Superfund Proposed Plan
Nepera Chemical Company, Inc. Superfund Site
Hampton burgh, Orange County, New York
July 2007
&EPA
PURPOSE OF THE PROPOSED PLAN
This Proposed Plan describes the remedial alternatives
considered for the contaminated soil and groundwateratthe
Nepera Chemical Company Superfund Site, and identifies the
preferred remedy with the rationale for this preference. This
Proposed Plan was developed by the U.S. Environmental
Protection Agency (EPA) in consultation with the New York
State Department of Environmental Conservation (NYSDEC).
EPA is issuing this Proposed Plan as part of its public
participation responsibilities under Section 117(a) of the
Comprehensive Environmental Response, Compensation,
and Liability Act (CERCLA) of 1980, as amended (commonly
known as the federal "Superfund" law), and Sections
300.430(f) and 300.435(c) of the National Oil and Hazardous
Substances Pollution Contingency Plan (NCP). The nature
and extent of the contamination at the site and the
alternatives summarized in this Proposed Plan are further
described in the June 16, 2006 Remedial Investigation (Rl)
Report and the June 26, 2007 Feasibility Study (FS) Report,
respectively. EPA and NYSDEC encourage the public to
review these documents to gain a more comprehensive
understanding of the site and Superfund activities that have
been conducted at the site.
This Proposed Plan is being provided to inform the public of
EPA's preferred remedy and to solicit public comments
pertaining to the remedial alternatives evaluated, including
the preferred alternatives. EPA's preferred remedy consists
of the following components:
Excavation of the soil in the source area (former
lagoon area), the design and construction of a biocell
to contain the excavated soil, the installation of a soil
vapor extraction (SVE) system within the biocell, and
operation of the SVE and biocell to remediate
contaminated soil. This soil remedial alternative is
referred to as Soil Alternative 4 (S4). In addition, the
excavated area will be treated with oxygenating
compounds (e.g., Oxygen Releasing Compounds) to
create an aerobic environment and, thereby,
stimulate biodegradation within the area of elevated
groundwater contamination. This groundwater
remedial alternative is referred to as Groundwater
Alternative 2 (GW2). The injection of oxygenating
compounds directly into the groundwater at location-
specific injection points to further enhance
biodegradation of groundwater contamination will be
evaluated during the remedial design. This will be
followed by a long-term groundwater monitoring
program where groundwater samples would be
Mark Your Calendar
July 31,2007 -August 29,2007: Public Comment Period
on the Proposed Plan.
August 16, 2007 at 7:00 p.m.: The U.S. EPA will hold a
Public Meeting to explain the Proposed Plan. The meeting
will be held at Campbell Hall in Hamptonburgh, New York.
For more information, see the Administrative Record
file (which will include the Proposed Plan and
supporting documents), which is available at the
following locations:
Hamptonburgh Town Hall
18 Bull Road
Campbell Hall, New York 10916
Tel. 845-427-2424
Hours: Monday - Friday 9:00am - 3:30pm
and
USEPA-Region II
Superfund Records Center
290 Broadway, 18th Floor
New York, NY 10007-1866
(212)637-4308
Hours: Monday-Friday, 9:00 a.m. - 5:00 p.m.
Written comments on this Proposed Plan should be
addressed to:
Mark Dannenberg
Remedial Project Manager
Eastern New York Remediation Section
U.S. Environmental Protection Agency
290 Broadway, 20th Floor
New York, New York 10007-1866
Telephone: (212)637-4251
Telefax: (212)637-3966
Email address: Dannenberg.mark@epa.gov
The EPA has a web page for the Nepera Chemical
Company Site at
www.epa.gov/region2/superfund/npl/neperachemical.
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collected and analyzed regularly in order to verify
that the concentrations and the extent of
groundwater contaminants are declining. The exact
frequency and parameters of sampling and location
of any additional monitoring wells would be
determined during the design phase.
The remedy described in this Proposed Plan is the preferred
remedy for the site. Changes to the preferred remedy or a
change from the preferred remedy to another remedy may be
made if public comments or additional data indicate that such
a change will result in a more appropriate remedial action.
The final decision regarding the selected remedy will be
made after EPA has taken into consideration all public
comments. EPA is soliciting public comment on all of the
alternatives considered in this Proposed Plan.
COMMUNITY ROLE IN SELECTION PROCESS
EPA and NYSDEC rely on public input to ensure that the
concerns of the community are considered in selecting an
effective remedy for each Superfund site. To this end, this
Proposed Plan, along with the supporting Remedial
Investigation and Feasibility Study Reports, have been made
available to the public for a public comment period which
begins on July 31, 2007 and concludes on August 29,
2007.
A public meeting will be held during the public comment
period at Campbell Hall in Hamptonburgh, New York on
August 16,2007 at 7:00 P.M. to elaborate on the reasons for
the proposed remedy and to receive public comments.
Comments received at the public meeting, as well as written
comments, will be documented in the Responsiveness
Summary Section of the Record of Decision (ROD), the
document which formalizes the selection of the remedy.
SCOPE AND ROLE OF ACTION
This Proposed Plan presents the preferred alternatives to
remediate the site. The objectives of the proposed remedy
are to remediate contaminated soil, reduce and minimize the
migration of contaminants in the groundwater, restore
groundwater quality, and minimize any potential future health
and environmental impacts.
SITE BACKGROUND
Site Description
The property is located on the south side of Orange County
Highway 4 in Hamptonburgh, Orange County, New York,
approximately 1.5 miles southwest of the Village of Maybrook
(see Figure 1). The site is owned by Nepera Chemical
Company, Inc. (Nepera). The site is 29.3 acres in area;
approximately 5 acres of the site were used for the historical
lagoon operations (see Figure 2). The site is located in a
rural residential/agricultural area, bounded by Orange County
Highway 4 to the north, Beaverdam Brook to the west, the
Otter Kill to the south, and an undeveloped tract of land to the
east. Three residences exist in the immediate vicinity of the
site, one to the southwest, one to the north and one to the
northeast (on the other side of Orange County Highway 4).
Approximately 7,000 people live within three miles of the
site, with the closest residences located approximately 250
feet to the west-southwest and 175 feet to the northeast.
The public water supply wells for the Village of Maybrook
are located approximately 800 feet to the northeast of the
site property. All residences in the vicinity of the site rely
on private wells for the potable water supply.
Site Geology/Hydroqeology
The site is in an area of rolling hill topography and is
located within a 4.5 square mile watershed consisting of
Beaverdam Brook and its tributaries, which discharge to
the Otter Kill, located approximately 500 feet to the south of
the property. The geologic units at the site are divided into
two primary units, the overburden (comprised of topsoil, fill,
and gravel) and the bedrock (comprised of shale). Ground
surface topography is generally bedrock controlled in that
the ground surface generally follows the bedrock surface
topography. The overburden thickness at the site is also
related to bedrock topography in that it is generally thinner
(or absent) over bedrock ridges, while greater overburden
thicknesses have been deposited in bedrock depressions
and valleys. The overburden ranges in thickness from 0 to
20 feet.
Most of the site is forested. The former lagoon area, which
was stripped of vegetation while in use, is now covered
with grasses, wild flowers, and mixed brush. There are two
aquifers that exist beneath the site, the overburden aquifer
and the bedrock aquifer. The overburden aquifer is the
surficial unit which overlies the bedrock aquifer. The
bedrock aquifer is the primary source for public water in the
area. No significant layers of impeding clays were
observed between the two aquifers within the study area.
An east to west trending groundwater divide is present in
the bedrock aquifer underlying (and transecting) the lagoon
area. As such, groundwater flow has a northerly and a
southerly component radiating from this divide.
Site History
The site was used for the disposal of industrial wastewater
generated at the Nepera Chemical Company facility in
Harriman, New York, located approximately 25 miles from
the site. Wastewater was trucked to the site and disposed
of in six constructed lagoons from 1953 through December
1967. Approximately 5 acres of the site were used for the
historical lagoon operations, six lagoons in all. No
wastewater disposal has occurred at the Site since
December 1967. Three of the lagoons were backfilled with
clean soil in 1968 and the remaining three lagoons were
backfilled with clean soil in 1974.
Beginning in 1967, numerous investigations were
conducted by various consultants to Nepera to determine
the extent of contamination at the site. Based on the
results of these investigations, NYSDEC placed the site on
the New York Registry of Inactive Hazardous Waste
Disposal Sites. On August 17, 1984, the State of New
York entered into a Consent Decree with Nepera Chemical
Company, Inc. to conduct a remedial investigation to
determine the type and extent of contamination at the site.
EPA Region II - July 2007
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On June 1, 1986, the EPA placed the Nepera site on the
National Priorities List (NPL) of sites under the
Comprehensive Environmental Response Compensation and
Liability Act 1980 (CERCLA), as amended. NYSDEC
continued as the lead regulatory agency overseeing the
implementation of the RI/FS.
Under an Administrative Order with NYSDEC, signed on
March 21, 1988, the Potentially Responsible Party (PRP),
namely Nepera Chemical Company, Inc., hired a contractor
to conduct a Remedial Investigation/Feasibility Study (RI/FS)
of the site in 1988. The first draft Rl was submitted in March
1996. EPA determined that further work was necessary to
define the type and extent of soil contamination at the site
and to determine the downgradient extent of the contaminant
plume which emanated from the site. In March 2005, an
updated draft Rl was submitted to NYSDEC and USEPA.
This document was revised and a Final Rl Report was
submitted on June 16 2006.
The lead agency for the Nepera site was recently re-
designated, at the conclusion of the RI/FS process, from
NYSDEC to USEPA.
SUMMARY OF SOIL AND GROUNDWATER SAMPLING
Major Rl activities performed during field data collection
activities included: on-site soil borings, soil sampling,
monitoring well drilling and installation, groundwater
sampling, and residential well sampling. The results of the Rl
are summarized below.
Soil
The PRP performed the Rl in several phases. Soil sampling
activities were conducted in 1991 and 1996. Focused soil
sampling identified contamination in the lagoon area and
determined the lagoon area to be the primary source of the
contaminants in the groundwater plume. The primary
contaminants identified during soil sampling activities include
benzene (maximum concentration of 13 milligrams per
kilogram (mg/kg)), chlorobenzene (maximum concentration of
12 mg/kg), ethylbenzene (maximum concentration of 22
mg/kg), toluene (maximum concentration of 52 mg/kg),
xylenes (maximum concentration of 300 mg/kg) and pyridine-
related compounds (maximum concentration of 74 mg/kg of
2-amino pyridine). Each of these contaminants are
considered as Contaminants of Concern (COCs) forthe Site.
In addition, several samples detected elevated levels of
metals, including mercury and manganese. An additional
120 soil samples were collected from the lagoon area in 2003
to evaluate concentration levels of metals. Soil samples
were also collected from locations not impacted by the site to
determine Site-specific background levels for metals.
Analytical data from the 2003 sampling activities indicated
that the metals in the lagoon area were analogous to
background concentrations and, as such, metals are not
considered to be COCs. The presence of mercury in
earlier samples (from 1991 and 1995) was of additional
concern as the form of mercury (e.g., organo-mercury or
inorganic mercury) can significantly change its toxicity. As
such, additional analyses were performed on selected
samples from the 2003 activities to determine form (or
species) of mercury present in Site soils. These analyses
determined that over 99% of the mercury present in Site
soils is in the form of inorganic mercury, which is
significantly less toxic than organo-mercury.
As stated earlier, the former lagoons are within an area
approximately 5 acres in size, but the total area of the
actual six lagoons is smaller. The total area of
contaminated soils (i.e., the six lagoons) is estimated to be
128,850 square feet (approximately 3 acres). The volume
calculations for contaminated soil are based on the actual
surface area of each lagoon, the average depth of the
overburden within each lagoon (down to bedrock), the
thickness of a distinct black-stained layer observed during
the completion of test pits, and the clean fill put on the
lagoons. The average overburden thickness was
estimated to range from 3.4 (for lagoon 6) to 13.3 feet (for
Lagoon 3). The total volume of contaminated soil is
estimated to be 30,086 cubic yards. Furthermore, it is
estimated that 20% (approximately 6,000 cubic yards) of
this is comprised of shale and cobble which will be sorted-
out prior to implementing a soil remedy. Therefore, the
remedial alternatives assessed in this Proposed Plan are
based on the total volume of contaminated soil being
24,086 cubic yards, which is equivalent to approximately
38,700 tons of contaminated soil.
Groundwater
The groundwater monitoring program included sampling of
groundwater monitoring wells located at (and bordering)
the site and analyses of these samples for organic and
inorganic compounds. These efforts were comprised of
several separate field mobilizations conducted between
1995 and 2003. The investigation was conducted in an
iterative manner, where the results of each task were used
to develop the scope of each subsequent task. The Rl
included:
• Installing permanent groundwater monitoring wells to
act as fixed monitoring and/or compliance points within
both the overburden aquifer and the bedrock aquifer.
A total of 38 groundwater monitoring wells were
installed in the study area.
• Collecting a series of groundwater samples from the
assembled monitoring network;
• Identifying the Contaminants of Potential Concern in
both aquifers;
EPA Region II - July 2007
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• Characterizing the horizontal and vertical extent of site-
related contaminants in the overburden and bedrock
aquifers and determining the extent of the groundwater
contaminant plume;
As with the contaminated soil, the primary contaminants
identified in groundwater include benzene, chlorobenzene,
ethylbenzene, toluene, xylenes and pyridine-related
compounds. These contaminants were detected above
MCLs in the wells located within the property boundary.
Residences in the vicinity of the site rely on private wells for
their potable water supply. As a precautionary measure, to
ensure that these wells are not impacted by the Site, private
wells in the immediate vicinity of the Site have routinely been
sampled for Site-related contaminants. With the exception of
minor levels of Site-related contaminants detected below
drinking water standards (e.g., MCLs) in May 2002 and
September 2003, sampling data indicates nondetectable
levels of Site-related contaminants in private wells. Also,
because of their close proximity to the Site (approximately
800 feet), the public wells located on County Highway 4,
which are used to supply drinking waterto customers served
by the Village of Maybrook, are monitored on a quarterly
basis for Site-related contaminants and must comply with the
New York State Department of Health drinking water
standards. Site-related contaminants have not been detected
in the Village of Maybrook Public Wells.
Sediment
As stated earlier, the Site is bounded by Beaverdam Brook to
the west and the Otter Kill to the south. Since the
hydrogeological link between groundwater and these water
bodies was not clear, sediment samples were collected in
1985, 1991, and 1995 from Beaverdam Brook and the Otter
Kill.
The EPA performed additional sediment sampling from the
floor of Beaverdam Brook in 2003. Groundwater flow
direction was considered to determine sampling location
points. Samples were collected from a total of 27 sampling
locations, upstream, downstream, and adjacent to the Site,
and were analyzed for volatile organic compounds and semi-
volatile organic compounds (including Site-related COCs).
Site-related COCs were not detected in these samples.
RISK SUMMARY
The purpose of the risk assessment is to identify potential
cancer risks and noncancer health hazards at the site
assuming that no further remedial action is taken. A baseline
human health risk assessment was performed to evaluate
current and future cancer risks and noncancer health hazards
based on the results of the Remedial Investigation.
A baseline ecological risk assessment was also conducted to
assess the risk posed to ecological receptors due to site-
related contamination.
WHAT IS RISK AND HOW IS IT CALCULATED?
A Superfund baseline human health risk assessment is an
analysis of the potential adverse health effects caused by
hazardous substance releases from a site in the absence of any
actions to control or mitigate these under current- and future-land
uses. A four-step process is utilized for assessing site-related
human health risks for reasonable maximum exposure scenarios.
Hazard Identification: In this step, the contaminants of concern
(COC) at a site in various media (i.e., soil, groundwater, surface
water, and air) are identified based on such factors as toxicity,
frequency of occurrence, and fate and transport of the
contaminants in the environment, concentrations of the
contaminants in specific media, mobility, persistence, and
bioaccumulation.
Exposure Assessment: In this step, the different exposure
pathways through which people might be exposed to the
contaminants identified in the previous step are evaluated.
Examples of exposure pathways include incidental ingestion of
and dermal contact with contaminated soil. Factors relating to
the exposure assessment include, but are not limited to, the
concentrations that people might be exposed to and the potential
frequency and duration of exposure. Using these factors, a
"reasonable maximum exposure" scenario, which portrays the
highest level of human exposure that could reasonably be
expected to occur, is calculated.
Toxicity Assessment: In this step, the types of adverse health
effects associated with chemical exposures and the relationship
between magnitude of exposure and severity of adverse effects
are determined. Potential health effects are chemical-specific
and may include the risk of developing cancer over a lifetime or
other noncancer health effects, such as changes in the normal
functions of organs within the body (e.g., changes in the
effectiveness of the immune system). Some chemicals are
capable of causing both cancer and noncancer health effects.
Risk Characterization: This step summarizes and combines
outputs of the exposure and toxicity assessments to provide a
quantitative assessment of site risks. Exposures are evaluated
based on the potential risk of developing cancer and the potential
for non-cancer health hazards. The likelihood of an individual
developing cancer is expressed as a probability. For example, a
10"4 cancer risk means a "one-in-ten-thousand excess cancer
risk"; or one additional cancer may be seen in a population of
10,000 people as a result of exposure to site contaminants under
the conditions explained in the Exposure Assessment. Current
Superfund guidelines for acceptable exposures are an individual
lifetime excess cancer risk in the range of 10"4 to 10"6
(corresponding to a one-in-ten-thousand to a one-in-a-million
excess cancer risk) with 10"6 being the point of departure. For
noncancer health effects, a "hazard index" (HI) is calculated. An
HI represents the sum of the individual exposure levels compared
to their corresponding reference doses. The key concept for a
non-cancer HI is that a "threshold level" (measured as an HI of
less than 1) exists below which non-cancer health effects are not
expected to occur.
EPA Region II - July 2007
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Human Health Risk Assessment
As part of the RI/FS, a baseline human health risk
assessment was conducted to estimate the risks associated
with the current and future effects of contaminants on human
health and the environment. A baseline human health risk
assessment is an analysis of the potential adverse human
health effects caused by hazardous-substance exposure in
the absence of any actions to control or mitigate these under
current and future land uses. A four-step human health risk
assessment process was used for assessing site-related
cancer risks and noncancer health hazards. The four-step
process is comprised of: Hazard Identification of Chemicals
of Potential Concern (COPCs), Exposure Assessment,
Toxicity Assessment, and Risk Characterization (see
adjoining box "What is Risk and How is it Calculated").
The human health risk estimates summarized below are
based on reasonable maximum exposure scenarios and were
developed by taking into account various conservative
estimates about the frequency and duration of an individual's
exposure to the site-related contaminants both for adults and
children, as well as the toxicity of these contaminants.
The baseline risk assessment began with selecting COPCs in
the various media (e.g., soil and groundwater) that would be
representative of site risks. The property is currently zoned
as agricultural/residential. Though the land is currently
undeveloped, the reasonably anticipated future land use,
based on its current zoning, is residential. As such, the risk
assessment was based on a future anticipated residential
land-use scenario (the most conservative scenario), though,
an open-space, park setting was also considered in the
baseline risk assessment. In addition, the potential future
use of groundwater as a drinking water source is consistent
with the State use designation of the aquifer. The baseline
risk assessment considered health effects for
trespassers/hikers, maintenance workers, and residents who
may be exposed to contaminants in the soils by ingestion,
inhalation, and dermal contact, and ingestion and inhalation
of groundwater used as a potable water supply. In this
assessment, exposure point concentrations were estimated
using either the maximum detected concentration of a
contaminant or the 95 percent upper confidence limit of the
average concentration. Chronic daily intakes were calculated
based on the reasonable maximum exposure (RME), which is
the highest exposure reasonably anticipated to occur at the
site. The RME is intended to estimate a conservative
exposure scenario that is still within the range of possible
exposures. Central tendency exposure (CTE) assumptions,
which represent typical average exposures, were also
developed. A complete summary of all exposure scenarios
can be found in the baseline human health risk assessment.
Human Health Risks
In the Human Health Risk Assessment, chemical data were
used to calculate cancer risks and noncancer health hazards
expressed as individual Hazard Quotients (HQ). These
cancer and noncancer risks, for the most conservative
scenario (namely, future residential use of the Site) are
expressed below.
EPA's statistical analysis of the groundwater sampling data
indicates that the probable exposure concentrations of
benzene (330 ug/l), xylenes (270 ug/l), 2-aminopyridine
(189 ug/l), and aniline (16 ug/l), when evaluated under
future residential exposure scenarios, are associated with
noncancer hazard quotients of 21, 4, 570, and 23,
respectively. In addition, the concentration of benzene is
associated with an excess lifetime cancer risk of 1 x 10~3.
All of these values exceed EPA's acceptable levels of
noncancer hazard or excess lifetime cancer risk.
Similarly, EPA's evaluation of the soils indicates that direct
exposure to the probable exposure concentrations of
benzene (4,440 ug/kg), toluene (10,000 ug/kg),
chlorobenzene (1,000 ug/kg), xylenes (69,000 ug/kg), and
2-aminopyridine (23,400 ug/kg) are associated with hazard
quotients of 42, 7, 5, 61, and 2, respectively. All of these
values exceed EPA's acceptable levels of noncancer
hazard. In addition, the concentration of benzene is
associated with an excess lifetime cancer risk of 1 x 10'4.
These risk and hazard levels indicate that there is
significant potential risk to receptors from direct exposure
to contaminated soil and groundwater. The risk estimates
are based on current reasonable maximum exposure
scenarios and were developed by taking into account
conservative assumptions about the frequency and
duration of an individuals' exposure to the soil and
groundwater, as well as the toxicity of these chemicals.
These calculated risks to human health indicate that action
is necessary by EPA to undertake remedial measures to
reduce the risks associated with the observed
contamination in soil and groundwater and restore the
groundwater to beneficial use.
Ecological Risk Assessment
A baseline ecological risk assessment (BERA) was
prepared to identify the potential environmental risks
associated with surface water, groundwater, sediment, and
soil. The results of the BERA suggested that there are
contaminants in groundwater, soils, and sediment, but they
are not present at levels posing significant risks to
ecological receptors. The potential for risk to ecological
receptors exposed to site-related contaminants was limited
to isolated locations, primarily in Lagoon 6, and the risk
associated with this area used the conservative assumption
that the ecological receptors (e.g., soil invertebrates,
mammalian insectivores, and carnivores) spend 100% of
their lives in the area of Lagoon 6. The contaminants that
were identified in the BERA (outside of Lagoon 6) were
determined not to pose a potential for adverse ecological
effects because they were common elements of soil that
were not related to Site operations, the detected
concentrations were lower than background levels, the
frequency of detections was low, or the HQs were only
slightly above 1 with no adverse impacts to populations
expected. A detailed presentation of these data can be
found in the Rl Report.
Risk Summary Conclusion
EPA Region II - July 2007
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Exposure to contaminated soil poses risks to human health.
Furthermore, the contaminated soil continues to be a source
of groundwater contamination. As such, it was decided that a
remedial action should be taken to reduce contamination in
the soil to levels below cleanup objectives. In addition,
exposure to contaminated groundwater poses risks to human
health. As such, it was decided that a remedial action should
be taken to restore the contaminated groundwater for future
use.
REMEDIAL ACTION OBJECTIVES
Remedial action objectives (RAOs) are media-specific goals
to protect human health and the environment. These objec-
tives are based on available information and standards such
as applicable or relevant and appropriate requirements
(ARARs), to-be-considered (TBC) guidance, and risk-based
levels established in the risk assessment.
The overall remedial action objective is to ensure the
protection of human health and the environment. The
general remedial objectives identified for the Site are to:
1. prevent exposure, to contaminated soils and
contaminated groundwater, to human and
ecological receptors;
2. minimize migration of contaminants from
soils to groundwater;
3. restore the aquifer(s) to beneficial use;
4. ensure that hazardous constituents within
the soil and groundwater meet acceptable
levels consistent with reasonably anticipated
future use; and
5. minimize potential human contact with
waste constituents.
Preliminary Remediation Goals
Preliminary Remediation Goals (PRGs) were selected based
on federal and state promulgated ARARs, risk-based levels,
background concentrations, and guidance values. These
PRGs were then used as a benchmark in the technology
screening, alternative development and screening, and
detailed evaluation of alternatives presented in the
subsequent sections of the FS Report. The PRGs for
groundwater and soil are shown in Table 1 below.
Table 1: Preliminary Remediation Goals
identified
compounds
Contaminant
Benzene
Chlorobenzene
Ethylbenzene
Toluene
Xylenes
2-amino pyridine
Pyridine
Alpha picoline
Acetone
Aniline
Pyridine-related
tentatively
PRG for
Groundwater
(ug/L) *
1
5
5
5
5
1
50
50
50
5
50
PRG for Soils
(ug/kg)
60***
1,100***
1 ,000 ***
700 ***
1 ,600 ***
400 ****
400 ****
575 ****
50 ***
1,510****
400 ****
* Groundwater cleanup levels for organic COCs are based
on the more conservative of the Federal Maximum
Contaminant Levels (MCLs) and the New York Ambient
Groundwater Standards and Guidance Values (NYSDEC
TOGs 1.1.1, June 1998).
*** The values shown are from NYSDEC Subpart 375:
Remedial Program Soil Cleanup Objectives.
**** The values shown were derived by NYSDEC based on
the Division Technical and Administrative Guidance
Memorandum: Determination of Soil Cleanup Objectives
and Cleanup Levels, Division of Hazardous Waste
Remediation, January 24, 1994.
SUMMARY OF REMEDIAL ALTERNATIVES
CERCLA Section 121(b)(1), 42 U.S.C. Section 9621 (b)(1),
mandates that remedial actions must be protective of
human health and the environment, cost-effective, comply
with other statutory laws (ARARs), and utilize permanent
solutions and alternative treatment technologies and
resource recovery alternatives to the maximum extent
practicable. Section 121(b)(1) also establishes a
preference for remedial actions which employ, as a
principal element, treatment to permanently and
significantly reduce the volume, toxicity, or mobility of the
hazardous substances, pollutants, and contaminants at a
site. CERCLA Section 121(d), 42 U.S.C. Section 9621 (d)
further specifies that a remedial action must attain a level
or standard of control of the hazardous substances,
pollutants, and contaminants, which at least attains ARARs
under federal and state laws, unless a waiver can be
justified pursuant to CERCLA Section 121(d)(4),42U.S.C.
Section 9621 (d)(4).
The objective of the feasibility study (FS) was to identify
and evaluate cost-effective remedial action alternatives
which would minimize the risk to public health and the
environment resulting from soil and groundwater
contamination at the site.
Detailed descriptions of the remedial alternatives for
addressing the contamination associated with the site can
be found in the FS report. This document presents a
summary of the six soil remediation alternatives and five
groundwater remediation alternatives that were evaluated.
The remedial alternatives are described below.
Common Elements for All Alternatives
All alternatives would include institutional controls.
Specifically, an environmental easement/restrictive
covenant would be filed in the property records of Orange
County. The easement/covenant would, at a minimum,
require: (a) with the exception of Alternative S6 -
Excavation and Off-Site Disposal, restricting any
excavation below the soil surface layer in those areas
undergoing remediation, unless the excavation activities
are in compliance with an EPA approved site management
plan; (b) restricting new construction at the Site unless an
evaluation of the potential for vapor intrusion is conducted
EPA Region II - July 2007
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and mitigation, if necessary, is performed in compliance with
an EPA approved site management plan; (c) restricting the
use of groundwater as a source of potable or process water
unless groundwater quality standards are met; and (d) the
owner/operator to complete and submit periodic certifications
that the institutional and engineering controls are in place.
A Site Management Plan (SMP) would be developed to
address soils and groundwater at the Site. The SMP would
provide for the proper management of all Site remedy
components post-construction, such as institutional controls,
and shall also include: (a) monitoring of Site groundwater to
ensure that, following the soil excavation, the contamination
is attenuating and groundwater quality continues to improve;
(b) identification of any use restrictions on the Site; (c)
necessary provisions for implementation of the requirements
of the above easement/covenant; and (d) provision for any
operation and maintenance required of the components of
the remedy.
In addition, physical controls, such as regular maintenance of
the perimeter fence, would be implemented to restrict Site
access and thereby prevent the potential exposure to
chemicals present in the soils in the vicinity of the former
lagoons.
Finally, all groundwater remedial alternatives would include
the requirement that those private wells, in the vicinity of the
Site, currently being monitored in relation to this Site will
continue to be monitored on an ongoing basis. The
frequency of the residential well sampling will be determined
during Remedial Design.
Soil Remedial Alternatives
Alternative S1 - No Action
Capital Cost: $0
Annual Cost: $0
Present-Worth Cost: $0
Construction Time: Not Applicable
The "No Action" alternative is considered in accordance with
NCP requirements and provides a baseline for comparison
with other alternatives. If this alternative were implemented,
the current status of the site would remain unchanged.
Institutional controls would not be implemented to restrict
future site development or use. Engineering controls would
not be implemented to prevent site access or exposure to site
contaminants. Although existing security fencing at the site
would remain, it would not be monitored or maintained under
this alternative.
Alternative S2 - Institutional Controls with Limited Actions
Capital Cost: $12,600
Annual Cost: $13,550
Present-Worth Cost:
Construction Time:
$217,000
3 months
This alternative is comprised of the institutional controls
mentioned previously. Physical controls would also be
used to eliminate the future potential for on-Site exposures.
A perimeter security fence (with appropriate warning signs)
has been constructed to restrict Site access and thereby
prevent the potential exposure to chemicals present in the
surface soils in the vicinity of the former lagoons. The Site
security fencing and warning signs would be routinely
inspected and maintained at the Site to restrict access to
the Site.
Institutional controls as the sole remedy would not be an
adequate substitute for engineering controls at this Site.
This Alternative would not achieve the Remedial Action
Objectives. Accordingly, this alternative will not be retained
for further consideration. Institutional controls, however, as
described in this alternative, will be retained as
components of other remedial alternatives.
Alternative S3 - Installation of a Cap Over the
Contaminated Soils
Capital Cost:
Annual Cost:
Present-Worth Cost:
Construction Time:
$2,290,000
$24,000
$2,647,000
8 months
Underthis alternative, a cap would be constructed overthe
area with contaminated soils. This area has soils above
the water table with concentrations exceeding the
NYSDEC Soil Cleanup Objectives.
Chemicals in the soils above the water table would be
contained by a cap. The cap would serve to inhibit
infiltration of precipitation and thereby reduce leaching of
chemicals from the soils to groundwater, and, therefore,
reduce chemical concentrations in the overburden and
bedrock groundwater overtime. The decreased infiltration
over the former lagoon area would result in a lowering of
the water table in the overburden aquifer directly beneath
the Site and, hence, further reduce the chemical migration
from this area via groundwater transport.
Alternative S4 - Excavation and On-Site SVE and Biocell
Capital Cost:
Annual Cost:
Present-Worth Cost:
$2,388,000
$406,000
$3,119,000
Construction Time: 2 years
This alternative would involve the excavation of the soils
within the former lagoons and treatment of the soils with
concentrations of Contaminants of Concern (COCs)
EPA Region II - July 2007
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exceeding the NYSDEC Soil Cleanup Objectives on-Site
utilizing SVE and biological degradation within an engineered
below-grade biocell. Excavated soils would be treated to
reach target cleanup levels.
The soils would be treated within the biocell by installing
perforated pipes within multiple layers of the biocell. The
perforated pipes would be connected to a blower unit to draw
air through the piles; contaminants would be volatilized into
this air. The air would be treated, if necessary, using carbon
adsorption, prior to being recirculated or exhausted to the
atmosphere. Nutrients would be added to the treatment
layers as required to enhance biological degradation.
In general, the biocell would be operated in two primary
modes: SVE mode (high airflow rate); and bioremediation
mode (low airflow rate).
During the SVE mode, the system would be operated at
higher air flow rates which would be selected to optimize the
removal of the volatile organic compounds (VOCs)
constituents using SVE. After the removal rate of the VOCs
decreases to an asymptotic or nominal rate, the system
would be switched over to the bioremediation mode. During
the bioremediation mode, the system would be operated at
an optimized air flow rate selected to sustain the aerobic
biodegradation of the remaining VOCs and semi-volatile
organic compounds (SVOCs).
Alternative S5 - In-Situ Soil Vacuum Extraction
Capital Cost:
Annual Cost:
Present-Worth Cost:
Construction Time:
$1,211,000
$460,900
$2,302,000
4 years
This alternative involves the installation of an in situ soil
vacuum extraction system (ISVE) in the area identified for
potential soil remediation. A drainage swale would be
constructed along the edge of the treatment area to prevent
surface water run-on to the treatment area.
The soil vapor extraction wells would be strategically placed
within the area of soil to be treated to ensure that airflow
within the area is maximized. The extraction wells would
consist of a screened section of pipe (or pipes) placed in a
permeable packing with the top few feet of the well grouted to
prevent the short circuit of airflow from the surface. An
impermeable temporary cap would be placed over the
treatment area to minimize infiltration of precipitation, lower
the water table and increase the volume of the unsaturated
zone, and prevent short circuiting of airflow directly from the
surface.
The extraction wells would be installed with vacuum and
positive pressures being applied at alternating well locations
to create an induced pressure gradient to move the vapors
through the soil. Extracted vapors would be treated utilizing
carbon filters, if required, prior to being reinjected or
exhausted to the atmosphere. Vapor-phase nutrients would
also be injected into the soils, if needed, to enhance
biodegradation.
Alternative S6 - Excavation and Off-Site Disposal
Capital Cost: $11,208,000
Annual Cost: $22,000
Present-Worth Cost: $11,228,000
Construction Time: 1 year
Alternative S6 involves the excavation of soils within the
former lagoons containing COCs at concentrations
exceeding NYSDEC Soil Cleanup Objectives. The
excavated soils would be disposed of off Site at an
appropriate landfill.
The Capital Cost associated with Alternative S6, as
reported in the FS Report, has a significant range because
it is not exactly known how much of the contaminated soil
would be classified as hazardous waste and would,
therefore, be more expensive to handle and dispose. The
Capital Cost cited above represents the high end of the
range. The Capital Cost associated with the low end of the
range is $5,736,000.
Alternative S6 would include the following major
components:
• pre-design investigation;
• excavation of on-site soils exceeding soil
cleanup objectives for the COCs;
• post excavation sampling to verify achievement
of soil cleanup objectives;
• disposal of excavated soils at appropriate off-site
facility (or facilities);
• backfilling of excavated areas with clean fill.
Groundwater Remedial Alternatives
Alternative GW1 - No Action
Capital Cost: $0
Annual Cost: $0
Present-Worth Cost: $0
Duration Time: 0 months
The No Action alternative was retained for comparison
purposes as required by the NCP. No remedial actions
would be implemented as part of this alternative.
Groundwater would continue to migrate and contamination
would continue to attenuate through dilution. This
alternative does not include institutional controls or long-
term groundwater monitoring.
EPA Region II - July 2007
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Alternative GW2 - Enhanced Bioremediation with Long-Term
Groundwater Monitoring
Capital Cost:
Annual Cost:
Present-Worth Cost:
Duration Time:
$13,200
$106,700
$528,000
8 years
This alternative involves the manipulation of Site groundwater
conditions to enhance in situ bioremediation of the COCs by
the indigenous microbial population. The design details for
enhanced bioremediation would be established following the
removal of the source area soils. The excavated area will be
treated with oxygenating compounds to create an aerobic
environment and, thereby, stimulate biodegradation within the
area of elevated groundwater contamination. Multiple
applications of the oxygenating compounds may be
necessary. This will be followed by a long-term groundwater
monitoring program where groundwater samples would be
collected and analyzed regularly in order to verify that the
concentrations and the extent of groundwater contaminants
are declining. The exact frequency and parameters of
sampling and location of any additional monitoring wells
would be determined during the design phase. The site-
related COCs are susceptible to degradation in aerobic
conditions. To enhance aerobic biodegradation outside of
the source area, the remedial design will consider the
controlled, location-specific injection(s) of oxygenating
compounds into the groundwater contamination plume(s) at
various locations to stimulate biodegradation of COCs.
Multiple injections overtime may also be necessary for this
action to be fully effective.
The groundwater monitoring program would be conducted to
ensure that this remedy was protective, that the
concentrations of COCs were attenuating, and to evaluate
the rates of biodegradation/bioremediation (in both the
bedrock and overburden aquifers).
Alternative GW3 - Groundwater Extraction and Treatment
(Pump And Treat)
Capital Cost:
Annual Cost:
Present-Worth Cost:
Duration Time:
$1,656,000
$229,000
$3,339,000
13 years
Under this alternative, an overburden and bedrock
groundwater collection system would be installed
downgradient of each area with identified soil and
groundwater concentrations above the potential cleanup
levels. The components of this alternative include the
installation of several strategically located bedrock
groundwater extraction wells and a water table tile collection
system installed in two areas of the overburden
(downgradient of the source area to capture both the north
and south components of the groundwater flow from the
source area). The collection systems would be designed to
minimize the migration of contaminants in groundwater and
to restore the aquifer(s) to beneficial use. The bedrock
extraction wells would pipe contaminated groundwaterto a
groundwater treatment system for treatment; the tile
collection system would route contaminated groundwater in
the overburden to the groundwater treatment system for
treatment. This alternative would prevent the potential
migration of chemicals off Site via groundwater transport.
The collected groundwater would be treated via a carbon
adsorption system located along the western edge of the
Site to meet discharge standards as well as water quality
requirements for discharge to Beaverdam Brook.
An ongoing groundwater monitoring program would be
conducted to ensure that this remedy was protective.
Alternative GW4 - Enhanced Bioremediation
Capital Cost:
Annual Cost:
Present-Worth Cost:
Duration Time:
$332,000
$106,700
$846,000
8 years
This alternative involves the manipulation of Site
groundwater conditions to enhance in situ bioremediation
of the COCs by the indigenous microbial population. The
design details for enhanced bioremediation would be
established following the treatment/removal of the source
area soils. Treatment would involve either the controlled
injection of oxygenating compounds (e.g., Oxygen
Releasing Compounds (ORCs)) to enhance biodegradation
of the COCs or the controlled injection of a chemical
oxidizer (e.g., hydrogen peroxide) and nutrients into the
groundwater contamination plumes to chemically convert
the organic contamination into nonhazardous compounds.
The preliminary design assumes that 440 injection points
would be required for the injection of ORC into the
overburden groundwater. The area would encompass both
the source area and locations downgradient of the source
area, including both the north and south components of the
groundwater flow. Multiple injections over time may be
necessary for this action to be fully effective.
An ongoing groundwater monitoring program would be
conducted to ensure that this remedy was protective, that
the concentrations of COCs were attenuating, and to
evaluate the rates of biodegradation/bioremediation (in
both the bedrock and overburden aquifers).
Alternative GW5 - Biosparging
Capital Cost: $191,000
Annual Cost: $106,700
Present-Worth Cost: $738,000
Duration Time: 8 years
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Under this alternative, pressurized gas (i.e., oxygen) would
be injected into the groundwater at very low flowrates to
enhance bioremediation. Specifically, the biosparging
technology considered here is "in situ Submerged Oxygen
Curtain" (iSOC). This technology injects supersaturated
oxygen into the groundwater such that oxygen is infused into
groundwater without the formation of bubbles. This prevents
vapors (e.g., the bubbles) from entering the vadose zone.
The vadose zone is that portion of the soil between the land
surface and the zone of saturation, or, in other words, the
vadose zone extends from the ground surface to the water
table.
An ongoing groundwater monitoring program would be
conducted to ensure that this remedy was protective.
EVALUATION OF ALTERNATIVES
In selecting a remedy for a site, EPA considers the factors set
forth in CERCLA §121, 42 U.S.C. §9621, by conducting a
detailed analysis of the viable remedial alternatives pursuant
to the NCR, 40 CFR §300.430(e)(9) and OSWER Directive
9355.3-01. The detailed analysis consists of an assessment
of the individual alternatives against each of nine evaluation
criteria and a comparative analysis focusing upon the relative
performance of each alternative against those criteria.
Overall protection of human health and the
environment addresses whether or not a remedy
provides adequate protection and describes how
risks posed through each exposure pathway (based
on a reasonable maximum exposure scenario) are
eliminated, reduced, or controlled through treatment,
engineering controls, or institutional controls.
Compliance with applicable or relevant and
appropriate requirements addresses whether or not
a remedy would meet all of the applicable or relevant
and appropriate requirements of other federal and
state environmental statutes and regulations or
provide grounds for invoking a waiver.
Lonq-Term effectiveness and permanence refer to
the ability of a remedy to maintain reliable protection
of human health and the environment over time,
once cleanup goals have been met. It also
addresses the magnitude and effectiveness of the
measures that may be required to manage the risk
posed by treatment residuals and/or untreated
wastes.
Reduction of toxicity, mobility, or volume through
treatment is the anticipated performance of the
treatment technologies, with respect to these
parameters, a remedy may employ.
Short-Term effectiveness addresses the period of
time needed to achieve protection and any adverse
impacts on human health and the environment that
may be posed during the construction and
implementation period until cleanup goals are
achieved.
Implementability is the technical and administrative
feasibility of a remedy, including the availability of
materials and services needed to implement a
particular option.
Cost includes estimated capital and operation and
maintenance costs, and net present-worth costs.
State acceptance indicates whether, based on its
review of the RI/FS reports and the Proposed
Plan, the State concurs with, opposes, or has no
comment on the preferred remedy at the present
time.
Community acceptance will be assessed in the
ROD, and refers to the public's general response
to the alternatives described in the Proposed Plan
and the RI/FS reports.
A comparative analysis (one for soils and one for
groundwater) of these alternatives, based upon the
evaluation criteria noted above, follows.
Comparative Analysis for Soils
Overall Protection of Human Health and the
Environment
Alternatives S1 and S2 would not be protective of
human health and the environment, since they
would not actively address the contaminated soils,
which present unacceptable risks of exposure and
are a source of groundwater contamination.
Alternative S3 would be protective of human health
and the environment in that the cap would prevent
exposure to contaminated soil and would also
serve to minimize infiltration of precipitation and
thereby reduce leaching of chemicals from the
soils to groundwater, hence, reducing
contamination of the groundwater; however,
Alternative S3 would not actively remediate
contaminated soil. Alternatives S4, S5, and S6
would be protective of human health and the
environment, since each alternative relies upon a
remedial strategy or treatment technology capable
of eliminating human exposure and removing the
source of groundwater contamination.
Compliance with ARARs
The soil cleanup objectives used for the Site are
based on NYSDEC values (NYSDEC Subpart375:
Remedial Program Soil Cleanup Objectives -
and/or- NYSDEC's Division Technical and
Administrative Guidance Memorandum:
Determination of Soil Cleanup Objectives and
Cleanup Levels, Division of Hazardous Waste
Remediation, January 24, 1994.) These NYSDEC
soil cleanup objectives were utilized as PRGs for
the site-related contaminants.
EPA Region II - July 2007
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Since the contamination in the soils would not be
addressed under Alternatives S1 and S2, they would
not achieve the soil cleanup objectives. While the
cap installed under Soil Alternative S3 would comply
with RCRA design standards, this alternative would
not actively remediate contaminated soil and, as
such, would not achieve the soil cleanup objectives.
Alternatives S4 and S5 would each attain the soil
cleanup objectives specified. Alternative S6 would
involve the excavation and removal of the
contaminated soil from the site, and thereby achieve
soil cleanup objectives for the Site property.
Alternatives S4 and S6 both involve the excavation
of contaminated soils and would, therefore, require
compliance with fugitive dust and VOC emission
regulations. In addition, Alternative S6 would be
subject to New York State and federal regulations
related to the transportation and off-site
treatment/disposal of wastes. In the case of
Alternatives S4 and S5, compliance with air emission
standards would be required for the SVE or ISVE
system. Specifically, treatment of off-gases would
have to meet the substantive requirements of New
York State Regulations for Prevention and Control of
Air Contamination and Air Pollution (6 NYCRR Part
200, et seq.) and comply with the substantive
requirements of other state and federal air emission
standards.
Lonq-Term Effectiveness and Permanence
Alternatives S1 and S2 would not involve any active
remedial measures, and, as such, not be effective in
eliminating the potential exposure to contaminants in
soil and would result in the continued migration of
contaminants from the soil to the groundwater.
Alternative 3 involves installation of a landfill cover
which would eliminate the potential exposure to
contaminants in the soil and also reduce leaching of
contaminants from the soil to groundwater.
Alternatives S4, S5, and S6 would each be effective
in the long term by either removing the contaminated
soils from the Site or treating them in place.
Reduction in Toxicity, Mobility or Volume
Alternatives S1 and S2 would provide no reduction in
toxicity, mobility, or volume of contaminants.
Alternative S3 would reduce the migration of
contaminants from soil to groundwater but would not
provide a reduction in toxicity or volume of
contaminants. Alternatives S4 and S5 would reduce
toxicity, mobility, and volume of contaminants
through on-site treatment. Under Alternative S6, the
toxicity, mobility, and volume of the contaminants
would be eliminated by removing contaminated soil
from the Site property.
Short-Term Effectiveness
Alternative S1 and S2 do not include any physical
construction measures in any areas of contamination
and, therefore, would not present any potential
adverse impacts to on-property workers or the
community as a result of their implementation.
Alternatives S3, S4, S5, and S6 could result in
some adverse impacts to on-property workers
through dermal contact and inhalation related to
the installation of the remedial systems associated
with each of these alternatives. Alternatives S4
and S6 involve significant excavation activities that
would need to be properly managed to prevent or
minimize adverse impacts. For instance,
excavation activities would need to be properly
managed to prevent transport of fugitive dust and
exposure of workers through dermal contact and
by inhalation of volatile organic compounds in the
air. Noise from the treatment unit and the
excavation work associated with Alternatives S3,
S4, S5, and S6 could present some limited
adverse impacts to on-property workers, while
truck traffic related to Alternative S6 could provide
nuisance impacts (e.g., noise and traffic) to nearby
residents. In addition, interim and post-remediation
soil sampling activities would pose some risk to
on-property workers. The risks to on-property
workers and nearby residents under all of the
alternatives could, however, be mitigated by
following appropriate health and safety protocols,
by exercising sound engineering practices, and by
using proper protective equipment.
Alternatives S4 and S6 involve significant
excavation activities that would need to be
properly managed to prevent or minimize adverse
impacts. For instance, excavation activities would
need to be properly managed to prevent transport
of fugitive dust and exposure of workers to volatile
organic compounds in the air.
Since no actions would be performed under
Alternative S1, there would be no implementation
time. Since only limited actions would be
performed under Alternative S2, there would be
very little implementation time. It is estimated that
Alternative S3 would require 3 months to complete
the landfill cap, Alternative S4 would require 2
years to complete, Alternative S5 would require 4
years to complete, and Alternative S6 would
require approximately one year to complete.
Implementability
Alternatives S1 and S2 would be the easiest soil
alternatives to implement in that there are no field
activities to undertake.
Alternatives S3, S4, S5, and S6 would all employ
technologies known to be reliable (though the
biocell proposed as a component of Alternative S4
is a lesser known technology relative to the site-
related COCs) and that can be readily
implemented. In addition, equipment, services,
and materials needed for these alternatives are
readily available, and the actions under these
alternatives would be administratively feasible.
Furthermore, sufficient facilities are available for
EPA Region II - July 2007
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the treatment/disposal of the excavated materials
under Alternative S6.
Monitoring the effectiveness of the SVE system (in
Alternative S4), and the ISVE system (in Alternative
S5) would be easily accomplished through soil and
soil-vapor sampling and analysis. Under Alternatives
S4, S5, and S6, determining the extent of soil
cleanup would be easily accomplished through post-
excavation soil sampling and analysis.
Cost
The estimated capital, annual operation and
maintenance (O&M) (including monitoring), and
present-worth costs for each of the soil remediation
alternatives are presented in Table 2. All costs are
presented in U.S. Dollars.
Table 2: Cost Analysis for Soil Remediation Alternatives
Remedial
Alternative
S1
S2
S3
S4
S5
S6
Capital
Cost
0
12,600
2,290,000
2,388,000
1,211,000
5,736,000
Annual
O&M
Cost
950
13,550
24,000
406,000
460,900
22,000
Present
Worth
Cost
15,000
217,000
2,647,000
3,119,000
2,302,000
5,756,000
Construction
Time
No time
Months
Several
months to
install cap
2 years
4 years
1 year
According to the capital cost, O&M cost and present
worth cost estimates, Alternative S1 has the lowest
cost and Alternative S6 has the highest cost when
comparing all Alternatives.
Comparative Analysis for Groundwater
Overall Protection of Human Health and the
Environment
All alternatives except GW1 would provide adequate
protection of human health and the environment. As
noted above in the risk assessment section, there
are unacceptable human health cancer risks or non-
cancer health hazards associated with the
groundwater contamination at the site. Though no
private wells exist on the Site property, the future use
of groundwater as a drinking water source is
consistent with the State use designation of the
aquifer and such use would present unacceptable
present and future carcinogenic and noncarcinogenic
risks at the Site. These calculated risks to human
health require EPA to enact remedial measures to
reduce the risks associated with the observed
contamination and restore the groundwater to
beneficial use. EPA believes that Alternatives GW2,
GW4 and GW5 would ultimately provide full
protection of human health by reducing
contaminant concentrations to cleanup objectives.
Alternative GW3 would also reduce contaminant
concentrations through treatment, would prevent
migration of chemicals off-Site via groundwater
transport, and, ultimately, restore the aquifer(s) to
best use.
Compliance with ARARs
EPA and the New York State Department of
Health (NYSDOH) have promulgated health-based
protective MCLs (40 CFR Part 141, and
10NYCRR, Chapter 1 and Part 5), which are
enforceable standards for various drinking water
contaminants (chemical specific ARARs). The
aquifer at the Site is classified as Class GA (6
NYCRR 701.18), meaning that it is designated as
a potable water supply.
Alternative GW1 does not include any active
groundwater remediation; contamination in the
groundwater would likely attenuate naturally, to
some degree, particularly after a soil remedy is
implemented. Alternatives GW2, GW4, and GW5
involve the manipulation of Site groundwater
conditions to enhance in situ bioremediation of the
COCs by the indigenous microbial population, and,
thereby, break-down the COCs into non-
hazardous compounds. Alternatives GW2, GW4,
and GW5, each focus on the most contaminated
regions of the bedrock and overburden aquifers
(e.g., under and immediately downgradient of the
source area) and, as such, would decrease the
amount of time needed to achieve cleanup
objectives. Following implementation of
Alternatives GW2, GW4 or GW5, it is estimated
that ARARs would be achieved throughout the Site
within ten years after the soil remedy is
implemented. Under Alternative GW3,
groundwater would be extracted from both the
bedrock and the overburden aquifers, treated by a
carbon adsorption system, and discharged to
Beaverdam Brook. The discharge to Beaverdam
Brook would comply with surface water discharge
requirements and the disposition of treatment
residuals would have to be consistent with the
Resource Conservation and Recovery Act
(RCRA). Alternative GW3 would prevent the
potential migration of chemicals off Site via
groundwatertransport and, as such, ARARs would
be met downgradient of the groundwater
containment system (e.g., off the site property);
ultimately, treatment of the contaminated
groundwater would achieve ARARs within the site
property and would restore the aquifer(s) to best
use.
For Alternatives GW2, GW3, GW4, and GW5,
compliance with ARARs would be demonstrated
through a long-term groundwater monitoring
program.
EPA Region II - July 2007
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Long-Term Effectiveness and Permanence
Once the source control remedy is implemented, it is
anticipated that all of the groundwater alternatives
would achieve groundwater ARARs, although
Alternative GW1 would be expected to take the
longest. The time to achieve groundwater standards
would vary for the other alternatives due to the
complex nature of the subsurface environment.
Alternative GW3 would prevent the potential
migration of chemicals off Site via groundwater
transport, but would take longer to achieve cleanup
objectives than Alternatives GW2, GW4, or GW5.
As Alternatives GW2, GW4, and GW5 focus on the
most contaminated regions of the bedrock and
overburden aquifers, these alternatives would be
expected to achieve aquifer restoration more quickly
than the other alternatives.
Reduction in Toxicity, Mobility or Volume
Alternatives GW2, GW4, and GW5 would each
reduce the volume and toxicity of the contaminants
through treatment by chemically breaking down the
bulk of the dissolved VOC and SVOC contamination
as it migrates through the aquifer. The VOC and
SVOC contaminants would be changed into
degradation products.
Alternative GW3 would reduce the toxicity, mobility,
and volume of contaminated groundwater through
removal and treatment with the goal of restoring the
aquifers to their beneficial uses.
GW1 provides no further reduction in toxicity,
mobility or volume of contaminants of any media
through treatment. Following implementation of the
source area remedy, natural attenuation processes
would likely occur to some degree even under this
alternative. Future risks posed by the site will
depend on future site usage.
Short-Term Effectiveness
Alternative GW1 presents virtually no change to the
short-term impacts to human health and the
environment since no construction or active
remediation is involved. Alternatives GW2, GW3,
GW4, and GW5 each present some risk to on-
property workers through dermal contact and
inhalation from activities associated with
groundwater remediation. Specifically, construction
and remedial activities required to implement
Alternatives GW2, GW4, and GW5 would potentially
pose a risk of worker exposure to the oxygenating
compound(s) when injected into the aquifer. The
possibility of having to readminister oxygenating
compound(s) in future injections is likely. Alternative
GW3 would potentially result in greater short-term
exposure to contaminants to workers who install
extraction wells and the groundwater tile collection
system, as well as come into contact with the
treatment system. In addition, under Alternatives
GW2, GW3, GW4, and GW5, some adverse
impacts would result from disruption of traffic,
excavation activities, noise, and fugitive dust
emissions. However, proper health and safety
precautions would minimize short-term exposure
risks as well as disturbances.
Implementability
Alternative GW1 would be the easiest groundwater
alternative to implement, since it would require no
activities. Alternative GW3 would be the most
difficult alternative to implement in that it would
require the construction of a groundwater
extraction system including piping and a tile water
collection system. Alternative GW2 would be
easier to implement than Alternatives GW4 and
GW5. The services and materials necessary for
each of the groundwater alternatives are readily
available. Under Alternatives GW2, GW3, GW4,
and GW5, groundwater sampling would be
necessary to monitor treatment effectiveness.
Each of the alternatives have been proven
effective for most, if not all, of the COCs in
groundwater.
Cost
The estimated capital, annual operation and
maintenance (O&M) (including monitoring), and
present-worth costs for each of the soil
remediation alternatives are presented in Table 3.
All costs are presented in U.S. Dollars.
Table 3: Cost Comparison for Groundwater Remediation
Alternatives
Remedial
Alternative
GW1
GW2
GW3
GW4
GW5
Capital
Cost
0
13,200
1,656,000
332,000
191,000
Annual
Cost
950
106,700
229,000
106,700
106,700
Present
Worth
15,000
528,000
3,339,000
846,000
738,000
Duration
of
Operation
N/A
8 years
1 3 years
8 years
8 years
According to the capital cost, O&M cost and
present worth cost estimates, Alternative GW1 has
the lowest cost and GW3 has the highest cost
when comparing all alternatives.
State Acceptance
NYSDEC concurs with the preferred remedy.
Community Acceptance
Community acceptance of the preferred remedy
will be assessed in the ROD following review of
the public comments received on the Post
Decision Proposed Plan.
EPA Region II - July 2007
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PREFERRED ALTERNATIVES
Basis for the Remedy Preference
Based upon an evaluation of the various alternatives, EPA
recommends employing Alternative S4 (Excavation and On-
Site SVE and Biocell) to remediate the source area and
Alternative GW2 (Enhanced Bioremediation with Long-Term
Groundwater Monitoring) to remediate the groundwater.
Implementation of these alternatives would include
institutional controls to restrict groundwater use and prevent
disturbance of the soils in the biocell until groundwater
ARARs and/or soil cleanup objectives are met.
Specifically, an environmental easement/restrictive covenant
would be filed in the property records of Orange County. The
easement/covenant would, at a minimum, require: (a)
restricting any excavation below the soil surface layer in the
area of the biocell, unless the excavation activities are in
compliance with an EPA-approved site management plan; (b)
restricting new construction at the Site unless an evaluation
of the potential for vapor intrusion is conducted and
mitigation, if necessary, is performed in compliance with an
EPA approved site management plan; (c) restricting the use
of groundwater as a source of potable or process water
unless groundwater quality standards are met; and (d) the
owner/operator to complete and submit periodic certifications
that the institutional and engineering controls are in place.
A Site Management Plan (SMP) would be developed to
address soils and groundwater at the Site. The SMP would
provide for the proper management of all Site remedy
components post-construction, such as institutional controls,
and shall also include: (a) monitoring of Site groundwater to
ensure that, following the soil excavation, the contamination
is attenuating and groundwater quality continues to improve;
(b) identification of any use restrictions on the Site; (c)
necessary provisions for implementation of the requirements
of the above easement/covenant; and (d) provision for any
operation and maintenance required of the components of
the remedy.
Upon completion of remediation, no hazardous substances
would remain above levels that would prevent unlimited use
or unrestricted exposure. Under the preferred remedy, EPA
would conduct reviews of the site at least once every five
years until groundwater remediation has restored the
aquifer(s) to drinking water quality standards and soil cleanup
objectives are met.
EPA believes that Alternative S4 is the most cost-effective
option for the contaminated soils given the evaluation
criteria and reasonably anticipated future land use. While
Alternative S4 may involve potential short-term community
impacts in the form of nuisances associated with
construction (e.g., noise and truck traffic), Alternative S4
would be protective of human health and the environment.
Furthermore, Alternative S4 would provide a permanent
solution, and would achieve soil cleanup objectives forthe
site-related COCs in the shortest amount of time and in the
most cost-effective manner. Therefore, EPA and NYSDEC
believe that Alternative S4 would effectuate the soil
cleanup while providing the best balance of tradeoffs with
respect to the evaluating criteria.
Alternative S1 was not identified as the preferred
alternative because it calls for no action and would not be
protective of human health and the environment. Similarly,
Alternative 2 would only provide limited action by imposing
institutional controls and site fencing and warning
maintenance signs. Alternative 3 was not proposed
because, while it is slightly less expensive than Alternative
4, it calls for containment of the waste constituents and
provides no treatment of the contamination. Alternative 5
was not proposed because, while it includes the soil vapor
extraction technology of Alternative 4, it does not include
the biological treatment component, which EPA believes
will be effective in addressing the pyridine-related
compounds. Alternative 6 was not proposed because it
would not appear to be cost-effective compared to the
other alternatives.
EPA is proposing Alternative GW2 to address the
contaminated groundwater because the Agency believes it
would be protective of human health and the environment
and would achieve the ARARs in the most cost-effective
manner. Alternative GW1 would rely solely on natural
processes to restore groundwater quality to beneficial use,
and, as such, would take significantly longer than the
preferred alternative. While Alternative GW3 would prevent
the potential migration of chemicals off Site via
groundwater transport, it would take longer to achieve
cleanup objectives and would cost significantly more than
Alternatives GW2, GW4, and GW5. While Alternatives
GW2, GW4, and GW5 are similar in that they each involve
the addition of oxygen into the groundwater environment to
enhance biodegradation of the contaminants, Alternative
GW2 would be easier to implement then the other
alternatives, and is expected to cost significantly less.
Therefore, EPA and NYSDEC believe that the combination
of Alternatives S4 and GW2 would successfully remediate
the contaminated soils and expedite the remediation of
contaminated groundwater at the Site, while providing the
best balance of tradeoffs among the alternatives with
respect to the evaluation criteria. Furthermore, the
preferred remedies would utilize permanent solutions and
treatment technologies to the maximum extent practicable.
EPA Region II - July 2007
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SOURCE: USGS MAYBROOK NEW YORK AND
GOSHEN NEW YORK QUADRANGLE MAP
LOCATION
SOURCE: RAND McNALLY ROAD ATU\S
figure 1
SITE LOCATION
FORMER LAGOON SITE
Hamptonburgh, New York
EPA Region II - July 2007
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EPA Region II - July 2007
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