Superfund Record of Decision New London Submarine Base Defense Reutilization Marketing Office Contaminated Soil and Groundwater Groton CT


                                    EPA/ROD/R01-98/002
                                    1998
EPA Superfund
     Record of Decision:
     NEW LONDON SUBMARINE BASE
     EPA ID: CTD980906515
     OU02
     NEW LONDON, CT
     03/31/1998

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EPA 541-R98-002


                                  INTERIM
                             RECORD OF DECISION
                                    FOR
                     DEFENSE REUTILIZATION AND MARKETING
                       NAVAL SUBMARINE EASE NEW LONDON
                             GROTON, CONNECTICUT

                         COMPREHENSIVE LONG-TERM
                  ENVIRONMENTAL ACTION NAVY(CLEAN)CONTRACT
                                Submitted to:
                              Northern Division
                         Environmental Branch Code 18
                     Naval Facilities Engineering Command
                     10 Industrial Highway, Mail Stop #82
                       Lester, Pennsylvania 19406-1433
                                Submitted by:
                         Brown & Root Environmental
                          600 Clark Avenue, Suite 3
                 King of Prussia, Pennsylvania 19406-1433

                                 February 1998

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                          TABIiE OF CONTENTS

SECTION                                                                           PAGE

LIST OF ACRONYMS AND ABBREVIATIONS	V

GLOSSARY	G-l

DECLARATION FOR THE INTERIM RECORD OF DECISION	1

1.0   SITE NAME, LOCATION, AND DESCRIPTION	1-1

2 . 0   SITE HISTORY AND ENFORCEMENT ACTIVITIES	2-1
       2.1     LAND USE AND SITE HISTORY	2-1
       2 . 2     RESPONSE AND ENFORCEMENT HISTORY	2-1

3.0   COMMUNITY PARTICIPATION	3-1

4 . 0   SCOPE AND ROLE OF RESPONSE ACTION	4-1

5 . 0   SUMMARY OF SITE CHARACTERISTICS	5-1
      5 .1     TOPOGRAPHY AND SURFACE FEATURES	5-1
       5 . 2     SURFACE WATER FEATURES	5-1
       5 . 3     SOIL CHARACTERISTICS	5-1
       5.3.1   Geology	5-7
       5 . 4     HYDROGEOLOGY	5-7
       5.5     ECOLOGICAL HABITAT	5-9
       5 . 6     SUMMARY OF NATURE AND EXTENT OF CONTAMINATION	5-9
       5.6.1   DRMO Soil	5-9
       5.6.2   DRMO Groundwater	5-22
       5.6.3   DRMO Surface Water	5-23

6 . 0   SUMMARY OF SITE RISKS	6-1
       6.1     CONTAMINANT IDENTIFICATION	6-1
       6 . 2     EXPOSURE ASSESSMENT	6-4
       6 . 3     TOXICITY ASSESSMENT	6-4
       6.4     RISK CHARACTERIZATION	6-5
       6.4.1   Summary of Human Health Risk Characterization	6-5
       6.4.2   Remediation Goals for Human Health Protection	6-9
       6.4.3   Summary of Ecological Risk Assessment	6-10
       6.4.4   Remediation Goals for Protection of Ecological Receptors	6-11
       6.4.5   Remediation Goals for Protection of Surface Water	6-16
       6.4.6   Discussion of Uncertainty Factors	6-17
       6.5     CONCLUSION	6-19

7 . 0   REMEDIAL ACTION OBJECTIVES AND DEVELOPMENT OF ALTERNATIVES	7-1
       7 .1     STATUTORY REQUIREMENTS/RESPONSE OBJECTIVES	7-1
       7 . 2     TECHNOLOGY SCREENING AND ALTERNATIVE DEVELOPMENT	7-2

8 . 0   DESCRIPTION OF ALTERNATIVES	8-1
       8 .1      ALTERNATIVE  1  -  NO  ACTION	8-1
       8.2      ALTERNATIVE  2  -  INSTITUTIONAL CONTROLS AND MONITORING	8-1
      8.3       ALTERNATIVE  3  -  "HOT SPOTS" EXCAVATION, OFFSITE DISPOSAL,
                 INSTITUTIONAL CONTROLS,  AND MONITORING	8-2
      8.4       ALTERNATIVE  4  -  EXCAVATION, ON SITE TREATMENT (THERMAL
                DESORPTION & FIXATION-SOLIDIFICATION), AND OFFSITE DISPOSAL	8-4

9. 0   SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES	9-1
       9.1     EVALUATION CRITERIA USED FOR DETAILED ANALYSIS	9-1
       9.1.1   Threshold Criteria	9-1
       9.1.2   Primary Balancing Criteria         	9-1
       9.1.3   Modifying Criteria	9-2
       9 . 2     COMPARATIVE ANALYSIS OF ALTERNATIVES BY CATEGORY	9-2
       9.2.1   Overall Protection of Health and Environment	9-2
       9.2.2   Compliance with ARARs and TBCs	9-3
       9.2.3   Long-term Effectiveness and Permanence     	9-4

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        9.2.4   Reduction of Toxicity, Mobility, or Volume through Treatment	9-5
        9.2.5   Short-term Effectiveness	9-5
        9.2.6   Implementability	9-6
        9.2.7   Cost	9-8
        9.2.8   State Acceptance	9-8
        9.2.9   Community Acceptance	9-8

10 . 0   SELECTED REMEDY	10-1
        10 .1      COMPONENT 1:  INSTITUTIONAL CONTROLS	10-1
        10.1.1.   Cap Maintenance     	10-1
        10.1.2    Limitations on Site Access        	10-1
        10.1.3    Land Use Restrictions      	10-2
        10 . 2      COMPONENT 2 :  GROUNDWATER MONITORING	10-4

11. 0   STATUTORY DETERMINATIONS	11-1
        11.1      PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT	11-1
        11. 2      COMPLIANCE WITH ARARS	11-1
        11. 3      COST EFFECTIVENESS	11-1
        11.4      UTILIZATION OF PERMANENT SOLUTIONS AND ALTERNATIVE TREATMENT
                 OR RESOURCE RECOVERY  TECHNOLOGIES  TO  THE MAXIMUM EXTENT
                 PRACTICABLE	11-5
       11.5       PREFERENCE FOR TREATMENT AS A PRINCIPAL ELEMENT	11-5

12 . 0   DOCUMENTATION OF NO SIGNIFICANT CHANGES	12-1

13.0   STATE ROLE	13-1

APPENDICES

     A      PUBLIC MEETING TRANSCRIPT
     B      CTDEP COMMENTS ON PROPOSED PLAN
     C      RESPONSIVENESS SUMMARY
     D      DECLARATION OF CONCURRENCE

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                                  TABLES
NUMBER                                                                                  PAGE

5-1    Summary of Soil Analytical Results	5-12
5-2    Summary of Phase I Groundwater Analytical Results (Unfiltered)	5-17
5-3    Summary of Round I/Phase 11 Groundwater Analytical Results	5-18
5-4    Summary of Round 2/Phase 11 Groundwater Analytical Results	5-20
6-1    Estimated Human Health Risks	6-6
6-2    Summary of Human Health COCs for Remediation Goal Development	6-8
6-3    Major Contributors to Risk for Terrestrial Vegetation Based on RME and CTE
        Exposure,  DRMO	6-12
6-4    Major Contributors to Risk for Soil Invertebrates Based on RME and CTE Exposure,
       DRMO	6-13
6-5    Major Contributors to Risk for Terrestrial Vertebrates RME Scenario,  DRMO	6-14
6-6    Major Contributors to Risk for Terrestrial Vertebrates CTE Scenario,  DRMO	6-15
 11-1  Assessment of Chemical-Specific ARARs and TBCs for Alternative 2 - Institutional
        Controls and Monitoring	11-2
 11-2  Assessment of Location-Specific ARARs and TBCs for Alternative 2 - Institutional
        Controls and Monitoring	11-3
 11-3  Assessment of Action-Specific ARARs and TBCs for Alternative 2 - Institutional
        Controls and Monitoring	11-4

                                  FIGURES

NUMBER                                                                                    PAGE

1-1    Location Map	1-2
1-2    DRMO Location Map	1-3
5-1    Former Sampling Locations	5-3
5-2    Time-Critical Removal	5-5
10-1   Groundwater Monitoring Plan Decision Diagram	10-5

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                       LIST  OF ACRONYMS  AND ABBREVIATIONS

ARAR          Applicable  or  Relevant and Appropriate Requirements
AWQC          Ambient Water  Quality Criteria
CERCLA        Comprehensive  Environmental Response,  Compensation,  and  Liability Act of 1980
CFR           Code of Federal  Regulations
CGS           Connecticut  General  Statutes
CLEAN         Comprehensive  Long-Term Environmental Action Navy
COC           Contaminants of  Concern
CSF           Cancer Slope Factor
CTDEP         State of Connecticut Department of Environmental Protection
CTE           Central Tendency Exposure
CTO           Contract task  order
CWA           Clean Water  Act
DRMO          Defense Reutilization and  Marketing Office
DW/WWT        Dewatering/Wastewater Treatment
ERA           Ecological  Risk  Assessment
FFA           Federal Facilities Agreement
FFS           Focused Feasibility  Study
FS            Feasibility  Study
GAC           Granular Activated  Carbon
GCL           Geosynthetic Clay Liner
GRA           General Response Actions
HBL           Health Based Limit
HI            Hazard Index
HQ            Hazard Quotient
ICR           Incremental  Cancer  Risks
IEUBK         Integrated  Exposure  Uptake Biokinetic
IR            Installation Restoration
IRA           Interim Removal  Action
MCL           Maximum Contaminant  Levels
NCP           National Contingency Plan
NPL           National Priorities  List
NSB-NLON    Navy Submarine Base New London
O&M           Operation and  Maintenance
ORNL          Oak Ridge National  Laboratory
OSHA          Occupational Safety  and Health Administration
PAH           Polynuclear  Aromatic Hydrocarbons
PCB           Polychlorinated  Biphenyls
PPE           Personal Protective  Equipment
PRG           Preliminary  Remedial Goal
RAB           Restoration  Advisory Board
RAO           Remedial Action  Obj ectives
RCRA          Resource Conservation and  Recovery Act
RCSA          Regulations  of Connecticut State Agency
RfD           Referenee Dosage
RI            Remedial Investigation
RME           Reasonable Maximum  Exposure
ROD           Record of Decision
SARA          Superfund Amendments and Reauthor!zation Act
SCS           United States  Department of Agriculture Soil Conservation  Service
SSL           Soil Screening Levels
SWPC          Surface Water  Protection Criteria
TBC           To be considered
TCLP          Toxicity Characteristic Leaching Procedure
TSD           Treatment,  Storage,  Disposal
USEPA         United States  Environmental Protection Agency
USGS          United States  Geological Survey
VOC           Volatile Organic Compound

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GLOSSARY

Applicable, or Relevant and Appropriate Requirements (ARARs) - The Federal and state environmental and
facility siting rules, regulations, and criteria which must be met by the selected remedy under
Superfund.

Asphalt/GCL cap - Cover made up of a layer of asphalt and a Geosynthetic Clay Liner (GCL) which was
placed over areas of contaminated soil at DRMO in 1995. The GCL is a fabricated liner which consists of
an impervious layer of bentonite clay "sandwiched" between two permeable layers of geotextile fabric.

Chemical fixation-solidification - Controlled mixing of waste material (typically soil or sludge) with
selected chemicals which induce a solidification of this material and the immobilization (fixation) of
certain contaminants within the solidified material.

Contaminants - Any physical, biological, or radiological substance or matter that, at a certain
concentration, could have an adverse effect on human health and the environment.

Excavation - Earth removal with construction equipment such as backhoe, trencher, front-end loader, etc.

Feasibility Study (FS) - A report that presents the development, analysis, and comparison of remedial
alternatives.

Groundwater - Water found beneath the earth's surface. Groundwater may transport substances that have
percolated downward from the ground surface as it flows towards its point of discharge.

"Hot Spots" - Those areas of soil at DRMO where contaminant concentrations result in unacceptable risk to
site workers if the site continues to be used as it presently is.

Landfilling - Controlled burial of material at a site specifically designed for this purpose.

PAHs - Polycyclical Aromatic Hydrocarbons. High molecular weight, relatively immobile, and moderately
toxic solid organic chemicals featuring multiple benzenic (aromatic) rings in their chemical formula.
Typical examples of PAHs are naphthalene and phenanthrene.

PCBs - Polychlorinated Biphenyls. High molecular weight, moderately mobile, and moderately to highly
toxic liquid organic chemicals featuring two benzenic rings and multiple chlorine atoms in their chemical
formula. In the past, PCBs were commonly used as cooling fluid in electronic transformers and, as a
result, PCB contamination is relatively widespread.

Record of Decision (ROD) - An official document that describes the selected Superfund remedy for a site.
The ROD documents the remedy selection process and is issued by the Navy and U.S. EPA following the
public comment period.

Remedial Investigation (RI) - A report which describes the site, documents the type and distribution of
contaminants detected at the site, and present the results of the risk assessment.

Responsiveness Summary - A summary of written and oral comments received during the public comment
period, together with the Navy's and U.S. EPA's responses to these comments.

Risk Assessment - Evaluation and estimation of the current and future potential for adverse human health
or environmental effects from exposure to contaminants.

Sediment - Soil, sand, and minerals typically transported by erosion from soil to the bottom of surface
water bodies, such as streams, rivers, ponds, and lakes.

Source - Area(s) of a site where contamination originates.

Surface Water - Water from streams, rivers, ponds, and lakes. For this ROD surface water means water of
the Thames River.

Thermal Desorption - Removal of volatile and semivolatile contaminants (typically organic chemicals)
through heating of the contaminated material with hot air, followed by capture and treatment of the
removed contaminants from the exhaust gases.

Time Critical Removal Action - Site cleanup action conducted on an accelerated schedule for the rapid
correction of an environmental situation of particular concern.
Vadose - Soil above the typical groundwater level.

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DECLARATION FOR THE INTERIM RECORD OF DECISION

SITE NAME AND LOCATION

The Defense Reutilization and Marketing Office (DRMO) is located on the Naval Submarine Base New London
(NSB-NLON), Groton, Connecticut. This Interim Record of Decision (Interim ROD) addresses the contaminated
soil and groundwater at this site.

STATEMENT OF BASIS AND PURPOSE

This Interim ROD presents the following interim remedy for soil and groundwater at the DRMO:

• Institutional Controls
• Monitoring

The selected remedial action was chosen in accordance with the Comprehensive Environmental Response,
Compensation, and Liability Act (CERCLA) of 1980, as amended by the Superfund Amendments and
Reauthorization Act (SARA) of 1986, and to the extent practicable, the National Oil and Hazardous
Substances Pollution Contingency Plan (NCP). This decision is based on the administrative record for the
DRMO which was developed in accordance with Section 113(k) of CERCLA, and is available for public review.
By implementing institutional controls and maintenance of the existing asphalt and geocomposite clay (GC)
layers, the U.S. Navy plans to protect potential human receptors from adverse health effects of exposure
to the underlying contaminants. By implementing monitoring, the U.S. Navy plans to verify that the
contaminants in the soil are not migrating to the Thames River through the groundwater. The Connecticut
Department of Environmental Protection (CTDEP) concurs with the selected remedy for DRMO.

ASSESSMENT OF DRMO

Actual or threatened releases of hazardous substances from this site, if not addressed by implementing
the response action selected in this Interim ROD, may present a current or potential threat to public
health, welfare, or the environment.

The U.S. Navy has determined that remedial action is necessary for this site because the risks to
potential human receptors associated with the soil at this site exceed the U.S. EPA limit of cumulative
noncarcinogenic Hazard Index (HI) of 1.0 and cumulative incremental cancer risk (ICR) of 1 x 10 -6. Also
the risks for these potential receptors exceed CTDEP Remediation Standards limit of 1 x 10 -6 Incremental
Cancer Risk (ICR) for individual contaminants with a cumulative ICR exceeding 1 x 10 -5 and cumulative HI
exceeding 1.0. Currently there are no receptors at the site that are facing a health risk although there
is a potential for migration of contaminants through the groundwater and into the Thames River. This
Interim ROD selects the remedy to address potential future risks.

DESCRIPTION OF THE SELECTED REMEDY

This remedial action addresses the soil and groundwater at the DRMO. A Time-Critical Removal Action at
the DRMO was completed in January 1995. Contaminated soils were excavated down to the water table and
disposed off site. The excavated area was backfilled and covered with a geosynthetic clayliner (GCL) and
asphalt. The remainder of the DRMO, was paved with asphalt. Contaminated soil remains in place below the
water table.

The U.S. Navy has determined that institutional controls and monitoring is appropriate for the
contaminated soil and groundwater at this site. Potential exposure to soil and potential migration of
contaminants into the groundwater are the principal threats posed by the site. This remedy involves
maintenance of the existing asphalt and GCL cover on the site, records in the Base Master Plan regarding
the contamination and restricting future land development at the site, installation of monitoring wells,
and periodic sampling and analysis of groundwater. Land use restrictions will be placed on the property.

STATUTORY DETERMINATIONS

The remedy selected by the U.S. Navy for DRMO is protective of human health and the environment, complies
with federal and state reguirements that are legally applicable or relevant and appropriate to this
remedial action, and is cost-effective. However, because this remedy will result in hazardous substances
remaining in the soils above health-based levels, groundwater monitoring will be implemented to assess
whether the remedy is achieving long-term remedial reguirements. A review of the data and site conditions
will be conducted within five years after commencement of remedial action to ensure that the remedy
continues to provide adeguate protection of human health and the environment. This remedy uses permanent
solutions and alternative treatment technologies to the maximum extent practicable for this site. The

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selected remedy does not satisfy the statutory preference for remedies,  that employ treatment as a
principal element to reduce toxicity, mobility, or volume of contaminants. Continued   maintenance of the
controls installed during the Time-Critical Removal Action provides adequate   protection of human health
and the environment from exposure to contaminated soil under current land use conditions. Protection of
the environment will be assessed through groundwater monitoring to evaluate contaminant migration risks.

DECLARATION

This Interim ROD represents the selection of a remedial action under CERCLA for the DRMO. The foregoing
represents the selection of a remedial action by the Department of the Navy and the U.S. EPA Region I
with the concurrence of the CTDEP..

Concur and recommend for immediate implementation:

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               1.0 SITE NAME, LOCATION, AND DESCRIPTION

NSB-NLON covers approximately 550 acres of land in the southeast of Connecticut in the towns of Ledyard
and Groton, on the east bank of the Thames River, approximately 6 miles north of Long Island Sound. For
almost 100 years, the Naval Submarine Base New London  (NSB-NLON) has served as a major support center for
the U.S. Atlantic fleet. The location of NSB-NLON is shown as the U.S. Naval Reservation on Figure 1-1.

The Defense Reutilization and Marketing Office (DRMO) is located adjacent to the Thames River in the
northwestern section of NSB-NLON as shown on Figure 1-2. The site is located between a bedrock outcrop
that runs roughly parallel to the Providence and Worcester Railroad to the east and the Thames River to
the west. The site covers approximately 3 acres of land gently sloping towards the Thames River. A
majority of the site is paved with an asphalt layer, and it features buildings, a weighing scale, and
miscellaneous storage piles. Currently, the DRMO is used as a storage and collection facility for items
such as computers, file cabinets, and other office equipment to be sold during auctions and sales held
periodically during the year.

   
   

                2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES

This section summarizes the land use, response history, and enforcement history for the DRMO.

2.1    LAND USE AND SITE HISTORY

For almost 100 years, the NSB-NLON has served as a major support center for the U.S. Atlantic fleet. From
1950 to 1969, the DRMO was used as a landfill and waste burning area. Non-salvageable waste items
including construction materials and combustible scrap were burned along the Thames River shoreline, and
the residue was pushed to the shoreline and partially covered.

At various times, metal and wood products have been stored over most of the site. Building 491, located
in the northern, unpaved portion of the site was used to store miscellaneous items including batteries.
Metal scrap bailing operations are performed adjacent to Building 491 on a gravel surface. Building 491
formerly housed a battery acid handling facility.

Buildings 355 and Building 479 are located in the southern, paved, portion of the site and are primarily
used for storage. A large scrap yard is located north of Building 479. Details of the site are described
in Section 5.0 and depicted on Figure 5-1.

Submarine batteries were previously stored in the southeast portion of the site adjacent to the railroad
tracks. No evidence of leaks was observed.

2.2    RESPONSE AND ENFORCEMENT HISTORY

The U.S. Navy has placed 25 sites under the purview of the Installation Restoration Program. Depending on
the characteristics of the sites, the media of concern at these sites are: soil, sediment, groundwater,
surface water, and air. Records of Decision have been issued for some of these sites, and of these sites,
remedial actions have been completed at several of them. The majority of the remaining sites are under
various stages of remedial investigation and feasibility study preparation. Some of the sites have been
classified low priority based on low risk ranking by the U.S. Navy and will not be investigated at this
time.

The IRP and CERCLA. In 1975, the Department of Defense developed a program to investigate and clean up
problem areas involving contamination of land and water at Federal facilities such as the NSB-NLON. That
program, known as the Installation Restoration Program  (IRP), is being conducted in accordance with the
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), commonly referred to as
the Superfund law. In 1986, Congress passed amendments to CERCLA that contain provisions for Federal
facilities. NSB-NLON was placed on the National Priorities List (NPL) of Federal Superfund sites on
August 30, 1990, by the U.S. Environmental Protection Agency  (U.S. EPA).

Initial Assessment Study (IAS). An IAS (Envirodyne, 1982) was conducted to identify and evaluate past
hazardous waste disposal practices at NSB-NLON and to assess the associated potential for environmental
contamination. The IAS recommended further investigation of several areas including the DRMO.

Federal Facility Agreement  (FFA). The U.S. Navy entered into an FFA with the U.S. EPA and the Connecticut
Department of Environmental Protection (CTDEP) on January 5,  1995. The FFA established roles and
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responsibilities of each agency, set deadlines for the investigation and cleanup of hazardous waste
sites, and established a mechanism for the resolution of disputes among agencies.

Remedial Investigations, studies, and removal action conducted to date. A Phase I Remedial Investigation
(RI)  (Atlantic, 1992), a Phase II RI (B&R Environmental, March 1997), and a Focused Feasibility Study
(FFS, Atlantic 1993) were conducted over the course of several years, ending in March 1997. A
time-critical removal action was completed in January 1995  (OHM, September 1995)wherein approximately
4,700 tons of soil contaminated with lead, polynuclear aromatic hydrocarbons (PAHs),  and PCBs were
excavated from the site down to the water table and disposed of at an offsite hazardous waste landfill.
Contaminated soil below the groundwater level was left in place. The excavated area was backfilled with
clean borrow material from an offsite location, and the area was capped with geosynthetic clay/geotextile
layers and overlaid by gravel/asphalt layer. At the time of completion of the removal action, the
remaining area was also paved with an asphalt layer.

Feasibility Study (FS) and Proposed Remedial Action Plan  (PRAP). A draft final FS for this site (B&R
Environmental, September 1997) and a PRAP (U.S. Navy and B&R Environmental, September 1997) based on this
FS were prepared for this site. The scope of this FS was limited to the soil and groundwater at the site.
However, this FS also addressed reduction of any adverse affects that the soil and groundwater may have
on surface water in Thames River.

                       3.0 COMMUNITY PARTICIPATION

Throughout the history of the investigations and enforcement activities at NSB-NLON,  the community has
been actively involved in accordance with CERCLA Sections 113(k)(2)(B)(i-v) and 177.  Community members
and other interested parties have been kept abreast of site activities through informational meetings,
published "fact sheets and information updates," press releases, public meetings, and Technical Review
Committee (TRC)/Restoration Advisory Board  (RAB) meetings.

The TRC was established in 1988 and was later  (in 1994)  reorganized and renamed the RAS.  The RAB has been
an important vehicle for community participation in the NSB-NLON IRP. The RAB consists of representatives
of the U.S.  Navy, U.S. EPA, CTDEP, planners and officials of neighboring towns, Navy and U.S. EPA
contractors, and local residents with scientific knowledge of or interest in the sites. The RAS meets
guarterly to review technical aspects of the NSB-NLON IRP and provides a mechanism for community input to
the program.

To ensure that the community is well informed about NSB-NLON IRP activities, the Navy has provided and
will continue to provide the public with the following sources or vehicles of information.

       •      Public Information Repositories.  The Public Libraries  in Groton and Ledyard,  and the Naval
              Submarine Base,  are the designated information repositories for the Subbase IRP.

       •      Key Contact Persons.  The  Navy has designated a Public Affairs Officer and an U.S.  EPA
              Community Involvement Coordinator as information contacts for the Subbase.  Their addresses
              and phone numbers are included in all information material distributed to  the public,
              including any fact sheets and press releases.  The Public Affairs  Officer will maintain the
              site mailing list to ensure that all interested individuals receive more pertinent
              information on the IRP activities.

       •      Mailing List.  To ensure that information materials reach the individuals who are interested
              in or  affected by the IRP activities at the Subbase, the Navy maintains and will regularly
              update a mailing list of  interested persons. Anyone interested in being placed on the list
              can do so by contacting the Subbase Public Affairs Officer.

       •      Regular Contact with Local Officials.  The  Navy has managed and will continue to arrange
              regular meetings to discuss the status of  the IRP with  the RAB, which includes
              representatives from neighboring towns.  The Navy contacts other town officials on an
              as-needed basis.

       •      Press  Releases and Public Notices. The Navy has issued  and will continue to issue press
              releases to local media sources to announce public meetings and comment periods,  the
              availability of the IRP reports and plans,  and to provide general information updates as and
              when the Public Affairs Officer sees fit.
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       •      Public Meetings.  The Navy has held and will continue to hold informal public meetings as
              needed to keep residents and town officials informed about IRP activities at the Subbase and
              of  significant milestones in the IRP.  The meetings include presentations by Navy technical
              staff,   U.S.  EPA personnel,  and/or support contractors for both agencies. The meetings also
              include a guestion-and answer period.  Minutes of meetings during public comment periods are
              included in the Administrative Record for public reference.

       •      Fact Sheets and Information Updates.  The Navy has been developing a series of fact sheets
              which are mailed to public officials  and other interested individuals and/or used as
              handouts at the public meetings.  Each fact sheet includes a schedule of upcoming meetings
              and other site activities. The fact sheets may explain why the Navy is conducting certain
              activities or studies,  update readers on potential health risks,  or provide general
              information on the IRP process.

A detailed formal NSB-NLON Community Relations Plan was published in February of 1994. The plan
identifies issues of community interest and concern regarding the NSB-NLON. The plan also describes a
program of community relations activities that the Navy will conduct during the IRP.

The activities of the community relations program outlined in this plan have the following specific
objectives:  (l)to keep local officials, citizens, military personnel, and the media informed of site
activities;  (2) to increase community awareness of the goals and procedures of the IRP; and  (3) to
provide opportunities for public involvement in the cleanup process.

The information in the Community Relations Plan is based upon:

       •      interviews with area residents and local officials conducted in Groton and Ledyard on
              October 2-3,  1991;

       •      interviews with area residents and local officials conducted by phone in September and
              October of 1991;

       •      input of the TRC/RAB which had regularly met to discuss progress at the Subbase;

       •      public comments and guestions at public information meetings held in 1990 and 1991;

       •      review of Navy site files; and

       •      discussions held with Navy,  U.S.  EPA,  contractors, and technical and public affairs staff.

The U.S. Navy published a notice and brief analysis of the DRMO Proposed Plan in the New London Day on
September 18, 1997, and made the RI/FS Proposed Plan documents available to the public at the Groton
Public Library, Groton, Connecticut, and the Bill Library, Ledyard, Connecticut.

From September 18 through October 18, 1997, the U.S. Navy held a 30-day public comment period to accept
public input on the alternatives presented in the FS and the Proposed Plan, as well as other documents
previously released to the public. On September 25, 1997, NSB-NLON personnel and regulatory
representatives held a public meeting to discuss the Proposed Plan, answer guestions and concerns
regarding the site and the remedial alternative under consideration, and accept any oral comments. A
transcript of this meeting is presented in Appendix A. The Navy did not receive any written comments from
the public during the 30-day public comment period. Comments from CTDEP on the proposed plan were
received in a letter dated October 17, 1997, a copy of which is presented in Appendix B. A Responsiveness
Summary is presented in Appendix C. The Declaration of Concurrence is presented in Appendix D.

This decision document presents the selected remedial action for the DRMO at NSB-NLON, chosen in
accordance with CERCLA, as amended by SARA, and, to the extent practicable, the National Contingency
Plan. The decision for the DRMO is based on the Administrative Record.

                            4.0 SCOPE AND ROLE OF RESPONSE ACTION

This response action following the time-critical removal action that was completed in January 1995 as
described on page 2-2. The scope of this remedial action at the DRMO addressed in this ROD is limited to
the soil and groundwater. The remedial action was selected among a total of four alternatives that were
retained for detailed screening in the FS for this site, including No Action.

The selected alternative is institutional controls and monitoring. Institutional controls will consist of
maintenance of the existing cap with limitations to site access and restrictions on land development.
-------
Monitoring will consist of groundwater sampling and analysis in accordance with the Groundwater
Monitoring Plan (B&R Environmental, October 1997).  If the concentrations of groundwater COCs are shown to
exceed site-specific Surface Water Protection Criteria  (SWPC) ,  then additional action would be taken,
including expansion of the scope of monitoring to include surface water and sediment sampling, followed
by analysis to determine if COCs are migrating from the site to Thames River. If exceedances of
volatilization criteria are detected, then additional action would be taken including determining the
need for additional remedial action. Five-year site reviews will be conducted over a duration of 30
years.

                              5.0 SUMMARY OF SITE CHARACTERISTICS

This section presents a summary of site characteristics for the DRMO based on information generated
during the Phase I and Phase II RIs. This section discusses topography, surface water, soils, geology,
ecological features, and the nature and extent of contamination present at the DRMO.

5.1   TOPOGRAPHY AND SURFACE FEATURES

The DRMO topography and site features are illustrated in Figure 5-1. An exposed, bedrock highpoint,
located to the east of the DRMO, slopes steeply to the west towards the site. The ground surface within
the DRMO site boundaries gently slopes westward from an elevation of 8 feet above mean sea level (amsl)
along the eastern boundary of the site to 4 feet amsl at the Thames River. The land is relatively flat,
low lying and prone to flooding by the Thames River.

As part of the Time-Critical Removal Action, a geosynthetic clay liner (GCL) and asphalt cap were
installed over an area of excavation, and the remaining portion of the DRMO was paved with asphalt.
Buildings 479, 355, and 491 are located within the paved area.  Figure 5-2 shows the pre-excavation and
post-excavation confirmation sampling locations for this removal action at the DRMO.

5.2   SURFACE WATER FEATURES

All surface runoff from the site flows to the Thames River which is located along the western edge of the
DRMO. Two storm sewer systems located along the southern boundary of the site transfer runoff from the
eastern side of the Providence and Worcester Railroad to the Thames River (Atlantic, August 1992).  The
DRMO is within the 100-year flood plain of the Thames River.

5.3   SOIL CHARACTERISTICS

The Soil Classification Survey  (SCS) Soils Map (SCS, 1983) classifies the soil at the DRMO as Udorthents
Urban land complex. This classification is defined as being excessively drained to moderately drained
soil that has been disturbed by cutting and filling.

To the north of the site, the soil is classified as the Hinkley Loam. This soil is found on stream
terraces and outwash plains and consists of a dark, gravely sand loam. Native materials at the DRMO were
most likely of this type.




Northwest and upslope of the site, along the exposed bedrock highpoint, the soil is classified as
Hollis-Charlton-Rock complex. This classification is defined as being stones and boulders intermingled
with a dark, fine, sandy loam. Bedrock outcrops are prevalent.

5.3.1 Geology

Geologic conditions underlying the DRMO consist of a westward-thickening wedge of overburden materials
(fill and natural deposits) overlying fractured metaimorphic bedrock. The upper layer of fill material is
between 2 and 20 feet thick. The fill consists primarily of sand and gravel but also contains metal and
wood. The fill is thickest along the Thames River  (6MW2D, 6TB10, 6TB12, 6TB16, 6TB17, and 6TB19) and
thinnest at 6TB13 and 6TB15. There was no evidence of fill at 6MW7S  (southeast corner of site) or the
6MW6 and 6MW5 well clusters  (offsite) .

In most cases, the fill is underlain by clayey silt, which thickens from 2 feet along the eastern portion
of the DRMO to a maximum observed thickness of 46 feet along the Thames River. The silt layer is
underlain by sand and gravel, except at 6MW2D where the silt lies directly on bedrock. Upslope of the
DRMO at the 6MW5 and 6MW46 well clusters, the clayey silt is missing, and 20 feet of sand and gravel rest
on bedrock.
-------
The coarse-grained natural overburden materials are generally mapped as terrace deposits along the Thames
River  (USGS, 1960). These terrace deposits are stratified drift of former glacial meltwater streams.

At the DRMO, the coarse-grained terrace deposits are overlain by the clayey silt, which are finer-grained
river bottom sediments.

Bedrock in the northern portion of the DRMO has been mapped as the Granite Gneiss. Bedrock in the
southern portion of the DRMO has been mapped as the Mamacoke Formation  (USGS, 1967).  These mapped
formations were detected during drilling: the Granite Gneiss was encountered at 6MW5D and the Mamacoke
Formation was encountered at 6MW6D. The Westerly Granite has been mapped along the eastern portion of the
site, but it was not detected during drilling  (Phase I RI).  The bedrock at the DRMO slopes westward
toward the Thames River. The slope of the bedrock surface across the DRMO is approximately 25 percent.

5.4     HYDROGEOLOGY

Groundwater is present within the overburden and bedrock underlying the DRMO. The water table is
generally encountered within the fill materials at the site (between 2.5 and 10.5 feet below ground
surface), with the underlying clayey silt and terrace deposits under saturated conditions. Based on the
expected relative permeability of these three units (the coarse-grained fill and terrace deposits are
expected to be significantly more permeable than the intervening clayey silt layer) ,  the three deposits
are considered to be separate hydrostratigraphic units. The clayey silt may function as an aquitard
relative to the overlying and underlying coarser grained units.

Groundwater flow is generally from east to west, following topographic and bedrock surface slope to the
Thames River. The Thames River is tidally influenced with a mean tidal range at NSB-NLON of 2.2 feet,
which creates reversals in groundwater flow directions and causes water levels to fluctuate. Based on a
tidal study conducted as part of an Action Memorandum for Building 31 at the Lower Base, monitoring well
water levels at a distance of approximately 100 feet from the Thames River were noted to fluctuate by
1.19 feet.

Due to the proximity of the site to the river, and the demonstrated influence of tides on groundwater
levels near the river at the Lower Base, it is expected that tidal fluctuations of the river locally
affect groundwater levels, at least in the western portion of the DRMO.

During low tide, the hydraulic gradient of the groundwater table at NSB-NLON is towards the Thames River
and will result in the highest discharge rate of groundwater to the river. During high tide, the
hydraulic gradient of the groundwater is reversed and flow occurs from the river to the site, temporarily
halting the discharge of groundwater from the base to the river (B&R Environmental, March 1997).

No clear patterns for vertical groundwater flow are evident from the water level data. At well cluster
6MW2S/2D, an upward flow gradient was observed between the fill and terrace deposits during two of the
three comprehensive water level measuring rounds. At cluster 6MW3S/3D, a downward gradient was observed
between the fill and terrace deposits during two of the three measurement rounds. At cluster 6MW5S/5D, an
upward gradient was observed between the bedrock and terrace deposits during two of three measurement
rounds, while at cluster 6MW6S/6D, a downward gradient between the fill and bedrock was observed during
all three water level rounds. Vertical gradients are expected to fluctuate significantly near the river,
due to tidal fluctuations and the resulting impacts on groundwater levels. Shallow overburden groundwater
levels are expected to vary in response to the tides,  more than deeper groundwater, due to a more direct
hydraulic connection between the shallow overburden and river in comparison to deeper groundwater flow
zones.

Since the underlying clayey silt layer likely acts to minimize groundwater impacts from the DRMO to the
deep river bottom and alluvial deposits, the groundwater flux from the DRMO to the river was calculated
from the fill only. The average hydraulic conductivity of the fill materials was calculated by taking the
geometric mean of DRMO-specific hydraulic conductivities  (both Phase I RI and Phase II RI) for two wells
completed within the fill materials. Hydraulic conductivities from Phase I RI well 6MW2S  (70 ft/day) and
from Phase II RI well 6MW7S  (1.9 ft/day), were used for this calculation. The average hydraulic
conductivity calculated for the fill material is 11.5 feetlday. Using Darcy's eguation, the associated
hydraulic discharge rate was calculated to be 1,666 cubic feet/day The actual discharge rate is likely to
be substantially lower than this calculated rate, as tidal effects were not considered. During periods of
high tide, groundwater discharge to the river is expected to be halted as gradients reverse and the river
recharges the groundwater.

The groundwater is classified as GB. This classification applies to groundwater within a historically
highly urbanized area or an area of intense industrial activity and where public water supply service is
available.
-------
Such groundwater may not be suitable for human consumption without treatment due to waste discharges,
spills, or leaks of chemicals or land use impacts.

5.5    ECOLOGICAL HABITAT

The DRMO site is located in the northwestern section of NSB-NLON, adjacent to the Thames River. In the
past, the southern half of the DRMO was covered with asphalt, most of which was deteriorated, while the
northern portion was unpaved and had a gravel surface. The site was subseguently remediated in 1995, and
a GCL cap was placed over a majority of the central and northern portions of the site  (OHM, September
1995). Bituminous concrete pavement was then placed over the entire area of the composite cap as well as
most other open areas of the site. This section of the NSB-NLON is very well-developed and is
characterized by high human activity. Because of these conditions, the DRMO provides poor habitat for
wildlife and, as previously mentioned, does not constitute a critical habitat for any endangered species.

However, the site lies within the floodplain of the Thames River, which flows past the site. Potential
ecological receptors occur within the river system.

5.6      SUMMARY OF NATURE AND EXTENT OF CONTAMINATION

5.6.1	DRMO Soil

The soil analytical data are summarized in Table 5-1. Since soils excavated during the Time-Critical
Removal Action are no longer present at the site, they are not included in Table 5-1 and are also
excluded from the following discussion of the nature and extent of contamination at the site. The sample
locations are shown on Figures 5-1 and 5-2.

Several volatile organic compounds (VOCs), including carbon disulfide, vinyl chloride, monocyclic
aromatics, ketones, and several halogenated aliphatics, were detected in the surface and subsurface soils
at this site.

Most VOCs were detected infreguently  (seven of 73 total samples) and at relatively low concentrations
(less than 20 Ig/kg) , with the exception of a few subsurface soil samples. The subsurface sample from
boring 6TB4 in the central portion of the site (6 to 8 feet deep) contained the following halogenated
aliphatics:

1,12,2-tetrachloroethane (6,400 Ig/kg), 1,1,2-trichloroethane  (590 Ig/kg), 1,2-dichloroethane  (1,900
Ig/kg), 1,2-dichloroethene (16,000 Ig/kg), tetrachloroethene (210 Ig/kg), trichloroethene  (7,100 Ig/kg),
and vinyl chloride  (1,300, Ig/kg) .  These compounds and their degradation products are typically used in
degreasing operations. Their occurrence at such concentrations was limited to the sample collected from
6TB4, Xylenes (340 Ig/kg)  and acetone  (350 Ig/kg) were also detected in sample 6TB4. Xylenes  (5,400
Ig/kg) and 4-methyl-2-pentanone (5,100 Ig/kg) were detected in a subsurface soil sample 6TBI7  (10 to 12
feet deep), located near the Thames River.

Several semivolatile organic compounds (SVOCs),  including 4-methylphenol, benzoic acid, carbazole,
chlorinated benzenes, phthalates,  and polynuclear aromatic hydrocarbons  (PAHs) were detected in DRMO
soils. PAHs were the most prevalent class of chemicals observed in the soil at this site. Soil samples
collected throughout the site contained PAHs. PAHs detected most frequently  (e.g., pyrene, fluoranthene,
chrysene, benzo(b)fluoranthene, benzo(a)pyrene)  are relatively insoluble. Soluble PAHs (e.g.,
naphthalene, 2-methylnaphthalene,  dibenzofuran,  acenaphthalene) were also detected but were much less
prevalent. The presence of PAHs may be attributable to the placement of contaminated material during land
filling activities that occurred prior to construction of the DRMO, or it could be related to releases of
oily materials.  The higher concentrations generally occurred in the soils surrounding the area excavated
during the Time-Critical Removal Action.  Maximum concentrations of most PAHs in surface soils were found
in the sample collected during the Time-Critical Removal Action from location 45, along the excavation
sidewalls approximately 100 feet north of Building 479 in the central portion of the site. Maximum
concentrations of most PAHs in subsurface soils were found in a soil sample from boring 6TB17, located
approximately 60 feet further north and 50 feet east of the Thames River.

Several pesticides and polychlorinated biphenyls  (PCBs) (Aroclor-1254 and Aroclor-1260) were also
detected in soil samples collected at the DRMO site. Pesticides/PCBs were detected more frequently and at
higher concentrations in surface soils than in subsurface soils. For example, 4,4'-DDE, endrin, endrin
aldehyde, and gamma-chlordane were the pesticides detected in subsurface soils; they were each detected
in less than three of 17 subsurface samples at concentrations less than 6 mg/kg. The two Aroclors were
detected in subsurface soils © max= 12,000 Ig/kg Aroclor-1260)  and surface soils © max = 29,100 Ig/kg
Aroclor-1260) at higher concentrations than the pesticides in surface soils.
-------
A majority of the maximum concentrations of pesticides in the surface soil samples were found in samples
from locations 74 and 77, collected during the Time-Critical Removal Action near the eastern border in
the central portion of the site. Although several pesticides were detected in the surface soils,
concentrations of pesticides were low relative to PCB concentrations. With the exception of 4,4'-DDD  (227
Ig/kg)  from location 74, all pesticide concentrations were less than 65 Ig/kg. Concentrations of
Aroclor-1254 and Aroclor-1260, however, ranged up to 22,400 Ig/kg and 29,100 Ig/kg, respectively, in the
surface soil samples. Concentrations of PCBs were generally highest in the soils surrounding the
excavation area.

The subsurface sample collected from boring 6TB20 at a depth of 4 to 6 feet was the only sample analyzed
for dioxins which was not excavated during the Time-Critical Removal Action. OCDD  (3.07 Ig/kg), and
1,2,3,4,6,7,8-HpCDD  (0.67 Ig/kg) were detected in this sample.

Concentrations of metals were generally higher in surface soils than in subsurface soils. Maximum
concentrations of all metals detected in surface and subsurface samples exceeded NSB-NLON background with
the exceptions of boron  (in surface soils)  and aluminum  (in subsurface soils). Maximum concentrations of
copper, lead, sodium, and zinc in both surface and subsurface soils, and of mercury and nickel in surface
soils only, exceeded NSB-NLON background levels by more than two orders of magnitude. Maximum
concentrations of metals in surface soils were found in various soil samples collected in the northern
half of the DRMO site. A majority of the maximum concentrations of metals in subsurface samples were
found in the sample collected at a depth of 10 to 12 feet from boring 6TB17, located approximately 50
feet east of the Thames River shoreline and 40 feet north of the originally paved portion of the site.
Cyanide was also detected at concentrations less than 8 mg/kg in 27 of 56 surface soil samples and one
subsurface soil sample  (6TB20).

Barium, cadmium, chromium, lead, mercury, selenium, and silver were detected in the Toxicity
Characteristics Leaching Procedure  (TCLP) analytical results of surface soil samples. With the exception
of mercury, these same metals were detected in TCLP analytical results of subsurface soil samples. The
volatile organic compound 1,2-dichloroethane was also detected in the TCLP analysis of the subsurface
soil sample from boring 6TB20. The maximum concentration of lead in surface soils exceeded the associated
Federal Toxicity Characteristic regulatory level as shown on Table 5-1. All other inorganic
concentrations are below Federal Toxicity Characteristic regulatory levels.

Two pavement samples were collected in the scrap yard of the DRMO. Aroclor-1248, Aroclor-1254, and
Aroclor-1260 were detected in both samples at concentrations ranging from 171 Ig/kg to 388 Ig/kg. Maximum
concentrations of all three Aroclors were found in the pavement sample from boring 19. Lead was also
detected in both samples at concentrations of 10.6 mg/kg and 25.0 mg/kg from borings 19 and 20,
respectively.

5.6.2	DRMO Groundwater

The analytical results for groundwater samples collected during the Phase I RI and Rounds 1 and 2 of the
Phase II RI are summarized in Tables 5-2 through 5-4.

Limited organic contamination was noted in these samples. Trichloroethene, 1,1-dichloroethane, and 1,2
dichloroethene  (total) were detected in from one to three shallow Phase I RI samples at concentrations of
8 Ig/L or less. Maximum concentrations were all found in the sample from well 6MW4S, located in the
center of the scrap yard. These same chemicals were detected, each in one shallow well sample, at
concentrations of 3 Ig/L or less during Round 1 of the Phase II RI. Carbon disulfide  (3 Ig/L) and
1,2-dichloroethene  (total)  (2 Ig/L) were also each detected in one deep well sample during Round 1.
During Round 2 of the Phase II RI, 1,2-dichloroethene (total), trichloroethene, and/or vinyl chloride
were detected in the samples from two shallow wells  (6GW3S and 6GW8S) at concentrations of 8 Ig/L or
less. Trichloroethene (2 Ig/L) was detected in deep well sample 6GW6D.

Benzoic acid (21 Ig/L) and bis(2-ethylhexyl)phthalate (10 Ig/L) (detected in the sample from well 6MW5D,
located northeast (upgradient) of the DRMO site) were the only SVOCs detected during the Phase I RI.
Several phthalate esters, benzoic acid, and 1,4-dichlorobenzene were detected in groundwater samples
during Round 1 of the Phase II RI; each was detected in only one sample at a concentration of 5 Ig/L or
less. Two PAHs were also detected, each at 1 Ig/L, in the sample from deep well 6MW2D, located near the
northwest corner of Building 355. Bis(2-ethylhexyl)phthalate and phenol (0.7 Ig/L and 3 Ig/L,
respectively, in sample 6GW6D) were the only semivolatiles detected in Round 2 Phase II RI samples. No
pesticides or PCBs were detected in any of the groundwater samples collected from the DRMO.

Maximum concentrations of most metals detected during the Phase I RI were found in the sample from
shallow well 6MW4S,  located in the center of the scrap yard. Since this well was later abandoned, no
further data were available for well 6MW4S. Maximum concentrations of a majority of metals detected
during the Phase II RI were found in samples from wells 6MW2S and 6MW2D, located near the northwest
-------
corner of Building 355. Concentrations of metals were generally higher in deep wells than in shallow
wells. Notable concentrations of arsenic  (maximum of 21 Ig/L in 6GW2D) ,  lead  (maximum of 52.7 Ig/L in
6GW2S) ,  and manganese  (maximum of 1,440 Ig/L in 6GW2D)  were detected in groundwater samples.

Based on the levels of uncertainty reported with results  (i.e. uncertainty levels are greater than
results)  for gross alpha in all samples for which gross alpha was analyzed, and for gross beta in samples
6MW2S and 6MW3S, gross alpha and gross beta were considered as not detected in these samples. With this
in mind,  gross beta was detected in shallow well samples at concentrations ranging from 6.3 pCi/L to 180
pCi/L and in the deep well sample 6MW5D at 3.1 pCi/L. Complete gamma spectrum analysis was performed only
for samples from well 6MW1S collected during Rounds 1 and 2 of the Phase II RI.  Only naturally occurring
potassium-40 (140 pCi/L)  was detected in the Round 2 Phase II RI sample from this well.
-------
                                                TABIiE 5-1

                                    SUMMARY OF SOIL ANALYTICAL RESULTS
                                    DRMO, NSB-NLON GROTON, CONNECTICUT
                                                PAGE 1 OF 5
      Analyte
   Surface Soils (<2 Feet)  (1)
Frequency  Concentration  Location of
   of          Range        Maximum
Detection                  Detection
    Subsurface Soils  (>2 Feet)  (2)
Frequency   Concentration   Location of
   of          Ranqe          Maximum
Detection                    Detection
VOLATILE ORGANICS  (uq/kq)
1,1,2,2-Tetrachloroethane
1,1, 2-Trichloroethane
1,1 -Dichloroethane
1,1 -Dichloroethene
1, 2-Dichloroethane
1,2-Dichloroethene  (total)
2-Butanone
2-Hexanone
4-Methyl-2-pentanone
Acetone
Benzene
Carbon disulfide
Chloroethane
Chloroform
Ethylbenzene
Methylene chloride
Styrene
Tetrachloroet
Toluene
Trichloroethene
Vinyl chloride
Xylenes, total
SEMIVOLATILE ORGANICS  (uq/kq)
1,2, 4-Trichlorobenzene
1, 3-Dichlorobenzene
1/56
0/56
3/56
0/56
2/56
0/14
7/56
1/56
1/56
30/56
2/56
4/56
1/56
0/56
3/56
39/56
4/56
12/56
15/56
26/56
1/56
10/56
2/56
1/56
1.78
-
1.38-6.25

1.25-6.68
-
2.35-14.4
3.03
1.21
1.87-1630
1.13-6.41
1-5.37
1.55
-
1.22-9.07
2-427
1.28-2.59
1-14.7
1-12.2
1-93.1
1.66
0.992-29.7
4820-4940
1060
DRMO- 3 5
ND(3)
DRMO- 3 5
ND
DRMO- 40
ND
DRMO- 40
DRMO- 4 2
DRMO- 4 2
DRMO- 7 2
DRMO- 40
DRMO- 60
DRMO- 3 5
ND
DRMO- 4 5
DRMO- 7 5
DRMO- 3 5
DRMO- 7 4
DRMO- 3 6
DRMO- 4 4
DRMO- 3 5
DRMO- 4 5
DRMO- 63
DRMO- 3 5
1/17
1/17
0/17
1/17
2/17
2/17
0/17
0/17
1/17
2/17
1/17
3/17
0/17
1/17
1/17
2/17
0/17
4/17
3/17
6/17
1/17
2/17
0/16
0/16
                                                          6400
                                                           590

                                                            13
                                                         79-1900
                                                         2-16000
                                                          5100
                                                         78-350
                                                            7
                                                          2-48

                                                            14
                                                            44
                                                          17-41

                                                          5-210
                                                           1-43
                                                          1-7100
                                                           1300
                                                         340-5400
                                6TB4
                                6TB4
                                 ND
                                6TB4
                                6TB4
                                6TB4
                                 ND
                                 ND
                                6TB17
                                6TB4
                                6TB4
                                6TB4
                                 ND
                                6TB4
                                6TB4
                                6TB16
                                 ND
                                6TB4
                                6TB4
                                6TB4
                                6TB4
                                6TB17

                                 ND
                                 ND
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                                                         TABLE 5-1

                                             SUMMARY OF SOIL ANALYTICAL RESULTS
                                             DRMO, NSB-NLON GROTON CONNECTICUT
                                                        PAGE 2 OF 5
        Analyte
2-Methylnaphthalene
4-Methylphenol
Acenaphthene
Acenaphthylene
Anthracene
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)flouranthene
Benzo(g,h,i)perylene
Benzo(k)fluoranthene
Benzole acid
Bis(2-ethylhexyl)phthalate
Butyl benzyl phthalate
Carbazole
Chrysene
Dibenzo(a,h)anthracene
Dibenzofuran
Fluoranthene
Fluorene
Indeno(1,2,3-cd)pyrene
Naphthalene
Phenanthrene
Pyrene
PESTICIDES/PCBs(ug/kg)
4,4' -DDD
4,4'-DDE
Surface Soils (<2Feet) (1)
Freguency
of
Detection
8/56
1/56
6/56
11/56
30/56
36/56
31/56
36/56
22/56
28/56
2/9
37/56
1/56
9/47
37/56
1/56
6/56
42/56
9/56
22/56
6/56
34/56
44/56
3/56
3/56
Concentration
Range

48.7-8360
209
286-13700
286-13700
39-29300
100-43700
188-40600
150-786000
62.4-11000
47-19400
9300-12000
179-12500
423
46-14200
93-47100
1160
82-14300
66-95100
214-19200
60.3-9290
228-23700
55-96900
140-174000
9.3-227
10.5-35.9
Location of
Maximum
Detection
DRMO- 67
DRMO- 5 4
DRMO- 4 5
DRMO- 4 5
DRMO- 4 5
DRMO- 4 5
DRMO- 4 5
DRMO- 4 5
DRMO- 4 3
DRMO- 4 3
6SS3
DRMO- 4 5
DRMO- 5 2
DRMO- 4 5
DRMO- 4 5
DRMO- 3 7
DRMO- 4 5
DRMO- 4 5
DRMO- 4 5
DRMO- 4 3
DRMO- 4 5
DRMO- 4 5
DRMO- 4 5
DRMO- 7 4
DRMO- 7 4
Subsurface Soils (>2Feet) (2)
Freguency
of
Detection
4/16
1/16
3/16
1/16
5/16
9/16
6/16
10/16
4/15
7/15
2/10
2/16
0/16
1/8
11/16
1/15
1/16
11/16
3/16
4/15
2/16
9/16
12/16
0/17
1/17
Concentration
Range

42-44000
790
49-52000
89
37-41000
72-5000
74-31000
24-39000
370-9400
20-25000
32-220
120-7700
-
26000
100-4300
130
46000
36-100000
66-70000
26-9800
6500-87000
79-160000
47-89000
-
4.1
Location of
Maximum
Detection
6TB17
6TB4
6TB4
6MW2
6TB17
6TB17
6TB17
6TB17
6TB17
6TB17
6MW7S
6MW4
ND
6TB17
6TB17
6MW2
6TB17
6TB17
6TB17
6TB17
6TB17
6TB17
6TB17
ND
6TB9
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                                                        TABIiE 5-1

                                              SUMMARY OF SOIL ANALYTICAL RESULTS
                                              DRMO, NSB-NLON GROTON, CONNECTICUT
                                                          PAGE 3 OF 5
Analyte
4,4'-DDT
Aroclor-1254
Aroclor-1260
Delta-BHC
Dieldrin
Endosulfan II
Endosulfan
Endrin
Endrin aldehyde
Endrin ketone
Gamma-Chlordane
Heptachlor
DIOXINS(ug/kg)
1,2,3,4,6,7,8-HpCDD
OCDD
INORGANICS (mg/kg)
Aluminum
Antimony
Arsenic
Barium
Beryllium
Boron
Cadmium
Calcium
Chromium
Cobalt
Surface Soils (<2Feet) (1)
Freguency
of
Detection
7/56
36/56
33/56
1/56
1/56
2/56
2/56
2/56
4/47
3/56
2/56
5/56
-
-
56/56
35/45
55/56
56/56
56/56
1/5
54/56
56/56
56/56
54/56
Concentration
Range

1.42-63.4
75-22400
120-29100
5.09
4.68
2.24-25.4
28.0-37.9
10.6-12.5
2.56-6.06
3.21-31.9
2.77-20.4
0.96-20.7
-
-
2430-18900
0.0249-134
0.31-164
17.9-934
0.119-24.9
2.9
0.175-126
500-16300
4.42-1210
1.69-179
Location of
Maximum
Detection
DRMO- 7 4
DRMO- 7 2
DRMO- 3 5
DRMO- 7 7
DRMO- 7 7
DRMO- 7 4
DRMO- 60
DRMO- 7 7
DRMO- 7 4
DRMO- 7 7
DRMO- 7 4
DRMO- 7 4
NA(4)
NA
DRMO- 4 6
DRMO- 63
DRMO- 7 5
DRMO- 40
DRMO- 3 6
6TB11
DRMO- 40
DRMO- 4 8
DRMO- 63
DRMO- 4 8
Subsurface Soils (>2Feet) (2)
Freguency
Of
Detection
0/17
3/17
6/17
0/17
0/17
0/17
0/17
1/17
2/9
0/17
1/17
0/17
1/1
1/1
17/17
3/7
17/17
17/17
14/17
4/9
12/17
17/17
15/17
16/17
Concentration
Range

-
72-440
110-12000
-
-
-
-
4.4
5.6-5.8
-
2.5
-
0.67
3.07
4880-12100
4.1-7
1.1-7.5
28-212
0.22-16.8
15.6-96.2
0.45-6.4
981-21400
6.2-139
3.5-130
Location of
Maximum
Detection
ND
6TB20
6TB2
ND
ND
ND
ND
6MW2D
6TB9
ND
6TB20
NO
6TB20
6TB20
6TB16
6MW3D
6MW1
6TB17
6TB17
6TB17
6MW4
6TB17
6MW4
6TB17
-------
                                                               TABIiE 5-1

                                                   SUMMARY OF SOIL ANALYTICAL RESULTS
                                                   DRMO,  NSB-NLON GROTON, CONNECTICUT
                                                               PAGE 4 OF 5
    Analyte
Copper
Cyanide
Iron
Lead
Magnesium
Manganese
Mercury
Nickel
Potassium
Selenium
Silver
Sodium
Thallium
Vanadium
Zinc
TCLP  (mg/L)
Barium  (100.0)
Cadmium  (1.0)
Chromium  (5.0)
Lead  (5.0)
Mercury  (0-2)
Selenium  (1.0)
Silver  (5.0)
1,2-Dichloroethane  (0.5) (6)
Surface Soils (<2 Feet) (1)
Freguency
of
Detection
56/56
27/56
56/56
56/56
56/56
56/56
55/56
56/56
56/56
17/56
33/56
53/56
15/56
56/56
56/56
10/10
6/10
6/10
6/10
1/10
1/10
5/10
0/1
Concent r at ionl
Range

6.37-8730
0.0264-7.68
3590-103000
2.9-5980
1080-7190
56.7-1260
0.0033-20.7
608-6520
608-6520
0.112-0.773
0.021-24.3
41.2-4220
0.0145-0.64
6.26-368
12.5-28300
0.18-1.4
0.011-0.25
0.008-0.11
0.11 -6.2
0.0077
0.1
0.0082-0.012
-
Location of
Maximum
Detection
DRMO- 4 9
DRMO- 6 9
DRMO- 4 8
DRMO- 7 7
6SS3
DRMO- 40
DRMO- 4 6
DRMO- 4 8
6SS3
DRMO- 40
DRMO- 63
DRMO- 7 8
6TB23
DRMO- 5 2
6TI32
6MW4
6MW4
6TB2
6SS3
6MW2
6MW5S
6TB1
ND
Subsurface Soils (>2
Freguency
of
Detection
17/17
1/14
17/17
17/17
17/17
17/17
9/15
17/17
17/17
2/17
0/17
16/17
0/17
17/17
17/17
9/9
3/9
4/9
3/9
0/9
1/9
2/9
1/1
Concentration
Range

10.6-4980
0.15
6480-65800
2.3-2140
1820-6670
126-673
0.12-0.78
6.5-374
1050-6280
1-5.3
-
117-5860
-
9-63.8
25.6-14900
0.073-1.3
0.019-0.087
0.0077-0.11
0.2-0.87
-
0.1
0.01-0.029
0.028
Feet) (2)
Location of
Maximum
Detection
6TB17
6TB20
6TB17
6TB17
6TB16
6TB17
6TB20
6TB17
6MW7S
6TB17
ND
6TB4
ND
6MW4
6TB17
6MW4
6MW4
6MW5S
6MW4
ND
6MW1
6MW5S
6TB20
-------
                                                                       TABIiE 5-1

                                                            SUMMARY OF SOIL ANALYTICAL RESULTS
                                                            DRMO,  NSB-NLON GROTON,  CONNECTICUT
                                                                      PAGE 5 OF 5
        Analyte
MISCELLANEOUS PARAMETERS
Ash  (%)
Cation ex. capacity  (meq/lOOg
PH
Specific gravity  (g/cm3)
Total organic carbon  (mg/kg)
        Surface Soils  (<2 Feet)  (1)
Frequency    Concentration    Location of
    of           Range          Maximum
Detection                      Detection
                                  NA
                                  NA
                                  NA
                                  NA
                                  NA
        Subsurface Soils  (>2 Feet)  (2)
Frequency   Concentration        Location of
    of          Range               Maximum
Detection                          Detection
   2/2
   2/2
   2/2
   2/2
   3/3
81.4-85.8
 9.3-21
7.69-7.76
 2.1-2.2
 600-8400
6TB16
6TB16
6TB20
6TB20
6TB20
NOTES:
1 Includes samples 6MW1  (0-2),  6MW2  (0-2),6TI38  (0-2) (field duplicate of 6MW2 (0-2) ) , 6MW4 (0-2) , 6MW5S (0-2) , 6SS3, 6
  duplicate of 6SS3)6SS4,6TBI(0-2) .6TB2(0-2) , 6TB3(0-2) , 6TB8(0-1),6TB11(-02),6TB12(0-2),6TB20 (0-1),6TB23 (0-1) ,
  16144-32,16144-35 through-55  16144-41  is  a field  duplicate of 16144-40),16144-56,16144-DUP (field duplicate of 16144-60,
  through-82) 17144-64 is a field  duplicate of 16144-63,  16144-82  is  a field duplicate of 16144-74).  Maximum concentrations are
  used for the evaluation of field duplicates and are  counted as  one  sample.  Excavated samples  are not included in the summary.
  Surface soil samples were collected during the Phase I  RI (September to November 1990) ,  the FFS (October 1993) ,  and the
  Time Critical Removal Action  (November to December 1994).
2 Includes samples 6MWI(4-6),6MW6(4-6)(field duplicate of 6MW1(4-6)),6MW2(2-4),6MW2D-0406,6MW3D-0406,6M
  6MW5S(8-10),6MW7S-0709,6TB1(2-4),6TB2(2-4),6TB3(6-8) ,6TB4(6-8) ,6TB8(4-6) ,6TB9(2-4),6TB10(4-6) , 6TB16(16-18) ,
  6TB16(8-10) , 6TB17(10-12),6TB37(10-12) (field duplicate of 6TB17(10-12)),  and 6TB20(4-6).  Maximum concentrations are used
  for evaluation of field duplicates and are counted as one sample. Excavated samples are not included in the summary.
  Subsurface soil samples were  collected during the Phase I RI (September to October 1990),  FFS (October 1993),  and Phase
3 Not Detected.
4 Not Analyzed.
5 Values in parentheses represent  Federal Toxicity  Characteristic  Regulatory Level (58 FR 46049)
6 NA - Not Applicable.
-------
                                                                TABIiE 5-2

                                     SUMMARY  OF  PHASE  I  GROUNDTCATER ANALYTICAL RESULTS (UNFILTERED)
                                                  DRMO, NSB-NLON GROTON, CONNECTICUT
      Analyte
VOLATILE ORGANICS  (ug/L)

1,1-Dichloroethane
1,2-Dichloroethene  (total)
Trichloroethene
SEMIVOLATILE ORGANICS  (ug/L)
Benzole acid
Bis (2-ethylhexyl)phthalate
INORGANICS  (ug/L)
Arsenic
Barium
Cadmium
Calcium
Copper
Iron
Lead
Magnesium
Manganese
Mercury
Nickel
Potassium
Selenium
Sodium
Zinc
Shallow Wells (1)
Frequency
of
Detection
1/5
3/5
3/5
0/5
0/5
3/5
4/5
3/5
5/5
5/5
5/5
1/5
5/5
5/5
5/5
2/5
5/5
4/5
5/5
5/5
Concentration
Range

2
1-2
1-8
-
-
3.35-18.6
27.9-86.2
2.1-4
6970-1700001
8-355
102-4880
3.4
1270-396000
20.1-1000
-
11.7-23.2
3230-123000
9.9-23.5
7470-3350000
11.25-356
Location of
Maximum
Detection
6MW4S
6MW4S
6MW4S
ND
ND
6MW4S
6MW4S
6MW4S
6MW4S
6MW4S
6MW5S
6MW5S
6MW4S
6MW5S
ND
6MW4S
6MW4S
6MW4S
6MW4S
6MW4S
Frequency
of
Detection
0/1
0/1
0/1
1/1
1/1
0/1
1/1
0/1
1/1
1/1
0/1
0/1
1/1
1/1
1/1
0/1
1/1
0/1
1/1
1/1
Deep Wells (2)
Concentration
Range

_
-
-
21
10
_
33.9
-
10600
9.4
-
-
1000
84.5
0.3
-
3460
-
14600
13.8

Location of
Maximum
Detection
ND(3)
ND
ND
6MW5D
6MW5D
ND
6MW5D
ND
6MW5D
6MW5D
ND
ND
6MW5D
6MW5D
6MW5D
ND
6MW5D
ND
6MW5D
6MW5D
NOTES:
1 Includes samples 6MW1S,6MW2S,6MW3S,6MW6S(field  duplicate  of 6MW3S),6MW4S,and 6MW5S.
  Duplicate sample results are  averaged  and  counted as  one  sample.
2 Includes sample 6MW5D.
3 ND - Not Detected
-------
                                                                  TABLE 5-3

                                      SUMMARY OF ROUND I/PHASE  II GROUNDWATER ANALYTICAL RESULTS
                                                   DRMO NSB-NLON GROTON,  CONNECTICUT
                                                              PAGE 1  OF 2
                                                           Shallow Wells  (1)
                                                                                         Filtered
                                                                                       Concentration
                                                                                          Range
                                                                          Location of
                                                                            Maximum
                                                                          Detection
VOLATILE ORGANICS
1,1-Dichloroethane
1,2-Dichloroetlmm  (total)
Carbon disulfide
Trichtoroeth
SEMIVOLATILE ORGANICS
1,4-Dichlorobenzene
Benzo(g.h,i)perylene
Benzole acid
Bis(2-ethylhexyl)phthalate
Di-n-butyl phthalate
Di-n-octyl phthalate
Diethyl phthalate
Dimethyl phthalate
Indeno(1,2, 3-cd)pyrene
INORGANICS
Aluminum
Arsenic
Barium
Boron
Cadmium
Calcium
Chromiun
Cobalt
Copper
Iron
Lead
Magnesium
Manganese
Mecury
Nickel
Potassium
Sodium
1/5
1/5
1/5
0/5
1/5
1/5
           27. 05-2090
               2-4 .3
            10.3-75.4
           474.5-1560
               2.6
           24700-140000
               6.3
6MW2S
6MW2S
6MW6S
6MW2S
6MW6S
6MW2S
6MW2S
 ND
6MW2S
6MW2S
6MW2S
6MW2S
6MW7S
6MW2S
 ND
6MW2S
6MW2S
   ND
 6MW2S
 6MW6S
 6MW2S
  ND
 6MW2S
  ND
  ND
6MWIS
6MW3S
  ND
6MW2S
6MW7S
6MW1S
6MW3S
6MW2S
6MW2S
23400-274000
    47.6
   4.6-14.3
    63.1
  6880-39400
   45.6-50.9
  11000-729000
    852-1340
6MW2D
6MW2D
6MW3D
6MW2D
 ND
6MW3D
6MW2D
6MW2D
6MW2D
6MW2D
6MW2D
6MW3D
6MW2D
 ND
6MW2D
6MW2D
6MW3D
 ND
 ND
6MW3D
6MW2D
 ND
6MW3D
6MW2D
 ND
6MW3D
6MW3D
6MW3D
6MW3D
6MW3D
 ND
6MW3D
6MW3D
6MW3D
-------
                                                                                         TABLE 5-3

                                                                 SUMMARY OF ROUND  I/PHASE II GROUNDWATER ANALYTICAL  RESULTS
                                                                             DRMO  NSB-NLON GROTON, CONNECTICUT
                                                                                         PAGE 2 OF 2
                                                                                                                                                              Deep Wells  (2)
Vanadium
Zinc
MISCELLANEOUS  PARAMETERS
BOD  (mg/L)  (5)
COD  (mg/L)  (6)
Hardness  as  CaCO  3 (ing/
Total organic  carbon (ing/  1/1
Total phosphorus  (mg/L)   1/1
TSS  (mg/L)  (7)            1/1
Oil  & grease  (ing/ L)       1/1
Location of
   Maximum
Detection
 6MW2S
 6MW2S
Freguency
    of
Detection
   2/5
   1/5
 Location of
   Maximum
Detection
  6MW3S
  6MW1S
   Location of
      Maximum
  Detection
6MW2D
  6MW2D
Location of
   Maximum
Detection
   ND
    6MW3D
1 Includes samples  6GW1S,6GW2S, 6GW3S, 6GW6S,  6GW7S,
2 Includes samples  6GW2D,  6GW3D, and 6GW6D
3 Not Analyzed.
4 Not Detected.
5 BOD - Biochemical  Oxygen Demand.
6 COD - Chemical  Oxygen Demand.
7 TSS - Total  Suspended Solids.
-------
                                                                                TABLE 5-4

                                                        SUMMARY  OF ROUND 2/PHASE II GROUNDWATER ANALYTICAL RESULTS
                                                                    DRMO, NSB-NLON GROTON, CONNECTICUT
                                                                             PAGE 1 OF 2
                                                                         Frequency
VOLATILE ORGANICS  (ug/L)
1,2-Dichloroethene(total)
Trichloroethene
Vinyl chloride
SEMIVOLATILE ORGANICS  (ug/L)
Bis (2-Ethylhexyl)phthlate
phenol
INORGANICS  (ug/L)
Aluminum
Antimony
Arsenic
Barium
Beryllium
Boron
Calcium
Colbalt
Copper
Iron
Magnesium
Manganese
Nickel
Potassium
Sodium
Vanadium
Zinc
MISCELLANOUS PARAMETERS
Ammonia,as nitrogen(m
COD  (mg/L)  (5)
Hardness as CaCO 3(mg/
Total organic carbon  (mg/
                                             Range
                                                         Maximum
                                                         Detection
ND
ND
                                             Location of
                                              Maximum
                                             Detection
NA
NA
6MW2S
6MW3S
6MW2S
6MW7S
ND
6MW2S
6MW2S
6MW6D
6MW2D
6MW7S
6MW1S
6MW7S
ND
6MW2S
6MW2S
6MW3S
6MW1S
1/3 0.7
1/3 3
2/3 88.85-806
0/2
2/3 2.65-21
3/3 28.6-242
I/ 1
3/ 87.4-2340
3/ 15150-268000
I/ 11.6
I/ 9.7
3/3 5690-44550
3/3 8490-949000
3/3 649-1440
1/3 24.1
3/3 14500-313000
3/3 09500-756000
1/2 5.45
2/3 4.2-105
6MW2D
6MW6D
6MW2D
ND
6MW2D
6MW3D
6MW3D
6MW2D
6MW3D
6MW6D
6MW2D
6MW6D
6MW3D
6MW2D
6MW6D
6MW2D
6MW3D
6MW6D
6MW6D
-
-
O/
o/
I/
3/
O/
3/
3/
I/
2/
3/3

3/3
1/3
3/3
3/3
1/2
0/3
  Filtered
Concentration  Location  of
    Range        Maximum
                Detection
                  NA
                  NA
-------
                                                                                                       TABLE 5-4

                                                                              SUMMARY OF ROUND 2/PHASE II GROUNDWATER ANALYTICAL RESULTS
                                                                                          DRMO, NSB-NLON GROTON, CONNECTICUT
                                                                                                      PAGE 2 OF 2

                                                                           Shallow Wells (1)
                                               Unfiltered                                                  Filtered                                               Unfiltered                      Filtered

Analyte                     Frequency         Concentration        Location  of         Frequency         Concentration        Location  of      Frequency      Concentration         Location of       Frequency     Concentration        Location of
                                                                     Maximum              of                Ranqe             Maximum           of             Ranqe               Maximum            of             Ranqe              Maximum
                                                                    Detection         Detection                               Detection      Detection                             Detection        Detection
Total phosphorus  (mq/L)        1/1                   1                  6MW3S                -                                      NA                                                    NA                                                   NA

TSS  (mq/L)(5)                  1/1                   1

Oil  & qrease  (uq/L)            1/1                  500


NOTES:
1 Includes samples  6GW1S-2,  6GW2S-2,  6GW3S-2,  6GW6S-2, 6GW7S-2, and 6GW8S-2.
2 Includes samples  6GW2D-2,  6GW3D-2,  SGW6D-2,  and 6GW6D-D-2  (field duplicate of  6GW6D-2). Duplicate sample results are averaqed  and  counted as one sample.
3 Not Analyzed.
4 Not Detected.
5 COD - Chemical  Oxyqen  Demand.
6 TSS - Total Suspended  Solids.
-------
5.6.3
           DRMO Surface Water
A surface water sample was collected in the Thames River. No organic chemicals were detected in the
surface water sample. Several metals were detected including aluminum, calcium, copper, iron, magnesium,
manganese, potassium, selenium, sodium, and zinc. Based on the levels of uncertainty reported with the
laboratory results  (i.e., uncertainty levels are greater than results), gross alpha and gross beta were
considered as not detected in this sample.

                              6.0 SUMMARY OF SITE RISKS

A baseline risk assessment provides the basis for taking action and indicates the exposure pathways that
need to be addressed by the remedial action. It serves as the baseline indicating what risks could exist
if no action were taken at the site. This section of the Interim ROD reports the results of the baseline
risk assessment conducted for the site.
A human health and ecological risk assessment was performed to estimate the probability and magnitude of
potential adverse human health and environmental effects from exposure to contaminants in various media
at DRMO. The human health risk assessment procedure followed the most recent guidance from the U.S. EPA
(U.S. EPA, December 1989 and March 25, 1991) and regional guidance  (U.S. EPA Region I, June 1989, August
1994, and August 1995). The ecological risk assessment used numerical criteria from regulatory-based
standards and guidance provided by various government agencies in the U.S. and Canada against which
contaminant concentrations were compared to arrive at guantitative risk levels. The ecological risk
assessment also use U.S. EPA-approved methodology for estimating potential risks to terrestrial receptors
via food-chain modeling.

The risk assessment followed a four step process: (1) conceptual model development and contaminant
identification, which identified those chemicals which, given the specifics of the site, were of
significant concern;  (2) exposure assessment, which identified actual or potential exposure pathways,
characterized the potentially exposed populations, and determined the extent of possible exposure;  (3)
toxicity assessment, which evaluated the type and magnitude of adverse health and ecological effects due
to exposure to the contaminants; and  (4)  risk characterization, which integrated the three earlier steps
to summarize the potential and actual non-carcinogenic  (toxic) and carcinogenic  (cancer causing) risks
posed by contaminants at the site, and uncertainties inherent in the risk assessment process.
6.1
         CONTAMINANT IDENTIFICATION
The chemicals evaluated for the DRMO are as follows:
Non-carcinogenic PAHs
Other SVOCs
(12 compounds: primarily
phthalates and phenols
BTEX Compounds
(All BTEX compounds)
Carcinogenic PAHs
Pesticides
7 compounds and derivatives)

Chlorinated VOCs
(13 compounds)
PCBS
(Aroclors 1260,1254 and
hexachlorobiphenyl)
Inorganics
(25 constituents)

Other VOCs
(9 compounds)
Notes:  PAHs: Polynuclear Aromatic Hydrocarbons
        PCBs: Polychlorinated Biphenyls
        BTEX: Benzene, Toluene, Ethylbenzenes, and Xylenes
        VOCs: Volatile Organic Compounds
        SVOCs: Semivolatile Organic Compounds

Concentrations of detected chemicals were compared to benchmark concentrations for human health concern,
especially the U.S. EPA Region III risk-based concentrations  (RBCs). Those analytes with concentrations
exceeding the benchmarks were selected as chemicals of concern  (COCs).  A similar process was carried out
for ecological receptors using published ecological benchmarks.

Details of the COG selection process and exposure point concentrations are presented in the Phase II RI
(B&R Environmental, March 1997).

COCs were selected by comparing the maximum concentrations to Region III residential soil screening
levels. The list of potential COCs for soil at the DRMO consist of:

       •      VOCs: 1,1,2,2-tetrachloroethane and vinyl chloride.
-------
       •      PAHs:  benzo(a)anthracene,  benzo(b)fluoranthene, benzo(k)fluoranthene, benzo(a)pyrene,
              dibenz(a,h)anthracene,  and indeno(1,2,3-cd)pyrene.

              PCBs:  Aroclors-1254 and -1260 and hexachlorobiphenyl

              Dioxins:  1,2,3,4,5,6,7,8-HpCDD and OCDD.

       •      Metals:  antimony,  arsenic, barium,  beryllium, cadmium,  chromium, lead, manganese, mercury,
              nickel,  thallium,  vanadium, and zinc.

Vinyl chloride, 1,1,2,2-tetrachloroethane, dibenz(a,h)anthracene, and dioxins were  retained as COCs  for
the "all soil"  (soil from depths of  0 to 10 feet)  category only. Dioxins were not  found at  detectable
levels in the surface soil samples.

Maximum soil detections were also compared to U.S.  EPA's Soil Screening Levels  (SSLs) for migration  to
groundwater in the Phase II RI. Maximum site concentrations  exceeded SSLs  (Generic  SSLs,  Soil  Screening
Guidance: U.S. EPA/540/R-95/128; May 1996) for antimony, arsenic, barium,  cadmium,  chromium, lead,
mercury, nickel, silver, thallium, zinc, 1,1-dichloroethane, 1,2-dichloroethene  (total),
1,1,2-trichloroethane,  1,1,2,2-tetrachloroethane,  tetrachloroethene, vinyl chloride, methylene chloride,
trichloroethene, 1, 2, 4-trichlorobenzene, benzo(a)anthracene, benzo(a)pyrene, benzo(b)fluoranthene,
carbazole, dibenzo(a,h)anthracene, indeno(1,2,3-cd)pyrene, Aroclor-1254, Aroclor-1260,
hexachlorobiphenyl,  and dieldrin. These  chemicals may migrate to groundwater and potentially impact  water
guality.

For groundwater, all data from both  shallow and deep wells were used to identify potential  COCs. The
following chemicals were retained as COCs for this  medium:

       •      Halogenated aliphatic hydrocarbons  (1,2-dichloroethene,  trichloroethene,  and vinyl
              chloride).
       •      1,4-Dichlorobenzene
              Bis(2-ethylhexyl)phthalate
       •      Indeno(1,2,3-cd)pyrene
       •      Metals (antimony,  arsenic, barium,  beryllium, boron,  cadmium, chromium, lead,  manganese,
              selenium,  and vanadium)

For screening purposes,  concentrations  of these chemicals were  compared to Federal  Maximum  Contaminant
Levels  (MCLs). This comparison showed that maximum detections of trichloroethene, vinyl chloride,
bis(2-ethylhexyl)phthalate, antimony, and lead exceeded primary MCLs. Antimony, which was not  detected in
the unfiltered samples,  was selected as  a COG in  the Phase II RI because the concentration  of  this
chemical in filtered sample 6GW3S exceeded the risk-based  screening level.

Although groundwater COCs were identified in the  Phase II RI as a concern, the human health risk
assessment did not identify any chemicals in the  groundwater as being of concern to potential  human
receptors because total risks for each  exposure scenario were within acceptable U.S. EPA  limits. Critical
to this conclusion is the fact that  the  groundwater at this  site is classified as  GB, and is therefore
not a drinking-water source. Groundwater concentrations were also compared to CTDEP's Surface Water
Protection Criteria (SWPC)  using a site-specific  dilution factor that was  considered appropriate for
discharge of the groundwater to Thames  River, and no COCs emerged from the comparison. Also, because
there is no anticipated contact between potential  ecological receptors and groundwater, no  COCs were
identified in the groundwater for ecological risks.

One site surface water sample, 6SW1. was collected  during the Phase I RI. Aluminum,  copper, iron,
manganese, selenium, zinc,  and several primary inorganic human nutrients were detected at varying
concentrations in this sample. All detections were  below the risk-based COG screening criteria for tap
water ingestion and National Ambient Water Quality  Criteria  (NAWQC). No COCs were  identified in the  Phase
II RI for surface water, indicating  that potential  exposure  to  this medium would result in  minimal risks.

6.2       EXPOSURE ASSESSMENT

Based on information obtained through site visits,  inspections, and discussions with personnel at the
DRMO or those involved in future planning for the  area, the  following potential receptors were
identified:

       •      Full-time  employees exposed to surface soil up to a depth of 2.0 feet below ground surface
              (bgs)
-------
       •      Construction workers exposed to all soil to a depth of 10 feet bgs ("all soil")  and
              groundwater
       •      Older child trespassers exposed to surface soil up to a depth of 2.0 feet bgs
       •      Future residents exposed to all soil to a depth of 10 feet bgs
       •      Terrestrial vegetation, soil invertebrates,  and terrestrial vertebrates exposed to surface
              soil

Note that the only current human receptor at this site is the full-time employee.  Another potential
current  (albeit unlikely) receptor is an older child resident: of the base who might trespass on the site
despite existing fencing and security. Currently, there are no significant ecological receptors at the
site.

Although this future land use scenario is extremely unlikely, the possibility of the DRMO site being used
for residential purposes was considered for the determination of human health risks. This was done
because the DRMO site constitutes riverfront real estate and since traditionally this kind of property
has been highly desirable for residential development such a future land use scenario cannot be
completely ruled out. Under such a residential scenario, removal of the asphalt layer  (either by
artificial forces or natural degradation) could result in significant exposure of potential ecological
receptors to surface soil.

Intake of each COG by each potential receptor  (human or ecological) was estimated by incorporating
site-specific soil concentrations into standard eguations developed by the U.S. EPA  (U.S. EPA, December
1989 and March 1991). The resulting  intakes were expressed as milligrams of analyte per kilogram of body
weight per day. The major assumptions about exposure freguency and duration are presented in the Phase II
RI Report (B&R Environmental, March  1997).

6.3     TOXICITY ASSESSMENT

The toxicity assessment examines information concerning the potential human health effects and ecological
effects from exposure to COCs. The toxicity assessment provides, for each COG, a gualitative review of
potential human health effects and ecological effect and a guantitative estimate of the relationship
between the magnitude(dose) and type of exposure and the severity and/or probability of human health
effects. The toxicological evaluation involves a critical review and interpretation of toxicity data from
epidemiological, clinical, animal, and in vitro studies, as well as structural-activity relationship
assessments. The available toxicological data base is used by the U.S. EPA to derive cancer slope factors
(CSFs) for carcinogenic effects and  Reference Doses  (RfDs) for noncarcinogenic effects. CSFs and RfDs are
published by the U.S. EPA in references listed in the Phase II RI  (B&R Environmental, March 1997). These
toxicity values are integrated with  the exposure assessment  (intake) to characterize the potential for
the occurance of adverse health effects.

The COCs for ecological receptors are selected based on the comparison between chemicals detected in the
site media and predicted body burdens in concentrations greater than regulation-based criteria  (such as
ambient water guality criteria), ecotoxicological guidance provided by agencies such as U.S. EPA. the
Ontario Ministry of the Environment  (OME). Oakridge National laboratories  (ORNL),  National Oceanic and
Atmospheric Administration (NOAA), etc. At the DRMO, all of the sources listed above were used, as guoted
in Section 3.4 of the Phase II R  (B&R Environmental, March 1997).

6.4        RISK CHARACTERIZATION

This section on risk characterization summarizes the results of the risk assessment from the Phase II RI
(B&R Environmental, March 1997). Details are provided in the Phase II RI. The first part presents a
summary of the human health risk characterization. The second part presents a summary of the ecological
risk characterization.

6.4.1	Summary of Human Health Risk Characterization

Estimated exposure  (intake) values were integrated with toxicity values  (CSFs and RfDs) through a series
of calculations, to develop Hazard Indices (His) and Incremental Cancer Risks  (ICRs) for noncarcinogenic
and carcinogenic risks, respectively. In order to determine if potentially significant risks exist for
human receptors, guantitative estimates of risk were compared to "acceptable" levels of risk. Estimated
His were compared to unity (1.0). Estimated ICRs were compared to the U.S. EPA target risk range of 1E-4
to 1E-6. According to State of Connecticut's Soil Remediation Regulations, direct exposure criteria to
potential receptors do not apply because the soil is beneath a cap or pavement and is considered to be
inaccessible, and the pollutant mobility criteria for protection of groundwater do not apply since the
soil is located below the seasonal high water table.
-------


The following paragraphs summarize the estimated cumulative risks, and Table 6-1 presents a summary of
the estimated risks. Both validated and unvalidated data were used in this risk assessment. Multiple
potential receptor groups were considered for the DRMO including an older child trespasser, construction
worker, future residents, and full-time employees. Carcinogenic risks, as guantified by lifetime
Incremental Cancer Risks (ICRs),  were compared to the U.S. EPA's target risk range of 1E-4 to 1E-6. Most
cumulative ICRs were either less than 1E-6 or within the U.S. EPA's target risk range. An exception was a
cumulative ICR of 1.4E-4 for residents under the Reasonable Maximum Exposure(RME) scenario which assumes
exposure to maximum concentrations of contaminants. In this case, potential risks are attributable to
ingestion of soil containing PAHs, PCBs, dioxins, arsenic, and beryllium, as well as dermal contact with
PCBs and inhalation of fugitive dust containing chromium. In general, exposure to soil contributes the
most to the cumulative cancer for at receptors. COCs for exposure to soil include PCBs (Aroclors), and
PAHs [especially benzo(a)pyrene]  with somewhat less risk from certain inorganic contaminants; (arsenic
and beryllium).

Noncarcinogenic risks, as guantified by Hazard Indices (His), was compared to unity  (1.0). For all
receptors considered, the cumulative His under the RME scenario exceeded 1.0. His did not exceed unity
for any receptor under,  the Central Tendency Exposure (CTE) scenario which assumes exposure to average
concentrations of contaminants.  Most risks stem from ingestion of and dermal contact with soils. The
majority of the risk is contributed by the PCBs. Most of the remaining risks are attributable to
antimony, cadmium, and,  to some extent, chromium in soil. Exposure to lead in the soil at the DRMO was
addressed in the Phase II RI using the U.S. EPA IEUBK model for lead uptake from soil. Although the
conclusion in the Phase II RI was that blood levels would be below the level of concern (Ig/dL)  for a
child receptor, higher soil concentrations (by over an order of magnitude) were detected in the
unvalidated data from the confirmation sampling of the January 1995 time-critical removal action. The
previously reported Phase II RI concentrations estimated blood lead levels of roughly half of the level
of "concern" (10 Ig/dL). However, because of the higher levels of lead reported in the confirmation
sampling data for the January 1995 time-critical removal action  (which remains unvalidated) it is
expected that the corresponding blood lead levels could be several times higher than the level of
"concern" (10 Ig/dL) , and therefore, it is now concluded that lead is a COG for the soil at the DRMO.

Table 6-2 identifies the complete list of human health COCs in surface and subsurface soils for the
potential receptors of concern.  This table presents a list of those contaminants that contributed under
the RME to either a cumulative hazard index exceeding 1.0 of a cumulative ICR exceeding 1E-4 or both. The
RME was chosen conservatively to be the potential exposure to receptors of concern for estimating
remediation goals.
-------
                                               TABIiE 6-2

                     SUMMARY OF HUMAN HEALTH COCs FOR REMEDIATION GOAL DEVELOPMENT
                                                 DRMO
                                    NSB-NLON, GROTON, CONNECTICUT

     Potential Human                                          COCS
        Receptor
                                  Noncarcinogenic           Carcinogenic Effects
                                      Effects
    Full-time Employee               Aroclors                     None  (1)
   Construction Worker          Aroclors, Cadmium,                None  (1)
                                        and
                                Hexachlorobiphenyl
  Older Child Trespasser             Aroclors                     None  (1)
   Child/Adult Resident          Aroclors, Cadmium          Benzo(a)anthracene,
                                        and                   Benzo(a)pyrene,
                                Hexachlorobyiphenyl        Benzo(b)fluoranthene,
                                                          Dibenzo(a,h)anthracene,
                                                          Indeno(1,2,3-cd)pyrene,
                                                       Hexachlorobiphenyl, Arochlors,
                                                      Dioxins, Arsenic, Beryllium and
                                                                Chromium

Note:

1   No carcinogenic COCs were identified for these potential receptors because estimated
    cumulative ICRs were within the acceptable range of 1E-06 and 1E-04.


6.4.2	Remediation Goals for Human Health Protection

Using risk values based on the analyte concentrations with validated and unvalidated data and for "all
soil" data from 0 to 10 feet bgs, remediation goals were calculated for the protection of potential human
receptors at NSB-NLON. The COCs that reguire remediation goals are those presented in Table 6-2.
Initially, all exposure pathways  (considering all receptors, media, and routes of exposure) with
Incremental Cancer Risks  (ICRs) of more than 1E-06 and/or Hazard Indices  (His) of more than 1.0 were
identified. If the risk or hazard values approached these levels, the relevant scenarios were also
included for initial consideration. For each scenario, individual chemicals which contributed at least
1E-6 to the ICR or 0.1 to the HI were selected. If the risk or hazard values approached these levels, the
contributing chemicals were also included in the remediation goal calculations. Upon further
consideration, the ICR level of 1E-4, established by U.S. EPA as representing an unacceptable risk, was
used instead to initially screen potential cancer risks for development of remediation goals. No
groundwater COCs were identified for human health protection, as discussed in Section 6.4.1.

The groundwater at this site is classified as GB guality, which implies that the groundwater is not
suitable for human consumption without treatment, and where a public water supply from another source is
available. Therefore, remediation goals were not developed for the protection human receptors from
consumption of groundwater.

Site-specific remediation goals were calculated using the following eguation:

          Exposure Concentration/Calculated Risk Value = Remediation Goal/Desired Risk Level

Solving for the Remediation Goal, the eguation becomes:

          Remediation Goal = (Exposure Concentration)  (Desired Risk Level)/Calculated Risk Value

For example, assuming that the total ICR  (ingestion and dermal routes) for an employee exposed to
Aroclors in surface soil was 1.86E-6 (B&R Environmental, March 1997) and that the soil concentration was
0.35 mg/kg, the remediation goal at the 1E-6 level would be calculated as follows:

                    Remediation Goal = (0.35 mg/kg)  (1E-6)/1.86E-6 =0.19 mg/kg

Remediation goal calculations are presented in Appendix A of the FS  (B&R Environmental,
September 1997) under Preliminary Remediation Goal calculations.
-------
The final remediation goals for soil COCs were selected by identifying chemicals which contributed at
least a 1E-06 risk to an overall ICR of more than 1E-4 and/or a major portion of an overall HI greater
than 1.0. Typically the COCs for non-carcinogenic risk contributed an HQ approaching or greater than 1.0.
The following remediation goals were developed for the COCs identified during the human health risk
assessment:
Soil remediation goals For Full-Time Employee:

              Aroclors (1254  and 1260)

Soil remediation goals For Construction Worker:

              Aroclors (1254  and 1260)

       •       Cadmium

Soil remediation goals For Older Child Trespasser:

              Aroclors (1254  and 1260)

Soil remediation goals For Future Resident:

       •       Benzo(a)anthracene

       •       Benzo(a)pyrene

       •       Benzo(b)fluoranthene

       •       Dibenzo(a,h)anthracene

       •       Indeno(1,2,3-cd)pyrene

              Aroclors(1254  and 1260)

       •       Hexachlorobiphenyl

              Dioxins (HpCDD  & OCDD)

       •       Arsenic

       •       Beryllium

       •       Cadmium

       •       Chromium
10 mg/kg



6 mg/kg

84 mg/kg



10 mg/kg



2 mg/kg

0.2 mg/kg

2 mg/kg

0.2 mg/kg

2 mg/kg

0.35 mg/kg

0.35 mg/kg

0.00059 mg/kg

0.96 mg/kg

0.35 mg/kg

67 mg/kg

11 mg/kg
-------
6.4.3	Summary of Ecological Risk Assessment

An ecological risk assessment was performed for the DRMO during the Phase II RI following the procedures
described in Section 3.4 of the Phase II RI report  (B&R Environmental, March 1997). The ecological risk
assessment for the DRMO began with an evaluation of contaminants in soils. Inorganic COCs were identified
as those chemicals with average concentrations exceeding background concentrations and published
benchmark values protective of terrestrial vegetation, soil invertebrates, the short-tailed shrew, and
the red-tailed hawk. Organic COCs were identified as those chemicals where concentrations exceeded
benchmark values. Potential risks to terrestrial vegetation, soil invertebrates, and terrestrial
vertebrates were then evaluated. For each COG, the potential risks were estimated by dividing the soil
concentration (maximums for RME and averages for CTE) by the benchmark values to arrive at Hazard
Quotients (HQs). The HQs determined for this site are summarized in Tables 6-3 through 6-6. Chemicals
associated with the DRMO were considered to represent a risk to receptors if the HQs exceeded 1.0. Total
risks to terrestrial receptors are expressed in terms of Hazard Indices (His) , which are a sum of
chemical-specific HQs for each potential pathway of exposure. These risks to potential terrestrial
receptors are summarized in Tables 6-5 and 6-6. Results of these comparisons indicate that terrestrial
receptors are potentially at risk under both RME and CTE conditions.

The ecological risk assessment concluded that exposure to surface soils could adversely impact
terrestrial ecological receptors, using highly conservative estimates. However, the DRMO does not provide
a suitable ecological habitat (due to the presence of paving, buildings, cap, etc.), and actual risks to
ecological receptors are likely to be much less than those calculated for this area. It is unlikely that
ecological receptors will utilize this area, essentially eliminating the possibility that these receptors
will be exposed to these chemicals. Furthermore, the presence of the cap effectively eliminates direct
contact with soil at the site. When the current site conditions are factored into this evaluation, it is
concluded that soil at the DRMO represents little potential risk to ecological receptors, If the cap is
destroyed in the future due to artificial or natural forces, then there would be a potential risk to
ecological receptors.

Sediment toxicity tests conducted during the Phase II RI, indicated that conditions at a sediment
sampling point collected near the DRMO  (EC-T3504) may adversely impact sensitive benthic
macroinvertebrates. It is not known if contaminant migration from the DRMO is the cause of these
conditions.  The major ecological concern is potential future transport of contaminated soils or
groundwater to the Thames River.

6.4.4	Remediation Goals for Protection of Ecological Receptors

Under the current land use the ecological receptor exposure risks for the DRMO are low. However, under a
future land use scenario, removal of the asphalt cap could be anticipated allowing ecological receptors
to be exposed to surface soil. Therefore, remediation goals for soil at the DRMO were derived from values
presented in either the Area A Downstream/OBDA FS (B&R Environmental, July 1997) or the ORNL database
(ORNL, 1996) of toxicological benchmarks for ecological risk assessment. The value for DDT/DDD was
derived using a risk-based approach to calculate a site-specific value which is protective of terrestrial
receptors such as the short-tailed shrew (B&R Environmental, July 1997). The remediation goal for zinc
was based on a screening value determined to be protective of terrestrial plants  (ORNL, 1996; Will and
Suter, 1994). All other soil remediation goals presented were derived by ORNL and were chosen by
comparing the ORNL benchmarks for plants, microorganisms, and earthworms in soils to calculate
remediation goals for wildlife.  The most conservative value was selected as the soil remediation goal
(Efroymson et al., 1996). Remediation goals were only developed for COCs determined to contribute the
major portion of the cumulative risk to the ecological receptors, as listed below:

       •      Aluminum               50 mg/kg (Efroymson,  et al.,  1996 (plant))
       •      Antimony               5 mg/kg (Efroymson,  et al.,  1996 (plant))
       •      Boron                  0.5 mg/kg (Efroymson,  et al.,  1996 (plant))
       •      Cadmium                3 mg/kg (Efroymson,  et al. ,  1996 (plant))
       •      Chromium               0.4 mg/kg (Efroymson,  et al.,  1996 (earthworm))
              Cobalt                 20 mg/kg (Efroymson,  et al.,  1996 (plant))
       •      Copper                 50 mg/kg (Efroymson,  et al.,  1996 (earthworm))
       •      Lead                   50 mg/kg (Efroymson,  et al.,  1996 (plant)
       •      Mercury                0.128  mg/kg (Efroymsog,  et al.,  1996  (shrew))
       •      Silver                 2 mg/kg (Efroymson,  et al.,  1996 (plant))
              Thallium               1 mg/kg (Efroymson,et al.,  1996 (plant))
       •      Vanadium               2 mg/kg (Efroymson,  et al.,  1996 (plant))
              Zinc                   50 mg/kg (Will  and Suter,  1994  (plant))
              DDTR                   5 mg/kg (B&R Environmental,  July 1997 (shrew))
-------
6.4.5	Remediation Goals for Protection of Surface Water

Contaminants present in the groundwater could migrate to the Thames River during tidally influenced
fluctuation of water table elevations. Contaminants present in the vadose zone soil could also migrate
via infiltration into the groundwater and periodic flooding (albeit at minimal levels because of the
existing asphalt cap on site) ,  followed by migration to the Thames River. Surface water protection
criteria (SWPC) for contaminant levels in groundwater were developed using State of Connecticut Surface
Water Criteria and a site-specific dilution factor that was estimated to be 100. Contaminant
concentrations in the groundwater did not exceed these SWPCs;  therefore, remediation goals were not
developed for groundwater.

Remediation goals were developed for contaminants present in the soil that could potentially leach into
the groundwater and enter the Thames River. An allowable soil value was calculated to be protective of
the surface water by taking a ratio of the maximum SWPC divided by the Safe Drinking Water Act Maximum
Contaminant Level (MCL)  or a Health Base Limit (HBL)  for SSL development and multiplying by the Federal
pollutant mobility criteria (U.S. EPA, May 1996)  adjusted by a site-specific dilution factor of 10. COCs
for this scenario were identified when maximum concentrations exceeded these allowable values. The
following are the allowable soil values (remediation goals) that were developed for the COCs identified
in the soil to be protective of the surface water from contaminants leaching from the soil:

       •      Benzoic Acid          8.4 mg/kg
       •      Benzo(a)anthracene    27 mg/kg
       •      Benzo(a)pyrene        28 mg/kg
       •      Benzo(b)fluoranthene  75 mg/kg
       •      Barium                160 mg/kg
       •      Cadmium               48 mg/kg
       •      Chromium             209 mg/kg
       •      Silver               6.12 mg/kg
              Zinc                 13,200  mg/kg
              Aroclors-1254/1260   0.38 mg/kg
       •      Hexachlorobiphenyl   0.38 mg/kg
              4,4'-DDD             0.08 mg/kg
-------
Chemical of Concern
                      TABLE  6-3

MAJOR CONTRIBUTORS TO RISK FOR TERRESTRIAL VEGETATION
        BASED ON RME AND CTE EXPOSURE, DRMO
           NSB-NLON, GROTON, CONNECTICUT

              Hazard Quotient  (RME)
                         Hazard Quotient  (CTE)
Aluminum
Antimony
Boron
Cadmium
Chromium
Copper
Mercury
Silver
Vanadium
Zinc
2
3
5
1
2
2
2
3
1
5
.OE+2
.8E+0
.8E+0
.4E+0
.8E+1
.9E+0
.9E+0
.1E+0
.7E+1
.7E+2
1.6E+2
1.5E+0
3.3E+0
l.OE+0
2.1E+1
1.4E+0
1.3E+0
Not Evaluated
1.3E+1
4.5E+1
                                            TABLE  6-4

                         MAJOR CONTRIBUTORS TO RISK FOR SOIL INVERTEBRATES
                               BASED ON RME AND CTE EXPOSURE,  DRMO
                                  NSB-NLON, GROTON,  CONNECTICUT
Chemical of Concern

Copper
Lead
Zinc
Chromium
    Hazard Quotient  (RME)

           9.7E+0
           7.7E+0
           5.7E+0
           1.1E+0
Hazard Quotient  (CTE)

       4.6E+0
       2.6E+0
    Not Evaluated
    Not Evaluated
-------
                                                      TABIiE 6-5
                               MAJOR CONTRIBUTORS TO RISK FOR TERRESTRIAL VERTEBRATES
                                                 RME SCENARIO, DRMO
                                           NSB-NLON, GROTON, CONNECTICUT
Receptor

Short-tailed Shrew
Red-tailed Hawk
Chemicals of Concern

Antimony
Vanadium
Zinc
Lead
All others
Total Receptor HI
Pathway

Soil
Food
Water
Chemicals of Concern

Zinc
4,4'-DDT
Antimony
4,4'-ODD
All others
Total Receptor HI
Pathway

Soil
Food
Water
 Total HI per COG for all
        Pathways
         3.4E+2
         7.2E+1
         2.4E+2
         5.6E+1
         2.0E+2
         9.2E+2
  Total HI per Pathway

         4.7E+2
         4.5E+2
         O.OE+0
Total HI per COG for all
        Pathways
         1.7E+2
         3.3E+0
         7.8E+0
         2.8E+0
         6.9E+1
         1.9E+2
  Total HI per Pathway

         5.9E+1
         1.3E+2
         O.OE+0
 % Contribution of COG to Total
          Receptor HI
             37.4
              7.9
             26.4
              6.1
             22.2

 % Contribution of Pathway to
      Total Receptor HI
             51.5
             48.5
              0.0
% Contribution of COG to Total
         Receptor HI
             88.9
              1.7
              4.2
              1.5
              3.7

 % Contribution of Pathway to
      Total Receptor HI
             31.4
             68.6
              0.0
NOTES:
HI   -   Hazard Index
COG  -   Contaminant of Concern
-------
                                                        TABIiE 6-6
                                  MAJOR CONTRIBUTORS TO RISK FOR TERRESTRIAL VERTEBRATES
                                                     CTE SCENARIO, DRMO
                                              NSB-NLON, GROTON, CONNECTICUT
Receptor

Short-Tailed Shrew
Red-Tailed Hawk
Chemicals of Concern

Antimony
Zinc
Lead
Thallium
All others
Total Receptor HI
Pathway

Soil
Food
Water
Chemicals of Concern

Zinc
Antimony
Thallium
Cobalt
All others
Total Receptor HI
Pathway

Soil
Food
Water
Total HI per COG for
    all Pathways
       1.4E+2
       1.9E+1
       1.9E+1
       1.9E+1
       4.0E+1
       2.4E+2
Total HI per Pathway

       1.3E+2
       l.OE+2
       O.OE+0
Total HI per COG for
    all Pathways
       1.3E+1
       3.1E+0
       7.0E-1
       4.0E-1
       4.8E-1
       1.8E+1
Total HI per Pathway

       8.0E+0
       9.9E+0
       O.OE+0
 Contribution of COG to Total
        Receptor HI
          58.8
           8.2
           8.1
           8.0
          16.9

o Contribution of Pathway to
     Total Receptor  HI
          56.5
          43.5
           0.0
 Contribution of COG to Total
        Receptor HI
          73.7
          17.5
           3.9
           2.2
           2.7

o Contribution of Pathway to
     Total Receptor  HI
          44.6
          55.4
           0.0
NOTES:
HI   -   Hazard Index
COG  -   Contaminant of Concern
-------
6.4.6  Discussion of Uncertainty Factors

Uncertainties in human health risk assessment arise from:

              Selection of COCs
       •      Exposure assessment
       •      Toxicological evaluation
       •      Risk characterization

Uncertainty in the selection of COCs is associated with the quality of the predictive data bases and the
procedures used to include or exclude constituents as chemicals of concern.

Uncertainty associated with the exposure assessment is associated with the values used as input variables
for a given intake route, the methods used and the assumptions made to determine exposure point
concentrations, and the predictions regarding future land use and population characteristics.

Uncertainty in the toxicity assessment is associated with the quality of the existing data to support
dose-response relationships, and the weight-of-evidence used for determining the carcinogenicity of
chemicals of concern.

Uncertainty in risk characterization is associated with exposure to multiple chemicals and the cumulative
uncertainty from combining conservative assumptions made in earlier activities. For the purpose of this
risk assessment, the use of unvalidated data adds considerable uncertainty because this new data shows
higher contaminant concentrations, and therefore greater potential risks. However, since the data are
unvalidated, it is not clear whether these greater potential risks reflect actual site conditions. Also,
the exposure assessment assumes that surface soil is accessible to potential receptors, which is
conservative because the entire site is paved, and it is likely to be maintained in paved condition in
the foreseeable future.

While the procedures for human health risk assessment are somewhat standardized and consequently the
uncertainty factors are controlled, the procedures for ecological risk assessment are less standardized.
The following discussion summarizes these uncertainty factors and states the salient assumptions for
ecological risk assessment  (ERA).

In order to understand how useful or appropriate the results of the ERA are, the uncertainties associated
with the assessment need to be considered. Uncertainties from fairly well-known sources, like errors in
sampling and measurement, will affect the assessment. More serious uncertainties may stem from
lesser-known sources, such as how available environmental contaminants are for uptake by exposed plants
and animals, and how well toxicological studies on laboratory subjects relate to organisms in nature. A
brief outline of the uncertainties in the ERA includes:

Sources of error or variability:

       •      Sampling and measurement
       •      Data handling and analysis

Incomplete knowledge of the relationship between measured contaminant concentrations and actual exposure
to contaminants:

       •      Spatial and temporal factors (e.g.,lack of feeding in areas of highest or lowest
              contaminant concentrations)
       •      Availability of contaminants for uptake by organisms
       •      Transfer of contaminants in food chains

Incomplete knowledge of toxicology:

       •      Use of non-native organisms and unnatural situations in experiments
       •      Applicability of length of the experiment and the effects measured
       •      Effects of toxicant mixtures

For the most part, assumptions are made corresponding to uncertainties in the ERA. The following list of
assumptions may help clarify the nature of the uncertainties:

Sampling and Data Handling

Errors in the design of the sampling program, performance of sampling, analytical measurement, data
handling, and data analysis do not have a significant effect on the results of the ERA. Therefore,
-------
assumptions are not relevant to this aspect of the input.

    Exposure
       •      Proportion of site size to individual's home range is an adequate exposure factor
       •      Animals are exposed throughout the year
       •      No degradation or loss of contaminants from system
       •      100 percent of each contaminant is available for uptake by organisms
       •      Contaminant transfer from one level of a food chain to the next is adequately described by
              a single factor

    Toxicology
       •      Experimental conditions apply adequately to those at DRMO
       •      Toxicants do not affect each others'  actions via synergistic or antagonistic effects

6.5    CONCLUSION

Actual or threatened releases of hazardous substances from this site, if not addressed by implementing
the response action selected in this Interim ROD, may present an imminent and substantial endangerment to
public health, welfare, or the environment.

                     7.0 REMEDIAL ACTION OBJECTIVES AND DEVELOPMENT OF ALTERNATIVES

This section describes the remedial action objectives and the development of alternatives. Alternatives
were developed in the FS for contaminated soil and groundwater to meet remedial action objectives for
these media.

7.1 STATUTORY REQUIREMENTS/RESPONSE OBJECTIVES

Under its legal authorities, the U.S. Navy's primary responsibility at NPL sites is to undertake remedial
actions that are protective of human health and the environment. In addition, Section 121 of CERCLA
establishes several other statutory requirements and preferences, including: a requirement that the U.S.
Navy's remedial action, when complete, must comply with all federal and more stringent state
environmental standards, requirements, criteria or limitations under an environmental or facility siting
law, unless a waiver is granted; a requirement that the U.S. Navy select a remedial action that is
cost-effective and that utilizes permanent solutions and alternative treatment technologies or resource
recovery technologies to the maximum extent practicable; and a preference for remedies in which treatment
that permanently and significantly reduces the volume, toxicity, or mobility of the hazardous substances
is a principal element over remedies not involving such treatment. Remedial alternatives were developed
to be consistent with these Congressional mandates.

Based on preliminary information relating to types of contaminants, environmental media of concern, and
potential exposure pathways, RAOs were developed to aid in the development of alternatives. These
remedial action objectives were developed to mitigate existing and future potential threats to public
health and the environment. These remedial action objectives are as follows:

       •      Prevent exposure (unacceptable risk)  to receptors under either a current industrial or
              future,  although unlikely,  residential land use scenario either through institutional
              controls and/or removal/treatment/disposal

       •      Prevent unacceptable risk to ecological receptors in the Thames River from potential
              migration of contaminants
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ESTIMATED VOLUMES OF CONTAMINATED MEDIA

For remedial action purposes, preliminary volumes of contaminated media were estimated from samples that
contained contaminants at concentration levels that exceeded Remediation Goals for current industrial
land use and future residential land use. Based on the known extent of contamination, the following are
the estimated areas and volumes of contaminated soil:
    Current Industrial Land Use
    Future Residential Land Use

    NOTES:
Estimated Area
   (sq ft)
   11,230
   105,800
Average Depth
      (ft)
    6 to 10
    6 to 10(1)
Estimated Volume
     (cu yd)
      3,150
     13,570
    1 Depths include existing clean cover of 3 feet thickness from post-removal action backfill.
      A 1:1 sideslope is assumed for stability during excavation.

7.2   TECHNOLOGY SCREENING AND ALTERNATIVE DEVELOPMENT

CERCLA and the NCP have set forth the process by which remedial actions are evaluated and selected. In
accordance with these requirements, a list of potential technologies were screened for effectiveness,
implementability, and cost in attaining the remedial action objectives for contaminated soil and
groundwater. A range of alternatives were developed from the technologies that were retained from
screening.

The FS developed a range of alternatives considering the CERCLA statutory preference for a treatment that
reduces the toxicity, mobility, or volume of the hazardous substances. This range included an alternative
that removes or destroys hazardous substances to the maximum extent feasible, eliminating or minimizing
to the degree possible the need for long-term management. This range also included an alternative that
removes the threat posed by the contaminated media at the site with little or no treatment onsite but
disposes of the material at an offsite facility where the material would be managed in a manner that
would minimize any risk of threat to human health or release to the environment. The range also includes
an alternative that involves little or no treatment onsite but provides protection through engineering or
institutional controls, and a no action alternative.

                            8.0 DESCRIPTION OF ALTERNATIVES
This section provides narrative summary of the alternatives that were evaluated in the FS  (B&R
Environmental, September 1997). The alternatives were as follows:  (1) No Action,  (2) Institutional
Controls and Monitoring, (3) "Hot Spots" Excavation, Offsite Disposal, Institutional Controls, and
Monitoring,  (4) Alternative 4 - Excavation, Onsite Treatment (thermal desorption  &
fixation-solidification),  and Offsite Disposal
8.1
       ALTERNATIVE 1 - NO ACTION
No action is required for this alternative. This alternative is required by the National Contingency Plan
(NCP) and is used as a baseline comparison with other alternatives. At the DRMO this alternative would
still include the existing cap but with no maintenance of that cap. This alternative is typically not
selected unless the risks of doing nothing are acceptable to human health and environment. At this site
the No Action alternative would result in contamination being left in place which would be a continued
threat to human health and the environment.

This alternative would not comply with the following key Applicable or Relevant or Appropriate
Requirements (ARARs):

       •       Connecticut Department of Environmental Protection (CTDEP)  Remediation Standard Regulations
              (direct  exposure criteria would be applicable in the future if the existing cap deteriorates
              and the  contaminated soil is no longer considered "inaccessible.")

       •       Federal  Executive Order regarding Floodplain Management (applicable because the site is
              within the 100  year flood plain of Thames River)

       •       Federal  Coastal Zone Management Act (applicable because the site is present in a coastal
              zone)
There are no costs associated with this alternative.
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8.2    ALTERNATIVE 2 - INSTITUTIONAL CONTROLS AND MONITORING

Alternative 2 would consist of two major components in addition to the existing cap:  (1) institutional
controls and  (2) monitoring.

Institutional controls would include maintenance of the existing cap and implementation of limits to site
access and land use restrictions. These controls would eliminate or reduce pathways of exposure to
contaminants at the site.

Monitoring would include regular groundwater sampling and analysis in accordance with the Groundwater
Monitoring Plan (B&R Environmental, October 1997) .  If groundwater COCs concentrations are shown to exceed
site-specific Surface Water Protection Criteria  (SWPC),  and Volatilization Criteria, the scope of this
monitoring would be expanded to include surface water and river sediment sampling and analysis to
determine if COCs are migrating from the DRMO to the Thames River and if additional action is reguired.
Finally, monitoring would include 5-year reviews for the life of the project, i.e., 30 years.

This alternative would comply with the location-specific Applicable or Relevant or Appropriate
Reguirements, particularly:

       •      Executive Order regarding Floodplain  Management (applicable because the site is within the
              100  year flood plain of Thames River)
       •      Coastal  Zone Management Act (applicable because the site is present in a coastal zone)

This alternative would comply with chemical specific ARARs and TBCs, particularly the direct exposure
criteria under the State of Connecticut's Remedial Standards for soils.

    Estimated Time for Construction:          Minimal
    Capital Cost:                              $90,800
    Operating and Maintenance Cost:           $618,000 (total for 30 years)
    Total Cost  (as present worth):            $708,000

8.3 ALTERNATIVE 3 - "HOT SPOTS" EXCAVATION, OFFSITE DISPOSAL, INSTITUTIONAL CONTROLS, AND MONITORING

Alternative 3 would consist of four major components in addition to the existing cap: (1) excavation of
contaminated soil "hot spots" with dewatering of wet soil and repair and restoration of the existing cap,
(2) offsite disposal of excavated soil,  (3) institutional controls, and  (4) monitoring.

Soil contaminated with Contaminants of Concern  (COCs) at concentrations exceeding industrial land use
remediation goals would be excavated, dewatered on site as reguired, and disposed of at an offsite RCRA
hazardous waste Treatment/Storage/Disposal  (TSD) facility. Clean soil from an offsite borrow source would
be backfilled in the excavated areas. The excess water present in the soil excavated from the saturated
zone would be drained and the wastewater treated onsite at a Dewatering/Wastewater Treatment  (DW/WWT)
plant that would be constructed on site, followed by discharge to Thames River.

Institutional controls and monitoring would be identical to those for Alternative 2.

This alternative would comply with location-specific ARARs, particularly:

       •      Federal  Executive Order regarding Floodplain Management (applicable because the site is
              within the 100 year flood plain of Thames  River)

       •      Federal  and State of Connecticut Coastal Zone Management Act (applicable because the site is
              present  in a coastal zone)

This alternative would comply with chemical specific ARARs and TBCs, particularly the direct exposure
criteria under the State of Connecticut's Remediation Standards for soil.

This alternative would also comply with action-specific ARARS with regard to excavation, dewatering, and
offsite disposal,  particularly:

              Federal  Clean Air Act:  National Emission Standards for Hazardous Air Pollutants (NESHAPs)
              applicable to control of fugitive dust emissions during excavation,  handling,  and
              transportation)
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       •      Federal Air Pollution Control:  Stationary Sources,  Control of Particulate Emissions and
              Control of Odors (applicable to control of fugitive dust emission,  particulate emissions and
              odors during excavation,  handling and transportation)

       •      State of Connecticut's Hazardous Waste Management:  Generator and Handier
              Reguirements-General Standards,  Listing and Identification (applicable to determining
              hazardous characteristics of excavated waste)

       •      State of Connecticut's Hazardous Waste Management:  Treatment/Storage/Disposal Facility
              (TSDF)  Standards (applicable to temporary storage and dewatering of excavated soil that is
              determined to be hazardous by characteristic)

       •      State of Connecticut's Solid Waste Management Regulations (applicable to closure of site
              remaining after excavation of "hot spots")

       •      State of Connecticut's Disposition of PCBs (applicable to disposal  of excavated soil
              containing PCBs at levels exceeding remedial goals)

       •      State of Connecticut's Water Pollution Control and Water Quality Standards (applicable to
              discharge of treated water from dewatering of excavated soil)

    Estimated Time for Construction:        5 months
    Capital Cost:                           $4,363,000
    Operating and Maintenance Cost:         $ 618, 000  (total for 30 years)
    Total Cost  (as present worth):          $4,981,000

8.4    ALTERNATIVE 4 - EXCAVATION, ONSITE TREATMENT  (THERMAL DESORPTION & FIXATION-SOLIDIFICATION), AND
       OFFSITE DISPOSAL

Alternative 4 would consist of three major components:  (1) excavation with dewatering of wet soil,  (2) on
site treatment of excavated soil, and  (3) offsite disposal of treated soil.

Soil contaminated with COCs at concentrations exceeding residential land use, ecological, and surface
water protection remediation goals would be excavated. Wet excavated soil would be dewatered on site if
necessary. The excess water from the excavated saturated zone soil would be drained and the wastewater
treated onsite at a DW/WWT plant and discharged to Thames River, as noted under Alternative 3.

Excavated soil would be treated on site using a combination of thermal desorption to remove and destroy
organic COCs and chemical fixation-solidification to immobilize inorganic COCs. High-temperature thermal
desorption would remove organic contaminants through volatilization and subseguent treatment and
destruction of these volatilized contaminants. As reguired, the thermally treated soil would then undergo
chemical fixation-solidification to bind inorganic contaminants with the soil in a leach-resistant
matrix. Prior to thermal desorption, excavated soil would be pre-treated by size separation and/or
crushing-grinding-shredding, if necessary.

Following on site treatment, the soil would be disposed of at an offsite solid waste disposal facility.
Clean soil from an offsite borrow area would be backfilled into the excavated areas.

This alternative would comply with location- specific ARARs, particularly:

       •      Federal Executive Order regarding Floodplain Management (applicable because the site is
              within the 100 year flood plain of Thames River)

       •      Federal and State of Connecticut's Coastal Zone Management Act (applicable because the site
              is present in a coastal zone)

This alternative would comply with chemical specific ARARs and TBCs, particularly the direct exposure
criteria under the State of Connecticut's Remediation Standards for soil.

This alternative would also comply with action-specific ARARS with regard to excavation, onsite treatment
and offsite disposal, particularly:

              Federal Clean Air Act:  National Emission Standards for Hazardous Air Pollutants (NESHAPs)
              applicable to control of fugitive dust emissions during excavation,  handling,  treatment,  and
              transportation and applicable to control of emissions from thermal  desorption)
-------
       •      Federal Air Pollution Control:  Stationary Sources,  Control of Particulate Emissions,  Control
              of Organic Compounds Emissions  and Control of Odors (applicable to control of fugitive dust
              emission,  particulate emissions and odors during excavation,  handling,  treatment,  and
              transportation,  and applicable  to control of emissions from thermal desorption)

       •      State of Connecticut's Hazardous Waste Management:  Generator and Hand'er
              Reguirements-General Standards, Listing & Identification (applicable to determining
              hazardous  characteristics of excavated waste)

       •      State of Connecticut's Hazardous Waste Management:  Land Disposal Restrictions (applicable to
              deriving treatment standards for excavated soil that is determined to be hazardous by
              characteristic)

       •      State of Connecticut's Hazardous Waste Management:  TSDF Standards (applicable to temporary
              storage and treatment of excavated soil that is determined to be hazardous by
              characteristic)

       •      Federal Resource Conservation and Recovery Act: Treatment Standards for Hazardous  Debris-
              Thermal Desorption (applicable  to treatment of excavated soil that is determined to be
              hazardous by characteristic)

       •      State of Connecticut's Solid Waste Management Regulations (applicable to closure of site
              after excavation of soil contaminated at levels exceeding remediation goals)

       •      State of Connecticut's Disposition of PCBs (applicable to treatment and disposal of
              excavated  soil  containing PCBs at levels exceeding remedial goals)


       •      State of Connecticut's Water Pollution Control and Water Quality Standards (applicable to
              discharge of treated water from dewatering of excavated soil)

    Estimated Time for Construction:   7 months
    Capital Cost:                      $  16,129,000
    Operating and Maintenance Cost     $  0
    Total Cost  (as present worth):     $  16,129,000

                     9.0 SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES

Section 121(b)(1) of CERCLA presents several factors that, at a minimum, the U.S. Navy is required to
consider in its assessment of alternatives. Building upon these specific statutory mandates, the NCP
articulates nine evaluation criteria to be used in assessing the individual remedial alternatives.

9.1    EVALUATION CRITERIA USED FOR DETAILED ANALYSIS

A detailed analysis was performed on the  alternatives using the nine evaluation criteria in order to
select an interim site remedy. Section 9.2 contains a summary of the comparison of each alternative's
strengths and weaknesses with respect to  the nine evaluation criteria. These criteria are summarized in
Subsection 9.1.1 through 9.1.3.

9.1.1  Threshold Criteria

The two threshold criteria described below must be met in order for the alternatives to be eligible for
selection in accordance with the NCP.

       •      Overall protection of human health and the environment addresses whether a remedy  provides
              adequate protection to human health and the environment,  in both short term and long term,
              from unacceptable risks posed by hazardous substances, pollutants,  or contaminants present
              at the site by eliminating,  reducing,  or controlling exposure.

       •      Compliance with  ARARs addresses whether a remedy attains applicable or relevant and
              appropriate requirements under  Federal environmental laws and state environmental  and
              facility siting  laws or provide grounds for involving a waiver.
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9.1.2  Primary Balancing Criteria

The following five criteria are utilized to compare and evaluate the elements of one alternative to
another that meet the threshold criteria.

Long-term effectiveness and permanence addresses the criteria that are utilized to assess alternatives
for the long-term effectiveness and permanence they afford, along with the degree of certainty that they
will prove successful.

       •      Reduction of toxicity,  mobility,  or volume through treatment addresses the degree to which
              alternatives employ recycling or treatment that reduces toxicity,  mobility,  or volume,
              including how treatment is used to address the principal threats posed by the site.

       •      Short-term effectiveness addresses the period of time needed to achieve protection and any
              adverse impacts  on human health and the environment that may be posed during the
              construction and implementation period,  until cleanup goals are achieved.

       •      Implementability addresses the technical and administrative feasibility of a remedy,
              including the availability of materials and services needed to implement a particular
              option.

       •      Cost includes estimated capital costs (indirect and direct)  and annual operating &
              maintenance  (O&M)  costs,  as well as present-worth costs.
9.1.3  Modifying Criteria

The modifying criteria are used on the final evaluation of remedial alternatives generally after the U.S.
Navy has received public comment on the RI/FS and Proposed Plan.

       •      State acceptance addresses the state's position and key concerns related to the preferred
              alternative and  other alternatives,  and the state's comments on ARARs and to be considered
              (TBC)  criteria or the proposed use of waivers.

       •      Community acceptance addresses the public's general response to the alternatives described
              in the Proposed  Plan and RI/FS report.

9.2    COMPARATIVE ANALYSIS OF ALTERNATIVES BY CATEGORY

9.2.1  Overall Protection of Health and Environment

Alternative 1 would provide some protection of human health and the environment because of the existing
cap. However, since the cap would not be maintained, this protection would be limited. Also, since no
monitoring would be performed, potential contaminant migration to groundwater and to the Thames River
would not be detected in time for appropriate action.

Alternative 2 would be protective of human health and the environment. Institutional controls would be
protective because the existing cap would be maintained, site access would be restricted, and the DRMO
would be kept in its current industrial function, all of which would minimize human health and ecological
risks from direct exposure to contaminated soil under the current land use scenario. Maintenance of the
cap would also minimize infiltration through the contaminated vadose zone soil and thereby, minimize
potential contaminant migration. Monitoring would be protective as it would detect potential migration of
soil contaminants to the Thames River which could adversely impact ecological receptors in that river or
to groundwater.

Alternative 3 would be more protective than Alternative 2 since, in addition to institutional controls
and monitoring, soil "hot spots"  (i.e., soil contaminated above industrial land use remediation goals)
would be removed from the site and disposed of at an offsite RCRA hazardous waste TSD facility. Although
complete verification sampling would not be feasible because of the presence of sheet piling and water in
most excavated areas, this removal and disposal would virtually eliminate unacceptable human health risk
from direct exposure to contaminated soil under the current industrial land use scenario. Removal and
disposal of soil "hot spots" would also be protective of ecological receptors in the Thames River by
significantly reducing the possibility that contaminants would migrate from the DRMO soil to that river.

Alternative 4 would be the most protective of human health and the environment. All soil contaminated
above residential land use, ecological, and surface water protection remediation goals would be
excavated, treated on site to irreversibly remove and destroy organic COCs and immobilize inorganic COCs,
and disposed of at an offsite solid waste disposal facility. Although the existing cap would be removed
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and not replaced and complete verification sampling would not be feasible because of the presence of
sheet piling and water in most excavated areas, these actions would virtually eliminate unacceptable
risks to human and ecological receptors from direct exposure to soil under all scenarios. These actions
would also be protective of ecological receptors in the Thames River since the sources of potential
contaminant migration to that river from the DRMO soil would no longer exist.

9.2.2  Compliance with ARARs and TBCs

Alternative 1 would not comply with chemical-specific and location-specific ARARs. No action-specific
ARARs or TBCs apply to this alternative.

Alternatives 2,3, and 4 would comply with chemical-specific, location-specific, and action-specific
ARARs and TBCs. These alternatives would comply with the CTDEP Remediation Standard Regulations by either
minimizing exposure or removing the contaminants from the site. These alternatives would also comply with
the Executive Order regarding Floodplain Management and the Coastal Zone Management Act.

In addition to these location-specific ARARs, Alternative 2 would also comply with action-specific ARARs
corresponding to monitoring well placement, and handling/storage/disposal of any hazardous waste or
PCB-contaminated waste that may be generated during well placement, Alternatives 3 and 4 would also
comply with action-specific ARARs corresponding to fugitive dust emissions controls, water pollution
control and water guality standards, hazardous waste management, TSDF standards, and PCBs disposition for
excavation/dewatering and storage/disposal of wastes. Alternative 4 would also comply with RCRA standards
for thermal desorption treatment.

9.2.3   Long-term Effectiveness and Permanence

Alternative 1 would have very limited long-term effectiveness and permanence because all contaminated
soil would remain on site, and the existing cap would not be maintained. Therefore, as the existing cap
deteriorates over time, an unacceptable risk  (HI > 1.0) could develop for site workers from direct
exposure to contaminated soil. As there would be no institutional controls to limit site access or
prevent residential development, the potential would also exist for unacceptable risk to develop for
trespassers (HI > 1.0)  and possible future resident  (HI > 1.0 and ICR > 1E-4). Residential development of
the DRMO could also result in unacceptable risk to a correspondingly increased population of ecological
receptors from exposure to contaminated surface soil. Since there would be no monitoring, potential
impact to the groundwater and to the Thames River from possible migration of contaminants from soil would
not be detected in time for appropriate remedial action,

Alternative 2 would be long-term effective, Institutional controls, including maintenance of the existing
cap, limits to site access, and land use restrictions, would effectively minimize risks from direct
exposure of human and ecological receptors to contaminated soil. Long-term monitoring would be effective
for the detection of potential migration of soil contaminants to the Thames River which could adversely
impact ecological receptors in that river.

Alternative 3 would provide better long-term effectiveness than Alternative 2 since, in addition to
institutional controls and monitoring, it would include removal and offsite disposal of soil "hot spots".
Although complete verification sampling would not be feasible because of the presence of sheet piling and
water in most excavated areas, these remedial actions would effectively eliminate unacceptable human
health risk from direct exposure to soil contaminated above industrial land use remediation goals. These
remedial actions would also effectively reduce the potential for soil contaminants to migrate to the
Thames River,  which could adversely impact ecological receptors in that river.

Alternative 4 would offer the best long-term effectiveness. All soil contaminated above residential land
use, ecological, and surface water protection remediation goals would be excavated, treated on site to
irreversibly remove and destroy organic COCs and immobilize inorganic COCs, and disposed of at an offsite
solid waste disposal facility. Although complete verification sampling would not be feasible because of
the presence of sheet piling and water in most excavated areas, these remedial actions would effectively
eliminate unacceptable risks to human and ecological receptors from direct exposure to soil under all
land use scenarios. These remedial actions would also effectively eliminate the potential for soil
contaminants to migrate to the Thames River, which could adversely impact ecological receptors in that
river.

9.2.4  Reduction of Toxicitv, Mobility, or Volume through Treatment

Alternatives 1 and 2 would not achieve any reduction of toxicity, mobility, or volume of contaminants
through treatment.
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Alternative 3 would achieve a slight reduction in contaminant toxicity and volume through the on site
treatment of the drainage water from the wet excavated soil by the granular activated carbon (GAG)
adsorption unit of the DW/WWT facility. Because the GAG would ultimately be either thermally regenerated
or destroyed by incineration, the achieved reduction in contaminant toxicity and volume would be
100-percent irreversible.

Alternative 4 would significantly reduce contaminant toxicity, mobility, and volume through treatment. On
site thermal desorption would remove 90 percent or more of organic COCs in a 100 percent irreversible
way. On site chemical fixation-solidification would immobilize inorganic COCs in an almost completely
irreversible way. However, chemical fixation-stabilization may also increase volume of treated soil by 10
to 15 percent. As Alternative 3, Alternative 4 would also achieve a slight, 100-percent irreversible,
reduction in contaminant toxicity and volume through the on site treatment of the drainage water from the
wet excavated soli by the GAG adsorption unit of the DW/WWT facility.

9.2.5  Short-term Effectiveness

Implementation of Alternative 1 would not result in risks to site workers or adversely impact the
surrounding community or environment since no remedial activities would be performed. Alternative 1 would
never achieve the remedial action objectives (RAOs).

Implementation of Alternative 2 would result in a slight possibility of exposing site workers to
contaminated soil during the maintenance of the existing cap and fence and to contaminated soil and
groundwater during the construction of new groundwater monitoring wells and the maintenance and sampling
of the new and existing wells. However, these risks of exposure would be effectively controlled by
wearing of appropriate PPE and compliance with proper site-specific health and safety procedures.
Implementation of Alternative 2 would not adversely impact the surrounding community and environment.
Alternative 2 would immediately achieve the RAOs. However, continued achievement of the RAO for
protection of ecological receptors in the Thames River would have to be regularly verified through
monitoring.

Implementation of Alternatives 3 and 4 would result in a significant possibility of exposing construction
workers to contaminated soil and groundwater during the excavation, dewatering, and offsite
transportation activities. Implementation of Alternative 4 would also result in an added possibility of
exposing construction workers to contaminated soil and offgas emissions during the thermal desorption and
chemical fixation-solidification activities. However, all these risks of exposure would be effectively
controlled by the implementation of engineering controls  (e.g., dust suppression, offgas treatment), by
the wearing of appropriate PPE, and by compliance with applicable OSHA regulations and proper
site-specific health and safety procedures. Implementation of Alternative 3 could have some impact on the
surrounding community and environment because of the potential for release of fugitive dust and spillage
of contaminated soil during excavation and offsite transportation. However, this impact would be
adeguately controlled through the implementation of appropriate procedures, such as perimeter air
monitoring, spill prevention, and erosion and sedimentation controls. Implementation of Alternative 4
could have a slightly greater impact than Alternative 3 on the surrounding community and environment
because of the added risk of exposure to offgas from the thermal desorption unit. However, this possible
incremental impact would also be adequately controlled through offgas treatment. Alternative 3 would
achieve the RAOs in 5 months but continued achievement of the RAO for protection of ecological receptors
in the Thames River would have to be regularly verified through monitoring: Alternative 4 would achieve
the RAOs in 7 months.

       Implementabillitv
There would be no remedial action to implement under Alternative 1.

Alternative 2 would be simple to implement. Maintenance of the existing cap and fence,  posting of
notices, and institution of land use restrictions as part of the institutional controls component are all
relatively simple tasks which could be readily accomplished. Installation of new wells, maintenance and
sampling of new and existing wells, and performance of 5-year reviews as part of the monitoring component
could also be readily accomplished. Resources, equipment, and materials are available for all of these
tasks. The administrative implementability of institutional controls and monitoring would also be simple
as long as the DRMO stays under the Navy control but, even in the unlikely event that this would change,
adequate provisions could be relatively easily incorporated in any property transfer documents to insure
continuation of these controls and monitoring under civilian ownership.

Alternative 3 would be significantly more difficult to implement than Alternative 2. This alternative
would require excavation of non-cohesive soil (i.e., sand and gravel) to a depth of up to 10 feet bgs,
which is well below the groundwater table. This would raise two significant implementability concerns.
First, the excavated areas would have to be extensively shored with sheet piling and, second, water would
-------
have to be allowed to accumulate within the excavated areas, which would significantly hinder excavation
efficiency. These concerns aside, excavation could be performed with normal construction equipment which
is readily available. Installation and operation of a DW/WWT facility for the onsite dewatering of wet
soil and treatment of drainage water could be implemented with readily available resources, equipment,
and material. Offsite disposal of excavated soil would be readily implementable since permitted RCRA
hazardous waste TSD facilities with adequate capacity are available to receive this kind of waste
material. The institutional controls and monitoring components of Alternative 3 would be identical to and
as readily implementable as those of Alternative 2. The administrative implementability of Alternative 3
would be very similar to that of Alternative 2 with the difference that the proper State agencies would
have to be consulted to determine treatment criteria for discharge of the drainage water to the Thames
River and that offsite disposal of excavated soil would have to meet all applicable RCRA regulations,
including manifesting of the shipments of excavated soil. Both of these additional administrative
requirements could readily be accomplished.

Alternative 4 would be the most difficult to implement. The significant concerns about implementability
of the excavation component of this alternative would be identical to those of the same component for
Alternative 3. As with Alternative 3, onsite dewatering of wet soil and treatment of the drainage water
would be readily implementable. For the onsite treatment component, although thermal desorption services
are readily available, the number of contractors with experience for treatment of PCB contaminated waste
may be relatively limited. The balance of the on site treatment component would be easily implementable
since experienced chemical fixation-solidification contractors are readily available, There would be no
institutional controls and monitoring to implement. The administrative implementability of Alternative 4
would be comparable to that of Alternative 3 with the additional requirement that the appropriate State
agencies would have to be contacted to determine acceptable air emissions for the    thermal desorption
unit, which could be accomplished relatively easily.

9.2.7  Cost

The capital, total O&M cost over 30 years, and 30-year net present-worth (NPW) costs of the alternatives
are presented in the following table and ranked according to the 30-year NPW cost.

    Alternative        Capital(&)        30-year O&M ($)         30-year NPW(&)
          100                        0
          2               90,800            618,000                  708,000
          3            4,363,000            618,000                4,981,000
          4           16,129,000                  0               16,129,000

The total operating costs shown for Alternatives 2 and 3 are for groundwater monitoring only and include
a $20,000 lump sum amount at the end of the third year of monitoring for final site reviews and report
preparation. The 30-year NPW costs for Alternatives 2 and 3 include the performance of 5-year reviews for
30 years.

9.2.8  State Acceptance

The CTDEP, as a party of the Federal Facility Agreement  (FFA), has provided comments on the FS (B&R
Environmental, September 1997) and PRAP (U.S. Navy and B&R Environmental, September 1997), and has
documented its concurrence with the remedial action, as stated in Section 13 of this Interim ROD. A copy
of the CTDEP's letter of concurrence is presented in Appendix D of this Interim ROD.

9.2.9  Community Acceptance

The PRAP presents the preferred alternative for the DRMO. From September 18, 1997 through October 18,
1997, the U.S. Navy held a public comment period to accept public input. A public meeting was held in
Groton, Connecticut on September 25, 1997 to discuss the PRAP and to accept any oral comments.

Community acceptance of the PRAP was evaluated based on comments received at the public meeting and
during the public comment period. This is documented in the transcript of the Public Meeting in Appendix
A, and in the Responsiveness Summary in Appendix C of this Interim ROD.

                                  10 . 0 SEIiECTED REMEDY

Based upon the requirements of CERCLA,  the NCP, the detailed analysis of alternatives, and comments
received from the U.S. EPA, the CTDEP,  and the public,  the U.S. Navy has selected Alternative 2
(Institutional Controls and Monitoring)  as the most appropriate remedy for the DRMO site. Upon
implementation of this remedy, the human health risks resulting from exposure to the soil and groundwater
at the DRMO will be minimized and potential risks to ecological receptors in the adjacent Thames River
-------
will be monitored.

Alternative 2 consists of two components in addition to the existing asphalt and GCL cap: 1)
institutional controls and 2) groundwater monitoring. This alternative will rely upon maintenance of the
existing cap, limitation of site access, restrictions of land use, and groundwater monitoring to evaluate
whether contaminants present at the DRMO are migrating to the Thames River and causing adverse ecological
effects. Although this alternative is based on the assumption that the DRMO will continue to be owned and
operated by the Navy, provisions are included in this IROD for the continuation of these institutional
controls in the event of a different ownership. The estimated net present worth of Alternative 2 is
$708,000, with a capital cost of $90,800 and an annual operation and maintenance cost of $21,000.

10.1     COMPONENT 1: INSTITUTIONAL CONTROLS

Institutional controls will include maintenance of the existing cap, limitations on site access, and
restrictions on land use.

10.1.1   Cap Maintenance

Maintenance of the existing asphalt and GCL cap will consist of regular inspections to assess the
integrity of the asphalt and GCL cap. Periodic repair and replacement of the asphalt layer will be
performed as needed.

10.1.2   Limitations on Site Access

Limitations on Site Access will consist of maintaining the existing chain link fence that surrounds the
DRMO and posting of signs to warn potential trespassers that a health hazard is present. Signs will be
posted along the perimeter and at the front entrance to the site. In addition, during operation of the
site for its current military purpose, gates will be locked, and a security desk will be maintained at
the entrance to the site.

10.1.3   Land Use Restrictions

This IROD specifies the use of land use restrictions (LURs) for that portion of the Naval Submarine Base
New London  (the Installation) in the area of the DRMO (the Subject Area)  to limit activities  (including,
but not limited to, excavation or drilling) , to prohibit residential use of property, and restrict
excessive vehicular use or any other activity that could compromise the integrity of the existing cover
system. The restrictions are intended to protect human health and the environment from exposure to
landfilled waste and contaminated soil and to restrict activities that could compromise the integrity of
the cover system or interfere with monitoring of the site. If these institutional controls are complied
with and they fail to protect human health and the environment, this IROD shall be reopened.

10.1.3.1 Land Use Restrictions

No restricted activities or uses shall occur without prior approval from EPA and the CTDEP. In
furtherance of these purposes, the Navy shall reguire that use, occupancy, and activity of and at the
Subject Area be restricted as follows:

    1.    No residential use  (as defined under CT Remediation Standard Regulations, RSCA
          22a-133k-l(a)(53))
          of the Subject Area will be permitted;
    2.    No building, structure or improvement of existing structures shall be allowed on the Subject
          Area;

    3.    No activity that could breach or damage the existing cover system shall occur; and

    4.    No entry upon the Subject Area by any motor vehicle weighing in excess of the structural load
          limit of the existing cover system shag occur.

The Navy shall ensure that notice of the existence of the cover system and the LURs at the DRMO are
conspicuously posted. A copy of the LURs shall be maintained and available at the Subject Area. The LURs
shall be recorded in the base master plan and any other Installation vehicles which will ensure proper
notification of the LURs to Installation personnel.

Any proposed changes to or temporary release of any previously identified LURs for the site must be
approved by the agencies in writing prior to implementation. Reguests for review of any LURs change
proposal will consider the degree of change proposed, the effectiveness of the remediation effort to
-------
date, any natural remediation that may have occurred since the original remedial actions, etc.

10.1.3.2  Monitoring to assure compliance with the Land Use Restrictions

Compliance with the LURs at DRMO shall be accomplished through strict adherence to such vehicles as the
base master plan. The Navy shall notify the agencies if, despite proper precautions, an unauthorized land
use or activity is discovered by the installation. The unauthorized land use or activity will be reported
immediately to the agencies for determination of an appropriate corrective action.

The Navy shall review on a guarterly basis the status of adherence to the LURs. The Navy shall forward an
annual report describing the present and anticipated land use and LURs at DRMO to EPA and the CTDEP
certifying retention of the specified LURs for the DRMO site.

10.1.3.3  Transfer of Title

If the Navy seeks to transfer title to any property within the Subject Area, the LURs shall be contained
in the instrument of conveyance and such instrument shall be filed and recorded in the land Records of
the Town of Ledyard, State of Connecticut.

The filing and recording of LURs by the Navy or disposal agency shall be in accordance with state and
local law and include, without limitation, declaration(s) of covenants, conditions, and restrictions that
run with the land setting forth the LURs and compliance therewith. The form and substance of the
Declaration and any future declarations(s) shall be those determined in the sole and absolute discretion
of EPA, in consultation with CTDEP, and shall be subject to review and approval by EPA, in consultation
with CTDEP, prior to filing. All such declaration(s) shall be enforceable by the United States and the
State of Connecticut and shall provide that these persons have the right to inspect the Subject Area at
reasonable times and with prior notice, unless an emergency situation exists, to assess compliance with
the declaration.

The LURs and obligations set forth in this IROD shall be binding upon any Successors in Interest and
Assigns. In the event the Subject Area is to be transferred by deed, the Navy shall reguest the disposal
agency to ensure that any deed, lease, or other instrument of conveyance for the Subject Area shall: (a)
contain a notice that the Subject Area and any interest in the Subject Area is subject to the
restrictions and obligations of this IROD: (b) contain such restrictions and obligations, and, (c)
include agreement by the transferee of the interest in the Subject Area to comply with such restrictions
and obligations. Prior to any transfer of any interest in the Subject Area the prospective Successor in
Interest shall be provided with a  copy of this IROD.

10 . 2 COMPONENT 2 : GROUNDTCATER MONITORING

Groundwater monitoring shall be performed in accordance with the Groundwater Monitoring Plan for the DRMO
site  (Brown & Root Environmental, October 1997). Groundwater samples will be analyzed to evaluate whether
contamination from the DRMO is migrating to the Thames River and causing an adverse ecological effect.
After baseline conditions have been established as described in the Groundwater Monitoring Plan,  the
monitoring program may be revised based on the analytical data collected from the previous sampling
events. If groundwater COCs are detected at concentrations above SWPCs or Volatilization Criteria,
additional evaluations will occur as described in the Groundwater Monitoring Plan, including but not
limited to surface water and sediment samples shall be collected and analyzed to determine if these COCs
are migrating from the DRMO to the Thames River. After sufficient monitoring data have been collected,
such data will be evaluated to determine the need for additional remedial action at the site. If data
show that the site has not adversely impacted the environment, the need for additional monitoring will be
evaluated and modified, as appropriate. Figure 10-1 depicts the decision-making framework for the
groundwater data collection.

Every 5 years for 30 years, a site review will be conducted to evaluate the site status and determine
whether further action is necessary. Such site reviews are reguired when contaminants remain at the site
(see CERCLA °121 (c)) .


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                              11.0 STATUTORY DETERMINATIONS

Under CERCLA Section 121, the U.S. Navy must select remedies that are protective of human health and the
environment, comply with applicable or relevant and appropriate requirements (unless a statutory waiver
is justified),  are cost-effective, and utilize permanent solutions and alternative treatment technologies
or resource recovery technologies to the maximum extent practicable. In addition, CERCLA includes a
preference for remedies that employ treatment that permanently and significantly reduces volume,
toxicity, or mobility of hazardous wastes as their principal element. The following sections the discuss
how the selected remedy for the DRMO meets the statutory requirements.

11.1  PROTECTION OF HUMAN HEALTH AND THE ENVIRONMENT

The selected remedy protects human health by minimizing direct contact with the contaminants using
institutional controls and maintenance of the existing asphalt and GCL cap. The reduced exposure to
potential receptors will ensure that the risks are within the acceptable limits corresponding to a
maximum cumulative ICR of 1E-04 and a maximum cumulative HI of 1.0. The selected remedy will be
protective of the environment of concern, namely the Thames River, that runs adjacent to the site by
monitoring for contaminant migration from the soil into the groundwater. The monitoring will be conducted
according to the Groundwater Monitoring Plan described in Section 10 of this Interim ROD. If the
groundwater COCs are shown to exceed site-specific Surface Water Protection Criteria, then additional
action would be taken, including expansion of the scope of monitoring to include surface water and
sediment sampling. If exceedances of Volatilization Criteria are detected, then additional action would
be taken including determining the need for additional remedial action.

11.2  COMPLIANCE WITH ARARS

The selected remedy will comply with all Federal and State of Connecticut ARARs. The chemical-specific,
location-specific, and action-specific ARARs and TBCs that have been analyzed for this remedial action
and the methods by which compliance will be attained are summarized in Tables 11-1, 11-2, and 11-3,
respectively.
-------
                                                  TABIiE 11-1

                                 ASSESSMENT OF CHEMICAL-SPECIFIC ARARs AND  TBCs
                          FOR ALTERNATIVE 2 - INSTITUTIONAL CONTROLS AND MONITORING
                                     DEFENSE REUTILIZATION AND MARKETING OFFICE
                                          NSB-NLON, GROTON, CONNECTICUT


     Requirement     Citation    Status         Synopsis of Requirements        Action to be Taken to
                                                                                    Attain ARAR
FEDERAL
                                   There are no federal chemical-specific-  ARARs
STATE OF CONNECTICUT
                                   There are no state chemical-specific ARARS
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                                                                           TABIiE 11-2
      Requirement
FEDERAL
Executive Order 11988
RE: Floodplain Management
       Citation

Executive Order
11988
Coastal Zone Management Act    16 USC Parts 1451
                               et seg.
Fish and Wildlife Coordination 16 USC 661 et seg:
Act                            40 CFR ° 6 302
STATE OF CONNECTICUT
Coastal Management Act
Tidal Wetlands
CT Endangered Species Act
CGS °° 22a-92 and
94
                               RCSA °° 22a-30-l
                               thru 17
CGS °° 26-303 thru
314
                                                       ASSESSMENT OF LOCATION-SPECIFIC ARARs AND TBCs
                                                    FOR ALTERNATIVE 2 - INSTITUTIONAL CONTROLS AND MONITORING
                                                       DEFENSE REUTILIZATION AND MARKETING OFFICE
                                                               NSB-NLON, GROTON, CONNECTICUT
      Status

Applicable
                       Applicable
                       Applicable
Applicable
                       Applicable
Applicable
          Synopsis of Reguirement

This order reguired Federal agencies,
wherever possible, to avoid or minimize
adverse impacts upon floodplains. Reguires
reduction of risk of flood loss, minimize the
impact of floods on human safety, health and
welfare, and to restore and preserve the
natural and beneficial values of the floodplains.
Reguires that any actions must be conducted
in a manner consistent with state approved
management programs.

Reguires action to be taken to protect fish and
wildlife from projects affecting streams or
rivers, Consultation with U.S. Fish & Wildlife
Service to develop measures to prevent and
mitigate loss.
Reguires projects within a state designated
coastal zone to minimize adverse impacts on
natural coastal resources.

Activities within or affecting tidal wetlands
regulated.
Regulates activities affecting state-listed
endangered or threatened species or their
critical habitat.
        Action to be Taken to Attain ARAR

    Monitoring well installation and groundwater
    monitoring activities within the 100-year floodplain
    will be carried out to minimize impacts to
    floodplain resources.
                                                                     This site is located in a state coastal flood zone
                                                                      (within the 100 year floodplain). Therefore,
                                                                     applicable state coastal zone management
                                                                     reguirements will be addressed.
                                                                     If monitoring wells are reguired to be installed in
                                                                     the river or its tidal zone, the U.S. Fish  & Wildlife
                                                                     Service will be consulted as to measures reguired
                                                                     to protect fish and wildlife resources.
    Monitoring well installation and groundwater
    monitoring activities within the 100-year coastal
    floodplain will be carried out to minimize impacts
    to coastal resources.
are If monitoring wells are reguired to be installed in
    the river or its tidal zone monitoring and
    maintenance activities will be implemented so as
    to not negatively impact tidal resources.
    The state-threatened Atlantic sturgeon inhabits the
    Thames River. If monitoring wells are reguired to
    be installed in the river or its tidal zone monitoring
    and maintenance activities will be implemented so
    as to not negatively impact the sturgeon or any of
    its critical habitat which may occur within the River.
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                                                                                               TABLE  11-3
                                                                    ASSESSMENT  OF ACTION-SPECIFIC ARARs AND TBCs
                                                                 FOR ALTERNATIVE 2  - INSTITUTIONAL CONTROLS AND  MONITORING
                                                                        DEFENSE  REUTILIZATION  AND  MARKETING OFFICE
                                                                             NSB-NLON, GROTON,  CONNECTICUT
                                        Citation
                                                                Status
                                                                                                                                          Action to be Taken to Attain ARAR
FEDERAL
Guidance on Remedial Actions  for  OSWER  Directive
Superfund Sites with PCB          9355.4-01
Contamination
STATE OF CONNECTICUT
Hazardous Waste Management:
Generator and Handler
Requirements
These sections establish standards  for
listing and identification of hazardous
waste, The standards of 40 CFR  260-261
are incorporated by reference.

This section establishes standards  for
groundwater monitoring and post-closure.
The standards of 40 CFR 264 are
incorporated by reference.
These regulations establish allowable
noise levels. Noise levels from
construction activities are exempt  from
these requirements.

The guidelines provide technical  and
administrative guidance for the
development, adoption, and
implementation of erosion and sediment
control program.
Connecticut's Water Quality Standards
establish specific numeric criteria,
designated uses, and anti-degradation
policies for groundwater and surface
water.
These regulations provide specific  numeric
cleanup criteria for a wide variety of
contaminants in soil, groundwater and soil
vapor. These criteria include volatilization
criteria, pollutant mobility criteria, direct
exposure criteria and surface water
protection criteria.
This guidance will be considered  in  evaluating
PCB issues as part of the remedial action  Low
levels of PCBs  (47.2 ppm or less) are  present
within soils at the site.

For any materials generated during monitoring
well installation, hazardous waste determinations
will be performed, and the wastes would  be
managed in accordance with requirements  of
these regulations, if necessary.
The remedy would comply with the  post-closure
requirements of this section through groundwater
monitoring and institutional controls  at the  Site.

Noise generated by installation of monitoring
wells will meet these regulations. This
alternative involves drilling  and monitoring
activities which are not anticipated to  generate
excessive noise.
Erosion and sediment control measures  would
be implemented during well installation.
                                                                                                                                       Although no groundwater plume has been
                                                                                                                                       identified at this site, the proposed groundwater
                                                                                                                                       monitoring will be conducted to determine if  any
                                                                                                                                       contaminants of concern are migrating offsite  at
                                                                                                                                       levels above CTDEP surface water protection or
                                                                                                                                       volatilization standards for GB groundwater.
                                                                                                                                       Maintenance of the cap and institutional controls
                                                                                                                                            will satisfy the Remediation Standards
                                                                                                                                                 Regulations for soil.
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11.3  COST EFFECTIVENESS

In the U.S. Navy's judgement, the selected remedy is cost effective,  (i.e., its overall protectiveness
justifies the cost). In selecting this remedy, the U.S. Navy analyzed the overall effectiveness of all
alternatives that were protective and complied with ARARs.  The No Action alternative is the least
expensive  (zero cost) alternative, but it would not be protective of human health, and there would be no
mechanism to monitor any impacts on the environment. Alternative 2 would be the least expensive of the
alternatives that address the exposure to contaminants and the potential for their migration in the
environment. Given the potential land use at the DRMO in the foreseeable future, the current industrial
land use is likely to continue and residential land use is very unlikely. As long as the base maintains
records of the contamination in the Master Plan and through any other applicable means, residential land
use would be prohibited and any transfer of property would be accompanied with deed restrictions. Also,
records of the contamination in the Master Plan at the site or through any other applicable means would
warn workers to take adeguate protective measures during intrusive activities. Under these circumstances,
the costs associated with excavation and offsite disposal of contaminated soil  (Alternative 3) or
excavation of contaminated soil with onsite treatment followed by offsite disposal (Alternative 4) would
not be justifiable.

Estimated total cost (30-year present worth) of the selected remedy: $ 708,000

11.4   UTILIZATION OF PERMANENT SOLUTIONS AND ALTERNATIVE TREATMENT OR RESOURCE RECOVERY TECHNOLOGIES TO
       THE MAXIMUM EXTENT PRACTICABLE

The selected remedy proposes maintenance of the existing asphalt and GCL cap to minimize exposure to
potential receptors within the foreseeable future at the DRMO under the management of the U.S. Navy. The
nature of the contaminants and potential risks at the DRMO do not warrant the need for an alternative
treatment or resource recovery technology. Among those alternatives that are protective of human health
and the environment and comply with ARARs, the U.S. Navy, with the U.S. EPA and CTDEP concurrence, has
determined that this selected remedy provides the best balance of trade-offs in terms of long-term
effectiveness and permanence; reduction in toxicity, mobility or volume through treatment; short-term
effectiveness; implementabillity; and cost while also considering the statutory preference for treatment
as a principal element and considering state and community acceptance.

11.5   PREFERENCE FOR TREATMENT AS A PRINCIPAL ELEMENT

The selected remedy does not treat the soil for reduction of toxicity, mobility or volume through
treatment as the principal element. The risks posed by the contaminants can be adeguately reduced by
minimizing exposure to potential receptors.

                            12.0   DOCUMENTATION OF NO  SIGNIFICANT CHANGES

The U.S. Navy (September 1997) released the PRAP for public comment on September 18,  1997. The PRAP
identified institutional Controls and Monitoring (Alternative 2) as the preferred alternative for soil
and groundwater remediation for the DRMO. Public comments have been considered by the U.S. Navy prior to
the selection of the preferred alternative. Upon review of these comments,  it was determined that no
significant changes to the remedy, as originally identified in the Proposed Plan were necessary.

                            13.0  STATE ROLE

The CTDEP, as part of the Federal Facilities Agreement (FFA) ,  has reviewed the various alternatives. The
CTDEP has also reviewed the Phase II RI  (B&R Environmental, March 1997) , FS (B&R Environmental, September
1997), and PRAP (U.S. Navy and B&R Environmental,  September 1997) to determine if the selected remedy is
in compliance with applicable or relevant and appropriate state environmental laws and regulations.

The CTDEP concurs with the selected remedy for the DRMO.  A copy of the letter of concurrence is presented
in Appendix D of this Interim ROD.
-------
                                              REFERENCES

Atlantic, August 1992. Phase I Remedial Investigation Naval Submarine Base - New London, Groton,
Connecticut. Atlantic Environmental Services, Inc., Colchester, Connecticut.

Atlantic, May 1993. Work Plan - Phase II Remedial Investigation - Installation Restoration Study - Naval
Submarine Base - New London, Groton, Connecticut. Atlantic Environmental Services, Inc., Colchester,
Connecticut.

Atlantic, 1994. Focused Feasibility Study, DRMO, Naval Submarine Base - New London, Groton, Connecticut.
Atlantic Environmental Services, Inc., Colchester, Connecticut.

B&R Environmental, March 1997. Phase II Remedial Investigation for Naval Submarine Base New London,
Groton, Connecticut, Brown & Root Environmental, King of Prussia, Pennsylvania.

B&R Environmental, July 1997. Feasibility Study for Area A Downstream/OBDA, Naval Submarine Base, New
London  (Draft Final). Brown & Root Environmental, King of Prussia, Pennsylvania, July 1997.

B&R Environmental, September 1997. Draft Final Feasibility Study, DRMO, Naval Submarine Base - New
London, Groton, Connecticut, Brown & Root Environmental, King of Prussia, Pennsylvania, September 1997.

B&R Environmental, October 1997. Groundwater Monitoring Plan for Defense Reutilization and Marketing
Office, Naval Submarine Base - New London, Groton, Connecticut. Brown & Root Environmental, King of
Prussia, Pennsylvania, October 1997.

CTDEP  (State of Connecticut Department of Environmental Protection), 1992. Water Quality Standards.
Connecticut Department of Environmental Protection, Bureau of Water Management, Planning and Standards,
Hartford, Connecticut.

CTDEP  (State of Connecticut Department of Environmental Protection), January 1996. Remediation Standard
Regulations. Bureau of Water Management, Permitting, Enforcement and Remediation Division, Hartford,
Connecticut.

Efroymson, R. A., G. W. Sutter II, B. E. Sample, and D. S. Jones, 1996. Preliminary remediation goals,
for ecological endpoints. ES/ER/TM-162/R1. Oak Ridge National Laboratory, Oak Ridge, Tennessee.

Envirodyne, 1982. Initial Assessment Study(IAS), Envirodyne Engineers, 1982.

Long, E. R. , D. D. MacDonald, S. L. Smith, et al., 1995. "Incidence of Adverse Biological Effects within
Ranges of Chemical Concentrations in Marine and Estuarine Sediments." Environmental Management, Vol. 19,
No. 1, pp. 81-97.

Naval Facilities Engineering Command, 1988. Master Plan for Naval Submarine Base, New London.

OHM  (OHM Remediation Services Corporation), September 1995. Final Report for Interim Remedial Action,
Site 6, Naval Submarine Base, New London, Groton, Connecticut. Hopkinton, Massachusetts.

ORNL, 1996. Screening Benchmarks for Ecological Risk Assessments: Version 1.6. Database prepared by the
Environmental Sciences and Health Sciences Research Divisions of Oak Ridge National Laboratories. Oak
Ridge, Tennessee. October 1996.

SCS  (Soil Conservation Service), 1983. Soil Survey of New London County Connecticut.

Suter and Mabrey, 1994. Toxicological Benchmarks for Screening of Potential Contaminants of Concern for
Effects on Aquatic Biota on Oak Ridge Reservation: 1994 Revision. Oak Ridge National Laboratory, Oak
Ridge, Tennessee. ES/ER/TM-96/R1.

USEPA  (United States Environmental Protection Agency), 1988. Guidance for Conducting Remedial
Investigations and Feasibility Studies Under CERCLA. EPA/540/G-89/004. Office of Emergency and Remedial
Response. Washington D.C. OSWER Directive 9355.3-01.

USEPA  (United States Environmental Protection Agency) Region I, June 1989. Draft Final Supplemental Risk
Assessment Guidance for the Superfund Program. EPA/901/5-89/001- Boston, MA.
-------
USEPA  (United States Environmental Protection Agency), December 1989. Risk Assessment Guidance for
Superfund - Volume I - Human Health Evaluation Manual  (Part A) - Interim Final, EPA/540/1-89/002. Office
of Emergency and Remedial Response.

USEPA  (United States Environmental Protection Agency), March 25, 1991. Risk Assessment Guidance for
Superfund - Volume I: Human Health Evaluation Manual - Supplemental Guidance - "Standard Default Exposure
Factors" - Interim Final. OSWER Directive 9285.6-03. Office of Emergency and Remedial Response.

USEPA  (United States Environmental Protection Agency), Region I, August 1994. Revised Interim Soil Lead
Guidance for CERCLA Sites and RCRA Corrective Action Facilities. Office of Solid Waste and Emergency
Response, Washington, D.C., Directive 9355.4-12.

USEPA  (United States Environmental Protection Agency), Region I, August 1995. Risk Updates, Number 3.
Waste Management Division, Boston, MA.

USEPA  (United States Environmental Protection Agency) Region IV, 1995. Supplemental Guidance to RAGS:
Region IV Bulletins - Ecological Screening Values. Ecological Risk Assessment Bulletin No. 2, November
1995. USEPA Region IV, Waste Management Division, Atlanta, Georgia.

USEPA  (United States Environmental Protection Agency), May 1996. Soil Screening Guidance Technical
Background Document. EPA/540/R-95/128. Office of Solid Waste and Emergency Response. Washington, D.C.
Directive 9355.4-17A.

USGS (United States Geological Survey), 1960. Surficial Geology of the Uncasville Quadrangle, U.S.
Geological Survey, Geologic Quadrangle Map GQ-138, by Richard Goldsmith, 1960.

USGS (United States Geological Survey), 1967. Bedrock Geology of the Uncasville Quadrangle, U.S.
Geological Survey Geologic Quadrangle Map GQ-576, by Richard Goldsmith, 1967. New London County,
Connecticut.

U.S. Navy and B&R Environmental, 1997. Proposed Remedial Action Plan, DRMO, Naval Submarine Base - New
London, Groton, Connecticut. Brown & Root Environmental, King of Prussia, Pennsylvania, September 1997.

Will, M. E. and G. W. Sutter II, 1994. Toxicological benchmarks for screening potential contaminants of
concern for effects on terrestrial plants: 1994 revision. ES/ER/TM-85/R1. Oak Ridge National Laboratory,
Oak Ridge, Tennessee.
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                                             APPENDIX A

                                       PUBLIC MEETING TRANSCRIPT

                              DEPARTMENT OF THE NAVY
                                               NORTHERN DIVISION
                                     NAVAL FACILITIES ENGINEERING COMMAND
                                             10 INDUSTRIAL HIGHWAY
                                                 MAIL STOP, #82
                                              LESTER, PA 19113-2090                    IN REPLY REFER TO

                                           MINUTES OF PUBLIC MEETING

                                 SITE 6 - DEFENSE REUTILIZATION AND MARKETING OFFICE


To:       NSB-NLON Public Meeting Attendees

From:     Mark Evans, Remedial Project Manager, Northern Division, Naval
          Facilities Engineering Command

Date:     7 November 1997

Subject:  Public Meeting Minutes - September 25, 1997
          Installation Restoration Program
          Naval Submarine Base - New London  (NSB-NLON)
          Groton, Connecticut

Attendees of the meeting

Andy Stackpole      NSB-NLON
Mark Evans          Navy
Greta Deirocini     Navy
Kymberlee Keckler   USEPA Boston
Mark Lewis          CTDEP
Corey Rich          Brown & Root
Kelly Smay          Brown & Root
Bart Pearson        Community
Noah Levine         Community
Gabe Stern           Community


Welcome and Introduction

Andy Stackpole opened the meeting at 6:30 p.m..

Mr. Stackpole introduced Kelly Smay from Brown & Root Environmental. Ms. Smay gave a presentation on the
DRMO Proposed Remedial Action Plan.
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                                                             APPENDIX B
                                                    CTDEP COMMENTS ON PROPOSED PLAN


                                                                            October 17,1997

Mr. Mark Evans
U.S. Department of the Navy
Northern Division, Naval Facilities Engineering Command, Code 1823
10 Industrial Way, Mail Stop 82
Lester, PA 19113-2090

Re: State Comments Regarding Proposed Plan for Site 6- Defense Reutilization and Marketing
    Office, Naval Submarine Base New London, Groton, Connecticut.

Dear Mr. Evans:

The Department has received and reviewed the Proposed Plan for the Defense Reutilization and Marketing
Office at the Naval Submarine Base New London in Groton. Proposed Plan was dated September 1997.

The preferred alternative being presented by the Navy in the Proposed Plan for the Defense Reutilization
and Marketing Office consists of five elements: 1) Continued maintenance of the existing cap 2) Land use
restrictions that would limit future development 3) Fencing and notices posted on the site perimeter, 4)
Long- term monitoring of contaminants in groundwater,  and if reguired, in surface water and sediment, and
5) Five-year reviews. The State supports the Proposed Plan as presented.

The State offers the following comments.

While the State believes the proposed remedy will satisfy the reguirements of the Remediation Standard
Regulations, we would prefer a more permanent remedy involving excavation of contaminated materials.
Polluted soil with substances exceeding the pollutant mobility and direct exposure criteria remains on
the site. The numeric direct exposure and pollutant mobility criteria, which are contained in Appendices
A and B, respectively, of the Regulations, do not apply to these soils, by virtue of the location of the
soils with respect to permanent structures, pavement,  and the water table at the site, as described
below.

Direct Exposure Criteria

The numeric direct exposure criteria (Appendix A to the Regulations) do not apply to soils that are
inaccessible, as defined in the Regulations. Inaccessible soil is defined in the Regulations as "polluted
soil which is  (A) more than four feet below the ground surface;  (B)  more than two feet below a paved
surface comprised of a  minimum of three inches of hiniminous concrete or concrete, which two feet may
include the depth of any material used as sub-base for the pavement; or  (C)(i)  beneath an existing
building or  (ii) beneath another existing permanent structure provided written notice that such structure
will be used to prevent human contact with such soil has been provided to the Commissioner." Section
22a-133k-2(b)(3) of the Regulations states in part that the direct exposure criteria do not apply to
"inaccessible soil at a release area provided that if such inaccessible soil is less than 15 feet below
the ground surface an environmental land use restriction is in effect with respect to the subject parcel
or to the portion of such parcel containing such release area, which environmental land use restriction
ensures that such soils will not be exposed as a result of excavation, demolition or other activities and
that any pavement which is necessary to render such soil inaccessible is maintained in good condition
unless and until such restriction is released in accordance with said section 22a-133g-l" (emphasis
added).

To fully comply with the intent of the Regulations, the remedy must include institutional controls, and
an inspection and maintenance program to ensure the continued integrity of the pavement that renders the
soil inaccessible.


Since all of the remaining contaminated soil is either beneath the cap  (a permanent structure designed to
prevent human contact) or beneath pavement, this exemption is applicable, provided a regular inspection
and maintenance program is put in place to ensure that the pavement and cap remain in good condition and
institutional controls prevent damage to the cap which will prevent human contact with soil contaminated
at levels exceeding the direct exposure criteria.
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Pollutant Mobility Criteria

Section 22a-133k-2(c) (1)  and (2)  of the Regulations specifies that in an area with a ground water
classification of GB,  the pollutant mobility criteria apply to "soil above the seasonal high water
table". Because the soil with contaminants at levels exceeding the pollutant mobility criteria found in
located below the seasonal high water table, the numeric pollutant mobility criteria found in Appendix B
to the Regulations do not apply.

Interim Remedy

The Navy, EPA, and the State previously agreed that this will be considered an interim status remedy
since compliance with all ARARs has not yet been demonstrated. Further action may be reguired depending
on the results of ground water monitoring. The Proposed Plan does not clearly identify the fact that this
is an interim remedy.  This fact should be clearly spelled out in the Record of Decision.

It should also be stated clearly that the purpose of the ground water monitoring program is to evaluate
the effectiveness of the interim remedy (cap) being selected and to provide data to determine whether
contaminants migrating from the site pose an unacceptable threats to human health and the environment. If
the monitoring program identifies such unacceptable threats, future actions to address those threats
should not be limited only to the additional monitoring described in the proposed plan. We anticipate
that the final Record of Decision for the DRMO will depend heavily on the results of ground monitoring
performed under the interim Record of Decision, and upon ground water investigations performed under the
base wide ground water Operable Unit.

If you have any guestions regarding this letter, please contract me at (860)424-3768.

                                               Sincerely,
                                               
                                               Mark R. Lewis
                                               Senior Environmental Analyst
                                               Federal Remediation Program
                                               Permitting, Enforcement & Remediation Division
                                               Bureau of Water Management

cc:  Kymberlee Keckler,  US EPA New England, Federal Facilities Section
     Andy Stackpole, NSBNL Environmental Department
     Jack Looney, CT Attorney General's Office
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                                                  APPENDIX C

                                            RESPONSIVENESS SUMMARY

The Navy published a notice and brief analysis of the Proposed Plan in the New London Day on September
18, 1997 and made the plan and the administrative record available to the public at the Groton Public
Library, the Bill Library and the Naval Submarine Base Library.

On September 25, 1997, the Navy held an informational meeting to discuss and present the Proposed Plan.
Also, on September 25, 1997 the Navy held a public hearing to discuss the Proposed Plan and to accept any
oral comments. A transcript of this meeting is included in Appendix A. From September 18, 1997 to October
18, 1997 the Navy held a 30-day public comment period to accept public comment on the Proposed Plan.

SUMMARY OF COMMENTS RECEIVED DURING THE PUBLIC COMMENT PERIOD

Oral comments received during the public hearing held on September 25, 1997 are provided in Appendix A.
No written comments were received during the public comment period other than a letter dated October 17,
1997 from the Connecticut Department of Environmental Protection (CTDEP) expressing their support of the
Proposed Plan as presented.
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                                                    APPENDIX D

                                             DECLARATION OF CONCURRENCE


The State of Connecticut has concurred with the Proposed Remedial Action Plan as shown in Appendix B. The
changes to this ROD as requested by the State have been incorporated in this ROD. The U.S. EPA has
concurred with the selected remedial action as described in the Declaration of this ROD.


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