Superfund Record of Decision Dover Air Force Base WP 21 and IWBS Areas Dover DE


                                    EPA/ROD/R03-98/108
                                    1998
EPA Superfund
     Record of Decision:
     DOVER AIR FORCE BASE
     EPA ID: DE8570024010
     OU14
     DOVER, DE
     05/01/1998

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EPA 541-R98-108

                           INSTALLATION RESTORATION PROGRAM
                                 RECORD OF DECISION
                 FOR EXCAVATION, TREATMENT, AND OFF-SITE DISPOSAL OF
       LIQUID WASTE DISPOSAL AREA 21  (WP21) AND INDUSTRIAL WASTE BASINS  SOIL,
                               WEST MANAGEMENT UNIT
                          DOVER AIR FORCE BASE, DELAWARE

                                    FEBRUARY 1998
                                    Submitted to
                                   436th SPTG/CEV
                      Dover Air Force Base, Delaware 19902-6600

                                    Submitted by
                      HAZARDOUS WASTE REMEDIAL ACTIONS PROGRAM
                           Oak Ridge, Tennessee 37831-7606
                                     managed by
                        LOCKHEED MARTIN ENERGY SYSTEMS, INC.
                                      for the
                             U.S. Department of Energy
                           Under Contract DE-AC05-840R21400

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                              CONTENTS

    LIST OF FIGURES 	3

    LIST OF TABLES 	3

    ACRONYMS 	4

    1.  DECLARATION OF THE SELECTED REMEDY 	1
       1.1 SITE NAME AND LOCATION 	1
       1.2 STATEMENT OF BASIS AND PURPOSE 	1
       1. 3 ASSESSMENT OF THE SITE 	1
       1.4 DESCRIPTION OF THE SELECTED REMEDY 	2
       1.5 STATUTORY DETERMINATIONS 	3

    2.  DECISION SUMMARY 	4
       2.1 INTRODUCTION 	4
       2 . 2 PUBLIC PARTICIPATION 	4
       2 . 3 SITE BACKGROUND 	5
       2 . 4 SUMMARY OF SITE RISKS 	12
       2.5 REMEDIAL ACTION OBJECTIVES 	19
       2 . 6 SUMMARY OF ALTERNATIVES 	20
           2.6.1 Alternative 1-No Action 	20
           2.6.2 Alternative 2-Excavation,  Off-Site Treatment and Disposal	21
       2.7 COMPARISON OF REMEDIAL ALTERNATIVES 	23
           2.7.1 Overall Protection of Human Health and the Environment  	23
           2.7.2 Compliance with ARARs 	23
           2.7.3 Long-Term Effectiveness and Permanence 	24
           2.7.4 Reduction in Toxicity,  Mobility, and Volume 	24
           2.7.5 Short-Term Effectiveness 	24
           2.7.6 Implementability 	28
           2.7.7 Cost 	28
           2.7.8 Regulatory Acceptance 	28
           2.7.9 Community Acceptance 	28
       2.8 SELECTED REMEDIAL ALTERNATIVE 	28
       2.9 PERFORMANCE STANDARDS 	29
       2.10 STATUTORY DETERMINATION 	29

    REFERENCES 	31

GLOSSARY 	A-l

RESPONSIVENESS SUMMARY 	B-l

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                             LIST OF FIGURES

Figure 1.  Location of Dover Air Force Base 	6
Figure 2.  Management Units and Areas of Investigation,  Dover Air Force Base	7
Figure 3.  Location of Liquid Waste Disposal Area 21 (WP21)  	8
Figure 4.  Approximate Limit of Soil Excavation at Site WP21 	22

                             LIST OF TABLES

Table 1. Constituents in Surface Water (Ig/L)  	10
Table 2. Constituents in Sediment (Ig/kg)  	11
Table 3. Summary of the 1988 VOC Soil Data 	12
Table 4. Summary of the 1997 VOCs Industrial Waste Basin Soil Sample Results	13
Table 5. Summary of the 1997 SVOCs/Pesticides/Metals Industrial Waste Basin Soil
    Sample Results 	14
Table 6. Summary of the 1997 VOCs WP21 Lagoon Area Soil Sample Results 	15
Table 7. Summary of the 1997 SVOCs WP21 Soil Sample Results 	16
Table 8. 1997 Pesticides/PCBs/Metals WP21 Lagoon Area Soil  Sample Results 	17
Table 9. General Response Actions and Potential Remedial Technologies for Soils ...20
Table 10.  Soil Remedial Technology Screening 	25
Table 11.  Summary of Potential ARARs for  Site WP21 	26
Table 12.  Dover AFB,  Site WP21 Cost Analysis 	30

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                                ACRONYMS
1,1,1-TCA        1,1,1-Trichloroethane
1,2-DCA          1,2-Dichloroethane
1,2-DCE          1,2-Dichloroethene
ARARs            Applicable or relevant and appropriate requirements
B                Compound detected in associated blank
bgs              Below ground surface
CERCLA           Comprehensive Environmental Response, Compensation, and Liability Act of 1980
CFR              Code of Federal Regulations
CSOIL            Commercial/Industrial Soil Ingestion Scenario
!c               Degree Celsius
!F               Degree Fahrenheit
D                Compound identified in the analysis at a secondary dilution factor
DAF              Dilution attenuation factor
DAFB             Dover Air Force Base
ODD              1,l-Dichloro-2,2-bis(p-chlorophenyl)ethane
DDE              1,l-Dichloro-2,2-bis(p-chlorophenyl)ethene
DDT              1,1,l-Trichloro-2,2-bis(p-chlorophenyl)ethane
DNREC            State of Delaware Department of Natural Resources and Environmental Control
DRGHW            State of Delaware Regulations Governing Hazardous Wastes
DWPCR            State of Delaware Water Pollution Control Regulations
FS               Feasibility Study
ft               Feet or foot
ft 2             Sguare feet
HAZWRAP          Hazardous Waste Remedial Actions Program
IRP              Installation Restoration Program
IWB              Industrial waste basin
J                Value is estimated
MCL              Maximum Contaminant Level
MEK              Methyl ethyl ketone or 2-Butanone
MIBK             4-Methyl-2-pentanone
Ig/kg            Micrograms per kilogram
Ig/L             Micrograms per Liter
mg/kg            Milligrams per kilogram
NAAQS            National Ambient Air Quality Standards
NCP              National Oil and Hazardous Substances Pollution Contingency Plan
NPDES            National Pollutant Discharge Elimination System
O&M              Operation and maintenance
OWS              Oil/water separator
PCB              Polychlorinated biphenyl
PCE              Tetrachloroethene
POTW             Public owned treatment work
PP               Proposed Plan
RAO              Remedial action objective
RBC              Risk-based concentration
RCRA             Resource Conservation and Recovery Act
RI               Remedial Investigation
ROD              Record of Decision
SAIC             Science Applications International Corporation
SARA             Superfund Amendments and Reauthorization Act of 1986 and 1990
SDWA             Safe Drinking Water Act
SSLgw            Soil Screening Levels-Transfers from Soil to Groundwater
SVOC             Semivolatile organic compound
TCE              Trichloroethene
U                Analyte was analyzed for but not detected
USAF             U.S. Air Force
USEPA            U.S. Environmental Protection Agency
UST              Underground storage tank
VOC              Volatile organic compound
WMU              West Management Unit
WP21             Liguid Waste Disposal Area 21

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1. DECLARATION OF THE SELECTED REMEDY

1.1 SITE NAME AND LOCATION

Liquid Waste Disposal Area 21 (WP21) and Industrial Waste Basins (IWBs), Area 6, West
Management Unit (WMU), Dover Air Force Base (DAFB), Kent County, Delaware.

1.2 STATEMENT OF BASIS AND PURPOSE

This record of decision (ROD) presents the selected remedial action for soil at WP21 and the IWBs
which was chosen in accordance with the requirements of the Comprehensive Environmental Response,
Compensation, and Liability Act of 1980 (CERCLA), as amended by the Superfund Amendments and
Reauthorization Act (SARA) of 1986 and 1990 and, to the extent practicable, the National Oil and
Hazardous Substances Pollution Continqency Plan (NCP), 40 Code of Federal Requlations Part 300. The
U.S. Air Force (USAF), the lead aqency, as the owner/operator of the Base, and the U.S. Environmental
Protection Aqency (USEPA), Reqion III prepared this decision based on the Administrative Record for
the site. The State of Delaware Department of Natural Resources and Environmental Control (DNREC)
provided support.

The State of Delaware concurs with the selected remedy. The Information Repository for the
Administrative Record contains the information supportinq this remedial action decision and is at the
Dover Public Library, Dover, Delaware.

1.3 ASSESSMIENT OF THE SITE

Dover AFB identified soil contamination related to the activities that occurred in and around the
WP21 and IWBs site area. WP21 and the IWBs are in close proximity to one another. WP21 is the
primary location of a former liquid waste disposal basin located in the west-central portion of the
Base. The IWBs were the primary liquid waste receivinq basins prior to treatment throuqh oil/water
separators.

Site WP21 is the most heavily investiqated of all the IRP sites at DAFB. The first samplinq
occurred in 1980 and consisted of a sludqe sample from the impoundments. DAFB sampled qroundwater in
1982 from three wells-MWIOl, MW102, and MW103-installed at the perimeter of the impoundments. In
1984, the base sampled surface water and sediment from within the impoundments. After DAFB closed
the impoundments in 1986, they performed soil samplinq, more extensive qroundwater samplinq, and
soil qas samplinq.

Based on the analysis of qroundwater and soil from the site, the base identified WP21 as a
potential source of chlorinated solvents and metals. Groundwater samples collected in 1982 contained
tetrachloroethene (PCE), 1,1,1-trichloroethane(1,1,1-TCA), trichloroethene (TCE), trans-1,2-
dichloroethene(trans-1,2-DCE), and vinyl chloride at levels exceedinq requlatory action levels. Metals
in sludqe included cadmium, chromium, copper, iron, lead, silver, and zinc.

Additional surface water and sediment samples collected from the laqoons in 1984 prior to closure
(Science Applications International Corporation [SAIC],1986), contained elevated levels of volatile
orqanic compounds (VOCs), semivolatile orqanic compounds (SVOCs), and metals above MCLs. The
compounds detected in the sediment samples were similar to those present in the surface water samples,
however they were below their inqestion RBCs for industrial exposure. On the basis of these data, the
material received in the waste impoundments is likely to have contributed solvent-related orqanics and
metals to the surroundinq subsurface soils and qroundwater.

Durinq the 1997 investiqation, the base collected soil samples to evaluate the extent of residual
soil contamination that may remain from the operation of the industrial waste basins and the operation
and subsequent removal of the waste laqoons at WP21. This investiqation showed that the former laqoons
do not appear to be a source. Analyses of soil samples from around the IWBs and the associated
oil/water separators indicated that these structures are likely sources of qroundwater contamination.
Elevated levels of chlorinated solvents and petroleum hydrocarbons above their correspondinq Soil
Screeninq Levels-Transfers from Soil to Groundwater (SSLqw) were present in the soil intervals below
the bottom of the IWB concrete structures. The investiqators also found pesticides in shallow soils
that are probably related to their use across DAFB.

The USAF and the EPA have decided to excavate, treat and dispose of soil beneath the IWBs
because concentrations of hazardous substances in the soil exceed their SSLqw. The potential risks
identified at the site are due to the miqration of contaminants from the soil to the qroundwater
downqradient users of the water may inqest. The potential risk at the IWBS/WP21 is primarily
attributable to chlorinated solvents, pesticides, and metals in soil.

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         Actual or threatened releases of hazardous substances from this site, 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.

    1.4 DESCRIPTION OF THE SELECTED REMEDY

         The selected remedy consists of excavation of the contaminated soil beneath the IWB concrete
    structures, and off-site treatment and disposal of the soil. The contractor will level the soil cap on
    WP21, over the formet lagoons, and will use the material to fill the excavation of the IWB area. Final
    evaluation of the performance of this remedy,  remediation of contaminated groundwater at the site, and
    compliance with applicable or relevant and appropriate reguirements (ARARs)  will occur in the final
    Basewide ROD.

    1.5 STATUTORY DETERMINATIONS

         The selected remedial action satisfies the remedial selection process reguirements of
    CERCLA and NCP. As reguired under CERCLA, the selected remedy provides the best balance
    of trade-offs among the nine evaluation criteria. The selected action provides protection of
    human health and the environment, complies with federal and state reguirements that are legally
    applicable or relevant and appropriate to the action, and is cost effective. This remedy uses
    permanent solutions and alternative treatment technology to the maximum extent practicable and
    satisfies the statutory preference for remedies that use treatments that reduce toxicity, mobility,
    or volume as a principal element.

         Because the remedy will result in the removal of the contaminated soil and there will be no
    hazardous substances in the site soils above action levels, no further review  (i.e., 5-year review)
    will be necessary to ensure the remedy provides adeguate protection of human health and the
    environment in accordance with NCP Section 300.430 (f)(4)(ii).



                             2. DECISION SUMMARY

    2.1 INTRODUCTION

         DAFB recently completed a summary soil sampling report and Remedial Investigation (RI) that
    addressed soil in the immediate vicinity of the WP21 and two IWBs that are located along its
    northwestern boundary at DAFB, Delaware. The site is located in what is called Area 6 of the West
    Management Unit (WMU).  Groundwater for the site is being addressed under a ROD for Natural
    Attenuation of Groundwater, Target Area 1 of Area 6 in the WMU.

         The remedial action is undertaken as part of the USAF's Installation Restoration Program (IRP).
    The basis for the remedial action is primarily found in the document Summary Report WP21 Soil
    Sampling, Dover Air, Force Base, Dover, Delaware  (Dames & Moore, September 1997) . Other
    information relevant to the site are found in the Basewide Remedial Investigation, West Management
    Unit, Dover Air Force Base (Dames & Moore, August 1997)  and the Area 6 Remedial Investigation,
    Dover Air Force Base, Dover,  Delaware reports which characterized contamination and evaluated
    potential risks to public health and the environment.

         This ROD explains the nature of the contaminated soil at Site WP21 and IWBs, summarizes the
    history and principal findings of previous field investigations, briefly describes the selected
    alternative, and presents the rationale for the selected alternative.  The State of Delaware concurs
    with the remedy selected in this ROD.

         As an aid to the reader, a glossary of the technical terms used in this ROD is provided at the
    end of the document.

    2.2 PUBLIC PARTICIPATION

         DAFB offered opportunities for public input and community participation during the investigations
    and Proposed Plan (PP)  for WP21 and the IWBs in the WMU. The PP was made available to the public
    in the Administrative Record. Documents composing the Information Repository for the Administrative
    Record for the site are available at the Dover Public Library,  Dover,  Delaware. The notice of
    availability for the PP was published in the local newspaper and the Base newspaper. A public comment
    period was held from Monday,  January 12,1998,  until Wednesday,  February 11,  1998. The public comment
    period was not extended as there were no reguests for an extension. No written comments were received

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from the public, and no public meeting was requested. These community participation activities fulfill
the requirements of Section 113(k)(2)(B)(I-v) and 117(a)(2) of CERCLA.

2.3 SITE BACKGROUND

DAFB is located in Kent County, Delaware, 3.5 miles southeast of the city of Dover (Fiqure 1) and
is bounded on the southwest by the St. Jones River. DAFB comprises ~4,000 acres of land, including
annexes, easements, and leased property (Figure 2). DAFB is relatively flat, with elevations ranging
from ~10 to 30 ft above mean sea level. The surrounding area is primarily cropland and wetlands.

DAFB began operation in December 194 1. Since then, various military services have operated out
of DAFB. The current host organization is the 436th Airlift Wing. Its mission is to provide global
airlift capability, including transport of cargo, troops, equipment, and relief supplies.

DAFB is the U.S. East Coast home terminal for the C-5 Galaxy aircraft. DAFB also serves as the
joint services port mortuary, designed to accept casualties in the event of war. The C-5 Galaxy, a
cargo transport plane, is the largest aircraft in the USAF, and DAFB is one of the few military bases
at which hangars and runways are designed to accommodate these planes.

The portion of DAFB addressed in this ROD-IRP Site WP21-is located within the WMU, one of
four management units into which the Base has been divided (Figure 2).

DAFB owned and operated two surface impoundments that received hazardous waste from 1963
until 1984 (Figure 3). The former impoundments, known as IRP Site WP21, are located in the western
portion of DAFB, adjacent to Atlantic Suva and southwest of Building 719. WP21 covers -19,200 ft 2
and is secured by a locked chain-link fence. Access is limited and controlled by personnel at the DAFB
water plant. Currently, the site is occupied by two concrete IWBs that are connected to the Industrial
Waste Collection Drain (IRP Site OT41) and two oil/water separators (OWSs) (IRP Site OT46).

The treatment system at WP21 was initially built in 1963 to receive wastes from the engine
overhaul shop (Building 719). The system consisted of primary receiving basins (IWBs) (12,000-gallon
capacity), the secondary impoundments (WP21) (170,000-gallon capacity), and an underground pipeline
through which waste flowed after passing through the OWSs (OT46). In 1968 the system was expanded to
accept wastes from other facilities (Building 724-metal plating shop and Building 582-wash racks).
When in operation, wastewater from the various facilities was discharged to the IWBs. Untreated
wastewater was processed through an OWS located at the end of each IWB. Separated oils were pumped
to a 15,000-gallon underground storage tank (IRP Site WP33). Treated wastewater was sent to the
unlined surface impoundments (Site WP21). The flow of treated wastewater from unlined surface
impoundments varied over time and is summarized below:

• Between 1963 through 1969, treated wastewater was sent to the north drainage ditch (Site SD12)

• Between 1969 through 1975, treated wastewater was sent to the DAFB Wastewater Treatment Plant
(Site OT28).

• Between 1975 through 1985/1986 (closure of the two surface water impoundments), treated
wastewater was sent to the Kent County Regional Wastewater Treatment Plant.

• Between 1985/1986 to preseny, at the time the two surface impoundments were closed, two OWSs
(OT46) were installed near the end of each IWB to provide additional treatment prior to
discharge to the sanitary sewer and ultimately the Kent County Regional Wastewater Treatment
Plant.

Each OWS is constructed of steel with internal coalescing plates and contains a 300-gallon
holding tank. The OWSs measure 53.5 in. wide by 142 in. long by 61 in. deep and work by gravity
separation. Separated water is discharged directly to the sanitary sewer.

The two unlined surface impoundments known as WP21 were closed in August 1986. According to
design specifications provided by DAFB, the impoundments were ~4 ft deep. During removal, the
sludge within the unlined impoundments was excavated along with ~6 in. of soil beneath them. The
amount of sludge and soil removed is unknown. The area was backfilled with unaffected soil, capped
with a synthetic material and clay, and covered with grass under the supervision of the State of
Delaware's DNFLEC. The impoundments were certified as closed on September 4,1986. The 15,000-gal

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underground waste storage tank (WP33) was removed in or around 1984.

When the surface impoundments were listed on DAFB's Part A permit under the Resource
Conservation and Recovery Act (RCRA), they were interim status, which required compliance with
standards of 40 Code of Federal Regulations (CFR) Part 265. After receipt of an incomplete post-
closure notice, DNREC issued a Secretary's Order for compliance with the Delaware Regulations
Governing Hazardous Waste (DRGHW) , which was amended on May 10, 1989. DAFB was required to
begin quarterly groundwater monitoring and to statistically evaluate the data obtained as part of the
Secretary's Order.

Quarterly groundwater monitoring samples have been analyzed and evaluated from WP21 from
April 1990 through January 1994. Biannual samples are now being collected in accordance with the Post
Closure Permit.

The Columbia Formation is the shallowest water-bearing unit and holds the water table aquifer.
Deeper aquifers are protected by the extensive upper clay of the Calvert Formation. The upper portion
of the Columbia Formation is finer grained and contains more silt and clay lenses than the deeper
portions. The deeper portion of the Columbia Formation typically consists of fine-to-coarse-grained
sand with occasional lenses of fine-to-medium sand and discontinuous gravel lenses interpreted as
channel lag deposits. The maximum thickness of the Columbia Formation at WP21 is ~38 ft. The water
table is generally encountered at a depth of ~11 ft below ground surface (bgs) at WP21 but varies
seasonally.

Site WP21 is the most heavily investigated of all the IRP sites at DAFB. The first sampling
occurred in 1980 and consisted of a sludge sample from the impoundments. Groundwater was sampled in
1982 from three wells-MWIOl, MW102, and MW103-installed at the perimeter of the impoundments. In
1984, surface water and sediment from within the impoundments were sampled. Soil sampling, more
extensive groundwater sampling, and soil gas sampling were performed after the impoundments were
closed.

Based on the analysis of materials from the impoundments prior to closure, WP21 was identified as
a potential source of chlorinated solvents and metals in groundwater. Groundwater samples collected in
1982 contained PCE, 1,1,1-TCA, TCE, trans-1,2-DCE, and vinyl chloride each at less than 50 Ig/L.
Metals in sludge included cadmium (1,900 mg/kg), chromium (33,000 mg/kg), copper (333 mg/kg), iron
(11,000 mg/kg), lead (8,200 mg/kg), silver (15.9 mg/kg), and zinc (4,300 mg/kg).

Additional surface water and sediment samples were collected from impoundments in 1984 prior to
closure (SAIC, 1986). The surface water samples SW001 and SW002 were collected from separate
impoundments and were analyzed for VOCs and metals. The detected analytes and concentrations are
shown in Table 1.

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                 Table  1.  Constituents in Surface Water  (Ig/L)
      Sample ID:
           Date:
1,1,1-TCA
1,1-DCA
1,1-DCE
1,2-DCA
Benzene
Ethylbenzene
Methylene chloride
PCE
Toluene
trans-1,2-DCE
TCE
Sample ID:

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     Sediment samples collected from the impoundments at the same time were analyzed for VOCs,
SVOCs,  and metals (SAIC, 1986).  SD01 was collected from the top 6 in.  of sediment/sludge in the
smaller impoundment,  whereas SD02 was collected from 4 to 5 ft below the sediment in the other
impoundment.

     The compounds detected in the sediment samples are similar to those present in the surface water
samples (Table 2). On the basis of these data,  the material received in the waste impoundments is
likely to have contributed solvent-related organics and metals to the surrounding subsurface soils and
groundwater.  However, the downward migration to several feet below the basins was apparently
retarded as indicated by lower constituent concentrations in the subsoil of SD02.

     Soil samples were also collected during the installation of the monitoring wells at WP21 in 1988.
The monitoring wells were located beyond the actual surface impoundments, either upgradient or
downgradient of WP21. Therefore,  these soil data did not necessarily reflect source specific
constituents. Soil samples collected from the two closest monitoring well pairs (MW211 and MW212)
are summarized in Table 3 (VOC data only).  These wells were located substantially downgradient and
beyond the area of the waste lagoons at WP21.

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                Table 2. Constituents  In Sediment (Ig/kg)
Sample ID: SD01 SD02
Date: 12/12/84 12/12/84
'CA 12 2.9
202
1 8.2
1.1
ihloropropane 0.60
40.70
lenzene 1.8
ne chloride 45.9
105 4.5
659
, 2-DCE 229
65.5 2.4
ihlorobenzene 273 1.2
ihlorobenzene 34.3
Sample ID:
Date:
Arsenic
Cadmium
Chromium
Copper
Iron
Lead
Mercury
Nickel
Silver
Zinc




SD01
12/12/84
4.05
15.20
378
17.2
0.22
102
0.06
5.08
0.25
66.6




SD02
12/12/84
37.2
2.71
68.1
6.63
0.46
24
0.02
5.78
0.05
22.6




1,1,1-TCA
1,1-DCA
1,1-DCE
1,2-DCA
1,2-Dic
Benzene
Chic
Met!
PCE
Toluene
trai
TCE
1,2-
1,3-
1,4-Dichlorobenzene
Phenol
0.60

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                 Table 3. Summary of the 1988 VOC Soil Data
            Analyte
1,1,1-TCA
1,1-DCA
1,1-DCE
1,2-DCA
1,2-DCE
2-Butanone
4-Methyl-2-Pentanone
Acetone
Chloroform
Methylene Chloride
Toluene
TCE
Highest
concentration
(Ig/kg)
260D
68
38
61
29
500D
45
160B
3BJ
140B
6J
27
Number
of hits

2
1
1
1
1
2
2
6
4
6
2
3
Number
of samples

6
6
6
6
6
6
6
6
6
6
6
6
B - Compound was detected in associated blank.
D - Compound identified in the analysis after dilution.
J - Value is estimated.
U - Analyte was analyzed for but not detected.

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     During the 1997 investigation, soil samples were collected to evaluate the extent of residual
soil contamination that may remain from the operation of the industrial waste basins and the operation
and subseguent removal of the waste lagoons at WP21. Analytical data are summarized in Tables 4 and 5
for the IWBs/OWSs area and in Tables 6, 7,  and 8 for the former lagoons area of WP21.

2.4 SUMMARY OF SITE RISKS

     Ordinarily,  the risks posed by hazardous substances at a Superfund site are analyzed in several
stages. At an early stage of the analysis,  concentrations of hazardous substances at the site are
compared with health-based "screening" levels. If the concentration of a hazardous substance at the
site is lower than the screening levels, then that substance poses no unacceptable risk to human
health or the environment; the substance is excluded from further study. On the other hand,  if the
concentration of a

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Table 4. Summary of the 1997 VOCs Industrial Waste Basin Soil Sample Results
                Analyte
   Highest
concentration
   (Ig/kg)
 Number
of hits
  Number
of samples
RBC for
 CSOIL*
(Ig/kg)
 SSLgw
20 DAF**
(Ig/kg)
 Background
concentration
   (Ig/kg)
           1,1,1-TCA                90,700D
           1,1-DCA                   1010
           1,1-DCE                   4600D
           Acetone                   43.5J
           Benzene                   7.04J
           Chlorobenzene             17.6J
           Chloroethane              15.5
           cis-l,2-DCE               503
           Ethylbenzene              772
           Methylene Chloride        50.6
           PCE                       309
           Toluene                   527
           TCE                       607
           Xylene (total)             9030D
4,
2,
9,
2,
2,
4,
2,
2,
2,
7,
1.
4,
5,
1.
. 1E+07
. OE+08
. 5E+03
.OE+08
. OE+05
. 1E+07
.2E+05
. OE+07
.OE+08
. 6E+05
. 1E+05
. 1E+08
.2E+05
. OE+09
2000
23,000
60
16,000
30
1000

400
13,000
20
60
12,000
60
190,000
           *  CSOIL-USEPA Region III Risk-Based Concentration/Industrial Soil Ingestion Scenario.
           ** SSLgw-UWEPA Soil Screening Guidance for Soil Screening Levels - Transfers from Soil to Groundwater with a default dilution-attenuation factor  (DAF) of 20.
              Bold values indicate exceedances.

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         Table 5. Summary of the 1997 SVOCs/Pesticides/Metals Industrial Waste Basin Soil Sample Results
Analyte
   Highest
concentration
  (Ig/kg)
 Number
of hits
Number of
 samples
RGB for
 CSOIL
(Ig/kg)
 SSL gw
 20 DAF
(Ig/kg)
 Background
concentration
   (Ig/kg)
2-Methylnaphthalene         6720J
Bis(2-ethylhexyl)phthalate  184J
Di-n-butyl phthalate        225J
Naphthalene                 8290
Chlordane-alpha             4.24
Chlordane-gamma             3.23J
DDD                         172
DDE                         219
DDT                         89.9
Endosulfan I                2.06
Endrin                      5.24J
Heptachlor epoxide          0.342J
Calcium                    2.54E+06
Silver                      2130
41,000


16,000
16,000
24,300
17,000
17,000
1.2E+07
6.1E+05
630
3.6E+06
2.3E+06
84,300
10,000
10,000
16,000
54,300
32,000
18,000
1000
700
                                                                              l.OE+07
                                                                                          34,300
                                                                                    1,080,000
                                                                                       970
     *   CSOIL-USEPA Region III Risk-Based Concentration for Commercial/Industrial Soil Ingestion Scenario.
     **  SSLgw-USEPA soil Screening Guidance for Soil Screening Levels-Transfers from Soil to Groundwater with a default dilution-attenuation factor (DAF) of 20.
         Bold values indicate exceedances.

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                Table 6. Summary of the 1997 VOCs WP21 Lagoon Area Soil Sample Results
       Analyte
2-Butanone  (MEK)
4-Methyl-2-Pentanone
(MIBK)
Acetone
Methylene Chloride
TCE
Highest
concentration
(Ig/kg)
124
12
71.8
4.74
1.67
Number
of hits

2
1
7
3
1
Number
of samples

19
19
19
19
19
RBC for
CSOIL
(Ig/kg)
l.OE+09
1.6E+08
2.0E+08
7.6E+05
5.2E+05
SSLgw
20 DAF
(Ig/kg)


16,000
20
60
Background
concentratio
      n
  (Ig/kg)
    CSOIL-USEPA Region III Risk-Based Concentration for Commercial/Industrial Soil Ingestion Scenario.
    SSLgw-USEPA Soil Screening Guidance for Soil Screening Levels-Transfers from Soil to Groundwater with a default dilution-attenuation factor  (DAF) of 20.
    Bold values indicate exceedances.

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                         Table 7. Summary of the 1997 SVOCs WP21 Soil Sample Results
         Analyte
Benzopyrene
Benzo[a]anthracene
Benzo[b]fluoranthene
Benzo[g,h,i]perylene
Benzo[k]fluoranthene
Chrysene
Di-a-butyl phthalate
Fluoranthene
Indeno(1,2,3-CD)pyrene
Phenanthrene
Pyrene
   Highest
concentration
  (Ig/kg)

   299J
   1180
   1470
   588J
   543J
   1160
   171J
   2400
   537J
   1140
   1860
 Number
of hits
Number of
 samples
                      19
                      19
                      19
                      19
                      19
                      19
                      19
                      19
                      19
                      19
                      19
RBC for
 CSOIL*
(Ig/kg)
 SSLgw
20 DAF**
(Ig/kg)
780
7800
7800
78,000
7.8E+05

8.2E+07
7800
8000
2000
5000
49,000
1.6E+05
2.3E+06
4.3E+06
14,300
 Background
concentration
   (Ig/kg)
                                                            6.1E+07
                                                                           4.2E+06
    CSOIL-USEPA Region III Risk-Based Concentration for Commercial/Industrial Soil Ingestion Scenario.
    SSLgw-USEPA Soil Screening Guidance for Soil Screening Levels-Transfers from Soil to Groundwater with a default dilution-attenuation factor  (DAF) of 20.
    Bold values indicate exceedances.

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     Table
1997 Pesticides/PCBs/Metals WP21 Lagoon Area Soil Sample Results
 Analyte
     Highest
   concentration
    (Ig/kg)
Alpha-BHC
Chi ordane- alpha
Chi ordane- gamma
DDD
DDE
DDT
Dieldrin
Gamma-BHC (Lindane)
PCB 1016
PCB 1260
Calcium
Silver
7.72J
3.52J
25.8
351
2090
2460
172
65. 8 J
95.9
154
782
3370
Number
of hits
                                       3
                                       2
                                       3
                                       5
                                       7
                                       7
                                       2
                                       3
                                       1
                                       1
                                       19
                                       11
Number of
 samples
                                           19
                                           19
                                           19
                                           19
                                           19
                                           19
                                           19
                                           19
                                           19
                                           19
                                           19
                                           19
RBC for
CSOIL*
(Ig/kg)
                                                                        l.OE+07
 SSLgw
20 DAF**
(Ig/kg)
910
16,000
16,000
24,300
17,000
17,000
360
4400
1.4E+06
41,000
0.5
10,000
10,000
16,000
54,300
32,000
4
9
1000***
1000***
                                                                                         34,300
Background
concentration
  (Ig/kg)
                                                                          1.08E+06
                                                                             970
CSOIL-USEPA Region III Risk-Based Concentration for Commercial/Indstrial Soil Ingestion Scenario.
SSLgw-USEPA Soil Screening Guidance for Soil Screening Levels-Transfers from Soil to Groundwater with a default dilution-attenuation factor  (DAF) of 20.
Preliminary Remediation Goal
Bold values indicate exceedances.

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hazardous substance is higher than the screening levels, then that substance is studied further in a
site-specific baseline risk assessment. The baseline risk assessment is designed to identify which hazardous
substances pose risks that reguire a remedy, and which pose risks that are within acceptable limits.
Ordinarily, remedial action is taken only after the site-specific baseline risk assessment determines that
one or more substances pose unacceptable risks to human health or the environment.

At this site, however, the USAF and EPA have decided to take remedial action at an early stage-the
screening stage-rather than wait for the results of a more detailed site-specific baseline risk assessment.
The concentrations of several hazardous substances in soil beneath the IWBs exceed the Soil Screening Levels
for Ground Water Transfer (SSLgw), as explained in more detail below. The USAF and EPA agree, based upon this
data, that the soil containing these hazardous substances should be excavated, treated and disposed of in
order to prevent hazardous substances in the soil from migrating to ground water below. Given the particular
circumstances at this site, the decision to proceed with a remedy, without awaiting a more detailed
site-specific baseline risk assessment, is consistent with the directive in the NCP that "Remedial actions
are to be implemented as soon as site data and information make it possible to do so." 40 C.F.R. °
300.430(a) (1).

USAF and EPA have determined that, in the particular circumstances of this site, them is enough
information and site data available to choose a remedy without conducting a more detailed site-specific
baseline risk assessment. The USAF and EPA's decision to proceed with excavation, treatment and disposal at
this site, without conducting a more elaborate site-specific baseline risk assessment, is not intended to set
a precedent for other sites.

Soil data are compared with several sets of criteria. For organics (VOCs, SVOCs, and
pesticide/polychlorinated biphenyls [PCBs]), positive detections are compared with USEPA Region III Risk-
Based Concentrations (RBCs) established for soil ingestion under an industrial/commercial scenario (CSOIL)
and the USEPA Soil Screening Guidance: Technical Background Document for Soil Screening
Levels-Transfers from Soil to Groundwater (SSLgw). SSLgw criteria tend to be more stringent than the
CSOIL criteria and final risk assessment cleanup levels, but are generally used for guidance only. The metal
results are compared to DAFB-specific background levels as established during the Basewide RI or the USEPA
Region III RBCs.

The potential risks associated with WP21 are those that would adversely affect human health or the
environment, effects that could occur under current or potential future use conditions if the contamination
is not remediated. The principal risk at WP21 is due to the potential migration of hazardous substances from
soil to groundwater. Some constituents of concern in the soil beneath the IWBs exceed the SSLgw criteria.
This situation may present an unacceptable risk to downgradient users of groundwater. The soils will be
removed because they failed to comply with the SSLgw criteria. This remedial action will eliminate the
potential migration of the contaminants from the soil to the groundwater and the potential risk exposure
related to this site.

A potential short-term risk would be as a result of the remedial action itself. Site workers and
visitors may be exposed to site contaminants through inhalation and ingestion of contaminated soil particles
and volatilized constituents, and direct dermal-contact with contaminated materials. Target populations only
include site workers and visitors. Appropriate health and safety precautions will be implemented during the
removal action to protect site workers and visitors. No site-specific risk calculations have been performed
for WP21 soil, but environmental risks for WP21 will be addressed in the Basewide ROD.

It should be noted that only the site soils are being addressed in this ROD. The site groundwater
(Columbia Aguifer) is not used by the Base for industrial, residential, and recreational purposes.
Institutional controls are currently in-place for both the site soil and groundwater. Groundwater
contamination is to be addressed in the Basewide ROD.

Details concerning the potential human health risks for the Area 6, of which WP21 is a part, may be
reviewed in the Area 6 Remedial Investigation Report, Dover Air Force Base, Dover, Delaware, July 1994.
Tables 4 through 8 provide summaries of the constituents of concern and their corresponding RBC and/or
background concentration that will be used in the remediation of the site soil.

No VOCs, SVOCs, pesticide/PCBs were detected above the CSOIL-RBCs for the Site WP21 and the IWB
areas. Except for calcium and silver, all metals were detected at concentrations below the CSOIL-RBCs and
Base-specific background levels. Calcium, detected in every sample, exceeded its background level in one
sample-B3304A. Silver, the only other metal to exceed its background level (0.97 mg/kg), was detected at
concentrations up to 3.37 mg/kg in 11 of the 19 samples collected from the former lagoons area. All silver
detections were below its CSOIL and SSLgw criteria of l.OE+07, Ig/kg and 3.4E+05,ug/kg, respectively.

Chlorinated compounds and fuel-related constituents were detected at 8 to 10 ft bgs near the IWBs,
especially Basin A (B3301B). Since no VOCs were detected at the 2- to 4 -foot interval in either boring

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flanking Basin A, a release from the bottom of the basin is most likely. Similar constituents were detected
in Basin B, but at much lower concentrations, indicating significantly smaller releases compared with Basin
A. Low levels (<16 Ig/kg) of four solvents were detected in B3303A (2 to 4ft bgs) and B3304A (6 to 8 ft bgs)
collected on either side of Basin B. These detections may be remnants of small surface spills from the IWBS.
An upgradient source of these constituents is unlikely because they were not detected in other soil samples
or upgradient groundwater.

2.5 REMEDIAL ACTION OBJECTIVES

Remedial action objectives (RAOs) are media-specific goals to be reached during site remediation that
are protective of human health and the environment. These objectives are typically achieved by preventing
exposure and reducing contaminant levels (Guidance for Conducting Remedial Investigations and Feasibility
Studies Under CERCLA, Interim Final, USEPA, October 1988). The RAOs for the WP21 former sludge
lagoons and industrial waste basins are: 1) For soil within the boundaries shown on Figure 4, down to the
water table, reduce the contaminants to their SSLgw level; 2) If soil at the boundaries shown on Figure 4, at
any depth down to the water table contains concentrations of any hazardous substance(s) listed in Tables 4
through 8 of this ROD greater than the CSOIL concentrations for the substance(s), then reduce the
concentration of such substance(s) to the CSOIL concentration for the substance(s), or less. The principal
threat at WP21 is the potential migration of hazardous substances from soil to groundwater. The remedial
action will eliminate this threat by removing and treating the contaminated soil.

2.6 SUMMARY OF ALTERNATIVES

Remedial alternatives were categorized and specific process options were identified based on a review of
literature, vendor information, performance data, and experience developing other remedial programs under
CERCLA. Applicable remedial alternatives were evaluated for each of the three general response actions. The
three general response actions are described in Table 9.

General response actions are the steps that could be taken to achieve the RAOs for the soil at WP21.
Based on the results of the initial screening of the response action technologies and representative process
options, the following two technologies are considered applicable:

• Alternative 1 - No Action
• Alternative 2 - Excavation, Off-Site Treatment and Disposal

These remedial alternatives are described in the following subsections. In addition, the capital, annual
operation and maintenance (O&M), and present worth costs of each alternative are provided.

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           Table 9. General Response Actions and Potential Remedial Technologies for Soils
                                 Site WP21, Dover Air Force Base

General response action                  Soil technology description         Description
No Action                                None                               None

Soil Removal                             Excavation                         Excavation of contaminated soils is
                                                                            reguired before any ex situ treatment
                                                                            technology implementation.

Treatment                                Thermal Desorption                 Soil is excavated and treated by a
                                                                            licensed facility using thermal
                                                                            desorption at temperatures between
                                                                            800 and 10005F.  Off gases are
                                                                            treated using a bag house and a
                                                                            thermal oxidizer.

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2.6.1 Alternative 1-No Action

Alternative 1, the No Action alternative, is considered in the range of alternatives to serve as a
baseline or to address sites that do not require active remediation. The NCP and CERCLA guidance require that
the No Action alternative be evaluated. This alternative assumes that no remedial action will occur and that
the site would be left in its present condition. No efforts are undertaken to reduce soil contaminants. Any
changes to the site would be a direct result of natural processes, and no monitoring would be conducted to
document changes in contaminant levels. No cost is associated with this alternative.

Alternative 1

Cost category Cost ($)

Capital 0

Annual Operations and Maintenance 0

Present Worth 0

2.6.2 Alternative 2-Excavation, Off-Site Treatment and Disposal

The excavation, off-site treatment and disposal alterative shall consist of excavating and transporting
the VOC-contaminated soils from the WP21 site to an off-site, licensed treatment and disposal facility. The
treatment option shall use thermal desorption to drive off the volatile contaminants from the soil. Off-gases
and particulate shall be captured and/or destroyed. Treated residuals shall be disposed into a licensed
landfill. The tasks to be performed during this alternative shall include: 1) removal of the IWBs, OWSs, a
lift station, and associated piping; 2) removal of contaminated soils associated with these structures; 3)
treatment of contaminated soil through thermal desorption; 4) disposal of treated soil at a licensed landfill
as daily cover material; 5) removal of the WP21 soil cap; and 6) restoration of the site to a usable
condition.

The contaminated soils from the IWBs and OWSs shall be excavated to the water table, estimated to be 12
ft bgs, within the boundaries outlined in Figure 4 of this ROD. The excavated soil shall be packaged for bulk
shipment and transported by tractor trailer rig (18 yd 3 capacity) to the thermal desorption treatment
facility. The treated residuals shall be disposed at a licensed landfill as daily cover material.

The contaminated soil will be excavated using common construction equipment. Backhoes could excavate
the soil to a depth of 12 ft bgs and stockpile the soil for loading and packaging for shipment. Front-end
loaders could be used to load the soil into lined, 18 yd 3 end-dump trailers for bulk transportation. Soil
removal involves the use of heavy equipment to excavate the contaminated soil from the site. This response
action relies on common construction equipment such as bulldozers, excavators, and dump trucks. The
excavation technology of Alternative 2 is well demonstrated and reliable.

The total volume of soil in the area to be excavated is estimated at 2600 yd 3. This excludes soil
volume from the WP21 cap. The volume of contaminated soil at the IWB/OWS area is assumed to be 50% of the
total soil volume because the investigative results showed that contaminants were primarily released from the
bottom of the IWBS. With an additional soil volume from the lift station and all piping, assumed to be 10% of
the excavated volume, the total estimated volume of contaminated soil is 1400 yd 3. An excess 1500 yd 3 of
clean soil will be stockpiled/disposed on the Base. Figure 4 provides an illustration of the approximate
limits of the soil excavation to be conducted at Site WP21.

The estimated total volume of clean soil, above the geomembrane on the WP21 cap is 2200 yd 3. There is
sufficient volume of clean soil from the WP21 cap cover to use as the fill in the excavations at the IWBs,
OWSs, lift station, and associated piping. Excess clean soil can be transported to a location designated by
the Base. The time for all tasks to be completed under this alternative is estimated to be three months.

Alternative 2

Cost category Cost ($)

Capital $653,725

Annual Operations and Maintenance $0

Present Worth $653,725

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2.7 COMPARISON OF REMEDIAL ALTERNATIVES

This section provides a comparative analysis of the two remedial alternatives. The focus of the
comparative analysis is on the relative advantages and disadvantages offered by each of the alternatives in
relation to the seven evaluation criteria that were analyzed. A detailed summary of the technology screening
and analysis is provided in Table 10.

2.7.1 Overall Protection of Human Health and the Environment

The overall protectiveness criterion is a composite of other evaluation criteria, especially short-term
effectiveness, long-term effectiveness, and compliance with ARARs. Alternative 1 (No Action) would not be
protective of human health and the environment because of potential leaching of contaminants to groundwater.

Alternative 2 (Excavation/Off-Site Treatment and Disposal) is considered to be protective of human
health because of institutional controls now in place and the removal and treatment of a potential source of
groundwater contamination. The removal action will effectively reduce risk by removing a potential source of
groundwater contamination. In addition, risk to human health through exposure to contaminated soils will be
reduced.

2.7.2 Compliance with ARARs

Alternative 1 (No Action) provides no mechanism to evaluate compliance with ARARs and therefore does
not comply with ARARs.

Because Alternative 2 relies on proven methods for removing and treating of contaminated soils, this
alternative will comply with all chemical-, location-, and action-specific ARARs. Table 11 provides a
summary of the ARARs for Alternative 2. Because an on-site thermal desorption system would reguire a
lengthy permitting and trial burn testing, the use of an off-site, thermal desorption system was evaluated.
The most likely applicable or relevant and appropriate reguirements for this alternative would include
permitting for intrastate transport and disposal of a special or hazardous material. An air permit from DNREC
addressing fugitive dust emmissions generated during soil excavation may be necessary, and there may be
excavation permitting reguirements from the Base.

A number of other ARARs-including the Clean Water Act and RCRA-must be considered. Primary
among them are compliance with VOC emission limitations to the atmosphere, land treatment regulations, and
effluent discharge limitations to surface water. The selected alternative will comply with all ARARs.

2.73 Long-Term Effectiveness and Permanence

The No Action alternative does not provide controls to reduce concentrations of organics in the soil to
levels below RBCs and groundwater protection standards. The No Action Alternative does not provide for
long-term effectiveness and permanence. Excavation, off-site treatment and disposal is an extremely effective
treatment technology for the destruction of organic contaminants. Destruction and removal efficiencies can
range from 95% to 99.9999%, depending on combustion temperature and residence time in the treatment unit.
Under current federal guidelines, VOCs are candidates for thermal treatment in a rotary dryer or thermal
screw at 6005-12005C. Thermal desorption is not effective for inorganic contaminants, such as metals. The
metals generally remain in the soil, but they may be released as particulate in the off-gas and trapped in
the air pollution control system. The technology would achieve both the short- and long-term effectiveness
criteria.

2.7.4 Reduction in Toxicity, Mobility, and Volume

The No Action Alternative does not employ removal or treatment processes to address soil contamination.
Therefore there would be no reduction of toxicity, mobility, or volume of contaminants in soil. This
alternative will not satisfy the statutory preference for treatment as a principal component of remedial
action.

Excavation and thermal desorption reduces the potential threat to human health and the environment by
removing the organic contaminants from the soil for subseguent capture and destruction. Metals occurring in
the soil remain in the soil residual or may be contained in the air pollution control system and must be
properly disposed of. Additional treatment (stabilization) may be reguired for the metals before disposal.

2.7.5 Short-Term Effectiveness

The No Action Alternative does not provide any remedial actions; therefore, short-term risks to the
community or environment would not result from implementation.

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     No risks to the community or environment would be expected during implementation of the treatment
alternative if an off-site, thermal desorption system is used.  The major routes of exposure during treatment
are contact with the contaminated soil and inhalation of off-gas vapors or particulates.  Dust suppression
measures will be implemented during excavation activities to minimize exposure to airborne dust particles and
contaminants. Protection from exposure to the public and the environment is provided by proper packaging

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              Technology
                              Easily implemented.
                              Low potential for exposure to
                              contamination during
                              implementation.
Contaminated soils will
continue to be a  source
of environmental
contamination.
Would not reduce
mobility, toxicity,  or
volume of
contaminants.
                                                                                                  Retained
Required by the
NCP as a
baseline in
feasibility, study
analysis, and
comparison.

Will not meet
removal action
obj ectives
               Excavation
                              Easily implemented.
                                                                  Long-term monitoring
                                                                  would be required.
Depth and composition
of material requiring
excavation must be
considered.
                                                                                                                        Required for any
                                                                                                                        ex  situ
                                                                                                                        alternative
                                                                                                                        including
                                                                                                                        treatment and/or
                                                                                                                        disposal.
Treatment      Thermal        Technology is reliable and has
               Treatment      been  demonstated for treating a
                              wide  range of organic
                              contaminants at full-scale
                              including PCBs and pesticides.

                              Destruction and removal
                              efficiencies up to 99.99%, thus
                              reducing volume or organic wastes.
Off-gas treatment of
metals may require  air
pollution control
equipment.
Subsequent treatment
of inorganic
contamination remaining
in residual soil
potentially required.
More efficient
when treating
larger volumes.
                                                                  Off-base  treatment
                                                                  would require
                                                                  transportation because
                                                                  no local  facilities are
                                                                  available.
                                                     Could be used  in
                                                     combination
                                                     with other
                                                     technologies for
                                                     disposal of soil
                                                     containing a
                                                     range of
                                                     contaminants .
                                                                  High  clay/siIt  content
                                                                  may result  in poor
                                                                  processing
                                                                  performance.
                                                     Potentially
                                                     capable of
                                                     treating a wide
                                                     range of contaminants  in soil.

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                                        Table 11. Summary of ARARs for Site WP21
Environmental laws and regulations
                                                                                                     Consideration as an ARAR
 A. Delaware Hazardous Waste Management  Regulations (Delaware Regulations  Governing
    Hazardous Waste  [DRGHW])

    1.   Standards applicable to  containers and tanks (DRGHW Part 264, Subpart  I  and
        J)
During the action,  soil may be  dewatered.  Contaminated water may be temporarily
stored onsite tanks or containers awaiting treatment.  The tanks and containers  shall
meet all the requirements  of Part 264,  Subpart I & J.
    4.  Land Disposal Restrictions  (DRGHW Part 268)
Land disposal restriction  and treatment requirments shall be met with  respect  to
residuals generated by  this  alternative.
 B. Delaware Industrial Waste  Effluent  (DWRCR Section 8)
 C. Delaware Water Quality  Standars  (DNREC Surface Water Quality Standards)
Discharge of groundwater  contained in excavated soil to surface water  shall  meet
NPDES requirements.

The remedy may distrub  the  existing surface water drainage system. Effluents,  from a
surface water drainage  system,  may require pretreatment.  Any effluent  discharge  to
public owned treatment  works  (POTWs)  shall meet pretreatment standards.

Effluents from the  surface  water drainage system shall not adversely affect  water quality
above acceptable limits.

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    Environmental laws and regulations                                                                        Consideration as an ARAR





III.   Clean Water Act, 33 USC  1251-1387,  esp.  1311-17





      A.   Effluent guidelines  (4 0  Code  of Federal Regulations [CFR] 403)

-------
and transport of the soil to the treatment facility. Protection from exposure to the facility workers is
accomplished by the implementation of institutional controls and the use of proper protection equipment,
such as respirators and protective clothing. Air pollution control equipment is used to minimize the
threat of airborne contaminants. Air monitorinq is used to ensure there is no significant threat from the
inhalation of vapors or particulates.

2.7.6 Implementablility

Three main factors are considered under this criterion: technical feasibility, administrative
feasibility, and availability of services and materials. Because the No Action Alternative does not
provide any remedial actions, there are no technical or administrative difficulties associated with it. In
addition, the No Action Alternative would not limit or interfere with the ability to perform future
remedial actions.

Alternative 2 is technically and administratively feasible, and the required services and materials are
readily available. The treatment alternative uses thermal desorption technoloqy, which has been used for a
number of years to treat volatile hazardous materials. It is easy to implement and is particularly
applicable as a treatment alternative for VOCs. The technoloqy is readily available, and several licensed
facilities are located in the Mid-Atlantic Reqion of the U.S. for either treatment and/or disposal.

2.7.7 Cost

No direct costs are associated with the implementation of Alternative 1 (No Action). The estimated
costs of the Alternative 2, includinq capital costs, annual O&M costs, and present net worth, are
summarized in Table 12. Total cost for the Alternative 2 is estimated to be $653,725. The total amount
of soil to be excavated from the IWBs, OWSs, lift station, and associated pipinq is estimated at 2600
cubic yards. The estimated soil volume requirinq treatment, includinq packaqinq, transport, disposal,
and a 15% "soil expansion" factor is 1400 cubic yards. Treatment and disposal costs were estimated at
$35/ton. A conversion factor of 1.6 tons per cubic yard was used to compute costs.

2.7.8 Requlatory Acceptance

The USEPA and the State of Delaware have reviewed the alternatives and are in aqreement with the
selected remedy for Site WP21.

2.7.9 Community Acceptance

No comments were received durinq the public comment period and no community opposition to the
selected remedy was noted.

2.8 SELECTED REMEDIAL ALTERNATIVE

The selected remedial action is Alternative 2, soil excavation with off-site treatment and disposal. The
soil excavation and off-site treatment and disposal of contaminated soil shall be protective of human
health and the environment, shall comply with ARARs, and shall offer lonq-term effectiveness.
Excavation and off-site treatment is considered easy to implement and effective at treatinq the constituents
of concern at the site. The selected alternative also meets the statutory preference for treatment.

2.9 PERFORMANCE STANDARDS

The selected Alternative shall meet the followinq performance standards: 1) excavation of soil, down
to the water table within the boundaries outlined in Fiqure 4, and 2) if soil at the boundaries outlined on
Fiqure 4, at any depth down to the water table, contains concentrations of any hazardous substance(s)
listed in Tables 4 throuqh 8 of this ROD that an qreater than the CSOIL concentrations for the substances,
all soil with hazardous substance(s) that exceed CSOIL concentrations shall be excavated.

2.10 STATUTORY DETERMINATION

Based on consideration of the requirements of CERCLA, the comparative analysis, and comments,
DAFB, USEPA, and the State of Delaware believe Alternative 2 provides the best balance of the trade-offs
amonq the alternatives with respect to the criteria used to evaluate remedies. The selected remedy is
consistent with CERCLA and, to the extent practicable, the NCP. The selected remedy is protective of
human health and the environment, complies with federal and state requirements that are leqally applicable
or relevant and appropriate to the remedial action, is cost-effective, and uses permanent solutions and
alternative treatment to the maximum extent practicable.

The reliance on excavation, treatment, and disposal mechanisms for the cleanup of orqanic- and

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inorganic-based media has been demonstrated at various sites around the country to be cost effective and,
if properly monitored,  is an environmentally sound solution to soil contamination. It results in permanent
reduction in concentrations of contaminants in the subsurface. Therefore,  Alternative 2 is the selected
remedial action for the IWBs at Site WP21.

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Table 12. Dover AFB, Site WP21 Cost Analysis
Alternative 2: Excavation, Off-Site Treatment and Disposal
Cost Estimating Worksheet (-30% to +50% Level)*
Cost component
Total capital cost*
Comments and references
1. Mobilization
2. Demolition and Excavation
3. WP21 Restoration
$186,000
$76,325
$48,500
4. Thermal Treament and Disposal $99,900

5. Demobilization $12,000

6. Reporting $10,000

7. Contractor Costs - Direct $433,625

8. Profit, Insurance, Bonds, Permits $86,700

Total Direct Capital Costs $520,325

9. Contractoes costs - Indirect $133,400

Total Capital Costs $653,725
Includes site preparation activities for performing the
excavation, site utilities hookups, construction of decon
pad, etc.

Includes demolition of piping, concrete cutting, lift station
demolition, hauling, soil excavation, etc.

Includes removal of WP21 soil cap, hauling of excess soil,
surveying, site restoration, etc.

Includes transporting, treating, and disposing of soil.

Includes site demob and disconnection of utilities.

Documentation of site activities.
Includes engineering design and construction services.
* All costs are rounded to the nearest significant dollar value. The following costs were estimated and provided by a vendor with
an thermal desorption facility in New Castle, Delaware. The costs were based on an excavated soil volume from a 1.4-acre site.
Factors and unit costs for soil expansion, packaging, transportation, actual treatment and actual disposal were not broken out.
These vendor estimated costs are provided for information only.

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                                         REFERENCES

Dames & Moore, July 1994. Area 6 Remedial Investigation Report, Dover Air Force Base, Dover, Delaware.

Dames & Moore, June 1995. Draft Final, Area 6 Focused Feasibility Study Report, Dover Air Force
Base, Dover, Delaware.

Dames & Moore, August 1997. Basewide Remedial Investigation, West Management Unit, Dover Air
Force Base, Dover, Delaware.

Dames & Moore, September 1997. Summary Report WP21 Soil Sampling, Dover Air Force Base, Dover, Delaware.

Hazardous Waste Remedial Actions Program  (HAZWRAP), January 1998. Final Proposed Plan for
Liguid Waste Disposal Area 21  (WP21) and Industrial Waste Basins Soil, West Management Unit, Dover
Air Force Base, Dover, Delaware.

HAZWRAAP, February 1997. Draft Technical Memorandum Lindane Source Area Investigation,
December 1996  (Stage 2), Dover Air Force Base, Dover, Delaware.

R.S. Means Company, Inc., 1996. Environmental Restoration Unit Cost Book-1996. ISBN: 0-87629-422-0.

U.S. Army Corp of Engineers, June 1995. Federal Facilities Agreement Report for Area 6.

USEPA, 1988. Guidance for Conducting Remedial Investigations and Feasibility Studies Under CERCLA,
Interim Final, EPA 540-G-89-004, October.

USEPA, 1993. Guide to Conducting Non-Time Critical Removal Actions Under CERCLA, EPA 540-R-93-057, August.

USEPA, 1997. EPA Region III Risk-Based Concentration Table.

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GLOSSARY

aquifer - A geologic formation capable of yielding water to wells and springs.

Applicable or Relevant and Appropriate Requirements (ARARs) - Criteria set forth by federal, state,
or local regulations that must be considered in the evaluation of remedial alternatives and govern the
environmental actions at a particular site.

Capital Cost - Cost incurred for the construction and startup of a facility.

Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA)- A federal
law passed in 1980 and revised in 1986 by the Superfund Amendments and Reauthorization Act (SARA).
CERCLA provides federal authority and money for the USEPA to respond directly to the release or
threatened release of hazardous substances into the environment at inactive sites.

The State of Delaware Department of Natural Resources and Environmental Control (DNREC)-
State regulatory agency in charge of overseeing environmental programs at DAFB.

Feasibility Study - A study to develop and evaluate options for remedial actions.

Groundwater - Subsurface water residing in a zone of saturation.

Installation Restoration Program (IRP) - The Department of Defense (DOD) program designed to
identify, report, and correct environmental deficiencies at DOD installations. At DAFB, this program
implements the requirements for cleanup under CERCLA.

leachate - The solubilization and transport of constituents in soil through the percolation of surface water
to groundwater.

National Oil and Hazardous Substances Pollution Contingency Plan (NCP) - The federal regulation
that provides a contingency plan for discharges or releases of hazardous substances, pollutants,
contaminants, or oil into the environment that may present an immediate danger to public health or welfare.

Operation and Maintenance Costs (O&M) - Annual costs incurred for operation and maintenance of a facility.

Record of Decision (ROD) - A legal document that explains the specific clean-up alternative to be
implemented at a Superfund site.

Remedial Action Objective (RAO) - Cleanup goal established for remediation.

Remedial Investigation (RI) - An investigation that involves sampling the air, soil, and water to
determine the nature and extent of contamination at an abandoned wage site and the human health and
environmental risks that result from that contamination.

Resource Conservation and Recovery Act (RCRA) - Federal law enacted to address environmental
issues created by current waste disposal, spills, and handling practices.

Selected Alternative - The cleanup strategy that offers the best chance of success in protecting human
health and the environment from contamination at a site. The selected alternative is selected from several
clean-up strategies because it satisfies USEPA criteria for effectiveness, implementability, cost, and
public and regulatory acceptance.

Superfund Amendments and Reauthorization Act (SARA) - A congressional act that modified CERCLA. SARA was
enacted in 1986 and again in 1990 to authorize additional funding for the Superfund program.

U.S. Environmental Protection Agency (USEPA) - The federal regulatory agency in charge of overseeing
environmental programs at DAFB.

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RESPONSIVENESS SUMMARY





     (None received)

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