PB95-963904
EPA/ROD/R03-95/193
March 1995
EPA Superfund
Record of Decision:
Standard Chlorine of Delaware, Inc.,
Delaware City, DE
3/9/1995
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RECORD OF DECISION
STANDARD CHLORINE OF DELAWARE SITE
DECLARATION
SITE NAME AND LOCATION
Standard Chlorine of Delaware
New Castle, Delaware
STATEMENT OF BASIS AND PURPOSE
This Record of Decision (ROD) presents the selected remedial
action for the Standard Chlorine of Delaware Site in New Castle,
Delaware.. The selected remedy was chosen in accordance with the
.Comprehensive Environmental Response, Compensation and Liability
Act of 1980 (CERCLA), as amended by the Superfuhd Amendments and
Reauthorization Act of 1986, 42 U.S.C. § 9601 et seq_._ and the
National Oil and Hazardous Substances Pollution Contingency Plan
(NCP), 40 CFR Part 300. This decision is based on the
Administrative Record for this Site.
The Delaware Department of Natural Resources and Environmental
Control (DNREC), acting on behalf of the State of Delaware, has
concurred with the selected remedy (See attached letter dated
February 23, 1995.
ASSESSMENT OF THE SITE
Standard Chlorine of Delaware is an operating plant which
continues to produce, chlorinated benzenes. The remedies selected
in this ROD do not address any potential risk posed by the Site
in the day-to-day operations of the manufacturing facility.
Pursuant to duly delegated authority, I hereby determine, in
accordance with Section 106 of CERCLA, 42 U.S.C.. § 9606, that
actual or threatened releases of hazardous substances from this
Site, as discussed in the Summary of Site Risks, if not addressed
by implementing the response action selected in this Record of
Decision (ROD), may present an imminent and substantial
endangerment to public health, welfare, or the environment.
DESCRIPTION OF THE SELECTED REMEDY
The selected remedy consists of two components: an interim action
for the ground water and a final action for the soils and
sediments. The interim action component will address
containment of the ground water; the final action will address
treatment of the contaminated soils and sediments.
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Interim Action for Ground Water
The interim action for the ground water addresses containment of
ground water to minimize the continued release of contaminants.
The interim action includes the following steps:
Construct a subsurface physical barrier such as a
trench or slurry wall to contain ground water and Dense
Non-aqueous Phase Liquids (DNAPLs)
Install low-volume recovery wells to remove pools of
DNAPLs which are identified during remedial design
Repair and upgrade (if necessary) the existing ground
water pump-and-treat system
Treat contaminated ground water in the .existing waste
water treatment plant along with treatment of all
resulting air emissions
Establish institutional controls to include deed
restrictions and a Ground Water Management Zone (GWMZ)
Determine the extent of ground water and DNAPL
contamination
Evaluate the technical practicability of remediating
ground water to health-based levels.
Final Action for Soils/Sediments
The preferred final action for soils and sediments is biological
treatment. This innovative technology has the potential for
substantial risk reduction 'at a much lower cost than thermal
treatment. The major steps of biological treatment are as
follows:
Conduct biological treatability/pilot-scale studies to
determine the ability of biological treatment to reduce
the concentration of contaminants in the soils and
sediments to cleanup criteria
Bioremediate the soils/sediments along the western
drainage gully, the eastern drainage ditch, the soils
. adjacent to Catch Basin #1, those along the railroad
tracks and along the unnamed tributary to Red Lion
Creek, in addition to those soils in the waste piles
and in the sedimentation basin using in situ (in place)
or ex situ (excavated) treatment.
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Contingency Action for Soils/Sediments
If based on the results of the treatability studies or further
testing during the remedial design phase, it is determined that
bioremediation is not feasible for this Site, the preferred
contingency remedy is Low Temperature Thermal Desorption (LTTD).
The contingency remedy (LTTD) includes the following steps:
Excavate and treat the soils/sediments along the
western drainage gully, the eastern drainage ditch, the
soils adjacent to Catch Basin #1, those in the waste
piles and in the sedimentation basin, as well as the
soils along the unnamed tributary to Red Lion Creek
Construct a low permeability asphalt cap along the
railroad tracks and adjacent to Catch Basin #1
_ Restore the wetlands damaged by the remedial action.
DECLARATION OP STATUTORY DETERMINATIONS
The selected remedy for ground water is an interim action and is
protective of human health and the environment. Compliance with
Federal and State requirements that are legally applicable or
relevant and appropriate will be determined when EPA makes a
final decision on the ground water remedy in a future ROD.
The selected final remedy for soils and sediments is protective
of human health and the environment, complies with Federal and
State requirements that are legally applicable or relevant and
appropriate to the remedial action, and is cost-effective. This
remedy utilizes permanent solutions and alternative treatment
technologies to the maximum extent practicable and it satisfies
the statutory preference for a remedy that employs treatments
that reduce toxicity, mobility, or volume as their principal
element.
Because the selected remedy will result in hazardous substances
remaining onsite above health-based levels, a review under
Section 121 (c) of CERCLA, 42 U.S.C. §9621(c) will be conducted
within five years after initiation of the remedy to ensure that
the selected remedy is providing protection of human health and
the environment.
Thomas C. Volt/aggio/ Dipe'ctor Date
Hazardous WastN^^rtagement Division
Region III
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DECISION SUMMARY
1.0 SITE HISTORY AND ENFORCEMENT ACTIVITIES
The Standard Chlorine of Delaware, Inc. ("SCD" or "Standard
Chlorine") Superfund Site ("Site" or "SCD Site"), approximately
40 acres in size, is located three miles northeast of Delaware
City, Delaware. The SCD plant facility is bounded to the north
and east by property owned by Occidental Chemical Corporation
(formerly Diamond Shamrock Company),.to the west by Air Products
and Chemicals, Inc. and to the south by Governor Lea Road and
property owned by Star Enterprise and Delmarva Power and Light.
Red Lion Creek is located approximately 1,000 feet north of the
SCD plant facility and flows east to the Delaware River (See
Figure 1). .The SCD facility was constructed in 1965 on farmland
purchased from the Diamond Alkali Company which had purchased the
land from the Tidewater Refinery Company. SCD operations were
started in 1966 with the production of chlorinated benzene
compounds including chlorobenzene, paradichlorobenzene,
orthodichlorobenzene, and lesser amounts of metadichlorobenzene
and trichlorobenzene. Although operational production has varied
over the years, these chemicals are still the primary products
produced at the SCD facility.
1.1 Past Releases and Remedial Responses
In September 1981, a release of approximately 5,000 gallons of
monochlorobenzene ("MCB") occurred at the SCD Site while workers
were filling a railroad tank car. Some of the released chemical
ran off in surface ditches toward a tributary to the Red Lion
Creek. Figure 2 shows the approximate 1981 release flow pathway.
In response to this spill, under.the direction of the Delaware
Department of Natural Resources and Environmental Control
("DNREC"), SCD moved to prevent the discharge of MCB to the Red
Lion Creek. First, SCD took action to contain and recover the
surface runoff. Second, SCD excavated and disposed of
contaminated soils at an off-site permitted commercial facility.
Finally, SCD conducted an investigation to determine the extent
of contamination to the subsurface.
SCO's investigation revealed that the ground water beneath the
Site was contaminated with other chlorinated benzene compounds,
in addition to MCB. The primary source for the other chlorinated
benzene was attributed to a leaking .process drainage catch basin
(CB#1), which was discovered and repaired in March 1976. SCD
installed a ground water recovery and treatment system in 1982.
This system has been upgraded over time. The current
configuration was implemented after a second major release from
the facility which occurred in 1986 and is discussed below.
Monitoring of the ground water recovery and treatment system is
performed by SCD and has been documented in quarterly reports to
DNREC since 1988.
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The second major release occurred at the SCD facility on January
5, 1986 when approximately 400,000 gallons of paradichlorobenzene
("DCB") and approximately 169,000 gallons of trich'lorobenzene
("TCB") were released at the Site due to a total above ground
tank failure. The released material followed two pathways of
flow, one easterly, onto asphalt paved plant property and one
northerly, along the railroad tracks (Figure 3 shows the
approximate flow pathways). The released material spread to the
unnamed tributary of Red Lion Creek, adjacent to the SCD
facility, and continued downstream to the point of confluence
with Red Lion Creek (See Figure 4). -At the time of the release,
the tide in Red Lion Creek was high and ebbing; consequently,
some of the contaminants migrated from the mouth of the tributary
upstream along the southern shoreline of Red Lion Creek.
SCD used booms, dikes and a filter fence to contain and minimize
further discharge of contamination through the unnamed tributary
into the Red Lion Creek. Some of the spilled material was
recovered for reprocessing. SCD built a sedimentation basin to
store contaminated sediments. Contaminated soils and sediments
were also excavated and stockpiled in waste piles adjacent to
the SCD 'facility (identified as soil piles in Figure 4).
1.2 Enforcement Activities
In 1982, EPA and DNREC conducted a Preliminary Assessment/Site
Inspection ("PA/SI") to determine if the Site was eligible for
inclusion on the National Priorities List ("NPL"). As a result
of the above-described releases, the SCD Site was placed on the
NPL on July 1,. 1987. On January 12,-1988, SCD entered into a.
Consent Order with DNREC to conduct a Remedial
Investigation/Feasibility Study ("RI/FS") at the Site. This
Consent Order was subsequently amended in November 1988.
Pursuant to Section 113(k)(2)(B)(i-v) of the Comprehensive
Environmental Response, Compensation, and Liability Act of 1980
("CERCLA"), as amended, the RI/FS reports and the Proposed
Remedial Action Plan- ("Proposed Plan") for this Site were
released to the public for comment on April 4, 1994.
2.0 HIGHLIGHTS OF COMMUNITY PARTICIPATION
The Proposed Plan for the Site and all other documents that were
used in developing the Proposed Plan are available to the public
in the Administrative Record file located at the EPA Docket Room
in Region Ill's Philadelphia office and the DNREC office in New
Castle, Delaware. The notice of availability of these documents
was published in The Wilmington News Journal on April 4, 1994.
Following this announcement, EPA mailed approximately 3,00.0 fact
sheets to residents who live within a one-half mile radius of the
Site. The fact sheet summarized the six alternatives that
address the long-term clean-up of the Site and outlined EPA's
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preferred alternative as described in the Proposed Plan.
A public comment period on the documents was originally scheduled
from April 4, 1994 to May 4, 1994. However, Standard Chlorine
requested a first extension, and 30 days were added to the
comment period, extending it to June 4, 1994. In a letter dated
May 31, 1994, Standard Chlorine requested information from EPA as
well as a second extension of the public comment period. EPA had
no written documentation to respond to this additional request,
and in turn, EPA granted Standard Chlorine an extension until
June 8, 1994 to submit comments on the Proposed Plan.
EPA held a public meeting on the Proposed Plan on April 27, 1994,
at the'Carpenters Local 626 Union Hall in New Castle, Delaware.
The public was notified of the meeting by advertisements that ran
in the April 4, 1994 edition of the Wilmington News Journal and
the.April 7, 1994 edition of the New Castle Weekly. The mailed
fact sheet also gave.notice of the public meeting. The meeting
was attended by local residents, state and federal officials, and
representatives from Standard Chlorine.
At this meeting, EPA representatives answered questions
about conditions at the Site and the remedial alternatives under
consideration. A response to the comments received during the
public comment period, including those expressed verbally at the
public meeting, is included in the Responsiveness Summary, which
is part of this Record of Decision.
This ROD presents the selected remedial action for the
Standard Chlorine of Delaware Site in New Castle County,
Delaware, chosen in accordance with CERCLA and the National Oil
and Hazardous Substances Pollution Contingency Plan (NCP) , 40
C.F.R. Part 300. The decision for this Site is based on the
Administrative Record which is available at the above-mentioned
locations.
3.0 SUMMARY OF SITE CHARACTERISTICS
The RI was designed to define the extent of contamination in the
soil, sediments, surface water, and ground water associated with.
the 1981 and 1986 releases. The RI was designed to provide data
to support a feasibility study of potential remedial actions.
Data collected during the RI determined that soils, sediments and
ground water at the Site are contaminated with chlorinated
benzene compounds. The areas/media evaluated as part of the RI
are shown on Figure 4 and include the following:
1. Soils- surface and subsurface soils in the pathways of the
1981 and the 1986 releases;
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2. Sediments - in the unnamed tributary and the Red Lion Creek;
3. Surface Water - in the sedimentation basin, the unnamed
tributary, and the Red Lion Creek;
4. Ground Water - throughout the Site;
5. Soil Piles and Soil Pile Runoff. Areas - clean-up activities
associated with the 1986 release resulted in the consolidation of
soil and sediments into waste piles;
6. Sedimentation Basin- saturated soils and sediments were
excavated as part of the 1986 spill clean-up and were placed in a
double-lined basin. The integrity of the liner system is
suspect;
7. Catch Basin #1 (CB#1)- a settling unit, fed by a process
sewer line, in which the heavier chlorinated benzene compounds
from SCD manufacturing operations settle and are recycled to the
SCD production process; and
8. Effluent Pipeline- an underground wastewater pipeline which
runs from SCD's facility to the Delaware River.
3.1 Soils /Sediments
The RI findings revealed that surface soils, subsurface soils and
sediments along the pathways of the 1981 and 1986 releases were
contaminated with chlorinated benzene as were the soil piles and.
sedimentation basin that were built following the 1986 release.
Figures 5 and 6 show the concentration of total chlorinated
benzene compounds for samples collected in the pathways of the
1981 and 1986 .releases. Figure 7 shows the sediment analytical
results from samples collected along the unnamed tributary to Red
Lion Creek and Figure 8 shows the sediment analytical results
from samples collected from Red Lion Creek. The concentration of
total chlorinated benzene compounds in on-site surface soils
(soils inside the existing fence of the SCD plant and noted as
the SCD facility boundary on Figure 2} ranged from 1.2 mg/kg to
68,427 mg/kg with an arithmetic mean concentration of 4,452
mg/kg. Typically, the concentrations of chlorinated benzene are
much lower in the subsurface. The concentration of total
chlorinated benzene compounds for off-site surface soils (soils
outside the existing fence of the SCD plant and noted as the SCD
facility boundary on Figure 2) ranged from 1 mg/kg to 87,691
mg/kg, with an arithmetic mean concentration of 3,742 mg/kg. The
concentration of total chlorinated benzene compounds for off-site
sediments ranged from 0.5 mg/kg to 178,228 mg/kg with an
arithmetic mean concentration of 4,199 mg/kg. Tables 1, 2 and 3
provide more detail on the range of concentrations for the
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individual compounds analyzed.
Sediments in the sedimentation basin are contaminated with
chlorinated benzene. A composite sample from three grab samples
contained 43,931 mg/kg of chlorinated benzene compounds. The
presence of site-specific chemicals in the monitoring zone,
located between the primary and secondary liners, indicates that
the integrity of the primary or upper basin liner is suspect.
Water in the sedimentation basin is periodically pumped to the
SCD's existing waste water treatment plant.
Subsurface soil sampling in the vicinity of Catch Basin #1
revealed elevated levels of contaminants to a depth of
approximately 32 feet below the surface. CB#1 was excavated and
repaired in 1976 because of a leak. Currently, an inspection of
the integrity of CB#1 is conducted annually by SCD.
3.2 Surface Water
Based oh the findings of the draft Remedial Investigation ("RI"),
EPA and DNREC limited the boundaries of the Red Lion Creek
investigation to the area west of Route 9 (See Figure 4).
Occidental Chemical Company ("Oxychem"), a company whose property
is located adjacent to that of Standard Chlorine, is under an
Administrative Order on Consent with EPA, under the Resource
.Conservation and Recovery Act ("RCRA"), to conduct a RCRA
Facility Investigation and Corrective Measure Study ("RFI/CMS")
(similar to a RI/FS), which will address the investigation of Red
Lion Creek east of Route 9. Information obtained from Oxychem's
investigation is being shared by both RCRA and CERCLA
investigatory .groups at EPA. Depending on the results of the
RFI, EPA may require Standard Chlorine to conduct additional
remedial work concerning Red Lion Creek.
Low levels of chlorinated benzene compounds were detected in
surface water samples collected from the unnamed tributary to Red
Lion Creek and Red Lion Creek. The concentrations ranged from 10
to 360 micrograms per liter (ug/1) . The concentrations of
chlorinated benzene compounds were generally higher in samples
collected from surface water in the unnamed tributary to Red Lion
Creek'than in.samples collected from the Red Lion Creek. This is
probably due to the presence of contaminated soils and sediments
adjacent to and along the unnamed tributary to Red Lion Creek.
Surface waters in the sedimentation basin, the unnamed tributary,
and the Red Lion Creek contain chlorinated benzene compounds. An
advisory issued by DNREC and the Delaware Division of Public
Health on May 2, 1986 recommending that the public not consume
fish taken from Red Lion Creek downstream of Route 13 is
currently in effect.
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3 .3 Ground Water and Hydrogeology
The SCD Site lies within the Atlantic Coastal Plain Physiographic
Province, which consists .of a southeasterly dipping wedge of
unconsolidated sands, silts, clays and gravels. The Pleistocene
Age Columbia Formation, which immediately underlies the SCD Site,
is comprised of orange-brown and yellow-brown fine to coarse sand
with silt and gravel lenses. The observed thickness of the
Columbia Formation at the Site ranges from 40 to 75 feet. The
Merchantville Formation is a dark grey to black micaceous sandy
silt or silty/clayey fine sand which underlies the Columbia
Formation at the Site with the exception of the central portion
and north central portion of the Site where it is absent. The
thickness of the Merchantville Formation across the plant
property ranges from 0 to less than 10 feet thick. The Potomac
Formation, which contains laterally discontinuous sand stringers,
underlies the Merchantville Formation and the Columbia Formation
where the Merchantville is absent. The Potomac Formation
observed at the Site consists of red and gray variegated, stiff,
plastic clay with a sand unit encountered at approximately 130
feet below ground surface in the immediate vicinity of the Site.
The uppermost aquifer beneath the Site is the Columbia aquifer.
Depth to ground water in this aquifer as measured in August, 1990
ranged from 30 to 60 feet below ground surface. This aquifer is
unconfined, and the general direction of ground water flow is to
the.north-northwest, north, and north-northeast toward the
unnamed tributary to the Red Lion Creek, and toward Red Lion
Creek. The Columbia aquifer is not known to be used as a current
source for drinking water at the Site in close proximity to the
Site. The uppermost water-bearing sand within the Potomac
Formation is located approximately 130 feet below ground surface
in the Site vicinity and is referred to as the "uppermost Potomac
aquifer" in the RI reports. The ground water flow direction in
the uppermost Potomac aquifer at the Site is generally in a
southeast direction. The Potomac aquifer is used as a drinking
water source. The 60 to 70 feet combined thicknesses of the
Merchantville Formation and clays of the Potomac Formation behave
as an aquitard separating the Columbia aquifer and the uppermost
Potomac aquifer.
The ground water investigation portion of the RI did not require
or include any field investigative techniques which would aid in
identifying the occurrence and extent of Dense Non Aqueous Phase
Liquids ("DNAPLs") in the subsurface soils and aquifer. In
accordance with a Consent Order with DNREC, Standard Chlorine
conducts quarterly ground water monitoring. The quarterly
monitoring reports indicated that at least six wells have
detected "free organics in well." EPA believes that the
description of free organics most likely reflects DNAPLs obtained
during sampling at the respective wells.
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DNAPLs are hydrocarbon, liquids (organic compounds) such as
chlorinated solvents, which are heavier (denser) than water and
immiscible with water (do not mix well with water). Gravity
causes DNAPLs to migrate downward and infiltrate the subsurface
soils and ground water table until the DNAPLs reach an
impermeable layer. As DNAPLs move through the subsurface, some
will dissolve into the ground water and most will sorb to or be
trapped into the granular pore spaces in the soils as residual
DNAPLs. When DNAPLs are present in large volume, some will pool
as a separate distinct liquid on an impermeable layer. Since
residual DNAPLs are trapped between soil grains, they are usually
immobile and can be difficult to remove from the subsurface.
DNAPLs which are present as a pool or lens are usually mobile and
will move along the gradient'at the top of an impermeable
subsurface layer.
Standard Chlorine attempted to define the area of probable DNAPL
occurrence by comparing the concentration of total chlorinated
benzene compounds with the effective solubility of those
compounds. Figure 9 shows the approximate extent of probable
DNAPL contamination based on these calculations. Product, or
.known DNAPL, was identified in several wells during Standard
Chlorine's quarterly ground water sampling.
A supplemental assessment was conducted by Standard Chlorine to
address potential soil and ground water quality impacts resulting
from historical leaks in the SCD effluent pipeline. Samples were
collected from the monitoring wells adjacent to the effluent
pipeline (See Figure 4) in November 1991. Samples taken from
monitoring well #16 revealed concentrations of chlorinated
benzene compounds, above the Maximum Contaminant Levels ("MCLs").
MCLs are referred to as drinking water standards and are
enforceable standards for public drinking water supplies
promulgated under the Safe Drinking Water Act, 42 U.S.C. §§ 300f-
300j.
4.0 SCOPE AMD ROLE OF REMEDIAL ACTION
As part of the RI/FS, a risk assessment was performed by Standard
Chlorine to evaluate the actual and potential threats that the
contamination at the Site poses to human health and to the
environment. For a discussion of the results of the risk
assessment, see Section 5.0 of the ROD which is titled "Summary
of Site Risks."
Once EPA determines from a risk assessment that remedial action
is necessary at a site, EPA characterizes waste on-site as either
a principal threat waste or a low level threat waste. The
concepts of principal threat wastes and low-level threat wastes
as developed by EPA in the National Oil and Hazardous Substances
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Pollution Contingency Plan ("NCP") are applied on a site-specific
basis when characterizing source material. Source material is
defined as material that includes or contains hazardous
substances, pollutants, or contaminants which acts as a reservoir
for migration of contamination to ground water, to surface water,
to air, or which acts as a source for direct exposure. Source
materials are considered to be principal threat wastes when they
contain high concentrations of toxic compounds (e.g., several
orders of magnitude above levels that allow for unrestricted use
and unlimited exposure) or are highly mobile and cannot be
reliably contained.
The principal threat wastes associated with the SCD Site are the
surface soils along the 1981 and 1986 spill pathways, the
material in the soil piles and the sedimentation basin, some
sediments in the unnamed tributary to the Red Lion Creek, soils
adjacent to Catch Basin #1 (CB#1), and the DNAPL contamination in
the subsurface.
Section-300.430 (a) (1) (ill) of the NCP, 40 C.F.R.
§ 300.430 (a) (1.) (iii) , states that "EPA expects to use treatment
to address the principal threats posed by a site, wherever
practicable, " that "EPA expects to use engineering controls, such
as containment, for waste that poses a relatively low, long-term
threat or where treatment is impracticable," that "EPA expects to
use institutional controls... to supplement engineering controls
as appropriate...," and that institutional controls "shall not
substitute for active response measures... as the sole remedy
unless such active measures are determined not to be
practicable..."
EPA's decision for this Site consists of two components, an
interim action and a final action. The interim action component
will address the ground water and DNAPLs. It will also attempt
to minimize the continued release of contaminants into the
adjacent wetlands, the unnamed tributary to Red Lion Creek, and
to Red Lion Creek itself. The final action component of this ROD
will address the contaminated soils and sediments associated with
the 1981 and 1986 releases.
4.1 Interim Action - Ground Water
EPA will require that the interim action at the SCD Site be
implemented, while additional information is collected and
evaluated during the implementation of the interim remedy to
evaluate the technical practicability of ground water restoration
to federal and state drinking water quality criteria.. As an
interim action, EPA will require that the exposure of people and
the area's ecosystem to contaminated ground water be prevented,
and to the extent practicable, further contaminant migration be
prevented. EPA will also require the removal of DNAPL pools if
identified during Remedial Design.
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The remedial objectives for the interim action component of this
ROD are the following:
I. Prevent exposure to the contaminated ground water.
2. Prevent further migration of the contaminated ground
water.
3. Prevent further degradation of the environment caused
by the discharge of contaminated ground water to the
unnamed tributary to Red Lion Creek and Red Lion Creek
and to the wetlands along the unnamed tributary to Red
Lion Creek.
4. Remove any pools of DNAPL which may act as a continuing
source of ground water contamination, if shown to exist
following additional investigation.
As part- of the interim action, additional data will be collected
to determine the extent of DNAPL and ground water contamination.
The review of the data and of this remedy will be ongoing as EPA,
in consultation with DNREC, continues to develop final remedial
alternatives for the ground water, and DNAPL contamination.
Following implementation of the Interim Action, EPA will make a .
final decision on the ground water remedy which will be
documented in a future ROD.
4.2 Final Action - Soils/Sediments
The remedial alternatives for this final action component of the
ROD address the surface and subsurface soils along the pathways
of the 1981 and 1986 releases, the sediments in the unnamed
tributary to Red Lion Creek, the soil piles, the sedimentation
basin, and the soils adjacent to CB#1. The remedial objectives
for these soils and .sediments are the following:.
1. Remediate soils and sediments to levels that are
protective of human health and the environment;
2. Minimize infiltration, run-on, and run-off of
precipitation to areas containing subsurface
contaminated soils and sediments;
3. Monitor and maintain the integrity of Catch Basin #1 to
ensure that it does not serve as a continuing source of
contamination to subsurface soils and ground water;
4. Reduce toxicity of sediments to aquatic organisms;
5. Reduce bioaccumulation of contaminants.
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Only the subsurface soils that can be excavated around CB#l
without damaging the integrity of the structure will be
remediated. Integrity testing of CB#1, such as a hydrostatic
test, will be required to ensure that there are no future
releases.
It should be noted that the SCD facility is an operating plant
which continues to produce chlorinated benzene compounds. The
remedy identified in this ROD does not cover any potential risk
posed to the Site by the day-to-day operations of the
manufacturing facility. EPA notes that the remedy described in
this ROD addresses the human health and environmental effects of
the 1981 and 1986 chlorinated benzene spills and the releases
from Catch Basin #1 at the plant. EPA will require that SCD
conduct additional sampling and analysis of areas ("hot spots")
that may contain contaminated soils. Hot spots will be selected
based on other releases; past and present operations; and
storage/handling practices of solid and hazardous waste. The
results-of the "Hot Spot" analysis will be used to determine if
additional remediation measures are required under CERCLA
authorities. Environmental effects of day-to-day operations and
potential releases beyond the 1981 and 1986 spills are regulated
by various federal laws and regulations (e.g., including but not
limited to the Resource Conservation and Recovery .Act, as
amended, 42 U.S.C. §§ 260.1 et sea.) as well as those of the
State of Delaware (e.g., including but not limited to the
Hazardous Substance Clean-up Act, 7 Del. C. Chapter. 91) and are
therefore not the subject of this ROD. EPA may require
additional work and this ROD may be amended if the results of the
"Hot Spot" sampling identify contamination above the clean-up
criteria or the soils meet the definition of a characteristic
hazardous waste.
Although this is the final component of the remedy for soils and
sediments planned for this Site, changes in conditions may lead
to further response actions.' Other possible response actions may
include removal of sediments in Red Lion Creek or the remediation
of other areas of the Site. Further actions would be based on,
among other things, analytical results.of samples collected from
an investigation being conducted east of Route 9, "Hot Spot"
analysis, data collected as part of an ecological monitoring
plan, or other Site-related investigations.
5.0 SUMMARY OF SITE RISKS
A Baseline Risk Assessment ("BLRA") was prepared as part of the
RI/FS to evaluate the potential human health impacts that may
result from exposure to Site contaminants if no remediation is
conducted. To determine whether there is an actual or a
potential impact at the Site, a complete exposure pathway must be
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established. A complete exposure pathway consists of the
following components:
1. A source or mechanism-for contaminants to be released
to the environment;
2. A medium through which contaminants may be transported
such as water, soil, sediment, or. air;
3. A point of actual or potential exposure or contact for
humans or environmental receptors;
4. A route or mechanism such as ingestion, inhalation, or
dermal contact for exposure at the contact point.
The maximally exposed or most sensitive receptor was selected for
each medium (e.g., soil, ground water) on the assumption that
future use of the Site would be restricted to
commercial/industrial use. The receptors evaluated included
current and future worker; current and future visitor; and
hunter/fisherman.
An ecological investigation was conducted as part of the RI/FS
which focused on the delineation of wetlands, fish sample
collection and analysis, and an overall ecological risk
assessment. The ecological risk assessment focused on
identifying potential adverse effects of the Site.contaminants of
concern on the flora and fauna (i.e., plants and animals) in the
area.
The BLRA assessed the risks associated with the Site to people
and can be found in Volume 1, Section 6 of the Remedial
Investigation Report, which is part of the Administrative Record
for the Site. The Ecological Assessment assessed risks to plants
and animals associated with the Site and can be found in Volume
1, Section 5 of the Remedial Investigation,Report. EPA has
determined that actual or threatened releases of hazardous
substances from this Site, if not addressed by implementing the
response action selected in this ROD., may present an imminent and
substantial endangerment to human health and the environment.
5.1 Human Health Risk Assessment
The BLRA is divided into two categories of impacts: carcinogenic
and non-carcinogenic or systemic. Many contaminants cause both
types of impacts. Remedial action is generally warranted when
the calculated carcinogenic risk level exceeds 1 X 10"4 (meaning
that one additional person out of 10,000 is at risk of developing
cancer caused by a lifetime of.exposure to. contaminants at the
Site) under current or future conditions for any of the evaluated
exposure scenarios. Remedial action is also generally warranted
11
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if the calculated non-carcinogenic Hazard Index1 exceeds 1.0
under current or future conditions for any of the evaluated
exposure scenarios.
Since the Site is. an operating industrial facility and is
surrounded by other large industrial facilities, the land use
that was assumed was industrial. The risks were calculated by
first determining all the various ways in which humans come in
contact with contaminants at the Site currently or potentially in
the future. The receptors evaluated included current and future
worker; current and future visitor; and hunter/fisherman. Table
4 presents the exposure scenarios and potential exposure
pathways.
The second step in the risk calculations involves determining
which contaminants are contributing significantly to the total
risk.and should be labeled as contaminants of concern. Using
procedures outlined in EPA's "Risk Assessment Guidance for
Superfund" (EPA/540/1-89/002), a list of contaminants of concern
was developed for each media in each area related to an exposure
pathway.
Another part of a risk calculation is the cancer potency factors
(CPFs)2 or reference doses (RfDs)3. Used both in the screening
1The potential for health effects resulting from exposure to
non-carcinogenic compounds is estimated by comparing an estimated
dose to an acceptable level, or reference dose. If this ratio
exceeds 1.0, there is a potential health risk associated with
exposure to that chemical. The ratios can be added for exposures
to multiple contaminants. The sum, known as the Hazard Index, is
not a mathematical prediction of the severity of toxic effects,
but rather a numerical indicator of the .transition from
acceptable to unacceptable levels.
2CPFs, also known as slope factors, have been developed by
EPA's Carcinogenic Assessment Group for estimating excess
lifetime cancer risks associated with exposure to potentially
carcinogenic chemicals. CPFs, which are expressed in units of
(mg/kg/day)-1, are derived from the results of human
epidemiological studies or chronic animal bioassays to which
animal-to-human extrapolation and uncertainty factors have been
applied.
3An RfD is a toxicity value used to estimate the potential
for adverse non-carcinogenic health effects. The model to
determine RfDs from the dose-response assessment assumes that
there is a concentration for non-carcinogens below which there is
little potential for adverse health effects over a lifetime of
exposure. The RfD is designed to represent this threshold level.
The RfD is calculated from the highest chronic exposure level
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steps and the actual risk calculations, CPFs and RfDs are
estimates of the degree of a contaminant's toxicity.
Actual or potential risks are calculated by multiplying each
intake factor by the proper CPF for carcinogens, or by dividing
each intake factor by the proper RfD for non-carcinogens. Note
that various exposure parameters are involved in the calculation
of intake factors, including the concentration, of each
contaminant of concern for each exposure pathway.4
The contaminants contributing to the risk at the Site are
referred to as contaminants of concern ("COCs") and consist of:
benzene*
chlorobenzene
1, 2-dichlorobenzene
1,3-dichlorobenzene
1, 4 -dichlorobehzene*
hexachlorobenzene*
nitrobenzene
pentachlorobenzene
1,2,3,4-tetrachlorobenzene
1,2,4,5-tetrachlorobenzene
toluene
1,2,3 -trichlorobenzene
1,2,4 -1richlorobenzene
1,3,5 -trichlorobenzene
that did not cause adverse effects (the no-observed-adverse-
effect level ("NOAEL")) in animals. The NOAEL is divided by a
factor to account for any uncertainty such as using data on
animals to predict effects on humans and an allowance for
sensitive individuals. Uncertainty factors range from 1 to
10,000 based on the confidence level associated with the data.
The resulting RfD (mg/kg-body weight/day) is used to quantify the
risk.
4The concentration value used is the 95% upper confidence
limit (UCL) for the arithmetic mean of .the levels of each
contaminant found in the samples taken from the appropriate media
in each area. This particular concentration value is a
statistical estimate of the highest average concentration
predicted to occur in 95 out of 100 sets of samples. The use of
the 95% UCL produces an estimate of risks for the "Reasonable
Maximum Exposure" ("RME") scenario. The 95% UCL is used to
account for the fact that the actual number of samples is
relatively small to accurately predict the average. This method
of calculating risks is designed to provide a conservative
estimate and makes the underestimation of actual risks highly
unlikely.
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Benzene is a known human carcinogen and the other starred items
(* ) are contaminants which are suspected human carcinogens.
1,4-dichlorobenzene poses the greatest carcinogenic risk at the
Site, primarily due to the high levels detected in the soil.
In addition to the COCs listed above, metachloronitrobenzene,
ethylbenzene and PCBs were identified in the BLRA as COCs.
However, because of the lack of toxicity criteria on
metachloronitrobenzene, the risks associated with exposure to
this particular contaminant were not evaluated quantitatively in
the BLRA. With regard to ethylbenzene and PCBs which were
detected exclusively in sediment, the associated systemic and
carcinogenic risks to hunters and fishermen were negligible.. .
Carcinogenic and chronic non-carcinogenic health.effects were
evaluated for ground water and soil ingestion, dermal contact
with soil, fish ingestion, dermal exposure to surface water and
sediments, and inhalation of airborne soil particles. Table 5
summarizes the carcinogenic risk and Table 6 summarizes the non-
carcinogenic risk associated with the Site.
Receptors for which risks are unacceptable include the
current/future worker, the future visitor, and the
hunter/fisherman. Under the current worker scenario, 1,4-
dichlorobenzene poses the greatest carcinogenic risk at the Site,
primarily due to the high levels detected in the soil. Exposure
to ground water from the Columbia aquifer accounted for most of
the future risk at the Site. Currently, ground water from the
Columbia aquifer in the vicinity of the Site is not used as a
drinking water supply source and there is no current evidence
that the contamination has entered the Potomac Formation aquifer.
5.2 Ecological Risk Assessment
The ecological investigation focused on the delineation of
wetlands surrounding the unnamed tributary to Red Lion Creek,
fish sample collection and analysis from two locations in Red
Lion. Creek and an overall ecological risk assessment. The
ecological risk assessment focused on identifying potential
adverse effects of the Site contaminants of concern on the flora
and fauna (i.e., plants and animals) in the area.
Figure 10 delineates the extent of the wetlands in the unnamed
tributary to Red Lion Creek. Generally, the wetlands were
defined by the topography of the area.
The ecological assessment characterized the plant and animal
species in the area impacted by the previous releases of
contaminants. No endangered or threatened species were
identified. Animals can be exposed to these contaminants through
several routes including ingestion of surface water, fish, and
14
AR308682
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vegetation, and/or contact with surface water, soil, and
sediment.
The great blue heron, the white-tailed deer, and the meadow vole
were selected as representative species from the area for the
terrestrial portion of the ecological risk assessment. Toxicity
tests were performed using earthworm, lettuce seeds and Hyallela
azteca (a type of waterbug) as surrogates for soil fauna, soil
flora, and aquatic life, respectively. The results of the
assessment indicated a potential for adverse effects to occur to
the meadow vole, the earthworm (soil fauna) , aquatic life of Red
Lion Creek, and terrestrial vegetation (soil flora). The results
of the ecological assessment can be found in Volume 1, Section 5
of the Remedial Investigation Report.
Fish were collected from both upstream and downstream locations
on three separate occasions in 1990 and 1991. The concentration
of chlorinated benzene in the fish caught downstream (near the
Rt. 9 bridge) ranged from 0.01 to 1.4 mg/kg. Analytical results
for fish samples collected at the upstream sampling location near
Route 13 indicate no detectable levels of chlorinated benzene.
Table 7 presents the summary of the analytical results of the
fish sampling in the fall of 1990 and spring of 1991.
Calculations using this data indicate that the presence of
chlorobenzene in fish tissue does not pose a threat to the great
blue heron which was used as the representative species for this
part of the ecological assessment.
In March of 1990, Standard Chlorine, and EPA were unable to
collect the designated type and quantity of fish. EPA conducted
an independent analysis of the carp fillets collected from this
sampling event. It was later determined that carp was not an
appropriate species for evaluating human and ecological exposure,
but was worthwhile as an indicator for defining decreasing
chlorobenzene levels in the Red Lion Creek system. Table 8
presents the summary of the analytical results of the fish
sampling in March 1990.
5.3 Summary of Areas Requiring Remediation
5.3.1 Interim Action
EPA has determined that the Columbia aquifer ground water is
contaminated and that contamination in the aquifer must be
contained as an interim measure while additional information is
collected and evaluated during the implementation of the interim
remedy to determine the. technical practicability of Columbia
aquifer ground water restoration to federal and state drinking
water standards. Currently this ground water is not used as a
potable source. Ground water flows toward the Red Lion Creek and
serves as a continuing source of contamination to the creek.
15 . '
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Pools of DNAPL, if they exist, could act as a continuing source
of ground water contamination and will be collected and removed
as part of this interim action. The nature and extent of ground
water contamination in the vicinity of the effluent pipeline and
the adjacent Air Products and Chemicals Inc. ("Air Products")
property will also be investigated and remedial alternatives will
be evaluated.
5.3.2 Final Action
Based on the potential impacts to human health and the
environment, EPA has determined that the following areas of the
Site warrant remediation:
Railroad Track Area
Western Drainage Gully
Eastern Drainage Ditch
Soil Piles
Sedimentation Basin
. Sediments in the Unnamed Tributary to Red Lion Creek, and
Catch Basin #1.
5.3.3 Clean-up Criteria
CERCLA requires that on-site remedial actions must attain federal
and more stringent State applicable or relevant and appropriate
requirements ("ARARs") of environmental laws and regulations.
There are no chemical-specific clean-up level ARARs for soils or
sediments. Therefore, the results of the human health and
ecological risk assessments are used to establish acceptable
exposure levels for soils and sediments.
Using the findings of the human-health risk assessment, the
clean-up criteria.for on-site soils and,sediments (soils and
sediments inside the existing fence of the SCO plant and noted as
the SCD facility boundary on Figure 2) based on risk to a future
worker is 625 mg/kg for total COCs with a ceiling concentration
of 450 mg/kg for 1,4-dichlorobenzene. (Hereafter, the on-site
clean-up criterion will be referred to as 625/450 mg/kg of total
COCs.) On-site soils must also pass Toxicity Characteristic
Leaching Procedure ("TCLP") analysis.
The RI suggests that these clean-up criteria represent a
carcinogenic risk of 1 X 10"5 to future workers. SCD calculated
16
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these levels using two conservative assumptions. SCD assumed
first, that the worker would be exposed for 24 hours a day as
opposed to a typical 8 hours a day scenario. Secondly, SCD
assumed that contaminants would be absorbed through the skin.
For most chemicals, there are many uncertainties associated with
calculating a risk related to dermal (skin) contact with
contaminated soil. Consequently, EPA does not usually recommend
quantifying risks related to skin exposure. By incorporating
more realistic assumptions into the calculations, i.e., an 8-hour
work day and elimination of skin contact as an exposure route,
EPA has determined that the actual residual cancer risk to a
future worker at the Site following remediation (at the proposed
clean-up levels) is approximately 1 X 1CT6.
The clean-up criteria for off-site soils and sediments (soils and
sediments outside the existing fence of the SCD' plant and noted
as the SCD facility boundary on Figure 2) is based on the risk to
the ecological receptors (flora and fauna). Based on toxicity
testing for the germination of lettuce seed and survival of the
earthworm, the clean-up criterion is 33 mg/kg for total COCs for
off-site soils and sediments. Off-site soils must also pass TCLP
analysis.
Restoration of ground water to drinking water standards where .
DNAPLs are present may not be technically practicable. Interim
measures to contain the ground water, and recover DNAPL pools, .if
identified during Remedial Design, will be initiated while
further investigation is conducted to determine the technical
practicability of meeting ARAR clean-up criteria in the ground
water. EPA will require that the interim action be protective of
human health and the environment by preventing exposure to ground
water. Each of the remedial alternatives discussed in the next
section has a component for preventing exposure to ground water.
6.0 DESCRIPTION OF ALTERNATIVES
The Feasibility Study ("FS") and the Feasibility Study Addendum
contain all the remedial alternatives considered by SCD for the
clean-up of the soils, sediments, and ground water at the SCD
Site. Five alternatives were analyzed in detail in the FS and
the FS Addendum which are contained in the Administrative Record.
In addition, EPA evaluated an additional alternative which is a
combination of Alternatives 5A and 5B and is called Alternative
6. These alternatives, which differ in the way they deal with
soil and.ground water contamination at the Site, include:
1) No Action
2) Containment
3) Closure and In Situ Bioremediation of Wetland Sediments
4A) Thermal Treatment & In Situ Bioremediation of Wetland
i
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Sediments
4B) Thermal Treatment
5A) Ex Situ Bioremediation
5B) In Situ Biological Treatment of Wetland Sediments to
supplement Alternatives 3 and 4A
6} In Situ/Ex Situ Bioremediation
Alternatives 3 and 4A, as proposed in the Feasibility Study do
not address remediation of the wetland sediments. Alternative 5B
in the Feasibility Study Addendum is a description of the in situ
bioremediation treatment for the wetland areas to supplement
Alternatives 3 and 4A, as described in the FS. Since Alternative
5B is not a site-wide alternative, but a supplement to
Alternatives 3 and 4A, it will be discussed and evaluated as a
component of Alternatives 3 and 4A.
6.1 Common Elements
Each of.. the alternatives evaluated in detail, except for
Alternative 1 - (No Action) , contain certain common components
which are discussed below:
Ground water - The interim action alternatives include
maintenance and operation of the existing ground water extraction
wells. Recovered water will be treated in the existing air
stripper and then discharged under SCO's National Pollutant
Discharge Elimination System ("NPDES") permit # DE0020001
requirements. The NPDES permit program establishes the
requirements for the direct discharge of pollutants to waters of
the United States, including the discharge of pollutants to
surface waters. Air emissions from the air stripping unit will
go to the existing SCD plant boilers. Since SCO is an operating
facility, and is subject to process changes, the treatment
technology for ground water is subject to change, based on
effectiveness and/or NPDES requirements. Any changes to the
ground water treatment process will comply with applicable
federal and state NPDES regulations. Controls for air emissions
generated from treatment of ground water will also be required.
Low volume product recovery wells will be installed to attempt to
recover DNAPLs. Four (4) product recovery wells were identified
in the FS to develop cost estimates. The actual number and
location of recovery wells will be determined as part of the
Remedial Design. The recovered DNAPL will be stored on-site
temporarily, and ultimately disposed of off-site, in accordance
with applicable federal and state regulations promulgated
pursuant to RCRA.
In the event that SCD should reduce or cease production
operations at the Site, EPA will require that the existing waste
water treatment plant be modified or a new one be constructed to
manage contaminated ground water. Treatment of air emissions in
accordance with applicable or relevant and appropriate federal
18
4R30868.6
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and state requirements would also be mandated.
Soils/Sediments - Each of the alternatives evaluated in the FS
included the use of the sedimentation basin for consolidation of
soils and sediments. Under this scenario, the sedimentation
basin would have to be retrofitted to satisfy the RCRA
requirements for landfills and the treated soils and sediments
would have to satisfy RCRA Land Disposal Requirements ("LDRs"),
promulgated at 40 C.F.R. Part 268 prior to being placed in the
basin. Because the RCRA LDRs would be triggered if the
sedimentation basin were used for consolidation of soils and
sediments, Alternatives 4A, 4B, and 5A have been revised to
mandate closure of the sedimentation basin.
There is a possibility that the on-site clean-up criterion of 450
mg/kg for 1,4-dichlorobenzene could fail TCLP analysis and in
turn meet the definition of a characteristic hazardous waste
under federal or state RCRA regulations. Under each of the
alternatives, EPA will therefore require that all treated soils
pass TCLP analysis prior to being used as backfill at the Site.
Surface Water - Surface water in the unnamed tributary to Red
Lion Creek and Red Lion Creek will be addressed through
remediation of the soils, sediments, and ground water. Surface
water in the sedimentation basin will be pumped and treated in
SCO's, waste water treatment plant and air stripper and discharged
under an NPDES permit.
Institutional Controls - Institutional controls for the Site
will include use, access, and deed restrictions intended to limit
future land and ground water use and security fences to limit
access. DNREC will also implement a ground water management zone
("GWMZ") which will prevent the installation of drinking water
wells in the area impacted by the releases.
Monitoring - Site monitoring will include monitoring of the
ground water in both.the Columbia and Potomac aquifers. A
monitoring plan will be prepared during the Remedial Design phase
which will describe in detail the Site monitoring activities.
The ground water monitoring activity will involve the
installation of additional on-site and off-site monitoring wells.
Ecological monitoring will be conducted annually with the first
round prior to the start of remedial action to establish a data
baseline and then annually thereafter for a period of at least
five years. . The ecological monitoring activities of the surface
water systems present at the Site (the wetlands, the unnamed
tributary to Red Lion Creek, and Red.Lion Creek) will include
chemical analysis of surface water, sediments and fish and
muskrat tissue, and sediment bioassays.
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6.2 Description of Alternatives
The following is a brief description of the alternatives which
were evaluated for the Site. A summary of each of the
alternatives is included in Table 9.
Alternative 1 - No Action
Estimated Capital Costs: $0
Estimated Annual O&M Costs: $0
Estimated Present-Worth Costs: $0
The NCP requires that EPA consider a no action alternative for
every site to establish a baseline for comparison to alternatives
that do require action. Under this alternative, the operation of
the existing ground water treatment and recovery system would be
discontinued. The existing contaminated soils, soil piles, and
sedimentation basin would remain in place. No further activities
for upgrading or closure of the soil piles or sedimentation basin
would occur.
Estimated Capital Costs: $2.24 million
Estimated Annual O&M Costs: $80,000
Estimated Present-Worth Costs: $3.47 million
Ground Water - In addition to the components discussed above
under common elements, additional extraction wells would be
installed to reduce the flow of ground water to the Red Lion
Creek. Five additional extraction wells were used in the FS to
develop cost estimates.
Soils.- Soils along the western drainage gully (to a depth of 7
feet) that exceed the "off-site" clean-up criterion of 33 mg/kg
of total COCs and the soils along the eastern drainage ditch (to
a depth of 3 feet) and Catch Basin #1 .(to a depth of 15 feet)
that exceed the "on-site" clean-up criterion of 625/450 mg/kg of
total COCs would be excavated and consolidated in the existing
sedimentation basin, followed by in situ
stabilization/solidification. The soil pile material would be
consolidated in the sedimentation basin as well. The
sedimentation basin would then be capped with a multi-layer cap.
The excavated and backfilled areas where elevated levels of
contaminants remain in the subsurface would be capped with either
asphalt or a Flexible Membrane Liner ("FML"). A low permeability
asphalt cap would be applied in the area of the railroad tracks
and Catch Basin to reduce infiltration (See Figure 11) .
20
flR308688
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Sediments - The existing silt fences across the mouth of the
unnamed tributary wetland area would be reconstructed and
additional silt fences would be installed. New silt fences would
be installed in the unnamed tributary to Red Lion Creek to
prevent contaminated sediment migration to the Red Lion Creek.'
Figure 12 identifies the location of the silt fence. The
sediments in the sedimentation basin would be stabilized to
reduce free moisture and improve bearing strength to support the
final cap. The sedimentation basin would be capped with a multi-
layer cap.
Alternative 3 - Cloaure and In Situ Bioremediation of Wetland
Sediments
Estimated Capital Costs: $5.2 million.
Estimated Annual O&M Costs: $101,000
Estimated Present-Worth Costs: $.6.8 million
Ground Water - In addition to the components discussed above
under common elements, a ground water containment system would be
installed along the shorelines of the unnamed tributary and the
Red Lion Creek to capture ground water before it enters the Red
Lion Creek. A deep interceptor trench was described in the FS to
evaluate the containment approach as well as to develop costs.
Other physical barriers that could be used at the. Site include . '
sheet pilings or a slurry wall. The exact length, location, (see
Figure 13) and type of physical barrier to contain contaminated
ground water and DNAPLs would be based on information gathered
during Remedial Design ("RD") activities. Soils excavated from
the trench could be contaminated and would be analyzed to
determine contaminant concentration levels. If the excavated
trench soils exceed 33 mg/kg of total COCs, these soils would
require treatment before disposal.
Soils - The same as Alternative 2 for surface and subsurface
soils; except the sedimentation basin would be retrofitted with a
new liner and leachate collectipn system (See Figure 14). During
the public comment period and in follow-up meetings and
discussions with EPA and DNREC, SCD provided clarification on the
use of the sedimentation basin as a Corrective Action Management
Unit (CAMU)- SCD maintained that the sedimentation basin could
be retrofitted to comply with the RCRA CAMU provisions and in
turn comply with ARARs. A more detailed discussion of CAMU and
Alternative 3 is provided in Section 7.2, the Responsiveness
Summary, and the Administrative Record.
Sediments - Contaminated sediments along the unnamed tributary to
Red Lion Creek and Red Lion Creek itself that exceed the off-site
(sediments outside the existing fence of the SCD plant and noted
as the SCD Facility Boundary on Figure 2) clean-up criterion of
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33 mg/kg of total COCs which are accessible from the shorelines
using conventional equipment would be excavated and consolidated
into the retrofitted sedimentation basin, and treated by
stabilization/solidification. The excavated sediments and the
existing sediments in the sedimencation basin would be stabilized
in a mechanical mixing plant prior to being placed back in the
retrofitted basin. The FS states that stabilization would reduce
the contaminant mobility by solidification. Those sediments that
exceed the clean-up criterion of 33 mg/kg of total COCs and are
difficult to access in the wetland area of the unnamed tributary
to Red Lion Creek and Red Lion Creek would undergo in situ
biological treatment. In situ bioremediation technology entails
treating the contaminated soils in place, eliminating the need
for soil excavation. The technology usually involves enhancing
natural biodegradation processes by adding nutrients, oxygen, and
in some cases, microorganisms. See Figure 12 for the approximate
delineation of the area to be remediated in and along the
wetlands.
Alternative
Estimated Capital Costs: $10.1 million
Estimated Annual O&M Costs: $106,700
Estimated Present-Worth Costs: $11.7 million
This alternative includes the treatment of soils and sediments
using thermal desorption technology. Thermal desorption is the
heat -induced desorption, volatilization, and capture of volatile
and semi-volatile organic compounds from contaminated solids.
The contaminants would be removed from the soil, collected, and
concentrated in the vapor treatment system. It could be possible
to return the concentrated contaminants to the SCD facility
processing units for recycling. Otherwise they would be shipped
to a RCRA permitted treatment -or disposal facility.
Ground Water - same as Alternative 3
Soils - Soils along the western drainage gully (to a depth of 7
feet) that exceed the off -site clean-up criterion of 33 mg/kg of
total COCs and the soils along the eastern drainage ditch (to a
depth of 3 feet) and Catch Basin #1 (to a depth of 15 feet) that
exceed the on-site clean-up criteria of 625/450 mg/kg of total
COCs would be excavated. These soils along with the soils in the
soil piles and the sedimentation basin, would undergo thermal
desorption. Treated soils would be used as backfill where the
treatment is successful in remediating the soils to the clean-up
criteria or performance standards. Although the FS states that
soils not remediated to the clean-up criteria would be
stabilized/solidified, if necessary, and consolidated into the
22
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retrofitted sedimentation basin, EPA will require that all soils
be treated to the clean-up criteria. The sedimentation basin
would be closed rather than retrofitted as delineated in
Alternative 3. In excavated areas, where high concentration
subsurface soils remain, a Flexible Membrane Liner or asphalt
would be used to cap the backfilled excavations. A low
permeability asphalt cap would be applied in the area of the
railroad track and Catch Basin #1 to reduce infiltration (See
Figure 15).
Sediments - Contaminated sediments along the unnamed tributary
to Red Lion Creek and Red Lion Creek that exceed the off-site
(sediments outside the existing fence of the SCD plant and noted
as the SCD facility boundary.of Figure 2} clean-up criterion of
33 mg/kg of total COCs which are accessible from the shorelines
using conventional equipment would be excavated, thermally
treated, and used as backfill. Those sediments which exceed the
clean-up criterion-of 33 mg/kg of total COCs and are difficult to
access in the wetland area of the unnamed tributary and Red Lion
Creek would undergo in situ biological treatment as described
under Alternative 3. See Figure 12 for the approximate
delineation of the wetland areas to be remediated.
Alternative 4 B - Thermal Treatment
Estimated.Capital Costs: $15.5 million
Estimated Annual O&M Costs: $100,000
Estimated Present-Worth Costs: $17.06 million
Same as alternative 4A, except all soils and sediments, including
those areas which are difficult to access, that exceed the clean-
up criterion of 33 mg/kg of total COCs along the unnamed
tributary to Red Lion Creek and the Red Lion Creek would be
excavated and thermally treated (See Figures 12 and 15).
Alternative 5A - Ex Situ Biological Treatment
Estimated Capital Costs: $9 to 11.3 million
Estimated Annual O&M Costs: $100,000
Estimated Present-Worth Costs: $10.6-12.9 million
This alternative, as discussed in the FS Addendum, involves the
ex situ biological treatment of contaminated soils and sediments.
This treatment may take place under aerobic (the presence of
oxygen) or anaerobic (absence of oxygen) conditions. The results
of the treatability study conducted as part of the RI/FS to
determine the viability of bioremediation technology for soils
and sediments at the SCD Site were not definitive. Regardless,
all of the contaminants are volatile and amenable to
23
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biodegradation, which suggests that bioremediation could be
effectively used at this Site. The actual biological treatment
process would be refined after additional studies including
treatability studies and/or pilot scale tests were conducted
during the Remedial Design.
Ground Water - Same as Alternative 3
Soils/Sediments - Soils and sediments would be excavated as
delineated in Alternative 4B, only the treatment technology
employed would be ex situ biological treatment rather than
thermal treatment (See Figures 12 and 15).
Alternative SB - In Situ Biological Treatment
Alternative 5B is not a site-wide alternative, but a supplement
to Alternatives 3 and 4A and is discussed and evaluated as a
component of Alternatives 3 and 4A.
EPA evaluated an additional alternative that is a modification of
the alternatives proposed in the FS which is. described below as
Alternative 6. . ' .
Alternative 6 - Ex Situ/In Situ Bioremediation
Estimated Capital Costs: $4.9 to 10.8 million
Estimated Annual O&M Costs: $90,000
Estimated Present Worth Costs: $6.6 to 12.2 million
This alternative includes the treatment of soils and sediments
using bioremediation technology and is a modification/combination
of Alternatives 5A and 5B as described in the FS Addendum. The
modification would include a combination of both in situ and ex
situ bioremediation. The actual biological treatment process
would be refined after additional studies including treatability
studies and pilot scale tests were conducted during the Remedial
Design.
Ground Water - Same as Alternative 3
Soils/Sediments - Soils along the western drainage gully (to a
depth of 7 feet) that exceed the off-site clean-up criterion of
33 mg/kg of total COCs and the soils along the eastern drainage
ditch (to a depth of 3 feet) and Catch Basin #1 (to a depth of 15
feet) that exceed the on-site clean-up criterion of 625/450 mg/kg
of total COCs would either be excavated and biologically treated
24
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or biologically treated in place. -All treated soils must pass
TCLP before being used as backfill to demonstrate that the'
treated soils no longer meet the definition of a characteristic
hazardous waste. After treatment, the soils adjacent to Catch
Basin #1 would be capped with a low permeability asphalt cap.
The soils along the railroad track area would be biologically
treated in-place. If in situ biological treatment is
unsuccessful in remediating the soils in the area along the
railroad tracks to the on-site clean-up criterion, this area
would be capped with a low permeability asphalt cap. Soils and
sediments outside the existing fence that exceed the off-site
clean-up criterion of 33 mg/kg for total COCs (soils and
sediments outside the existing fence of the SCD plant and noted
as the SCD facility boundary on Figure 2) would also be
remediated with biological treatment. This alternative would
remediate and cap the'same soils and sediments as delineated
under Alternatives 4A and 4B, only the treatment technology
employed would be bioremediation. -The sediments in the
sedimentation basin would be removed from the basin for ex situ
bioremediation.
If bioremediation were successful in remediating excavated
soils/sediments to 33 mg/kg of total COCs, the sedimentation
basin could be dismantled and closed in accordance with RCRA
closure requirements and the ARARs identified on Table 10.
Closure of the sedimentation basin would comply with the RCRA
requirements as set forth in 40 C.F.R. § 264.228 and the Delaware
Regulations Governing Hazardous Waste § 264.228 and would include
testing of the soils underlying the existing liner to ensure that
the soils are not contaminated. Any contaminated soils
underlying the basin that exceed the off-site clean-up criterion
of 33 mg/kg for total COCs would be remediated with biological
treatment. Closure of the area formerly occupied by the
sedimentation basin would entail grading, seeding and stabilizing
with a variety of plants and shrubs. Species would be selected
during the Remedial Design for their value in development of
diversity, density, and abundance of wildlife qualities.
7.0 SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
All of the six remedial alternatives described above were
assessed in accordance with the nine evaluation criteria as set
forth in the NCP, 40 C.F.R. § 300.430(e) (9). These nine
evaluation criteria can be categorized into three groups:
threshold criteria, primary balancing criteria, and modifying
criteria. Below is a -summary of the nine criteria that were
used to evaluate the remedial alternatives for the SCD Site.
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AR30869
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Threshold Criteria
Overall, protection of human health and the environment:
Whether the remedy provides adequate protection of human
health and the environment and how risks posed through each
pathway are eliminated, reduced or controlled through treatment,
engineering controls, or institutional controls.
Compliance with ARARs;
Whether or not a remedy will meet all applicable or
relevant and appropriate requirements ("ARARs") of federal and
state environmental laws and regulations and/or whether there are
grounds for invoking a waiver. Whether or not the remedy
complies with advisories, criteria and/or guidance that may be
relevant.
Primary Balancing Criteria
Long-term effectiveness and permanence;
The ability of the remedy to afford long-term, effective .
and permanent protection to human health and the environment
along with the degree of certainty that the alternative will.
prove successful.
Reduction of toxicity, mobility or volume through
treatment:
The extent to which the alternative will employ treatment
technologies to reduce the toxicity, mobility, or volume of the
contaminants causing the site risks.
'short-term effectiveness;
The time until protection is achieved and the short-term
risk, or impact to the community, on-site workers, and the
environment that may be posed during the construction and
implementation of the alternative.
Implementability:
The technical and administrative feasibility of a remedy,
including the availability of materials and services needed to
implement that remedy.
26
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Cost:
Includes estimated capital, operation and maintenance, and
net present worth costs.
Modifying Criteria
State Acceptance:
Whether the state concurs with, opposes, or has no comment
on the preferred remedial alternative.
Community Acceptance:
Whether the public agrees with the preferred remedial
alternative (this is assessed based on a review of the public
comments received on the Proposed Plan).
Each alternative must first satisfy the threshold criteria as
described above. Next the primary balancing criteria are used to
weigh the tradeoffs or advantages and disadvantages of the
various alternatives. Finally, after public comment has been
obtained, the modifying criteria are considered. A summary of
the relative performance of the alternatives with respect to each
of the nine criteria follows. This summary provides the basis
for determining which alternative provides the "best balance" of
tradeoffs with respect to the nine evaluation criteria.
7.1 Overall Protection of Human Health and the Environment
A primary or threshold requirement of CERCLA is that the selected
remedial action be protective of human health and the
environment. A remedy is protective if it reduces current and
potential risks to acceptable levels within the established risk
range posed by each .pathway at the Site.
Alternative 1 (No Action) would neither eliminate nor reduce to
acceptable levels the threats to human health or the environment
presented by contamination at the Site. It is therefore
unacceptable and will not be discussed in the remainder of this
analysis.
Ground Water
The actions described as necessary for ground water are the same
for Alternatives 3 through 6. Based on historical data of the
existing' pump and treat system, it is uncertain whether the
ground water system proposed in Alternative 2 would be effective
in preventing contaminated ground water from entering Red Lion
Creek. The ground water containment and extraction system
27
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included as a component of Alternatives 3 through 6 is protective
of human health and the environment.
Soils/Sediments/Surface Water
Of the six alternatives evaluated, Alternatives 3 through 6 are
protective of human health and the environment. Alternative 2
does not prevent exposure to contaminated sediments in the
wetland area and therefore is not protective of the environment.
Alternatives 4B, 5A and possibly 6 will, however, result in the
temporary loss of some habitat during remediation. Alternative 2
includes the installation of new silt fences along the unnamed
tributary to Red Lion.Creek to prevent migration of contaminants
into Red Lion Creek. Under Alternative 2, however, some of the
contaminated sediments will be left in place which allow for
continued exposure to ecological systems and is not protective of
the environment. Alternative 2 will be eliminated from further
consideration as a viable alternative since it is not protective
of the environment.
Under Alternatives 3, 4A, 4B, 5A and 6, surface water will be
addressed through remediation of the soils, sediments, and
containment of ground water. Each of the alternatives would
prevent contaminated ground water from migrating into Red Lion
Creek. Under Alternatives 3,4A, 4B, 5A, and 6, surface water
run-off would no longer come in contact with highly contaminated
soils and sediments because the contaminated soils/sediments
would be either remediated to the clean-up criteria, contained, .
and/or capped.
7.2 Compliance with ARARS
This criterion addresses whether a remedy will meet all of the
applicable or relevant and appropriate requirements ("ARARs") of
federal and state environmental laws and regulations, and/or
whether there are grounds for invoking a waiver.
Ground water
In accordance with EPA's Ground Water Protection Guidelines, the
Columbia aquifer is classified as a Class IIB aquifer (i.e., it
has the potential for use as a drinking water source). Both the
federal and state Safe Drinking Water laws set minimum standards
for drinking water called Maximum Contaminant Levels ("MCLs"),
which are applicable under CERCLA. MCLs are not ARARs for
interim action remedies consisting of containment under CERCLA
because additional information is required before EPA can make a
final decision on the ground water remedy. Since the remedy for
ground water is an interim action for containment of ground water
and DNAPLs, all of the alternatives will require that additional
work be conducted to determine not only the extent of DNAPL
28
AR308696
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contamination, but also the technical practicability of restoring
ground water to federal and state drinking water standards and
establishing alternative, protective remedial strategies if
restoration is determined to be technically impracticable.
All of the alternatives will have air emissions from the ground
water treatment systems which will be treated either in the
existing plant boilers, or other appropriate equipment (approved
by EPA in consultation with DNREC) to comply with federal and
state ARARs.
All of the alternatives will discharge treated ground water to
the Delaware River and will comply with the substantive
requirements of the NPDES program and federal and state water
laws.
Any product (i.e., non-aqueous phase liquid) which is recovered
from the low volume product recovery wells will be stored on-site
temporarily, and ultimately disposed of off-site in accordance
with applicable federal and state regulations promulgated
pursuant to RCRA.
Soils/Sediments/Surface Water
The soils and sediments are contaminated due to a release of
commercial chemical products which are listed as hazardous wastes
in 40 C.F.R. § 261.33. Once these soils are excavated, they must
be managed in accordance with federal and state RCRA regulations.
All of the alternatives in the FS proposed placing excavated,
treated and/or untreated soils in the existing sedimentation
basin. RCRA regulations would require that all the excavated
contaminated soil be treated to satisfy Land Disposal Regulations
(40 C.F.R. Part 268) and that the sedimentation basin be designed
and constructed in accordance with RCRA hazardous waste
treatment, storage and .disposal facility regulations if it is to
hold hazardous waste or contaminated soils that must be managed
'as a hazardous waste. . .
The Hazardous and Solid Waste Amendments of 1984 ("HSWA")
prohibit the land disposal of untreated hazardous wastes. HSWA
requires that EPA set "...levels or methods of treatment, if any,
which substantially diminish the toxicity of the waste or
substantially reduce the likelihood of migration of hazardous
constituents from the wastes..." On June 1, 1990, EPA
promulgated land disposal regulations in 40 C.F.R. Part 268 for
various hazardous wastes, including chlorobenzene (U037), 1,2-
dichlorobenzene (U070), 1,3-dichlorobenzene (U071), and 1,4-
dichlorobenzene (U072). These regulations delineated certain
treatment standards and concentration based standards. 40 C.F.R.
§ 268.43 identifies the concentration based standards (effective
December 19, 1994) of 6.0 mg/kg for chlorobenzene, 1,2-, 1,3-,
. '29
AR308697
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and 1,4-dichlorobenzene and "reflect the performance of well-
designed and well operated incineration systems."
An interpretation of the federal RCRA regulations, referred to as
the "Contained-in Policy" (OSW Memorandum dated November 13,
1986) , is described on page 986 of the Federal Register, Volume
57, No. 6, January 9, 1992. This interpretation states that
contaminated media such as soil, which contains hazardous waste
must be managed as if it were a hazardous waste, subject to all
treatment, storage and disposal requirements under RCRA Subtitle
C, until it no longer contains hazardous waste. Under the
"Contained-in Policy," contaminated soil is considered to no
longer contain listed hazardous waste when hazardous constituents
of the listed waste are at or below health-based levels. The
clean-up criteria for the SCD Site, as discussed previously in
.this ROD., were developed after a thorough review of both the
site-specific human health risk assessment and the site-specific
ecological risk assessment which were prepared during the RI/FS.
As such-, the clean-up criteria or performance standards are
health-based levels which, when met, will minimize the threat to
human health and the environment.
The land disposal treatment standards are technology based and
are more stringent than the Superfund clean-up criteria which
were selected for the SCD Site using the Superfund Risk
Assessment Guidance Document and the site-specific human health
and ecological assessment. However, EPA believes that the clean-
up criteria are protective and will minimize the threat to human
health and the environment and are consistent with RCRA's
Contained-in Policy. Therefore, once the Superfund contaminated
soils and sediments at the Site have been treated to reduce the
concentration of COCs to below the clean-up criteria (soils must
also pass TCLP analysis) , they need not be managed in accordance
with all Subtitle C requirements provided the treated soils are
managed/disposed at the SCD Superfund Site. The site-specific
clean-up criteria, however, will only apply to the waste or
contamination described in this ROD; they are not intended to be
used as cleah-up criteria or standards for any other
contamination or wastes under any other circumstances.
In February 1993, EPA promulgated regulations under Subtitle C of
RCRA in the Federal Register which utilized the concept of
Corrective Action Management Units ("CAMUs") to address the
management of remediation wastes. The regulation states that
"placement of remediation wastes into or within a CAMU does not
constitute land disposal of hazardous wastes." The regulations
require-that the CAMU satisfy specific criteria before EPA's
Regional Administrator can designate an area or unit as a CAMU.
During the public comment period, Standard Chlorine proposed that
the sedimentation basin be designated as a CAMU. Upon a review
of the CAMU regulations and Standard Chlorine's comments, EPA has
determined that the retrofitted sedimentation basin could not be
30
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designated as a CAMU. Further detail and discussion of this
issue, beyond that discussed below, can be found in the
Responsiveness Summary attached to this ROD.
Alternatives 2 and 3 would not be able to comply with LDR or the
"Contained-in Policy" because neither alternative will reduce the
concentration of contaminants in the soils or sediments to
satisfy the Land Disposal Regulations or health based numbers.
Alternatives 2 and 3, will therefore be eliminated from further
consideration as viable alternatives since neither alternative
will satisfy the RCRA ARARs.
EPA's internal review of the draft ROD for the SCD Site revealed
the possibility that the on-site clean-up criterion of 450 mg/kg
of 1,4-dichlorobenzene could possibly fail TCLP analysis. EPA's
Risk Reduction Engineering Laboratory in Cincinnati, Ohio stated,
"Soil and sediment containing more than 150 mg/kg 1,4-
dichlorobenzene have the potential to be characteristic
hazardous wastes. The TCLP limit for this compound
(hazardous waste number D027) is 7.5 mg/L; 100 times
higher than the drinking water MCL (at the time the TCLP
standard was set) but about 10 times lower than the
solubility of 1,4-dichlorobenzene in pure water."
EPA RCRA program staff agreed that soil containing 450 mg/kg of
1,4-dichlorobenzene could fail TCLP analysis. Therefore, EPA
will require all excavated and treated soils be analyzed for TCLP
to demonstrate that the treated soils do not meet the definition
of a characteristic hazardous waste.
Additional treatability studies/pilot tests are required to
determine if soils and sediments excavated and treated under
Alternatives 5A and 6 would remediate the soils and sediments to
the clean-up criteria and TCLP limits. Soils and sediments
treated in situ under Alternatives 4A and 6 are not subject to
the land disposal requirements. -Previous studies have
demonstrated that the thermal component of Alternatives 4A and 4B
can remove 99.9% of the contaminants and in turn will be able to
remediate the soils and sediments to the clean-up criteria and
TCLP limits.
There are several other ARARs associated with remediation of the
soils and sediments that must be complied with. For example, the
Delaware Wetlands Act of 1973 and the Archeological and
Historical Preservation Act of 1974 must be addressed. All of
the alternatives can be designed and implemented to comply with
these requirements.
There are no ARARs that establish specific clean-up criteria for
soils and sediments. Therefore, the results of the human health
and ecological risk assessment performed as part of the RI/FS
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were used to establish acceptable exposure levels for soils and
sediments. Alternatives 4A, 4B, 5A, and 6 will prevent exposure
to contaminated soils/sediments above the acceptable exposure
levels.
Alternatives 4B and 5A will have the greatest negative impact on
the surrounding wetlands, since they involve the physical removal
of all contaminated soils and sediments above the established
clean-up criteria. This impact is off-set by having the most
assurance of satisfying Delaware Surface Water Quality Standards
for Red Lion Creek. Each of the alternatives involves some
impact on the wetland areas. Alternatives 4A and 6 may be the
least disruptive to the habitats in the wetlands, however, each
alternative includes provisions for wetlands restoration.
7.3 Long-Term Effectiveness and Permanence
Long-term effectiveness and permanence refers to the ability of a
remedy to maintain reliable protection of human health and the
environment over time once clean-up levels have been achieved.
Ground Water
The ground water treatment and containment systems proposed in
Alternatives 4A, 4B, 5A and 6 provide a more effective barrier in
containing the ground water plume than the option proposed in
Alternative 2. All of the alternatives will result in hazardous
substances remaining on-site above health-based levels. Since
the ground water component of the remedy is an interim action,
review of this portion of the remedy will be ongoing as EPA
continues to develop final remedial alternatives for the ground
water and DNAPLS.
Soils/Sediments/Surface Water
Previous studies have demonstrated that the thermal treatment in
Alternatives 4A and 4B is capable of a 99.9% removal efficiency.
There is some uncertainty associated with remediating the
sediments to clean-up criteria with in situ bioremediation in
Alternatives 4A and 6 and with ex situ bioremediation in
Alternatives 5A and 6. If bioremediation is successful,
Alternatives 4A, 5A and 6 provide for treatment of all surface
soils and sediments above the clean-up criteria and therefore
offer long-term effectiveness and permanence equivalent to
Alternative 4B.
There are uncertainties associated with bioremediation
(Alternatives 4A, 5A and 6) in satisfying performance standards
or clean-up criteria, which will require treatability studies and
pilot scale tests prior to implementation. In situ
bioremediation and its success for treating chlorinated benzene
has not been demonstrated in the field to date. In the event
32
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that treatability studies demonstrate that the technology
employed pursuant to Alternatives 6 is ineffective, (i.e., cannot
reduce the level of contaminants in soils/sediments to the clean-
up criteria), the contingency remedy Alternative 4B, will provide
for long-term effectiveness and permanence.
7.4 Reduction of Toxicity, Mobility, or Volume through
Treatment
This evaluation criterion addresses the degree to which a
technology or remedial alternative reduces the toxicity,
mobility, or volume of a hazardous substance. Although § 121 (b)
of CERCLA, 42 U.S.C. § 9621(b), establishes a preference for
remedial actions that permanently and significantly reduce the
toxicity, mobility, or volume of hazardous substances, EPA
expects to use a combination of treatment and engineering
controls to achieve protection of human health and the
environment, as set forth in the NCP at 40 C.F.R.
§ 300.430(a) (iii) . EPA's expectation is that treatment should be
utilized whenever principal threats occur, and that containment
will be considered for wastes that pose a relatively low long-
term threat or where treatment is impracticable.
Ground Water
Each of the alternatives would reduce the volume and toxicity of
the contamination through the use of recovery wells, at DNAPL
pools if identified during the remedial design. Ground water
would be treated on-site and recovered DNAPLs would be shipped
off-site for treatment. The interceptor trench in Alternatives 3
through 6 provides a more effective physical barrier than the
extraction wells in Alternative 2, and in turn would be more
effective in reducing the mobility of contaminated ground water
and DNAPLs. The physical barrier to contain ground water would
reduce the mobility of contamination as an interim action, while
a final remedial solution is being developed. EPA will require
that interim actions to contain ground water and remove DNAPLs at
the SCD Site be implemented, while additional information is
collected and evaluated and an ultimate remedy will be outlined
in a final ROD for ground water at the Site.
Soils/Sediments/Surface Water
Alternatives 4A, 4B, 5A and 6 provide for maximum reduction of
toxicity and mobility by permanently treating the soils. It is
anticipated that bioremediation will reduce the level of
contaminants to the clean-up criteria. If additional studies
demonstrate that bioremediation (Alternatives 4A, 5A and 6) is
ineffective, (i.e., cannot reduce the level of contaminants in
soils/sediments to the clean-up criteria), Alternative 4B, would
be most effective in reducing the toxicity, mobility, and volume
of contamination through treatment.
33
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7.5 Short-Term Effectiveness
This evaluation criterion addresses the effects of the
alternative during the construction and implementation phase
until remedial objectives are met. Under this criterion,
alternatives are evaluated with respect to their effects on human
health and the environment during implementation of the remedial
action.
Ground Water
Alternative 2 requires the installation of additional extraction
wells which is much less intrusive than the construction of the
interceptor trench which is the ground water remedial measure
proposed in Alternatives 3.through 6. The trench would require
more manpower and could possibly expose workers and the
environment to airborne emissions and contaminated ground water
during its construction. Alternative 2 would have a minimum
impact on the wetlands and could be implemented more quickly than
the interceptor trench. The topography of the area where the
trench would be constructed is steep in some areas, resulting in
space constraints and associated safety hazards. Thus,
Alternative 2 would have some advantages over the remaining
alternatives with respect to short-term effectiveness.
Soils/Sediments/Surface Water
Alternatives 4A, 4B, 5A and 6 require excavation of sediments
which can result in additional exposure of workers and the
environment to airborne emissions. Both 4B and 5A will have
significant short-term negative impact on wetlands, which will be
mitigated as part of the remedial action. If additional
treatability studies demonstrate that in situ bioremediation can
satisfy the performance standards and clean-up criteria for
sediments in the unnamed tributary, Alternatives 4A, and 6 would
be equivalent in short-term impacts. There is some uncertainty
of the estimated timeframes required for bioremediation, both in
situ (Alternatives 4A, 6) and ex situ (Alternatives 5A and 6) , to
treat the soils and sediments to the clean-up criteria.
7.6 Inplementability
Implementability refers to the technical and administrative
feasibility of a remedy, including the availability of materials
and services needed to implement each component.
Ground Water
Alternative 2 is easier to implement than Alternatives 3 through
6, because of the simpler design. Ground water remediation for
Alternatives 3 through 6 employs conventional construction
techniques but the limited space available, as well as the
34
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specific physical barrier type selected, may affect the relative
ease of implementability.
Soils/Sediments/Surface Water
Alternative 4B (Thermal Treatment) utilizes a proven technology,
but would be somewhat difficult to implement at this Site due to
difficulties in accessing some of the sediments, as well as the
need to pre-treat the sediments to reduce the moisture content.
Alternative 5A and 6 (Ex Situ Biological Treatment) utilize a
developing technology and would require additional treatability
studies and pilot scale tests prior to implementing on a site-
wide basis. There is even less certainty associated with the
implementation of an in-situ biological process (Alternative 4A
and 6) due to the difficulties associated with maintaining
optimal conditions in a natural environment. Monitoring the
. effectiveness of in situ bioremediation may present additional
uncertainties.
7.7 Cost
All Media
The costs of the alternatives shown above in Section 6 include
capital costs and operation and maintenance ("O&M") costs. The
cost estimates are based on a variety of information, including
estimates from suppliers, construction unit costs, vendor
information, and conventional cost estimate guides.
Alternatives 4A, 4B, 5A and 6 are in line with the statutory
preference for treatment to reduce inherent hazards posed by
principal threats. The present worth cost estimate of
Alternative 4A is $11.7 million, 4B is estimated at $17.1
million, Alternative 5A is estimated to cost from $10.6 million
to $12.9 million, and Alternative 6 is estimated to cost from
$6.6. million to $12.2 million.
7.8 State Acceptance
The Delaware Department of Natural Resources and Environmental
Control (DNREC), acting on behalf of the State of Delaware, has
concurred with the selected remedy.
7.9 Community Acceptance
Generally, local residents and concerned citizens expressed no
opposition to the selected remedy at the public meeting held on
April 27, 1994, provided that the additional studies conducted
during the Remedial Design demonstrate that bioremediation would
be successful in reducing the.level of contaminants to.the clean-
up criteria. Standard Chlorine of Delaware submitted comments on
the selected remedy and stated its preference for Alternative 3.
The comments received during the public comment period concerning
35
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the various alternatives are summarized in the Responsiveness
Summary which is part of this ROD.
8.0 SELECTED REMEDY: DESCRIPTION AND PERFORMANCE STANDARDS
8.1 Description of Selected Remedy
Based on the findings in the RI/FS, the nine criteria listed
above, and public comments, EPA has selected Alternative 6 (Ex
Situ/In Situ Bioremediation) as the remedy for the. contaminated
soils and sediments at the SCD Site, with a contingency to
implement Alternative 4B (Low Temperature Thermal Desorption) in
, the event that it is determined that the bioremediation
alternative cannot achieve the clean-up criteria. The selected
remedy also includes a component to contain contaminated ground
water and to recover DNAPLs as described below.
8.1.1 Ground Water - Interim Remedy
The selected remedy calls for the design and implementation of an
interim remedial action for ground water to protect human health
and the environment. The goals of this remedial action are (1)
to prevent further migration of the contaminated ground water,
(2) prevent further degradation of the unnamed tributary to Red
Lion Creek and of Red Lion Creek, (3) to remove DNAPL pools, if
identified during remedial design, which act as a. continuing.
source of ground water contamination, and (4) to gather
information to use in determining the technical practicability of
remediating ground water.
Information gathered during the implementation of this interim
remedial action will be evaluated to determine the technical
practicability of remediating the ground water to health based
levels and to ensure .that hydraulic control of the contaminated
plume is maintained. After EPA, in consultation with DNREC,
determines- that sufficient information, has been collected' to make
a decision regarding the technical practicability of remediating
ground water to health based levels, a final ROD for ground
water, which specifies the final goal.for the remedial action and
anticipated remediation timeframe, will be prepared by EPA.
8.1.1.1 Physical Barrier
The ground water containment component of the selected remedy
consists of a physical barrier such as a trench or slurry wall.
The physical.barrier will be installed along the shorelines of
the unnamed tributary to Red Lion Creek and Red Lion Creek to
capture ground water and DNAPLs before they enter the Red Lion
Creek. Soils excavated from the trench may be contaminated and
will be analyzed to determine the concentration of contaminants.
Excavated soils exceeding the off-site clean-up criterion will
36
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undergo remediation as described below in Section 8.1.2 before
appropriate disposal occurs. In addition, low volume recovery
wells will be installed to attempt to recover DNAPLs. The
recovered DNAPLs will be stored on-site temporarily and
ultimately disposed of off-site in accordance with applicable
hazardous waste regulations. Recovered ground water will be
treated in the existing air stripper and then discharged to the
Delaware River under SCD's NPDES permit requirements. Off gases
will be treated by either burning in the existing facility
boilers or other appropriate treatment in accordance with all
applicable federal and state requirements to prevent transfer of
contaminants from the water to the air.
8.1.1.2 Existing Ground Water Control Systems
Repairs and upgrades (if necessary) of the existing ground water
pump and treat system will be required. Historically, a few of
the well pumps have not functioned at optimum capacity. At a
minimum, measures to ensure that the existing recovery wells pump
at design capacity will be required. . In addition, routine
physical testing of Catch Basin #1 will be required to minimize
the possibility of future releases.
8.1.1.3 Institutional Controls
Institutional controls will include use, access, and deed
restrictions. With respect to deed restrictions, notifications
will be placed on the deeds to the properties that comprise the
Site (includes property.currently owned by Occidental and Air
Products) which shall limit the future use of the Site to prevent
exposure to ground water and subsurface soils. The deed
restrictions shall identify the extent of ground water
contamination and the areas containing subsurface contamination.
Given the extent of ground water and subsurface soil
contamination and the selection of an industrial use clean-up
level (for on-site soils), imposition of deed restrictions is
necessary to protect human health and avoid more costly and more
disruptive remedial action. In addition, DNREC will implement a
ground water management zone for the area.
8.1.1.4 Possible Facility Closure
The remedy includes a provision for the development of a plan to
provide an alternate means of treating the ground water and
DNAPLs in the event that SCD should reduce or cease operations at
the Site. Any other environmental concerns at the time of
possible closure of the facility will be addressed by various
federal laws and regulations as well as those of the State of
Delaware.
37
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8.1.1.5 Additional Investigative/Monitoring Work
Additional investigative work will be required to define the
extent of the DNAPL and ground water contamination. This
investigation will include the installation of wells on the north
side of Red Lion Creek and on property currently owned by Air
Products. A detailed evaluation of the restoration potential of
the aquifer will also be conducted.
The FS did not address remediation of ground water in the
vicinity of monitoring well number 16 ("MW #16") , which is
adjacent to the effluent pipeline. Since the investigation of
this area was limited to one round of sampling, additional
investigation of this area will be conducted during the remedial
design. Based on the results of this investigation, EPA in
consultation with DNREC may require additional ground water
remediation activities in the vicinity of the effluent pipeline.
Pre-remediation and post-remediation monitoring of the Site,
according to a monitoring plan developed during the Remedial
Design, will be required to ensure that the remedy is protective
of resources at the Site. Site monitoring activities will
include monitoring of the ground water in both the Columbia and
Potomac Formations, off-site monitoring including monitoring
wells located on adjacent properties, and monitoring of the
surface water systems present at the .Site (the wetlands, unnamed
tributary to Red Lion Creek, and Red Lion Creek) . The ground
water monitoring activity will involve the installation of
additional on-site and off-site monitoring wells.
8.1.2 Soils/Sediments - Final Remedy
EPA's selection of a final action to remediate the contaminated
soils and sediments at the SCD Site is a modified Alternative 6
(Ex Situ/In Situ Biological Treatment) with a contingency final
action of a modified Alternative 4B (Thermal Treatment) , if
Alternative 6 is unable to remediate contaminated soils and
sediments to the clean-up criteria. The modifications of
Alternatives 4B and 6, from those described in the Proposed Plan,
include the following provisions:
1) "Hot Spot" sampling and analysis of soils where
releases have occurred on the operating portion of the
Site and may not have been properly remediated and/or
areas where hazardous materials may have been placed or
temporarily stored based on current and past operational
practices;
2) TCLP analysis of remediated soils to ensure treated
soils no longer meet the definition of a characteristic
hazardous waste.
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8.1.2.1 Sedimentation Basin
Each of the alternatives in the FS proposed using the existing
sedimentation basin for consolidating contaminated and or treated
soils and sediments which would not comply with ARARs (see
Section 7.2 of this ROD and the Responsiveness Summary).
Therefore, the selected remedy will include closure of the
existing sedimentation basin in accordance with all applicable
state and federal regulations.
Closure of the sedimentation basin will include testing of the
soils underlying the existing liner to insure that the soils are
not contaminated. Any contaminated soils underlying the basin
that exceed the off-site clean-up criterion of 33 mg/kg for total
COCs will be remediated. Closure of this area will include
grading, placement of top soil, seeding and planting a variety of
plants and grasses. The flora species will be selected for
survivability and value in development of diversity, density, and
abundance of wildlife quality and will include mixed herbs,
.grasses and shrubs.
8.1.2.2 Bioremediation Alternative
As part of Alternative 6, additional studies (treatability
studies and pilot scale tests) of both ex situ and in situ
bioremediation will be conducted during the Remedial Design to
determine if either will be able to treat the soils/sediments to
the clean-up criteria. If additional studies demonstrate that
neither ex situ nor in situ biological treatment are able to
remediate soils to the clean-up criteria as delineated in Section
5.3.3. of this ROD, then Alternative 4B (Low Temperature Thermal
Desorption) will be implemented.
Several different types of biological treatment processes will be
evaluated during the Remedial Design. Treatability studies and
pilot scale tests will be performed. One type of ex situ
bioremediation to be evaluated is slurry phase'bioremediation,
where contaminated soils and sediments are placed in a reactor
(tank) and combined with water to form a slurry. Other types of
ex situ bioremediation that may be considered and evaluated
include solid-phase bioremediation and composting. In situ
bioremediation entails the additioh of nutrients, oxygen (if the
process is aerobic) , and possibly microorganisms to the
contaminated sediments to enhance the natural biodegradation
process. Several different conditions under which in situ
bioremediation may be.employed at this Site will also be
evaluated during the Remedial Design. Additional ex situ and in
situ bioremediation processes not mentioned above may also be
evaluated during Remedial Design.
If, based on the results of the additional treatability studies,
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full-scale bioremediation is performed in the field, it must
effectively reduce the concentration of contaminants to satisfy
the clean-up criteria. If biological"remediation is unable to
achieve these levels, Alternative 4B will be implemented.
8.1.2.3 Thermal Treatment Alternative
If, based on the results of further testing during the Remedial
Design, it is determined that soils/sediments which are
bioremediated will not be able to meet the clean-up criteria and
pass TCLP analysis, the contingency Alternative 4B will be
implemented. This alternative involves the Low Temperature
Thermal Desorption ("LTTD") of. contaminated soils and sediments.
Under this alternative, contaminated soils/sediments will be
heated at low temperatures ranging from 200* to 1000"F, driving
off water and volatile contaminants. Recovered product from this
treatment would be sent to the SCD plant for reuse if possible.
Recovered vapors (air emissions) will be burned in an
afterburner, sent to the existing boilers, captured by carbon
adsorption beds or treated in some other manner consistent with
ARARs.
8.1.2.4 Clean-up Criteria
The clean-up criteria for on-site soils and sediments (soils and
sediments inside the existing fence of the SCD facility and noted
as the SCD facility boundary on Figure 2) is 625 mg/kg of total
COCs with a ceiling of 450 mg/kg for 1,4-dichlorobenzene. All
on-site soils and sediments containing contamination in excess of
these criteria will be remediated to the on-site clean-up
criteria and pass TCLP analysis before they can be used as
backfill for the on-site excavated areas. On-site soils will be
remediated to the off-site clean-up criteria before they can be
used as backfill for off-site excavated areas.
The selected remedial alternative will provide for treatment of
contaminated soils both on and off-site. The clean-up criterion
for off-site soils and sediments (soils and sediments outside the
existing fence of the SCD facility and noted as the SCD facility
boundary on Figure 2) is 33 mg/kg of total COCs. All off-site
excavated contaminated soils and sediments will be remediated to
the off-site clean-up criterion and pass TCLP analysis before
they can be used as backfill for the off-site or on-site
excavated areas.
Soils along the western drainage gully (to a depth of 7 feet) ,
soils in the waste piles, sediments in the sedimentation basin,
sediments in and along the unnamed tributary that exceed the off-
site clean-up criterion of 33 mg/kg of total COCs and the soils
along the eastern drainage ditch (to a depth of 3 feet) and Catch
Basin #1 (to a depth of 15 feet) that exceed the on-site clean-up
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criteria of 625/450 mg/kg of total COCs will either be excavated
and treated (using ex situ bioremediation) or biologically
treated in place (in situ bioremediation). If bioremediation is
unable to treat the soils to the clean-up criteria, the soils
will be excavated and treated with Low Temperature Thermal
Desorption. Excavation beyond a depth of 15 feet may result in
damage to the structural integrity of the Catch Basin. After the
soils adjacent to the Catch Basin have been treated to meet the
clean-up criteria, the area will be capped with a low
permeability asphalt cap. .
Since shutting down the railroad tracks would detrimentally
affect SCD plant operations, soils along the railroad tracks that
exceed the on-site clean-up criteria of 625/450 mg/kg of total
COCs will be biologically treated in place. If in situ
.bioremediation is unable to remediate the soils .in this area to
the clean-up criteria, this area will be capped with a low
permeability asphalt cap which will minimize infiltration.
In the .event that SCD should reduce or cease operations at this
Site, EPA will re-evaluate the on-site clean-up criteria since
they are based on occupational exposure.
8.1.2.5 Soil and Sediment Monitoring
Ecological monitoring will be conducted annually starting prior
to the start of remedial action to establish a data baseline, and
then annually thereafter for a period of at least five years.
The purpose of the ecological monitoring is to document that the
remedial objectives are met. The ecological monitoring
activities will include chemical analysis of surface water,
sediments, fish and muskrat tissue, and bioassays. Decisions
regarding the possible need for additional remediation activities
will be made after the monitoring activities have been conducted
long enough to establish trends and those trends have been
thoroughly evaluated by EPA, DNREC, and any necessary support
agencies. Decisions regarding the need for any possible
additional remediation and/or monitoring activities at the Site
will be made by EPA in consultation with DNREC.
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8.1.2.6 Additional Work
EPA received comments during the public comment period concerning
possible spills and releases of hazardous substances at the SCD
Site that may not have been properly remediated or addressed.
The EPA RCRA program has also expressed concern that areas which
would typically be evaluated under a RCRA Facility Investigation,
were not investigated as part of the Superfund Remedial
Investigation. Therefore, the selected alternative will also
require "Hot Spot" sampling and analysis. Spill areas that were
identified during the Remedial Investigation will be sampled and
analyzed for potential contamination. Other areas that may be
included in the "Hot Spot" analysis are areas or units at the
Site where hazardous material may have been placed or temporarily
stored based on current and past operational practices. Soil
samples collected from these areas will be analyzed to determine
if they are contaminated. The "Hot Spot" investigation will
include sampling and analysis of soils for various parameters
including volatile organic and semi-volatile organic compounds.
In addition, twenty-five per-cent (25%) of the samples will also
be sampled for metals, pesticides, and Polychlorinated Biphenyls
("PCBs"). EPA may require additional work if the results of the
"Hot Spot" sampling identify contamination above the clean-up
criteria.
8.1.2.7 Summary
Alternative 6 with a contingency of Alternative 4B, is the
selected alternative for the treatment of soils, sediments and
ground water at the Site, since it meets the threshold criteria,
and provides the best balance of long- and short-term
effectiveness, permanence, implementability, and reduction of
toxicity, mobility and volume of contaminants through treatment.
The NCP states that EPA will place priority on treating materials
that pose the principal threat at a given site.
Alternative 6 is the selected alternative because it has the
potential to achieve the same end result as Alternative 4B at a
substantially lower cost. EPA and DNREC foresee the use of a
combination of ex situ bioremediation and in situ bioremediation
at this Site. For example, ex situ bioremediation could be used
for all soils and some sediments. . If successful, in situ
bioremediation would be used in the railroad track area and for
some of the sediments for which access is difficult along the
unnamed tributary to Red Lion Creek and the.Red Lion Creek.
Alternative 4B will be implemented if the additional
investigation performed during the Remedial Design demonstrates
that bioremediation will not be able to satisfy the clean-up
criteria. Previous studies have demonstrated that this
technology (Low Temperature Thermal Desorption) is capable of a
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99.9% Destruction Removal Efficiency ("DRE") for the contaminants
found in the soils and sediments at the Site. In addition,
possible recovery and reuse of the product phase will also
reduces the volume of residuals which could require further
treatment.
8.2 Performance Standards/Clean-up Criteria
8.2.1 Ground Water
To reduce the risk to human health and the environment via the
exposure pathways attributed to the migration of ground water
from the Site, a physical barrier such as a trench or slurry wall
shall be installed along the shorelines of the unnamed tributary
to Red Lion' Creek and Red Lion Creek to capture ground water -and
DNAPLs before they enter Red Lion Creek. In addition, low volume
recovery wells shall be installed to attempt to recover DNAPL
pools which may be identified during the Remedial Design.
The physical barrier shall be designed and constructed to prevent
contaminated ground water and DNAPLs from migrating to the
unnamed tributary to Red Lion Creek and to Red Lion Creek. The
length, location, and material to be used for the construction of
the physical barrier shall be approved by EPA, in consultation
with DNREC, during the Remedial Design.
The existing ground water extraction wells (RW #1, #2, #3, #4,
and #5) shall be repaired (or replaced, if necessary) so that
they shall operate at original design capacity. A ground water
extraction system shall be constructed to accompany the physical
barrier selected during Remedial Design. The dewatering system
shall collect ground water and pump it to a waste water treatment
plant. The elevation of the Columbia aquifer shall be maintained
so as not to exceed the seasonal high ground water table'prior to
construction of the physical barrier.
The extracted ground water shall be treated to comply with the
substantive requirements of the Delaware Regulations Governing
Control of Water Pollution for discharge to the Delaware River
(Refer to Table 10 for a listing of the ARARs associated with the
selected remedy) .
Air emissions generated from the treatment of ground water shall
be treated and shall comply with the substantive requirements of
the State of Delaware Implementation Plan, the National Emissions
Standards for Hazardous Air Pollutants, the Delaware Ambient Air .
Quality- Standards, and the Delaware Regulations Governing the
Control of Air Pollution.
All residual waste generated as a result of ground water
treatment shall be disposed of at an off-site facility approved
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by EPA.
Recovery wells shall be installed at areas identified during the
Remedial Design that contain known DNAPLs. Location of wells and
pumping rates shall be designed to maximize DNAPL removal.
Collection and storage of DNAPLs shall comply with the
substantive requirements of the Delaware Regulations Governing
Hazardous Waste. Recovered DNAPLs shall be shipped off-site for
disposal in accordance with applicable federal and state
regulations promulgated pursuant to RCRA.
An operations and maintenance plan for the ground water
containment and extraction system shall be developed. The
performance of the ground water containment and extraction system
shall be monitored on a monthly basis and documentation of
results submitted to EPA and DNREC on a quarterly basis.
Operation of the system may be modified, as warranted by the
performance data collected during operation, as approved by EPA
in consultation with DNREC.
All components of the ground water remedy shall be implemented in
accordance with the ARARs delineated in Table 10.
8.2.1.1 Ground Water Investigation/Monitoring
Investigation
A ground water investigation shall be conducted to characterize
the nature and extent of ground water and DNAPL contamination.
The investigation shall provide information to determine the
extent of ground water contamination as well as the technical
practicability of remediating ground water to MCLs and other
health-based levels. Information gathered during this
investigation shall address the following areas of concern:
contaminant characteristics; hydrogeological conditions;
contaminant distribution and potential subsurface migration;
performance of aquifer restoration and other previous response
actions; availability of alternative technologies, and an
estimate of the degree of restoration that will be achievable at
the Site, if applicable.
Further investigation of the effluent pipeline shall be conducted
to determine the nature and extent of ground water contamination
in this area. Sampling and analysis of wells located on Air
Products property shall be performed. Additional monitoring
wells shall.be installed on the north side of Red Lion Creek and
on property currently owned by Air Products.
The investigation shall provide the necessary information for EPA
to make a determination of the technical practicability of ground
water restoration as delineated in the OSWER Directive 9234.2-25
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entitled "Guidance for Evaluating the Technical Impracticability
of Ground Water Restoration" and to develop final remediation
standards for ground water.
Monitoring
A ground water monitoring program shall be implemented to
evaluate the effectiveness of the ground water containment system
and DNAPL removal and containment systems. The exact location of
monitoring wells to be included in the monitoring program shall
be determined during the Remedial Design and approved by EPA in
consultation with DNREC. The frequency and duration of the
sampling and the analytical parameters and methods to be used
shall also be approved by EPA in consultation with DNREC during
the Remedial Design. In addition, an operation and maintenance
("O&M") plan approved by EPA in consultation with DNREC'shall be
implemented for the ground water monitoring program. Monitoring
shall continue until EPA, in consultation with DNREC, makes a
final decision on the ground water remedy in a ROD.
Additional monitoring wells shall be installed at locations
determined during Remedial Design by EPA for the purpose of
defining the nature and extent of ground wat-er contamination.
Trench Excavation
Sampling and analysis of excavated soils from the trench (See
Figure 13) shall be conducted in a statistically significant
manner, to be approved by EPA in consultation with DNREC, to
determine if 'soils require remediation. Any excavated soils from
the trench which exceed the off-site clean-up criterion of 33
mg/kg of total COCs will undergo remediation as described in
Section 8.1.2.
8.2.1.2 Institutional'Controls
DNREC shall institute a ground water management, zone (GMZ) in the
Site area to prevent exposure to contaminated ground water
through the installation of future potable water wells.
Institutional controls will include use, access, and deed
restrictions. With respect to deed restrictions, notifications
shall be placed on the deeds to the properties that comprise the
Site (includes property currently owned by Occidental and Air
Products) which shall limit the future use of the Site to prevent
exposure to ground water and subsurface soils. The deed
restriction shall identify the extent, of ground water
contamination and the areas containing subsurface contaminated
soils. The notifications shall remain in effect until drinking
water standards are achieved throughout the contaminated area and
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flR3087(3
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the subsurface soils are remediated.
Signs shall be posted at all times on the west and east side of
Route 9, adjacent to Red Lion Creek, that warn the public of the
advisory recommending that the public not consume fish from Red
Lion Creek in the area from Route 13 to the Delaware River until
the advisory is lifted by DNREC and the Division of Public
Health.
8.2.2 Soils and Sediments
8.2.2.1 Performance Standards Common to Both Bioremediation and
Thermal Treatment
To reduce the risk to human health and the environment, soils, and
sediments shall be remediated as described in Section 8.1,
Description of the Selected Remedy. All components of the remedy
and contingency remedy for soils and sediments shall be
implemented in accordance with the ARARs delineated in Table 10.
Excavation of Soils and Sediments
Confirmatory sampling shall be conducted in a statistically
significant manner, to be approved by EPA in consultation with
DNREC, to determine that sufficient soils, and sediments have been
excavated. The excavated areas containing contaminated soils in
the subsurface shall either be lined with a flexible membrane
liner prior to being backfilled or shall be capped in a manner to
reduce infiltration through the contaminated subsurface soils.
Management and Disposal of Treatment Residuals
During Remedial Design, a waste management plan shall be
developed to identify potential waste streams and appropriate
handling and disposal mechanisms. This plan-shall be approved by
EPA in consultation with DNREC. In the event treatment residuals
are determined to be hazardous wastes, they shall be managed in
accordance with the federal and state ARARs outlined in Table 10.
These wastes may include contaminated carbon filters, waste
water, and recovered product.
Backfilling of Treated Soils and Sediments
The treated soils and sediments may be backfilled into excavated
areas if they satisfy the clean-up criteria and pass TCLP
analysis as follows: all off-site excavated contaminated soils
and sediments shall be remediated to the off-site clean-up
criterion (33 mg/kg of total COCs) and pass TCLP analysis before
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they shall be used as backfill for the on-site or off-site
excavated areas; all on-site excavated soils shall be remediated
to the on-site clean-up criteria (625 mg/kg of total COCs with a
ceiling of 450 mg/kg of 1,4-dichlorobenzene) and pass TCLP
analysis before they shall be used as backfill for on-site
excavated areas. On-site excavated soils and sediments may only
be used as off-site backfill if they meet the off-site clean-up
criterion.
Closure of the Sedimentation Basin
Closure shall include sampling of the soils underlying the
existing liner in a statistically significant manner to insure
that the soils do not contain concentrations of contaminants
which exceed the off-site clean-up criterion (33 mg/kg of total
COCs). Following excavation the area shall be graded and a
protective, vegetative soil cover shall be placed over the area.
The soil cover shall: (1) support the germination and propagation
of vegetation; and (2) compact well and not crack excessively
when dry. EPA anticipates that following treatment, the soil
will no longer "contain" hazardous wastes and thus will cease to
be a hazardous waste for purposes of federal and state law.
Maintenance of the area formerly occupied by the sedimentation
basin shall be conducted as necessary until the area is
stabilized with diverse plant growth which can support animal
species common to the area.
Waste Piles
The design, operation, and closure and post-closure of the
existing waste piles and waste piles generated during the
stockpiling of excavated soil from either the pilot scale
treatability studies or the full-scale implementation of the
remedy shall comply with the substantive regulations set forth in
the Delaware Regulations Governing Hazardous Waste, §§ 264.250-
259 and 4.0 C.F.R. § .264 Subpart M - Land Treatment for
bioremediation and 40 C.F.R. §264 Subpart L - Waste Piles for
thermal treatment.
Tanks
The design and operation of tanks used in the treatment of
contaminated soils and sediments shall comply with the
substantive regulations set forth in the Delaware Regulations
Governing Hazardous Waste, §§ 264.190-199 and 40 C.F.R. §§
264.190 - 199.
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Capping
The cap to be constructed in the railroad track and catch basin
areas shall consist of asphalt and shall be constructed in a
manner to minimize infiltration into the subsurface. The areas
to be capped shall be graded to minimize ponding of water and
designed to accommodate heavy traffic. Routine inspection and
maintenance of the capped areas shall be required until such time
as EPA determines that the subsurface soils are no longer serving
as a source of ground water contamination. Maintenance shall
include repairs to the asphalt cap as necessary to correct cracks
and to control the effects of settling and subsidence.
Catch Basin #1 Integrity Testing
Catch Basin #1 will undergo integrity testing no less than once a
year upon EPA's approval of testing plans and protocols in
consultation with DNREC. The testing shall consist of a
hydrostatic test or some equivalent test to determine the
integrity of the catch basin. Testing plans and protocols shall
be submitted during Remedial Design to EPA for approval prior to
implementing the tests.
Surface Water Runoff Controls
Storm water runoff from all areas of soil disturbance resulting
from Site remediation activities which may reach the waters of
the state of Delaware without treatment prior to discharge shall
be controlled in a manner consistent with ARARs. EPA, in
consultation with DNREC, will approve the control measures to be
implemented at the Site. All control measures shall be routinely
inspected and maintained until EPA, in consultation with DNREC,
determines that storm water runoff no longer poses a potential to
contaminate waters of the state of Delaware
Wetlands
Excavation in the wetland areas, if it occurs as part of the
remedy, shall meet the following criteria:
1) The excavated areas in the wetlands may remain at the
excavated elevation and grade, no deeper than three feet, (as
opposed to backfilling) if an acceptable marsh substrate exists.
The substrate would be acceptable if it contained sufficient
organic matter to support the growth of wetland species and
contains less than 33 mg/kg of total COCs. If the substrate is
not suitable for planting, a two to three inch layer of clean
fill containing sufficient organic matter to support wetlands
vegetation shall be applied before planting. Temporary
stabilization shall include planting of water tolerant annual
species in the exposed wetland area.
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2) The upland areas and banks shall be stabilized in accordance
with substantive State erosion and sedimentation control
requirements. Temporary stabilization shall include planting of
an acceptable annual species in the upland/bank areas. The
plantings shall be maintained until the area is stabilized.
3) Natural succession is acceptable as long as there is a
Phragmites control plan in place. The phragmites control plan
shall be approved by EPA in consultation with DNREC. In the
event that natural succession in the wetlands is not successful
(e.g. 80% cover within 1-2 years) a contingency plan to maintain
plantings shall be developed.
4) Prior to excavating sediments in the wetland area, a minimum
of four man-days work shall be spent collecting and moving to a
new environment any wildlife residing in areas to be remediated.
5) The excavation of contaminated sediment and soils shall be
designed and performed in such a way as to minimize environmental
harm.
A monitoring plan for wetland vegetation, both planted and
naturally occurring, shall be-developed and approved by EPA in
consultation with DNREC. The wetland monitoring shall be
conducted for at least five years after the remedial action is
complete in order to document the successful re-establishment of
a wetland community.
Any damage to the wetlands done as part of the remediation
activities shall be mitigated on a one to one ratio and in
accordance with Section 404 of the Clean Water Act. The wetland
restoration plan shall be approved by EPA in consultation with
DNREC.
Erosion Control
An erosion control plan shall be developed and implemented which
outlines procedures to be used to control transport of soil and
sediment. The plan shall be developed in accordance with state
and/or local regulations and shall be approved by EPA in
consultation with DNREC. It shall address all activities .which
present the potential for transport of soils and sediments.
Health and Safety
During all Site work, Occupational Safety and Health
Administration ("OSHA") standards set forth at 29 C.F.R. Parts
1904, 1910, and 1926 governing worker safety during hazardous
waste operations, shall be met. The Remedial Design shall
include a Health and Safety Plan to be accepted by EPA.
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All remedial work shall be done in such a manner as to minimize
transport of airborne participates and volatilization of
contaminants. As part of the remedial action Health and Safety
Plan, levels of particulate and/or air contaminants considered to
pose an unacceptable health risk in accordance with OSHA
regulations and the National Institute for Occupational Safety
and Health ("NIOSH") guidance documents shall be identified along
with monitoring requirements to measure particulate counts and/or
air contaminant concentrations.
An EPA-approved air monitoring program shall be established for
the remedial action. This monitoring program shall provide for
the protection of on-site workers and prevent the release of
unacceptable emissions. Emissions from the remedial activities
shall not exceed a carcinogenic risk of 1 x 10"s. If this level
is exceeded, control measures shall be implemented to reduce
emissions below this level.
Air monitoring shall be done at appropriate times to ensure
protectiveness of human health. If the air monitoring results
indicate that particulate counts and/or air contaminant
concentrations are high enough to pose unacceptable health risks
to people on-site or off-site, appropriate measures shall be
taken to reduce the emissions to safe levels off-site, and either
to reduce the emissions to safe levels on-site or to protect the
workers through personnel protective equipment.
Institutional Controls
Institutional controls will include use, access, and deed
restrictions. With respect to deed restrictions, notification
shall be placed on the deeds to the properties that comprise the
Site (includes property currently owned.by Occidental and Air
Products) which shall limit the future use of the Site to prevent
exposure to ground water and subsurface soils. The deed
restriction shall identify the extent of ground water
contamination and the areas containing subsurface contaminated
soils.
Access Restrictions
The existing fence (noted as the SCD boundary on Figure 2) shall
be maintained to restrict access to the operating portion of the
Site. A minimum of five (5) signs shall be posted along the
unnamed tributary to Red Lion Creek, the Red Lion Creek, the area
around the soil piles, sedimentation basin, and the western
drainage gully. The signs shall warn trespassers and any others
on the property of the contamination in the area and shall be
maintained until the soils/sediments are remediated to the clean-
up criteria.
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Ecological Monitoring
The effectiveness of the selected remedy in protecting ecological
resources shall be monitored by an ecological monitoring plan
that shall be developed during Remedial Design. The plan shall
include monitoring of wetland soils and sediments, the stream
benthic environment, and the aquatic environment. The plan shall
be submitted for review and approval by EPA in consultation with
DNREC. Ecological monitoring shall be conducted annually with
the first round prior to the start of remedial action to
establish a data baseline and then annually thereafter for a
period of at least five (5) years.
The ecological monitoring activities shall include chemical
analysis of surface water, soils/sediments and fish and muskrat
tissue, and sediment bioassays. An ecological reference station
with similar sampling protocol shall be established as part of
the ecological monitoring plan. Annual sampling shall be
conducted in late spring, but shall not be done directly after a
storm event.
A minimum of thirteen (13) sampling stations shall be established
for monitoring the wetlands along the unnamed tributary to Red
Lion Creek and Red Lion Creek. Samples of both soil/sediment and
surface water shall be used for chemical analysis and toxicity
testing.
Fish and muskrat samples shall be chemically analyzed for
residues of COCs. Tissue residue of COCs should not be
significantly different than those in the same species taken at
an appropriate reference site.
Chemical analysis of sediments shall be conducted according to
the EPA-approved monitoring plan. Samples shall be split for
toxicity testing. Samples shall be collected from areas
estimated to have a minimum of 50% fines (percentage of sediments
that can pass through a 74 micron sieve).
Sediment toxicity testing shall be conducted according to .the
EPA-approved monitoring plan. A 30% or greater reduction in
survival compared to the control sample shall be considered a
significant impact. No significant impacts should be observed.
If EPA, in consultation with DNREC determines that these
monitoring data indicate that the Site-specific clean-up criteria
are no longer protective (for example, the chlorinated benzene
compounds remaining in the sediments become more bioavailable due
to changing conditions and cause a greater impact) , additional
remedial measures beyond those described in this ROD may be
required.
A determination of success in the recovery of the ecological
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resources at the Site and the possible need for additional
remediation activities based on the ecological monitoring will
only be made after the ecological monitoring activities have been
conducted and after evaluation by EPA, DNREC, and any necessary
support agencies using state of the art risk assessment methods..
Decisions regarding the need for any possible additional
remediation activities at the Site will be made by EPA in
consultation with DNREC.
Operation and Maintenance
An Operation and Maintenance ("O&M") Plan shall be developed for
review and approval by EPA in consultation with DNREC. The O&M
Plan shall include requirements for the maintenance of the former
sedimentation basin, Catch Basin #1, capped areas, on-site soil
disposal areas and storm water controls. The O&M Plan shall
include formats to be used for documentation of inspections and
maintenance which shall be submitted to EPA and DNREC for review.
8.2.2.2 Performance Standards for Bioremediation
Treatability Studies
A workplan for the Bioremediation Treatability Study shall be
developed during the initial phases of the Remedial Design and
submitted for approval by EPA in consultation with DNREC. The
treatability study shall be conducted in accordance with
appropriate EPA guidance including but not necessarily limited to
EPA's "Guide for Conducting Treatability Studies under CERCLA:
Aerobic Biodegradation Remedy Screening, Interim Guidance,"
EPA/540/2-91/013A, July 1991.
The treatability study shall be designed to evaluate the
technical feasibility of using in situ and. ex situ biological
treatment for remediating various portions of the SCD site. It
shall include an evaluation of technologies such as solid and
slurry phase bioremediation. It shall evaluate the possibility
of implementing aerobic and anaerobic bioremediation.
The effects that the hydrogeology of various portions of the Site
may have on the bioremediation alternative under consideration
shall be addressed in the treatability study.
The treatability study shall focus on stimulation of indigenous
microorganisms to degrade the chlorobenzene.
The treatability study shall include measures to account for
volatilization resulting from stirring or agitation. Mass balance
calculations shall be provided in a report of the findings of the
52
AR308720
-------
treatability study(s).
If EPA determines, in consultation with DNREC, that based on the
results of the pilot scale test ex situ or in situ bioremediation
can achieve the soil/sediment clean-up criteria, then
bioremediation shall be implemented in the field.
Conditions Triggering Implementation of Contingency Remedy
If the results of the treatability studies .and/or pilot scale
tests demonstrate that bioremediation technology can not meet the
soil/sediment clean-up criteria outlined in Section 8.1 above,
Low Temperature Thermal Desorption technology will be used to
treat the contaminated soils and sediments.
8.2.2.3 Performance Standards for the Contingency Alternative -
Low Temperature Thermal Desorption
If it is determined by EPA in consultation with DNREC, that
bioremediation is not capable of achieving either the on-site or
off-site clean-up criteria for contaminated soils/sediments, the
soils and sediments shall be treated using Low Temperature
Thermal Desorption ("LTTD"). In addition to the performance
standards common to both bioremediation and thermal treatment
described above, the specific performance standards for LTTD are
described below:
The operation and closure of the thermal desorption unit shall
comply with the regulations outlined in 40 C.F.R. Part 264,
Subpart X - Miscellaneous Units. Storage of all residual wastes-
shall comply with the substantive regulations set forth in the
Delaware Regulations Governing Hazardous Waste, Part 264.170-178
and Part 264.190-199 (storage of hazardous waste in containers
and tanks) .
Treatment of Air Emissions from the Thermal Desorption Unit
Contaminants in the effluent air from the thermal desorption unit
shall be removed with a treatment unit, the specifications of
which shall be determined during the Remedial Design and subject
to EPA approval in consultation with DNREC. The treatment
unit(s) shall be designed and operated in accordance with the
ARARs listed in Table 10.
Pre-design testing of the LTTD process will be conducted to
establish operating parameters. Based on the pre-design testing
results, an Operations and Maintenance Plan will be prepared for
EPA's approval in consultation with DNREC.
53
flR30872
-------
9.0 STATUTORY DETERMINATIONS
EPA's primary responsibility at Superfund sites is to undertake
remedial actions that are protective of human health and the
environment. In addition, § 121 (b) of CERCLA, 42 U.S.C. § 9621,
establishes several other statutory requirements and preferences.
These requirements specify that when complete, the selected
remedial action for each site must comply with applicable or
relevant and appropriate ("ARARs") environmental standards
established under federal and state environmental laws unless a
statutory waiver is invoked. The selected remedy also must be
cost effective and utilize treatment technologies to the maximum
extent practicable. Finally, the statute includes a preference
for remedies that permanently and significantly reduce the
volume, toxicity or mobility of hazardous substances. The
following sections discuss how the selected remedy for this Site
meets these statutory requirements.
9.1 Protection of Human Health and the Environment
Ground Water
The selected interim remedy for ground water protects human
health and .the environment by controlling exposure to
contaminated ground water associated with the Site. Ground water
containment will prevent further migration of contamination from
the Site to the unnamed tributary to Red Lion Creek and Red Lion
Creek. Recovery of DNAPLs will reduce and/or eliminate a
principal threat by removing a continuing source of
contamination.
Institutional.controls, which provide for the establishment of a
ground water management zone and deed restrictions, will prevent
future exposure to contaminated ground water and subsurface soils
by prohibiting the future installation of wells in the
contaminated aquifer and shall identify the areas containing
subsurface contaminated soils. Air emissions produced by the
treatment of ground water will either be treated in the existing
plant boilers or other appropriate equipment (approved by EPA in
consultation with DNREC). Any residual waste generated as a
result of air treatment will be shipped off-site to a treatment
or disposal facility approved by EPA. Treated ground water will
be discharged to the Delaware River in accordance with the Clean
Water Act and NPDES requirements. This interim remedy will be
protective of human health and the environment while additional
information is collected for EPA to make a final decision
regarding ground water remediation in a subsequent ROD.
54
AR308722
-------
Soils and Sediments
The selected remedy and the contingency remedy for soils and
sediments protect human health and the environment by eliminating
direct contact with contaminants in the soils and sediments by
treating the contaminated soils and sediments to health-based
numbers. The railroad track area and Catch Basin #1 will be
capped to minimize infiltration and reduce the migration of
contaminated subsurface soils (greater than 15 feet in the area
adjacent to Gatch Basin #1). Catch Basin #1 will be physically
tested on a periodic basis (not less than once a year) to ensure
that it does not serve as .a continuing source of contamination to
the ground water.
Air emissions which might be produced by either the selected
remedy, or the contingency remedy will be captured by air
pollution control equipment. Ecological monitoring of the Red
Lion Creek will ensure that the selected remedy is protective of
the environment. Through monitoring, institutional controls and
treatment, this remedy will be protective of human health and the
environment during and upon completion of the remedial action.
It should be noted that the scope of the selected remedy was
designed primarily to address the impacts associated with the
spills which occurred in 1981 and 1986. As noted in Section 4.2
Final Action - Soils/Sediments, this remedy does not address any
potential risk associated with the ongoing day-to-day operations
at the SCD manufacturing facility.
9.2 Compliance with Applicable or Relevant and Appropriate
Requirements (ARARs)
Ground Water
EPA is selecting an interim remedy for the containment and
treatment of ground water; and containment and source removal of
known or identified DNAPLs. As part of the interim remedy, work
will be conducted to reduce the migration of the plume and data
will be gathered to determine the technical practicability of
remediating ground water to state and federal standards that are
potentially ARARs. Since the remedy for ground water is an
interim remedy, the standards for drinking water are not
applicable at this time and will be evaluated in a subsequent
ROD. The ground water containment system will be constructed to
comply with the ARARs listed in Table 10.
Soils and Sediments . .
The selected remedy and the contingency remedy shall attain all
action, location, and chemical-specific applicable or relevant
and appropriate requirements for the Site which are listed in
Table 10. Also included in the table are criteria, advisories or
55
4R308723
-------
guidance to be considered ("TBCs") for implementation of this
remedy.
9.3 Cost Effectiveness
Ground Water and Soils/Sediments
The interim remedy component is the same for both the selected
remedy and the contingency remedy. The NCP requires EPA to
evaluate cost-effectiveness by first determining if the
alternative satisfies the threshold criteria: protection of human
health and the environment and compliance with ARARs. The
effectiveness of the alternative is then determined by evaluating
the following three of the five balancing criteria: long-term
effectiveness and permanence, reduction of toxicity, mobility, or
volume through treatment, and short-term effectiveness. The
selected remedy meets these criteria and is cost-effective
because the costs are proportional to its overall effectiveness.
The estimated present worth cost range for the selected remedy is
$6.6 to $12.2 million. In the event that the selected remedy is
not effective in remediating the soils and .sediments to the
clean-up criteria, than the contingency remedy will be
implemented at a present worth cost of $17.06 million.
The interim remedy for ground water 'and the selected remedy and
the contingency remedy for soils and sediments are cost effective
in mitigating the risks posed by the contaminants associated with
the Site, they meet all other requirements of CERCLA, and afford
overall effectiveness proportionate to costs.
9.4 Utilization of Permanent Solutions and Alternative Treatment
Technologies to the Maximum Extent Practicable
Ground Water
The interim remedy for ground water consists of a containment
system and a pump and treat system. The treatment of extracted
ground water represents permanent treatment of the contaminants.
Removal of subsurface DNAPLs represents a permanent solution in
eliminating a potential continuing source of ground water
contamination. Additional investigation and evaluation is
required to determine the practicability of restoring the
contaminated ground water to health-based standards which would
be a permanent solution.
Soils/Sediments
EPA has determined that the selected remedy satisfies the
statutory preference for treatment as a principal element and
represents the maximum extent to which permanent solutions and
treatment technologies can be utilized in a cost-effective manner
56
-------
for remediation of the Site. This is accomplished by treating
all contaminated soils and sediments to health-based numbers.
Although the process of bioremediation has been utilized for
decades in the field of wastewater engineering, its application
to soils and sediments .at hazardous waste sites is new and still
undergoing intensive development. Of those alternatives that are
protective of human health and the environment and comply with
ARARs, EPA has determined that the selected remedy provides the
best balance of tradeoffs in terms of long-term effectiveness and
permanence, reduction in toxicity, mobility, or volume through
treatment, short-term effectiveness, implementability, and cost,
while also considering the statutory preference for treatment as
a principal element and considering state and community
acceptance. The contingency remedy also fulfills the requirement
of using permanent solutions and alternative treatment
technologies to the maximum extent practicable.
9.5 Preference for Treatment as a Principal Element
Ground Water
The .treatment of extracted ground, water is a major component of
the remedy. The containment of ground water and recovery of
DNAPLs is an interim remedy while additional information is
collected and evaluated to determine the feasibility of restoring.
ground water to drinking water standards.
Soils/Sediments
The selected remedy and the contingency remedy use treatment to
address the threats posed by contaminants in the soils and
sediments at the Site. This preference for treatment as a
principal element is satisfied since treatment of chlorinated
benzene compounds are the principal elements of either remedy.
10.0 Documentation of Significant Changes
The following changes have been made since the Proposed Plan was
issued on April 4, 1994:
1. EPA will require that all treated soils/sediments be .
sampled for TCLP analysis prior to being used as backfill
material to verify that the treated soils are not a
characteristic hazardous waste.
2. EPA received comments during the public comment period
concerning possible spills and releases of hazardous
materials at the SCD Site that may not have been properly
remediated or addressed. Based on this information, EPA
.57
flR308725
-------
will now require "Hot Spot" sampling and analysis as part
of the selected remedy. Spill areas that were identified
during the Remedial Investigation will be investigated.
Other areas that may be included in the "Hot Spot"
analysis are other areas or units where hazardous material
may have been placed or temporarily stored based on
present and past operations.
58
4R308726
-------
RED LION CREEK I
STANDARD CHLORINE
OF DELAWARE
OCCIDENTAL
CHEMICAL
COMPANY
GOVNEROR LEA ROAD
STAR
ENTERPRISES
INC.
CvJ
r^
CO
CD
CO
cc.
STANDARD
CHLORINE
OF DELAW/
FIGURE 1
SITE LOCATION MAP
-------
SCO
FACILITY
BOUNDARY
1981 REUASE LOCATION
MOTION OF ruw
SCO FAOUIY BOUNDARY
FIGURE 2 1961 RELEASE fLOW PATHWAYS
STANDARD CJiLO^INK OF DELAWARE. INC
DELAWARE C;TY. DELAWARE
-------
CO
CD
CO
SCO
FACIUIY
BOUNDARY
AIR
PRODUCTS
FACILITY
1M0 RELEASE LOCMWN
MEC1MN OF FLOW
SCO FAOUTY BOUMMRT
0 200 400
SCA1£ H fttl
FIGURE 3 1986 RELEASE F)X>W PATHWAYS
STANDARD CHLORINE OF DELAWARE. INC
DELAWARE CITY. DELAWARE
-------
SEDIMENTS ACCESSIBLE
FROM SHORELINE
SEDIMENTS IN
WETLANDS
SOIL PILES )
DRAINAGE / f/v) ^
DITCH / / V ^
WESTERN
DRAINAGE
GULLEY
EFFLUENT
PIPELINE
RAILROAD
TRACK
AREA i
200 400 600 BOO
| | |
SCALE IN FEET
FIGURE 4
RI/FS AREAS EVALUATED
STANDARD CHLORINE OF DELAWARE, INC
DELAWARE CITY, DELAWARE
flR308730
-------
ss-s Sol Sanpto Locator)
3-Sampte Nwntar
Total ConomMton (mota) «* SCO
1961 RELEASE
FIGURES
-------
. T«M ConoMMkn Inntitf of SCO
Analvud Par«iMtara
STANDARD CMLOMNE Of DELAWARE, MC.
-------
UpeJ
-------
SodmwrH Sample Location
SO Sednwni Sample
(Initial Rl Activity) Red Lion Creek Bed
SED Sediment Sample
(Supplemental HI Adwty) Wetland Area
SSC Snfcnent To>iC9ly Test Screening
Sjixu* (Supptomenial HI Aetwry)
i
SOI :»«lmeni Io»ory Test Sample
iSuppteinonul Rl ActMty)
Had ton Greek Bed
SSL) Stxfmenl Sample (Supplemental Rl Activity)
aodUon Creek Bed
CS) Total Concentrations (m0K0) ol
SCO Analyzed Parameters
SCO
FIGURE 8
-------
APPROXIMATE. LIMIT OF
PROBABLE DNAPL
m> ncoovtiy w»«
on Sui EnMipiH* w.«
4 wr W.I Port
l»conc*Miilion Cootou tin*
<00 and Tail CoflEwwmon Imtfl)
o> SCO An*Vi*tf Pw
tmnvvn (avl) ft»«« « OalnUi MM
coHctKi«*n«« w
O1NOTE: DRAWING REVISED BY STANDARD CHLORINE OF
DELAWARE, INC. TO SHOW APPROXIMATE LIMIT
OF PROBABLE DNAPL.
RQURE9
-------
WMwdOrineaton Survey PoW
AR308736
FIGURE 10
WETLAND DEUNEATION
-------
CONSOLIDATE/IN SITU
STABILIZE/CAP
REMOVE/CONSOLIDATE
SUBSURFACE SOL
REMOVAL AND CAP
WHERE APPROPRIATE
SCALE M FEET
CCJ.N.P
EXISTING CROUNOWATER
EXTRACTION WEILS
MMOVr/CONSttJOATC/CAr
PROPOSED PRODUCT
RECOVERY WELLS
SUKUVACt
SML KMOVAL
I. ALL DIMENSIONS ARE
APPROXIMATE
2. LOCATION AND NUMBER OF NEW
CROJNDWATER EXTRACTION AND
PRODUCT RECOVERY WELLS IS
PRESENTED ON A CONCEPTUAL
BASIS ONLY.
ALTERNATIVE 2 - CONCEPTUAL LAYOUT OF
PROPOSED REMEDIAL ACTIONS
STANDARD CHLORINE OP DELAWARE. INC
DELAWARE CITY. DELAWARE
-------
MVKMKMKXKMMMjMM
KACILITY BOUNDARY
NOTE:
ALL DIMENSIONS ARE
APPROXIMATE.
0 200 400
ALTERNATIVES 3 - 4A - 6 - INSITU BIOREMECNATE
ALTERNATE 46 - REMOVE AND THERMALLY TREAT
ALTERNATIVE S* - REMOVE AND BIOLOGICALLY TREAT
CO
CO
ALTERNATIVE 3 - REMOVE AND STABIUZf/SOUDIfY IN BASIN
'ALTERNATIVES 4A * B - REMOVE AND THERMALLY TREAT
ALTERNATIVES SA - 6 - REMOVE AND BIOLOGICALLY TREAT
SCALE IN FEET
30
PROPOSED REMED.AL ACTIONS IN WETLANDS
STANDARD CHLORINE OF DELAWARE. INC.
DELAWARE CITY. DELAWARE
FIGURE 12
-------
400
ro
CO
o
CO
J
CO
STABILIZATION/
SOLIDIFICATION
AREA
SUBSURFACE
REMOVAL WHERE
tffMffOUf.
PRODUCT RECOVERY WELLS
2. LOCATION AND NUMBER OF NEW
CROUNOWMER EXTRACTION AND
PRODUCT RECOVERY WELLS IS
PRESENTED ON A CONCEPTUAL
BASIS ONLY.
3. REMEDIAL ACTIONS IN WETLANDS
DEPICTED IN FIGURE 0.
ALTERNATIVE 3 - CONCEPTUAL LAYOUT Of
PROPOSED REUtOIAL ACTIONS
STANDARD CHLORINE OK DELAWARE. INC
DELAWARE CITY, DELAWARE
FIGURE 11
-------
RED UON CREEK
£»
3D
CO
O
CD
J
INTERCEPTOR
TRENCH
TO GROUNDWATtR
TREATMENT SYSTEM
FACILITY BOUNDARY
MIX XX M X M MIX M MKMMIMMMM
OQQQ
200
SCALE IN FEET
400
APPROXIMATE MANHOLE
LOCATIONS
APPROXIMATE SUMP
LOCAflONS
1. ALL DIMENSIONS ARE
APPROXIMATE
2. LO«>TION AND LAYOUT OF INTERCEPTOR TRENCH/PHYSICAL
BARRIER IS DEPICTED O.M CONCEPTUAL BASIS. DESIGN
OF INTERCEPTOR TRENCH/PHYSICAL BARRIER TO BE
PREFORMED DURING REMEDIAL DESIGN.
ALTERNATIVES 3 - 4A - 4B - 6A - 8
CONCEPTUAL IHTKRCEFTOR TKENCH/PHYSICAL
BARRIER LOCATION
STANDARD CHLORINE OF CKUWARK. INC
DKUfiRK Ctn. OKUttRK
FIGURE 13
-------
400
REMOVE/IREAT/BACKflU.
EXISTING CROUNONATER
EXTRACTION HELLS
(OPTIONS A * B)
PRODUCT RECOVERY WELLS
(OPTION A AND B)
REMOVE/TREAT/ASPHALT
ALL DIMENSIONS ARE
APPROXIMATE
J. IOCATWN OF PRODUCT RECOVERY
WELLS PRESENTED ON A
CONCEPTUAL BASIS ONLY.
REMEDIAL ACTIVITIES M WETLANO
AREAS ARE OEPtCTED ON fK. I
4. BIOLOGICAL TREATMENT UMT MLL
REPLACE THE THERMAL OESORPTUN
LWT TOR ALTERNATIVE M AND/OR «.
ALTBVMTME6
PROPOSED REUEDIAL ACTIONS.
STANDARD CHLORINE OP DELAWARE. INC
DELAWARE CITY. DELAWARE
FIGURE 16
-------
REMOVE AND TREAT
ftEMOVE/TREAT/BACKFIU.
SUBSURFACE SOIL
REMOVAL WHERE
APPMPMATC
REMOVE/TREAT/
BACKFILL
RCMOVE/TREAl/ASPHALT CAP
BACKrUl
EXISTING CROUNDWATER
EXTRACTION NELLS
(OPTIONS A * B)
PRODUCT RECOVERY WEUS
(OPIKW A AND B)
NOTES:
I. ALL DIMENSIONS AXE
APPROXIMATE
LOCATION OF PRODUCT RECOVERY
NELLS PRESENTED ON A
CONCEPTUAL BASIS ONLY.
1 REMEDIAL ACTIVITIES M WETLAND
AREAS ARE DEPICTED ON FK.
4. BIOLOGICAL TREATMENT UMT WLL
REPLACE THE THERMAL OCSORPTUN
UMT FOR ALTERNATIVE W AND/OR I.
ALTERNATIVES 4A - 4B - 6A
PROPOSED REUEDIAL ACTIONS.
STANDARD CHLORINE OF DELAWARE. INC
DELAWARE CITY. DELAWARE
FIGURE lii
-------
TABIE1
Descriptive Statistics for Chemicals of Concern in On-site Surface Soils
(mg/kg)
P- ----.-«- ..-
UolliCiCIa
Benzene
Chlorobenzene
1.3-Dichlorobenzene
1 ,2-Dichlorobenzene
1 ,4-Dichlorobenzene
Bthylbenzene
Toluene
1 ,3.5-Trichlorobenzene
1,2.4-Trichlorobenzene
1 .2,3 Trichlorobenzene
1,2,4,5 Telrachlorobenzene
1 ,2,3.4-Telrachlorobenzene
Pentachlorobenzene
Hexachlorobenzene
Nitrobenzene
Meiachloroniuobenzene
PCBs
Aroctor 1016
Aroc lor 1221
Aroclor-1232
Aroctoc-1242
Aroc tor- 1248
Aroclor 1254
Aroc lor 1260
Frequency
of
Detection
5-56
31-56
21-58
33-58
42-58
0-56
3-56
41-59
41-42
51-52
52-54
47-47
49-51
41-59
15-59
9-58
0-6
0-6
04
0-6
0-6
0-6
06
Range of Method
Detection
Limits
0.005-2
0.005-3
0.010-3
0.0103
0.0103
0.005-2
0.005-2
0.050-5
0.010-5
0.050-5
0.0505
0.050-5
0.050-5
0.010-5
0.010-10
0.150-15
0.000-0
0.0000
0.000-0
0.000-0
0.000-0
0.000-0
0.000-0
Range of
Delected
Concentrations
0.040-270
0.034-3300
0.038-600
0.041-13000
0.035-41000
0.000-0
0.002-69
0.062-29
0.048-6288
0.039-1809
0.040-232
0.058-869
0.042-921
0.347-14
0.144-22
0.225-4
0.000-0
0.000 0
0.000-0
0.0000
0.000-0
0.0000
0.000-0
Arithmetic
Mean
Concentrations
8
181
38
470
3,053
ND
1
2
293
122
41
138
103
1
1
0.443
ND
ND
ND
ND
ND
ND
ND
Standard
Deviation
42
572
124
1.914
8,638
ND
10
6
1,078
323
55
258
185
3
4
1
ND
ND
ND
ND
ND
ND
ND
Upper 95%
CoocenUAlions
18
320
68
934
5,148
ND
4
4
603
204
54
205
149
2
2
0.734
ND
ND
ND
ND
ND
ND
ND
30
CO
CD
CO
^vj
-c-
co
ND - Nol Delected
-------
TABLE 2
Descriptive Statistics for Chemicals of Concern in Off-site Surface Soils
(mg/kg)
Parameters
Benzene
Chtorobenzene
1,3-Dichlorobenzene
U-Dichlorobenzene
1 ,4-Dichkwobenzene
Cthylbenzene
Toluene
1,3,5-Trichlorobenzene
1 ,2.4-Trichlorobenzcne
1 ,2,3-IYichlorobenzene
1 .2.4.5-Tetrachlorobenzene
1 ,2,3.4-TeirachkHobenzene
Penlachlorobenzene
Hexachtorobenzene
Nitrobenzene
Meiachloronilrobenzene
PCBs
Aroclor-1016
Aroclor-1221
Aroc lor 1232
Aroclor-1242
Aroclor-1248
Aroclor-1254
Aroctor-1260
Frequency
of
Detection
3-50
33-49
35-50
40-50
42-49
0-50
12-50
36-47
28-31
42-46
36-40
42-45
44-47
20-50
6-48
3-50
0-0
0-4
0-4
0-4
0-4
0-4
0-4
0-4
Range of Method
Detection
Limits
0.005-0.02
0005-0.03
0.010-0.03
0.010-0.03
0.010-0.03
0.005-0.02
0.005-0.02
0.050-0.37
0010-0.05
0.050-0.37
0.050-0.37
0.0504.37
0.050-0.37
0.010-0.05
0.010-0.10
0.150-0.37
0.00012-0.00012
0.00012-0.00012
0.00012-0.00012
0.00012-0.00012
0.00012-0.00012
0.00024-0.00024
0.00024-0.00024
Range of
Delected
Concentrations
0.036-170
0.003-5600
0.004-2600
0.005-10000
0007-59000
0.0000
0.002-170
0.004-31.5
0.064-6100
0.017-1250
0.009-994
0.020-959
0.005-772
0.002-39.2
0.621-4.39
0.247-1.05
00
00
04)
00
00
0-0
0-0
Arithmetic
Mean
Concentrations
4
228
97
423
2,3%
ND
4
2
298
88
80
73
48
1
0.349
0.124
ND
ND
ND
ND
ND
ND
ND
Standatd
Deviation
2o
890
407
1,58*
9.391
ND
16
5
l;200
252
221
210
129
6
0.925
0.189
ND
ND
ND
ND
ND
ND
Upper 95%
Concentrations
11
461
203
833
4,832
ND
8
3
700
156
144
131
84
3
0.598
0.173
ND
ND
ND
ND
ND
ND
ND ; ND
CO
CD
CO
ND-Not Detected
-------
TABLE 4
Exposure Scenarios and Potential Exposure Routes
Current Worker
Incidental soil ingesdon
Dermal absorption from soil
Inhalation of airborne soil
Current Visitor
Incidental soil ingesdon
Dermal absorption from soil
Inhalation of airborne soil
Future Worker
Incidental soil ingesdon
Dermal absorption from soil
Inhalation of airborne soil
Ingestion of groundwater
future Visitor
Incidental soil ingesdon
Dermal absorption from soil
Inhalation of airborne soil
Ingestion of groundwater
Current Hunter/Fisherman
Incidental soil ingestion
Dermal absorption from soil
Inhalation of airborne soil
Ingestion of fish
Dermal absorption from surface water
Dermal contact with sediment
-------
TABLES
Descriptive Statistics far Chemicals of Concern in Off-site Sediments
(mg/kg)
Pinmelers
Benzene
Chtorobenzene
1 ,3-Dichlorobenzene
1,2-Dichlorobenzene
1 .4-DichkHobenzene
Elhylbenzene
Toluene
1 J.S-Trichlorobenzene
1 ,2,4-Trichlorobenzene
1 ,2.3-Trichlorobenzene
1 ,2,4,5-TetrachloiDbenzene
1 .2.3.4-Tetrachlorobenzene
Peniachlorobenzene
Hexachlorobenzene
Nitrobenzene
Meiachloroniuobenzene
PCBs
Aroclor-1016
Aroctor 1221
Arockx-1232
Aroclor-1242
Aroclor-1248
Aroclor-1254
Aroclor-1260
frequency
of
Detection
30-121
72-120
43-121
57-121
78-120
4-121
33-121
71-121
87-91
99-109
101-118
104-111
92-110
48-122
62-122
18-122
0-0
0-10
0-10
0-10
0-10
0-10
0-10
3-10
Range of Method
Detection
Limits
0.005-0.02
0.005-0.03
0.010-0.03
0.010-0.03
0.010-0.03
0.005-0.02
0.0050.02
0.050-0.37
0.010-0.05
0.050-0.37
0.050^.37
0.050-0.37
0.050-0.37
0.010-0.05
0.010-0.10
0.150-0.37
0.00012-0.00012
0.00012-0.00012
0.00012-0.00012
0.00012-0.00012
0.00012-0.00012
0.00024-0.00024
0.00024-0.00024
Range of
Delected
Concentrations
0.029-200
0.004-4700
0.005-2900
0.007-4700
0.009-160000
0.170-1200
0.031- 1100
0.013-10
0.058-760
0.018-827
0.024-1%
0.040-1030
0.011-573
0.002-2.14
0.070-27
0.016-3
0-0
0-0
00
0-0
00
0-0
0.110-0.32
Arithmetic
Mean
Concentrations
7
113
32
90
3,846
11
13
0.436
20
23
7
22
13
0.136
0.955
0.178
ND
ND
ND
ND
ND
ND
0.056
S-andard
Deviation
28
u 375
280
492
18,276
117
108
1
104
96
24
108
61
0.290
3
0.382
ND
ND
ND
ND
ND
ND
0.107
Upper 95%
Concentrations
12
174
77
169
6,779
30
31
0.609
39
39
II
40
24
0.182
1
0.239
ND
ND
ND
ND
ND
ND
0.134
CO
O
CO
*-»J
-e'-
en
ND - Not Delected
-------
TABLES
SUMMARY OF CARCINOGENIC RISKS1
tXKKUK£ 3OLNAHO8
Sod Ingestion
Soil Dermal Contact
Soil Oust ingesoon
. Ground Water Ingestion
Fisn ingsstion
Surface Wataf Derma) Contact
Sediment Derma) Contact
TOTAL F6K*
Current worxer
2.I3E-09
i.OOE-04
t.TTE-07
NA* '
NA
NA
NA
12E04
HOI3
-------
TABLE 7
SUMMARY OF ANALYTICAL RESULTS
FISH SAMPLING
Simple Location
FhhType
Analyied Portion
Sample Type
Matrix
UnlU
Laboratory
ParamttC^
BMICIW
CMorobenttM
13-DkfckrotMfiieite
12-Dkhlorobaitciic
14-DkhlorolMnitnc
Ethlylwmene
TalMiw
l3$-TrkhlorobtniCTM
124-TricMorobeniem-
113-TrichlorofctMittt
1245-TelnuMorobenttiK
1234-TelrachlorobtitttBC
PeBlarhlorobeniene
MeiarMorbbrniriie
Nllrobmtrnr
MrUcMonmllrobtnicne
Aroclor-1016
TOTALS
Arodor-1221
Arodor-1232
Arodor-1242
Arorior-124S
Aroclor-1254
Arodor-lttO
Rte 9 Bridge
Area
C*lfl*
wfww Bowy
Nomul
FISH
Mg/fcg
WESTON
ND
0.15
NO
NO
0.64 J
NO
NP
ND
0.61 1
NO
ND
ND
ND
ND
NO
ND
ND
1.4
ND
ND
ND
ND
ND
0.61 J
Rle 9 Bridge
Art*
Catfish
FUM
Normal
FISH
mg/kg
WESTON
ND
ND
ND
ND
ND
NO
ND
ND
0.27 *
ND
ND
ND
NO
ND
ND
ND
ND
0.27
ND
NO
ND
ND
ND
0.25 )
Rle 9 Bridge
Am
Simfbli
Whole Body
Nom»l
FISH
"flf
WESTON
ND
0.022
ND
ND
ND
ND
ND
ND
0.17 J
ND
ND
ND
ND
ND
ND
ND
ND
0.19
ND
ND
ND
ND
ND
0.3 J
Rlr 9 Bridge
Area
Swifbk
Whole Body
Dap
FISH
MCftl
WESTON
ND
0.035
ND
ND
ND
ND
ND
ND
0.21 J
ND
NO
NO
ND
ND
ND
ND
ND
0.25
ND
ND
ND
ND
ND
0.32 J
Rle 9 Bridge
Are*
Cnpple
FUlel
Normil
FISH
mc/fcf
WESTON
ND
0.006
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
0.01
ND
ND
ND
ND
ND
ND
Rle 13 Bridge
. Are*
Catfish
Whole Body
Norntil
FISH
me/ten
WESTON
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
0.00
ND
ND
ND
ND
ND
0.96 J
Rle 13 Bridge
Are*
Citflib
FIBel
Normal
FISH
nigAg
WESTON
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
0.00
ND
ND
ND
ND
ND
0.36 J
Rle 13 Bridge
Art*
[_ SiLiflih
Whole Hod;
Normal
risn
»B"<*
WESTON
ND
ND
ND
ND
ND
ND
ND
ND
ND
Nl)
ND
ND
ND
ND
ND
ND
ND
o.OO
ND
Nf»
ND
ND
ND
0.3 J
Rle 13 Bridge
Area
Cnppk
Flflrt
Normal
FISH
mg/kg
WESTON
ND
ND
ND
ND
NO
ND
ND
ND
ND
ND
ND
Nl)
ND
ND
ND
ND
ND
0.00
Nl)
ND
ND
ND
ND
Nl)
WESTON - Roy F. Westoa. Inc.
Dup - Field duplicate sample.
ND Not delected above detection limit.
J - EMinuled below detection limit.
CO
CD
CO
CO
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TABl£8
EPA Anaytical Data
March 1990 Fish Sampling Event
Red Lion Green
Parameters
Methylene Chloride
Acetone
Carbon disulfide
Benzene
Toluene
Chioro benzene
1,3 Dichlorobenzene
1 ,4 Dichlorobenzene
1,2 Dichlorobenzene
Isophorone
1,2,4 Trichlorobenzene
Bis(2-Ethylhexyl)phthalate
4,4-DDE
Aroclor- 1,200
Barium
Calcium
Copper
Iron
Lead
Magnesium
Manganese
Mercury
Potassium
Selenium
Sodium
Zinc
Units
. ug/Kg
ug/Kg
ug/Kg
ug/Kg
ug/Kg
ug/Kg
ug/Kg
ug/Kg
ug/Kg
ug/Kg
ug/Kg
ug/Kg
ug/Kg
ug/Kg
mg/Kg
mg/Kg
mg/Kg
mg/Kg
mg/Kg
mg/Kg
mg/Kg
mg/Kg
mg/Kg
mg/Kg
mg/Kg
mg/Kg
Carp Fillet Identification
F-l
51
240
24
95
10
870
660
4,000
3,100
370
7,100
450
1,700
4,700
1.7
2,100
6.6
99.9
7.2
1,320
3.3
2.7
19,600
10.8
1,690
35.1
F-2
65 .
870
130
*
*
*
*
*
*
*
*
620
*
*
2.6
4,240
1.8
31.4
1.2
1,500
5.9
0.97
19,000
4.7
1,980
37.4
* Analyte not detected.
-------
TABLE 9
SUMMARY Or ALTERNATIVES
«*«
W0M
W«*»f
AtTHVMTWEl
*>**»
.
NoAcMon
M.1BMMHE*
- RMMM McWy «oo^W», M0M|r
oontvnlnMjHKf MJ(tK0i ofe
- Comolkfcto *nd oonMn mmMd MM* ki
SMMMMkMy (In riM iMl«Ml ki b*Mn
bwMI inuMMcyw cap on MdfcMMtMVon bMln
AMU* cap ki ralkMd Imc* tnn tna atdi
bM*i
llMnow cnntnlMMi In ato iffNtfif, and
Un» gcMM-uni mlnj an FML In tac^wiid
MtmonftoflnQ
Otdlm»nt barrtom |tW tonoM, ggr»)j»t»
- ataMte^ottcHrv (to .ft* RMlwtate In bMln
^^w ttM^Hyk^rikn
StomoNkirino
Con*Ki» inMng ground *** *xnaHon «nd
MdMnMl vcMotton to i*duo» IhM Ma
Tuami* mlnfl liKiig « modin»d ground
«H
M.1BMMNE*
RMIKM* raMMy aooMtlM*. highly
contvnlraM wiMo* MM
- flMiWzWnlldlly <« ««u) mnoMd tuitoc* <)»
trw MtMfiwnttOon DMin
nwofMtnid dfiiMntalton bMln to Incfciov new
cap
- JUptM* cap In ra»Md tack and «*c«i bMki
Anno**, I mauttMi ibjMHnAolktIfy (w illii)
UM MMmMoM uring «i FML m ncmtMd
6At wonHoonQ
n»movi f»«cMty aconlbto MgMy
bow Mtton tM«to
- HMKW* iMtoiW* turn wdlmnMlon bMki to
m dki itaHMattan/MMMc^on
* HMOntVUCI MOMMflBBOn DMNt to fOCWOt nMV
«p
ContoNdfto itohHli»rtfri) »tHin»nli Into
nMonMmcted bMln
Bite moftftoring
- Cnhano* «dM(no ground ««*w nwxwwy «yflwn
lodud* UM of miMiOon IMNH md hydmufc
, f^viuct mxNwy ««
TfMlnMnt utlno «taUng or modM*d QroufxJ .
WMK tMtawnl ty*M (rif tklpplno)
M.1EHM1WE4
Wv^^___^^ T^^^^^^A ^^i4 IK l^k*
IIIBNIIV I^BBHBHi MnD ! «
nitara^TiMhim
MMM!MtfW2|
R*fflow iMdlly OMMlbl*. highly
coflbunlratKl witac* «o«»
llWIMptkMI
B*cMM ITMM Mm Into vtamtHl VM>
bMki
* SutfvOV VMlVf MMltfOM fWOVBSWy
Ml »*»m*nti of option A
Opjton A*
tecWHI ufaMJrfM* nKt
QppQnB:
-ANwmMnbiofOpttonA
IrwdtuttOMl control fdMd nNtricttorw)
- 8lto monHottnQ
- ki «ttu blorwiwcMallon of wiwlnlng MwUwxl
KDOWA Mtkdb WYWk
- RMtora dkturtMd mtlwKte
a»dlm«nt bvrtora M MOMuiy
M wpMto ol Option A with ttw «xotpdon
DA MnKMMd and ttMniHuly trMNvd,
ALTBVMYNEOA
P« ^Bfcl Mr III lt^ Ti^^b^wtf
R»mov« r*«dlV « ««lb<»,
highly oontwnlnat*d Mirfac« tollt
TnMt removed *ott» twJno M
BKWM trMtod oNt Into
xcavwxtftreM
ndcifcfctoHin
Surtio* MtH conbolt *»
RMIKN* coMolldM.
UDMNtaM »0llt
fMtrtctfom)
"
tfVMfllTMfll
AilHMAIMEfl
Biaw%iHhiHato^al
b« VMUxf wtth In «lbi
t*«m»dl«bon
-SNiinonloiIng
RMtoiv vny dMu rtMd wvttendv
wtth clown to Includ*
pUDMTwnt of top«*. dlnp.
and Mbj^ltohlng dlwrn*
SWIW M AllHIUMM 3
6*m* M AMnwdtM 2
AR308750
-------
TABLE 10
APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS (ARARs)
AND TO BE CONSIDERED MATERIAL (TBCs)
STANDARD CHLORINE SITE
ID
r^
CO
CD
CO
QC
act
ARARorTBC
L aiQMICALSPECIFIC
A. Water
1. Clean Water Act
2. Health Effects
Assessment
3. IJPA Health Advisories
4. Delaware
Comprehensive Water
ResourcesManagement
Committee Reports,
December 13, 1983
Legal rttfrinm
Clean Water Act, Section
303
EPA Office of Drinking
Water
ARAR
da*
Relevant
and
Appropriate
To be
considered
To be
considered
To be
considered
RnjniFCdicat Synopsis
Water quality criteria set at levels to protect human health
for water and fish ingestion and protection of aquatic life in
streams, lakes, and rivers.
Non-enforceable uxricity data for specific chemicals for use in
public health assessments. Also "to be considered" are
Carcinogenic Potency Factors and Reference Doses provided
in the Supertund Public Health Evaluation Manual.
Non-enforceable toxicity data for specific chemicals for use in
public health assessments. Also to be considered are
Carcinogenic Potency Factors and Reference Doses provided
in the Superfund Public Health Evaluation Manual.
The reports were adopted as policy by the DNREC
Secretary. Among these reports is the Groundwatcr Quality
Management Report, July 1983, which provided Delaware
with a number of tools for dealing with ground-water
contamination.
AHtoMfcy to
Selected Rowdy
Surface water in the wetlands and the Red Uon
Creek must attain these standards.
To be considered where remedial action addresses
risk-based criteria or when selling clean-up standards
for the protection of human health.
To be considered where remedial action addresses
risk-based criteria or when setting clean-up standards
for the protection of human health.
To be considered for ground-water monitoring.
-------
ARARorTBC
B. Air
1. Clean Air Act
a. National Emissions
Standards for
Hazardous Air
Pollutants
b. Stale of Delaware
Implementation Plans
for Attainment and
Maintenance of
National Ambient Air
Quality Standards
2. Delaware Ambient Air
Quality Standards
a LOCATION
SPECIFIC
1. Coastal Zone
Management Act of
1972;
Coastal Zone Act
Reauthorization
Amendments of 1990
2. The Archaeological
and Historical
Preservation Act of
1974
Legal dutfca
42 U.S.C | 7401
40 C.F.R Part 61
40 C.F.R Section 52,
420-460 Subpart I
Title 7, Delaware Code,
Ch 60, Regulation 3,
Section 6003
16 U.S.C. 14S1 et seq.
15 C.F.R. Part 930
16 U.S.C $ 469
ARAR
Oaas
Relevant
and
Appropriate
Relevant
and
Appropriate
Applicable
Applicable
Applicable
RcqidKSMt Sysnpaii
Standards promulgated for air emissions from specific source
categories. Not applicable but may be relevant and
appropriate for emissions from air strippers at Superfund
sites.
Sets forth (he Slate's Implementation Plan for Attainment of
Air Quality Standards.
Establishes ambient air quality standards.
Requires that Federal agencies conducting or supporting
activities directly affecting the coastal zone, conduct or
support those activities in a manner that is consistent with
the approved appropriate State coastal zone management
program. (See Delaware's Comprehensive Update and
Routine Program Implementation, March 1993)
Requirements relating to potential loss or destruction of
significant scientific, historical, or archaeological data
AnteMkylo
Selected Remedy
Relevant and appropriate for potential releases
resulting from soil/sediment and ground-water
treatment.
Applicable for potential release* from air stripping
of ground waler,excavatlon work,or other remedial
actions.
Applicable for potential releases from air stripping
of ground water, excavation work, or other remedial
actions.
Remedial actions are required to be consistent, to
the maximum extent practicable, with Delaware's
coastal zone management program. .EPA must notify
Delaware of its determination that the actions are
consistent to the maximum extent practicable.
Further action will be taken to identify resources
and, if identified, action will be taken to mitigate any
adverse effects on those resources that would result
from construction. If resources happen to be
identified in other areas (although no specific actions
will be taken to find), action will be taken to mitigate
any adverse effects on those resources that would
result from implementation of the remedial action.
Ox)
to
r-.
CO
CD
CO
cc
«cr
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ARARorlBC
3. Prelection of
Floodplains
4. Protection of Wetlands
5. Delaware Coastal
Zone Act, 7 Delaware
Code Chapter 70;
Coastal Zone Act
Regulations, 6/9/93
6. Delaware Wetlands
Kegulations Revised
June 29, 1984
7. Delaware Regulations
Governing the Use of
Subaqueous Lands,
amended September 2,
1992
8. Delaware Executive
Order 56 on
freshwater Wetlands .
(1988)
9. Governor's
Roundlable
Report on Freshwater
Wetlands (1989)
10. Ground Water
Protection
Strategy of 1984
Leg*l Citation
40 C.F.R. Part 6,
Appendix A
40 C.F.R. Part 6,
Appendix A
7 Delaware Code
Sections 7003, 7004
Sections 1, 2, 7
Sections 1, 3, 4
EPA 440/6-84-002
ARAR
dim
Applicable
Applicable
To be
considered
Applicable
Applicable
To.be
considered
To be
considered
To be
considered
Requiraaeot SyBopcfc
Sets forth EPA policy for carrying out provisions of
Executive Order 11988 (Floodplain Management) which
requires actions to avoid adverse effects, minimize potential
. harm, and restore and preserve natural and beneficial values.
Sets forth EPA policy for carrying out provisions of
Executive Order 11990 (Protection of Wetlands) which
requires actions to avoid advene effects, minimize potential
harm, and restore and preserve natural and beneficial values.
Controls the location, extent, and type of industrial
development in Delaware's coastal areas.
Requires activities that may adversely affect wetlands in
Delaware to be permitted. Permits must be approved by the
county or municipality having jurisdiction.
Requires activities that affect public or private subaqueous
lands in the State be permitted.
General policy to minimize the adverse effects to freshwater
wetlands.
General policy to minimize the adverse effects to freshwater
wetlands.
Identifies ground water quality to be achieved during
remedial actions based on aquifer characteristics and use.
AppfeaHtty to
Sdeetad Rowdy
Applicable since much of the remedial action will
take place within the 100-year floodptaln.
Applicable to any portion of the remedy which may
affect the wetlands.
Will be considered for consistency tince (he remedial
action is located in Delaware's coastal area.
Any substantive requirements shall be met since
wetlands may be dredged (or excavated) and
restored along the unnamed tributary. Since all of
the wetland remediation Is considered "on-t ite",
pursuant to Section 121 of CBRCLA, no permit will
be obtained.
Any substantive requirements shall be met since the
remediation may involve dredging or excavating of
the unnamed tributary. Since all of the wetland
remediation is considered "on-site", pursuant to
Section 121 of CERCLA, no permit will be obtained.
To be considered for wetland remediation and
restoration.
To be considered for wetland remediation and
restoration.
The EPA aquifer classification will be taken into
consideration during design and implementation of
the treatment remedy.
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CO
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net
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ARARorTBC
III ACTION SPECIFIC
A. MvcdUncous
1. Delaware Regulations
Governing Hazardous
Substance Cleanup,
1/93
B. Water
1. Clean Water Act
(CWA); National
Pollutant Discharge
Elimination System
Requirements
2. Stale of Delaware
Regulations Governing
the Construction of
Water Wells,
January 20, 1987
3. Delaware Water
Quality Standards, as
amended, February 26,
1993
4. Delaware River Basin
Commission (DRBC)
Water Quality
5. Delaware Regulations
Governing the
Allocation of Water
March 1, 1987
Legal Otatiaai
Section 9
40 C.F.R. Part 122-125
Sections 3, 4, 5, 6, 7, 8, 9,
10
Sections 3-6, 8-10, 11.1,
11.2, 11.3, 11.4, 11.6, 12
DRBC Ground Water
Protected Area
Regulation, No. 4, 6(f),
9, 10; Water Code of the
Basin, Sections 2.20.4,
2.50.2
Sections 1, 3, 5.05
ARAR
OSSB
Relevant
and
Appropriate
Applicable
Applicable
Applicable
Applicable
Applicable
Reqviresneal SyDopssj
Establishes clean-up criteria for hazardous waste sites.(lxlO'5;
Hazard Index of 1; or natural background if higher). Only
criteria considered relevant and appropriate are for soils and
sediment.
Enforceable standards for all discharges to waters of the
United Stales.
Contain requirements governing the location, design,
installation, use, disinfection, modification, repair, and
abandonment of all wells and associated pumping equipment.
Standards are established in order to regulate the discharge
into slate waters in order to maintain the integrity of the
water.
Regulate restoration, enhancement, and preservation of
waters in the Delaware River basin.
Contain information pertaining to water allocation permits
and criteria for their approval.
Appfcabislryto
1. Soils and sediments will be remediated to 1X10-6.
2. Will be considered during ground water
investigation.
Discharge limits shall be met for all on-«iie
discharges to surface water Including treated ground
water. If ground water treatment to provided by a
means other than the existing wastewater treatment
facility, only substantive requirements need by met
and no permit shall be obtained.
Installation of any monitoring and recovery wells and
the abandonment of wells shall meet all substantive
requirements.
Applicable should the ground-water treatment
system Involve discharge to surface water.
Applicable if remedial action Involves discharge of
> 50,000 gallons/day average over any month or a
withdrawal of ground water of 100,000 gallons/day or
more average over any month.
May be applicable for the ground-water recovery
system. No permit required.
LO
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in
AKARorlBC
6. Stale of Delaware
Groundwaler
Management Plan
November 1, 1987
7. Delaware Regulation!
Governing Control of
Water Pollution.
amended 6/23/83
CAlr
1. Control of Air
Emissions from Air
Strippers at Superfund
Ground Water
Sites, June IS, 1989
2. Delaware Regulations
Governing the Control
of Air Pollution
D. Sediments/Solids
1. Delaware Sediment
and Storrowaler
Regulations
January 23, 1991
E. Waste Handling and
Disposal
1. Delaware Regulations
Governing Solid Waste
Legal Citation
Section 7, 8, 9, 10, 11, 12,
13
EPA OSWER Directive
9355.0-28
Regulations Number 2,
19,24
Section 3, 6, 9, 10, 11,15
Sections 2, 5, 6
ARAR
CbM
To be
considered
Applicable
To be
considered
Applicable
Applicable
Relevant
and
Appropriate
Rcquheaient Synopsis
Policy for ground-water management.
Contain water quality regulations for discharges into surface
and ground water.
Policy to guide the selection of control* for air strippers at
groundwater sites according to the air quality status of the
site's location (i.e., ozone attainment or non-attainment area).
Sets forth the requirement that a permit is necessary to
operate an air stripper if emissions will exceed 2.5 IbsVday.
Section 2 describes general conditions. Section 19 deals with
odor. Section 24 deals with volatile organic compounds.
Establishes a statewide sediment and stormwater
management program.
Establishes regulations to implement an improved solid waste
management program.
Apptkabujty to
Scfacud RoMdy
To be considered in setting the ground water
management zone.
Applicable for discharge of treated ground water
into surface water. Abo applicable for itormwaier
runoff into the unnamed tributary and Red Lion
Creek.
To be considered in determining if air emissions
controls are necessary (or ao air stripper because
New Castle is in an ozone non-attainment area.
Sources most in need of controls are those with
emissions rates in excess of 3 IbsVhour or 15 IbsVday
or a potential rate of 10 tonstyear of total VOCs.
If emissions exceed 2.5 ItwYday then the substantive
requirements of the regulation must be met. In
addition, the emissions from the air stripper must
meet the Ambient Air Quality Standards set forth in
Regulation 3 of 7 Delaware Code, Chapter 60,
Section 6003.
A stormwater and sediment management plan
consistent with Delaware requirements must be
approved by Delaware before construction disturbing
over 5,000 square feet of land can begin.
May be relevant and appropriate for the residual
waste generated from the treatment of ground water,
.soils, and sediments.
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2. Delaware Regulations
Governing Hazardous
Wade
3. Resource Conservation
and Recovery Act of
1976; Hazardous and
Solid Waste
Amendments of 1984
4. Standards Applicable
to Generators of
Hazardous Waste
5. RCRA Requirements
for Use and
Management of
Containers
6. RCRA Requirements
for Tanks Systems
Legal Citation
SEE BELOW
E.4, E.5, E.6, E.7, B.8,
E.9, E.10, E.11, E.13,
E.14, E.15, E.16
SEE BELOW
E.4, E.5, E.6. E.7, E.8,
E.9, E.10, E.11, E.12,
E.13, E.14, E.1S, E.16
Federal RCRA
regulations would not
apply for those
regulations which
Delaware has the
authority from EPA to
administer.
Delaware Regulations
Governing Hazardous
Waste, (DRGHW) Part
262.10-58
EPA Regulations, 40
C.F.R Part 262.10-58
DRGHW Part 264.170-
178 EPA Regulations, 40
C.F.R Part 264.170-178
DRGHW Part 264.190-
199
EPA Regulations, 40
C.F.R Part 264.190-199
ARAR
OMI
SEE
BELOW
.SEE
BELOW
Applicable
Applicable
Applicable
Reqwrenenl Synoprii
Delaware Regulations Governing Hazardous Waste Part 261
define "hazardous waste". The regulations listed below apply
to the handling of such hazardous waste.
Regulates the management of hazardous waste, to ensure the
safe disposal of wastes, and to provide for resource recovery
from the environment by controlling hazardous wastes "from
cradle to grave."
Establishes standards for generators of hazardous wastes
including waste determination manifests and pre-transport
requirements.
Requirements for storage of hazardous waste in storage
containers.
Requirements for storage or treatment of hazardous waste in
tank systems.
ApptabiUtyto
Sdodcd RcMjd^r
SEE BELOW
SEE BELOW
Applicable to the wsitewater treatment plant and
residual waste generated by the treatment of soils &
sediments if the waste generated by the treatment
system(s) is a RCRA-hazardous waste.
Applicable for temporary storage containers and on-
site treatment systems.
Only applicable for onsite treatment systems and
temporary storage tanks containing hazardous waste.
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7. Standards for owners
and operators of
facilities thai store or
(real hazardous waste
in surface
impoundments
8. Standards Tor owners
and operators of
facilities that store or
treat hazardous waste
in waste piles
9. Standards for owners
or operators of
facilities that treat or
dispose of hazardous
waste in land
treatment units
10. Standards for owners
or operators of
facilities that treat or
dispose of hazardous
waste in incinerators
11. Standards for owners
or operators of
facilities that treat or
dispose of hazardous
waste in miscellaneous
units
12. Standards for owners
or operators of
facilities that treat or
dispose of hazardous
waste
Lend Cfutina
DRGHW Part 264.220-
231
EPA Regulations 40
C.F.R Subpart K
264.220-231
DRGHW Pan 264.250-
258
EPA Regulations, 40
C.F.R Subpart L
264.250-258
DRGHW Pan 264.270-
283
EPA Regulations, 40
C.F.R Subpart M-
264.270-283
DRGHW Pan 264.340-
351
EPA Regulations,
40 C.F.R Subpart O
264.340-351
DRGHW Pan 264.600-
603
EPA Regulations, 40
C.F.R Subpart X
264.600-603
EPA Regulations, 40
C.F.R Subpan AA
264.1030-1037
ARAR
dan
Applicable
Applicable
Applicable
Applicable
Applicable
Applicable
Requirement Sy»opsii
Requirements for storage or treatment of hazardous waste in
surface impoundments.
Requirements for storage or treatment of hazardous waste in
waste piles.
Requirements for storage or treatment of hazardous waste in
land treatment units
Requirements for storage or treatment of hazardous waste in
incinerators
Requirements for storage or treatment of hazardous waste in
miscellaneous units
Applies to process vents associated with air stripping
operations that manage hazardous wastes.
Applicability to
Selected Reaedy
(264.228 is applicable to the existing surface
impoundment.
(264.220-231 are applicable to any toil* and
sediments which are excavated and stored in a
surface impoundment prior to or during treatment.
(264.258 is applicable to the ensling soil pile*.
$264.250-258 are applicable to any soils and
sediments which are excavated and stored in waste
piles prior to, or during treatment.
Applicable to Exsitu bioremediation if a land
treatment unit is selected for the bioremediation
technology.
Applicable to low temperature thermal desorplion
of soils and sediments.
Applicable to low temperature thermal desorplion of
soils and sediments.
Applies to treatment of ground water in an air
stripper.
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ARARorTBC
13. The Hazardous Waste
Permit Program
14. Identification and
Listing of Hazardous
Wastes
IS. Standards Applicable
to transporters of
hazardous waste
16. RCRA Land Disposal
Restrictions
LenlCilatfiaB
DRGHW Pan 122
EPA Regulations, 40
C.F.R Part 270
DRGHW Pan 261
EPA Regulations, 40
C.F.R Pan 261
DRGHW Pan 263
EPA Regulations 40,
CF.R Part 263.10-31
DRGHW Part 268
EPA Regulations, 40
C.F.R Part 268
ARAR
OM
Applicable
Applicable
Applicable
Applicable
Requires a permit for the treatment, storage, or disposal of
any hazardous waste as identified or listed in Pan 261.
Identifies solid wastes which are regulated as hazardous
wastes.
Establishes standards for transportation of hazardous waste.
Restrictions on land disposal of hazardous wastes.
AntfaMttpto
Selected Reaedjr
Any substantive requirements will be met
But no permit will be required for on-tite activities.
Use to determine which materials must be managed
as a hazardous waste.
Applicable to residual waste generated by the
treatment of toils and sediment! and recovered
DNAPL.
Applicable for off -site land disposal of hazardous
waste generated from the treatment of groundwaler,
oils and sediments.
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STATE
OF NATURAL RESOURCES
ft ENVIRONMENT**. CONTROL
DIVISION OF AIR & WASTE MANAGEMENT
69 KIMGS HIGHWAY
P.O. Box 1<1O1
OJT«C£ OF THE OOVCB. OEIAVKMC 199O3 r*L*f*OMt: (3O2J 739.
OlRCCTOR
February 23, 1995
Peter H. Kostmayer (3RAOO) .
U.S. EPA, Region III
841 Chestnut Building
Philadelphia, Pennsylvania 19107
RE: State of Delaware Concurrence with Record of Decision
Standard Chlorine of Delaware, Inc. Superfund Site
Delaware City, New Castle County, Delaware
Dear Mr. Kostmayer:
The Department of Natural Resources and Environmental Control has
reviewed the February 1995 Record of Decision (ROD) for the
Standard Chlorine of Delaware, Inc. Superfund site. This
correspondence represents the Department's official concurrence
with the selected remedy described in the ROD for the Standard
Chlorine site. As you are aware, the Department has been actively
involved throughout the Superfund process as it pertains to this
site and plans to continue to do so.
Director
Division of Air and Waste Management
AVH:dw
AVH94123.wp
DE-053 II B-9
pc: N. V. Raman
Karl Kalbacher
Anne Killer
flR308803
FEB-24-1995 08:38 302 323 45S1 977. p. 02
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RESPONSIVENESS SUMMARY
STANDARD CHLORINE OF DELAWARE, INC.
DELAWARE CITY, NEW CASTLE COUNTY DELAWARE
The Responsiveness Summary documents public concerns and
cuimnents expressed during .the public comment period. The suuuuary
also provides EPA's response to those comments. The information
is organized as follows:
I. Overview
II. Background on Community Involvement
III. Summary of Comments and EPA Responses from:
(1) The Public Meeting
(2) Citizens
(3) Potentially Responsible Parties (PRPs)
Air Products
Occidental
Standard Chlorine of Delaware
(4) Natural Resource Trustees
National Oceanic and Atmospheric
Administration
Fish and Wildlife Service
I. OVERVIEW
A public comment period was held from April 4, 1994 through
May 4, 1994 to receive comments from the public on the Remedial
Investigation/Feasibility Study (RI/FS) Reports, the Proposed
Remedial Action Plan (PRAP), and EPA's preferred alternative for
the Standard Chlorine of Delaware Superfund Site. The public
comment period for written and oral comments on these documents
was" extended to June 6, 1994 due to a timely request from
Standard Chlorine. In a letter dated May 31, 1994 Standard
Chlorine of Delaware requested additional information from EPA as
well as an extension of time to provide comment on the PRAP. EPA
had no written documentation to respond to this additional
request and in turn EPA granted Standard Chlorine an extension to
June 8, 1994 to submit comments.
To facilitate commenting, EPA held a public meeting on April
AR308753
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27, 1994 in Carpenters Union Hall, 626 Wilmington Road, New
Castle, Delaware at 7:00 P.M. At the meeting, EPA discussed the
Remedial Investigation (RI), including the Risk Assessment (RA),
and the Feasibility Study (FS) Reports .which were developed for
the Site. EPA also presented the Proposed Plan for eliminating
and/or mitigating the public health and environmental threacs
nosed by the contamination detected in environmental media at the
Site.
At this meeting, EPA explained that the preferred
alternative consisted of two components: one for ground water and
the other for soils and sediments. The preferred alternative for
ground water is an interim remedy to contain ground water with a
physical barrier, such as a trench or slurry wall, to prevent it
from migrating to the Red Lion Creek. The preferred alternative
for soils and sediments is a final remedy which consists of
treating this contaminated media, either in situ or ex situ with
bioremediation technology. If bioremediation is unsuccessful in
treating the soils and sediments to the clean-up criteria, then
the soils and sediments would be excavated and treated with low
temperature thermal desorption.
The April 27, 1994 public meeting also provided the
opportunity for the public to ask questions and express opinions
and concerns. The comments and questions received at the public
meeting, along with EPA responses, are summarized in.Section III
of this document.
II. BACKGROUND ON COMMUNITY INVOLVEMENT
Community involvement at the site has been moderate
throughout the Superfund process. Interest has focused primarily
on issues of groundwater contamination and the safety of
consuming fish from Red Lion Creek. EPA initiated several
community involvement activities to obtain public input on
remedial activities at the Site. These activities included:
Development of a mailing list, which included
the addresses of residents who live within a 1/2 mile
radius of the site.
Opening the public comment period for the Proposed
Remedial Action Plan, April 4, 1994 to June 8, 1994.
Distribution a fact sheet which summarized EPA's
Proposed Remedial Action Plan.
Hosting a public meeting on the Proposed Remedial
Action Plan on April 27, 1994.
The public comment period was announced in the April 4,
2
4R308760
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1994 edition of the Wilmington News Journal and the April 7, 1994
edition of the New Castle Weekly. Following the announcements,
EPA mailed approximately 3000 copies of the fact sheet to
residents in the area which summarized the six alternatives that
addressed the long-term clean-up of the Site.
III. SUMMARY OF COMMENTS AND EPA'S RESPONSES
1. PUBLIC MEETING
Approximately 30 people attended the public meeting,
including residents, representatives from EPA, the State, and
industry. The meeting lasted two and one-half hours. As
discussed in Section I of this document, EPA presented an
overview of the Site, including a history of releases, findings
of the studies conducted to date, and the alternatives evaluated
for remediation, including EPA's preferred alternative.
Several residents asked questions for clarification of EPA's
presentation. These questions were answered at the meeting.
There were other questions and comments relating to health
effects posed by the Site, the quality of fish in the Red Lion
Creek and Delaware River, worker and residential exposure to
releases at the Site, and specific comments on EPA's recommended
alternative. These questions and comments are summarized later
in this Responsiveness Summary.
The primary concerns voiced by the citizens involve the
following:
The impact of the ground water contamination and the
proposed remedy on residential wells;
The quality of fish in Red Lion Creek and the Delaware River
and the need for proper posting of signs to inform the
public; . . .
Impact of dredging sediments on aquatic life in Red Lion
Creek and the Delaware River;
Overall industrial practices of Standard Chlorine resulting
in spills, worker exposure, and air releases impacting the
community;
The inability of bioremediation to treat the soils/sediments
to the clean-up criteria, the long-term .impact of
bioremediation, and the. time frame for remediation.
A copy of the public meeting transcript and letters
forwarded by citizens are located in the Administrative Record.
Questions and comments presented at the April 27, 1994 meeting
AR30876I
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are summarized briefly in this section and are grouped according
to subject. The EPA response follows each of the questions or
comments presented.
1.1 Comment
Two residents at the public meeting were concerned that the
conLamiiiated ground water at the SCD Site could migrate off-siLe
and contaminate private drinking wells. One resident identified
the location of her well in relationship to the Site.
EPA Response
EPA explained that the Remedial Investigation demonstrated
that the contamination of ground water is limited to the Columbia
aquifer. Typically, domestic or private wells in this area are
located in the Columbia aquifer. The water in the Columbia
aquifer at the SCD Site flows underneath the Standard Chlorine
Site to the Red Lion Creek. The private wells identified at the
meeting are not in the pathway of ground water flow from the Site
and therefore should not be impacted by any ground water
contamination at the Site.
EPA explained that although it is unlikely that the SCD Site
is impacting any private wells, there may be other sources of
contamination that could impact private wells. EPA recommended
that residents with concerns about the quality of their water
from private wells have their wells sampled and analyzed on a
periodic basis.
1.2 Comment
A few residents were concerned that the recommended remedial
alternative for ground .water would lower the water table and .
possibly dry up or deplete ground water necessary for the private
wells.
EPA's Response
EPA explained that the existing pump and treat system at the
Site would be maintained and would not impact private wells. The
existing pump and treat system was originally designed to prevent
ground water from entering the Red Lion Creek. The pumping rate
and capacity of the existing pump and treat system is too low and
too far removed from residential wells to dry up or deplete
ground water from private wells. The physical barrier that was
proposed as the interim remedy for ground water would contain
ground water and would minimize any ground water discharge into
Red Lion Creek, but would not impact any private wells.
fiR308762
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1.3 Comment
A few residents asked if it was safe to eat fish from Red
Lion Creek or the Delaware River in the area where Red Lion Creek
discharges into the Delaware River. One resident asked what the
impact of dredging of Red Lion Creek or the Delaware River would
have on the quality of fish.
EPA's Response
EPA explained that currently there is a hea-lth advisory in
effect warning the public not to consume fish from Red Lion
Creek. Samples of fish from the Delaware River were not
collected as part of the investigation at the Site. While there
is the possibility that contamination from the Standard. Chlorine
Site has migrated to the Delaware River, the level of
contamination would be lower than it is at the Site. It is worth
noting however, that there are many other sources.of
contamination contributing to the contamination of water,
sediments, and fish in the Delaware River including industrial
discharges and storm water run-off. While the Standard Chlorine
Site may be contributing somewhat to the contamination in the
Delaware, there are also other sources of contamination that may
pose a risk or make the fish unsafe to eat.
The remedy for the sediments in the wetland area may entail
excavation or dredging. Dredging of the sediments in the wetland
area will result in a temporary loss of habitat for aquatic life,
but the overall long-term impact will be beneficial for the
aquatic life.along the unnamed tributary to Red Lion Creek and
the Red Lion Creek itself by removing the source of
contamination. Controls will be required during the dredging
operations to minimize the release of particulate matter into Red
Lion Creek. EPA.is not requiring dredging of the Delaware River
as part of this Superfund Remedial Action.
1.4 .Comment
A few residents requested that signs be posted along Red
Lion Creek warning the public not to consume fish from Red Lion
Creek.
EPA' s Response
The State of Delaware determines the necessity of issuing
fish consumption health advisories through a formalized multi-
department review process. A health advisory may be publicized
in any of the following ways: legal notice in a newspaper of
statewide circulation and at least one local newspaper, a press
release, posting of signs by the Department of Health and Social
6R308763
-------
Services (DHSS) in. the waters from which the fish are limited for
consumption, publication in the annual Delaware Fishing Guide, or
other publications that may reach the angling public. The
purchase of an annual fishing license by freshwater fisherman is
required by the State of Delaware. A copy of the annual Delaware
Fishing Guide, containing the list of fish consumption
advisories, is given to each license purchaser.
The State of Delaware has publicized the advisory for Red
Lion Creek in a number of ways and intends to continue to
publicize the advisory for as long as it is in effect. Sign
posting in the common fishing area in Red Lion Creek has been
done in the past and will continue in the future.
1.5 Comment
A few residents asked who would pay for the clean-up and
who would conduct the clean-up. One resident implored that EPA
reconsider having Standard Chlorine take part in the clean-up.
EPA's Response
. EPA stated it would take appropriate steps to ensure that
the responsible parties would pay for the clean-up. If Standard
Chlorine or any of the other Potentially Responsible Parties
(PRPs) agree to perform the clean-up, they would retain an
established environmental consultant who would actually implement
the remedy under EPA's oversight. It is cost effective for
government and industry to have the responsible party (s) conduct
the remedial design and remedial action at a Superfund Site. All
work conducted by the consultant would be reviewed by EPA's
technical staff, an oversight contractor, and the State. EPA is
confident that if Standard Chlorine or any of the other PRPs were
to implement the selected remedy, sufficient controls would be in
place to ensure that the activities were conducted in accordance
with EPA's Record of .Decision, and other appropriate guidance on
remedial actions.
I.6 Comment
A Standard Chlorine employee read a statement at the
meeting. In summary, the employee expressed concerns that
Standard Chlorine continues to release contaminants into the
environment without notifying appropriate authorities. The
employee is also concerned that workers as well as residents are
exposed to.these chemicals. The employee requested that EPA
conduct a detailed inspection for leaking pipes and tanks.
-------
EPA's Response
In response to this comment, EPA has incorporated a
significant change in the ROD from the Proposed Plan which was
issued on April 4, 1994. The ROD contains a provision for area-
wide sampling and analysis of site soils to determine if
concentrated areas of contamination (hot spots) which require
remediation exist. If the resulcs of Lhe hot spot sampling and
analysis suggest that additional areas beyond those currently
identified in the ROD contain contamination above the .specified
clean-up criteria, there are a variety of federal enforcement
authorities which EPA might utilize to ensure that these areas
are properly addressed.
Following'the public meeting, EPA contacted the Occupational
Health and Safety Administration (OSHA) to arrange for an
inspection. EPA was informed that an OSHA inspection had been
conducted on March 8, 1994. At that time, OSHA found no
violation of its standards.
In January, 1995, Standard Chlorine participated in a
voluntary EPA chemical safety audit for the purpose of
identifying methods, procedures, etc. to minimize releases from
pipes, tanks, and associated equipment. In addition to the
hazardous'waste regulations, Standard Chlorine is subject to
water and air regulations which may entail periodic physical
inspections and record keeping review.
1.7 Comment
A few residents raised questions on the recommendation of
using bioremediation at the Site and requested information that
documents the effectiveness of bioremediation on soils
contaminated with chlorinated benzene compounds.
EPA's Response
Bioremediation, the process by which hazardous substances
are degraded by microorganisms, is an innovative technology which
has been selected, and is being considered, at many Superfund
sites around the country. An EPA Engineering Bulletin entitled
"In Situ Biodegradation Treatment" contains a table that lists
sites around the country where in situ bioremediation is eizher
in the process or planning stages. A copy of this document can
be found in the Administrative Record.
Various laboratory studies using different microorganisms,
demonstrated that 1,4-dichlorobenzene is amendable to. .
biodegradation. Copies of the articles which discuss these
flR308755
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studies and were published in professional journals are found in
the Administrative Record.
1.8 Comment
One resident objected to capping of any areas and requested
that EPA consider excavating all contaminated soils and sediments
for off-site disposal.
EPA's Response
The selected remedy entails capping of the railroad track
area if in situ bioremediation is unsuccessful in remediating the
contaminated soils.. EPA recognizes that Standard Chlorine is an
operating facility and that the railroad line is vital to the
production process, and in turn will not require the excavation
of soils in this area when there is another alternative that is
protective of human health and the environment.
The area around Catch Basin #1 will also be capped after
soils to a depth of 15 feet are excavated for treatment. The
subsurface soils in this area contain elevated levels of
chlorinated benzene compounds which will migrate downward over
time and eventually be captured by the physical barrier, for
containing ground water and DNAPL. Capping of this area is
appropriate for the nature and location of the contamination.
The remainder of the soils and sediments that are
contaminated above the specified on-site or off-site clean-up
criteria will be treated using either in-situ/ex-situ
bioremediation or low temperature thermal desorption. The
selected remedy is protective of human health and the environment
and is cost effective. While it is true that excavation and off-
site disposal of the contaminated soils and sediments could also
be implemented in a manner which would be protective of human
health and the environment,, it would also be much more costly to
implement. Thus, EPA believes that the selected remedy provides
the best balance among the alternatives available for this site.
1.9 Comment
A resident asked how long it would take to remediate the
Site.
EPA's Response
EPA explained that there were several legal steps required
prior to having the remedy actually implemented. EPA would first
attempt to negotiate a Consent Decree with the PRPS to perform
8
AR308766
-------
the work at the Site. The Consent Decree would provide the
mechanism under which the PRPs would be required to complete this
work on an enforceable schedule."
Assuming, a Consent Decree is successfully negotiated, the
PRPs would prepare a work plan for EPA's approval. The work plan
would provide the details on implementing the work delineated in
the Record of Decision.
The selected remedy calls for treatability studies to be
conducted to determine if bioremediation can successfully treat
the contaminated soils and sediments. The treatability studies
will also help identify the length of time required for
bioremediation to achieve the clean-up levels. If as -a 'result of
these studies it is determined that bioremediation will not be
successful,, the design of the Low Temperature Thermal Desorption
Process will begin.
In view of the uncertainties associated with the length of
time required for various steps in the process, the various
options which may be implemented, and the time required for
bioremediation to achieve the clean-up levels, it is difficult to
predict with any certainty when the bioremediation process will
be completed.
1.10 Comment
A resident asked that the entire area where the soils and
sediments are contaminated be fenced or posted to warn hunters
and fishermen. .
Response
EPA agrees that this area should be posted with warnings to
alert hunters and fishermen. The Record of Decision requires
posting of this area until the remedial action is complete. It
should be noted, however, that persons who are hunting in the
site area are trespassing on private property.
2. CITIZENS
EPA received two letters from citizens concerning the
Proposed Plan.
2.1 Comment
In one letter, a citizen was concerned about the impact of
the contaminated ground water on a domestic well.
EPA's Response
EPA called the citizen and determined the location of the
flR303767
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domestic well to be upgradient and out of range of the ground
water contamination at the Site. See EPA's response to Comment
1.1.
2.2 Comment
The other letter agreed with EPA's recommended alternative
along with a statement that EPA should require Standard Chlorine
to pay for the remedial action.
EPA's Response
See response to Comment 1.5.
3. POTENTIALLY RESPONSIBLE PARTIES (PRPs)
Air Products
EPA received written comments from Air Products and
Chemicals, Inc. which .is located immediately adjacent to the
Standard Chlorine property.
3.1 Comment
Air Products expressed concern that the RI Reports suggested
that ground water underneath the property owned by Air Products
may be contaminated. "Air Products would like (i) a resampling
of the two wells on its property to determine what changes, if
any, have occurred since 1990; and (ii) a further investigation
of the ground water plume to determine its extent under Air
Products' property."
EPA's Response
As noted in the Proposed Plan and the Record of Decision,
the decision for remediating the ground water is an interim
remedy. EPA agrees that additional investigation is required to
determine the extent of ground water contamination. As part of
the additional investigation, EPA will require that the two wells
on Air Products property be sampled and analyzed.
3.2 Comment
Air Products requested "the opportunity to participate in
any decisions regarding the placement of additional monitoring
wells and the design of the ground water remediation plan that
may affect the extent of the contaminant plume under Air
Products' property or the length of time that plume may exist."
EPA's Response
Air Products will have access to the information generated
10
flR308768
-------
during the additional investigation to determine the extent of
the ground water contamination via the Administrative Record
which will be placed in the Site Repository. Air Products will
also have the opportunity to comment on any recommended
alternatives for the final ground water remediation remedy.during
the public comment period for the Proposed Plan.
If the selected final remedy for the Site involves the
installation of wells or other structures on Air Products
property, EPA will also make the information developed during
remedial design available for Air Products review and comment.
Occidental Chemical Corporation
EPA received written comments from Occidental Chemical
Corporation .which is the landowner immediately east and north of
the Standard Chlorine property east and west of Route 9.
3.3 Comment
Occidental states that it is under a Consent Order with EPA
to conduct an investigation that includes the pipeline and Red
Lion Creek east of Route 9. The analytical results of the
Standard Chlorine RI showed the. presence of chlorobenzenes in the
ground water, adjacent to the pipeline, and west of route 9.
Occidental states that Standard Chlorine should be responsible
for addressing contamination which originates from and is
contiguous with the Standard Chlorine Site.
Response
EPA will require that an interim action at the Standard
Chlorine Site be implemented, while additional information is
collected and evaluated to make a decision in a final ROD for the
ground water. If the results of the ground water investigation
demonstrate a need for ground water remediation in the.vicinity
of the pipeline (both the east and west side of route 9), EPA
would use it'a legal authorities to have the work conducted by
the PRPs.
Standard Chlorine of Delaware. Inc.
Standard Chlorine had comments on the RI/FS as well as the
PRAP. Detailed comments were provided on behalf of Standard
Chlorine by BCM Engineers and Lowenstein, Sandier, et.al. The
comments are divided into the following categories:
Human Health Risk Assessment
11
flR308769
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Ecological Risk Assessment
Clean-up Criteria
EPA's Recommended Alternative
Ground Water
Soils/Sediments
Comparative Analysis of Alternative 3
SCD's Proposed Plan
Alternative 3 and Compliance wich ARARs
Questions and EPA's responses to the questions and comments
in each of these categories are summarized below:
HUMAN HEALTH RISK ASSESSMENT
3.4 Comment
Standard Chlorine stated that ingestion of ground water
should not be considered in evaluating human health risk.
Institutional controls such as prohibition of drinking, water
wells and deed restrictions will insure that ingestion of ground
water is not a pathway of future exposure of contaminants.
EPA's Response
The Preamble to the NCP (F.R. Vol 55, No.46 page 8711, March
8, 1990) states that "The effectiveness of the institutional
controls in controlling risk may appropriately be considered in
evaluating the effectiveness of a.particular remedial
alternative, but not as part of a baseline risk assessment."
Since it is the Superfund program's goal to return usable
ground waters, to their beneficial uses wherever practicable, it
is appropriate that ingestion of ground water be considered in
evaluating human health risk under a future-use scenario.
3.5 Comment
Standard Chlorine stated that the clean-up goal of soils
should be amended to reflect risk without dermal contact because
EPA guidance (EPA/600/8-91/011B) states that dermal contact with
soils should not be quantified due to the many uncertainties
associated with dermal contact. Standard Chlorine also states
that "assuming an acceptable risk of 1 x 10~5, a clean-up goal is
required only for 1,4-dichlorobenzene at a goal of 2,400 mg/kg."
12
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EPA's Response
In a meeting with Standard Chlorine on April 27, 1992, and
in follow-up telephone conversations with consultants
representing Standard Chlorine, EPA stated that the Agency's most
recent guidance at the time recommended that dermal contact with
soils not be quantified. Despite EPA bringing this matter to the
attention of Standard Chlorine, the revised Risk Assessment;
prepared by consultants for Standard Chlorine, included
calculations for the dermal pathway.
Standard Chlorine assumed an acceptable risk of 1 x 10"5 and
proposed clean-up criteria of 625 mg/kg of total COCs with a
ceiling of 450 mg/kg for 1,4-dichlorobenzene. This number was
calculated assuming dermal exposure. Traditionally, EPA Region
III uses 1 x 10~6 as a point of departure in determining
acceptable risks. In turn, EPA conducted a rough calculation of
the risk eliminating the dermal pathway and determined that 625
mg/kg of total COCs was within the 1 X 10"6 risk range.
Although Standard Chlorine states that a clean-up goal for
1,4-dichlorobenzene should only be 2,400 mg/kg at a 1 x 10"5
risk, no supporting calculations were provided. Assuming that
these calculations are correct, EPA would require remediation to
an acceptable risk of 1 X 10"6 which would be a clean-up level of
240 mg/kg for 1,4-dichlorobenzene. EPA approved the Remedial
Investigation Reports which included the Baseline Risk Assessment
and is confident in the calculations used to develop the clean-up
criteria for on-site soils. EPA maintains that 625 mg/kg of
total COCs with a ceiling of 450 mg/kg for 1,4-dichlorobenzene is
protective of workers at the Site.
ECOLOGICAL ASSESSMENT
Standard Chlorine states that a review of the ecological
studies conducted during the RI identified deficiencies in the
data and confounding factors which must be addressed to establish
ecological risk. Each issue is discussed separately.
3.6 Comment
Standard Chlorine states that 'confounding factors (dry
substrate that may have impacted the mortality of the earthworm)
may have affected the results of the earthworm bioassay making
the findings unreliable. Even if the confounding factor (the dry
substrate) "did not affect the results of the bioassay, the
difference between the NOEL (33 mg/kg) and the LOEL (486 mg/kg)
is too great (453 mg/kg) to define a clean-up goal." Standard
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Chlorine further states a clean-up goal of 33 mg/kg is too
conservative and additional bioassays are necessary.
EPA's Response
EPA agrees that confounding factors may have had an impact
on the results of the earthworm bioassay tests. However, the
off-site clean-up level was not arrived at solely on the basis of
these tests. While Standard Chlorine has suggested that the
clean-up levels of 33 mg/kg is too conservative, literature
searches suggest that a clean-up level of 33 may be too high to
be protective of all ecological resources. EPA also agrees that
additional bioassay tests are necessary and will be required as
part of the ecological monitoring plan.
Conducting ecological assessments at hazardous waste sites
is a new and developing area of investigation and there are
inherent difficulties associated with interpreting the data
obtained from an ecological assessment. Based upon che
information available at this time, EPA maintains that the clean-
up criterion of 33 mg/kg for off-site soils and sediments, in
conjunction with an ecological monitoring plan, is protective of
human health and the environment.
Due, in part, to the inherent difficulties associated with
obtaining precise results from any ecological assessment, EPA is
requiring an ecological monitoring plan to monitor the
effectiveness of the selected remedy. If new information becomes
available during or after the Remedial Design/Remedial Action
that demonstrates that the off-site clean-up criterion is not
protective, EPA, in consultation with DNREC and other support
agencies, may require additional remediation.
3.7 Comment
Standard Chlorine states that the results of the bioassays
do not suggest a dosage response relationship between the
chemicals of concern and germination of lettuce seeds. The
bioassays for lettuce seed lacked sufficient data to determine if
the results were due to levels of contaminants in the soil or
physical characteristics of the soil (e.g.nutrient availability,
etc.) .
EPA's Response
Contrary to SCD's view, the lettuce seed test showed
reliable results. The lettuce seed test was a valid test in that
it was successful in identifying a NOEL (2.2 mg/kg; 77% survival)
and a LOEL (32.8 mg/kg; 38% survival). All concentrations above
32.8 mg/kg had less than 38% survival. Whether or not there was
a dosage response relationship for all concentrations above the
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LOEL is irrelevant to the validity of the test.
Although physical characteristics of the soil were not
measured, the effects of site-specific soils on the germination
of lettuce seeds were evaluated. The findings from this test in
conjunction with other testing, literature searches and input by
federal and state biologists and scientists were used to develoo
the clean-up criterion for off-site soils and sediments.
Based on the information available at this time', EPA
maintains that the clean-up criterion of 33 mg/kg for off-site
soils and sediments, in conjunction with an ecological monitoring
plan, is protective of human health and the environment .
3.8 Comment . '
Standard Chlorine disagrees with a comment from the National
Oceanic and Atmospheric Administration (NOAA) on the PRAP about
the bioassay for Hyallela azteca. Specifically, NOAA stated that
the bioassay for Hyallela azteca indicated a statistically
significant decrease in percent survival at 1.7 mg/kg, whereas
Standard Chlorine states that the RI did not report this decrease
in percent survival at a concentration of 1.7 mg/kg (See Comment
4.4) .
EPA7 s Response . . .
The bioassay data that NOAA referenced was in Appendix K of
the RI report. The consultants who prepared the RI stated that
they did not use this bioassay data, instead relying on the
bioassays conducted in Appendix J. The reported reason for not
using bioassay data from Appendix K was that chronic level
effects could not be determined as a result of test
concentrations used. NOAA states it does not know how the RI
intended to use these data, or exactly why they were disregarded.
NOAA's evaluation of the-bioassay results in Appendix K indicated
a statistically significant reduction of.survival (variance
testing with Dunnett's procedure) in samples SDT-4 and SDT-6 as .
compared to controls, the RI reported that these sediment
samples contained total chlorinated benzenes at concentrations of
109 mg/kg in SDT-4 and 1.7 mg/kg in SDT-6. Therefore, NOAA
concludes that these data suggest that detrimental effects to
Hyallela azteca could occur at concentrations as low as 1.7
mg/kg.
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CLEAN-UP CRITERIA
3.9 Comment
Standard Chlorine states that the clean-up criterion of 33
mg/kg for off-site soils and sediments represents the worst case
effects identified in the RI Reports and fails to account for
uncertainties, suitability to habitat, and other confounding
facLors. Standard Chlorine further states that "application of
the worst case effect to all habitats is inappropriate and overly
conservative." To support its comments, Standard Chlorine
provided the following data:
Lettuce seed germination test results
Lowest Observable Effects Level (LOEL) 33 mg/kg
Earthworm toxicity test results
Lowest Observable Effects Level (LOEL) 486 mg/kg
Hyallela azteca sediment toxicity test results
No Observable Effects Level (NOEL) 136 mg/kg1
EPA/s Response
There is no single universally accepted and standardized
"cook book" approach to addressing sediment quality and clean-up
criteria. EPA used the results of the Ecological Assessment as
identified in the RI report to develop the clean-up criterion for
off-site soils and sediments. In addition, EPA and NOAA
conducted a literature search to substantiate the RI findings.
The results of the sediment toxicity tests, the earthworm
toxicity tests and the lettuce seed germination tests were
evaluated and used to develop the off-site clean-up criterion of
33 mg/kg. Biologists and scientists from EPA, DNREC, the Fish
and Wildlife Services (F&WS) and the Natioanl Oceanic and
Atmospheric Administration (NOAA) reviewed and commented on the
data reported in the Ecological Assessment.
EPA disagrees with the NOEL for the Hyallela azteca as
stated in Standard Chlorine's comment. Page 6-209 of the RI
report states that the NOEL for the Hyallela azteca is 68 mg/kg.
Comparison of NOEL for each of the tests results is as follows:
Lettuce seed germination test results
1Standard Chlorine stated in their comments that the NOEL
for Hvallela azteca was identified at 136 mg/kg. EPA was unable
to substantiate this statement. Page 6-209 of the RI report
states the no-observable-adverse-effeet-level (NOEL) was
determined to be 68 mg/kg for the Hyallela azteca.
16
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No Observable Adverse Effects Level (NOEL) 2 mg/kg
Earthworm toxicity test results
No Observable Adverse Effects Level (NOEL) 33 mg/kg
Hyallela azteca sediment toxicity test results
No Observable Effects Level (NOEL) 68 ma/kg2
As Standard. Chlorine staces, there are uncertainties
associated with each of the tests, but even with these
uncertainties, the NOEL levels are very close in range. The
clean-up criterion of 33 mg/kg does not represent a worse case
scenario, but rather a mid-range value that is not overly
conservative.
The species typically used in bioassay tests are selected .
due to their hardiness and their ability to tolerate hostile
living conditions. The Hyallela azteca is a hardy species and
therefore the findings of the sediment bioassays do not take into
consideration the impact of the contamination on a sensitive
species that could be an ecological receptor at this Site.
EPA's literature search has revealed that background value
established by Canada for chlorobenzenes is 100 ug/kg which is
substantially lower than the clean-up criterion of 33 mg/kg.
Another study revealed that terrestrial.fauna can be adversely
affected by levels of chlprobenzene as low as 144 ug/kg. EPA
recognizes that the literature search does not carry as much
weight as the site specific data in developing clean-up criteria,
but should be considered in conjunction with site specific data
to develop clean-up criteria.
Therefore, EPA does not agree that the soil/sediment clean-
up criterion is too low. In fact, the literature search suggests
that the number may be too high. EPA'has determined that a
c_ean-up criterion of 33 mg/kg of total COCs in conjunction with
an Ecological Monitoring Plan will be protective of the
environment at this Site.
3.10 Comment
Standard Chlorine recommended that additional studies be
2 As stated under comment 3.8, information contained in
Appendix K of the RI report shows the lower survival rate for
Hyallela azteca at sampling locations with concentrations as low
as 1.7 mg/kg. Page 5-209 of the RI report states that the
results of the toxicity tests presented in Appendix K were not
discussed in the RI report because chronic level effects could
not be determined as a result of the test concentrations.
17
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conducted that are designed to reduce or eliminate confounding
factors and establish habitat specific clean-up goals.
EPA's Response
EPA agrees that additional testing should be conducted,
however, we believe that the testing should be designed'to
confirm that the remedial activities have successfully protected
the ecosystem of the Site as opposed to developing new clean-up
criteria. As stated in responses to Comments 3.9, 3.12, and
3.13, the clean-up level of 33 mg/kg is based on several studies
and EPA believes it is an appropriate value to be used as the
off-site clean-up criterion. EPA's Region III is always open to
review sound scientific data and in turn, Standard Chlorine may
independently gather additional information or conduct additional
studies for EPA's review.
3.11 Comment
Standard Chlorine stated that the proposed clean-up level of
33 mg/kg appears to impact only the germination of lettuce. The
off-site areas proposed for clean-up include areas (drainage
swale, soil piles, and wetlands) that would not support
herbaceous upland vegetation because of heavy flows due to
intense precipitation events. Standard Chlorine stated that the
use of germination success for lettuce, an upland species, for
sediments in wetlands which may be saline (estuarine) is not
ecologically appropriate.
EPA7 s Response
SPA's recommendation of the clean-up criterion of the
drainage swale, soil piles, and wetlands is predicated upon two .
views; !') it is both an indirect source of contamination to
downgradient receptors and is a pathway for movement of
upgradient sources; and 2) it possesses habitat potential in and
of itself and thus contamination located there poses a potential
for risk to any ecological receptors that may live there. EPA
does not agree that heavy flows due to precipitation events in
the drainage swale will present a long-lasting obstacle to
eventual colonization by flora and fauna. The swale has the
ability to support vegetation and therefore the results of the
lettuce, seed germination are appropriately applied to this area.
Prior to the 1986 spill, the soils in the soil piles did
provide a habitat for species in the area. Remediation of these
soils will convert the material from waste to soil and in turn
the soils can be used to support flora and fauna.
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EPA agrees that the germination success for lettuce may not
be an appropriate test for developing clean-up criterion for the
wetlands. The results of bioassays of the Hyallela azteca would
be more appropriate in developing clean-up criterion for the
wetland area-. Although the RI reported the results of the
bioassay for Hyallela azteca as having a NOEL of 68 mg/kg, the
d=»i-a in Appendix K of the RI report, suggested detrimental effects
at concentrations as low as 1.7 mg/kg ]iee response to comment
3.8). EPA believes that bioassays of the Hyallela azteca are
appropriate in developing clean-up criteria for wetlands.
Based on the data in the RI, along with information obtained
as part of a literature search, EPA'has determined that a clean-
up criterion of 33 mg/kg of total COCs, for both the off-site
soils and sediments, in conjunction with an Ecological Monitoring
Plan will be protective of -the environment at this Site.
3 .12 Comment
Standard Chlorine stated that detailed studies of the
biological communities utilizing the sediments of the tributary
are necessary to determine the ecological resources that have
been impacted by the 1986 spill or will be disrupted and
destroyed if the sediments are excavated under Alternative 4B.
EPA's Response
The ecological studies conducted as part of the RI were
typical of most Superfund Ecological Assessments. EPA does not
typically require a level of study that would offer full survey
data for all habitats found within the area of impact.
After the public comment period closed, SCD submitted a
workplan (dated August 1994) for additional studies to clarify
points raised during the public comment period. . The purpose of
the studies proposed in the workplan is to serve as a baseline
for the ecological monitoring plan and to establish a clean-up
goal .for the unnamed tributary. Both EPA's Biological Technical
Assistance Group (STAG) and DNREC have reviewed the workplan.
BTAG contends that sufficient site-specific data has been used in
developing the clean-up level and recommends proceeding with the
existing clean-up level in conjunction with an ecological
monitoring plan. DNREC believes that the technical approaches in
parts of the workplan have merit and could be useful in
combination with the ecological monitoring program. The detailed
comments are included in the Administrative Record. EPA will
consider incorporating portions of the proposed studies as
components of the ecological monitoring plan.
The clean-up criterion of 33 mg/kg for off-site soils and
sediments is based on bioassays of three species representing
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-different habitats and EPA believes it will be protective given
the conditions found at this Site. While it is true that
excavation of these off-site areas will have a significant short
term impact to the existing biological communities, these
negative impacts will be outweighed by the positive results
expected as a result of the long-term clean-up in these areas.
3.13 Comment
Standard Chlorine recommended that additional studies of the
tributary to Red Lion Creek be undertaken to define appropriate
clean-up levels based, on site specific field studies.
EPA's Response
EPA maintains that sufficient site specific studies have
been conducted as part of the RI to develop clean-up criteria for
the unnamed tributary to Red Lion Creek. See responses to
Comments 3.6, 3.7, 3.9, 3.10, 3.11, and 3.12.
3.14 Comment
Standard Chlorine commented on NOAA's comment which
referenced that the clean-up criterion of 33 mg/kg is.two orders
of magnitude above the apparent effects threshold (AET") for 1,4-
dichlorobenzene and three orders of magnitude above the AET for
1,2,4-trichlorobenzene. Standard Chlorine contends that the AETs
cited by NOAA were based on regional studies (e.g. Pugent Sound)
that consider multiple chemicals or groups of chemicals and
therefore are unable to attribute observed effects to specific
chemicals. Standard Chlorine contends that additional studies
are necessary to develop site specific AETs. Standard Chlorine
proposes establishing site specific AETs based on sediment
chemistry .compared to benthic community indices.
EPA's Response
EPA agrees that the AET's cited by NOAA may be based on
studies that consider multiple chemicals or groups of chemicals.
At the same time, EPA recognizes that the clean-up criteria of 33
mg/kg is for multiple contaminants, primarily chlorinated benzene
compounds, (i.e. the COC's identified in the RI/FS and the ROD)
and not just 1,4-dichlorobenzene or 1,2,4-trichlorobenzene.
Benthic community data, as proposed by Standard Chlorine,
may be difficult to interpret for several reasons. First,
coastal plain streams, in general, tend to have a low diversity
of macroinvertebrates, making it difficult to apply the EPA Rapid
Bioassessment Protocol. Second, Red Lion Creek is an example of
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a physically- and chemically-altered system. The presence of
other manufacturing and disposal sites along the Creek may also
impact the health of the system." Therefore, 'the benthic
assessment must do more than simply demonstrate the spatial
pattern of richness and abundance in Red Lion Creek. It will be
necessary to identify one or more "reference" streams (DNREC has
proposed Dragon Run as an appropriate reference stream)
consisting of other tide-gate impacted systems which are free of
chemical facilities. Finally, bentnic studies will not provide
any information on the chemical status of the fish community
which has been impacted as a result of contamination in the Creek
and is the subject of a fish consumption advisory. Refer to the
Administrative Record for BTAG's specific comments on Standard
Chlorine's "Workplan for Additional Ecological Studies" dated
August 1994 which proposes benthic macroinvertebrate studies.
3.15 Comment .
Standard Chlorine stated that the requirements for the
ecological monitoring plan in the PRAP were vague and consisted
of 'chemical assays as opposed to ecological studies.
EPA's Response
The Ecological Monitoring. Plan, as described in the
Performance Section of the ROD, includes bioassays, chemical
monitoring of sediments, toxicity testing, habitat
characterization, and measurements of contaminant concentrations
in fish and muskrat tissue.
GROUND WATER
3.16 Comment
Standard Chlorine proposed that the ROD include an interim
action to contain ground water and DNAPL and include language
that addresses the uncertainty in achieving required.clean-up
levels.
EPA'g Response
The ground water component of the ROD is an interim action
and the. clean-up criteria has not been defined. The ROD requires
containment of ground water and recovery of known DNAPL (if
identified), as well as additional investigation to determine the
technical practicability of remediating ground water.
21
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3.17 Comment
Standard Chlorine stated that "it is not practical that a
remedial goal of MCLs be considered. "
EPA's Response
EPA agrees that it may not be practical to restore ground
wacer to MCLs in areas where there is known or suspected DNAPLs.
The analysis of ground water samples from monitoring wells during
the RI demonstrate that there are areas that contain known or
suspected DNAPL. On the other hand, there are areas that show
.lower concentrations of contaminants (e.g. MW 16) that indicate
dissolved contaminants which may be amendable to restoration to
MCLs. A determination of final clean-up criteria and of
possible additional remedial action will be made in a subsequent
ROD for ground water.
3.18 Comment
Standard Chlorine stated that EPA's concern of a low point
within the Columbia Formation at a location north of the SCD Site
in the vicinity of monitoring wells MW-6 and MW-7 is based on
misinterpretations of data used to develop figures in a 1983
hydrogeologic report on .the SCD Site. Standard Chlorine stated
that additional information will be collected during the RD to
determine the length and location of the physical barrier to
contain ground water.
EPA's Response
EPA agrees that additional information would be useful in
determining whether a low point does exist within the Columbia
Formation beneath the Standard Chlorine Site. EPA agrees that
additional information is required as part of the- RD.to determine
the length and location of the physical barrier to contain ground
water and DNAPL. In addition, EPA will require that additional
monitoring wells be installed to insure that contaminated ground
water and or DNAPL have not migrated northward beyond Red Lion
Creek.
SOILS/5EPIMBNTS
3.19 Comment
Standard Chlorine stated that in situ remedies have
advantages over ex situ remedies. Standard Chlorine proposed to
identify and evaluate additional in situ technologies that could
prove successful as contingency remedies for bioremediation.
Standard Chlorine suggested that the ROD allow for the inclusion
22
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of such technologies as contingencies to Alternative 6.
In a letter dated September 16, 1994, Standard Chlorine
proposed conducting additional treatability studies to identify
other technologies that may be more successful than
bioremediation in remediating the Site. In this letter, SCD
proposed investigating ex-situ soil vapor extraction utilizing
the sedimentation basin as a containment cell.
EPA' s Response
EPA agrees that in situ treatment, if capable of remediating
soils/sediments to the clean-up criteria, has some advantages
over ex situ treatment. The Feasibility Study identified
numerous in situ technologies for consideration at the Standard
Chlorine Site. All of these in situ technologies, with the
exception of. bioremediation, were eliminated at different phases
of the screening and evaluation process for various reasons. In
their c'omments, Standard Chlorine did not propose a specific in
situ treatment technology or new information that would make it
reasonable to revisit an in situ technology that was previously
eliminated. Therefore, EPA cannot justify the evaluation of
other in situ technologies either as a contingency to in situ
bioremediation or as a substitute for bioremediation.
EPA maintains that sufficient information is available to
make a final decision on remediating the soils and sediments at
the Site. EPA Region III will always review sound scientific
data and in turn, Standard Chlorine may independently gather
additional information or conduct additional studies for EPA's
review. However, the ROD will not require these additional
studies, and the schedule for the design of the selected remedy
will not be delayed in order to allow for the performance of
these additional investigations.
3.20 Comment
Standard Chlorine states that the location of the railroad
track area precludes implementation of biological treatment and
the ROD should identify that this area will be capped with
asphalt.
EPA' s Response
EPA recognizes that the railroad track area of the plant is
an integral part of the industrial operations. At the same time,
EPA contends that the area may be amendable to in situ
bioremediation and that this remediation could take place without
shutting down the railroad tracks. Placement of an asphalt cap
will entail downtime along the railroad tracks and/or
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coordination of deliveries and shipments. In situ bioremediation
would have a similar impact on the railroad track-but would have
the long term benefit of remediating the soils as opposed to
capping to prevent exposure.
3.?T COMPARATIVE ANALYSIS OF ALTERNATIVE
Standard Chlorine stated that Alternative 3 complies with
ARARs and provided a description of Alternative 3 as it was
presented in the FS along with a detailed comparative analysis of
Alternative 3 to EPA's recommended alternative (Alternative 6).
The analysis breaks out the media by ground water and . .
soil/sediments. The following is a brief summary of Standard
Chlorine's comparison for each of the criteria and EPA's response
for each criterion.
3.21(a) Overall Protection of Human Health and the Environment
GROUND WATER
Comment
Standard Chlorine states that Alternative 3 and Alternative
6 are equally protective of human health and the environment.
Standard Chlorine states that "it is not technically feasible to
restore ground water in the area as a future water supply
resource." SCO also states that through the implementation of
institutional controls, such as the designation of a ground water
management zone, it is possible to preclude the use of the site
ground water as a future potable source.
EPA's Response
EPA agrees that Alternative 3 and Alternative 6 are equally
protective of human health and the environment. EPA agrees that
it may not be technically practicable to restore ground water
containing DNAPLs to drinking water standards, but that there are
areas of ground water at the Site which may not be contaminated
with DNAPLs and may in turn be amendable to restoration to MCLs.
§300.430 (a) (iii) (F) of The National Oil and Hazardous Substance
Pollution Contingency Plan (NCP) states :
"EPA expects to return usable ground waters to their
beneficial uses, wherever practicable, within a timeframe
that is reasonable given the particular circumstances of the
site."
Also see response to comment 3.17.
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SOILS/SEDIMENTS
Comment
Standard Chlorine states that Alternative 3 and Alternative
6 are equally protective of human health and the environment.
Standard Chlorine also states that in situ technology would be
less disruptive to the wetlands and in turn more protective and
that otner in situ remedies should be evaluated as contingencies
for bioremediation.
EPA' s Response
EPA agrees that both Alternative 3. and Alternative 6 are
protective of human health and the environment. EPA also agrees
that in situ technology . would be less disruptive to the wetlands
then ex situ technology. Also see response to Comment 3.19.
3.21(b) Compliance with ARARs
GROUND WATER
Standard Chlorine commented that it is not technically
feasible to restore ground water in the area to MCLs.
EPA's Response
See response to comments 3.17 and 3. 21 (a).
SOILS AND SEDIMENTS
Comment
Standard Chlorine commented that Alternative 3 could comply
with ARARs according to the provisions of RCRA that apply to
corrective action management units ("CAMUs") .
EPA' 3 Response
The existing sedimentation basin does not satisfy the
requirements outlined in the regulations and therefore EPA cannot
consider designating the basin as a CAMU and in turn Alternative
3 does not comply with ARARs. This issue is discussed in more
detail in comments and responses 3. 23 (a) through 3.23(e).
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3.21(c) Lona-Term Effectiveness and Permanence
GROUND WATER
Comment
Standard Chlorine states that both Alternative 3 and
Alternative 6 offer long-term effectiveness and permanence.
EPA's Response
EPA agrees with this comment.
SOILS/SEDIMENTS
Comment
Standard Chlorine states that in situ treatment is preferred
for the'sediments in the wetland area as opposed to excavation
which woul-:1 disrupt the wetland area. Standard Chlorine also
states thac Alternative 3 is equivalent to Alternative 6 in long-
term effectiveness and permanence because the accessible soils
and .sediments would be treated via stabilization and provide for
containrr.ant in a disposal unit.
EPA's Response
Although EPA agrees that in situ treatment of the sediments
would be less disruptive to the wetlands, EPA nonetheless
believes that excavation and removal of the contaminated
sediments offers long-term effectiveness and permanence.
Moreover, specific in situ technologies and their impact on the
wetlands would need to be evaluated.
EPA does not agree that Alternative 3 is equivalent to
Alternative 6 in long term effectiveness and permanence.
Alternative 3 relies on containment of solidified/stabilized
contaminated soils and sediments in a lined and capped disposal
unit. The long-term stability of the stabilized soils/sediments
is not known. No information was presented nor were studies
conducted on the effects of freezing/thawing, wetting/drying,
aging, contact with liner materials, and contact with cap
materials. Alternative 6 entails treatment of the contaminated
soils and sediments to a health-based number and therefore
provides for long-term effectiveness and permanence. EPA
considers Alternative 3 primarily containment, and in turn the
long-term effectiveness and permanence is not equivalent to
Alternative 6 or the contingency Alternative 4B. Also see
response to Comment 3.21(d).
26
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3.21(d) Reduction in Toxicity, Mobility or Volume
GROUND WATER
Comment
SCD states that both Alternative 3 and Alternative 6 satisfy
the statutory preference for reduction of toxicity, mobility, or
volume Uhiough treatment of che principal threat, i-o human health
and the environment.
EPA's Response
The ground water component of Alternative 3 and Alternative
6 are the same. The remedy for ground water is an interim remedy
and is primarily a containment remedy in that a physical barrier
will be constructed to contain ground water. A ground water
investigation will be conducted to determine the technical
practicability of restoring ground water to MCLs.
SOILS/SEDIMENTS
Comment
SCD states that Alternative 3 addresses, treatment of
accessible soils and sediments via solidification/stabilization
and provides for containment in a disposal unit resulting in
reduction of toxicity and mobility.
EPA's Response
EPA does not agree that solidification/stabilization results
in reduction of toxicity. Although the mobility of the waste
will be less due to containment in a lined disposal unit,
stabilization has not been demonstrated to reduce the mobility of
the contaminants in the soils/sediments causing the site risks.
The stabilization of the. contaminated soils and sediments as
described in the FS does not constitute treatment. The FS report
states .
Stabilization of the material in the basin is primarily
directed toward improving the load bearing strength to
support the final cover. Stabilizing agents must be
selected via treatability testing to meet this [remedial]
design objective. Some chemical fixation may result,
however it [is] not the primary objective.
There is a statutory preference for selecting remedial
27
AR308785
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actions that employ treatment technologies that permanently and
significantly reduce the toxicity, mobility, or volume of the
hazardous substances as a principal element. The preamble to the
NCP (55 Fed. Reg. 8721) states:
EPA is establishing, as a guideline, that treatment as part
nf OKRCLA retnedi.es should generally achieve reductions of 90
to 99 percent in the concentration of mobility of individual
contaminants of concern, although tnere will be situations
where reductions outside the 90 to 99 percent range that
achieve health-based or other site-specific remediation
goals (correspondence to greater or lesser concentration
reductions) will be appropriate.
In a letter dated September 16, 1994, SCD requested that EPA
consider "A reduction less than 90% ... where the treatment is
employed in conjunction with a RCRA minimum technology disposal
unit". The regulations require that treated soils meet Land
Disposal Regulations (LDR) to be placed in a RCRA minimum
technology disposal unit. LDR requires that the soils be treated
to levels equal to or greater than the 90% reduction.
An OSWER Draft publication 9380.3-07FS, February 1991,
titled "Immobilization as Treatment" states;
"Solidification alone is not included as a treatment
technology under the Superfund definition of immobilization
because it does not satisfy the statutory preference for
treatment to reduce the toxicity, mobility, or volume (TMV) under
Superfund. The term "solidification" implies a treatment
technology which is intended to produce a monolith for purposes
of structural integrity. Since the principal purpose of
solidification is structural integrity, it does not qualify as
treatment under Superfund for purposes of reduction in TMV."
The document further states, "Immobilization is not deemed
to constitute treatment to reduce TMV in the following
circumstances:
Immobilization of volatile organics
Immobilization of semi-volatile and non-volatile
organics where a treatability study producing data
meeting the above mentioned criteria is not performed,
. planned and/or referenced."
An EPA Engineering Bulletin (EPA/540/S-92/015), dated May
1993, titled "Solidification/Stabilization of Organics and
Inorganics" states:
"Based on present information, the Agency [EPA] does not
believe that immobilization [solidification/stabilization]
28
SR308786
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is an appropriate treatment alternative for volatile organic
compounds (VOCs). Selection of immobilization of semi-
volatile compounds (SVOCs) and non-volatile organics
generally requires the performance of a site-specific
treatability study or non-site-specific treatability study
data generated on waste which is very similar (in terms of
type of contaminant, concentrations, and waste matrix) to
that to be treated and that demonstrates, through Total
Waste Analysis (TWA), a significant reduction (e.g 90 to 99
percent reduction) in the concentration of chemical
constituents of concern.... Although this policy represents
EPA's strong belief that TWA should be used to demonstrate
effectiveness of immobilization for organics, other
leachability tests may also be appropriate in addition to
TWA...."
In response to SCD's comment, EPA requested that SCD provide
additional information to support their claim that stabilization
satisfies the NCP definition of treatment. In a letter dated
September 16, 1994, SCD provided information on leachate test
protocols to demonstrate compliance with treatment goals. SCD
stated that they do "not believe that the use of Total Waste
Analysis (TWA) accurately reflects the reduction in mobility
achieved by stabilization/solidification and emplacement in a
RCRA minimum technology disposal unit". In turn, SCD proposed
that the American Nuclear Society Leach Test be utilized .for
determining if treatment is successful.
Since the soils and sediments are contaminated with a listed
hazardous waste, the Land Disposal Restrictions would apply.
Regulation 40 C.F.R. 268.40 states "A restricted waste identified
in § 268.41 may be land disposed only if an extract of the waste
or of the treated residue of the waste developed using the test
method in appendix II of part 261 ((Method 1311 Toxicity
Characteristic Leaching Procedure (TCLP)) does not exceed the
value shown in Table..." The American Nuclear Society Leach Test
is not identified in the 'regulations as an appropriate test
method for determining compliance with LDR. Thus any evaluation.
of the effectiveness of a proposed stabilization process.would
have to satisfy both the requirement to demonstrate a significant
reduction (90 to 99% reduction demonstrated via TWA or some other
appropriate, analysis) in the contaminants of concern and the
regulatory requirements for testing referenced in 40 C.F.R.
268.40.
For stabilization to be considered treatment under CERCLA,
the process in itself must reduce the mobility, toxicity, or
volume of the contaminant. As the FS states, the main objective
of stabilization in Alternative 3 is to improve the bearing
strength, and is not necessarily accompanied by reduction in
contaminant mobility. The toxicity of chlorobenzenes would not be
29
flR308787
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expected to decrease from the proposed treatment. The volume of
material containing the contaminants typically increases during
stabilization/solidification processing.
EPA recognizes that stabilization/solidification is used as
treatment in many RODs, but is typically part of a treatment
train involving some other form of treatment for sites containing
soils contaminated with organic compounds. EPA has no data or
literature to support that stabilization, as proposed in the
Feasibility Study, will reduce the toxicity (Total Waste Analysis
or Leachability testing) of the contaminated soils/sediments. In
addition, there is no information to evaluate the long-term
stability of the proposed stabilization process, the effects of
free zing/thawing, wetting/drying, aging, contact with liner
materials, contact with cap materials, and contact with
precipitation or ground water that infiltrates the containment
barriers.
EPA maintains that Alternative 6, and the Contingency
Alternative 4B are more effective in reducing the toxicity,
mobility, and volume of contamination through treatment.
3.21(e) Short-Term Effectiveness
GROUND WATER
Comment
SCD states that both Alternative 3 and Alternative 6 would
implement the same remedial components to contain, collect, and
treat contaminated ground water and DNAPL which may result in
minimal, if any, impacts to human health and the environment
during the construction period.
EPA's Response
EPA agrees with this comment.
SOILS/SEDIMENTS
Comment
SCD states that EPA's contingency alternative (4B-thermal
treatment) would be less protective of human health and the
environment during implementation than Alternative 3. Thermal
treatment would involve:
Excavation in wetlands and loss of habitat during
remediation;
30
4R308788
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Generation of residuals requiring further treatment
and/or ultimate disposal;
Greater potential short-term exposure to humans
EPA.'3 Response
Alternative 6, the selected alternative, minimizes short
term impacts by conducting in situ treatment, if it is determined
to be effective, which will minimize impact on wetlands and
habitat. In the event that bioremediation (Alternative 6) is
ineffective in remediating the soils and sediments to the clean-
up criterion, then thermal treatment (Alternative 4B) will be
implemented. Both Alternative 3 and Alternative 4B have a short-
term risk associated with excavation of contaminated soils and
sediments.
Chlorinated benzene compounds are volatile. Many
stabilization processes generate heat, either chemically
(hydration reactions) or mechanically (mixing) and in turn
Alternative 3 may have substantial volatilization of
contaminants. A modelling study performed by Battelle for EPA
(Contract 68-CO-0003, work assignment 13,1993) estimated that
volatilization of 1,2-dichlorobenzene could be substantial at
temperatures above 20'C (1,4-dichlorobenzene was not modeled).
The results of this study suggest that Alternative 3 could
generate residuals, i.e. capturing and treatment of air
emissions, which would require further treatment and/or ultimate
disposal. In addition, workers could be exposed to air emissions
from the volatilization of the contaminants. In turn,
Alternative 3, which is a. stabilization process, also has short-
term risk associated with it, and may present a greater risk to
human health than Alternative 6 or the contingency Alternative
4B.
3.21(f) Implementabilitv
GROUND WATER
Comment
The limited space may affect the implement ability of the
interceptor trench.
E_PAf s Response
EPA agrees with this comment.
31
flR308789
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SOILS/SEDIMENTS
Comment
SCD stated that thermal treatment would be more difficult to
implement than in situ bioremediation of sediments in the wetland
srpa. Thermal treatment of the sediments in the wetland area
would entail disruption/destruction of wetland areas.
EPA's Response
EPA's selected remedy is bioremediation which would be
easier to implement in the wetland area than thermal treatment.
In the event that bioremediation is unsuccessful in remediating
the sediments to the clean-up criterion, then thermal treatment
would be used to treat the contaminated wetlands. EPA agrees
that thermal treatment would be disruptive to the wetlands and
has included a requirement in the ROD calling for the development
of a wetlands restoration plan.
3.2l(g) Cost
Comment
SCD states that the present worth cost of Alternative 6 is
greater than the $12.2 million described in the PRAP, while
Alternative 3 is estimated at $6.8 million. SCD also states that
Alternative 3 would provide equivalent risk reduction to
Alternative 6 at a potentially lower cost.
EPA's Response
EPA utilized unit cost figures provided in SCD's FS to develop
the estimated present worth cost of Alternative 6. The cost is
higher than Alternative 3 because the remedy includes treatment
of all soils and sediments above the clean-up criterion resulting
in a more permanent solution. As stated in response 3.21(a),
both Alternative 3 and Alternative 6 are protective of human
health and the environment.
3.22 Comment
Standard Chlorine provided a comprehensive description of
their proposed remedy for the Site. EPA has summarized SCD's
comments and grouped them into four categories: Additional Work
during Remedial Design, Ground Water, Soils/Sediments and
Institutional Controls.
32
flR308790
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3.22(a) Additional Work During Remedial Design
Comment . _.
Standard Chlorine had two pages of comments relating to
elements that they believe should be included in the Remedial
Design. These elements included monitoring and investigative
approaches for determining the extent of the DNAPL and ground
water contamination.
EPA's Response
Many of the tasks proposed appear reasonable and will be
evaluated further during the Remedial Design phase of the
project. .
3.22(b) Ground Water
Comment
SCO stated that the three components of long-term ground water
remediation (interceptor trench,, aqueous phase recovery wells,
and DNAPL zone recovery wells) would be finalized during Remedial
Design and an achievable clean-up criteria will be based on the
optimally designed integrated recovery system.
EPA's Response
The intent of the interim remedy for ground water is to contain
the ground water and recover known DNAPL. Clean-up criteria for
ground water will be identified in the final remedy which will be
based on the findings of the additional investigation.
3.22(c) Soils and Sediments
3.22(c)(1) Comment
SCO maintains that there is no evidence that the soils underlying
the sedimentation basin are contaminated.
EPA's Response
The FS reported that the primary liner had been breached and
therefore the liner'of'the sedimentation basin "was suspect". EPA
agrees that .there is no analytical data to document that the
soils underlying the sedimentation basin are .contaminated because
no soil samples were obtained from this area. Based on the
findings of the FS, EPA believes that the soils underlying the
33
flR30879
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basin may be contaminated so once samples are obtained and
analyzed, further remediation may be necessary.
3.22(c)(2) Comment
SCD proposed to conduct additional work to identify habitat
conditions to be used to recompute the clean-up criterion for
off-site soils and sediments.
EPA's Response
As stated previously, EPA believes that the off-site clean-up
criterion .established in the ROD will be protective of human
health and the environment. Thus there is no need to recompute a
clean-up criterion. Further, EPA maintains that the additional
work to evaluate habitat conditions will not be necessary to
develop clean-up criterion. The Ecological Assessment conducted
during -the Remedial Investigation entailed numerous studies
including, but not limited to, fish tissue sampling and analysis..
toxicity testing, wetland delineation, and analysis of ecological
receptors. The off-site clean-up criterion was identified only
after an analysis of all of the results from the ecological
assessment. As noted in the ROD, an Ecological Monitoring Plan
will be developed and implemented to ensure that the remedy is
and remains protective .
3.22(c) (3) Comment
SCD proposed to conduct additional treatability studies for
bioremediation and other applicable technologies..
EPA's Response
EPA's Region III is always open to reviewing additional
information regarding treatment alternatives. However,. EPA
believes that the RI/FS provides sufficient information to select
a remedy for this Site. The ROD will not require additional
treatability studies, and the schedule for the design of the
selected remedy will not be delayed to allow time for the
performance of these studies.
3.22(d) Institutional Controls
Comment . .
SCD states that institutional controls would be implemented
under their plan to include site monitoring, site access
restrictions, and deed restrictions. In addition, DNREC would
implement a ground water management zone for the area.
34
5R308792
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EPA's Response
EPA agrees that these elements should be included in the
remedial action and these elements are included in the ROD.
3.23 Applicability of "CAMU" and Alternative 3
Standard Chlorine submitted several pages of comments
discussing the Corrective Action Management Unit ("CAMU")
provisions of RCRA. SCD states that the CAMU provisions of RCRA
are ARARs for the soil and sediment related components of SCO's
recommended remedial alternative (Alternative 3) for this Site
and that SCD's preferred alternative would comply with these
ARARs.
3.23(a) Comment
SCD stated that Section 121 of the Comprehensive
Environmental Response, Compensation, and Liability Act
("CERCLA"), 42 U.S.C.§9621 and 40 C.F.R. §300.430(f)(1)(i)(A) of
EPA's National Oil and Hazardous Substances Pollution Contingency
Plan ("NCP"), require compliance with ARARs as a threshold
requirement which each alternative remedy must meet in order to
be eligible for selection,
EPA's Response
EPA agrees with this comment.
3.23(b) Comment
SCD stated that remediation of soils and sediments at the
Site is governed by action-specific ARARs in the absence of
chemical-specific and location-specific ARARs.. SCD stated that
"EPA should select these technology-based or activity-based
requirements by determining the management actions necessary to
address the risk to human health and the environment or exposure
posed by the hazardous substances in the source area being
addressed". SCD further stated that SCD's recommended
alternative (Alternative 3) is "just as protective of human
health and the environment as the remedy selected in the PRAP,
since all soils and sediments exceeding clean-up criteria would
be treated and/or contained in a lined and capped unit".
EPA's Response
EPA agrees that both Alternative 3 and Alternative 6 are
protective of human health and the environment. EPA maintains
that the stabilization of soils and sediments prior to
35
AR308793
-------
consolidation in a lined and capped unit does not constitute
treatment. See response to comment 3_.21(d) .
3.23(c) The Applicability. Relevance and Appropriateness of RCRA
Comment
SCD stated that for several reasons, including the fact that
the soils and sediments are contaminated with a RCRA hazardous
waste, RCRA requirements are relevant and appropriate to the SCD
Site even if they are not applicable.
EPA'-s Response
EPA agrees with this comment.
3.23(d) . The Applicability. Relevance, and Appropriateness of
the CAMU Provisions of the Corrective Action Management
Regulations
Comment.
SCD stated that the preamble to the CAMU regulations states
that the CAMU requirements "will also become RCRA ARARs for
hazardous waste management activities at CERCLA sites". SCD also
stated that "SCO's preferred remedial alternative [Alternative 3]
will provide long-term and short-term effectiveness and
permanence that is equivalent to the levels that would be
provided by the remedial alternative selected by EPA in the
PRAP".
EPA's Response
The CAMU regulations are not ARARs for the Standard Chlorine
Site and would only be considered ARARs if EPA were to designate
the sedimentation basin as a CAMU. 40 C.F.R. § 264.552 (b) (1)
specifies requirements for designating regulated units as CAMUs.
Specifically 40 C.F.R. § 264.552(b) CD(i) states:
"The regulated unit is closed or closing, meaning it has
begun the closure process under § 264.113 or § 265.113; and
(ii) Inclusion of the regulated unit will enhance
implementation of effective, protective and reliable
remedial actions for the facility."
The closure process has not begun for the existing
sedimentation basin and therefore EPA cannot consider designating
36
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the basin as a CAMU. EPA does not agree that Alternative 3
provides long-term and short-term effectiveness and permanence
that is equivalent to that of the selected remedy. See responses
to comments 3.21(c) and (e) for a more detailed explanation.
3.23(e) Implementation of the CAMU_Provisions at the SCO Site
3.23(e) (1) Comment
SCD stated that "Selection and implementation of SCO's
preferred alternative would be consistent with the CAMU
provisions of RCRA both in terms of the portions of the SCD site
that would be designated as a CAMU and placement of excavated and
created wastes from the site back into a reconstructed and capped
unit. "
EPA's Response
40 C.F..R. § 264.552 defines the requirements to be used by
the Regional Administrator to designate an area of a facility as
a CAMU. Neither the FS nor Standard Chlorine's comments on the
PRAP provide sufficient detail to determine if the sedimentation
basin would satisfy the requirements in 40 C.F.R. § 264.552. For
example, 40 C.F.R. §§ 264.552(c) arid (d) contain specific
requirements which EPA must evaluate and address before it can
designate an area as a CAMU. This information was not provided
by Standard Chlorine and thus EPA is not in a position to make a
determination that Alternative 3 could be implemented in
compliance with the CAMU provisions of RCRA. Standard Chlorine
has not demonstrated that the soils and sediments would undergo
treatment as required by the CAMU regulation 40 C.F.R. §
264.552(c) (6), prior to placement in the reconstructed and capped
unit. See response to comment 3.21(d).
The soils arid sediments which were.placed in the
sedimentation basin were contaminated with a listed hazardous
waste and as such are required by RCRA regulations to be managed
as a hazardous waste. In turn, the sedimentation basin is a
regulated hazardous waste unit because it received a hazardous
waste. 40 C.F.R. § 264.552(b)(1)(i) requires that a regulated
unit be closed or undergoing closure in order to be designated as
a. CAMU. Since SCD never obtained a permit for storage/disposal
of hazardous waste in the sedimentation basin, and the basin is
not closed or undergoing closure, EPA can not consider
designating the sedimentation basin as a CAMU and in turn the
CAMU regulations are not ARARs.
37
flR308795
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3.23(e){2) Comment
SCD stated that if EPA designated the sedimentation basin as
a CAMU, SCD would be able to place remediation wastes into the
CAMU without triggering RCRA LDRs. SCD further states that "this
exemption from the LDRs would encompass any wastes generated as
part of the CERCLA cleanup, no matter where the wastes originated
within the SCD site".
EPA's_Response
EPA agrees that by designating the sedimentation basin as a
CAMU, LDRs would not be triggered. However the intent of the
CAMU regulations is not to by-pass LDR requirements, but to allow
for more flexibility in management of remediation wastes. Prior
to the CAMU concept, many remedies were limited to capping in
place because the only other alternative was excavating,
incinerating to LDR requirements and ultimate off-site disposal
at a RCRA Subtitle C facility which would result in high costs.
The preamble to the final CAMU regulations (58 Fed. Reg.
6658, 8660) states the CAMU concept is
"... estimated to result in more treatment of wastes using
more effective treatment technologies than would occur under
the other regulatory options considered by the Agency. In
addition., today's rule is predicted to result in more on-
site waste management (vs. off-site management); lesser
reliance on incineration; greater reliance on innovative
technologies; and a lower incidence of capping waste in
place without treatment."
The preamble also states (58 Fed. Reg. 8658, 8682) that the
CAMU alternative "... would likely provide a greater degree of
certainty of long-term effectiveness ... by encouraging greater
use of ex-situ treatments other than incineration and reduced use
of management in place."
Regulation 40 C.F.R. §264.552 (c) (6) states "The CAMU shall
enable the use, when appropriate, of treatment technologies,
(including innovative technologies) to enhance the long-term
effectiveness of remedial actions by reducing the toxicity,
mobility, or volume of wastes that will remain in place after
closure of the CAMU".
As stated previously (See EPA's response 3.21 (c) and
3.21(d), as well as the ROD, stabilization, as proposed in SCD's
preferred alternative (Alternative 3) does not constitute
treatment or a reduction in toxicity, mobility or volume (See 40
C.F.R. §264.552(c) (6) and in turn would not satisfy the CAMU
regulations. Also see response to 3.23(e) (1).
38
flR30879S
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3.23(e)(3) Comment
SCD states that according to the preamble to the final CAMU
regulations, "a facility owner required to remediate a surface
impoundment (e.g.. by removing or treating some or all of the
sludges) need not comply with LDRs when it redeposits residuals
back into the impoundment if EPA designates the impoundment as a
CAMU or part of a CAMU. Under this same reasoning, SCD would not
have to comply with the LDRs or Minimum Technology Requirements
("MTRs") with respect to excavated wastes placed into a
reconstructed and capped unit pursuant to implementation of SCO's
preferred remedial alternative.
EPA's Response
EPA agrees that the preamble to the final CAMU regulations
states that the placement of remediation wastes into a CAMU will
not trigger LDRs or MTRs. For reasons identified in response to
comment 3.23 (e) (1), EPA may not designate the sedimentation
basin as a CAMU and SCD is required to comply with LDRs and MTRs
because they are ARARs.
3.23(e)(4) Comment
SCD states that "the remedial alternative [Alternative 3]
described in the FS and in the letter to you [EPA], dated June 6,
1994, should be governed by the CAMU provisions of RCRA, which
are ARARs for that remedy". SCD states that their preferred
alternative, [Alternative 3] would satisfy CERCLA's threshold
requirement that the chosen remedy comply with ARARs.
EPA's Response
EPA does not agree that the CAMU provisions of RCRA are
ARARs for the SCD Site. The CAMU provisions would only be ARARs
if EPA designated a unit at the SCD Site as CAMU. As stated in
response to comment 3.23(e)(1), EPA may not designate the
sedimentation basin as a CAMU and in turn the CAMU provisions are
not ARARs. EPA has determined that Alternative 3 does not
satisfy CERCLA's threshold criteria for compliance with ARARs,
and this is discussed in Section 7 of the ROD.
3.23(e)(5) Comment
SCD states that "The SCD preferred remedy [Alternative 3]
would provide long-term and short-term risk reduction and
protectiveness levels that correspond to the levels that would be
achieved through implementation of the remedy chosen by EPA in
the PRAP, at a potentially significant cost savings".
. 39
BR308797
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EPA' s Response
See EPA's responses 3.21(c) and 3.21(e).
3.23(e) (6) Comment
SCO states that selection of Alternative 3 in a manner
consistent with RCRA's CAMU provisions would promote EPA's
objective of removing regulatory impediments which, when applied
to the contaminated soils and sediments at the SCD Site, could
impede EPA's ability to select and implement a reliable,
protective, and cost-effective remedy at the SCD Site.
EPA' s Response
As stated in response to comment 3.23(e) (1), EPA may not
designate the sedimentation basin as a CAMU and in turn the CAMU
provisions of RCRA are not ARARs. Alternative 3 is eliminated as
a viable alternative because it does not comply with ARARs. EPA
has selected a remedy which utilizes innovative technology
(bioremediation) and is cost effective with a present-worth cost
of $6.6 to 12.2 million. In the event that bioremediation is
unsuccessful in remediating the soils/sediments to the clean-up
criteria, the contingency remedy is a proven technology that will
remediate the soils/sediments to the clean-up criteria.
4 . NATURAL RESOURCE TRUSTEES
National Oceanic and Atmospheric Administration (NOAA)
4. .1 Comment
NOAA requested that "trigger values" that would cause
additional cLean-up of Red Lion Creek east of Route 9 be
addressed more fully. NOAA also requested copies of the reports
being prepared under the Consent Order between Occidental
Chemical Corporation and EPA.
EPA' s Response
EPA is requiring that Standard Chlorine conduct ecological
monitoring to demonstrate that the remedy is protective of the
environment. If the results of the ecological monitoring along
with the findings of the investigation being conducted by
Occidental Chemical Corporation suggest that additional remedial
action is needed, EPA will require that this additional work be
40
flR303798
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conducted. Due to the nature of the ecological studies that will
be conducted, it is difficult to identify an exact "trigger
value" at which remediation would be required.
Copies of all the reports prepared by Occidental Chemical
Corporation under the Consent Order can be made available to
NOAA.
4.2 Comment
NOAA commented that page 5 of the PRAP did not address .
sediments in Red Lion Creek in two separate references.
EPA's response
The first reference identifies the principal threat'wastes
associated with the Standard Chlorine Site and the sediments in
the Red Lion Creek are not considered principal threats (Note,
however, that some of the sediments in the unnamed tributary to
Red Lion Creek are considered principal threat wastes). The
second reference describes the final action component for
remediation of soils and sediments. EPA is not requiring
Standard Chlorine to remediate the sediments in Red Lion Creek at
this time, since the monitoring data indicates that the
concentrations of contaminants in Red Lion Creek are below the.
off-site clean-up criterion.
4.3 Comment
NOAA requested that EPA collect additional sediment and
surface water data from the unnamed tributary to Red Lion Creek
and Red Lion Creek to define the extent of contamination.
EPA's Response
Numerous sediment samples were collected from the unnamed
tributary to Red Lion Creek and Red Lion Creek during the
Remedial Investigation and the nature and extent of contamination
has been defined for a clean-up criterion of 33 mg/kg of total
COCs. In the event that the results of the ecological monitoring
suggest that the clean-up criterion are not protective of the
environment, EPA will require that additional data be collected
at that time.
4.4 Comment
NOAA expressed concern that the clean-up criterion, of 33
mg/kg of total COCs for soils/sediments in the unnamed tributary
to Red Lion Creek and Red Lion Creek may not be protective based
on the interpretation of the bioassay data conducted, as part of
the Ecological Assessment (Also see comment and response 3.8).
41
flR303799
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NOAA recommends that the tests be repeated using proper QA/QC and
validation guidelines to determine a clean-up level protective of
aquatic resources.
EPA's Response
EPA recognizes that there are uncertainties associated with
the findings of the bioassay data referenced by NOAA. However,
as noted in our response to Comment 3.10, the off-site clean-up
criterion of 33 mg/kg of total COCs is based on the results of
several studies and EPA believes it is an appropriate value to be
used as the off-site clean-up criterion. Further, to ensure that
this level is in fact protective of ecological receptors, the ROD
calls for an extensive ecological monitoring plan to be developed
and implemented as part of the selected remedy.
4.5 Comment
NOAA requested that chemical analyses of surface water,
sediments, fish tissue, and sediment bioassays be included in the
ecological monitoring plan.
EPA's Response
The ROD calls for the development of an ecological
monitoring plan which will include these elements.
4.6 Comment
NOAA requested that the ecological monitoring plan not be
limited to six years in the event that the remedy is not
successful.
EPA' s. Response
The ROD requires that the ecological monitoring be conducted
for "at least five years".
4.7 Comment
NOAA expressed concern that the on-site clean-up criteria
for soils and sediments (625 mg/kg) is an order of magnitude
higher than the off-site clean-up criterion (33 mg/kg) and may
act as a source of contamination for the off-site soils and
sediments.
42
AR30880Q
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EPA's Response
Performance Standards in the ROD require control of storm
water run-off from all areas of the Site that may potentially
contaminate the waters of the State of Delaware.
4.8 Comment
NOAA requested "some explanation as to why the treatability
studies were not definitive".
EPA's Response
The objective of the treatability study was to evaluate the
technical feasibility of utilizing bioremediation at the SCD
Site. Flask tests were conducted in a laboratory for a period of
60 days. EPA's review of the test results identified problems
with the experiment design, which in turn impacted the
interpretation of the data.
Overall, the treatability studies were not definitive based
on the following: (1) variability of the concentration of total
chlcrobenzenes observed in the flasks and the. associated lack of
confidence in the data, (2) the potential for volatile losses
from the reactor flasks, (3) inconclusive stoichiometric release
of chlorides, (4) no nutrient consumption, and (5).lack of
microbial data.
U.S. Fish and Wildlife Service (F&WS)
4.9 Comment
F&WS commented that the ecological monitoring plan should
contain all the elements identified in the PRAP.
EPA's Comment
The Ecological Monitoring Plan called for by this Record of
Decision incorporates all of the ecological monitoring activities
identified in the PRAP.
4.10 Comment
F&WS believes the time frame for the ecological monitoring
plan should be left open ended.
EPA's Response
See Response to Comment 4.6
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BR30880
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4.11 Comment
F&WS is concerned that the on-site clean-up criteria for
soils and sediments (625 mg/kg) is higher than the off-site
clean-up criterion (33 mg/kg) and may act as a source of
contamination for the off-site soils and sediments. F&WS
recommends an erosion control plan supported by monitoring.
SPA's _Rasponse
See Response to 4.7.
4.12 Comment
F&WS had specific comments on items that should be included
in the wetland mitigation plan.
EPA's Response
. EPA will provide the F&WS the opportunity to review and
comment on the wetland mitigation plan prior to EPA issuing
approval of the plan.
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