United States
Environmental Protection
Agency
Off ice of
Emergency and
Remedial Response
EPA/ROD/R03-93/174
September 1993
PB94-963904
SEPA Superfund
Record of Decision:
U.S. Defense General Supply
Center, VA
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50272-101
REPORT DOCUMENTATION
PAGE
1. REPORT NO.
EPA/ROD/R03-93/174
3. Recipient's Aeeeition No.
4. TJlto and Subtitle
SUPERFUND RECORD OF DECISION
U.S. Defense General Supply Center, VA
Third Remedial Action
5. Report Data
09/29/93
6.
7. Authorfa)
8. Performing Organb*tlon Rapt No.
9. Performing Organization Nam* and Address
10 Proftet Tart/Work Unit No.
11. Contract(C)orarant(G)No.
(G)
12. Sponsoring Organization Name and Address
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
13. Type of Report a Period Covered
800/800
14.
IS. Supplementary Notes
PB94-963904
16. Abstract (Lhrdt: 200 words)
The 71-acre U. S. Defense General Supply Center site is a supply and storage facility
within the 640-acre Defense Logistics Agency located in Chesterfield County, Virginia.
Land use in the area is predominantly residential, commercial, and light industrial,
with a wetlands area located along the eastern edge of the site. Land surface at the
site has been altered extensively by grading and filling operations, and surface
drainage from the site flows into No Name Creek, ultimately reaching the James River
less than two miles away from the site. Of the estimated 2,200 residents who live
within one mile downgradient of the site, 10 residences use ground water for their
drinking water supply; and many more use ground water for household activities. The
site has been divided into three distinct geographic areas for remediation, which
include the Open Storage Area (OSA), Area 50, and the National Guard Area (NGA). Since
1942, the 43-acre OSA has been used as a storage lot for bulk drummed chemicals. The
majority of the 55-gallon drums contain petroleum oils and lubricants (POLs), but
solvents, pesticides, herbicides, and other chemicals also are stored in this area.
The northern end of the OSA was also a former drum recoupment area, which operated from
the early 1960s until 1982. Area 50 is approximately 13 acres and was used as a
landfill for construction debris and damaged containers.of solid and liquid stock
(See Attached Page)
17. Document Analysis a. Descriptors
Record of Decision - U.S. Defense General Supply Center, VA
Third Remedial Action
Contaminated Medium: gw
Key Contaminants: VOCs (benzene, PCE, TCE)
b. Identffien/Open-Endsd Terms
c. COSATI Field/Group
18. Availability Statement
19. Security Class (TMs Report)
None
20. Security Ctass (TMs Paot)
None •
21. No. of Pto*s
54
22. Price
(See ANSI-Z39.18)
SM Instructions on flvwrsv
OPTIONAL FORM 272 (4-77)
(Formerly NTtS-35)
Department of Commerce
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EPA/ROD/ROX-93/174
U.S. Defense General Supply Center, VA
Third Remedial Action
Abstract (Continued)
chemicals in the 1960s and 1970s. Some of the contaminants disposed of in the area
include photographic development chemicals, organic solvents, pesticides, herbicides,
POLs, and PCBs. The NGA is a 15-acre area which was leased to the Virginia Army National
Guard beginning in the 1950s. The NGA is currently used for vehicle maintenance
operations which include engine cleaning and degreasing, fluid changes, lubrication, and
engine rebuilding, all of which required the use of chlorinated and non-chlorinated
solvents. In the past, underground and above-ground storage tanks in this area wer.e used
to store fuels, oils, and solvents. In 1984, EPA initiated investigations at the site
which later revealed, contamination of the soil and ground water by petroleum products,
chlorinated and non-chlorinated solvents, pesticides, herbicides, and metals from improper
chemical handling and storage activities conducted in the late 1950s and 1970s. Two 1992
RODs addressed source contamination in two separate areas, as OUs 1 and 5, respectively.
This ROD addresses an interim remedy for the ground water, as OU9. Six future RODs are
planned for the site; three will address source contamination as OUs 2, 3,. and 4, and
three will address ground water contamination as OUs 6, 7, and 8. The primary
contaminants of concern affecting the ground water are VOCs, including benzene, PCE, and
TCE.
The selected interim remedial action for this site includes extracting and treating ground
water using air stripping; controlling air emissions using activated carbon adsorption,
followed by either offsite treatment or offsite disposal of the spent activated carbon;
discharging the treated ground water onsite to a series of infiltration trenches; and
monitoring the ground water. The estimated present worth cost for this remedial action is
$594,067, which includes an estimated annual O&M cost of $46,000.
PERFORMANCE STANDARDS OR GOALS:
Final goals for -ground water have" not been determined and will be implemented as part of
OU6. Chemical-specific ground water interim action levels are based on SDWA MCLs or MCLGs,
and include benzene 5 ug/1; PCE 5 ug/1; and TCE 5 ug/1.
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RECORD 07 DECISION
INTERIM REMEDIAL ACTION
DEFENSE GENERAL SUPPLY CENTER - OPERABLE UHIT 9
1.0 DECLARATION
1.1 SITE NAME AND LOCATION
Operable Unit 9
Open Storage Area/Area 50/National Guard Area Groundvater
Interim Remedial Action
Defense General Supply Center
Chesterfield County, Virginia
*.
1.2 STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected interim remedial action
for Operable Unit 9 (OU9) at the Defense General Supply Center (DGSC) in
Chesterfield County, Virginia near Richmond. OU9 pertains to groundvater
beneath Area 50, the Open Storage Area (OSA), and the National Guard Area
(NGA). The action vas chosen in accordance with the Comprehensive
Environmental Response, Compensation, and Liability Act of 1980, as amended
(CERCLA), 42 U.S.C. SS 9601 et sag., and, to the extent practicable, the
National Oil and Hazardous Substances Pollution Contingency Plan (NCP), 40
C.F.R. Part 300. This decision is based on the administrative record for
this Operable Unit. Both EPA and the Commonwealth of Virginia concur with
the selected remedy.
1.3 ASSESSMENT OP THE SITE
Actual or threatened releases of hazardous substances from OU9 at
DGSC, if not addressed by implementing the interim remedial 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 THE SELECTED REMEDY
This operable unit is the third of nine operable units that are
currently being addressed at the DGSC. OU9 addresses interim treatment and
containment of groundvater in the upper and lower aquifers beneath Area 50,
the OSA, and the NGA. The other OUs, and the portions of the Site that
each addresses are as follows:
o OUl-Open Storage Area Source Area
o OU2-Area 50 Source Area
o OU3-National Guard Area Source Area
o OU4-Fire Training Area Source Area
o OU5-Acid Neutralization Source Area
o OU6-OSA/Area 50/NGA Groundwater (Final Remedy)
o OU7-Fire Training Area Groundwater
o OU8-Acid Neutralization Pits Groundwater
RODS addressing OUl and OUS were signed in March and May 1992,
respectively, and are currently being implemented.
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OU6 and OU9 are the same geographic location. OU9 relates to interim
treatment of the contaminated groundwater. OU6 relates to the final
groundwater remedy for this location.
The primary objectives of this remedy for OU9 are to reduce risk to
human health by impeding further spread of groundwater contaminated with
volatile organic compounds (VOCs) in OU9 through groundwater extraction and
treatment before the final remedial action is implemented, to lessen the
migration of contaminated groundwater, to initiate the reduction of
toxicity, mobility, and volume of the contaminants in the groundwater, and
to collect data regarding changes in the aquifer and contaminant
concentrations in response to remediation measures. This remedy is
considered an interim action. Final cleanup goals for groundwater have not
yet been determined. A final action that addresses the groundwater (0176)
will be selected after data generated during the implementation of this
interim action are evaluated. This interim action for OU9 is expected to
become part of the final action for OU6 and to provide for significant risk
reduction early in the remedial process.
The major components of the selected remedy include:
• Withdrawal of contaminated groundwater from unconsolidated deposits
through a series of extraction wells and intercepting trenches;
• Conveyance of contaminated groundwater through a pipe network to. an
on-site treatment facility;
• Treatment of contaminated groundwater through air stripping of VOCs
and activated carbon treatment of related air emissions sufficient to meet
Federal and State Applicable or Relevant and Appropriate Requirements
(ARARs) for air and the receiving aquifer;
• Discharge of treated groundwater to a series of percolation trenches
on DGSC property;
• Off-site disposal or treatment of spent activated carbon used to
control air emissions of VOCs.
• Periodic groundwater monitoring to evaluate the performance and
effectiveness of the groundwater extraction, treatment, and percolation
system, and to establish final cleanup goals; and,
• Modification of the system as necessary based on periodic monitoring.
1.5 STATUTORY
This interim action is protective of human health and the environment,
complies with Federal and State requirements that are applicable or
relevant and appropriate to this limited-scope action, and is cost
effective. Although this interim action is not intended to fully address
the statutory mandate for permanence and treatment to the maximum extent
practicable, this interim action utilizes treatment and thus is in
furtherance of that statutory mandate. Because this remedy does not
constitute the final remedy for the Operable Unit, the statutory preference
for remedies that employ treatment that reduces toxicity, mobility, or
volume as a principal element, although partially addressed in this remedy,
will be addressed by the final response action. Subsequent actions are
planned to address fully the threats posed by conditions at this Operable
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Unit. Because this remedy will result in hazardous substances remaining
on-site above health-based levels, a review will be conducted to ensure
that the remedy continues to provide adequate protection of human health
and the environment within five years after commencement of the remedial
action.
/*/ ^ ^ _ date
Jan B. RedJtman ^
Staff Director, Environmental and Safety Office
Defense Logistics Agency
/s/ **^c _ date
Stanley L. Laskowski
/ Acting Regional Administrator
' United States Environmental Protection Agency-Region III
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RECORD 07 DECISION
INTERIM REMEDIAL ACTION FOR OPERABLE UNIT 9
U.S. DEFENSE GENERAL SUPPLY CBHTER
THE DECISION SUMMARY
2.1.0 SITE NAME, LOCATION AND DESCRIPTION
Operable Unit 9 (OU9)—
Area 50/Open Storage Ar•a/National Guard Area—Groundvater
Interim Remedial Action
Defense General Supply Center
Chesterfield County, Virginia
2.1.1 Introduction. The Defense General Supply Center (DGSC), a federal
facility located near Richmond, Virginia, was placed on the National
Priorities List (NPL) in 1987. The Defense Logistics Agency (DLA) is the
lead Federal Agency for this Site and, in a Proposed Plan published on May
3, 1993, proposed that an interim remedial action be implemented at a
portion of DGSC to lessen the migration of contaminated groundwater and
treat contaminated groundwater. This document summarizes the decision
process leading to the selection of this interim remedial action for
Operable Unit 9 at DGSC. The activities described in this document are not
the final remedy for the Site's contaminated groundwater. A ROD describing
the final remedial action will be issued at a later date. This interim
remedial action is expected to become part of the final remedial action.
The interim remedial action selected for Operable Unit 9 (OU9)
consists of extracting the groundwater with wells and trenches, treating
the groundwater with an air-stripper treatment system, and then discharging
the treated water to a series of infiltration trenches above the
contaminated groundwater. Resulting air emissions will be controlled
through activated carbon treatment. The spent activated carbon will be
shipped off-site for treatment or disposal.
2.1.2 Location and Mission. The Defense Logistics Agency, an agency of
the Department of Defense, provides logistics support to the military
services including procurement and supply support, contract administration
and other services. DGSC, located in Chesterfield County, Virginia
approximately 11 miles south of the City of Richmond is one of DLA's
primary logistical centers providing such support (See Figure 1). Since
1942, DGSC's mission has been the managing and furnishing of military
general supplies to the Armed Forces and several federal civilian agencies.
Today DGSC manages more than 300,000 items at a facility valued at $100
million and encompassing 640 acres. The facility includes more than 16
million square feet of covered storage space in 27 large brick warehouses
and an additional one million square feet of office space.
2.1.3 Land Use. Land use in Chesterfield County in the vicinity of DGSC
is primarily single family residential, intermixed with retail stores and
light industry. DGSC is the major industry in the area. The area to the
northeast and east of DGSC has been developed as both single family and
multi-family housing. See Figure 4 showing the location of nearby
residences.
2.1.4 Climate. DGSC is located within the modified continental climatic
zone, an area characterized by extreme variations in temperature and
precipitation during the course of a year. Typically, the area experiences
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•- -]
warm summers, relatively mild winters and normally adequate rainfall. The
mean annual temperature is between 55°F and 60°F. The average annual
precipitation is 44.2 inches. The mean annual pan evaporation rate for the
area is between 48 and 64 inches. Precipitation and pan evaporation are
generally greatest during July and August. Wind direction in the vicinity
of OGSC is variable, although the prevailing wind direction is southerly.
2.1.5 Topography. The land surface at DGSC has been extensively altered
by grading and filling operations. The topography is generally flat with a
slight slope towards the southeast. The maximum difference in the local
topographic relief is approximately 30 feet. Elevations range from 125
feet above mean sea level (msl) at the northern boundary of the Site to 95
feet above msl near the southeastern corner. Surface drainage in the study
area is towards a storm sewer system that drains eastward and discharges
into No Name Creek. The Creek flows north*to-south along the eastern edge
of the National Guard Area, turns to the east, and ultimately discharges
into the James River, some 1 and 1/2 miles away from the Site.
2.1.6 Geology. The unconsolidated soils below DGSC have been divided into
four formations by the U.S. Geological Survey. The Eastover Formation is
present immediately below the land surface and consists of up to 25 feet of
inter-layered beds of sand, silt and clay with occasional gravel. The
predominantly gray clay and silt of the Calvert Formation underlies the
Eastover throughout the area. The Calvert Formation is typically 11 feet
thick. The Aquia Formation, approximately 7 feet of gray sand, gravej. and
clay, underlies the Calvert Formation. The Potomac Formation, which
underlies the Aquia Formation, extends to the bedrock. The Potomac
consists of approximately 40 feet of interbedded sand and gravel with
occasional silt and clay seams. Bedrock in the region consists of the
Petersburg Granite. (See Figure 3.)
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FIGURE 1
SITE AREA
DEFENSE GENERAL SUPPLY CENTER
RICHMOND, VIRGINIA
AREA SO
FORMER UkNOfiU
SEABOARD
COAST UNE
L
SCALE IN MILES
= LAW ENVIRONMENTAL, INC.
GOVERNMENT SERVICES DIVISION
SOURCE: RBIH^NVESTXaATON. AREA SaOPBI STORAGE AREA
AM) WrtlONALGUAfCAflEA. OMfCS4MOORE.JU.YaL KM
1548.4:
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FOAMED AREA SO LANDFILL
EXPLANATION
— — — - BOUNDARY OF SUPPLY CENTER
AA-
A'TRACE OF HYOBOGEOIOGIC
SECTION--S»euon >«ewn
m ligui* 3
U.S. GEOLOGICAL SURVEY
MONITORtNO-IMELL CLUSTER
* NO OENTIFCR
U.S. GEOLOGICAL SURVEY BEDROCK
WELL AND IDENTIFIER
U.S ARMY ENVIRONMENTAL
HYGIENE AGENCY MONITORING
WELL PAW AND IDENTIFIER
U.S. ARMY ENVIRONMENTAL
HYGENE AGENCY MONITORING-
WELL AND IDENTIFIER
Map 'S modified irom Defense General Supply Center Installation Services' base map.
Figure 2.-- Location of U.S. Geological Survey monitoring-well clusters and selected
U.S. Army Environmental Hygiene Agency wells.
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FEET
150 -
125 H
100 H
75 H
50 H
25 H
Sea Level
, I LEI
Upper unconlined aquiler EASfOVfcR t-ORMATION
CALVERT FORMATION
AQUIA FORMATION
NOTE: Location ol section shown on liyure 2.
Sea Luvo'
0 100 200 300 METERS
VERTICAL SCALE GREATLY EXAGGERATED
DATUM IS SEA LEVEL
Figure 3.—Hydrogeologic section showing relations among formations.
(view looking north: trace of section is shown in figure 2.}
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FIGURE 4
LOCATION OF AREA WELLS
DEFENSE GENERAL SUPPLY CENTER, RICHMOND, VIRGINIA
L
SOURCE:
RESIDENTIAL WELL SURVEY.
TAW 4. ENGINEERING SCIENCE, INC.
OCTOBER 1902
LEGEND
LOCATION OP RESIDENTIAL WELL
5 MILE RADIUS UNE
LAW ENVIRONMENTAL, INC.
GOVERNMENT SERVICES DIVISION
154*51
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2.1.7 Natural Resources, the vegetation on DGSC is extremely limited due
to buildings, warehouses, roads, etc., but the vegetation off-site around
DGSC is composed of mixed woodlands and shrubs. Species which may utilize
the limited additional habitat on-site include rodents, rabbits, squirrels,
birds, reptilesr and amphibians.
There are two natural resource areas on the DGSC property. The first
is a recreational pond with fish and waterfowl (domestic ducks and geese)
located approximately a half mile south of OU9; and the second is the
Bellwood Elk Preserve, which is also located a half mile south of OU9.
Off-site, there are also two protected areas. The closest is the Pocahontas
State Forest and Park located approximately five miles southwest of the
Site. The second is the Presquie National Wildlife Refuge, approximately
ten miles southeast of the Site on the James River. There are no protected
lands in the immediate vicinity of DGSC (Law, 1993). According to the
Commonwealth of Virginia Department of Conservation and Recreation,
Division of Natural Heritage, there are no Federally protected species
occurring within the area. However, protected species of migratory birds
may pass through or near DGSC. There is one critical habitat, wetlands,
known to exist around the DGSC property. It is along No-Name Creek and lies
on the eastern edge of OU9.
2.1.8 Hydrogaology. An unconfined water table aquifer is present within
the Eastover Formation. This aquifer, referred to in this document as the
Upper Aquifer, is the first water bearing unit affected by contamination
resulting from activities at the Open Storage Area/Area 50/National Guard
Area (See Figure 3). The low-permeability Calvert and Aquia Formations lie
beneath the Upper Aquifer and separate it from the Potomac Formation which
is referred to as the Lover Aquifer in this document. However, there are
both naturally occurring and man-made pathways between the two aquifers.
Generally the water in both the Upper and Lower Aquifers could be used as
drinking water and the water quality would be class IIA under EPA's
groundwater classification method. The selected interim remedy for OU9 ad-
dresses groundwater within the Upper and Lower Aquifers.
2.1.9 Physical Description of Open Storage Area/Are* 50/Hational Guard
Area. Area 50, the Open Storage Area (OSA), and the National Guard Area
(NGA) are adjoining areas located in the central portion of DGSC as shown
in Figure 2. The OSA is a 43-acre fenced area encompassing Open Storage
Areas 38 through 47. The OSA currently serves as a storage lot for bulk
drummed chemicals. The majority of the 55-gallon drums contain petroleum,
oils, and lubricants (POLs), but solvents, pesticides, herbicides, and
other chemicals are also stored in this area. There is also a former drum
recoupment area at the northern end of the OSA. An existing recoupment
area is located at the southern end of OSA-46, in and around Building 203.
The OSA is primarily gravel with few paved areas, and the drums are stored
horizontally on wooden stringers.
Area 50 is approximately 13 acres and located directly east of the OSA
and directly west of the NGA. Area 50 was used as a landfill for
construction debris and damaged containers of solid and liquid stock
chemicals. Area 50 is relatively level with the surrounding land surface
and is grass covered. Slight depressions are located within Area 50
because some of the fill material has settled.
The NGA is a 15-acre parcel located east of Area 50. Although DGSC
owns the property, DGSC has leased the land to the Virginia Army National
Guard since the 1950s. The NGA is currently used for vehicle maintenance
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operations. These activities, which may use chlorinated and non-
chlorinated solvents, include engine cleaning and degreasing, fluid
changes, lubrication, and engine rebuilding. Existing storage tanks are
shown in the Focused Feasibility Study (FFS) for the NGA (OU3). The NGA is
covered with asphalt and concrete paving and gravel.
2.2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES
2.2.1 General. DGSC was originally constructed in 1941 as two separate
facilities: the Richmond General Depot and Richmond Holding and
Reconsignment Point. In 1942, the two facilities were consolidated and in
1962 the installation became known as Defense General Supply Center. Past
industrial operations at DGSC have included parachute manufacture and
repair, mess kit and canteen repair, refrigerator repair, material
handling, equipment overhaul, and engine rebuilding. Current industrial
operations include the refurbishing of steel combat helmets and compressed
gas cylinders using a dry (ball blasting) process, and tent and fabric
repair. DGSC motor pool operations include minor vehicle repairs, fluid
changes, and vehicle lubrication. These activities take place at the motor
pool facility located in the southern portion- of DGSC. There are
underground gasoline and fuel storage tanks located throughout the Site.
Chemical operations at DGSC have included storing and shipping flammable,
toxic, corrosive and oxidizer chemicals for DLA. The majority of the
chemicals are stored in warehouses at DGSC. Chemicals stored at DGSC- have
also included pesticides and herbicides for use at DGSC and as part of the
chemical stock mission of DGSC.
2.2.2 Open Storage Area/Area 50/national Quard Area. Since 1942, the OSA
has been used as a storage lot for bulk drummed chemicals, the majority of
which were 55-gallon drums of POLs. The northern end of the OSA was also a
former drum recoupment area which had been in operation from the early
1960s until 1982.
Although currently level with the surrounding grade, Area 50 was
formerly a ravine which received construction debris and damaged containers
of solid and liquid stock chemicals from the early 1960's until the early
1970's. Potentially hazardous substances that were present at the Site and
may have been disposed of at Area 50 include toxic and reactive chemicals
used in photographic development processes, organic solvents, pesticides
and herbicides, POLs, polychlorinated biphenyls (PCBs), and other
unidentified compounds. Some of the chemicals may have been disposed of in
Area 50 in drums or damaged containers while others may have been disposed
of as bulk liquids. Remediation of the soil and landfill in Area 50 has
been identified as OU2, for which a remedy has not yet been selected.
The NGA has been leased from DGSC by the Virginia Army National Guard
since the 1950's. The major activities in this area have included vehicle
maintenance using both chlorinated and non-chlorinated solvents for
degreasing purposes. Some waste solvents were reportedly disposed of in
the storm sewer system or on unpaved areas of the NGA. In the past,
underground and aboveground tanks were used for storing fuels, oils, and
solvents in this area. A number of underground and above-ground storage
tanks were located throughout the National Guard Area, most of which have
since been removed.
2.2.3 In 1984, DGSC was recommended for placement on the CERCLA National
Priorities List (NPL), and it was promulgated to the NPL in 1987. This
10
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action was a result of a Hazard Ranking System (HRS) scoring performed for
DGSC that was based on the conclusions of previous studies done at the Site
by the United States Army Environmental Hygiene Agency (USAEHA) and the
United States Army Toxic and Hazardous Materials Agency (USATHAMA). In
August, 1986 the. United States Environmental Protection Agency, Region III
(EPA), issued a Corrective Action Permit to DGSC pursuant to the Resource
Conservation and Recovery Act (RCRA), 42 U.S.C. SS 9601 et s&q. As part of
RCRA activities conducted at the Site, Dames and Moore, a contractor of
DGSC, prepared Remedial Investigation Reports for three areas at DGSC in
1989. The three reports were:
• Remedial Investigation for the Fire Training Area, May 1989;
• Remedial Investigation for the Acid Neutralization Pits Area,
April 27, 1989; and
• Remedial Investigation for the Open Storage Area/Area 50/National
Guard Area, July 1989.
In September, 1990, the DLA, DGSC, EPA, and the Commonwealth of Virginia
entered into a CERCLA Interagency Agreement (IAG) pursuant to Section 120
of CERCLA, 42 U.S.C. S 9620, which contains the requirements for the
implementation of remediation activities. DLA has been proceeding in
accordance with the requirements of the Interagency Agreement, and no
enforcement actions related to CERCLA responses have been initiated. - A
list of environmental studies performed at DGSC since 1984 is included in
Appendix A of this ROD.
In March and May of 1992 the first two of nine Records of Decision
(ROD) for DGSC were signed. Remedial design activities have been nearly
completed for OU5 (soil vapor extraction near the Acid Neutralization
Pits). No physical cleanup of the Site is planned under OU1, which
includes maintenance of fencing and security to continue restriction of
Site access and deed restrictions to restrict future development of the
Site.
2.3.0 SUMMARY OF COMMUNITY PARTICIPATION
2.3.1 On February 23, 1984, DGSC organized an Interagency Task Force
consisting of State regulatory agencies, EPA, County agencies, Virginia
National Guard, representatives of nearby residential areas, and DGSC
personnel. The purpose of this group was to ensure that actions carried
out at the Site were done with input and review froa affected parties.
This group was active in the mid-1980s, but became less active after the
County installed water supply lines to supply potable water to residents
located near DGSC.
2.3.2 In May 1992 DGSC implemented a formal community relations program as
required by CERCLA. DGSC mails a periodic newsletter to interested parties
which describe current activities being performed in support of the
remedial response activities at the Site. In addition, public meetings are
held at important points during the remediation process to provide a means
of community involvement. An administrative record file, open to the
public, is maintained at the Chesterfield Public Library at the
Chesterfield County Courthouse in Chesterfield, Virginia.
2.3.3 Community participation requirements in CERCLA, Sections
11
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113 (k)(2)(B) and 117 have been met for this interim action. The Proposed
Plan for OU9 was released to the public on May 3, 1993. That document was
made available to the public and included in the administrative record
file. The notice of availability for the Proposed Plan was published in
the Richmond Times Dispatch on Nay 3, 1993. The public comment period was
held from May 3, 1993 to June 17, 1993. In addition, a public meeting was
held on June 2, 1993. At this meeting, representatives from the DLA, EPA,
and the U.S. Army Corps of Engineers answered questions concerning the
remedial alternatives evaluated for Operable Unit 9. A transcript of the
public meeting is available in the administrative record file. A response
to the comments received during the public comment period is included in
the Responsiveness Summary, which is attached to this ROD.
2.4.0 SCOPE AND ROLE OF THE RESPONSE ACTION WITHIN THE SITE STRATEGY
2.4.1 As .With many Superfund sites, the problems at D6SC are complex. As
a result, the work at DGSC has been organized into nine operable units,
each of which addresses a portion of the contamination at DGSC. In
addition to OU9, the operable units at this Site include:
OU 1 - Open Storage Area Source Area
OU 2 - Area 50 Source Area
OU 3 - National Guard Area Source Area
OU 4 - Fire Training Area Source Area
OU 5 - Acid Neutralization Pits Source Area
OU 6 - Area 50/Open storage Area/National Guard Area
Groundwater (Final Remedy)
OU 7 - Fire Training Area Groundwater
OU 8 -Acid Neutralization Pits Groundwater
Each of the operable units at DGSC is being investigated and remediated
under a separate schedule. The process for evaluating an operable unit and
selecting a final remedy can be complex and time consuming. In such cases,
it may be beneficial to begin cleanup activities in the form of interim
remedial actions before the final remedy is selected in order to reduce
risk early in the remedial process. OU6 is a location where such interim
activities are considered appropriate because contaminants are continuing
to flow with the groundwater to previously uncontaminated areas at greater
distances from the Site. An interim remedial action that reduces the
"spread" (both horizontally and vertically in the subsurface) of
contaminants and begins the process of collecting and treating hazardous
substances is both possible and desirable. Therefore, the location
designated as Operable Unit 6 is the location of this interim remedial
action (OU9). Geographically, OU6 and OU9 are the same location and
consist of the same contaminated groundwater. Administratively, they are
different actions and are assigned different operable unit designations.
2.4.2 Consistency with Future Remedial Actions. The remedy selected in
this ROD for interim action is the first step in the process to cleanup the
contaminated groundwater at this location. Subsequent actions are planned
to further address groundwater contamination at this Operable Unit. These
actions will be determined when the Remedial Investigation/Feasibility
Study (RI/FS) for OU6 is completed and will be subject to public comment.
Because the interim remedial action selected for OU9 will remove
contaminated groundwater from the aquifer, it is expected to provide early
risk reduction and to become part of the total remedial action that will
attain applicable or relevant and appropriate requirements (ARARs) of state
12
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and federal environmental laws. See section 2.8.3 and Table 4 below.
2.4.3 Goals of the Interim Action. The goals of this interim action are
to lessen the migration of contaminated groundwater, to initiate the
reduction of toxicity, mobility, and volume of the contaminants in the
groundwater, and to collect data regarding changes in the aquifer and
contaminant concentrations in response to remediation measures. During
treatment, VOCs removed from extracted groundwater will be captured and
sent off-site for permanent disposal. This interim action will likely
reduce the total volume of contaminated groundwater to be treated in the
long run because dispersion will be reduced.
2.5.0 SUMMARY OP SITE CHARACTERISTICS
2.5.1 Contamination sources. The types of contaminants that are present
at the Site which are affecting OU9 include petroleum products, chlorinated
and non-chlorinated solvents, pesticides, herbicides and metals. The
sources of these contaminants are being addressed by several operable
units. Contamination of the groundwater in OU9 is the result of chemical
handling and storage activities conducted between the late 1950s and the
mid-1970s. The primary source of the contamination in OU9 is the Area 50
landfill (OU2). Minor sources are the Open Storage Area (OU1) and the
National Guard Area (OU3). Chemicals migrated downward from contaminated
soil to contaminate the underlying groundwater. The contaminated
groundwater migrated both downward and laterally within the Upper and Lower
Aquifers, eventually moving beyond the DGSC boundary.
2.5.2 contaminant Migration and Location of the Oroundvater Plum*. The OU9
groundwater was contaminated primarily by the OU2 Source Area and migrates
eastward beyond the DGSC boundary (See Figures 5a, 5b, 5c, & 5d). There
are two interrelated, but separate groundwater aquifers beneath the Site;
the Upper Aquifer and the Lower Aquifer. The physical characteristics of
the two aquifers are different. Both of the aquifers are contaminated but
the plume size and shape varies between the two. According to the United
States Geological Survey Report, Ground-Water Contamination and Movement at
the Defense General Supply Center, Richmond, Virginia, prepared in 1990,
groundwater flow in the Upper Aquifer is generally towards the north-
northeast at an average rate of approximately 65 feet per year. The
average depth to groundwater varies seasonally but typically ranges from 13
to 16 feet below ground surface. The hydraulic gradient varies from 0.05
percent to 0.12 percent. The low hydraulic gradient indicates that the
rate and direction of groundwater flow are likely to exhibit minor seasonal
changes in response to precipitation. Some, but not all, of the
groundwater in the Upper Aquifer discharges into No-Name Creek.
Groundwater flow direction in the Lower Aquifer is to the east beneath the
OSA and Area 50, with a change of direction to the southeast as the water
flows east of the NGA. Groundwater flow in the Lower Aquifer is
approximately 225 feet per year. There are both naturally occurring and
man-made pathways between the Upper and Lower Aquifers and contaminated
groundwater can migrate between the two.
2.5.3 Sis* and Location of Plum*. VOCs have been detected in the Upper
and Lower Aquifers under DGSC property and an adjacent area. Maps showing
the size and location of the contaminated plume in the Upper and Lower
Aquifers are shown on Figures 5a, 5b, 5c, and 5d. These maps were
developed by Dames and Moore, and the United States Geological Survey
(U.S.G.S.) based upon data collected in 1986 and 1990. According to a
13
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detailed investigation by the U.S.G.S., the plume has not yet spread to
Rayon Park and other areas where individual water supply wells are located.
See Figure 4. The volume of contaminated groundvater in the Upper Aquifer
is estimated to be approximately eight million gallons. The volume of con-
taminated groundwater in the Lower Aquifer is approximately forty million
gallons.
2.5.4 Organic Constituents in the Oroundvater. Several rounds of sampling
and analysis have been performed at OU9 to evaluate the magnitude and
extent of groundwater contamination. Approximately 44 organic compounds
have been detected in the groundwater in OU9. Most of the detected
compounds were found at extremely low concentrations that are not expected
to represent a risk to human health or the environment. However, some were
found at concentrations significantly greater than Maximum Contaminant
Levels (MCLs), promulgated pursuant to the Safe Drinking Water Act, 42
U.S.C. SS 300f to 300J-26, and are of greater concern. See Table 1. The
primary contaminants detected in the groundvater at OU9 are volatile
organic compounds which have been found both on and off the Site.
Contaminant concentrations are greatest beneath Area 50 and decrease as the
plume moves down-gradient (East) beyond the Site boundary.
Trichloroethene, a chlorinated solvent, has been detected at concentrations
as great as 18,000 parts per billion. l,2-Dichloroethene(trans) was found
at concentrations up to 13,000 parts per billion. Other volatile organic
compounds have been detected in off-site wells at lower, but still
significant concentrations.
2.5.5 Znorganio Constituenta ia tn« Oroundvater. Inorganic constituents
were evaluated in a 1992 data collection study conducted by Law
Environmental and in earlier sampling programs, in the general vicinity of
the Area 50 Source Area (OU2). These data are listed in Tables 2 and 3.
The maximum concentrations reported for the listed metals did not exceed
the Maximum Contaminant Level Goals (MCLGs) for inorganic contaminants
promulgated, at 40 C.F.R. S 141.51, pursuant to the Safe Drinking Water
Act, 42 U.S.C. SS 300f to 300J-26. However, there were isolated samples in
which the maximum concentrations of some metals, notably zinc, iron,
silver, selenium, lead, and copper, exceeded the Virginia Groundwater
Standards, the Federal Ambient Water Quality criteria, or the Virginia
Surface Water Standards. Although the latter two sets of criteria are not
directly applicable to groundwater, they are shown in Tables 2 and 3 for
reference in evaluating remedial alternatives in which extracted
groundwater would be discharged to surface water.
The recently collected data on the Upper Aquifer are considered
preliminary, and are under review by EPA and VDEQ. Upgradient samples were
collected during these sampling programs and comparisons with this data
will provide insight into the degree to which contaminants are present
because of releases from source area operable units at the Site as opposed
to natural conditions or some other cause.
14
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TABLE 1
MAJOR OROAHZC CONTAMINANTS ENCOUNTERED AT OD9
1
Contaminant
Vinyl cailoride
Trichloroethene
Tetrachloroethene
Methylene Chloride
1 , 2-Dichloroethane
1, 2-Dichloropropane
Carbon Tetrachloride
Benzene
1,1 Dichloroethene
Chlorobenzene
1 , 2 -Dichloroethene (trans)
1,1, 1-Trichloroethane
Ethylbenzene
Acetone
Maximum
Concentration
Encountered1
87
18,000
3,000
560
376
240
30
6
180
1,500
13,000
1,400
35
180
Action
Level
2
5
5
5
5
5
5
5
7
100
100
200
700
3700
Basis
MCL
MCL
MCL
MCL
MCL
MCL
MCL
MCL
MCLG
MCLG
MCLG
MCLG'
MCLG
IRIS
Concentrations are in micrograms per liter (equivalent to parts per billion).
MCL—Maximum Contaminant Levels for organic contaminants promulgated pursuant
to the Safe Drinking Water Act, 42 U.S.C. SS 30Of to 300J-26. 40 C.F.R. S
141.61.
MCLG—Maximum Contaminant Level Goals for organic contaminants promulgated
pursuant to the Safe Drinking Water Act, 42 U.S.C. SS 300f to 300J-26. 40
C.F.R. S 141.50.
IRIS—EPA Integrated Risk Information System
1Source: Dames 6 Moore (1989)
15
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TABLE 2
DEFENSE GEHERAL SUPPLY CEHTBB—O09
Upp«r Aquifer Qroondvat«r
M*ST"i«J'
Parameter
Aluminum
Arsenic
Barium
Beryllium
Cadmium
Calcium
Chromium
(total)
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Mercury
Nickel
Potassium
Selenium
im Concentrations
of Metals
Max. Cone. Fed. ANQC
3600
4.0
790
2.9
BOL(S.O)
;/ 32,000
13
180
BOL(S.O)
55,000
BDL(IO.O)
14,000
5,200
BOL(0.2)
30
4,900
BOL(l.O)
—
190
—
5.3
1.1
—
210
12
1,000
3.2
—
— '
.012
160
—
5
Detected in
VA sw atd.
—
190
—
—
1.1
—
211
11.8
—
3.2
—
~
.012
161
—
5
Well Savplfl
Fed. MCLO
—
508
2,000
4
5
~
100
1300
—
15
—
—
2
100
—
50
is in 1992
VA ON Std.
—
50
1,000
—
0.4
—
50
1,000
—
50-
—
—
0.05
—
—
10
16
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TABU 2 (coat.)
DBPEHSB GENERAL SUPPLY CEHTBR—OU9
Upper Aquifer Groundvater
Maximum Concentrations of Metals Detected in Well Samples in 1992
ParaMt*r
Silver
Thallium
Vanadium
Zinc
Max. Coac.
BOL(4.0)
BOL(6.0)
BDL(7.0)
120
r«d. ANQC
.12
40
—
110
V* SN Std. P«d. MCLB
—
0.5
—
107.8
VA ON ltd.
—
~
—
50
NOTES:
1. "Max. cone." are the maximum concentrations of dissolved metals in the
Upper Aquifer, in micrograms/liter, measured during the 1992 sampling
program. See Lav Environmental, Inc., April, 1993 in Appendix A.
2. "Fed. AWQC" are the Federal Ambient Water Quality Criteria established
under section 304 or 303 of the Clean Water Act, 33 U.S.C.A S 1314 or 1313,
for the protection of freshwater aquatic life from chronic toxicity.
3. "VA SW Std." are Virginia Surface Water Standards for the protection of
freshwater aquatic life from chronic toxicity (four day average
concentration not to be exceeded more than once every three years), VR 680-
21-01.
4. "Fed. MCLG" are the Federal Maximum Contaminant Level Goals, 40 C.F.R.
S 141.51.
5. "VA GH Std." are the Virginia Groundvater Quality Standards, VR 680-21-
04.
6. All values are in micrograms/liter.
7. "BDL"—below detection limit, which is shown in parentheses.
8. No MCLG exists for arsenic. The Maximum Contaminant Level (MCL) for
arsenic is 50. 40 C.F.R. S 141.62.
17
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TABLB 3
Maxiaua
Parameter
Aluminum
Arsenic
Barium
Beryllium
Cadmium
Calcium
Chromium
(total)
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Mercury
Nickel
Potassium
Selenium
OKFEH81
L01
Conoantrationa
I QENERAL SUPPLY CEHTER— OU9
rar Aquifar oroundvatar
of, Matala Dataetad in Well
Max. Cone. Fed. ANQC
924
4.6
190
1.9
BDL
19,900
BDL
5.2
19
1,840
8.9
44,410
162
BDL
41
84,600
19
—
190
—
5.3
1.1
—
210
12
1,000
3.2
—
— •
.012
160
—
5
V* SW 8td. Fed.
—
190
2
—
1.1
—
211
11.8
—
3.2
—
—
.012
161
—
5
Sanplea
MCLO
—
S0«
,000
4
5
—
100
1300
—
15
—
2
100
—
50
la 1992
V* OW Std.
—
50
1,000
—
0.4
—
50
1,000
—
50
—
0.05
—
—
10
18
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TABLE 3 (CODt.)
DBPBN8B GENERAL SUPPLY CENTER—OU9
Lever Aquifer Groundvater
Concentrations of Metals Detected in Well Samples in 1992
Par*Mt«r Max. Cone. P«d. ANQC V* SW 8td. F«d. MCLO VA OW Std.
Silver 861 .12
Thallium BDL 40 — 0.5
Vanadium 5.8
Zinc -. 467 110 107.8 — 50
NOTES:
1. "Max. cone." are the maximum concentrations of metals in the Lover
Aquifer, in micrograms/liter, measured during the 1989 Dames & Moore
sampling program. See Dames & Moore, July, 1989 in Appendix A.
2. "Fed. AWQC" are the Federal Ambient Water Quality Criteria established
under section 304 or 303 of the Clean Water Act, 33 U.S.C.A S 1314 or 1313,
for the protection of freshwater aquatic life from chronic toxicity.
3. "Va. SW Std." are the Virginia Surface Water Standards for the
protection of freshwater aquatic life from chronic toxicity (four day
average concentration not to be exceeded more than once every three years),
VR 680-21-01.
4. "Fed. MCLG" are the Federal Maximum Contaminant Level Goals, 40 C.F.R.
S 141.51. 5. "VA GW Std." are the Virginia Groundvater Quality Standards,
VR 680-21-04.
6. All values are in micrograms /liter.
7. "BDL11—below detection limit.
8. No MCLG exists for arsenic. The Maximum Contaminant Level (MCL) for
arsenic is 50. 40 C.F.R. S 141.62.
19
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2.5.0 Contaminant Phases, only dissolved groundwater contaminants have been
encountered. Organic non-aqueous phase liquids (NAPLs) have not been
detected at this Operable Unit nor do Site characterization data indicate
they exist. However, if they are encountered during a future phase of work,
system design can be modified to attempt their recovery and treatment.
2.5.7 Contamination in No-Ham* Creek. Chemical analyses have been performed
on water collected from No-Name Creek, located near the downgradient edge of
the contaminant plume. The Creek is a hydrologic discharge zone for some of
the groundwater in the Upper Aquifer being remediated by OU9. The analyses
indicate that the Creek is contaminated with a variety of organic
contaminants similar to those found in the groundwater being remediated by
OU9.
2.5.8 Potentially Affected Populations. There are approximately 350 houses
and 400 apartments located downgradient within a 1-nile radius of OU9, with
an estimated population of 2,200 residents. Figure 4 (Law, 1993) shows a map
of the area one-half mile down-gradient from this Operable Unit. A few of
the nearby residents rely on groundwater wells for their drinking water, but
connection to the Chesterfield County water is available to all residents.
Approximately ten families within a one-mile radius of OU9 continue to use
wells for drinking water supplies. In addition, some nearby residents use
groundwater for purposes such as bathing, cooking, clothes washing, and lawn
or gardening purposes. Environmental receptors do not appear to be
significantly affected directly by the groundwater. However, since the
groundwater discharges to No-Name Creek, the Creek is a potential path 'for
receptors to come in contact with contaminants. Human populations
potentially affected include children and possibly fishermen attracted to the
Creek. Environmental receptors include biota, fauna, and flora in and around
the Creek.
20
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NATIONAL GUARD AREA
WOODED AREA
EXPLANATION
APPROXIMATE AREA OF CONTAMINATION
'I US GEOtOGICAl SIMVEV MONITORING
WEll ClUSIER AND IDENTIFIER
BO I US GEOIOGICAI SURVEV BEDROCK
• WEll AND IDENTIFIER
1378 CONCENIR«IION OF VOLATILE OROANICS
IN MICHOGRAUS PER III EH
Figure 5a -Area of ground-water contamination in the upper unconfined aquifer beyond the boundaries
of the Defense General Supply Center. March 1990.
-------
NATIONAL GUARD AREA
EXPLANATION
v-:-:v:-::::::::y APPBOXIMAIS AREA OF CONIAMINAIIOK
<.-'.'.•.'.•-• X^
BH I us OEOtOOICAl 6UBVET BEDROCK
* WEtl AMD IDENTIFIIfR
133 4 CONCENTRATION OF VOLATILE OBGANICS
IN MltHOOBAMB PER LITER
Figure 55 'Area of ground-water contamination in the middle part bf the lower confined aquifer beyond the
boundaries ol the Defense General Supply Center. March 1990.
-------
FEET
1*°-i CC
110-
100-
90-
80-
70-
60-
50-
40-
30
CC'
Q
^ --- T __ — — — — -------
J A __ — •"" UW€R UNCONFWED AOU*EH
FEET
- 120
-110
- 100
- 90
- 80
- 70
-60
-50
40
too
200 FEET
30
25
SO METERS
VERTICAL SCALE GREATLY EXAGBttTED
DATUM IS NATIONAL GEODETIC VERTICAL DATUM OF 1929
B
309
BOL
EXPLANATION
AREA OF CONTAMMATDN
US. GEOLCOCAL SURVEY MONTCRMG-WEU. CLUSTER
MDOLE OF SCREENED NTERVAL
CONCENTRATION OF VOLATLE-ORGAMC COMPOUNDS.
M MCROGRAUS PER UTER
BELOW DETECTION LMTS
ORECnON OF GROUND-WATER FLOW
Figure 5c-Longitudinal hydrogeologic section of zone of contamination
within the upper and lower aquifers. March 1990.
-------
FEET FEET
120-
1 10-
IOO-
90-
80-
70-
60-
5O-
BB BB1
J
. — *
-*
-•
^
\ A B __J
Wfllttf IAWA!
^™ ^^B5 M^BK 3SS3^—^m~ <«^_ _
BOL
••BOL /'/.
^BOl ^
'S
-•
-BOt
'wsmrn
TiaHiJ:
gittA/--^
284.1
Ilii
^'*.x7:?.-^S-:-; J -»
"
££w-^ $'
Y-V'-V •'/•'.•'.'/.•/.' *
•••'.vv^.-.jx'
D. 1
— . ' • — • ~ —
: UPPER
^BDl
CONFINING
-BDl
LOWER CONFINED
-BDL
-28
D ' '
•
UNCONFINED
AQUIFERgn,
BDL
UNIT
•-BDL
AQUIFER
-BOt
BDL-
*"BDl BOI •
*•
»•
••
0 100 200 300 FEET
lii.
1 1 1 l
0 26 60 76 METERS
-120
-110
- 1 00
-90
- BO
-70
-6O
- 50
- 40
VERTICAL SCALE GREATLY EXAGGERATED
DATUM IS NATIONAL GEODETIC VERTICAL DATUM OF 1989
EXPLANATION '
fxWxl AREA OF CONTAMINATION 137.8 CONCENTRATION OF VOL Mil E -ORGANIC COMPOUNDS.
IN MICftOOMAMS fttt IITEA
B
US QEOlOOICAl SURVEY MONITORING-
Will CLUSTER
BDl BELOW DETECTION LIUIIS
-»•»- MIDDLE OF SCREENED INTERVAL
Figure 5d -Lateral hydrogeologic section of zone ol contamination within the upper
and lower aquifers looking upgradienl. March 1990.
-------
2.6.0 SCUMMY 07 SITE RISKS
2.6.1 CERCLA directs that human health and the environment be protected
from current and potential exposure to hazardous substances. In order to
assess the current and potential risks at DGSC a full risk assessment is
being conducted as part of the RI/PS of OU6. That risk assessment is not
yet complete and is therefore not included in this Record of Decision.
However, the levels of contamination within the Upper and Lower Aquifers
are quite high and it is likely that the Operable Unit presents a
significant potential risk to human health and the environment. Results of
several rounds of groundwater sampling revealed that certain VOCs are
present in the Upper and Lower Aquifers. The concentrations of several
VOCs in the groundwater exceeded the national primary drinking water
standards as established under the Safe Drinking Water Act. Some of the
VOCs detected, including trichloroethene, the most common contaminant at
this Operable Unit, are suspected human carcinogens. Vinyl chloride is a
known human carcinogen which was detected in the groundwater of this
Operable Unit.
Based on a preliminary review, EPA's Regional toxicologist estimates
that the concentrations of vinyl chloride, trichloroethene,
tetrachloroethene, 1,2-dichloroethane, 1,2-dichloropropane, and 1,1-
dichloroethene in groundwater, reported in Table 1, all pose potential
incremental cancer risks above 1.0 x 10~* by the ingestion route alone.
(Incremental cancer risk is a probability that is generally expressed* in -,
scientific notation. An excess lifetime cancer risk of 1.0 x 10~*
indicates that, as a plausible upper bound, an individual has a one in ten
thousand chance of developing cancer as a result of Site-related exposure
to a carcinogen for 30 years of a 70-year lifetime. EPA considers excess
lifetime cancer risks in the range of 1.0 x 10~4 to 1.0 x 10"6 to be
acceptable.) A single risk of that magnitude, alone, would be sufficient
to justify initiation of remedial action. Actual or threatened releases of
hazardous substances from this Operable Unit, if not addressed by
implementing the response action selected in this ROD, may present an
imminent and substantial endangerment to public health, welfare, or the
environment.
Although some metals are present in the groundwater at concentrations
above background levels, their concentrations and extent are less than
those of organic contaminants and they are not thought to present a
significant short-term health risk which would warrant remediation under
this interim action. However, this issue will be further examined during
the development of the detailed risk assessment for OU6.
Environmental risk studies have been conducted at DGSC in the general
area being addressed under OU9. Samples were collected from surface vater
and sediments in No-Name Creek, both upstream and downstream of the area
believed to be affected by the groundwater plume. Low levels of VOCs were
found in the surface vater downstream of the DGSC boundary and chemical
concentrations were found to be above Virginia Surface Water Standards for
several metals. In addition, surface water and sediments were subject to
standard toxicity tests, and the results of these tests are currently being
reviewed. A benthic macroinvertebrate study was performed on No-Name
Creek, with samples collected from both upstream and downstream locations.
As previously stated, while the results of the studies are available, they
are under review by the Region III Interagency Biological Technical
Assistance Group and it is planned that the results of their review will be
factored into the remedy selection for OU6, the final remedial action for
23
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the groundwater in this area.
2.6.2 Toxicity Characteristics of Selected contaminants in Op«rabl« unit
9.
2.6.2.1 Acetone is a colorless liquid with a somewhat sweet odor. It is a
volatile and highly flammable liquid solvent that has many industrial uses,
but which can also occur naturally as a metabolic product released by
plants and animals. Acetone is usually absorbed by inhalation, but can also
be absorbed by dermal contact. Ingestion of acetone can include impaired
motor coordination, dizziness, flushing, sweating, increased heart rate,
nausea, and collapse into stupor, chronic toxicity include irritation and
inflammation of the eyes, nose, throat and gastrointestinal tract. Liver
and kidney damage have also been reported. EPA classifies acetone as a
non-carcinogen.
2.6.2.2 Chlorob«ns«n« is a colorless, flammable liquid with an almond-like
odor. It is manufactured for use as a solvent and as a chemical
intermediate. The primary route of exposure is through inhalation. Acute
toxicity of chlorobenzene is relatively low. The primary target organs for
chlorobenzene are the brain, liver and kidney. Occupational exposure to
chlorobenzene has been correlated with irritation of the eyes and nose,
skin irritation and toxicity of the nervous system. Chlorobenzene is not
classified as a carcinogen.
2.6.2.3 l,2-Dichloroeth«n« is a colorless, flammable liquid generally used
as a solvent for organic materials, dye extraction, perfumes and
thermoplastics. 1,2-Dichloroethene is absorbed through oral, inhalation,
and dermal routes. It is considered acutely toxic when absorbed, with the
principal toxic effects occurring in the lungs and liver. Humans exposed
to high concentrations of 1,2-Dichloroethene have exhibited central nervous
system effects including drowsiness and nausea. Chronic effects of low
doses on humans are unknown.
2.6.2.4 Ethyl B«ns«n«. The major uses of ethyl benzene include use as an
intermediate in the production of styrene, in the manufacture of cellulose
acetate and synthetic rubber, and as a diluent in the paint industry, in
agricultural sprays for insecticides, and in gasoline blends. Primary
routes of exposure include drinking water, breathing air, and touching soil
contaminated with ethyl benzene. Symptoms of short-term human exposure
include irritation to the eyes, nose, throat and skin, dizziness,
drowsiness, weakness and dermatitis. Ethyl benzene may cause liver and
kidney injury.
2.6.2.5 M«thyl«n« Chloride is a colorless, odorless solvent found in
insecticides, metal cleaners, paints and paint removers. Methylene
Chloride is absorbed via inhalation or ingestion. At low doses Methylene
Chloride can interfere with oxygen transport by the blood and result in
cardio-respiratory stress. High exposures are associated with damage to
the central nervous system as well as liver and kidney effects. EPA
classifies Methylene Chloride as a probable human carcinogen.
2.6.2.6 T«traohloro«th«n« is a colorless, nonflammable liquid with a
characteristic order. It is a solvent widely used as a dry-cleaning agent,
a degreaser, a chemical intermediate, and a fumigant. It is readily
absorbed after ingestion or inhalation, but dermal absorption is poor.
Exposure to high concentrations of tetrachloroethene in the atmosphere can
result in dizziness, headache, sleepiness, confusion, nausea, difficulty in
24
-------
speaking and walking, and possibly unconsciousness and death. EPA
classifies Tetrachloroethene as a probable human carcinogen.
2.6.2.7 1,1,1-Trichloroethaae is a colorless liquid with a sweet
characteristic odor. It is used as a solvent for metal cleaning, in
textile processing, as an aerosol propellant and in the manufacture of
other chemicals. 1,1,1-Trichloroethane can enter the body through the
lungs by breathing contaminated air or through the digestive system by
eating or drinking contaminated food or water. Acute exposures to 1,1,1-
Trichloroethane may result in dizziness, and loss of balance and
coordination. Continued breathing of high concentrations of 1,1,1-
Trichloroethane could lead to unconsciousness and death. Animal studies
have shown that breathing 1,1,1-Trichloroethane can cause damage to
breathing passages, lungs and liver. There are also cardiovascular effects
associated with 1,1,1-Trichloroethane.
2.6.2.8 Trichloroethene is a colorless liquid with on odor similar to
ether. The major use of Trichloroethene is as a solvent for degreasing
metal parts. Trichloroethene is not acutely toxic by the inhalation or
oral routes. Human epidemiology studies have not shown a clear connection
between exposure to trichloroethene and increased cancer risk. However
animals exposed to high concentrations of Trichloroethene have developed
cancers in the lungs and liver. Therefore, EPA classifies Trichloroethene
as a probable human carcinogen.
2.6.2.9 Vinyl Chloride is a colorless gas with a mild, sweet odor. It is
used as a refrigerant gas, and in the manufacture of chlorinated compounds.
Acutely toxic exposures in humans affect the central nervous system and
death can result if humans are exposed to high levels. Inhalation of vinyl
chloride has been reported to result in impaired liver function, liver
damage and central nervous system effects. Chronic inhalation exposure has
also resulted in a syndrome known as vinyl chloride disease. Symptoms
include circulatory disturbances in the extremities, and blood, lung, and
liver effects. The USEPA classifies vinyl chloride as a known human
carcinogen.
2.6.2.10 B«ns«n« is a clear, volatile, colorless, highly flammable liquid
with a characteristic odor. Benzene is used as a constituent in motor
fuels, as a solvent for fats, inks, oils, paints, plastics and rubber, as a
chemical intermediate, and in the manufacture of detergents, explosives,
Pharmaceuticals, and dye-stuffs. Exposure to benzene can occur through
skin and eye contract, ingestion and inhalation. Local exposure to benzene
may result in skin and eye irritation and dermatitis. Short-tern exposure
to benzene may lead to central nervous system depression. Headache,
dizziness, nausea, convulsions, coma, and death may result. Long-term
exposure to benzene may lead to blood changes such as anemia. Occupational
exposure to benzene may result in leukemia. EPA has classified benzene as
a Group A human carcinogen.
2.6.2.11 l,2-Diohloro«tlLaae (also known as ethylene dichloride or EDC) is
a colorless, flammable liquid which has a pleasant odor and sweetish taste.
It has a wide variety of uses including the manufacture of polyvinyl
chloride, nylon, viscose rayon, rubber and various plastics. It is a
solvent for resins, asphalt, paint and it is also used as a degreaser, as
an antiknock agent in gasoline, or in the drycleaning industry. The EPA
considers 1,2-Dichloroethane as a class B2 carcinogen, based on evidence
that it causes a variety of tumors in rats and mice and is mutagenic in
bacteria. Inhalation exposure causes headache, dizziness, nausea,
25
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vomiting, abdominal pain, irritation of mucous membranes, and liver and
kidney damage. Dermal exposure may cause dermatitis.
2.6.2.12 1,2-Dichloropropane is a flammable organic liquid miscible with
other organic solvents. 1,2-Dichloropropane caused an increased incidence
of combined adenomas and carcinomas of the liver in male and female rats
and caused a slight increase in mammary adenocarcinomas in female rats.
High concentrations of 1,2-Dichloropropane cause nervous system depression
and narcosis in humans and can adversely affect the liver, kidneys,
adrenals, and heart.
2.6.2.13 1,1-Dichloroethylene (also known as 1,1-Dichloroethene) caused
kidney tumors .in male mice, and leukemia in both male and female mice in
separate inhalation studies. Negative results were obtained in oral
studies involving rats and mice. 1,1-Dichloroethylene is therefore
considered .to be a possible human carcinogen. It has been found to be
embryotoxic and fetotoxic in rats and rabbits via inhalation. Chronic
exposure by rats to low oral doses caused liver changes. Acute exposure to
high doses causes central nervous system depression.
2.6.2.14 Carbon T«trichloride (also known as Tetrachloromethane) is a
colorless liquid with an ether-like odor. Damage to the liver and kidneys
are associated with exposure to carbon tetrachloride in both animals and
humans. Carbon tetrachloride has been found to be carcinogenic in mice,
rats, and hamsters. It is classified by EPA as a probable human
carcinogen.
2.7.0 DBSCRXPTXOlf OF ALTERNATIVES
2.7.1 To accelerate the process of identifying an interim remedy, only a
limited number of groundwater extraction, treatment, and discharge
alternatives for OU9 were identified and evaluated for effectiveness,
implementability, and cost to attain the remedial goals of this interim
action. The alternatives considered are described below.
2.7.2 Three interim remedial action alternatives were identified for
evaluation. They are:
• Alternative 1 - Bo Action
• Alternative 2a - Pump, Treat and Discharge to Bo-Name Creek
• Alternative 2b - Pump, Treat and Return into the upper Aquifer
A fourth alternative which would pump contaminated groundwater from the
aquifers and then discharge the contaminated water into the local sever
system for conveyance to the local Publicly Owned Treatment Works (POTW)
for subsequent treatment and discharge was also briefly considered.
However, the local POTW is already operating at near capacity and does not
have the excess capacity necessary to accept either untreated or treated
groundwater from this interim remedial action. Therefore, the alternative
was not considered further. The three alternatives which were considered
are described below:
2.7.3 Alternative I--BO Action. The HCP requires that a "no action"
alternative be evaluated at every site in order to establish a baseline for
comparison. 40 C.F.R. S 300.430. Under this alternative, no further
action would be taken at this Operable Unit to prevent exposure to the
contaminated media or to reduce risk at the Operable Unit. However,
26
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further remedial action would be evaluated for OU6.
2.7.4 common Elements of Alternatives 2a and 2b—Pump and Treat system.
Most of the components of Alternatives 2a and 2b are the same. Although
specific details of the two systems have not yet been designed, the general
configuration of either system would consist of the following:
2.7.4.1 Groundvater Extraction Trenches and Wells. To minimize further
migration of contamination in the aquifer, a system of recovery trenches
and wells will be installed to intersect groundwater within the Upper and
Lower Aquifers at the downgradient (east) boundary of the National Guard
Area on DGSC property. Trenches or wells will be used to intersect the
Upper Aquifer. Only wells will intersect the Lower Aquifer. Submersible
pumps will be installed in each of the wells so that contaminated
groundwater can be withdrawn. The number of extraction wells and trenches,
well depths, sizes and locations will be determined during the remedial
design phase. In general, the actual design will be site-specific and
intended to efficiently remove more highly contaminated water and to impede
the flow of contaminated groundwater away from the Site. The rate of
groundwater extraction is expected to be between 50 and 100 gallons per
minute from all wells combined.
2.7.4.2 Air-Stripper. A series of pipes will connect the extraction wells
and trenches to an air-stripper located on DGSC property, probably in the
National Guard Area. Air-strippers typically consist of a hollow,
cylindrical tower approximately 20 to 30 feet tall and 2 to 3 feet in
diameter filled with plastic balls (or other material) called "packing".
An air-blower near the base of the tower blows air up through the packing
and out the open top of the tower. Simultaneously, contaminated water is
pumped to the top of the tower and allowed to trickle down through the
packing. After treatment in the air-stripper, the groundwater is expected
to contain concentrations of VOCs equal to or less than the Action Levels
listed in Table 1. Metals will not be removed by this system.
The air passing up through the packing and contaminated water in the
tower evaporates or "strips" away certain volatile organic contaminants
such as the ones encountered at DGSC. However, the contaminants are not
destroyed. They are transferred from groundwater to the air passing
through the air-stripper. To reduce emissions of VOCs to the atmosphere,
VOCs are removed from the air by an air emissions control system such as
Granular Activated Carbon (GAC), or some other effective technology, where
they are adsorbed. If the air-stripper operates at 100 gallons per minute,
and the average concentration of volatile organic compounds in the
groundwater is approximately 1000 parts per billion, then approximately 1.6
pounds of VOCs will be emitted to the air emissions control system each
day. Less than 2 and 1/2 percent of this amount, or less than .04
Ibs./day, will be released to the atmosphere after the air passes through
the air emissions control system. These VOC emissions rates are far below
the limits established in applicable or relevant and appropriate state air
emissions regulations listed in Table 4. The above emissions rates are
also well below the "to be considered" level established by EPA policy
which indicates that sources most in need of air emissions controls are
those with actual VOC emissions rates in excess of 15 Ibs./day in areas
designated as nonattainment for National Ambient Air Quality Standards for
ozone. (See OSWER Directive 9355.0-28—Control of Air Emissions from
Super fund Air Strippers at Super fund Groundvater Sites.) If any GAC wastes
are generated, they will be managed in accordance with the ARARs identified
in Table 4. The ARARs for GAC wastes, which may contain VOCs at
27
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concentrations subject to the Land Disposal Restrictions, 40 C.P.R. Part
268, include, among other things, requirements regarding waste analysis,
proper storage, notification of appropriate treatment standards,
manifesting, and transportation.
2.7.4.3 Monitoring. Air emissions from the air-stripper tower will be
monitored to ensure compliance with applicable or relevant and appropriate
requirements (ARARs) of state and federal environmental laws. See section
2.8.3 and Table 4 below. For either alternative, VOC concentrations in
groundwater would be monitored periodically to evaluate the effectiveness
of the pump and treat system, to provide operational data, and to obtain
data on changes in contaminant concentrations in response to the interim
remedy, which data are needed for the design of the remedial action for
OU6. Monitoring locations and frequency will be determined during the
design phase. Similarly, monitoring of the air-stripper, groundwater
treated by the air-stripper, and air emissions from control equipment will
be planned during the design phase to ensure that the air-stripper is
effective.
2.7.4.4 Treated Groundvater Management. After the groundwater passes
through the air-stripper most of the organic contaminants will have been
removed from the groundwater. The treated groundwater will be discharged
from the air-stripper at the same rate that contaminated groundwater is
pumped from the ground. Alternatives 2a and 2b, described below, are two
options available for the discharge of the treated groundwater.
2.7.5.1 Alternative 2a~PUB?, Treat, and Discharge to Ho-Haae Creak.
capital Cost: $398,118
Annual O«M Costs: $ 46,000
Months to Implement: 8
Present worth Costst $561,234
After groundwater from the Upper and Lower Aquifers is extracted from
the trenches and wells, and treated in an air-stripper as described above,
the groundwater would be discharged to No Name Creek. See Figure 6. The
groundwater extraction and treatment system would be designed and operated
in accordance with the ARARs listed in Table 4.
The discharge of treated groundwater to No Name Creek would comply
with the ARARs listed in Table 4 with the possible exceptions of Virginia
Surface Water Standards for three metals (selenium, lead, and zinc), for
which the highest concentrations observed in groundwater exceeded those
Standards. See Tables 2 and 3. The Virginia Water Quality Standards are
the basis of effluent limits, established pursuant to the Virginia
Pollutant Discharge Elimination System (VPDES), for surface water
discharges. The substantive requirements of the VPDES would be ARARs for
on-site discharges of treated groundwater to surface water. ("On-site"
includes "all suitable areas in very close proximity to the contamination
necessary for implementation of the response action.11) 40 C.F.R. $
300.400(e). Because the concentrations of these metals in the groundwater
vary spatially and temporally, their concentrations in extracted
groundwater cannot be predicted before the remedy is designed or becomes
operational. Therefore, there is a possibility that the concentrations of
one or more of these metals in the treated water might exceed the Virginia
Surface Water Standards if this Alternative were selected. Consequently,
either a waiver of compliance with those Standards might be required
pursuant to section 300.430(f)(l)(ii)(C) of the NCP or additional treatment
28
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(ac additional cost) might be required to remove these metals from the
water prior to its discharge to the Creek.
2.7.5.2 Alternative 2b - Pump, Treat, and Return to the tipper Aquifer.
Capital Cost: $430,951
Annual O&M Costs: $ 46,000
Months to Implement: 8
Present worth Costs: $594,067
Alternative 2b is identical to Alternative 2a from the extraction
wells and trenches to the air-stripper discharge. However, beyond the air
stripper discharge, the management of the treated water varies between the
two systems. See Figure 7. In Alternative 2a, the treated water would be
discharged to No-Name Creek. In Alternative 2b, the treated water would be
discharged to a series of infiltration trenches located on DGSC property as
shown in Figure 8. As with Alternative 2a, it is expected that this in-
terim remedy would become part of a total remedial action that would attain
ARARs. As discussed above, the groundwater extraction and treatment system
would be designed and operated r.n compliance with the ARARs listed in Table
4.
The discharge of treated groundwater to the infiltration trenches
would comply with the ARARs listed in Table 4. Although certain metals
might be discharged at concentrations exceeding the numerical limits of the
Virginia Groundwater Standards, this discharge would nevertheless comply
with those Standards because the only source of the metals discharged will
be the aquifer from which the water is being pumped for treatment and the
metals discharged will be the same as those contained in the groundwater
originally.
2.7.6 implementation Requirements and Schedule. The interim action at OU9
is scheduled to become operational by July 1995 (estimated). The interim
remedy would continue to operate until the OU6 final remedy becomes
operational.
29
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DGSC OPERABLE UNIT
INTERIM REMEDIAL ACTION
ALTERNATIVE 2A
NO NAME CREEK
. IHEAIEU UATEH OISCMAME
CONT«1INnlEO
* A90VE Ntl-S '
c:\d9ii\uu97a.dgn Hay. % 1933 11.40:
Figure 6
-------
DGSC OPERABLE UNIT S
INTERIM REMEDIAL ACTION
ALTERNATIVE 2B
RETURN IHEATED WATER
BACK TO AOUII-LH
AIR STRIPPER
6) HATCH DISCHARGE 10 fERCOI. Al I UN THEICH
CHOUNOHA1ER CUIirMllrMIEO
teavt
AI WJ.S
Nay. &>. 1933 11:42:48
Figure 7
-------
2.7.7 Assumption*, Limitations and Uncertainties. A major assumption
contained in this document is that pump and air-strip technology will be
effective at this Operable Unit. At some sites where groundwater can be
efficiently extracted and treated, groundwater contamination is not always
reduced to the desired concentrations or in accordance with predicted
schedules. This situation is a particular problem when Dense Non-aqueous
Phase Liquids are present, which is not thought to be the case at DGSC.
DLA believes that the selected interim action will be effective at DGSC.
In addition, since this is only an interim measure, the effectiveness of
this system will be carefully assessed and will be an important evaluation
factor during the selection of the final remedial measure for OU6.
2.7.8.0 Physical Effect* on the Environment. Factors affecting the
environment which must be considered when evaluating the pump and treat
alternatives include aquifer draw down and disposal of the treated
groundwater. Treated groundwater will be discharged to infiltration
trenches if Alternative 2b is implemented. If Alternative 2a is
implemented the groundwater will be discharged to No Name Creek. The
effects of these alternate methods of handling the treated groundwater are
discussed in greater detail below.
2.7.8.X Alternative 2a. No Name Creek in the vicinity of the NGA is an
ephemeral stream and has very low flows. Alternative 2a would discharge
approximately 50 to 100 gallons per minute to the Creek. However,
contaminated groundwater from the Upper Aquifer naturally discharges -into
the Creek currently, so the net effect of the discharge on flow rates in
the Creek would be less than 50 to 100 gallons per minute.
Because the water removed from the aquifer would not be replaced under
Alternative 2a, groundwater levels of the Upper Aquifer would decrease in
the vicinity of the groundwater extraction wells and trenches.
2.7.8.2 Alternative 2b. In Alternative 2b, treated groundwater would be
discharged to infiltration trenches in the OSA/Area 50/NGA. Because the
overall rate of groundwater extraction would equal the rate of treated
water discharge to infiltration trenches, there would not be a widespread
impact on groundwater. However, there would be localized areas of
groundwater mounding and groundwater depressions in the vicinity of the
plume. The water level elevation of the Upper Aquifer may decrease
significantly in the vicinity of extraction wells and trenches. The
groundwater level near the infiltration trenches would rise. However DLA
and EPA do not anticipate major changes in groundwater levels east of No
Name Creek.
with respect to stream flow changes, No Name Creek has been found to
be a gaining stream (i.e., groundwater enters the Creek) in the area where
it flows off the DGSC property. While the installation of an upgradient
intercepting trench system could be expected to temporarily reduce stream
flow, as the return flow reaches the creek watershed, steady state
conditions are expected to develop which would result in return to near
normal conditions. The operational controls for the remedy will be
developed to take this point into consideration. The overall impact to the
environment would be expected to be negligible. Accordingly, Alternative
2b would be an appropriate interim measure.
32
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2.8.0 SUMMARY OT THB COMPARATIVE AKALY8I8 OF ALTERNATIVES
2.8.1 Below, each of the remedial action alternatives are compared on the
basis of the nine evaluation criteria set forth in the NCP at 40 C.F.R.
Section 300.430(e)(9). The information used in this comparison is derived
mainly from the Focused Feasibility Study Report for QSA/Area 50/NGA Ground
Water (Operable Unit 6]_f Law Environmental, Inc. April, 1993; Ground-Water
Contamination and Movement at the Defense General Supply Center. U.S.
Geological Survey, Richmond, Va., 1990; and, Remedial Investigation for
Area 50/Open Storage Area/Nat1. Guard Area. Dames & Moore, July, 1989,
along with drafts of the OU9 Proposed Plan and ROD. All of these documents
are in the administrative record file maintained by DGSC. The nine
criteria are categorized below into three groups: threshold criteria,
primary balancing criteria, and modifying criteria.
THRESHOLD CRITERIA
1. Overall protection of human health and the environment; and
2. Compliance with applicable or relevant and appropriate
requirements (ARARs).
PRIMARY ?^TfMiCIMO CRITERIA
3. Long-term effectiveness and permanence;
4. Reduction of toxicity, mobility, or volume through treatment;
5. Short-term effectiveness;
6. Implementability; and
7. Cost.
MODIFYING CRITERIA
8. State/Support Agency acceptance; and
9. Community acceptance.
These evaluation criteria relate directly to requirements in Section
121 of CERCLA, 42 U.S.C. S 9621, which determine the overall feasibility
and acceptability of the remedy.
Threshold criteria must be satisfied in order for a remedy to be
eligible for selection. Primary balancing criteria are used to weigh major
trade-offs between remedies. State/Support Agency and community acceptance
are modifying criteria formally taken into account after public comment is
received on the Proposed Plan. A summary of the relative performance of
the alternatives with respect to each of the nine criteria follows. This
summary provides the basis for determining which alternative provides the
"best balance" of tradeoffs with respect to the nine evaluation criteria.
2.8.2 overall Protection of Buvan Health and the Environment. A primary
requirement of CERCLA is that the selected remedial action be protective of
human health and the environment. A remedy is protective if it reduces
current and potential risks to acceptable levels within the established
risk range posed by each exposure pathway at the operable unit.
The No Action alternative would not be protective of human health and
the environment because it allows the contaminants to continue to migrate
away from the Site. The No Action alternative would not eliminate any
exposure pathways or reduce the level of risk. Therefore, the No Action
alternative will not be considered further in this analysis as an option
33
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for this Operable Unit.
Both of the Pump and Treat Alternatives would protect human health and
the environment by reducing or controlling the risk through treatment to
begin reducing the concentration and volume of contaminants in the
groundwater and by inhibiting the migration of contaminated groundwater in
the aquifers. However, the concentrations of contaminants in the
groundwater vary spatially and temporally and the concentrations of metals
that will remain in groundwater after it is treated to remove VOCs cannot
be predicted before the remedy is designed or operational. Thus, it is
anticipated that the treated water effluent produced by Alternative 2a
would contain certain metals, possibly in excess of applicable Virginia
Surface Water Standards, since these metals were present at such
concentrations in the most contaminated well samples. Alternative 2b would
not include surface water discharge of the treated groundwater, but: would
discharge treated groundwater to an area that is already contaminated.
Because Alternative 2a, which includes surface water discharge of treated
water, poses the possibility of producing treated water effluent containing
certain metals at concentrations exceeding Virginia Surface Hater
Standards, Alternative 2b is considered more protective of the environment.
2.8.3 Compliance vith Applicable or Relevant and Appropriate Requirements
(ARARs). This criterion addresses whether a remedy will meet ARARs or
provide grounds for invoking a waiver under the NCP at 40 C.F.R. Section
300.430(f)(1)(ii)(C). Under Section 121(d) of CERCLA, 42 U.S.C. Section
9621(d), remedial actions at CERCLA sites must attain applicable or
relevant and appropriate standards, requirements, criteria, and limitations
(collectively referred to as "ARARs") under federal environmental laws and
promulgated State environmental or facility siting laws, unless such ARARs
are waived pursuant to Section 121(d)(4) of CERCLA, 42 U.S.C. Section
9621(d)(4). See Table 4. Section 300.5 of the NCP defines "applicable
requirements" as "those cleanup standards, standards of control, and other
substantive requirements, criteria, or limitations promulgated under
federal environmental or state environmental or facility siting laws that
specifically address a hazardous substance, pollutant, contaminant,
remedial action, location, or other circumstance found at a CERCLA site."
"Relevant and appropriate requirements" are defined as "those cleanup
standards, standards of control and other substantive requirements,
criteria, or limitations promulgated under federal environmental or state
environmental or facility siting laws that, while not 'applicable' to a
hazardous substance, pollutant, contaminant, remedial action, location, or
other circumstance at a CERCLA site, address problems or situations
sufficiently similar to those encountered at the CERCLA site that their use
is well suited to the particular site." 40 C.F.R. S 300.5.
In addition to ARARs, Table 4 lists "to-be-considered" (TBC) material
identified as useful in evaluating and selecting this remedy. TBC material
may include advisories, criteria, or guidance to be considered for a
particular release. CERCLA does not require compliance with this TBC
material. As in other aspects of this interim remedial action, the
identified ARARs and TBCa relate only to the selection of an interim
remedial action for OU9 and not to the final remedial action which will be
selected at a later date for OU6.
All aspects of Alternative 2b, including groundwater extraction,
treatment, and discharge to infiltration trenches, air emissions, and
management of VOC-contaminated 6AC waste, would comply with the ARARs
identified in Table 4. With one exception discussed in the next paragraph,
34
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all aspects of Alternative 2a would also comply with the ARARs identified
in Table 4. Both Alternatives 2a and 2b would treat extracted groundwater
to meet all currently promulgated federal and state water quality standards
for VOCs in surface water or groundwater. See Table 1 for the VOC levels
which these Alternatives would meet. Additionally, the air-stripper used
in these Alternatives will be designed with an air emissions control system
to meet all substantive and applicable requirements of Virginia air quality
regulations listed in Table 4.
As previously stated, the discharge of treated groundwater to No Name
Creek under Alternative 2a would comply with the ARARs listed in Table 4
with the possible exception of Virginia Surface Water Standards for
selenium, lead, and zinc which were measured in the groundwater at
concentrations exceeding those Standards. See Tables 2 and 3. In order to
implement Alternative 2a, either a waiver of compliance with the Virginia
Surface Water Standards pursuant to section 300.430(f)(1)(ii)(C) of the NCP
or additional treatment to remove metals might be necessary. Alternative
2b would comply with all pertinent ARARs listed in Table 4. Because of the
uncertainty regarding the ability of Alternative 2a to comply with the
Virginia Surface Water Standards for certain metals, Alternative 2b is
considered a better choice than Alternative 2a with reference to this
criterion.
The final cleanup levels for contaminated groundwater remaining in the
aquifer are not addressed in this ROD because such goals are beyond the
scope of the selected interim remedial action, the purposes of which are
limited to begin reducing the potential for current or future exposures to
the contaminated groundwater in the Upper and Lower Aquifers, reducing the
migration and dispersion of contaminants in groundwater of OU9, and
obtaining data on changes in the aquifer and contaminant concentrations in
response to the pump and treat system as a method for decontaminating
groundwater at this Operable Unit. Thus, the ARARs that pertain to this
interim action are simply those that relate to groundwater extraction,
treatment to remove VOCs from extracted groundwater, management of wastes
(e.g., spent activated carbon) generated during groundwater treatment, and
discharge of treated groundwater. The question of whether or not MCLs,
MCLGs, or chemical-specific ARARs are attained in the aquifer itself is
beyond the scope of this interim remedy. The final cleanup levels for the
aquifer will be addressed in the final remedial action ROD for OU6.
On-site activities will also be performed in compliance with other
applicable legal requirements (e.g., worker health and safety laws and
regulations, see 40 C.F.R. S 300.150) that are not within the scope of
federal environmental or state environmental or facility siting laws. Off-
site activities (e.g., off-site transportation, treatment, or disposal of
spent activated carbon) performed under this interim remedial action will
comply with all applicable laws and regulations.
35
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TABLE 4
APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS (ARARs)
AND "TO BE CONSIDERED11 MATERIAL (TBCa)
Area 50 Landfill, Open Storage Area, and National Guard Area—Groundwater
Operable Dnit 9
Defense G«n«ral Supply Center, Richmond, Virginia..
Standards,
requirements, Description of Alternatives
criteria, and affected Nature of affected by
limitations Citation activities Requirement Requirement
Non-zero Maximum 40 C.F.R. Discharge of Relevant and 2b
Contaminant Level Part 141, treated appropriate
Goals (MCLGs) and Subparts F groundwater
MCLs promulgated and G into trenches
under the Safe
Drinking Hater Act,
42 U.S.C. S 300f to
300J-26. See Table
1 for MCLs and MCLGs
relevant to this
Operable Unit.
Underground 40 C.F.R. Discharge of Applicable 2b
Injection Control Part 146, treated
Program: Criteria Subpart F groundwater
and Standards into trenches
36
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TABLE 4 (OODt.)
APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS (ARARa)
AMD "TO BE CONSIDERED1* MATERIAL (TBCs)
Area SO Landfill, Open Storage Area, and National Guard Ar«a—oroundwator
Operabla Unit 9
Dafansa o«n«ral Supply Cantor, Richmond, Virginia
Standards ,
requirements,
criter la, and
limitations
Citation
Description of
affected
activities
Nature of
Requirement
Alternatives
affected by
Requirement
Virginia Groundwater
Standards
Commonwealth of
Virginia Regulations
for the Control and
Abatement of Air
Pollution—Emission
Standards for Odor;
Emission Standards
for Toxic
Pollutants;
Standards of
Performance for
Toxic Pollutants
VR680-21-04
VR
120-04-01,
120-04-02,
120-04-03,
120-05-03
Discharge of
treated
groundwater
into trenches
Atmospheric
emissions from
air-stripper
Applicable
Relevant and
Appropriate
2b
2a & 2b
37
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TABLE 4 (cont.)
APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS (ARARs)
AND "TO BE CONSIDERED" MATERIAL (TBCs)
Area 50 Landfill, Open Storage Area, and National Guard Area"-Groundwater
Operable Unit 9
Defense General Supply Center, Richmond, Virginia
Standards ,
requirements,
criteria, and
limitations
Citation
Description of
affected
activities
Nature of
Requirement
Alternat ives
affected by
Requirement
Standards for Owners
and Operators of
Hazardous Waste
Treatment, Storage,
and Disposal
Facilities—Air
Emission Standards
for Process Vents
and Equipment Leaks
VA Hazardous Waste
Management
Regulations (VHWMR)
VR 672-10-1—
Identification and
Listing of Hazardous
Wastes; Notification
of Hazardous Waste
Management Activity;
Manifest Regulations
for Hazardous Waste
Management;
Regulations
Applicable to
Generators of
Hazardous Waste;
Regulations
40 C.F.R.
Part 264,
Subparts AA
and BB
VHWMR, Parts
III, IV, V,
VI, VII, and
X
Atmospheric
emissions from
air-stripper
Treatment of
groundwater.
On-site
management,
manifesting,
and off-site
transport of
spent
activated
carbon used to
control air
emissions from
air-stripper.
Relevant and
Appropriate
2a & 2b
Applicable
2a & 2b
38
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TABLE 4 (OOnt.)
APPLICABLE OR RELEVANT AMD APPROPRIATE REQUIREMENTS (ARARs)
AND "TO BE CONSIDERED11 MATERIAL (TBC0)
Area 50 Landfill, Open Storage Area, and National Guard Area—Oroundvatar
Operable Unit 9
Defense Oanaral Supply Cantar, Richmond, Virginia
Standards ,
requirements,
criteria, and
limitations
Citation
Description of
affected
activities
Nature of
Requirement
Alternatives
affected by
Requirement
Applicable to
Transporters of
Hazardous Waste;
Standards for Owners
and Operators of
Hazardous Haste
Treatment, Storage,
and Disposal
Facilities
39
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TABLE 4 (oont.)
APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS (ARARs)
AND "TO BE CONSIDERED" MATERIAL (TBCs)
50 Landfill, Open Storage Area, and National Guard Area—broundwater
operable OnIt 9
Defense General Supply Canter, Richmond, Virginia
Standards ,
requirements ,
criteria, and
limitations .
Citation
Description of
affected
activities
Nature of
Requirement
Alternatives
affected by
Requirement
Land Disposal
Restrictions
40 c.F.R.
Part 268
Corrective Action
for Solid Waste
Management Units
40 c.F.R.
Part 264,
Subpart F
Notification
(S 268.7),
storage (S
268.50),
manifesting,
and off-site
transportation
requirements
applicable to
spent
activated
carbon used to
control air
emissions from
air-stripper
Groundwater
extraction and
discharge to
infiltration
trenches
Applicable
2a & 2b
Relevant and
Appropriate
2a & 2b
40
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TABLE 4 (oont.)
APPLICABLE OR RELEVANT AMD APPROPRIATE REQUIREMENTS (ARARs)
AMD "TO BE CONSIDERED" MATERIAL (TBCs)
Area 50 Landfill, Open storage Area, and National Guard Araa—Oroundwatar
Oparabla Unit 9
Dafanaa General Supply Cantar, Richmond, Virginia
Standards ,
requirements ,
criteria, and
limitations
Citation
Description of
affected
activities
Nature of
Requirement
Alternatives
affected by
Requirement
VA Surface Water
Standards With
General, Statewide
Application, used in
conjunction with the
VA Pollutant
Discharge
Elimination System
to establish
contaminant limits
for discharges to
surface water
Endangered Species
Act of 1973
VA Endangered
Species Act
VA Wetlands
Regulations
VR 680-21-01
and 680-14-01
16 U.S.C. SS
1531-1544
Va. Code SS
29.1-563 et
sag.
VR 450-01-
0051
Discharge of
treated
groundwater to
surface water
Applicable
2a
Groundwater
extraction and
discharge
Groundwater
extraction and
discharge
Groundwater
extraction and
discharge
Applicable
Applicable
Applicable
2a & 2b
2a & 2b
2a & 2b
41
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TABLE 4 (oont.)
APPLICABLE OR RELEVANT AMD APPROPRIATE REQUIREMENTS (ARARa)
AND "TO BE CONSIDERED** MATERIAL (TBCs)
Area 90 Landfill, Open Storage Area, and National Guard Araa—Oroundwatar
Oparabla unit 9
Defense General Supply Canter, Richmond, Virginia
Standards ,
requirements,
criteria, and
limitations
Citation
Description of
affected
activities
Nature of
Requirement
Alternatives
affected by
Requirement
Wetlands Protection
VA Stormwater
Management
Regulations
Chesapeake Bay
Preservation Area
Designation and
Management
Regulations
Guidelines for
Specification of
Disposal Sites for
Dredged or Fill
Material
40 C.F.R. S
6.302 and Pt.
6, App. A,
E.O. 11990
VR 215-02-00
VA Code SS
10.2100 et
aeq.; VR 173-
02-01
40 C.F.R.
Parts 230
232
and
Groundwater
extraction and
discharge
Treatment
system
construction
and
maintenance
Treatment
system
construction
and
maintenance
Treatment
system
construction
Applicable
Applicable
2a & 2b
2a & 2b
Applicable
2a & 2b
Applicable
2a & 2b
42
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TABLE 4 (oont.)
APPLICABLE OR RELEVANT AMD APPROPRIATE REQUIREMENTS (ARARs)
AND "TO BE CONSIDERED*' MATERIAL (TBCs)
Area SO Landfill, open Storage Area, and National Guard Araa—oroundwater
Operable Unit 9
Defense General Supply Center, Richmond, Virginia
Standards ,
requirements ,
criteria, and
limitations
Citation
Description of
a f f e c t e d
activities
Nature of
Requirement
Alternatives
affected by
Requirement
Control of Air
Emissions from
Super/und Air
Strippers at
Super/und
GroundVater Sites.
OSWER
Directive
9355.0-28
Groundwater
remediation
generally
TBC
2a & 2b
43
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2.8.4 Long-Term. Effectiveness and Permanence. This evaluation criterion
addresses the long-term protection of human health and the environment once
remedial action cleanup goals have been achieved, and focuses on residual
risks that will remain after completion of the remedial action.
Extraction and treatment of contaminants in the Upper and Lower
Aquifers will reduce groundwater contamination and will enhance the
attainment of a permanent remedy for these aquifers. With reference to
permanence, both alternatives would permanently remove VOCs from the
groundwater extracted from the contaminated plume. Again, with reference
to permanence, both Alternatives 2a and 2b are similar in that they are
interim actions designed to function only until the remedy selected in the
final ROD for this area can be implemented. Finally, Alternatives 2a and
2b would be about equally effective in that both would remove the same
amount of VOCs and would produce operational data that could be used to
accelerate selection and implementation of the final remedy.
2.8.5 Reduction of Mobility, Toxicity, and Volume Through Treatment. This
evaluation criterion addresses the degree to which a technology or remedial
alternative reduces the toxicity, mobility, or volume of a hazardous
substance. Section 121(b) of CERCLA, 42 U.S.C. Section 9621(b),
establishes a preference for remedial actions that permanently and
significantly reduce the toxicity, mobility, or volume of hazardous
substances. A combination of treatment and engineering controls may be
used, as appropriate, to achieve protection of human health and the
environment, as set forth in the NCP at 40 C.F.R. Section 300.430(a)(iii).
Treatment should be utilized to address the principal threats (such as
liquids, high concentrations of toxic compounds, and highly mobile
materials) presented by a site and engineering controls such as containment
will be considered for wastes that pose a relatively low long term threat
or where treatment is impracticable. See 40 C.F.R. S 300.430(a)(iii).
The pump and treat system of both Alternatives 2a and 2b would reduce
the toxicity, mobility, and volume of the contaminants in the extracted
groundwater from the upper and Lower Aquifers. Air-stripping of VOCs is a
proven treatment process which has been demonstrated to effectively reduce
voc contamination by forcing an air stream through the water and causing
the compounds to evaporate. Then, the activated carbon emissions control
system would adsorb the compounds with the result that final emissions
would be nearly at non-detect levels. Spent activated carbon would be
removed from the system and incinerated or regenerated, resulting in the
destruction of contaminants.
By pumping groundwater from the most contaminated areas of the Upper
and Lower Aquifers, both Alternatives 2a and 2b would reduce the mobility
of the contaminants by inhibiting the migration of contaminated groundwater
in the aquifers. The discharge of treated groundwater to infiltration
trenches under Alternative 2b could potentially further mobilize
contaminants in the source area, however, this potential problem can be
mitigated during the design phase. However, Alternative 2a might increase
the movement of certain metal contaminants into No Name Creek and thus
would be less desirable than Alternative 2b from this perspective.
2.8.6 Short-Term Effectiveness. This evaluation criterion addresses the
period of time needed to achieve protection of human health and the
environment, and any adverse impacts that may be posed during the
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construction and implementation period of a remedy, until cleanup goals are
achieved.
Both Alternatives 2a and 2b would be effective in the short-term
because they would prevent further degradation of groundwater quality and
would initiate reduction in toxicity, mobility, and volume of VOC
contamination until a final action is selected and implemented. However,
Alternative 2a would possibly increase the rate of discharge into Mo Name
Creek of certain metallic contaminants at concentrations exceeding Virginia
Surface Water Standards. No adverse effects on human health or the en-
vironment are expected from Alternative 2b.
Any short-term risk to workers involved in construction of the remedy
would be reduced through implementation of a health and safety plan.
2.8.7 Xaplemeatability. This evaluation criterion addresses the technical
and administrative feasibility of each remedy, including the availability
of materials and services needed to implement the chosen remedy.
The pump and treat system is a treatment process which has been
demonstrated to effectively reduce VOC contamination at many other NFL
sites. Air-stripping technology is relatively simple and well-understood.
The design stage can be completed in approximately eight months. There are
many sources of air-stripping technology and equipment available for use at
DGSC and no unusual services or materials are required. Alternative 2a,
stream discharge, would probably require a discharge point into No-Name
Creek which is located outside the DGSC boundary, and a delay to obtain
access would be a possibility. Alternative 2b would be implemented
entirely on property under the control of DGSC.
2.8.8 Cost. Section 121 of CERCLA, 42 U.S.C. Section 9621, requires
selection of a cost-effective remedy that protects human health and the
environment and meets the other requirements of the statute. The
alternatives are compared with respect to present worth cost, which
includes all capital costs and the operation and maintenance costs incurred
over the life of the project. Capital costs include those expenditures
necessary to implement a remedial action, including construction costs.
The estimated costs consist of capital, operating, and present worth
values. The capital costs of the two Alternatives ($398,118 for
Alternative 2a versus $430,951 for Alternative 2b) are nearly equivalent,
which reflects the similarity between them. Also, the difference between
the two estimates is not very significant because it is in the range of the
uncertainty inherent in preliminary estimates of construction costs. A
present worth analysis of each Alternative provided estimates of $561,234
for Alternative 2a and $594,067 for Alternative 2b, also indicating that
the cost of either Alternative is about the same.
2.8.9 State/Support Agency Acceptance. This criterion indicates whether,
based on its review of the RI/FS and Proposed Plan, the State and/or the
Support Agency concurs with, opposes, or has no commment on the preferred
alternative.
The Virginia Department of Environmental Quality (VDEQ) served as the
support agency for the Commonwealth of Virginia. VDEQ has reviewed the
remedial alternatives under consideration for the DGSC Site and has
45
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provided EPA with technical and administrative requirements for the
Commonwealth of Virginia. VDEQ agrees with the analysis of alternatives
presented in this ROD.
Both the EPA and the Commonwealth of Virginia, upon review of the
Proposed Plan, concur in the selection of the Pump and Treat Alternative 2b
as an interim remedial action for DGSC OU9.
2.8.10 Community Acceptance. This criterion includes a determination of
which components of the alternatives interested persons in the community
support, have reservations about, or oppose based on public comments.
On June 2, 1993, a public meeting was held at the Be11wood Elementary
School, near Richmond, Virginia to discuss the preferred alternative as
described in the Proposed Plan. A public comment period for the Proposed
Plan was held from May 3, 1993 through June 17, 1993. Comments received
during the public meeting and the public comment period are discussed in
the Responsiveness Summary attached to this ROD.
2.9.0 SELECTED REMEDY
2.9.1 General Description of the Selected Remedy. Based upon consideration
of the requirements of CERCLA, the detailed analysis of the alternatives,
and public comments, DLA has selected Alternative 2b (Pump, Treat and
Discharge into the Upper Aquifer) as the interim remedial action for the
OU9. This action will achieve significant risk reduction early in the
remedial process. The system will include the following basic components.
Contaminated groundwater will be captured and removed from the Upper and
Lower Aquifers through a series of extraction wells and trenches. Specific
well locations and pumping rates have not yet been determined. However,
initial evaluation is that the pumping rate will be between 50 and 100
gallons per minute. The water from the extraction wells and trenches will
be transported to a centrally located air-stripper and treated. Following
treatment, the groundwater will be discharged to a series of infiltration
trenches located on DGSC property. See Figure 8.
The trenches are expected to be approximately ten feet deep and 600 to
1200 feet long. Air emissions from the air-stripper will be controlled
with an activated carbon adsorption system. The interim system will be
operated until the final ROD for OU6 is implemented. During this interim
action, the air-stripper is expected to reduce VOC contaminant
concentrations in treated groundwater to below the action levels shown in
Table 1 prior to discharging it to infiltration trenches.
The selected remedy includes a groundwater monitoring program that
will be developed and implemented during the remedial design and remedial
action phases. Similarly, the treatment process itself will be monitored
with respect both to the quantity and quality of the return flow, as well
as to the air emissions control system.
2.9.2 Treatability Testing. Because pump and treat technology is well
understood, and because this interim remedial action is not the final
action, detailed treatability testing will not be performed at this
Operable Unit. However, it is possible that limited additional chemical
analysis of the groundwater will be performed during the design phase in
46
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order to determine if any special pre-treatment or post-treatment of the
water is necessary. During construction of the extraction wells, well
development tests will be conducted on each well as it is completed. The
number, spacing, and pumping rate of the wells and trenches will be
adjusted according to the results of these tests. Some minor changes may
be made to the design of this remedy as a result of these tests.
47
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I
a
LEGEND
KTTB BUILDINGS
SQUNOARr
OF SUPPLY
CENTER
DGSC RICHMOND OUS
INTERIM REMEDIAL ACTION
FIGURE 8
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2.10.0 STATUTORY. DETERMXKATIOHS
2.10.1 To meet the statutory requirements of CERCIA Section 121, the
selected remedy must:
• Be protective of human health and the environment;
• Comply with ARARs (or justify an ARARs waiver);
• Be cost effective;
• Utilize permanent solutions and alternative treatment
technologies to the maximum extent practicable; and
• Satisfy the preference for treatment that reduces toxicity,
mobility/ or volume as a principal element, or provide an
explanation as to why this preference is not satisfied.
2.10.2 How the selected remedy complies with each of these requirements is
summarized below:
2.10.2.1 Protection of Human Health and Environment. The Upper and Lower
Aquifer system is a current source of drinking water in the area of DGSC
and therefore presents a potential threat to human health and the
environment. Although no wells used currently for residential drinking
water supply are believed to be contaminated at the present time, the
interim action will provide protection of human health for users through
extraction and treatment of contaminated groundwater until a final action
is determined. The remedy also provides protection to human health and the
environment by inhibiting the spread of contamination to wells that are not
currently contaminated.
2.10.2.2 Compliance with ARARs. The selected remedy will treat extracted
groundwater to meet all Federal MCLGs and MCLs for VOCs applicable to this
interim action. Additionally, the air-stripper and air emissions control
system will be designed to meet substantive and applicable State air
quality regulations, as well as all other ARARs listed in Table 4.
Finally, all components of the pump, treat, and discharge system will be
constructed and operated in accordance with the pertinent ARARs identified
in Table 4.
2.10.2.3 Cost-Effectiveness. Section 300.430(f)(1)(ii)(D) of the NCP, 40
C.F.R. S 300.430(f)(1)(ii)(D), requires that the selected remedy be cost-
effective. That section of the NCP states that cost-effectiveness is
determined by first evaluating the following three of the five "balancing"
criteria to determine overall effectiveness of the remedy: long-term
effectiveness and permanence, reduction of toxicity, mobility, or volume
through treatment, and short-term effectiveness. Overall effectiveness is
then compared to cost to ensure that the remedy is cost-effective. A
remedy is cost-effective if its costs are proportional to its overall
effectiveness. The interim remedy selected for OU9 will employ a proven
technology which can be implemented year round to begin permanently
removing VOCs from groundwater and to inhibit the spread of groundwater
contamination until a final remedy is implemented. The remedy can be
constructed in less than a year and will begin removing VOCs and limiting
the spread of contaminated groundwater as soon as it is operational. The
remedy will also be effective in the short-term as explained in section
2.8.6 above. The projected cost of this interim remedial action is
proportional to its overall effectiveness as evaluated by the above
criteria. Therefore, this remedy is cost-effective.
49
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2.10.2.4 utilisation of permanent solutions and Alternative Treatment
Technologies to the Maximum Extent Practicable. The selected remedy is not
designed or expected to be final, however, in light of its limited scope,
it provides the best balance of trade-offs in terms of long-term
effectiveness and permanence, reduction in toxicity, mobility, or volume
through treatment, short-term effectiveness, implementability, and cost,
while also considering the statutory preference for treatment as a
principal element and considering state and community acceptance. The
objectives of this interim remedial action are to begin reducing the
potential for current or future exposure to contaminated groundwater in the
Upper and Lower Aquifers, through treatment and containment, and to reduce
the migration of contaminants. Extraction and treatment of contaminants in
the Upper and Lower Aquifers by the selected remedy will immediately begin
to achieve significant reduction in the risk at the Site in the short-term
by inhibiting the spread of contaminated groundwater and by permanently
removing a portion of the VOCs, and will enhance implementation of a final
remedy for this Operable Unit by providing operational data for use in
selecting and designing the final action for OU6. Utilization of a
permanent solution will be addressed in the final decision document for
OU6.
2.10.2.5 Preference for Treatment as a Principal Element. Because this
remedy does not constitute the final remedy for the Operable Unit, the
statutory preference for remedies that employ treatment that reduces
toxicity, mobility, or volume as a principal element, although partially
addressed in this remedy, will be addressed by the final response action.
The Pump and Treat remedy is a treatment process which has been
demonstrated to effectively reduce VOC contamination of groundwater at
other NPL sites. The VOCs removed by the air-stripper will be captured by
air emissions controls and taken off-site for incineration or other
treatment.
2.10.2.6 Documentation of Significant Changes. The Interim Proposed Plan
for OU9 was released to the public on May 3, 1993. .The Proposed Plan
identified Alternative 2b - Pump, Treat and Discharge to the Upper Aquifer
as the preferred alternative. All written and verbal comments submitted
during the public comment period were reviewed. Upon review of the
comments it was determined that no significant changes to the alternative,
as it was originally identified in the Proposed Plan, were necessary prior
to it becoming the selected remedy.
50
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APPENDIX A
BIBLIOGRAPHY
Dames and Moore/ 1989. U.S. Army Corps of Engineers, Norfolk
District. "Remedial investigation Area 50, Open Storage
Area/ and National Guard Area. Defense General Supply
center/ Richmond Virginia". July 1989
Lav Environmental/ Inc./ 1992. U.S. Army Corps of Engineers/
Huntsville Division. "Final RI Work Plan for Fire Training
Area, Acid Neutralization Pits Area/ and Area 50/Open
Storage Area/National Guard Area". August 1992.
Lav Environmental/ Inc./ 1993. U.S. Army Corps of Engineers/ ..
Huntsville Division. "Remedial Investigation Report
Addendum for Area SO/ Open Storage Area/ National Guard Area
for Defense General Supply Center/ Richmond/ Virginia".
Internal-Draft/ January 1993.
Lav Environmental/ Inc. / 1993. U.S. Army corps of Engineers/
Huntsville Division. "Focused Feasibility study Report for
QSA/Area SO/NGA Ground Water ou «", Defense General supply
Center/ Richmond/ Virginia. Draft/ April, 1993
USEPA/ 1990*. "National Contingency Plan**. February 1990.
USEPA/ I990b. "Federal Facility Agreement, Defense Logistics
Agency/ Defense General Supply Center, Richmond and Impacted
Environs". September 1990.
USGS, 1990. "Ground-vater Contamination and Movement at the
Defense General Supply Center/ Richmond/ Virginia1*. United
states Geological survey/ water-Resources Investigations
Report 90-4113.
U.S. Department of Health and Human Services/ PHS, ATSDR. Public
Health Assessment for DGSC. April 21, 1993.
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