PB95-963920
EPA/ROD/R03-95/210
March 1996
EPA Superfund
Record of Decision:
Dover Air Force Base,
Lindane Source Area of Area 6, DE
9/26/1995
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RECORD OF DECISION
DECLARATION OF THE SELECTED INTERIM REMEDY
Site Name and Location
Lindane Source Area of Area 6, West Management Unit, Dover Air Force
Base, Kent County, Delaware.
Statement of Basis'and Purpose
This Record of Decision (ROD) presents the selected interim remedial action
for Lindane Source Area, which was chosen in accordance with the requirements of
the Comprehensive Environmental Response, Compensation, and Liability Act of 1980
(CERCLA), 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), 40 CFR Part 300. This decision
prepared by the U.S. Air Force, the lead agency, as the owner/operator of the Base
is based on the Administrative Record for the Site. Support was provided by the U.S.
Environmental Protection Agency (EPA) Region HI and the Delaware Department
of Natural Resources and Environmental Control (DNREC).
The State of Delaware and the U.S. Environmental Protection Agency concur
with the selected interim remedy. The information supporting this interim remedial
action decision is contained in the information repository for the Administrative
Record located at the Dover Public Library, Dover, Delaware.
Assessment of the Site
The Area 6 Remedial Investigation identified a lindane plume in groundwater
that emanates from the Paint Washout Area (Site SSS9). Soil and groundwater data
indicate that the Undone source resides somewhere between two monitoring well
points in this area. Groundwater concentrations, of lindane increase from 0.042 /tg/L
to 27 /ig/L between these points. Although a Risk Assessment was not specifically
performed for groundwater in the Lindane Source Area, the contribution of lindane
to the overall Area 6 risk from exposure to groundwater under a hypothetical future
commercial/industrial land use scenario was 2 x 10"5.
Actual or threatened releases of hazardous suBstances from this^Site, if not
addressed by implementing the interim response action selected in this ROD, may
present a current or potential threat to public health, welfare, or the environment.
Lindane Source Area
1
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Description of the Selected Interim Remedy
The selected interim remedy consists of excavation and removal of the lindane-
contaminated soil source with offsite incineration treatment. The soil source of
lindane will be further delineated during the Remedial Design. The lindane-
contaminated soil will be handled as a U129 listed hazardous waste as defined under
the Delaware Regulations Governing Hazardous Waste.
Statutory Determinations
The selected interim remedial action satisfies the remedial selection process
requirements of CERCLA and the NCP. The selected interim remedy provides the
best balance of trade-offs among the nine criteria required to be evaluated under
CERCLA. The selected interim action provides protection of human health and the
environment, complies with federal and state requirements that are legally applicable
or relevant and appropriate to the action, and is cost effective. This interim remedy
utilizes permanent solutions and alternative treatment technology to the maximum
extent practicable, and satisfies the statutory preference for remedies that employ
treatment that reduces toxicity, mobility, or volume as a principal element. The Air
Force understands that although this interim remedy may not achieve MCLs for
certain contaminants, this interim action is only part of a total remedial action for the
Base that will be protective of the public health and welfare and of the environment
when completed (CERCLA 121d, 42 U.S.C 9621.d).
Q SFP IPOS
CHARLES T. ROBERTSON,'JR. Date THOMAS C
Lieutenant General, USAF Hazardous W^ste
Air Mobility Command Division Direcu
Chairperson, Environmental Environmental Protection Agency
Protection Committee Region m
Lindane Source Area
2
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RECORD OF DECISION
FOR THE INTERIM REMEDY OF
LINDANE SOURCE AREA OF AREA 6
WEST MANAGEMENT UNIT
DOVER AIR FORCE BASE, DOVER, DELAWARE
August 3, 1995
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DECISION SUMMARY FOR THE RECORD OF DECISION
LINDANE SOURCE AREA OF AREA 6
WEST MANAGEMENT UNIT
DOVER AIR FORCE BASE
INTRODUCTION
Dover Air Force-Base (DAFB) recently completed a Focused Feasibility Study
(FFS) conducted to address chlorinated solvent and pesticide source area
contamination in Area 6 of Dover Air Force Base (DAFB), Delaware as an interim
response. The FFS was undertaken as part of the U.S. Air Force's Installation
Restoration Program (IRP). The basis for the FFS was the Area 6 Remedial
Investigation (RI) report dated July 1994, which characterized contamination and
evaluated potential risks to public health and the environment. The interim FFS was
performed as the first phase of Feasibility Studies to be conducted on sites in the West
Management Unit, the management unit to which Area 6 belongs. The scope of the
FFS was limited to the evaluation of alternatives for remediation of primary
chlorinated solvent and pesticide source areas originating in the northern, upgradient
portion of the Area 6 region of investigation. The final remediation of source areas,
if necessary, and non-source area contamination in Area 6 posing human health or
environmental risks will be addressed in the final Base-wide Feasibility Study (FS).
This Record of Decision (ROD) addresses the lindane source area, which is
one of the source areas evaluated in the FFS. This ROD summarizes the FFS,
describes the remedial alternatives that were evaluated, identifies the remedial
alternative selected by DAFB, and explains the reasons for this selection. The U.S.
Environmental Protection Agency (EPA) and the State of Delaware concur with the
interim remedy selected in this ROD. ~ *,
As an aid to the reader, a glossary of the technical terms used in this ROD is
provided at the end of the summary.
Lindane Source Area
ROD-1
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PUBLIC PARTICIPATION
The Proposed Plan for this site was issued on June 16, 1995. The public
comment period on the Plan was open through July 31,1995. Documents comprising
the Administrative Record for the site were available at the Dover Public Library.
SITE BACKGROUND
DAFB is located in Kent County, Delaware, 3.5 miles southeast of the city of
Dover (Figure 1) and is bounded to the southwest by the St. Jones River. DAFB
comprises approximately 4,000 acres of land, including annexes, easements, and leased
property (Figure 2). The surrounding area is primarily cropland and wetlands.
DAFB began operation in December 1941. Since then, various military services
have operated out of DAFB. The present host organization is the 436th Airlift Wing.
Its mission is to provide global airlift capability, including transport of cargo, troops,
equipment, and relief supplies.
DAFB is the U.S. East Coast home terminal for the C-5 Galaxy aircraft. The
Base also serves as the joint services port mortuary, designed to accept casualties in
the event of war. The C-5 Galaxy, a cargo transport plane, is the largest aircraft in
the USAF, and DAFB is one of a few military bases at which hangars and runways are
designed to accommodate these planes.
The portion of DAFB addressed in this ROD is located within Area 6 of the
West Management Unit The West Management Unit is one of four Management
Units into which the Base has been divided (Figure 3). Area 6 is the largest of five
associated areas identified in the West Management Unit. The Area 6 region of
investigation extends approximately 8,400 feet from its northern most point near the
'' . ••*«
hardstand and Building 723 to its southern most point near the St. Jones River
(Figure 4). The area north of U.S. Highway 113 contains the industrialized portion
of the Area 6 region of investigation. The location addressed in this ROD falls within
this industrialized portion of Area 6.
Lindane Source Area
ROD-2
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OVER
FAMILY
...HOUSING
=K ANNEX
113
FIGURE 1
LOCATION OF
DOVER- AIR FORCE BASE
Lindane Source Area
ROD-3
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c
g.
§§
o
p
—-— USAF PROPERTY LINE
PORT MAHON
FACILITY LOCATED
IN FLOOD-PRONE AREA
Apprmlmately 4 Uilei Northeast of OAF8
DAMES & MOORE
FIGURE 2
BASE BOUNDARIES
DOVER AIR FORCE
BASE
DOVER FAMILY HOUSING ANNEX
Note AnxoilntoMy 1 UK Sovtlwnt o< OWB
Modified from
ing Selene*. '983
Original Base Mop Produced fay HA2WRAP.
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c
ex
n>
I
1000 0 2000
-===========3
SCALE IN FEET
IMPS PfftP/uitD
DAMES * MOORE
FIGURE 3
MANAGEMENT UNITS
AND AREAS
OF INVESTIGATION
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Region
Inyestigati
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DAFB is relatively flat, with elevations ranging from approximately 10 to 30
feet above mean sea level (MSL). The ground surface is covered almost entirely by
buildings, concrete, and asphalt. Surface water runoff throughout the industrialized
portion of Area 6 is controlled by an extensive storm drainage system. The storm
drains direct most runoff to either Pipe Elm Branch or the golf course tributary to the
St. Jones River.
The Columbia Formation is the shallowest water-bearing unit and holds the
water table aquifer. The Columbia Formation typically consists of fine to coarse
grained sand with varying amounts of silt, clay, and gravel. Discontinuous lenses of
gravel, silt and clay are also common. Generally, the upper portion of the Columbia
Formation is finer grained and contains more silt and clay lenses than the deeper
portion. The water table is generally encountered at a depth of 10 to 12 feet below
ground surface (bgs) in the northern portion of Area 6 and shallows to within a few
feet of the surface in the Base housing area near the St. Jones River. The
groundwater elevation or potentiometric surface of both the shallow and deep zones
of the Columbia Aquifer range from approximately 13.5 feet MSL in the northern
portion to less than 3 feet MSL near the St. Jones River. The thickness of the
Columbia Formation in Area 6 ranges from 28 to 64 feet.
Unconformably underlying the Columbia Formation is the upper unit of the
Calvert Formation, which generally consists of gray to dark gray firm, dense silt and
clay, with thin laminations of silt and fine sand. This upper silt and clay unit ranges
in thickness from 15 to 21 feet in the northern portion of Area 6. The hydraulic
conductivity of this unit range from 6.83 x 10'3 to 1.53 x 19'3 ft/day (2.41 x 16"6 to 5.39
x 10 cm/sec), which are three to five orders of magnitude lower than the overlying
Columbia Formation. These significantly lower hydraulic conductivities SSrm a barrier
to the vertical migration of constituents identified in the Columbia Aquifer.
Underlying this confining unit is the upper sand unit of the Calvert Formation or the
Frederica Aquifer. This aquifer averages 22 feet in thickness in the vicinity of DAFB.
No constituents of concern were identified in the three Frederica monitoring wells
Lindane Source Area
ROD-7
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installed in Area 6. Additionally, no production wells are installed the Frederica
Aquifer in the vicinity of DAFB.
Area 6 is defined by the association of chlorinated solvents in groundwater
forming a plume in the Columbia Aquifer. The Area 6 RI identified a lindane
groundwater plume (Figure 5) that emanates from the Paint Washout Area (Site
SS59). Lindane is a nonvolatile pesticide compound. The lindane source is believed
to reside in the subsurface soils of the open storage yard in the Paint Washout Area
near well MW212S. Lindane concentrations in shallow groundwater are approximately
three orders of magnitude higher in this well than in the nearest upgradient shallow
well.
SOURCE AREA CHARACTERISTICS
The following section describes the physical and chemical characteristics of the
lindane source area, which is addressed in this Record of Decision.
Soil and groundwater data indicate that a lindane source area resides in the
Paint Washout Area (Site SS59), located in the eastern portion of the open storage
yard near 5th Street. A map of the Paint Washout Area vicinity summarizing the
available lindane data in soil and groundwater is presented in Figure 6. As shown in
the figure, the concentration of lindane in the groundwater between wells 21 IS and
212S increases from 0.042 pg/L to 27 /tg/L between these points. Thus, the
groundwater data indicates that the soil-based lindane source resides in the vicinity of
well 212S. For cost estimating purposes only, the assumed dimensions of the lindane
source area are 20 feet by 20 feet by 1 foot thick, covered by 1 foot of soil. The
remedial design will define the exact dimensions of the lindane source area.
SUMMARY OF SITE RISKS
"•' . . •*»
The full Risk Assessment (RA) for Area 6 can be found in the final Area 6 RI
report dated July 1994. The purpose of the RA is to determine whether exposure to
site-related contaminants could adversely affect human health and the environment.
The focus of the baseline RA is on the possible human health and environmental
Lindane Source Area
ROD-8
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LEGEND:
Arto* of «l«vot«d
UNOANE In
d««p and »hollow
Columbia Aqulftr,
"9/1-
Monitoring W«ll/
Piazomiltr
GP101
0 Groundwoltr Prob*
DDL B«low O.t.cllon Umtt
''0*\. UNOANE contour.,
^
IMPS PREPARED Bl:
DAMES & MOORE
a xo too
B0ttŁ: 1 NCH • 000 FST
FIGURE 5
UNOANE IN
SHALLOW AND DEEP
COLUMBIA AQUIFER
Lindane Source Area
ROD-9
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I/Water
para tor
MAPS PREPARED BY:
Assumed Undone
Source Area
DAMES & MOORE
Original Bait map produced by MAZWRAP.
FIGURE 6
ASSUMED LINOANE
SOURCE AREA
LOCATION
Lindane Source Area
ROD-10
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effects that could occur under current or potential future use conditions in the event
that the contamination is not remediated. The risk is expressed as lifetime excess
cancer risk (LECR) for carcinogens, and hazard quotient (HQ) for noncarcinogens.
For example, an LECR of 1 x 10"6 represents one additional case of cancer in one
million exposed population, whereas a hazard quotient above one presents a likelihood
of noncarcinogenic health effects in exposed populations.
The baseline RA focused on potential pathways by which maintenance and
construction workers could be exposed to contaminated materials in Area 6. The
workers' exposure to groundwater and soil have been evaluated under a regular
maintenance scenario; a future construction scenario; and a hypothetical future
groundwater use from the Columbia Aquifer under a commercial/industrial scenario.
Although a specific Lindane Source Area RA has not been performed, the calculated
i
risk contribution from the hypothetical future exposure to lindane-contaminated
groundwater in Area 6 was 2 x 10~5. In addition to the overall Area 6 risk, lindane
concentrations in the Lindane Source Area have been compared to the risk-based
screening concentrations (RBSCs) developed for commercial/industrial scenario at
DAFB to identify if it presents a risk-based concern.
The future use of groundwater from the Columbia Aquifer by Base personnel
is quite unlikely and hypothetical. This hypothetical future groundwater use assumes
that groundwater from the Columbia Aquifer will be used for drinking and showering
purposes by Base personnel under a commercial/industrial scenario. The RBSCs were
compared with maximum detected concentration of lindane in the Lindane Source
Area. The maximum detected lindane concentration of 27 pg/L hi Lindane Source
Area groundwater is higher than its RBSC of 0.22 pg/L.
The maximum concentration of lindane detected in soil was compared to its
RBSC developed for exposure to soil under a commercial/industrial scenario. The
maximum detected lindane concentration of 36 /ig/kg is substantially lower than its
RBSC of 2,200 /xg/kg.
Lindane Source Area
ROD-11
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The groundwater and soil data suggest that there is a soil-based source of
lindane, and the possibility exists for exposure of workers to hazardous substances in
soil during excavation activities. Source areas identified during excavation will require
worker protection in accordance with health and safety protocols. All workers
performing excavation work at DAFB will be health and safety trained for work at
CERCLA sites.
Based on the direction of groundwater flow, the Area 6 plume extends in a
southerly direction towards the St. Jones River. There are no surface water discharge
points within Area 6 between the Lindane Source Area and the river. Presently, the
Area 6 plume is confined within the Base property, and has not reached the St. Jones
River.
Actual or threatened releases of hazardous substances from this Site, if not
addressed by the selected alternative or one of the other active measures considered,
may present a current or potential threat to public health, welfare, or the environment.
REMEDIAL ACTION OBJECTIVE
For the lindane source area, an action-specific interim RAO of removing the
soil source of lindane has been established, though no specific lindane concentration
limits have been set. A lindane action level will be established during the Remedial
Design that will minimize further degradation of groundwater quality through leaching.
The action level will be determined through the use of an appropriate leaching model
and collection of site data. Remediation of the plume itself is not addressed in this
ROD.
The issues of final cleanup levels and attainment of ARARs will be addressed
in the Final Basewide Record of Decision. The remedial action selected fer this ROD
is only part of the remedial action which will be selected in a Final Basewide ROD.
SUMMARY OF ALTERNATIVES
Engineering technologies applicable to remediating the contaminated media
were screened according to their effectiveness and implementability. Only one
Lindane Source Area
ROD-12
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technology was determined to be applicable and it was developed into the action
remedial alternatives. The two remedial alternatives evaluated are presented below.
• Alternative 1-No Action.
• Alternative 2-Offsite Incineration of Lindane-Contaminated Soil.
The two remedial alternatives that were evaluated in detail are described
below. In addition, the capital, annual operation and maintenance (O&M), and
present worth costs of both alternatives are provided.
Alternative 1
Capital Cost
Annual O&M Cost
Present Worth
Lindane
Source Area
$000
$000
$000
The no action alternative is evaluated in order to establish a baseline for
comparison against other alternatives. Under this alternative, no efforts are
undertaken to remove the lindane-contaminated soil source of the lindane
groundwater plume.
Alternative 2
f : • '
Capital Cost
Annual O&M Cost
Present Worth
, Lindane
Source Area
$140,000
; ..$000
$140,000
Alternative 2 consists of excavation and removal of the lindane-contaminated
soil source with offsite incineration treatment.
Lindane Source Area
ROD-13
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The soil source of lindane contamination will be further delineated during the
remedial design. The lindane contaminated soil is interpreted as a U129 listed
hazardous waste under the implementing regulations of the Resource Conservation
and Recovery Act (RCRA), and as such is subject to land disposal restrictions.
Therefore, lindane-contaminated soil exceeding action levels will be excavated and
sent to an offsite RCRA-permitted facility for incineration and disposal. This
treatment method will reduce residual lindane concentrations in the .treated soil to
below the treatment level required for disposal of the soil.
The action-specific RAO of removing the soil-based source of lindane will be
achieved within one year. The present worth cost of this alternative is $140,000.
EVALUATION OF ALTERNATIVES
The selected alternative for remediating the contamination in the Lindane
Source Area is Alternative 2. Based on current information, this alternative provides
the best balance of trade-offs among the alternatives with respect to the nine criteria
that are required to be evaluated under CERCLA. This section profiles the
performance of the selected alternative against the nine criteria and explains how it
compares to the other alternative under consideration.
Overall Protection of Human Health and the Environment
The overall protectiveness criterion is a composite of other evaluation criteria,
especially short-term effectiveness, long-term effectiveness, and compliance with
ARARs. Alternative 1 (no action) is not considered effective because the soil source
of lindane contamination will remain in place. Alternative 2 (lindane removal) will
meet the RAO and is considered effective.
'! - . -*fe
Compliance With
There are no ARAR considerations associated with Alternative 1 (no action).
Alternative 2 (lindane removal) consists of the excavation and removal of the soil-
based source of lindane. This soil will be managed as U129 listed hazardous waste.
The excavation, handling, transportation, treatment, and ultimate disposal actions for
Lindane Source Area
ROD-14
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this soil will comply with RCRA requirements. The Delaware regulations
implementing RCRA in the state are the Delaware Regulations Governing Hazardous
Waste (DRGHW). Lindane is listed as a hazardous waste under DRGHW 26133.
The storage of hazardous waste in piles is addressed under DRGHW 264. The
transportation of hazardous waste is addressed under DRGHW Part 263. Finally, land
disposal restrictions are addressed under DRGHW Part 268.
Long-Term Effectiveness and Permanence
The long-term effectiveness and permanence criterion primarily considers the
magnitude of residual risk that would remain after the implementation of an
alternative, and the adequacy and reliability of the controls instituted. Under
Alternative 1 (no action), the lindane-contaminated soil source will be left in place.
Hence, the long-term protectiveness of this alternative cannot be demonstrated.
Alternative 2 (lindane removal) provides for the removal and treatment of the
lindane-contaminated soil source material. This represents a permanent remedy that
will halt further leaching of lindane into groundwater.
Reduction of Toxicity. Mobility, and Volume
No reduction of toxicity, mobility, or volume will be achieved from the
implementation of Alternative 1. Alternative 2 consists of the removal and offsite
incineration of the Undane-contaminated soil, which will reduce the toxicity of the
treated soil. In addition, it will reduce the source of lindane contamination that may
leach into groundwater.
Short-Term Effectiveness
Alternative 1 (no action) includes no remedial actions. Therefore, there will
be no short-term impacts on community or worker' health or the envinShment from
construction activities. However, Alternative 1 will not eliminate the soil-based source
of lindane.
Alternative 2 will result in the rapid removal of the soil-based source of
lindane. The exposure by construction workers to lindane-contaminated soil and dust
Lindane Source Area
ROD-IS
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will be minimized through the use of appropriate protective clothing and equipment.
No impacts to the community are anticipated.
Implementabilitv
Three main factors are considered under this criterion: technical feasibility,
administrative feasibility, and availability of services and materials. Both alternatives
are Administratively feasible and the required services and materials are readily
available. Hence, the comparison will focus on the technical feasibility of the
alternatives.
Alternative 1 (no action) have no technical feasibility considerations. The
technical feasibility considerations associated with Alternative 2 (lindane removal) are
minimal. The qualified excavation and transportation contractors required to perform
the work are readily available. In addition, there is ample offsite incineration capacity
available to perform the required thermal destruction.
Cost
No direct costs are associated with the implementation of Alternative 1 (no
action). The capital costs of Alternative 2 (lindane removal) is $140,000. There are
no O&M costs associated with either alternative.
State Acceptance
The State of Delaware concurs with the selected interim remedy for the lindane
source area.
Community Acceptance
No public comments were received on the proposed interim remedy.
•/ . <*,
CONCLUSION
Based on the evaluation of the alternatives using the nine criteria, Alternative
2 (lindane removal) is preferred. Alternative 2 is protective of human health and the
environment, complies with all ARARs, and represents a permanent remedy that will
protect groundwater quality.
Lindane Source Area
ROD-16
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The selected alternative utilizes permanent solutions and alternative treatment
technologies to the maximum extent practicable. This interim action will not
negatively impact the ability to implement a final action if required. The final remedy
will be selected in the final Base-wide ROD.
Actual or threatened releases of hazardous substances from this Site, if not
addressed by the selected alternative, may present a current or potential threat to
public health, welfare, or the environment.
Lindane Source Area
ROD-17
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GLOSSARY AND ACRONYMS
Aquifer - A geologic formation capable of yielding water to wells and springs.
ARARs • Applicable or Relevant and Appropriate Requirements. Criteria set forth
by federal and state statute and regulations that must be considered in the
evaluation of remedial alternatives.
Capital Cost - Cost incurred for the construction and startup of a facility.
CERCLA - Comprehensive Environmental Response, Compensation, and Liability
Act Federal law creating the Superfund program.
DAFB - Dover Air Force Base.
EPA - Environmental Protection Agency.
FS - Feasibility Study.
FFS - Focused Feasibility Study.
Gronndwater - Subsurface water residing in a zone of saturation.
HO - Hazard Quotient. An indicator of the noncarcinogenic health risk associated
with exposure to a chemical. -
Incineration - The process of burning a material so that only ashes remain.
Leach - The solubilization and transport of constituents in soil through the percolation
of surface water to groundwater.
LECR - Lifetime Excess Cancer Risk. The probability of the carcinogenic health risk
associated with exposure to chemicals of concern.
'' •- . •*
O&M Cost - Annual cost incurred for operation and maintenance of a facility.
Plume - A recognizable distribution of constituents in groundwater.
Potentiometric Surface - An imaginary surface that represents the static head of
groundwater and is defined by the level to which water will rise.
Lindane Source Area
ROD-18
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GLOSSARY (cont'd)
RAO - Remedial Action Objective. Cleanup goal established for the remediation.
RBSC - Risk-Based Screening Concentration. A chemical-specific concentration used
to preliminarily assess whether exposure to the chemical poses a potential
health risk.
RCRA - Resource Conservation and Recovery Act.
ROD - Record of Decision. A legal document issued by the lead governmental
agency selecting the remedy to be implemented at a CERCLA site.
Lindane Source Area
ROD-19
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