PB96-964413
EPA/ROD/R08-96/115
October 1996
EPA Superfund
Record of Decision:
Ellsworth Air Force Base,
Operable Unit 12, Rapid City, SD
5/10/1996
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Final
Record of Decision for
Remedial Action at Operable Unit 12
Ellsworth Air Force Base, South Dakota
United States Air Force
Air Combat Command
Ellsworth Air Force Base
April 1996
Air Force Project No. FXBM 94-7002
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Final Record of Decision Operable Unit 12
Ellsworth Air Force Base, South Dakota
TABLE OF CONTENTS
Chapter Page
1.0 DECLARATION FOR THE RECORD OF DECISION 1-1
1.1 SITE NAME AND LOCATION 1-1
1.2 STATEMENT OF BASIS AND PURPOSE 1-1
1.3 ASSESSMENT OF THE SITE 1-1
1.4 DESCRIPTION OF SELECTED REMEDY 1-1
1.5 STATUTORY DETERMINATION ; 1-2
1.6 SIGNATURE AND AGENCY CONCURRENCE ON THE REMEDY 1-3
2.0 DECISION SUMMARY 2-1
2.1 SITE NAME AND LOCATION 2-1
2.2 OPERABLE UNIT 12 (OU-12) DESCRIPTION/HISTORY AND
REGULATORY OVERSIGHT ACTIVITIES 2-1
2.2.1 Description/History 2-1
2.2.2 Regulatory Oversight Activities 2-2
2.3 HIGHLIGHTS OF COMMUNITY PARTICIPATION 2-3
2.4 SCOPE AND ROLE OF RESPONSE ACTION 2-4
2.5 SITE CHARACTERISTICS 2-5
2.5.1 Soils 2-5
2.5.2 Sediment 2-6
2.5.3 Ground Water 2-6
2.5.4 Surface Water 2-7
2.6 SITE RISK SUMMARY 2-8
2.7 DESCRIPTION OF ALTERNATIVES 2-11
2.8 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES 2-12
2.8.1 Overall Protection of Human Health and the Environment 2-12
2.8.2 Compliance with ARARs -. 2-13
2.8.3 Long-Term Effectiveness and Permanence 2-14
2.8.4 Reduction of Toxicity, Mobility, and Volume Through Treatment 2-15
2.8.5 Short-Term Effectiveness 2-15
2.8.6 Implementability 2-16
2.8.7 Cost : 2-16
2.8.8 State Acceptance 2-18
2.8.9 Community Acceptance : 2-18
2.9 SELECTED ALTERNATIVE 2-18
2.10STATUTORY DETERMINATIONS 2-21
2.10.1 Protection of Human Health and the Environment 2-21
2.10.2 Compliance with ARARs 2-21
2.10.3 Cost Effectiveness 2-22
TABLE OF CONTENTS (continued)
Apnl 1996
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Final Record of Decision Operable Unit 12
Ellsworth Air Force Base, South Dakota
2.10.4 Utilization of Permanent Solutions and Alternative Treatment
Technologies to the Extent Possible 2-22
2.10.5 Preference for Treatment as a Principal Element 2-22
2.11 DOCUMENTATION OF SIGNIFICANT CHANGES 2-22
3.0 LIST OF ACRONYMS AND ABBREVIATIONS 3-1
APPENDICES
Appendix A Figures
Appendix B Responsiveness Summary
LIST OF FIGURES
Figure 2-1 Area Location Map
Figure 2-2 Site Map
Figure 2-3 Operable Unit 12
Figure 2-4 OU-12 Potentially Affected Wetlands
Figure 2-5 Operable Unit 12 Area of Attainment
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Final Record of Decision Operable Unit 12
Ellsworth Air Force Base, South Dakota
1.0 DECLARATION FOR THE RECORD OF DECISION
1.1 SITE NAME AND LOCATION
Operable Unit 12 (OU-12), Hardfill No. 1, Ellsworth Air Force Base (EAFB), National
Priorities List Site.
Meade and Pennington Counties, South Dakota
1.2 STATEMENT OF BASIS AND PURPOSE
This decision document describes EAFB's selected remedial action for OU-12, in accordance with
the Comprehensive Environmental Response,.Compensation, and Liability Act of 1980
(CERCLA), as amended by the Superfund Amendments and Reauthorization Act of 1986
(SARA), and the National Oil and Hazardous Substances Pollution Contingency Plan (NCP).
This decision is based on the contents of the Administrative Record for OU-12, EAFB. The U.S.
Environmental Protection Agency (EPA) and the South Dakota Department of Environment and
Natural Resources (SDDENR) concur with the selected remedial action.
1.3 ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances from OU-12, if not addressed by
implementing the response action selected in this Record of Decision (ROD), may present an
imminent and substantial endangerment to public health, welfare, or the environment.
1.4 DESCRIPTION OF SELECTED REMEDY
Twelve potentially contaminated areas, or operable units, have been identified at EAFB. This
ROD is for a remedial action at OU-12 (Hardfill No. 1, approximately 14 acres) and is the ninth
ROD for EAFB
The selected alternative, capping, includes the following major components:
Placing a soil cover capable of sustaining perennial vegetation over the hardfill area;
Pre-design study to identify the source of methane and examine the need for hardfill gas
control measures, and evaluate the need for erosion control measures along the stream
- adjacent to the hardfill areas;
Institutional controls for the hardfill areas;
Long-term monitoring;
Long-term maintenance of soil cover.
Implementation of the remedy will reduce the future risk to human health and the environment to
acceptable levels.
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Final Record of Decision Operable Unit 12
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1.5 STATUTORY DETERMINATION
The selected remedy is protective of human health and the environment, complies with Federal
and the State of South Dakota 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 (or resource recovery) technologies, to the maximum extent practicable for
OU-12. However, because treatment of the principal threats of the OU was not found to be
practicable, this remedy does not satisfy the statutory preference for treatment as a principal
element. The large size of the hardfill and the fact that there are no apparent on-site hot spots that
represent major sources of contamination preclude a remedy in which contaminants could be
excavated and treated effectively.
Because this remedy will result in hazardous substances remaining on-site beneath the hardfill
cover area, a review will be conducted no less often than every five years after signing of the
ROD to ensure that the remedy continues to provide adequate protection of human health and the
environment.
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1.6 SIGNATURE AND AGENCY CONCURRENCE ON THE REMEDY
BRETT M. DULA Date
Lieutenant General, USAF
Vice Commander
JACKW. MCGRAW Date
Acting Regional Administrator
U.S. Environmental Protection Agency Region 8
NETTIE H. MYERS, Secretary Date
Department of Environment and Natural Resources
State of South Dakota
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Final Record of Decision Operable Unit 12
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1.6 SIGNATURE AND AGENCY CONCURRENCE ON THE REMEDY
BRETT M. DULA
Lieutenant General, USAF
Vice Commander
Date
JACK W. MCGRAW
Acting Regional Administrator
U.S. Environmental Protection Agency Region 8
Date
NETTIE H. MYERS, S
Department of Enviro
State of South Dakota
Date
nd Natural Resources
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Final Record of Decision Operable Unit 12
Ellsworth Air Force Base, South Dakota
2.0 DECISION SUMMARY
2.1 SITE NAME AND LOCATION
EAFB is a U.S. Air Force Air Combat Command (ACC) installation located 12 miles east of
Rapid City, South Dakota, and adjacent to the small community of Box Elder (Figure 2-1).
EAFB covers approximately 4,858 acres within Meade and Pennington counties and includes
runways and airfield operations, industrial areas, and housing and recreational facilities (Figure 2-
2). Open land, containing a few private residences, lies adjacent to EAFB on the north, south,
and west, while residential and commercial areas lie to the east of the Base.
2.2 OPERABLE UNIT 12 (OU-12) DESCRIPTION/HISTORY AND REGULATORY
OVERSIGHT ACTIVITIES
2.2.1 Description/History
Ellsworth Air Force Base (EAFB) was officially activated in July 1942 as the Rapid City Army
Air Base, a training facility for B-17 bomber crews. It became a permanent facility in 1948 with
the 28th Strategic Reconnaissance Wing as its host unit. Historically, EAFB has been the
headquarters of operations for a variety of aircraft, as well as the Titan I Intercontinental Ballistic
Missile, and the Minuteman I and Minuteman n missile systems. The Air Force has provided
support, training, maintenance, and/or testing facilities at EAFB. Presently, the 28th
Bombardment Wing (B-1B bombers) is the host unit of EAFB.
OU-12 is located in the southern half of EAFB, immediately north of the Alert Apron and
southwest of the Primary Instrument Runway (Figure 2-3). OU-12 is the area designated as
Hardfill No. 1 which is approximately 14 acres in size. OU-12 was identified as a hardfill, rather
than a landfill, because disposal records indicated that it only received construction debris such as
wood, metal, concrete, and asphalt. An unnamed ephemeral drainage channel runs through the
center of the hardfill which carries surface water runoff from the Base storm water management
system. Storm water from taxiways, runways, and operations areas along the South Dock drain
into this ephemeral drainage. The water in the drainage channel flows south to a ponded area in
the center of the hardfill, and then southwest, around the Alert Apron, past OU-1, into Pond 001,
and ultimately off-Base.
Historical aerial photographs indicate the area has been used for dumping of construction debris'
such as wood, metal, concrete, and asphalt since the 1940s. Construction debris is visible over
portions of OU-12, although much of the former disposal area is covered by vegetation.
Disposal of hazardous materials has not been documented at OU-12; however, the area was
designated as an operable unit based on historical disposal practices at the Base.
The topography at OU-12 is characterized by a north-south unnamed, unlined ephemeral drainage
channel through the center of the hardfill which carries surface water runoff from taxiways,
runways, and other operations areas. Surface topography at OU-12 generally slopes toward the
ephemeral stream. Hardfill areas encroach upon the east bank of the drainage channel and also
serve as riprap in some places. The hardfill boundaries extend to the south, beneath the present-
day Alert Apron. The drainage channel contains wetlands which are illustrated on Figure 2-4.
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Final Record of Decision Operable Unit 12
Ellsworth Air Force Base, South Dakota
The shallow aquifer at EAFB is considered a potential drinking water source and possibly
discharges to the surface. The ground water is classified as having a beneficial use as a drinking
water supply suitabje for human consumption (ARSD Chapter 74:03:15, Groundwater Quality
Standards).
Deeper bedrock aquifers also exist beneath EAFB. These deeper aquifers are separated from the
shallow aquifer by 800 feet of low-permeability clays and silts. In the past, EAFB utilized these
deeper aquifers for its water supply. Presently, EAFB obtains its potable water from the Rapid
City Municipal Distribution System.
2.2.2 Regulatory Oversight Activities
Environmental investigation activities at EAFB were initiated by the Air Force in 1985 through an
Installation Restoration Program (IRP) Phase I Installation Assessment/Records Search and Phase
H, Confirmation/Quantification. The Phase I study, dated September, 1985, identified a total of
17 locations at EAFB where releases involving hazardous substances potentially occurred.
In Phase II, of the IRP investigation, field activities included soil vapor surveys, geophysical
surveys, surface and subsurface soil sampling, ground-water sampling, ground-water hydrologic
testing, and ecological investigations.
On August 30, 1990 (55 Federal Register 35509), EAFB was listed on the U.S. EPA's National
Priorities List (NPL). A Federal Facilities Agreement (FFA) was signed in January 1992 by the
Air Force, the U.S. Environmental Protection Agency (EPA), and the State of South Dakota
(SDDENR) and went into effect on April 1, 1992. The FFA establishes a procedural framework
and schedule for developing, implementing, and monitoring appropriate response actions for
EAFB in accordance with the Comprehensive Environmental Response, Compensation, and
Liability Act of 1980 (CERCLA), as amended by the Superfund Amendments and
Reauthorization Act of 1986 (SARA), and the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP). It also states the oversight procedures for EPA and the State to ensure
Air Force compliance with the specific requirements. The FFA identified 11 site-specific operable
units (OUs) and a Base-wide ground-water operable unit. The Base-wide ground-water OU is
primarily used to address contaminated ground water that was not addressed during the
investigation of a site-specific OU.
Listing on the NPL and execution of the FFA required the U.S. Air Force to perform a remedial
investigation/feasibility study (RI/FS) to investigate the 12 operable units. In 1993 and 1994, an
extensive RI field program was conducted to characterize conditions at OU-12. The program
included: drilling and of boreholes, installation of monitoring wells, geotechnical analysis of soil
samples, ecological evaluation, assessment of human health risks, and review and compilation of
previous IRP investigations. Collection and laboratory analysis of soil, ground-water, surface
water, and sediment samples were included in the RI field program.
2.3 HIGHLIGHTS OF COMMUNITY PARTICIPATION
Community relations activities that have taken place at EAFB to date include:
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FFA process. After preparation of the FFA by the USAF, EPA, and SDDENR, the
document was published for comment. The FFA became effective April 1, 1992.
Administrative Record. An Administrative Record for information was established in
Building 8203 at EAFB. The Administrative Record contains information used to
support USAF decision-making. All the documents in the Administrative Record are
available to the public.
Information repositories. An Administrative Record outline is located at the Rapid City
Library (public repository).
Community Relations Plan (CRT). The CRP was prepared and has been accepted by
EPA and the State of South Dakota and is currently being carried out. An update to this
plan will be prepared in 1996.
Restoration Advisory Board (RAB). The RAB has been formed to facilitate public
input in the cleanup and meets quarterly. In addition to USAF, EPA, and South Dakota
oversight personnel, the RAB includes community leaders and local representatives from
the surrounding area.
Mailing list. A mailing list of all interested parties in the community is maintained by
EAFB and updated regularly.
Fact sheet. A fact sheet describing the status of the IRP at EAFB was distributed to the
mailing list addressees in 1992.
Open house. An informational meeting on the status of the IRP and other environmental
efforts at EAFB was held on May 6, 1993. An open house was held November 16, 1995
in conjunction with the Restoration Advisory Board meeting. Information on the status
of environmental efforts at EAFB was provided at the open house.
Newspaper articles. Articles have been written for the base newspaper regarding ERP
activity.
Proposed Plan. The proposed plan on this action was distributed to the mailing list
addressees for their comments.
A public comment period was held from December 28, 1995 to January 27, 1996, and a public
meeting was held on January 11, 1996. At this meeting, representatives from EAFB answered
questions about the remedial action. A response to the comments received during this period is
included in the Responsiveness Summary, which is part of this Record of Decision (ROD).
This ROD is based on the contents of the Administrative Record for OU-12, in accordance with
the CERCLA, as amended by SARA, and the NCP. The RI/FS reports and the Proposed Plan for
OU-12 provide information about OU-12 and the selected remedy. These documents are available
at the Information Repositories at EAFB and the Rapid City Public Library.
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Final Record of Decision Operable Unit 12
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2.4 SCOPE AND ROLE OF RESPONSE ACTION
The FFA identified 11 site-specific area operable units (OUs) as well as a Base-wide
ground-water operable unit. The 12 operable units are identified as follows:
OU-1 Fire Protection Training Area
OU-2 Landfills Nos. 1 and 6
OU-3 Landfill No. 2
OU-4 Landfill No. 3
OU-5 Landfill No. 4
OU-6 Landfill No. 5
OU-7 Weapons Storage Area
OU-8 Explosive Ordnance Disposal Area (Pramitol Spill)
OU-9 Old Auto Hobby Shop Area
OU-10 North Hangar Complex
OU-11 Base-wide Ground Water
OU-12 Hardfill No. 1
This ROD is to document the selected remedy for the preferred remedial action (RA) at OU-12
and is the ninth ROD for EAFB. The remedial action objectives (RAOs) are to reduce the
potential risks posed by contaminants in surface soils and to reduce the mobility of potential
contaminants in the hardfill through containment.
The development of alternatives for OU-12 was conducted under EPA's Presumptive Remedies
Approach [Presumptive Remedies: Policy and Procedures (OSWER Directive 9355.0-47FS);
Presumptive Remedy for CERCLA Municipal Landfill Sites (OSWER Directive 9355.0-49FS);.
By using this approach, selection of an alternative for remediation is streamlined by using
preferred technologies based on historical patterns of remedy selection and EPA's scientific and
engineering evaluation of performance data on technology implementation.
The presumptive remedy stipulates containment as the appropriate remedy for landfills. The
response action, containment by capping, would remove risk associated with the ingestion, dermal
contact, and inhalation exposure pathways. The area of attainment defines the area over which
preliminary remediation goals would be achieved, and is based on the RAOs. The area of
attainment would include hardfill areas not meeting appropriate closure standards. The remedy
does not address leachate remediation since identified wastes placed in the hardfill do not typify
that which would normally be associated with leachate production. Ground-water monitoring will
identify whether leachate is being produced in the future.
2.5 SITE CHARACTERISTICS
This section describes the presence and distribution of contaminants at OU-12 as a result of past
activities.
2.5.1 Soils
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Ellsworth Air Force Base. South Dakota
Volatile Organic Compounds (VOCs)
Five different VOCs were reported in the 1995 RI surface and subsurface soil samples from
OU-12. The maximum reported value was 47 micrograms per kilogram (ug/kg) of toluene in a
sample collected from the southern edge of OU-12.
Jet Fuel
Total petroleum hydrocarbons (TPH) as jet fuel was reported in 9 of 18 surface soil samples at a
maximum concentration of 2,500 milligrams per kilogram (mg/kg). Jet fuel was reported in
surface soil samples collected from both within and outside the identified hardfill areas. Jet fuel
was not reported in capillary fringe samples, but was reported in three other subsurface samples at
a maximum concentration of 260 ug/kg.
Semi-Volatile Organic Compounds (SVOCs)
Twenty-three separate SVOCs were reported in surface soil samples collected during the RI at
OU-12. The majority of the SVOCs was fuel related polycyclic aromatic hydrocarbon
compounds (PAHs). Many of the reported SVOCs are considered to be related to Basewide
activities associated with aircraft operations and not with disposal practices at the hardfill. The
highest concentrations of surface-soil SVOCs were, however, reported in soil samples collected
from near the soil piles and fill areas.
Pesticides
Two pesticides were reported in surface soil samples and two pesticides were reported in
subsurface soil samples from OU-12. The maximum reported pesticide concentration was
33 ug/kg of p,p'-DDD in a surface soil sample. The reported concentrations are typical of urban
and agricultural areas and are considered to be the result of past pest-management practices at
EAFB.
Inorganic Constituents
Analytical results of surface soil samples indicated that the highest number of inorganic
constituents above background were reported in a sample collected west of the soil piles. The
largest number of these inorganic constituents was found in samples collected in the central-
eastern portion of OU-12. The mean concentrations of some inorganic constituents in subsurface
soil samples are 240 mg/kg for barium, 18.3 mg/kg for lead, 1563 mg/kg for manganese, and 21
mg/kg for arsenic. There appears to be no pattern in the distribution of the reported inorganic
constituents. The random distribution suggests the natural occurrence of these compounds in the
soil. However, these inorganic constituents were still evaluated in the risk assessment due to the
uncertainty associated with the disposal practices.
2.5.2 Sediment
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Organic Contaminants
Acetone was reported in one sediment sample at a concentration of 430 ug/kg, and carbon
disulfide was reported in two samples at a maximum concentration of 35 ng/kg. Total petroleum
hydrocarbons was reported in each of the seven sediment samples, at a maximum concentration
of 20,000 ug/kg. Twenty-two SVOCs were reported in the OU-12 sediment samples, including
PAHs, carbazole, 4-methylphenol, dibenzofuran, and phthalates. The highest reported SVOC
concentrations were reported in the upgradient sample. The exact source of SVOCs in the
sediment is not known, but impacts from upstream of OU-12 are considered likely. Pesticides
were reported in each of the sediment samples. No discernible pattern was observed, and the
source of the reported pesticides is considered to be Basewide pest management practices.
Inorganic Contaminants
Nineteen of the twenty inorganics analyzed for were reported in the six sediment samples from
OU-12. The mean concentrations of some inorganic compounds detected in sediment samples are
384 mg/kg for barium, 149 mg/kg for lead, 685 mg/kg for manganese, and 15.4 mg/kg for
arsenic. There does not appear to be any pattern to the distribution of the reported inorganic
contaminants.
2.5.3 Ground Water
Ground-water sample results do not indicate any discernable ground-water contamination at
OU-12. Low levels of certain contaminants were intermittently detected in ground-water samples
from isolated areas.
Organic Contaminants
Acetone was reported in three often ground-water samples at concentrations ranging from
11 micrograms per liter (ug/L) to 17 ug/L. Trichloroethene (TCE) was reported in two often
samples at a maximum concentration of 7.0 ug/L. Total-1,2-dichloroethene (DCE) was reported
in one sample at a concentration of 19.0 ug/L, and 1,1,1-trichloroethane (TCA) was reported in
one sample at an estimated value below the sample quantitation limit (SQL) of 0.40 ug/L. Two
SVOCs (naphthalene and bis (2-ethylhexyl)phthalate) were reported in OU-12 ground-water
samples. Five different pesticides were reported in the OU-12 ground-water samples. With the
exception of one sample collected east of a hardfill area on the southern end of the OU, reported
pesticides are associated with samples from wells located upgradient of OU-12 hardfill areas.
Inorganic Contaminants
Twelve inorganic constituents were reported at concentrations greater than the background range.
Nickel and Antimony were the only inorganic constituents reported above the Safe Drinking
Water Act Maximum Contaminant Level (MCL) of 100 ug/L and 6 ug/L, respectively. The
inorganic constituents detected in ground water are considered to be the result of natural
variations in geologic deposits because they were reported at levels consistent with background.
2.5.4 Surface Water
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Organic Contaminants
Four VOCs, benzene, ethylbenzene, toluene, and xylene, were reported in surface water samples
from OU-12. The exact source of the reported VOC is not known, but reported values are
indicative of non-point source runoff from the industrial portion of the Base, taxiways, and aprons
upstream of OU-12. Total petroleum hydrocarbons as jet fuel was reported in two of the six
surface water samples at a maximum concentration of 180 ug/L. These two surface water
samples were taken from locations further upstream than the other four surface water samples.
The jet fuel in surface water samples is considered to be a result of discharge from the Base
operation area upstream of OU-12. Eight SVOCs and one tentatively identified compound (TIC)
were reported in surface water samples. The source of reported SVOCs is considered to be
runoff from Base operations areas north of OU-12. One pesticide was reported in each of the
three samples which were taken upstream from the hardfill areas. Reported concentrations are
consistent with what would be expected with past pest-management practices at EAFB.
Inorganic Contaminants
Three analytes, arsenic, iron, and manganese, were reported at concentrations exceeding Federal
Ambient Water Quality Criteria (FAWQC). The source of the reported inorganics in surface
water is considered to be from a combination of naturally-occurring geologic deposits and Base
operation areas upstream of OU-12.
2.6 SITE RISK SUMMARY
Human Health Risks
Risk Assessment Process .
The assessment of human health risks for this OU considered the following topics:
(1) Contaminants of concern (COCs) in ground-water, surface water, sediment, and soil samples
taken at OU-12;
(2) Current and future land-use conditions;
(3) Potential environmental pathways by which populations might be exposed;
(4) Estimated exposure point concentrations of COCs;
(5) Estimated intake levels of the COCs;
(6) Toxicity of the COCs; and
(7) Uncertainties in the assessments of exposure, toxicity, and general risks.
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Final Record of Decision Operable Unit 12
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Noncarcinogenic and carcinogenic risks were calculated for the following five potential exposure
groups:
(1) Current EAFB maintenance personnel mowing grass on-site;
(2) The future child/adult living on-site who ingests or has dermal contact with surface soil;
(3) The future adult living on-site who ingests and showers with shallow ground water;
(4) Future adolescents who are exposed to surface water and sediment through wading; and,
(5) Future adult construction workers who excavate on-site for building residences.
A quantitative risk assessment was performed for the ground water, soil, sediment, and air. The
risk assessment evaluated potential effects on human health posed by exposure to contaminants
within OU-12. Carcinogenic risks were estimated as the incremental probability of an individual
developing cancer over a lifetime as a result of exposure to a potential cancer-causing chemical.
The acceptable risk range expressed as a probability is one cancer incident in ten-thousand people
to one cancer incident in a million people. This level of risk is also denoted by 1 x 10"4 to 1 x 10"*.
Risks within the acceptable risk range may or may not warrant remedial action depending upon
site-specific circumstances. Risks below this range cannot be differentiated from the background
occurrence of cancer in human populations.
Noncarcinogenic health risks are evaluated using a hazard index (Ffl). If the hazard index is less
than or equal to one, the contaminant concentration is considered an acceptable level and
generally assumes that the human population may be exposed to it during a 30-year period
without adverse health effects. Risks calculated in a risk assessment are potential risks and are
excess (i.e., over background) risks due to exposure from contaminants at the OU.
Risk Assessment Results
The risk assessment for OU-12 indicated that the total carcinogenic site risk is within the
acceptable risk range for the residential scenario and is less than 1X10"* for industrial scenario.
The majority of the total carcinogenic site risk for the residential scenario is from exposure to
surface soil contaminants from within the hardfill. The noncarcinogenic His are below the
reasonable maximum exposures (RME) of 9 x 10"5 for current industrial land use and 1 x 10"1 for
future residential land use. The average His for both current industrial land use and future
residential land use were 3 x 10"6 and 5 x 10"2, respectively. However, due to the heterogeneity of
the hardfill contents, great uncertainty is associated with the calculated risk values.
Arsenic and benzo(a)pyrene in the sediment of the drainage areas also contributed to the total site
risk. Based on the risk assessment (risk calculated for sediment is 3 x 10"6), and other factors
such as maximum concentrations, distribution, detection frequency, etc., remediation is not
warranted for sediment at OU-12.
The risk to human health from the ingestion and use of the shallow ground water is 2 X 10"6. This
is on the lower end of the acceptable risk range. Based on this calculated acceptable risk and low
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concentrations of contaminants detected in ground-water samples, remediation is not warranted
for ground water.
The calculated risk level for the surface water at OU-12 is 8 X 10'8, which is below the acceptable
risk range. Remediation is not warranted for surface water as part of OU-12.
Risk Assessment Conclusions
Remedial action is warranted for the hardfill based on the potential risk to human health from
future releases of hazardous substances from the hardfill. Contaminants in the hardfill may leach
downward to contaminate the underlying ground water. Off-Base residents may then ingest or
come in contact with the contaminated ground water. Also, the surface of the hardfill may erode,
thus exposing off-Base residents to contaminants in both surface water and air.
Due to the potential heterogeneity of the waste materials present within the hardfill, a complete
characterization of waste materials present was not possible during the RI. This adds a degree of
uncertainty to the risk assessment for the hardfill contents.
Rather than attempting to fully characterize hardfill contents and gain more certainty in the risk
assessment, the Air Force utilized guidance developed by EPA titled Presumptive Remedy for
CERCLA Municipal Landfill Sites (OSWER Directive 9355.0-49FS). The presumptive remedy
for landfills is containment (capping) of landfill contents. Using the presumptive remedy strategy,
a quantitative risk assessment is not necessary to evaluate whether the containment remedy
addresses all exposure pathways and contaminants potentially associated with a landfill. Rather,
all potential exposure pathways can be identified using the conceptual site model and compared to
the pathways addressed by the presumptive remedy. Containment of the landfill contents
addresses exposure pathways and risks normally associated with landfills. The contaminant
exposure pathways for the potential risks associated with the hardfill contents at OU-12 include
(1) direct physical contact with the hardfill contents and (2) consumption or contact with ground
water that may become contaminated, (3) consumption or contact with potentially contaminated
surface water, and (4) ingestion of potentially contaminated sediment in the drainage channel
which bisects OU-12.
Actual or threatened releases of hazardous substances from OU-12, if not addressed by
implementing the response action selected in this Record of Decision (ROD), may present an
imminent and substantial endangerment to public health, welfare, and the environment.
. Ecological Risks
An ecological risk evaluation of OU-12 was based on a combination of data and literature
reviews, field and laboratory analyses, analyte evaluation and screening, and preliminary risk
screening. The ecological risk assessment was performed in three phases, or tiers. Tier I was a
screening-level risk assessment. Tiers II and III were progressively more detailed risk
assessments. The pertinent findings are summarized below.
OU-12 presents a mixture of disturbed habitat, such as the exposed hardfill area and associated
weedy vegetation, and attractive habitat including grassland, wetlands, and some cottonwood and
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willow trees. In spite of the disturbance, including the close proximity of OU-12 to the runway, a
variety of ecological receptors could be attracted to the area for foraging and possibly nesting.
Rare, threatened, or endangered species could also utilize OU-12 for foraging and possibly
nesting. There were no rare, threatened or endangered animal or plant species identified at OU-
12. However, rare, threatened, or endangered species may utilize OU-12 as a transient habitat.
Due to the low levels of contaminant concentrations, the contaminants do not pose an
unacceptable risk to these species. In addition, the limited contact these species would have with
the OU-12 area ensures unacceptable risk to a single individual will not occur.
Terrestrial vegetation and soil fauna communities differ between OU-12 and a reference area.
Influence of chemicals detected in the soil could be neither confirmed or denied, based on the
data. This prompted movement of the OU from Tier I to Tier II ecological evaluation.
Findings of the OU-12 RI indicate that the contaminants at OU-12 are not affecting species
identified in the vicinity of EAFB on a population basis. However, screening of chemical
concentrations in surface water, sediment, and surface soil, and sample-by-sample examination of
the database, identified a number of metals and organic compounds present at sufficient
concentrations to warrant a Tier HI risk assessment. The Tier III risk assessment will be a Base-
wide ecological risk assessment to be conducted as part of OU-11.
2.7 DESCRIPTION OF ALTERNATIVES
Presumptive Remedy for CERCLA Municipal Landfill Sites, (OSWER Directive 9355.3-11FS)
was the basis for the abbreviated feasibility study (FS). The OSWER directive established
containment of the contamination within the landfill as the presumptive remedy for municipal
landfills.
Although not specifically identified as a municipal landfill, OU-12 exhibits characteristics that
make this presumptive remedy applicable. The hardfill contents at OU-12 do not have the
characteristics to produce any significant leachate or gas, although detectable levels of methane
gas was identified in one area of OU-12. The risk assessment did not identify the ground water as
a pathway of concern. Even though the hardfill contents were not identified as a source of
unacceptable risk to human health, the heterogeneity of the hardfill contents causes uncertainties
in the risk assessment. Therefore, the presumptive remedy focuses on containment of the hardfill
contents.
. Alternative 1 - No Action
The no-action alternative represents the baseline condition at OU-12 and refers to
taking no action at OU-12, although existing maintenance of the site (mowing)
would be continued.
Alternative 2 - Institutional Controls
Institutional controls (access restrictions and deed restrictions).
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Monitoring of ground water, and sediment.
Long-term maintenance of existing soil cover.
Alternative 3 - Capping
Placing a soil cover capable of sustaining vegetation on the area of attainment at
HardfillNo 1.
Long-term maintenance of soil cover.
Monitoring and institutional controls as stated in Alternative No. 2.
2.8 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
The analysis of alternatives coupled with the use of the presumptive remedy combine for a
narrower range of feasible approaches to address remedial activities at OU-12.
The remedial action objectives for OU-12 are as follows:
Hardfill
Prevent ingestion and dermal contact with hardfill contents.
Reduce the mobility of potential contaminants in the hardfill.
Control surface water runoff and erosion of the hardfill cover.
The area of attainment is defined as the area which will achieve the remedial action objectives
after remediation is completed. The area of attainment for OU-12 is the extent of the hardfill
areas, approximately 14 acres (Figure 2-5).
Pursuant to Section 300.430(e)(9)(iii) of the EPA's revised NCP, the remedial action to be
implemented should be selected based upon consideration of nine evaluation criteria. These
criteria are as follows:
1. Overall protection of human health and environment.
2. Compliance with applicable or relevant and appropriate requirements (ARARs).
3. Long-term effectiveness and permanence.
4. Reduction of toxicity, mobility, or volume of contamination.
5. Short-term effectiveness.
6. Implementability.
7. Cost.
8. State acceptance.
9. Community acceptance.
The following sections provide a brief review and comparison of the remedial alternatives
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according to EPA's evaluation criteria.
2.8.1 Overall Protection of Human Health and the Environment
The assessment of this criterion considers how the alternatives achieve and maintain protection of
human health and the environment.
Alternative 1 (no action) does nothing to reduce risk at OU-12. Alternative 2 (institutional
controls) provides for maintenance of non-vegetated areas. Access restrictions would reduce risk
by reducing exposure. Alternative 3 (soil cover) provides containment of the hardfill contents.
This would eliminate risk associated with exposure to potential contaminants in the landfill and
the future risk associated with potentially contaminated ground water.
2.8.2 Compliance with ARARs
Alternatives are assessed under this criterion in terms of compliance with ARARs. Applicable
requirements include cleanup standards, standards of control and other substantive environmental
protection requirements, criteria, or limitations promulgated under Federal or state laws that
specifically address a hazardous substance, pollutant, contaminant, remedial action, location or
other circumstances at a CERCLA site.
Relevant and appropriate requirements address problems or situations sufficiently similar to those
encountered at a CERCLA site that their use is well suited to the environmental and technical
factors at a particular site. The determination of "relevant and appropriate" emphasizes the
similarity and appropriateness of the requirement to a site. ARARs are grouped into these three
categories:
Chemical-Specific ARARs are health or risk-based numerical values or
methodologies which, when applied to site-specific conditions, result in
establishment of the amount or concentration that may be found in, or discharged
to, the environment.
Location-Specific ARARs restrict the concentration of hazardous substances or
the conduct of activities solely because they are in specific locations such as flood
plains, wetlands, historic places, and sensitive ecosystems or habitats.
Action-Specific ARARs are usually technology or activity-based requirements or
limitations on actions taken with respect to hazardous wastes.
A summary evaluation of Federal and State ARARs pertinent to this remedial action is provided in
Table 2-1 at the end of Section 2.0 and a narrative discussion of compliance with ARARs is
provided below for the alternatives considered.
Alternative 1 (No Action):
The No Action alternative does not comply with State of South Dakota Solid Waste Management
Regulations (ARSD Article 74:27). The OU-12 RI concluded that ground water has not been
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adversely impacted and was not a potential transport pathway; therefore, ground water ARARs at
the OU are met. Alternative 1 does not meet the remedial action objectives for OU-12. An
action would not be taken to prevent human contact with surface-soil contaminants and potential
contaminants within the hardfill may leach to the ground water.
Alternative 2 (Institutional Controls):
Alternative 2 does not comply with State of South Dakota Solid Waste Management Regulations.
The OU-12 RI concluded that ground water has not been adversely affected and was not a
potential transport pathway; therefore, ground water ARARs at the OU are met. Alternative 2
does not meet the remedial action objectives for OU-12.
Alternative 3 (Capping):
Alternative 3 will meet State of South Dakota Solid Waste Management Regulations for the
disposal of solid waste by providing containment of hardfill contents, access/development
restrictions, and long-term monitoring. Additional cover material will be added under this
alternative to achieve compliance with the State requirements. The State is Federally authorized
for the Resource Conservation and Recovery Act (RCRA) Subtitle D Municipal Solid Waste
Program (8 October 1993, 58 FR 52486). The resulting cover will also ensure continued
compliance with the Safe Drinking Water Act Maximum Contaminant Levels (MCLs) by
preventing the downward transport of contaminants to the ground water.
Section 404 of the Clean Water Act (CWA) regulates the discharge of dredge or fill material into
waters of the United States. Section 404 is implemented through regulations set forth in 33 CFR
parts 320 through 330 and 40 CFR Part 230. To fully cover the hardfill, the wetlands near the
ephemeral stream may be filled. This may adversely affect a water of the United States. The
Executive Order on Protection of Wetlands (E.O. No. 11, 990) requires Federal Agencies to
avoid, to the extent possible, the adverse impacts associated with the destruction or loss of
wetlands if a practical alternative exists. If the discharge of fill material into a water body cannot
be avoided, the use of appropriate and practicable mitigation measures to minimize the adverse
impact to the aquatic ecosystem will be required. Appropriate mitigation measures may be
implemented during the remedial action. If wetlands at OU-12 will be adversely effected, an
alternate area will be chosen for construction of a new wetland for the mitigation purposes. This
ARAR will be met.
Implementation of the presumptive remedy (containment by capping) strategy for landfills has
been shown by EPA to meet the remedial action objectives by preventing direct contact with
hardfill contents and ingestion of surface soil and sediment.
2.8.3 Long-Term Effectiveness and Permanence
The assessment of this criterion considered the long-term effectiveness of alternatives in
maintaining protection of human health and the environment after response action objectives have
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been met.
Alternative 1 would not provide additional effectiveness or permanence in reducing the potential
for direct contact or ingestion of the surface soil or sediments. No further controls for the OU
would be developed under this alternative.
Alternative 2 would provide for increased effectiveness of access restrictions (in addition to the
general EAFB access restrictions). Additionally, maintaining vegetation on the hardfill would
reduce erosion potential. Permanency and reliability of these controls would be enhanced through
long-term monitoring and maintenance of the OU. Uncertainties exist for the ability to provide
long-term access restrictions.
Alternative 3 would offer the highest level of long-term effectiveness. The earthen cover would
reduce potential future risks to human health. Erosion would be limited by the development and
maintenance of a vegetated area. Upon completion, long-term maintenance of the cover and
monitoring of ground water would be provided. Future land uses will be allowed if the integrity
of the hardfill cover is not compromised.
2.8.4 Reduction of Toxicity, Mobility, and Volume Through Treatment
The assessment of this criterion involves considering the anticipated performance of specific
treatment technologies an alternative may employ.
Alternative 1 would not provide for the reduction of toxicity, mobility, or volume of potential
contaminants within the hardfill. Alternative 2 would reduce the mobility of contaminants in
surface soils through long-term erosion maintenance of existing cover soils. Alternative 3 does
not use treatment technologies, but reduces the mobility of potential contaminants in the hardfill
through containment.
2.8.5 Short-Term Effectiveness
The assessment of this criterion considers the effectiveness of alternatives in maintaining
protection of human health and the environment during the construction of a remedy until
response action objectives have been met.
It is not anticipated that the proposed alternatives would significantly impact worker or
community health and safety during the implementation period. Alternatives 2 and 3 may impact
community and worker health and safety through dust emissions during the initial construction
phase. The impact could be minimized through dust mitigation.
Alternatives 2 and 3 may create a short-term increase in risk during remedial activities due to the
inhalation exposure pathway. Disturbances of surface soil through earthwork and soil disturbance
would result in exposure to workers. Dust mitigation during these activities would minimize this
potential impact. Alternative 3 would present the potential for temporarily increasing the
opportunity for erosion of the disturbed soil, although erosion and sediment control measures will
help to minimize this adverse impact.
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Final Record of Decision Operable Unit 12
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2.8.6 Implementability
The assessment of this criterion considers the administrative and technical feasibility of
implementing the alternatives and the availability of necessary goods and services for
implementation of the response action.
Alternative 1 would not be difficult to implement since, aside from long-term monitoring, no
further action would be undertaken.
Alternative 2 requires no special or unique activities and could be implemented using locally
available materials and contractors. Long-term monitoring would indicate whether additional
action would need to be implemented in the future.
Alternative 3 could be implemented with standard construction equipment, materials, and
methods. The availability of an on- or off-Base supply of cover material will require further
consideration during the remedial design analysis. Wetlands mitigation (as a result of drainage
modifications) could also be implemented with standard construction equipment, materials, and
methods. Land use (or deed) restrictions can be implemented at EAFB by various administrative
means.
2.8.7 Cost
A summary of the costs for each alternative is presented on the following page.
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Final Record of Decision Operable Unit 12
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Alternative No. 1 (No Action)
Total Capital Costs
Total Annual (Sampling/Analysis) Costs
30-Year Present Value for Annual Costs
Annual Cost = $0
Years = 30
Discount Rate = 5%
TOTAL 30-Year Present Value
$0
$0
$0
50
Alternative No. 2 (Institutional Controls)
Total Capital Costs
Total Annual (Sampling/ Analysis/O&M) Costs Years 1-5
Total Annual (Sampling/Analysis/O&M) Costs Years 6-30
30-Year Present Value for Annual Costs
Annual Cost Year 1-5 = $130,500
Annual Cost Year 6-30 = $66,700
Years = 30
Discount Rate = 5%
TOTAL 30-Year Present Value
$180,000
$130,500
$66,700
$1,301,500
51,481,500
Alternative No. 3 (Capping)
Total Capital Costs
Total Annual (Sampling/Analysis/O&M) Costs Years 1-5
Total Annual (Sampling/Analysis/O&M) Costs Years 6-30
30-Year Present Value for Annual Costs
Annual Cost Year 1-5 = $130,500
Annual Cost Year 6-30 = $66,700
, Years = 30
Discount Rate = 5%
TOTAL 30- Year Present Value
$1,497,500
$130,500
$66,700
$1,301,500
52,799,000
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2.8.8 State Acceptance - - ._.
The assessment of this criterion considered the State's preferences for or concerns about the
alternatives.
The State concurs with the selected remedy. The State provided comments on the remedial
investigation, feasibility study, Proposed Plan, and this ROD. After incorporating adequate
responses to the comments into the respective documents, the State concurred with the remedy.
2.8.9 Community Acceptance
Comments offered by the public were used to assess the community acceptance of the proposed
alternative. The community expressed its concerns about the selected remedy during the public
comment period. The questions and concerns of the community are discussed in detail in the
Responsiveness Summary, which is Appendix B of this ROD.
2.9 SELECTED ALTERNATIVE
Based on the requirements of CERCLA, comparative analysis of the nine criteria, public
comments, and in consultation with EPA and the State, the Air Force has determined that the
selected alternative is Alternative 3, Capping. This alternative includes institutional controls in
conjunction with physical modification of the OU to reduce potential risk. Five-year reviews of
the remedy will be required because potential contaminants will remain at OU-12 following
completion of remedial action. Major components of Alternative 3 are:
Install an earth cover over the area of attainment at Hardfill No 1.
Institutional controls to prevent future use of the area for residential use and/or
limiting its use to industrial uses.
Developing a long-term monitoring and maintenance plan for the hardfill.
Each of these items is discussed below.
Installation of Soil Cover
An earthen cover over will be placed over Hardfill No. 1 (approximately 14 acres). Cover will be
graded and contoured to maintain stability and route surface-water runoff away from previously
active fill areas and prevent ponding of the water. The cover will be vegetated to enhance
evapotranspiration and reduce infiltration and soil erosion. A pre-design study will be conducted
to examine the need for landfill gas control measures, and evaluate the need for erosion control
measures along the stream adjacent to the hardfill areas.
If the discharge of fill material into a water body cannot be avoided, the use of appropriate and
practicable mitigation measures to minimize the adverse impact to the aquatic ecosystem will be
required. Appropriate mitigation measures may be implemented during the remedial action. If
lining or filling of the drainage channel results in adverse impacts to wetlands at OU-12, an
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Final Record of Decision Operable Unit 12
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alternate area will be chosen for construction of a new wetland for the mitigation purposes.
Institutional Controls
Institutional controls would be implemented to prevent human exposure to contaminated soil and
ground water. These controls will include: (1) issuing a continuing order by the Installation
Commander to restrict access to the hardfill and to restrict or control temporary construction
activities unless proper protective equipment is worn; (2) filing a notice with the State of South
Dakota to recommend denial of water rights permit applications to install ground-water wells
within the hardfill boundary and any area which may be affected by potential contaminants within
the landfill; (3) filing a notice to the deed detailing the restrictions of the continuing order and
ground-water well restrictions; and (4) a covenant to the deed in the event of property transfer.
The continuing order would be issued by the Installation Commander to restrict access to or
disturbance of the hardfill as long as Ellsworth AFB owns the property. Specifically, it would:
Restrict or place limitations on the installation of any new underground utilities or other
construction activities in the area of the hardfill, thus preventing accidental exposures to
construction workers.
Provide for the use of proper protective equipment, in the event that access through the
hardfill cover is required.
Require that the integrity of the hardfill cover be maintained. Limit future land uses to
non-intrusive activities only. Maintenance of the hardfill will require development of
standard operating procedures (SOPs) to provide for inspections and repairs. To assist
with the institutional controls, a fence may be placed around the hardfill and authorized
personnel would have access through a locked gate. Access would only be allowed to
perform hardfill monitoring and maintenance activities. Warning signs would be posted at
the hardfill to deter unauthorized access.
The continuing order also would mandate that, if the hardfill cover was ever removed or
breached, the area of attainment would be re-evaluated to determine the need for a replacement
cap or other remedial action.
Continuing order requirements will be in effect as long as the property is owned by
Ellsworth AFB. In the case of the sale or transfer of property within OU-12 by the United States
to any other person or entity, the Air Force will place covenants in the deed, which will restrict
access and prohibit disturbance of contaminated soils or the remedial action without approval of
the United States. These covenants will be in effect until removed upon agreement of the State of
South Dakota, the U.S. Environmental Protection Agency, and the U.S. Air Force or their
successors in interest. The Air Force will also include in the deed the covenants required by
section 120(h)(3) of the Comprehensive Environmental Response, Compensation and Liability
Act (CERCLA), which include (1) a warranty that the United States will conduct any remedial
action found to be required by law after the date of the transfer; (2) a right of access in behalf of
EPA and the Air Force or their successors in interest to the property to participate in any
response or corrective action that might be required after the date of transfer. The right of access
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Final Record of Decision Operable Unit 12
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referenced in the preceding sentence shall include the State of South Dakota for purposes of
conducting or. participating in any response or corrective action that might be required after the
date of transfer.
Long-Term Monitoring and Maintenance
A maintenance program would be established to ensure the long-term integrity hardfill conditions
remedy would be maintained. The maintenance program would include development of standard
operating procedures (SOPs) to provide for inspections, repairs, and general maintenance of the
hardfill.
A long-term monitoring program will be developed and implemented during remedial action and
is subject to approval of both EPA and SDDENR. Contaminant concentrations in the sediment
and ground water will be monitored to evaluate the effectiveness of the hardfill cover and to
determine if ground-water contaminants have been transported beyond the hardfill boundaries.
This alternative will meet the remedial action objectives and reduce the potential risk for OU-12
by reducing the mobility of potential contaminants in the hardfill. This will be achieved by the
construction of the hardfill cover and maintenance and possible modification of drainage channel.
This alternative meets the statutory requirements of Section 121 of CERCLA as amended by
SARA. These statutory requirements include protectiveness of human health and the environment,
compliance with ARARs, cost effectiveness, and use of permanent solutions and alternative
treatment technologies to the extent practicable.
The statutory preference for treatment is not satisfied; however, the selected alternative is the
presumptive remedy (containment) developed by EPA for landfills.
Alternative 3 would limit exposure of hardfill materials, and contaminants present in surface soils
and sediment at the OU, to humans, wildlife and the environment. Therefore the selected
alternative will be protective of human health and the environment and will comply with ARARs.
2.10 STATUTORY DETERMINATIONS
The selected remedy meets the statutory requirements of CERCLA as amended by SARA. These
requirements include protection of human health and the environment, compliance with ARARs,
cost effectiveness, utilization of permanent solutions and alternative treatment technologies to the
extent practicable. Containment, by definition, does not attempt to reduce the toxicity or volume
of potentially hazardous materials; rather, it reduces the likelihood of exposure to these materials
by preventing the movement of materials beyond the boundaries of the hardfill and preventing
direct contact with hardfill materials. The selected remedy represents the best balance of tradeoffs
among the alternatives considered, with respect to pertinent criteria, given the scope of the action.
The manner in which the selected remedy meets each of these requirements is discussed in the
sections below.
2.10.1 Protection of Human Health and the Environment
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Final Record of Decision Operable Unit 12
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The selected remedy addresses health and environmental issues that were identified in the OU-12
RI report. Specifically, the capping alternative:
Eliminates exposure to hardfill contents by installing an earthen cap.
Reduces the potential infiltration of contaminants to the ground water.
Prevents unauthorized access to the area by installing a perimeter fence and restricted
access signs.
Provides for long-term monitoring of ground water and sediment to identify potential
future risks associated with OU-12.
2.10.2 Compliance with ARARs
Alternative 3 will meet State landfill closure requirements by providing containment of hardfill
contents, access/development restrictions and long-term monitoring. The OU-12 RI concluded
that ground water has not been adversely affected and was not a potential transport pathway;
therefore ground water ARARs at the OU are met. Wetlands adversely affected by the remedial
activities may need to be mitigated. Additional information about ARAR compliance is contained
in Section 2.8.2.
Implementation of the presumptive remedy (containment by capping) strategy for landfills has
been shown by EPA to meet the remedial action objectives by preventing direct contact with
landfill contents.
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Final Record of Decision Operable Unit 12
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2.10.3 Cost Effectiveness
The selected remedy provides overall effectiveness in reducing human health risks relative to its
costs. The presumptive remedy process insures cost-effective remedies are chosen. The chosen
hardfill cover type ensures containment of the hardfill contents. Site specific conditions were used
to determine the type of cover necessary for the hardfill. Based on the information provided
during the remedial investigation, a more costly cover would not be cost effective.
2.10.4 Utilization of Permanent Solutions and Alternative Treatment Technologies to the
Extent Possible
EPA has established that proper capping has proven effective in containing landfill contents. This
alternative provides long-term prevention of exposure to potential hardfill material, prevents
unauthorized access, and provides for long-term ground water monitoring to detect movement of
chemicals from the area. A five-year review of the selected remedy will be performed because
contaminants may be remaining within the hardfill. The review will be conducted no less often
than every five years after the signing of the ROD to ensure the remedy continues to provide
adequate protection of human health and the environment.
2.10.5 Preference for Treatment as a Principal Element
Treatment of the hardfill contents is not supported based on the findings of the remedial
investigation for OU-12. No identifiable hot spots were reported present and the risks associated
with OU-12 can be addressed by eliminating exposure to the hardfill contents by capping.
2.11 DOCUMENTATION OF SIGNIFICANT CHANGES
The selected action is the same as the preferred alternative presented in the Proposed Plan for
OU-12 remedial action. There have been no changes relative to the Proposed Plan.
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Final Record of Decision Operable Unit 12
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TABLE 2-1 EVALUATION OF FEDERAL AND STATE ARARS THAT APPLY TO OU-12, ELLSWORTH AFB, SOUTH DAKOTA
Applicable or Relevant and Appropriate Federal Standards, Requirements, Criteria and Limitations
Standard, Requirement, Criteria
or Limitation
Safe Drinking Water Act
National Primary Drinking
Water Standards
National Secondary Drinking
Water Standards
Maximum Contaminant
Level Goals
Clean Water Act
Water Quality Criteria
Criteria and Standards for
the National Pollutant
Discharge Elimination
System
Citations
42 USC 300, f, g
40CFRPart 141.60-
.63
40CFRPart 143.3
40CFR 14 1.50 and
Public Law No. 99-
330, 100 Slat. 642
(1986)
33 USC 1251-1376
40 CFR Part 131.36
40CFRPart 125.1-.3
Description
Establishes health based standards for
public water systems (maximum
contaminant levels).
Establishes aesthetic based standards
for public water systems (maximum
contaminant levels).
Establishes drinking water quality
goals set at concentrations of
unknown or anticipated adverse
health effects with an adequate
margin of safety.
Establishes criteria for water quality
based on toxicity to aquatic organisms
and human health.
Establishes criteria and standards for
technology-based requirements in
permits under the Clean Water Act.
ARARType
Chemical
Chemical
Chemical
Chemical
Chemical
Applicability to OU-12
Relevant and appropriate for
federal Class II aquifers.
Relevant and appropriate.
Relevant and appropriate.
Relevant and appropriate.
Aquifer may be a federal
Class II A (discharge to
surface water).
Relevant and appropriate.
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TABLE 2-1 EVALUATION OF FEDERAL AND STATE ARARS THAT APPLY TO OU-12, ELLSWORTH AFB, SOUTH DAKOTA
(Continued)
Standard, Requirement, Criteria
or Limitation
Citations
Description
ARARType
Applicability to OU-12
Executive Order on
Protection of Wetlands
Clean Air Act
National Primary and
Secondary Ambient Air
Quality Standards
National Emission
Standards for Hazardous
Air Pollutants
E. O. No. 11,990
40 CFR 6.302(a) &
Appendix A
40 CFR Part 50.1-.6,
.8, .9,. 11,. 12
40 CFR Part 61
Requires federal agencies to avoid, to
the extent possible, the adverse
impacts associated with the
destruction or loss of wetlands and to
avoid support of new construction in
wetlands if a practicable alternative
exists.
Establishes standard for ambient air
quality to protect public health and
welfare.
Establishes regulatory standard for
specific air pollutants.
Action/Location
Applicable. OU-12 has
wetland areas adjacent to
remediation areas.
Action
Action
Applicable. Methane
treatment may be required at
OU-12.
Applicable. Methane
treatment may be required at
OU-12.
F:\PROJ\6037885\FS\ROD12\I-'1NAL\12FNLKOD.WI'D
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April, 1996
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Final Record of Decision Operable Unit 12
Ellsworth A ir Force Base, South Dakota
TABLE 2-1 EVALUATION OF FEDERAL AND STATE ARARS THAT APPLY TO OU-12, ELLSWORTH AFB,
SOUTH DAKOTA (Continued)
Applicable or Relevant and Appropriate State Standards, Requirements, Criteria and Limitations
Standard, Requirement, Criteria
or Limitation
South Dakota Waste
Management Regulations
South Dakota Waste
Management Regulations
South Dakota Waste
Management Regulations
South Dakota Water Quality
Standards
South Dakota Ground Water
Standards
South Dakota Surface Water
Quality Standards
South Dakota Remediation
Criteria for Petroleum-
Contaminated Soils
Citations
74:26:03:04
74:27:03:11
74:27:15
74:03:04:02, 10
74:03:15
74:03:02
74:03:32
Description
Establishes requirements for disposal
of hazardous wastes in sanitary
landfills.
Defines requirements for closure of
solid waste disposal facilities.
Establishes standards for landfill
closure and post-closure monitoring.
Defines use of Box Elder Creek and
certain tributaries.
Defines ground water classifications
by beneficial use and sets chemical
standards.
Establishes surface water quality
standards.
Establishes requirements for the
remediation of soil contaminated with
petroleum products.
ARARType
Action
Action
Action
Action
Chemical
Chemical
Chemical
Applicability to OU-12
Relevant and appropriate.
Relevant and appropriate.
Relevant and appropriate.
Landfill closure imminent for
OU-12.
Relevant and appropriate.
Relevant and appropriate.
Relevant and appropriate.
Surface water exists at OU-12.
Relevant and appropriate.
F: \1>ROJ\603 7885\I?S\ROD 12WNMM 2FNLHOD. \VPD
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April. 1996
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Final Record of Decision Operable Unit 12
Ells\vorth Air Force Base, South Dakota
3.0 LIST OF ACRONYMS AND ABBREVIATIONS
ACC: Air Combat Command
AF: Air Force
AFB: Air Force Base
ARARs: Applicable or Relevant and Appropriate Requirements
CERCLA: Comprehensive Environmental Response, Compensation and Liability Act
COC: Chemicals of Concern
DNAPL: Dense non-aqueous phase liquid
EAFB: Ellsworth Air Force Base
EP: Extraction Procedure, the EPA's standard laboratory procedure for leachate
generation.
EPA: Environmental Protection Agency
FFA: Federal Facilities Agreement
FPTA: Fire Protection Training Area . .
FT A: Fire Training Area
GPR: Ground Penetrating Radar
HQ: Headquarters
IN SITU: In the original place
IRIS: Integrated Risk Information System
IRP: Installation Restoration Program
JP-4: Jet Propulsion Fuel Number Four; contains both kerosene and gasoline fractions.
LNAPL: Light Non-Aqueous Phase Liquid
MCL: Maximum Contaminant Levels
mgd: Million Gallons per Day
jig/L: Micrograms per liter
mg/L: Milligrams per liter
MSL: Mean Sea Level
NAPL: Non Aqueous Phase Liquid
NCP: National Oil and Hazardous Substances Contingency Plan
NEPA: National Environmental Policy Act
NPDES: National Pollutant Discharge Elimination System
NPDWR: National Primary Drinking Water Regulations
NPL: National Priorities List
OU: Operable Unit
O&G: Symbols for oil and grease
PAH: Polynuclear Aromatic Hydrocarbon
PCB: Polychlorinated Biphenyl; liquids used as a dielectrics in electrical equipment
F:\PROJ\6037885ttAOD12\FIXAL\12FNLROD.WPDJI\" April, 1996
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Final Record of Decision Operable Unit 12
Ellsworth Air Force Base, South Dakota
PCE: Perchloroethylene; liquids used in degreasing or paint removal.
PL: Public Law^
ppm: Parts per million by weight
RAO: Remedial Action Objective
RCRA: Resource Conservation and Recovery Act
RI/FS: Remedial Investigation/Feasibility Study
ROD Record of Decision
SARA: Superfund Amendments and Reauthorization Act
SACM: Superfund Accelerated Cleanup Model
SVOC: Semivolatile Organic Compound
TCA: 1,1,1,-tetrachloroethane
TCE: Trichloroethylene
TCL: Target Compound List
TCLP: Toxicity Characteristic Leaching Procedure
IDS: Total Dissolved Solids
TOC: Total Organic Carbon
TSD: Treatment, storage or disposal sites/methods
USAF: United States Air Force
U.S. EPA: United States Environmental Protection Agency
USD A: United States Department of Agriculture
USFWS: Unites States Fish and Wildlife Service
USGS: United States Geological Survey
VES: Vertical Electrical Sounding
VOC: Volatile Organic Compound
WQC: Water Quality Criteria
WWTP: Wastewater Treatment Plant
F:\PROJ\6037885\FS\ROD12\FINAL\12FNLROD.IVPD 3-2 April, 1996
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Final Record of Decision Operable Unit 12
Ellsworth Air Force Base, South Dakota
APPENDIX A
FIGURES
F:\PROJ\6037885\F&ROD12\FINAL\12FNLROD.WPD April. 1996
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D
O
2 O
UMNESOTA
ELLSWORTH AFB
Rapid City
Scale In Ulln
APPROXIMATE
EL-L.S WORTH
AIR FORCE BASE
ELLSWORTH AFB
RAPID OTY. SOUTH DAKOTA
AREA LOCATION MAP
ROJECT UGR
DESIGNED BY
DRAWN BY
MRG
CHECKED BY
SCALE
AS SHOWN
DATE
JUNE 94
PROJECT NO
60378.85
FIGURE:
2-1
-------
*
o
m
1200 2400
SCALE IN FEET
LEGEND
OPERABLE UNITS
OU-1 FIRE PROTECTION TRAINING
AREA (FT-01)
OU-2 LANDFILLS 1 4 6 (LF-02)
OU-3 LANDFILL 2 (LF-03)
OU-4 LANDFILL 3 (LF-04"
OU-5 LANDFILL 4 (LF-05
OU-6 LANDFILL 5 (LF-06'
OU-7 LOW LEVEL RADIATION WASTE BURIAL AREA (RW-07)
OU-B EXPLOSIVE ORDNANCE DISPOSAL AREA tc PRAMITOL SPILL
OU-9 OLD AUTO HOBBY SHOP AREA (OT-15)
OU-10 NORTH HANGAR COMPLEX (ST-19)
OU-11" BASEWIDE GROUND WATER
OU-12 HARDF1UL NO. 1
2
o: <
OQ
ELLSWORTH
AIR FORCE BASE
ELLSWORTH AFB
RAPID Cm. SOUTH DAKOTA
SITE LOCATION MAP
ROJECT MGR
DESIGNED BY
DRAWN BY
STAFF
CHECKED BY
SCALE
AS SHOWN
DATE
MAY 95
PROJECT NO
60378.85
FIGURE:
2-2
-------
\ PRIMARY
\INSTRUMENT
X RUNWAY
uuire or
ou-u STUOT AREA
V \ < ./pi
.-\: - V (f R
WATER UTIUTY
SANfTARY SEWER UTIUTY
SURFACE DRAINAGE
EXPOSED HARDFILL AREA
HISTORICAL HARDFILL AREAS
WITH VEGETATION COVER
-------
2
£
6°
Is
~
600*
800*
WETLAND SPECIES:
T - THREE-EDGE BULRUSH (Scirpus pungtra)
A - CORDGRASS (Spnrtira, pttAvnata.)
A - CATTAIL (mostly Typha. latiJUia)
O - SEDGE (Car** spp.)
D - SPIKERUSH (EUocharis maenstachya)
- GIANT BULRUSH (Scirpus validvs)
f - SANDBAR WILLOW (Salix uxigua)
D - COTTONWOOD (Populvs
- BASE BOUNDARY FENCE
NOTE: Map represents general distribution
of dominant wetland species
r:\HORIZONS\NeW\Uuai-OU\vtCl -7-4 Owe
ELLSWORTH
AIR FORCE: BASE:
ELLSWORTH AFB
PROJECT LOCATION
1993 Rl
OU-2, OU-1, tc OU-12
WETLANDS VEGETATION MAP
ROJKTUCR
DESIGNED BT
DRAWN BY
DJS
CHECKED BT
SCALE
AS SHOWN
DATE
MAR 94
PROJECT NO
60378.85
FIGURE
2-4
-------
PRIMARY
INSTRUMENT
RUNWAY
TOPOGRAPHIC ELEVATION ABOVE
MSL - CONTOUR INTERVAL-10'
VEGETATIVE SOIL COVER
HISTORICAL HARDFILL AREAS
WITH VEGETATION COVER
LOCATION OF SOIL PILE
SCALE
P
Z
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Final Record of Decision Operable Unit 12
Ellsworth Air Force Base, South Dakota
APPENDIX B
RESPONSIVENESS SUMMARY
F:\PROJ\603788S\FS\ROD12\FINAL\12FNLROD.WPD ~' April, 1996
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Final Record of Decision Operable Unit 12
Ellsworth Air Force Base, South Dakota
Responsiveness Summary
.Remedial Action at Operable Unit Twelve
Ellsworth Air Force Base, South Dakota
1. Overview
The United States Air Force (USAF) established a public comment period from December 28, 1995
to January 27, 1996 for interested parties to review and comment on remedial alternatives considered
and described in the Proposed Plan for Operable Unit Twelve (OU-12). The Proposed Plan was
prepared by the USAF in cooperation with the U.S. Environmental Protection Agency (USEPA) and
the South Dakota Department of Environment and Natural Resources (SDDENR).
The USAF also held a public meeting at 7:30 p.m. on January 11, 1996 in the 28th Bomb Wing
Auditorium at Ellsworth Air Force Base (EAFB) to outline the proposed remedy to reduce risk and
control potential hazards at the Operable Unit (OU).
The Responsiveness Summary provides a summary of comments and questions received from the
community at the public meeting and during the public comment period, as well as the USAF's
responses to public comments.
The Responsiveness Summary is organized into the following sections:
Background on Community Involvement
Summary of Comments and Questions Received During the Public Comment Period
and USAF Responses
Remedial Design/Remedial Action Concerns
Based on the requirements of CERCLA, comparative analysis of the nine criteria, public comments,
and in consultation with EPA and the State, the Air Force has determined that the selected alternative
is Alternative 3, Capping. Major components of Alternative 3 are:
Install an earth cover over the area of attainment at Hardfill No 1.
Institutional controls to prevent future use of the area for residential use and/or
limiting its use to industrial uses.
Developing a long-term monitoring and maintenance plan for the hardfill.
F:\PROJ\6037885\FSWOD12\FINAL\12FNLROD.WPD B-l April. 1996
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Final Record of Decision Operable Unit 12
Ellsworth Air Force Base, South Dakota
2. Background on Community Involvement
On August 30, 1990 EAFB was listed on the USEPA's National Priorities List (NPL). A Federal
Facilities Agreement (FFA) was signed in January 1992 by the Air Force, EPA and the State and
went into effect on April 1, 1992. The FFA establishes a procedural framework and schedule for
developing, implementing, and monitoring appropriate response actions for EAFB.
Community relations activities that have taken place at EAFB to date include:
FFA process. After preparation of the FFA by the USAF, EPA, and SDDENR, the
document was published for comment. The FFA became effective April 1, 1992.
Administrative Record. An Administrative Record for information was established
in Building 8203 at EAFB. The Administrative Record contains information used to
support USAF decision-making. All the documents in the Administrative Record are
available to the public.
Information repositories. An Administrative Record outline is located at the Rapid
City Library (public repository).
Community Relations Plan (CRP). The CRP was prepared and has been accepted
by EPA and the State of South Dakota and is Currently being carried out. An update
to this plan will be prepared in 1996.
Restoration Advisory Board (RAB). The RAB has been formed to facilitate public
input in the cleanup and meets quarterly. In addition to USAF, EPA, and South
Dakota oversight personnel, the RAB includes community leaders and local
representatives from the surrounding area.
Mailing list. A mailing list of all interested parties in the community is maintained by
EAFB and updated regularly.
Fact sheet. A fact sheet describing the status of the IRP at EAFB was distributed to
the mailing list addressees in 1992.
Open house. An informational meeting on the status of the IRP and other
environmental efforts at EAFB was held on May 6, 1993. An open house was held
November 16, 1995 in conjunction with the Restoration Advisory Board meeting.
Information on the status of environmental efforts at EAFB was provided.
Newspaper articles. Articles have been written for the base newspaper regarding IRP
activity.
F:\PROJ\6037885\FSWOD12\FINAL\12FNLROD.WPD J}-2 APnl- 1996
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Final Record of Decision Operable Unit 12
Ellsworth Air Force Base, South Dakota
The Proposed Plan for this remedial action was distributed to the mailing list addressees for their
comments and additional copies of the Proposed Plan were available at the January 11, 1996 public
meeting. A transcript of comments, questions and responses provided during the public meeting was
prepared. Base on these public meetings, there have been no key public issues with the exception of
surface water runoff from OU-12.
3. Summary of Comments and Questions Received During the Public Comment Period
and USAF Responses
Part I - Summary and Response to Local Community Concerns
Review of the written transcript of the public meeting did not indicate community objections to the
proposed remedial action. No written comments were received during the public comment period.
The majority of the comments received during the public meeting were in the form of questions about
the remedial investigation findings, the remedial action; i.e., what would be done, how it would be
done, and what effects the action might have. Representatives of the USAF were available to
provide answers to the questions and also provided an overview presentation during the meeting to
describe the proposed actions.
Part n - Comprehensive Response to Specific Technical, Legal and
Miscellaneous Questions
The comments and questions below are in the order they appear in the written transcript of the
January 11, 1996 public meeting.
Comment 1. Mayor Baldwin
Asked about whether the cost for covering the landfill could be justified for a landfill that
poses no unacceptable risk.
Response: The presumptive remedy was selected as the preferred alternative based on the
uncertainty associated with the presence of hazardous substances within the hardfill. It
is not practical to determine the exact type and quatity of contaminants within the
hardfill; the cost of such an investigation would be prohibitive. Narrowing scope of
investigation allowed the Air Force to save money up-front. The soil cover is an
economical type of cover which permits the Air Force to achieve a great degree of
confidence that the public health and safety is being protected. The cover would also
prevent future releases of unidentified contaminants from within the hardfill to the
underlying ground water. If the ground water were to become contaminanted, a large
amount of money would be needed for the ground-water remediation, similar to the
money being spent for the ground-water cleanup at OU-4.
F:\PROJ\601788S\f-StfiOD12\FINAL\I2FNLROD.WPD Jj-3 April, 1996
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Final Record of Decision Operable Unit 12
Ells\vorth Air Force Base, South Dakota
Comment 2. Jan Deming
Asked about whether the results of the methane gas survey would change the preferred
alternative fqr the site, and, if so, would any changes be brought before the public for
comment.
Response: The results of the methane gas survey will be used to determine the extent of the area
with methane, and the concentrations of methane in those areas. The main concern
with methane is that it.might hinder the growth of vegetation. The study will determine
whether the level of methane is sufficient to warrant methane gas venting as part of the
cover system.
Comment 3. Jan Deming
Asked if the methane gas poses a health risk to humans.
Response: Methane is not a risk to humans at OU-12. Methane is the result of decomposition of
organic material such as domestic refuse. All landfills that contain domestic refuse
vent methane to the atmosphere, except in the case of very, very large landfills. The
explosive nature of methane is generally the primary concern at landfills which would
require a nonpermeable cover. Since the cover at OU-12 will be made of perameable
earthen materials, methane (if present) would not accumulate beneath the cover and
present the explosive risk.
Comment 4. Phyllis Engleman
Asked if the drainage through the middle of OU-12 had any contaminants?
Response: Jet-fuel related contaminants were present in the sediment. The contaminants were
evaluated in the risk assessment. The calculated risk for the drainage channel is within
the acceptable range. The sediment is also being investigated as part of the Basewide
Ecological Risk Evaluation under OU-11. If there is any need for remediation based
on the findings of OU-11, it will be addressed in the OU-11 Proposed Plan.
4. Remedial Design/Remedial Action Concerns
During the Remedial Design (RD), the Base will make available a fact sheet and a notice of
availability of the Record of Decision to allow additional public involvement.
F:\PROJ\602788S'
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