EPA Superfimd
Record of Decision:
Mountain Home Air Force
Base (O.U. 1, 3, 5, 6), ID
9/27/1995
PB95-964614
EPA/ROD/R10-95/124
January 1996
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RECORD OF DECISION
FOR
MOUNTAIN HOME AIR FORCE BASE
OPERABLE UNITS NOS. 1, 3, 5, 6
LAGOON LANDFILL AND FHUE TRAINING AREA 8
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Table of Contents
DECLARATION FOR THE RECORD OF DECISION
DECISION SUMMARY
I. SITE NAME, AND LOCATION 1
II. SITE HISTORY AND ENFORCEMENT ACTIVITIES 5
A. SITE HISTORY 5
B. ENFORCEMENT ACTIVITIES 18
III. HIGHLIGHTS OF COMMUNITY PARTICIPATION 18
IV. SCOPE AND ROLE OF OPERABLE UNIT 20
V. SUMMARY OF SITE CHARACTERISTICS 20
A. TOPOGRAPHY, SURFACE FEATURES, AND CLIMATE 20
B. REGIONAL AND SITE GEOLOGY 21
1. Regional Geology 21
2. Site Geology 21
C. SOILS 22
D. HYDROGEOLOGY 22
E. SURFACE WATER HYDROLOGY 23
F. NATURE AND EXTENT OF CONTAMINATION 23
1. Soils .• 25
2. Surface Water and Sediment 38
3. Perched Groundwater 41
4. Regional Groundwater 42
4.1 Pre-RI Investigations 42
4.2 Remedial Investigation Results 43
G. GROUNDWATER MODELING RESULTS 46
H. POTENTIALLY EXPOSED POPULATION 50
VI. SUMMARY OF SITE RISKS 51
A. HUMAN HEALTH RISKS 51
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1. Contaminant Identification -51-
2. Exposure Assessment -51-
3. Toxicity Assessment -55-
4. Risk Characterization -56-
B. ENVIRONMENTAL RISKS -63-
C. SUMMARY OF SITE RISK CONCLUSION -64-
D. REMEDIAL GOALS FOR SITE ST-11 -64-
VII. DESCRIPTION OF ALTERNATIVES -64-
VIII. THE SELECTED REMEDY -72-
IX. STATUTORY DETERMINATION -75-
X. DOCUMENTATION OF SIGNIFICANT CHANGES -75-
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TEXT TABLES
Table 32 Chemicals of Concern Detected in Groundwater from Either Base Production or
Monitoring Wells
Table 33 Maximum Detected Groundwater Concentrations at All Base Wells to RBCs
Table 34 Concentrations of Dissolved Metals (Background) in Groundwater in Wells in
Elmore County, Idaho Gig/L)
Table 35 Chemicals of Concern in Groundwater Based on Fate and Transport Modeling
Results
Table 36 Model-Estimated Peak 30-Year Average Concentrations Compared to EPA
Region III RBCs
Table 37 RME Metals Concentrations in Designated Background Soil Samples (mg/kg)
Table 40 Comparison of Maximum Detected Groundwater Concentrations at All Base
Wells to RBCs
Table 41 Alternative Cost Analysis for Site ST-11
Table 42 Cost Analysis for Regional Groundwater Monitoring
TEXT FIGURES
FIGURE 1 LOCATION MAP MOUNTAIN HOME AIR FORCE BASE IDAHO
FIGURE 2 SITE LOCATIONS MAP MOUNTAIN HOME AIR FORCE BASE IDAHO
FIGURE 3 WELL LOCATIONS MAP MOUNTAIN HOME AIR FORCE BASE IDAHO
FIGURE 4 SOILS INVESTIGATION APPROACH
APPENDIX A
TABLES 1-31, 38, & 39
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APPENDICES
APPENDIX A
TABLES 1-31, 38 & 39
Table 1 Summary of Chemicals Detected in Surface Water Samples at the North Cell,
Wastewater Lagoons
Table 2 Summary of Chemicals Detected in Surface Water Samples at the East Cell,
Wastewater Lagoons
Table 3 Summary of Chemicals Detected in Surface Water Samples at the West Cell,
Wastewater Lagoons
Table 4 Summary of Chemicals Detected in Surface Water Samples at the South Cell,
Wastewater Lagoons
Table 4a Lagoon Landfill Lagoon Sediments Volatile Organics pig/kg and Total Petroleum
Hydrocarbons mg/kg
Table 5 Summary of Chemicals Detected in Groundwater Samples at MW-1
Table 6 Summary of Chemicals Detected in Groundwater Samples at MW-2
Table 7 Summary of Chemicals Detected in Groundwater Samples at MW-3
Table 8 Summary of Chemicals Detected in Groundwater Samples at MW-4
Table 9 Summary of Chemicals Detected in Groundwater Samples at MW-5
Table 10 Summary of Chemicals Detected in Groundwater Samples at MW-6
Table 11 Summary of Chemicals Detected hi Groundwater Samples at MW-7
Table 12 Summary of Chemicals Detected in Groundwater Samples at MW-8
Table 13 Summary of Chemicals Detected hi Groundwater Samples at MW-9
Table 14 Summary of Chemicals Detected in Groundwater Samples at MW-11
Table 15 Summary of Chemicals Detected in Groundwater Samples at Perched Wells at
MW-12
Table 16 Summary of Chemicals Detected in Groundwater Samples at Perched Wells at
MW-15
Table 17 Summary of Chemicals Detected in Groundwater Samples at MW-16
Table 18 Summary of Chemicals Detected in Groundwater Samples at MW-17
Table 19 Summary of Chemicals Detected in Groundwater Samples at MW-18
Table 20 Summary of Chemicals Detected in Groundwater Samples at BPW-1
Table 21 Summary of Chemicals Detected in Groundwater Samples at BPW-2
Table 22 Summary of Chemicals Detected in Groundwater Samples at BPW-4
Table 23 Summary of Chemicals Detected in Groundwater Samples at BPW-5
Table 24 Summary of Chemicals Detected in Groundwater Samples at BPW-6
Table 25 Summary of Chemicals Detected in Groundwater Samples at BPW-7
Table 26 Summary of Chemicals Detected in Groundwater Samples at BPW-8
Table 27 Summary of Chemicals Detected hi Groundwater Samples at BPW-9
Table 28 Summary of Chemicals Detected in Groundwater Samples at 301
Table 29 Summary of Chemicals Detected in Groundwater Samples at 31ABA1
Table 30 Summary of Chemicals Detected in Groundwater Samples at 36AAAA
Table 31 Summary of Chemicals Detected in Groundwater Samples at 5ACCI
Table 38 Summary of Base-Wide Chemicals of Concern in Soils (mg/kg) RME
Concentrations of Metals Above Background and Detected Organic Compounds
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Table 39 Summary of Base-Wide Chemicals of Concern in Surface Water (mg/kg) RME
Concentrations of Metals Above Background and Detected Organic Compounds
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LIST OF ACRONYMS
ACC Air Combat Command
ARARs Applicable or Relevant and Appropriate Requirements
bgs below ground surface
BPW Base production well
BTEX Benzene, toluene, ethylbenzene, and xylenes
CERCLA Comprehensive Environmental Response, Compensation, and Liability Act
COC Chemical of concern
DRMO Defense Reutilization and Marketing Office
EOD Explosive Ordnance Disposal
ERA Ecological Risk Assessment
ET Evapotranspiration
FFA Federal Facilities Agreement
gpm gallons per minute
GRO . Gasoline-range organics
HWMA Hazardous Waste Management Act
IDHW Idaho Department of Health and Welfare
LFI Limited Field Investigation
LOX Liquid Oxygen
MCL Maximum Contaminant Level
MHAFB Mountain Home Air Force Base
MSL Mean sea level
NCP National Contingency Plan
OU Operable Unit
PAH Polyaromatic hydrocarbons
PCB Polychlorinated biphenyl
PCOCs Potential chemicals of concern
POL Petroleum, Oil, and Lubricants
RAB Restoration Advisory Board
RAOs Remedial Action Objectives
RBC Risk-Based Concentration
RCRA Resource Conservation and Recovery Act
RfD Reference Dose
RI Remedial Investigation
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RME Reasonable Maximum Exposure
ROD Record of Decision
SAC Strategic Air Command
SARA Superfund Amendments and Reauthorization Act of 1986
SF Slope Factor
SVOC Semivolatile organic compound
TAG Tactical Air Command
TCE Trichloroethene
TCO Total chromatographable organics
THM Trihalomethane
TPH Total petroleum hydrocarbons
TRPH Total recoverable petroleum hydrocarbons
TVHC Total volatile hydrocarbons
TVOC Total volatile organic compound
UCL Upper confidence limit
USAF United States Air Force
USEPA United States Environmental Protection Agency
UST Underground storage tank
VOC Volatile organic compound
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DECLARATION FOR THE RECORD OF DECISION
MOUNTAIN HOME AIR FORCE BASE, MOUNTAIN HOME, IDAHO
OPERABLE UNITS NOS. 1, 3, 5, AND 6
SITE NAME AND LOCATION
Mountain Home Air Force Base (MHAFB)
Operable Units Numbers 1, 3, 5, and 6
Mountain Home, Elmore County, Idaho
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected final remedial action for Operable Units (OUs)
Numbers 1, 3, 5, 6, and sites at the Lagoon Landfill and Fire Training Area 8, consisting of a
total of 33 sites at Mountain Home Air Force Base in Mountain Home, Idaho. The selected
remedy was chosen in accordance with the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980 (CERCLA or Superfund), as amended by the Superfund
Amendments and Reauthorization Act of 1986 (SARA), and, to the extent practicable, the
National Oil and Hazardous Substances Pollution Contingency Plan (NCP). This decision is
based on the Administrative Record for these sites.
The lead agency for this decision is the U.S. Air Force (USAF). The U.S. Environmental
Protection Agency (USEPA) concurs with this decision and, along with the State of Idaho
Department of Health and Welfare (IDHW), has participated in the scoping of the site
investigation and evaluation of remedial investigation report. The State of Idaho concurs with
the selected remedy.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from one site of the 33 sites addressed in
this ROD, if not addressed by implementing the response action selected in this ROD, may
present a potential future threat to public health, welfare, or the environment.
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DESCRIPTION OF THE SELECTED REMEDY
The OUs 1, 3, 5, and 6 are the final OUs planned for the site. USAF, EPA, and IDHW have
determined that no remedial action is necessary under CERCLA for soil or regional groundwater
at 32 of the 33 sites within OU1, OU3, OUS, OU6, Lagoon Landfill, and Fire Training Area 8
to ensure protection of human health and the environment.
One site, the Flightline Fuel Spill site (ST-11 - the Perched Zone), will undergo a Limited Action
consisting of the following:
• Notice of Restriction which will identify the perched zone and prohibit drilling of
the perched zone or use of the perched water as drinking water on the MHAFB
Comprehensive Plan. The Plan will be registered on land plat maps held by
MHAFB. The land is held by lease by the Air Force and can not go back to the
land holder (Bureau of Land Management) until contamination is below MCLs.
• Leak detection program, which will ensure early detection of any future petroleum
leaks at the site. The program includes petroleum inventory and annual flight line
leak detection programs.
• Sampling of the perched groundwater prior to removal of the land use restriction
to ensure that perched water meets the standards of the Safe Drinking Water Act.
• Monitoring of the perched groundwater quality in accordance with the approved
groundwater monitoring plan.
The Limited Action alternative addresses the principal threat posed by Site ST-11 because the
perched water would only present an unacceptable risk if site use changed and if the perched
water could be used as a source of water for residential use.
The No Remedial Action alternative for the regional groundwater includes at least annual
monitoring of the regional groundwater. The purpose of the monitoring is to verify uncertainties
with the groundwater fate and transport model. Monitoring of contaminants of concern will occur
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at least annually in accordance with the groundwater monitoring plan. The monitoring data
would then be evaluated as part of the CERCLA 5-year review to determine if continued
monitoring of the Snake River Plain regional aquifer is necessary.
STATUTORY DETERMINATION
No remedial action is necessary for soil or groundwater at any of the sites to ensure protection
of human health or the environment. The no action remedy for regional groundwater includes
monitoring of groundwater. The selected remedy for the perched groundwater at site, ST-11, the
Flight Line Fuel Spill, is protective of human health and the environment, complies with federal
and state requirements that are legally applicable or relevant and appropriate to the remedial
action, and is cost-effective. This remedy utilizes permanent solutions and alternative treatment
technologies to the maximum extent practicable for this site. However, because treatment of the
principle threats of the site was not found to be practicable, this remedy does not satisfy the
statutory preference for treatment as a principle element. Furthermore, because the remedy at
Site ST-11 will result in hazardous substances remaining on site above health-based levels, a
review will be conducted within 5 years after commencement of the remedial action to ensure
that the remedy continues to provide adequate protection to human health and the environment.
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Signature sheet for the foregoing Operable Units Numbers 1, 3, 5, 6, Lagoon Landfill, and Fire
Training 8 Record of Decision between the U.S. Air Force and the U.S. Environmental Protection
Agency, with concurrence by the Idaho Department of Health and Welfare.
L^Chuck C. Clarke Date
x f Regional Administrator, Region 10
U.S. Environmental Protection Agency
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Signature sheet for the foregoing Operable Units Numbers 1, 3, 5, 6, Lagoon Landfill, and Fire
Training Area 8 Record of Decision between the U.S. Air Force and the U.S. Environmental
Protection Agency, with concurrence by the Idaho Department of Health and Welfare.
Thad A. Wolfe
Lieutenant General, USAF
Vice Commander
Date
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Signature sheet for the foregoing Operable Units Numbers 1, 3, 5, 6, Lagoon Landfill, and Fire
Training Area 8 Record of Decision between the U.S. Air Force and the U.S. Environmental
Protection Agency, with concurrence by the Idaho Department of Health and Welfare.
Wallace N. Cory
Administrator
Division of Environmental Quality
Idaho Department of Health and Welfare
Date
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DECISION SUMMARY
MOUNTAIN HOME AIR FORCE BASE
OPERABLE UNITS NOS. 1, 3, 5, AND 6
MOUNTAIN HOME, ELMORE COUNTY, IDAHO
INTRODUCTION
In 1988, Base sampling detected bromoform in a Base production well. Because of this
detection, the Base was evaluated using the Hazard Ranking System. In August 1990, Mountain
Home Air Force Base (MHAFB) was listed on the USEPA's National Priorities List (NPL) of
hazardous waste sites under CERCLA (1980) as amended by SARA (1986). In January 1992,
the USEPA Region 10, IDHW, and MHAFB signed a Federal Facilities Compliance Agreement
that established a remedial investigation process schedule for MHAFB.
In accordance with Executive Order 12580 (Superfund Implementation) and the NCP, the USAF
recently completed the RI/FS process for the four OUs, the Lagoon Landfill, and Fire Training
Area 8 addressed in this ROD. The purpose of the RI/FS was to determine the nature and extent
of contamination associated with these sites and to evaluate the current and potential future risk
to human health and the environment posed by the 33 sites addressed in this ROD. The RI/FS
addressed contamination associated with surface water, sediment, soil, and groundwater.
I. SITE NAME, AND LOCATION
MHAFB is located on about 5,800 acres of land 10 miles southwest of Mountain Home, Idaho,
in Elmore County (see Figure 1). MHAFB was established in 1943 and became a Strategic Air
Command (SAC) Base in 1948. In 1951, the Base was reassigned to the Military Air Transport
Service, and SAC resumed control from 1953 until 1965. Tactical Air Command (TAG) assumed
control of the Base in 1965 until 1993. Currently, Air Combat Command (ACC) controls the
mission at MHAFB. The total resident population of MHAFB is currently about 7,000 people.
The surrounding current land use for the Base is agricultural. Mountain Home AFB is likely to
remain a military installation in the near future of 30 years. The Base is undergoing a significant
expansion and is the first wing that will be assigned fighter, tanker, and bomber aircraft. The
Snake River is about 2.5 miles south of the Base, but no permanent streams exist on or near the
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MOUNTAIN HOME
AIR FORCE
MOUNTAIN
HOME
C.J. STRIKE
RESERVOIR
I
I
I
X
I
C
I
AREA LOCATION
LOCATION MAP
SCALE IN MILES
Woodward-Clyde
ENGINEERING & SCIENCES APPLIED
TO THE EARTH k ITS ENVIRONMENT
LOCATION MAP
MOUNTAIN HOME AIR FORCE BASE IDAHO
DRN BY: CJG
CH1CD BY:
DATE: 07/14/94
DATE:
PROJECT NO.
92MC520A
HC. NO.
1
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Base. Groundwater is found at approximately 350 to 400 feet below ground surface (bgs) at the
Base, and up to 900 feet bgs within the Snake River Plain. Groundwater is the source of
drinking water at the Base and is a source of irrigation and drinking water for nearby farm
residents adjacent to the Base. The Base currently has 11 Base Production Wells (BPWs) and
monitors groundwater quality.
Since the Base was established in 1943, varying quantities of hazardous wastes have been
generated and disposed of at MHAFB. The sources of waste include fuel management, industrial
and aircraft operations, and fire training activities.
MHAFB was investigated by separating a total of 33 sites into six OUs. Sites at MHAFB with
similar operations or investigative activities were grouped into OUs to facilitate the
characterization of potential environmental impacts and subsequent actions at the Base. The
USAF investigated the 33 sites within OUs 1,3, 5, 6, the Lagoon Landfill, and Fire Training
Area 8 with oversight by the United States Environmental Protection Agency (USEPA) Region
10 and the Idaho Department of Health and Welfare (IDHW).
OU2 was investigated under a previous program and included the "B"-Street Landfill (LF-02) and
the soils investigation of the Lagoon Landfill (LF-01). The OU2 ROD was completed in 1993
recommending no action for LF-02. LF-01 was deferred to this ROD. OU4 (Fire Training
Area 8) was also addressed in a ROD signed in 1992.
The groundwater pathway for OU2 and OU4 and ST-13 were evaluated as part of the OU3
Basewide groundwater and ecological investigation and is included as part of this ROD. In
addition, soils and groundwater of LF-01 are addressed in this ROD.
Following listing on the NPL, OU1 sites were investigated as Limited Field Investigations (LFIs),
and sites determined to pose a potential risk to human health or the environment were further
investigated in OU6 as Remedial Investigations (RIs) or Phase II LFIs. These include Sites
SD-12, SD-24, SD-25, SD-27, SS-29, and OT-16. An underground storage tank (UST) at Fire
Training Area 8 (FT08-UST) was also included in OU6. OU3 included Remedial Investigations
of the Basewide groundwater, the Basewide ecological risk assessment, and five fuel release sites.
The OUS site consists of a low-level radioactive waste disposal area where a remedial response
action (i.e., source removal) was completed. The sites included in these OUs are:
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Operable Unit 1
DP-09 Waste Oil Disposal Area
DP-18 Old Burial Trench
FT-04 Fire Training Area 4
FT-05 Fire Training Area 5
FT-06 Fire Training Area 6
FT-07A Fire Training Area 7A
FT-07B Fire Training Area 7B
FT-07C Fire Training Area 7C
LF-03 Existing Landfill
LF-23 Solid Waste Disposal Area
OT-10 Perimeter Road
OT-15 Corker Material Burial Area
OT-16 Munitions Disposal Area (further studied in OU6)
SD-12 Entomology Shop Yard (further studied in OU6)
SD-24 MWR Auto Hobby Shop/Munitions Trailer Maintenance Shop
(further studied in OU6)
SD-25 Flight Line Storm Drain (further studied in OU6)
SD-27 Vehicle Wash Rack (further studied in OU6)
SS-26 Drum Accumulation Pad
SS-28 Former Wash Water Accumulation Basin
SS-29 Drum Accumulation Pad (further studied in OU6)
SS-30 DRMO Storage Area
ST-22 Titan Missile Maintenance Area
Operable Unit 3
Basewide Groundwater and Ecological Investigation
Fuel Sites (Operable Unit 3)
• ST-11
• ST-13
ST-31
Flight Line Fuel Spill
POL Underground Storage Tanks (groundwater only)
BX Service Station
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ST-32 MX Service Station
ST-34 Fuel Hydrant No. 9
ST-35. Hospital Fuel Spill
Operable Unit 5
RW-14
Low Level Radioactive Waste Container Storage Area
Operable Unit 6
SD-12 Entomology Shop Yard
SD-24 MWR Auto Hobby Shop/Munitions Trailer Maintenance Shop
SD-25 Flight Line Storm Drain
SD-27 Vehicle Wash Rack
SS-29 Drum Accumulation Pad
OT-16 Munitions Disposal Area
FT08-UST UST at Fire Training Area 8
Landfill #1
LF-01
Lagoon Landfill
H. SITE HISTORY AND ENFORCEMENT ACTIVITIES
A. SITE HISTORY
The 33 individual sites are located in various areas at MHAFB (Figure 2). A brief description
of each site within the OUs follows. A detailed figure for each site is shown in Mountain Home
OU3 RI Documents.
Operable Unit 1
Note: The sites investigated in both OU1 and OU6 are discussed in the OU6 section.
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I
f&K^iMlSlF
^lilWl^-^
SO-24
SD-2S
SS-26
SD-27
SS-28
SS-29
SS-30
ST-31
ST-32
ST-34
ST-35
UCOON LANDFILL
"B" STREET LANDFILL
EXISTING LANDFILL
FIRE TRAINING AREA 4
FIRE TRAINING AREA S
FIRE TRAINING AREA 6
FIRE TRAINING-AREA 7A
FIRE TRAINING AREA 7B
FIRE TRAINING AREA 7C
FIRE TRAINING AREA 8
UST AT FIRE TRAINING AREA 8
WASTE DISPOSAL AREA
PERIMETER ROAD
FLIGHT LINE FUEL SPILL
ENTOMOLOGY SHOP YARD
USTs AT POL YARD
LOW-LEVEL RADIOACTIVE BURIAL SITE
CORKER MATERIAL BURIAL SITE
MUNITIONS DISPOSAL AREA
OLD BURIAL TRENCH
TITAN MISSILE MAINTENANCE AREA
SOLID WASTE DISPOSAL AREA
MWR AUTO HOBBY SHOP / MUNITIONS
TRAILER MAINTENANCE SHOP
FLIGHT LINE STORM DRAIN
DRUM ACCUMULATION PAD
VECHICLE WASH RACK
FORMER WASH WATER
ACCUMULATION BASIN
DRUM ACCUMULATION PAD
DRMO STORAGE AREA I
BX SERVICE STATION
MX SERVICE STATION
FUEL HYDRANT No. 9
HOSPITAL FUEL SPILL
M
2000 1000
2000
SCALE IN FEET
SOURCE: MOUNTAIN HOUE AfO CAD GCNCRtrCD SITC VU
SITE LOCATIONS MAP
MOUNTAIN HOME AIR FORCE BASE
IDAHO
DRN BY CJG IDATE 05/to/9«
PltOICCT NO.
92UCHOC
Lie. «
. _L
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• DP-09 Waste Oil Disposal Area is located within the southeast perimeter of
MHAFB near the southeast end of the main runway. The site reportedly operated
from about 1953 to 1956. It was reportedly a natural depression where waste oil
and possibly other petroleum wastes and solvents were disposed of in trenches
about 140 to 170 feet long. These suspected disposal trenches are not currently
open, but they are visible as four parallel lines of disturbed soil and contrasting
vegetation. The site is now bare ground, and it is not used.
• DP-18 Old Burial Trench is located in the northeast part of MHAFB along its
eastern perimeter in an open field. It is reportedly an 800-foot-long by 10-foot-
deep trench said to have received outdated military supplies, vehicles, small arms
munitions, and other solid waste in 1953. The site now contains some demolition
debris, and it is nonirrigated and has minimal maintenance.
• FT-04 Fire Training Area 4 was the first fire training area at MHAFB, and it is
located in the north part of MHAFB. Fire training exercises reportedly occurred
from 1943 to 1944. Past records indicate fire training exercises were done about
twice per week within a bermed area. During each exercise, 200 to 300 gallons
of aviation fuel and petroleum, oil, and lubricant wastes were poured onto a mock
aircraft and burned. Historical aerial photographs indicate the training exercises
occurred within an area about 60 feet wide and 130 feet long. The site is now in
an open field that is nonirrigated and has minimal maintenance.
• FT-05 Fire Training Area 5 was the second fire training area at MHAFB and is
located in the north-central part of the Base. Fire training exercises reportedly
occurred from 1944 to 1945. Past records indicate fire training exercises were
done about twice per week within a bermed area. During each exercise, 200 to
300 gallons of aviation fuel and petroleum, oil, and lubricant wastes were poured
onto a mock aircraft and burned. The site is now under the northeast part of
supply warehouse Building 1325.
• FT-06 Fire Training Area 6 is the site of a former fire training area located in
the west-central part of MHAFB. Fire training exercises were completed twice per
week from 1948 to 1950 and 1951 to 1953. During each exercise, 200 to
300 gallons of aviation fuel and petroleum, oil, and lubricant wastes were poured
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onto a mock aircraft and burned. The site is currently mostly overlain by
flightline concrete and asphalt.
• FT-07A Fire Training Area 7A was a fire training area located in the southwest
part of MHAFB. Fire training exercises reportedly occurred from 1953 to 1962.
Past records indicate fire training exercises were done about twice per week within
a circular-shaped bermed area. During each exercise, 200 to 300 gallons of
aviation fuel and petroleum, oil, and lubricant wastes were poured onto a mock
aircraft and burned. Historical aerial photographs indicate the training exercises
occurred within a circular area about 480 feet wide. The site is south of an
abandoned east-west runway in an open field that is nonirrigated and has minimal
maintenance.
• FT-07B Fire Training Area 7B is located hi the south-central part of MHAFB.
It was a fire training area which operated from about 1953 to 1962. Past records
indicate fire training exercises were done at two small burn pits about twice per
week. During each exercise, 200 to 300 gallons of aviation fuel and petroleum,
oil, and lubricant wastes were poured onto mock aircraft and burned. The site is
north of an abandoned east-west runway in an open field that is nonirrigated and
has minimal maintenance.
• FT-07C Fire Training Area 7C is located in the southwest part of MHAFB. It
was a fire training area which operated from about 1953 to 1962. Past records
indicate fire training exercises were done at two small burn pits about twice per
week. During each exercise, 200 to 300 gallons of aviation fuel and petroleum,
oil, and lubricant wastes were poured onto a mock aircraft and burned. The site
is south of an abandoned east-west runway in an open field that is nonirrigated
and has minimal maintenance.
• LF-03 Existing Landfill is located in the southwest part of MHAFB. It is the
currently operating landfill and has operated as a sanitary landfill for the Base
since 1969. Because it is an open/operating landfill, it is designed, operated, and
monitored to comply with both state and federal regulations that apply to
municipal landfills. There is no documented record or history of hazardous
materials being placed in this landfill.
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LF-23 Solid Waste Disposal Area is a former landfill area in the south-central
part of MHAFB about 100 feet north of the southern base boundary. Exact dates
of landfill operation are not known; however, historical aerial photographs indicate
that the solid waste disposal area was present as early as October 1950 and
consisted of three burial trenches or depressions. Debris disposed in the trenches
included tires, household refuse, and other solid waste. The site is now an open
field that is nonirrigated and that receives minimal maintenance.
OT-10 Perimeter Road is along the MHAFB western boundary, south of the
wastewater lagoons. Waste oils were placed on a perimeter road for dust control.
The practice may have begun as early as 1943, and it ended in 1975. A truck
equipped with a vacuum system collected waste oils from the flight line, motor
pool, and auto hobby shop. Waste oil was reportedly applied to the entire width
of the road surface. This perimeter road was paved with crushed asphalt sometime
after 1987 and remains an active roadway.
OT-15 Corker Material Burial Area is located along the western boundary of
MHAFB adjacent to the west side of the wastewater lagoons. Components of
aircraft wings containing a boron-fiber composite known as "corker material" were
reportedly buried at this site in 1979 after the crash of an airplane. The site is
now in an open field that is nonirrigated and that receives minimal maintenance.
SS-26 Drum Accumulation Pad is located centrally along the Base Flightline
near Building 208, which includes the Wheel and Tire Shop. SS-26 served as an
accumulation point for that operation. The site is a 10-foot by 10-foot continuous-
pour concrete pad that was used for temporary storage of drummed waste solvents
and petroleum, oil, and lubricants (POL) wastes that were routinely collected for
reuse, resale, or disposal. The pad was likely poured hi the mid-1970s, and it was
used until a nearby covered storage building was constructed in 1990. Most of the
drummed wastes stored on the pad were from the Wheel and Tire Shop, 366th
Equipment Maintenance Squadron. The largest volume of waste generated was
PD-680, a petroleum-distillate-based solvent. The site is currently inactive and no
waste materials are stored on the pad.
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SS-28 Former Wash Water Accumulation Basin is located in the north-central
part of the Base. The site was part of a maintenance facility for the Base railroad
that was used from 1943 until 1987. It was a small unlined pit on the west side
of a maintenance building that received wash water and solvents that had been
used to clean locomotives. In 1987, soils around and beneath the pit were
reportedly removed, and the excavation was backfilled with clean fill. The
depression is no longer present and wash water is contained in 55-gallon drums
for proper disposal. The site is bare ground.
SS-30 DRMO Storage Area is located in the north-central part of the Base. The
area is a former unlined and unbermed storage pad that is located within the larger
operating Defense Reutilization and Marketing (DRMO) area, which is a permitted
RCRA facility. Before December 1987 the storage pad was used as a temporary
storage point for drummed wastes that were collected from Base shops and other
military facilities in the region. Wastes were processed for recycling, resale, or
disposal based on the nature, quantity, and purity of the wastes. The site is
currently paved with asphalt and is used to temporarily store nonhazardous scrap
metal and office furniture for later sale.
ST-22 Titan Missile Maintenance Area is located in the northwest part of the
Base. Exact dates of operation for the facility are not known; however, the three
off-Base Titan missile sites operated by the Base were active from April 1962 to
June 1965. Four USTs that historically contained solvents, acids, and caustic
solutions were located within this site. The USTs were abandoned by filling them
with sand, and sealing the manway entry ports with cement. The site is currently
paved and remains part of the active flightline near the hangar complex.
Operable Unit 3
Basewide Groundwater/Ecological Investigation. The groundwater operable unit
consists of the Snake River Plain Aquifer (regional aquifer) 350 to 400 feet below
ground surface at the Base. It considers potential releases of chemicals of concern
to the groundwater from all 33 sites investigated as part of the CERCLA process.
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Fuel Sites
The ecological evaluation considers the potential adverse impact (individually and
collectively) that exposure to environmental media (surface water, sediment, and
soil) at the 33 sites may have on ecological receptors (individuals and populations
of plant and animal species).
• ST-11 Flight Line Fuel Spill is located in the west-central part of the Base. The
leak occurred from a 3/4-inch ventline for a 16-inch fueling line. The fueling line
carries jet fuel (JP-4) from the POL Yard to fueling hydrants along the flight line.
The leak occurred soon after the fueling system was installed. Available
information suggests that the leak occurred during the first half of 1957.
Interview information indicates that the leak was intermittent and ongoing for a
period of two to three months. During this time, as much as 50,000 to 90,000
gallons of fuel may have been released via the ventline leak. Upon discovery of
the leak, the ventline was repaired and new access manholes were installed over
the fueling line at the leak location. A leak detection system has been installed
along the trace of this and all active fuel pipelines at Mountain Home AFB. This
system is sampled annually to check for current leakage. To date, no leakage has
been detected and the pipeline system remains operational. The site is almost
entirely under concrete. It is under an active aircraft parking apron.
• ST-31 BX Service Station is located in the central part of the Base. The facility
originally included a service building, three gasoline dispenser islands, and three
10,000-gallon steel USTs that were installed in 1955 and used to store leaded and
unleaded gasoline. Pumps and piping were replaced in 1983. Tank/piping
tightness tests done in 1992 indicated that one of the tanks and its piping were
leaking. The other two tanks passed the test. The duration of fuel release is not
known, but the leak may have occurred over a period of years. The tank that
failed the test, its associated piping, and approximately 800 cubic yards of
contaminated soil were removed from the site, and the excavation was backfilled
with clean fill. The BX Service Station remains an active facility, and it is
regulated under the Idaho UST program. Most of the site is paved with asphalt
parking lot or covered with buildings. Some areas of exposed soil exist.
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• ST-32 MX Service Station is located in the central part of the Base. A 60-foot
by 80-foot concrete pump-island pad was present in the center of the site. Six
concrete pump islands were on the pad. The MX Service Station was constructed
in 1948 to supply fuel to military vehicles. Original features included a service
building (T-1113), one 5,000-gallon steel UST (diesel), one 12,000-gallon steel
UST (gasoline), and one 19,000-gallon steel UST (diesel). Some piping changes
were made in 1962, and two new pumps were added in 1991. The 12,000-gallon
and 19,000-gallon USTs were removed in February 1992, and the 5,000-gallon
UST was removed in May 1992. A 3-mm-diameter hole was observed in the
12,000-gallon UST after it was removed. Contaminated soil was removed and
taken to the Base biotreatment area. The excavations were backfilled with clean
fill. All surface structures have been subsequently removed and the site remains
an open lot. Most of the site is covered by asphalt or concrete with some small
areas of exposed soil.
• ST-34 Fuel Hydrant No. 9 is located in the central part of the Base. The site
includes Fuel Head No. 9, the fuel line that runs west under the taxiway, and the
metering pit immediately west of the taxiway. The site is part of the JP-4 fueling
system that was installed at the Base during the mid-1950s. The hydrant system
was used to both meter fuel to aircraft and to defuel aircraft. After fueling
operations and during defueling, fuel from the line to the fuel head drained back
to the metering pit. The delivery pump in the metering pit transferred fuel to a
defueling tank located near Fuel Hydrant No. 9. In April 1991, a fuel leak was
detected at the metering pit. The fuel hydrant, the metering pit, and adjacent soils
were excavated and removed. Almost the entire site is located under the concrete
aircraft parking apron and the concrete taxiway.
• ST-35 Hospital Fuel Spill is located in the northeast part of the Base. The site
consists of a fuel line that is under the hospital access road that intersects with
Main Avenue. The release occurred in the mid-1980s (probably 1985 or 1986).
According to Base records, the pipeline was cut by a tooth on a grading machine
during construction of the access road. An estimated 800 to 1,000 gallons of JP-4
were released from the pipeline under nonpumping gravity flow conditions. The
pipeline was reportedly repaired the day following the release. The Base
reportedly recovered 350 to 400 gallons of fuel from the ground by pumping the
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fuel into bowsers. Soils at the release site were excavated immediately to a depth
of 3.5 feet over an area about 50 feet in diameter, centered on the release point.
The extent of contamination during excavation was reportedly determined by the
presence of fuel odors and soil staining. Subsequent to the fuel line release and
repair, a soil vapor monitoring system was installed along all active fuel
distribution pipelines at Mountain Home AFB. No ongoing leakage has been
detected at the site.
Operable Unit 5
• RW-14 Low Level Radioactive Waste Container Storage Area was located
along the west perimeter of MHAFB and consisted of two low-level radioactive
waste containers buried vertically in the ground. The containers reportedly
contained radium-illuminated aircraft instruments and possibly some medical
radiology waste. The containers consisted of an 18-foot-long section of Schedule
120, black iron pipe that was used for a period of two years during the mid-1950s
and about 20 feet of several 55-gallon drums that were welded together. The
period during which the 55-gallon drums may have been used is not known. A
separate removal action was completed at the site. The containers were removed
and were disposed at a licensed off-Base disposal facility (Richland, Washington).
Testing at the time of the removal action indicated no contamination of site soils.
The site is now in an open field that is nonirrigated and that receives minimal
maintenance.
Operable Unit 6
• SD-12 Entomology Shop Yard was located hi the north-central part of MHAFB.
Site facilities included a building approximately 40 feet by 60 feet and two
1,000-gallon USTs located north and northwest of the building. The building was
constructed in 1958 and was converted to the Entomology Shop in the late 1960s.
The facility was used to store and handle herbicides, pesticides, and application
equipment. The application equipment was filled and cleaned within the building.
Wastewater generated from cleaning the application equipment was discharged to
surface soils outside the building through a concrete ditch and later through a
buried drainpipe from 1969 to 1981. After 1981, the wastewater was collected in
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an UST installed adjacent to the northwest side of the building. The Entomology
Shop was demolished and the USTs were removed in 1987. Currently, the site
is covered with asphalt and used as a parking lot.
• SD-24 Morale, Welfare, and Recreation (MWR) Auto Hobby Shop/Munitions
Trailer Maintenance Shop is located in the northwest part of MHAFB. This
facility was originally built in 1960 and 1961 as a liquid oxygen (LOX)
production and helium loading plant. The original plant included LOX and liquid
nitrogen storage vessels (currently removed), a chemical waste collection tank/oil
sump, a concrete-lined blow-down trench (drain trough) for storage vessel pressure
relief that had a trough sump and a dry sump at the south end, and a drainage
flume and rock infiltration gallery used to control surface water runoff. The
facility became the MWR Auto Hobby Shop in 1965. Waste oil was typically
removed from the site; however, between 1965 and 1974, some waste oil was
placed in the drain trough and on the surface soils located southwest of the
building. According to one interview record, in 1985 waste solvents were
disposed of in animal holes located within the fenced yard at the site; however,
this record could not be substantiated through soil borings or soil gas analysis.
The drain trough and trough sump were capped with concrete in the mid-1980s.
The waste collection tank was taken out of service, cleaned, and the drain line
from the shop was plugged. The Munitions Trailer Maintenance Shop has
occupied the facility since about 1982 and remains the active function of the
facility.
• SD-25 Flight Line Storm Drain is located in the northwest part of the Base.
Storm water runoff from the flight line area, parking lots, and streets, and waste
water from former and current operation facilities drain into the Flight Line Storm
Drain site. Site SD-25 includes about 6,000 feet of open ditches and about 7,000
feet of underground drainage. A check dam controls storm water flow out of the
MHAFB property. Two discharge lines from oil/water separators at flightline
shops outfall into the open ditch. The flightline drain culvert system and open
ditch remain active and standing water is present in certain segments of the ditch
year-round. Hazardous waste is no longer discharged to any portion of the site.
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• SD-27 Vehicle Wash Rack is located in the northwest part of the Base. It is used
to clean construction vehicles. The site consists of a concrete wash rack located
north of Building 1354 that was built in the 1960s. The wash rack drainage ditch
and a concrete drum storage pad are located northeast of the wash rack area. Prior
to the mid-1980s, a petroleum-distillate-based degreasing agent was used to clean
grease and asphalt from vehicles. Wash water was discharged to the unlined wash
rack drainage ditch, and soils and sediment were reportedly removed from the
ditch on an annual basis until about 1990. An interview record alleges a spill of
mixed solvent wastes from four drums on the parking area located east of the
wash rack. Bulk storage of drums occurs within the fenced drum storage area.
Leaking and overfilled waste oil drums and visibly stained soils were reported at
the drum storage area in 1986. The wash rack drainage ditch was graded over in
the fall of 1993, and a new oil/water separator and piping were installed to receive
the waste water discharges from the Vehicle Wash Rack.
• SS-29 Drum Accumulation Pad is located in the central part of the Base. It
consists of a concrete pad approximately 20 feet by 35 feet in size that was used
as a temporary accumulation area by the Propulsion Shop and the Nondestructive
Testing Laboratory. Chemical wastes, including solvents, penetrants, emulsifiers,
fuel, and hydraulic oil, were stored in drums on the fenced pad from the mid-
1970s until 1990. Spilled waste was reportedly observed along the outside of the
fence in 1986. The pad is currently inactive and no wastes are stored there.
• OT-16 Munitions Disposal Area is located in the north-central part of MHAFB
near the northern perimeter fence. The site consisted of two burn operation areas
operated by Explosive Ordnance Disposal (EOD) personnel. The facility was built
sometime between 1950 and 1957. One burn operation was fueled by a 50-gallon
diesel fuel tank. This operation was a popping furnace located in the center of a
large circular graded area about 500 feet in diameter. It consisted of a concrete
and steel structure with a steel plate that was heated to detonate munitions. Only
the concrete blast-wall remains at the site. The popping furnace was dismantled
in the fall of 1992 after it was determined not to be contaminated. The dismantled
popping furnace was taken off Base as scrap, and the furnace area was clean-
closed under State of Idaho Hazardous Waste Management Act (HWMA)
regulations (the State's equivalent program to USEPA's RCRA). A second burn
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area was an open burn pit about 60 feet long and 30 feet wide. Munitions were
placed in the pit along with wood and fuel, ignited, and allowed to detonate. The
open burn pit has not been used since April 1990. The Munitions Disposal Area
remains an inactive facility.
• FT08-UST, UST at Fire Training Area 8 was located in the south-central part
of the Base. The site consists of a former UST associated with the fuel
distribution system for the old burn pit at Fire Training Area 8. The UST was
installed in about 1977 and had a 15,000 gallon capacity, and was used to store
jet fuel (JP-4). JP-4 used for the fire training exercises was pumped from the
UST to the old burn pit. There is no record of leaks from the UST. The UST
was located inside of the currently used MHAFB fire training area compound.
The UST and its associated pipe system were removed in 1993 and the excavation
was backfilled.
Lagoon Landfill
• LF-01 Lagoon Landfill is a former landfill that is located near the west
boundary of the Base and beneath the Base wastewater lagoons. The wastewater
lagoon system consists of four lagoon cells with a total surface area of about
73 acres and an average depth of 3.5 to 4 feet. The lagoon cells were built in
1961. The landfill trenches beneath them served as the main Base landfill prior
to construction of the lagoon system. A separate Remedial Investigation/Baseline
Risk Assessment was done at the wastewater lagoons as part of OU2. Samples of
lagoon water and lagoon sediment were collected and analyzed.
The results of the OU2 RI/BRA indicated that volatile organic compounds,
semivolatile organic compounds, pesticides/polychlorinated biphenyls (PCBs), and
metals are present in lagoon sediments. The Baseline Human Health Risk
Assessment and Baseline Ecological Risk Assessment for the site shows that no
unacceptable risks to humans or populations of key ecological receptors are
expected from current or future exposures to lagoon sediment or water; however,
individual animals may be at risk. Because the lagoons were considered to be a
potential continuous source of chemicals to groundwater, LF-01 is also included
in the Basewide groundwater investigation in OU3.
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Groundwater Pathway Sites
• ST-13 POL Underground Storage Tanks was previously investigated by CH2M-
Hill in early 1983 and is located at the POL Yard and consisted of four USTs
reportedly located just southeast of Building 1307 (small pumphouse). The USTs
were either 12,000-gallon or 15,000-gallon tanks which received segregated POL
wastes: waste solvents, waste synthetic oils, waste mineral oils, miscellaneous
waste fuels (JP-4 mostly), and petroleum products. The age of the tanks is
unknown, and it is also not known if the tanks were associated with Facility 1308
or with Building 1307. They were removed in a RCRA non-clean closure in June
1988 by U.S. Pollution Control, Inc., and soil samples collected before and during
the removal showed various detects of VOCs. The site was in the OU3 RI to
evaluate possible releases of POL wastes to groundwater.
• FT-08 Fire Training Area Site FT-08 was investigated in the OU4 RI/BRA
Report (W-C 199la). It is an abandoned fire training exercise area that was in use
from 1962 through 1986. It includes a bermed pit used to contain the fuel which
was then ignited for the fire-fighting exercise. From 1962 to 1975, the fuel
included aviation gas (AVGAS), motor gas (MOGAS), and possibly spent solvents
and waste POLs. From 1975 to 1986, jet fuel (JP-4) was used. (Note that
information given to IDHW by one interviewee alleges that TCE disposal occurred
at the site after 1975.) The investigation results at FT-08 show that site soils are
contaminated with varying concentrations of VOCs, SVOCs, petroleum
hydrocarbons, and metals. The highest concentrations of these compounds were
found in the surface soils within the bermed area and in the soils underlying the
bermed area. The results of the Human Health Risk Assessment and Ecological
Risk Assessment indicate no unacceptable health risks are expected from exposure
to soils at FT-08. No further action was recommended for this site. The OU4
vadose zone modeling considered leaching only by precipitation of contaminants
currently in soil. FT-08 was included in OU3 fate and transport modeling to
consider the possible impacts on groundwater of past releases and of past
infiltration of applied water.
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B. ENFORCEMENT ACTIVITIES
In January 1991, USAF, EPA, and IDHW entered into a Federal Facilities Agreement (FFA) that
was made final in January 1992. The FFA established a procedural framework and schedule for
developing, implementing, and monitoring appropriate response actions conducted at MHAFB.
Under the terms of the FFA, EPA and IDHW provided oversight of subsequent RI activities and
agreed on the final remedy set forth in this ROD.
Investigation of the SWMUs addressed in this Record of Decision was done pursuant to Module
4 of the Mountain Home AFB HWMA Permit. Any SWMU not addressed in this ROD or the
OU2 or OU4 ROD are subject to the conditions of the HWMA Permit.
The DRMO is the only HWMA permitted site at Mountain Home AFB. Two other sites, ST-13
and OT-16, were both closed following RCRA (HWMA) procedures. Site ST-13 was closed with
petroleum contamination left in place and Site OT-16 was clean closed.
in. HIGHLIGHTS OF COMMUNITY PARTICIPATION
The following community relations activities were conducted during the Limited Field
Investigations and Remedial Investigations/Baseline Risk Assessments:
• The USAF developed a Community Relations Plan in May 1991 as part of the
overall management plan for environmental restoration activities at the Base. The
Community Relations Plan was designed to promote public awareness of the
investigations and public involvement in the decision-making process.
• The Technical Review Committee was formed in 1992 as a method to keep state
and local officials updated on the progress of the investigation.
• In an effort to more fully involve the public, the Technical Review Committee was
modified to create a Restoration Advisory Board (RAB). The elected officials and
regulatory agencies continued their membership, and an additional six local
citizens were nominated by their peers to serve on the board. The board is co-
chaired by a MHAFB official and one of the new community RAB members.
Members are requested to review draft as well as final documents, and are
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responsible for bringing community concerns to the meetings. The RAB has met
quarterly since April 1994. Notices inviting the public to the RAB meetings
appeared in the Mountain Home News and the MHAFB Gunfighter.
• A tour of MHAFB environmental restoration sites was conducted on June 7, 1995,
in preparation for the public comment period on the Proposed Plan.
• The Proposed Plan was released on June 19 and was mailed out to RAB members
on the mailing list. A notice was published in the MHAFB Gunfighter, Mountain
Home News, and the Idaho Statesman announcing the meeting.
• A public comment period for remedial alternatives was open from June 19 to
July 19, 1995. A public meeting to discuss remedial alternatives and receive
public comments was held on June 26, 1995, at Mountain Home High School.
One person from the public attended.
• No comments were received during the public comment period; therefore this
ROD does not include a Responsiveness Summary.
• The documentation which supports this ROD is available for public review in the
Information Repository at the following location:
Mountain Home Air Force Base Library
520 Phantom Avenue, Building 2427
MHAFB, ID 83648-5224
Phone: (208) 828-2326
Hours: Monday - Thursday 9 a.m. - 9 p.m.
Friday 9 a.m. - 5 p.m.
Saturday - Sunday 10 a.m. - 4 p.m.
• The remedy selection is based on the Administrative Record at the following
locations:
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Mountain Home Air Force Base
366 (CES/CEVR)
1030 Liberator Street
MHAFB, ID 83648
Phone: (208) 828-2338
IV. SCOPE AND ROLE OF OPERABLE UNIT
There are 6 OUs considered at MHAFB. Two of the OUs, OU2 (ROD signed in June 1993) and
OU4 (ROD signed in June 1992) have been previously addressed with recommendations of No
Further Action. Four remaining OUs and two sites, one from OU2 and one from OU4, are
addressed in this ROD. OU1 and OU6 address soils. OU3 addresses fuel releases, potential
releases to Basewide groundwater from all sites in all OUs, sediment from the Lagoon Landfill,
and evaluation of individual and cumulative ecological risk for all sites in all OUs. OUS was a
removal action for two containers for low-level radioactive wastes.
V. SUMMARY OF SITE CHARACTERISTICS
A. TOPOGRAPHY, SURFACE FEATURES, AND CLIMATE
MHAFB is located on the Mountain Home Plateau, a rolling upland plain covered primarily with
lava and windblown sediment. Scattered shield volcanoes and cinder cones rise several hundred
feet above the plain. The plateau slopes gently downward toward the north, west, and southwest.
Elevations range from 2,700 to 3,200 feet above mean sea level (MSL).
The Snake River forms the southern and southwestern boundary of the Mountain Home Plateau.
The plateau is drained by a series of intermittent streams that discharge to the Snake River during
rainy periods.
The climate at MHAFB is arid. The area receives about 8 inches of precipitation annually.
Evapotranspiration (ET) is between 5 and 9 inches per year. This results in an annual net
precipitation of about +3 inches to -1 inch. The 100-year, 24-hour storm event results in 2 inches
of precipitation. The 25-year, 24-hour storm event results in 1.6 inches of precipitation.
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Area wind directions are highly variable, arising predominantly from the northwest during the
spring and summer and from the east and east-southeast during the fall and winter.
No floodplains or historic sites are on Mountain Home AFB.. One area, the Flight Line Storm
Drain (SD25) is considered a wetland. This is a man-made feature and conveys storm water and
Flight Line Shops' waste water to a series of surface water treatment lagoons. No known
endangered species inhabit the Base.
B. REGIONAL AND SITE GEOLOGY
1. Regional Geology
The Mountain Home Plateau, on which MHAFB is located, is underlain by over 10,000 feet of
volcanic and sedimentary rocks. The principal geologic formations of interest are the Glenns
Ferry Formation, the Bruneau Formation of the Idaho Group, and the Snake River Group, which
is the uppermost bedrock unit. The Snake River Group, which is 550 feet thick, consists of
several basalt flows and unconsolidated alluvial deposits. The basalt originated from volcanic
sources as much as 60 miles east of MHAFB. The Snake River Group forms the bedrock at
MHAFB and elsewhere in the Mountain Home Plateau.
Wind-blown and alluvial deposits overlie the Snake River Group. These deposits consist of a
layer of unconsolidated silt and sand ranging in thickness from several inches to approximately
30 feet.
2. Site Geology
In the vicinity of Mountain Home, Idaho, and the Base, the upper geologic unit is mostly
Pleistocene basalt of the Snake River Group. Site specific geology is summarized as follows:
• Unconsolidated silt or fine sand from a few feet to more than 20 feet thick covers
basalt over most of the Base
• Basalt beneath the Base is between 490 and 580 feet thick
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• As many as 12 interbed (windblown or waterlain sediments that might impede the
vertical movement of water in the vadose or phreatic zone) or interflow (rubbly,
broken, or horizontally fractured zones that facilitate horizontal movement of
water in the vadose or phreatic zone) intervals are present in the basalt below the
Base; in the vadose zone, infiltration water may reach a zone of low vertical
hydraulic conductivity (interbed or dense basalt) and pond in a zone of higher
hydraulic conductivity (interflow or fractured basalt); such a zone is a "perched
groundwater" zone, and the rate of infiltration from such a zone depends on the
contrast in vertical hydraulic conductivity between the material in which the water
is held and the material that has impeded infiltration of the vadose water
• Available data suggest that all of these interbed or interflow intervals are
discontinuous across the Base
• Some intervals are continuous across a small portion of the Base
• One or two of the deeper intervals appear to be more continuous than shallower
intervals
C. SOILS
Soils at MHAFB are typical of the entire plateau, consisting mostly of wind-blown silt and sand.
Typical permeabilities of site soils are reported to be low to moderate ranging from 0.6 to
6.0 in/hr. The different soil series occurring on Base include: the Bahem, the Garbutt, the
Minidoka, the Minveno, the Royal, and the Trevino. These soils are typical of the arid
environment found in the Mountain Home Area.
D. HYDROGEOLOGY
In the vicinity of MHAFB, the regional aquifer is in the basalts of the Snake River Group.
Regional groundwater flows in a southerly direction toward the Snake River at a gradient of
about 1 foot per 1,000 feet. At the Base, the gradient is lower, between 1 foot per 10,000 feet
and 1 foot per 100,000 feet. The principal recharge area for the aquifer underlying the Mountain
Home Plateau is in the mountains north of the plateau where precipitation infiltrates directly into
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rock outcrops. A small amount of recharge is probably provided by deep percolation of
intermittent stream flow and excess irrigation water.
Drinking water at MHAFB is obtained from nine Base production wells completed in the Snake
River Group basalts. The Base production wells range in depth from 379 feet to 610 feet bgs.
The water table at the Base occurs at a depth of about 350 feet bgs. Calculations of aquifer
transmissivities (rate of water movement through the aquifer) for the Base production wells result
in values ranging from 65,000 to 650,000 gallons per day per foot. An average yield of 1,094
gpm was calculated in 1987 from available well production data.
Within a 2-mile radius of the Base, about 35 private wells have been drilled, ranging from 300
to 700 feet in depth. Several wells are downgradient (south) of the Base. The locations of on-
Base and off-Base wells are shown on Figure 3.
Halls Ferry Springs and Weatherby Springs are both located about 2.5 miles south of the Base
along the north canyon wall of the Snake River. Both springs are discharge points for the
regional aquifer.
E. SURFACE WATER HYDROLOGY
The Snake River is the primary surface water feature in the Mountain Home area. Two
ephemeral streams, Canyon Creek (located to the west) and Rattlesnake Creek (located to the
east), are near the Base. When flow events occur, both Canyon Creek and Rattlesnake Creek
discharge to the Snake River. Base drainage discharges to Canyon Creek on the few occasions
when storm water is released from the dam across the Base storm water drain.
F. NATURE AND EXTENT OF CONTAMINATION
This section presents the findings of the soils, groundwater, sediment, and surface water
investigations for OUs 1, 3, 5, 6, Lagoon Landfill, and Fire Training Area 8 at MHAFB.
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1. Soils
Investigative Approach
Figure 4 is a flow diagram that shows the approach used. The approach consisted of six steps
which leads into the risk management decision-making process.
Step 1 in the process was to evaluate the site history and identify potential chemicals of
concern (PCOC) and possible "hot spot" release points. A PCOC was selected using the
site history to identify compounds and specific chemicals that may have been released at
a site. For chemicals except metals, if it was detected, it was considered a PCOC. For
metals, if it was considered a site-related chemical and it was above the established site
background, it was considered a PCOC.
Step 2 was the evaluation of Fire Protection Training Areas (other sites move directly to
Step 3) using soil vapor surveys to identify if volatile organic compounds (VOCs) were
present in the soils. If no VOCs were present, then no further investigation of the site
was done and all pathways were considered incomplete, thus eliminating the soil and
groundwater pathways. The criteria used included the exceedances of 1 ppm total volatile
organic hydrocarbons. If the 1 ppm was exceeded, the process moves to Step 3.
Step 3 of the process included the sampling surface and subsurface soil and analysis of
those areas where a release of chemicals ("hot spots") likely occurred. The identification
of release points was based on an evaluation of site history and processes used at the site.
If potential chemicals of concern or metals were detected above background, the site
moved to Step 4 of the process. If PCOCs were not detected and metals were below
background, the site was not evaluated further. Background concentration of metals for
Mountain Home AFB was established by collecting and analyzing samples from
noncontaminated areas at the Base and using the calculation of 1.5 times the 95% upper
confidence level of the mean as the background concentration for a specific metal analyte.
Step 4 of the process evaluated the PCOCs against USEPA Region 3 published Risk
Based Concentrations (RBCs). The RBCs are calculated concentrations that consider
residential exposure at the 1 in 1,000,000 excess cancer risk for the ingestion route. If
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Step 1
Step 2
StepS
Figure 4
Soils Investigation Approach
Evaluate Site History and identity potential
chemicals of concern and "Hot Spot" release points
Is the Site a Fire
Protection Training
Area?
Complete Soil Vapor Survey
to identify volatile
contamination
Use identified "Hot Spots" to complete
soil sampling and laboratory analysis
Q:\92520\A\RODSOIL.VSD /da!
MHAFB - Record of Decision for OUs 1, 3, 5, and 6
Are there detects of volatile
organic compound above 1 ppm?
No further investigation if
site contamination is
volatile organic
compounds.
Were any PCOC detected, or are
metals above backround levels?
Drop site from further
investigation
26
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Figure 4
Soil Investigation Approach-Continued
Step 4
For those PCOC that were
detected, or for metals above
background, compare the
concentration to RBCs
Are any of these
concentrations above the
s or background?
Remove site from further soils
evaluation and evaluate the
detectton(s) as part of the
Basewide Groundwater and
Ecological Assessment
Yes
I
StepS
Consideration is given to the
frequency of detection and the
concentration of detection
above RBCs or background
Step 6
Complete baseline risk
assessment and risk
management decision-making
process.
Q:\92520\A\RODSOIL. VSD /dal
MHAFB - Record of Decision forOUs 1,3, 5, and 6
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9/14/95
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none of the PCOCs were above the published RBCs, the site was removed from further
evaluation regarding the soils. However, all the detected PCOCs were further evaluated
as part of the Basewide groundwater evaluation and ecological assessment. This was done
to be conservative, to consider the mobility of a specific chemical, and to consider the
scenario that a given chemical, although below a risk concentration in soil, could be
transported to groundwater where it could pose a risk through ingestion. Another
consideration was the cumulative potential impacts of detected chemicals in soils on the
ecological receptors from the sites.
If the PCOCs were above the RBCs, the site was carried forward to Step 5.
Step 5 of the process evaluated the frequency of detections and the concentration of the
detection above the conservative EPA Region 3 RBCs.
Step 6 of the process was to complete the baseline risk assessment and risk management
decision-making process considering all aspects of the data and the sites likely future use.
The site was then either eliminated from further consideration or evaluated further in the
RI/FS process.
The following are the results of the soil investigation.
GUI and OU6 Sites
DP-09 Waste Oil Disposal Area. Soil samples collected at the site had no detected soil
contamination. Therefore, no exposure pathways for soil were evaluated, and the site was
removed from further consideration for potential releases to regional groundwater.
DP-18 Old Burial Trench. Four soil samples were collected at 15 test pits at the site. The
compound 1,2-dichloroethane was detected at 4 pg/kg, but this maximum concentration was 3
orders of magnitude less than EPA Region 3 RBCs. Therefore, no exposure pathways for soil
were evaluated, and the site was removed from further consideration for potential releases to
regional groundwater because no evidence of the past site disposal activity was observed and the
one chemical detection mentioned is likely due to laboratory contamination and not site related.
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FT-04 Fire Training Area 4. Soil gas samples were collected at 49 sampling points, and they
were analyzed for total volatile organic compounds (TVOCs) and for total benzene, toluene,
ethylbenzene, and xylenes (BTEX) using a field gas chromatograph. All samples were below the
1 ppm TVOCs' screening level criteria. Therefore, no exposure pathways for soil were evaluated,
and the site was removed from further consideration for potential releases to regional
groundwater.
FT-05 Fire Training Area 5. Soil gas samples were collected at 9 sampling points, and they
did not detect TVOCs or BTEX above the 1 ppm screening level criteria. Therefore, no exposure
pathways for soil were evaluated, and the site was removed from further consideration for
potential releases to regional groundwater.
FT-06 Fire Training Area 6. Soil gas samples were collected at 32 sampling points. At one
sampling point, TVOCs were detected above the 1 ppm screening level; however, all of the other
sampling points were below the screening-level criteria. Therefore, no exposure pathways for
soil were evaluated, and the site was removed from further consideration for potential releases
to regional groundwater.
FT-07A Fire Training Area 7A. Soil gas samples were collected at 43 sampling points, and
they did not detect TVOCs above the 1 ppm screening-level criteria concentration. Therefore,
no exposure pathways for soil were evaluated, and the site was removed from further
consideration for potential releases to regional groundwater.
FT-07B Fire Training Area 7B. Soil gas samples were collected at 45 sampling points.
TVOCs exceeded the 1 ppm screening-level criteria at some locations. Soil samples were
collected from 2 soil borings that were completed in "hot spot" areas identified by the soil gas
sampling. Soil samples were analyzed for VOCs, semivolatile organic compounds (SVOCs), total
recoverable petroleum hydrocarbons (TRPH), and metals. Chemicals detected in soil samples
included VOCs, SVOCs (no PAHs), TRPH, and metals. Several VOCs including solvents and
fuel constituents were detected in concentrations below their EPA Region 3 RBCs. Therefore,
no exposure pathways for soil were evaluated. Because VOCs were detected, the site was
evaluated for exposures via the groundwater pathway using fate and transport modeling.
FT-07C Fire Training Area 7C. Soil gas samples were collected at 55 sampling points.
TVOCs exceeded the 1 ppm screening level at several sample locations. Soil samples were
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collected from 2 soil borings that were completed in "hot spot" areas identified by the soil gas
sampling. Soil samples were analyzed for VOCs, SVOCs, TRPH, and metals. Chemicals
detected in soil samples included VOCs, metals, and TRPH. The maximum concentrations of
VOCs and TRPH were toluene at 37 ^g/kg and TRPH at 2640 mg/kg. VOCs were detected
below their EPA Region 3 RBCs. Therefore, no exposure pathways for soil were evaluated.
Because VOCs were detected, the site was evaluated for exposures via the groundwater pathway
using fate and transport modeling.
LF-03 Existing Landfill. Review of site operational procedures and records indicated that
hazardous wastes are not and have not been disposed at this site. Therefore, no sampling was
done at the site under CERCLA. No exposure pathways for soil were considered, and the site
was not evaluated for exposures via the groundwater pathway. The site is currently operating
under State landfill regulations.
LF-23 Solid Waste Disposal Area. Twelve soil samples were collected at this site (1 each at
12 test pits), and they were analyzed for VOCs, SVOCs and metals. Several SVOCs (all
polyaromatic hydrocarbons [PAHs]) were detected at 2 sample locations in concentrations slightly
(less than 1 order of magnitude) above their EPA Region 3 RBCs. The compounds and
concentrations that exceeded EPA Region 3 RBCs were benzo(a)anthracene (1,700 /xg/kg),
benzo(b)fluoranthene (1,700 /*g/kg), benzo(k)fluoranthene (830 /ig/kg), benzo(a)pyrene (130
/ig/kg), and indeno(l,2,3-cd)pyrene (650 /ig/kg). These concentrations are at the low end of the
range of concentrations (slightly about 10"6 threshold to excess cancer risk of a residential
scenario for ingestion) for EPA's target risk range for cleanup at Superfund sites. No quantitative
evaluations of exposure pathways for soil were considered. The mobility of PAHs in the soil-
water system is considered to be low, so the site was not evaluated for exposures via the
groundwater pathway.
OT-10 Perimeter Road. Sixteen soil samples were collected from 16 soil borings (1 per boring)
along the centerline and the edge of the road. Samples were analyzed for VOCs, SVOCs, TRPH
and metals. Several VOCs (e.g., 1,1-dichloroethane and 1,2-dichloroethane) and several SVOCs
(e.g., 4-nitrophenol and di-n-octylphthalate [a possible laboratory contaminant]) were detected at
several sample locations. The highest VOC and SVOC concentrations were 1,1-dichloroethane
at 4.4 jig/kg and benzoic acid at 120 ng/kg, respectively. All detected concentrations were 2 to
3 orders of magnitude less than compound-specific EPA Region 3 RBCs. Therefore, no exposure
pathways for soil were considered. Because several organic compounds were detected and
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because some of these compounds are known to be mobile in the soil-water system, the site was
evaluated for exposures via the groundwater pathway using fate and transport modeling.
OT-15 Corker Material Burial Area. Thirteen soil samples were collected from 3 soil borings
drilled at this site. All samples were analyzed for the element boron, the only potential chemical
of concern known to have been disposed at the site. Boron was not detected in any of the
samples, and the sample detection limit for all samples was several orders of magnitude less than
the EPA Region 3 RBC for boron. Therefore, no exposure pathways for soil were considered,
and the site was not evaluated for exposure via the groundwater pathway.
SS-26 Drum Accumulation Pad Near Building 208. Eight soil samples were collected from
4 soil borings (2 per boring), and they were screened for VOCs (the only potential compounds
of concern known to have been temporarily stored at the site) by headspace analysis using a
photoionization detector. No headspace readings were above background readings. Therefore,
no exposure pathways for soil were considered. Because of the possibility that liquid wastes may
have been accidentally released to soils hi the past, the site was evaluated for exposure via the
groundwater pathway using fate and transport modeling.
SS-28 Wash Water Accumulation Basin. Four soil samples were collected from 2 soil borings
(2 per boring), and they were analyzed for VOCs, SVOCs, TRPH and metals. Two VOCs,
trichloroethene (TCE) (17 /xg/kg) and methylene chloride (5.3 /xg/kg) (a possible laboratory
contaminant) were detected in 2 of the 4 samples. The concentrations of both VOCs were several
orders of magnitude below the EPA Region 3 RBCs; therefore, no exposure pathways for soil
were considered. Because VOCs were detected and because an applied-water driving-force
existed at the site in the past, the site was evaluated for exposures via the groundwater pathway
using fate and transport modeling.
SS-30 DRMO Storage Area. Four soil samples were collected from 2 soil borings (2 per
boring), and they were analyzed for VOCs, SVOCs, pesticides/PCBs, herbicides and metals.
Several VOCs (ethylbenzene 2 /ug/kg, TCE 4 /xg/kg, toluene 17 /xg/kg, xylenes 5.4 jig/kg, styrene
1.5 jig/kg, and benzoic acid 5 pig/kg) were detected in several of the soil samples. The
concentrations of all VOCs were several orders of magnitude below their RBCs; therefore, no
exposure pathways for soil were considered. Because VOCs were detected and because liquid
wastes may have been accidentally released to soils in the past, the site was evaluated for
exposures via the groundwater pathway using fate and transport modeling.
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ST-13 Former USTs at the POL Yard. Soil samples collected before and during the UST
removal at this site indicated that soil contained several VOCs. Because contaminated soils were
removed and because the site was closed under RCRA (including a RCRA cap), no exposure
pathways for soil were considered. Since liquid wastes may have been accidently released from
the USTs, the site was evaluated for exposures via the groundwater pathway by fate and transport
modeling. A 50-foot rock core was completed 60 feet east of the site to evaluate penetration of
liquid fuels into bedrock. This hole was drilled as part of another investigation and considered
here to evaluate the potential of petroleum product for ST-13 to migrate horizontally 50 feet and
penetrate bedrock. No evidence of organic contamination was found below 30 feet below ground
surface.
ST-22 Titan Missile Maintenance Area. Six soil samples were collected from 6 soil borings
(1 per boring), and they were analyzed for VOCs and for hydrogen ion concentration (pH).
Several VOCs were detected in several samples. Maximum concentrations were:
1,2-dichloroethane 1.5 /ig/kg, methylene chloride 6.5 /ig/kg (a possible laboratory contaminant)
and acetone 12 /ig/kg) (also a possible laboratory contaminant). Maximum concentrations of all
VOCs were between 2 to 6 orders of magnitude below their respective EPA Region 3 RBCs;
therefore, no exposure pathways for soil were considered. Because VOCs were detected and
because liquid wastes may have been accidentally released to soils in the past, the site was
evaluated for exposures via the groundwater pathway using fate and transport modeling.
SD-12 Entomology Shop Yard. Sixteen soil borings were drilled at this site. Fifty-two samples
collected from the soil borings were analyzed for pesticides/PCBs and for chlorinated herbicides.
Seventeen samples from the soil borings were analyzed for VOCs, SVOCs, and metals. Twenty-
three samples from the soil borings were analyzed for TRPH. Two discrete surface soil samples
were analyzed for metals. A number of VOCs (e.g., chlorobenzene, toluene, trichloroethene, and
1,1-dichloroethene) were all detected at a very low estimated maximum concentration of 2 /ig/kg
in site soils. Very low concentrations of SVOCs (e.g., less than 50 /ig/kg of
benzo(b)fluoranthene, benzo(k)fluoranthene, diethylphthalate, fluoranthene, and pyrene) were
detected in samples from 4 soil borings. Only one metal, lead, was detected, and it was detected
only in one surface soil sample at 32.2 /ig/kg, which is slightly greater than background
concentration. Herbicides and pesticides (e.g., MCPA, MCPP, alpha-chlordane, dieldrin, gamma-
chlordane, 4,4'-DDD, 4,4'-DDE, 4,4'-DDT, gamma-BHC, heptachlor, and aldrin) were detected
in the highest concentrations at 4,000 /tg/kg, 200,000 pig/kg, 1,300 /ig/kg, 2,900 /ig/kg,
1,200 fig/kg, 1,200 /ig/kg, 230 /tg/kg, 2,700 /ig/kg, 1.1 /ig/kg, 280 /xg/kg, and 120 /ig/kg,
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respectively. The highest concentrations and frequencies of detections occurred northwest of the
location of the former site building where rinse water was discharged to soils. Most pesticides
and herbicides were detected in surface or shallow subsurface soils. Because numerous
compounds were detected in site soils, and many of the detected chemicals were above EPA
Region 10 RBCs exposure pathways for soils were considered. Since the former practice of rinse
water discharge to soils may have resulted in transport of dissolved contaminants, and because
of the potential for chemicals to leach from soils, the site was evaluated for exposures via the
regional groundwater pathway using fate and transport modeling. Note: The investigation was
done in 1991 and considered EPA Region 10 RBCs; since that time EPA Region 3 issued updated
RBC tables.
SD-24 MWR Auto Hobby Shop. Fifty-one soil gas samples collected at 25 sample locations
were analyzed for halogenated compounds (GC calibrated to a TCE standard) and BTEX. Thirty-
three soil samples were collected from 17 soil borings, and they were analyzed for VOCs,
SVOCs, TRPH, and metals. Results showed a number of VOCs (2-butanone, acetone, methylene
chloride [all 3 are possible laboratory contaminants], toluene, TCE, xylenes, 1,2-dichloroethene,
and dibromochloromethane) detected hi soils. High concentrations (measured or estimated in the
range of 20 to 1,000 milligrams per kilogram) of VOCs (TCE, toluene, xylenes and
1,2-dichloroethene) were limited to soils in the immediate vicinity of a former waste collection
tank. All other detected VOC concentrations were in the range of a few to a few tens of jttg/kg.
The highest concentrations of SVOCs (mainly PAHs, benzo(a)anthracene, fluoranthene, and
pyrene [all in the range of 45-720 pig/kg]; and phenol and 2,4-dimethylphenol[in the range of
120 to 200 mg/kg]), and TRPH (in the range of 10,000 to 48,000 mg/kg) were also in soils
adjacent to the waste collection tank. Slightly elevated concentrations of TRPH, PAHs, and
metals (cadmium and lead) were found near the outfalls of 2 oil drainlines. Because elevated
concentrations of VOCs, SVOCs, TRPH, and metals were found in site soils and many of the
detected chemicals were above EPA Region 10 RBCs, exposure pathways for soils were
considered. Since contaminated soils found near the waste collection tank were likely caused by
leakage from the tank, and because of the potential for chemicals to be leached from soils, the
site was evaluated for exposures via the groundwater pathway using fate and transport modeling.
SD-27 Vehicle Wash Rack. Ten soil samples were collected from ten soil borings at this site.
All samples were analyzed for VOCs, SVOCs, TRPH and metals. In addition, 5 of the soil
samples were analyzed for pesticides/PCBs. Results show a large number of compounds are
present in soil/sediment at the site. VOCs detected include methylene chloride, 2-butanone,
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acetone (all three are likely laboratory contaminants), 1,1,1-trichloroethane, carbon disulfide,
ethylbenzene, tetrachloroethene, toluene, trichloroethene, and xylenes. Maximum concentrations
were for toluene (120 fig/kg) and xylenes (300 nf*/kg). All other concentrations were below 25
/zg/kg. SVOCs detected include mostly PAH compounds. The four compounds with the highest
detected concentrations are: fluoranthene (44 mg/kg), benzo(b)fluoranthene (32 mg/kg), chrysene
(19 mg/kg), and benzo(a)pyrene (18 mg/kg). VOC and SVOC concentrations were highest in a
short section of the site drainage ditch near its middle part. TRPH concentrations (maximum of
9,230 mg/kg) were highest in a small area near a lubricant dispensing area. A number of
pesticides (heptachlor epoxide, dieldrin, 4,4'-DDD, endrin, 4,4'-DDE, 4,4'-DDT, methoxy
chlordane, alpha-chlordane, and gamma-chlordane) were found in samples from the ditch.
Maximum concentrations ranged from 10 /tg/kg (4,4'-DDT) to 130 /xg/kg (4,4'-DDD). Five
metals were found at elevated concentrations in samples from the ditch and from near the
lubricant dispensing area: barium (1,570 mg/kg maximum), cadmium (5.2 mg/kg maximum),
chromium (99.1 mg/kg maximum), lead (161 mg/kg maximum), and zinc (329 mg/kg maximum).
Because of the elevated concentrations of the compounds in site soils and many of the detected
chemicals were above EPA Region 10 RBCs the site was evaluated for exposure pathways for
soil. Since the ditch receives wash water, and because of the potential for chemicals to leach
from soil, the site was evaluated for exposures via the regional groundwater pathway using fate
and transport modeling.
SS-29 Drum Accumulation Pad. Seventeen soil samples were collected from eight soil borings.
All samples were analyzed for VOCs, SVOCs, TRPH, and metals. Results showed VOCs
(2-butanone), methylene chloride [both are likely laboratory contaminants], toluene, xylenes,
1,1 -dichloroethane, 1,1,1 -trichloroethane, TCE, and tetrachloroethene). VOC concentrations were
low (maximum of 31 ptg/kg for 1,1,1-trichloroethane). A large number of SVOCs were detected,
and most were PAHs. The four SVOCs with the highest detected concentrations are fluoranthene
(54 mg/kg), benzo(b)fluoranthene (53 mg/kg), pyrene (46 mg/kg), and chrysene (23 mg/kg). The
maximum TRPH concentration was 10,800 mg/kg. Several metals were detected in elevated
concentrations: barium (4,270 mg/kg maximum, cadmium (748 mg/kg maximum), chromium
(117 mg/kg maximum), lead (369 mg/kg maximum), and zinc (471 mg/kg maximum). Maximum
concentrations of all compounds were restricted to a small area adjacent to the northwest and
southwest sides of the concrete pad at the site. Because of the elevated concentrations of the
compounds in site soils and many of the detected chemicals were above EPA Region 10 RBCs,
the site was evaluated for exposure pathways for soil. Since liquid wastes may have been
released at the site in the past, and because of the potential for chemicals to leach from soils, the
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site was evaluated for exposures via the regional groundwater pathway using fate and transport
modeling.
OT-16 Munitions Disposal Area. Eight surface soil samples were collected, and they were
analyzed for explosives and metals. Twelve subsurface soil samples were collected from two soil
borings and three test pits. Subsurface soil samples were analyzed for VOCs, SVOCs, pesticides/
PCBs, TRPH, and metals. In addition, the samples from the test pits were analyzed for
explosives. Results show that low concentrations (2 to 15 pig/kg) of VOCs (2-butanone), acetone,
methylene chloride [all three likely laboratory contaminants], and toluene) were detected in site
soils. Relatively high concentrations (maximums from 99 to 3,200 /xg/kg) of several PAHs
(benzo[a]anthracene, benzo[a]pyrene, benzo[b]fluoranthene,chrysene, fluoranthene, indeno[ 1,2,3-
cdjpyrene, and pyrene) were detected at the burn pit, and they are likely associated with past
burning activities. Because of the elevated concentrations of the compounds in site soils and
many of the detected chemicals were above EPA Region 10 RBCs, the site was evaluated for
exposure pathways for soil. Owing to the potential for chemicals to leach from soils, the site was
evaluated for exposures via the regional groundwater pathway using fate and transport modeling.
FT08-UST, UST at Fire Training Area 8. The tank sludge was sampled for flash-point
analysis, total organic halide, and metals to insure proper disposal procedures were followed for
the sludge. After removal of the UST, three soil samples were collected from the bottom of the
excavation, and they were analyzed for VOCs, SVOCs, pesticides/PCBs, and TRPH. Only one
compound, the VOC methylene chloride, was detected (1 to 2 /tg/kg). This compound is a
common laboratory contaminant, and it is not believed to be related to site activities. The
detected concentrations are well below the compound's EPA Region 3 RBC. Therefore, no
consideration of exposure pathways for soil were considered. Because of the possibility (although
believed to be remote) that a release of liquid waste may have occurred from the UST and may
have gone undetected, the site was evaluated for exposures via the regional groundwater pathway
using fate and transport modeling.
Fuel Sites
ST-11 Flight Line Fuel Spill. Ninety-nine soil gas samples were collected at 38 sample
locations. Samples were analyzed for total volatile hydrocarbons (TVHC) and BTEX using a
field gas chromatograph (GC). Results were used to select locations for 14 soil borings.
Seventy-six soil samples collected from the soil borings were screened in the field using
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headspace analysis, and fourteen of these samples (1 per boring) were also screened using
immunoassay analysis. Fourteen soil samples (1 per boring) were analyzed for BTEX, total
gasoline range organics (GRO), and lead.
Fifty-four soil or rock samples from the rock cores were screened by headspace analysis, and 14
of these samples were also screened by immunoassay analysis. Results showed fuel
contamination of benzene, toluene, ethylbenzene, and xylenes was present at the site. The
maximum detected concentrations of these contaminants are 15 mg/kg, 42 mg/kg, 60 mg/kg and
400 mg/kg, respectively. Benzene was in concentrations above EPA Region 3 RBCs hi soils near
the release point and along the fuel pipeline; therefore, exposure pathways for soils were
considered.
ST-31 BX Service Station. Fifty-five soil gas samples were collected at 20 sample locations.
Samples were analyzed for TVHC and BTEX. Results were used to select locations for 8 soil
borings. Forty-nine soil samples collected from the soil borings were screened using headspace
analysis. Sixteen of these samples (2 per boring) were analyzed for BTEX, GRO, TCO and lead.
Two rock cores were drilled into bedrock beneath site soils. Head space readings were taken on
rock samples from both rock cores, and 2 samples (top and bottom) were collected from a
granular interbed (soil material) encountered between 53 to 58 below ground surface in the deeper
of the 2 rock cores. The interbed samples were analyzed for BTEX and GRO. Four samples of
bedrock from the shallower of the two rock cores were analyed using immunoassay techniques.
Only the deepest interval in this rock core had results above the detection limit of 15 ppm. This
result was greater than 15 and less than 1,000 ppm for a sample from 28.5 feet below ground
surface. The results showed that residual gasoline contamination (benzene, toluene, ethylbenzene,
and xylenes) exists in site soils at maximum concentrations of 85.3 mg/kg, 644 mg/kg, 194
mg/kg, and 1,315 mg/kg, respectively, mainly at the bottom of the site UST excavation and in
soils at the northeast end of the excavation. Benzene was in a concentration above the EPA
Region 3 RBCs. For this reason, exposure pathways for soil were considered. The samples from
the interbed below the site were nondetect for fuel constituents; therefore, it is unlikely that fuel
has migrated to depth beneath the site. Because of the potential that fuels may have migrated to
depth somewhere other than the location of the rock core and because of the potential for fuel
constituents to be leached from soils, the site was evaluated for exposures via the regional
groundwater pathway using fate and transport modeling.
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ST-32 MX Service Station. Fifty-six soil gas samples were collected at 21 sample locations.
Samples were analyzed for Total Volatile Hydrocarbons (TVHC). Results were used to select
locations for 10 soil borings. One hundred and thirteen soil samples collected from the soil
borings were screened using headspace analysis. Twenty of these samples (2 per boring) were
analyzed for BTEX, Gasoline Range Organics (GRO), and Total Chromatographic Organics
(TCO), and lead. Two rock cores were drilled into bedrock beneath site soils. Headspace
readings were taken on samples from both rock cores, and samples from a granular zone at 154
feet below ground surface in the deeper of the 2 rock cores was analyzed for BTEX, GRO, TCO
and gasoline range petroleum hydrocarbons immunoassay. The results showed residual fuel
contamination (benzene, toluene, ethylbenzene, and xylenes) is present at maximum
concentrations of 1.8 mg/kg, 69.9 mg/kg, 48.6 mg/kg, and 474 mg/kg, respectively, in soils under
the east end of the old pump island pad and underneath the excavations where the former USTs
were removed. These levels are below the EPA Region 3 RBCs. However, to be conservative,
exposure pathways for soils were considered. Headspace readings and analytical results for
samples from the rock cores suggest that it is unlikely that bulk fuels migrated to depth beneath
the site. Because of the potential that fuels may have migrated to depth somewhere other than
the location of the deep rock core and because of the potential for fuel constituents to be leached
from soils, the site was evaluated for exposures via the regional groundwater pathway using fate
and transport modeling.
ST-34 Fuel Hydrant No. 9. Sixty soil gas samples were collected at 20 sample locations.
Samples were analyzed for TVHC and BTEX. Results were used to select locations for 4 soil
borings. Twenty-two samples collected from the soil borings were screened using headspace
analysis, and 4 of these (1 from the bottom of each boring) were further screened using
immunoassay analysis. Four of the 22 soil samples (1 per boring) were analyzed for BTEX and
GRO. Fuel constituents (toluene, ethylbenzene and xylenes) were detected in only 1 of the 4 soil
samples at a maximum concentration of 10.7 mg/kg, 7.5 mg/kg, and 139.2 mg/kg, respectively,
the one collected near the former metering pit. These concentrations are below the EPA Region
3 RBCs. Because fuel-related compounds were detected, exposure pathways for soils were
considered. Soil sampling indicated that it was unlikely that bulk fuels had migrated through soil
to bedrock; however, because of the potential that such migration had occurred and because of
the potential for fuel constituents to be leached from soils, the site was evaluated for exposures
via the regional groundwater pathway using fate and transport modeling.
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ST-35 Hospital Fuel Spill. Two soil borings were drilled at this site. Their locations were
based on records and interview information about the location of the fuel release. Eight samples
collected from the soil borings were screened using headspace analysis, and 2 of these samples
(1 from the bottom of each boring) were further screened using immunoassay analysis. All
screening analyses were nondetect. Since no evidence of contamination was found, no further
evaluation of the site was done.
OU5 Sites
RW-14 Low Level Radioactive Waste Container Storage Area. Investigation and source
removal actions done for RW-14 indicate that no radioactivity above naturally occurring
background levels exists in the site soils or air. Since the source was removed and no
contamination was detected, no further evaluation of the site was done.
Landfill #1
Lagoon Landfill LF-01 was investigated as part of OU2. During this investigation, soil,
groundwater, surface water, sediment, and bedrock samples were taken. The results of analyzing
soil, perched groundwater, and regional groundwater for VOCs, SVOCs, pesticides, PCBs,
herbicides, metals, and TPH revealed little or no evidence of contamination. Sediment and
wastewater samples indicated the presence of contamination. Sediment contained 6 VOCs,
5 SVOCs, DDT, DDD, DDE, alpha- and gamma-chlordane, heptachlor epoxide, Aroclor 1254,
cadmium, copper, lead, mercury, silver, and zinc. In the Baseline Risk Assessment, it was
concluded that there is no unacceptable risk to human health or ecological receptors from soil,
sediment, or wastewater exposure pathways. However, it was unclear how groundwater is
effected by the contaminants found at LF-01. For this reason, LF-01 groundwater is included
in OU3 Basewide groundwater. Results and recommendations for OU3 include the groundwater
influenced by LF-01.
2. Surface Water and Sediment
Surface water and sediment were sampled and considered at sites SD-25 and LF-01 where surface
water and sediment occur. Sediment was sampled at site SD-27; no surface water was present.
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SD-25 Flight Line Storm Drain. Sixteen sediment samples were collected and analyzed for
VOCs, SVOCs, pesticides/PCBs, TRPH, and metals (one soil sample was collected from a soil
boring with no detected chemicals). Four surface water samples were collected and analyzed for
VOCs, SVOCs, pesticides/PCBs, TRPH, and metals. Results show that only very low
concentrations of several VOCs (benzene, 0.24 /xg/L; bromodichloromethane, 1 /tg/L;
dibromochloromethane, 3 jig/L; toluene, 2 /ng/L; TCE, 0.2 pig/L; and xylenes, 4 /ig/L) and
SVOCs (2-methylnaphthalene, 2 /xg/L; 4-methylphenol, 27 /ig/L; naphthalene, 2 /xg/L;
pentachlorophenol, 4 /zg/L; and phenol, 8 /ig/L) were present in surface water. None of these
concentrations exceeded Federal Water Quality criteria.
A large number of compounds were detected in the sediment samples. The 4 VOCs with the
greatest maximum concentrations were xylenes (2,500 Mg/kg), chlorobenzene (890 /ig/kg), 1,2-
dichloroethene (470 jig/kg) and ethylbenzene (400 fig/kg). All other VOCs were present in
maximum concentrations of 2 to 71 /tg/kg. The 4 SVOCs with the greatest maximum
concentrations were the PAHs, fluoranthene (26 mg/kg), pyrene (19 mg/kg), benzo(b)fluoranthene
(16 mg/kg),'andchrysene(10mg/kg). The maximum TRPH concentration was 20.1 mg/kg. The
highest VOC, SVOC, and TRPH concentrations were ha sediment samples collected from a short
length of the storm drain where the outfalls of several drains from industrial facilities enter the
storm drain. Two PCB compounds were also detected in this area (Aroclor-1254, maximum
concentration of 1,800 /tg/kg, and Aroclor-1260, maximum concentration of 1,300 /ig/kg). A
number of pesticides (alpha-chlordane, beta-BHC, dieldrin, gamma-chlordane, heptachlor,
heptachlor epoxide, 4,4'-DDD, 4,4'-DDE, and 4,4'-DDT) were found along the entire length of
the drain in maximum concentrations that ranged from 3 to 650 /ig/kg. Four metals were found
throughout the drain at elevated concentrations, cadmium (47 mg/kg maximum), chromium
(231 mg/kg maximum), lead (998 mg/kg maximum), and zinc (559 mg/kg maximum).
Elevated concentrations of the compounds were detected in sediment and surface at the site with
many of the detected compounds above conservative Region 10 RBCs. Therefore, the site was
evaluated for sediment and surface water exposure pathways. Because the dram contains areas
of standing water and because chemicals can be leached from soil/sediment, the site was
evaluated for exposures via the regional groundwater pathway using fate and transport modeling.
SD-27 Vehicle Washrack Drainage Ditch. A total of 6 sediment samples were collected at this
site during the site investigations. Sediment samples were analyzed for VOCs, SVOCs,
pesticides/PCBs, metals, and TRPH. Several VOCs, SVOCs, pesticides/PCBs, metals, and TRPH
92520\A\520AOU3.ROD /dal/cee • 9/25/95
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were found in the site ditch sediments. VOCs detected included toluene, xylenes, ethylbenzene,
1,1,1 -trichloroethane, carbon disulfides, PCE, and TCE. Concentrations ranged from a low of
2 /zg/kg for toluene, PCE, and TCE to a high of 300 pig/kg for xylenes.
Several non-PAH SVOCs were reported in these sediment samples including dibenzofuran,
carbazole, and 4-methylphenol. Concentrations ranged from dibenzofuran at 73 /ig/kg to
carbazole at 2,900 pg/kg. High levels of total PAHs were reported in these samples ranging from
total concentrations of 1,706 ng/kg to 212,000 pig/kg. Several pesticides/PCBs, including DDE,
ODD, DDT, endrin, methoxychlor, endosulfan-sulfate, alpha-chlordane, and gamma-chlordane
were detected at two sediment sampling locations. Concentrations ranged from 15 fig/kg of
gamma-chlordane to 200 fig/kg of methoxychlor. TRPH was detected in all of the ditch sediment
samples at concentrations ranging from 82.3 mg/kg to 3,050 mg/kg. Metals detected above
calculated background concentrations, included arsenic, chromium, cadmium, lead, mercury, and
zinc. Due to concentrations of chemicals detected in site sediment, and many of the detected
compounds were above the Region 10 RBCs, the site was evaluated for sediment exposure
pathways. Because chemicals can be leached from the sediment, the site was evaluated for
exposures via the regional groundwater pathway using fate and transport modeling.
LF-01 Lagoon Landfill. Sediment and wastewater samples collected during the RI indicated the
presence of contamination. Sediment contained 6 VOCs ranging from 11 /ig/kg (xylenes) to
168 pig/kg (acetone); 5 SVOCs ranging from 5,300 fig/kg bis(2-ethylhexyl)phthalate to
6,200 /ng/kg of pyrene, fluoranthene, benzo(k)fluoranthene, and di-n-butylphthalate; DDT
(35,000 /xg/kg); DDD (410 jig/kg); DDE (76 fig/kg); alpha- and gamma-chlordane 15 fig/kg and
20 /ig/kg); heptachlor epoxide (16 /tig/kg); Aroclor 1254 (310 fig/kg); cadmium; copper; lead;
mercury; silver; and zinc.
Analytical results for sampling of the lagoons at LF-01 are presented as Tables 1, 2, 3, 4, and
4a shown in Appendix A. Water samples contained 2-butanone and benzene at 5 and 4 /ig/L,
respectively, and 1,2-dichlorobenzene (5 /zg/L), 4-methylphenol (5 /ig/L), phenol (5 figfL), and
naphthalene (7/ig/L). Because of the detections of chemicals of concern hi the site sediment and
wastewater and the detections being above Region 10 RBCs, a Baseline Human Health Risk
Assessment was completed. In the Baseline Risk Assessment, it was concluded that there is no
unacceptable risk to human health or ecological receptors from soil, sediment, or wastewater
exposure pathways. However, it was unclear how groundwater is effected by the contaminants
found at LF-01. For this reason, the LF-01 groundwater pathway is included in OU3 Basewide
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groundwater investigation. Results and recommendations for OU3 include the groundwater
influenced by LF-01.
3. Perched Groundwater
Perched groundwater was encountered at sites LF-01 and ST-11.
Perched Groundwater at LF-01. The perched groundwater at LF-01 was encountered in three
horizons below the site. None of the layers was continuous. Elevated levels of ions, such as
nitrates, were detected hi the perched zone at LF-01 in comparison to regional groundwater. The
source of the perched water is likely due to water from the lagoons at LF-01, infiltrating through
the vadose zone to a semipermeable layer where a perched zone was created. The perched zones
are confined mainly to fractured basalt and interflow zones. The exact horizontal extent is not
known, but likely is confined to the area directly below the lagoons as evidenced by a dry core
hole adjacent to the lagoon. LF-01 perched water is included in this section because it was
evaluated for its potential impact to the regional groundwater as part of the OU3 investigations.
LF-01 is presented in detail in the OU2 ROD.
Perched Groundwater at ST-11. Eight rock cores were drilled into bedrock beneath site soils,
7 of these encountered perched groundwater, and 5 of these were completed as temporary perched
groundwater monitoring wells. Perched groundwater was encountered at about 30 to 40 feet
below ground surface.
The perched water zone at ST-11 is confined mainly to a fractured zone hi the basalt bedrock.
This fractured zone exists immediately above a silty sand layer that was encountered in the rock
borings. This silty sand layer was observed to be dry during drilling activities. The lateral extent
of the perched water is uncertain, but appears to be at least 250 feet by 500 feet. It is not certain
from the data currently available whether the perched water encountered in the different locations
at the site is connected and represents a continuous, interconnected perched water layer.
However, the perched layer is likely limited in extent and volume. Field tests indicate that both
of these zones have limited capacity to be pumped.
Water samples from the 7 perched water cores were analyzed for BTEX, GRO, and total
chromatographable organics (TCO). The eighth rock core did not encounter perched water, and
it was drilled to 169 feet below ground surface. Maximum detected dissolved fuel constituents
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of benzene and xylenes were detected in perched groundwater in concentrations of 7,500 and
440 /ig/L, respectively. These are above EPA Region 3 RBCs for water ingestion. The
maximum total petroleum hydrocarbon for GRO and TCO was 12,000 mg/L. No RBCs exist for
the GRO and TCO analysis. Exposure pathways for perched groundwater were considered. The
site was also evaluated for exposures via the regional groundwater pathway using fate and
transport modeling.
4. Regional Groundwater
4.1 Pre-RI Investigations
The following is a summary of results from previous studies (results from USGS sampling, Base
monitoring of Base production wells, and sampling by the IDHW) on groundwater quality at
MHAFB:
• ' Mobile inorganic chemicals (chloride, sulfate, and nitrite + nitrate nitrogen)
associated with uifiltrating wastewater at the Base lagoons and with irrigation
water applied to the Base golf course have impacted groundwater at the Base.
• The time of travel required for the surface-applied water to reach the water table
was apparently short. Chloride concentrations in groundwater sampled at Base
production wells located adjacent to the Base golf course began to rise in the late
1950s. The source of chloride may be potassium fertilizers or naturally occurring
chloride hi site soils). The golf course was completed in 1956.
• A thin perched water zone has developed on top of an interbed several tens of feet
above the regional water table and below the wastewater lagoons. Concentrations
of inorganic solutes are higher in the perched water when compared to
concentrations in the regional aquifer near the lagoons. The inorganic solutes are
below MCLs except for nitrate.
• Concentrations of a number of volatile organic compounds (below MCLs) have
been detected in Base production wells.
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• Trichloroethene (TCE) has been detected in concentrations that are usually below
the MCL and are 2 /xg/L or less in Base production wells and Base monitoring
wells. The source of the TCE appears to be consistent with historical release from
an area or areas in the south-central part of the Base. One measurement of TCE
was above the 5 /ig/L MCL; however, this was from data collected that was not
part of this investigation and did not contain proper QA/QC or validation.
• Several compounds that belong to the class of compounds known as trihalo-
methanes (THMs), including chloroform, bromoform, bromodichloromethane, and
chlorodibromomethane, have been detected in Base production wells, but they
have not been detected in Base monitoring wells. The source of the THMs may
be the chlorination equipment used for the Base water supply system (wellhead
chlorination units).
4.2 Remedial Investigation Results
Analytical results from sampling of wells at the Base are presented as Tables 5 through 31 shown
in Appendix A. Up to four rounds of groundwater sampling at 8 Base production wells, 18 Base
monitoring wells, and 5 off-Base irrigation wells were performed as part of the OU3 RI. Results
indicate that TCE was the only CERCLA related contaminant that was consistently detected hi
several wells; however, all concentrations of TCE except for one sample, were well below
(2 /ig/L) the MCL of 5 /xg/L set by the Safe Drinking Water Act (SDWA). The one sample that
had an exceedance of the MCL had a TCE concentration of 14.7 /xg/L; however, this sample did
not have an approved quality control program, and the result is questionable. In addition to TCE,
other volatile organic compounds were also detected in the groundwater at levels below MCLs.
Table 32 identifies the chemicals of concern that were detected in the regional groundwater.
Table 33 shows the maximum detected concentrations of chemicals that were detected in the
regional groundwater.
Many of the metals species detected by the four rounds of groundwater sampling are near
apparent background concentrations. The background concentrations for metals were determined
by the average concentrations for the upgradient western Snake River Plain regional aquifer, or
median concentrations for Elmore County, Idaho. Metals that exceed apparent background
conditions for the aquifer are present in concentrations below levels of concern (EPA maximum
contaminants levels [MCLs]) except for one detection of cadmium that was slightly above
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TABLE 32
CHEMICALS OF CONCERN DETECTED IN GROUNDWATER
FROM EITHER BASE PRODUCTION OR MONITORING WELLS
4-Nitrophenol
Acetone
Aluminum
Barium
Benzene
Bis(2-ethylhexyl)phthalate
Bromoform
Cadmium
Chromium
Cobalt
Copper
Di-n-octylphthalate
Lead
Manganese
Mercury
Methylene Chloride
Nickel
Pentachlorophenol
Trichloroethene
Vanadium
Zinc
Note: Zinc does not have EPA-«stablished toxicity factors.
92520\A\ROD\520A3ROD.T32 /dal 09/14/95
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TABLE 33
MAXIMUM DETECTED GROUNDWATER CONCENTRATIONS
AT ALL BASE WELLS TO RBCs{1)
Well ID
OU3-BPW2-RGW-002
OU3-BPW4-RGW-002
OU3-BPW2-RGW-001
OU3-MW6-RGW-001
OU3-BPW4-RGW-001
OU3-BPW7-RGW-002
OU3-MW8-RGW-002
OU3-BPW5-RGW-001
OU3-MW1-RGW-004
OU3-BPW9-RGW-001
OU3-MW06-RGW-001
OU3-MW16-RGW-004
OU3-MW17-RGW-002
OU3-BPW9-RGW-001
OU3-BPW1-RGW-004 and
OU3-BPW9-RGW-001
OU3-BPW9-RGW-001
Chemical
4-Nitrophenol
Acetone
Benzene
Bis(2-ethylhexyl)phthalate
Bromoform
Cadmium
Chromium
Copper
Di-n-octylphthalate
Lead
Mercury
Methylene Chloride
Nickel
Pentachlorophenol
Trichloroethene
Zinc
Maximum Detected Concentrations (ug/L)
1
10
1.4
120
3
5.2
14.7
53
3
7.3
0.2
2
16.3
0.65
3
840
MCL(5)
(ug/L)
--
--
5
--
100
5
100
1300(6)
15
2
--
100
1
5
—
RBC(1) (ng/L)
2300
3700
0.36
4.8
2.4
18
180(2)
1400
730
15(3)
11
4.1
730
0.56
1.6
NA
(l> RBC is the EPA Region III risk-based concentration for residential tap water based on a Iff6 excess cancer risk level and a Hazard Quotient of 1 for noncancer effects (EPA 19
m RBC is for chromium VI and compounds
<3) No Region III RBC available for lead. Value is the action level defined in the May 1993 Drinking Water Regulation and Health Advisory (EPA 1993).
<4) Estimated risk at maximum detected concentration based on RBC comparison. Risk = (maximum cone. / RBC) * 1 x 10"6
(5> EPA maximum contaminant level
(6) EPA action level
NA = RBC not available because there are no EPA-established toxicity factors for this compound.
Note: No noncarcinogens exceeded RBCs; therefore, no total Hazard Index was calculated.
92520U\[RD2T01.XLS]TABLE 33 /md/cee
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(5.2 pig/L versus 5.0 /ig/L). This concentration is still below the conservative EPA Region 3
RBC for water ingestion. Background concentrations for metals are shown in Table 34.
G. GROUNDWATER MODELING RESULTS
Fate and transport modeling was used to identify sites that may have in the past, are currently,
or may in the future release COCs to the regional groundwater aquifer. Table 35 lists the COCs
and the sites where the COC was modeled. The concentrations used in the modeling were the
maximum detected for a site. The modeled concentrations in groundwater were compared to
MCLs and EPA Region 3 health risk-based concentrations (RBCs) for groundwater ingestion.
The models used are highly conservative and would tend to overestimate actual chemical
concentrations. The EPA Region 3 RBCs are conservative criteria that consider ingestion of
groundwater under a residential scenario.
Where high degrees of uncertainty existed with regard to model parameters, the fate and transport
modeling used conservative assumptions regarding factors such as source concentrations,
infiltration rates, vadose zone transport parameters, and degradation rates. When the net impact
of all model parameter and assumption uncertainty is considered, the probability is high that the
model could be expected to significantly overestimate potential groundwater concentrations of
COCs.
The method used to calculate the peak 30-year average exposure point concentrations includes
peak concentrations from past years before current or future exposures could occur. This
approach is likely to significantly overestimate potential exposure point concentrations.
Table 36 shows the analytes and the sites where modeled results exceeded MCLs or RBCs. The
modeled concentrations given in Table 36 are the peak 30-year average concentrations that are
estimated to occur at the location of the model-predicted present-day peak concentration in
groundwater. That is, the fate and transport model was used to predict the location in the
groundwater of the highest concentration of each analyte from each source area. The model was
then used to predict the 30 highest consecutive annual concentrations at this location. The
average of these 30 concentrations was then considered to be the reasonable maximum exposure
concentration for a residential receptor.
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TABLE 34
CONCENTRATIONS OF DISSOLVED METALS (BACKGROUND)
IN GROUNDWATER IN WELLS IN ELMORE COUNTY, IDAHO (jig/L)
Location
5S-8E-34BDC2
5S-10E-30CAC1
5S-7E-24DDD1
5S-6E-16DBD1S
4S-3E-35BCA1
4S-2E-25DAD1
4S-5E-25BBC1
4S-9E-3DCA1
4S-6E-2DAA1
3S-6E-14CDA1
3S-7E-8CAA1
Date
9/12/80
9/15/80
9/12/80
9/23/90
8/19/80
9/24/80
6/2/81
9/10/80
5/27/81
11/21/80
5/21/81
Al As
10
3
7
5
18
7
10
6
10
5
10
Ba Be B Cd Cr Co Cu Fe
- 140 150
60 - - - - 30
• 110 - - - - 30
60 <10
- 120 <10
10 <1 - <1 ND <3 <10 <10
30 - - - - - 10
7 <1 - <1 ND <3 <10 <10
9 <1 - <1 1 <3 <10 <10
Pb Li Mn Mo
40 160
- 600 1
60 140
10 <1
2
- 60 <1
<10 7 <1 <10
10 <1
<10 <4 1 <10
1 ...
<10 <4 <1 <10
Sr V . Zn
4
- 130
- 100
- <3
.
- 490
45 23 <3
- 40
62 11 41
.
51 13 10
Source: Wood and Low (1988)
Note: - = data not available
ND = nondetect
52520\A\IKn2T0I.XLS |TA»l.li34/md/ccc
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TABLE 35
CHEMICALS OF CONCERN IN GROUNDWATER BASED ON
FATE AND TRANSPORT MODELING RESULTS00
Chemical of Concern Site Where Detected in Soil
Arsenic Landfill 2 (LF-02)
Trichloroethene Fire Training Area 7B (FT-07B)
1,1,2-Trichloroethane Fire Training Area 7B (FT-07B)
Chloroform Fire Training Area 7B (FT-07B)
Trichloroethene Fire Training Area 7C (FT-07C)
Chloroform Fire Training Area 7C (FT-07C)
Trichloroethene Fire Training Area 8 (FT-08)
Chemicals of concern selected based on results of fate and transport modeling. Only trichloroethene has been detected
in groundwater on the Base.
92520\A\ROD\520A3ROD.T35 /dal 09/14/95
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TABLE 36
MODEL-ESTIMATED PEAK 30-YEAR AVERAGE CONCENTRATIONS
COMPARED TO EPA REGION HI RBCs(a)
Site
LF-02
FT-07B
FT-07C
FT-08
Peak 30- Year
Average
Concentration
Chemical (/tg/L)1*1'
Arsenic 14 Peak 30-year average concentration based on results of fate and transport modeling (see Sections 8.0 and 9.0)
ArsenicconcentrationmodeledtogroundwateratcenterofLF-02(14 fig/L). Quoted exposure point concentration at edge
of Landfill 2 is-expected to be lower by a factor of 10 to 100, and resulting risks will be lower by the same factor (see
text).
(f) Total cancer risk for FT-07B
fe> Total cancer risk for FT-07C
Note: Predicted cancer risk levels for FT-07B, FT-07C and FT-08 are for contaminants predicted by fete and transport
modeling to be present in groundwater. Predicted cancer risk level for LF-02 is for a contaminant predicted by
fate and transport modeling to reach the groundwater over 6,000 years in the future.
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This is a very conservative approach because some of the years with the highest predicted
concentrations occurred in the past. As a result, the modeling is likely to overestimate the actual
condition. This conservatism was built into the model to offset uncertainties in other components
of the modeling.
The modeled concentration of arsenic in groundwater was 14 jig/L, which is below the MCL
(50 mg/L) (expected to reach regional groundwater in 6,000 years). This concentration exceeds
the Region 3 RBCs by a factor of 370. The modeling results indicated that TCE and two
inorganic compounds may reach the aquifer at levels slightly above safe drinking water standards.
As noted, the model used conservative assumptions. As a result, the modeling is likely to
overestimate the actual condition. The model-estimated concentration of trichloroethene
(9.4 ftg/L) exceeded the MCL (5 jig/L). The model-estimated concentrations of all other analytes
were below the respective MCLs.
For Site ST-11, benzene, ethylbenzene, toluene, and xylenes were chemicals of concern. Model-
estimated concentrations in groundwater from infiltration of perched groundwater at ST-11 of
ethylbenzene, toluene, and xylenes were below detectable quantities. The model-estimated
concentration of benzene was 0.6 [ig/L which is significantly below MCLs.
H. POTENTIALLY EXPOSED POPULATION
MHAFB is likely to remain a military installation in the near future of 30 years. Currently,
humans who might be directly exposed to chemicals in the soils at each site are Base employees
(occupational receptors) who are assumed to work at the site for 25 years. This is a conservative
approach because the standard tour of duty at MHAFB is three years, and because chronic daily
exposures do not occur at most sites. However, occupational exposures are the best guide to
potential risks likely to occur at the sites under current or future use.
For hypothetical future scenarios, trespassers or recreational receptors (ages 6 to 12 years) are
assumed to be exposed to ditch sediments and water; and residents are also assumed to be
exposed to the regional groundwater and soil.
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VI. SUMMARY OF SITE RISKS
The following section provides an indication of the risks to human health and the environment
that are posed by the sites addressed in this ROD. Human health risks are described by
discussing the types of contaminants, the exposures including pathways, exposed population, a
toxicity assessment, and risk characterization. Environmental risks are addressed for the actual
or potential threat to plant and animal species from chemicals released from the sites.
A. HUMAN HEALTH RISKS
1. Contaminant Identification
The media contaminant and concentrations of concern for each site are summarized in the
Summary of Site Characteristics section.
2. Exposure Assessment
Exposure Pathways
The exposure pathway evaluated in the quantitative baseline risk assessments are listed below:
Current and Future Base Workers
• Incidental ingestion of soil or sediment
• Inhalation of volatile chemicals and particulate matter released from soil
• Dermal contact with soil or sediment
• Dermal contact with surface water
Note: Exposure to sediment and surface water were at LF-01 and Flight Line Storm
Drain.
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Future Hypothetical Trespassers (Recreational Users) at Flight Line Storm Drain
• Incidental ingestion of sediment
• Dermal contact with sediment
• Inhalation of volatile chemicals and particulate matter released from sediment
• Dermal contact with surface water
Future Hypothetical On-Site Residents
• Incidental ingestion of soil
• Inhalation of volatile chemicals and particulate matter released from soil
• Dermal contact with soil
• Ingestion of, dermal contact with, and inhalation of volatile emissions from
groundwater
Potentially Exposed Population
Current Use Scenario
Base employees (occupational receptors), who are assumed to work at the site 25 years, are the
likely population who could be directly exposed to chemicals. The average tour of duty at the
Base is three years, and chronic daily exposures do not occur at most sites. Therefore, addressing
long-term occupational exposure is a conservative approach. Trespassers were not evaluated
because exposures and risks would be lower than for on-site workers.
Future Use Scenario
Humans who might be directly exposed to chemicals at the sites if industrial activities resume
would be workers. Hypothetical on-site future residential scenarios were evaluated as a maximum
exposure to soils, air, and groundwater. If no unacceptable risks were calculated using the
residential scenario, no other scenario was considered because this scenario would show the likely
highest potential risk.
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Monitoring/Modeling Data and Exposure Point Concentrations
Chemicals evaluated as potential chemicals of concern in the RI, are chemicals that have been
released from past disposal practices. Chemicals with EPA-established toxicity factors were
evaluated quantitatively in the risk assessment; chemicals without EPA-established toxicity factors
were addressed qualitatively. Metals within background level and common laboratory and field
contaminants are not potential chemicals of concern. Furthermore, metals that are essential
nutrients (e.g., calcium, magnesium, iron, potassium, and sodium) are not considered potential
chemicals of concern. The RME metals concentrations in designated background soil samples
are shown on Table 37.
The exposure point concentration for soils and sediment used to estimate risks included the
arithmetic mean and upper 95 percent upper confidence limit (UCL) on the mean soil and
sediment concentrations calculated using sample analytical results for each RI site. The
95 percent UCL concentration accounts for the uncertainty associated with the estimation of the
mean, and is' used to represent the reasonable maximum exposure (RME) concentrations. If the
calculated 95 percent UCL concentration exceeds the maximum detected concentration, the
maximum is used for RME concentration. Tables 38 and 39 (shown in Appendix A) summarize
the RME concentrations for organic chemicals and metals of concern in soils and sediments, and
surface water at Basewide locations.
The exposure point concentration for surface water was the RME calculated for surface water
from samples at the Flight Line Storm Drain.
The exposure point concentrations for groundwater are the maximum modeled concentration and
the maximum detected concentrations at Base monitoring/production wells.
The exposure point concentration for air emissions was calculated using a screening-level air
emission and dispersion model to estimate air concentration due to wind erosion and volatilization
of chemicals at each RI site. Airborne emissions from soils resulting from volatilization of
volatile organic compounds and emissions of semivolatile compounds, pesticides/PCBs,
herbicides, and metals associated with wind erosion of particulate matter (dust) less than
10 microns in diameter were evaluated. RME air concentrations were estimated using reasonable
maximum soils concentrations.
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TABLE 37
RME METALS CONCENTRATIONS IN
DESIGNATED BACKGROUND SOIL SAMPLES (mg/kg)
Analyte
Background Level
Aluminum
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Copper
Lead
Mercury
Nickel
Silver
Vanadium
Zinc
23616
4.5
274
1
<.06
21.2
10.3
20
17.5
0.1
22.2
0
37.4
65
Source: W-C 1992a.
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3. Toxicity Assessment
The toxicity assessment addresses the potential for a chemical of concern to cause adverse effects
in exposed populations and estimates the relationship between extent of exposure and extent of
toxic injury (dose-response relationship) for each chemical.
Qualitative and quantitative toxicity information for the chemicals of concern is acquired through
evaluation of relevant scientific literature. The most directly relevant data come from studies in
humans. However, most of the useable information on the toxic effects of chemicals comes from
controlled experiments in animals. The result of toxicity assessments performed by EPA is the
development of chemical-specific toxicity factors for the inhalation and oral exposure routes.
These toxicity factors are published in the Integrated Risk Information System (IRIS) and the
Health Effects Assessment Summary Tables (EPA 1992).
EPA toxicity factors are used to assess potential health risks resulting from the estimated chemical
intakes. Toxicity factors are expressed either as reference doses (RfDs) for noncarcinogenic
compounds or cancer slope factors (SFs) for carcinogens. RfDs are used to estimate the potential
for noncarcinogenic (toxic) effects of substances. An RID is the daily dose of a noncarcinogen
that is not likely to result in toxic effects to humans over a lifetime of exposure. RfDs are
derived from human epidemiological studies or animal studies to which safety factors have been
applied (e.g., to account for the use of animal data to predict effects in humans). RfDs are
expressed in units of mg chemical/kg body weight/day. Estimated daily chemical doses from
exposure to contaminated media are compared to the RfD to estimate the potential for toxic
effects.
Slope factors (SFs) have been developed by EPA for estimating excess lifetime cancer risks
associated with exposure to potential carcinogens. SFs, which are expressed in units of
(mg/kg-day)"1, are multiplied by the estimated daily dose of a potential carcinogen, in mg/kg-day,
to provide an upper-bound estimate of the excess lifetime cancer risk associated with exposure
at that dose level. The term "upper-bound" reflects the conservative estimate of the risks
calculated from the SF. Use of this approach makes underestimation of the actual cancer risk
highly unlikely. Slope factors are derived from the results of human epidemiological studies or
chronic animal studies, which applies mathematical extrapolation from high doses to low doses
(e.g., to account for the use of animal data to predict effects on humans).
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4. Risk Characterization
Risk Quantification
The risk characterization combines the outputs of the exposure and toxicity assessments to
develop quantitative estimates of health risks associated with the site. Noncarcinogenic health
risks are characterized by comparing the estimated daily chemical dose to the RfD. The ratio of
the estimated dose to RfD is called the hazard index. Hazard indexes are added together for all
chemicals and exposure pathways to yield a total hazard index for the combined exposures. A
hazard index equal to or less than 1 indicates that no adverse noncarcinogenic health effects are
expected to occur, even to sensitive individuals over a lifetime of exposure.
Carcinogenic health risks are characterized as the excess probability (for example, 1 in 1,000,000)
that an individual will develop cancer due to the estimated exposure. Excess probability means
the increased risk over and above the normal risk of getting cancer. Cancer risks are calculated
by multiplying the estimated daily chemical intake by the chemical-specific cancer slope factor.
Cancer risks are calculated separately for each carcinogen and each exposure pathway, and then
added together to yield a total upper-bound estimate of cancer risk due to the combined
exposures. This is a highly conservative approach, which makes underestimation of the actual
cancer risk unlikely.
EPA has established an acceptable target excess cancer risk range of 1 x 10"6 to 1 x 10"4 (1 in
1,000,000 to 1 in 10,000) as guidance for protection of public health from exposure to chemicals
released from Superfund sites (EPA 1989). An excess lifetime cancer risk of 1 x 10"4 indicates
that an individual has an extra one in ten thousand chance of developing cancer over a lifetime
of exposure to site-related carcinogens.
Site-specific average risk estimates were calculated using reasonable best estimates. Site-specific
RME and standard default RME risk estimates were calculated using conservative (health-
protective) best estimates of probable exposures under various exposure scenarios. Standard
default exposure factors were used for most of the sites at MHAFB.
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Risk Estimation Using Investigation Results
The maximum detected concentrations of all the COCs in regional groundwater were below the
MCLs during the MHAFB OU3 RI. Furthermore, any detected chemical compounds were
compared to EPA Region 3's RBCs, and risks associated with these chemicals were calculated
using EPA Region 3 RBCs exposure factors, scenario, etc. A total cumulative risk of 3 x 10~5
was estimated for ingestion of regional groundwater. Table 40 compares the maximum detected
groundwater concentrations at all Base production wells to EPA Region 3 RBCs.
A number of perched groundwater bodies were found at MHAFB. In the perched water (27 feet
bgs) at Site ST-11, the concentration of some volatile chemicals such as benzene, toluene, and
ethylbenzene were above MCLs. Using EPA Region 3 RBCs conservative exposure factors, a
total risk of 2 x 10"2 was estimated for ingestion of perched groundwater as drinking water.
However, as shown in the RI section of this ROD, the contaminants currently present in the
perched water at ST-11 do not present an unacceptable risk to the regional groundwater.
Risk Estimation Using Modeling Results
Table 36 shows the results of risk assessment that was performed using 30-year peak modeled
concentrations. Only chemicals that exceeded MCLs or Region 3 RBCs were included in the
risk evaluation. Arsenic (from LF-2) presents a risk of 3.7 x 10"*, which exceeds EPA's
acceptable risk range of 10"6 to 10"4 for carcinogens. However, the assumptions that were used
for the model were conservative. As a result, the modeled concentrations are likely to
overestimate the future condition, and the future risk that is associated with groundwater
ingestion. Therefore, no unacceptable human health risks are expected due to exposure to
regional Snake River Plain aquifer groundwater at MHAFB.
Uncertainty
Throughout the human health risk assessment, conservative assumptions regarding exposure
concentrations, exposure conditions, toxicity, and risk characterization were used that tend to
overestimate potential risk. The chief conservative assumptions and other uncertainties affecting
the risk assessment are discussed here.
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TABLE 40
COMPARISON OF MAXIMUM DETECTED GROUND WATER CONCENTRATIONS
AT ALL BASE WELLS TO RBCs(1)
Well ID
OU3-BPW2-RGW-002
OU3-BPW4-RGW-002
OU3-BPW2-RGW-001
OU3-BPW2-RGW-002
OU3-BPW4-RGW-001
OU3-BPW7-RGW-002
OU3-MW8-RGW-002
OU3-BPW5-RGW-001
OU3-MW1-RGW-004
OU3-BPW9-RGW-001
OU3-MW06-RGW-001
OU3-MW16-RGW-004
OU3-MW17-RGW-002
OU3-BPW9-RGW-001
OU3-BPW1-RGW-004 and
OU3-BPW9-RGW-001
OU3-BPW9-RGW-001
Chemical
4-Nitrophenol
Acetone
Benzene
Bis(2-ethylhexyl)phthalate
Bromoform
Cadmium
Chromium
Copper
Di-n-octylphthalate
Lead
Mercury
Methylene Chloride
Nickel
Pentachlorophenol
Trichloroethene
Zinc
Maximum Detected
Carcinogens? Concentrations (ug/L)
NO
NO
YES
YES
YES
YES
YES
NO
NO
NO
NO
YES
NO
YES
YES
NO
1
10
1.4
120
3
5.2
14.7
53
3
7.3
0.2
2
16.3
0.65
3
840
MCL<5>
(Hg/L)
--
-
5
-
100
5
100
1300(S)
—
150(<)
2
--
100
1
5
-
Carcinogenic Risk at
Exceeds RBC Maximum Detected
RBC(1) (ug/L) ? Concentrations05
2300
3700
0.36
4.8
2.4
18
180<2)
1400
730
153)
11
4.1
730
0.56
1.6
NA
NO
NO
YES
YES
YES
NO
NO
NO
NO
NO
NO
NO
NO
YES
YES
NA
Total Cancer Risk
3.9E-06
2.5E-05
1.3E-06
2.9E-07
8.2E-08
4.9E-07
1.2E-06
1.9E-06
3.4E-05
(l) RBC is the EPA Region III risk-based concentration for residential tap water based on a 10"* excess cancer risk level and a Hazard Quotient of 1 for noncancer effects (EPA 1994).
(2) No Region HI RBC is available for lead. Value is the action level defined in the May 1993 Drinking Water Regulation and Health Advisory (EPA 1993).
(3) Estimated cancer risk at maximum detected concentration based on RBC comparison. Risk = (maximum cone. / RBC) * 1 x 10"6
NA = RBC not available because there are no EPA-established toxicity factors for this compound.
Note: No noncarcinogens exceeded RBCs; therefore, no total Hazard Index was calculated.
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9/14/95
Rev. 0
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Risk evaluation of groundwater was conservative because EPA Region 3 RBCs
were deemed to be conservative.
Uncertainties are inherent in any modeling effort, and the conservative
assumptions used are likely to overestimate the risk to human health in the actual
future condition. ST-11 is the only site that would present an unacceptable risk
if the perched groundwater were used as a drinking water source in a future
residential scenario.
EPA RfDs used in calculating RBCs are based on conservative estimates of the
potential for adverse noncarcinogenic effects. Most RfDs are developed by
reducing the dose at which no adverse effects were observed in the most sensitive
animal species by uncertainty factors ranging from 10 to 10,000. This
extrapolation method provides a considerable level of conservatism in the RfDs
used to estimate the potential for noncarcinogenic health effects and could result
in an overestimate of potential hazards by several orders of magnitude.
EPA slope factors used in calculating RBCs are highly conservative estimates of
dose-response relationships and probably result in a significant overstatement of
actual cancer risk and in very conservative (low) RBCs. Cancer SFs are calculated
using the 95 percent UCL on a dose-response curve estimated by a linear
mathematical model that extrapolates from short-term, high-dose animal exposures
to long-term, low-dose human exposures. EPA guidance states that the cancer SFs
are upper-bound estimates of potency, and actual potency is likely to be lower
(therefore, RBCs could be higher).
Zinc was considered a chemical of concern, but it was not evaluated in the
quantitative risk assessment because it does not have EPA-established toxicity
factors. EPA has established toxicity factors for hundreds of potentially hazardous
compounds associated with waste materials, and detected analytes without toxicity
factors often have no known adverse affects or data are inadequate for quantitative
risk assessment. The exclusion of zinc from the quantitative analysis is not likely
to affect the results or conclusions of the risk assessment relative to the chemicals
with known toxicities.
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• Health risks due to exposures to TPH were not addressed quantitatively in the risk
assessment. Exclusion of TPH is expected to have little effect on the risk results
because the major toxic constituents of TPH (e.g., benzene, ethylbenzene, toluene,
xylene, PAHs) were evaluated quantitatively, and other constituents of TPH are
not likely to contribute significantly to health risk.
• Cumulative carcinogenic risks were estimated assuming that effects of individual
chemicals are additive. This approach does not account for potential synergism,
antagonism, or differences in target-organ specificity and mechanism of action.
This approach may over- or underestimate actual health risks.
Summary of Human Health Risks
The following sites had no detected chemicals hi soils, and no further action was recommended:
• Waste Oil Disposal Area (DP-09)
• Corker Material Burial Site (OT-15)
• Old Burial Trench (DP-18)
• Fire Training Areas 4, 5, and 7A (FT-04, FT-05, and FT-07A)
• Drum Accumulation Pad Near Building 208 (SS-26)
• Hospital Fuel Spill (ST-35)
• Low-Level Radioactive Waste Container Storage Area (RW-14)
• Underground Storage Tanks at Fire Training Area 8 (FT-08 UST)
For sites that had detectable levels of contaminants present in soil and/or sediment and/or surface
water, degree of risk associated with ingestion, inhalation, and dermal contact of contaminated
media was characterized hi the risk assessment. Potential risks were calculated for present and
future occupational exposures and for hypothetical future residential exposures. According to the
risk assessments, the following sites presented no unacceptable risks.
• Old Entomology Shop (SD-12)
• Former Auto Hobby Shop (SD-24)
• Flight Line Storm Drain (SD-25)
• Munitions Disposal Area (OT-16)
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• Flight line Fuel Spill (ST-11)
• BX Service Station (ST-31)
• Fuel Hydrant #9 (ST-34)
The following sites showed some potential for health risks under certain conservative exposure
scenarios. The vehicle wash rack (SD-27) and the drum accumulation pad (SS-29) showed
cancer risks of 3 x 10"* and 2 x 10"4, respectively, for hypothetical future residential exposures.
However, as discussed in the OU-6 RI, both of these sites are quite small (e.g., 20 x 20 feet)
making any significant exposure unlikely, and residential development at these sites is unlikely.
Therefore, the risks due to residential exposures are likely overestimated. No unacceptable risks
were calculated for occupational exposures; therefore, no unacceptable risks are expected for
likely exposures at these sites.
The MX (ST-32) showed a noncancer hazard index of 1.5 for hypothetical future residential
exposures to soil. This slightly exceeds the target index of 1.0, however residential development
at this site is unlikely. Therefore, the risks due to residential exposures are likely overestimated.
No unacceptable risks were calculated for occupational exposures; therefore, no unacceptable risks
are expected for likely exposures at these sites.
Regional Groundwater Exposure Pathway
Risks associated with contaminants in groundwater were also assessed by comparing measured
concentrations of contaminants in the groundwater and model-predicted future concentrations in
groundwater to conservative risk-based concentrations. Risk assessment was performed in
regional groundwater using both investigation results and modeling results and the exposure
factors presented hi EPA Region 3 RBCs. The EPA Region 3 RBCs are conservative criteria that
consider mgestion of groundwater under a residential scenario. Following are the sites that were
evaluated in the risk assessment process and presented no unacceptable risk.
• Fire Training Areas 6, 7B, and 7C (FT-06, FT-07B, FT-07C)
• Solid Waste Disposal Area (LF-23)
• Perimeter Road (OT-10)
• Wash Water Accumulation Basin (SS-28)
• DRMO Storage Area (SS-30)
• Former Underground Storage Tanks at POL Yard (ST-13)
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• BX Service Station (ST-31)
• MX Service Station (ST-32)
• Fuel Hydrant No. 9 (ST-34)
• Entomology Shop Yard (SD-12)
• MWR Auto Hobby Shop/Munitions Trailer Maintenance Shop (SD-24)
• Flight Line Storm Drain (SD-25)
• Vehicle Wash Rack (SD-27)
• Drum Accumulation Pad (SS-29)
• Munitions Disposal Area (OT-16)
• Lagoon Landfill (LF-01)
Perched Groundwater - ST-11
One site, Flight Line Fuel Spill Site ST-11, showed a risk to hypothetical future residents if the
perched water zone was ever utilized for a potable water source. The excess cancer risk
calculated for this scenario is one in 100. However, modeling does not indicate a risk to regional
groundwater which is used as drinking .water because the levels of contaminants in perched
groundwater would not contribute contaminants at levels exceeding MCLs.
Lagoon Landfill LF-01
The Lagoon Landfill (LF-01) showed cancer risks of 2 x 10"4, for hypothetical future residential
exposures to sediments in the sewage lagoon (if it were drained and used for residential purposes
in the future). However residential development at this site is unlikely. Therefore, the risks due
to residential exposures are likely overestimated. No unacceptable risks were calculated for
occupational exposures; therefore, no unacceptable risks are expected for likely exposures at these
sites.
The risk assessment conducted as part of the Remedial Investigations for OU1, OU3, and OU6
(risk assessment was not conducted at OU5 because all contaminated material was removed)
concluded that contaminants are not present in environmental media (soil, surface water, air, or
groundwater) at MHAFB at current points of exposure at concentrations that could pose a
significant human health risk or environmental risk under present future site use. In addition,
evaluation of the groundwater pathway concluded that contaminants will not be transported to
regional groundwater in the future at concentrations that could pose a significant health risk.
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B. ENVIRONMENTAL RISKS
The Basewide Ecological Risk Assessment (ERA) was done to assess the actual or potential
adverse impacts on plant and animal species from chemicals released to the environment at the
sites investigated through the CERCLA process. As part of the Basewide ERA, ecological
receptors were identified on a Basewide basis. The presence or absence of transport mechanisms
for contaminants from individual sites to ecological receptors was determined. The presence of
critical habitat, federal- or state-protected species, or other species of special concern was assessed
(no critical habitat was identified), and the potential for adverse ecological impacts to any of
these species by contaminants at the sites was estimated. Sources of contaminants and combina-
tions of sources of contaminants with the greatest relative potential for adverse ecological impacts
were identified. Ecological receptors at the greatest potential risk due to exposure to multiple
sources were evaluated.
Potential toxic effects on individuals of key species were considered as the first step in estimating
potential population effects. Potential effects on the population considered the abundance or
rarity and sensitivity of the key receptors and the potential for alternate habitat for the species.
The loss of one individual of a rare threatened and endangered species could be significant.
However, none of the key receptor species at the Base are rare in a regional context. Similarly,
the habitat suitable for wildlife at the Base is not unique or rare in a regional context, although
the aquatic and wetland habitats present at the Wastewater Lagoons and Flight Line Storm Drain
are uncommon in the region. For that reason, most of the key receptors (individuals) inhabiting
or frequenting the Base will also be found in similar areas beyond the Base boundaries, reducing
the potential for impacts at the population level.
No populations of any identified plant or animal species are at risk, although sensitive individual
plants could be at risk at one site (SD-25, Flight Line Storm Drain, OU6), and individual animals
could be at risk at one site (LF-01, Wastewater Lagoons, OU2). In addition, a few chemicals
slightly exceeded the conservative chemical benchmarks at several of the sites. However, as
discussed in the MHAFB OU3 Ecological Risk Assessment, because of the very conservative
nature of the chemical benchmarks and because of other very conservative assumptions used in
the ecological risk assessment, no measurable adverse ecological effects are expected to animal
or plant populations.
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C. SUMMARY OF SITE RISK CONCLUSION
In conclusion, based on the results from the field investigation and the risk assessment, remedial
action is not necessary for the protection of human health and the environment for the soil or the
regional groundwater at all the sites except for the perched water at the Flight Line Fuel Spill site
(ST-11).
D. REMEDIAL GOALS FOR SITE ST-11
The No Remedial Action alternative is proposed for both the soil and the regional groundwater
at all the sites except for the Flight Line Fuel Spill Site, ST-11.
Remedial action was deemed necessary for Site ST-11 to prevent human and environmental
exposure to the contaminated perched water, and to address the uncertainties with the future land
use. The Remedial Action Objectives (RAOs) for Site ST-11 are:
• The protection of human health by preventing human exposure to the perched
water
• The protection of the environment by preventing an inadvertent release through
either accidental penetration of the contaminated zone or extraction and release of
contaminated groundwater to the environment
VII. DESCRIPTION OF ALTERNATIVES
The alternatives analyzed for the Flight Line Fuel Spill Site (ST-11) are presented below. The
alternatives are listed in the order they are presented in the Remedial Investigation/Feasibility
Study report.
Alternative 1: No Remedial Action (included as a baseline for comparison)
The No Remedial Action alternative would require nothing be done to the site now and is
considered as a baseline for comparison in accordance with the National Contingency Plan. With
this alternative, contamination will be left in place, and a 5-year review of the site would be
necessary.
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Alternative 2: Limited Action
The components of this alternative are:
• Access control - Currently, the USAF closely restricts access owing to the fact that
most of the area is in a restricted area of MHAFB (guards monitor the area
24 hours a day).
• Notice of Restriction, which will identify the perched zone and prohibit drilling
of the perched zone or use of the perched water as drinking water on the MHAFB
Comprehensive Plan. The Plan will be registered on land plat maps held by
MHAFB. The land is held by lease by the Air Force and can not go back to the
land holder (Bureau of Land Management) until contamination is below MCLs.
• Leak detection program, which will ensure early detection of any future petroleum
leaks at the site. The program includes petroleum inventory and annual flight line
leak detection programs.
• Sampling of the perched groundwater prior to removal of the land use restriction
to ensure that perched water meets the standards of the Safe Drinking Water Act.
• Monitoring of the perched groundwater quality in accordance with the approved
groundwater monitoring plan.
With this alternative, contamination will be left in place, and a 5-year review of the site would
be necessary.
Alternative 3: Remedial Action by Pump and Treat (would entail installation of a
pump-and-treat system to remove contaminated perched water and treat it to remove
contaminants).
The Pump and Treat alternative would actively extract contaminated groundwater using a series
of closely spaced extraction wells. Water delivered from the extraction system would be passed
through an air stripper for volatile organic compound removal with a catalytic ozonator added
to treat the volatile air emissions from the air stripping process.
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Evaluation of Alternatives
The NCP (at 40 CFR 300.430[e][9][iii]) lists nine criteria to be considered in the evaluation and
comparison of remedial action alternatives. The first two criteria are considered "threshold"
criteria. If an alternative does not meet these threshold criteria, it cannot be selected. The
USAF, USEPA, and IDHW used these criteria as a basis for the evaluation of the alternatives.
Based on the evaluation, the preferred remedial alternative for the perched water at Site ST-11
is the Limited Action alternative. A discussion of the criteria follows:
Criterion 1 - Overall Protection of Human Health and the Environment
This criterion addresses whether a remedy provides adequate protection and how risks posed
through each pathway are eliminated, reduced, or controlled through treatment, engineering
controls, or institutional controls.
Limited Action and Pump and Treat are considered protective of human health and the
environment. The No Remedial Action alternative is only considered protective if the current
land use does not change and the perched water is not used for drinking water. The Pump and
Treat alternative is considered most protective because contaminants would be permanently
removed from the perched groundwater to levels that pose no health risk.
The Limited Action alternative is also considered protective because currently there are no users
of the perched groundwater, and the filing of a Notice of Restriction at the site will prevent any
future human and environmental exposure to the contaminated perched water. Furthermore, the
Limited Action alternative will require an evaluation of the perched zone to ensure that the
perched water meets applicable drinking water standards before it can be used as a drinking water
source. This would be done by installing a monitoring well and collecting perched water
sample(s) to be analyzed for fuel-related contamination.
Criterion 2 - Compliance with Federal and State Environmental Standards
This criterion addresses whether a remedy will meet all of the applicable or relevant and
appropriate requirements (ARARs) of Federal and State environmental regulations. ARARs
considered here include provisions of the Federal Safe Drinking Water Act enacted as Public Law
92520\A\520AOU3.ROD /dal/cee 9/25/95
MHAFB - Record of Decision for OUs 1,3, 5, and 6 -66- Rev. 2
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93-523, December 16, 1974, and the Idaho Administrative Procedure Act (IDAPA), Section 16,
Title 02, Water Quality Standards and Wastewater Treatment Requirements, July 1993.
The No Remedial Action alternative would not meet this criterion because inadvertent exposure
to hazardous levels of contaminants could occur if the perched water were considered as a
drinking water source. The Limited Action and Pump and Treat alternatives are considered to
be compliant with the pertinent environmental regulations. The Limited Action, although without
active treatment will meet the ARARs within a reasonable time frame. The Limited Action
alternative meets this criterion because it considers the perched groundwater as a water of the
State of Idaho and, as such, addresses the State's concerns should this water ever be used for
domestic supply. Furthermore, the Limited Action alternative will also ensure that ARARs are
met prior to the removal of the Notice of Restriction. The Pump and Treat alternative would
meet the criterion more quickly and effectively because contaminant concentrations in the perched
water would be quickly and permanently reduced to acceptable levels.
Criterion 3 - Long-Term Effectiveness and Permanence
This criterion addresses the magnitude of residual risk and the ability of a remedy to maintain
reliable protection of human health and the environment over time.
The No Remedial Action alternative does not meet this criterion because no action would be
taken, contaminants would be left in place, and inadvertent exposure to these contaminants could
occur. Since the source for the release in the pipeline has been addressed and a leak detection
program is performed annually along the pipeline, both the Limited Action and the Pump and
Treat alternatives meet this criterion. The Limited Action alternative would prevent inadvertent
human and environmental exposures to the perched water. However, the Pump and Treat
alternative would meet this criterion sooner and more effectively because it would actively reduce
the concentration of contaminants to below federally regulated Maximum Contaminant Levels
(MCLs).
Criterion 4 - Reduction of Toxicity, Mobility, or Volume through Treatment
This criterion addresses the degree to which a remedy reduces toxicity, mobility, and volume of
the hazardous substances or impacted media.
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The No Remedial Action and Limited Action alternatives do not actively reduce the level of
contaminants through treatment at Site ST-11. However, no reductions are needed immediately
because site access and use are restricted.
Mobility is not reduced for the No Remedial Action alternative because inadvertent release of the
contaminants could occur if the land use changes. The Notice of Restriction filed for the Limited
Action alternative will prevent inadvertent release of Site ST-11 contaminants by specifically
preventing any subsurface intrusion (i.e., drilling) through the confining layer under the perched
water. The Pump and Treat alternative is the only alternative that would meet this criterion by
permanently reducing the toxicity, mobility, and volume of hazardous constituents in the perched
system by treatment.
Criterion 5 - Short-Term Effectiveness
This criterion addresses the period of time needed to achieve protection of human health and the
environment, and any adverse impacts that may be posed during the construction and
implementation period.
Since ST-11 is in a restricted area of MHAFB, and no receptor is associated with the current
industrial land use, all three alternatives would be effective for short term. The No Remedial
Action and Limited Action alternatives do not currently require any implementation, while the
Pump and Treat alternative would require one year to implement. Standard protective
construction procedures would be followed during the implementation of the Pump and Treat
alternative.
Criterion 6 - Implementability
This criterion addresses the technical and administrative feasibility of a remedy, including the
availability of materials and services needed to implement the alternative.
The Limited Action and No Remedial Action alternatives are easily implementable. Virtually no
effort would be required to carry out the No Remedial Action alternative. Minimal effort would
be expended to file a Notice of Restriction for land use under the Limited Action alternative, and
site access restrictions due to MHAFB security are already in place. Also, should land use
change in the future to residential, installation of a monitoring well and collection of a water
92520\A\520AOU3.ROD /dal/cee 9/25/95
MHAFB - Record of Decision for OUs 1,3, 5, and 6 -68- Rev. 2
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sample for water quality analysis would require little effort. The Pump and Treat alternative
could be implemented with much more difficulty because of the use of the site as an active
aircraft parking apron and taxiway.
Criterion 7 - Costs
This criterion addresses the estimated capital (direct and indirect) and operation and maintenance
costs associated with the alternative. In comparison to the other alternative, these costs are
summarized in Table 4la.
No cost is required to implement the No Remedial Action alternative at this site. The cost for
the Limited Action alternative is relatively small as it requires the proper public notification in
certain offices at MHAFB, the installation of a monitoring well, and the collection of perched
water samples to demonstrate the effectiveness of natural attenuation of fuel-related contaminants.
The cost to administer the Notice of Restriction, including changes to appropriate documents
(Base Comprehensive Plan), is estimated at $5,050. The estimated cost to install a perched zone
well is $14,000, and the estimated cost to abandon the well (assuming a present cost of $1,500,
an inflation rate of 5 percent per year, and a monitoring period of five years) is $1,823. The
estimated total capital costs are $20,873. Assuming that perched zone monitoring will occur once
per year for a period of five years, and assuming a present cost of $2,175 for sampling and
reporting (again with 5 percent inflation) total operations and maintenance is estimated at
$12,018. The total cost for this alternative is estimated to be $32,891. The actual cost will
depend on the frequency and duration of sampling. These will be described in a Groundwater
Sampling Plan. Table 41 b shows the detailed cost estimates for Limited Action at ST-11 in
addition to the alternative cost analysis.
The capital costs to implement the Pump and Treat alternative are relatively high. The cost for
system installation would be about $1,355,789. The present-worth operation and maintenance
costs associated with the system for a 1-year life is $48,981, and the total present worth cost
using a 5 percent rate over 1 year is $1,404,770.
92520\A\520AOU3.ROD /dal/cec 9/25/95
MHAFB - Record of Decision for OUs 1.3,5, and 6 -69- Rev. 2
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TABLE 41a
ALTERNATIVE COST ANALYSIS FOR SITE ST-11
Alternative I
No Action
Alternative II
Limited Action
Alternative III
Pump & Treatment
Capital Costs
Operation and Maintenance
Present Worth
$0
$0
$0
$20,873
$12,018
$32,891
$1,355,789
$48,981
$1,404,770
92S2Q\A\520AOU3.t4l/cee
HAFB - Record of Decision Tor OU» 1, 3. 5, and 6
09/26/95
:ev. 2
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TABLE 41b
DETAILED COST ANALYSIS FOR LIMITED ACTION AT SITE ST-11
Costs
(i)
(2)
(3)
W
Notice
Well Installation
Well
Abandonment01
Analytical
Field Labor<2>
Materials
Report'3'
Total'4'
Year 1
$5,050
$14,000
$275
$800
$100
$1,000
$21,225
Year 2
$289
$840
$105
$1,050
$2,284
Year3
$303
. $882
$110
$1,103
$2,398
Year 4
$318
$926
$116
$1,158
$2,518
YearS
$1,823
$334
$972
$122
$1,216
$4,467
Well abandonment was estimated based on a present cost of $1,500 and 5 percent per year inflation.
Field labor costs were estimated by assuming 10 hours labor per event for each of 2 individuals at $40 per hour per individual.
Reporting costs were estimated at 10 hours of labor for 1 individual at $50 per hour plus $500 per event for word processing, duplicating,
An inflation rate of 5 percent per year was assumed.
Total
$32,891
clerical, and materials.
92S20\A\52QAOU3.t4l/cec
MIIAI'B • Record of Ocelilon for OU» I, 3, 5, and 6
09/26/95
Rev. 2
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Criterion 8 - State Acceptance
The State of Idaho concurs with the selected remedy.
Criterion 9 - Community Acceptance
This criterion addresses whether community concerns are addressed by the preferred remedy and
whether the community has a preference for a remedy.
The community has been made aware of the Proposed Plan through public meetings and an open
public comment period. This is described in Section III of the ROD. One individual from the
public attended the public meeting. No oral or written comments regarding the Proposed Plan
were received.
Vm. THE SELECTED REMEDY
USAF, EPA, and IDHW have determined that no remedial action is necessary under CERCLA
at 32 of the 33 sites investigated. The selected remedy at ST-11 meets the Remedial Action
Objectives, and will ensure protection of human health and the environment.
The selected remedy for Site ST-11 is the Limited Action alternative. This alternative prevents
inadvertent human and environmental exposures to the contaminated perched water and meets all
applicable, relevant, and appropriate requirements (ARARs) within a reasonable time frame. This
alternative is more cost effective than the Pump and Treat alternative. Furthermore, it is also
more implementable.
The Limited Action consisting of the following components:
• Notice of Restriction, which will identify the perched zone and prohibit drilling
of the perched zone or use of the perched water as drinking water on the MHAFB
Comprehensive Plan. The Plan will be registered on land plat maps held by
MHAFB. The land is held by lease by the Air Force and can not go back to the
land holder (Bureau of Land Management) until contamination is below MCLs.
92520\A\520AOU3.ROD /dal/cee 9/25/95
MHAFB - Record of Decision for OUs 1,3,5. and 6 -72- Rev. 2
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• Leak detection program, which will ensure early detection of any future petroleum
leaks at the site. The program includes petroleum inventory and annual flight line
leak detection programs.
• Sampling of the perched groundwater prior to removal of the land use restriction
to ensure that perched water meets the standards of the Safe Drinking Water Act.
• Monitoring of the perched groundwater quality in accordance with the approved
groundwater monitoring plan.
This action is necessary because of the risk identified from the contaminated perched water if the
perched water zone were considered as a source of drinking water. This action will meet the
remedial action objectives within the reasonable time frame for this site by ensuring:
• The protection of human health by preventing human exposure to the perched
water
• The protection of the environment by preventing an inadvertent release through
either accidental penetration of the contaminated zone or extraction and release of
contaminated perched groundwater to the environment
Because contaminants will be left in place, this alternative would include the statutory 5-year
review requirements to ensure that the selected remedy is still protective of human health and the
environment.
The no action for 32 of the 33 sites addressed in this ROD includes long-term monitoring of the
regional Snake River Plains aquifer at MHAFB. The purpose of the long-term monitoring of the
regional groundwater is to address uncertainties associated with the fate and transport modeling.
The planned monitoring will be done at least annually for a minimum of five years collecting
samples at specific wells for laboratory analysis of selected VOCs and selected metals in
accordance with the monitoring plan. Based on the assumption that eight wells will be sampled
annually for five years, the present worth estimated cost of this annual sampling for five years
considering a 5% interest rate is $47,520. This costs includes laboratory analysis, sample
collection, data validation, and a summary report. Table 42 shows the costs estimated for no-
92520\A\520AOU3.ROD /dal/cee 9/25/95
MHAFB - Record of Decision for OUs 1, 3, 5, and 6 -73- Rev. 2
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TABLE 42
COST ANALYSIS FOR REGIONAL GROUNDWATER MONITORING
Year 1
Year 2
Year 3
Year 4
YearS
Total
Costs
to
(2)
(3)
Analytical'"
Field Labor12'
Materials'3'
Report'4'
Total'3'
Analytical costs
Field labor costs
PvnpnrlaKI^ ^niii
$4,000
$1,600
$500
$2,500
$8,600
assume 8 wells sampled annually
assume a total of 20 hours labor
nmpnt u/nc pctimntivl at H^ftft npr
$4,200
$1,680
$525
$2,625
$9,030
at a cost of $500 per well.
per event for each of 2 individuals
PVC!Tlt
$4,410
$1,764
$551
$2,756
$9,482
at $40 per
$4,631
$1,852
$579
$2,894
$9,956
hour per individual.
$4,862
$1,945
$608
$3,039
$10,453
$47,520
(5)
Reporting costs were estimated at 40 hours of labor for one individual at $50 per hour plus $500 per event for word processing, duplicating, clerical, and materials.
An annual inflation rate of 5 percent per year was assumed.
92520\A\520AOU3.ROD /dal/cee
MHAFB - Record of Decision for OUs 1, 3, 5, and 6
09/26/95
Rev. 2
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action monitoring of regional groundwater assuming that each of 8 existing wells will be sampled
annually for a period of 5 years.
Results of the monitoring will be used to evaluate analyte-specific trends to determine whether
further monitoring or other action is necessary to ensure protection of human health and the
environment.
IX. STATUTORY DETERMINATION
Based on the results of the Baseline Risk Assessment and other information available in the
administrative record, no action is necessary for soil or groundwater to ensure protection of
human health and the environment.
The selected remedy at ST-11 is protective of human health and the environment, and will
comply with federal and state requirements that are applicable or relevant and appropriate within
a reasonable time frame. ARARs considered here include provisions of the Federal Safe Drinking
Water Act enacted as Public Law 93-523, December 16, 1974, and the Idaho Administrative
Procedure Act (IDAPA), Section 16, Title 02, Water Quality Standards and Wastewater
Treatment Requirements, July 1993. It is also cost effective. The remedy at Site ST-11 does not
satisfy the statutory preference for treatment as a principal element of the remedy. However, the
restriction placed at the site prevents exposure to humans and protects the environment by
preventing an inadvertent release or excursion of the contaminated groundwater and requires that
MCLs be met prior to lifting this restriction. Sampling will be conducted to ensure that the
perched groundwater meets drinking water quality prior to removal of the land restriction.
Because this remedy will result in hazardous substances remaining on site above health-based
levels, a review will be conducted within five years after commencement of remedial action to
ensure that the remedy continues to provide adequate protection of human health and the
environment.
X. DOCUMENTATION OF SIGND7ICANT CHANGES
No significant changes have been made to the Remedial Investigation Report or to the selected
remedy as proposed in the proposed plan that was released for public comment on June 19th,
1995. Perched groundwater at ST-11 will be monitored in accordance with the groundwater
92520\A\520AOU3.ROD /dal/cee 9/25/95
MHAFB - Record of Decision for OUs 1,3, 5, and 6 -75- Rev. 2
-------
monitoring plan. Costs associated with perched groundwater monitoring were not estimated hi
the Proposed Plan. For this reason, the estimated costs for Limited Action at ST-11 is $27,841
greater than the $5,050 that was estimated for the Notice of Restriction described in the Proposed
Plan.
92520\A\520AOU3.ROD /dal/cee 9/25/95
MHAFB - Record of Decision for OUs 1,3, 5, and 6 -76- Rev. 2
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APPENDIX A
TABLES 1-31, 38 & 39
92520\A\520AOU3.ROD /cee/dal 9/14/95
MHAFB - Record of Decision for OUs 1, 3, S, and 6 Rev. 2
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TABLE 1
SUMMARY OF CHEMICALS DETECTED IN SURFACE WATER SAMPLES
AT THE NORTH CELL, WASTEWATER LAGOONS
Locator/Sample Round/Sample No. NLC-001-001 NLC-001-002 NLC-001-003 NLC-002
Result RL Qual Result RL Qual Result RL Qual Result RL
Qual
NLC-003
Result RL Qual
Semi volatile Organics (ug/L)
Phenol 3 10 J < 10 U < 10 U
Di-n-butylphthalate 1 10 J 1 10 J < 10 U
4-Methylphenol 6 10 J < 10 U < 10 U
bis(2-Ethylhexyl)phthalate 1 10 J < 10 U < 10 U
Water Quality (mg/L)
Alkalinity, Total as CaCO3 at pH 4.5
Alkalinity, Bicarb, as CaCOS at pH 4.5
Alkalinity, Carb. as CaCO3 at pH 8.3
Chloride
Fluoride
Nitrate plus Nitrite as N
Orthophosphate as P
Sulfate
Total Dissolved Solids
195
195
<
24.8
1.5
2
4.9
21.7
691
5
5
5
3
0.1
0.1
1
5
10
U
J
J
J
198
155
43
66.4
0.5
<
6.1
117
562
5
5
5
3
0.1
0.1 U
0.5
5
10
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2TOI.XLS]TABLE16/-/jdg
MIIAPU - Record of Decision forOUs 1,3,5, and 6
9/14/95
Rev. 0
-------
TABLE 2
SUMMARY OF CHEMICALS DETECTED IN SURFACE WATER SAMPLES
AT THE EAST CELL, WASTEWATER LAGOONS
Locator/Sample Round/Sample No.ELC-001-004 ELC-002 ELC-003
Result RL Qual Result RL Qual Result RL Qual
Semivolatile Organics (fig/L)
1,2-Dichlorobenzene 1
Naphthalene 1 1
Water Quality (mg/L)
Alkalinity, Total as CaCO3 at pH 4.5
Alkalinity, Bicarb, as CaCOS at pH 4.5
Chloride
Fluoride
Orthophosphate as P
Sulfate
Total Dissolved Solids
10 J
10 J
199
199
69.9
0.24
4.6
117
628
5
5
3
0.1
0.5
5
10
J
J .
J
204
204
55
0.48
3.2
96.3
486
5
5
3
0.1
0.25
5
10
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2TOI .XLSJTABLE 2 /dal/jdg 9/14/95
Ml 1AF13 -Record of Decision for OUs 1,3, S, and 6 Rev. 0
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TABLE 3
SUMMARY OF CHEMICALS DETECTED IN SURFACE WATER SAMPLES
AT THE WEST CELL, WASTEWATER LAGOONS
Locator/Sample Round/Sample No. WLC-001-006 WLC-002 WLC-003
Result RL Qual Result RL Qual Result RL Qua!
Volatile Organics (ug/L)
Benzene 0.11 0.4 J
Water Quality (mg/L)
Alkalinity, Total as CaCO3 at pH 4.5
Alkalinity, Bicarb, as CaC03 at pH 4.5
Chloride
Fluoride
Orthophosphate as P
Sulfate
Total Dissolved Solids
210
210
89.7
<
2.2
126
776
5
5
3
0.1
0.5
5
10
J
UJ
J
216
216
66.7
0.39
2.6
111
557
5
5
3
0.1
0.25
5
10
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2TOI.XLS]TABLE 16/-/jdg 9/14/95
Ml IA1-U - Record of Decision for OUs 1,3,5, and 6 Rev. 0
-------
TABLE 4
SUMMARY OF CHEMICALS DETECTED IN SURFACE WATER SAMPLES
AT THE SOUTH CELL, WASTEWATER LAGOONS
Locator/Sample Round/Sample No. SLC-001-001 SLC-001-007 SLC-001-009 SLC-002 SLC-003
Result RL Qua! Result RL Qual Result RL Qual Result RL Qual Result RL Qual
Semivolatile Organics(|ig/L)
bis(2-Ethylhexyl)phthalate 57 9 < 9 U
Water Quality (mg/L)
Alkalinity, Total as CaCO3 at pH 4.5 180 5 244 5
Alkalinity, Bicarb, as CaCO3 at pH 4.5 163 5 244 5
Alkalinity, Carb. as CaC03 at pH 8.3 17.3 5 < 5 U
Chloride 96.9 3 J 87.2 3
Fluoride < 0.1 UJ 0.18 0.1
Nitrate plus Nitrite as N • < 0.1 U 0.14 0.1
Orthophosphate as P 4.4 0.5 0.59 0.05
Sulfate 120 5 J 140 5
Total Dissolved Solids 673 10 653 10
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual =• Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2T01.XLS]TABLE 4 /dal/jdg
MIIAW • Record of Decision forOUs 1.3.5, and 6
9/14/95
Rev. 0
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TABLE 4A
MAXIMUM SEDIMENT CONCENTRATIONS
FOR LAGOON LANDFILL (LF-01)
AND FLIGHTLINE STORM DRAIN (SD-25)
Methylene Chloride
Acetone
Carbon Disulfide
2-Butanone
Tetrachloroethene
Toluene
Ethylbenzene
Xylenes (total)
Total Petroleum Hydrocarbons
1,2-Dichloroethene (total)
1,1,1-Trichloroethane
Chlorobenzene
Trichloroethene
LF-01
2 J
170
7 J
32 J
1 J
26 J
2 J
16 J
5,210
SD-25
5 J
71 J
33 J
2 J
12 J
400 J
2,500
470 J
19 J
890 J
3.6 J
J = Estimated value below sample reporting limit or estimated based on quality control
criteria
U = Not detected
UJ = Estimated nondetect
Note: Total Petroleum Hydrocarbons refers to analyses by EPA Method 418.1 for
Total Petroleum Hydrocarbons
92520\A\[RD2TO 1 .XLSJTABLE 4A/cee 9/25/95
MHAFB - Record of Decision for Oils 1,3, 5, and 6 Rev. 2
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TABLES
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT MW-1
Locator/Sample Round
Semivolatile Organics (fig/L)
bis(2-Ethylhexyl) phthalate
Di-n-octylphthalate
OU3-MW1-RGW-002
Result RL Qua!
OU3-MW1-RGW-003
Result RL Qual
OU3-MW1-RGW-004
Result RL Qual
10
10
u
u
10
10
u
u
Metals (fig/L)
Aluminum
Arsenic
Barium
Calcium
Cobalt
Iron
Lead
Magnesium
Manganese
Potassium
Sodium
Vanadium
2090
5
152
140000
6
5080
3.9
45000
324
8340
91000
18.2
Water Quality (rag/L)
Alkalinity, Total as CaCO3 at pH 4.5
Alkalinity, Bicarb, as CaCO3 at pH 4.5
Chloride
Fluoride
Nitrate plus Nitrite as N
Orthophosphate as P
Sulfate
Total Dissolved Solids
411
411
80.3
0.17
7.3
<
78.4
698
5
5
3
0.1
0.5
0.05 U
5
10
330
330
79.6
<
7.5
0.055
77.7
702
5
5
3
0.1
0.5
0.1
5
10
J
UJ
J
365
365
79.4
0.24
8
0.072
75.7
664
5
5
3
0.1
0.5
0.05
5
10
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R=Rejected value.
U = Nondetected value.
92520\A\[RD2T01.XLS]TABLE 5/-/jdg
MHAFB - Record of Decision for OUs 1,3,5, and 6
9/14/95
Rev. 1
-------
TABLE 6
SUMMARY OF CHEMICALS DETECTED IN GROUND WATER SAMPLES AT MW-2
Locator/Sample Round
Metals (ug/L)
Aluminum
- Arsenic
Barium
Calcium
Chromium
Copper
Iron
Lead
Magnesium
Manganese
Nickel
Potassium
Sodium
Vanadium
Zinc
Water Quality (mg/L)
Alkalinity, Total as CaC03 at pH 4.5
Alkalinity, Bicarb, as CaCO3 at pH 4.
Chloride
Fluoride
Nitrate plus Nitrite as N
Orthophosphate as P
Sulfate
Total Dissolved Solids
LF02-MW02-RGW-00 1 OU3-MW2-RGW-002
Result RL Qual Result RL Qual
3820
1.1
28.5
20300
10.5
7.8
5630
1.8
7070
144
11.3
3450
12400
19.3
19.6
66
66
3.9
0.14
1.2
0.14
8.5
125
5700
<
28.9
21000
22.3
J <
6580
J - 7.6
7460
142
<
3550
12700
21.1
25.3
63.2
63.2
4
0.13
0.86
J <
9
130
1 U
U
12.5 U
U
15.3 U
U
5
5
3
0.1
0.1
0.05 U
5
10
MW2-RGW-003
Result RL Qual
623 J
< 1 U
< 15.8 U
16200
< 8 U
< 4.8 U
4820 J
3.9 U
6960 J
123
< 8 U
2840
10100
18.2
< 16.4 U
OU3-MW2-RGW-004
Result RL Qual
3040
< 1
< 21.1
16500
10.9
< 5
4220
5.3
6380
94.6
< 13.3
< 2820
10800
< 19.7
< 17.8
U
U
U
J
U
UJ
UJ
U
U
U
U
U
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2TOI.XLS]TABLE16/-/jdg
MIIAPU - Record of Decision forOUs 1,3,5, and 6
9/14/95
Rev. 0
-------
TABLE?
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT MW-3
Locator/Sample Round
LF02-MW03-RGW-001
Result RL Qual
OU3-MW3-RGW-002
Result RL Qual
Metals (ug/L)
Aluminum
Barium
Calcium
Iron
Magnesium
Manganese
Potassium
Sodium
Vanadium
Zinc
Water Quality (mg/L)
Alkalinity, Total as CaC03 at pH 4.5
Alkalinity, Bicarb, as CaC03 at pH 4
Chloride
Fluoride
Nitrate plus Nitrite as N
Orthophosphate as P
Sulfate
Total Dissolved Solids
Total Petroleum Hydrocarbons (mg/L)
TPH
48.6
6.1
14600
274
4810
11.6
3390
11400
14.2
< 7.2 ' U
64.5
64.5
3.2
0.15
1.1
< 0.05 UJ
7
119
29.6 J
<
8.1
14500
974
4800
<
3130
10900
12.5
8.1
63.2
63.2
3.5
0.14
0.85
7.9
122
<
68.8 U
17.8 U
5
5
3
0.1
0.1
5
10
1 U
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual •= Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2T01.XLS]TABLE 7/-/jdg
Ml IAFI) • Record of Decision for OUs 1,3,5, and 6
9/14/95
Rev. 0
-------
TABLE 8
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT MW-4
Locator/Sample Round LF02-MW04-RGW-001 OU3-MW4-RGW-002
Result RL Qual Result RL Qual
Metals (fig/L)
Aluminum
Barium
Calcium
Iron
Lead
Magnesium
Manganese
Potassium
Sodium
Vanadium
Water Quality (mg/L)
Alkalinity, Total as CaCO3 at pH 4.5
Alkalinity, Bicarb, as CaCO3 at pH 4.5
Chloride
Fluoride
Nitrate plus Nitrite as N
Orthophosphate as P
Sulfate
Total Dissolved Solids
Total Petroleum Hydrocarbons (mg/L)
TPH
76.9
7.4
13200
350
3.8 J
4290
15.9
3270
13000
17.8
61.1
61.1
3.5
0.18
1
0.068 J
7.9
113
10.1 J
102
8.2
13100
<
<
4240
<
3290
12400
15.4
57.6
57.6
3.3
0.15
0.89
7.9
125
<
210
1
10.3
5
5
3
0.1
0.1
5
10
1
U
u
U
u
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
} = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2TOI.XLS]TABLE 16/-/jdg 9/14/95
Ml lAl'U - Record of Decision for OUs 1,3,5, and 6 Rev. 0
-------
TABLE 9
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES FOR MW-5
Locator/Sample Round
Semivolatiles (ug/L)
bis(2-Ethylhexyl)phthalate
Metals (ng/L)
Aluminum
Barium
Calcium
Iron
Magnesium
Manganese
Potassium
Selenium
Sodium
Vanadium
Water Quality (mg/L) :
Alkalinity, Total as CaCO3 at pH 4.5
Alkalinity, Bicarb, as CaCO3 at pH 4.5
Chloride
Fluoride
Nitrate plus Nitrite as N
Orthophosphate as P
Sulfate
Total Dissolved Solids
Total Petroleum Hydrocarbons (mg/L)
TPH
LF02-MW05-RGW-001
Result RL Qual
120 J
30
7
13300
110
4270
23.1
3210
< 1 UJ
11700
14.5
61
61
3.6
0.16
0.9
0.22 J
8.5
116
3.9 J
OU3-MW5-RGW-002
Result RL Qual
<
<
5.7
13100
470
4400
<
3370
<
12000
12.5
60.1
60.1
3.5
0.14
0.84
0.16
8.3
130
<
10 U
30 U
13.4 U
2 UJ
5
5
3
0.1
0.1
0.05
5
10
1 U
OU3-MW5-RGW-003
Result RL Qual
< 10 U
< 46 UJ
< 4.5 U
12400
341
4030 J
< 14.8 U
2950
2.6 J
9680
15.4
OU3-MW5-RGW-004
Result RL Qual
< 11 U
< 36 U
< 5.6 U
11700 J
193 U
< 4040 U
< 5.5 U
< 2640 U
< 2 UJ
10100
< 17.2 U
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2T01 .XLS]TABLE 9/jdg
MHAFB - Record of Decision for OUs 1,3,5, and 6
9/14/95
Rev. 0
-------
TABLE 10
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT MW-6
Locator/Sample Round
Semivolatile Organ ics (ug/L)
bis(2-Ethylhexyl) phthalate
Metals (ug/L)
Barium
Calcium
Iron
Magnesium
Manganese
Potassium
Sodium
Vanadium
Water Quality (mg/L)
Alkalinity, Total as CaC03 at pH 4.5
Alkalinity, Bicarb, as CaC03 at pH 4.5
Chloride
Fluoride
Nitrate plus Nitrite as N
Orthophsphate as P
Sulfate
Total Dissolved Solids
Total Petroleum Hydrocarbons (mg/L)
TPH
LF01-MW06-RGW-001
Result RL Qual
< 10 UJ
6.6
23400
578
7720
13.9
4100
15900
14.3
64
64
11.1
0.15
3.7
0.064 J
28
173
20.8 J
OU3-MW6-RGW-002 OU3-MW6-RGW-003
Result RL Qual Resul RL Qual
4
23
6.5
19200
<
<
6450
3750
13900
63.5
63.5
8.1
0.14
2.2
<
19.1
169
<
J < 10 UJ
344 U
11.5 U
5 59.1 5
5 59.1 5
3 7.1 3 J
0.1 0.13 0.1 J
0.1 2.1 0.1
0.05 U < 0.05 U
5 18.5 5 J
10 154 10 J
1 U
OU3-MW6-RGW-004
Result RL Qual
< 10 U
64.1 5
64.1 5
7.8 3
0.21 0.1
1.9 0.1
< 0.05 U
17.6 5
152 10
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2TOI.XLS]TABLE16/-/jdg
MIIAFD • Record or Decision forOUs 1,3,5, and 6
9/14/95
Rev.O
-------
TABLE 11
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT MW-7
Locator/Sample Round
Volatile Organics (fig/L)
Trichloroethene
Metals (ftg/L)
Arsenic
Barium
Calcium
Iron
Magnesium
Manganese
Potassium
Sodium
Vanadium
Water Quality (mg/L)
Alkalinity, Total as CaCO3 at pH 4.5
Alkalinity, Bicarb, as CaCO3 at pH 4.
Chloride
Fluoride
Nitrate plus Nitrite as N
Orthophosphate as P
Sulfate
Total Dissolved Solids
Total Petroleum Hydrocarbons (mg/L)
TPH
LF01-MW07-RGW-001 OU3-MW7-RQW-002 OU3-MW7-RGW-003
Result RL Qual Result RL Qual Result RL Qual
0.2
1.1
24
55000
397
20500
12.3
6170
33000
7.2
180
180
36.8
0.2
6.9
0.12
35.8
340
13.6
J <
<
28.8
63000
<
24100
<
7080
37800
7.7
209
209
46.3
0.1
5.1
J <
31.8
402
J <
0.38 U 0.22 0.38 J
1 U
347 U
19 U
5 175 5
5 175 5
3 54.4 3 J
0.1 R
0.2 4.9 0.5
0.05 U < 0.05 U
5 53.4 5 J
10 380 10
1 U
OU3-MW7-RGW-004
Result RL Qual
< 0.35 U
168 5
168 5
32.5 3
0.17 0.1
3.8 0.2
< 0.05 U
27.9 5
320 10
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL == Reporting Limit
Qual = Qualifier
J •= Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\|RD2T01.XLS]TABLE 1 l/-/jdg
Ml IAI;13 • Record of Decision for OUs 1,3, 5, and 6
9/14/95
Rev. 0
-------
TABLE 12
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT MW-8
Locator/Sample Round
Volatile Organics (fig/L)
Benzene
Trichloroethene
Metals (fig/L)
Aluminum
Arsenic
Barium
Calcium
Chromium
Iron
Magnesium
Manganese
Potassium
Sodium
Vanadium
Water Quality (mg/L)
Alkalinity, Total as CaCO3 at pH 4.5
Alkalinity, Bicarb, as CaCO3 at pH 4.5
Chloride
Fluoride
Nitrate plus Nitrite as N
Sulfate
Total Dissolved Solids
Total Petroleum Hydrocarbons (mg/L)
TPH
LF01-MW08-RGW-001
Result RL Qual
< 0.4 U
< 0.38 U
< 28 U
1.4
13.2
55500
< 5 U
502
15900
25.6
6230
36300
6.8
170
170
37.6
0.23
4.7
35.4
333
24.7 J
OU3-MW8-RGW-002 OU3-MW8-RGW-003 OU3-MW8-RGW-004
Result RL Qual Result RL Qua! Result RL Qual
0.39
0.55
1430
1.5
19.5
56100
14.7
2020
15800
60.7
6020
33000
7.7
155
155
39.3
0.18
4.1
43.2
365
<
0.4 J < 0.4 U < 0.4 U
0.38 0.3 0.38 J < 0.35 U
5 106 5 189 5
5 106 5 189 5
3 22.7 3 J 42.7 3
0.1 0.12 0.1 J 0.21 0.1
0.2 3.6 0.2 3.7 0.2
5 31.6 5 J 35.6 5
10 268 10 J 368 10
1 U
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2TOI.XLS]TABLE16/-/jdg
MIIAFD • Record or Decision forOUs 1,3,5, and 6
9/14/95
Rev. 0
-------
TABLE 13
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT MW-9
Locator/Sample Round
LF01-MW09-RGW-001
Result RL Qual
OU3-MW9-RGW-002
Result RL Qual
Volatile Organics (ug/L)
Trichloroethene
Metals (fig/L)
Barium
Calcium
Magnesium
Potassium
Sodium
Vanadium
Zinc
Water Quality (mg/L)
Alkalinity, Total as CaC03 at pH 4.5
Alkalinity, Bicarb, as CaCO3 at pH 4.5
Chloride
Fluoride
Nitrate plus Nitrite as N
Orthophosphate as P
Sulfate
Total Dissolved Solids
1.3
31.8
8200
24900
7606
27400
9.9
454
98.4
98.4
60
< 0.1 U
14.4
0.4 J
143
474
1.2
28
70600
21800
6520
24700
11.1
237
91.8
91.8.
53.6
0.1
9.5
<
113
455
0.38
5
5
3
0.1
0.5
0.05 U
5
10
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2T01.XLS]TABLE 13/-/jdg
MHAFB - Record of Decision for OUs 1,3,5, and 6
9/14/95
Rev. 0
-------
TABLE 14
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT MW-11
Locator/Sample Round
08-MW11-RGW-001
Result RL Qual
OU3-MW11-RGW-002
Result RL Qual
OU3-MW11-RGW-003
Result RL Qua!
OU3-MW11-RGW-004
Result RL Qual
Volatile Organ ics (ug/L)
Trichldroethene
Metals (fig/L)
Aluminum
Barium
Calcium
Iron
Lead
Magnesium
Manganese
Potassium
Selenium
Sodium
Vanadium
Zinc
Water Quality (mg/L)
Alkalinity, Total as CaC03 at pH 4.5
Alkalinity, Bicarb, as CaCO3 at pH 4.5
Chloride
Nitrate plus Nitrite as N
Orthophosphate as P
Sulfate
Total Dissolved Solids
1.3
97.6
< 40.2 U
98600
140
2.2 J
29400
16.2
7650
1.5 J
29200
9.2
572
91.4
91.4
75.3
15.6
0.5 J
180
553
1.6
323
36.2
86800
<
<
26700
<
7160
<
26500
9.6
429
93.2
93.2
66
11.7
<
146
561
0.38
447 U
2 U
6.9 U
2 UJ
5
5
3
0.5
0.05 U
5
10
1.5 0.38 2.7 0.4
86.7 5
86.7 5
64.4 3 J
11.1 0.5
< 0.05 U
144 5 J
542 10
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2TOI.XLS]TABLE16/-/jdg
MIIAPU - Record of Decision forOUs 1,3,5, and 6
9/14/95
Rev. 0
-------
TABLE 15
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT PERCHED WELLS AT MW-12
LOCATOR
Metals (ng/L)
Aluminum
Barium
Beryllium
Calcium
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Nickel
Potassium
Sodium
Vanadium
Zinc
TPH (mg/L)
Total Petroleum Hydrocarbons
Water Quality (mg/L)
Alkalinity, Total as CaCO3 at pH 4.5
Alkalinity, Bicarb, as CaCO3 at pH 4.5
Chloride
Fluoride
Nitrate plus Nitrite as N
Orthophosphate as P
Sulfate
Total Dissolved Solids
LF01-MW12-PGW-001
Result RL Qual
112000
893
5.6
152000
147
57.6
118
132000
50.6
79700
2490
142
23800
74600
156
382
<
360
360
69.6
0.31
9.1
0.68
72.1
800
J
J
J
J
J
J
J
• J
J
J
J
J
J
J
1 UJ
J
LF01-MW12-PGW
Result RL
3940
126
< 1
81000
39.2
4.5
10
4800
1.8
32000
113
24.9
6550
67700
12.2
68.5
< 1
355
355
68.6
0.26
11.2
0.062
73.6
692
-001-conf.
Qual
J
U
J
J
J
J
J
J
J
J
J
J
J
J
UJ
J
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\|RD2T01.XLS]TABLEI5/-/jdg
MIIAl'U - Record of Decision forOUs 1,3,5, and 6
9/14/95
Rev. 0
-------
TABLE 16
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT PERCHED WELLS AT MW-15
Locator/Sample Round
Volatile Organ ics (jig/L)
Trichloroethene
Semivolatile Organics (ug/L)
bis(2-ethylhexyl)phthalate
Pesticides/PCB's (ug/L)
Hcptachlor epoxide
Metals (ug/L)
Aluminum
Barium
Beryllium
Calcium
Chromium
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Nickel
Potassium
Sodium
Vanadium
Zinc
TPH (mg/L)
Total Petroleum Hydrocarbons
Water Quality (mg/L)
Alkalinity, Total as CaC03 at pH 4.5
Alkalinity, Bicarb, as CaCO3 at pH 4.5
Chloride
LF01-MW15-PGW-001
Result RL Qual
< 0.38 U
< 10 U
< 0.048 U
78100
684
5.5
164000
330
39.3
86.4
105000
49.3
60200
1740
187
14500
35600
111
296
J
J
J
J
J
J
J
J
J
J
J
J
J
J
265
265
77.3
UJ
LF01-MW15-PGW-001-conf.
Result RL Qual
0.3
8.4
258
258
75.3
J
1
0.045
5700
96.6
< 1
96600
58.9
5.5
14.8
7810
2.3
35100
145
36.5
3930
32100
13.5
76.8
J
J
J
U
J
J
J
J
J
J
J
J
J
J
J
J
Sheet 1 of 2
9/14/95
Rev. 0
-------
TABLE 16
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT PERCHED WELLS AT MW-15
Locator/Sample Round LF01-MW15-PGW-001 LF01-MW15-PGW-001-conf.
Result RL Qual Result RL Qual
Water Quality (mg/L), cont.
Fluoride 0.48 0.23
Nitrate plus Nitrite as N 30 24.9
Orthophosphate as P 0.1 J 0.27 J
Sulfate 67.8 66
Total Dissolved Solids 672 614
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2TOl.XLS]TABLE 16/-/jdg 9/J4/95
Ml IAI-U - Record of Decision for OUs 1,3,5, and 6 Sheet 2 of 2 Rev. 0
-------
TABLE 17
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT MW-16
Locator/Sample Round
Volatile Organics (ug/L)
Methylene Chloride
Metals (fig/L)
Arsenic
Barium
Calcium
Iron
Magnesium
Manganese
Potassium
Selenium
Sodium
Vanadium
Water Quality (mg/L)
Alkalinity, Total as CaC03 at pH 4.5
Alkalinity, Bicarb, as CaCO3 at pH 4.5
Alkalinity, Carb. as CaC03 at pH 8.3
Chloride
Fluoride
Nitrate plus Nitrite as N
Sulfate
Total Dissolved Solids
OU3-MW16-RGW-001
Result RL Qual
<
2.5
6.9
10600
119
2960
<
3950
12900
19.1
56.2
56.2
<
3.9
0.27
0.42
5.5
114
10 U
4 U
5
5
5
3
0.1
0.1
5
10
OU3-MW16-RGW-002
Result RL Qual
<
2.4
9.4
12200
546
3070
9.1
•3220
<
10300
17.3
63.1
46.7
16.4
<
0.19
0.4
5.4
119
10 U
20 UJ
5
5
5
3
0.1
0.1
5
10
OU3-MW16-RGW-003 OU3-MW16-RGW-004
Result RL Qua] Result RL Qual
<
1.8
<
11300
894
2910
<
3210
3.4
10700
17
57.2
57.2
<
0.18
0.38
5.7
122
10
5.8
12.9
5
5
5
0.1
0.1
5
10
U 2 J
U
J
J
U
J
62.4 5
55.5 5
U 6.9 5
J 0.26 0.1
0.38 0.1
J 5.4 5
J 107 10
Results presented here ore only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2TOI.XLS]TABLEI6/-/jdg
MIIAFD • Record or Decision forOUs 1,3,5, and 6
9/I4/9S
Rev. 0
-------
TABLE 18
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT MW-17
Locator/Sample Round
OU3-MW17-RGW-001
Result RL Qual
OU3-MW17-RGW-002
Result RL Qual
OU3-MW17-RGW-0003
Result RL Qual
OU3-MW17-RGW-0004
Result RL Qual
Metals (ng/L)
Barium
Calcium
Chromium
Iron
Magnesium
Nickel
Potassium
Sodium
Vanadium
Water Quality (mg/L)
Alkalinity, Total as CaCO3 at pH 4.5
Alkalinity, Bicarb, as CaC03 at pH 4.5
Chloride
Fluoride
Nitrate plus Nitrite as N
Orthophosphate as P
Sulfate
Total Dissolved Solids
30.8
56300
<
1040
17300
5.5
5480
22900
7.2
113
113
38.1
0.15
6.9
0.064
64.2
333
9 U
5
5
3
0.1
0.5
0.05
5
10
28.6
56000
7.4
1740
17300
16.3
6100
22000
6.7
113
113
35.6
0.1
5.9
0.088
60.2
336
5
5
3
0.1
0.5
0.05
5
10
Results presented here are only those chemicals which were detected at least once in this well ana have passed data review.
RL - Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\lRD2T01.XLS]TABLEI8/-/jdg
MHAFB - Record of Decision for OUs 1,3, 5, and 6
9/14/95
Rev. 0
-------
TABLE 19
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT MW-18
Locator/Sample Round
OU3-MW18-RGW-001
Result RL Qual
OU3-MW18-RGW-002
Result RL Qual
Metals (ug/L)
Barium
Calcium
Iron
Magnesium
Manganese
Potassium
Sodium
Vanadium
Zinc
Water Quality (mg/L)
Alkalinity, Total as CaCO3 at pH 4.5
Alkalinity, Bicarb, as CaCO3 at pH 4.5
Chloride
Fluoride
Nitrate plus Nitrite as N
Orthophosphate as P
Sulfate
Total Dissolved Solids
33.5
50900
1840
15700
21.9
6590
24200
6.8
9.4
56
56
46.9
0.21
8.5
<
84.9
382
5
5
3
0.1
0.5
0.05
5
10
29
49800
1510
15300
27.4
7120
22000
5.8
<
58.8
58.8
43.5
0.13
7.6
0.072
77.1
331
9.8 U
5
5
3
0.1
0.5
0.05
5
10
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL - Repotting Limit
Qual = Qualifier
J •= Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2TOI.XLS]TABLEI6/-/jdg
MIIAPU - Record of Decision forOUs 1,3,5, and 6
9/14/95
Rev. 0
-------
TABLE 20
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT BPW-1
Locator/Sample Round BPW1-RGW-001 OU3-BPW1-RGW-003 OU3-BPW1-RGW-004
Result RL Qual Result RL Qual Result RL Qual
Volatile Organics (ug/L)
Trichloroethene
Bromoform
Semivolatile Organics (ug/L)
bis(2-Ethylhexyl)phthalate
Metals (Mg/L)
Arsenic
Barium
Calcium
Manganese
Water Quality (mg/L)
Alkalinity, Total as CaC03 at pH 4.5
Alkalinity, Bicarb as CaC03 at pH 4.5
Chloride
Fluoride
Nitrate plus Nitrite as N
Sulfate
Total Dissolved Solids
1.8 . 1.9 1.9 0.35
2 J < 10 U < 10 U
< 10 U 2 J < 10 U
1-3
2.8
292 J
8.4
107
107
38.4
0.28
17
78.1
393
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2T01 .XLS]TABLE 20/-/jdg 9/14/95
M11AFD - Record of Decision for Oils 1, 3, 5, and 6 Rev. 0
-------
TABLE 21
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT BPW-2
Locator/Sample Round
Volatile Organics (fig/L)
Benzene
Trichloroethene
Semivolatile Organics (ug/L)
4-Nitrophenol
bis(2-ethylhexyl)phthalate
Metals (ug/L)
Barium
Calcium
Magnesium
Potassium
Sodium
Vanadium
Water Quality (mg/L)
Alkalinity, Total as CaC03 at pH 4.5
Alkalinity, Bicarb, as CaC03 at pH 4.5
Chloride
Fluoride
Nitrate plus Nitrite as N
Orthophosphate as P
Sulfate
Total Dissolved Solids
BPW2-RGW-001
Result RL ual
1.4
1.3
< 24
3
8.8
16500
3710
4350
14200
15.4
64.8
64.8
4.9
0.14
1.5
0.36
11.4
130
U
J
J
J
J
J
J
OU3-BPW2-RGW-002 OU3-BPW2-RGW-003 OU3-BPW2-RGW-00
Result RL Qual Result RL Qual Result RL Qual
<
1
9.9
16600
<
3620
12500
15.4
63.5
63.5
4.7
0.15
1.5
<
11.5
138
0.4 U < 0.4 U < 0.4 U
0.38 U < 0.35 U 2.5 0.35
J < 25 U < 25 U
3800 U
5
5
3
0.1
0.1
0.05 U
5
10
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2TOI.XLS]TABLE16/-/jdg
MIIAPU - Record of Decision forOUs 1,3,5, and 6
9/14/95
Rev. 0
-------
TABLE 22
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT BPW-4
Locator/Sample Round
BPW4-RGW-001
Result RL Qual
OU3-BPW4-RGW-002
Result RL Qual
OU3-BPW4-RGW-003
Result RL Qual
OU3-BPW4-RGW-004
Result RL Qual
Volatile Organics (ng/L)
Acetone
Bromoform
Trichloroethene
Metals (ug/L)
Barium
Calcium
Magnesium
Potassium
Sodium
Vanadium
Water Quality (mg/L)
Alkalinity, Total as CaC03 at pH 4.5
Alkalinity, Bicarb, as CaC03 atpH 4.5
Chloride
Fluoride
Nitrate plus Nitrite as N
Orthophosphate as P
Sulfate
Total Dissolved Solids
< 10 U
3 J
1
11.6
32700 J
10200 J
4470
15300
136
87.8
87.8
13.6
0.14
6.6
0.062 J
27.8
225
1
13.2
38100
12200
4430
16000
13.5
88.6
88.6
19
0.1
6.4
<
36.5
248
0.38 J 1 0.35 1.1 0.35
5
5
3
0.1
0.5
0.05 U
5
10
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2TOI .XLS]TABLE 22/-/jdg
MHAFB • Record of Decision forOUs 1,3, 5, and 6
9/14/95
Rev. 0
-------
TABLE 23
SUMMARY OF CHEMICALS DETECTED IN GROUND WATER SAMPLES AT BPW-5
Locator/Sample Round
BPW5-RGW-001
Result RL Qual
OU3-BPW5-RGW-002
Result RL Qual
Metals Oig/L)
Barium
Calcium
Copper
Iron
Lead
Magnesium
Manganese
Potassium
Sodium
Vanadium
Zinc
Water Quality (mg/L)
Alkalinity, Total as CaC03 at pH 4.5
Alkalinity, Bicarb, as CaCO3 at pH 4.5
Chloride
Fluoride
Nitrate plus Nitrite as N
Orthophosphate as P
Sulfate
Total Dissolved Solids
31.5
79400
53
<
3.1
24400
<
8440
32900
10.3
131
87.5
87.5
63.8
0.14
12.3
0.11
154
490
J
J
17 U
J
J
8 U
J
34.1
80700
<
831
3.3
24500
16.6
7120
28300
8.6
176
81
81
63.3
<
11
<
153
545
7.7
5
5
3
0.1
0.5
0.05
5
10
U
J
U
U
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2TOI.XLS]TABLE16/-/jdg
MIIAPU - Record of Decision forOUs 1,3,5, and 6
9/14/95
Rev. 0
-------
TABLE 24
SUMMARY OF CHEMICALS DETECTED IN GROUND WATER SAMPLES AT BPW-6
Locator/Sample Round
BPW6-RGW-001
Result RL Qual
OU3-BPW6-RGW-002
Result RL Qual
Semivolatile Organics (ug/L)
bis(2-Ethylhexyl) phthalate
Metals Gig/L)
Arsenic
Barium
Calcium
Magnesium
Potassium
Sodium
Vanadium
Water Quality (mg/L)
Alkalinity, Total as CaC03 at pH 4.5
Alkalinity, Bicarb, as CaCOS at pH 4.5
Chloride
Fluoride
Nitrate plus Nitrite as N
Sulfate
Total Dissolved Solids
< 10 U
3.8
12.7
22000
5460
4750 J
11900 J
21.3
58.6
58.6
8.4
0.19
1.2
29
185
1
2.5
30.4
53900
13700
6780
18500
18.3
57.2
57.2
31.8
0.16
3.6
111
354
J
5
5
3
0.1
0.2
5
10
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL *> Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondctected value.
92520\A\[RD2T01.XLS]TABLE 24/-/jdg
Ml I AM • Record of Decision forOUs 1,3,5, and 6
9/14/95
Rev. 0
-------
TABLE 25
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT BPW-7
Locator/Sample Round
BPW7-RGW-001
Result RL Qual
OU3-BPW7-RGW-002
Result RL Qual
Volatile Organics (ug/L)
Methylene Chloride
Metals (ng/L)
Barium
Cadmium
Calcium
Magnesium
Potassium
Selenium
Sodium
Vanadium
TPH (mg/L)
Total Petroleum Hydrocarbons
Water Quality (mg/L)
Alkalinity, Total as CaC03 at pH 4.5
Alkalinity, Bicarb, as CaCO3 at pH 4.5
Chloride
Fluoride
Nitrate plus Nitrite as N
Sulfate
Total Dissolved Solids
< 10 U
< 57.3 U
< 4 U
97600
20300 J
9840 J
1.6 J
26700 J
12.3
61.4
61.4
54.2
0.32
12.2
184
521
1
42
5.2
63600
14900
7600
<
22100
15.4
1.2
59.9
59.9
36.9
0.11
7.8
128
406
2
1
5
5
3
0.1
0.5
5
10
J
J
UJ
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
) = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2TOI.XLS]TABLE16/-/jdg
MIIAPU - Record of Decision forOUs 1,3,5, and 6
9/14/95
Rev. 0
-------
TABLE 26
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT BPW-8
Locator/Sample Round
OU3-BPW8-RGW-001
Result RL Qual
OU3-BPW8-RGW-002
Result RL Qual
Volatile Organ ics (fig/L)
Trichloroethene
Metals (fig/L)
Barium
Calcium
Magnesium
Potassium
Sodium
Vanadium
Zinc
Water Quality (mg/L)
Alkalinity, Total as CaCO3 at pH 4.5
Alkalinity, Bicarb, as CaCOS at pH 4.5
Chloride
Fluoride
Nitrate plus Nitrite as N
Sulfate
Total Dissolved Solids
0.3 J
48.5
94600
25800
8640
32100
9.4
28.2.
79.7 5
79.7 5
70.7 3
0.13
12.9 1
192 5
584 10
<
54.3
104000
28000
9420
29800
10.6
<
80.7
80.7
72.9
<
15.7
199
664
0.38
19
5
5
3
0.1
1
5
10
U
U
U
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2TOI .XLS]TABLE 26/-/jdg
MIIAFI) • Record of Decision Tor OUs 1,3,5, and 6
9/14/95
Rev. 0
-------
TABLE 27
SUMMARY OF CHEMICALS DETECTED TN GRQTJNDWATER SAMPT>F.S AT RPW-9
Locator/Sample Round BPW9-RGW-001 OU3-BPW9-RGW-002 OU3-BPW9-RGW-003 OU3-BPW9-RGW-004
Result RL Qua! Result RL Qual Result RL Qual Result RL Qual
Volatile Organics (u,g/L)
Trichloroethene
Semivolatile Organics (fig/L)
bis(2-Ethylhexyl) phthalate
Pentachlorophenol
Metals Oig/L)
Barium
Calcium
Copper
Iron
Lead
Magnesium
Manganese
Nickel
Potassium
Sodium
Vanadium
Zinc
Water Quality (mg/L)
Alkalinity, Total as CaCO3 at pH 4.5
Alkalinity, Bicarb, as CaCO3 at pH 4.5
Chloride
Fluoride
Nitrate plus Nitrite as N
Sulfate
Total Dissolved Solids
Orthophosphate as P
1.6
< 10 U
0.65 J
17.2
45300 J
35.2 J
978
7.3 J
14600 J
18.8
< 7 U
6420
22500
12.5
840
100
100
25.7
0.15
4.6
62.6
284
< 0.05 UJ
2.4
1
<
18.1
44600
<
<
<
14000
<
3.3
5070
19600
11.6
178
101
101
24.6
4.4
55.4
307
0.079
2.4 0.35
J
0.65 U < 25 U
9.7 U
54.1 U
1 UJ
4 U
5
5
3
0.02
5
10
0.05
3 NJ
2 ' J
< 25 U
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
N = Presumptively present.
92520\A\[RD2TOI.XLS]TABLE16/-/jdg
MJIAFI) • Record of Decision for Oils 1,3,5, and 6
9/14/95
Rev. 0
-------
TABLE 28
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT 301
Locator/Sample Round OU3-30I-RGW-002
Result RL Qual
Metals (ng/L)
Barium 9.8
Calcium 26600
Chromium 7.3
Magnesium 8560
Manganese 4
Nickel 3.8
Potassium 3800
Sodium 14300
Vanadium 19.3
Water Quality (mg/L)
Alkalinity, Total as CaC03 at pH 4.5 67.7 5
Alkalinity, Bicarb, as CaCO3 at pH 4.5 67.7 5
Chloride 13.4 3
Fluoride 0.14 0.1
Nitrate plus Nitrite as N 3.8 0.2
Sulfate 31.8 5
Total Dissolved Solids 202 10
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U ° Nondetected value.
92520\A\[RD2T01 .XLSJTABLE 28/-/jdg 9/14/95
Ml I API) • Record of Decision forOUl 1,3, 5, and 6 Rev. 0
-------
TABLE 29
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT 31ABA1
Locator/Sample Round
OU3-31ABA1-RGW-002
Result RL Qual
OU3-31ABA1-RGW-003
Result RL Qual
Volatile Organics (fig/L)
Tetrachloroethene
Trichloroethene
Metals (fig/L)
Arsenic
Barium
Calcium
Lead
Magnesium
Potassium
Sodium
Vanadium
TPH (mg/L)
Total Petroleum Hydrocarbons
Water Quality (mg/L)
Alkalinity, Total as CaC03 at pH 4.5
Alkalinity, Bicarb, as CaCO3 at pH 4.5
Chloride
Fluoride
Nitrate plus Nitrite as N
Orthophosphate as P
Sulfate
Total Dissolved Solids
1
1
2.8
20.1
52100
4.2
16300
5800
28100
12.5
1.3
142
142
34.1
0.13
5.5
0.056
47.5
356
0.39 J < 0.39 U
0.38 J 0.21 0.35 J
J
1
5
5
3
0.1
0.2
0.05
5
10
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R *> Rejected value.
U = Nondetected value.
92520\A\[RD2TOI.XLS]TABLE16/-/jdg
MIIAPU - Record of Decision forOUs 1,3,5, and 6
9/14/95
Rev. 0
-------
TABLE 30
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT 36AAAA
Locator/Sample Round OU3-36AAA-RGW-001
Result RL Qual
Metals (fig/L)
Antimony 68.5
Arsenic 1.2
Barium 10.7
Calcium . 12700
Chromium 7.3
Magnesium 3680
Potassium 3160
Sodium 9970
Vanadium 22.6
Water Quality (mg/L)
Alkalinity, Total as CaC03 at pH 4.5 57.9 5
Alkalinity, Bicarb, as CaCO3 at pH 4.5 57.9 5
Chloride 3 3
Fluoride 0.15 0.1
Nitrate plus Nitrite as N 1.1 0.1
Sulfate 6.7 5
Total Dissolved Solids 116 10
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
02520\A\[RD2T01 .XLS]TAni J: 30/-/jdg 9/14/95
MIIAFIJ • Record of Decision for Oils 1,3,5, nnd 6 Rev. 0
-------
TABLE 31
SUMMARY OF CHEMICALS DETECTED IN GROUNDWATER SAMPLES AT 5ACCI
Locator/Sample Round OU3-5ACC1-RGW-002 OU3-5ACC1-RGW-003
Result RL Qual Result RL Qual
Volatile Organics (ug/L)
Acetone
Methylene Chloride
Metals Oig/L)
Calcium
Magnesium
Potassium
Sodium
Vanadium
TPH(mg/L)
Total Petroleum Hydrocarbons
Water Quality (mg/L)
Alkalinity, Total as CaCO3 at pH 4.5
Alkalinity, Bicarb, as CaCO3 at pH 4.5
Chloride
Fluoride
Nitrate plus Nitrite as N
Sulfate
Total Dissolved Solids
7
1
53400
16300
6320
21000
12.5
1
88.4
88.4
36.9
0.1
7.5
71.6
352
J
J
1
5
5
3
0.1
0.5
5
10
< 10 UJ
< 10 U
Results presented here are only those chemicals which were detected at least once in this well and have passed data review.
RL = Reporting Limit
Qual = Qualifier
J = Estimated value.
R = Rejected value.
U = Nondetected value.
92520\A\[RD2TOI.XLS]TABLE !6/-/jdg 9/14/95
Ml IA1-U - Record of Decision for OUs 1,3,5, and 6 Rev. 0
-------
TABLE 38
SUMMARY OF BASE-WIDE CHEMICALS OF CONCERN IN SOILS (mg/kg)
RME CONCENTRATIONS OF METALS ABOVE BACKGROUND AND DETECTED ORGANIC COMPOUNDS
Analyte DP-09(3)
Metals
Antimony
Arsenic 4.8 J
Barium
Beryllium
Cadmium 0.84
Chromium
Cobalt
Copper
Lead
Mercury
Nickel
Silver 1.3
Vanadium
Zinc
VOCs
,1-Dichloroethane
,1,1 Trichloroethane
,2-Dichloroethane
,1-Dichloroethene
,2 Dichloroethene
,1,2-Trichloroethane
2-Butanone
Acetone
Benzene
Carbon disulfide
Chloroform
Chlorobenzene
Dibromochloromethane
\\tRD2T01. XLSJTABLE 38/jdg/md/jdg/md
1 • Record of Decision for OUs 1, 3, 5, and 6
DP-18(3) FT-07B(3) FT-07C(3) LF-02(2) LF-23(3) OT-16(1)
D*» TR
5.5 J
18.8 14.7 12.6 38.1 10.5 8.9 J
406
1.74 1.1
0.73 1.47 0.74
44 24.2
173 J 20.7 24.53
24.5 133 J 157.2
0.57 0.62 0.41
25.4
46.4
95.2 1403 1176.2 65.5 79.31
0.0028 J 0.0019 J
0.004 J 0.046 0.026
0.0016 J
0.0023 J
0.0086 J 0.009 0.007
32 0.031 0.01
0.0035 J 0.0023 J
0.0085 J 0.0071
9/14/95
Sheet 1 of 8 Rev. 1
-------
TABLE 38
SUMMARY OF BASE-WIDE CHEMICALS OF CONCERN IN SOILS (mg/kg)
RME CONCENTRATIONS OF METALS ABOVE BACKGROUND AND DETECTED ORGANIC COMPOUNDS
Analyte DP-09(3)
Ethylbenzene
Methylene Chloride
Styrene
Tetratchloroethene
Toluene
Trichloroethene
Xylenes (total)
SVOCs
1 ,4-Dichlorobenzene
2,4-Dichlorophenol
2,4-Dimethylphenol
2-Methylphenol
4-Methyl phenol
4-Nitrophenol
Benzole Acid
bis(2-ethylhexy!)phthalate
Butylbenzylphthalate
Carbazole
Di-n-butylphthalate
Dibenzofuran
Diethylphthalate
Hexylphthalate
N-nitrosodiphenylamine
Phenol
DP-18(3) FT-07B(3) FT-07C(3) LF-02(2) LF-23(3)
D** TR
0.0018 J 0.002 J
0.03 0.013
31 0.001J
0.0032 J 0.0013 J 0.001 J 0.002 J
0.18 0.037 0.017 0.008
0.005 1J 0.0038 J 0.006 0.005
0.061 J 0.005 0.005
1.544
0.224
0.066 J
4.7 J 0.11
0.213
0.1J 0.196 0.49
0.044 J 0.079 J
0.044 J 0.27 J
0.086 J
2.8 J
OT-16(1)
0.002 J
0.004
PAHs
2-Methylnaphthalene
92520\A\[RD2T01 .XLSJTABLE 38/jdg/md/jdg/md
MHAFB • Record of Decision for OUs 1,3,5, and 6
20
Sheet 2 of 8
0.053 J
0.11 J
9/14/95
Rev. 1
-------
TABLE 38
SUMMARY OF BASE-WIDE CHEMICALS OF CONCERN IN SOILS (mg/kg)
RME CONCENTRATIONS OF METALS ABOVE BACKGROUND AND DETECTED ORGANIC COMPOUNDS
Analyte
Acenaphthene
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(b,h)perylene
Benzo(g,h,i)perylene
Benzo(k)fluoranthene
Chrysene
Dibenzo(a,h)anthracene
Fluoranthene
Fluorene
Ideno (l,2,3-c,d) pyrene
Naphthalene
Phenanthrene
Pyrene
TPH
TRPH
Pesticides
2,4-D
4,4-DDD
4,4-DDE
4,4-DDT
Aldrin
alpha-Chlordane
DP-09(3) DP-18(3) FT-07B(3) FT-07C(3) LF
D»*
0.083 J
0.673
0.595
0.878
0.045
0.49
0.687
0.867
0.1 J
0.34
0.649
8720 2640 886
0.041
0.381
0,995
-02(2)
TR
0.08 J
0.193
1.458
0.283
1.473
1.082
0.257
1.46
0.17J
1.572
0.094 J
0.234
0.193
1.507
1.47
3970
6.5
0.042
0.065
0.032
0.014
LF-23(3)
0.68
0.75
1.7
1.3
1.7
0.66
0.83
1.7
-
3.33
0.55
0.65
0.28 J
3.33
0.41
OT-16(1)
2.122
2.1
2.308
2.139
1.978
0.099
2.347
653.23
92520\A\[RD2T01.XLS]TABLE38/jdg/mdyjdg/md
MHAFB ' Record of Decision Tor OUs 1,3, 5, and 6
Sheet 3 of 8
9/14/95
Rev. 1
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TABLE 38
SUMMARY OF BASE-WIDE CHEMICALS OF CONCERN IN SOILS (rag/kg)
RME CONCENTRATIONS OF METALS ABOVE BACKGROUND AND DETECTED ORGANIC COMPOUNDS
Analyte DP-09(3) DP-18(3) FT-07B(3) FT-07C(3) LF-02(2) LF-23(3) OT-16(1)
D** TR ""
Dieldrin 0.011 J
Endrin
gamma-Chlordane 0.016
Heptachlor
Heptachlor epoxide
Herbicide
MCPP
PCBs
Aroclor-1242 0.134
Aroclor-1254 0.271 0.2
Aroclor-1260 0.041
D - Drum Disposal Area TR - Trench Area
J -Estimated Value
* - Sediment Samples Included In SD-25 Sediment Data
x - Represents Surface Soil Sample Data
** - Samples contained @ 1/3 coal ash and 2/3 soil, which has been considered representative of the Ash Disposal Area also
Sources: 1 W-C 1993a 3 W-C 1992b
2 W-C 1992a
92520\A\[RD2T01.XLS]TABLE 38/jdg/md/jdg/md 9/14/95
MHAFB - Record of Decision forOUs 1,3,5, and 6 Sheet 4 of 8 Rev. 1
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TABLE 38
SUMMARY OF BASE-WIDE CHEMICALS OF CONCERN IN SOILS (mg/kg)
RME CONCENTRATIONS OF METALS ABOVE BACKGROUND AND DETECTED ORGANIC COMPOUNDS
Analyte
Metals
Antimony
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Copper
Lead
Mercury
Nickel
Silver
Vanadium
Zinc
VOCs
1,1-Dichloroethane
1,1,1 Trichloroethane
1,2-Dichloroethane
1,1-Dichloroethene
l,2Dichloroethene
1 , 1 ,2-Trichloroethane
2-Butanone
Acetone
SD-12(1) SD-24*(1) SD-27*(1) SS-28(3)
0.66 J
5.94 4.6 J
516.14
1.2
1.09 1.9 1.1
38.7 22.1
22.71
26.75 34.1
91.6 82
23.4
43.6
283.08 74.5
0.002 J
3.88
0.0056 0.008
0.011 0.009 3.844
SS-29(1)
1097.63
122.06
43.58
135.7
162
0.0025 J
0.0095
0.025 J
0.004 J
ST-ll(l) ST-34(1)
7.6 J
4.86
1.09
23.43
10.1 91.43
66.35
0.254 J
Benzene
Carbon disulfide
Chloroform
Chlorobenzene
Dibromochloromethane
0.006 J
0.002 J
0.001 J
7.501
92520\A\[RD2T01.XLS]TABLE38/jdg/md/jdg/md
MHAFB - Record of Decision for OUs 1,3,5, and 6
Sheet 5 of 8
9/14/95
Rev. 1
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TABLE 38
SUMMARY OF BASE-WIDE CHEMICALS OF CONCERN IN SOILS (mg/kg)
RME CONCENTRATIONS OF METALS ABOVE BACKGROUND AND DETECTED ORGANIC COMPOUNDS
Analyte
SD-12(1)
SD-24*(1)
SD-27*(1)
SS-28(3)
SS-29(l)
ST-ll(l)
ST-34(1)
Ethylbenzene
Methylene Chloride
Styrene
Tetratchloroethene
Toluene
Trichloroethene
Xylenes (total)
0.002 J
0.002 J
0.002 J
0.004
3.974
136
3.18
0.02
0.022
0.002 J
0.102
0.003 J
0.259
0.005 J
0.017
0.003 J
0.0033 J
0.0074
0.0061
0.002 J
11.8
106
106
10.72
139.2
139.2
SVOCs
1,4-DichIorobenzene
2,4-Dichlorophenol
2,4-Dimethylphenol
2-Methylphenol
4-Methyl phenol
4-Nitrophenol
Benzoic Acid
bis(2-ethylhexyl)phthalate
Butylbenzylphthalate
Carbazole
Di-n-butylphthalate
Dibenzofuran
Diethylphthalate
Hexylphthalate
N-nitrosodiphenylamine
Phenol
0.064
27.2
5.5 J
6.7 J
3.35 J
0.1 J
1.3
0.065
0.091
1.1
2.406
2.4 J
3J
1.3 J
6.3
0.54 J
0.865
0.54
1.192
0.53
PAHs
2-Methylnaphthalene
92520\A\[RD2T01 .XLSJTABLE 38/jdg/md/jdg/md
MHAFB • Record of Decision for OUs 1,3,5, and 6
Sheet: 6 of 8
9/14/95
Rev. 1
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TABLE 38
SUMMARY OF BASE-WIDE CHEMICALS OF CONCERN IN SOILS (mg/kg)
RME CONCENTRATIONS OF METALS ABOVE BACKGROUND AND DETECTED ORGANIC COMPOUNDS
Analyte
Acenaphthene
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(b,h)perylene
Benzo(g,h,i)perylene
Benzo(k)fluoranthene
Chrysene
Dibenzo(a,h)anthracene
Fluoranthene
Fluorene
Ideno (l,2,3-c,d) pyrene
Naphthalene
Phenanthrene
Pyrene
TPH
TRPH
Pesticides
2,4-D
4,4-DDD
4,4-DDE
4,4-DDT
Aldrin
alpha-Chlordane
SD-12(1) SD-24*(1)
0.31
0.33 J
0.041 0.74
0.42
0.048
0.43
0.092 J
0.04 0.8
0.31 J
0.51J
0.045 5.6
7099
0.326
0.098
0.691
0.052
0.322
SD-27*(1) SS-28(3)
2.4 J
2.834
7.468
7.466
12.186
4.865
3.807
7.454
4.253
17.608
1.267
4.966
1.8
14.012
3083.12
0.113 J
0.048
0.01 J
0.03 J
SS-29(1) ST-ll(l) ST-34(1)
0.723
0.911
3.146
5.449
12.495
0.42
6.243
0.58
12.993
0.763
2.73
0.053 J
11.261
1874.78
92520\A\[RD2T01.XLS]TABLE38/jdg/md/jdg/md
MHAFB - Record of Decision for OUs 1, 3, 5, and 6
Sheet 7 of 8
9/14/95
Rev. 1
-------
TABLE 38
SUMMARY OF BASE-WIDE CHEMICALS OF CONCERN IN SOILS (mg/kg)
RME CONCENTRATIONS OF METALS ABOVE BACKGROUND AND DETECTED ORGANIC COMPOUNDS
Analyte
SD-12(1)
SD-24*(1)
SD-27*(1)
SS-28(3)
SS-29(1)
ST-ll(l)
ST-34(1)
Dieldrin
Endrin
gamma-Chlordane
Heptachlor
Heptachlor epoxide
1.12
0.299
0.084
0.024 J
0.027 J
0.022 J
0.023
Herbicide
MCPP
94.00
PCBs
Aroclor-1242
Aroclor-1254
Aroclor-1260
D - Drum Disposal Area TR -Trench Area
J -Estimated Value
* - Sediment Samples Included In SD-25 Sediment Data
x - Represents Surface Soil Sample Data
** - Samples contained @ 1/3 coal ash and 2/3 soil, which has been considered representative of the Ash Disposal Area also
Sources: 1 W-C 1993a 3 W-C I992b
2 W-C 1992a
92520\A\[RD2T01 .XLSJTABLE 38/jdg/md/jdg/md
MHAFB - Record of Decision for OUs 1,3,5, and 6
SheettSofS
9/14/95
Rev. I
-------
TABLE 39
SUMMARY OF BASE-WIDE CHEMICALS OF CONCERN
IN SURFACE WATER (mg/kg)
RME CONCENTRATIONS OF METALS ABOVE BACKGROUND
AND DETECTED ORGANIC COMPOUNDS
Analytes LF-01(2) SD-25(1)
Metals
Aluminum
Arsenic
Barium
Beryllium
Cadmium
Chromium
Cobalt
Copper
Lead
Mercury
Nickel
Silver
Vanadium
Zinc 0.167
VOCs
1,1-Dichloroethane
1,1,1 Trichloroethane
1,2-Dichloroethane
1,2 Dichloroethene
1,1,2-Trichloroethane
2-Butanone 0.005 0.004 J
Acetone 0.070
Benzene 0.004
Bromodichloromethane 0.001 J
Carbon disulfide
Chloroform
Dibromochloromethane 0.003 J
Ethylbenzene
Methylene Chloride
Styrene
Tetratchloroethene
Toluene 0.002 J
Trichloroethene
Xylenes (total) 0.004 J
92520\A\[RD2TO 1 .XLS]TABLE 39 /md/cee 9/25/95
MHAFB - Record of Decision for OUs 1,3,5, and 6 Sheet 1 of 3 Rev. 1
-------
TABLE 39
SUMMARY OF BASE-WIDE CHEMICALS OF CONCERN
IN SURFACE WATER (mg/kg)
RME CONCENTRATIONS OF METALS ABOVE BACKGROUND
AND DETECTED ORGANIC COMPOUNDS
Analytes
LF-01
P)
SD-25(1)
SVOCs
1,2 Dichlorobenzcne
1,4-Dichlorobenzene
2,4-Dichlorophenol
2,4-Dimethylphenol
3,3-Dichlorobenzidine
4-methyl phenol
Benzoic Acid
bis (2-ethylhexyl) phthalate
Butylbenzylphthalate
Carbazole
Di-n-butylphthalate
Di-n-octylphthalate
Dibenzofuran
N-nitrosodiphenylamine
Pentachlorophenol
Phenol
0.005
0.005
0.025
0.027
0.005
0.002 J
0.004 J
0.008
PAHs
2-Methylnaphthalene
Acenaphthene
Anthracene
Benzo (a) anthracene
Benzo (a) pyrene
Benzo (b) fluoranthene
Benzo (g,h,i) perylene
Benzo (k) fluoranthene
Chrysene
Dibenzo (a,h) anthracene
Fluoranthene
Fluorene
Indeno (l,2,3-c,d) pyrene
Naphthalene
Phenanthrene
Pyrene
TPH
0.002 J
0.007
0.002 J
TRPH
92520\A\[RD2T01.XLS]TABLE 39 /md/cee
MHAFB - Record of Decision for OUs 1,3, S, and 6
Sheet 2 of 3
9/25/95
Rev. I
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TABLE 39
SUMMARY OF BASE-WIDE CHEMICALS OF CONCERN
IN SURFACE WATER (mg/kg)
RME CONCENTRATIONS OF METALS ABOVE BACKGROUND
AND DETECTED ORGANIC COMPOUNDS
Analytes LF-01(2) SD-25(1)
Pesticides
4,4-DDD
4,4-DDE
4,4-DDT
Aldrin
alpha-Chlordane
beta-BHC
Dieldrin
gamma-Chlordane
Heptachlor
Heptachlor epoxide
Herbicide
MCPP
PCBs
Aroclor-1242
Aroclor-1254
Aroclor-1260
J Estimated value
Sources:
(l) W-C 1993
(2) W-C 1992a
92520\A\[RD2TO 1 .XLSJTABLE 39 /md/cee 9/25/95
MHAFB - Record of Decision for OUs 1,3,5, and 6 Sheet 3 of 3 Rev. 1
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