PB96-963906
EPA/ROD/R03-96/222
August 1996
EPA Superfund
Record of Decision:
Patuxent River Naval Air Station,
St* Mary's County, MD
7/29/1996
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anta
RECORD OF DECISION
FORMER SANITARY LANDFILL
NAVAL AIR STATION PATUXENTRIVER,
MARYLAND
Department of the Navy
Commanding Officer
Naval Air Station.
22268 Cedar Point Road
Patuxent River, Maryland 20670-5409
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DECLARATION
Site Name and Location
Former Sanitary Landfill (Site^l 1), Naval Air Station Patuxent River
Patuxent River, St. Mary's County, Maryland.
Statement of Basis and Purpose
This decision document presents the selected interim remedial action for Operable Unit 1
(OU1) of the Former Sanitary Landfill site, at the U.S. Naval Air Station Patuxent River,
MD, which was chosen in accordance with the requirements of the Comprehensive
Environmental Response, Compensation, and Liability Act of 1980 (CERCLA), as amended
by the Superfund Amendments and Reauthorization Act of 1986 (SARA) and, to the extent
.practicable, the National Oil and Hazardous Substances Pollution Contingency Plan (NCP).
This decision document explains the factual and legal basis for selecting the remedy for this
site.
The Maryland Department of the Environment (MDE) concurs with the selected interim .
remedy. The information supporting this interim remedial action decision is contained in the
administrative record for this site.
Assessment of the Site
Actual or threatened releases of hazardous substances from this site, if not addressed by
implementing the interim response action selected in this Record of Decision (ROD), may
present an imminent and substantial threat to public health, welfare, or the environment
Description of the Selected Remedy
OU1 is the first of two planned for the site. OU1 will reduce contaminants emanating from
and degradation of groundwater beneath the Former Sanitary Landfill ("the Landfill"). The
second operable unit (OU2) will address groundwater, surface water, and sediments at the
site. The leachate collection system will be evaluated and upgraded during the remedial
design and the remedial action. Although not part of the site, the adjacent Current Sanitary
Landfill will be capped simultaneously under state landfill closure regulations. OU2 is
expected to be the final remedial action for the site. This Record of Decision has been
developed for OU1 at the Former Sanitary Landfill. This interim remedy will reduce the
potential of human exposure to wastes remaining at the landfill, precipitation filtering
through landfill waste, and the potential risk posed by inhalation and ingestion of
contaminated surficial soil at the landfill. This interim action will allow for the continued
investigation of the landfill while evaluating final remedial options for groundwater, surface
water, and sediment at the site. Lastly, this interim action is consistent with the long-term
remedial goals for the Former Sanitary Landfill.
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The major components of the selected remedy include the following:
• A RCRA Subtitle D cap will be constructed on the Landfill. The Current Sanitary
Landfill (10 acres) will be capped at the same time as the Landfill (6.5 acres) since a leachate
collection system connects the landfills together.
• Groundwater and leachate collection system monitoring will be conducted on a
regular basis. The leachate collection system will be modified or upgraded to intercept
leachate from the decomposition of the wastes and groundwater intrusion to the maximum
. extent practicable. Leachate will be treated, if required, before discharge to the publicly
owned treatment works (POTW).
• A landfill gas treatment system will be installed and used to treat landfill gas before
discharge to the atmosphere.
• Landfill gas monitoring will be conducted on a regular basis.
• Wetlands impacted by implementation of the interim remedy will be replaced. A
wetland delineation shall be conducted during the remedial design. Acreage replaced shall be
one for one for wetlands permanently lost, but one for one replacement shall be adjusted by
considering full function, value, and time factors.
• Land use controls in the form of deed restrictions will be exercised to limit property
use to maintain the integrity of the impermeable cap and to limit possible exposure to
landfilled wastes. Land use access will be restricted except to authorized personnel required
to maintain the cap, the leachate collection system, and landfill gas/treatment system.
Declaration of Statutory Determinations
This interim action is protective of human health and the environment and is intended to
provide adequate protection until a final ROD is signed; this interim action complies with
Federal and State requirements that are legally applicable or relevant and appropriate for this
limited-scope action and is also cost-effective. This interim action does not intend to utilize
permanent alternative treatment (or resource recovery) technologies to the maximum extent
practicable for this operable unit. Although this interim action is not intended to address fully
the statutory mandate for pennanence*and treatment to the maximum extent practicable, this
interim action does utilize permanence and thus is in furtherance of that requirement.
The preamble of the NCP states that treatment is the preferred means by which principal
threats posed by sites should be addressed. The preamble characterizes principle threats as
"waste that cannot be readily controlled in place, such as liquids, compounds ... Treatment is
less likely to be practicable when sites have large volumes of low concentrations of material,
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or when waste is very difficult-tb handle and treat" (55 Fed. Reg. 8,703 [March 8,1990]).
The waste material found in'the landfill, neither liquid nor highly mobile, can be readily
controlled in place. The removal of large amounts of waste would be difficult to handle and
treat, and could significantly increase the risk posed by a release of contaminants Because
this interim action does not constitute the final remedy for the Former Sanitary Landfill site,
the statutory preference for remedies that employ treatment that reduces toxicity, mobility, or
volume as a principal element will be addressed by the final response action. The final action
is planned to address fully the threats posed by conditions at the Former Sanitary Landfill.
A five-year review is necessary because this interim 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 continues to
provide adequate protection of human health and the environment. This five, year review is
consistent with Section 121© of CERCLA, 42 U.S.C. § 9621(c). Because this is an interim
action ROD, review of this site and of this remedy will be ongoing as EPA and the Navy
continue to develop final remedial alternatives for OU2 at the Former Sanitary Landfill.
Capt. E. L. Standridge y Date
Commanding Officer
Naval Air Station, Patuxent River, Maryland
Thomas C. Voltaggio,
Division Director HazardlSus-Waste Management
U.S. Environmental Protection Agency, Region HI
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DECISION SUMMARY
TABLE OF CONTENTS
1.0 SITE NAME, LOCATION, AND DESCRIPTION 1
s
2.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES 2
3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION 6
4.0 SCOPE AND ROLE OF INTERIM REMEDIAL ACTION 7
5.0 SITE CHARACTERISTICS 8
6.0 SUMMARY OF SITE RISKS 11
7.0 DESCRIPTION OF ALTERNATIVES 13
8.0 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES 16
9.0 SELECTED REMEDY 22
10.0 STATUTORY DETERMINATIONS 25
FIGURES - FIGURE 1 THROUGH 8
APPENDIX A - HUMAN HEALTH RISK ASSESSMENT/EXPOSURE
ASSESSMENT
APPENDIX B - CONTAMINANTS OF CONCERN/APPROXIMATE RISK
LEVELS
APPENDIX C - APPLICABLE OR RELEVANT AND APPROPRIATE
REQUIREMENTS (ARARs)
APPENDIX D - MARYLAND DEPARTMENT OF THE ENVIRONMENT
CONCURRENCE LETTER
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DECISION SUMMARY
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1.0 SITE NAME. LOCATION. AND DESCRIPTION
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1.1 Site Name & Location .
Naval Air Station Patuxent River (NAS) is a 6,800-acre naval installation located in St.
Mary's County, Maryland (Figure 1). The installation is located at the confluence of the
Patuxent River and Chesapeake Bay and has been in operation since 1942. The
installation is bordered by residential, park, industrial, and commercial properties.
Approximately 11,000 military, civilian, and contractual personnel work at the
installation.
The Former Sanitary Landfill is approximately 1.5 miles southeast of the main entrance
(gate 2) near the southern border of the installation and adjacent to the intersection of
State Route 235 and Hermanville Road (Figure 2). Adjacent and down gradient to the
Former Sanitary landfill is the Current Sanitary Landfill (Figure 3). For the purposes of
this document the Former Sanitary Landfill will be referred to as the landfill.
1.2 Description
The landfill is approximately 6.5 acres in size and operated from 1974 to 1980.
Presently, the landfill is covered with two feet of soil and is heavily vegetated. The
landfill is surrounded on all sides by a predominantly coniferous forest and two
intermittent streams to the east and west. The surrounding wooded area is occasionally
used by installation personnel for recreational purposes such as hiking, bird watching,
and hunting. Currently, the area is accessible to installation personnel by foot and a gate
at the entrance limits vehicular access. The landfill is within l/2 mile of residential
dwellings outside the confines of the installation.
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2.0 SITE HISTORY ANP ENFORCEMENT ACTIVITIES
2.1 History
Disposal operations at the landfill began in April 1974 which consisted of placing solid
waste in 10 foot lifts and 50 foot working faces. Once the solid waste was placed in the
lifts, it was covered with soil from the borrow area next to the landfill. The borrow area
for the landfill during its operation is the area now known as the Current Sanitary
Landfill. It is estimated that the landfill received approximately 22,500 tons of plastic
and paper trash. It is estimated that the landfill received approximately 43 tons of oil
contaminated soils and liquid wastes consisting of; petroleum-oil lubricants, solvents,
thinners, paints, small amounts of pesticides, and photographic wastes. The liquid wastes
were predominantly residues left in cans, rags and absorbents. The landfill operated
under Maryland Department of the Environment (MDE) Solid Waste Permit number 79-
18-08-04A from March 1, 1979 until September of 1980 when the landfill was closed.
Located next to the landfill is the 10-acre Current Sanitary Landfill. Disposal operations
began at the Current Sanitary Landfill when the landfill closed in 1980. The Current
Sanitary Landfill is regulated under the Resource Conservation and Recovery Act
(Subtitle D) (Solid Waste Disposal Act), as administrated by the MDE Solid Waste
Program. An estimated 145,000 tons of municipal solid waste were disposed of at the
Current Sanitary Landfill. The Current Sanitary Landfill received waste as defined under
its Refuse Disposal Permit for municipal landfills from September 1, 1980 to November
17, 1991. In October 1991, the NAS began transporting municipal wastes to the St.
Andrews Landfill in St. Mary's County, Maryland. This was with the permission of the
St. Mary's County Commissioners in a letter dated October 1, 1991. From November
18, 1991 to May 27, 1994, the Current Sanitary Landfill accepted rubble fill only as per
Code Of Maryland Regulation (COMAR) 26.04.07.13. From May 28, 1994 to
September 30, 1994, the Current Sanitary Landfill accepted clean fill only. The purpose
of this waste acceptance policy change was due to the amount of fill area remaining. On
November 14, 1994, NAS provided verbal notification to the State that the Current
Sanitary Landfill was closed on September 30, 1994:
During construction of the Current Sanitary Landfill, a leachate collection system was
extended along the downgradient perimeter of the landfill. The leachate collection
system is intended to intercept leachate generated by the wastes as a result of
groundwater intrusion and precipitation infiltration. The system connects the two
landfills, therefore, any monitoring of the system includes leachate from both landfills.
The leachate is sent via underground piping to the St. Mary's Metropolitan Commission,
Pine Hill Run Wastewater Treatment Facility, for treatment and discharge. Monthly
monitoring of the leachate began in January 1985. Flow varies from a low of 12,000
gallons per day to a high of 25,000 gallons per day. Currently, the leachate is sampled
and analyzed quarterly.
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In May of 1985 four 4-inch PVC monitoring wells were constructed as part of a
Confirmation Study performed by CH2M Hill. All four wells are permitted with the
State of Maryland (SM-81-1568 through 1571). The wells range (three downgradient
and one upgradient) in depth from 32 to 43 feet. On March 13, 1986, NAS began
submitting an annual Landfill Annual Report to the State of Maryland. The report
included monthly groundwater elevations, leachate data, and the amount of waste
deposited. During the time period of February 7 to March 14 and June 26 to July 21,
1989, five additional monitoring wells were installed as part of the Hydrogeologic Study
of the Former and Current Landfills, conducted by CH2M Hill. Two wells were installed
in the first clay layer 32 to 43 feet below ground surface and the remaining three were
installed in the next lower clay layer approximately 80 to 85 feet below ground surface.
All five wells are permitted by the State of Maryland (SM-81-4016 through 4020).
Initially (August 1985), the State of Maryland periodically sampled the wells. Then on
September 23, 1992, the State of Maryland requested the submission of a Landfill
Sampling and Analysis Plan. The State of Maryland decided to no longer collect and
analyze samples from the groundwater monitoring wells (the last MDE sampling event
was December 1992) and on November 2, 1992, NAS submitted a revised landfill
sampling and analysis plan. On January 1, 1993, NAS began quarterly sampling of the
wells. Since 1993, the monitoring well information has been included in the Landfill
Annual Report. Surface water monitoring data was collected in June 1974 from the
seasonal streams on either side of the landfill. Additional surface water samples were
collected in 1985 and 1987.
2.1.1 Previous Investigations
The Department of the Navy (DON) issued guidance in the 1980's for all installations to
perform hazardous waste assessments of sites as a result of past disposal activities. Fred
C. Hart and Associates was contracted by Chesapeake Division to perform the task and in
March 1984, the Initial Assessment Study of Naval Air Station Patuxent River. Maryland
was completed. The landfill was one of 31 sites identified in the 1984 report, and it was
recommended for further study because of its potential contribution to surface water
and/or groundwater contamination.
The first Groundwater Monitoring Plan and Quality Report was prepared by Beavin
Company on March 20, 1986. This report contained the water level elevation and water
quality data from sampling events. The State acknowledged receipt of this report and
requested additional information about the groundwater. This request led to the eventual
development of a hydrogeologic investigation.
The first sanitary landfill utilization report entitled Sanitary Landfill Utilization Report
was prepared by Beavin Company on March 5, 1986. The report identified the Current
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Sanitary Landfill as beginning operations in September of 1980 and the Former Sanitary
Landfill ending operations in September of 1980.
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The report stated that the Current Sanitary Landfill was constructed using drawings
developed under contract N62477-77-C-0068. The Current Sanitary Landfill is underlain
with a clay liner and the slopes are covered with a synthetic liner. A leachate collection
system was installed along the perimeter of the landfills and the leachate is collected and
discharged to the sanitary sewer system which is conveyed to the St. Mary's
Metropolitan Commission Pine Hill Run Wastewater Treatment Plant. The report also
provided a solid waste characterization report.
The Confirmation Study Report (site investigation), prepared by CH2MHill, was
conducted in 1987 to verify the presence of contamination based on the Initial
Assessment Study. The investigation supports the previous study and the site was ,
recommended for the next phase of the Navy's Installation Restoration Program.
In 1988, A. T. Kearny, Inc. and The Earth Technology Corporation conducted a
Resource Conservation and Recovery Act (RCRA) Facility Assessment of NAS. The •
RCRA Facility Assessment (RFA') Phase n Report identified the Former Sanitary
Landfill as Solid Waste Management Unit (SWMU) 47. The RFA noted that paper,
plastics, cardboard, hospital wastes, cesspool/sewage sludge, demolition/construction
debris, landscaping wastes, petroleum-oil lubricant (POL) products, paints, antifreeze,
solvents, pesticides, asbestos, and photo lab wastes were deposited in the Former
Sanitary Landfill from 1974 to 1980.
In 1990, a Hvdrogeological Investigation of the Current and Former Sanitary Landfills
was conducted by CH2MHill to determine groundwater flow, elevation, conductivity, pH,
and temperature.
The Interim Remedial Investigation (IRI) was part one of the two phase Remedial
Investigation of the Installation Restoration Program. The ERI was conducted in 1991 by
CH2MHill to determine the human health risk posed by the site. The IRI only partially
characterized risk to human health at the site because insufficient information was
collected to evaluate environmental risk. EPA subsequently supplemented the human
health risk assessment at the site to complete the human health risk assessment. The IRI
Report was finalized in February 1994.
In August 1995, the GORE-SORBER— Screening Survey (soil gas survey) was
conducted. Samples were taken at intersections of a 100 by 100 ft. grid network. The
total number of samples collected was 57. The information from this sampling event will
be used to determine the need for possible treatment of the landfill gases and new
monitoring well locations.
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2.2 Enforcement Actions
To date, no Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA) and/or RCRA enforcement actions have been taken at Site 11, the Former
Sanitary Landfill (CERCLA landfill).
On April 4, 1987 MDE issued a Notice of Violation (NOV) for the Current Sanitary
Landfill for not complying with the terms and conditions of the permit. As a result of the
NOV, stricter monitoring controls were enforced. The NOV required the following:
•Modification of the existing landfill to control leachate migration, management and
disposal.
•Preparation of a Groundwater Monitoring Plan with a discussion of the underlying
groundwater quality and fluctuations.
•Submission of a monthly leachate monitoring report.
•Submission of a deed amendment.
•Performance of monthly monitoring of well water elevations for submission with the
landfill utilization annual report.
The Navy formally responded to the NOV by sending information that showed the Navy
was in compliance with the terms and conditions of the permit. In 1995, additional
measures were undertaken to monitor the landfills. The measures are as follows:
•A flow meter was installed in May 1995 to keep a constant reading on leachate being
collected and sent for treatment.
•From April to June 1995, sediment and erosion control structures were repaired, the
Current Sanitary Landfill site was graded to drain, and the slopes were stabilized.
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3.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION
Community participation requirements in CERCLA Sections 113(k)(2)(B)(I-v) and 117
have been met for this interim action.
A news release announcing the Proposed Plan availability, thirty-day comment period,
and public meeting was sent to the Enterprise Newspaper. The thirty-day public
comment period was held from September 6, 1995 through October 6, 1995 and the
public meeting was held on September 15, 1995. At the public meeting, representatives
from U.S. Environmental Protection Agency (EPA), MDE, NAS, and Engineering Field
Activity Chesapeake presented a summary of the site conditions and the interim remedial
alternatives under consideration and answered questions presented by the public.
Responses to the comments received during the public meeting are included in the
Responsiveness Summary, which is part of this Record of Decision (ROD). No written
public comments were received during the comment period.
This decision document presents the selected interim remedial action for the Former
Sanitary Landfill at the Naval Air Station, Patuxent River. The remedy has been chosen
in accordance with CERCLA, as amended by Superfund Amendments and
Reauthorization Act (SARA), and, to the extent practicable, the National Contingency
Plan (NCP). The decision for this interim remedial action is based on the administrative
record.
The IRI for the landfill was released to the public on August 8, 1994. Both the IRI and
the Proposed Plan were made available to the public in the information centers located at
the NAS and Lexington Park Public Libraries.
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SRIM REMEDIAL ACTION
Past disposal operations at the landfill have contaminated soil, groundwater, sediment
and surface water. The Navy has decided to manage the remediation of the landfill in
phases or Operable Units (OUs). An OU is defined by the National Oil and Hazardous
Substances Pollution Contingency Plan (40 CFR 300.5)(NCP), as a discrete action which
is an incremental step toward comprehensively mitigating site problems. The NCP (40
CFR 300.430(a)(l)(ii)(A)) states "Sites should generally be remediated in operable units
when early actions are necessary or appropriate to achieve significant risk reduction
quickly, when phased analysis and response is necessary or appropriate given the size or
completion of total site cleanup."
The interim remedial action (IRA), to be implemented as Operable Unit One (OU1), will
reduce the potential risk to human health and the environment associated with the
landfill. The IRA consists of a RCRA Subtitle D cap and a passive landfill gas collection
system. The landfill gas will be treated and monitored. Operable Unit two (OU2) will
evaluate groundwater, surface water, and sediment contamination to evaluate the
performance of the cap and determine if further remedial actions are necessary.
This IRA will reduce the long-term risk of possible exposure to contaminants originating
from the landfill. The cap will be designed to allow for the control, treatment, and
monitoring of landfill gases. The cap will also reduce vertical infiltration of
precipitation. The amount of leachate generated is expected to decrease because the
landfill will be capped. During the remedial design, the leachate collection system that
connects the Former and Current landfills will be evaluated and upgraded. In addition,
the cap will limit possible exposure to landfill wastes. The interim remedial action is
consistent with long-term remedial goals for the site.
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5.0 SITE CHARACTERISTICS
5.1 Topography, Hvdrogeologv, Geology
Surface elevation ranges from 70 to 120 feet above mean sea level. Along the perimeter
of the site, surface elevations drop 10 to 20 feet. Surface water drains from the site into
two intermittent streams that flow into Pond 3 located approximately 2,500 feet to the
north. Pond 3 drains into Pine Hill Run to the east, which discharges to the Chesapeake
Bay.
Groundwater elevation ranges from 50 to 80 feet above mean sea level (see Figure 4).
Groundwater flow in the vicinity of the landfill is primarily north northeast.
Groundwater originates from outside the installation and flows toward Pond 3 and Pine
Hill Run. It is estimated that the average groundwater flow rate is 30 feet per year.
Soil at the site consists of unconsolidated coastal plain sediments. There are essentially
two lithologic units. The first unit consists of sands and silty sands with layers of clays
and gravel. This occurs at elevations less than 50 feet above mean sea level and again at
elevations greater than 70 feet. The second unit consists of clays and silty clays and
occurs at elevations between 50 and. 70 feet above mean sea level (see Figures 5-8).
5.2 Nature and Extent of Contamination
No surface soil samples were collected at the landfill because clean soil was used to
cover landfilled wastes. Wastes in the landfill have never been sampled and analyzed.
Landfill wastes are not typically sampled because they are not homogenous. However, a
soil gas survey was performed which revealed the presence of the same volatile organic
compounds (VOCs) (benzene, carbon disulfide, chloroform, 1,1-dichloroethene, 1,2-
dichloroethane, trichloroethene, and vinyl chloride) found in groundwater and surface
water at the site. Therefore, the source of groundwater contamination must be the wastes
present in the landfill. Contaminants of concern (COCs) identified during the previous
investigations are presented in the table below. A detailed explanation of each COC and
the base-line risk assessment can be found in the Summary of Risks section.
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TABLE OF COCs
Contaminants of Concern .
Volatile Organic Compounds
Benzene
Carbon Disulfide
Chloroform
1,1-Dichloroethene
1,2-Dichloroethane
1,4-Dichlorob enzene
Methylene Chloride
1,2,3-Trichloropropane
1,1,2,2-Tetrachloroethane
Tetrachloroethene
Trichloroethene
Vinyl Chloride
Concentration
(parts per billion)
10
36
9
9
3
7
190
1
1
3
1
13
Media
Groundwater
Groundwater
Groundwater
Groundwater
Groundwater
Groundwater
Groundwater
Groundwater
Groundwater
Groundwater &
Surface Water
Groundwater &
Surface Water
Groundwater
Inorganic
Arsenic
Beryllium
Lead
Manganese
Thallium
1.7
0.99
64
2310
8.9
Groundwater
Groundwater
Groundwater
Groundwater
Groundwater
5.3 Potential Route of Contaminant Migration and Route of Exposure
The most likely pathway of exposure for a worker at the site is contact with the landfill
contents or surface soil that has been contaminated by the landfill contents.
Contaminants could be absorbed through the skin or ingested. The seasonal streams that
flow adjacent to the landfill may present a risk if an individual possibly got their hands
and feet wet in the stream. Also, the potential of a well being dug in the shallow aquifer
for the purpose of supplying drinking water could present a risk. Although leachate
generated is a pathway for the migration of contamination, it was not considered an
exposure pathway because the leachate is collected via underground pipes and is
discharged directly to the publicly owned wastewater treatment facility.
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5.4 Population and Environmental Areas
Presently, the groundwater is "not a drinking water source and there are no plans to use it
as such in the future. Civilian and Navy personnel who hunt game or participate in
nature walks in the area of the site could possibly be exposed to fugitive gas emissions
and contaminated surface runoff. Also, wildlife in the area could possibly be exposed to
contamination similar to human exposures. Exposures could occur from drinking surface
water and direct contact with wastes and surface water.
5.5 Site Specific factors that may affect the Interim Remedial Action at the Site
There are two seasonal streams and low lying areas (97,500 square feet) that qualify as
wetlands in the vicinity of the landfill.
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6.0 SUMMARY OF SITE RISKS
6.1 Summary of Site Risks at the Former Sanitary Landfill
An interim action must either; 1) prevent further environmental degradation or, 2)
achieve a significant reduction in risk. An interim remedial action does not require a
complete baseline risk assessment, although the data must be sufficient in quality and
quantity to substantiate the action. The interim action at the Former Sanitary Landfill
consists of installing a RCRA Subtitle D cap. The cap will control landfill gas
emissions, reduce vertical infiltration due to precipitation, minimize leachate generation,
prevent further groundwater and surface water degradation, and eliminate the surface soil
exposure pathways.
6.1.1 Human Health Risks
Federal safe drinking water standards and health advisories promulgated under the Safe
Drinking Water Act (40 CFR 300.430(e)) were exceeded for site-specific chemical
contaminants of concern (COCs) in groundwater. In addition, risk-based concentrations
(RBCs) and/or action levels were exceeded for several COCs in groundwater.
Safe drinking water standards and/or risk-based concentrations were exceeded for the
following organic compounds; Benzene, Carbon Disulfide, Chloroform, 1,4-
Dichlorobenzene, 1,2-Dichloroethane, 1,1-Dichloroethene, Methylene chloride, 1,1,2,2-
Tetrachloroethane, Tetrachloroethene, Trichloroethene, 1,2,3-Trichloropropane, and
Vinyl Chloride. Safe drinking water standards and/or risk-based concentrations were
exceeded for the following inorganic compounds; Arsenic, Beryllium, Lead, Manganese,
and Thallium.
6.1.2 Exposure Assessment
Receptors (potential future residents, hunters, trespassers, workers, wildlife, etc.) at the
site may come in contact with contaminants via groundwater, surface water, soil,
sediments, and landfill gases. Exposure to contaminants in groundwater, surface water,
soil, and sediment can occur through ingestion, inhalation and dermal contact. Exposure
to contaminants in fugitive dust emissions from soil may result in exposure through
inhalation. Additional exposure may occur through ingestion offish, wildlife, and
vegetation.
While ingestion, inhalation, and/or dermal contact with contaminants in surface water
and sediment may present an additional risk, the cumulative risk from these media have
not been evaluated for the interim remedy. These media will be evaluated under OU2.
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The IRI evaluated only dermal contact with surface water due to potential exposure to
volatile organic compounds. This dermal contact evaluation was inconclusive.
6.1.3 Toxicitv Assessment
See Appendix A for the toxicological profiles of the COCs listed above.
6.1.4 Risk Characterization
The exceedance of RBCs and/or action levels provide the basis for this interim remedial
action. It serves as the baseline indicating the current risk posed by the landfill. Risk
from potential future use of groundwater at the site has been estimated using RBC tables
(Appendix B), maximum contaminant levels (MCLs) and/or action levels. The estimated
risk level (cancer 2.28xlO"3, HI 17.626) exceeds the acceptable risk range promulgated
by the EPA. In addition, several MCLs and/or action levels were also exceeded. This
interim assessment indicates that it may be prudent to avoid use of groundwater at the
site and that the interim remedial action is necessary.
The list of COCs was determined by EPA following a cursory review of the data
available for the site. These COCs are found in groundwater, surface water, and were
detected during the soil gas survey at the landfill. Appendix B lists the preliminary
COCs at the landfill. Approximate risk levels were determined using the RBCs.
Monitoring will evaluate all potential COCs for the remedial investigation and feasibility
study (RI/FS). Additional COCs may be determined at that time.
6.2 Environmental Risk
The limited risk assessment presented hi the IRI report looked only at risks to humans.
Ecological effects were not evaluated. An ecological risk assessment was not conducted
for any COC. No ecological exposure assessment, effects assessment, or risk
characterization was conducted. Therefore, no cumulative risk was evaluated based upon
environmental exposures.
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7.0 DESCRIPTION OF ALTERNATIVES
7.1 Alternative A: No Action
The No Action alternative does not reduce or eliminate the source of contamination at the
landfill. An evaluation of the No Action alternative is conducted as required by law.
The purpose of Alternative A is to serve as a baseline to compare the risk reduction
effectiveness of the other alternatives.
Under this alternative, the Navy, EPA and MDE would take no further action at the site
to reduce the infiltration of precipitation through the landfill waste or reduce human
contact with the potentially contaminated soil. Additionally, the No Action alternative
would not control or treat any potentially hazardous landfill gas emitting from the
landfill. Contaminants would continue to be released into the environment via surface
water runoff and soil erosion into surrounding surface water bodies. Treatment of
wastes, implementation of access and land use restrictions, cap installation, and removal
of contaminated soil OF groundwater would not be instituted. This alternative is not '
protective of human health and the environment. There is no cost associated with the No
Action alternative.
7.2 Alternative B: Groundwater and Landfill Gas Monitoring with Land Use
and Access Restrictions
This alternative would implement the follow actions:
•Installation of institutional controls
•Landfill gas monitoring
•Groundwater monitoring
Institutional controls would include land use and access restrictions. Access restrictions
would eliminate access to unauthorized personnel and land use restrictions would limit
future development and require permits, supervision, and health and safety precautions
for any activities conducted on or near the landfill. The National Contingency Plan
requires a five-year review at a site which has wastes left in place at or above risk-based
concentration levels. Analytical data from the monitoring of groundwater, surface water,
soil, sediment and landfill gas emissions would be reviewed and a determination made
whether or not to conduct additional remedial actions.
This alternative would only minimally reduce the risk to human health and the
environment but would not eliminate the overall risk. This alternative is more protective
than the baseline alternative (Alternative A), because it limits future development of the
area. This alternative does not incorporate any present or future activities to remediate
13
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the landfill. There is no reduction in toxicity, mobility, or volume of wastes associated
with this alternative.
7.3 Alternative C: RCRA Subtitle D Cap with Groundwater and Landfill Gas
Monitoring with Land Use and Access Restrictions
This alternative would implement the following actions:
•Installation of a RCRA Subtitle D landfill cap
•Implementation of institutional controls
•Installation of a landfill gas collection and treatment system
•Groundwater monitoring
•Modify or upgrade of the leachate collection system
The RCRA Subtitle D landfill cap consists of a barrier system with the following layers;
high quality vegetation, 6" of topsoil, 18" of cover soil, a geocomposite layer (Type C
Geotextile/Geonet/Tyne C Geotextile), a geomembrane (40-mil HDPE), and 24" of
compacted soil. The cap will control landfill gas emissions, reduce vertical infiltration
due to precipitation, minimize leachate generation and further groundwater and surface
water degradation, and eliminate the surface soil exposure pathways.
The leachate collection system will be modified or upgraded to intercept leachate
generated by the landfill from landfill waste decomposition and groundwater intrusion to
the maximum extent practicable. The construction activities of the cap will be tailored to
minimize impacts to nearby streams and wetlands. If wetlands are impacted, a minimum
of one to one replacement will be enforced and full function and value will be
determined.
Institutional controls would include land use and access restrictions. Access restrictions
would eliminate access to unauthorized personnel and land use restrictions would limit
future development and require permits, supervision, and health and safety precautions
for any activities conducted on or near the landfill. The National Contingency Plan
requires a five-year review at a site which has wastes left in place at or above risk-based
concentration levels. Analytical data from the monitoring of groundwater, surface water,
sediment and landfill gas emissions would be reviewed and a determination made
whether or not to conduct further remedial actions.
7.4 Applicable or Relevant and Appropriate Requirements (ARARs)
ARARs are identified by the NCP 40 CFR 300.430 as "requirements applicable to the
release or remedial action contemplated based upon an objective determination of
whether the requirements specifically address hazardous substances, pollutants,
contaminants, remedial actions, location, or other circumstances found at a CERCLA
14
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site. If determined that a requirement is not applicable to a specific release, the
requirement may still be relevant and appropriate to the circumstances of the release."
ARARs are control standards; cleanup standards and other substantive environmental
criteria, requirements or limitations promulgated under Federal and State Laws.
With the exception of MCLs which will be addressed in the final record of decision
(ROD), the selected alternative must comply with Federal and State ARARs. A complete
ARAR table can be found in Appendix C.
The installation is included on the National Priorities List and therefore, pursuant to
section 121 (e)(l) of CERCLA, is exempt from obtaining permits for CERCLA response
actions which are conducted entirely onsite. The installation is required to meet the
substantive requirements of all appropriate permits, and to submit those permit
applications for informational purposes to the respective programs to ensure that the
requirements are met.
A wetland delineation was conducted during the remedial design so that impacts during
the remedial action can be calculated and the size of replacement wetlands estimated.
The acreage replaced shall be at least one for one for wetlands permanently lost due to-
the remedial action, but one for one replacement shall be adjusted to consider three
factors: 1) the time for the replacement wetland to achieve the full function and value of
the impacted wetland; 2) the loss of function and value of the impacted wetland from the
moment of wetland loss to full replacement; and 3) if the replacement area already has
wetlands, to account for the impact of the function and value of the wetland habitat.
Water will be applied to control dust emissions during construction to comply with the
Clean Air Act and Maryland Air Pollution Control regulations. Erosion and sediment
control measures will be implemented around the perimeter of the landfill during
construction in accordance with MDE regulations.
15
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8.0 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
This section evaluates the advantages and disadvantages associated with each alternative
with respect to each of the nine criteria.
8.1 Overall Protection of Human Health and the Environment
Overall protection of human health and the environment addresses whether a remedy
provides adequate protection of human health and the environment from unacceptable
risks posed by hazardous substances, pollutants, or contaminants present at the site by
eliminating, reducing, or controlling exposures through treatment, engineering, or
institutional controls.
Alternative C will control landfill gas emissions, reduce vertical infiltration due to
precipitation, minimize leachate generation, reduce groundwater and surface water
degradation, and eliminate surface soil exposure pathways. This alternative will also
implement institutional controls which include land use and access restrictions. Access
restrictions would eliminate access to unauthorized personnel and land use restrictions
would limit future development and require permits, supervision, and health and safety
precautions for any activities conducted on or near the landfill.
Alternative B only implements institutional controls, which would prevent direct contact
of contaminated groundwater, surface water, soils, and sediments. This alternative does
not reduce, eliminate, or control any of the exposure pathways. Alternative A does not
implement institutional controls nor does it reduce, eliminate, or control any of the
exposure pathways. Alternatives A and B are not protective of human health and the
environment and are not considered viable alternatives under this criteria.
8.2 Compliance with Applicable or Relevant and Appropriate Requirements
(ARARs)
Compliance with ARARs addresses whether an alternative attains all ARARs under
Federal or State environment or facility-siting laws or provides the grounds for invoking
one of the six ARAR waivers stated in §300.430(f)(l)(ii)(C) of the NCP. With the
exception of MCLs which will be addressed in the final record of decision (ROD), the
selected remedy for OU1 will comply with ARARs for impermeable covers, performance
standards, and component standards for closed sanitary landfills. Since groundwater is
not being treated, MCLs will not be met; however, exceedances of MCLs have triggered
the remedial action.
Alternative C will meet all ARARs, with the exception of MCLs. This alternative will
meet all applicable requirements for impermeable covers, performance standards, and
16
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component standards for closed sanitary landfills. Compliance with MCLs will be
evaluated under the final operable unit (OU2) since this interim remedial alternative will
not meet MCLs. Any impacts to surrounding areas such as wetlands and intermittent
streams will be handled in accordance with current state and federal policies and
procedures. If wetlands are impacted, a minimum of one to one replacement will be
enforced and full function and value will be determined.
Controlling dust emissions during construction will be necessary to comply with Clean
Air Act and Maryland Air Pollution Control regulations. Erosion and Sediment control
measures will be implemented around the perimeter of the landfill during and after
construction in accordance with MDE regulations.
The selected alternative will comply with Federal and State ARARs for impermeable
covers, performance standards, and component standards for closed sanitary landfills
with the exception of MCLs which will be addressed in the final record of decision
(ROD). The following list includes a portion of the ARARs that apply to the landfill:
1. Federal and State endangered species protection
2. Federal and State wetland protection regulations
3. Federal and State air emission regulations from landfills, vents, and treatment
systems
4. RCRA Subtitle D and state landfill closure requirements
5. State and local requirements for discharge to a publicly owned wastewater
treatment plant
5. State sediment and erosion control
7. State storm water management requirements
8. State noise control regulations
9. Migratory Bird Treaty Act
10. State requirements for the installation and decommission of groundwater
monitoring wells and piezometers
The specific ARARs are listed in detail in the ARAR table found in Appendix C.
40 CFR Part 60, Standards of Performance for New Stationary Sources and Guidelines
for Control of Existing Sources: Municipal Solid Waste Landfills was considered and
evaluated as a potential ARAR at the landfill. 40 CFR Part 60.16 requires methane
recovery to reduce emissions contributing to global wanning.
Upon review of 40 CFR 60.16, it was determined that this regulation is not relevant and
appropriate. 40 CFR 60.16 is not an ARAR at the landfill because the landfill did not
accept wastes since November 8, 1987, or is operating and has capacity for future use.
Further, it has been determined that this regulation is not relevant and appropriate
because the landfill does not have design capacities greater than or equal to 2.5 million
17
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Mg or 2.5 million cubic meters. In addition, the composition of the landfill waste will
not generate sufficient methane to implement methane recovery.
\
Although not an ARAR, native species will be used to vegetatively cover the landfill in
furtherance of Executive Order 60 FR No. 154, 8/10/95 (Office of the Federal
Environmental Executive; Guidance for Presidential Memorandum on Environmentally
and Economically Beneficial Landscape Practices on Federal Landscaped Grounds).
8.3 Long-Term Effectiveness and Permanence
This criterion examines the ability of a remedy to maintain reliable protection of human
health and the environment over time, once remedial action goals have been
met. Permanence is viewed along a continuum, and an alternative can be described as
offering a greater or lesser degree of permanence.
Alternative C has the highest degree of long-term effectiveness and permanence.
Alternative C will control landfill gas emissions, reduce vertical infiltration of
precipitation, minimize leachate generation, reduce groundwater and surface water
degradation, and eliminate the surface soil exposure pathways. This alternative also
includes institutional controls which prevent land use and access. Access restrictions
would eliminate access to unauthorized personnel and land use restrictions would limit
future development and require permits, supervision, and health and safety precautions
for any activities conducted on or near the landfill.
Alternative B provides limited long-term effectiveness with the placement of land use
and access restrictions on the landfill. Although access would be restricted under
Alternative B, the site will still be accessible. Therefore, Alternative B does not provide
adequate long-term effectiveness and permanent protection to human health and the
environment.
Alternative A does not provide protection of human health and the environment.
8.4 Reduction of Toxicitv. Mobility, or Volume (TMV> through Treatment
This criterion assesses the relative performance of recycling or treatment technologies on
the TMV of contaminants.
Alternative C provides for a reduction in mobility of waste by preventing contaminated
surface runoff and reducing precipitation infiltration. Capping of the landfill will not
reduce the toxicity or volume of waste. No treatment is associated with this alternative.
The landfill gas will be collected and treated to meet landfill gas emission requirements.
18
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Alternatives A and B do not provide any reduction in toxicity, mobility or volume of
wastes through treatment.
8.5 Short-Term Effectiveness
This criterion addresses the adverse impacts on human health and the environment that
may be posed in the time it takes to implement the remedy and achieve remediation
goals.
Alternative C poses short-term risks during the grading phase of construction due to
emissions of volatiles and fugitive dust. Protection will be achieved once the barrier
system has been placed over the landfill.
Landfill gases could be emitted to the atmosphere during soil gas monitoring under
alternatives A and B.
Alternative A does not provide short-term protection of human health and the
environment.
8.6 Implementability
Under this criterion we analyze the technical and administrative feasibility of the remedy,
including the availability of materials and services needed to implement each component
of the option in question.
Alternative C is implementable. The materials and equipment required for constructing
the cap are easily obtainable. This alternative would use standard construction
equipment such as a backhoe, spreader and dump trucks.
Alternative B would require an upgrade of the monitoring equipment already in place at
the Former Sanitary Landfill. Land use and access restrictions are administratively
feasible.
Alternative A does not require any implementation. This alternative requires no action at
the site.
19
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8.7 Cost
Cost includes estimated capital and operation and maintenance costs, and net present
value of capital and operation' and maintenance costs.
Even though Alternative C is the most costly alternative, it is the most protective of
human health and the environment. The capital cost to construct the cap is $2,381,000
and the cost for operation and maintenance is $168,000. Using a 30-year present worth
calculation with a 6% interest rate the total cost is $4,693,486.
The cost associated with Alternative B includes sampling and analysis of groundwater
and landfill gas. Operation and maintenance costs are $168,000. Using a 30-year
present worth calculation with a 6% interest rate the cost is $2,312,486.
There is no cost associated with Alternative A.
Cost Comparison for the Former Sanitary Landfill
Cost in 1995 Dollars
Alternative Description Capital Cost Annual Present Worth
O&M Cost 30yL6%
A
B
C
8.8 State Acceptance
The Maryland Department of Environment/Waste Management Administration concurs
with the preferred alternative (Alternative C) that meets or exceeds the specifications
given in COMAR 26.04.07.21H. COMAR 26.04.07.21H describes the industrial waste
landfill closure requirements for a low permeability cap, a drainage layer, final earthen
cover, and vegetative stabilization as specified in COMARs 26.04.07.21(E)l-4. The low
permeability cap design will minimize infiltration. A cap of synthetic material will have
a minimum thickness of 20 mils and-a maximum permeability of lx!0.10 cm/sec. A
minimum of 1 foot of clay with an in-place permeability less than or equal to lx!0_5
cm/sec may be used. The drainage layer will be of a minimum 6-inch thickness. A
minimum cover thickness of 2-ft and minimum slope shall be 4 percent. Cover material
shall contain sufficient organic materials and nutrients to sustain a vegetative cover.
Topsoil or topsoil created using sewage authorized by COMAR 26.04.06 is acceptable
final cover. Vegetation stabilization using perennial species shall occur within 30-days
20
No Action '
GW & Gas Monit.
Cap. GW & Gas
$0
$_0
$2.381.000
$0
$168.000
$168.000
$_Q
$2.312.486
$4.693.486
-------
after the final cover is installed. Vented methane shall not exceed 25% of the lower
explosive limit (LEL). State concurrence was given on November 20, 1995 in a letter
addressed to Mr. Bayly Smith at the Naval Air Station, Patuxent River, Maryland
(Appendix D).
8.9 Community Acceptance
Community Acceptance summarizes the public's general response to the alternatives
described in the Proposed Plan or the Feasibility Study. Comments and responses
received during the thirty-day comment period and the Proposed Plan Public Meeting
'held on September 15, 1995 are included in the Responsiveness Summary.
8.10 Summary of Detailed Evaluation
The following general conclusions can be made from the comparative analysis:
•Alternatives A and B do not meet the threshold criteria for protection of human health
and the environment. Although Alternative B has some protective controls (land use and
access restrictions), it does not provide adequate long-term protection of human health
and the environment.
•Alternative C meets the threshold criteria for protection of human health and the
environment. This alternative satisfies all evaluation criteria except the Reduction of
Toxicity, Mobility, or Volume through Treatment.
21
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9.0 SELECTED REMEDY
This section describes the selected alternative. The remedy includes the following:
•Installation of a RCRA Subtitle D landfill cap
•Implementation of institutional controls
•Installation of a landfill gas collection and treatment system
•Groundwater monitoring
•Modify or upgrade of the leachate collection system
9.1 Remediation Requirements
The selection of the preferred alternative is based upon the requirements of CERCLA,
including an analysis of the alternatives under the nine evaluation criteria, and public
comments. The US Navy, with the concurrence of EPA and MDE has selected
Alternative C (RCRA Subtitle D Cap with Groundwater and Landfill Gas Monitoring,
and Land Use and Access Restrictions) because it is the most protective of human health
and the environment and most appropriate for remediation of the landfill.
The RCRA Subtitle D landfill cap consists of a barrier system which consists of the
following layers; high quality vegetation, topsoil, subsoil, geotextile, geonet,
geomembrane (40-mil HDPE), and cushion soil. The cap will control landfill gas
emissions, reduce vertical infiltration due to precipitation, minimize leachate generation,
and prevent further groundwater and surface water degradation, and eliminate surface
soil exposure pathways. The leachate collection system will be modified or upgraded to
collect leachate generated from the decomposition of landfilled wastes and groundwater
intrusion to the maximum extent practicable. Construction activities will be tailored to
minimize impacts to nearby streams and wetlands.
Institutional controls will include land use and access restrictions. Access restrictions
will eliminate access to unauthorized personnel and land use restrictions would limit
future development and require permits, supervision, and health and safety precautions
for any activities conducted on or at the landfill. Land-use and access restrictions will be
imposed for the immediate landfill area. A fence will be installed around the landfill to
prevent access thereby eliminating the risk of contact with the wastes while ensuring the
integrity of the cap. No invasive development of the landfill area will be allowed. The
National Contingency Plan requires *a five-year review at any site where wastes are left in
place at or above levels that allow for unlimited and unrestricted exposure. Analytical
data from the monitoring of groundwater, surface water, soil, sediment and landfill gas
emissions will be reviewed and a determination made whether or not to conduct further
remedial actions.
22
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9.2 Performance Standards
9.2.1 Landfill Cap
The landfill cap will be constructed according to the following performance standards:
The cap design will minimize infiltration. A cap of synthetic material will have a
minimum thickness of 20 mils and a maximum permeability of IxlO"10 cm/sec. A
minimum of 1 foot of clay with an in-place permeability of IxlO"5 cm/sec may be used.
The drainage layer will be of a minimum thickness of 6 inches. The cover thickness will
be a minimum of 2 feet with a slope of at least 4 percent. Cover material shall contain
sufficient organic materials and nutrients to sustain a vegetative cover. Topsoil or topsoil
created using sewage authorized by COMAR 26.04.06 is acceptable final cover.
Vegetative stabilization with perennial species shall occur within 30-days after the final
cover is installed. Vented methane shall not exceed 25% of the lower explosive limit.
The final cover system, will be designed to minimize infiltration and erosion. The
permeability will be less than or equal to the permeability of any bottom liner system or
natural subsoils present or have a permeability no greater than IxlO"5 cm/sec. The
infiltration layer will contain a minimum of 18-inches of earthen material. Erosion will
be minimized by the use of a final cover that contains a minimum of 6-inches or earthen
material capable of sustaining native plant growth.
9.2.2 Landfill Gas Collection System and Fiare
The landfill gas collection system and flare will be constructed and operated according to
the following performance standards:
Volatile organic compounds (VOCs) emissions shall not exceed 450 Ib/hr, 3,000 Ib/day,
10 gal/day.
9.2.3 Leachate Collection System
The leachate collection system will meet the following performance standards:
The leachate collection system will be modified or upgraded to intercept leachate
generated by the landfill from landfill waste decomposition and groundwater intrusion to
the maximum extent practicable.
The leachate collection system will operate in accordance with the pre-treatment NPDES
permit for off-site POTW discharge. The details of the leachate monitoring will be
included in the operations and maintenance (O&M) plan. Leachate discharge standards
23
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will comply with any change to the pre-treatment permit requirements or another
permitted discharge point.
9.3 Cost of Selected Remedy
The total cost to construct the cap is $4,693,486. Construction of the cap, landfill gas
collection system with a flare, and upgrading the leachate collection system is estimated
to be $2,381,000 and the cost for operation and maintenance is estimated at $168,000
annually using 30-year present worth with a 6% interest rate.
24
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10.0 STATUTORY DETERMINATIONS
Remedial actions must meet the statutory requirements of Section 121 of CERCLA as
discussed below. Remedial actions undertaken at NPL sites must achieve adequate
protection of human health and the environment, comply with applicable or relevant and
appropriate requirements 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 requirements that are
met by this remedial alternative. Refer to the attached ARAR table (Appendix C) for
more information on specific ARARs mentioned below.
10.1 Overall Protection of Human Health and the Environment
The Navy has determined that the interim remedial action will protect human health and
the environment. The installation of a RCRA cap will eliminate direct contact,
inhalation, and leaching of contaminants to groundwater, surface water and sediment by
controlling precipitation entering the landfill and minimizing leachate generation. There
will be limited short term risks as with any construction activity at the site. However, the
short-term risk should be minimal because the landfill wastes will not be removed from
the landfill during construction activities. Also, the permanent RCRA cap will stabilize
existing conditions at the landfill.
10.2 Compliance with Applicable or Relevant and Appropriate Requirements
The selected remedy will be constructed to meet all applicable or relevant and
appropriate requirements whether chemical, action, or location specific.
Waste disposal activities at the Former Sanitary Landfill occurred before establishment
of the current State regulations regarding disposal of solid and hazardous wastes.
Therefore, the waste area is not subject to current waste disposal requirements specified
hi Maryland's Solid Waste Management regulations (COMAR 26.04.07) or Hazardous
Waste Management regulations (COMAR 26.13).
However, these regulations are considered relevant and appropriate according to the
requirements of the federal NCP (40 CFR 300), which specifies the means by which
remedial actions at this NPL facility should be conducted. As described in the NCP,
overall protection of human health and the environment and compliance with ARARs are
considered threshold requirements that, unless waived, must be met when selecting
remedial action at NPL sites (40 CFR Part 300.430(f)(l)(I)(A)).
25
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The Maryland Department of the Environment, Waste Management Administration
(MDE/WAS) considers installation of a low permeability cap in accordance with the
specifications given in COMAR 26.04.07.21 to be the minimum appropriate action to
address the area described as the Former Sanitary Landfill.
10.3 Location-Specific ARARs
Location-specific ARARs include both federal and State regulations to protect
endangered species and the Archaeological Historic Preservation Act of 1974. In
addition, both federal and state regulations regarding the protection of wetlands and
RCRA capping requirements are considered Location-Specific ARARs.
Federal and State regulations for the protection of wetlands will be met if wetlands are
impacted by the interim remedial action. No impacts to wetlands are anticipated. If,
however, wetlands are lost or destroyed by the remedial action, there will be a minimum
of one for one replacement depending upon the quality of the impacted wetlands.
The low permeability cap will be designed to minimize infiltration per Maryland Solid
Waste Regulations COMAR 26.04.07.21. The design of the cover system and low
permeability cap will be consistent with both Federal and State regulations. The low
permeability cap may be of a synthetic material having a minimum thickness of 20 mil
(.5 mm) with a maximum permeability of IxlO"10 centimeters/second (cm/sec). A
minimum of 1 foot of clay or other natural fine-grained material with an in-place
permeability of less than 1x10"5 cm/sec may be also used. The minimum slope will be
4%. The drainage layer will have a minimum thickness of 6-inches and will be placed
upon the low permeability cap. The drainage layer will be designed not to puncture or
degrade or otherwise jeopardize the integrity of the low permeability cap. Filter fabrics
and synthetic drainage blankets may be used. The final earthen cover placed over the
drainage layers will have a minimum thickness of 2-ft and a minimum slope of 4%.
Cover material shall contain sufficient organic material and nutrients to sustain a
vegetative cover. Topsoil or topsoil created by sewage sludge and less select soils are
acceptable as authorized by COMAR 26.04.06. Within 30-days after the final earthen
cover is installed, the area will be vegetatively stabilized with perennial cover species. If
the final cover is installed at a time which precludes seeding, the area will be mulched hi
accordance with sedimentation and erosion control specifications until the next available
seeding window when the site will be vegetatively stabilized. Methane vented to the
atmosphere shall not exceed 25% ofjhe lower explosive limit (LEL) at the property
boundary.
Regular inspections of the cap will be conducted to ensure that its integrity is maintained
and that it is functioning as designed. The O&M plan will include procedures to repair
and/or replace components of the cap as necessary, to maintain its grade and vegetative
cover hi order to control sedimentation and erosion.
26
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10.4 Action-Specific ARARs
\
Action-specific ARARs include State Noise Pollution Control, capping, stormwater
management, sediment and erosion control, discharge to an off-site POTW, and gas
collection landfill gas treatment regulations.
The low permeability cap will exceed both Federal and State ARARs for cap components
to reduce infiltration of precipitation. Sedimentation and erosion control measures will
be implemented as a component of the design specifications. Sedimentation and erosion
control measures shall be consistent with State and local ARARs. During construction,
air borne dust emissions will be controlled by the application of clean potable water.
Dust suppression activities will meet the Clean Air Act and Maryland Pollution Control
regulations.
Presently, the leachate generated by the landfill and collected by the leachate collection
system meets off-site pre-treatment POTW discharge requirements. After the low
permeability cap is constructed, contaminants in the leachate may increase in
concentration. The O&M plan will include action levels or triggers below pre-treatment
POTW requirements that when exceeded will initiate development of a leachate pre-
treatment system to meet off-site POTW requirements. If leachate treatment is
prohibitively expensive, the leachate will be disposed of off-site in accordance with
RCRA and/or the Clean Water Act (CWA).
The landfill gas collection system will have a paniculate filter and a flare mechanism.
These mechanisms will allow the methane gas and other volatile organic compounds
generated after the landfill is capped to be burned. Monitoring of the landfill gas
collection system and gases generated will be conducted as specified in the O&M plan.
New monitoring wells will be installed in accordance with state requirements.
Substantive permit and licensing requirements will be followed.
Long-term sampling and analysis of the landfill gas, leachate, and groundwater at the site
will be conducted. The specific analytical methods, procedures and sampling frequency
will be specified in the O&M plan. These activities will be conducted to ensure that
long-term effectiveness and integrity of the low permeability cap is maintained.
Land-use and access restrictions will limit the use and development of the property.
These restrictions will ensure the long-term effectiveness and integrity of the low
permeability cap.
27
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10.5 Cost Effectiveness
The selected remedy is cost-effective because it provides overall effectiveness
proportional to the cost. Although roughly twice as expensive as Alternative B, the
selected alternative provides greater protection of human health and/or the environment.
10.6 Utilization of Permanent Solutions and Alternative Treatment Technologies
(Resource Recovery Technologies) to the Maximum extent Practicable.
Capping is a permanent solution and is a common remedy for landfilled wastes of high
volume and low contaminant concentration. Containment in the form of capping is
typical and appropriate for a site of this type.
Alternative treatment or resource recovery technologies were not selected for this site
because of the high volume of wastes and low contaminant concentrations, which make
treatment prohibitively expensive.
10.7 Preference for Treatment as a Principal Element
The interim action does not utilize permanent alternative treatment (or resource recovery)
technologies to the maximum extent practicable for this operable unit due to cost and
other considerations. Although this interim action does not fully address the statutory
mandate for permanence and treatment to the maximum extent practicable, this interim
action is permanent and thus partially satisfies this mandate.
28
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Naval Surface
Warfare Center
Ml
sX 4HL
^Annapolis ^^^K
^_ ^^t
Patuxent River
Naval Air Station
12
Scale in Miles
Figure 1
Prtuont Rtor N*rt >Mr 9«lon Vicinity
St Mary's County, MD.
-------
SANITARY LANDFILL
NOT TO SCALE
Great
Hills
Figure 2
AREA MAP
SUE 11, FORMER SANITARY LANDFILL
Patuxent River Naval Air Station
-------
/^
\ \
1 i
j ' , / | A//
I I / / ! / v
. I : ! , '•//'*
rv\VN Site 11
Current Landfill
Monitoring Well
Sirface WaterSampte
mm mm ^ Leachate Collection Drain
From r«200' Base Maps. 1968
Figure 3
o 100 ZOO SITEMAP
^•fcinFMC SITE 11, FORMER SANITARY LANDFILL
Patuxent River Naval Air Station
-------
-•"W'
v//
11MW-14
'49.09 ^ O1MW
47.85
/"• '' i
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- 1 / / /
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\ t \
\ I . \ \ i \
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Vdf
Site 11
Current Landfill
Monitoring Well
Sirface Water Sample
— — - Approximate Equipotential Line
47.85 Shallow Well Water-Level Elevation
49.09 Deep Well Water-Level Elevation
From r=200' Base Maps. 1968
Note: All measurements are in feet above sea level.
0 100 200
Scale in Feet
Figure 4
WATER-LEVEL ELEVATIONS AT
SITE 11, AUGUST 28,1991
Patuxent River Naval Air Station
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SHB-11J/'' w ; /// // \\ \ \
g^v>Jii\ ' ' /!: . \\iv
l^^i \ i I /M\\ ^v \ \ \
*Ow« \* l / /. I \\\ •• i '
•8i;^^r.\\ j// \v\ \ •
<^ \\\\v/n \\\ ,-N
\\\\\ Ml \M v
^ . > \ v : i i \\ \—
F^
^\\\ //;.,.v
.-v*\V!//i '^^-
^ \ \\N x\ I \ \ ^
Site 11
Current Landfill
Monitoring Wei I
S iff ace Water Sample
0 100 200
SdtoinFMt
From r=200' Base Maps. 1968
Figun> 5
LOCATION OF GEOLOGIC CROSS SECTIONS
SITE 11, FORMER SANITARY LANDFILL
Patuxent River Naval Air Station
-------
120 -^ 11MW-16
^ 117.6
100--
1
a
8 so --
i
ca
60 —
40
LEGEND
-r- 120
11MW-14
11MW-2D
71.1
11MW-16
117.6
B-22
11MW-5S
11MW-5D
79.0
Sand and Silty Sand with zones of
Clay and Gravel
Clay and Silty Clay
Landfill Material (Vertical limits
unknown)
Well Designation
Surface Elevation (feet above MSL)
1977 Soil Borings
Monitoring Well Screen
Water Table (Approximate)
1"-250'Horizontally
1". 201 Vertically
Note: This cross-section was interpolated between
boring location. Actual conditions between
boring may differ from thoM shown here.
- - 100
'-- 80
--60
40
--20
-l-o
Figure 6
SITE 11 - GEOLOGIC CROSS SECTION A-A'
Patuxent River Naval Air Station
-------
80
60 - -
Jj 40 --
20 —
B
11MW-13
68.1
A-A*
11MW-14
11MW-2D
71.1
B-22
B-18
B
11MW-15
65.1
80
LEGEND
11MW-13
68.1
Sand and Silty Sand with zones of
Clay and Gravel
Clay and Silty Clay
Landfill Material (Vertical limits
unknown)
Well Designation
Surface Elevation (feet above MSL)
--60
- - 40
- -20
1". 125' Horizontally
r- 20' Vertically
J-0
Note: This cross-section was interpolated between boring location.
Actual conditions between boring may differ from those shown here.
B-22 1977 Soil Borings
[±| Monitoring Well Screen
\7 Water Table (Approximate)
Flgurt 7
SITE 11 - GEOLOGIC CROSS SECTION B-B'
Patuxent River Naval Air Station
-------
100 -r
80--
60--
40--
20--
LEGEND
-r- 100
11MW-13
68.1
11MW-6S
11MW-6D
61.1
?Wtf&£Z&&££££££&&££££&£^
- - 80
--60
11MW-13
68.1
B-22
Sand and Silty Sand with zones of
Clay and Gravel
Qay and Silly Clay
Landlill Material (Vertical limits
unknown)
Well Designation
Surface Elevation (feet above MSL)
1977 Soil Borings
Monitoring Well Screen
Waltr Table (Approximate)
1". 125' Horizontally
r- 20' Vertically
--40
--20
Note: This cross-section was interpolated between boring location.
Actual conditions between boring may differ from those shown here.
Figure 8
SITE 11 - GEOLOGIC CROSS SECTION C-C'
Patuxent River Naval Air Station
-------
APPENDIX A
Human Health Risk Assessment/Exposure Assessment
\
Human Health Risk Assessment
The human health exposure assessment in the Interim Remedial Investigation (IRI) report
for the Former Sanitary Landfill (Site 11) evaluated two potential exposure scenarios.
The only current exposure scenario evaluated dermal contact with the VOCs in surface
water. The only future exposure scenario evaluated the future risk posed by the ingestion
of contaminated groundwater at the site.
COCs were not evaluated in accordance with applicable Environmental Protection
Agency (EPA) guidance entitled Selecting Exposure Route and Contaminants of Concern
by Risk-Based Screening. Therefore, several COCs were not included in the IRI limited
baseline risk assessment. In addition, the limited baseline risk assessment did not
consider a residential exposure scenario. The occupational exposure scenarios evaluated
in the limited baseline risk assessment for groundwater are not considered by EPA since
the most likely use for .groundwater is residential.
The IRI report acknowledged that MCLs were exceeded for trichloroethylene and
tetrachloroethylene. No other risk information, calculations, comparisons, risk-based
concentrations and/or health advisories were evaluated. No cumulative risk calculation
was considered.
Exposure Assessment
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., IxlO"6 or 1E-6). An excess lifetime cancer risk of 1E-6 indicates
that, 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 specific conditions at the site. Acceptable cancer risk is 1x10-4 to 1x10-6.
The estimated total cancer risk calculated by EPA is 2.28E-03 (Appendix B). This risk
level exceeds the acceptable risk range.
Potential concern for noncarcinogenic (non-cancer causing compounds) effects of a
single contaminant in a single medium is expressed as a hazard quotient (HQ) or the ratio
of the estimated intake derived fromjhe contaminant concentration in a given medium to
the contaminant's reference dose. The Hazard Index (HI) is developed by adding the HQs
for all contaminants within a medium or across all media to which a given population
may reasonably be exposed. The HI provides a useful reference point for measuring the
potential significance of multiple contaminant exposures within a single medium or
across media. At the Former Sanitary Landfill, the HI expressed by EPA for
groundwater is 17.62. A HI index greater than 1 means there is a risk.
-------
Toxicological Profiles for COCs at the Former Sanitary Landfill
\
Volatile Organic Compounds (VOCs)
BENZENE
Benzene is an aromatic hydrocarbon. It is associated with gasoline and has been used as
a solvent in many industries, including the printing, plastics, and rubber industries.
Exposure to benzene may be associated with effects on the central nervous system
(headache, dizziness), respiratory system (irritation), blood (aplastic anemia, anemia,
leukemia), and skin (dermatitis) (Sittig, 1985). Gastrointestinal irritation has also been
reported.
EPA has classified benzene as a Group A known human carcinogen. This is based on an
increased incidence of leukemia in exposed workers and neoplasia in rats.
CARBON BISULFIDE
Carbon disulfide is a solvent used in the manufacturing of viscose rayon, cellophane,
carbon tetrachloride, and flotation agents. It can affect the nervous system as a narcotic
and anesthetic. Other target organs include the kidneys, liver, and skin (as an irritant).
(Sax, 1992; Hawley, 1981)
CHLOROFORM
Chloroform has been used as an anesthetic, although this use has been discontinued.
Chloroform has been used as a solvent by a variety of industries. Chloroform is a
common contaminant of public water supplies where it is formed by the interaction of
chlorine and naturally occurring organic compounds (Sittig, 1985).
Chloroform can affect the liver, heart, and nervous system. The gastrointestinal system
can also be affected. Symptoms of exposure can include dizziness, nausea, and skin
irritation. Chloroform is classified a Group B2 probable human carcinogen by EPA.
-------
1,1-DICHLOROETHENE
1,1-Dichloroethene (1,1-DCE), formerly known as vinylidene chloride, is used in the
manufacture of 1,1,1-trichloroethane and in polymers. Polymer applications include
mortars, concretes, and fabrics (Sittig, 1985).
1,1-DCE is an irritant that can also affect the liver. Inhalation of high concentrations of
1,1-DCE has resulted in CNS depression, as well as liver and kidney damage. 1,1-DCE
is highly volatile and is readily absorbed by the respiratory and GI tracts. EPA has
classified 1,1-DCE as a Group C possible human carcinogen. 1,1-DCE has been shown
to alkylate DNA.
1,2-DICHLOROETHANE
1,2-Dichloroethane (1,2-DCA) is used hi synthetics (nylon, rayon, rubber, plastics)
industries. It can be used as a solvent, fumigant, and degreaser. It may be used in the
photographic, adhesive., water softening, cosmetic, and pharmaceutical industries (Sittig,
1985).
Prolonged dermal contact with 1,2-DCA can cause irritation and dermatitis. Symptoms
of inhalation exposure can include CNS effects such as dizziness and depression of
respiration, as well as nausea.
EPA has classified 1,2-DCA as a Group B2 probable human carcinogen. 1,2-DCA has
also been shown to alkylate DNA.
1,2-DICHLOROETHENE
1,2-Dichloroethene (1,2-DCE) is used as a solvent for waxes, resins, and acetylcellulose.
It is also used in the rubber extraction, refrigeration, and Pharmaceuticals industry
(Sittig, 1985).
1,2-DCE can irritate the skin and mucous membranes. Via the inhalation route,
dizziness, nausea, and vomiting and CNS depression may occur (Sittig, 1985). The
lungs, liver, and kidneys may be affected.
•^
1,2-DCE is not classified as a carcinogen by EPA.
-------
1,4-DICHLOROBENZENE
1,4-Dichlorobenzene is used primarily as a deodorizer and insecticide and is a byproduct
of chlorobenzene production (Sittig, 1985).
1,4-Dichlorobenzene has been associated with hemolytic anemia and liver necrosis. The
dichlorobenzenes reportedly impart an offensive taste and odor to water (Sittig, 1985).
Skin/eye irritation and liver toxicity have been reported in humans (Sax, 1989).
1,4-Dichlorobenzene is classified as a Group B2 probable human carcinogen by EPA.
METHYLENE CHLOREDE (DICHLOROMETHANE)
Methylene chloride, also known as DICHLOROMETHANE, is a volatile solvent and
common laboratory contaminant. Like many volatile solvents, methylene chloride can
affect the nervous system, especially after, inhalation exposure. Potential effects include
dizziness, numbness, eye and skin irritation, and cardiac effects.
Methylene chloride is classified by the EPA as a Group B2 (probable human) carcinogen
via the oral and inhalation routes of exposure.
1,2,3-TRICHLOROPROPANE
Trichloropropane (1,2,3) is a colorless, volatile liquid with a strong acid odor. It is used
to dissolve oils, fats, waxes, chlorinated rubber, and numerous resins. It is also used as a
paint and varnish remover, a solvent, and a degreasing agent.
Exposure to 1,2,3-Trichloropropane may occur through inhalation, skin absorption,
ingestion, skin and eye contact.
Trichloropropane (1,2,3) is highly toxic by inhalation and moderately toxic by skin
absorption. It is a local irritant and produces a number of unpleasant sensory effects and
eye and throat irritation. Long term exposure to 1,2,3-trichloropropane in laboratory
mice and rats have been shown to cause liver and kidney damage, and death at very high
doses. A decreased in the number of red cells have been seen in mice and rats.
«*
Trichloropropane (1,2,3) is currently being reviewed by the Agency for its
carcinogenicity.
-------
1,1,2,2-TETRACHLOROETHANE
Tetrachloroethane (1,1,2,2) is a heavy, volatile liquid which is nonflammable and has a
sweetish, chloroform like odor. It is used as a dry cleaning agent, as a fumigant, in
cement, and in lacquers.
Exposure to 1,1,2,2-tetrachloroethane may occur through inhalation of vapor and
absorption of liquid through the skin, ingestion, and eye contact.
Exposure to 1,1,2,2-tetrachloroethane may result in tremors of hands, followed by skin
irritation, numbness, dizziness and vomiting. Eye irritation and tearing. Long term
exposure may cause nervousness, loss of appetite, constipation, tremors, fatigue,
dizziness, nausea, vomiting and headache and liver damage.
Tetrachloroethane (1,1,2,2) has been shown to cause liver cancer in mice. The EPA has
classified 1,1,2,2-tetrachloroethane as a Class C-possible human carcinogen.
TETRACHLOROETHENE
Tetrachloroethene (PCE), also known as perchloroethylene, is a commonly used solvent
in the dry cleaning, degreasing, and textile industries. It is also used as an intermediate
in the manufacture of organic chemicals (Sittig, 1985).
Irritation of the skin can occur after dermal exposure. High-level inhalation exposure
can cause respiratory and eye irritation. Other effects include CNS depression and liver
damage (Sax, 1989).
EPA ECAO classifies PCE as a Group B2 probable human carcinogen, although this is
not considered Agency-wide consensus at this time.
TRICHLOROETHENE
Trichloroethene (TCE) has been used as a solvent in degreasing operations associated
with both metal-using industries and dry cleaning. TCE has been used as an intermediate
in the production of pesticides, waxes, gums, resins, paints, varnishes, and trichloroacetic
acid (Sittig, 1985).
TCE toxicity can include dermatitis, CNS depression, anesthesia, and effects on the liver,
kidneys, and heart. TCE is a volatile compound, and inhalation exposure may be
significant.
The carcinogenicity of TCE is currently under review.
-------
VINYL CHLORIDE
Vinyl chloride is a volatile organic compound used in the manufacture of polyvinyl
chloride and other resins. It is also used as a chemical intermediate and a solvent (Sittig,
1985). Vinyl chloride can be found environmentally as a breakdown product of
tetrachloroethene, trichloroethene, 1,1-dichloroethene, and 1,2-dichloroethene.
Vinyl chloride can cause skin irritation and CNS depression. Chronic exposure may
cause hepatic damage (Doull, 1986). Vinyl chloride is classified by EPA as a Group A
(known) human carcinogen, and has been specifically associated with hemangiosarcoma
of the liver.
-------
INORGANICS
ARSENIC
Arsenic has been used by the agricultural, pigment, glass, and metal smelting industries.
Arsenic is a ubiquitous metalloid element. Acute ingestion of arsenic can be associated
with damage to mucous membranes including irritation, vesicle formation, and
sloughing. Arsenic can also be associated with sensory loss hi the peripheral nervous
system and anemia. Liver injury is characteristic of chronic exposure. Effects of arsenic
on the skin can include hyperpigmentation, hyperkeratosis, and skin cancer. (Casarett &
Doull, 1986)
EPA classifies arsenic in drinking water as a Group A known oral human carcinogen.
BERYLLIUM
Beryllium is used hi alloys as well as X-ray and nuclear applications. The major source
of beryllium exposure of the general population is from the combustion of coal and oil.
(Casarett and Doull, 1986)
Adverse effects can include respiratory effects (after inhalation exposure) or contact
dermatitis. Other target organs include the liver, spleen, and heart (Sittig, 1985).
Beryllium is classified by EPA as a Group B2 probable human carcinogen via the oral
and inhalation routes.
LEAD
Lead has been used as a gasoline additive (tetraethyl lead) and hi paint pigments,
batteries, X-ray shielding, and plumbing, and has been associated with smelting and
plating industries.
The target organs for lead exposure include the nervous system, hematopoietic system,
kidneys, and reproductive system. Symptoms of severe toxicity may include anemia,
encephalopathy and peripheral neuropathy. Recently, an association between low-level
lead exposure and unpaired neurological development in children has been suggested.
EPA considers lead to be a Group B2 probable human carcinogen via the oral route, but
no Agency-wide consensus has been reached concerning a cancer slope factor.
-------
MANGANESE
Manganese is used in the manufacture of dry cell batteries, paints, dyes, and in the
chemical and glass and ceramics industries. Manganese is an essential nutrient in food;
the average human intake is reported to be approximately 10 mg/day (Sittig, 1985).
Previous reports of neurotoxicity from manganese were generally reported from high-
level occupational exposure to dust and fumes. More recent studies have focused on
exposures to drinking water, with subtle neurologic effects being reported after chronic
consumption of high concentrations of manganese in water (Sittig, 1985; USEPA, 1993).
Manganese is not classified as a carcinogen by EPA.
THALLIUM
Thallium is a byproduct of iron, cadmium, and zinc refining. It has been used in alloys,
optical lenses, jewelry,, semiconductors, and dyes and pigments. Thallium compounds-
have been used as pesticides. (Casarett and Doull, 1986)
Thallium toxicity can result in hair loss, gastrointestinal irritation, paralysis, nephritis,
and liver necrosis. Thallium is one of the more toxic metals, with an estimated lethal
dose in humans of 8 to 12 mg/kg. (Casarett and Doull, 1986)
-------
Appendix C •
Applicable or Relevant and Appropriate Requirements
Former Sanitary Landfill Site (Site 11)
Naval A'ir Station Patuxent River, St. Mary's County, Maryland
Page 1 of 14
ARAR or TBC
Legal Citation
Classification
Summary Requirement
Applicability to Interim Remedial Alternative
I. CHEMICAL
SPECIFIC
A. Water
1. Safe Drinking
Water Act
42 U.S.C. § 300f et seg.
a. Maximum
Contaminant
Levels (MCLs)
40 C.F.R. §§ HI.11-.12
and 141.61-.62
Relevant and Appropriate
MCLs are enforceable standards for public
drinking water supply systems which have
at least 15 service connections or are
used by at least 25 persons. These re-
quirements are not directly applicable
since groundwater at the Site is not used.
However, under the circumstances at this
Site, MCLs are relevant and appropriate
requirements because ground-water may be a
future drinking water source.
The NCP requires where the MCLG is set at a
level of zero, the MCL for that contaminant
under the Safe Drinking Water Act shall be
attained by remedial actions for groundwater or
surface waters that are current or potential
sources of drinking water. Although this
interim remedial alternative will not achieve
MCLs, compliance with MCLs wilt be evaluated
under the final operable unit (OU2).
b. Maximum
Contaminant
Level Goals
(MCLGs)
40 C.F.R. § 141.50-.51
Relevant and Appropriate
NCLGs are non-enforceable health goals for
public water supplies which have at least
15 service connections or are used by at
least 25 persons. MCLGs are relevant and
appropriate.
The NCP requires that remedial actions for
groundwater that is a current or potential
source of drinking water shall meet non-zero
MCLGs for pollutants, contaminants, and hazard
ous substances under the Safe Drinking Water Act
where the MCL is relevant and appropriate. Non
zero MCLGs are relevant and appropriate for
groundwater because groundwater is a potential
source of drinking water. MCLGs will be evalu-
ated under the final operable unit (QU2).
-------
Appendix C
Applicable or Relevant and Appropriate Requirements'
Former Sanitary Landfill (Site 11) Naval Air Station Patuxent River
Page 2 of U
ARAR or TBC
Legal Citation
Classification
Summary Requirement
Applicability to Interim Remedial Alternative
2. EPA Health
Advisories on
Drinking Water
EPA Office of Drinking
Water
To Be Considered
These advisories are non-enforceable gui-
delines for public water supply systems.
These advisories shall be considered for
remedial actions involving groundwater
monitoring, recovery and treatment. Health
advisories shall be used in the monitoring
program to evaluate if groundwater treatment is
necessary under the final operable unit 2 (OU2)
U. LOCATION
SPECIFIC
A. The Endangered
Species Act of
1978
16 U.S.C. § 1531 50
C.F.R. Part 402
Applicable
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.
Potential affected endangered species have not
been identified. The remedial action shall be
implemented so as not to adversely affect such
resources should any be identified in the
future.
B. The
Archaeological
Historic
Preservation Act
of 1974
16 U.S.C. § 469
Applicable
Requires actions to avoid potential loss
or destruction of significant scientific,
.historical, or archaeological data.
No archeological or historical resources have
been identified at the site but they have been
identified within the installation. During
construction if archeological or historical
resources are identified, the remedial action
shall be modified to mitigate any adverse
effects on identified off-site historic
resources that might be destroyed due to the
implementation of the remedial action.
-------
Appendix C
Applicable or Relevant and Appropriate Requirements
Former Sanitary Landfill (Site 11) Naval Air Station Patuxent River
Page 3 of 14
ARAR or TBC
Legal Citation
Classification
Summary Requirement
Applicability to Interim Remedial Alternative
C. Wetlands
Executive Order 119 90,
Protection of Wetlands
(40 C.F.R. 6, Appendix
A)
Clean Water Act of 1972
(CWA) Sectior) 404
Applicable
Action to minimize the destruction, loss,
or degradation of wetlands.
Wetlands are adjacent to the landfill. Wet-
lands should not be impacted. However, if
wetlands are destroyed, lost or degraded due
to the remedial action, mitigation shall be as
follows. For wetlands permanently lost due to
the remedial action, there shall be a minimum
one for one replacement. ' The'one for .one
replacement shall be adjusted via HEP or similar
model to consider 1) time for replacement
wetland to achieve full function and value; H)
loss of function and value of impacted wetland
from the moment of wetland loss to full
replacement; and 3) if the replacement area is a
wetland, to account for impact to the wetland.
Wetland areas that remain wetlands but impacted
by the remedial action must be replanted with
wetland vegetation specified by EPA.
D. Maryland
Wetland
Regulations
CGNAR 08.05.04 &.07 &.1S
CONAR 08.05.07 &.05
Relevant and Appropriate
Protects non-tidal wetlands of the State
from dredging, filling, removal, or other
alteration and requires State oversight
and approval.
A wetland survey and a wetland delineation was
conducted as part of the design specifications.
No wetlands should be filled, dredged, removed
or otherwise altered by the remedial action.
E. Procedures
for Implementing
the Requirements
of the Council on
Environmental
Quality on the
National
Environmental
Policy Act
40 C.F.R. Part 6
Appendix A
Applicable
This is 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 if a practicable alternative
that has less effects is available. If
there is no other practicable alternative,
impacts must be mitigated.
These procedures will be triggered if
construction of the cap affects wetlands.
-------
Appendix C
Applicable or Relevant and Appropriate Requirements
Former Sanitary Landfill (Site 11) Naval Air Station Patuxent River
Page 4 of 14
ARAR or TBC
Legal Citation
Classification
Summary Requirement
Applicability to Interim Remedial Alternative
F. Threatened and
Endangered
Species
COHAR 08.03.08
Applicable
Requires action to conserve endangered
species and the critical habitats they
depend on.
Some of the State's endangered species and
critical habitats are not currently protected
under Federal Endangered Species Act.
Potentially affected State endangered species
and critical habitats have not been identified
on-site. The remedial action shall be imple-
mented so as to not adversely affect any such
resources
identified in the future.
G. Water/lce-
Sanitary
Facilities
Regulation by
State on Water
and Drinking
Water
Environmental Article
Title 9
Subtitles 2 and 4
Applicable
This law provides for. the protection of
the drinking water in the State and
enforcement of Federal Drinking Water
Criteria. Permits, plans and
specifications are required for landfill
closures.
The design specifications will require permits,
plans, and the specifications for landfill
closure. The cap will be designed to reduce
infiltration thus protecting drinking water.
lit. ACTION
SPECIFIC
A. Maryland
Control Noise
Pollution;
Noise & Vibration
Prohibition
COHARs 26.02.03.02A(2)
and B(2) and COHAR
26.02.03.02.03A
Applicable
These regulations set limits on noise
levels for the protection of human health
and welfare and property in the State.
The maximum permitted levels for
construction activities may not exceed 90
dBA during the day and 75 dBA during nig-
ht.
Maximum Allowable Noise Levels will not be
exceeded at the landfill property boundaries
during grading, construction and operation of
the remedy. Equipment shall meet performance
and ambient noise levels during all phases of
the remedial action.
-------
Appendix C
Applicable or Relevant and Appropriate Requirements
Former Sanitary Landfill (Site 11) Naval Air Station Patuxent River
Page 5 of 14
ARAR or TBC
Legal Citation
Classification
Summary Requirement
Applicability to Interim Remedial Alternative
B. Capping/
Closure and Post-
Closure
40 C.F.R. 258.60
Relevant and Appropriate
A final cover system is designed to
minimize infiltration and erosion.
Permeability will be less than or equal to
the permeability of any bottom liner
system or natural subsoils present or have
a permeability no greater than 1x10
cm/sec. The infiltration layer will
contain a minimum of 18-inches of earthen
material. Erosion will be minimized by
the use of a final cover that contains a
minimum of 6-inches of earthen material
capable of sustaining native plant growth.
The design specifications will attain the
infiltration and permeability requirements. The
erosion control layer will provide protection
from wind and water erosion. There will be a
notation on the deed or other instrument that is
examined during a title search that notifies in
perpetuity the land has been used as a landfill
and has use restrictions under § 258.61-(c)(3).
40 C.F.R. 258.61
Relevant and Appropriate
Requires a 30-year post closure regimen
including maintaining the integrity and
effectiveness of the final cover to
correct for settlement, subsidence,
erosion or other events. Prevent run-on
and run-off from eroding or otherwise
damaging the final cover. Maintain and
operate the leachate collection system,
ground-water monitoring system and
landfill gas monitoring system.
The design will prevent run-on and run-off from
eroding or destroying the integrity of the final
cover system. A operation and maintenance (O&M)
plan will be developed for the site which will
include a 30-year post closure monitoring
program. The O&M plan will include procedures
to repair, correct, and maintain the integrity
of the cap and final cover. The O&M plan wilt
include procedures to repair subsidence, the
leachate collection system, and the groundwater
monitoring system.
40 C.F.R. 265.310
Relevant and Appropriate
Final cover to provide long-term minimiza-
tion of infiltration.
The Navy has determined that this regulation is
relevant and appropriate due to the presence of
hazardous waste-1 ike constituents in the
landfill.
-------
Appendix C
Applicable or Relevant and Appropriate Requirements
Former Sanitary Landfill (Site 11) Naval Air Station Patuxent River
Page 6 of 14
ARAR or TBC
Legal Citation
Classification
Summary Requirement
Applicability to Interim Remedial Alternative
40 C.F.R. 265.310
Relevant and Appropriate
Restrict post-closure use of property to
prevent damage to the cover.
The Navy has determined that this regulation is
relevant and appropriate due to the presence of
hazardous waste-1 ike constituents in the
landfill. Land use documents will contain such
restrictions.
40 C.F.R. 265.310
Relevant and Appropriate
Prevent run-on and run-off from damaging
the cap.
The Navy has determined that this regulation is
relevant and appropriate due to the presence of
hazardous waste-like constituents in the
landfill. The design will prevent run-on and
run-off from damaging the cap.
40 C.F.R. 265.310
Relevant and Appropriate
30-year post-closure care to ensure site
is maintained and monitored.
The Navy has determined that this regulation is
relevant and appropriate due to the presence of
hazardous waste-like constituents in the
landfill. The operations and maintenance (O&H)
plan will require a 30-year post closure period
-------
Appendix C
Applicable or Relevant and Appropriate Requirements
Former Sanitary Landfill (Site 11) Naval Air Station Patuxent River
Page 7 of 14
ARAR or T8C
Legal Citation
Classification
Summary Requirement
Applicability to Interim Remedial Alternative
Maryland Solid
Uaste and Water
Supply
Regulations
COMAR 26.04.03CA&D)
26.04.04
26.04.04.06
26.04.04.07(8)
(CK1-
&4)
(D-l)
and
(K-0)
26.04.07.21(A)
(B)
(0)
(E)
(F)
and
(H)
Applicable
Well construction requirements.
Requires well construction permits.
Issuance of well construction permits.
Construction Standards.
Sanitary landfill closure, cap closure,
vegetative stabilization, and gas venting.
The cap design will minimize infiltration. A
cap of synthetic material will have a minimum
thickness of 20 mils and a maximum permeability
of 1x10 cm/sec. A minimum of 1 foot of clay
with an in-ptace permeability less than or equal
to 1x10 cm/sec may be used. The drainage
layer will be of a minimum 6-""inch thickness.
The cover thickness will be a minimum of 2-ft
with a slope of at least 4 percent. Cover
material shall contain sufficient organic
materials and nutrients to sustain a vegetative
cover. Topsoil or topsoil created using sewage
authorized by COMAR 26.04.06 is acceptable final
cover. Vegetative stabilization with perennial
species shall occur within 30-days after the
final cover is installed. Vented methane shall
not exceed 25% of the lower explosive limit
(LED.
C. WATER
1. Water
Appropriation or.
Use
COMAR 08.05.02
Relevant and Appropriate
Mechanism of maintaining a current data
base of wells & groundwater use in the
State.
Groundwater data will be collected from
monitoring wells. The data collected will be
used to determine if groundwater treatment is
needed in the second operable unit (OU2) for the
site. Data will- be provided to the State.
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Appendix C
Applicable or Relevant and Appropriate Requirements
Former Sanitary Landfill (Site 11) Naval Air Station Patuxent River
Page 8 of 14
ARAR or TBC
Legal Citation
Classification
Summary Requirement
Applicability to Interim Remedial Alternative
2. Stormuater
Management
COMARs 26.09.02. &
.01
.03(A&B)
-05(A)
.06
.08
and
.10
Applicable
These regulations require the design and
construction of a system necessary to
control stormwater.
The remedial design will contain measures to
control and manage stormwater both pre and post
construction. The State will review the
remedial design for stormwater management
requirements.
3. Erosion &
Sediment Control
COMARs 26.09.01 &
.04
.05
.06
.07
and
.11
Applicable
Requires the preparation and implementa-
tion of an erosion and sediment control
plan for activities involving land
clearing, grading and earth disturbances
and establishes.erosion and sediment
control criteria.
The remedial design will include the substantive
standards required for clearing, grading, and
other earth disturbances.
The design will contain sediment and erosion
control provisions. This includes compliance
with County and Municipal erosion and sediment
control ordinances, and the Commission's erosier
and sedimentation control regulations.
Inspections, review of plans, permit applica-
tions, and field reviews during construction
wilt be conducted as appropriate.
4. Ground-Water
Monitoring and
Corrective Action
40 C.F.R. 258.51
Relevant and Appropriate
Requires a groundwater monitoring system
that consists of an appropriate number of
monitoring wells and depths to monitor
hydrogeologic conditions, and indicate
background water-quality. The State shall
be notified when monitoring wells or
piezometers are installed or decommis-
sioned.
New monitoring wells or piezometers installed
will be designed to maintain integrity of the
borehole, and the annulus space above the
sampling depth will be sealed to prevent
contamination of samples and ground-water. The
numbers, spacing, and depths shall be determinec
by characteriza-tion of the aquifer thickness,
groundwater flow direction, and seasonal and
temporal fluctuations in groundwater flow.
Decommission procedures will be included in the
operations and maintenance (O&M) plan.
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Appendix C
Applicable or Relevant and Appropriate Requirements
Former Sanitary Landfill (Site 11) Naval Air Station Patuxent River
Page 9 of H
ARAR or TBC
Legal Citation
Classification
Summary Requirement
Applicability to Interim Remedial Alternative
5. Ground-water
Sampling and
Analysis
Requirements
40 C.F.R. 258.53
Relevant and Appropriate
The ground-water monitoring program must
include consistent sampling and analysis
procedures that ensure-monitoring results
provide an accurate representation of
groundwater quality at back-ground and
down-gradient wells installed in
compliance with § 258.51(a).
Sampling and analysis will include procedures
and techniques for proper sample collection,
preservation, shipment, analytical procedures,
chain-of-custody, quality assurance and quality
control. EPA Region 3 Modifications to the
National Functional Guideline will be used for
data validation. Current' contract laboratory
program (CLP) statements of work (SOWs) will be
followed. Analytical methods will accurately
measure hazardous constituents and other
monitoring parameters. Ground-water elevations
will be measured immediately prior to purging,
each time groundwater is sampled. The design
plans and specifications will include these
requirements.
6. Board of Well
Drillers
COHAR 26.05.01-.09
Applicable
Provides licensing requirements for
drilling and well installation.
Licensing requirements shall be incorporated
into the design specifications.
.0. Discharge To
POTW
40 C.F.R. 403.5 and
local POTU regulations
Applicable
Discharge must comply with POTU pre-
treatment program, including POTW-speciftc
pollutants, spill prevention, reporting
and monitoring requirements.
The discharge currently meets State and local
discharge to POTU requirements. If levels to
discharge to the POTU are approached, the O&H
plan will allow for the treatment of the
leachate before it is discharged to the POTU.
E. Gas Collection
And Vents
CAA Section 101 and 40
C.F.R. 52
Relevant and Appropriate
File an Air Pollution Emission Notice
(APEN) with the state to include
estimation of emission rates for each
pollutant expected.
The design will include an estimate of air
emissions. The design will allow for the
collection and treatment of landfill gases.
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Appendix C
Applicable or Relevant and Appropriate Requirements
Former Sanitary Landfill (Site 11) Naval Air Station Patuxent River
Page 10 of 14
ARAR or TBC
Legal Citation
Classification
Summary Requirement
Applicability to Interim Remedial Alternative
COMAR 26.11.03
Relevant and Appropriate
State-adopted, National Ambient Air Qua-
lity Standards and Guidelines
The substantive standards of these regulations
apply.
COMAR 26.11.06.03
Relevant and Appropriate
Air Quality: General Emission Standards,
Prohibitions, Restrictions - Participate
Matter
These substantive standards erf this'regulation
will apply and be included in the design.
COMAR 26.11.06.06
Applicable
Air Quality: General Emission Standards -
Volatile Organic Compounds (VOCs). This
regulation applies to installations where
the discharged VOC has a vapor pressure
greater than 0.002 pounds per square inch
absolute.
The substantive standards of this regulation
apply to this site and will be considered
during the remedial design.
COMAR 26.11.15 &
.11
.12
and
.13
Applicable
Air Quality: Toxic Air Pollutants
Any source that discharges a Class I or
Class II Toxic Air Pollutant (TAP) into
the ambient air is subject to this
regulation.
These regulations are applicable.
40 C.F.R. Part 60
Subpart WWW
To Be Considered
NESHAP
This regulation shall be considered at this
site.
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Appendix C
Applicable or Relevant and Appropriate Requirements
Former Sanitary Landfill (Site 11) Naval Air Station Patuxent River
Page 11 of 14
ARAR or TBC
Legal Citation
Classification
Summary Requirement
Applicability to Interim Remedial Alternative
40 C.F.R. 52
Applicable
Predict total emission of volatile organic
compounds (VOCs) to demonstrate emissions
do not exceed 450 Ib/hr, 3,000 Ib/day, 10
gal/day or allowable emission levels from
similar sources using Reasonably Available
Control Technology (RACT)
This regulation is applicable and will be
considered in the design.
Section 101 of the Clean
Air Act (CAA) and 40
C.F.R. § 52
Relevant and Appropriate
Design system to provide odor-free
operation
The landfill gas collection system will, be
designed to include a flare. The O&H plan will
include sampling and analysis of landfill gas tc
ensure the landfill gas collection and flare
system is operating properly.
CAA Section 112(D)
Relevant and Appropriate
Emission Standards for new stationary
sources
Relevant and Appropriate.
CAA Section 118
Applicable
Control of pollution from Federal
Facilities
This regulation shall apply at this site and be
addressed in the design specifications.
40 C.F.R. Part 61
Relevant and Appropriate
Verify that emissions of mercury, vinyl
chloride, and benzene do not exceed levels
expected from sources in compliance with
hazardous air pollution regulation.
The O&H plan will include sampling and analysis
requirements to verify compliance.
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Appendix C
Applicable or Relevant and Appropriate Requirements
Former Sanitary Landfill (Site 11) Naval Air Station Patuxent River
Page 12 of 14
ARAR or TBC
Legal Citation
Classification
Summary Requirement
Applicability to Interim Remedial Alternative
F. Emission
Standards For
Process Vents
40 C.F.R. Part 264 Sub-
part AA
Relevant and Appropriate
Establishes requirements for process vents
for operators that manage hazardous wastes
with organic concentrations of at least 10
parts per million weight.
This regulation shall be incorporated into the
design of the landfill gas collection system,
filter and flare. The O&M plan will detail the
specific sampling methods and analytical
procedures.
G. Air
1. Maryland
Regulations
Governing Air
Emission
Standards
COHAR 26.11.06.02
.03
.06
.08
and
,09
Applicable
Provides air quality standards, general
emission standards and restrictions for
articles, machines, equipment, etc.
capable of generating, causing, or
reducing emissions.
Landfill gas vents shall meet substantive
standards of these regulations. If any other
equipment or construction capable of generating
causing, or reducing emissions is required (e.g
air stripper), it shall also meet these require
merits.
2. Maryland
Regulations
Governing Toxic
Air Pollutants
COMAR 26.11
.15.04
.05
.06
.07
.08
.11
.13
and
.19.02(0)
Applicable
Provides air quality standards, emission
standards from construction activities,
vents, and treatment technologies.
Active or passive landfill gas venting systems
shall adhere to these regulations. The design
shall meet these requirements.
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Appendix C
Applicable or Relevant and Appropriate Requirements
Former Sanitary Landfill (Site 11) Naval Air Station Patuxent River
Page 13 of 14
ARAR or TBC
Legal Citation
Classification
Summary Requirement
Applicability to Interim Remedial Alternative
COHAR 26.13.05 &
Applicable
.146(9)
and
.14C<2)
Regulation applies to owners and operators
of all facilities that treat, store, or
dispose of hazardous waste.
For landfills, the owner or operator is to
cover or otherwise manage the landfill to
control wind dispersal if the landfill
contains paniculate matter subject to
wind dispersal. •
Maintain a wind dispersal system and
inspect weekly.
These regulations are applicable to this site
and shall be complied with within the design
specifications.
I. Hazardous
Waste Management
COMAR 26.13
26.13.01
26.13.02 &
.01
.02
.03
.04
.04-1
.04-2
.06
.07
.08
and
.10-.16
Applicable
Maryland Regulations for generators on
maintenance/or removal of hazardous
wastes. Includes regulations for the
transport and identification of hazardous
wastes. Wastes generated from the
installation of monitoring wells, residues
or byproducts from groundwater treatment
which are hazardous or wastes generated by
an active landfill gas extraction system
shall be identified for proper disposal.
The remedial design will include analytical
methods and sampling procedures necessary to
characterize the waste for transport and
disposal off site.
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Appendix C
Applicable or Relevant and Appropriate Requirements
Former Sanitary Landfill (Site 11) Naval Air Station Patuxent River
Page 14 of 14
ARAR or TBC
Legal Citation
Classification
Summary Requirement
Applicability to Interim Remedial Alternative
COHAR 26.13.03 &
.02
.04
and
.05
Applicable
Standards applicable to generators of
hazardous wastes.
The remedial design and operation and mainten-
ance plan will include procedures to identify
hazardous wastes generated by this remedial
action.
COMAR 26.13.04 &
' .01
and
.03
Applicable
Standards applicable to transporters of
hazardous wastes.
The remedial design wilt include these
requirements for the transport of hazardous
materials.
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Appendix D
MARYLAND DEPARTMENT OF THE ENVIRONMENT
2500 Broening Highway • Baltimore, Maryland 21224
(410)
Parris N. Glendening - Jane T. Nishida
Governor Secretary
November 20, 1995
Mr. Bayly Smith
Naval Air Station
Environmental Department
Public Works Building 504
Patuxent River MD 20670
Re: Proposed Plan for the Former Sanitary Landfill, foterim Remedial Action,: Patuxent River
Naval Air Station- Dated September 1995.
Dear Mr. Smith:
The Maryland Department of the Environment, Waste Management Administration
(MDE/WAS) has reviewed the above referenced document. As we have discussed in several
meetings over the last few months, this document presents the Navy's plan to cap the Former
Sanitary Landfill at the Patuxent River Naval Air Station.
The waste disposal activities at the Former Sanitary Landfill occurred prior to the
establishment of current State regulations regarding the disposal of solid and hazardous wastes.
Therefore, this waste area is not subject to current waste disposal requirements as specified in
Maryland's Solid Waste Management regulations (COMAR 26.04.07) or Controlled Hazardous
Substances regulations (COMAR 26.13).
These regulations are considered relevant and appropriate according to the requirements
of the federal National Contingency Plan (NCP) (40 CFR Part 300), which specifies the means by
which remedial actions at this National Priorities List (NPL) facility should be conducted. As
described in the NCP, the overall protection of human health and the environment and compliance
with Applicable or Relevant and Appropriate Requirements (ARARs) are considered threshold
requirements that in most cases must be met when selecting the remedial action at NPL sites (40
CFR part 300.430 (f) (1) (I) (A)).
The MDE/WAS concurs with the decision to cap the Former Sanitary Landfill with a low
permeability cap that meets or exceeds the specifications given in COMAR 26.04.07.21H.
Tnn COD TUT:
"Together We Can Clean Up'
°
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Mr. Bayly Smith
Page 2
If you should have any questions, please contact me at (410) 631-3440 or 3394.
Sincerely,
KL:bjm
cc: Ms. Wanda Holmes
Mr. Andrew Sochanski
Mr. Richard Collins
Mr. Robert DeMarco
Mr. Edward Dexter
Ms. Hilary Miller
Kim Lemaster
Acting Section Head
Federal/NPL Superfund Division
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RESPONSIVENESS SUMMARY
The following responsiveness summary for the Former Sanitary Landfill site at Naval
Air Station Patuxent River, Maryland, documents the public involvement in the interim
remedial action selection process. This summary also paraphrases the comments
received by the Naval Air Station during the public comment period and also provides
responses. This responsiveness summary consists of the following sections:
Section 1.0 Overview
Section 2.0 Background on Community Involvement
Section 3.0 Summary of Comments Received During the Public Comment Period
and Agency Responses
1.0 Overview
On September 6, 1995, the Proposed Plan for the Former Sanitary Landfill. Interim
Remedial Action (Operable Unit 1) was made available to the public for review and
comment. A public comment period continued for thirty days until October 6, 1995, and
.a public meeting was held on September 15, 1995. During the public meeting,
community members voiced their concerns and opinions on the Proposed Plan to which
the Naval Air Station Patuxent River, U.S. Environmental Protection Agency, and
Maryland Department of the Environment responded.
Based on oral comments received during the public meeting and the fact that no written
comments were received by the Naval Air Station Patuxent River during the thirty-day
comment period, the selected interim remedial action seems acceptable to the local
community of Lexington Park, Maryland. The selected interim remedial action specified
in the Proposed Plan and Record of Decision involves the installation of an impermeable
cap in accordance with the Resource Conversation Recovery Act (RCRA) and State of
Maryland Code of Maryland Regulations (COMAR). Also, the selected interim remedial
action consists of institutional controls and deed restrictions as specified hi the Decision
Summary of the Record of Decision.
2.0 Background on Community Involvement
Community interest in the Former Sjinitary Landfill grew when the Proposed Plan for the
site was issued in September of 1995. During the public comment period, no written
questions or concerns were received. The community voiced their concerns during the
public meeting held on September 15, 1995. Responses to the questions and comments
were provided during the meeting. A summary of the meeting minutes can be found hi
section 3.0 of this report.
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The following is a list of public meetings and events associated with the Former Sanitary
Landfill:
\
03/26/96 Restoration Advisory Board Meeting
12/07/95 Restoration Advisory Board Meeting
09/15/95 Proposed Plan Public Meeting
09/06/95 30 Day Public Comment Period
08/24/95 Restoration Advisory Board Meeting
3.0 Summary of Comments Received During the Public Comment Period
and Agency Responses
The public comment period on the Proposed Plan for the Former Sanitary Landfill.
Interim Remedial Action (Operable Unit \). was held from September 6, 1995 to
October 6, 1995 and a public meeting was held on September 15, 1995.
A transcript of the public meeting held on September 15, 1995 can be found in the
Administrative Record for the Former Sanitary Landfill (Site 11) and is available for
review. The Administrative Record can be found in the Installation Restoration
information repositories located at the Lexington Park Public Library and the Naval Air
Station Patuxent River Library.
Comment 1; How is the present worth of the landfill construction and annual operating
and maintenance (O & M) calculated?
NAS & EPA Response: Present worth analysis is used to determine what amount of
money, if invested today, would yield the needed future costs. The present worth
analysis defines the amount of money required to fund construction and O & M of a
project over a specified amount of time. The analysis involves back calculating future
costs of O & M to present costs using a discount rate. The discount rate is typically the
interest rate paid on long-term bonds. Essentially, if x amount of dollars is deposited
into an account at a given interest rate and length of time, there will be enough money to
cover the annual costs of O & M for 30 years. For example, the operation and
maintenance cost hi 1996 for the Former Sanitary Landfill is estimated to be
$168,000.00. To determine the present cost of O & M over a 30 year period and at a six
percent (typical) interest rate, a conversion factor of 13.7648 is multiplied by
$168,000.00.
In this case, the answer is $2,312,486.00. If $2,312,486.00 were invested in an account,
at an interest rate of six percent, and if $168,000.00 (current dollar value) were
withdrawn annually for 30 years, there would be enough money to cover the necessary O
& M. Present worth analysis is not a final total for operation and maintenance. The
present worth analysis is a comparison methodology used for various remedial
alternatives at the current dollar value.
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Comment 2; What is the life span of a typical landfill cap?
EPA Response; A landfill cap is designed to last a lifetime which is generally
considered fifty (50) years; provided the landfill cap is constructed and maintained
properly.
Comment 3; What will happen to the contents of the landfill and the surrounding soils
of the site once the cap is installed? What is a five-year review?
NAS & EPA Response: The cap will reduce precipitation infiltration and the amount of
leachate generated. The leachate will probably decrease in volume, but increase in
concentration. If necessary, the leachate will be pre-treated before being discharged to
the St.Mary's County Metropolitan Commission treatment facility. Continued
monitoring of the shallow groundwater and leachate will provide the necessary
information needed to make a determination if pre-treatment is warranted. Since wastes
are being left in place, the Navy and EPA-are required to re-evaluate monitoring and
sampling data every five years to determine whether or not the selected remedy remains
protective of human health and the environment or has created any additional or adverse
risks.
Comment 4; What do the post-closure monitoring requirements consist of?
NAS & EPA Response: In the beginning, quarterly sampling will occur and if possible,
it will be reduced to bi-annually. Currently, sampling consists of static shallow
groundwater elevations and chemical analysis. Also, the flow-rate of the leachate is
recorded and a chemical analysis is performed. The new sampling requirement can be
found hi the Post-Closure Monitoring Plan. Former and Current Landfills. Patuxent
River Naval Air Station. Patuxent River. Maryland prepared by Baker
Environmental, INC. dated March 28, 1996. The plan can be found in the local
information repositories.
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Comment 5; Is the approach selected in the proposed plan unique?
\
NAS & EPA Response; The selected remedy is considered a presumptive remedy. As
defined by EPA, "Presumptive remedies are preferred technologies for common
categories of sites, based on historical patterns of remedy selection and EPA's scientific
and engineering evaluation of performance data on technology implementation. EPA has
evaluated technologies that have been consistently selected at past sites using the remedy
selection criteria set out in the National Oil and Hazardous Substances Pollution
Contingency Plan (NCP); reviewed currently available performance data on the
application of these technologies; and has determined that a particular remedy, or set of
remedies, is presumptively the most appropriate for addressing specific types of sites".
Comment 6; What do the liners consist of beneath the two landfills and what is the
integrity of each?
NAS & MDE Response; The Former Sanitary Landfill does not have a liner beneath it
because federal and state regulations, at the time of construction, did not require it. The
Current Sanitary Landfill has a clay liner on the bottom and a synthetic liner on the
slopes or sides. The integrity of each liner will be evaluated during the Remedial
Investigation phase of the Installation Restoration Program.
Comment 7; When did the Current Sanitary Landfill close and when must construction
begin and end?
NAS & EPA Response; The Current Sanitary Landfill closed September 30, 1994.
Capping, according to state solid waste regulations, must begin by October 1, 1996 and it
must end by October 1, 1997. Also, since the landfills are side-by-side and they utilize
the same leachate collections system, capping only one landfill would prove useless.
Precipitation infiltration would still occur in the uncapped landfill and leachate
generation would not be reduced in the capped landfill. The Current Sanitary Landfill is
being closed under state landfill closure regulations which consists of a RCRA Subtitle D
cap.
Comment 8; Is landfill gas monitoring part of the overall monitoring requirements?
NAS & EPA Response; The landfill gases will be collected, monitored, and if
necessary, treated in accordance with Federal and State regulations. Landfill gases will
be flared using natural gas to enhance destruction of methane and other potential
emissions. See the Post-Closure Monitoring Plan. Former and Current Landfills.
Patuxent River Naval Air Station. Patuxent River. Maryland document for details.
-------
Comment 9: Can the site be re-utilized for another purpose?
NAS & EPA Response: Land-use and access restrictions will be imposed for the
immediate landfill area. A fence will surround the landfill to prevent access, thus
eliminating the risk of contact with wastes by unauthorized personnel and ensuring
integrity of the cap. If development of the landfill area were allowed to occur, the cap
could be breached or the performance of the remedial action reduced to unacceptable
levels. Therefore, no invasive development will be allowed on the site.
Comment 10; What is the possibility that groundwater is contaminated and the
possibility of future use of groundwater in the vicinity as a drinking source.
NAS & EPA Response: There are no potable wells in the vicinity of the landfill, nor
will there be any new wells installed in the future per land-use restrictions.
Groundwater flows northeast toward Pond 3, Pine Hill Run, and eventually the
Chesapeake Bay. There are no shallow unconfined wells close enough to the landfill that
warrant sampling due to the minimal influence that a residential well would have. See
the Interim Remedial Investigation Report, prepared by CH2M Hill, dated February
1994, for further groundwater information, which can be found in the Installation
Restoration information repositories.
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