plans, and agreements" at the Base (DoD 2008, Ch. 1.1.2) and was required to: "honor all existing, previously negotiated Federal Facility Agreements in place" (DoD 2008, Ch. 2.17.5).
In January 2009, the Navy and the Air Force entered into a separate Memorandum of Agreement, which delegated installation support and authority back to the Air Force General who is the Andersen Base Commanding Officer (BCO) under the authority, control, and direction of the Joint Region Commander, who is a Navy Admiral. This delegation includes the authority to sign RODs. The Andersen BCO and Andersen environmental staff continue to administer the Federal Facilities Agreement (FFA) under Navy direction. Both the Air Force and the Navy notified the U.S. Environmental Protection Agency (EPA) of the change of administrative responsibility under the FFA (See Appendix A).
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 1-1 Andersen AFB, Guam January 2011
Proposed Plan for No Further Action at IRP Sites 10, 13, 15, 26, and 27, Andersen Air Force Base, Guam (USAF 2010)
Historical information can be found through the internet at http://www.adminrec.com/ PACAF.asp, and the above referenced documents can be found at the following locations:
Nieves M. Flores Memorial Library and University of Guam (UOG) 254 Martyr Street Government Documents Department Hagatna, Guam 96910 Robert F. Kennedy Library, UOG Station Phone: (671) 475-4751 Mangilao, Guam 96923 Phone: (671) 735-2316
The Navy and United States (U.S.) Environmental Protection Agency (EPA) have jointly selected the remedy for the site. The EPA concurs with the selected remedy. The Guam Environmental Protection Agency (GEPA) also concurs with the selected remedy.
1.3 Selected Remedy and Statutory Determinations A remedial investigation (RI) report summarized the various environmental investigations and interim response actions for seven IRP sites at Andersen AFB: Sites 3, 10, 13, 15, 21, 26, and 27. Based on the results of the human health and ecological risk assessments for five of the sites (Sites 10, 13, 15, 26, and 27), the Navy determined that exposure to contaminants of potential concern (COPCs) in site soil and soil gas does not pose an unacceptable risk to human health or the environment; therefore, no CERCLA action is necessary. Per the NCP (40 Code of Federal Regulations [CFR] 300.430(e)(6)), the Navy and EPA have co-selected no further action (NFA) for Sites 10, 13, 15, 26, and 27.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 1-2 Andersen AFB, Guam January 2011
1.4 Authorizing Signatures
1.4.1 U.S. Navy This signature sheet documents U.S. Navy co-selection of the remedy in this ROD for Sites 10, 13, 15, 26, and 27 at Andersen AFB, Guam.
______John W. Doucette Date Brigadier General, USAF Base Commanding Officer Under Delegation of Authority from Commander Joint Region Marianas
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 1-3 Andersen AFB, Guam January 2011 1.4.2 U.S. Environmental Protection Agency This signature sheet documents U.S. EPA co-selection of the remedy in this ROD for Sites IO, 13, 15, 26, and 27 at Andersen AFB, Guam.
:2 / :2 '1/ Qolb Angeles Herrera Date Assistant Director, Superfund Division Federal Facility and Site Cleanup Branch U.S. EPA Region 9
Final NFA ROD, !RP Sites IO, 13, 15, 26, a11d 27 1-5 A1u/ers1:11 AFB, Guam Ja1111ary 2011 I .4.3 Guam Environmental Protection Agency The Territory ofGuam EPA concur.; with the remedy selected in thi~ ROD for Sile.ct IO, 13, IS, 26, and 27 at ersen AFB, Gu8m.
/ cios Date Administrator Gullffi Environmental Protection Agency
Final NFll ROD. IRPS//e:s 10. 13. /5, 16, and 17 1-7 llnder:;en AFB, G11nn1 January 2011
2.0 Decision Summary The Decision Summary identifies the Selected Remedy, explains how the remedy fulfills statutory and regulatory requirements, and provides a substantive summary of the AR file that supports the remedy selection decision.
2.1 Site Name, Location, and Description Andersen AFB is the home for the Headquarters of the Pacific Air Force’s 36th Air Base Wing (36 ABW). Andersen AFB and Navy on Guam are presently managed by Joint Region Marianas. Andersen AFB is also home for the Air Mobility Command’s 734th Air Mobility Support Squadron, and several other tenant organizations.
Andersen AFB occupies the northern portion of Guam (Figure 1) and consists of three major subdivisions: the North Field (also referred to as the Main Base), the Northwest Field, and the Marbo Annex (Figure 2). The North Field, or Main Base, is where most of the active operations take place. All five sites included in this ROD are located on the Main Base (Figure 3).
Site 10 is located on the Main Base south of the eastern end of Perimeter Road and 1,000 feet (ft) northeast of Building (Bldg.) 19028. The site is approximately 33 acres in size. The access road through the Civil Engineer lay-down yard borders the southern side of the site, while mature limestone forest borders the northeastern side of the site. A grassy maintenance road borders the west side of the site, and a skeet range used by military personnel is located just off Perimeter Road in the northwestern corner of the site. The nearest surface water body is the Pacific Ocean, which is located approximately 2,100 ft to the east of the site (Figure 4).
Site 13 is located on the Main Base, approximately 2,500 ft north-northeast from Marine Drive. Site 13 consists of two separate physical sites herein known as the Original Site and the Expansion Site. The center of the Original Site lies approximately 3,000 ft south- southwest of the shoreline at Tarague Beach on the north shore of Guam. The Original Site comprises approximately 5.5 acres and represents a small former quarry with 35-ft to 40-ft vertical walls extending upward to the surrounding limestone plateau. The quarry is situated atop a steep slope consisting predominantly of loose gravel, large boulders intermixed with debris, and overgrown vegetation (Figure 5). The center of the Expansion Site lies approximately 4,000 ft south-southwest of the shoreline at Tarague Beach and 1,400 ft south of the Original Site. The Expansion Site is approximately 11.5 acres and is situated atop the plateau within gently rolling terrain (Figure 5).
Site 15 is an inactive facility approximately 10 acres in size. It resides in the southeastern portion of the Main Base at Andersen AFB and is accessed using an unpaved road from the golf course. Site 15 is the location of Andersen AFB’s former sewage treatment plant, and is situated approximately 1,000 ft east of the present Palm Tree Golf Course sanitary sewage lift station (Bldg. 1098). Site 15 is situated approximately 1,000 ft west of the eastern cliff edge of Guam, and is bounded to the east by ridges and on the northern, eastern, and southern borders by undulating, dense limestone forest. A residential housing area, Robert’s Terrace, is located approximately 2,000 ft to the southwest of the site (Figure 6). Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-1 Andersen AFB, Guam January 2011
Site 26 comprises approximately 5 acres and is situated in the northwest corner of the flightline on the Main Base at Andersen AFB. Site 26 is bounded to the north and west by Perimeter Road and to the south and east by vegetation. The area surrounding the site is covered primarily with grass, gravel, and exposed limestone bedrock. The site is located within the fenced area of the flightline. Access to the site is restricted by a chain-link fence and locked gate. The areas of concern at Site 26 include an abandoned burn pit, an oil/water separator, an aboveground storage tank (AST), and an underground storage tank (UST). These areas were initially the main focus of the environmental investigation at Site 26 (Figure 7).
Site 27 is located southwest of the intersection formed by Perimeter Road and Marianas Boulevard, adjacent to the Andersen II Tank Farm. Perimeter Road borders the northwest side and Marianas Boulevard the northeast side of the site. Both roads are separated from the site by approximately 120 ft of maintained grass. The Andersen II Tank Farm fenceline and an access road to the Tank Farm complete the site borders on the southeast and the southwest, respectively. The site was landscaped to direct drainage from the pad and surrounding roadways to the three dry injection wells, which are part of Andersen AFB’s Stormwater Drainage System number (No.) 2 and are located adjacent to the site’s southeastern border. The site is approximately 9.4 acres in size, and consists of a 500-ft by 200-ft asphalt area on the northeast end and a 3-by-3 array of nine 100-ft by 100-ft, raised asphalt pads to the southwest (Figure 8).
Andersen AFB IRP conducted investigations at Sites 10, 13, 15, 26, and 27 in accordance with CERCLA under the DERP, which was established by Section 211 of the 1986 SARA.
As the support agencies, EPA Region 9 provides primary oversight of the environmental restoration actions, in accordance with the Federal Facilities Agreement (FFA) with concurrence by the GEPA.
2.2 Site History and Enforcement Activities This section provides background information and summarizes the series of investigations that led to the ROD. It describes the CERCLA response actions undertaken at IRP Sites 10, 13, 15, 26, and 27.
2.2.1 Base Operational History Historically, the U.S. Army Air Corps built and maintained three air bases on Guam after World War II when Americans took control of the island from the Japanese in July 1944. Since October 2009, the Navy has assumed responsibility for the real estate administration and the implementation of the FFA for Andersen AFB. The Navy has delegated signature authority for the ROD to the Andersen AFB BCO. Construction began on the North Field in November 1944 and at Northwest Field in January 1945, and they were completed in the first half of 1945. The Northwest Field has remained inactive since 1949, and it has since been used by the military for various training exercises.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-2 Andersen AFB, Guam January 2011 N
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Figure 1 Location of Guam in the Pacific Ocean Record of Decision for IRP Sites 10, 13, 15, 26 and 27 Andersen AFB, Guam ANDERSEN AFB
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r,_ , a ANDERSEN AFB COMMUNICATION ANNEX
NORTH PACIFIC ~ OCEAN lJ N 0 3 GUAM SCALE IN MILES
Legend
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Major Road
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Figure 2 Andersen AFB Location Map Record of Decision for IRP Sites 10, 13, 15, 26 and 27 Andersen AFB, Guam ,,.__ ' PACIFIC OCEAN
SITE 26
TARAGUE BEACH '
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SITE 15. " \ SITE 13 ,--'--,- '..J N ,--,--,-- 3000' 0 3000' 1o--s;;;-~ I SCALE IN FEET
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Figure 3 Site Location Map Record of Decision for IRP Sites 10, 13, 15, 26, and 27 Andersen AFB, Guam ~ LEGEND N 0 1000' 11111111111111 IRP SITE 10/LANDFILL 14 -- --- IRP SITE BOUNDARY ---GRAPHIC SCALE IN FEET--- 1 IR+s MONITORING WELL
Figure 4 Location Map IRP Site 10 Record of Decision for IRP Sites 10, 13, 15, 26, and 27 Andersen AFB, Guam 1,000 0 1,000 L:\work\AFCEE\Guam\TO 0025 (60133951)\Reports\RI Report\Andersen Figures\Figure 6 IRP Site 15 Loc Map.ai 6/13/2010 rks 0025 (60133951)\Reports\RI Report\Andersen Figures\Figure 6 IRP L:\work\AFCEE\Guam\TO
Figure 6 Location Map of IRP Site 15 Record of Decision for IRP Sites 10, 13, 15, 26, and 27 Andersen AFB, Guam IRP SITE BOUNDARY '°N 0 0 ~ INSTALLATION BOUNDARY ~ § N ll!llla!llll!at IRP SITE 26 /FIREFIGHTER "' llBllRliBllll TRAINING A~EA-2 ~ 1500' 0 1500' 4 -- --- IRP-4 GROUNDWATER r ---GRAPHIC SCALE IN FEET --- + MONITORING WELL ~ ~ L-~~~~~~~~~~~~~~~~~~~~~~~~__JL_~~~~~~~~~__J
Figure 7 Location Map of IRP Site 26 Record of Decision for IRP Sites 10, 13, 15, 26, and 27 Andersen AFB, Guam MAIN
1 0 0 0 0 00 0 0 0 ~ nHn
LEGEND ~ --- IRP SITE BOUNDARY '°N - · - INSTALLATION BOUNDARY 0 0 0 N / 1!8888!!88 IRP SITE 26/FIREFIGHTER ~ 1188888811 TRAINING AREA-2 ~ 1000' 0 1000' ~ ~~~~~--~~ IRP-4 GROUNDWATER 0 MONITORING WELL ~ GRAPHIC SCALE IN FEET + ~ '--~~~~~~~~~~~~~~----::::------::---~~~__._~~~~~~~~~~~_J Figure 8 Location Map IRP Site 27 Record of Decision for IRP Sites 10, 13, 15, 26, and 27 Andersen AFB, Guam
Andersen AFB was placed on the National Priorities List (NPL) on 14 October 1992. Final listing brought Andersen AFB under the federal facility provisions of CERCLA. In March of 1993, the U.S. Air Force (USAF) entered into a FFA with the EPA and the Territory of Guam for installation environmental restoration efforts specific to a design RI/Feasibility Study (FS).
Each of the five sites was first identified during the IRP Phase I Records Search in August 1984, whereupon the sites were assessed using the Hazard Assessment Rating Methodology (HARM), which evaluated factors such as site characteristics, waste characteristics, potential for contaminant migration, and waste management practices (ESE 1985). The HARM system was designed to indicate the relative need for remedial action. Sites receiving a HARM score were recommended for further investigation.
A Resource Conservation and Recovery Act (RCRA) Facility Assessment (RFA) was conducted in 1986 and assessed 63 solid waste management units and other areas of concern to evaluate their respective potential for releases to the environment (SAIC 1986). The following sites were included in the RFA: Site 10, Site 15, and Site 27.
2.2.2 Site 10 History Based upon the results of a records search, Site 10 was operational from the 1950s through 1976 and was used for sanitary, industrial, and debris disposal. The site supposedly consisted of a shallow excavated area with fill, concrete debris, wood, and solid construction debris. Soil cover was used to close the site (ESE 1985). However, in the 1993 aerial photographs, the identification of various types of debris, clearings, mounds, and access roads indicate active or recent landfill activities.
2.2.3 Site 13 History Site 13 was used from 1967 to 1968 for the disposal of waste liquids, deteriorated metal drums, miscellaneous scrap metal, construction debris, and asphaltic materials from the asphalt plant located to the south of the site (ICF 1996).
2.2.4 Site 15 History Site 15 was used for sewage treatment and as a fill area for disposal of construction or demolition debris, general refuse, and municipal waste. Site 15 served as the Andersen AFB sewage treatment plant from 1948 through 1963 (Andersen AFB 1948, 1963) where sanitary wastewater was passed through the treatment plant and effluent was discharged over the cliff-line outfall into the Pacific Ocean (Andersen AFB 1948). The sewage treatment plant was non-operational because of overloading that required repair of the sanitary sewer system (Andersen AFB 1963) from 1963 until 1975, whereupon raw sanitary sewage was discharged directly into the Pacific Ocean (Andersen AFB 1975b). The sewage treatment plant was abandoned in June 1975 (Andersen AFB 1975a). No records could for the years 1975 through 1981 were available for review. Since 1981, sanitary wastewater from Andersen AFB has been connected to the Guam municipal wastewater treatment system (FWENC 2002).
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-19 Andersen AFB, Guam January 2011
2.2.5 Site 26 History Site 26 is a former firefighter training area located in the northwest corner of the flightline on the Main Base at Andersen AFB. Firefighter training exercises, which took place at the site from 1958 through 1988, consisted of filling the old burn pit with water and releasing fuel mixtures that were ignited then extinguished by firefighters. After the exercises, residual liquids were drained into an onsite oil/water separator. Field activities were conducted serially as part of investigations that took place between 1996 and 2002. A vapor extraction system (VES) was operated beneath the former UST from 1998 through 2007.
2.2.6 Site 27 History Site 27 was reportedly used as an outside storage area for petroleum, oil, lubricants, and solvents from 1950 to the late 1970s. Potentially hazardous wastes were reportedly stored on a 300-ft by 200-ft area in the northern corner of the site from the late 1970s to late 1983 (ICF 1996). Since 1983, the site has been intermittently used as a temporary parking lot for trucks and for fire-training activities.
2.2.7 Previous Investigations and Response Actions
2.2.7.1 Site 10 Previous Investigations and Response Actions The IRP Phase I Records Search (ESE 1985) concluded that Site 10 posed no potential for contamination or hazardous leachate formation, and that based on the evaluation of past operations, NFA was recommended. No HARM score was given.
The RFA Report (SAIC 1986) noted that no evidence of a potentially hazardous release in the area was observed and no records of release were found. It was not known whether hazardous wastes were disposed of at this landfill.
Site reconnaissance confirmed that the site consisted of a shallow excavated area with fill, concrete debris, wood, and solid construction debris, and that soil cover was used to close the site (ESE 1985). Also, an area with approximately 30 drums has been observed approximately 250 ft southwest of the site.
2.2.7.1.1 Site 10 Engineering Evaluation and Cost Analysis (EE/CA) A field investigation was conducted at the site between February and July 1997 as part of an engineering evaluation and cost analysis (EE/CA), and is documented in the Final EE/CA Report for IRP Site 10 dated May 1999 (EA 1999a). The field investigation at Site 10 included a site reconnaissance/detailed site inventory (DSI), surface soil sampling, electromagnetic (EM) geophysical survey, soil gas sampling, topographic survey, and ecological survey.
Site reconnaissance was performed to locate the horizontal boundary of landfill operations. A DSI was performed to document physical evidence of surface disposal within the Site. All waste materials were described and located within 1-ft of accuracy.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-20 Andersen AFB, Guam January 2011
Subsequent to the DSI, an EM geophysical survey was conducted to identify any subsurface anomalies that may indicate landfill areas. Using an excavator, a total of 33 test ditches were excavated to evaluate the horizontal extent of buried waste, based upon the results of the DSI, EM survey, and soil gas survey. Each ditch was excavated until bedrock was encountered or to a depth no deeper than 3 ft below the bottom of the waste.
A total of 70 whole-air, active soil gas sample points were installed along a survey grid. Soil gas samples were collected at these points and analyzed for volatile organic compounds (VOCs) at the onsite gas laboratory. A total of 12 locations were resampled because of the presence of an unknown contaminant detected in equipment blanks collected prior to sampling. No target VOCs were detected at or above the method detection limits (MDLs). A second round of eight soil gas samples were collected, including two passive soil gas (GoreSorber) samples and six active soil gas samples. No VOCs were detected.
A total of 63 surface soil samples were collected from 33 locations at Site 10 (Figure 9) to characterize possible contamination associated with the onsite debris. Samples were collected at randomly selected 100-ft grid intersections, and in a biased manner, with the biased samples collected in areas covered with debris, areas of stressed vegetation, or in drum locations. Samples were analyzed for semivolatile organic compounds (SVOCs), metals, and cyanide.
Sample results were compared to the 1998 EPA Region 9 preliminary remediation goals (PRGs) and background threshold value (BTVs) (EPA Region 9 1998), and 22 of the samples had polynuclear aromatic hydrocarbons (PAH) concentrations that exceeded residential PRGs. The samples that contained PAHs were generally located in areas where drums or mounds with asphalt/tar-like material were observed (EA 1999a). Additionally, eight surface soil samples exceeded residential PRGs and BTVs for the metals iron, manganese, lead, and antimony. Because of the proximity of the skeet range in the northern reaches of the site, it is likely that the elevated concentrations of lead and antimony are due to metal shot in the soil, the presence of which was observed during the DSI (EA 1999a). Additional surface soil samples were collected in July 1997 to further characterize the lateral extent of PAHs and metals.
Results from the test ditching, geophysical survey, and DSI indicated eight possible waste disposal areas. Six of the areas consisted of mounds of debris and fill material above grade. One test trench was excavated from each of the areas and an associated subsurface soil sample was collected. A total of seven subsurface soil samples (including one duplicate), were collected from the six test pits, and analyzed for SVOCs, metals, and cyanide. In the subsurface soil samples, no VOCs were detected at or above the MDL. Several PAHs were detected but not above residential PRGs. Additionally, no metals exceeded BTVs and residential PRGs in the subsurface soil samples.
In June 1998, a qualitative habitat and biota survey was conducted at Site 10. Major habitats were identified and characterized, and a detailed inventory of fauna and flora at the site was developed: dominant vegetation was identified, canopy cover and tree diameter breast height was recorded, as were all animal sightings, including signs such as trails, scat, and antler rubbings. Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-21 Andersen AFB, Guam January 2011
The results of the 1999 human health risk assessment (HHRA) indicated no concern for adverse health effects for either occasional users/trespassers or resident adults (EA 1999a). However, it did conclude that potential non-cancer health concerns existed for future resident children, who may be exposed to COPCs through incidental ingestion and dermal contact with surface soil, and through inhalation of particles from surface soil. These risks were driven principally by antimony and manganese. Excess lifetime cancer risk calculations for resident children resulting from exposure to COPCs in soil and air at Site 10 via ingestion, dermal contact, and inhalation of soil particles were within the upper end of the acceptable range according to NCP standards.
2.2.7.1.2 Site 10 Interim Removal Action Based upon the results of the 1999 HHRA, further action was warranted to address soils containing elevated concentrations of antimony, lead, manganese and PAHs. The 1999 EE/CA evaluated several remedial alternatives and recommended (1) the removal of contaminant of concern (COC)-impacted soils, asphalt, and asphalt-containing drums and (2) that they be transported to Andersen AFB landfill, or a certified off-island hazardous waste disposal facility. The USAF decided to perform a non-time-critical removal action to minimize human health risks posed by Site 10. Although future residential development of the site was not expected, as a conservative measure, the child resident exposure scenario was used to generate remedial goals (EA 1999a). Remedial goals were chosen using the target cancer risk value of 1E–06 for carcinogenic COCs (PAHs), non-cancer hazard index (HI) of 1 (or BTV, whichever was greater) for non-cancer COCs (manganese and antimony), and the EPA lead screening value of 400 milligrams per kilogram (mg/kg) (EA 1999a).
Between September 1999 and April 2006, interim removal actions were performed at the 14 areas at Site 10 (Figure 10). Approximately 9,360 cubic yards (yd3) of contaminated soil was removed and disposed of at the on-base waste consolidation unit. In addition to contaminated soils, approximately 400 drums containing asphaltic material, 3 drums of hydraulic fluid/motor oil, several drums of silicone grease, and an accumulation of automotive batteries and other metallic debris were also removed and disposed of off site at the on-base consolidation unit. Following interim removal actions, the site was subsequently regraded and the excavations backfilled with clean soil.
2.2.7.2 Site 13 Previous Investigations and Response Actions The IRP Phase I Records Search (ESE 1985) concluded that Site 13 posed no potential for contamination or hazardous leachate formation and, based on the evaluation of past operations, NFA was recommended. No HARM score was given.
Site 13 was not investigated during the subsequent 1986 RFA.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-22 Andersen AFB, Guam January 2011 IRP Site 10 + '
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LEGEND + SURFACE SOIL SAMPLE ~ SUBSURFACE SOIL SAMPLE N - IRP SITE BOUNDARY 200' 0 200' --~--~ BANYAN TREE I • I
Figure 9 Site 10 Sampling_ ~oca f 10 ns Record of Dec1s1on ford 27 IRP Sites 10, 13, 15, 26, an Andersen AFB, Guam rks
APPROXIMATE SCALE 1 : 2,400 L:\work\AFCEE\Guam\TO 0025 (60133951)\Reports\RI Report\Andersen Figures\Figure 10 Exca Bound IRP 10 [Converted].ai 7/14/2010 10 Exca Bound IRP Report\Andersen Figures\Figure 0025 (60133951)\Reports\RI L:\work\AFCEE\Guam\TO Figure 10 Excavation Boundaries and Soil Confirmation Sampling Locations IRP Site 10 Record of Decision for IRP Sites 10, 13, 15, 26, and 27 Andersen AFB, Guam
During a 1992 site visit by ICF (ICF 1994) approximately 200 drums were observed in a forested area near the base of the slope. Most of the drums appeared deteriorated and empty; however, some could not be examined. In addition, a deteriorated drum was observed on the cliff face and a small tar spill, approximately 20 ft by 15 ft, was seen above the slope at the former rock quarry (ICF 1996). Based on a records search (ICF 1996), the area was reportedly used as a disposal area for empty asphalt drums and waste liquids. However, that search was not able to confirm disposal or waste types for this site. Operations are assumed to have been concurrent with a nearby asphalt plant that operated from 1967 to 1968. The asphalt plant was situated at the Munitions Maintenance Squadron (MMS) building located to the south of and proximal to the Original Site (within approximately 1,500 to 2,000 ft). IRP Site 13 was also used for the disposal of various debris types, including unexploded ordnance/ordnance and explosive waste, household debris, and metal debris.
The Expansion Site was discovered in 2002 during fire prevention and clearing operations adjacent to Bldg. 9100. Approximately three separate areas containing accumulations of concentrated and deteriorated metal drums, asphalt mounds, and fill material with metal and other debris were found within this area.
2.2.7.2.1 Site 13 Engineering Evaluation and Cost Analysis A field investigation at Site 13 was conducted between March 2000 and January 2003 as part of an EE/CA, and is summarized in the Draft EE/CA Report for IRP Site 13 dated October 2003 (URS 2003). Field activities included a visual site reconnaissance, DSI, EM geophysical survey, test pitting, surface and subsurface soil sampling, topographic survey, and an ecological survey.
The DSI was conducted to accurately define the environmental setting and boundaries of the site, and the location of a former limestone quarry including identification of potentially hazardous wastes.
Subsequent to the DSI, an EM geophysical survey was performed to define the horizontal extent of buried wastes at the site. The EM survey consisted of 14 survey areas: three above the cliff-line, two at the base of slope at the Original Site, and nine survey areas at the Expansion Site. These surveys were conducted in areas that could be easily walked and cleared of small shrubbery, and that were relatively flat.
Test pit locations were chosen and excavated based on the DSI survey and geophysical survey to characterize the buried waste contained in large mounds or subsurface areas of the site. Because of the topographic nature of the site and the subsurface geology, excavating activity was severely limited and, thus, the number of excavated pits was limited. Large quantities of tar and asphalt were encountered during the excavation of several test pits.
Four rounds of soil sampling were conducted at IRP Site 13 and encompassed both the Original Site and Expansion Site. Soil samples were collected from the associated fill areas of the former dumpsite, areas of concentrated debris, and areas suspected to contain COPCs based on the DSI and geophysical survey. Soil samples were collected from the Original Site in May 2000, January 2002, and June 2002. Soil samples were collected from the Expansion Site in June 2002 and January 2003. Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-27 Andersen AFB, Guam January 2011
In May 2000, 33 surface soil and 10 subsurface soil samples were collected at the Original Site and analyzed for SVOCs, PAHs, pesticides, polychlorinated biphenyls (PCBs), metals, and cyanide. As part of the 2003 EE/CA, analytical results were compared to 2000 EPA PRGs (EPA Region 9 2000) and BTVs. Because of a number of samples with elevated arsenic and manganese values, in January 2002, 17 additional surface soil samples and nine subsurface soil samples were collected to further delineate the extent of arsenic and manganese impacts. Also, four additional samples were analyzed for PAHs. In June 2002, two additional surface soil samples and seven subsurface soil samples were collected and analyzed for arsenic and manganese to further delineate the extent of surface contamination where test pit excavation activities took place in January 2002 (Figure 11).
June 2002, 11 surface soil samples were collected from the Expansion Site and analyzed for PAHs, pesticides, PCBs, metals, and cyanide (Figure 12). No subsurface soil samples were collected. In January 2003, 41 additional surface soil samples were collected and analyzed for the same series of analytes to better delineate the nature of the compounds detected in the first round of soil sampling. Also collected were 11 subsurface soil samples, and analyzed for PAHs, manganese and lead, as these analytes represented the most pervasive exceedances detected during the June 2002 surface soil sampling.
Analytical results were compared to the 2000 U.S. EPA Region IX Preliminary Remedial Goals (PRGs) and BTVs that were developed as part of the Operable Unit (OU) 3 RI. A HHRA and ecological risk assessment (ERA) were also performed. The HHRA concluded that cumulative non-cancer risks across all soil exposure pathways for both surface and subsurface soils exceeded the HI threshold of 1.0 for future resident adults and children, driven primarily by arsenic and manganese. There was no non-cancer COC identified for occasional users/trespassers in surface soil at IRP Site 13.
Cumulative cancer risks for surface soil were within the EPA acceptable risk range of 1E-04 to 1E-06 for all receptors (adult and child resident and occasional user/trespasser). Subsurface soil cancer risks exceeded 1E-04 for resident adults and children, driven primarily by arsenic.
The ERA concluded that risks to all identified ecological receptors from exposure to COPC in surface soil appear to be acceptable based on the conservative risk assessment results. NFA was recommended.
Based upon the results of the HHRA, the EE/CA recommended further action for surface soils. Four remedial alternatives were evaluated: 1) No Action; 2) Institutional Controls; 3) Installation of a Soil Cover; and 4) Surface Soil Removal. Alternative 4 was recommended.
However, an updated risk assessment performed for Site 13 as part of the 2010 RI concluded that site-specific soil conditions measured at the site possess sufficient binding potential to effectively reduce the bioavailability of the metals, thereby reducing potential site risks to within, or below, the EPA acceptable risk range of 1E–04 to 1E–06 for all receptors.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-28 Andersen AFB, Guam January 2011 Philippine E-6+00 Sea D- ~
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LEGEND + SURFACE SOIL SAMPLE LOCATION + SUBSURFACE SOIL SAMPLE LOCATION § WOODEN TELEPHONE POLE EDGE OF VEGETATION
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Figure 11 Sampling Locations at Site 13 -Original Site Record of Decision for IRP Sites 10, 13, 15, 26, and 27 Andersen AFB, Guam LEGEND
SURFACE SOIL + SAMPLE LOCATION SUBSURFACE SOIL + SAMPLE LOCATION EDGE OF LIMESTONE ~ VEGETATION GEOPHYSICAL D-6~ SURVEY POINT • SURVEY CONTROL POINT
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'°N 0 0 Figure 12 0 / g Sampling Locations at Site 13 - f: Expansion Site [;1 Record of Decision for ~ IRP Sites 10, 13, 15, 26, and 27 / ' Andersen AFB, Guam ~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
2.2.7.3 Site 15 Previous Investigations and Response Actions Based on the 1985 IRP Phase I Records Search, Site 15 was operated as an area for fill and debris disposal during 1968, and had a minimal potential for contamination or hazardous leachate formation. Site 15 was, therefore, recommended for NFA (ESE 1985). The RFA Report did not address Site 15 because “the area was reportedly heavily overgrown, and is not recognizable as a disposal site.” It concluded that there was “no potential for past or ongoing release” because the site was not known to contain hazardous constituents (SAIC 1986).
2.2.7.3.1 Site 15 Engineering Evaluation and Cost Analysis A field investigation was conducted at Site 15 between March and July 2001 that included a visual site reconnaissance, DSI, EM geophysical survey, soil gas survey, test ditching and trenching, surface and subsurface soil sampling, an ecological survey, and a topographic survey. Results of the EE/CA were documented in the Final EE/CA Report for IRP Site 15 (FWENC and EA 2002).
A site reconnaissance and DSI were conducted to accurately define the boundary and nature of the environmental setting of the site, including the identification of any potentially hazardous wastes.
An EM geophysical survey was performed following the DSI to define the horizontal extent of suspected buried wastes at the site. The geophysical survey was conducted by taking initial EM measurements at approximately 6-inch intervals along the 100-ft grid lines established at the site. Results of the geophysical survey indicated that the majority of anomalies were consistent with metallic surface debris and the sewage treatment plant- related structures identified during the DSI.
A soil gas survey consisting of eight soil gas probes was conducted to evaluate the presence and extent of VOCs in the subsurface soil and bedrock around the Imhoff tank and the sludge drying bed at Site 15. Soil gas probes were installed to a depth of approximately four ft below ground surface (bgs). Soil gas samples were collected from each of the soil gas probes, and were analyzed for VOCs using the on-island gas chromatography/mass spectrometry (GC/MS). No VOCs were detected.
Test ditches and test pits were excavated around the perimeter of areas of interest identified during the DSI and geophysical surveys for visually confirming the nature and extent of buried waste. Four test ditches were completed at the site. Nine test pits were also excavated to determine the contents of surface mounds and the vertical extent of buried waste debris.
A total of 33 surface soil samples and 14 subsurface soil samples were collected and analyzed for VOCs (subsurface samples only), SVOCs, PAHs, pesticides, PCBs, and metals (Figure 13). Analytical results were compared to the 2000 EPA PRGs and BTVs. Benzo(a)pyrene was detected at elevated concentrations in two surface soil samples collected in the northern portion of the site, while several pesticides were detected in one surface soil sample at concentrations exceeding the residential PRGs. Additionally, chromium and iron were detected at concentrations exceeding the residential PRGs and BTVs each in one surface soil sample. Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-33 Andersen AFB, Guam January 2011
Four subsurface soil samples were collected from within the Imhoff Tank and Sludge Drying Bed. The sample from the bottom of the Imhoff Tank contained the pesticides α-chlordane and γ-chlordane above residential PRGs. Samples from the Sludge Drying Bed contained several PAH compounds, the metals arsenic, lead, mercury, and cadmium, the PCB Aroclor 1260, and the pesticides, aldrin, dieldrin, α-chlordane, γ-chlordane, dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethylene (DDE), and dichlorodiphenyldichloroethane (DDD) residential and industrial PRGs and/or BTVs (Figure 13).
Results of the HHRA concluded that the cancer risks posed by exposure to surface or subsurface soil, all pathways, was within EPA’s risk range of 1E–04 to 1E–06. The HHRA also concluded that there was no concern for adverse non-cancer health effects among current and future occasional users/trespassers for exposure to either surface or subsurface soils.
For surface soil, non-cancer HIs exceeded 1.0 for future residents, and cumulative non- cancer risks across all pathways exceeded an HI of 1.0 for future potential resident adults and children for exposure to subsurface soil at the site.
The ERA concluded that seven metals (beryllium, cadmium, chromium, lead, manganese, thallium, and zinc) and three organic compounds (chlordane, DDT/DDD/DDE, and carbazole) were identified as contaminants of potential ecological concern (COPECs) at Site 15. Ecological risks were modeled through representative receptors, including plants, soil invertebrates, Mariana crow, Micronesian starling, yellow bittern, and the Mariana fruit bat. The Tier 1 ERA concluded acceptable risks to the Mariana fruit bat, soil invertebrates, and terrestrial plants at Site 15. However, all three modeled bird species were found to be at potential risk from total DDT.
Based upon the results of the HHRA and ERA, further action was warranted to address soils containing elevated concentrations of PAHs, metals, and pesticides. The EE/CA evaluated several alternatives, and the USAF selected the Removal Alternative Protective of Residential Users as the preferred alternative to minimize exposure risks to human and environmental receptors without restricting future land use. Although future residential development of the site was not expected, as a conservative measure, the child resident exposure scenario was used to generate remedial goals (Shaw 2006) of 1E–06 for carcinogenic COCs, and a non-cancer HI of 1 (or BTV, whichever was greater) for non-cancer COCs (Shaw 2006).
2.2.7.3.2 Site 15 Interim Removal Action An interim removal action was conducted at Site 15 to address surface and subsurface soil contamination. The interim removal action was conducted in two phases: Phase I–August 2006 through November 2006 and Phase II–Spring–Summer 2009 (Figure 14), and are documented in the Interim Removal Action Completion Report (Shaw 2009). The scope and extent of the interim removal action consisted of:
Demolition of onsite structures, including the Parshall Flume, Bar Screen, Tool House, portions of the Imhoff Tank, and Sludge-Drying Bed. 3 Excavation and removal of approximately 3,063 yd of COC-contaminated soil, which was disposed of along with 356 yd3 of concrete from the demolished structures, and 95-linear feet of asbestos-containing pipe at the on-base consolidation unit.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-34 Andersen AFB, Guam January 2011 + -----
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SURFACE SOIL SAMP~ LOCATION SUBSURFACE SOIL SAMP~ LOCATION WITH DESCRIPTOR '°N 0 0 2 GEOPHYSICAL CONTOURS / ~ f: N 0: 100' 0 100' "° ~ ' ------~ ...._~~~~~~~~~~~~~~~~~s_c_A~~IN~~-~~~~~~~~~~~~~~~~~~~---'
Figure 13 Site 15 Sampling Locations Record of Decision for IRP Sites 10, 13, 15, 26, and 27 Andersen AFB, Guam Figure 14 Site Excavation Boundaries, Site 15 Soil Removal Action Record of Decision for IRP Sites 10, 13, 15, 26 and 27 Andersen AFB, Guam L:\work\AFCEE\Guam\TO 0025 (60133951)\Reports\RI Report\Andersen Figures\Figure 14 SEB Site 15.ai 6/15/2010 rks Site 15.ai 6/15/2010 14 SEB Figures\Figure Report\Andersen 0025 (60133951)\Reports\RI L:\work\AFCEE\Guam\TO
3 Excavation and removal of 125 yd of PCB-contaminated soils and associated piping, which was subsequently disposed of off-island at the U.S. Ecology facility in Beatty, NV.
Performance of a successful field treatability study for the treatment of hazardous pesticide-contaminated soil, with subsequent treatment of 945 yd3 of hazardous pesticide-contaminated soil, which was subsequently disposed of at the consolidation unit. 3 Removal of approximately 70 yd of recyclable metal and transported to an on-island recycling facility.
Following completion of interim removal activities, all excavated areas were backfilled using clean overburden soil, compacted, and graded. An approximate 3-inch layer of topsoil was subsequently placed over the backfilled areas to encourage growth of native shrubs, plants, and trees.
2.2.7.4 Site 26 Previous Investigations and Response Actions The IRP Phase I Record Search (SAIC 1986) performed for several sites, including Site 26, noted that at Site 26, flammable liquids were used for training including various fuels, solvents, and oil. The flammable liquids were stored on site in the 6,000-gallon AST. The flammable liquids were later changed to Jet Propellant 4 only.
An IRP Phase II Stage 1-Confirmation/Quantification Investigation was conducted at the abandoned burn pit in 1987 to determine the existence of potential contamination (Battelle 1989). Four surface soil samples were collected from the burn pit, and a monitoring well IRP-4 was drilled, installed, and sampled. Ethylbenzene (12 mg/kg), toluene (21 mg/kg), and total xylenes (109 mg/kg) were identified in one of the soil samples collected from the burn pit. No soil action levels existed at the time of sampling. No VOCs were detected in any of the groundwater samples collected from monitoring well IRP-4 at concentrations that exceeded maximum contaminant levels (MCLs).
Additional soil samples from the abandoned burn pit and groundwater samples from monitoring well IRP-4 were collected as part of the IRP RI/FS Phase II Stage 2 field investigation in 1989. A total of 12 surface soil samples were collected from the burn pit area from 0 to 3 inches bgs (SAIC 1991a,b). No VOCs, SVOCs, pesticides/PCBs, or metals were detected in any of the soil samples at concentrations that exceeded the 2000 EPA Region 9 PRGs or BTVs. Total petroleum hydrocarbons (TPH)-diesel range organics (DRO) was detected in all samples at concentrations ranging from 16 to 19,000 mg/kg. No VOCs, SVOCs or pesticides/PCBs were detected at concentrations that exceeded the MCLs in the groundwater samples collected from IRP-4 during 20 April and 31 August 1989 sampling activities.
2.2.7.4.1 Site 26 Engineering Evaluation and Cost Analysis Several field investigations were conducted at Site 26 between 1996 and 2002, with the results summarized in the Final EE/CA for IRP Site 26/Firefighter Training Area-2 (FWENC and EA 2003). These field activities included a site reconnaissance and DSI, soil
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-39 Andersen AFB, Guam January 2011
gas survey, EM geophysical survey, surface and subsurface soil sampling, and a topographic survey.
The site reconnaissance/DSI included a walkthrough to visually inspect mounds, areas of stressed vegetation, stained soil, or abrupt changes in vegetation. In conjunction with the visual inspection at Site 26, an EM geophysical survey was performed using appropriate geophysical instruments to locate potential buried waste. The EM induction survey identified a UST just to the north of the existing AST, after which Andersen AFB personnel were notified. The UST was added to the ongoing UST decommissioning program and removed from the site in January 1997 (Jacobs 1998).
In 1996, 55 whole-air active soil gas points were installed at the site to examine the horizontal and vertical extent of any soil contamination, with two of the 55 active soil gas points installed near the UST. Soil gas points were installed at a depth of approximately four ft bgs using a portable hydraulic auger. All soil gas samples were analyzed for VOCs using the onbase GC/MS. Additionally, three GoreSorbers (passive soil gas) were installed in the abandoned burn pit at a depth from 6.5 ft bgs to 10 ft bgs. After 15 days, the GoreSorbers were retrieved and submitted for analysis of VOCs (FWENC and EA 2003). Low concentrations of fuel and chlorinated VOCs were detected at locations scattered across the site.
In January 1996, 21 surface soil samples were collected from the abandoned burn pit, AST, oil/water separator, and their vicinity at a depth from 0 inches bgs to 3 inches bgs (Figure 15). Samples were analyzed for SVOCs, metals, dioxins, pesticides, and PCBs. Based on a recommendation from the EPA upon reviewing the 1996 surface soil sampling results, in April 2002, one 50-ft and two 25-ft boreholes were drilled in the abandoned burn pit to delineate potential subsurface contamination (Figure 15). Two subsurface soil samples were collected from one borehole at approximately 25 ft bgs and 50 ft bgs, with one subsurface soil sample collected from each of the remaining two boreholes at a depth of approximately 25 ft bgs. Samples were analyzed for VOCs, PAHs, pesticides, and PCBs.
On 21 January 1997, the UST was removed from Site 26 using a crane. The UST was a buried 35-ft-long tanker trailer containing approximately 3,000 gallons of a petroleum- solvent mixture (Jacobs 1998). This non-aqueous phase liquid was pumped to a container prior to removing the UST. The UST had no ancillary piping and was in good condition with very little rusting or pitting of the metal. The age and history of the UST are unknown. The excavation pit had a weathered solvent/hydrocarbon odor, and stained soils were observed beneath the UST (FWENC and EA 2003). A grab sample was collected from the tank liquid and the sludge contained in the UST, and it was analyzed for waste profiling purposes. Elevated concentrations of VOCs were detected in the liquid sample. The sludge sample collected from the UST contained concentrations of arsenic, chromium, cadmium, lead, and total halogens indicating that the sludge should be considered hazardous waste (FWENC and EA 2003). As a result, the sludge was removed from the UST and disposed of off-island (Jacobs 1998).
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-40 Andersen AFB, Guam January 2011 ABANDONED ABOVEGROUND STORAGE TANK (EMPTY)
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SURFACE SOIL SAMPLE + LOCATION N SUBSURFACE SAMPLING 100' 0 100' + LOCATION rv--v-.. FOREST ------SCALE IN FEET
Figure 15 Site 26 Sampling Locations Record of Decision for IRP Sites 10, 13, 15, 26, and 27 Andersen AFB, Guam
After the removal of the UST, five soil samples were collected from the excavation pit at approximately 2 ft below the UST bottom (about 10 ft bgs) (Figure 15). These soil samples were analyzed for TPH-gasoline range organics (GRO), TPH-DRO, VOCs, pesticides, PCBs, and metals (Jacobs 1998). Elevated concentrations of TPH and VOCs typical of fuel hydrocarbons were detected in the soil samples. Subsequently, the excavation pit was backfilled using a blend of excavated soils, imported fill, and nitrogen-rich fertilizer at a minimum rate of 1/2 pound per cubic yard of backfilled soil. The fertilizer was added to the backfill soil to enhance the natural biodegradation of residual hydrocarbons in the excavated pit (Jacobs 1998).
After the removal of the UST, two shallow boreholes were drilled at the former UST location (Figure 15) to approximately 20 ft bgs and 50 ft bgs, respectively, and limestone (rock) core samples were collected at 10-ft intervals. All core samples were analyzed for TPH-GRO, TPH-DRO, VOCs, pesticides, PCBs, and metals (Jacobs 1998). Because of elevated concentrations of these analytes at depth in the boreholes, the vertical extent of the impacted area at the former location of the UST remained a concern for the Site. Four additional deep boreholes were subsequently drilled to define the extent of the impacted areas at Site 26.
Between February and March 1998, three 6-inch-diameter boreholes were drilled immediately outside the former tank pit (Figure 15) to total depths of approximately 405 ft bgs, 302 ft bgs, and 191 ft bgs, respectively. Limestone core samples were collected at 10-ft intervals from 20 ft bgs to 100 ft bgs and then at approximate 20-ft intervals below 100 ft bgs. Elevated concentrations of several VOCs, TPH-GRO, and TPH-DRO were detected in samples at depth. The PCB Aroclors 1254 and 1260 were also detected in several sample intervals in each soil boring location at depth.
Based on the elevated concentrations of VOCs and TPH in the subsurface, combined with the physical characteristics of the site, a soil vapor remedial system was installed at Site 26.
2.2.7.4.2 Site 26 Interim Removal Action In 1998, following the UST removal and identification of elevated concentrations of VOCs and TPH in soils beneath the former tank pit, three existing deep boreholes were converted into remedial wells. The system was designed to operate as either a bioventing system or VES, depending on the results of the pilot test. Between August and April 1998, the remedial system was started up and all components were successfully tested and found to be operational (Jacobs 1998).
In November 1998, a pilot test was conducted at the former location of the UST to assess the effectiveness of the bioventing system and VES for long-term operation at the site. The test concluded that site characteristics met the requirements of both remedial options. The USAF selected VES to help mitigate the downward migration of VOCs to groundwater. The VES system was operated from December 1998 to August 2001. During this time, the VOC removal rate was estimated at approximately 247 pounds per day (lbs/day) (Andersen AFB 2005). In August 2001, the VES system was shut down.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-43 Andersen AFB, Guam January 2011
In April 2002, four 8-inch-diameter boreholes were installed near the former UST to an approximate depth of 300 ft bgs to delineate the lateral and vertical extent of contamination. Three of the boreholes were located outside of the known area of impact and are intended for potential use as bioventing air monitoring points. The fourth borehole was located inside of the COPC plume for potential use as a bioventing air injection point (FWENC and EA 2003).
On 25 April 2002, the remedial system at the former UST area was converted to a bioventing system and all components were successfully tested and found to be operational. The bioventing system was operational from April 2002 until May 2004, during which time the VOC emission rate was estimated at 95 lbs/day (based upon samples collected between August 2002 and March 2003) (EA 2007).
In January 2004, a peer review evaluation of Site 26 concluded that the bioventing system, while capable of degrading fuel components, would not have any effect on chlorinated VOCs such as tetrachloroethylene (PCE). On 14 January 2005, the system was switched to the VES mode of operation, and eight rounds of vapor sampling were conducted between 15 February and 18 October 2005, at which time VOC emissions results ranged from 4.7 to 16.9 lbs/day. A noticeable drop in the VOC emission rate occurred since the initial operation of the system, decreasing from 247 lbs/day in July 2001 to 95 lbs/day in March 2003 to 16.9 lbs/day in October 2005. Closure of the system was agreed upon by the USAF, EPA, and GEPA in March 2007 as removal rates had reached asymptotic notation (EA 2007).
2.2.7.5 Site 27 Previous Investigations and Response Actions
The IRP Phase I Records Search (Reynolds et al. 1985) identified Site 27 as consisting of an outside storage area for petroleum, oil, lubricants and solvents, and later, for hazardous wastes. The report concluded that although no spills had been reported in this area, any spillage would run in a southerly direction toward three dry underground injection control wells. Based on the potential for contamination and contaminant migration, the site was evaluated using the HARM system. Site 27 was assigned a HARM score of 58 out of 100 possible points (ESE 1985). The report concluded that the need for further investigation at the site would be encompassed by an existing groundwater monitoring program, and that no other monitoring was recommended.
In the RFA Report (SAIC 1986), the area was identified as a RCRA-regulated unit that was taken out of service in 1983 but had not undergone a RCRA closure. As part of a proposed Closure Plan, Site 27 was used as an accumulation point for hazardous wastes found throughout the base during a hazardous waste remedial operation (EA 1999c). Three soil samples were collected and analyzed using the RCRA toxicity characteristic leaching procedure. The results confirmed that the soil samples were below levels for RCRA- regulated wastes, although lead and arsenic were identified as being above the MDLs. The plan stated that decontamination was not required.
2.2.7.5.1 Site 27 Engineering Evaluation and Cost Analysis A field investigation was conducted at Site 27 between April 1997 and July 1997 that included a visual site reconnaissance, DSI, soil gas survey, surface and subsurface soil sampling, and a topographic survey. Results of the EE/CA were documented in the Final Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-44 Andersen AFB, Guam January 2011
Decision Summary, No Further Response Action Planned (NFRAP) for IRP Site 27/Hazardous Waste Storage Area 1, dated April 1999 (USAF 1999).
Site reconnaissance was performed to document surface disposal and to locate the lateral boundaries of site operations. As a result, the site was expanded to include the former storage yard. A DSI was performed to document surface features within the site. All waste materials were described and located in the cell within 1-ft accuracy. Emphasis was particularly placed on evidence of potential staining on the asphalt pads and the location of cracks within the asphalt pad that might allow infiltration of potential spills.
A soil gas survey was conducted to evaluate the extent of VOCs in the subsurface soil and bedrock. A portable hydraulic auger was used to drill 2-inch-diameter holes to approximately four to eight ft bgs for installation of soil gas sampling points. A total of 32 of the 69 total samples contained reported concentrations of VOCs. These 32 samples contained PCE in concentrations ranging from 0.2 to 25.5 micrograms per liter (g/L). In addition, 10 of the 32 samples contained trichloroethylene in concentrations ranging from 0.1 to 5.0 g/L. Chloroform was detected in 1 of the 32 samples at a concentration of 0.1 g/L. The 32 soil gas samples with VOCs were all collected from the general area of the 3 ft-by-3 ft array of raised storage pads. The highest PCE concentrations were detected in soil gas points located slightly southeast of the center of the 3-ft by-3 ft array. In general, PCE was present at slightly higher concentrations in the deeper samples compared to shallower samples from the same area. PCE concentrations, regardless of depth, decreased toward the edges of the storage yard.
A total of 21 surface soil samples were collected at Site 27 (Figure 16) and were analyzed for SVOCs, PAHs, and metals. Shallow subsurface soil samples were also collected, using a hand-auger. The number of subsurface soil samples collected was limited (five from three locations) since depth to bedrock was less than 2 ft in most locations. Shallow subsurface soil samples were collected in locations adjacent to soil gas points where bedrock was not encountered during point installation and low concentrations of VOCs were reported. Subsurface soil samples were analyzed for VOCs, SVOCs, PAHs, and metals.
Three PAH compounds were detected in surface soil samples at concentrations above their respective residential 1997 PRGs: benzo(b)fluoranthene (one sample), dibenz(a,h)anthracene (one sample), and benzo(a)pyrene (five samples). While still in excess of PRGs, detected PAH concentrations were low, suggesting that their presence is a result of surface runoff from the asphalt pads. No metals were identified at levels above residential PRGs and BTVs.
Trace levels of VOCs, and no SVOCs or PAHs were detected in any of the shallow subsurface soil samples. Two samples containing detectable levels of PCE were collected at different depths from the same boring location. The PCE concentration in both samples was below the PRGs.
The metals aluminum, arsenic, chromium, cobalt, and iron were detected at concentrations above their residential PRGs and BTVs in one or more samples each. The concentration of arsenic also exceeded its industrial PRG. Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-45 Andersen AFB, Guam January 2011
Given the limited data available from soil gas and shallow subsurface soil sampling, three boreholes were drilled and sampled at the site to delineate the vertical extent of VOCs (Figure 16). Seven subsurface soil samples were collected from the three boreholes, which were drilled to a total depth between 30 ft bgs and 50 ft bgs using a rock coring bit to sample. The three boreholes were advanced within the area where PCE concentrations in soil gas were greatest. Core samples were collected at 10-ft intervals to borehole total depth and analyzed by the on-base GC/MS laboratory. A total of seven subsurface core samples were collected. None of the samples contained detectable VOC concentrations.
Based upon the results of the EE/CA, NFA was recommended in a Final No Further Response Action Planned (NFRAP) Decision Document for IRP Site 27/Hazardous Waste Storage Area 1 dated April 1999 (USAF 1999).
2.2.8 Enforcement Activities Andersen AFB was listed on the NPL on 14 October 1992. The enforcement activities for Andersen AFB were initiated when the USAF entered into a FFA with the EPA Region 9 and GEPA. The FFA, finalized on 30 March 1993, established a framework for performing detailed environmental investigations at Andersen AFB. The FFA was based upon applicable environmental laws including CERCLA, the Hazardous and Solid Waste Amendments, SARA, and the NCP.
2.3 Community Participation The NCP (40 CFR 300.430(f)(3)) establishes a number of public participation activities that the lead agency must conduct following preparation of the Proposed Plan (PP) and review by the support agency. Components of these items and documentation of how each component was satisfied for IRP Sites 10, 13, 15, 26, and 27 are described in Table 2-1 and Table 2-2.
Community involvement is an important component of the 36 ABW Environmental Restoration Program (ERP). Public participation has been encouraged throughout the decision process for environmental activities at Andersen AFB. Numerous documents have been made available in the AR to inform and update interested parties on the progress of the site investigations and response actions.
Information regarding the 36 ABW ERP is also provided through regular meetings of the Andersen AFB Restoration Advisory Board (RAB). The Andersen RAB was formed and held its first meeting in August 1994. The RAB meets quarterly to increase community awareness about the ER Program and elicit the public’s voice in environmental restoration issues at Andersen AFB. Information regarding environmental work at Andersen AFB is regularly made available through the RAB process.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-46 Andersen AFB, Guam January 2011 , l , \ Phlllpphe ~ \ Sea \ N \ \ 150 75 0 150 \ \ GRAPHIC SCALE IN FEET \ \ \ + \ \ + \ AFB \ \ \ LEGEND \ \ SURFACE SOIL \ + SAMPLE LOCATION \ SUBSURFACE SOIL \ SAMPLE LOCATION \ + \ BERM \ , ....__~~~~~~~~~~~....--...... ___. \ \ \ \ \ \ \ \ \
I I I I I I I I I I I I / I I / / I I ////
Figure 16 Site 27 Sampling Locations Record of Decision for IRP Sites 10, 13, 15, 26, and 27 Andersen AFB, Guam
Table 2-1: Public Notification of Document Availability Requirement: Satisfied by: Notice of availability of the PP and RI/FS must be made in a Notice of availability was published in the widely-read section of a major local newspaper. Guam Pacific Daily News newspaper on 4 May 2010. Notice of availability should occur at least two weeks prior to the Notice of availability was published on beginning of the public comment period. 4 May 2010. The public comment period began on 18 May 2010. Per the NCP (40 CFR 300.430(f)(3)(i)(A)), notice of availability Notice of availability included all of these must include a brief abstract of the PP, which describes the components. alternatives evaluated and identifies the preferred alternative. Notice of availability should consist of the following information: Site name and location Date and location of public meeting Identification of lead and support agencies Alternatives evaluated in the detailed analysis Identification of preferred alternative Request for public comments Public participation opportunities including: Location of information repositories and AR file Methods by which the public may submit written and oral comments, including a contact person Dates of public comment period Contact person for the community advisory group (e.g., Restoration Advisory Board) if applicable
Table 2-2: Public Comment Period Requirements Requirement: Satisfied by: Lead agency should make document available to public for review Document was made available to the public on same date as newspaper notification. on 18 May 2010. The notification of availability was made on 4 May 2010. Lead agency must ensure that all information that forms the basis Andersen AFB maintains the AR file for for selecting the response action is included as part of the AR file IRP Sites 10, 13, 15, 26, and 27. All data and made available to the public during the public comment collected and all CERCLA primary period. documents produced for IRP Sites 10, 13, 15, 26, and 27 are maintained as part of this file at the Nieves M. Flores Memorial Library in Hagatna, and the University of Guam RFK Library in Mangilao which are available to the public. CERCLA (40 CFR 307.177(a)(2)) requires the lead agency to The Navy provided a public comment provide the public with a reasonable opportunity to submit written period for the RI/FS and the PP from and oral comments on the PP. 18 May to 17 June 2010. The NCP (40 CFR 300.430(f)(3)(i)) requires the lead agency to allow the public a minimum of 30 days to comment on the RI/FS and the PP. The lead agency must extend the public comment period by at The Navy received no requests to extend least 30 additional days upon timely request. the public comment period.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-49 Andersen AFB, Guam January 2011
Requirement: Satisfied by: The lead agency must provide the opportunity for a public meeting A public meeting was held on 19 May 2010 to be held at or near the site during the public comment period. A at 6:30pm at the Guam Marriott Resort & transcript of this meeting must be made available to the public and Spa in Tumon. A transcript of this meeting be maintained in the AR for the site (pursuant to NCP [40 CFR has been added to the AR file. 300.430(f)(3)(i)(E)]).
Navy responses to comments received during the public comment period are introduced in Section 1.0 and provided in Appendix B.
2.4 Scope and Role of Operable Unit or Response Action The Navy is required by CERCLA to identify and investigate potential environmental contamination associated with its past military activities and to clean up contamination as necessary to protect human health and the environment. To meet CERCLA’s mandates, the Navy implemented an IRP in 1980 under which all eligible investigation and remedial activities were to be performed. IRP investigations at Andersen AFB were initiated in 1983 with a records search to identify potential sites of concern.
Andersen AFB elected to use an OU approach to manage the RIs under their IRP. As a result, this section describes the overall remedial strategy for the entire installation.
The USAF, with concurrence from the EPA and GEPA, has organized the IRP environmental restoration work at Andersen AFB within six OUs. According to the 1993 FFA, the OUs were formed to (1) expedite the completion of environmental activities, (2) evaluate sites with similar locations and potentially similar requirements as unique groups, (3) complete remedial design investigations at sites where closure decisions have been previously reached with the Government of Guam, and (4) provide a screening mechanism for evaluating newly or tentatively identified sites for inclusion in the RI/FS. Six OUs were initially established in the FFA; however, in 1996, the USAF, EPA, and GEPA agreed that to effectively respond to project property transfers, the criteria used to develop the original OUs were impractical (EA 2009).
The OUs were redesignated in 1996 with a focus on the need to group sites into geographically-distinct OUs that combined soil, potential contaminant sources, and groundwater: Harmon OU, Marianas Bonins Command OU, Main Base OU, Northwest Field OU, Uranao OU and Site-wide OU (EA 2009). The five IRP sites addressed in this ROD (Sites 10, 13, 15, 26, and 27) are all located within the Main Base OU. The Main Base OU addresses potential soil contamination at the IRP sites located within the Main Base.
The selected NFA decision in this document constitutes the planned final action for Sites 10, 13, 15, 26, and 27, and is protective of human health and the environment.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-50 Andersen AFB, Guam January 2011
2.5 Site Characteristics
2.5.1 Physiography and Climate The Mariana Islands are a complex geological island-seamount system forming the Mariana Archipelago. The island of Guam has two distinct physiographic provinces: the Northern Limestone Plateau and the Southern Volcanics, which are separated by the Adelup Fault. South of the fault, the island is composed almost entirely of volcanic rocks, and north of the fault the island is composed almost entirely of limestone (excluding portions of Mt. Santa Rosa and Mataguac Hill). Andersen AFB is situated on an undulating karst limestone plateau along the northernmost portion of the island.
Guam is located at 13° 27' north latitude (approximately 900 miles north of the equator), creating a year-round warm and humid climate. The mean annual temperature is 81 degrees Fahrenheit (°F). Daily temperatures range from the lower 70s to the upper 80s °F. Relative humidity ranges from 65 to 80 percent (%) in the afternoon and 85 to 100% in the evening. Guam has two distinct seasons: a wet season and a dry season. The dry season is typically from December to June, and the wet season occurs from July through November. Approximately 65% of the annual precipitation falls during these five rainy months, and the annual rainfall on northern Guam averages between 80 and 100 inches.
The dominant winds are the trade winds, blowing from the east or northeast with velocities between 4 and 12 miles per hour (mph) throughout the year. These winds are strongest during the dry season, averaging 15 to 25 mph, and calms are rare. During the wet season, the trade winds are still dominant but not constant. The winds can blow from any direction with wind speeds generally less than 15 mph, interspersed with frequent calms. Storms may occur at any time during the year, although tropical storms and typhoons are more frequent during the rainy season. Large rainfall events associated with typhoons are common with as much as 25 inches in a 24-hour period (Ward et al. 1965).
2.5.2 Geology The island of Guam has two distinct physiographic provinces, the Northern Plateau and the Southern Volcanics. The Adelup Fault separates these two provinces. North of the fault, the island is composed almost entirely (excluding portions of Mt. Santa Rosa and Mataguac Hill) of the Mariana and Barrigada Limestones, which are situated unconformably atop the fine-grained volcanic rocks of the Alutom Formation (Tracey et al. 1964) located at depth. Mt. Santa Rosa and Mataguac Hill represent isolated volcanic terrains belonging to the Alutom Formation.
The Pliocene-Pleistocene-aged Mariana Limestone consists of four distinct limestone facies: The reef facies is situated along the cliff-line and consists predominantly of fossil corals in growth with encrusting calcareous algae. It is white, massive, generally compact, and porous to cavernous (Tracey et al. 1964). The detrital facies is lagoonal in origin, and varies from friable to well-cemented, with variable grain sizes. It is also generally porous (Tracey et al. 1964). The molluscan facies consists of fine-grained limestone containing abundant casts and molds of mollusks (Tracey et al. 1964). The fore-reef facies consists of a well-bedded, friable to indurated limestone deposited as fore-reef sand and debris.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-51 Andersen AFB, Guam January 2011
The Miocene-aged Barrigada Limestone lies beneath the Mariana Limestone. The Barrigada Limestone is generally a deep-water deposit of medium- to coarse-grained texture and ranges from compact and well lithified to extremely friable. It is a principal water-bearing unit and contains abundant solution openings, voids, and fissures.
The Main base and Northwest Field are both located on the northern plateau of Guam with flat-laying limestone, gently rolling topography between 400 and 600 ft above mean sea level, and limited surface runoff. The thin soil and the limestone bedrock are very porous and permeable. Therefore, rainwater readily infiltrates downward preventing the formation of surface streams, rivers, and lakes (Stearns 1937, Mink 1976).
2.5.3 Hydrogeology Groundwater on northern Guam occurs as a freshwater lens, referred to as the Northern Guam Lens (NGL), and is encountered at depths varying from 230 ft bgs to 600 ft bgs. The EPA has designated the NGL as a sole-source aquifer (Barrett, Harris, & Associates 1982). The permeability and porosity of the Northern Plateau limestones are very high. As a result, there are no rivers or streams in northern Guam. All precipitation, except that portion lost to evapotranspiration, contributes to the groundwater. The recharge to the aquifer by precipitation averages 0.77 million gallons per day per square kilometer (Mink 1976).
The limestone aquifer of northern Guam have an average gradient of 0.00005 feet per foot, a hydraulic conductivity (K) of approximately 2,000 feet per day (ft/day), and a porosity of 10 to 15%. The K of the NGL varies four orders of magnitude from 2 ft/day to over 20,000 ft/day (Mink 1976). This extreme difference is a function of lithology and dissolution variation within the limestone.
In karstic limestones, permeability and porosity (and thus they hydrogeologic parameters) have three components: matrix permeability of the rock itself, the permeability produced by fractures (joints, faults and bedding planes), and the permeability due to solution conduits. Matrix hydraulic conductivities of more compact, or argillaceous limestones have been estimated to range from 1E-07 to 1E-09 ft/day, while younger, coarser limestones unimpacted by orogenic forces yielded estimates of 0.028 to 1E-04 ft/day (White 2007). In contrast, measurements of K within the fracture or solution channel components can range up to feet per second.
Based on analyses of several pump tests in Guam, Mink (1976) calculated average K values for the limestones on a regional scale, based upon lithology. On the low end are the more argillaceous units of the lagoonal facies possessing a value of 26 ft/day, with the higher value of K (190 ft/day) belonging to the “cleaner”, purer, and cavernous limestones of the fore reef facies, with values up to 20,000 ft/day in areas of significant karst formation.
The porosity of the limestone ranges from 15 to 25% (Mink 1976; URS 2003).
The important factors governing the volume of freshwater in the lens are (1) the effects of mixing freshwater and ocean water, (2) the permeability of the limestone formations, and (3) the rate of recharge (Ward et al. 1965). Regionally, the groundwater flow direction in the NGL is from the limestone/volcanic contacts toward the sea. Faults, fractures, brecciated zones, joints, solution channels, or cavities can affect flow and pumping wells. Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-52 Andersen AFB, Guam January 2011
2.5.4 Ecology Biology and ecology are important considerations in the Andersen AFB ERP. Most of the native terrestrial birds and mammals on Guam are considered threatened or endangered (DWAR 1994), and parts of Andersen AFB provide critical habitats for several of these species.
The currently known range of the Mariana crow (Corvus kubaryi) is centered on the Northwest Field of Andersen AFB and extends along the cliff-line adjacent to the North Field (ICF 1994).
The only native mammals on Guam are bats. The Mariana fruit bat (Pteropus mariannus) is listed as endangered by either the Government of Guam or by the U.S. Fish and Wildlife Service (USFWS) (Guam DAWR 1997), and is found among several roosts along the cliff- line near Pati Point, along the northeast shoreline of the North Field of Andersen AFB.
One species of tree, the hayan lagu (Senanthes nelsoni), has been listed as an endangered species by the USFWS. In addition, a second species of tree, ufa-halomtano (Hentlera Iongipetiolata), is listed by the Government of Guam as endangered (Guam DAWR 1997). The known distribution of both hayan lagu and ufa-halomtano is along the cliff-line adjacent to the North and Northwest Fields of Andersen AFB.
Four major habitat types are located within Site 10: (1) Second-growth Limestone Forest, (2) Mixed Shrub Vegetation/Second-growth Limestone Forest, (3) Tangantangan Forest, and (4) Active Base. Approximately 80% of Site 10 consists of Tangantangan forest, 10% Second-growth Limestone Forest, 8% Mixed Shrub Vegetation/Second-growth Limestone Forest, and 2% Active Base. The entire site is considered a cultural and archeological site, and portions of it are used for recreational purposes such as archery.
Site 13 is generally comprised of a limestone forest with sparse to heavy undergrowth beneath a canopy of taller, emergent trees. Although there are several threatened and endangered species of flora and fauna on Andersen AFB, no known endangered or threatened species were observed at Site 13.
Site 15 is approximately 10 acres in size, approximately 4 acres of which are fill material. Approximately 18% of the site consists of mixed herbaceous vegetation, 48% consists of Tangantangan forest, and the remaining 34% of habitat within the site boundary and surrounding the site consists of Second-growth Limestone Forest. Two notable species of trees identified in the limestone forest habitats surrounding Site 15, but not on the site, were Tabernaemontana rotensis, a rare, native tree species proposed for listing on the Guam Endangered Species List, and Ufa-halomtano (Heritiera longipetiolata), a tree that is considered “rare and endangered” on Guam.
Much of Site 26 consists of maintained grass, with limited habitat value. However, areas of Mixed Shrub Forest and Mixed Herbaceous Vegetation can be found in the south and east. Several animal species have been identified as living within the boundary of Site 26. During site visits, geckos, skinks, and brown tree snakes were encountered.
Although there are several threatened and endangered species within Andersen AFB, none of the critical habitats for these species is located at or near Site 27. The only animals Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-53 Andersen AFB, Guam January 2011
encountered during site visits were a number of small shrews that live in the sparse vegetation growing in the sediment of the drainage channels. The entire site is a disturbed ground habitat. The property has either been developed with asphalt or has maintained grass.
2.5.5 Nature and Extent of Contamination
2.5.5.1 Site 10 Nature and Extent of Contamination Following the soil removal action, the remaining potential human health and ecological risks posed by Site 10 were reevaluated which took into account updated toxicity factors and screening levels. This risk evaluation was performed as part of the Final Remedial Investigation Report, IRP Sites 03, 10, 13, 15, 21, 26, and 27, Andersen Air Force Base, Guam (AECOM 2010). The results of this risk evaluation are described below.
Risk-based screening of post-removal soil analytical results indicated that four PAH compounds were detected at levels above their respective residential regional screening levels (RSLs): benzo(a)anthracene (two samples), benzo(a)pyrene (nine samples), benzo(b)fluoranthene (three samples), and dibenz(a,h)anthracene (one sample). Benzo(a)pyrene exceeded its industrial RSL in one sample, with a concentration of 450 micrograms per kilogram. The location of the PAH exceedances were scattered across the landfill with no identifiable hot spot. All but one exceedance came from surface soils. Manganese exceeded its respective RSL and BTV in two surface soil samples from the southern half of the site (Figure 17).
2.5.5.2 Site 13 Nature and Extent of Contamination Based upon the results of the HHRA, the EE/CA recommended further action for surface soils. Four remedial alternatives were evaluated: 1) No Action; 2) Institutional Controls; 3) Installation of a Soil Cover; and 4) Surface Soil Removal. Alternative 4 was recommended.
However, the potential human health and ecological risks posed by Site 13 were reevaluated which took into account updated toxicity factors and screening levels. This risk evaluation was performed as part of the Final Remedial Investigation Report, IRP Sites 03, 10, 13, 15, 21, 26, and 27, Andersen Air Force Base, Guam (AECOM 2010). The results of this risk evaluation are described below.
Surface Soil
Fourteen surface soil samples from the Original Site (Figure 18) and nine surface soil samples from the Expansion Site (Figure 19) contained one or more of the following PAH compounds at concentrations above their residential RSLs: benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, dibenz(a,h)anthracene, and indeno(1,2,3-cd)pyrene.
In general, soil samples with PAH exceedances at the Original Site were collected from an area toward the bottom of the steep slope in the northwest corner, near accumulations of deteriorating drums, some containing residual asphalt or tar, or near accumulations of asphalt. Similarly, at the Expansion Site, the soil samples containing elevated PAHs were collected from the southern or western portion near accumulations of tar/asphalt and/or deteriorating 55-gallon drums of asphalt/tar.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-54 Andersen AFB, Guam January 2011 L:\work\AFCEE\Guam\TO 0025 (60133951)\Reports\RI Report\5 Working Final\RI Figures\Fig17.pdf lmn 7/710 Soil SampleResults Above ScreeningLevels IRP Sites10, 13,15,26and27 Record ofDecision for Andersen AFB, Guam IRP Site10 Figure 17 Figure 18 Soil Sampling Results Above Screening Levels IRP Site 13 (Original Site) Record of Decision for IRP Sites 10, 13, 15, 26 and 27
L:\work\AFCEE\Guam\TO 0025 (60133951)\Reports\RI Report\5 Working Final\RI Figures\Fig18.pdf 0025 (60133951)\Reports\RI Report\5 Working L:\work\AFCEE\Guam\TO Main Base, Andersen AFB, Guam S-091 S-092 DDT 1.858
Figure 19 Soil Sampling Results Above Screening Levels IRP Site 13 (Expansion Site)
Record of Decision for
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In addition, Aroclor 1260 and DDT were detected in one surface soil sample each at the Expansion Site at concentrations above their respective RSLs.
At the Original Site, arsenic (6 samples), cobalt (7 samples), manganese (13 samples), and iron (3 samples) were identified at concentrations in excess of their residential RSLs and BTVs. Arsenic results also exceeded industrial RSLs. Thallium and cadmium were detected above screening levels in 1 sample each. With the exception of the sample that contained thallium and arsenic, all remaining exceedances for metals occurred in soil samples collected from the base of the slope and in the northeast corner of the Original Site, not from the areas of concentrated metal debris or deteriorated drums (Figure 18). The identification of thallium and cadmium in only 1 sample each above screening levels suggests limited impacts from these two metals in surface soil. At the Expansion Site, cobalt (three samples), iron (three samples), and lead (two samples) were detected at concentrations above both their residential RSLs and BTVs. Arsenic concentrations also exceeded industrial RSLs. Soil samples with elevated concentrations of these metals are limited to the western portion of the Expansion Site, but scattered, and not indicative of particular “hot spots.” Antimony, chromium, and manganese were identified in one sample each above their respective screening levels. The identification of antimony, chromium, and manganese in only one sample each above screening levels suggests limited impacts from these metals in surface soil. All metals exceedances except manganese came from soil samples collected from the western portion of the Site (Figure 19).
Subsurface Soil
Subsurface soil sample results indicated that five soil samples at the Original Site and two samples at the Expansion Site contained one or more of the aforementioned PAHs above EPA residential RSLs. Similar to the surface soils, most soil exceedances came from the steep slope in the northwest portion of the Original Site (Figure 18), and near the drum accumulations in the southern and western portions of the Expansion Site (Figure 19).
At the Original Site arsenic (three samples), cobalt (one sample), iron (two samples), and lead (two samples) exceeded their respective RSLs in subsurface soil samples at locations scattered across the site (Figure 18). The differences in metal concentrations between surface and subsurface soil at the Original Site are likely to be reflective of the heterogeneous nature of the material at the dump site.
Three of the 11 subsurface samples from the Expansion Site contained metals above screening levels, including arsenic and lead in 1 sample, chromium (2 samples), and iron (2 samples), at locations similar to the surface soil sample exceedances (Figure 19).
2.5.5.3 Site 15 Nature and Extent of Contamination Following completion of the soil removal action, the potential human health and ecological risks posed by Site 15 were reevaluated which took into account updated toxicity factors and screening levels. This risk evaluation was performed as part of the Final Remedial Investigation Report, IRP Sites 03, 10, 13, 15, 21, 26, and 27, Andersen Air Force Base, Guam (AECOM 2010). The results of the risk evaluation are described below.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-61 Andersen AFB, Guam January 2011
Risk-based screening of post-removal soil analytical results identified only the PAH compound benzo(a)pyrene in 10 surface and 3 subsurface soil samples above its residential RSL (Figure 20). Locations of exceedances occurred across the site and were not indicative of any hot spot.
2.5.5.4 Site 26 Nature and Extent of Contamination Following closure of the VES system, the potential human health and ecological risks posed by Site 26 were reevaluated which took into account updated toxicity factors and screening levels. This risk evaluation was performed as part of the Final Remedial Investigation Report, IRP Sites 03, 10, 13, 15, 21, 26, and 27, Andersen Air Force Base, Guam (AECOM 2010).
Results of risk-based screening indicate that five PAH compounds were detected at levels above their respective residential RSLs in one burn pit surface soil sample: benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, and indeno(1,2,3-cd)pyrene. Benzo(a)pyrene, benzo(b)fluoranthene, and benzo(a)anthracene also exceeded their respective industrial RSLs.
PCB Aroclor 1254 was detected in subsurface soil from the bottom of the UST excavation at a depth of 10 ft.
Dioxin TEQs for all surface soil samples collected from the abandoned burn pit also exceeded the residential RSL for TEQ.
2.5.5.5 Site 27 Nature and Extent of Contamination Based upon the results of the EE/CA, NFA was recommended in a Final No Further Response Action Planned (NFRAP) Decision Document for IRP Site 27/Hazardous Waste Storage Area 1 dated April 1999 (USAF 1999). However, a reevaluation of the potential human health and ecological risks, which takes into account updated toxicity factors and screening levels, was performed as part of the Final Remedial Investigation Report, IRP Sites 03, 10, 13, 15, 21, 26, and 27, Andersen Air Force Base, Guam (AECOM 2010). The results of the risk evaluation are described below.
Results of the risk-based screening indicate that three PAH compounds were detected at levels above their respective residential RSLs: benzo(a)pyrene (five samples), benzo(b)fluoranthene (one sample), and dibenz(a,h)anthracene (one sample) (Figure 21). Each of these exceedances occurred in shallow soil samples located away from the actual storage pads, and are likely reflective of asphalt run-off.
Aluminum (two samples), arsenic (one sample), chromium (one sample), and cobalt (one sample) were detected above their respective residential RSL values in subsurface soils, with arsenic values exceeding industrial RSLs. As these exceedances were only encountered in subsurface soils, and in light of the thin, immature soil cover, it is likely that these metals concentrations represent the upper range of naturally occurring values.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-62 Andersen AFB, Guam January 2011 L:\work\AFCEE\Guam\TO 0025 (60133951)\Reports\RI Report\5 Working Final\RI Figures\07Jul10_PDFs\Fig20.pdf 0025 (60133951)\Reports\RI Report\5 Working L:\work\AFCEE\Guam\TO Figure 20 Post-Removal Soil Sample Results Above Screening Levels at IRP Site 15 Record of Decision for IRP Sites 10, 13, 15, 26 and 27 Andersen AFB, Guam L:\work\AFCEE\Guam\TO 0025 (60133951)\Reports\RI Report\5 Working Final\RI Figures\07Jul10_PDFs\Fig21.pdf ,,, ...... / ,,, / ,,, / I ...... , , l/ ...... , , , ,, ...... , I ..... I ,,.... I I I -:/ I I I I / / / / / Results Above Screening Levels Locations at IRP Site 27 Record of Decision for IRP Sites 10, 13, 15, 26 and 27 Surface and Shallow Subsurface Soil Sample Fence ~ Form• Hydrant • :;:1 SOOll Fire -+: ,~, Line .a\$; .. 5003 <' \f=: __:_.(_ -+- + \ // Andersen AFB, Guam 501 .. '. S005 · '('\ •• ""'. 4f." \a. "":: ~ / '. -+- \ \ 1 _J,_/ \ ..... ·v:~ And_...n ~ •• Figure 21 /. Former 5008 \\ . \ Pa.rtcfl\'g SDl1'. .. ~ \"""' ... .. '}.\ \ Lot )!+- • \ Tank ,. \ II / . ,,,, \ \ . '\ . \ Farm "' / ·:. \ \\ (adapted from EA, 150 INORGANIC Non-Bold ORGANIC 19998) Bold B(a)F B(a)P + ~ 5002 . 75 GRAPHIC LEGEND 8'nzo RESIDENTIAL RESIDENTIAL FORMER CONCEN1RA CONCEN1RA110N SAMPLE SUBSURFACE SAMPLE SURFACE Benzo ANAL ANAL EXPANDED CENTER SWALE SCALE ~\\ N 0 YlES YTES \ (a) (b) IN LINE LOCATION LOCATION FENCE SOIL FEET mg/kg p)'l"ene fluaranthene µg/kg 110N STUDY RLSs RLSs DRAINAGE SOIL \ \ LINE \ EXCEEDS EXCEEDS AREA 150
2.6 Current and Potential Future Land and Resource Uses
2.6.1 Land Use
2.6.1.1 Site 10 Land Use The current land use of Site 10 is industrial and limited to occasional adult users and trespassers. The southeastern part of the site is secured with a locked gate. The northwestern part of the site is accessible by the ground maintenance road, which is restricted to military personnel only. Skeet Club activities at the skeet range (in the northwest portion of the site) bring people to the site twice a month (Works 1997). There are no worker activities presently at the site, and maintenance activities are limited to the extent that they represent less of an exposure than the occasional user/trespasser.
The Navy and USAF determine land use at Andersen AFB, which is updated every two years in the Base General Plan (BGP), and have the authority to determine the future anticipated land use of Site 10. The Navy has determined that the most likely future land use of Site 10 over the foreseeable future is to remain unchanged from current use. This determination is made considering the following assumptions:
The site is located approximately 1,000 ft south of the active flightline (Figure 4), which restricts current land use to commercial/industrial use.
According to the BGP, future use of the site is expected to remain unchanged (Alba 1997).
The site is located in an area of small cliffs and ridges that make it unsuitable for commercial/industrial use. Therefore, future construction activities are not expected to take place at the site.
The current land use of adjacent/surrounding land is industrial. The current use of adjacent/surrounding land is expected to remain the same over the foreseeable future.
The populations of concern (receptors) at the site include current and future occasional adult users/trespassers. There is also hunting of wild deer and pig in this area. Therefore, ingestion of deer and wild pig meat by adults and children is a pathway of concern at the site. Potential risks from ingestion of deer and wild pig meat have been evaluated on a base-wide basis, and all risks were found to be below the EPA’s risk targets of 1E–6 for cancer and HI equal to 1.0 for noncancer risks. These results are presented in the EE/CA report for IRP Site 16 (EA 1999b). Although any future residential development is not expected at this site, as a worst case scenario, residential adults and children are included in this assessment as populations of potential concern.
2.6.1.2 Site 13 Land Use The current land use of Site 13 is currently industrial. The Original Site represents a small former quarry with 35-ft to 40-ft vertical walls extending upward to the surrounding limestone plateau. The quarry is situated atop a steep slope consisting predominantly of loose gravel, large boulders intermixed with debris, and overgrown vegetation. Access to the
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-67 Andersen AFB, Guam January 2011
site is limited because of the difficult terrain. In contrast, the Expansion Site is situated atop the plateau within gently rolling terrain. Access is unrestricted.
The Navy has determined that the most likely future land use of Site 13 over the foreseeable future is to remain unchanged from current use. This determination is made considering the following assumptions as presented in the Draft Engineering Evaluation/Cost Analysis Report for IRP Site 13/Landfill 18, Andersen Air Force Base, Guam (URS 2003):
Site 13 and adjacent areas are not currently used for residential purposes due to the rugged topography, proximity to the MMS, and proximity to the Rifle and EOD Ranges.
Andersen AFB land reuse plans (BGP) exclude future residential reuse for IRP Site 13 and adjacent areas.
The current land use of adjacent/surrounding land is recreational and includes a firing range, hunting area, and an actively used beach area (Tarague Beach, approximately 3/4 mile south of the site; Figure 5). The current land use of adjacent/surrounding land is expected to remain the same over the foreseeable future.
Current receptors at Site 13 include the occasional user, trespasser, and the recreational hunter. Trespassers and hunters may walk through the area as well as maintenance workers who may work at the site on a limited basis. Future potential receptors include onsite resident adults and children, trespassers, and recreational hunters. Although there are no plans to develop the area for residential use, residential exposure was evaluated in the HHRA as a conservative measure.
2.6.1.3 Site 15 Land Use The current land use of Site 15 is industrial. The site is bounded by native dense limestone forest vegetation and is accessible using an unpaved access road from the golf course. Nearby facilities and residential populations include the Palm Tree Golf Course sanitary sewage lift station (Bldg. 1098) (1,000 ft east of the site) and the Robert’s Terrace residential housing area (2,000 ft northeast of the site) (Figure 6). The current use of adjacent/surrounding land is expected to remain the same over the foreseeable future.
Potential receptors at the site include occasional users/trespassers such as hunters as well as maintenance workers who may work at the site on a limited basis. There is limited hunting of deer and wild pigs in this area of Andersen AFB, as noted in the discussion on Site 10 previously. While there are no plans to develop this site for residential use at anytime in the future, risks to potential future residents were evaluated in the HHRA as a conservative measure.
2.6.1.4 Site 26 Land Use The current land use of Site 26 is industrial. The site is located in the northwest corner of the airfield flight line on the Main Base, and is bound to the north and west by Perimeter Road. Areas to the east and south are moderately-vegetated to densely-vegetated. Access to the site is controlled by a 7-ft-high concrete wall and a locked entrance gate. The nearest residents to
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-68 Andersen AFB, Guam January 2011
Site 26 live in Base housing on the other side of the flight line, approximately 1.4 miles to the south.
The site is located within the active flight line (Figure 7), which restricts current land use to commercial/industrial use.
The current land use of adjacent/surrounding land is industrial. The current use of adjacent/surrounding land is expected to remain the same over the foreseeable future.
Potential receptors to the impacted area at Site 26 are limited to the firefighters who may occasionally use the new firefighter training area, the U.S. Department of Agriculture (USDA) personnel who maintain the snake traps along the perimeter wall, and possible trespassers. Firefighters train approximately 2 to 4 days per year, and USDA personnel would be present for half of an hour every other week. Due to the site’s location along the flight line, as long as Andersen AFB is active, the site will continue to be a restricted area, and residential development prohibited. However, as a conservative measure, potential future residents were evaluated as part of the HHRA.
2.6.1.5 Site 27 Land Use The current land use of Site 27 is industrial. The former storage yard is not currently used on an active basis, although base personnel do conduct frequent operations at the site. These operations include the use of the onsite fire hydrant system for fire training activities, a water supply source from ongoing construction activities at the landfill, the maintenance of onsite power equipment related to a power line that runs through the site, and grass-mowing activities along the perimeter of the site.
The Navy has determined that the land use of Site 27 over the foreseeable future will be industrial. This determination is made considering the following assumptions:
The site is located in close proximity to the active flight line (Figure 8), which restricts current land use to commercial/industrial use.
The current land use of adjacent/surrounding land is industrial. The current use of adjacent/surrounding land is expected to remain the same over the foreseeable future.
However, as a conservative measure, potential future residents were evaluated as part of the HHRA.
2.6.2 Groundwater and Surface Water Uses Due to the highly porous limestone and permeable soils, no significant surface water bodies exist on the northern half of Guam. Rainwater readily infiltrates downward through the interconnected pore spaces of the vadose zone preventing the formation of surface streams, rivers, and lakes (Stearns 1937, Mink 1976).
Groundwater on northern Guam occurs as a freshwater lens, referred to as the NGL, and is encountered at approximately 400 to 600 ft bgs. The EPA has designated the NGL as a sole- source aquifer (Barrett, Harris, & Associates 1982). The important factors governing the volume of freshwater in the lens are (1) the effects of mixing freshwater and marine water, Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-69 Andersen AFB, Guam January 2011
(2) the permeability of the limestone formations, and (3) the rate of recharge (Ward et al. 1965). Faults, fractures, brecciated zones, joints, solution channels, or cavities can affect flow and pumping wells.
The NGL beneath Andersen AFB is subdivided into six subbasins. Areas of concern at the base overlie four of the six groundwater subbasins. Any contaminants are not expected to cross subbasin boundaries. Groundwater flow within each has been shown to flow radially outward toward the Pacific Ocean.
Andersen AFB utilizes ten deep groundwater wells, and pumps the water through a single treatment plant then on to an on-base reservoir prior to distribution. Potable water from this system is regulated through the Guam EPA, and Andersen AFB is in full compliance with Guam Safe Drinking Water Regulations (Kingston 2004).
2.7 Summary of Site Risks This section summarizes the human health and ecological risk assessments that have been performed at Sites 10, 13, 15, 26, and 27 as part of the 2010 RI. The results of the HHRA and ERA, exposure to COPCs in soil and soil gas at Sites 10, 13, 15, 26, and 27 do not pose an unacceptable risk to human health or the environment. Therefore, no CERCLA action is necessary for any of the five sites, and per the NCP (40 CFR 300.430 (e)(6)), NFA is being recommended.
2.7.1 Summary of Human Health Risk Assessment The HHRA estimates what risks the site poses if no action were taken. It provides the basis for taking action (if any) and identifies the contaminants and exposure pathways that need to be addressed by any remedial action. This section of the ROD summarizes the approaches used and the results of the baseline risk assessment for this site. Potential risks for both current and future site occupants are addressed.
2.7.1.1 Identification of Contaminants of Concern This section identifies those contaminants associated with unacceptable risk at the site and that are the basis for the proposed remedial action. Although other contaminants were detected at the site, these COCs are the primary risk-driving contaminants. The data used in this risk assessment was deemed to be of sufficient quality and quantity for its intended use. The detection frequency, range of detected concentrations, and the exposure point concentrations (EPCs) for contaminants and media of concern are presented in Table 2-3 grouped by environmental medium.
Human health risks were estimated for potential exposure to site COPCs at Sites 10, 13, 15, 26, and 27. COPCs were identified separately for each site and for the different exposure media (i.e., soil and soil gas) by a screening risk evaluation step. All usable chemical analytical results that were detected at least once in soil or soil gas were screened against health-protective concentrations/levels published by the EPA (EPA 2009) to determine which contaminants, if any, may pose a potential to cause adverse health effects. The contaminants with maximum concentrations below the screening criteria are considered to have little potential to cause adverse health effects and are not further evaluated. The
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-70 Andersen AFB, Guam January 2011
contaminants whose concentrations do exceed the screening criteria are considered to have the potential to cause adverse health effects and are further evaluated as COPCs.
In addition, because metals were detected in soil samples from all of the sites, maximum concentrations detected at each site were screened against published background concentrations. ICF published a study reporting calculated background concentrations (or BTVs) of metals found on Andersen AFB (ICF 1997). In addition, Andersen AFB published a study for the recalculation of a BTV for manganese in soil (Andersen AFB 2001). If the maximum concentration of a metal in soil at a site exceeded the EPA RSLs but was below background, it was not evaluated as a COPC and was considered to be naturally occurring.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-71 Andersen AFB, Guam January 2011
Table 2-3: Exposure Point Concentrations for COCs Detected at Sites 10, 13, 15, 26, and 27 Concentration Detected Dermal/Ingestion Exposure (mg/kg) Frequency of Point Concentration EPA 2008 RSL Media Contaminant of Concern a Min Max Detection (mg/kg) (Residential) Site 10 Surface Soil, Benzo(a)anthracene 0.0018 0.440 0.72 0.0683 0.15 Onsite – Direct Contact Benzo(a)pyrene 0.0023 0.450 0.73 0.0779 0.015 Benzo(b)fluoranthene 0.0024 0.460 0.70 0.0723 0.15 Dibenz(a,h)anthracene 0.0014 0.130 0.36 0.0112 0.015 Indeno(1,2,3-cd)pyrene 0.0016 0.374 0.65 0.0563 0.15 Lead 1.5 1,400 1.00 181.2 400 Surface Soil, Benzo(b)fluoranthene 0.0024 0.46 0.70 N/A 0.15 Onsite – Indirect Contact (volatilization) Subsurface Soil, Benzo(a)anthracene 0.0018 0.440 0.75 0.0448 0.15 Onsite – Direct Contact Benzo(a)pyrene 0.0023 0.450 0.73 0.0779 0.015 Benzo(b)fluoranthene 0.0024 0.460 0.74 0.0723 0.15 Dibenz(a,h)anthracene 0.0016 0.130 0.34 0.0519 0.015 Indeno(1,2,3-cd)pyrene 0.0012 0.374 0.60 0.05194 0.15 Lead 1.5 1,400 0.97 191.2 400 Subsurface Soil, Benzo(b)fluoranthene- 0.0024 0.46 0.74 N/A 0.15 Onsite – Indirect Contact (volatilization) Site 13 Surface Soil, Onsite –Direct Aroclor 1260 0.0040 0.2422 0.25 0.0158 0.22 Contact Benzo(a)anthracene 0.0018 0.535 0.31 0.0291 0.15 Benzo(a)pyrene 0.00006 0.5535 0.43 0.0742 0.015 Benzo(b)fluoranthene 0.0015 0.5318 0.43 0.0626 0.15 Dibenz(a,h)anthracene 0.0027 0.3888 0.43 0.104 0.015 Indeno(1,2,3-cd)pyrene 0.0013 1.116 0.24 0.0965 0.15 4,4’-DDT 0.0003 1.858 0.43 0.192 1.7 Antimony 0.16 100 0.93 5.068 (63)
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-72 Andersen AFB, Guam January 2011
Concentration Detected Dermal/Ingestion Exposure (mg/kg) Frequency of Point Concentration EPA 2008 RSL Media Contaminant of Concern a Min Max Detection (mg/kg) (Residential) Site 13 - Surface Soil, Arsenic 0.36 76.8 0.96 26.8 (62) Onsite – Direct Contact Cadmium 0.17 73.8 0.98 12 70 (cont’d) Chromium, total 4.6 1,200 1.00 331.3 (1,080) Cobalt 0.4 317 0.91 31.67 (29) Copper 1.7 3,490 1.00 345.1 3,100 Iron 38.1 477,000 1.00 68,640 (116,495) Lead 2.9 5,110 1.00 561.7 400 Manganese 0.05 3,710 1.00 3,723 (5,500) Mercury 0.02 110.6 0.98 7.621 6.7 Thallium 0.11 6.4 0.83 1.167 5.1 Surface Soil, Benzo(b)fluoranthene- 0.0015 0.5318 0.43 N/A 0.15 Onsite – Indirect Contact (volatilization) Subsurface Soil, Onsite – Aroclor 1260 0.0040 0.2422 0.23 0.0152 0.22 Direct Contact Benzo(a)anthracene 0.0018 0.535 0.32 0.0318 0.15 Benzo(a)pyrene 0.00006 0.6627 0.43 0.0876 0.015 Benzo(b)fluoranthene 0.0015 0.570 0.42 0.0714 0.15 Dibenz(a,h)anthracene 0.0027 0.3888 0.07 0.0193 0.015 Indeno(1,2,3-cd)pyrene 0.0013 1.678 0.25 0.1222 0.15 4,4’-DDT 0.0003 1.858 0.41 0.1619 1.7 Antimony 0.16 100 0.92 4.66 (63) Arsenic 0.36 321 0.96 38.04 (62) Cadmium 0.17 73.8 0.96 10.97 70 Chromium, total 2.5 1,610 1.00 367.9 (1,080) Cobalt 0.4 317 0.92 29.08 (29) Copper 1.7 3,490 0.99 228 3,100 Iron 38.1 477,000 1.00 71,028 (116,495) Lead 1.8 5,110 1.00 486.1 400 Manganese 0.05 27,400 1.00 3,267 (5,500)
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-73 Andersen AFB, Guam January 2011
Concentration Detected Dermal/Ingestion Exposure (mg/kg) Frequency of Point Concentration EPA 2008 RSL Media Contaminant of Concern a Min Max Detection (mg/kg) (Residential) Site 13 - Subsurface Soil, Mercury 0.02 110.6 0.97 6.549 6.7 Onsite – Direct Contact Thallium 0.11 6.4 0.84 1.156 5.1 (cont’d) Subsurface Soil, Benzo(b)fluoranthene 0.0015 0.57 0.42 N/A 0.15 Onsite – Indirect Contact (volatilization) Site 15 Surface Soil, Onsite –Direct Benzo(a)pyrene 0.011 0.0576 0.13 0.05321 0.015 Contact Subsurface Soil, Onsite – Aroclor 1254 0.0161 0.0861 0.08 0.02466 0.22 Direct Contact Benzo(a)pyrene 0.0022 0.140 0.25 0.02805 0.015 α-chlordane 0.00047 2.3 0.71 0.501 1.6 Dieldrin 0.00079 0.140 0.37 0.01739 0.03 γ-chlordane 0.00049 1.7 0.80 0.688 1.6 Heptachlor epoxide 0.00058 0.39 0.32 0.04859 0.053 p-p’-DDE 2E–06 2,000 0.83 0.3219 1.4 Subsurface Soil, Onsite – α-chlordane 0.00047 2.3 0.71 N/A 1.6 Indirect Contact Dieldrin 0.00079 0.140 0.37 N/A 0.03 (volatilization) γ -chlordane 0.00049 1.7 0.80 N/A 1.6 p-p’-DDE 2E–06 2,000 0.83 N/A 1.4 Site 26 Surface Soil, Onsite –Direct Dioxins, total PCDD 1.7E–06 6.3E–05 1.00 4.08E–05 0.0045 Contact Benzo(a)anthracene 2.5 2.5 0.06 2.5 0.15 Benzo(a)pyrene 4.6 4.6 0.06 4.6 0.015 Benzo(b)fluoranthene 7.2 7.2 0.06 7.2 0.15 Benzo(k)fluoranthene 2.3 2.3 0.06 2.3 1.5 Indeno(1,2,3-cd)pyrene 1.6 1.6 0.06 1.6 0.15
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-74 Andersen AFB, Guam January 2011
Concentration Detected Dermal/Ingestion Exposure (mg/kg) Frequency of Point Concentration EPA 2008 RSL Media Contaminant of Concern a Min Max Detection (mg/kg) (Residential) Site 26 - Surface Soil, Ethylbenzene 12 12 0.25 12 5.7 Onsite – Direct Contact Lead 0.66 82.8 0.62 29 400 (cont’d) Subsurface Soil, Onsite – Aroclor 1254 0.0161 0.0861 0.08 0.02466 0.22 Direct Contact Dioxins, total PCDD 1.7E–06 6.3E–05 1.00 4.08E–05 0.0045 Benzo(a)anthracene 2.5 2.5 0.06 2.5 0.15 Benzo(a)pyrene 4.6 4.6 0.06 4.6 0.015 Benzo(b)fluoranthene 7.2 7.2 0.06 7.2 0.15 Benzo(k)fluoranthene 2.3 2.3 0.06 2.3 1.5 Indeno(1,2,3-cd)pyrene 1.6 1.6 0.06 1.6 0.15 Ethylbenzene 12 12 0.20 12 5.7 Tetrachloroethene 0.00389 28 0.83 25.4 0.57 Lead 0.66 1,450 0.66 348.6 400 Soil Vapor (mg/m3) Tetrachloroethene 0.1 3.9 0.29 N/A Site 27 Surface Soil Onsite –Direct Benzo(a)pyrene 0.0026 0.052 0.35 0.01872 0.015 Contact Benzo(b)fluoranthene 0.0025 0.190 0.60 0.05027 0.15 Dibenz(a,h)anthracene 0.0032 0.028 0.10 0.01511 0.015 Aluminum 142 114,000 0.95 44,827 (173,500) Arsenic 0.3 51.3 0.95 21.76 (62) Chromium, total 3.6 462 1.00 192.2 (1,080) Cobalt 1.3 15.9 0.35 4.09 (29) Iron 49.8 75,300 1.00 21,227 (116,495) Manganese 0.68 4,010 1.00 1,082 (5,500) Subsurface Soil Onsite – Benzo(a)pyrene 0.0026 0.052 0.35 0.01872 0.015 Direct Contact Benzo(b)fluoranthene 0.0025 0.190 0.60 0.04844 0.15 Dibenz(a,h)anthracene 0.0032 0.028 0.10 0.01511 0.015 Aluminum 142 248,000 0.96 112,886 (173,500) Arsenic 0.3 201 0.96 58.37 (62) Chromium, total 3.6 1,320 1.00 584.4 (1,080) Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-75 Andersen AFB, Guam January 2011
Concentration Detected Dermal/Ingestion Exposure (mg/kg) Frequency of Point Concentration EPA 2008 RSL Media Contaminant of Concern a Min Max Detection (mg/kg) (Residential) Subsurface Soil Onsite – Cobalt 1.3 29.6 0.48 8.87 (29) Direct Contact (cont’d) Iron 49.8 147,000 1.00 51,912 (166,495) Manganese 0.68 4,010 1.00 1,469 (5,500) Soil Vapor Chloroform 0.10 0.10 0.0167 N/A 0.11 3 (mg/m ) Tetrachloroethene 0.20 25.50 0.46 N/A 0.0004 Trichloroethene 0.20 5.00 0.13 N/A 1.2 Note: Values in parentheses represent background threshold values. mg/kg milligram per kilogram mg/m3 milligram per cubic meter a COCs evaluated for both direct soil contact and indirect (volatilization) at a site were listed twice, one for each route of exposure.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-76 Andersen AFB, Guam January 2011
2.7.1.2 Exposure Assessment This section documents the populations and exposure pathways that were quantitatively evaluated in the risk assessment. A conceptual site model (CSM) was developed to aid in determining reasonable exposure scenarios and pathways of concern; this CSM is shown on Figure 22. As described in this section, both current and future populations have been evaluated based on current and reasonably anticipated future land use. The contaminated media to which people may be exposed is also discussed.
A conceptual exposure model was developed to depict the potential relationship or exposure pathway between contaminant sources and receptors. An exposure pathway describes the means by which a receptor can be exposed to contaminants in environmental media.
The primary purpose of the CSM is to structure the HHRA to determine whether exposure pathways are incomplete (requiring no further evaluation) or potentially complete (i.e., possible). Only potentially complete exposure pathways are evaluated quantitatively in the risk assessment, which is consistent with EPA guidance (EPA 1989). A potentially complete exposure pathway must include all of the following elements before a quantitative assessment is performed:
Sources and type of contaminants present
Affected media (e.g., soil, soil gas)
Contaminant release and transport mechanisms (e.g., spills, volatilization)
Known and potential routes of exposure (e.g., ingestion, dermal contact, inhalation)
Known or potential human or environmental receptors (e.g., residents, workers, wildlife)
The absence of any one of these elements results in an incomplete exposure pathway. Thus, for an incomplete pathway with no potential human exposure, the potential for adverse health effects would be deemed negligible and would not warrant further evaluation. Figure 22 represents the CSM for current and anticipated future human and ecological receptors potentially exposed to COPCs in surface and subsurface soil and soil gas associated with Sites 10, 13, 15, 26, and 27.
2.7.1.2.1 Incomplete and Insignificant Exposure Pathways Of those exposure pathways that are presented in Figure 22, several have been deemed to be incomplete, insignificant, or not applicable. Thus, these pathways do not warrant quantitative assessment. The rationale for excluding a pathway from further evaluation is as follows:
Groundwater is located more than 250 ft bgs; therefore, incidental ingestion, dermal contact, and inhalation of vapors in ambient air from impacted groundwater are not evaluated.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-77 Andersen AFB, Guam January 2011
Inhalation of vapors in indoor air is considered an incomplete exposure pathway for current and future excavation/construction workers since they are generally in an outdoor environment.
Ingestion, dermal contact, and inhalation of vapors or particulates from surface water and sediment are considered to be incomplete pathways as the nearest source of surface water to all the sites is the Pacific Ocean, and Site 10 is the nearest site at a distance of approximately one-third mile.
2.7.1.2.2 Potentially Complete Exposure Pathways Based on analysis of the CSM, the following exposure pathways were considered for evaluation:
Incidental ingestion of contaminants in surface and subsurface soil by future residents (adults/children), current and future excavation/construction workers, and current and future occupational workers.
Dermal contact of contaminants from surface and subsurface soil by future residents (adults/children), current and future excavation/construction workers, and current and future occupational workers.
Inhalation of ambient air vapors and fugitive particulates from surface and subsurface soil by future residents (adults/children), current and future excavation/construction workers, and current and future occupational workers.
Inhalation of vapors in indoor air modeled from soil or as a result of soil gas migration by future residents and current and future occupational workers at Site 27. Evaluation may consider soil gas as the medium or indoor air.
2.7.1.2.3 Toxicity Assessment This section describes the carcinogenic and noncarcinogenic toxicity criteria used to calculate the potential risk for each COC. When available, these toxicity criteria are separated into ingestion, inhalation, and dermal routes of exposure. Also included is the source of the toxicity criteria and the primary health endpoint and organ of concern for each COC. Toxicity data for carcinogens is presented in Table 2-4 and Table 2-5 and for noncarcinogens in Table 2-6 and Table 2-7.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-78 Andersen AFB, Guam January 2011 Legend
Soil
Marianas Limestone
bgs Below Ground Surface ig22_CSM IRP Site3.ai ig22_CSM IRP
Inhalation of Incidental ingestion soil particulates dermal contact, inhalation of particulates Incidental ingestion dermal contact, inhalation of Inhalation of particulates soil vapor
debris and soil
Leaching to groundwater*
Note: Depth to groundwater 300 feet bgs *Groundwater is being addressed on a base-wide approach, and is not included here. L:\work\AFCEE\Guam\TO 0025 (60133951)\Reports\PP ROD\Records of Decision\01-NFA ROD Sites 10,13,15,26 & 27\1 IP Draft\Figures\F 10,13,15,26 & 27\1 IP ROD Sites of Decision\01-NFA ROD\Records 0025 (60133951)\Reports\PP L:\work\AFCEE\Guam\TO Figure 22 Generalized Conceptual Site Model Record of Decision for IRP Sites 10, 13, 15, 26 and 27 Andersen AFB, Guam
Table 2-4: Carcinogenic Toxicity Information for the Ingestion, Dermal Pathway Cancer Slope Factors (mg/kg-day) Weight of Evidence/ Cancer Guideline Contaminant of Concern Oral Dermal Description Source Date 4,4’-DDT 3.40E–01 3.40E–01 B2 IRIS 2008 p-p’-DDE 3.40E–01 6.8E–01 B2 IRIS 2008 α-chlordane 3.50E–01 7.00E–01 B2 IRIS 2008 γ -chlordane 3.50E–01 3.50E–01 B2 IRIS 2008 Aroclor 1254 2.00E+00 2.00E+00 B2 IRIS 2008 Aroclor 1260 2.00E+00 2.00E+00 B2 IRIS 2008 Arsenic a 1.50E+00 1.50E+00 A IRIS 2008 Benzo(a)anthracene 7.30E–01 7.30E–01 B2 NCEA/PRG b 2008 Benzo(a)pyrene 7.30+00 7.30+00 B2 IRIS 2008 Benzo(b)fluoranthene 7.30E–01 7.30E–01 B2 NCEA/PRG b 2008 Dibenz(a,h)anthracene 7.30E+00 7.30E+00 B2 NCEA/PRG b 2008 Indeno(1,2,3-cd)pyrene 7.30E–01 7.30E–01 B2 NCEA/PRG b 2008 Dieldrin 1.60E+01 3.2E+01 B2 IRIS 2008 Dioxins, total PCDD c 1.30E+05 1.30E+05 — Cal/EPA/PRG b 2008 Ethylbenzene 1.10E–02 1.10E–02 D Cal/EPA/PRG b 2008 Heptachlor epoxide 9.10E+00 1.82E+01 B2 IRIS 2008 Tetrachloroethene 5.40E–01 5.40E–01 — Cal/EPA/PRG b 2008 Cal/EPA California Environmental Protection Agency IRIS Integrated Risk Information System mg/kg-day milligram per kilogram per day NCEA National Center for Environmental Assessment EPA Weight of Evidence Classification: Chemicals and other agents in the environment assessed by the EPA are classified into five groups based upon scientific evidence of carcinogenicity. Group A = Human carcinogen. Group B1 = Probable human carcinogen; limited evidence is not conclusive. Group B2 = Probable human carcinogen; inadequate evidence is not conclusive. Group C = Possible human carcinogen; limited evidence that it causes cancer in animals, but no human data is available. Group D = Not classifiable as to human carcinogenicity. a Values listed are for inorganic arsenic. b Value was obtained from the Region 9 RSLs (2009). These values are still considered provisional. c Values listed are for 2,3,7,8-Tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD).
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Table 2-5: Carcinogenic Toxicity Information for the Inhalation Pathway Inhalation Cancer Contaminant of Slope Factor Weight of Evidence/Cancer Concern (mg/kg-day) Guideline Description Source Date p-p’-DDT 3.4E–01 B2 IRIS 2008 α-chlordane 3.50E–01 B2 IRIS 2008 γ -chlordane 3.50E–01 B2 IRIS 2008 Arsenic a 1.51E+01 A IRIS 2008 Benzo(b)fluoranthene 3.85E–01 B2 NCEA/PRG b 2008 Cadmium c 6.30E+00 B1 IRIS 2008 Chloroform 8.05E–02 A IRIS 2008 Chromium 4.20E+01 B2 IRIS 2008 Cobalt 3.15E+01 C IRIS 2008 Dieldrin 1.61E+00 B2 Cal/EPA/PRG b 2008 Tetrachloroethene 2.07E–02 — Cal/EPA/PRG b 2008 Trichloroethene 7.00E–03 — Cal/EPA/PRG b 2008 Cal/EPA California Environmental Protection Agency IRIS Integrated Risk Information System mg/kg-day milligram per kilogram per day NCEA National Center for Environmental Assessment EPA Weight of Evidence Classification: Chemicals and other agents in the environment assessed by the EPA are classified into five groups based upon scientific evidence of carcinogenicity. Group A = Human carcinogen. Group B1 = Probable human carcinogen; limited evidence is not conclusive. Group B2 = Probable human carcinogen; inadequate evidence is not conclusive. Group C = Possible human carcinogen; limited evidence that it causes cancer in animals, but no human data is available. Group D = Not classifiable as to human carcinogenicity. a Values listed are for inorganic arsenic. b Value was obtained from the Region 9 RSLs (2009). These values are still considered provisional. c Value listed is the oral RfD for food. IRIS also lists an oral RfD of 5.0E–04 for water.
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Table 2-6: Non-Cancer Toxicity Information for the Ingestion, Dermal Pathway Contaminant of Chronic/ Dermal Concern Subchronic Oral RfD RfD Primary Target Organ Source Date 4,4’-DDT Chronic 5.00E–04 5.00E–04 Alimentary Tract, Nervous, IRIS 2008 Reproductive α-chlordane Chronic 5.00E–04 2.5OE–04 Alimentary Tract, Immune, IRIS 2008 γ -chlordane Chronic 5.00E–04 2.5OE–04 Nervous IRIS 2008 Aluminum Chronic 1.00E+00 1.00E+00 Kidney, Nervous PPRTV/ 2008 PRG a Antimony Chronic 4.00E–04 6.00E–05 Cardiovascular, Eyes, IRIS 2008 Hematologic, Reproductive, Respiratory Aroclor 1254 Chronic 2.00E–05 2.00E–05 Alimentary Tract, IRIS/ 2008 Developmental, Endocrine, Eye, PRG Hematologic, Immune, Reproductive, Skin Arsenic b Chronic 3.00E–04 3.00E–04 Alimentary Tract, IRIS 2008 Cardiovascular, Developmental, Hematological, Nervous, Skin Cadmium Chronic 1.00E–03 2.50E–05 Kidney, Respiratory, Bone Loss IRIS 2008 Chloroform Chronic 1.00E–02 5.00E–03 Alimentary Tract, IRIS 2008 Developmental, Kidney Chromium Chronic 3.00E–03 3.90E–05 Hematologic, Respiratory, Skin, IRIS 2008 Reproductive (Cr VI only) Cobalt Chronic 3.00E–04 3.00E–04 Cardiovascular, Respiratory, PPRTV/ 2008 Skin, Hearing PRG a Copper Chronic 4.00E–02 4.00E–02 Alimentary Tract, Respiratory, PPRTV/ 2008 Skin PRG a Dieldrin Chronic 5.00E–05 2.50E–05 Alimentary Tract, Nervous IRIS 2008 Dioxins, total Chronic 1.00E–09 1.00E–09 Alimentary Tract, ATSDR/ 2008 PCDD Developmental, Endocrine, PRG a,c Hematologic, Immune, Reproductive, Respiratory, Skin Ethylbenzene Chronic 1.00E–01 1.00E–01 Alimentary Tract, IRIS 2008 Developmental, Endocrine, Kidney, Nervous, Reproductive, Skin Heptachlor Chronic 1.30E–05 6.5E–06 Alimentary Tract, Nervous IRIS 2008 epoxide Iron Chronic 7.00E–01 7.00E–01 Cardiovascular PPRTV/ 2008 EPA 2008 Lead Chronic — — Alimentary Tract, — 2008 Cardiovascular, Developmental, Hematologic, Immune, Kidney, Nervous, Reproductive Manganese Chronic 1.40E–01 1.40E–01 Nervous, Reproductive IRIS 2008 Mercury Chronic 3.00E–04 3.00E–04 Developmental, Immune, ORNL 2008 Kidney, Nervous Tetrachloroethene Chronic 1.00E–02 1.00E–02 Alimentary Tract, Kidney IRIS 2008
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Contaminant of Chronic/ Dermal Concern Subchronic Oral RfD RfD Primary Target Organ Source Date Thallium Chronic 6.50E–05 6.50E–05 Alimentary Tract, PRG 2008 Cardiovascular, Eye, Hematologic, Nervous, Reproductive Trichloroethene Chronic 3.00E–04 1.5E–04 Alimentary Tract, ORNL 2008 Developmental, Eye, Hematologic, Immune, Kidney, Nervous ATSDR Agency for Toxic Substances and Disease Registry Cal/EPA California Environmental Protection Agency IRIS Integrated Risk Information System mg/kg-day milligram per kilogram per day NCEA National Center for Environmental Assessment ORNL Oak Ridge National Laboratory RfD reference dose EPA Weight of Evidence Classification: Chemicals and other agents in the environment assessed by the EPA are classified into five groups based upon scientific evidence of carcinogenicity. Group A = Human carcinogen. Group B1 = Probable human carcinogen; limited evidence is not conclusive. Group B2 = Probable human carcinogen; inadequate evidence is not conclusive. Group C = Possible human carcinogen; limited evidence that it causes cancer in animals, but no human data is available. Group D = Not classifiable as to human carcinogenicity. a Value was obtained from the Region 9 RSLs (2009). These values are still considered provisional. b Values listed are for inorganic arsenic. c Values listed are for 2,3,7,8-Tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD).
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Table 2-7: Non-Cancer Toxicity Information for the Inhalation Pathway Inhalation Inhalation RfD Contaminant of Chronic/ RfC (mg/kg- Concern Subchronic (mg) day) Primary Target Organ Source Date α-chlordane Chronic 0.0007 2.00E–04 Alimentary Tract, Immune, IRIS 2008 γ -chlordane Chronic 0.0007 2.00E–04 Nervous IRIS 2008 Aluminum Chronic 0.0035 1.00E–03 Kidney, Nervous PPRTV/ 2008 PRG a Chloroform Chronic 0.098 2.80E–02 Alimentary Tract, ATSDR/ 2008 Developmental, Kidney PRG Chromium Chronic 1E–04 2.86E–05 Reproductive IRIS 2008 (Cr VI only), Hematologic, Respiratory, Skin Cobalt Chronic 6.86E–06 1.96E–06 Cardiovascular, Respiratory, PPRTV/ 2008 Skin, Hearing PRG a Ethylbenzene Chronic 1.00 2.86E–01 Alimentary Tract, IRIS 2008 Developmental, Endocrine, Kidney, Nervous, Reproductive, Skin Manganese Chronic 5.00E–05 1.43E–05 Nervous, Reproductive IRIS 2008 Mercury b Chronic 3.00E–04 8.57E–05 Developmental, Immune, IRIS 2008 Kidney, Nervous Tetrachloroethene Chronic 0.270 7.71E–02 Alimentary Tract, Kidney ATSDR/ 2008 PRG a Trichloroethene Chronic 0.0399 1.14E–02 Alimentary Tract, ORNL 2008 Developmental, Eye, Hematologic, Immune, Kidney, Nervous mg milligrams EPA Weight of Evidence Classification: Chemicals and other agents in the environment assessed by the EPA are classified into five groups based upon scientific evidence of carcinogenicity. Group A = Human carcinogen. Group B1 = Probable human carcinogen; limited evidence is not conclusive. Group B2 = Probable human carcinogen; inadequate evidence is not conclusive. Group C = Possible human carcinogen; limited evidence that it causes cancer in animals, but no human data is available. Group D = Not classifiable as to human carcinogenicity. a Value was obtained from the Region 9 RSLs (2009). These values are still considered provisional. b Value for mercuric sulfide was used as a surrogate because of its similar low bioavailability.
2.7.1.3 Risk Characterization This section of the risk assessment combines the results of the exposure assessment with the toxicity criteria identified for the COCs. Carcinogenic risks and noncarcinogenic impacts for each COC are presented for all populations and media of interest, including both current and future land use settings. Cumulative risks for all relevant pathways and populations are also described. These risk calculations are summarized in Appendix C (Table C-1 through Table C-5). The results of the HHRA are interpreted within the context of the CERCLA acceptable risk range (or state requirements, whichever is appropriate).
The major uncertainties affecting the risk assessment are also presented in this section, including uncertainties related to sampling and analysis, environmental fate and transport
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modeling, the use of default exposure assumptions, and those associated with the toxicity criteria.
For carcinogens, risks are generally expressed as the incremental probability of an individual’s likelihood of developing cancer over a lifetime as a result of exposure to the carcinogen. Excess lifetime cancer risk is calculated from the following equation:
Risk = CDI x SF
Where: Risk = a unitless probability (e.g., 2 x 10-5 or 2E–05) of an individual’s likelihood of developing cancer CDI = chronic daily intake averaged over 70 years (mg/kg per day [mg/kg-day]) SF = slope factor, expressed as (mg/kg-day)-1
These risks are probabilities that usually are expressed in scientific notation (e.g., 1E–06). An excess lifetime cancer risk of 1E–06 indicates that an individual experiencing the reasonable maximum exposure (RME) estimate has a 1 in 1,000,000 chance of developing cancer as a result of site-related exposure. This is referred to as an “excess lifetime cancer risk” because it would be in addition to the risks of cancer individuals face from other causes such as smoking or exposure to too much sun. The chance of an individual’s developing cancer from all other causes has been estimated to be as high as one in three. EPA’s generally acceptable risk range for site-related exposure is 1E–04 to 1E–06.
The potential for noncarcinogenic effects is evaluated by comparing an exposure level over a specified time period (e.g., life-time) with a reference dose (RfD) derived for a similar exposure period. An RfD represents a daily individual intake that an individual may be exposed to that is not expected to cause any deleterious effect. The ratio of site-related daily intake to the RfD is called a hazard quotient (HQ).
The HQ is calculated as follows:
Non-cancer HQ = CDI/RfD
Where: CDI = chronic daily intake RfD = reference dose
CDI and RfD are expressed in the same units and represent the same exposure period (i.e., chronic, subchronic, or short-term).
An HQ < 1 indicates that a receptor’s dose of a single contaminant is less than the RfD, and that toxic noncarcinogenic effects from that contaminant are unlikely.
The HI is generated by adding the HQs for all COCs at a site that affect the same target orga0n (e.g., liver) or that act through the same mechanism of action within a medium or across all media to which an individual may reasonably be exposed. An HI < 1 indicates that Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-86 Andersen AFB, Guam January 2011
adverse effects are unlikely from additive exposure to site contaminants. An HI > 1 indicates that site-related exposures may present a risk to human health.
2.7.1.3.1 Site 10 Risk Characterization Future Resident. Under the RME scenario, the potential incremental lifetime cancer risk (ILCR) for residents from all carcinogenic COPCs in surface soil (0–2 ft bgs) is 2E–06 and in subsurface soil (0-10 ft bgs) is 1E–06 (Table 2-8). The potential ILCRs are within the EPA target cancer risk range of 1E–06 to 1E–04. These risks are driven by direct exposure to soil with ingestion of soil (approximately 71%) being the main exposure pathway, while dermal absorption provides approximately 29% of the risk. Individual contaminant contributions are detailed in Table C-1 of Appendix C.
Because of a lack of non-carcinogenic toxicity values (e.g., RfD) for any of the COPCs carried through the risk assessment, the HI under the RME scenario, for potential non- carcinogenic health effects, in surface and subsurface soil, could not be calculated. However, because the cancer risk is at the low end of the EPA target risk range, it is likely that the potential for any adverse health effects is low.
Calculated blood lead levels for all receptors were below the California Environmental Protection Agency (Cal/EPA) recommended threshold of 10 microgram per deciliter (µg/dL).
Current and Future Excavation/Construction Worker. Under the RME scenario, the potential ILCR for excavation/construction workers from all carcinogenic COPCs in surface soil (0–2 ft bgs) is 5E–07 and in subsurface soil (0–10 ft bgs) is 4E–07 (Table 2-8). The potential ILCRs are below the EPA target cancer risk range of 1E–06 to 1E–04. Individual contaminant contributions are detailed in Table C-1 of Appendix C.
Because of a lack of non-carcinogenic toxicity values (e.g., RfD) for any of the COPCs carried through the risk assessment, the HI under the RME scenario for potential non- carcinogenic health effects in surface and subsurface soil could not be calculated. However, because the cancer risk is at the low end of the EPA target risk range, it is likely that the potential for any adverse health effects is low.
Occupational Worker. Under the RME scenario, the potential ILCR for occupational workers from all carcinogenic COPCs in surface soil (0–2 ft bgs) is 5E–07 and in subsurface soil (0–10 ft bgs) is 4E–07 (Table 2-8). The potential ILCRs are below the EPA target cancer risk range of 1E–06 to 1E–04. Individual contaminant contributions are detailed in Table C-1 of Appendix C.
Because of a lack of non-carcinogenic toxicity values (e.g., RfD) for any of the COPCs carried through the risk assessment, the HI under the RME scenario for potential non- carcinogenic health effects in surface and subsurface soil could not be calculated. However, because the cancer risk is at the low end of the EPA target risk range, it is likely that the potential for any adverse health effects is low.
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Table 2-8: Summary of Incremental Lifetime Cancer Risks and Cumulative Non-Cancer Hazard Indices at the Seven Sites on Andersen AFB ILCR HI Indoor Indoor Indoor Indoor Sub- Inhalation - Inhalation - Total - Total - Sub- Inhalation - Inhalation - Total - Total - Surface surface Surface Subsurface Surface Subsurface Surface surface Surface Subsurface Surface Subsurfac Receptor Soil Soil Soil Soil Soil Soil Soil Soil Soil Soil Soil e Soil Using Soil and Soil Gas to Model Indoor Inhalation Risks Site 10 Resident Adult 2E–06 1E–06 7E–10 6E–10 2E–06 1E–06 — — — — — — Child N/A N/A N/A N/A N/A N/A — — — — — — Excavation/ Construction 5E–07 4E–07 N/A N/A 5E–07 4E–07 — — N/A N/A — — Worker Occupational Worker 5E–07 4E–07 5E–11 5E–11 5E–07 4E–07 — — — — — — Site 13 Resident Adult 8E–05 1E–04 6E–10 7E–10 8E–05 1E–04 0.8 0.9 — — 0.8 a 0.9 a Child N/A N/A N/A N/A N/A N/A 7 8 — — 7 a 8 a Excavation/ Construction 2E–05 3E–05 N/A N/A 2E–05 3E–05 2 2 N/A N/A 2 a 2 a Worker Occupational Worker 2E–05 3E–05 5E–11 5E–11 2E–05 3E–05 0.6 0.6 — — 0.6 a 0.6 a Site 15 Resident Adult 9E–07 4E–06 — 5E–08 9E–07 4E–06 — 0.01 — 0.001 — 0.02 Child N/A N/A N/A N/A N/A N/A — 0.1 — 0.003 — 0.1 Excavation/ Construction 2E–07 1E–06 N/A N/A 2E–07 1E–06 — 0.03 N/A N/A — 0.03 Worker Occupational Worker 3E–07 1E–06 — 4E–09 3E–07 1E–06 — 0.01 — <0.001 — 0.01
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ILCR HI Indoor Indoor Indoor Indoor Sub- Inhalation - Inhalation - Total - Total - Sub- Inhalation - Inhalation - Total - Total - Surface surface Surface Subsurface Surface Subsurface Surface surface Surface Subsurface Surface Subsurfac Receptor Soil Soil Soil Soil Soil Soil Soil Soil Soil Soil Soil e Soil Site 26 Resident Adult 1E–04 2E–04 6E–08 6E–08 1E–04 2E–04 0.06 0.1 <0.001 <0.001 0.06 0.1 Child N/A N/A N/A N/A N/A N/A 0.6 0.9 <0.001 <0.001 0.6 0.9 Excavation/ Construction 3E–05 4E–05 N/A N/A 3E–05 4E–05 0.1 0.2 N/A N/A 0.1 0.2 Worker Occupational Worker 3E–05 4E–05 5E–09 5E–09 3E–05 4E–05 0.05 0.08 <0.001 <0.001 0.05 0.08 Site 27 Resident Adult 6E–07 2E–04 1E–06 1E–06 2E–06 2E–04 — 1 0.004 0.004 0.004 a 1 a Child N/A N/A N/A N/A N/A N/A — 9 0.01 0.01 0.01 a 9 a Excavation/ Construction 2E–07 4E–05 N/A N/A 2E–07 4E–05 — 2 N/A N/A — 2 a Worker Occupational Worker 2E–07 4E–05 1E–07 1E–07 3E–07 4E–05 — 0.7 <0.001 <0.001 <0.001 a 0.7 a Note: Bold font indicates exceedence of target risk or target hazard. — No value N/A not applicable a Results of the HHRA assume metals bioavailability of 100%. However, the site-specific geologic parameters measured at the site possess sufficient binding potential to effectively reduce the bioavailability of the metals to non-existent. In several instances, the concentrations were only slightly elevated, which may represent variations in natural background levels.
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2.7.1.3.2 Site 13 Risk Characterization Future Residents. Under the RME scenario, the potential ILCR for residents from all carcinogenic COPCs in surface soil (0–2 ft bgs) is 8E–05 and in subsurface soil (0–10 ft bgs) is 1E–04 (Table 2-8). The potential ILCRs are within the EPA target cancer risk range (E–06 to E–04). These risks are driven by direct exposure to soil with soil ingestion (approximately 86% and 87% for surface and subsurface soil, respectively) as the main exposure pathway. Arsenic (approximately 83% and 91% for surface and subsurface soil, respectively) is the main risk driver. Arsenic was detected in the majority of samples collected (95 of 99 samples in surface soil and 117 of 122 samples in subsurface soil) with the highest detection of 321 mg/kg in subsurface soil. Individual contaminant contributions are detailed in Table C-2 of Appendix C.
Under the RME scenario, the HI for potential non-carcinogenic health effects from the COPCs in surface soil is 7 for a child resident and 0.8 for an adult resident (Table 2-8). The HI from COPCs in subsurface soil is 8 for a child resident and 0.9 for an adult resident. The child resident HIs are above the EPA target non-cancer value of 1. However, all HI are below the HI derived from site background levels. Non-cancer hazards are driven by soil ingestion (approximately 80%) of arsenic, chromium, cobalt, and iron. Individual contaminant contributions are detailed in Table C-2 of Appendix C.
Calculated blood lead levels for all receptors were below the Cal/EPA recommended threshold of 10 µg/dL.
Current and Future Excavation/Construction Worker. Under the RME scenario, the potential ILCR for excavation/construction workers from all carcinogenic COPCs in surface soil (0–2 ft bgs) is 2E–05 and in subsurface soil (0–10 ft bgs) is 3E–05 (Table 2-8). The potential ILCRs are within the EPA target cancer risk range (E–06 to E–04). These risks are driven by direct exposure to soil with ingestion of soil (approximately 88% and 90% for surface and subsurface soil, respectively) being the main exposure pathway. Arsenic is the main risk driver (approximately 92% and 81% for surface and subsurface soil, respectively). Arsenic was detected in the majority of samples collected (95 of 99 samples in surface soil and 117 of 122 samples in subsurface soil) with the highest detection of 321 mg/kg in subsurface soil.
Under the RME scenario, the HI for potential non-carcinogenic health effects from the COPCs in surface soil is 2 for an excavation/construction worker (Table 2-8). The HI from COPCs in subsurface soil is 2 for an excavation/construction worker. The HIs are above the EPA target non-cancer value of 1 but below the HI derived from site background levels. Non-cancer hazards are driven by soil ingestion (approximately 92%) of arsenic, chromium, cobalt, and iron. Individual contaminant contributions are detailed in Table C-2 of Appendix C.
Occupational Worker. Under the RME scenario, the potential ILCR for excavation/construction workers from all carcinogenic COPCs in surface soil (0–2 ft bgs) is 2E–05 and in subsurface soil (0–10 ft bgs) is 3E–05 (Table 2-8). The potential ILCRs are within the EPA target cancer risk range (E–06 to E–04). These risks are driven by direct
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exposure to soil with ingestion of soil being the main exposure pathway (approximately 77% and 80% for surface and subsurface soil, respectively). Arsenic is the main risk driver (approximately 81% and 90% for surface and subsurface soil, respectively). Arsenic was detected in the majority of samples collected (95 of 99 samples in surface soil and 117 of 122 samples in subsurface soil) with the highest detection of 321 mg/kg in subsurface soil.
Under the RME scenario, the HI for potential non-carcinogenic health effects from the COPCs in surface soil is 0.6 for an occupational worker (Table 2-8). The HI from COPCs in subsurface soil is 0.6 for an occupational worker. The HIs are below the EPA target non- cancer value of 1. Individual contaminant contributions are detailed in Table C-2 of Appendix C.
Contaminant Fate, Transport, and Bioavailability. The HHRA performed for Site 13 calculated non-cancer HIs above 1 for both surface and subsurface soils for excavation/construction workers, and for subsurface soil for future child residents. These values, which exceed unity, are driven by the metals arsenic, chromium, cobalt, and iron. However, future development of at least the Original Site is highly unlikely because of the steep topography that comprises the majority of the Original Site, and a significant portion of the Site, which is not on a slope, consists of a former rock quarry.
Arsenic, chromium, and cobalt contributed to non-cancer risks for resident adults, children, and excavation/construction workers in surface soil at Site 13. In the HHRA, these metals are assumed to be 100% bioavailable. In soil however, a metal’s bioavailability is dependent upon its ionic state.
Arsenic, chromium, and cobalt are found as a complex mixture of mineral phases in various oxidation states, as a co-precipitate, sorbed and dissolved. In the alkaline soils such as those that exist in Guam, these metals usually remains tightly bound (adsorbed) onto, and sometimes absorbed into, ferromanganese oxide complexes and aluminum-rich clays, which are characteristics of the Ritidian Series and Guam Cobbly Clay Loam soils found at Site 13. With iron and aluminum concentrations several orders of magnitude greater than arsenic, chromium, and cobalt combined (144,000 mg/kg maximum and 111,000 mg/kg maximum, respectively), the iron and aluminum concentrations possess significant binding potential for arsenic, chromium, and cobalt to soil surfaces, which would result in a consequential drop in arsenic bioavailability.
This is mirrored in the high cation exchange capacity value of 36.6 milliequivalents, which has the potential to bind approximately 11,800 milligrams (mg) of arsenic, 7,920 mg of chromium, or 8,640 mg of cobalt for every kilogram of soil. The maximum observed concentrations were 321 mg/kg arsenic, 1,610 mg/kg chromium, and 317 mg/kg cobalt, indicating that all detected arsenic, chromium, and cobalt in site soils could easily be bound to the ferromanganese oxide complexes and aluminum-rich clays. As a result, these metals should not be considered COCs at Site 13 due to their low bioavailability.
Iron, while detected at concentrations above screening levels, represents an essential nutrient with extremely low toxicity. It is the most abundant element (by mass) on Earth (ATSDR 2003). Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-91 Andersen AFB, Guam January 2011
Generally, iron is not considered to cause harmful health effects except when swallowed in extremely large doses, such as in the case of accidental drug ingestion. Therefore, toxicological and epidemiological literature is limited. As part of a public health assessment performed for the Isla de Vieques Bombing Range, the Agency for Toxic Substances and Disease Registry (ATSDR 2003) calculated a daily consumption from exposure to the average concentration of iron in soil (45,600 mg/kg). Modeling results indicated exposure to iron in the soil would increase a child's daily consumption of iron by 4.56 milligrams per day (mg/day). The stated median daily intake in this study of dietary iron was given as roughly 11 to 13 mg/day for children 1 to 8 years old and 13 to 20 mg/day for adolescents 9 to 18 years. Therefore, the daily increases in consumption due to incidental soil ingestion are not likely to cause a person's daily dose to exceed levels known to induce poisoning (e.g., >200 mg/event) (ATSDR 2003).
2.7.1.3.3 Site 15 Risk Characterization Future Resident. Under the RME scenario, the potential ILCR for residents from all carcinogenic COPCs in surface soil (0–2 ft bgs) is 9E–07 and in subsurface soil (0–10 ft bgs) is 4E–06 (Table 2-8). The potential ILCRs are below or within the EPA target cancer risk range (E–06 to E–04). These risks were driven by direct exposure to soil, with ingestion of soil (approximately 70%) being the main exposure pathway, while dermal absorption provides approximately 30% of the risk.
Under the RME scenario, the HI for potential non-carcinogenic health effects from the COPCs in surface soil could not be calculated because of a lack of non-carcinogenic toxicity values (e.g., RfD). However, The HI from COPCs in subsurface soil is 0.1 for a child resident and 0.02 for an adult resident (Table 2-8). As a result, it can be determined that because the cancer risk is at or below the low end of the EPA target risk range and the hazard to subsurface soil is minimal, that the potential for any adverse health effects is low.
Current and Future Excavation/Construction Worker. Under the RME scenario, the potential ILCR for excavation/construction workers from all carcinogenic COPCs in surface soil (0–2 ft bgs) is 2E–07 and in subsurface soil (0–10 ft bgs) is 1E–06 (Table 2-8). The potential ILCRs are below or within the EPA target cancer risk range (E–06 to E–04). Individual contaminant contributions are detailed in Table C-3 of Appendix C.
Under the RME scenario, the HI for potential non-carcinogenic health effects from the COPCs in surface soil could not be calculated because of a lack of non-carcinogenic toxicity values (e.g., RfD). However, The HI from COPCs in subsurface soil is 0.03 for excavation/construction workers (Table 2-8). As a result, it can be determined that because the cancer risk is at or below the low end of the EPA target risk range and the hazard to subsurface soil is minimal, that the potential for any adverse health effects is low.
Occupational Worker. Under the RME scenario, the potential ILCR for occupational workers from all carcinogenic COPCs in surface soil (0–2 ft bgs) is 3E–07 and in subsurface soil (0–10 ft bgs) is 1E–06 (Table 2-8). The potential ILCRs are below or within the EPA target cancer risk range of (E–06 to E–04). Individual contaminant contributions are detailed in Table C-3 of Appendix C.
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Under the RME scenario, the HI for potential non-carcinogenic health effects from the COPCs in surface soil could not be calculated because of a lack of non-carcinogenic toxicity values (e.g., RfD). However, the HI from COPCs in subsurface soil is 0.01 for occupational workers (Table 2-8). As a result, it can be determined that because the cancer risk is at or below the low end of the EPA target risk range and the hazard to subsurface soil is minimal, that the potential for any adverse health effects is low.
2.7.1.3.4 Site 26 Risk Characterization Future Resident. Under the RME scenario and using soil gas data to evaluate vapor intrusion into indoor air, the potential ILCR from all carcinogenic COPCs in surface soil (0-2 ft bgs) is 1E–04 and in subsurface soil (0–10 ft bgs) is 2E–04 (Table 2-8). The potential ILCRs are within the EPA target cancer risk range of (E–06 to E–04). These risks are driven by direct exposure to soil with ingestion of soil being the main exposure pathway (approximately 73% and 62% of the surface and subsurface risk, respectively). Benzo(a)pyrene is the main risk driver (approximately 73% and 47% for surface and subsurface soil, respectively). In subsurface soil, PCE makes up the majority of the remaining risk (approximately 34%). Benzo(a)pyrene was only detected in 1 of 17 samples collected in both surface and subsurface soil with a concentration of 4.6 mg/kg. Due to the low number of detects (i.e., one), the maximum concentration of benzo(a)pyrene was utilized in the HHRA. Use of a more representative mean or median concentration would result in an ILCR for resident adults below 1E-04.
Under the RME scenario, the HI for potential non-carcinogenic health effects from the COPCs in surface soil is 0.6 for a child resident and 0.06 for an adult resident (Table 2-8). The HI from COPCs in subsurface soil is 0.9 for a child resident and 0.1 for an adult resident. All resident HIs are below the EPA target non-cancer value of 1. Individual contaminant contributions are detailed in Table C-4 of Appendix C.
Current and Future Excavation/Construction Worker. Under the RME scenario and using soil gas data to evaluate vapor intrusion into indoor air, the potential ILCR from all carcinogenic COPCs in surface soil (0–2 ft bgs) is 3E–05 and in subsurface soil (0–10 ft bgs) is 4E–05 (Table 2-8). The potential ILCRs are within the EPA target cancer risk range (E–06 to E–04). These risks are driven by direct exposure to soil with ingestion of soil being the main exposure pathway (approximately 74% and 72% of the surface and subsurface risk, respectively). Benzo(a)pyrene is the main risk driver (approximately 73% and 54% for surface and subsurface soil, respectively). However, in subsurface soil, PCE makes up for the majority of the remaining risk (approximately 25%). Benzo(a)pyrene was only detected in 1 of 17 samples collected in both surface and subsurface soil with a concentration of 4.6 mg/kg. Individual contaminant contributions are detailed in Table C-4 of Appendix C.
Under the RME scenario, the HI for potential non-carcinogenic health effects from the COPCs in surface soil is 0.1 for an excavation/construction worker (Table 2-8). The HI from COPCs in subsurface soil is 0.2 for an excavation/construction worker. Both HIs are below the EPA target non-cancer value of 1.
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Occupational Worker. Under the RME scenario and using soil gas data to evaluate vapor intrusion into indoor air, the potential ILCR from all carcinogenic COPCs in surface soil (0-2 ft bgs) is 3E–05 and in subsurface soil (0–10 ft bgs) is 4E–05 (Table 2-8). The potential ILCRs are within the EPA target cancer risk range (E–06 to E–04). These risks are driven by direct exposure to soil with ingestion of soil being the main exposure pathway (approximately 56% and 54% of the surface and subsurface risk, respectively). Benzo(a)pyrene is the main risk driver (approximately 74% and 54% for surface and subsurface soil, respectively). However, in subsurface soil, PCE makes up for the majority of the remaining risk (approximately 26%). Benzo(a)pyrene was only detected in 1 of 17 samples collected in both surface and subsurface soil with a concentration of 4.6 mg/kg. Individual contaminant contributions are detailed in Table C-4 of Appendix C.
Under the RME scenario, the HI for potential non-carcinogenic health effects from the COPCs in surface soil is 0.05 for an occupational worker (Table 2-8). The HI from COPCs in subsurface soil is 0.2 for an occupational worker. Both HIs are below the EPA target non- cancer value of 1.
ILCRs and cumulative non-cancer hazards for the future resident and the occupational worker could have been assessed using measured contaminant concentrations in soil instead of soil gas results. However, soil gas is typically more accurate and reflective of site conditions; therefore, the soil gas evaluation was used to assess the risk at Site 26 in this risk assessment.
2.7.1.3.5 Site 27 Risk Characterization Future Resident. Under the RME scenario and using soil gas data to evaluate vapor intrusion into indoor air, the potential ILCR from all carcinogenic COPCs in surface soil (0-2 ft bgs) is 2E–06 and in subsurface soil (0–10 ft bgs) is 2E–04 (Table 2-8). The potential ILCR for exposure to subsurface soil is above the EPA target cancer risk range (E–06 to E– 04). This risk is driven by direct exposure to soil with ingestion of soil being the main exposure pathway (approximately 91% of subsurface soil risk). Arsenic is the main risk driver (approximately 99%). Arsenic was detected in 24 of 25 samples collected at a maximum concentration of 201 mg/kg. Of those samples, 23 exceeded the residential screening criteria of 0.39 mg/kg; however, only 1 sample exceeded the BTV of 62 mg/kg.
Under the RME scenario, the HI for potential non-carcinogenic health effects from the COPCs in surface soil is 0.0 for a child resident and 0.0 for an adult resident (Table 2-8). The HI from COPCs in subsurface soil is 9 for a child resident and 1 for an adult resident. The child resident HI in subsurface soil is above the EPA target non-cancer value of 1. However, all HI are below the HI derived from site background levels. Non-cancer hazards are driven by soil ingestion (approximately 90%) of aluminum, arsenic, and total chromium. Individual contaminant contributions are detailed in Table C-5 of Appendix C.
Current and Future Excavation/Construction Worker. Under the RME scenario, the potential ILCR from all carcinogenic COPCs in surface soil (0–2 ft bgs) is 2E–07 and in subsurface soil (0–10 ft bgs) is 4E–05 (Table 2-8). The potential ILCR for exposure to soil is below or within the EPA target cancer risk range (E–06 to E–04). The risk in subsurface soil
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is driven by direct exposure to soil with ingestion of soil being the main exposure pathway (approximately 91% of subsurface soil risk). Arsenic is the main risk driver (approximately 99%). Arsenic was detected in 24 of 25 samples collected at a maximum concentration of 201 mg/kg. Of those samples, 23 exceeded the residential screening criteria of 0.39 mg/kg; however, only 1 sample exceeded the BTV of 62 mg/kg.
Under the RME scenario, the HI for potential non-carcinogenic health effects from the COPCs in surface soil could not be calculated because of a lack of non-carcinogenic toxicity values (e.g., RfD). However, the HI from COPCs in subsurface soil is 2 for excavation/construction workers (Table 2-8). The HI in subsurface soil is above the EPA target non-cancer value of 1. However, all HI are below the HI derived from site background levels. Non-cancer hazards are driven by soil ingestion (approximately 80%), which includes the ingestion of aluminum, arsenic, and total chromium. Individual contaminant contributions are detailed in Table C-5 of Appendix C.
Occupational Worker. Under the RME scenario and using soil gas data to evaluate vapor intrusion into indoor air, the potential ILCR from all carcinogenic COPCs in surface soil (0-2 ft bgs) is 3E–07 and in subsurface soil (0–10 ft bgs) is 4E–07 (Table 2-8). The potential ILCR for exposure to soil is below or within the EPA target cancer risk range (E–06 to E– 04). The risk in subsurface soil is driven by direct exposure to soil with ingestion of soil being the main exposure pathway (approximately 82% of subsurface soil risk). Arsenic is the main risk driver (approximately 98%). Arsenic was detected in 24 of 25 samples collected at a maximum concentration of 201 mg/kg. Of those samples, 23 exceeded the residential screening criteria of 0.39 mg/kg; however, only 1 sample exceeded the BTV of 62 mg/kg.
Under the RME scenario, the HI for potential non-carcinogenic health effects from the COPCs in surface soil is 0.0 for an occupational worker (Table 2-8). The HI from COPCs in subsurface soil is 0.7 for occupational workers. Both HIs are below the EPA target non- cancer value of 1. Individual contaminant contributions are detailed in Table C-5 of Appendix C.
ILCRs and cumulative non-cancer hazards for the future resident and occupational worker could have been assessed using measured contaminant concentrations in soil instead of soil gas results. However, soil gas is typically more reflective of current site conditions; therefore, the soil gas evaluation is used to assess the risk at Site 27 in this risk assessment.
Contaminant Fate, Transport, and Persistence. The HHRA performed for Site 27 calculated cancer risk for subsurface soil, adult residents, at the high end of the allowable range, and non-cancer subsurface soil HIs above 1 for excavation/construction workers, and future child residents. These risks are driven by the metals aluminum, arsenic, and chromium. Additionally, while arsenic contributed to the non-cancer risk at Site 13, no surface soil results and only one subsurface soil sample result contained arsenic above the BTV (the maximum value was used in the HHRA due to the low number of sample results). The mean concentrations of arsenic in surface and subsurface soils at Site 27 are 17.1 mg/kg and 25.38 mg/kg, respectively, with 95% upper confidence limit (UCL) values of
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21.76 mg/kg and 58.37 mg/kg. These values are comfortably below the BTV. As a result, no remediation of arsenic in Site 27 soils is required.
Chromium contributed to the non-cancer risk to excavation/construction workers and future resident child receptors in subsurface soils. Three of five subsurface soil samples contained chromium at concentrations above the BTV of 1,080 mg/kg, with an average subsurface concentration of 777 mg/kg. This contrasts with surface soil results, for which no value was greater than 50% of the BTV, with an average chromium concentration of 102 mg/kg.
The subsurface soil horizon from which the three samples were collected was thin across the site, generally less than 2 ft, and described as “stiff, reddish-brown clay with a minimal mixture of loose limestone fragments”; that is, immature soils that likely reflect the geochemical make-up of the parent rock. The three subsurface chromium results slightly exceeded the BTV (1,190 mg/kg, 1,120 mg/kg, and 1,320 mg/kg) and likely represent the upper end of variability of background chromium in Guam soils. As a result, no remediation of chromium in Site 27 soils is required.
Aluminum contributed to the non-cancer risk to excavation/construction workers and future resident child receptors in subsurface soils. Aluminum is the most abundant metal at the site, and the third most abundant element in the Earth’s crust, comprising approximately 8.8% by weight (Sorenson et al. 1974). It is common in all geologic environments, is an important constituent of clay minerals, and has been observed in Hawaiian soils at ranges up to 317,000 mg/kg (Moomaw et al. 1959). In limestone terrains such as Guam, clay deposits are usually residual, accumulating as a result of solution of the limestone bedrock. The three subsurface aluminum results that exceeded the BTV of 173, 500 mg/kg (235,000 mg/kg, 248,000 mg/kg, and 217,000 mg/kg) likely reflect the clay-rich nature of the soils from which the samples were collected. As a result, no remediation of aluminum in Site 27 soils is required.
In summary, the risk assessment for Site 27 concluded that no response action was warranted for metals in soil at Site 27 in order to protect human health and the environment. This decision is based upon several factors: significantly reduced bioavailability due to the binding potential of clays and ferromanganese hydroxides in the carbonate-based soils present at the site; the likelihood that observed soil concentrations of the metals chromium and aluminum reflect the underlying geology, which consists of rocks enriched in aluminum and chromium; and the site background concentrations.
2.7.1.4 Exposure to Lead An additional evaluation was conducted for exposure to lead where soil lead concentrations exceeded screening levels. This occurred only at Site 10 and Site 13. To provide site- specific evaluations of blood lead levels as they might relate to potential exposures to site- related surface soil, the Cal/EPA “LeadSpread7” model was employed (Cal/EPA 2000). According to Cal/EPA “LeadSpread 7 is the latest version of the California Department of Toxic Substances Lead Risk Assessment Spreadsheet. LeadSpread is a tool that can be used to estimate blood lead concentrations resulting from exposure to lead via dietary intake, drinking water, soil and dust ingestion, inhalation, and dermal contact.”
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No calculated blood lead levels were found to exceed 10 µg/dL for any receptor at Site 10 and Site 13, a level typically defined as a benchmark that should not be exceeded in 5% of the potentially exposed population. Lead is therefore not considered a risk at either site.
2.7.1.5 Human Health Risk Assessment Conclusions The HHRA for Site 10 concluded that both cancer and non-cancer risks for all soil exposure pathways were within or below the EPA target risk range. The results reflect the effectiveness of the interim remedial actions conducted at Site 10. Modeled blood lead levels were not found to exceed the EPA benchmark for any receptor, thus lead is not considered a risk at Site 10.
The HHRA for Site 13 identified several metals in surface soils above screening levels. However, the risk assessment for Site 13 concluded that no response action was warranted for metals in soil based upon significantly reduced bioavailability due to the binding potential of clays and ferromanganese hydroxides in the carbonate-based soils present at the site. These geochemical soil conditions would possess sufficient binding potential to effectively reduce the bioavailability of the metals to near zero. Quantitatively, this premise is supported by an elevated soil cation exchange capacity measurement, with a value sufficiently high to bind most of the metals within the soil complex, thereby making them biologically unavailable. Additionally, due to the alkaline hydrogen ion concentration (pH) and oxidative redox conditions of Guam soils, any metallic ions present are likely to exist in their more oxidized state, a condition which reduces both mobility and bioavailability.
In several instances, the values were only slightly elevated, and may represent variations in natural background levels. In consideration of these factors, no further response action is required. Modeled blood lead levels were not found to exceed 10 µg/dL for any receptor.
The HHRA for Site 15 concluded that both cancer and non-cancer risks for all soil exposure pathways were within or below the EPA target risk range. The results reflect the effectiveness of the interim remedial actions conducted at Site 15.
The HHRA for Site 26 concluded non-cancer risks were within or below the EPA target ranges. ILCR for resident adults was calculated at 2E-04, which is above the 1E-04 target range. However, due to the low number of detects (i.e., one) of benzo(a)pyrene in soil samples collected from the site, the maximum concentration was utilized in the HHRA. Use of a more representative mean or median concentration would result in an ILCR for resident adults below 1E-04.
Based upon the results of the previous investigations and operation of the VES, no further remedial action is required at Site 26.
The HHRA for Site 27 identified several metals in subsurface soils above screening levels. However, the risk assessment for Site 27 concluded that no response action was warranted for metals in soil at Site 27 in order to protect human health and the environment. This decision is based upon several factors: significantly reduced bioavailability due to the binding potential of clays and ferromanganese hydroxides in the carbonate-based soils present at the site; the likelihood that observed soil concentrations of the metals chromium Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-97 Andersen AFB, Guam January 2011
and aluminum reflect the underlying geology, which consists of rocks enriched in aluminum and chromium; and the site background concentrations. Modeled blood lead levels were not found to exceed 10 µg/dL for any receptor, and were found to be acceptable.
2.7.2 Summary of Ecological Risk Assessment The objective of the ERA was to evaluate possible risks to plants and wildlife associated with exposure to COPCs at each of the five sites: Site 10, Site 13, Site 15, Site 26, and Site 27. Ecological risks were estimated for each COPC based upon a combination of the concentration and toxicity of the COPC, the medium (e.g., soil or soil gas) in which the COPC is found, estimated exposure rate and estimated exposure duration. These calculations were derived for several representative species that were observed, or may be observed, at the IRP sites. The cumulative risk posed by the COPCs at a particular site is called the HQ. Any HQ above the value of 1 indicates the potential for ecological harm. The full ERA is presented in Appendix D of the RI report (AECOM 2010). The ecological risks were assessed according to the EPA ERA guidance (EPA 1997).
The ERA for each site began with a Tier 1 Steps 1 and 2 screening evaluation according to EPA guidance. The Tier 1 effort is a screening process designed to eliminate COPECs found in site media based on highly conservative risk considerations. For example, maximum media concentrations are compared to conservative media-specific screening values, and those that exceed the screening values are retained for further evaluation. Those that do not exceed the screening values are eliminated as COPCs.
In addition, measurement endpoints (measures of effects) corresponding to reduced growth/development, reproduction, and/or survival were identified for representative species observed, or expected to be present, at the sites being assessed. Exposure concentrations that produce adverse effects for growth/development, reproduction, or survival for plant and wildlife species were obtained from peer-reviewed publications. The no-observed-adverse- effect level was used to develop an exposure estimate below which adverse effects are not expected to occur. Ecological receptors selected for evaluation for each site include lower trophic level (LTL) groups of plants and soil invertebrates, and two higher trophic level wildlife species—one bird (yellow bittern) and one mammal (house mouse).
Selection of the bittern and mouse was based largely on the species’ ecological importance and representativeness for the sites, and their habits that tend to lead to maximum exposure to soil pathways. Available soil benchmarks from the literature were used to assess potential effects for plants and soil invertebrates. Bittern-specific and mouse-specific ingestion doses for soil-related COPC concentrations (i.e., ingestion doses for soil-based food items plus incidental soil ingestion) were used in conjunction with ingestion-dose toxicity reference values (TRVs) for birds and mammals, respectively, to derive soil benchmark concentrations (SBCs) for the bittern and mouse. The SBCs were calculated with the yellow bittern used to represent bird exposure, and the house mouse used to represent mammal exposure. The soil- based screening values for direct contact (plants and soil invertebrates) and food-chain exposure (bittern and mouse) were compared, and the lowest screening value for each contaminant was selected as the SBC for screening.
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A comparison of the maximum detected surface soil concentration for each contaminant was made to the lowest SBC for each site contaminant. If the maximum concentration for a contaminant exceeded the screening value, the contaminant was retained for further evaluation; otherwise, the contaminant was eliminated as a site COPEC and dropped from further evaluation.
Contaminants retained as COPCs at the end of the Tier 1 screen were carried forward to a Tier 2 Step 3a baseline ecological risk assessment (BERA). The Step 3a BERA involves refining exposure assumptions made in the Tier 1 screen in order to arrive at a more accurate estimation of risk to the representative ecological receptors. The Navy incorporated the following refinements for exposure assumptions into the Step 3a efforts to estimate exposure and HQs:
RME value for the EPC in estimating risk to ecological receptors is used. The RME is either the maximum concentration or the UCL of the mean, whichever is lower.
RME values are compared to site-specific background concentrations for metals.
Body weights for the bittern and mouse are the means for the particular species. Body weights were minimum values in the Tier 1 screen to maximize exposure and better represent juvenile exposure.
Food ingestion rates for the bittern and mouse are means for the particular species. Ingestion rates were maximum values in the Tier 1 screen to maximize estimates for contaminant intake.
Diets for the yellow bittern and the house mouse include portions for plant material/seeds, soil invertebrates, and soil in the diets, each of which contains differing concentrations for a COPEC. The relative proportions of plant material (seeds, shoots), soil invertebrates, and incidental ingested soil in the diets are based on literature- derived values for the bittern and mouse.
The site use factor (SUF) is the area of contamination at a site divided by the foraging area for a particular species. SUFs for the bittern and mouse were assumed to be 1 in the Tier 1 screen. In Tier 2, the following site areas were used to estimate SUFs for foraging areas identified for the bittern and mouse: Site 10 occupies 33 acres (13.35 hectares [ha]); Site 13 occupies 15 acres (6.07 ha); Site 15 occupies 10 acres (4.05); Site 21 occupies 5 acres (2.02 ha), and Site 26 occupies approximately 9 acres (3.64 ha). Foraging areas for the bittern and mouse were obtained from the scientific literature.
The following sections summarize ERA information for Step 3a BERA evaluations for each of five sites: Site 10, Site 13, Site 15, Site 26, and Site 27. Guidance for preparing a ROD (EPA 1999) notes that the following details should be discussed for ERA in the ROD:
Identification of COCs
Exposure assessment
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Ecological effects assessment (including identification of assessment and measurement endpoints)
Ecological risk characterization
For each of the sites, the exposure assessment and ecological effects assessment follow the same approach; therefore, Sections 2.7.2.1 and 2.7.2.2 (Exposure Assessment and Ecological Effects Assessment, respectively) apply to all sites. However, the identification of COPECs and the ecological risk characterization are unique to each site; therefore, these discussions are presented by site in Sections 2.7.2.3 through 2.7.2.7.
2.7.2.1 Exposure Assessment Exposures for ecological receptors for all five sites address four assessment endpoints: plants, soil invertebrates, omnivorous birds, and omnivorous mammals. Exposures for all assessment endpoints are based on RME values for EPCs in surface soil. The RME is either the maximum concentration or the UCL of the mean, whichever is lower. Exposures for plants and soil invertebrates are based on the RME value. Exposures for birds and mammals are estimated for uptake of contaminants from soil into food items (plant material and soil invertebrates) and incidental ingestion of soil. Higher trophic level receptors for birds and mammals are represented by the yellow bittern and the house mouse, respectively.
2.7.2.2 Ecological Effects Assessment Effects for plants and soil invertebrates are assessed by comparing measured concentrations of contaminants in soils to available effects-based soil benchmarks for plants and soil invertebrates. Effects for bird (e.g., yellow bittern) and mammal (e.g., house mouse) receptors are assessed by developing SBCs for the bittern and mouse for ingestion doses of soil-related COPECs that are compared to ingestion dose TRVs for birds and mammals, respectively. No toxicity tests or field studies were performed.
ERA assessment and measurement endpoints for the Step 3a BERA for all five sites are summarized in Table 2-9.
Table 2-9: Assessment and Measurement Endpoints for Step 3a BERA Considerations for Sites 10, 13, 15, 26, and 27 Receptor of Exposure Assessment Testable Measurement Concern Pathway Endpoint * Hypothesis Endpoint Data Available
Plants Root uptake of Decrease in H0: The Compare RME Site-specific contaminants in plant growth concentration of surface soil contaminant data soil and contaminants in concentration to for surface soil; for reproduction surface soil does risk-based soil Step 3a BERA use not exceed a level benchmark RME value known to be toxic concentration to plants developed to protect plant growth and reproduction
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Receptor of Exposure Assessment Testable Measurement Concern Pathway Endpoint * Hypothesis Endpoint Data Available
Soil Uptake of Decrease in H0: The Compare RME Site-specific Invertebrates contaminants in growth and concentration of surface soil contaminant data soil reproduction contaminants in concentration to for surface soil; for of soil surface soil does risk-based soil Step 3a BERA use invertebrates not exceed a level benchmark RME value known to be toxic concentration to soil developed to invertebrates protect growth and reproduction of soil invertebrates
Small Ingestion of Protection H0: The ingestion Compare RME Site-specific omnivorous contaminants in and of surface soil contaminant data mammals soil, and maintenance bioaccumulative concentration of for surface soil; for (represented accumulated in (survival, contaminants in contaminant to Step 3a BERA use by the house plant material and growth, and plant material, soil risk-based Eco- RME value mouse) soil invertebrates reproduction) invertebrates, and SBC for mammals of local surface soil does omnivorous not exceed a level mammal known to be toxic populations to small mammals
Small Ingestion of Protection H0: The ingestion Compare RME Site-specific omnivorous contaminants in and of surface soil contaminant data birds soil, and maintenance bioaccumulative concentration of for surface soil; for (represented accumulated in (survival, contaminants in contaminant to Step 3a BERA use by the yellow plant material and growth, and plant material, soil risk-based Eco- RME value bittern) soil invertebrates reproduction) invertebrates, and SBC for birds of local surface soil does omnivorous not exceed a level bird known to be toxic populations to small birds
H0 Null Hypothesis * Assessment endpoints identified for evaluation are based on the parameters used to derive toxicity benchmarks (see Measurement Endpoint column) and are not intended to imply measurement of these parameters in the field.
Those COPECs that failed the LTL screening process were retained for further evaluation in Tier 2. The Tier 2 exposure concentrations (RME) for each retained COPEC was compared to the LTL screening values by dividing the RME soil COPEC concentration by the LTL screening value to produce a HQ. A HQ greater than 1 indicates that the exposure concentration exceeds the screening value. The HQ results are summarized in Table 2-10.
Table 2-10: Tier 2 COPECs that Failed the Tier 2 LTL Screening Process COPECs Site 10 Site 13 Site 15 Site 26 Site 27 Inorganic Arsenic X X X X X Antimony X X — — — Barium — — — — — Beryllium — — — — — Cadmium — X X — —
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COPECs Site 10 Site 13 Site 15 Site 26 Site 27 Chromium X X X X X Cobalt — X X — — Copper — X — X — Lead X X X — X Manganese X X X X X Mercury — X X X X Nickel — X X — — Selenium X X X X X Silver X — — X — Thallium — X X — — Vanadium X X X X X Zinc X X X X X Organic Fluoranthene X — — — — Ethylbenzene — — — X — X Contaminant failed the Tier 2 LTL screening process and will be further evaluated in the higher trophic levels. — No further evaluation necessary.
Those COPECs that failed the Tier 1 direct contact and wildlife screening process were retained for further evaluation in Tier 2. In Tier 2, the potential risk to ecological receptors was estimated using the HQ methodology. Risk was estimated for each COPEC exposure pathway for representative bird and mammal species at each area of concern. A risk- management decision was made to place focus only on the risk associated with the upper trophic levels.
Exposure of birds and mammals in each area to COPECs is determined based on the exposure characteristics of the yellow bittern and the house mouse, respectively. The exposure parameters used in Step 3a included the RME COPEC concentrations in soil and food species, mean receptor body weight, and mean receptor food intake.
The HQ is used to integrate toxicity and exposure information to predict possible adverse effects to ecological receptors. The method compares estimates of chronic daily intake of each COPEC at each site to the respective TRV. This comparison is expressed as the quotient (the HQ value) of the ratio of intake/TRV.
2.7.2.3 Site 10
2.7.2.3.1 Site 10: Identification of Contaminants of Potential Environmental Concern COPECs for ecological risk were measured in surface soil samples. For higher trophic level receptors of birds (i.e., yellow bittern) and mammals (i.e., house mouse), Step 3a BERA HQs exceed 1 for only chromium for the bittern (HQ=3). However, the bittern HQ is for an EPC for chromium in soil of 247 mg/kg (95 UCL), which is below the background soil concentration for chromium (1,080 mg/kg). Therefore, chromium is removed as a soil COPEC for the bittern.
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2.7.2.3.2 Site 10: Ecological Risk Characterization For Site 10, results of the Tier 2 exposure and HQ calculations for the bird (yellow bittern) and mammal (house mouse) receptors are presented in Appendix D (Ecological Risk Assessment) of the RI. No HQs exceed 1 for the house mouse. For the yellow bittern, the only HQ exceeding 1 is for chromium (HQ=3). However, comparison of the soil RME concentration for chromium to the background concentration for site soils indicates the RME is below the background concentration. Therefore, chromium is removed as a surface soil COPC. As a result, soils at Site 10 do not represent an unacceptable risk of adverse effects to birds or mammals represented by the yellow bittern and house mouse, respectively.
2.7.2.4 Site 13
2.7.2.4.1 Site 13: Identification of Contaminants of Potential Environmental Concern COPECs for ecological risk were measured in surface soil samples. For higher trophic level receptors of birds (i.e., yellow bittern) and mammals (i.e., house mouse), Step 3a BERA HQs for the bittern exceed 1 for chromium (HQ=3) and lead (HQ=2). The bittern HQ for chromium is for an EPC for chromium in soil of 407 mg/kg (95 UCL), which is below the background soil concentration for chromium (1,080 mg/kg). Therefore, chromium is removed as a soil COPC for the bittern. The bittern HQ for lead is for an EPC for lead in soil of 562 mg/kg (97.5 UCL), which is above the background soil concentration for lead (166 mg/kg). However, the bittern HQ for lead assumes 100% bioavailability for lead in soil. Lead is likely present in a less bioavailable form (lead carbonate) because of the high pH of the limestone-derived soils. Therefore, the lead HQ slightly greater than 1 is likely an overestimate for lead risk, and lead is removed as a soil COPEC for the bittern.
2.7.2.4.2 Site 13: Ecological Risk Characterization For Site 13, results of the Tier 2 exposure and HQ calculations for the bird (yellow bittern) and mammal (house mouse) receptors are presented in Appendix D (Ecological Risk Assessment) of the RI. No HQs exceed 1 for the house mouse. For the yellow bittern, HQs exceed 1 for two metals (chromium HQ=3; lead HQ=2). For chromium, comparison of the soil RME concentration to the background concentration for site soils indicates the RME is below the background concentration for chromium. In contrast, comparison of the soil RME concentration for lead to the background concentration for site soils indicates the RME is above the background concentration for lead. However, the risk estimate for lead exposure is based on an assumption of 100% bioavailability for lead in soils. The limestone-derived soils have a high pH; thus, lead is likely to be present in a form (lead carbonate) that has a bioavailability less than 100%. Because of this and the relatively low HQ, the risk to bird populations from exposure to site lead is assumed to be acceptable. In summary, soils at Site 13 are not expected to represent an unacceptable risk of adverse effects to birds or mammals represented by the yellow bittern and house mouse, respectively.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-103 Andersen AFB, Guam January 2011
2.7.2.5 Site 15
2.7.2.5.1 Site 15: Identification of Contaminants of Potential Environmental Concern COPECs for ecological risk were measured in surface soil samples. For higher trophic level receptors of birds (i.e., yellow bittern) and mammals (i.e., house mouse), Step 3a BERA HQs for the bittern exceed 1 for chromium (HQ=3) and vanadium (HQ=2). The bittern HQ for chromium is for an EPC for chromium in soil of 664.1 mg/kg (95 UCL), which is below the background soil concentration for chromium (1,080 mg/kg). Therefore, chromium is removed as a soil COPC for the bittern. The bittern HQ for vanadium is for an EPC for vanadium in soil of 85.4 mg/kg (95 UCL), which is below the background soil concentration for vanadium (206 mg/kg). Therefore, vanadium is removed as a soil COPEC for the bittern.
2.7.2.5.2 Site 15: Ecological Risk Characterization For Site 15, results of the Tier 2 exposure and HQ calculations for the bird (yellow bittern) and mammal (house mouse) receptors are presented in Appendix D (Ecological Risk Assessment) of the RI. No HQs exceed 1 for the house mouse. For the yellow bittern, HQs exceed 1 for two metals (chromium HQ=3; vanadium HQ=2). However, comparison of the soil RME concentrations to background concentrations for site soils indicates the RMEs are below background concentrations for both chromium and vanadium. In summary, soils at Site 15 are not expected to represent an unacceptable risk of adverse effects to birds or mammals represented by the yellow bittern and house mouse, respectively.
2.7.2.6 Site 26
2.7.2.6.1 Site 26: Identification of Contaminants of Potential Environmental Concern COPECs for ecological risk were measured in surface soil samples. For higher trophic level receptors of birds (i.e., yellow bittern) and mammals (i.e., house mouse), Step 3a BERA HQs exceed 1 for the bittern for benzo(b)fluoranthene (HQ=3) and for the mouse for selenium (HQ=6). The bittern HQ for benzo(b)fluoranthene is for an EPC in soil of 7,200 micrograms per kilogram (maximum concentration), but is for only 1 detect in 17 soil samples. Therefore, benzo(b)fluoranthene is removed as a soil COPEC for the bittern based on the low frequency for detection. The mouse HQ for selenium is for an EPC for selenium in soil of 68.28 mg/kg (95 UCL), which is above the estimated background soil concentration for selenium (4.5 mg/kg); however, there are only 2 detects in 29 soil samples. Therefore, selenium is removed as a soil COPEC for the mouse based on the low frequency for detection.
2.7.2.6.2 Site 26: Ecological Risk Characterization For Site 26, results of the Tier 2 exposure and HQ calculations for the bird (yellow bittern) and mammal (house mouse) receptors are presented in Appendix D (Ecological Risk Assessment) of the RI. For the house mouse, one HQ exceeds 1 for selenium (HQ=6) for an RME value (68.28 mg/kg) above background (4.5 mg/kg), but selenium is only detected in 2 of 29 soil samples. For the yellow bittern, one HQ exceeds 1 for benzo(b)fluoranthene (HQ=3), but benzo(b)fluoranthene is only detected in 1 of 17 soil samples. In summary, soils at Site 26 are not expected to represent an unacceptable risk of adverse effects to birds or mammals represented by the yellow bittern and house mouse, respectively, based on the Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-104 Andersen AFB, Guam January 2011
low frequency of detects for those COPECs with HQs greater than 1. In addition, Site 26 is located in the industrial portion of Andersen AFB within the flightline. It consists of maintained landscaping and various structures associated with the fire-training activities that take place at the Site. Any wildlife habitat is significantly degraded and considered low quality. Furthermore, because of the Site’s location within the flightline, wildlife, especially avian wildlife, is discouraged.
2.7.2.7 Site 27
2.7.2.7.1 Site 27: Identification of Contaminants of Potential Environmental Concern COPECs for ecological risk were measured in surface soil samples. For higher trophic level receptors of birds (i.e., yellow bittern) and mammals (i.e., house mouse), no Step 3a BERA HQs exceed 1 for either the bittern or the mouse. Therefore, all contaminants are removed as soil COPECs for the bittern and the mouse.
2.7.2.7.2 Site 27: Ecological Risk Characterization For Site 27, results of the Tier 2 exposure and HQ calculations for the bird (yellow bittern) and mammal (house mouse) receptors are presented in Appendix D (Ecological Risk Assessment) of the RI. No Tier 2 BERA HQs exceed 1 for either the bittern or mouse. In summary, soils at Site 27 are not expected to represent an unacceptable risk of adverse effects to birds or mammals represented by the yellow bittern and house mouse, respectively.
2.8 Documentation of Significant Changes The selected remedy described in this ROD for Sites 10, 13, 15, 26, and 27 (and the preferred remedial alternative recommended in the PP) is protective of human health and the environment. No substantial changes have occurred in site contamination conditions, land use, or regulations pertaining to remediation of these sites.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 2-105 Andersen AFB, Guam January 2011
3.0 Responsiveness Summary This section provides a summary of the public comments regarding the PP for remedial action at Sites 10, 13, 15, 26, and 27, Andersen AFB. At the time of the public review period, the Navy had selected NFA as the preferred alternative for the site.
3.1 Stakeholder Comments and Lead Agency Responses Public comments were solicited during the public comment period and during the public meeting for the PP. The comment period was from 1 May to 30 May 2010 and the public meeting for the PP was held on 19 May 2010. A legal notice was published in the Guam Pacific Daily News on 4 May 2010 summarizing the PP and announcing the availability of the AR as well as the public comment period and public meeting. The PP public meeting was held at the Guam Marriott Resort and Spa in Tumon. The meeting was recorded and transcribed and is available in the AR. The transcript was reviewed by the Navy to prepare this Responsiveness Summary. Responses to comments received from the public and community stakeholders in attendance at the public meeting are addressed in Appendix B.
3.2 Technical and Legal Issues No technical or legal issues have been identified.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 3-1 Andersen AFB, Guam January 2011
4.0 References 40 Code of Federal Regulations (CFR) 300. National Oil and Hazardous Substances Pollution Contingency Plan. Available: http://ecfr.gpoaccess.gov.
42 United States Code (U.S.C.). 1980. The Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) of 1980, as amended. Chapter. 103. §§9601- 9675.
AECOM Technical Services, Inc. (AECOM). 2010. Final Remedial Investigation, IRP Site 10, 13, 15, 26, and 27, Andersen AFB, Guam. Guam: Andersen Air Force Base. February.
Agency for Toxic Substances and Disease Registry (ATSDR). 2003. Petitioned Public Health Assessment Soil Pathway Evaluation, Isla de Vieques Bombing Range Vieques, Puerto Rico. February.
Alba, Chit. 1997. Andersen Air Force Base. Personal Communication. June.
Andersen Air Force Base (Andersen AFB). 1948. North Field Guam, Mariana Islands, Sewage Deposal Plant, Plot Plan & Sections, As-Built. September.
———. 1963. Repair Sanitary Sewer System, Site Plan, Andersen Air Force Base. 15 April.
———. 1975a. Real Property Accountability Record, Building 1099. 36th Civil Engineering Squadron Real Property Office, Andersen Air Force Base, Guam. June.
———. 1975b. Strategic Air Command, Master Plan Narrative, Andersen Air Force Base, Guam, Mariana Islands. 1 January.
———. 2001. Technical Memorandum on the Recalculation of Background Threshold Value (BTV) for Manganese in Soil, Installation Restoration Program (IRP) Sites, Andersen Air Force Base, Guam. November.
———. 2005. Site 26 VES System, Result for 11th Vapor Sample. October.
Barrett, Harris & Associates and Camp, Dresser & McKee, Inc. 1982. Northern Guam Lens Study Aquifer Yield Report. December.
Battelle (Battelle Columbus Division). 1989. Installation Restoration Program Phase II Stage 1-Confirmation/Quantification, Andersen Air Force Base, Guam. Final Report. January.
California Environmental Protection Agency (Cal/EPA). 2000. LeadSpread 7: DTSC Lead Risk Assessment Spreadsheet. Department of Toxic Substances Control.
Defense Base Closure and Realignment Commission (DBCRC). 2005. 2005 Defense Base Closure and Realignment Commission Report. Final. Washington. September. Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 4-1 Andersen AFB, Guam January 2011
Department of Defense (DoD). 2008. Environmental Supplemental Guidance for Implementing and Operating a Joint Base. 15 April.
EA Engineering, Science, and Technology (EA). 1999a. Final Engineering Evaluation/Cost Analysis (EE/CA) for IRP Site 10/Landfill 14. Andersen Air Force Base, Guam. May.
———. 1999b. Final Engineering Evaluation/Cost Analysis (EE/CA) for IRP Site 16/Landfill 21. Andersen Air Force Base, Guam. May.
———. 1999c. Final No Further Response Action Planned Decision Document for IRP Site 27/Hazardous Waste Storage Area 1, Andersen AFB, Guam. April.
———. 2007. Technical Memorandum: Discontinuation of Vapor Extraction System at Fire Training Area 2, Andersen AFB, Guam. March.
———. 2009. Final Second Five-Year Review of Record of Decision for MARBO Annex OU, Andersen AFB, Guam. August.
Environmental Protection Agency, United States (EPA). 1989. Risk Assessment Guidance for Superfund (RAGS), Volume I, Human Health Evaluation Manual (Part A). Interim Final. EPA/540/1-89/002. Office of Emergency and Remedial Response. December.
———. 1997. Ecological Risk Assessment Guidance for Superfund: Process for Designing and Conducting Ecological Risk Assessment. Interim final. EPA/540/R-97/006. Office of Solid Waste and Emergency Response. June.
———. 2008. Integrated Risk Information System (IRIS). [online]. Available: http://www.epa.gov/iris/. Accessed: December 8, 2008.
———. 2009. Regional Screening Levels for Chemical Contaminants at Superfund Sites. EPA Office of Superfund. April.
Environmental Protection Agency, United States, Region 9 (EPA Region 9). 1998. Region 9 Preliminary Remediation Goals (PRGs). May.
———. 2000. Region 9 Preliminary Remediation Goals (PRGs). May.
Environmental Science and Engineering, Inc., and Reynolds, Smith and Hills, Inc. (ESE). 1985. Installation Restoration Program Phase I: Records Search, Andersen Air Force Base, Guam. March.
Foster-Wheeler Environmental Corporation (FWENC)/EA Engineering, Science, and Technology Inc. (EA). 2002. Final Engineering Evaluation/Cost Analysis Report for IRP Site 15/Landfill 20, Andersen Air Force Base, Guam. September.
———. 2003. Final Engineering Evaluation/Cost Analysis Report for IRP Site 26/Firefighter Training Area 2. August.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 4-2 Andersen AFB, Guam January 2011
Guam Division of Aquatic and Wildlife Resources (Guam DAWR). 1997. Personal communication with Grant Beauprez, Guam Department of Agriculture, Guam. 23 January.
ICF Technology, Inc., (ICF). 1994. Operable Unit 6 Basewide Work Plan for Operable Unit 4, Andersen Air Force Base, Guam. January.
———. 1996. Records Search for Andersen Air Force Base. Final. February.
———. 1997. Analysis of Background Threshold Values for Andersen Air Force Base, Guam.
Jacobs Engineering Group, Inc. (Jacobs). 1998. Site Summary Report for Firefighter Training Area 2 (Soil Vapor Extraction System), Andersen Air Force Base, Guam. August.
Kingston, P.A. 2004. Surveillance of Drinking Water Quality in the Pacific Islands: Situation Analysis and Needs Assessment. December.
Mink, J. F. 1976. Groundwater Resources of Guam: Occurrence and Development. WRRC Technical Report 1.285 p.
Moomaw, J.C., et al. 1959. Aluminum in Some Hawaiian Plants. In Pacific Science 13:335- 341.
Oak Ridge National Laboratory (ORNL). 2008. The Risk Assessment Information System (RAIS). [online]. Available: http://rais.ornl.gov/tox/tox_values.shtml. Accessed: December 8, 2008.
Reynolds, Smith and Hills, Inc. and Environmental Science and Engineering, Inc. 1985. Installation Restoration Program Phase I: Records Search, Andersen Air Force Base, Guam. March.
Science Applications International Corporation (SAIC). 1986. RCRA Facility Assessment Report, Solid Waste Management Units. December.
———. 1991a. IRP Phase 2, Remedial Investigation/Feasibility Study, Technical Report, Volume 1 Final, Andersen Air Force Base, Guam. December.
———. 1991b. Remedial Investigation/Feasibility Study, Stage II for Andersen Air Force Base, Guam. Technical Volume II. November.
Shaw Environmental, Inc. (Shaw). 2006. Environmental Cleanup Plan, Interim Remedial Action, Installation Restoration Program Site 15/Landfill 20, Andersen Air Force Base, Guam. Honolulu, Hawaii. June.
———. 2009. Draft Interim Removal Action Completion Report, IRP Site 15, Andersen AFB, Guam. October. Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 4-3 Andersen AFB, Guam January 2011
Sorenson, J. R. J., et al. 1974. Aluminum in the Environment and Human Health. In Environmental Health Perspectives 8:3-95.
Stearns, H. T. 1937. Geology and Water Resources of the Island of Guam, Mariana Islands. U.S. Navy Manuscript.
Tracey, J. I., Jr., S. O. Schlanger, J. T. Stark, D. B. Doan, and H. G. 1964. General Geology of Guam. Professional Paper 403-A. U.S. Geological Survey, Washington, D.C.104 pp. March.
United States Air Force (USAF). 1999. No Further Response Action Planned (NFRAP) for IRP Site 27/Hazardous Waste Storage Area 1. April.
———. 2010. Proposed Plan for No Further Action, IRP Site 10, 13, 15, 26, and 27, Andersen AFB, Guam. Guam: Andersen Air Force Base.
URS Corporation (URS). 2003. Draft Engineering Evaluation/Cost Analysis Report for IRP Site 13/Landfill 18, Andersen Air Force Base, Guam. June.
U.S. Bureau of the Census. 2001. Population of Insular Areas. Census Bureau Web Site (www.census.gov), Washington, D.C. 20233-3700.
Ward, P. E., Hoffman, S. H., and Davis, D. A. 1965. Hydrology of Guam. U.S. Geological Survey Professional Paper 403H. 28 p.
White, William B. 2007. A Brief History of Karst Hydrogeology: Contributions of the NSS. Journal of Cave and Karst Studies, v. 69 no. 1, p.13-26.
Works, D. 1997. Conservation Officer, Andersen Air Force Base. Personal communication. June.
Final NFA ROD, IRP Sites 10, 13, 15, 26, and 27 4-4 Andersen AFB, Guam January 2011
Appendix A Federal Facility Agreement Notice Letters
DEPARTMENT OF THE AIR FORCE HEADQUARTERS, 36TH WING (PACAF) UNIT 14007, APO AP 96543-4007
06 November 2009
36 CES/CEVR Unit 14007 APO AP 96543-4007
Mr. Mark Ripperda Project Manager U.S. Environmental Protection Agency 75 Hawthorne St., H-9-4 San Francisco, CA 94105-3901
Dear Mr. Ripperda
This letter provides notice of a change in administrative responsibility pursuant to paragraph 28 of Federal Facility Agreement (FFA) Docket Number 93-117 (FFA).
As you are aware, Andersen Air Force Base is in the process ofrealigning installation management functions to a newly established Joint Region Marianas pursuant to the 2005 Defense Base Closure and Realignment Commission Final and Approved Recommendations. Title to Andersen Air Force Base real property will remain in the United States and the property will continue to be utilized by the Air Force. As of October 1, 2009, however, administrative custody and responsibility for managing real property assets will transfer from the Air Force to the Navy. The Air Force will become a supported component of the Joint Region Marianas and the Navy will become the supporting component.
In accordance with the April 2008 Department of Defense Environmental Supplemental Guidance for Implementing and Operating a Joint Base, the Navy, as the suppmting component, "will be responsible for all existing andfature environmental permits, requirements, plans, and agreements at the installations to become the Joint Base." (Ch. 1.1.2). As the suppmting component, the Navy will be required to "honor all existing, previously negotiated Federal Facility Agreements in place at the installations to become the Joint Base at the time of transfer." (Ch. 2.17.5). The Navy is being supplied with an Environmental Condition of Prope1ty Repmt and with access to current environmental files including the FFA. No change to the FFA will be necessary in order for the Navy to assume responsibility for implementation of the FFA and the transfer ofresponsibility will not change the rights of the parties under the FF A or impede any action under the FF A. The Environmental staff will remain located at Andersen Air Force Base following 01 October 2009 and will be available to assist with any issues related to the FFA. However, the civilian environmental staff will become Navy employees and, likewise, funding responsibility will reside with the Navy. Please contact Mr. Russell Littlejohn, Environmental Flight Chief, at (671) 366-2556 if you have any questions or concerns or would like to discuss possible changes/addendums to the FFA to further document the substitution of the United States Navy for the United States Air Force as the entity responsible for implementation of the FFA.
Sincerely ~J!/.L__ GREGG IKEHARA Chief, Installation Restoration Program cc: Ms. Lorilee Crisostomo, GEPA Mr. Rich Howard, Tech Law Inc. DEPARTMENT OI" THE l\IAVY COMMAl~DER, JOINT REGION MARIANAS PSC 455, BOX '/ 52. FPO AP 96540-·/ 000
IN REPl Y REFER TO: 9510 Ser J4/1235 November 23,· 2009
Mr. Mark Ripperda US Enviromnental Protection Agency 7 5 Hawthorne St. H-9-4 San Francisco, CA 94105-3901
Dear Mr. Ripperda,
SUBJECT: NOTIFICATION OF TRANSFER OF ENVIRONMENTAL RESTORATION PROGRAM RESPONSIBILITY This letter serves as notification that all Enviromnental Restoration Program responsibilities for Andersen Air Force Base (AAFB), a property listed on the National Prio1ities List, will be officially transfened to the United States Navy under the Commander, Joint Region Maiianas (CJRM), effective October 1, 2009, pursuai1t to chapter 2.17 of the April 2008 Depaiiment of Defense Enviromnental Supplemental Guidance (EVSG) for Implementing ai1d Operating a Joint Base. This action is being talcen to implement the 2005 Defense Base Realignment and Closure (BRAC) Act which requires the transfer of all installation suppmi functions ai1d administrative custody of real prope1iy from AAFB to the U.S. Navy.
In accordance with the EVSG, the Navy, as the supporting component, "will assume responsibility for environmental restoration data repo1iing, budgeting, record keeping, and financial liability" (Ch. 2.17. 6), "will assume responsibility for all Restoration Advisory Boards" (Ch. 2.17.8), ai1d will be required to "honor all existing, previously negotiated Federal Facility Agreements in place at the installations to become the Joint Base (Region] at the time of transfer." (Ch. 2.17.5).
If you have any questions, please contact Mr. Richard Raines, P.E., at telephone (671) 339- 8420 or at [email protected]. Q:~~ P.S.LYNCH ~ Captain, CEC, U.S. NAVY Regional Engineer By direction of the Commander
Copy to: Guam Environmental Protection Agency CNIC (N45) NAVFAC Pacific (EV) 36CES DEPARTMENTOFTHEAIRFORCE HEADQUARTERS, 36TH WING (PACAF) UNIT 14007, APO AP 96543-4007
06 November 2009
36CES/CEVR Unit 14007 APO AP 96543-4007
Mr. Mark Ripperda Project Manager U.S. Environmental Protection Agency 75 Hawthorne St., H-9-4 San Francisco, CA 94105-3901
Dear Mr. Ripperda
This letter provides notice of a change in administrative responsibility pursuant to paragraph 28 of Federal Facility Agreement (FFA) Docket Number 93-117 (FFA).
As you are aware, Andersen Air Force Base is in the process of realigning installation management functions to a newly established Joint Region Marianas pursuant to the 2005 Defense Base Closure and Realignment Commission Final and Approved Recommendations. Title to Andersen Air Force Base real property will remain in the United States and ci1e property will continue to be utilized by the Air Force. As of October I, 2009, ho\vever, adtninistrative custody and responsibility for n1anaging real property assets will transfer from the Air Force to the Navy. The Air Force will become a supported component of the Joint Region Marianas and the Navy \Vill become the supporting coinponent. J In accordance with the April 2008 Department of Defense Environmental Supplemental Guidance for Implementing and Operating a Joint Base, the Navy, as the supporting component, "will be
responsible for all existing and.future enviro11111ental per111its1 require111ents, plans, a11d agree111ents al the insla/latio11s to become the Joint Bose. " (Ch. 1.1.2). As the suppotting component, the Navy will be required to ((honor all existing, previously negotiated Federal Facilit)1 Agree111e11ts in place al the i11stallotio11s to become the Joint Base at the time oftransfer." (Ch. 2.17.5). The Navy is being supplied with an Environmental Condition of Proper(y Repo1t and with access to current environmental files including the FFA. No change to theFFA will be necessary in order for the Navy to assume responsibility for implementation of the FFA and the transfer ofresponsibility will not change the rights of the parties under the FFA or impede any action under the FFA. The Environmental staff will remain located at Andersen Air Force Base following OJ October 2009 and will be available to assist with any issues related to the FFA. However, the civilian environmental staff will become Navy employees and, likewise, funding responsibility will reside with the Navy. ~, )
Please contact Mr. Russell Littlejohn, Environmental Flight Chief, at (671) 366-2556 if you have any questions or concerns or would like to discuss possible changes/addendums to the FFA to further document the substitution of the United States Navy for the United States Air Force as the entity responsible for implementation of the FFA.
Sincerely htf~ GREGG IKEHARA Chief, Installation Restoration Program cc: Ms. Lorilee Crisostomo, GEPA Mr. Rich Howard, Tech Law Inc. DEPARTMENT OF THE AIR FORCE HEADQUARTERS, 36TH WING (PACAF) UNIT 14007, APO AP 96543-4007
06 November 2009
36 CES/CEVR Unit 14007 APO AP 96543-4007
Ms. Lorilee Crisostomo Project Manager Guam Environmental Protection Agency P.O. Box 22439 GMF Barrigada, Guam 96921
Dear Ms. Crisostomo
This letter provides notice of a change in administrative responsibility pursuant to paragraph 28 of Federal Facility Agreement (FFA) Docket Number 93-117 (FFA).
As you are aware, Andersen Air Force Base is in the process of realigning installation management functions to a newly established Joint Region Marianas pursuant to the 2005 Defense Base Closure and Realignment Commission Final and Approved Recommendations. Title to Anderren Air Force Base real property will remain in the United States and the property will continue to be utilized by the Air Force. As of October 1, 2009, however, administrative custody and responsibility for managing real property assets will transfer from the Air Force to the Navy. The Air Force will become a suppmied component of the Joint Region Marianas and the Navy will become the supporting component.
In accordance with the April 2008 Department of Defense Environmental Supplemental Guidance for Implementing and Operating a Joint Base, the Navy, as the supporting component, "will be responsible for all existing andfature environmental permits, requirements, plans, and agreements at the installations to become the Joint Base. "(Ch. 1.1.2). As the supporting component, the Navy will be required to "honor all existing, previously negotiated Federal Facility Agreements in place at the installations to become the Joint Base at the time oftransfer. " (Ch. 2.17.5). The Navy is being supplied with an Environmental Condition of Property Report and with access to current environmental files including the FFA. No change to the FFA will be necessary in order for the Navy to assume responsibility for implementation of the FF A and the transfer of responsibility will not change the rights of the parties under the FFA or impede any action under the FFA. The Environmental staff will remain located at Andersen Air Force Base following 01 October 2009 and will be available to assist with any issues related to the FFA. However, the civilian environmental staff will become Navy employees and, likewise, funding responsibility will reside with the Navy. Please contact Mr. Russell Littlejohn, Environmental Flight Chief, at (671) 366-2556 if you have any questions or concerns or would like to discuss possible changes/addendums to the FFA to fi.nther document the substitution of the United States Navy for the United States Air Force as the entity responsible for implementation of the FFA.
Sincerely j~~L GREGG IKEHARA Chief, Installation Restoration Program cc: Mr. Mark Ripperda, USEP A Mr. Rich Howard, Tech Law Inc.
Appendix B Responsiveness Summary and Response to Regulatory Comments
RESPONSE TO REVIEW COMMENTS Draft Record of Decision for Sites 10, 13, 15, 26, and 27 Andersen Air Force Base, Guam July 2010 Review Comments Received September 2010 from U.S. EPA Reviewer: Mark Ripperda
ITEM PAGE SECTION COMMENT 1. Section 1.2 Add the footnotes concerning Navy and AF joint basing as discussed for the other and 1.5 RODs under review. Response: Per October 3 email from Gregg Ikehara, the following language has been added to Section 1.2: "The Department of Defense is in the process of realigning installation management functions at Andersen Air Force Base. On October 1, 2009, pursuant to the 2005 Defense Base Closure and Realignment Commission Report, administrative custody of all real property on Andersen Air Force Base and responsibility for installation support functions, including Environmental Restoration Program responsibilities, transferred within the Department of Defense from the Department of the Air Force to the Department of the Navy. Title to Andersen Air Force Base real property will remain with the United States and the Air Force will continue to utilize the Base. The Navy will also utilize portions of the Base. In accordance with the April 15 2008, Department of Defense Environmental Supplemental Guidance for Implementing and Operating a Joint Base, at the time of property transfer the Navy, as the new property manager at the Base, assumed responsibility ufor all existing and future environmental permits, requirements, plans, and agreements" at the Base (Ch. 1.1.2) and was required to "honor all existing, previously negotiated Federal Facility Agreements in place." (Ch. 2.17.5 of the Guidance). In January 2009, the Navy and the Air Force entered into a separate Memorandum of Agreement, which delegated installation support and authority back to the Air Force General who is the Andersen Base Commanding Officer under the authority, control, and direction of the Joint Region Commander, who is a Navy Admiral. This delegation includes the authority to sign Records of Decision. The Andersen BCO and Andersen environmental staff continue to administer the FFA under Navy direction. Both the Air Force and the Navy notified EPA of the change of administrative responsibility under the FFA (Appendix C)." Also per the email, the following language has been added on signature sheet following "Base Commanding Officer" in the General's printed title line: "Under Delegation of Authority from Commander Joint Region Marianas". Lastly, an Appendix has been added which will consist of the two FFA notice letters, one from the Air Force and one from the Navy. 2. Section 1.3 Change the last sentence to: Per the NCP (40 Code of Federal Regulations [CFR] 300.430(e)(6)), the U.S. Navy and U.S. EPA have co·selected no action for Sites 10, 13, 15, 26, and 27. RESPONSE TO REVIEW COMMENTS Draft Record of Decision for Sites 10, 13, 15, 26, and 27 Andersen Air Force Base, Guam July 2010 Review Comments Received September 2010 from U.S. EPA Reviewer: Mark Ripperda
Response: The last sentence of this section has been changed to: "Per the NCP (40 Code of Federal Regulations [CFR] 300.430(e)(6)), the U.S. Navy and U.S. EPA have co-selected no action for Sites 10, 13, 15, 26, and 27." 3. Section 1.4 There are no statutory requirements or ARARs with a no action remedy. You can Delete Section 1.4 and change the heading of Section 1.3 to: Selected Remedy and Statutory Determinations. The current language in Section 1. 3 addresses the requirements in the EPA Guidance on preparing RODs, highlight 8-4. Response: Section 1.4 has been deleted. The heading for Section 1.3 has been changed to: "Selected Remedy and Statutory Determinations." 4. Section 1.5.1 Change the text to: This signature sheet documents U.S. Navy co-selection of the remedy in this ROD for ... Response: The text in this section has been changed to: "This signature sheet documents U.S. Navy co-selection of the remedy in this ROD for Sites 10, 13, 15, 26, and 27 at Andersen AFB, Guam." 5. Section 1.5.2 Change the text to: This signature sheet documents U.S. EPA co-selection of the remedy in this ROD for ... Response: The ·text in this section has been changed to: "This signature sheet documents U.S. EPA co-selection of the remedy in this ROD for Sites 10, 13, 15, 26, and 27 at Andersen AFB, Guam." 6 . Section The section ends with a recommendation from the 2003 EE/CA for subsurface soil 2.2.7. 2.1 excavation for arsenic. There is no discussion on when or if this excavation took place. Please either add the excavation information. or if it didn't happen, a reference as to why. Response: The following paragraph has been added to the end of this section: "However, an updated risk assessment performed for Site 13 as part of the 201 O RI concluded that site-specific soil conditions measured at the site possess sufficient binding potential to effectively reduce the bioavaifability of the metals, thereby reducing potential site risks to within, or below, the EPA acceptable risk range of 1E-04 to 1E-06 for all receptors." RESPONSE TO REVIEW COMMENTS Draft Record of Decision for Sites 10, 13, 15, 26, and 27 Andersen Air Force Base, Guam July 2010 Review Comments Received September 2010 from U.S. EPA Reviewer: Mark Ripperda
7. Table 2-3 Please remove the inhalation EPC column. The soil screening criteria includes an inhalation pathway that applies standard assumptions to airborne soil. Please add a column showing the EPA PRGs or RSLs that were used in the screening analysis.
Res~onse : The inhalation EPC column has been removed from Table 2-3. A column showing EPA RSLs has been added. 8. Section 2.7 A table summarizing the risks for surface and subsurface soil for all the sites is a useful tool. With multiple sites, it can be difficult to find the final risks in the midst of all the explanatory text. Please show both total and incremental risk in the table. A typical format is [provided but not copied here]: Response: Table 2-8 has been included in Section 2.7 that reflects the format and information contained in the example. 9. Section 2.8 Please delete this section. The EPA guidance (Highlight 8-4) specifies that this is not applicable for a No Action Decision. Response: Section 2.8 has been deleted.
Appendix C Risk Characterization Tables
Table C-1.1: Site 10 Risk Summary Current/Future Current/Future Future Occupational Worker Excavation/Construction Worker Resident (Adult) EPC Ingestion & Cumulative Ingestion & Cumulative Ingestion & Cumulative Medium COC (mg/kg) Dermal Inhalation Risk Dermal Inhalation Risk Dermal Inhalation Risk Carcinogenic Risk Surface Soil Benzo(a)anthracene 0.0683 3.24E–08 n/a 3.24E–08 3.20E–08 n/a 3.20E–08 1.10E–07 n/a 1.10E–07 Benzo(a)pyrene 0.0779 3.69E–07 n/a 3.69E–07 3.65E–07 n/a 3.65E–07 1.26E–06 n/a 1.26E–06 Benzo(b)fluoranthene 0.0723 3.43E–08 n/a 3.43E–08 3.38E–08 n/a 3.38E–08 1.16E–07 n/a 1.17E–07 (dermal & ingestion) Benzo(b)fluoranthene 5.92E–09 a n/a 5.28E–11 n/a n/a n/a 6.78E–10 (inhalation) Dibenz(a,h)anthracene 0.0112 5.32E–08 n/a 5.32E–08 5.25E–08 n/a 5.25E–08 1.81E–07 n/a 1.81E–07 Indeno(1,2,3-cd)pyrene 0.0563 2.67E–08 n/a 2.67E–08 2.64E–08 n/a 2.64E–08 9.08E–08 n/a 9.08E–08 Subsurface Benzo(a)anthracene 0.0448 2.12E–08 n/a 2.12E–08 2.10E–08 n/a 2.10E–08 7.22E–08 n/a 7.22E–08 Soil Benzo(a)pyrene 0.0779 2.40E–07 n/a 2.40E–07 2.37E–07 n/a 2.37E–07 8.17E–07 n/a 8.17E–07 Benzo(b)fluoranthene 0.0723 3.01E–08 n/a 3.01E–08 2.97E–08 n/a 2.97E–08 1.02E–07 n/a 1.03E–07 (dermal & ingestion) Benzo(b)fluoranthene 5.19E–09 a n/a 4.64E–11 n/a n/a n/a 5.95E–10 (inhalation) Dibenz(a,h)anthracene 0.0519 4.15E–08 n/a 4.15E–08 4.10E–08 n/a 4.10E–08 1.41E–07 n/a 1.41E–07 Indeno(1,2,3-cd)pyrene 0.05194 2.46E–08 n/a 2.46E–08 2.43E–08 n/a 2.43E–08 8.37E–08 n/a 8.37E–08 Surface Soil risk total = 5.0E–07 n/a n/a 5.0E–07 n/a n/a 2.0E–06 Subsurface Soil risk total = 4.0E–07 n/a n/a 4.0E–07 n/a n/a 1.0E–06 Non-Carcinogenic Hazard Quotient n/a for Site 10 COC chemical of concern EPC exposure point concentration n/a not applicable a Measured in milligrams per cubic meter (mg/m3) of air.
Table C-2.1: Site 13 Cancer Risk Summary Carcinogenic Risk Current/Future Current/Future Future Occupational Worker Excavation/Construction Worker Resident (Adult) EPC Medium COC (mg/kg) Ingestion & Dermal Inhalation Cumulative Risk Ingestion & Dermal Inhalation Cumulative Risk Ingestion & Dermal Inhalation Cumulative Risk Surface Soil Aroclor 1260 0.0158 2.13E–08 n/a 2.13E–08 2.07E–08 n/a 2.07E–08 7.14E–08 n/a 7.14E–08 Benzo(a)anthracene 0.0291 1.38E–08 n/a 1.38E–08 1.36E–08 n/a 1.36E–08 4.69E–08 n/a 4.69E–08 Benzo(a)pyrene 0.0742 1.70E–06 n/a 1.70E–06 1.68E–06 n/a 1.68E–06 5.79E–06 n/a 5.79E–06 Benzo(b)fluoranthene 0.0626 1.24E–07 n/a 1.24E–07 1.22E–07 n/a 1.22E–07 4.21E–07 n/a 4.21E–07 (dermal & ingestion) Benzo(b)fluoranthene 5.13E–09 a n/a 4.58E–11 n/a n/a n/a 5.87E-10 (inhalation) Dibenz(a,h)anthracene 0.0965 1.48E–06 n/a 1.48E–06 1.46E–06 n/a 1.46E–06 5.04E–06 n/a 5.04E–06 Indeno(1,2,3-cd)pyrene 0.192 2.05E–07 n/a 2.05E–07 2.03E–07 n/a 2.03E–07 6.97E–07 n/a 6.97E–07 4,4’-DDT 0.0158 2.72E–08 n/a 2.72E–08 3.27E–08 n/a 3.27E–08 1.12E–07 n/a 1.12E–07 Arsenic 26.8 1.68E–05 n/a 1.68E–05 2.02E–05 n/a 2.02E–05 6.89E–05 n/a 6.89E–05 Cadmium 12 1.29E–09 n/a 1.29E–09 8.08E-10 n/a 8.08E-10 8.27E–09 n/a 8.27E–09 Chromium 331.3 2.37E–07 n/a 2.37E–07 1.49E–07 n/a 1.49E–07 1.52E–06 n/a 1.52E–06 Cobalt 31.67 1.70E–08 n/a 1.70E–08 1.07E–08 n/a 1.07E–08 1.09E–07 n/a 1.09E–07 Subsurface Soil Aroclor 1260 0.0158 2.05E–08 n/a 2.05E–08 1.99E–08 n/a 1.99E–08 6.87E–08 n/a 6.87E–08 Benzo(a)anthracene 0.0291 1.50E–08 n/a 1.50E–08 1.49E–08 n/a 1.49E–08 5.12E–08 n/a 5.12E–08 Benzo(a)pyrene 0.0742 7.27E–07 n/a 7.27E–07 7.18E–07 n/a 7.18E–07 2.47E–06 n/a 2.47E–06 Benzo(b)fluoranthene 0.0626 1.24E–07 n/a 1.24E–07 1.22E–07 n/a 1.22E–07 4.21E–07 n/a 4.21E–07 (dermal & ingestion) Benzo(b)fluoranthene 5.85E–09 a n/a 5.22E–11 n/a n/a n/a 6.70E-10 (inhalation) Dibenz(a,h)anthracene 0.0965 1.29E–06 n/a 1.29E–06 1.28E–06 n/a 1.28E–06 4.40E–06 n/a 4.40E–06 Indeno(1,2,3-cd)pyrene 0.192 1.77E–07 n/a 1.77E–07 1.75E–07 n/a 1.75E–07 6.01E–07 n/a 6.01E–07 4,4’-DDT 0.0158 2.30E–08 n/a 2.30E–08 2.77E–08 n/a 2.77E–08 9.43E–08 n/a 9.43E–08 Arsenic 26.8 2.39E–05 n/a 2.39E–05 2.87E–05 n/a 2.87E–05 9.79E–05 n/a 9.79E–05 Cadmium 12 1.18E–09 n/a 1.18E–09 7.39E-10 n/a 7.39E-10 7.56E–09 n/a 7.56E–09 Chromium 331.3 2.64E–07 n/a 2.64E–07 1.65E–07 n/a 1.65E–07 1.69E–06 n/a 1.69E–06 Cobalt 31.67 1.56E–08 n/a 1.56E–08 9.79E–09 n/a 9.79E–09 1.00E–07 n/a 1.00E–07 Surface Soil Risk Total = 2.0E–05 n/a n/a 2.0E–05 n/a n/a 8.0E–05 Subsurface Soil Risk Total = 3.0E–05 n/a n/a 3.0E–05 n/a n/a 1.0E–04 COC chemical of concern DDT dichlorodiphenyltrichloroethane EPC exposure point concentration n/a not applicable a Measured in milligrams per cubic meter (mg/m3) of air.
Table C-2.2: Site 13 Non-Cancer Risk Summary Non-Carcinogenic Hazard Quotient Current/Future Current/Future Future Future Occupational Worker Excavation/Construction Worker Resident (Adult) Resident (Child) EPC Ingestion & Medium COC (mg/kg) Dermal Inhalation Cumulative HI Ingestion & Dermal Inhalation Cumulative HI Ingestion & Dermal Inhalation Cumulative HI Ingestion & Dermal Inhalation Cumulative HI Surface Soil 4,4’-DDT 0.0158 4.49E–04 n/a 4.49E–04 1.35E–03 n/a 1.35E–03 5.87E–04 n/a 5.87E–04 5.31E–03 n/a 5.31E–03 Antimony 5.068 1.29E–02 n/a 1.29E–02 4.17E–02 n/a 4.17E–02 1.78E–02 n/a 1.78E–02 1.65E–01 n/a 1.65E–01 Arsenic 26.8 1.05E–01 n/a 1.05E–01 3.14E–01 n/a 3.14E–01 1.37E–01 n/a 1.37E–01 1.24E+00 n/a 1.24E+00 Cadmium 12 1.48E–02 n/a 1.48E–02 4.34E–02 n/a 4.34E–02 1.91E–02 n/a 1.91E–02 1.71E–01 n/a 1.71E–01 Chromium 331.3 1.63E–01 n/a 1.63E–01 4.40E–01 n/a 4.40E–01 2.00E–01 n/a 2.00E–01 1.72E+00 n/a 1.72E+00 Cobalt 31.67 1.05E–01 n/a 1.05E–01 3.43E–01 n/a 3.43E–01 1.49E–01 n/a 1.49E–01 1.36E+00 n/a 1.36E+00 Copper 345.1 8.50E–03 n/a 8.50E–03 2.79E–02 n/a 2.79E–02 1.19E–02 n/a 1.19E–02 1.11E–01 n/a 1.11E–01 Iron 68,640 9.66E–02 n/a 9.66E–02 3.18E–01 n/a 3.18E–01 1.35E–01 n/a 1.35E–01 1.26E+00 n/a 1.26E+00 Manganese 3,723 3.86E–02 n/a 3.86E–02 1.06E–01 n/a 1.06E–01 8.89E–02 n/a 8.89E–02 4.64E–01 n/a 4.64E–01 Mercury 7.621 2.50E–02 n/a 2.50E–02 8.23E–02 n/a 8.23E–02 3.50E–02 n/a 3.50E–02 3.26E–01 n/a 3.26E–01 Thallium 1.167 1.77E–02 n/a 1.77E–02 5.80E–02 n/a 5.80E–02 2.47E–02 n/a 2.47E–02 2.30E–01 n/a 2.30E–01 Subsurface 4,4’-DDT 0.0158 3.80E–04 n/a 3.80E–04 1.14E–03 n/a 1.14E–03 4.97E–04 n/a 4.97E–04 4.49E–03 n/a 4.49E–03 Soil Antimony 4.66 1.19E–02 n/a 1.19E–02 3.84E–02 n/a 3.84E–02 1.64E–02 n/a 1.64E–02 1.52E–01 n/a 1.52E–01 Arsenic 26.8 1.49E–01 n/a 1.49E–01 4.46E–01 n/a 4.46E–01 1.94E–01 n/a 1.94E–01 1.76E+00 n/a 1.76E+00 Cadmium 12 1.36E–02 n/a 1.36E–02 3.97E–02 n/a 3.97E–02 1.74E–02 n/a 1.74E–02 1.56E–01 n/a 1.56E–01 Chromium 331.3 1.82E–01 n/a 1.82E–01 4.88E–01 n/a 4.88E–01 2.22E–01 n/a 2.22E–01 1.91E+00 n/a 1.91E+00 Cobalt 31.67 9.63E–02 n/a 9.63E–02 3.15E–01 n/a 3.15E–01 1.37E–01 n/a 1.37E–01 1.25E+00 n/a 1.25E+00 Copper 228 5.61E–03 n/a 5.61E–03 1.85E–02 n/a 1.85E–02 7.84E–03 n/a 7.84E–03 7.31E–02 n/a 7.31E–02 Iron 71,028 9.99E–02 n/a 9.99E–02 3.29E–01 n/a 3.29E–01 1.40E–01 n/a 1.40E–01 1.30E+00 n/a 1.30E+00 Manganese 3,267 3.39E–02 n/a 3.39E–02 9.27E–02 n/a 9.27E–02 7.80E–02 n/a 7.80E–02 4.08E–01 n/a 4.08E–01 Mercury 6.549 2.15E–02 n/a 2.15E–02 7.07E–02 n/a 7.07E–02 3.00E–02 n/a 3.00E–02 2.80E–01 n/a 2.80E–01 Thallium 1.156 1.75E–02 n/a 1.75E–02 5.76E–02 n/a 5.76E–02 2.45E–02 n/a 2.45E–02 2.28E–01 n/a 2.28E–01 Surface Soil Risk Total = 0.6 n/a 2.0 n/a n/a 0.8 n/a n/a 7.0 Subsurface Soil Risk Total = 0.6 n/a 2.0 n/a n/a 0.9 n/a n/a 8.0 HI hazard index n/a not applicable Table C-3.1: Site 15 Cancer Risk Summary Carcinogenic Risk Current/Future Current/Future Future Occupational Worker Excavation/Construction Worker Resident (Adult) EPC Medium COC (mg/kg) Ingestion & Dermal Inhalation Cumulative Risk Ingestion & Dermal Inhalation Cumulative Risk Ingestion & Dermal Inhalation Cumulative Risk Surface Soil Benzo(a)pyrene 0.05321 2.52E–07 n/a 2.52E–07 2.49E–07 n/a 2.49E–07 8.58E–07 n/a 8.58E–07 Subsurface Soil Aroclor 1260 0.049 6.65E–08 n/a 6.65E–08 6.48E–08 n/a 6.48E–08 2.23E–07 2.23E–07 Benzo(a)pyrene 0.02805 1.34E–07 n/a 1.34E–07 1.32E–07 n/a 1.32E–07 4.54E–07 n/a 4.54E–07 α-chlordane 0.501 9.36E–08 n/a 9.52E–08 1.00E–07 n/a 1.00E–07 3.44E–07 n/a 3.64E–07 (dermal & ingestion) α-chlordane 1.91E–07 a n/a 1.55E–09 n/a n/a n/a 1.99E–08 (inhalation) Dieldrin 0.01739 2.26E–07 n/a 2.26E–07 2.05E–07 n/a 2.05E–07 7.11E–07 n/a 7.16E–07 (dermal & ingestion) Dieldrin 1.12E–08 a n/a 4.18E-10 n/a n/a n/a 5.35E–09 (inhalation) Γ-chlordane 0.688 1.29E–07 n/a 1.31E–07 1.38E–07 n/a 1.38E–07 4.72E–07 n/a 5.00E–07 (dermal & ingestion) Γ-chlordane 2.63E–07 a n/a 2.13E–09 n/a n/a n/a 2.74E–08 (inhalation) Heptachlor epoxide 0.04859 3.58E–07 n/a 3.58E–07 3.26E–07 n/a 3.26E–07 1.13E–06 n/a 1.13E–06 p-p’-DDE 0.3219 8.87E–08 n/a 8.87E–08 8.08E–08 n/a 8.08E–08 2.80E–07 n/a 2.80E–07 (dermal & ingestion) p-p’-DDE 1.40E–09 a n/a n/a n/a n/a n/a n/a (inhalation) Surface Soil Risk Total = 3.E–07 n/a n/a 2.E–07 n/a n/a 9.E–07 Subsurface Soil Risk Total = 1.E–06 n/a n/a 1.E–06 n/a n/a 4.E–06 COC chemical of concern DDE dichlorodiphenyldichloroethylene EPC exposure point concentration n/a not applicable a Measured in milligrams per cubic meter (mg/m3) of air.
Table C-3.2: Site 15 Non-Cancer Risk Summary Non-Carcinogenic Hazard Quotient Current/Future Current/Future Future Future Occupational Worker Excavation/Construction Worker Resident (Adult) Resident (Child) EPC Ingestion & Medium COC (mg/kg) Dermal Inhalation Cumulative HI Ingestion & Dermal Inhalation Cumulative HI Ingestion & Dermal Inhalation Cumulative HI Ingestion & Dermal Inhalation Cumulative HI Surface Soil Not applicable Subsurface α-chlordane 0.501 1.50E–03 n/a 1.56E–03 4.01E–03 n/a 4.01E–03 1.81E–03 n/a 2.33E–03 1.57E–02 n/a 1.69E–02 Soil (dermal & ingestion) α-chlordane 1.91E–07 n/a 6.21E–05 n/a n/a n/a 5.22E–04 n/a 1.23E–03 (inhalation) Dieldrin 0.01739 7.90E–04 n/a 7.90E–04 1.80E–03 n/a 1.80E–03 8.57E–04 n/a 8.57E–04 6.94E–03 n/a 6.94E–03 Γ-chlordane (dermal & 0.688 2.06E–03 n/a 2.14E–03 5.51E–03 n/a 5.51E–03 2.49E–03 n/a 3.20E–03 2.15E–02 n/a 2.32E–02 ingestion) Γ-chlordane (inhalation) 2.63E–07 n/a 8.53E–05 n/a n/a n/a 7.17E–04 n/a 1.69E–03 Heptachlor epoxide 0.04859 8.48E–03 n/a 8.48E–03 1.93E–02 n/a 1.93E–02 9.21E–03 n/a 9.21E–03 7.45E–02 n/a 7.45E–02 Surface Soil Risk Total = 0.0 n/a n/a 0.0 n/a n/a 0.0 n/a n/a 0.0 Subsurface Soil Risk Total = 0.01 n/a n/a 0.03 n/a n/a 0.02 n/a n/a 0.01 HI hazard index n/a not applicable Table C-4.1: Site 26 Cancer Risk Summary Carcinogenic Risk Current/Future Current/Future Future Occupational Worker Excavation/Construction Worker Resident (Adult) EPC Medium COC (mg/kg) Ingestion & Dermal Inhalation Cumulative Risk Ingestion & Dermal Inhalation Cumulative Risk Ingestion & Dermal Inhalation Cumulative Risk Surface Soil Dioxins, TEQ (ng/kg) 4.08E–05 2.22E–06 n/a 2.22E–06 2.67E–06 n/a 2.67E–06 9.09E–06 n/a 9.09E–06 Benzo(a)anthracene 2.5 1.18E–06 n/a 1.18E–06 1.17E–06 n/a 1.17E–06 4.03E–06 n/a 4.03E–06 Benzo(a)pyrene 4.6 2.18E–05 n/a 2.18E–05 2.15E–05 n/a 2.15E–05 7.41E–05 n/a 7.41E–05 Benzo(b)fluoranthene 7.2 3.41E–06 n/a 3.41E–06 3.37E–06 n/a 3.37E–06 1.16E–05 n/a 1.16E–05 (dermal & ingestion) Benzo(b)fluoranthene 6.17E–08 a n/a 5.51E-10 n/a n/a n/a n/a 7.07E–09 (inhalation ) Benzo(k)fluoranthene 2.3 1.09E–07 n/a 1.09E–07 1.08E–07 n/a 1.08E–07 3.71E–07 n/a 3.71E–07 Indeno(1,2,3-cd)pyrene 1.6 7.58E–07 n/a 7.58E–07 1.6 7.49E–07 n/a 2.58E–06 n/a 2.58E–06 Ethylbenzene 12 4.61E–08 n/a 5.81E–08 6.09E–08 n/a 6.09E–08 2.07E–07 n/a 3.34E–07 (dermal & ingestion) Ethylbenzene 5.87E–05 a n/a 1.19E–08 n/a n/a n/a n/a 1.27E–07 (inhalation ) Subsurface Soil Aroclor 1254 0.335 3.27E–07 n/a 3.27E–07 6.09E–08 n/a 6.09E–08 1.25E–06 n/a 1.25E–06 Dioxins, TEQ 4.08E–05 2.22E–06 n/a 2.22E–06 3.65E–07 n/a 3.65E–07 9.09E–06 n/a 9.09E–06 Benzo(a)anthracene 2.5 1.18E–06 n/a 1.18E–06 2.67E–06 n/a 2.67E–06 4.03E–06 n/a 4.03E–06 Benzo(a)pyrene 4.6 2.18E–05 n/a 2.18E–05 1.17E–06 n/a 1.17E–06 7.41E–05 n/a 7.41E–05 Benzo(b)fluoranthene 7.2 3.41E–06 n/a 3.41E–06 2.15E–05 n/a 2.15E–05 1.16E–05 n/a 1.16E–05 (dermal & ingestion) Benzo(b)fluoranthene 6.17E–08 a n/a 5.51E-10 3.37E–06 n/a 3.37E–06 n/a 7.07E–09 (inhalation ) (mg/m3) Benzo(k)fluoranthene 2.3 1.09E–07 n/a 1.09E–07 1.08E–07 n/a 1.08E–07 3.71E–07 n/a 3.71E–07 Indeno(1,2,3-cd)pyrene 1.6 7.58E–07 n/a 7.58E–07 7.49E–07 n/a 7.49E–07 2.58E–06 n/a 2.58E–06 Ethylbenzene 12 4.61E–08 n/a 8.76E–06 6.09E–08 n/a 6.09E–08 2.07E–07 n/a 1.12E–04 (dermal & ingestion) Ethylbenzene 4.92E–02 a n/a 8.71E–06 n/a n/a n/a n/a 1.11E–04 (inhalation ) (mg/m3) Tetrachloroethene 25.4 1.04E–05 n/a 7.97E–05 9.85E–06 n/a 9.85E–06 5.37E–05 n/a 7.94E–04 (dermal & ingestion) Tetrachloroethene 9.56E–06 a n/a 6.93E–05 n/a n/a n/a 7.41E–04 (inhalation)(mg/m3) Surface Soil Risk Total = 3.0E–05 n/a n/a 3.0E–05 n/a n/a 1.0E–04 Subsurface Soil Risk Total = 1.0E–04 n/a n/a 4.0E–05 n/a n/a 1.0E–03 COC chemical of concern EPC exposure point concentration n/a not applicable a Measured in milligrams per cubic meter (mg/m3) of air.
Table C-4.2: Site 26 Non-Cancer Risk Summary Non-Carcinogenic Hazard Quotient Current/Future Current/Future Future Future Occupational Worker Excavation/Construction Worker Resident (Adult) Resident (Child) EPC Ingestion & Medium COC (mg/kg) Dermal Inhalation Cumulative HI Ingestion & Dermal Inhalation Cumulative HI Ingestion & Dermal Inhalation Cumulative HI Ingestion & Dermal Inhalation Cumulative HI Surface Soil Dioxins, TEQ 4.08E–05 4.78E–02 n/a 4.78E–02 1.44E–01 n/a 1.44E–01 6.26E–02 n/a 6.26E–02 5.65E–01 n/a 5.65E–01 Ethylbenzene 12 1.17E–04 n/a 1.31E–04 3.87E–04 n/a 3.87E–04 1.64E–04 n/a 2.58E–04 1.53E–03 n/a 1.75E–03 (dermal & ingestion) Ethylbenzene 5.87E–05 n/a 1.34E–05 n/a n/a n/a n/a 9.35E–05 n/a 2.21E–04 (inhalation) Subsurface Aroclor 1254 0.335 2.29E–02 n/a 2.29E–02 6.39E–02 n/a 6.39E–02 2.85E–02 n/a 2.85E–02 2.51E–01 n/a 2.51E–01 Soil Dioxins, TEQ 4.08E–05 4.78E–02 n/a 4.78E–02 1.44E–01 n/a 1.44E–01 6.26E–02 n/a 6.26E–02 5.65E–01 n/a 5.65E–01 Ethylbenzene 12 1.17E–04 n/a 9.87E–03 3.87E–04 n/a 3.87E–04 1.64E–04 n/a 8.18E–02 1.53E–03 n/a 1.94E–01 (dermal & ingestion) Ethylbenzene 4.29E–02 n/a 9.75E–03 n/a n/a n/a n/a 8.17E–02 n/a 1.93E–01 (inhalation) Tetrachloroethene 25.4 1.12E–02 n/a 1.33E–01 2.19E–02 n/a 2.19E–02 3.85E–02 n/a 3.85E-02 1.17E–01 n/a 1.17E-01 (dermal & ingestion) Tetrachloroethene 9.56E–06 n/a 1.22E–01 n/a n/a n/a 6.77E–05 n/a 1.6E-04 (inhalation) Surface Soil Risk Total = 0.05 n/a n/a 0.1 n/a n/a 0.06 n/a n/a 0.6 Subsurface Soil Risk Total = 0.2 n/a n/a 0.2 n/a n/a 0.1 n/a n/a 0.9 HI hazard index n/a not applicable Table C-5.1: Site 27 Cancer Risk Summary Carcinogenic Risk Current/Future Current/Future Future Occupational Worker Excavation/Construction Worker Resident (Adult) EPC Medium COC (mg/kg) Ingestion & Dermal Inhalation Cumulative Risk Ingestion & Dermal Inhalation Cumulative Risk Ingestion & Dermal Inhalation Cumulative Risk Surface Soil Benzo(a)pyrene 0.01872 8.87E-08 n/a 8.87E-08 8.76E-08 n/a 8.76E-08 3.02E-07 n/a 3.02E-07 Benzo(b)fluoranthene 0.05027 2.38E-08 n/a 2.38E-08 2.35E-08 n/a 2.35E-08 8.10E-08 n/a 8.11E-08 (dermal & ingestion) Benzo(b)fluoranthene 8.4E–10 n/a 7.51E-12 n/a n/a n/a 9.63E-11 (inhalation) Dibenz(a,h)anthracene 0.01511 7.16E-08 n/a 7.16E-08 7.07E-08 n/a 7.07E-08 2.44E-07 n/a 2.44E-07 Subsurface Soil Arsenic 21.76 3.67E-08 n/a 3.67E-08 4.40E-05 n/a 4.40E-05 1.50E-04 n/a 1.50E-04 Chromium 192.2 4.19E-07 n/a 4.19E-07 2.62E-07 n/a 2.62E-07 n/a n/a n/a Cobalt 4.09 4.77E-09 n/a 4.77E-09 2.99E-09 n/a 2.99E-09 n/a n/a n/a Benzo(a)pyrene 0.01872 8.87E-08 n/a 8.87E-08 8.76E-08 n/a 8.76E-08 3.02E-07 n/a 3.02E-07 Benzo(b)fluoranthene 0.04844 2.30E-08 n/a 2.38E-08 2.27E-08 n/a 2.27E-08 7.81E-08 n/a 7.82E-08 (dermal & ingestion) Benzo(b)fluoranthene 8.10E–10 n/a 7.23E-12 n/a n/a n/a 9.28E-11 (inhalation) Dibenz(a,h)anthracene 0.01511 7.16E-08 n/a 7.16E-08 7.07E-08 n/a 7.07E-08 2.44E-07 n/a 2.44E-07 Soil Gas Chloroform 1.65E–06 n/a 3.08E-09 3.08E-09 n/a n/a n/a n/a 3.95E-08 3.95E-08 (mg/m3) Tetrachloroethene 1.99E–04 n/a 9.57E-08 9.57E-08 n/a n/a n/a n/a 1.23E-06 1.23E-06 Trichloroethene 6.04E–05 n/a 9.82E-09 9.82E-09 n/a n/a n/a n/a 1.26E-07 1.26E-07 Surface Soil Risk Total = 3.0E-07 n/a n/a 2.0E-07 n/a n/a 2.0E-06 Subsurface Soil Risk Total = 4.0E-07 n/a n/a 4.0E-05 n/a n/a 2.0E-04 Soil Gas Risk Total = 1.9E-07 n/a n/a n/a n/a n/a 1.4E-06 COC chemical of concern EPC exposure point concentration n/a not applicable a Measured in milligrams per cubic meter (mg/m3) of air.
Table C-5.2: Site 27 Non-Cancer Risk Summary Non-Carcinogenic Hazard Quotient Current/Future Current/Future Future Future Occupational Worker Excavation/Construction Worker Resident (Adult) Resident (Child) EPC Ingestion & Ingestion & Medium COC (mg/kg) Dermal Inhalation Cumulative HI Ingestion & Dermal Inhalation Cumulative HI Ingestion & Dermal Inhalation Cumulative HI Dermal Inhalation Cumulative HI Surface Soil Not applicable Subsurface Aluminum 112,886 0.117 n/a 0.117 0.374 n/a 0.374 0.178 n/a 0.178 1.50 n/a 1.50 Soil Arsenic 21.76 0.228 n/a 0.228 0.685 n/a 0.685 0.298 n/a 0.298 2.70 n/a 2.70 Chromium 192.2 0.288 n/a 0.288 0.776 n/a 0.776 0.314 n/a 0.314 2.78 n/a 2.78 Cobalt 4.09 0.029 n/a 0.029 0.0961 n/a 0.0961 0.041 n/a 0.041 0.382 n/a 0.382 Iron 51,912 0.073 n/a 0.073 0.240 n/a 0.240 0.102 n/a 0.102 0.951 n/a 0.951 Soil Gas Chloroform 1.65E–06 n/a 3.83E-06 3.83E-06 n/a n/a n/a n/a 3.22E-05 3.22E-05 n/a 7.60E-05 7.60E-05 (mg/m3) Tetrachloroethene 1.99E–04 n/a 1.68E-04 1.68E-04 n/a n/a n/a n/a 1.41E-03 1.41E-03 n/a 3.33E-03 3.33E-03 Trichloroethene 6.04E–05 n/a 3.44E-04 3.44E-04 n/a n/a n/a n/a 2.89E-03 2.89E-03 n/a 6.83E-03 6.83E-031 Surface Soil Risk Total = 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 Subsurface Soil Risk Total = 0.7 n/a n/a 2.0 n/a n/a 1.0 n/a n/a 9.0 Soil Gas Risk Total = 5.1E-041 n/a n/a n/a n/a n/a 4.0E-031 n/a n/a 0.01 HI hazard index n/a not applicable