EPA/ROD/R03-95/213
                                    1995
EPA Superfund
     Record of Decision:
     DOVER AIR FORCE BASE
     EPA ID: DE8570024010
     OU04
     DOVER, DE
     03/28/1995

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THE DECLARATION FOR THE RECORD OF DECISION
REMEDIAL ALTERNATIVE SELECTION

Site Name and Location

Underground Storage Tank  (UST) at Building 124  (WP 32) Dover
Air Force Base, Kent County, Delaware.

Statement of Basis and Purpose

This Record of Decision  (ROD) presents the selected remedial action for the UST at Building 124, which
was chosen in accordance with the requirements of the Comprehensive Environmental Response, Compensation,
and Liability Act of 1980  (CERCLA),  as amended by the Superfund Amendments and Reauthorization Act of
1986 (SARA) and, to the extent practicable, the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP) ,  40 C.F.R. Part 300. This decision is based on the Administrative Record for the
Site and was prepared by the United States Air Force, the lead agency, as the owner/operator of the base.
Support was provided by the U.S.  Environmental Protection Agency  (EPA)  Region III and the Delaware
Department of Natural Resources and Environmental Control (DNREC).

The State of Delaware,  in a letter dated May 5, 1994 to DAFB, and the Environmental Protection Agency
("EPA") concur with the selected remedy.  The information supporting this remedial action decision is
contained in the information repository for the Administrative Record located at the Dover Public
Library, Dover, Delaware.

Assessment of the Site

A limited number of hazardous substances were detected in the soil samples only in the proximity of the
storage tank, all of which were below action levels.  In the 1991 Site Inspection  (SI), lead was detected
at an elevated concentration, but a Toxicity Characteristic Leaching Procedure ("TCLP") test in 1993 has
shown that none of the metals tested leached above their detection limits.  The presence of hazardous
substances only in the proximity of the underground storage tank and the inaccessibility of the tank for
sampling and clean out results in a determination that actual or threatened releases of hazardous
substances from the building 124 underground storage tank has occurred.

Description of the Selected Remedy

The UST at Building 124 will be removed per the Delaware Regulations Governing Underground Storage Tanks
(DRGUST).   The UST and associated piping will be excavated,  cleaned, dismantled,  and disposed of as per
DRGUST.  Visibly contaminated soils, and soils directly beneath the tank would be sampled, analyzed, and
disposed of if necessary according to DRGUST.  The UST excavation would then be backfilled with clean
soil and an asphalt cap would be installed and maintained to allow reuse as a parking lot. Ground water
beneath this UST will be addressed in the base-wide investigation.

Statutory Determinations

The selected final remedial action for this operable unit satisfies the remedial selection process
requirements of CERCLA and the NCP.   The selected remedy of removal of the UST, piping and contaminated
soil provides the best balance of trade-offs among the listed evaluation criteria and the mandate to
consider alternative treatment and preference for permanent solutions. The selected action provides
protection of human health and the environment, complies with federal and state requirements that are
legally applicable or relevant and appropriate to the action, including the Delaware Department of
Natural Resources and Environmental Control regulations for handling underground storage tanks containing
or potentially containing hazardous substances, and is cost effective.  This remedy utilizes permanent
solutions and alternative treatment technology to the maximum extent practicable, and satisfies the
statutory preference for remedies that employ treatment that reduces toxicity, mobility, or volume as a
principal element.   Because this remedy will not result in hazardous substances remaining on-site above
health-based levels, the 5-year review will not apply to this action.  The State of Delaware and the
United States Environmental Protection Agency  (EPA) concur with the selected remedy.  The information
supporting this remedial action decision is contained in the administrative record file located at Dover
Air Force Base.  The information repository and index to the Administrative Record are located in the
Dover Public Library, Dover, Delaware.

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Remedial Alternatives

Three alternatives were evaluated and include:
       1)  No Action;
       2)  Abandon Tank In Place;
       3)  Remove Tank and All Contaminated Soil.

The No Action alternative requires no actions be taken at the site.
baseline for comparison and CERCLA requires it be evaluated.
                     This alternative serves as a
Alternative 2 is to abandon the UST in place followinq DRGUST.  Under these requlations the pipinq to the
UST would also be excavated and removed.  The interior of the UST would be cleaned and filled with
concrete.

Alternative 3 is to remove the UST followinq the DRGUST. The pipinq and UST would be excavated and
removed.  The UST will be cleaned and disposed of appropriately.  Visibly contaminated soils and those
directly below the tank will be sampled and disposed of as per DRGUST.  The UST excavation would then be
backfilled with clean soil and an asphalt cap installed to allow reuse as a parkinq lot.

Decision

The final selection of tank and contaminated soil removal is based on the nine CERCLA criteria:  Overall
Protection of Human Health and the Environment, Compliance with Applicable or Relevant and Appropriate
Requirements  (ARARs) ,  Lonq Term Effectiveness and Permanence, Reduction of Toxicity ,  Mobility, or
Volume, Short Term Effectiveness, Cost, Implementability, State Acceptance, and Community Acceptance.
The selected alternative provides the best balance of trade-offs amonq the listed evaluation criteria and
the mandate to consider alternative treatments and preference for permanent solutions.
        EDWIN E. TENOSO
        Lieutenant General, USAF
        Chairperson, AMC Environmental
        Protection Committee
THOMAS C. VOLTAGGIO
Hazardous Waste Manaqement
Division Director
Environmental Protection Aqency
Reqion III
The United States Air Force has initiated this ROD for the underqround storaqe tank at buildinq 124,
which historically received waste oil and other substances associated with automobile maintenance.
Althouqh access restrictions prevented samples from beinq taken from the waste oil remaininq in the tank,
soil samples in the immediate vicinity of the tank showed the presence of elevated metals, such as lead,
and certain VOCs, such as 1,1,1-Trichloroethane.  It appears that hazardous substances not normally found
in oil were released from this tank.  Therefore, while CERCLA's "Petroleum Exclusion" policy may apply
here, EPA believes that this action is appropriate to protect the public and the environment.  The State
of Delaware has concurred with this remedial action.

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Record of Decision
Underground Storage Tank at Building 124  (Site WP 32)
Dover Air Force Base
Kent County, Delaware

                                DECISION SUMMARY
Introduction

Dover Air Force Base (DAFB),  in consultation with the U.S. Environmental Protection Agency (EPA) and the
State of Delaware, Department of Natural Resources and Environmental Control (DNREC),  has evaluated all
available data for the Underground Storage Tank  (UST) at Building 124.  This Record of Decision (ROD)  has
been prepared by DAFB,  the lead agency for response actions at the site, to present the selected
alternative for this operable unit.  This selected alternative addresses constituents in the soil.
Groundwater will be addressed under a separate base-wide action.

The ROD utilizes information developed during a site investigation (SI) conducted in June 1991 and the
remedial investigation field work conducted in September 1993.  No comments were received on the Proposed
Plan during the public comment period.

Site Name, Location & Description

The UST at Building 124 is located in the southeastern portion of the industrial section of Dover Air
Force Base.  The base is located in Kent County, Delaware, 3.5 miles southeast of the City of Dover (Fig
1).   Bounded to the southwest by the St. Jones River, DAFB comprises approximately 4,000 acres, including
annexes, easements, and leased property.  The surrounding area is primarily cropland and wetlands with
limited residential areas  (Fig 2).

Site History and Enforcement Activities

Dover AFB began operation in December 1941 as a U.S. Army Air Corps coastal patrol base.  In August 1943,
the mission of the base changed to an operational training base for combat aircraft and development of
air-launched rockets.

When DAFB was listed on the National Priorities List in 1989, the UST at Building 124 was identified as
having the potential to release hazardous substances to the environment.  There have not been any federal
or state enforcement or permitting activities pertaining to this UST.

The UST at Building 124 is a 1,000-gallon underground storage tank that received waste oil from the
automobile hobby shop.




The tank began receiving oil in 1969.  Waste oil from vehicle oil changes was poured into a receiving
basin within the building. The oil flowed by gravity through a pipe into the tank.  Contents of the tank
were disposed of by a civilian contractor.  In 1991, responsibility for disposal of the tank contents was
transferred to the Defense Reutilization and Marketing Office (DRMO).

The waste oil was sampled and characterized using the Toxicity Characteristic Leaching Procedure  (TCLP)
prior to disposal by DRMO.  None of the analytes tested for in the TCLP leached above detection limits.
Use of the tank continued until mid-1991, when an above ground tank was installed to hold the waste oil.

The possibility of previous uncontrolled releases from the UST at Building 124 was evaluated by analysis
of subsurface soil samples during the 1991 Site Investigation.  Four samples were collected from four
separate borings  (B117 - B120)  at depths from 2-10 feet or 2-12 feet below ground surface (BGS) (Fig 3).
An additional composite soil sample comprised of surface soil from all of the four borings was also
collected.  Soil samples were analyzed for volatile organic compounds  (voc), semi-volatile organic
compounds  (SVOC), and lead.

A limited number of organic analytes were detected in the subsurface soil sample at this site with
elevated concentrations. Lead was detected at a concentration of 747 mg/kg  (milligram per kilogram, or
parts per million) in sample B 120.2-12.

The risk assessment within the SI concluded that of the six analytes detected at this site,  only lead
approached its health based action level.  The action level for lead is based on the EPA industrial
cleanup level of 1000 mg/kg.   The SI recommended further study at this site to delineate the extent of

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lead contamination.

Further study was undertaken to address contaminants in this area as part of the base-wide remedial
investigation of DAFB.  Two soil borings  (B429 and B430) were drilled adjacent to the tank (Fig 3) on
both sides of the SI boring B120.2-12.  Four samples were collected and analyzed for VOCs, SVOCs, metals,
and total petroleum hydrocarbons (TPH).  One sample from boring B429 was analyzed for pesticides and
polychlorinated biphenyls  (PCB).

The VOCs methylene chloride and acetone were detected in all of the samples at relatively low
concentrations.  These compounds are common laboratory contaminants and were also found in the associated
sample blanks.  The VOC 1,1,1-Trichloroethane was also found in two of the samples at the approximated
concentrations of 4 and 9 jig/kg  (micrograms per kilogram, or parts per billion). These values are well
below the Maximum Contaminant Level  (MCL)  of 200 parts per billion (ppb).   Therefore, if all of the
compounds were to migrate into the groundwater, they would not pose a risk.  No other VOCs were detected
in any of the Remedial Investigation samples.



Antimony, cadmium, and thallium were not detected; however,  the laboratory detection limits were higher
than the DAFB background concentrations.  The risk based concentrations (RBC) for antimony, cadmium, and
thallium are 410 mg/kg, 510 mg/kg,  and 72 mg/kg (based on Thallic Oxide, T1203) respectively (Smith,
October 1993).  These RBCs are well above the detection limits of 9.B mg/kg for antimony, 1.1 mg/kg for
cadmium and 0.65 mg/kg for thallium.  This indicates the soil concentration of the metals are well below
the RBCs and therefore, the three metals discussed do not pose a risk to human health.  Laboratory report
sheets for organic and inorganic analyses are presented in attachment 1.

Except for lead, no other metal was detected in the samples at levels significantly above reported DAFB
background concentrations  (Dames and Moore, December 1993).   Lead levels in samples collected during the
1993 Remedial Investigation fieldwork ranged from 2.3 to 4.5 mg/kg.  This level is within the range of
DAFB background levels and below the EPA industrial cleanup level of 1000 mg/kg.   Two samples were
collected by DAFB from a separate boring adjacent to SI boring B120.2-12 at depths of 5 and 10 feet BGS.
These samples were collected to address concerns regarding an earlier lead detection of 747 mg/kg near
the underground storage tank.  A toxicity characteristic leaching procedure  (TCLP)  test was performed to
assess the potential for lead or other metals present at the site to leach from the soil and contaminate
the groundwater.  None of the metals tested leached above their detection limits.  TCLP results are
presented in Attachment 2.

Total petroleum hydrocarbons (TPH)  were present in all the samples collected during the Remedial
Investigation.  The concentration of TPH ranged from 14.8 to 21.B mg/kg.  This value is well below the
action level of 1000 mg/kg promulgated in the Delaware Regulations Governing Underground Storage Tanks
(DRGUST) Rev. 14 May 1993.  Benzene, Toluene, Ethylbenzene,  Xylene (BTEX)  were analyzed, all analytes
were below the 10 mg/kg action level. The laboratory report sheet for TPH analysis is presented in
Attachment 3.

No semi-volatiles, pesticides,  or PCBs were detected in any of the 1993 Remedial Investigation samples.

Although access restrictions prevented samples from being taken from the waste oil remaining in the tank,
soil samples in the immediate vicinity of the tank showed the presence of elevated metals, such as lead,
and certain VOCs, such as 1,1,1-TCA.  It appears that hazardous substances not normally found in oil were
released from this tank and are either continuing to be released or have the potential to be released.

Highlights of Community Participation

The Proposed Plan for this operable unit was issued on June 12, 1994.  It was available for public review
along with the rest of the Administrative Record in the Information Repository at the Dover Public
Library, 45 State Street, Dover, Delaware 19901. The notice of public comment was published in Dover's
Delaware State News and the comment period lasted from June 12, 1994 to July 12,  1994.  During that time,
no public comments or a reguest for a public meeting were received.  Therefore, no public meeting was
held.

Scope and Role of the Operable Unit

This remedial action addresses the removal of the UST and all contaminated soil in excess of DRGUST's
promulgated levels.  The cleanup objective of this action is to reduce the potential for contamination of
the soil and groundwater as a result of leaks from the UST.   This action will remove a potential source
of soil and groundwater contamination.

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The remedial action described in this ROD does not address groundwater beneath the UST at Building 124.
Groundwater will be evaluated during the base-wide Remedial Investigation.  The remedial actions for
neighboring sites on DAFB shall be evaluated and presented as data becomes available from the base-wide
Remedial Investigation and Feasibility Study.  The selected remedy presented in this ROD is consistent
with the strategy for remediating DAFB.  Implementation of the selected alternative removes a potential
contamination source and allows resources and effort to be focused on other critical areas of the base.

Summary of Site Characteristics

The base was deactivated in September 1946.  From 1946 to 1950, the base was used periodically by the Air
National Guard.  In July 1950, the base was reactivated and designated Dover AFB. In March 1952, the base
came under the command of the Military Air Transport Service  (MATS) and the mission changed from air
and land defense to cargo operations.  Currently, DAFB is under the Air Mobility Command (AMC)  and is
home to the C-5 Galaxy Aircraft, providing global strategic airlift capability.

The surface topography of DAFB is relatively flat, with elevations ranging from 10-30 feet above mean sea
level.  Surface water runoff is handled by an extensive storm drainage network of open ditches and pipe
culverts.  The storm drainage network discharges into the St. Jones River, Pipe Elm and Morgan Branches.

The soils underlying DAFB consist mainly of silty sands.  Depth to groundwater varies across the base
from 8 to 15 feet below ground surface (BGS).  Shallow groundwater is contained within the Columbia
Aguifer.  The Columbia Aguifer consists of medium-to-coarse sand with gravelly sand, gravel, silt, and
clay lenses common throughout.  The saturated thickness of the Columbia Aguifer ranges from 15 feet in
the western portion of the base to 70 feet in the eastern portion.  Since the Columbia is the shallowest
aguifer, it is the most prone to degradation.  The Columbia Aguifer is not used as a source of drinking
water in the area surrounding DAFB.

Summary of Site Risks

When the UST at Building 124 was taken out of service in mid-1991, the tank was emptied to the maximum
extent possible. The tank was not cleaned because it lacks sufficient access. Condensation from within
the tank and moisture in the soil can work together to oxidize the metal tank and potentially additional
cause leaks.  Residual waste oil in the UST (which appears to be contaminated with heavy metals) is
leaking or has the potential to leak from the tank and continue contaminating surrounding soils and
groundwater.

Lead was detected in one soil sample adjacent to the tank during the 1991 SI at a concentration
approaching the EPA cleanup level. Subseguent soil sampling during the 1993 Remedial Investigation did
not confirm the high lead level or detect any other metals at concentrations above DAFB background
concentrations.  Samples analyzed for TCLP metals showed no metals leaching above detection limits.  No
semi-volatiles, pesticides or PCBs were detected in any of the 1993 Remedial Investigation samples at
levels of concern.

Therefore, soils at the site currently do not pose a risk to the health of on-site workers, and it is
unlikely that the soil is currently degrading groundwater above acceptable levels, because of the low
concentrations of contaminants that were detected in soil samples.  Groundwater at the site will be
addressed during the basewide Remedial Investigation which is underway.  If groundwater contamination is
detected, it will be addressed under a separate remedial action.

The base wide ecological assessment  (EA)  indicates the likelihood of exposure to the soil by terrestrial
wildlife is low.  The UST at Building 124 is located within a chain link fence and surrounded with
asphalt pavement.  Since the use of the facility will be as a recycling center, the pavement would be
maintained, thus reducing the chance of any exposure to site soils.

Description of Alternatives

This section summarizes the three alternatives reviewed for analysis and fulfillment of applicable or
relevant and appropriate reguirements.  The reviewed alternatives for the UST at Building 124 include:

           Alternative 1:                    No Action
           Alternative 2:                    Abandon tank in place
           Alternative 3:                    Remove tank and all contaminated soil

Alternative 1:  The CERCLA regulations reguire that a "No Action" alternative be evaluated at every site
to establish a base line of comparison.  If this alternative is selected, no remedial action would be
undertaken at this time.  The site conditions would remain as they are and the gualitative risks

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discussed above would continue.  There would be no reduction of the possible threat to human health and
the environment.

Alternative 2:  Under Alternative 2, the UST would be abandoned in place following the DRGUST.  Under
these regulations, the piping to the UST would be excavated and removed.  The interior of the UST would
be cleaned and the resulting liguid disposed of. The UST would then be filled with concrete to complete
the abandonment.  Given the fact that the tank is small (1000 gallons) and has no access hatch, cleaning
the tank would be impractical.

Alternative 3:  Under Alternative 3, the UST at Building 124 would be removed following the DRGUST.
Piping would be excavated and removed.  The UST would be removed, cleaned, dismantled, and disposed of in
accordance with DRGUST.  Visible contaminated soils and soil directly beneath the tank would be sampled
and disposed of according to the DRGUST.  DRGUST's cleanup levels for soils associated with a tank
removed at this site are 10 ppm total for BTEX  (benzene, toluene, ethylbenzene, xylene), 100 ppm total
TPH, and 1 ppm total VOC.  The UST excavation would be backfilled and an asphalt cap installed to allow
reuse of the area as a parking lot.

Summary of the Comparative Analysis of Alternatives

This section provides an analysis of the performance of the alternatives in comparison to one another.
The alternatives are evaluated using the nine criteria as set forth in 40 C.F.R. Section 300.430(e).

Overall Protection:  Alternatives 2 and 3 will provide an acceptable level of protection of human health
and environmental safety by eliminating the principal threats through contaminant source reduction and
treatment.  The "No Action" alternative would not afford any protection of human health and the
environment.

Compliance with the ARARs:   Alternatives 2 and 3 would meet their respective applicable or relevant and
appropriate reguirements of federal and state environmental laws, in particular, Title VII, Chapter 74 of
the Delaware Code and the Delaware "Regulations Governing Underground Tank Systems" Revised May 14, 1993.
However, only Alternative 3 provides for sampling directly beneath the UST.

All materials to be handled under Alternatives 2 and 3 will comply with RCRA's regulations pertaining to
the treatment, storage, and disposal of wastes as defined in 40 C.F.R.,  Parts 260 through 268.

Long-Term Effectiveness and Permanence:  Neither Alternative 1 nor 2 completely satisfy both long-term
effectiveness and permanence of remediation.  Alternative 3 will greatly reduce the risks presented by
possible releases from the tank.  Removal of potentially contaminated soil from beneath the tank will
eliminate a potential source of groundwater contamination.

Reduction in Toxicitv, Mobility, or Volume Through Treatment: Both Alternatives 2 and 3 will reduce the
toxicity and mobility of the potential contaminants at the site.  Only Alternative 3, however, provides
for removal and cleaning of the UST eliminating toxic hazardous substances and waste oil residuals from
the tank.  Removal of the UST will allow for the excavation of any contaminated soil from beneath the
tank, thereby reducing the chance of future release of contamination.  Alternative 2 may allow for the
removal of some of the waste oil residuals from the tank.   However, since the tank is left in place after
cleaning, potentially contaminated soil beneath this tank and any residuals not removed from the tank
would still pose a risk.  Alternative 1 will not reduce the toxicity, mobility, or volume of any
contaminants at this site.

Short-Term Effectiveness:  Alternatives 2 and 3 can implement tank remediation in a short period of time,
approximately 2 weeks, thereby rapidly eliminating a current continuing release or the threat of a
potential release.  Alternative 2 becomes effective upon completion of tank clean out.  Alternative 3
becomes effective upon tank and soil excavation.  Alternative 1 does nothing to address potential
releases from the tank.

Alternatives 2 and 3 include excavation and capping and, therefore, could pose short-term risks of
exposures to volatiles and inorganic particulate emissions during construction.  Off-site disposal of
excavated soils, if any, will occur within a 2-week span,  so worker and public exposure is of minimal
risk. Alternative 1 poses no short-term risk.

Implementabilitv:  Alternatives 2 and 3 would implement tank remediation in a short period of time,
approximately 2 weeks, thereby rapidly eliminating the threat of a potential release. Alternative 1
reguires no action and can be implemented immediately.

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Alternatives 2 and 3 both employ a proven and reliable technology, and will likely be able to implement
the remedy using conventional eguipment.  These two alternatives also provide the best means to monitor
the effectiveness of the remediation.

No difficulties with obtaining approvals from any other Federal Agency, the state or local community are
expected for any of the alternatives.

Cost:  Alternative 1 has no cost associated with its implementation.  Alternatives 2 and 3 are estimated
to cost approximately the same amount, $55,000.

State Acceptance:  The State of Delaware supports the Proposed Plan's preferred alternative.

Community Acceptance:  Since no comments were received during the public comment period, the community
would appear to support the Proposed Plan's preferred alternative.

Selected Alternative

The selected alternative for the UST at Building 124 is Alternative 3, removal of the tank, piping, and
contaminated soil.  This proposed alternative provides the best balance of trade-offs among the listed
evaluation criteria and the mandate to consider alternative treatments with the preference for permanent
solutions.

The selected alternative calls for the removal, treatment, and disposal to an DRGUST authorized landfill
of the UST, its associated piping, and soil contaminated above DRGUST's risk based levels.

The excavation will then be backfilled with clean soil and capped with asphalt.  Because the UST, its
contents, and the contaminated soil surrounding it will be removed, no additional monitoring, beyond
sampling to assure compliance with DRGUST's cleanup levels, is expected.

The cost to implement this remedy is expected to be about $55,000.

Statutory Determinations

The selected remedial action satisfies the remedy selection process reguirements of CERCLA and the NCP.
The selected remedy also provides adeguate protection of human health and the environment, achieves
compliance with all applicable or relevant and appropriate reguirements, utilizes a permanent solution,
and is cost effective.

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GLOSSARY

Administrative Record:  An official compilation of documents, data, reports, and other information that
is considered important to the status of and decisions made relative to a site.  A public version of the
record is placed in the information repository to allow public access to the material.

Carcinogens:  Substances which can or may cause cancer.

Comprehensive Environmental Response, Compensation, and Liability Act  (CERCLA):  A federal law passed in
1980 and modified in 1986 by the Superfund Amendments and Reauthorization Act  (SARA).

Maximum Contaminant Level  (MCL):   The maximum permissible level of a contaminant in water delivered to
any user of a public water system.  MCLs are enforceable standards.

Information Repository  (IR):  A location where copies of documents and data related to the site are
placed to allow the public access to the material.  The IR also contains an index for the Administrative
Record.

National Priorities List  (NPL):  EPA's list of the nation's top priority hazardous waste sites

Operable Unit (OU):  A discrete portion of work undertaken as part of the overall cleanup program.  OUs
can be determined geographically  (grouping several sites), as phases of a complete action at a single
site, or any combination of these.

Record of Decision  (ROD):  A legal document that describes the final remedial  action selected for a site,
why the remedial action was chosen, how much it will cost, and how the public  responded.

Risk Assessment (RA):   A means of estimating the amount of harm which a site could cause to human health
and the environment. The objectives of a risk assessment are  (1) to help determine the need for action by
estimating the harm if the site is not cleaned up, (2) to help determine the levels of chemicals that can
remain on the site and still protect human health and the environment, and  (3) to provide a basis for
comparing different cleanup methods.

1,1,1-TCA:  1,1,1-Trichloroethane.

Target Analyte List (TAL):  A subset of the Target Compound List which includes only inorganic
constituents.

Target Compound List  (TCL):  Developed by EPA for Superfund site sample analyses.  The TCL is a list of
analytes  (34 VOCs, 65 SVOCs, 19 pesticides, and 7 PCBs.

Upper Confidence Limit  (UCL):  The upper limit of a statistical range with a specified probability that a
given parameter lies below this limit.

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REFERENCES

Dames and Moore, Inc./HAZWRAP, site Investigation for the Underground Storage Tank At Site S-6  (MAC Code
WP32), DAFB, September 1991.

Dames and Moore, Inc./HAZWRAP, Remedial Investigation data, 1993,  (Report not complete).

Shacklette, H.T., and J.G. Boerngen, 1984.  Element Concentrations in Soils, and Other Surficial
Materials of the Conterminous United States, U.S. Geological Survey, Professional Paper No.  1270.

Shacklette, H.T., and J.G. Boerngen, 1981.  Chemical analysis of soils, and Other Surficial  Materials of
the Conterminous United States, U.S. Geological Survey, Open-file Report 81-197.

Smith, Roy, Oct 1993.  Risk-Based Concentrations, USEPA, letter.

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                        ATTACHMENT 1

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                        ATTACHMENT 2
                     REPORT OF ANALYSIS

Project Name:  Dover Air Force Base

Date Sample Collected:  12/2/93

Date Sample Received:  12/7/93
Project Number:  209993

Collected By: Client

Sample Type:  Soil
Analysis Requested:  TCLP RCRA 8 Metals  (CLIN 0019)
Date Sample Analyzed:  12/7 - 12/8/93

Method of Analysis:  55 FR 11876

        Parameter
Arsenic, mg/L
Barium, mg/L
Cadmium, mg/L
Chromium, mg/L
Lead, mg/L
Mercury, mg/L
Selenium, mg/L
Silver, mg/L
Analyst:  REP/AM
155336
GM939029
<0.010
<0.125
<0.25
<1.0
<0.25
<0.005
<0.013
<0.5
155337
GM939030
<0.010
<0.125
<0.25
<1.0
<0.25
<0.005
<0.013
<0.5
Regulatory
Limit
5,
100,
1,
5,
5,
0,
1,
5,
.0
.0
.0
.0
.0
.2
.0
.0

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                                ATTACHMENT 3
COMPUCHEM
LABORATORIES, INC
                TOTAL PETROLEUM HYDROCARBONS
                       SUMMARY  REPORT
ITEM
NO.
1.
2.
3.
4.
5.
6.
7.
SAMPLE
IDENTIFIER
B429A
B429B
B429C
B429CDUP
B430A
B430B
B430C
COMPUCHEM
NUMBER
578355
578357
578362
578364
578366
578368
578370
CONCENTRATION
(mg/kg)
21.8
21.5
16.8
17.1
14.8
16.6
21.3
                                                       DETECTION LIMIT
                                                          (mg/kg)

                                                            6.3
                                                            6.3
                                                            6.3
                                                            6.3
                                                            6.3
                                                            6.3
                                                            6.3
BRL =
         BELOW REPORTABLE  LIMIT
Reviewed by/ID#:
Reviewed by/ID#:
Date:
Date:

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