Superfund Record of Decision Naval Surface Warfare Dahlgren Site 9 Disposal Burn Area Dahlgren VA


                                   EPA/ROD/R03-98/069
                                   1998
EPA Superfund
     Record of Decision:
     NAVAL SURFACE WARFARE CENTER - DAHLGREN
     EPA ID: VA7170024684
     OU03
     DAHLGREN, VA
     09/30/1998

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EPA 541-R98-069

                             SITE 9 DISPOSAL/BURN AREA

                            NAVAL SURFACE WARFARE CENTER
                                   DAHLGREN SITE
                                 DAHLGREN, VIRGINIA
                                 RECORD OF DECISION

                                    SEPTEMBER 1998

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                               TABLE OF CONTENTS

SECTION                                                                                   PAGE

1.0   THE DECLARATION	1-1
      1.1   SITE NAME AND LOCATION	1-1
      1.2   STATEMENT OF BASIS AND PURPOSE	1-1
      1. 3   DESCRIPTION OF THE SELECTED REMEDY	1-1
      1. 4   STATUTORY DETERMINATIONS	1-3

2 . 0   DECISION SUMMARY	2-1
      2.1   SITE NAME,  LOCATION,  AND DESCRIPTION	2-1
      2 . 2   SITE HISTORY AND ENFORCEMENT ACTIVITIES	2-1
      2.2.1 History of Site Activities	2-1
      2.2.2 Previous Investigations	2-6
      2.2.3 Enforcement Actions	2-7
      2.2.4 Highlights of Community Participation	2-7
      2 . 3   SCOPE AND ROLE OF RESPONSE ACTION SITE 9	2-7
      2 . 4   SUMMARY OF SITE CHARACTERISTICS	2-7
      2.4.1 Sources of Contamination	2-8
      2.4.2 Description of Contamination	2-8
      2.4.3 Contaminant Migration	2-13
      2 . 5   SUMMARY OF SITE RISKS 	2-13
      2.5.1 Human Health Risks	2-14
      2.5.2 Environmental Evaluation	2-16
      2.5.3 Development of Preliminary Remediation Goals	2-18
      2 . 6   DESCRIPTION OF ALTERNATIVES	2-18
      2 . 7   SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES	2-26
      2.7.1 Threshold Criteria	2-26
      2.7.2 Primary Balancing Criteria	2-27
      2.7.3 Modifying Criteria	2-29
      2.8   THE SELECTED REMEDY	2-29
      2.8.1 Performance Standards	2-31
      2 . 9   STATUTORY DETERMINATIONS	2-33
      2.9.1 Protection of Human Health and the Environment	2-34
      2.9.2 Compliance with ARARs	2-34
      2.9.3 Cost-Effectiveness	2-35
      2.9.4 Utilization of Permanent Solutions and Alternative Treatment Technologies
            or Resource Recovery Technologies to the Maximum Extent
            Practicable	2-35
      2.9.5 Preference for Treatment as a Principal Element	2-35
      2.9.6 Documentation of Significant Changes	2-35

  3.0 RESPONSIVENESS SUMMARY	3-1
      3 .1   BACKGROUND ON COMMUNITY INVOLVEMENT	3-1

  APPENDICES

      A    Commonwealth of Virginia Concurrence with the Selected Remedy
      B    Summary of Informal Comments
      C    Applicable or Relevant and Appropriate Reguirements

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                                             LIST OF FIGURES





NUMBER                                                                                   PAGE





2-1       Location Map	2-2





2-2       Site Location Map	2-3





2-3       Site Map	2-4





2-4       Total Magnetic Field Contour Map Site 9	2-5





2-5       Sample Location Map	2-9





2-6       Selected Alternative (Alternative 3 With Options A,  B2 North and 83 South)	2-30











                                             LIST OF TABLES





2-1       Maximum Detected Values for COCs in All Media	2-10





2-2       Human Health Chemicals of Concern and Exposure Point Concentrations	2-15





2-3       Summary of Sediment PRGs	2-19

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1.0 THE DECLARATION

1.1 SITE NAME AND LOCATION

Site 9 Disposal/Burn Area
Naval Surface Warfare Center
Dahlgren, Virginia

1.2 STATEMENT OF BASIS AND PURPOSE

This decision document presents the selected remedial action for Site 9 Disposal/Burn Area and Site 58
Building 1350 Landfill (SWMU 134) at the Naval Surface Warfare Center, Dahlgren Site (NSWCDL) Dahlgren,
Virginia. Site 58 is a physical extension of the Site 9 Landfill and will be remediated pursurant to this
Record of Decision, Herein, Site 58 is addressed when Site 9 is referenced. This document focuses on remedial
decisions for Site 9 at the NSWCDL and the term "site" in this document refers to Site 9. This determination
has been made in accordance with the Comprehensive Environmental Response, Compensation, and Liability Act of
1980 (CERCLA) , as amended by Superfund Amendments and Reauthorization Act of 1986 (SARA), and to the extent
practicable, the National Oil and Hazardous Substances Pollution Contingency Plan (NCP). This decision is
based on the administrative record for this site.

The Commonwealth of Virginia concurs with the selected remedy (see Appendix A).

ASSESSMENT OF THE SITE

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

1.3 DESCRIPTION OF THE SELECTED REMEDY

The Navy will manage the remediation of the Disposal/Burn Area as a single remedial action. The remedial
action selected in this ROD addresses contamination associated with Site 9 Disposal/Burn Area contents,
surface soils, subsurface soils, marsh sediments, and groundwater. Possible contaminated surface water and
sediments in Gambo Creek near Site 9 will undergo further evaluation as part of the Gambo Creek Ecological
Assessment and a separate ROD will be issued for Gambo Creek. Any remedial action selected in the future for
Gambo Creek will be consistent with this ROD.

The selected remedy for Site 9 is to utilize capping to address both soils and sediments, and to provide
institutional controls, as well as groundwater, surface water, and sediment monitoring.

The major components of the selected remedy are:

Landfill

Wastes in the southern area, estimated at approximately 250 cubic yards (cy), shall be excavated until bare
soil is exposed. These wastes and surface soils shall be consolidated and stabilized on the landfill portion
of the site. Consolidation may include size separation, crushing and grinding, and dewatering. The landfill,
estimated to be approximately 5.0 acres upon completion of closure activities, will be covered with a
multilayer cap meeting the reguirements of the Virginia Solid Waste Management Regulations, 9 VAC 20-80-210
(Remedial Reguirements) and 9 VAC 20-80-250 (sanitary landfill).

The landfill cap will substantially limit precipitation and runoff from entering the consolidated fill
material. Based on preliminary modeling conducted to date by the Navy, it is anticipated that the multilayer
cap will need to exceed the minimum reguirements of a 9 VAC 20-80-250 (sanitary landfill) to be protective of
receptors in Gambo Creek, The final cap components will be determined during the final design for Site 9. The
multilayer cap will be revegetated, and the closure completed consistent with 9 VAC 20-80-250 (sanitary
landfill) closure reguirements. The closure will include provisions for the installation of structures at the
toe of the landfill and elsewhere to provide erosion and sediment control measures, including protection from
surges in the water surface of Gambo Creek due to major regional storm events such as hurricanes. The current
boundary of the landfill will be pulled back from Gambo Creek so that the waste associated with the cap will
be a minimum of 100 feet from Gambo Creek.

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An impermeable slurry wall will be installed on the hydraulically upgradient (west) side of the landfill,
which shall effectively redirect groundwater movement around the capped landfill. The slurry wall will be
installed to a depth below grade and key into the clay confining unit beneath the site.

Marsh

Surface debris will be removed (excavated) from the marshy area of the site and consolidated and stabilized
on the landfill. It is estimated that approximately 260 cy of surface debris will be removed from the marsh.
Vegetation in the marshy area of the site will be out back. If necessary, to support construction in the
marsh, a geogrid layer will be anchored over the entire 2.4 acre area. The placement of the geogrid over
the marsh would improve the lateral stability of the soils in the area and allow construction eguipment to
complete the placement of the cap over the waste disposal areas in the marsh. The marsh cap will meet the
Virginia Sanitary landfill cap minimum thickness reguirement of 2 feet The marsh cap would provide sound
engineering controls per 9 VAC 20-80-250 to help control groundwater which intrudes the site by being
constructed to an elevation (estimated to be 4 feet mean sea level (mnsl) which will preclude the
possibility of groundwater migrating upward through the waste and reaching, the cap surface. The marsh cap
will address 9 VAC 20-80-250 reguirements to control releases or otherwise reduce site risks by: 1)
cutting off potential contact exposure to wastes in the marsh; 2) enhancing evaporation of contaminated
groundwater which flows within the marsh cap; and 3) providing additional sorbing to soils through which
the contaminated groundwater must pass before being discharged to the marsh. Upon completion of the placement
of the marsh cap, appropriate vegetation will be re-introduced and maintained. Installation of the marsh
cap will raise the elevation of the marsh and will likely turn the capped area into an upland environment.
The wetland loss will be mitigated elsewhere at the NSWCDL facility.

Where Gambo Creek is within 100 feet of the waste/fill material in the marsh, on the northeastern portion
of the site, the shoreline of Gambo Creek will be protected against erosion to provide a benefit eguivalent
to moving waste 100 feet away from Gambo, Creek. This action shall address Commonwealth of Virginia
regulation 9 VAC 20-80-250. It is conservatively assumed that the shoreline protection will consist of spot
regrading of the Gambo Creek stream bank, placement of a geotextile, layer, and placement of riprap to the
same elevation as the existing stream bank. It is anticipated that 560 linear feet of shoreline protection
will be reguired. Portions of Gambo Creek on the southeastern portion of the site will be filled, and
established as wetlands.

While groundwater, surface water, and sediments shall be addressed through the above source controls,
other steps will also be taken to minimize risks. Institutional controls, including limiting site access
through gates and limiting future land use, will be implemented to eliminate or reduce pathways of exposure
to contaminants at the site. Monitoring will also be instituted to determine if contaminants are migrating at
significant rates and concentrations.

Institutional controls will be implemented to limit future site land use. For Site 9, an institutional
control plan will be developed as a part of remedial action design and include: access controls, signs along
the perimeter of the site, restrictions on shallow groundwater use for drinking water, description of land
use controls in the base master plan, periodic inspection, monitoring, and re-evaluation of land use
controls, annual certification that institutional controls are in place, notification to the U.S. EPA and
state regulators whenever the Navy anticipates any major changes in land use restrictions, public notice, and
a deed notification.

The Navy shall institute the following institutional controls within 90 days of installation of the
capping system: a real property description notation, Base Master Plan notations, and limited site access.
The Base Master Plan shall note the area as one in which residential development cannot occur, shallow
groundwater cannot be used, and site access shall be limited. A notation shall be filed in the real property
file maintained at Engineering Field Activity, Chesapeake (EFA Ches) (US Navy) for this site indicating the
extent of the area and the fact that solid wastes are present. The institutional controls shall also include
the following: within 90 days after completion of the remedy, the Navy shall produce a survey plat prepared
by a professional land surveyor registered by the Commonwealth of Virginia, indicating the location and
dimensions of the disposal area and the extent of groundwater contamination. Monitoring well locations shall
be included and identified on the survey plat. The plat shall contain a note, prominently displayed, which
states the owner's future obligation to restrict disturbance (excavation or construction) of the property. In
addition, post-closure use of the property shall prohibit residential use and access or use of groundwater
underlying the property for any purpose except monitoring and the function of the monitoring systems shall
not be disturbed. When landfill closure is complete, the owner of the property shall submit the survey plat
to the local recording authority, and shall record a notation with the deed (or some other instrument which
is normally examined during title search at the local land recording authority) notifying any potential

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purchaser of the property that the land has been used to manage solid waste and the integrity of the cover
system or the function of the monitoring system may not be disturbed.

The Navy shall institute groundwater monitoring to ensure remedial action objectives are being maintained.
The freguency of analysis and the length of time for monitoring shall be developed in the Operation and
Maintenance Plan. The Navy shall also monitor the surface waters and sediments at Site 9. The freguency of
analysis and the length of time for monitoring shall be specified in the Operation and Maintenance Plan.

Implementation of the selected remedy will address the principal threats at the site by reducing the
potential risk to human health and the environment associated with the surface soils, subsurface soils,
sediment, and groundwater.

1.4 STATUTORY DETERMINATIONS

The selected remedy for Site 9 is protective of human health and the environment, complies with Federal and
State reguirements that are legally applicable or relevant and appropriate to this action, and is
cost-effective.

The selected remedy for Site 9 addresses the remediation of surface soils, subsurface soils, sediment, and
groundwater contamination at Site 9. The selected remedy will provide for the long-term containment of
contamination in these media beneath the site. The installation of a capping system will reduce direct
contact and ingestion threats, and reduce risks to ecological receptors from contaminated media by containing
contaminants from these media.

The selected remedy for Site 9 will be constructed to meet all applicable or relevant and appropriate
reguirements (ARARs) whether chemical-, action-, or location-specific. No waivers of any ARARs are reguested.
Capping is a permanent solution and is an appropriate remedy for the contamination at the site. Capping is
standard technology and its application at Site 9 is considered technically superior to other alternatives.

This remedy utilizes permanent solutions and alternative treatment (or resource recovery) technologies to the
maximum extent practicable for this operable unit. However, because treatment of the principal threats of the
site was not found to be practicable, this remedy does not satisfy the statutory preference for treatment as
a principal element.

Because this remedy will result in hazardous substances remaining on-site above health-based levels, a review
will be conducted within five years after commencement of the remedial action to ensure that the remedy
provides adeguate protection of human health and the environment.

2.0 DECISION SUMMARY

2.1 SITE NAME, LOCATION, AND DESCRIPTION

This ROD is issued to describe the Department of the Navy's (NAVY) selected remedial action for Site 9,
Disposal/Burn Area, at the NSWCDL, Dahlgren, Virginia (Figure 2-1). Site 9 is one of several Installation
Restoration (IR) sites (Figure 2-2) located at the NSWCDL facility.

The Disposal/Burn Area is an inactive landfill, approximately 5 acres in size, located off Caskey Road in the
central portion of the Mainside, adjacent to the southwestern shore of Gambo Creek and associated marsh area.
Gambo Creek and its associated marsh area border approximately two-thirds of the site to the east and north
(Figure 2-3). The majority of the remaining area surrounding Site 9 is wooded. A fenced magazine (Building
954) is located approximately 80 feet west of the northwestern boundary of Site 9. An active dog kennel
(Building 1312) is located approximately 100 feet south of the site. A paved road provides access to a gated
entrance from the southwest. Historic information indicates that the facility used this area as a sanitary
landfill from the early 1940s until 1971. However, dumping and occasional burial of construction debris and
tree stumps continued until 1984.

During the Remedial Investigation (RI), a magnetic field survey was conducted to delineate the extent of the
landfill (Figure 24). The landfill fans out north and east toward Gambo Creek and the marsh. One to two feet
of soil covers the top of the landfill, although debris is visible along the slopes leading to Gambo Creek
and the marsh. The exact depth of the fill is between 5 and 15 feet in the landfill and in the marsh
respectively, based on test pit excavations. The site lies on a nearly level parcel of land, with elevations

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across the site ranging from over 10 feet above mean sea-level (msl) in the center of the landfill to
approximately 2 feet above msl at the base of the landfill slope in the marsh area. It is assumed that
landfilling operations at Site 9 have altered the original topography. There are currently no structures on
the site. The majority of the site is vegetated and several features are visible on the land surFace. Obvious
features include a large pile of fill soil in the northeast comer, several slabs of steel-reinforced concrete
adjacent to the pile of soil, and a pile of cut trees in the center of the site. Surface drainage
predominately flows in a southerly or southeasterly direction toward the large marsh area adjacent to Gambo
Creek. An east-west drainage ditch runs along the southern portion of the landfill surface and through a
culvert prior to entering Gambo Creek. Gambo Creek flows south-southeast and empties into Upper Machodoc
Creek.

Site 58, also called the Building 1350 Landfill (Solid Waste Management Unit (SWMU) 134), is an extension
of Site 9 to the southeast and will be remediated with Site 9. This site, approximately 0.7 acre in size, is
adjacent to Kennel Road, and extends to Gambo Creek. This landfill was in use during a later period than Site
9. The following items were observed at Site 58: 55-gallon drums of roofing tar, 5-gallon and 1-gallon empty
paint cans, railroad ties, fires, roofing shingles, and miscellaneous steel and concrete debris. The area has
a moderate to heavy vegetative cover. Surface water flows directly into Gambo Creek, or into a drainage ditch
on the south end of the site, and subseguently into Gambo Creek.

2.2 SITE HISTORY AND ENFORCEMENT ACTIVITIES

2.2.1 History of Site Activities

The history of Site 9 has been developed primarily from an Environmental Photographic Interpretation Center
(EPIC) analysis of aerial photographs prepared by U.S. EPA in 1992. A summary of the site history is
discussed in the following paragraphs.

Documentation of activity at Site 9 began in 1937. Evidence of waste disposal in the northern and eastern
portions of the site and along the edge of the marsh adjacent to the creek was observed in the 1943 imagery.
Continued site expansion and ongoing disposal activity was noted through the 1990 imagery. Evidence of liguid
discharges emanating from the material lining the perimeter of the fill area and flowing south, and emanating
from the center of the fill area and flowing north, was observed in the 1953 and 1958 imagery, respectively.

By 1960, filling operations had expanded across the marsh into Gambo Creek, and runoff had stained the
surface of the fill area as it flowed toward both the creek and a western channelized drainage path. Two
small trenches and a new fill area were observed west of the drainage path. A wide trench, spanning the
length of the new fill area and leading to the channelized drainage path was observed in the 1962 imagery.
Evidence of liguid discharge, flowing from the original fill area to Gambo Creek, was observed in the 1967
imagery, and filling operations had narrowed the width of the main channel. By 1969, filling operations had
completely altered the course of Gambo Creek. This change was apparently the result of a large increase in
the amount of material disposed on the east side of the new fill area. A smoke plume from a nearby classified
paper incinerator was also visible east of the new fill area in the 1969 imagery, and two horizontal storage
tanks (containing roofing tar) were observed in the southern portion of the site.

The 1974 imagery showed that the (original) fill area, which extended north into the marsh, was revegetating
while dumping continued in the southern portion of the site. By 1981 enough fill material had been added to
the north and east sections of the southern fill area to extend over most of the original fill area. Large
guantities of debris were observed along the fill face and in the center of the site in the 1983 and 1985
imagery. The 1990 imagery indicated most of the fill areas were revegetating. Drainage continued to flow east
from the northern portion of the site, into Gambo Creek. Evidence of crates and containers was noted to the
north, and a large area of debris was evident in the center of the landfill.

2.2.2 Previous Investigations

The first investigation at Site 9 was the Initial Assessment Study (IAS) in 1981. The IAS, involved an
on-site records review, site visit, and personnel interviews. The IAS determined that given the unknown
nature and extent of the waste disposed at Site 9, and the direct hydraulic connection of the site to Gambo
Creek and adjacent marsh areas, a Confirmation Study should be performed to determine the types and

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quantities of matadals escaping from the landfill, as well as the potential for impacts on the surrounding
marsh environment and Gambo Creek.

Additionally, the IAS indicated that friable asbestos insulation was disposed along with ordinary refuse, and
waste ash from heating coal used by NSWCDL until the mid-1940s was most likely disposed at the
Disposal/Burn Area. Subsequent Investigations did not find asbestos in the landfill, and based upon available
information it is anticipated that asbestos would onsite less than one percent of the waste mass at Site 9.
Therefore, Site 9 is not subject to closure requirements applicable to asbestos-containing materials. NSWCDL
converted from coal to oil in the mid-1940s. Historical records indicate that oil and grease from traps
connected with vehicle washing operations at Building 1329 were hauled to Site 9 for disposal.

The Confirmation Study at Site 9 was conducted in 1983 and 1984. As part of the study, four groundwater
monitoring wells were installed (upgradient well GW9-1 and downgradient wells GW9-2, GW9-3, and GW-94) to
monitor groundwater quality in the shallow aquifer. These wells were sampled in November 1983, December
1983, and November 1984. Four leachate samples were also collected from the standing water at the base of the
landfill face. Groundwater and leachate samples were analyzed for the following: total organic carbon (TOG),
total organic halides (TOX), phenol, iron, manganese, sodium, chloride, and sulfate.

Based on the field investigation and analytical results of the Confirmation Study at Site 9, R was concluded
that the elevated phenol concentrations (0.07 mg/kg) deteded in the groundwater of the Disposal/Burn Area did
not meet Virginia groundwater quality standards, and that TOG (5,100 mg/L) and TOX (280 Ig/L) concentrations
were elevated above typical background levels. Recommendations included the implementation of a
comprehensive groundwater monitoring program.

2.2.3 Enforcement Actions

No enforcement actions have been taken at Site 9. The Navy has owned this property since the early 1900's and
is identified as the responsible party.

2.2.4 Highlight of Community Participation

In accordance with Section 113 and 117 of CERCLA, the Navy provided a public comment period from August 20,
1998 through September 18, 1998 for the proposed remedial action described in the Feasibility Study and the
Proposed Plan for Site 9.

These documents were available to the public in the Administrative Record and information repositories
maintained at the Smoot Memorial Library, King George, Virginia; the NSWCDL General Library, Dahlgren,
Virginia; and the NSWCDL Public Record Room, Dahlgren, Virginia. Public notice was provided in The Freelance
Star newspaper on August 20, 1998 and The Journal newspaper on August 19, 1998 and a public meeting was held
in the King George Courthouse on August 27, 1998. No written comments were received during the comment
period, and the comments and responses provided during the public meeting are presented in Appendix B.

2.3 SCOPE AND ROLE OF RESPONSE ACTION SITE 9

Past disposal operations at the site have contaminated soil, groundwater, and sediments. The Navy has
decided to manage the remediation of the site as a single unit. The remedial actions identified in this ROD
address contamination associated with Site 9, Disposal/Burn Area, as identified in the Draft Final RI
Report, the Addendum RI Report, the Feasibility Study (FS) Report, and the Addendum FS Report for Site 9.
Several alternatives for response actions for contaminated media are identified in Section 2.6. The
rationale for selecting one of those alternatives as the remedy for this site is described in Section 2.7.

The selected remedy is to cap landfill soils and marsh sediments. Contaminated surface and subsurface
soils at Site 58 would be excavated and consolidated beneath the landfill cap, and shoreline protection will
be utilized to achieve 100 toot setback requirements established by the Commonwealth of Virginia. The
selected remedy will reduce the potential risk to ecological receptors associated with pesticides and
metals present in surface soils, metals present in subsurface soils and groundwater migrating to Gambo
Creek, and metals, pesticides/polychlorinated blphenyls (PCBs), and semivolatile compounds (SVOCs) present in
surface sediments in the marsh. The selected remedy will reduce the potential risk to human receptors from
metals in groundwater migrating to Gambo Creek.

This ROD is consistent with long-term remedial goals for Site 9. The selected remedy will reduce the
principal threat to ecological receptors in Gambo Creek from soil, groundwater, and sediment contamination.

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    2.4  SUMMARY OF SITE CHARACTERISTICS

The RI at Site 9 was completed in phases. Geophysical investigations were initiated in 1993. Sampling
activities, consisting of soil sampling, surface water and sediment sampling, and the installation and
sampling of groundwater monitoring wells, were completed in 1994. Additional RI sampling, consisting of
additional surface and subsurface soil sampling and groundwater monitoring activities was completed in
1996. The results of the RI are summarized below.

    2.4.1    Sources of Contamination

Geophysical and hydrogeologic investigations at Site 9 were conducted to identify disturbed areas and
buried metallic objects, and to investigate the extent of the landfill. The results of the survey indicated
the presence of metallic objects. These investigations along with test pits verified the extent of the
landfill. In addition, test pits verified the extent of buried wastes present in the marsh adjacent to the
landfill. Based on groundwater, subsurface soil, and sediment sampling results, the sources of contamination
are the wastes present in the landfill and marsh.

    2.4.2     Description of Contamination

Soil, groundwater, surface water, and sediment samples were collected and analyzed to determine the    nature
and extent of contamination at Site 9 (Figure 2-5).  The contamination concerns at Site 9 are    associated
with the landfill. Surface soil, subsurface soil, groundwater, surface water, and sediments have been
impacted by the waste disposal activities that occurred there. The primary contaminants of concern  (COG) are
SVOCs  (polynuclear aromatic hydrocarbons [PAH] compounds),  pesticides, and various metals (Table 2-1). The
results of the sampling and analyse are presented below,

    Surface and Subsurface Soils

Low-level  (PAH) contamination  (0.026 to 0.12 mg/kg)  and pesticides  (0.0038 to 0.72 mg/kg) were identified in
surface soils. Elevated levels of several metals, including arsenic (5.3 mg/kg), copper  (2,250 mg/kg), lead
(128 mg/kg), mercury  (0.93 mg/kg), and zinc (473 mg/kg) were also detected. In the subsurface soils,
high-level PAH contamination (21 to 150 mg/kg) and inorganic contamination were identified,  with lead  (3,250
mg/kg) detected at the highest concentration.  Low-level pesticides  (0.0012 to 2.7 mg/kg) were also detected
in the subsurface soils, The PAH and inorganic contamination appear to be related to the landfill itself
whereas the pesticide contamination appears to be related to wide spread spraying across the base.

    Groundwater

Low-level PAH  (0.5 to 53 Ig/L)  and pesticide  (0.0129 to 0.2 Ig/L) contamination was identified in
groundwater. Low level SVOC contamination (0.6 to 3 Ig/L) was also detected from seep samples. Inorganic
contaminants, such as barium (3,950 Ig/L),  lead  (1,370 Ig/L), and zinc (2,940 Ig/L) were detected at high
levels in groundwater. Inorganic contaminants in seepage were detected at only low to moderate levels with
respect to background.

    Surface Water and Sediment

No significant volatile organic compound (VOC),  SVOC, or pesticide/PCB contamination was identified in
surface water samples collected from Site 9. Inorganics; detected were at levels similar to or below
background in the majority of surface water samples. Two surface water sample locations, however,  exhibited
elevated concentrations of inorganics, including lead  (252 Ig/L)  and mercury  (I lag/Q. Sediment   sample
results indicate low level VOC contamination  (0.005 mg/kg to 0.58 mg/kg)  and SVOC contamination     (0.025
mg/kg to 1.0 mg/kg). Pesticides were detected at moderately elevated concentrations (0.0034 to 9.1   mg/kg).
Inorganic concentrations for most constituents in sediment were within or only slightly elevated   above
background levels. Copper (5,390 mg/kg)  and lead  (743 mg/kg)  were well above background levels.

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                                   TABLE 2-1

               MAXIMUM DETECTED VALUES FOR COCs  IN ALL MEDIA
                         SITE 9: DISPOSAL/BURN AREA
              NAVAL SURFACE WARFARE CENTER, DAHLGREN, VIRGINIA
      Chemical                      Maximum
     of Concern                 Detected Value

                  SURFACE SOILS

Organics  (mg/kg)
Benzo(a)anthracene                    0.08
Benzo(a)pyrene                        0.081
Benzo(b)flouranthene                  0.12
Benzo(k)flouranthene                  0.15
Indeno(l,2,3-cd)pyrene                0.056
Phenols                               0.006
4,4'-DDE                              0.420
4,4'-DDT                              0.720
Inorganics (mg/kg)
Aluminum                              9,150
Arsenic                               5.3
Chromium                              16.5
Copper                                2,250
Lead                                  128
Iron                                  16,700
Mercury                               0.93
Vanadium                              29.8
Zinc                                  473
               SUBSURFACE SOILS
Organics  (mg/kg)
Benzo(a)anthracene                    150
Benzo(a)pyrene                        110
Benzo(b)fluoranthene                  54
Benzo(k)flouranthene                  140
Dibenzo(a,h)anthracene                21
Indeno(1,2,3-cd)pyrene                44
Inorganics (mg/g)
Arsenic                               13.6
Lead                                  3,250
Iron                                186,000
                   SEDIMENTS
Organics  (mg/kg)
Acetone                               0.58

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TABLE 2-1
MAXIMUM DETECTED VALUES FOR  COCs  IN ALL MEDIA
SITE 9: DISPOSAL/BURN AREA
NAVAL SURFACE WARFARE CENTER,  DAHLGREN,  VIRGINIA
PAGE 2 OF 3
Chemical
of Concern
Alpha chlordane
Carbon Disulfide
4,4' -ODD
Gamma chlordane
Kel thane
Inorganics (mg/kg)
Aluminum
Arsenic
Beryllium
Cadmium
Chromium
Copper
Iron
Lead
Mercury
Silver
Vanadium
Zinc
SURFACE WATER
Organics (Ig/L)
Carbon Disulfide
Heptachlor
Fl ouranthene
Inorganics (Ig/L)
Aluminum
Arsenic
Beryllium
Cadmium
Chromium
Copper
Cobalt
Iron
Lead
Manganese
Mercury
Nickel
Silver
Zinc
Maximum
Detected Value
0.022
0.007
9.1
0.012
0.031

24,100
17.1
1.5
6.2
43.6
5,390
36,300
743
1.2
32.3
55
1,600


4.0
0.094
0.5

15,200
16
1.5
2
23.2
124
20.4
46,300
252
1,910
1
33.9
4.1
368

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TABLE 2-1
MAXIMUM DETECTED VALUES FOR COCs IN ALL MEDIA
SITE 9: DISPOSAL/BURN AREA
NAVAL SURFACE WARFARE CENTER, DAHLGREN, VIRGINIA
PAGE 3 OF 3

         Chemical                Maximum
        of Concern           Detected Value
                GROUNDWATER(1)

Organics (Ig/L)
Heptachlor                       0.105
Phenanthrene                      44
Inorganics (Ig/L)
Arsenic                           13.2
Barium                            3,950
Copper                             583
Cyanide                            4 .3
Lead                              1,370
Manganese                         1,350
Nickel                            62.7
Zinc                              2,940
1  Groundwater COCs were developed based on the expected industrial use  scenario

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2.4.3 Contaminant Migration

The presence of both organic and inorganic contaminants in the groundwater and seeps, as well as in
surface water and sediment samples, indicates the likelihood that migration has occurred into the
surrounding environmental media at this site. The major contaminants noted in the surface water and
sediment samples were PAH compounds, pesticides, and metals. Volatile organics were not determined to be
prevalent.

Given the distribution of compounds in groundwater, surface water, and sediment samples, two primary
release mechanisms can be identified. The first is migration as a solute from the buried waste in the
landfill and marsh, and the second is the migration via overland runoff/surface water flow.

Of the organic chemicals detected in groundwater monitoring wells at Site 9, only the volatile organic
compounds benzene, ethylbenzene, and xylenes, which were detected at low concentrations, are relatively
highly soluble. Because of these high solubilities, these compounds are susceptible to transport via
dissolution by infiltrating precipitation or fluctuations in the watertable.

The PAH compounds, detected primarily in only one well, are not as likely to be transported in a soluble
phase, given their relatively lower solubilities and vapor pressures. The lower molecular weight PAHs (e.g.,
acenaphthene, anthracene, fluorene, phenanthrene) may volatilize from surface waters, while the higher
molecular weight PAHs (e.g., benzo[alpyrene, benzo[a]anthracene, chrysene) are less likely to volatilize.
PAHs in water are much more likely to bind to soil and be transported via mass transport mechanisms.

The source of elevated metals at Site 9 is most likely due to the disposal of metallic waste in both the
landfill area and the marsh adjacent to the landfill. The release of relatively insoluble contaminants via
groundwater transport and overland transport is also a significant release mechanism acting at this site.
When the landfill was in operation, bare soil and surface-deposited wastes would have been subject to erosion
during precipitation. Soil containing contaminants would have been transported downslope via rainwater flow
toward Gambo Creek or the marsh, where flow would slow and sediments would be deposited. This material, along
with the buried waste in the landfill and marsh acts as a secondary source of contamination, evidenced by the
presence of insoluble contaminants in unfiltered water samples collected from these areas. Samples collected
from areas farther from the primary source contained much lower concentrations of these contaminants.

Metals are highly persistent environmental contaminants. The major fate mechanisms for metals are
adsorption to the soil matrix (as opposed to being part of the soil structure) and bioaccumulation. The
average groundwater pH at Site 9 is between 6 and 7, indicating that metals are only somewhat mobile in the
di s s olved phas e.

2.5 SUMMARY OF SITE RISKS

The human health and ecological risks associated with exposure to contaminated media at Site 9 were
evaluated in the Addendum RI Report for Site 9. The residential use scenario was not evaluated because the
site will remain in industrial use. Insttutional controls will be implemented to prohibit residential use and
shallow groundwater use. Off-site migration of impacted groundwater is not anticipated to be a human health
concern since the discharge location (Gambo Creek) is located immediately adjacent to Site 9. Groundwater
in the shallow aguifer is not a current source of drinking water and will not be used as one in the future.
Exposure to surface water is expected to be limited to fishermen in boats.

2.5.1 Human Health Risks

Exposure Pathways and Potential Receptors

Base workers, recreational users (adults and children), and construction workers were evaluated as potential
receptors in the guantitative risk assessment. Construction workers were evaluated for future conditions
only. The remaining receptors are considered for current and future conditions. Ingestion of fin fish was
evaluated for adult recreational users only. Construction workers were evaluated for exposure to surface
subsurface soil (0 to 12 feet), while surface soil (0 to 2 feet) exposure was considered for all other
receptors. Inhalation of volatile emissions and fugitive dust was evaluated gualitatively via a comparison of
site data to U.S. EPA Generic Soil Screening levels for transfers from soil to air. Inhalation exposure was
considered to be relatively insignificant since all detected soil concentrations were less than the screening
levels. Direct contact with surface water and sediment is expected to be intermittent and of short duration
because swimming in Gambo Creek is unlikely due to inhospitable conditions and access limitations. Therefore,
pathways associated with these media were not guantitatively evaluated.

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Exposure Assessment

The COCs that were evaluated and their maximum exposure point concentrations are presented in Table 2-2.
Exposure point concentrations are used to determine potential human health risks.

Toxicity Assessment

Cancer potency factors (CPFs) have been developed by U.S. EPA's Carcinogenic Assessment Group for
estimating excess lifetime cancer risks associated with exposure to potentially carcinogenic chemicals.,
CPFs, which are unitless, are multiplied by the estimated intake of a potential carcinogen, in mg/kg/day, to
provide an upper-bound estimate of the excess lifetime cancer risk associated with exposure at that intake
level. The term upper bound reflects the conservative estimate of the risks calculated from the CPFs. Use of
this approach makes underestimation of the actual cancer risk highly unlikely. Cancer potency factors are
derived from the results of human epidemiological studies or chronic animal bioassays to which
animal-to-human extrapolation and uncertainty factors have been applied.

Reference doses (RfDs) have been developed by U.S. EPA for indicating the potential for adverse health
effects from exposure to chemicals exhibiting noncarcinogenic effects. RfDs, which are expressed in units
mg/kg-day, are estimates of lifetime daily exposure levels for humans, including sensitive individuals.
Estimate intakes of chemicals from environmental media (e.g., the amount of a chemical ingested from
contaminated drinking water) can be compared to the RfD. RfDs are derived from human epidemiological
studies or animal studies to which uncertainty factors have been applied (e.g., to account for the use of
animal data to predict effects on humans). These uncertainty factors help ensure that the RfDs will not
underestimate the potential for adverse noncarcinogenic effects to occur.

Risk Characterization

Excess lifetime cancer risks are determined by multiplying the intake level with the cancer potency factor.
These risks are probabilities that are generally expressed in scientific notation (e.g., 1x10 -6). An excess
lifetime cancer risk of 1 x 10 -6 indicates that as a plausible upper bound, an individual has a one in one
million chance of developing cancer as a result of site-related exposure to a carcinogen over a 70-year
lifetime, under the specific exposure conditions at a site.

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                              TABLE 2-2
                             HUMAN HEALTH
          CHEMICALS OF CONCERN AND EXPOSURE POINT CONCENTRATIONS(1)
                     SITE 9: DISPOSAL/BURN AREA
                      NSWCDL, DAHLGREN, VIRGINIA
     Medium
Surface Soil
Surface/
Subsurface Soil
Fish Tissue(4)
Surface
Water/Sediment
         Organics
   Chemical    Exposure Point
               Concentration
                   (mg/kg)

No COCs (2)           NA
Benzo(a)anthracene    10
Benzo(a)pyrene       7.61
Benzo(b)fluoranthene 4.2
Benzo(k)fluoranthene 6.4
Dibenz(a,h)anthracen 1.4
e                    3.8
Indeno(1,2,3-
cd)pyrene
Fluoranthene
Heptachlor
  6.0(5)
0.8977(5)
Not evaluated(6)
                                        NA
                      Inorganics
                Chemical   Exposure Point
                            Concentration
                              (mg/kg)
                Arsenic
                Arsenic
                Iron
                Lead
Aluminum
Arsenic
Beryllium
Cadmium
Cobalt
Iron
Mercury
Silver
Manganese
Not evaluated
                3.2/5.3(3)
                  6.5
                 20000
                  184
  152(5)
0.2728
0.01387
0.1134
 10.66
 463(5)
 2.024
 6.468
 4,393
  NA
1  95 percent upper confidence limits  (UCLs) were used as exposure point concentrations  for
   reasonable maximum exposure  (RME) and central tendency effect  (CTE), unless  otherwise noted.
2  All detected concentrations are less than U.S. EPA Region III  risk-based  concentrations  (RBCs).
3  Data set consists of <10 samples. Average and maximum concentrations were used  for  the CTE  and RME.
4  Theoretical concentrations are based upon maximum surface water concentrations  and
   chemical-specific bio-concentrations factors  (BCFs).
5  Maximum detection was used since the calculated 95 percent UCL exceeds the maximum.
6  No human exposure is anticipated because of site-specific conditions  (i.e.,  inaccessibility,  the
   presence of snake and snapping turtles, etc.)
NA Not applicable.

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Potential concern for noncarcinogenic effects of a single contaminant in a single medium is expressed as
the hazard guotient (HQ) (or the ratio of the estimated intake derived from the contaminant concentration
in a given medium to the contaminants reference dose). By adding the HQs for all contaminants within a
medium or across all media to which a given population may reasonably be exposed, the Hazard Index
(HI) can be generated. The HI provides a useful reference point for gauging the potential significance of
multiple contaminant exposures within a single medium or across media.

Current Bass Worker. The cumulative noricancer hazard indices for ingestion of and dermal contact with
soils for Site 9, under industrial land use conditions are less than 1, which indicates that there are no
significant hazards associated with soils at Site 9. The cumulative ingestion and dermal contact cancer
risk is 7.4 x 10 -4, under a "reasonable maximum exposure" scenario, and this is below U.S. EPA's target
risk range of 1 x 10 -6 to 1 x 10 -4.

Adult Recreational User. The cumulative noncancer hazard index associated with the potential ingestion
of fin fish, is 20.6, indicating a potential risk. The cumulation ingestion and dermal contact cancer risk is
8.0 x 10 -7 under a reasonable maximum exposure scenario, which is below U.S. EPA's target risk range of 1 x
10 -6 to 1 x 10 -4. The cancer risk associated with fin fish ingestion, however, is 6.8 x 10 -4, indicating a
potential risk.

Child Recreational User. The cumulative noricancer hazard index and cancer risk associated with
ingestion of and dermal contact exposure with surface and subsurface soil at Site 9 under industrial land
use scenario are less than 1, and 9.1 x 10 -7, respectively, under a reasonable maximum exposure scenario.

Construction Worker. The cumulative noncancer hazard index and cancer risk associated with ingestion
and dermal contact exposure to Site 9 soil under industrial land use conditions are 5.3 x 10 -1 and.44 x
104, respectively, under a reasonable maximum exposure scenario.

Although the incremental cancer risk for the construction worker slighby exceeded 1x10 -6, it is within U.S.
EPAs target risk range of 1x10 -4 to 1x10 -6. Potential health hazards may be observed for adult
recreational users who ingest contaminated finish. Since the risk to all other receptors is less than
10 -6, and the hazard indices for receptors are less than 1.0, human health risks under industrial land M
conditions for those receptors are within acceptable risk ranges at Site 9.

2.5.2 Environmental Evaluation

The intent of the baseline ecological risk assessment (ERA) was to characterize potential receptors and to
estimate the potential hazard or risk to environmental receptors. Wetland identifications, terrestrial
wildlife inventories, vegetation surveys and macroinvertebrate inventories were performed in order to
characterize the habitats associated with Site 9. Sample locations were selected to detect potential
groundwater contamination discharging to nearby surface water bodies via the shallow aguifer as well as
contaminants resulting from surface water runoff. Samples were collected from marshy areas near the site as
well as points in Gambo Creek. Field work included sampling locations upstream, adjacent to, and downstream
of Site 9 in Gambo Creek. Surface water, sediment, fish tissue, sediment toxicity, and macroinvertebrate
community samples were taken from these locations, with the exception of fish tissue at the upstream
location. Information from the Gambo Creek Ecological Assessment (EA) was also used to support the Site 9
evaluation.

Ecological effects guotients (EEOs) were derived for each COG in all media. An EEO represents
the ratio of the maximum concentration of a constituent to an associated cleanup criteria or PRG.
An EEO egual to or greater than 1.0 indicates a potential risk to ecological receptors. Based on
EEOs and risk management factors, the following COCs are of greatest concern:

• Copper, lead, mercury, and zinc in surface water,
DDD, DDE, DDT, Aroclor-1260, copper, and lead in sediments,
• DDT, copper, lead, mercury, and zinc in surface soils.

Based on elevated concentrations and risk levels of metals like copper, lead, and zinc in all three
media, waste debris on Site 9 appears to be the source for the COCs.

Exposure Pathways

The exposure pathways consist of dermal absorption and ingestion of chemicals from soil, sediments, and
surface water.

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Exposure Assessment

Six contaminants in sediment  (DDD, DDE, DDT, Aroclor-1260, copper, and lead), four contaminants in surface
water (copper, lead, mercury, and zinc),  and five contaminants in surface soils  (DDT, copper, lead, mercury,
and zinc) were identified as COCs for ecological receptors. The EEQ for each of these contaminants was
greater than 1.

Potential Receptors

The organisms most likely to be ecological receptors, include mice, voles, rabbits, earthworms, ground
insects, fish, and a variety of birds. Because of the natural setting of Site 9 and the variety of nearby
habitats, Site 9 is likely to have a diversity of wildlife.

Risk Characterization

Based on risk management factors as well as potential risk levels, copper, lead, mercury, and zinc are
concerns for surface water; DDD, copper,  and lead are of concern in sediments; and DDT, copper, lead,
mercury, and zinc are concerns for surface soils.

2.5.3     Development of Preliminary Remediation Goals  (PRGs)

Contaminant fate and transport modeling was used to evaluate the potential for COCS identified by the human
health and ecological risk assessment to migrate to other media and present unacceptable risks. For example,
contaminants present in soils could migrate to groundwater or be carried with precipitation to surface water
or sediments at a site. In order to evaluate this potential, fate and transport modeling was conducted for
Site 9 using the ECTran model. The model uses contaminant properties such as the adsorption coefficient, and
site-specific characteristics such as groundwater velocity, to predict acceptable levels of COCs in soil and
groundwater that would be protective of surface water and sediment. Using regulatory criteria for surface
water and toxicity data for sediment, preliminary remediation goals (PRGs) were developed by the modeling to
determine if existing levels of COCs are acceptable. A complete discussion of the use of modeling and
assumptions is presented in Appendix C of the Site 9 FS and Addendum FS.

Potential migration of COG's evaluated for Site 9 by the ECTran model included:

       •      Surface soil to surface water via runoff
       •      Surface soil to sediment via runoff
       •      Surface soil to surface water via groundwater
       •      Subsurface soil to surface  water via groundwater
       •      Subsurface soil to sediment via groundwater
       •      Groundwater to surface water
       •      Groundwater to sediment

Based on potential migration, the following remedial action objectives (RAOs) are anticipated for Site 9
soil, sediments, and groundwater to address the primary exposure pathways. RAOs may be modified  (made more
stringent)  during Remedial Design based on more detailed evaluation:

       •      Prevent ecological receptors from being directly exposed to 4,4-DDE,  4-4-DDT,
              arsenic,  copper, lead, mercury, and zinc in surface soils at concentrations greater
              than 0.1 mg/kg, 0.1 mg/kg,  2.66 mg/kg, 50 mg/kg, 50 mg/kg,  0.0185 mg/kg,  and 50
              mg/kg, respectively.

       •      Prevent 4-4-DDD, 4-4-DDE,  4-4-DDT,  copper,  lead, mercury,  silver,  and zinc present
              in surface soil at concentrations greater than 0.028 mg/kg, 0.03 mg/kg, 0.018 mg/kg,
              33 mg/kg, 44 mg/kg, 0.13 mg/kg, 0.31 mg/kg, and 259 mg/kg respectively from
              migrating from the surface soils and causing adverse effects to ecological receptors.

       •      Prevent copper,  mercury,  and silver present in subsurface soil at concentrations
              greater than 246 mg/kg, 0.13 mg/kg, and 0.31 mg/kg, respectively,  from migrating to
              surface water via groundwater and causing adverse effects in ecological receptors.

       •      Prevent barium,  copper,  lead,  mercury,  manganese,  nickel,  silver,  and zinc present
              in subsurface soil at concentrations greater than 182 mg/kg, 50.1 mg/kg,  386 mg/kg,

-------
              0.45, 958 mg/kg, 76.4 mg/kg, 6.31 mg/kg, and 523 mg/kg, respectively, from
              migrating to sediments via groundwater and causing adverse effects in ecological receptors.

       •      Prevent barium,  cadmium,  copper,  lead,  manganese,  mercury, nickel, silver,  and
              zinc present in groundwater at concentrations greater than 2,530  Ig/L, 17.05 Ig/L
              655.8 Ig/L,  289 Ig/L, 8,790 Ig/L, 834.5 Ig/L, and 5,700 Ig/L, respectively, from
              moving to the creek surface water and sediment, and causing adverse effects in
              ecological receptors.

       •      Prevent ecological receptors from being exposed to marsh sediments contaminated
              with metals,  pesticides/PCBs,  and sernivolatile organic compounds listed in Table 2-3.

2.6       DESCRIPTION OF ALTERNATIVES

A detailed analysis of the possible remedial alternatives for Site 9 is included in the Site 9
Feasibility Study report.  The detailed analysis was conducted in accordance with the U.S. EPA
document entitled Guidance for Conducting Remedial Investigations and Feasibility Studies under
CERCLA and the National Oil Hazardous Substances Pollution Contingency  Plan.

-------
                   TABLE 2-3
                  SUMMARY OF SEDIMENT PRGs SITE 9 -  (MG/KG)
              NAVAL SURFACE WARFARE CENTER, DAHLGREN, VIRGINIA
      Chemical of Concern
2-Methylnaphthalene
4,4'-DDD
4,4'-DDE
4,4'-DDT
Anthracene
Aroclor-1254
Aroclor-1260
Arsenic
Benzo(a)anthracene
Benzo(a)pyrene
Benzo(b)flouranthene
Benzo(g,h,1)pyrene
Benzo(k)flouranthene
Cadmium
Chromium
Chrysene
Copper
Dibenzo(a, h) anthracene
Flouranthene
Fluorene
Indeno(1,2,3-cd) Pyrene
Lead
Mercury
Naphthalene
Nickel
Phenanthrene
Pyrene
Silver
Zinc
Preliminary Remediation
        Goals
Protection of Sediment
       0.67
      0.013
      0.031
      0.016
       1.1
      0.067
      0.067
        9.7
        16
        1.6
        4.8
        4.8
        4.8
        0.7
       28.8
        2.8
       30.0
        0.26
        5.1
        0.54
        4.8
       39.8
        0.2
        2.1
       34.3
        1.5
        2.6
        2.8
        234

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Because Site 9 is located adjacent to and partially in the marsh, which is the area of local groundwater
discharge, collection and treatment of contaminated groundwater is impractical. The shallow groundwater
beneath Site 9 is not currently or reasonably expected to be a source of drinking water and when
institutional controls are implemented, will be restricted from any use, except monitoring. Additionally,
containment of and diversion of groundwater from contaminant sources by installing an upgradient slurry
cutoff wall will control release of contaminants to the environment to levels which are protective of the
environment, For Site 9, under all the alternatives, except the No Action alternative, an institutional
control plan will be developed as part of the remedial action design and include: access controls, signs
along the perimeter of the site, restrictions on shallow groundwater use for drinking water, description of
land use controls in the base master plan, periodic inspection, monitoring, and re-evaluation of land use
controls, annual certification that institutional controls are in place, notification to the U.S. EPA and
state regulators whenever the Navy anticipates any major changes in land use restrictions, public notice, and
a deed notification.

The following institutional controls are part of every alternative except the No Action alternative, and
shall be undertaken within 90 days of completion of remedial construction: a real property description
notation, Base Master Plan notations, and limited site access.. The Base Master Plan shall note the area as
one in which residential development can not occur, shallow groundwater can not be used, and site access
shall be limited. A notation shall be filed in the real property file maintained at EFA Ches for this site
indicating the extent of the area and the fact that solid wastes are present. The institutional controls
shall also include the following: Within 90 days after completion of the remedy, the Navy shail produce a
survey plat prepared by a professional land surveyor registered by the Commonwealth of Virginia indicating
the location and dimensions of the disposal area and the extent of groundwater contamination. Monitoring well
locations shall be included and identified on the survey plat. The plat shall contain a note, prominently
displayed, which states the owner's future obligation to restrict disturbance  (excavation or construction) of
the property; post-closure use of the property shall prohibit residential use and access or use of
groundwater underlying the property for any purpose except monitoring, and the function of the monitoring
systems shall not disturbed. The owner of the property shall submit the survey plat to the local recording
authority when closure is complete. When landfill closure is complete, the owner of the property shall submit
the survey plat to the local recording authority, and shall record a notation with the deed  (or some other
instrument which is normally examined during title search at the local land recording authority notifying any
potential purchaser of the property that the land has been used to manage solid waste and the integrity of
the cover system or the function of the monitoring system may not be disturbed.

A summary of the remedial alternatives which were developed to address contamination associated with
Site 9 is presented below.

The following lists the primary components of each of the alternatives developed for Site 9. Each of
Alternatives 2 through 5 include institutional controls, surface water controls, and vegetation restoration
as appropriate.

       •      Alternative 1 No Action
              Landfill:                 No Action
              Marsh Area:              No Action
              Southern Portion:        No Action

       •      Alternative 2 Landfill Cap and Waste/Fill Excavation in Marsh
              Landfill:                 Multilayer Cap
              Marsh Area:              Excavate All Waste Material
              Southern Portion:        Remove Surface Debris/Surface Soil
              Options:                  A

       •      Alternative 3 Landfill Cap and Marsh Cap
              Landfill:                 Multilayer Cap
              Marsh Area:              Remove Surface Debris and Place
                                             Marsh Cap Over All Waste Material
       •      Southern Portion:        Remove Surface Debris/Surface Soil
              Options:                  A,  Bl, B2, B3

       •      Alternative 4 Landfill Cap and Surface Sediment Removal in Marsh
              Landfill:                 Multilayer Cap
              Marsh Area:              Excavate Surface Debris and Surface
                                             Sediments in Excess of PRGs

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• Southern Portion: Remove Surface Debris/Surface Soil
Options: A, Bl, B2, B3

• Alternative 5 Landfill Cap and Surface Debris Removal in Marsh
Landfill: Multilayer Cap
Marsh Area: Remove Surface Debris
Southern Portion: Remove Surface Debris/Surface Soil
Options: A, Bl, B2, B3

The following lists the options which were considered with Alternatives 2 through 5. Option A involves
placing a vertical slurry wall on the upgradient side of the landfill to reduce the amount of groundwater
flow through the landfill. The B options involve different methods of satisfying the reguirement for a 100
foot setback from Gambo Creek. The options are listed below.

• Option A Construct a slurry wall on the upgradient side of the landfill.

• Option Bl Remove all waste within 100 feet of Gambo Creek. Backfill with clean
soil and revegetate.

• Option B2 Place shoreline protection along the streambank anywhere the waste/fill
material is within 100 feet of Gambo Creek.

• Option B3 Relocate or fill in Gambo Creek so that it is at least 100 feet from
waste/fill material in the marsh.

As can be seen from the preceding lists, capping of the landfill is included in all of the alternatives
involving an action. Also, removal of surface debris and surface soil from the southern portion of the site
is included. Capping is the only action remedy considered for the landfill based on the containment
presumptive remedy and site specific conditions. Option A can be used to supplement the containment
remedy for the landfill. Since capping is a component of all of the action alternatives, it is coupled with
institutional controls, monitoring, and removal of surface debris from the southern portion of the site since
these components are also common to all of the action alternatives. A brief description of each alternative
and option is provided below.

Alternative 1: No Action

Under this alternative, no further effort or resources would be expended at Site 9. Alternative 1 serves as
the baseline against which the effectiveness of the other alternatives is judged.

The following costs are associated with this alternative:

Present Worth($): 15,550/5 yr (Estimated administrative cost of 5-year review of
remedial action over a 30-year period
Time to Implement: 0 months

Alternative 2: Landfill Cap and Waste/Fill Excavation In Marsh

Alternative 2, involves constructing a multilayer cap over the landfill portion of Site 9. The construction
of the landfill cap consists of four major components; (1) Regrading and consolidation of wastes, (2)
Construction of the cap components, (3) Installation of surface water controls including revegetation, and
(4) Institutional controls and monitoring. This alternative also involves removal of surface debris from the
southeast area of the site and removal of contaminated surface soil. The soil and surface debris would be
consolidated under the multilayer cap. Surface sediments from the ditch bordering the southern edge of the
landfill would also be excavated and consolidated under the cap.

Removal of waste/fill material from the marsh involves four major components: (1) Excavation of waste/fill
material in the marsh, (2) Consolidation of the material under the cap, (3) Revegetation and restoration of
the marsh, and (4) Surface water controls including shoreline protection.

This alternative can also be coupled with Option A which will be discussed at the end of this section. The
B options are not included as part of Alternative 2 because all of the wasteffill would be removed ftwm!h~
wetland which will satisfy the 100 loot off-set reguirement for Gambo Creek.

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Landfill Cap - Wastes and surface soil removed from the southern area of the site and the marsh would be
consolidated and stabilized on the landfill portion of the site. It is estimated that approximately 250 cy of
waste would be removed from the southern area of the site. Waste excavated from the wetland would
also be consolidated under the multilayer cap. Consolidation may include size separation, crushing and
grinding. The landfill, estimated to be approximately 5.0 acres upon completion of closure activities, would
be capped with a multilayer cap meeting the reguirements of the Virginia Solid Waste Management
Regulations, 9 VAC 20-80-210 (Remedial Reguirements) and 9 VAC 20-80-250 (sanitary landfill). The
landfill cap will limit precipitation and runoff entering the consolidated fill material. It is anticipated
that the multilayer cap will need to exceed the minimum reguirements of a 9 VAC 20-80-250 (sanitary
landfill), based on preliminary modeling conducted for the remedial design, to be protective of receptors in
Gambo Creek. The final cap components will be determined during the final design for Site 9. The multilayer
cap will be revegetated, and the closure completed consistent with 9 VAC 20-80-250 (sanitary landfill)
closure reguirements. The closure would include provisions for the installation of structures at the toe of
the landfill and elsewhere to provide erosion and sediment control measures including protection from surges
the water surface of Gambo Creek due to major regional storm events such as hurricanes. The current boundary
of the landfill will be pulled back from Gambo Creek so that the waste associated with the cap will be a
minimum of 100 feet from Gambo Creek.

Institutional controls, including limiting site access through access gates and future land use through a
deed notation would be implemented to eliminate or reduce pathways of exposure to contaminants at the
site. Groundwater, surface water, and sediments would be addressed through the above source controls
plus monitoring to determine it contaminants are migrating at significant rates and concentrations.

Removal of Waste/Fill Material in the Marsh - Under Alternative 2, all wastes would be excavated from the
marshy area of the site, consolidated and stabilized on the landfill. It is estimated that approximately
18,000 cy of waste/fill material would be removed from the marsh.

Once the material is excavated from the marsh, the material will be reguired to be stabilized before it can
be consolidated on the landfill portion of Site 9.

Option A - This option is to improve the performance of the remedy by reducing the movement of groundwater
through the landfill. The option would consist of installing an upgradient groundwater control such as an
impermeable wall (slurry wall) on the hydraulically upgradient (west) side of the landfill, effectively
redirecting groundwater movement around the capped landfill. The slurry wall would be installed to a depth
below grade and keyed into the clay confining unit beneath the site.

This remediation alternative would operate indefinitely. Annual operations and maintenance (O&M) costs
include annual landfill closure monitoring costs, including 5-year reviews under CERCLA for 30 years.

Capital Cost: $7,773,891 (without Option A)
$8,539,899 (with Option A)
Annual O&M: $33,350 + $15,500 every 5 years
Present Worth: $8,421,149 (without Option A)
$8,987,157 (with Option A)
Time to Implement: 6 months

Alternative 3: Landfill Cap and Marsh Cap

This alternative consists of the several components which were described in Alternative 2 including: the
landfill cap, removal of surface sediments, surface debris, and surface soil removal from the southern
portion of the Site, Option A, institutional controls, and monitoring. This information is not repeated here.

Alternative 3 provides a different remedy for the wastelfill material in the marsh (marsh cap) and includes
the three B options for achieving the 100 foot offset of waste from Gambo Creek.

Marsh Cap - The marsh cap consists of three major components: (1) removal of surface debris in the
marsh and consolidation onto the main portion of the landfill, (2) installation of a geogrid and cap over the
marsh area of the site, and (3) revegetating the marsh.

Under Alternative 3, surface debris would be removed (excavated) from the marshy area of the site and
consolidated and stabilized on the landfill. It is estimated that approximately 260 cy of surface debris
would be removed from the marsh. Vegetation in the marshy area of the site would be cut back. If

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required, a geogrid would be placed and anchored over the entire 2.4 acre area. The placement of the
geogrid over the marsh would improve the lateral stability of the soils in the area, and allow construction
equipment to complete the placement of the cap over the waste disposal areas in the marsh. The marsh cap
would meet the minimum thickness requirements (2 feet) of Virginia Sanitary landfill cap. The marsh cap would
provide sound engineering controls per 9 VAC 20-80-250 to help control groundwater which intrudes the site by
being constructed to an elevation (estimated to be 4 feet msl) which would preclude the possibility of
groundwater migration upward through the waste material and reaching the cap surface. The marsh cap will
address 9 VAC 20-80-250 requirements to control releases or otherwise reduce site risks by: 1).cutting off
potential contact exposure to wastes in the marsh; 2) enhancing evaporation of contaminated groundwater which
flows within the marsh cap; and 3) providing additional sorbing soils
through which the contaminated groundwater must pass before being discharged to the marsh. Upon completion of
the placement of the marsh cap, appropriate vegetation would be re-introduced and maintained. Installation of
the marsh cap would raise the elevation of the marsh and would likely turn the capped area into an upland.
The wetland loss would be mitigated elsewhere at the NSWCDL facility.

Option Bl - Remove All Waste in the Marsh Area from Within 100 Feet of Gambo Creek - This option would be
very similar to Alternative 2 where all of the waste is excavated from the Marsh area except a smaller area
would be excavated. Approximately 8,730 c.y. would be excavated from the marsh.

Because the waste will be removed from a substantial area of the marsh, the marsh cap would be reduced
to 39,700 square feet.

Option B2 - Shoreline Protection - Under this option, the shoreline of Gambo Creek would be protected
against erosion to provide a benefit equivalent to moving waste 100 feet away from Gambo Creek. This
protection would be provided where Gambo Creek is within 100 feet of the waste/fill material In the marsh.
Shoreline protection requirements would be determined during the Remedial Design based on detailed
hydrologic/hydraulic analysis. It is conservatively assumed that the shoreline protection will consist of
performing spot regrading of the Gambo Creek stream bank, placement of a geotextile, and placement of
riprap to the same elevation as the existing stream bank. It is anticipated that 560 linear feet of shoreline
protection will be required.

Option B3 - Relocation or Fill in Gambo Creek - This option involves rechanneling Gambo Creek so that
it does not flow within 100 feet of wasteffill material. Portions of Gambo, Creek would be filled, and
restored as wetlands. Other areas of the marsh would be excavated for the new channel and provide the
equivalent channel volume of open water as was lost due to filling activities. It is anticipated that sheet
piling would be required to facilitate the excavation and filling operations. The sheet piling would separate
the flow in Gambo Creek from the excavation and fill areas to limit the sediment that would enter the creek
during excavation. Approximately 0.6 acres of Gambo Creek would be filled. Material excavated from the marsh
would be used to fill Gambo Creek. Approximately 4,315 cy of material would be excavated and filled.

This remediation alternative would operate indefinitely. Annual O&M costs include landfill, groundwater, and
surface water and sediment monitoring costs and a report evaluating waste in place, which would occur
every 5 years for 30 years.

Capital Cost
Option Bl: $6,682,409 (without Option A)
$7,248,417 (with Option A)
Option B2: $2,981,059 (without Option A)
$3,547,067 (with Option A)
Option B3: $3,776,396 '(without Option A)
$4,342,404 (with Option A)
Annual O&M: $33,350 + $15,500 every five years
Present Worth:
Option Bl: $4,223,654 (without Option A)
$4,789,662 (with Option A)
Time to Implement: 6 months

Alternative 4: Landfill Cap and Surface Sediment Excavation in Marsh

This alternative consists of the several components which were described In Alternative 2, including: the
landfill cap, surface sediment removal from the ditch south of the landfill, surface debris/surface soil
removal from the southern portion of the Site, Option A, institutional controls, and monitoring. This
information is not repeated here,

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Alternative 4 provides a different remedy for the wasteffill material in the marsh  (surface sediment
removal) and includes the three B options to keep waste 100 feet away from Gambo, Creek. The three B
options are the same as described under Alternative 3.

Surface Sediment ~Excavation in Marsh - Surface sediment excavation consists of three major
components: (1) excavation of surface debris in the marsh and consolidation onto the main portion of the
landfill,  (2)  excavation of 1 foot of contaminated surface sediments and consolidation onto the main portion
of the landfill, and (3)  revegetating the marsh.

Under Alternative 4, surface debris would be removed  (excavated) from the marsh area, consolidated, and
stabilized on the landfill. Contaminated surface sediments within the limit of waste in the marsh would
also be excavated to address ecological risks from direct contact. The surface sediment would be
consolidated on the landfill, It is estimated that approximately 260 cy of surface debris from the marsh,
and 2,900 cy of surface sediments from selected areas of the marsh would be excavated. Contaminated
surface sediment would be excavated to a depth of 1 foot below grade and backfilled. The 1 foot depth
would be sufficient to prevent direct contact from most ecological receptors. Wastes removed from the
marsh would be replaced with clean fill and the area revegetated to restore these areas to their original or
enhanced condition.

This remediation alternative would operate indefinitely. Annual O&M costs include landfill, groundwater,
and surface water and sediment monitoring costs and a report evaluating waste in place, which would occur
every 5 years for 30 years.

             Capital Cost:
                Option Bl:        $6,768,684 (without Option A)
                                  $7,354,892 (with Option A)
                Option B2:        $2,974,508 (without Opbon A)
                                  $3,540,516 (with Option A)
                Option B3:        $3,769,845 (without Option A)
                                  $4,335,853 (with Option A)
          Annual OM               $33,350 + $15,500 every five years
        Present Worth:
                Option Bl:        $7,236,142 (without Option A)
                                  $7,802,150 (with Option A)
                Option B2:        $3,421,766 (without Option A)
                                  $3,987,774 (with Option A)
                Option B3:        $4,217,103 (without Option A)
                                  $4,783,111 (with Option A)
        Time to Implement:        6 months

Alternative 5: Landfill Cap and Surface Debris Removal in Marsh

This alternative consists of the several components which were described in Alternative 2 including: the
landfill cap,  surface debris removal from the southern portion of the Site, Option A, institutional controls,
and monitoring. This information is not repeated here.

Alternative 5 provides a different remedy for the waste/fill material in the marsh  (surface debris removal)
and includes the three B options for achieving the 100 foot offset of waste from Gambo Creek. The three B
options are the same as described under Alternative 3.

Surface Debris Removal in Marsh - Surface debris removal consists of 2 major components: (1)
excavation of surface debris in the marsh and consolidation onto the main portion of the landfill, and  (2)
revegetating the marsh.

Under Alternative 5, surface debris would be removed  (excavated) from the marsh area, consolidated, and
stabilized on the landfill. This alternative relies on the reduction in contaminant migration afforded by
capping the landfill and proposes only minimal disturbance to the marsh habitat.

It is estimated that approximately 260cy of surface debris would be excavated from the marsh. Wastes
removed from the marsh would be replaced with clean fill and the area revegetated to restore these areas
to their original or an enhanced condition.

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This remediation alternative would operate indefinitely. Annual O&M costs include landfill, groundwater, and
surface water and sediment monitoring costs and a report evaluating waste in place, which would occur
every 5 years for 30 years.

              Capital Cost
                Option Bl:       $6,380,802 (without Option A)
                                 $6,946,810 (with Option A)
                Option B2:       $2,392,976 (without Option A)
                                 $2,958,984 (with Option A)
                Option B3:       $3,188,313 (without Option A)
                                 $3,754,321 (with Option A)
               Annual O&M:       $33,350 + $15,500 every five years
            Present Worth:
                Option Bl:       $6,828,060 (without Option A)
                                 $7,394,068 (with Option A)
                Option B2:       $2,840,234 (without Option A)
                                 $3,406/242(with Option A)
                Option B3:       $3,635,571 (without Option A)
                                 $4,201,579(with Option A)
        Time to Implement:       6 months

2.7       SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES

The remedial alternatives described in Section 2.6 were evaluated in the Feasibility Study against nine
criteria identified in the NCP, as presented below.

2.7.1     Threshold Criteria

Overall Protection of Human Health and the Environment

Alternative 3 provides the highest level of overall protection to human health and the environment by
preventing transport of, and plant and animal contact with, contaminants through the containment of
wastes within the landfill and marsh area. Alternative 2 provides a high level of protection because all
waste material is removed from the marsh area, but reguires a significant disturbance of the marsh area
during construction with a greater possibility of contaminants being released during construction.
Alternative 4 provides less overall protection than Alternative 3 and reguires more disturbance of the
marsh area during construction with a possibility of contaminants being released during construction.
Alternative 5 provides less overall protection in the marsh than Alternative 4 because contaminated
sediment is neither removed or contained. Alternative 1 provides the least overall protection because no
action would be taken to reduce contaminant movernoent and contaminated soil and sediment is neither
removed nor contained.

Option A (slurry wall) would enhance the protectiveness of the landfill cap under all alternatives. The
slurry wall prevents groundwater from coming into contact with materials buried in the landfill and reduces
potential movement of contaminants to the environment

Option B2 provides a high level of overall protection by preventing potential erosion of buried waste within
the marsh.  Option B3 provides a high level of protection but reguires significant disturbance of Gambo, Creek
northeast of the landfill during construction with a greater possibility of affecting water guality due to
resuspension of sediment within Gambo Creek.

Option Bl provides a high level of protection but reguires significant disturbance of the marsh area during
construction with a greater possibility of contaminants being released during construction.

Every alternative except the No Action alternative implements measures to control sources of
contamination and exposure to humans and the environment to residual contamination, as necessary to
protect human health and the environment. This includes permanent notification in local land records of
groundwater use restrictions in order to control exposure of humans to residual contamination in
groundwater, and containment of and diversion of groundwater from contaminant sources by installing an
upgradient slurry cutoff wall in order to control release of contaminants to the environment to levels which
are protective of the environment.

Compliance with Applicable or Relevant and Appropriate Reguirements (ARARs)

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Groundwater chemical-specific ARARs (MCLs) would not likely be attained at Site 9 during the project life
under any of the alternatives. Because Site 9 is located adjacent to and partially in the marsh, which is the
area of local groundwater discharge, collection and treatment of contaminated groundwater is impractical. The
groundwater is not currently or reasonably expected to be a source of drinking water and when Institutional
controls are implemented, will be restricted from any use, except for monitoring.

Alternative 3 would achieve remediation goals and compliance with ARARs and To Be Considered (TBC)
reguirements. Under Alternative 3 buried waste would remain in the marsh area. Long term monitoring with the
opportunity to implement additional measures, if warranted, would mitigate such concerns. Alternative 2 would
meet remediation goals, ARARs, and TBCs but reguires more disturbance of the marsh area during construction
with a possibility of contaminants being released during construction. Alternative 4 would meet remediation
goals but also reguires more disturbance of the marsh area during construction with a possibility of
contaminants being released during construction. Alternative 5 is least likely to meet remediation goals,
ARARs, and TBCs because contaminated sediment is neither removed nor contained. Alternative 1 would not meet
remediation goals, ARARs, and TBCs because no action would be taken to reduce contaminant movement and
contaminated soil and sediment is neither removed nor contained.

Option A (slurry wall) would enhance the ability of the landfill cap to meet remediation goals, ARARs, and
TBCs under all alternatives. The slurry wall prevents groundwater from coming into contact with materials
buried in the landfill.

Option 82 meets remediation goals, ARARs, and TBCs by providing protection eguivalent to that reguired
to comply with the ARAR. Options Bl and B3 meet the ARARs by providing the 100 foot separation distance.

Appendix C is a table of the ARARs for Site 9.

2.7.2 Primary Balancing Criteria

Reduction of Toxicity, Mobility, and Volume

Alternative 3 reduces the mobility of contaminants present in the landfill and marsh area by capping the
waste. Alternative 2 reduces the mobility of contaminants present in marsh area by removing them and
placing them under the landfill cap. Alternative 4 reduces the mobility of contaminants present in the
marsh area by removing some of them and placing them under the landfill cap while covering the remaining
waste/fill material with clean soil. Alternative 6 does not reduce the mobility of contaminants present in
the marsh and reduces the mobility of contaminants in the landfill by capping. Alternative 1 does not reduce
the mobility of contaminants at Site 9. None of the alternatives reduce toxicity or volume of waste through
treatment because it would be cost prohibitive due to the large volume of waste present at the site.

Option A (slurry wall) would enhance the ability of the landfill cap to reduce the mobility of contaminants
under all alternatives. The slurry wall prevents groundwater from coming into contact with materials buried
in the landfill.

Option B2 reduces the potential mobility of contaminants by preventing potential erosion of buried waste
within the marsh. Options Bl and B3 reduce the potential mobility of contaminants by providing the 100
foot separation distance.

Long-term Effectiveness

Alternative 3 is expected to be effective in the long term. Under Alternative 3 buried waste would remain
in the marsh area. Long term monitoring with the opportunity to implement additional measures, if
warranted, will mitigate such concerns. Long-term effectiveness is expected to be somewhat better for
Alternative 2 because all waste is removed from the marsh area and somewhat less effective for
Alternative 4 since waste left in the marsh would not have a marsh cap. Alternative 5 is not expected to
be effective In the long term because surface sediments that do not meet cleanup goals would remain in
the marsh. Alternative 1 would not be effective in the long term because it does not protect the
environment.

Option A (slurry wall) is expected to be very effective in the long term. All of the B Options are expected
to be effective in the long term by providing protection from erosion of the waste material in the marsh.

Short-term Effectiveness

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Alternative 3 would be the most effective in the short term because it does not require disturbance of
waste materials buried in the marsh thereby reducing the short term exposure and potential releases of
contaminants to the environment. Construction operations associated with Alternatives 2 and 4 would
significantly disturb waste buried in the marsh, thereby reducing the short-term effectiveness. Although
Alternative 5 would provide the least amount of disturbance in the marsh, it would not be effective because
plants and animals remain exposed to contaminated sediment.

Option A (slurry wall) is expected to be very effective in the short term. Option B2 would be completed in
a shorter amount of time than Bl and B3, and would have a smaller impact on the marsh. Construction
operations for Options Bl and B3 would disturb large areas of the marsh and Gambo Creek.

Implementability

Alternative 3 and Option B2 are the most easily implemented, although all the alternatives can be
implemented using conventional, well-demonstrated, and commercially available technologies. Alternative 1
requires no implementation. Alternatives and options which involve removing waste, soils, or surface
sediments present common implementability issues which can be overcome. Alternative 2 would involve
excavating all waste buried in the marsh area and would be the most difficult alternative to implement.
Option B3 would involve relocating Gambo Creek and would be the most difficult of the B options to implement.

Cost

Alternatives 3, 4, and 5 are relatively similar in costs. Alternative 2 is the highest cost alternative
($8,990,000) while Alternative 5 is the least cost afternative ($2,840,000). The cost of implementing the
alternatives increases dramatically with the amount of waste removed from the marsh area.

Option A costs approximately $566,000 for all the alternatives. Of the B options, costs increase
significantly as more materials are removed from the marsh. Option B2 is the least cost option while
Option Bl is the highest cost option.

2.7.3 Modifying Criteria

State Acceptance

The Virginia Department of Environmental Quality, on behalf of the Commonwealth of Virginia, has reviewed the
information available for this site and has concurred with this ROD and the selected remedy identified below.
A copy of the concurrence letter from the Commonwealth of Virginia is attached as Appendix A

Community Acceptance

Community acceptance summarizes the public's general response to the alternatives described in the Proposed
Plan and the Feasibility Study. No written comments were received during the thirty-day comment period which
began on August 20, 1998 and ended on September 18, 1998. There were no formal comments or questions received
it the Proposed Plan public meeting held on August 27, 1998. The background on community involvement is
included in the Responsiveness Summary, Section 3.0 of the ROD.

2.8 THE SELECTED REMEDY

Alternative 3 with option A (upgradient groundwater control), option B2 to the north, (shoreline protection),
and B3 to the south (fill Gambo Creek and restore as wetlands) is the selected remedial alternative,
utilizing capping to address both soils and sediments. Based on available information and the current
understanding of site conditions, the selected remedy appears to provide the best balance with respect to
the nine NCP evaluation criteria. The selected remedy is shown in Figure 2-6. In addition, the selected
remedy is anticipated to meet the following statutory requirements:

• Protection of human health and the environment.
• Compliance with ARARs.
• Cost-effectiveness.

The selected remedy would address the contamination at Site 9. The selected remedy is estimated to
turn 2.4 acres of wetland (marsh soil cap area) to upland and create 1.0 acre of new wetland (area to be
excavated for cap construction and portions of Gambo Creek to be filled) at Site 9 (Figure 2-6). Additional

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wetland acreage will be created elsewhere at the NSWCDL facility to mitigate the wetland loss.

Institutional controls will be implemented to limit future site land use. For Site 9, an institutional
control plan will be developed as part of the remedial action design and include: access controls, signs
along the perimeter of the site, restrictions on shallow groundwater use for drinking water, description of
land use controls in the base master plan, periodic inspection, monitoring, and re-evaluation of land use
controls, annual certification that institutional controls are in place, notification to the U.S. EPA and
state regulators whenever the Navy anticipates any major changes in land use restrictions, public notice, and
a deed notification.

The Navy shall institute the following institutional controls within 90 days of completion of all remedial
actions: a real property description notation, Base Master Plan notations, and limited site access. The
Base Master Plan shall note the area as one in which residential development can not occur, shallow
groundwater can not be used, and site access shall be limited. A notation shall be filed in the real property
file maintained at EFA Ches (US Navy) for this site indicating the extent of the area and the fact that solid
wastes are present. The institutional controls shall also include the following: Within 90 days after
completion of the remedy, the Navy shall produce a survey plat prepared by a professional land surveyor
registered by the Commonwealth of Virginia indicating the location and dimensions of the disposal area and
the extent of groundwater contamination. Monitoring well locations should be included and identified on the
survey plat. The plat shall contain a note, prominently displayed, which states the owners future obligation
to restrict disturbance (excavation or construction) of the property; post-closure use of the property shall
prohibit: residential use and access or use of groundwater underlying the property for any purpose except
monitoring and the function of the monitoring systems shall not be disturbed. When landfill closure is
complete, the owner of the property shall submit the survey plat to the local recording authority, and shall
record a notation with the deed (or some other instrument which is normally examined during title search at
the local land recording authority) notifying any potential purchaser of the property that the land has been
used to manage solid waste and the integrity of the cover system or the function of the monitoring system may
not be disturbed.

The Navy shall institute groundwater monitoring to ensure the RAOs are being maintained. Monitoring of
surface water and sediments shall be implemented to measure concentrations of these constituents. The
freguency of analysis and the length of time for groundwater, surface water, and sediment monitoring shall
be developed in the Operation and Maintenance Plan.

Based on available information and the current understanding of site conditions, Alternative 3 appears to
provide the best balance with respect to the nine NCP evaluation criteria. In addition, the selected
alternative is anticipated to meet the following statutory reguirements:

• Protection of human health and the environment.
• Compliance with ARARs.
• Cost-effectiveness.

The institutional controls will further protect human health and the environment by limiting future land use
and by providing continuous monitoring.

2.8.1 Performance Standards

The selected remedy shall be capable of managing residuals and achieving all RAOs within the
boundaries of Site 9 and shall meet all ARARs and TBCs for the site.

Landfill Cap

The landfill cap shall be designed, constructed, operated, and maintained to meet or exceed the performance
reguirements of RCRA Subtitle D regulations specified in 40 CFR °° 258.60-61 and Virginia Solid Waste
Management Regulations, 9 VAC 20-80-210 (Remedial Reguirements) and 9 VAC 20-80-250 (Sanitary
Landfill).

The cap design shall minimize infiltration, and control surface water run on/runoff. The landfill cap shall
be constructed, at a minimum to the following performance standards: a 6-inch vegetative and protective layer
and a 18-inch infiltration layer with a hydraulic conductivity less than or egual to any natural soils below
the waste but not greater than 1 x 10 -5 cm/sec.

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Surface water drainage controls shall be constructed to prevent erosion of the cap. As determined by the
final Site 9 Cap Design, drainage channels shall be installed in certain areas on the top and perimeter of
the landfill cap to channel runoff away from the landfill.

Slurry Wall

The slurry wall will address 9 VAC 20-80-250 (Sanitary Landfill) and 9 VAC 20-80-210 (Remedial
Reguirements) by providing engineering control to reduce groundwater intrusion and flow through wastes
by diverting up-gradient groundwater flow away from the landfill. This will reduce groundwater levels and
slow contaminant release from the landfill.

Marsh Cap

The marsh cap shall meet the minimum thickness reguirements (2 feet) of Virginia Sanitary landfill cap.
The marsh cap shall provide sound engineering controls per 9 VAC 20-80-250 to help control groundwater
which intrudes the site by being constructed to an elevation (estimated to be 4 feet msl) which would
preclude the possibility of groundwater migration upward through the waste material and reaching the cap
surface. The marsh cap will address 9 VAC 20-80 250 reguirements to control releases or otherwise reduce site
risks by: 1) cutting off potential contact exposure to wastes in the marsh; 2) enhancing evaporation of
contaminated groundwater which flows within the marsh cap; and 3) providing additional sorbing soils through
which the contaminated groundwater must pass before being discharged to the marsh.

Shoreline Protection

The shoreline of Gambo Creek shall be protected against erosion of wastes buried in the marsh. This
protection would be provided where Gambo Creek is within 100 feet of the wastelfill material in the marsh
north of Site 9. Shoreline protection reguirements would be determined during the Remedial Design based
on detailed hydrologic/hydraulic analysis.

Fill In Gambo Creek

South of Site 9, portions of Gambo Creek shall be filled, and restored as wetlands so that Gambo Creek
does not flow within 100 feet of waste/fill material.

Monitoring Wells

A groundwater monitoring network shall be implemented in accordance with RCRA and VSWMR. It shall be
installed at the perimeter of the unit to evaluate any future contaminant transport. The location and
number of monitoring wells, the freguency of analyses, and the types of analyses shall be determined in
the site design and operation and maintenance documents. These documents must be approved by the
EPA and the Commonwealth of Virginia. Groundwater monitoring shall be determined in the site design
and operation and maintenance documents per 9 VAC 20-8-250.D.6 (Assessment Monitoring Program)
and 9 VAC 20-80-310 (Corrective Action Program). The wells shall be installed according to RCRA and
Commonwealth of Virginia construction reguirements.

Surface Water and Sediment

A surface water and sediment sampling and monitoring plan shall be developed as part of the Operation
and Maintenance (0 & M) Plan. The location and number of sampling locations, the freguency of analyses, the
types of analyses, and the duration of monitoring shall be determined in the 0 & M Plan. This plan must be
approved by the EPA and the Commonwealth of Virginia.

Institutional Controls

The Navy shall institute the following institutional controls within 90 days of completion of all remedial

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actions: a real property description notation, Base Master Plan notations, and limited site access. The
Base Master Plan shall note the area as one in which residential development can not occur, shallow
groundwater can not be used, and site access shall be limited. A notation shall be filed in the real property
file maintained at EFA Ches (US Navy) for this site indicating the extent of the area and the fact that solid
wastes are present. The institutional controls shall also include the following: Within 90 days after
completion of the remedy, the Navy shall produce a survey plat prepared by a professional land surveyor
registered by the Commonwealth of Virginia indicating the location and dimensions of the disposal area and
the extent of groundwater contamination. Monitoring well locations should be included and identified on the
survey plat. The plat shall contain a note, prominently displayed, which states the owners future obligation
to restrict disturbance  (excavation or construction) of the property; post-closure use of the property shall
prohibit residential use and access or use of groundwater underlying the property for any purpose except
monitoring and the function of the monitoring systems shall not be disturbed. When landfill closure is
complete, the owner of the property shall submit the survey plat to the local recording authority, and shall
record a notation with the deed (or some other instrument which is normally examined during title search at
the local land recording authority) notifying any potential purchaser of the property that the land has been
used to manage solid waste and the integrity of the cover system or the function of the monitoring system may
not be disturbed.

The Navy shall institute groundwater monitoring to ensure RAOs are being met. The freguency of analysis
and the length of time for groundwater, surface water,  and sediment monitoring shall be developed in the
Operation and Maintenance Plan.

2.9       STATUTORY DETERMINATIONS

Remedial actions must meet the statutory reguirements of Section 121 of CERCLA 42 U.S.C. 9621 as
discussed below.

Remedial actions undertaken at NPL sites must achieve adeguate protection of human health and the
environment, comply with ARARs of both Federal and state laws and regulations, be cost-effective, and
utilize, to the maximum extent practicable, permanent solutions and alternative treatment or resource
recovery technologies. Also, remedial alternatives that reduce the volume, toxicity, and/or mobility of
hazardous waste as the principal element are preferred.

The following discussion summarizes the statutory reguirements that are met by the selected remedy.

0.9.1     Protection of Human Health and the Environment

The selected remedy implements measures to control sources of contamination and exposure to humans
or the environment to residual contamination, as necessary to protect human health and the environment.
This includes permanent notification in local land records of groundwater use restrictions in order to
control exposure of humans to residual contamination in groundwater, and containment of and diversion of
groundwater from contaminant sources by installing an upgradient slurry cutoff wall in order to control
release of contaminants to the environment to levels which are protective of the environment.

Multilayer Cap - The multilayer cap would protect human health and the environment by preventing direct
exposure to contaminated soil and minimizing the potential of contaminant migration to the surface water
and sediment via groundwater.  Removal of surface debris and contaminated surface soils from the
southern portion of the site would remove the potential threat of this debris to both human and ecological
receptors. Implementation of institutional controls will assure that the site will not be used for any
purpose in the future which could damage the cap and potentially expose human and ecological receptors to the
waste in the landfill.

Marsh Cap - The marsh cap would protect against erosion of the waste/fill material and would increase
the separation distance between the waste/fill material and the marsh surface. The marsh cap would
prevent direct contact of the waste/fill materials with ecological receptors. The marsh cap would not
prevent leaching of contaminants from the underlying waste/fill material, however, the cap will be placed at
an elevation which is sufficient to prevent any contaminants from leaching to the surface and
contaminating the surface soils in the cap where the ecological receptors could contact the contaminants.

While contaminant migration from the subsurface is possible, it is unlikely. A small upward gradient exists
from the upper confined aguifer into Gambo Creek which could mobilize contaminants to the surface.
Although this gradient exists, the clay confining unit below the creek is estimated to be approximately
30 feet thick so that the upward flow of groundwater through this waste material would be very small

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(estimated to be 0.25 inches/year).  Tidal flushing is much more significant than flow from the upper
confined aguifer. In addition, the mobility of contaminants in the marsh is considered to be low due to the
types of contaminants.

Option - Option A (construct a slurry wall on the upgradient side of the landfill)  will provide additional
protection of human health and the environment by reducing the potential for groundwater to come into
direct contact with waste materials in the landfill.

Option B2 - Option B2 (shoreline protection along the streambank north of the marsh)  would provide
additional protection of human health and the environment by providing shoreline protection which, will
greatly reduce the potential for waste material to erode from the marsh and migrate further from Site 9.

Option B3 - Option B3 (filling Gambo Creek and restoring it as wetlands in the area adjacent to waste
south of the marsh)  will also provide additional protection of human health and the environment by
lessening the potential for the stream channel of Gambo Creek to erode into the waste/fill material.

2.9.2     Compliance with ARARs

Measures to control sources of contamination and exposure to humans or the environment to residual
contamination may be implemented provided: the groundwater protection standard cannot be practically
achieved; the groundwater is not currently or reasonably expected to be a source of drinking water and is
not hydraulically connected with waters to which contaminants may migrate in concentrations that would
exceed applicable standards; and the measures are consistent with the overall objective of the remedy,
i.e., to control the sources of releases so as to reduce or eliminate, to the maximum extent practicable
further releases of solid waste constituents into the environment that may pose a threat to human health
or the environment [9 VAC 20-80-310.B.2; B.5; C.3]. The selected remedy for Site 9 will satisfy these
criteria.

Multilayer Cap - The cap would meet all relevant and appropriate regulations and federal and state law.
The waste in the landfill would not be situated within 100 feet of a flowing surface water body (Gambo
Creek) as reguired by Virginia regulabons. The toe of the landfill adjacent to the marsh area would be
inundated by the 100-year storm and therefore would be considered to be located in the 100-year
floodplain, however,  the toe of the landfill would be protected against the 100-year flood elevation, as
reguired by Virginia regulations so that no adverse effects to the landfill would occur during this rare
event. Capping would be in compliance with applicable Virginia regulations and exceed the minimum reguirement
set forth in the Virginia sanitary and fill regulations.

Marsh Cap - The marsh cap would comply with the Virginia sanitary landfill regulations for the minimum
thickness of the cap. The marsh cap would not attain all aspects of the Virginia sanitary landfill
regulations (such as the specified maximum permeability of the cap materials),  but these reguirements are not
applicable relevant or appropriate since one of the reguirements of this cap is for it to act as a recharge
area rather than preclude infiltration into the cap.

Option A - Option A will meet all relevant and appropriate regulations and federal and state law.  Option A
will enhance the protectiveness of the multilayer landfill cap.

Option B2 - Option B2 (shoreline protection along the streambank north of the marsh)  would not provide
reguired 100 foot offset from flowing water body; however, Option B2 will provide eguivalent erosion
protection measures and the 100 foot offset is not appropriate.

Option B3 - Option B3 (filling Gambo Creek and restoring as wetlands adjacent to waste south of the
marsh) would comply with the 100 foot offset reguirement from a flowing water body.

2.9.3     Cost-Effectiveness

The selected remedy is cost-effective because it would provide overall effectiveness proportional to the
cost. Although more costly than several other alternatives, the selected alternative would achieve
remediation goals more guickly and efficiently than other alternatives, provide greater long-term protection
of human health and the environment and meet all identified ARARs.

2.9.4     Utilization of Permanent Solutions and Alternative Treatment Technologies or
          Resource Recovery Technologies to the Maximum Extent Practicable

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The selected alternative uses a permanent solution, capping. Capping is a permanent solution and is an
appropriate remedy for landfill waste, soils, and sediments contaminated with SVOCs, metals, and
pesticides. Capping is typical and appropriate for a site of this type.

2.9.5     Preference for Treatment as a Principal Element

The selected remedial action does not use treatment technologies because among other things, treatment
is not practicable for a site of this size.

2.9.6     Documentation of Significant Changes

The selected remedy is the same alternative identified as the recommended alternative in the Proposed
Remedial Action Plan and that was presented to the public at the public meeting held August 27, 1998.

There were no significant changes to the recommended remedial action alternative in the Proposed Plan.

It was determined, after issuance of the Proposed Remedial Acton Plan, that certain corrections were not
incorporated, as intended, in the final Remedial Investigation document. An errata has been filed with the
RI to detail these corrections. Conseguentially, Table 2-2 of this Record of Decision now includes a fish
tissue exposure point concentration for manganese; also, corresponding text has been corrected.

Provisions which address groundwater control reguirements have been revised in order to better describe
these reguirements, not only as supplemental institutional controls, but also as remedial (corrective action)
reguirements which are needed to address site risk. Table 2-1 now contains groundwater COCs, and
Section 2.4  (Summary of Site Characteristics) and Section 2.9 (Statutory Determinations) have been expanded.

Section 2.5.3 of the PRAP contains Remedial Action Objectives (RAOs) which were developed based on the
Preliminary Remediation Goals  (PRGs). RAOS may be modified during the Remedial Design based on more detailed
evaluation. Some of the numerical values in the PRAP were transcribed incorrectly from the RI/FS documents.
This ROD corrects this error.


                              3.0 RESPONSIVENESS SUMMARY

The selected remedy for Site 9 is a capping system. No written comments, concerns, or guestions were
received by the Navy, U.S. EPA, or the Commonwealth of Virginia during the public comment period from
August 20, 1998 to September 18, 1998. A public meeting was held on August 27, 1998 to present the
Proposed Plan for Site 9 and to answer any guestions on the Proposed Plan and on the documents in the
information repositories. A 30-minute presentation was provided during which informal guestions were
addressed. A period was set aside for formal guestions to be recorded by the court reporter. No formal
guestions were asked during the meeting.

A summary of the informal guestions that were asked at the public meeting is provided in Appendix B.
Additionally, a copy of the certified transcript of the Public Meeting is attached in Appendix B.

3.1         BACKGROUND ON COMMUNITY INVOLVEMENT

The Navy and NSWCDL have had a comprehensive public involvement program for several years. Starting in 1993,
a Technical Review Committee (TRC) met on average, twice a year to discuss issues related to investigative
activities at NSWCDL. The TRC was comprised of mostly governmental personnel, however a few private citizens
attended the meetings.

In early 1996, the Navy converted the TRC into a Restoration Advisory Broad  (RAB) and 8-10 community
representatives joined. The RAB is co-chaired by a community member and has held meetings approximately every
four to six months. The Feasibility Study and the Proposed Plan for Site 9 were both discussed at the RAB
meetings and a Site 9 tour was undertaken during a special RAB meeting.

Community relations activities for the final selected remedy include:

The documents concerning the investigation and analysis at Site 9, as well as a copy of the Proposed
Plan were placed in the information repository at the NSWCDL General Library and the Smoot Memorial
Library.

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Newspaper announcements on the availability of the documents and the public comment period/meeting
date was placed in The Journal on August 19, 1998 and the Freelance Star Newspaper on August 20,  1998.

The Navy established a 30-day public comment period starting August 20,  1998 and ending September 18,  1998 to
present the Proposed Remedial Action Plan. No written comments were received during the 30-day public comment
period.

A Public Meeting was held August 27, 1998 to answer any guestions concerning the Site 9 Proposed Plan.
Approximately 11 people, including federal, state and local government representatives attended the meeting.

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                                    APPENDIX A





          COMMONWEALTH OF VIRGINIA CONCURRENCE WITH  THE  SELECTED REMEDY

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APPENDIX B

SUMMARY OF INFORMAL COMMENTS

During the Public Meeting held on August 27, 1998, an overview of the Proposed Remedial
Action Plan for Site 9 was presented during a 30-minute period. The Navy, the Commonwealth of
Virginia, or the EPA have received no written comments from the public During the presentation
informal comments were received from attendees. These comments included the following:

Summary of Comments Received during the Public Meeting

1. What is the difference between the landfill cap and the marsh cap?

It was explained that the landfill cap would be designed to significantly reduce rainfall
infiltration through the cap to the buried waste materials. The marsh cap would be
designed to provide a physical barrier for plants and animals from coming in contact with
contaminated surface sediment in the marsh area. The marsh cap would also be
designed to prevent groundwater from potentially rising to the surface of the marsh and
transporting contaminants to the surface of the marsh cap. The marsh cap would be
designed to provide a sufficient elevation difference between the surface of the marsh
cap and the level to which groundwater may naturally rise. The marsh cap soil would
also be selected so that rainfall infiltration through the cap material would occur.

2. Why is a slurry wall preferred?

It was explained that the slurry wall is an impermeable barrier that prevents groundwater
upgradient of the landfill from passing through buried waste material. Instead,
upgradient groundwater would be directed around the landfill to the north and south.

3. Where is the contaminated groundwater and why wouldn't it be used for drinking water?

It was explained that groundwater generally moves from the west toward the east and
ultimately enters Gambo Creek. The area of contaminated groundwater is therefore
below the marsh between the landfill and Gambo Creek, which is generally considered
to be an area that would not be developed because of the marsh conditions.
Conseguently, it is unlikely that anyone would ever want to use groundwater from below
the marsh for drinking water. In addition, as part of the institutional controls, future use
of groundwater would be prohibited.

4. Why is there such a large difference in costs between the alternatives?

It was explained that the alternatives and options that involve excavation of marsh
materials significantly increase costs.

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 1                         NAVAL SEA SYSTEMS COMMAND

 2                       NAVAL SURFACE WARFARE CENTER
                              DAHLGREN DIVISION
 3

 4                              PUBLIC MEETING

 5
                     THURSDAY, AUGUST 27, 1998, 7:00 P.M.
 6                       KING GEORGE COUNTY COURTHOUSE
                             KING GEORGE, VIRGINIA
 7
                          PROPOSED REMEDIAL ACTION PLAN
 8                         Site 9, Disposal/Burn Area

 9

10

11

12
    USEPA Region III
13  Hazardous Site Cleanup Division
    Federal, Facilities Section
14  Mr.  Bruce Beach
    1650 Arch Street, Philadelphia, Pennsylvania 18107
15
    Virginia Department of Environmental Quality
16  Mr.  David Gillispie
    629 East Main Street,  Richmond, Virginia 23219
17
    Public Affairs Office
18  Commander,  Naval Surface Warfare Center
    Ms.  Jennifer Wilkins
19  17320 Dahlgren Road, Mail Code CD06 Dahlgren, Virginia 22448

20

21                          Reported by:   Lola Gail Serrett
                   FRANCES K. HALEY & ASSOCIATES, Court Reporters
             10500 Wakeman Drive, Suite 300, Fredericksburg, VA 22407
                     PHONE:  (540)898-1527    FAX: (540)898-6154

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 1  August 27,  1998:

 2

 3            There were no formal questions on the floor at this

 4 meeting.

 5

 6

 7
 9

10

11

12

13

14

15

16

17

18

19

20

21

                   FRANCES K. HALEY & ASSOCIATES, Court Reporters
              10500 Wakeman Drive, Suite 300, Fredericksburg, VA 22407
                    PHONE: (540)898-1527    FAX:  (540)-8-98-6154

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 1                  CERTIFICATE OF COURT REPORTER

 2

 3            I,  Lola Gail Serrett, hereby certify that I was the

 4  Court Reporter at the Public Meeting held at King George

 5  Courthouse,  King George,  Virginia, on August 27, 1998, at the

 6  time of the meeting herein.

 7           I,  further certify that the foregoing transcript is a

 8  true and accurate record of the proceeding herein.

 9           Given under my hand this 30th day of August, 1998.

10

11                                              

12

13

14

15

16

17

18

19

20

21

                   FRANCES K. HALEY ASSOCIATES,  Court Reporters
             10500 Wakeman Drive, Suite 300, Fredericksburg, VA 22407
                  PHONE:  (540)898-1527  FAX: (540)898-6154

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                                 APPENDIX C
             APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
                         Regulation
                       16 USC ° 1531 50
                       C.F.R. Part 402
                       4 VAC 15-20-130
                       to 140

                       2 VAC 5-310-10
Classification



Applicable



Applicable


Applicable
     ARAR or TBC

I. LOCATION SPECIFIC

Endangered Species
Act of 1978
Virginia Endangered
Species Regulations

Regulations for the
Enforcement of the
Endangered Plant
And Insect Specifies
Act
The Archaeological     16 U.S.C ° 469       Applicable
and Historical
Preservation Act of
1974

Virginia Natural Area  ° 10.1-209 to 217    To Be
Preserves Act                               Considered
Migratory Bird Area    16 USC °703          Applicable
   Requirement Synopsis
Act requires federal agencies to ensure that
any action authorized by an agency is not likely
to jeopardize the continued existence of any
endangered or threatened species or adversely
affect its critical habitat.

Similar Virginia requirements for submittal and
review of environmental assessments.
                   Requires actions to avoid potential loss or
                   destruction of significant scientific, historical,
                   archaeological data.
                   Allows for preservation of certain significant
                   ecological systems.
                   Protects almost all species of native birds in the
                   U.S. from unregulated "take" which can include
                   poisoning at hazardous waste sites.
                                                                                                                      Applicability to Remedial
                                                                                                                            Alternatives
Potentially affected endangered
species have not been identified.
The remedial action will be
implemented so resources are not
adversely affected should any be
identified in the future.
                                                                                                                      Site is not known to be within a
                                                                                                                      historically significant area. If
                                                                                                                      future resources  are identified
                                                                                                                      actions will be taken to ensure
                                                                                                                      compliance.

                                                                                                                      If specific species are found,
                                                                                                                      actions will be taken to eliminate
                                                                                                                      or minimize degradation to these
                                                                                                                      resources.

                                                                                                                      Remedy will be implemented to
                                                                                                                      ensure that wastes have no
                                                                                                                      impacts to native birds.

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                                                       APPENDIX C

                                APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
                                             SITE 9 DISPOSAL BURN AREA
                                            NSWCDL, DAHLGREN, VIRGINIA
      ARAR or TBC

Chesapeake Bay
Preservation Area
Designation and
Management
Regulations
Standards for
Owners and
Operators of
Hazardous Waste
Treatment, Storage,
and Disposal
Facilities
Virginia Hazardous
Waste Management
Regulations
  Regulation

9 VAC 10-20-10 to
280
Classification

Relevant and
Appropriate
40 C.F.R.  264.18 (b)  Applicable
9 VAC 20-60-10 to
1480
Applicable
   Requirement Synopsis

Requires that certain locally designated tidal
and non-tidal wetlands and other sensitive
areas be subject to limitations regarding land-
disturbing activities, removal of vegetation, use
of impervious cover, erosion and sediment
control, and stormwater management.

Applies to treatment, storage, or disposal of
hazardous waste within a 100 year floodplain
area.
Applies to treatment storage, or disposal of
hazardous waste.
Applicability to Remedial
       Alternatives

Remedy implementation will
require construction activities.
Actions will address the regulatory
requirements.
                                                                          Remedy implementation may
                                                                          produce incidental hazardous
                                                                          wastes within the 100 year
                                                                          floodplain area, although none are
                                                                          expected. Hazardous wastes
                                                                          encountered will be managed
                                                                          consistent with Federal and
                                                                          Virginia requirements.
                                                                                               Hazardous wastes encountered
                                                                                               will be managed consistent with
                                                                                               Federal and Virginia requirements.
Virginia Water
Protection Permit
Regulation
9 VAC 25-210-10 to
260
Applicable
Facility or activity design must adequately
address the issues arising from locating
facilities in wetlands and delineated wellhead
protection areas  (determined vulnerable).
Remedy implementation will
impact a wetland area. The
remedy will minimize impacts to
the wetlands and will restore
wetlands areas on the facility.

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                                                        APPENDIX C
        ARAR or TBC

Executive Order
11988, Protection of
Floodplains
Executive Order
11990, Protection of
Wetlands

Clean Water Act of
1972  (CWA) Section
404

Virginia Wetlands
Policy

Procedures for
Implementing the
Reguirements of the
Council on
Environmental
Quality on the
National
Environmental Policy
Act
                                  APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
                                                SITE 9 DISPOSAL BURN AREA
                                               NSWCDL, DAHLGREN, VIRGINIA
Regulation

40 C.F.R. 6, Appendix
A; excluding Sections
6(a) (2),6(a) (4) .
6(a)(6); 40 C.F.R.
6.302
40 C.F.R. 6.
Appendix A
33 U.S.C. °°1344
4 VAC 25-380-10 to
40

40 C.F.R.
Part 6
Appendix A
                                                Classification
Applicable
        Reguirement Synopsis

Facilities or activities located within the
floodplain must comply with this order.
Applicable
Action to minimize the destruction, loss, or
degradation of wetlands.
Applicable


Applicable
EPA's policy for carrying out the provisions of
Executive Order 11990  (Protection of
Wetlands).  No activity that adversely affects a
wetland shall be permitted.
Applicability to Remedial
           Alternatives

Site is partially within Gambo
Creek and is therefore partially in
the 100 year floodplain. Remedy
will be installed in the floodplain
and will be designed and
constructed to minimize impacts to
floodplain resources.

Portions of the site is in Gambo
Creek and are characterized as
wetlands. Remedy
implementation will be designed
and constructed to mitigate
wetland losses.
Portions of the site are in Gambo
Creek and are characterized as
wetlands. Remedy
implementation will be designed
and constructed to mitigate
wetland losses.

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                                                           APPENDIX C

                                      APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
                                                    SITE 9 DISPOSAL BURN AREA
                                                    NSWCDL, DAHLGREN, VIRGINIA
                        Regulation
                                           Classification
                       40 CFR 258.60-61
        ARAR or TBC

II. ACTION SPECFIC

Capping /Closure
and Post Closure for
Municipal Solid Waste
Landfills

Virginia Solid Waste   9 VAC 20-80-10 to   Applicable
Applicable
Management
Regulations

Military Munitions
Rules
                       790
                        (40 CFR 260-266 and To Be
                       270)                Considered
              managed in compliance with the
                        Reguirement Synopsis
Reguirements for final cover systems to
minimize infiltration and erosion. Reguirements
for at least a 10 year post closure care period
including maintaining integrity and effectiveness
of the final cover. Maintenance of groundwater
monitoring and landfill gas monitoring systems.
                     Recently promulgated regulations in response
                     to Section 107 of the Federal Facilities
                     Compliance Act of 1992 identifying when

                     conventional and chemical military munitions
                     become hazardous waste. Applications of the
                     rules are a 'TBC' until adopted by states
                     authorized to administer RCRA.
                                                      Applicability to Remedial
                                                            Alternatives
Installation of Virginia Sanitary
Landfill Cap reguires adherence to
these regulations or eguivalent
performance standards at Site 9.
                                                      Ordinance-related wastes
                                                      potentially buried at Site 9 will be


                                                      rules.
DoD Guidance on
Property
Contaminated with
Ammunition,
Explosives or
Chemical Agents
                        DoD 6055.9-STD
                                            To Be
                                            Considered
                     Dod guidance document stipulating policy and
                     procedure to provide protection of personnel
                     resulting from DoD ammunition, explosives or
                     chemical agent contamination. Includes
                     property currently or formerly owned, leased or
                     used by DoD, and calls for identification and
                     control at active installations, and provides
                     guidance for potential land disposal.
                                                      Capping of Site 9 will be
                                                      completed to be consistent with
                                                      DoD policy and procedures to
                                                      address safety issues.

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                                                            APPENDIX C
        ARAR or TBC

Erosion and
Sediment Control
Regulations
Virginia Solid Waste
Management
Regulations
AIR
Gas Collection
Vents
and
Gas Collection and
Vents
                                       APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
                                                     SITE 9 DISPOSAL BURN AREA
                                                    NSWCDL, DAHLGREN, VIRGINIA
          Regulation

          4 VAC 50-30-10 to
          110
          9 VAC 20-80-250

          9 VAC 20-80-210

          9 VAC 20-80-310
                    Classification

                    Applicable
                    Applicable

                    Applicable

                    Applicable
CAA Section 101 42  Relevant and
U.S.C. °7401,and 40 Appropriate
C.F.R. 52
          40 C.F.R.  52
                              Relevant and
                              Appropriate
   Reguirement Synopsis

Erosion and sediment control plans are to be
submitted for land-disturbing activities, and be
in compliance with of the locality and/or local
soil and water conservation district.
Permanent Closure Criteria governing: Access
Restriction, Closure and Post Closure Care,
Gas Management, Drainage Layer, Final
Cover, Run-on Run-off controls, Site
Monitoring, Control of Groundwater Intrusion,
Groundwater Corrective Action and compliance
with other permanent closure reguirements.
File an Air Pollution Emission Notice (APEN)
with the State to include estimation of emission
rates for each pollutant expected. Design
system to provide an odor-free operation.

Predict total emission of volatile organic
compounds (VOCs)  to demonstrate emissions
do not exceed 450 Ib/hr, 3,00 Ib/day, 10 gal/day
or allowable emission levels from similar
sources using Reasonably Available Control
Technology  (RACT).
    Applicability to Remedial
         Alternatives

Construction activities will disturb
the land in the vicinity of the site.
Activities will address Virginia
erosion and sediment control
reguirements.

Virginia Solid Waste Management
reguirements need to be
addressed with the installation of
the cap at Site 9. Eguivalent
performance standards will meet
Final Cover reguirements.
Design of capped area anticipated
to include venting to ensure cap
functions as intended.
                                                                                             Design of capped area to
                                                                                             demonstrate that decomposition
                                                                                             gases address regulatory
                                                                                             reguirements.

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APPENDIX C

APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
SITE 9 DISPOSAL BURN AREA
NSWCDL, DAHLGREN, VIRGINIA
ARAR or TBC

Gas Collection and
Vents
Gas Collection and
Vents
Regulation
Classification
40 C.F.R. 60 Subpart Applicable
WWW and CC
CAA Section 112(D) Relevant and
42 U.S.C. °7412 Appropriate
Requirement Synopsis

New Source Performance Standard (NSPS) for
municipal landfills: Landfill Emission Rule; deals
with non-methane organic compounds.
Emission Standards for new stationary sources.
Applicability to Remedial
Alternatives

NSPS requirements include
calculations for gas emission
rates, limitations on non-methane
emissions, monitoring and
recordkeeping. Site 9 gas vent
emissions are not expected to be
significant.

NSPS for venting. Confirmation
that standards are not exceeded
will be addressed.
Gas Collection and
Vents

Visible and Fugitive
Dust Emissions
Standards of
Performance for
Toxic Pollutants
CAA Section 118
42 U.S.C. °7418

9 VAC 5-30-20
Relevant and
Appropriate

Applicable
9 VAC 5-30-60 Applicable
9 VAC 5-50-60 to 120 Applicable
9 VAC 5-50-160 to Applicable
230
Control of air pollution from Federal Facilities.

Control of Particulate Matter (TSP)

Control of Particulate Matter (PM 10)

Standards for visible and/or fugitive dust
emissions.

Standards of performance for toxic pollutants.
NSWCDL is a Federal Facility and
will address all CAA requirements.

Visible and Fugitive Dust
emissions from remedial actions
shall be controlled, as necessary.
Toxic pollutants are not expected
during remedial actions; however,
corrective action will be performed
if problems arise.

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APPENDIX C
APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
SITE 9 DISPOSAL BURN AREA
NSWCDL, DAHLGREN, VIRGINIA
ARAR or TBC
Regulation
Classification
WATER
Criteria for 49 C.F.R. 257.3-3(a) Potentially
Classification of Solid Applicable
Waste Disposal 33 U.S.C. °°1342
Facilities and
Practices
Criteria for 49 C.F.R. 257.3-3(a) Applicable
Classification of Solid
Waste Disposal 33 U.S.C. °°1288
Facilities and
Practices
Criteria for 49 C.F.R. 257.3-4 and Applicable
Classification of Solid Appendix 1
Waste Disposal
Facilities and
Practices
Clean Water Act
Water Quality &
Groundwater
Standards
33 U.S.C.
seq.
'1251 et
9 VAC 25-260-190 to
240
Relevant and
Appropriate

Relevant and
Appropriate
Requirement Synopsis
Applicability to Remedial
Alternatives
A facility shall not cause a discharge of
pollutants into the waters of the U. S. that is in
violation of the substantive requirements of the
NPDES under CWA Section 402, as amended.
A facility or practice shall not cause nonpoint
source pollution of the waters of the U. S. that
violates applicable legal substantive
requirements implementing an areawide or
Statewide water quality management plan
approved by the Administrator under CWA
Section 208, as amended.

A facility or practice shall not contaminate an
underground drinking water source beyond the
solid waste boundary or a court- or State-
established alternative.
Criteria and standards for groundwater quality.
Virginia regulation provides basis for risk-based
remediation and discharge limitations.
No discharges under the remedy
are planned. In addition, NPDES
program is delegated to Virginia
(VPDES). Potentially applicable
for situations potentially not
covered by VPDES.

Potential future releases to
groundwater could migrate to the
stream. Ongoing monitoring will
address the requirement.
Potential future releases to
groundwater could contaminate
groundwater over risk-based
criteria. Ongoing monitoring will
address the requirement.

Provides basis for risk-based
decision making, establishes
standards for groundwater quality.
Ongoing monitoring at Site 9 will
address the requirement.

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                                                          APPENDIX C
        ARAR or TBC
Surface Water
Standards
Virginia Pollution
Discharge
Elimination System
(VPDES)

Virginia Pollution
Abatement  (VPA)
Permit Regulation

Virginia Solid Waste
Management
Regulations
Stormwater
Management
Regulations
                                      APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS
                                                     SITE 9 DISPOSAL BURN AREA
                                                    NSWCDL, DAHLGREN, VIRGINIA
Regulation
9 VAC 25-260-5 to
150,  160-170,310
9 VAC 25-31-10 to
940
9 VAC 25-32-10 to
300
9 VAC 20-80-250 (D)
Classification

Relevant and
 Appropriate


Applicable
Applicable
Applicable
      Reguirement Synopsis

Standards and criteria for State waters,
 including wetlands.
Procedures and reguirements for discharging
pollutants into surface waters, or any activity
which impacts physical, chemical or biological
properties of surface waters.
Groundwater Monitoring Design
                         4 VAC 3-20-10 to 251
                       Applicable
                      Criteria for Stormwater Management.
Applicability to Remedial
               Alternatives

Provides standards for evaluating
 State waters and wetlands at Site
9.

Capping of Site 9 is not expected
to produce waste liguids that
would be discharged to surface
waters. Any future activities or
groundwater monitoring (e.g.
generation of purge water) will
address regulatory reguirements.
completion of additional soil
borings, monitoring wells and
subsurface investigations will be
consistent with regulatory
reguirements.

Design of Site 9 cap will include
applicable Stormwater
management reguirements.

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