Superfund Program
Proposed Plan
Operable Unit 3 (OU3)
(Former Plant Area)
Standard Chlorine of Delaware, Inc. Site
New Castle County, DE
EPA Region 3
July 2009
EPA ANNOUNCES PROPOSED PLAN
This Proposed Plan identifies the Preferred
Alternative for the Standard Chlorine of
Delaware, Inc. Superfund Site (Site or SCD
Site) Operable Unit 3 (OU3). OU3 is the
vadose zone soil and soil gas in the former
plant area at the Site. This plan also provides
the rationale for this preference and includes
summaries of other cleanup alternatives
evaluated for use at this OU of the Site.
This document is issued by the U. S.
Environmental Protection Agency (EPA),
the lead agency for the Site, and the
Delaware Department of Natural Resources
and Environmental Control (DNREC), the
support agency. EPA, in consultation with
DNREC, will select a final remedy for OU3
of the Site after reviewing and considering
all information submitted during the 30-day
public comment period. EPA, in
consultation with DNREC, may modify the
preferred alternative or select another
response action presented in this Plan, based
on new information or public comments, or
may seek additional public comment on a
revised proposed plan as described in
Section 300.430(f)(3)(ii)(B) of the National
Oil and Hazardous Substances Pollution
Contingency Plan (NCP), 40 Code of
Federal Regulations (CFR)
§ 300.430(f)(3)(ii)(B). Therefore, the public
is encouraged to review and comment on all
the alternatives presented in this Proposed
Plan.
EPA is issuing this Proposed Plan as part of
its public participation responsibilities under
the NCP, at 40 CFR § 300.430(f)(2). This
Proposed Plan summarizes information that
Dates to Remember:
MARK YOUR CALENDAR
PUBLIC COMMENT PERIOD:
July 16, 2009 - August 14, 2009
EPA will accept written comments on the
Proposed Plan during the public comment
period.
PUBLIC MEETING:
July 28,2009
EPA will hold a public meeting to explain
the Proposed Plan and all of the alternatives
presented in the Feasibility Study. Oral and
written comments will also be accepted at the
meeting. The meeting will be held at the
Delaware City Fire Hall, 815 Fifth Street,
Delaware City, DE at 6:00 p.m.
For more information, see the
Administrative Record at the following
locations:
EPA Records Center
1650 Arch Street
Philadelphia, PA 19103
(215) 814-3123 for appointment
Delaware City Library
250 Fifth Street
Delaware City, DE 19706
on the web at:
www.epa.gov/arweb
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can be found in greater detail in the
Remedial Investigation/Feasibility Study
(RI/FS) reports and other documents
contained in the Administrative Record file
for this Site. EPA and DNREC encourage
the public to review these documents to gain
a more comprehensive understanding of the
Site and the Superfund activities that have
been conducted at the Site.
IDENTIFICATION OF OPERABLE
UNITS
This Proposed Plan addresses the evaluation
of remedial alternatives for Operable Unit 3
(OU3). This Proposed Plan does not address
other OUs at the Site. The first Record of
Decision (ROD) at the Site, issued in 1995,
did not refer to operable units. In the years
since, for administrative purposes, EPA has
identified operable units for the Site as
follows:
OU1: Interim action for groundwater
OU2: Final action for spill soils
OUS: Former plant area
OU4: All other actions, including the final
remedy for groundwater
Based on these OU designations, the 1995
ROD addressed OU1 and OU2. The final
remedy for groundwater will be issued in the
future as part of OU4.
SITE BACKGROUND AND HISTORY
The Standard Chlorine of Delaware, Inc.
Superfund Site is located in New Castle
County, Delaware. The Site is located
approximately 3 miles northwest of
Delaware City, Delaware, west of Route 9
(River Road) and south of Red Lion Creek
(See Figure 1).
The Site is approximately 65 acres in area,
and contains a fenced area that is the former
site of the Standard Chlorine of Delaware,
Inc. (later Metachem Products, LLC)
chlorobenzene manufacturing plant. The
plant was in operation from 1966 to May
Figure 1 - Standard Chlorine Site Map
2002, when it was shut down abruptly by its
owners.
A series of major releases of chlorobenzene
compounds in 1981 and 1986, totaling over
574,000 gallons, led to the listing of the Site
on the National Priorities List (NPL) in
1987. An Administrative Order on Consent
(AOC) between DNREC and Standard
Chlorine of Delaware, Inc. (SCD) requiring
the performance of an RI/FS by SCD at the
SCD Site was issued on January 12, 1988,
and amended November 14, 1988.
The objectives of the initial RI, completed in
1992, were to characterize Site conditions,
determine the nature and extent of
contamination, and assess risks to human
health and the environment related to the
soils. This initial 1992 RI concluded that
there is a large quantity of chlorobenzene
DNAPL (Dense Non-Aqueous Phase
Liquid) in the soils of the vadose and
saturated zones beneath the former plant
area. For many years this DNAPL was the
source of a plume of dissolved phase
chlorobenzenes originating beneath the plant
and flowing northward in the Columbia
Aquifer until it discharged into Red Lion
Creek and the surrounding wetlands.
Based on the conclusions of the 1992 RI and
the 1995 Feasibility Study, EPA issued a
Record of Decision (ROD) for the Site on
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March 9, 1995. A Unilateral Administrative
Order (UAO) for Remedial
Design/Remedial Action (RD/RA) was
issued by EPA to SCO on May 30, 1996.
The contaminants of concern (COCs)
identified in the 1995 ROD included
benzene, a dozen different chlorobenzene
compounds, and toluene. Subsequent
investigations have identified
polychlorinated biphenyls (PCBs),
metachloronitrobenzene, and dioxins as site-
related contaminants, but these compounds
were not included as COCs in the 1995
ROD.
The remedy selected in the 1995 ROD
consisted of two components: an interim
action for groundwater (currently identified
as Operable Unit 1 (OU1)) and a final action
for spill soils and sediments (currently
identified as OU2). The interim action for
groundwater addressed containment of
groundwater to minimize continued release
of contaminants, along with pumping and
treating any groundwater removed from the
containment area. The remedy selected for
spill soils and sediments was treatment,
either by bioremediation or by Low
Temperature Thermal Desorption.
The groundwater beneath the SCO Site does
not pose a current threat to drinking water
sources because of the large distance
between the contamination and the drinking
water source wells. The nearest drinking
water well is over one mile upgradient
(opposite the direction of groundwater flow)
and other wells are over three miles
downgradient (in the direction of
groundwater flow) and in a much deeper
portion of the Potomac Aquifer (next aquifer
down). These municipal supply wells are
sampled frequently to confirm the safety of
the water supply and there has been no
indication that site-related contaminants
have reached these wells. EPA is continuing
to investigate groundwater and the final
remedy for groundwater will be issued as
partofOU4.
In December of 1998, the SCO Facility and
property were sold to Metachem Products,
LLC (Metachem). Metachem continued
remedial design activities. Metachem filed a
bankruptcy petition on May 10, 2002, and
abandoned the SCO Site on May 14, 2002,
to the custody and control of EPA and
DNREC. Since then, EPA and DNREC
have implemented an emergency cleanup
action, constructed an interim remedy for
groundwater, and considered various options
for the long-term cleanup of the SCD Site.
In 2004, EPA issued a ROD Amendment
implementing offsite thermal treatment
(incineration) as the remedy for bulk liquid
wastes left onsite following the
abandonment of the facility.
The interim remedy for groundwater,
construction of a soil-bentonite subsurface
barrier wall, was completed in 2007. As a
result, the DNAPL beneath the former plant
and the plume of contamination emanating
from that DNAPL have been contained
within the barrier wall. The contaminated
groundwater from within the barrier wall is
being collected and treated via a
Groundwater Extraction and Treatment
System (GETS), often referred to as a
"Pump and Treat" or P&T System.
SITE CHARACTERISTICS
The following are some general
characteristics of the Site, followed by a
more detailed description of the
characteristics of OU3.
There is a large quantity of chlorobenzene
DNAPL (Dense Non-Aqueous Phase
Liquid) that is composed mostly of
chlorobenzene compounds in the vadose
zone soils and saturated sediment within the
Columbia Aquifer. For many years this
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DNAPL was the source of a groundwater
plume of dissolved phase chlorobenzenes
that originated from rainwater percolating
through soils contaminated with DNAPL, as
well as relatively clean groundwater flowing
through that same DNAPL in the aquifer
beneath the plant. This contaminated
groundwater plume flowed northward in the
Columbia Aquifer until it discharged into
Red Lion Creek and surrounding wetlands.
After EPA completed construction of a soil-
bentonite subsurface barrier wall in 2007,
the DNAPL beneath the former plant and
the plume of contamination emanating from
that DNAPL were contained within the
barrier wall. The contaminated groundwater
from within the barrier wall is being
collected and treated via a Groundwater
Extraction and Treatment System (GETS),
often referred to as a "Pump and Treat" or
P&T System.
The DNAPL beneath the Site is considered
to be a "principal threat waste" because it
contains chemicals of concern at
concentrations that would present a
significant risk to human health should
exposure occur. Although the DNAPL is
outside the scope of OU3 and will be
addressed as part of the future OU4 ROD,
the OU3 remedy will still have a beneficial
impact on human health and the
environment by reducing the mobility and
potential for exposure of receptors to this
principal threat waste. The OU3 remedy
will continue and expand upon the
containment of the DNAPL beneath the
former plant area begun by the subsurface
barrier wall built as part of the OU1 remedy.
OU3 Remedial Investigation (RI)
EPA initiated the RI/FS for the former plant
area of the Site, also known as Operable
Unit 3 (OU3) in February 2004 (see Figure 2
for a map of OU3 and its key features). The
objectives of the RI were generally to
characterize Site conditions, determine the
nature and extent of contamination, and
assess risks to human health and the
environment related to the soils.
Figure 2 - Approximate area of OU3
Summarized below are the findings of the
Remedial Investigation:
The August 2007 RI Report confirmed that
soils in the former plant area are
contaminated with benzene and various
chlorobenzene compounds including
chlorobenzene, di chlorobenzene and
trichlorobenzene, as well as other
contaminants, such as inorganics and
dioxins/furans. Pesticides and PCBs were
detected in a small number of samples.
Soil Gas Contamination: Soil gas was
collected during the RI and the results were
presented in the 2007 RI report, tables 4-10
and 4-11. The highest concentrations of
detected chemicals (including 160 ppmv
(parts per million by volume)
chlorobenzene, 40 ppmv benzene, 43 ppmv
1-2-dichlorobenzene) were primarily
volatile organic compounds (VOCs) the
same as or similar to those found in the plant
soils. The highest observed concentrations
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of soil gas were from the 6-inch to 4-foot
depth interval.
Northern Area Contamination: A small area
immediately north of the northern fence line
of the plant and south of the southern side of
the sedimentation pond is referred to in the
Feasibility Study Report and in this
Proposed Plan as the Northern Area (see
Figure 2). During construction of the
western stormwater basin in 2006 drum
segments and solidified puddles of
chlorobenzene were found. Because the full
extent of this contamination was not
delineated during the construction, there was
a concern that this apparent dumping might
have extended northward beyond the former
facility fence line. During the RI, soil from
the northern area was sampled and passive
soil gas samplers were deployed. Six
chlorobenzene compounds were detected at
relatively low concentrations from one of
the locations sampled in the Northern Area.
All of the passive soil gas samplers that
were deployed in this area exhibited no or
relatively low levels of contaminants.
Site Geology/Hydrogeology: Investigations
conducted during and before the RI indicate
the presence of the following subsurface
strata at the SCD Site, in descending order: a
thin layer of fill and recent deposits (native
soils), on the order of a few feet in
thickness. The fill and recent deposits are
underlain by the Columbia Formation
(Quaternary), consisting of fine sand to
coarse sand with varying amounts of gravel.
The Columbia Formation typically has a
distinct orange to yellow color. A basal
sand and gravel layer is a key marker bed
indicating the bottom of the formation.
Small lenses or stringers of silty clay or
clayey silt occur scattered throughout the
formation. In the area of OU3, the
Columbia Formation is from 55 to 74 feet
thick, with a general decrease in thickness to
the north. Beneath the Columbia Formation,
well below the vadose zone being addressed
in OU3, are the Merchantville and Potomac
Formations.
The Columbia Aquifer is the water table
aquifer immediately underlying the Site. Its
saturated thickness ranges from 10 feet north
of the former plant and near Red Lion Creek
to about 40 feet thick beneath the former
plant. The groundwater in the Columbia
Aquifer flows toward the north and
discharges into Red Lion Creek and its
surrounding wetlands.
SCOPE AND ROLE OF OPERABLE
UNIT 3 (OU3)
This action, referred to as Operable Unit 3
(OU3), will be the final action for the
vadose zone soils and soil gas in the former
plant area of the Site. The 1995 ROD
selected an interim action for groundwater
(now referred to as OU1) that called for the
containment and treatment of contaminated
groundwater in the Columbia Aquifer
beneath the Site. The 1995 ROD also
included a final remedy for treatment of
contaminated soils and sediments associated
with certain historic spills at the Site. A
future ROD (for OU4) will be the final
action for the Site and will include a final
remedy for groundwater.
SUMMARY OF SITE RISKS
The Baseline Risk Assessment (BLRA)
Report (Black & Veatch, 2007) for the SCD
Site includes detailed information on the
human health and ecological risk assessment
conducted in 2004. The complete BLRA is
part of the Administrative Record (AR) file
(see text box on the first page of this
document for AR locations). The findings
of the BLRA are summarized below.
Summary of the Human Health Risk
Assessment
The Human Health Risk Assessment
(HHRA) was conducted in accordance with
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the EPA Risk Assessment Guidance for
Superfund (RAGS) - Volume I Human
Health Evaluation Manual, Part A (EPA,
1989), Part D, Standardized Planning,
Reporting and Review of Superfund Risk
Assessments (EPA, 2001), and other
appropriate guidance (Black & Veatch,
2007).
The Site is located in the Delaware City
industrial Area and had historically been
zoned for heavy industrial use. When the
Coastal Zone Act was passed in the 1970s,
which would have prohibited heavy
industrial use, the SCD Site was among
those "grandfathered in" to allow continued
heavy industrial use. However, after the
bankruptcy of the Site's owners, the Site lost
its grandfathered status and will no longer
be eligible for heavy industrial use. Uses
including light industrial (warehousing,
trucking), commercial, open space or
parkland will be options for future land
owners. Institutional controls will be used to
prevent residential use.
Although groundwater is not a part of OU3,
the OU3 remedy will reduce the flushing of
contamination from the soils and soil gas
into the groundwater below. For that
reason, current and potential future
groundwater use is relevant. The Columbia
Aquifer groundwater beneath the Site
discharges to Red Lion Creek and soon
thereafter into the Delaware River. The
deeper groundwater beneath the Site is used
regionally as a drinking water source, but
the nearest intakes are miles away and
hundreds of feet deeper than the deepest
contamination yet found at the Site.
WHAT IS RISK AND HOW IS IT CALCULATED?
A Superfund human health risk assessment estimates
the "baseline risk". The baseline risk is an estimate
of the likelihood of health problems occurring if no
cleanup action were taken at a site. A four-step
process is used to estimate the baseline risk at a
Superfund site:
1. Analyze Contamination
2. Estimate Exposure
3. Assess Potential Human Health Dangers
4. Characterize Site Risk
In Step 1, EPA looks at the concentrations of
contaminants found at a site as well as past scientific
studies on the effects these contaminants have had on
people (or animals, when human health studies are
not available). Comparison between site-specific
concentrations reported in past studies enables EPA
to determine which contaminants are most likely to
pose the greatest threat to human health.
In Step 2, EPA considers the different ways that
people might be exposed to the contaminants
identified in Step 1, the concentrations that people
might be exposed to, and the potential frequency and
duration of exposure. Using this information, EPA
calculates the "reasonable maximum exposure"
(RME) scenario, which portrays the highest level of
human exposure that could reasonably be expected to
occur.
In Step 3, EPA uses the information from Step 2,
combined with information on the toxicity of each
chemical, to assess potential health risks. EPA
considers two types of risk: cancer risk and non-
cancer risk. The likelihood of any kind of cancer
resulting from a Superfund site is generally expressed
as an upper bound probability; for example, a "1 in
10,000 chance." In other words, for every 10,000
people that could be exposed, one extra cancer may
occur as a result of exposure to site contaminants.
An extra cancer case means that one more person
could get cancer than would normally be expected to
from all other causes. For non-cancer health effects,
EPA calculates a "hazard index," based on a
threshold derived from scientific studies. When the
hazard index exceeds 1, non-cancer effects will not
necessarily occur, but can no longer be ruled out.
Therefore, EPA will usually take action when the
hazard index is greater than 1.
In Step 4, EPA determines whether site risks are
great enough to cause health problems for people at
or near the site. The results of the three previous
steps are combined, evaluated, and summarized.
EPA adds up the potential risks from the individual
contaminants to determine the total risk from the site.
EPA evaluated exposures to people who
might drink well water in the area (or use it
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for washing or showering); as well as for
people who might come in contact with soil,
surface water, and sediment at or near the
SCD property. EPA also evaluated the risks
from eating fish or duck that might have
become contaminated from the Site. The
BLRA indicates that site-related
contamination is present in soils, soil gas,
sediment, surface water, groundwater, and
fish tissue at concentrations that present an
unacceptable cancer risk or non-cancer
hazard to human health. The BLRA's
discussions of the human health risks
associated with the OU3 soil and soil gas are
summarized below. The term "On Facility"
is used to refer to those areas within the
former plant's fence line, while "Off
Facility" is used to refer to those small areas
within OU3 but outside the plant's fence
line.
The total On Facility cancer risk for
exposure to OU3 soil and soil gas ranged
from 9.0E-04 for construction worker to
3.5E-02 for age adjusted resident. Age
adjusted resident refers to total cancer risk
from exposure to OU3 soil over a lifetime,
reflecting both child and adult exposures.
These risks exceed the EPA target risk range
of 1E-06 to 1E-04. The primary On Facility
cancer risk drivers are total 2,3,7,8-TCDD
TEQ, hexachlorobenzene, and 1,4-
dichlorobenzene in soil and 1,4-
dichlorobenzene, benzene, carbon
tetrachloride, chloroform, PCE and TCE in
soil gas. The total Off Facility cancer risk
for exposure to OU3 soil and soil gas ranged
from 8.6E-06 for construction worker to
2.0E-04 for age adjusted resident. These
risks also exceed the EPA target risk range
of 1E-06 to 1E-04. The primary Off Facility
cancer risk drivers are total 2,3,7,8-TCDD
TEQ and 1,4-dichlorobenzene in soil and
1,4-dichlorobenzene in soil gas.
The total On Facility and Off Facility hazard
indices exceeded one for industrial and
construction workers as well as adult and
child residents, indicating the potential for a
non-cancer effect. The primary On Facility
non-cancer hazard risk drivers are
1,2,3,4-tetrachlorobenzene and
1,2,4,5-tetrachlorobenzene in soil as well as
1,2-dichlorobenzene and chlorobenzene in
soil gas. The primary Off Facility non-
cancer hazard risk drivers are
1,2,3,4-tetrachlorobenzene and
1,2,4,5-tetrachlorobenzene in soil and
chlorobenzene in soil gas. Because the Off
Facility risk driver development was based
on sampling that occurred both within and
outside the Northern Area, the cancer and
non-cancer risk drivers for the Northern
Area may need to be re-evaluated if
contamination in that area is found through
additional sampling as part of the remedial
design.
Summary of the Ecological Risk
Assessment (Surface Soil)
The BLRA concluded that there are
potential risks to ecological receptors via
direct exposure to Site surface water,
sediment, and surface soil. Potential food
chain risks were identified through
incidental ingestion of sediment and surface
soil and ingestion of contaminated food
items (plants and earthworms). The risks
related to the OU3 soil are briefly discussed
here. The BLRA (Black & Veatch, 2007)
should be consulted for complete
information.
The BLRA indicated the potential for
ecological risk from site-related
contaminants in terrestrial habitats
associated with the SCD Site. These risks
include: reduced abundance and diversity of
plants and soil organisms as a result of direct
exposure to elevated contaminant levels and
potential reproductive toxicity from
bioaccumulative contaminants absorbed by
soil invertebrates and plants ingested by
terrestrial herbivores (plant eaters) and
vermivores (worm eaters).
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Contaminants in soil at concentrations that
present an ecological risk include:
Total chlorobenzenes
Hexachl orob enzene
4,4'-ODD
4,4'-DDT
Total PAHs
Fluoranthene
Phenanthrene
Pyrene
Pentachlorophenol
Aluminum
Chromium
Copper
Iron
Lead
Mercury
Nickel
Vanadium
Zinc
The BLRA indicated that uptake of
contaminants by soil invertebrates is greater
than that of uptake by plants; therefore,
vermivores would be more significantly
exposed. As a result, remedial goals that are
protective of vermivore communities will
also be protective of herbivore communities.
REMEDIAL ACTION OBJECTIVES
Remedial Action Objectives (RAOs) for the
Site are provided for the soil and soil gas in
OU3. To provide target cleanup levels that
ensure the RAOs will be met, quantifiable
preliminary remediation goals (PRGs) were
developed. The PRGs are listed in tables 2.2
and 2.3 of the OU3 Feasibility Study Report
(July 2009).
RAOs for Human Health:
• Prevent exposure to non-carcinogens
in the soil and soil gas at
concentrations that would result in a
target organ Hazard Index greater
than 1 via the potential exposure
routes of inhalation, ingestion and
dermal contact.
• Prevent exposure to carcinogens at
concentrations that would result in a
cumulative cancer risk in excess of
IxlO"5 (IE-OS) via the potential
exposure routes of inhalation,
ingestion, and dermal contact.
RAO for Environmental Protection:
• Prevent risks to ecological
communities exposed directly to the
soil COCs and indirectly via
bioaccumulation of soil COCs in
plants and earthworms.
RAO for Limiting Further Migration of
Contaminants:
• Minimize the further spread of
contamination via any of the
following major migration pathways:
0 Soil to groundwater
0 Soil to surface water
0 Soil to sediment
0 Soil to air.
SUMMARY OF ALTERNATIVES
Remedial alternatives for OU3 are presented
in this section. EPA identified and screened
a range of technologies with the potential to
address at least some portion of OU3
contamination. EPA then assembled the
technologies that passed the screening into a
series of cleanup alternatives and subjected
them to a more detailed evaluation. This
process is detailed in the OU3 Feasibility
Study Report (July 2009).
The four alternatives selected for the
detailed evaluation are:
Alternative 1 No Action
Alternative 2A Surface Cap
Alternative 2B Surface Cap with Soil
Vapor Extraction (SVE)
Alternative 2C Surface Cap with In Situ
Thermal Desorption (ISTD)
The proposed remedy for OU3 is Alternative
2A: Surface Cap. Each of the above
alternatives is presented in more detail
below.
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Alternative 1: No Action (No Cost)-The
no action alternative is included as a
baseline in the comparison of other
alternatives, as required by the NCP. No
remedial activities or institutional controls
would be implemented under this
alternative, although some level of natural
attenuation might occur.
Alternative 2A: Surface Cap ($11.5-
18.5M)-This alternative includes
construction of a cap compliant with the
applicable hazardous waste regulations. The
cap would cover 22.8 acres of the On
Facility area and would be constructed of
concrete, asphalt, or multiple layers of soil
and geosynthetic materials. The cap would
overlap the previously constructed vertical
groundwater containment barrier on the
west, south, and east sides of the On Facility
Area. On the north side, the cap border will
be the southern boundary of the Northern
Area. If it is determined that some or all of
the Northern Area is contaminated with
contaminants of concern at levels greater
than the Off Facility preliminary
remediation goals (PRGs), the northern end
of the cap will be extended to incorporate
those areas. Alternative 2A would also
incorporate Institutional Controls (ICs) to
restrict land use to commercial, light
industrial, open space or parkland use,
prevent groundwater use for commercial,
domestic and agricultural uses, require that
any construction activities minimize the
impact on the cap. These ICs could be
implemented through, for example without
limitation, zoning ordinances, restrictive
covenants and access agreements. These
ICs would be used in combination with
engineering controls such as air monitoring
and fences, and informational devices such
as signs and fact sheets to keep the public
informed of Site developments and hazards.
Additional Site preparation would be
required for cap construction because of the
remaining subsurface and surface structures
and debris located in the On Facility area.
These structures will be evaluated and,
where possible, demolished and prepared for
containment beneath the cap. In some
circumstances, either due to elevated
contaminant levels or other factors, EPA
may elect to send some of this demolition
debris off site for treatment or disposal. Care
must be taken during construction activities
to avoid damaging the previously installed
containment barrier and other interim
groundwater remedy components (including
piezometers, monitoring wells, and
extraction wells). Compliance with air
emissions limits and with stormwater and
sediment controls would be required.
Alternative 2B: Surface Cap with Soil
Vapor Extraction (SVE) ($19.1-26.2M)-In
this alternative, the surface cap and ICs in
Alternative 2A would be supplemented with
an in-situ SVE system. SVE wells would be
placed at some or all of the identified "hot
spots" and operated to treat VOCs under the
cap until no significant VOC removal (as
would be defined in the remedial design) is
being achieved. It is expected that the SVE
system would consist of several hundred air
extraction and inlet wells installed to depths
of approximately 50 feet below ground
surface. Off-gas from the SVE system
would likely need to be treated before it is
discharged to the atmosphere, most likely
with a vapor phase activated carbon
adsorption system. To enable this treatment
the extraction wells would be connected by
pipes to the off-gas treatment system. To
preserve surface cap integrity, the wells
would likely be installed before the cap is
constructed with conveyance piping being
laid in trenches installed in the ground
surface that would then be capped. Spent
carbon would be regenerated (either onsite
or offsite) for reuse or disposed of offsite.
More extensive sampling would need to be
performed to further delineate the
contaminated areas requiring treatment.
Pilot studies of the SVE system would be
required before this alternative could be
effectively implemented.
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Alternative 2C: Surface Cap with In Situ
Thermal Desorption (ISTD) ($92.8-
99.8M)-Alternative 2C includes many of
the elements of Alternative 2B (ICs, surface
cap, including further sampling, pilot studies
and vapor treatment). The main difference
for Alternative 2C is that the "hot spot" soil
areas more than 10 feet away from the soil
bentonite containment barrier would be
heated to facilitate volatilization and
removal of Semivolatile Organic
Compounds (SVOCs), PCBs, and dioxins.
The "hot spot" areas within 10 feet from the
containment barriers would be treated with
un-enhanced SVE. Based on discussions
with ISTD vendors, it is estimated that
approximately 2,800 ISTD heaters and
1,400 heated vapor extraction wells would
be placed between 8 and 12 feet apart over
the 330,000 square foot area that comprises
the "hot spots" in OU3. In the event that the
Northern Area is determined to be a "hot
spot" in need of treatment in addition to
capping, approximately 500 additional
heaters and 250 additional heated extraction
wells would be installed to address the
additional 60,000 square foot area. The
heaters and extraction wells would extend
through the 50 ft vadose zone and would
heat the soil to temperatures close to or
above the boiling points of the soil
contaminants. Soil heating for ISTD can be
achieved by several methods, including hot
air or steam injection, radio-frequency
heating, electrical resistance heating, and
thermal conduction heating. Because
temperatures in excess of 570 to 650°F
would likely be required to facilitate
volatilization of most of the SCD Site
organic compounds it is unlikely that hot air
or steam injection approaches would be
used. The volatilized organics would then
be extracted through the heated extraction
wells described above. Because of the
number of wells, the potential impacts of
heating on cap materials, the high costs of
materials required to construct heat resistant
wells, and the amount of wiring required for
the system, ISTD treatment would likely be
performed prior to the installation of the
surface cap. The ISTD wells would then be
removed or abandoned to ease cap
construction activities.
EVALUATION OF ALTERNATIVES
Nine criteria are used to evaluate the
remedial alternatives individually and
against each other in order to select a
remedy. This section of the Proposed Plan
profiles the relative performance of each
alternative against the evaluation criteria
(except the No Action Alternative, which
fails to meet the threshold criteria and is
dropped from further consideration.). Each
of the remaining alternatives is compared to
the other options under consideration. The
evaluation criteria are summarized below.
The nine criteria fall into three groups:
threshold criteria, primary balancing criteria,
and modifying criteria. A description of the
three groups follows:
• Threshold criteria, which are
requirements that each alternative
must meet in order to be eligible for
selection.
• Primary balancing criteria, which
are used to weigh major trade-offs
among alternatives.
• Modifying criteria, which may be
considered to the extent that
information is available during the
Feasibility Study, but can be fully
considered only after public
comment is received on the Proposed
Plan. In the final balancing of trade-
offs between alternatives upon which
the final remedy selection is based,
modifying criteria are of equal
importance to the balancing criteria.
10
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EVALUATION CRITERIA FOR SUPERFUND REMEDIAL ALTERNATIVES
Threshold Criteria
Overall Protectiveness of Human Health and the Environment determines whether an alternative eliminates, reduces, or
controls threats to public health and the environment through institutional controls, engineering controls, or treatment.
Compliance with certain Applicable or Relevant and Appropriate Requirements (ARARs) evaluates whether the alternative
meets the requirements of certain Federal and State environmental statutes and regulations that pertain to the site, or whether a
waiver is justified.
Primary Balancing Criteria
Long-term Effectiveness and Permanence considers the ability of an alternative to maintain protection of human health and the
environment over time.
Reduction ofToxicity, Mobility, or Volume of Contaminants through Treatment evaluates an alternative's use of treatment to
reduce the harmful effects of principal contaminants, their ability to move in the environment, and the amount of contamination
present.
Short-term Effectiveness considers the length of time needed to implement an alternative and the risks the alternative poses to
workers, residents, and the environment during implementation.
Implementability considers the technical and administrative feasibility of implementing the alternatives, including factors such as
the relative availability of goods and services.
Cost includes estimated capital and annual operation and maintenance costs, as well as present worth cost. Present worth cost is
the total cost of an alternative over time in terms of today's dollar value. Cost estimates are expected to be accurate within a
range of+50% to -30%.
Modifying Criteria
State/ Support Agency Acceptance considers whether the State agrees with the EPA's analyses and recommendations, as
described in the PJ/FS and Proposed Plan.
Community Acceptance considers whether the local community agrees with EPA's analyses and preferred alternative.
Comments received on the Proposed Plan are an important indicator of community acceptance.
The major findings of the detailed
evaluation of the four alternatives based on
the nine evaluation criteria are summarized
below: The "Detailed Analysis of
Alternatives" can be found in the Feasibility
Study Report.
1. Overall Protection of Human Health
and the Environment
Alternatives 2A, 2B, and 2C would all
reduce human health and ecological risks
from soil and soil gas to the preliminary
remediation goals developed in the
Feasibility Study Report by containing, and
preventing contact with, contamination
through the use of a surface cap. Alternative
2C would improve the level of human health
protection (specifically the health of future
construction workers or others performing
intrusive site work) afforded by the surface
cap by removing almost all organic
contamination from vadose zone soils in the
"hot spot" areas. Alternative 2B would also
provide some measure of added protection,
but would only remove VOCs and some
SVOCs from vadose zone "hot spot" soils.
Alternative 1 (No Action) would not provide
protection of the environment or human
health. As a result, Alternative 1 will be
eliminated from further consideration.
11
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2. Compliance with ARARs
Alternatives 2A, 2B, and 2C would all be
designed and implemented to comply with
the identified ARARs (shown in Table 2 at
the end of this document), with the
exception of the requirement to construct a
liner system beneath the waste. Instead, any
cap will overlap the soil bentonite
containment barrier that was constructed as
part of the interim groundwater remedy.
This barrier is keyed into a low-permeability
clay layer that lies between the contaminated
soils of the Columbia Formation and the
underlying Potomac Formation. This
method of construction will isolate the
contaminated OU3 soils from surrounding
uncontaminated areas. As a result, the
capping alternative will attain a standard of
performance that is equivalent to the
standard that would be attained through the
construction of a liner system. As a result,
this ARAR is waived pursuant to 40 CFR
Section 300.430 (f)(l)(ii)(C)(4).
3. Long-term Effectiveness and
Permanence
Alternative 2A would provide effective
containment of all contaminants located in
the soil and soil gas of OU3. Containment
would substantially reduce the risks related
to, and the potential spread of, Site
contaminants. To remain effective over the
long term, maintenance activities, including
management of vegetation and burrowing
animals and repairs of crack and erosional
features, would be required into perpetuity.
Alternatives 2B (SVE plus surface cap) and
2C (ISTD plus surface cap) would improve
the effectiveness of Alternative 2A by
reducing or eliminating organic
contaminants in the vadose zone of the
previously identified "hot spot" areas.
Because SVE would only address VOCs and
ISTD would reduce or eliminate all of the
organic contaminants in vadose zone soils in
these areas, Alternative 2C would be the
most effective over the long term.
For Alternatives 2A, 2B, and 2C,
reassessment of the effectiveness of these
alternatives would be necessary at five-year
intervals as required by CERCLA §121(c).
4. Reduction of Toxicity, Mobility or
Volume
Alternatives 2A, 2B, and 2C will all reduce
the mobility of the contaminants through the
use of a surface cap to reduce infiltration
(reducing the soil to groundwater pathway),
eliminate contact of contaminated materials
with stormwater (eliminating the soil to
sediment pathway), and containing soil gas
(eliminating the soil to air pathway).
Alternatives 2B and 2C also include
treatment technologies (SVE and ISTD,
respectively) that would reduce the volume
and toxicity of OU3 contaminants. The
greatest reduction of contaminant toxicity
and volume is expected from Alternative 2C
(combination of the surface cap and ISTD),
as it would remove VOCs, SVOCs, PCBs,
and dioxins from vadose zone soils in the
"hot spot" areas. Alternative 2B (surface
cap with SVE) would remove VOCs and
some SVOCs from the "hot spot" areas but
would not address dioxins, pesticides, and
other less volatile contaminants. Until pilot-
scale studies can be performed for the SVE
and ISTD technologies, no accurate
quantitative measure of potential
contaminant reduction can be made for
Alternatives 2B or 2C. Alternative 2A
(surface cap alone) would not reduce the
toxicity or volume of the OU3 contaminants.
5. Short-Term Effectiveness
Short-term risks to construction workers,
surrounding communities and the
environment are expected to occur from the
implementation of Alternatives 2A, 2B, and
2C. These risks include exposure to dust and
vapor during cap construction activities, as
well as continued risks from the current Site
conditions before the alternatives are fully
implemented. Alternatives 2B and 2C would
be somewhat less effective than Alternative
12
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2A in the short term because of the
increased site activities (well construction,
trenching, wiring and piping installation)
required to construct the SVE and ISTD
systems. Additionally, the SVE and ISTD
systems would increase the mobility of
organic contaminants over the short term.
Short term risks associated with Alternatives
2A, 2B, and 2C can be managed by a
combination of institutional controls,
Personal Protective Equipment (PPE), and
vapor and dust suppression measures to be
employed during construction activities.
Vapor capture and treatment systems would
address any increase in the off-gassing of
contaminants under Alternatives 2A, 2B and
2C.
It is anticipated that the planned activities
(excluding long-term O&M) for Alternative
2A could be completed within
approximately three years after issuance of a
Record of Decision. Alternatives 2B and 2C
could be completed within approximately
four years.
6. I in piemen tability
Of Alternatives 2A, 2B, and 2C,
construction of a surface cap by itself would
be most easily implemented. Although the
potable water line to the treatment building
would be rerouted so it would not pass under
the cap, this rerouting could be
accomplished using standard construction
equipment, materials, and methods. Care
would also have to be taken to avoid damage
to the existing GETS, piezometers, and
monitoring wells, but the overall cap
construction could similarly be performed
using standard construction equipment and
methods. Additionally, no further
delineation (aside from possibly in the
Northern Area) or pilot studies would be
needed before construction of a surface cap
covering all of OU3. ICs and other activities
to maintain the surface cap would be similar
under Alternatives 2A, 2B, and 2C.
The proposed treatment technologies (SVE
and ISTD) would require additional
characterization sampling to further
delineate the "hot spot areas" and the
Northern Area as well as pilot studies to
optimize well placement, blower and pipe
sizing, and, in the case of ISTD, the
temperatures that will be required to achieve
treatment of the OU3 contaminants. The
time required to construct Alternatives 2B
and 2C would also be longer than that
needed to complete the surface cap alone.
The SVE and ISTD systems would also
require controls to limit the off-gas
discharge into the air and would have to
meet the substantive provisions of air
discharge permit requirements. These
systems would also require the installation
of several hundred wells (in the case of
SVE) to over 4,000 wells (in the case of
ISTD), whereas Alternative 2A would
require installation of a small number of
monitoring wells. Alternative 2A would
also require a vapor treatment system to
meet the substantive provisions of air
discharge permit requirements for off-gas
from the cap soil gas capture system. While
SVE could be implemented using the
utilities already available onsite, it is
possible that a higher voltage electrical
supply and a natural gas supply will need to
be routed to the Site if ISTD is selected as
part of the OU3 remedy.
7. Cost
The order-of-magnitude level estimates for
total project costs (shown as present value
estimates taken over 30 years at a discount
rate of 5%) for the remaining alternatives
are shown in Table 1.
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Table 1: Summary of Alternative Costs
Alternative
Alternative 2A (Surface Cap)
Alternative 2B (Surface Cap + SVE)
Alternative 2C (Surface Cap + ISTD)
Estimated Total Project Cost (Present Worth),
million $
Multilayer Cap
$18.5
$26.2
$99.8
Concrete Cap
$17.5
$25.2
$98.8
Asphalt Cap
$11.5
$19.1
$92.8
NOTE: Because of the lack of definitive data showing that levels of contamination in the Northern Area
portion of OU3 require remediation, the costs associated with the Northern Area are not included
in the above estimates. If additional sampling shows that risks from soil and/or soil gas will
require remediation, additional costs (up to a maximum of between $421,000 and $861,000 to cap
the entire 1.4 acre Northern Area) would be incurred.
Alternative 2A is the least expensive of
these alternatives, followed by Alternative
2B and Alternative 2C. For all containment
alternatives, asphalt would be the least
expensive capping material choice, followed
by concrete and multilayer soil.
8. State/Support Agency Acceptance
The State of Delaware supports the
Preferred Alternative without comment.
9. Community Acceptance
Community acceptance of the Preferred
Alternatives will be evaluated after the
public comment period ends and will be
described in the Record of Decision for the
Site.
SUMMARY OF THE PREFERRED
ALTERNATIVE
The Preferred Alternative for OU3, the
vadose zone soils and soil gas in the former
plant area, is Alternative 2A (Surface Cap).
Based on an evaluation of the three retained
alternatives using the nine evaluation
criteria, it appears that Alternative 2A
(Surface Cap) presents the best balance of
the nine criteria in addressing the risks in
OU3. This alternative would comply with
the ARARs except where waived, and
would provide protection of human health
and the environment over the long term by
eliminating the soil and sediment exposure
pathways and substantially reducing the soil
gas exposure pathway. ICs would be used
to restrict land use to light industrial
(warehousing, trucking), commercial, open
space or parkland, and to prevent the use of
Site groundwater for commercial, domestic
and agricultural uses, ensure that remedial
measures remain in good functional
condition, and require that any construction
activities minimize the impact on the cap.
These controls could be implemented
through, among other mechanisms, without
limitation, zoning ordinances, access
agreements, restrictive covenants, and public
awareness efforts. ICs that achieve the
above outlined restrictions would be
required to increase the level of protection
and ensure that the surface cap continues to
be effective over the long term. There is no
current known risk of vapor intrusion in
future buildings that may be constructed at
the Site. Should new information become
available that would indicate that there is
such a risk then EPA will address the risk in
a new decision document. Alternatives 2B
and 2C would offer some increased
protection of human health during future
intrusive activities (e.g., construction, well
installation, and cap repair) by reducing
contaminant levels in "hot spot" soils and
soil gas, but any increased risk associated
with Alternative 2A could be managed
through the use of personal protective
14
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equipment (PPE), vapor and dust
suppression, worker training and other
precautions.
Although installation of a surface cap would
not reduce the toxicity or volume of the
OU3 contaminants, it would reduce the
mobility of the contaminants by
reducing/eliminating the infiltration of
precipitation, preventing stormwater contact
with contaminated soils, preventing the
airborne transport of contaminated soil
particles, and minimizing the potential off-
gassing of soil gases. While each of the
containment alternatives could be readily
constructed, implementation of Alternative
2A would be the easiest of the three and
could be accomplished in the shortest period
of time for the lowest overall cost.
EPA will decide which surface cap material
to use during the Remedial Design phase.
Although asphalt would be the least
expensive option and would provide
protection that should be (if properly
maintained) equal to that offered by the
concrete and multilayer soil options, a
choice must be made as to the possible
future uses of the capped area and the
importance of Site appearance. While the
concrete and asphalt caps would be
preferable if redevelopment of the Site for
some low occupancy business purpose is
envisioned, a multilayer soil cap would
likely be more visually appealing and more
amenable to conversion of the land to
parkland or open space.
COMMUNITY PARTICIPATION
EPA and DNREC will provide information
regarding the cleanup of OU3 of the
Standard Chlorine Site to the public through
public meetings, the Administrative Record
file for the Site, and announcements
published in the Wilmington News Journal,
a New Castle County newspaper. EPA and
the State encourage the public to gain a
more comprehensive understanding of the
Site and the Superfund activities that have
been conducted at the Site.
The front page of this Proposed Plan
provides the dates for the public comment
period; the date, location, and time of the
public meeting; and the locations of the
Administrative Record files.
EPA Points of Contact
Mr. Hilary Thornton
US EPA Region III
Remedial Project Manager
1650 Arch St.
3HS23
Philadelphia, PA 19103
215-814-3323
thornton.hilary@epa.gov
Trish Taylor
US EPA Region III
Community Involvement Coordinator
1650 Arch St.
3HS52
Philadelphia, PA 19103
215-814-5539
taylor.trish@epa.gov
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Table 2
Applicable or Relevant and Appropriate Requirements (ARARs)
for Standard Chlorine of Delaware Operable Unit 3 Alternatives 2A, 2B and 2C
(Page 1 of 8)
ARAR
Legal Citation
ARAR Class
Requirement Synopsis
Applicability to Remedial Alternatives
Toxic Substances
Control Act (TSCA)
40 CFR Part 761
(particularly §§1,3,61,
70,75,202-218,265,
272, 274)
Applicable
Establishes restrictions on the disposal
of bulk polychlorinated biphenyl
(PCB) remediation wastes.
This portion of TSCA will be applicable
if any soils excavated from the site
contain PCBs at concentrations greater
than 25 parts per million. This
concentration is based on the assumption
that the site is a low occupancy area as
defined in 40 CFR 761.3.
Clean Water Act
(CWA): National
Pollutant Discharge
Elimination System
(NPDES)
Requirements.
Clean Water Act, Section
402: 33 U.S.C. §1342,40
CFR Parts 122-125
Applicable
NPDES Permit Equivalence for the site
sets discharge limits for surface water
discharges from the groundwater
extraction and treatment system
(GETS) and stormwater outfalls.
The substantive provisions of these
requirements are applicable to any
portion of remedy which may affect the
water quality in the nearby wetlands or
Red Lion Creek. Previously constructed
sediment and erosion control features
will be used (and upgraded as needed) to
prevent/minimize sediment run off
resulting from construction activities.
Water discharges will be sampled and
analyzed in accordance with the NPDES
permit equivalence in place at the site,
included in Appendix B of the
Feasibility Study Report. Discharge
limits shall be met for all onsite
discharge to surface water including
stormwater and water treated by the
GETS.
Delaware Regulations
Governing Control of
Water Pollution as
amended 6/23/83
Sections 7, 8, 10
Applicable
Contain water quality regulations for
discharges into surface and ground
water.
The substantive provisions are
applicable to stormwater runoff into the
unnamed tributary and Red Lion Creek.
Also applicable to discharge of treated
ground water into surface water. These
provisions were considered in
determining the NPDES permit
equivalence limits.
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Table 2
Applicable or Relevant and Appropriate Requirements (ARARs)
for Standard Chlorine of Delaware Operable Unit 3 Alternatives 2A, 2B and 2C
(Page 2 of 8)
ARAR
Legal Citation
ARAR Class
Requirement Synopsis
Applicability to Proposed Remedies
State of Delaware
Surface Water Quality
Standards, as amended
July 11,2004.
Sections 1-7, 9, 10
Applicable
Standards are established to regulate
the discharge into state waters to
maintain the integrity of the water.
Applicable to stormwater runoff from
site. These standards were considered in
determining the NPDES permit
equivalence limits.
Coastal Zone
Management Act of
1972; Coastal Zone Act
Reauthorization
Amendments of 1990.
16USC1451etseq.;
15 CFR Part 930
Applicable
Requires that Federal agencies
conducting activities in or affecting the
coastal zone, conduct those activities in
a manner that, to the maximum extent
practicable, is consistent with the
enforceable policies of the appropriate
approved State coastal zone
management program.
The substantive requirements are
applicable to this remedial action, which
is being conducted by EPA at a facility
that is located in the Delaware coastal
zone.
Delaware Coastal Zone
Act; Delaware
Regulations Governing
the Coastal Zone
7 Delaware Code,
Chapter 70, at Sections
7002-7003;
Delaware Coastal Zone
Act Regulations of May
11, 1999, amended on
October 1,2001.
Applicable
Govern permissible activities and land
uses for properties located in
Delaware's Coastal Zone. Section
7003 of the Act sets forth the uses that
are absolutely prohibited in the Coastal
Zone. Section E of the regulations
specifically allows the, "installation
and modification of pollution control
and safety equipment for
nonconforming uses within their
designated footprint providing such
installation and modification does not
result in any negative environmental
impact over and above impacts
associated with the present use."
The Site is located in the Coastal Zone.
As a result, the substantive standards of
the statute and regulations apply to this
remedy.
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Table 2
Applicable or Relevant and Appropriate Requirements (ARARs)
for Standard Chlorine of Delaware Operable Unit 3 Alternatives 2A, 2B and 2C
(Page 3 of 8)
ARAR
Legal Citation
ARAR Class
Requirement Synopsis
Applicability to Proposed Remedies
Preservation of
Historical and
Archeological Data Act
(or Archeological and
Historic Preservation
Act of 1974)
16U.S.C.§469
Applicable
Requires that Federal agencies take
action to recover, protect, and preserve
any significant scientific, prehistorical,
historical, or archeological data that
may be irreparably lost or destroyed as
a result of the alteration of terrain
caused by Federal activities.
EPA does not currently have any
information that there are any significant
scientific, prehistorical, historical, or
archeological data at the site. If EPA
discovers that such data are present at
the site, actions will be taken to comply
with the substantive requirements of this
act.
The National Historical
Preservation Act and
regulations
16U.S.C. §470;
36 CFR Part 800
Applicable
Requirements that Federal agency
actions avoid adverse effects in historic
properties.
EPA does not currently have any
information that there are historic
properties at the site; if a determination
is made that there are historic properties
on or near the site, action will be taken
to mitigate any adverse effects on those
properties resulting from the remedial
activities.
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Table 2
Applicable or Relevant and Appropriate Requirements (ARARs)
for Standard Chlorine of Delaware Operable Unit 3 Alternatives 2A, 2B and 2C
(Page 4 of 8)
ARAR
Legal Citation
ARAR
Class
Requirement Synopsis
Applicability to Proposed Remedies
Delaware Regulations
Governing Hazardous
Waste (DRGHW)
SEE ITEMS 1 THROUGH 8
BELOW
The DRGHW provisions that
are a part of Delaware's
federally authorized program
would apply instead of the
federal RCRA regulations.
Additionally, any provision
that is not a part of the
authorized program, but that
is more stringent than the
federal requirement, would
also be applicable.
Applicable
Regulate the transportation,
management, treatment, and disposal
of hazardous wastes.
SEE ITEMS 1 THROUGH 8 BELOW
Regulations
promulgated pursuant
to the Resource
Conservation and
Recovery Act of 1976;
Hazardous and Solid
Waste Amendments of
1984
SEE ITEMS 1 THROUGH 8
BELOW
Federal RCRA regulations
would not apply for those
regulations where Delaware
has the authority from EPA to
administer. Federal citations
are also included in items 2
through 8 below because any
federal regulations that are
imposed under the Hazardous
and Solid Waste Amendments
of 1984, which are not a part
of Delaware's authorized
program, and which are
immediately effective, would
apply.
Applicable
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."
SEE ITEMS 1 THROUGH 8 BELOW
1.Identification
and Listing of
Hazardous Wastes
DRGHW Part 261
Applicable
Identifies solid wastes which are
regulated as hazardous wastes.
This part of the regulations will be used
to determine which materials must be
managed as hazardous wastes.
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Table 2
Applicable or Relevant and Appropriate Requirements (ARARs)
for Standard Chlorine of Delaware Operable Unit 3 Alternatives 2A, 2B and 2C
(Page 5 of 8)
ARAR
Legal Citation
ARAR Class
Requirement Synopsis
Applicability to Proposed Remedies
2. Standards
Applicable to
Generators of
Hazardous Waste
DRGHW Part 262
subpart A (sections
262.10-262.12) and §
262.34;
40 CFR Part 262. subpart
A (§§262.10-262.12 and
§ 262.34)
Applicable
Establishes standards for generators of
hazardous wastes including waste
determination and requirements
regarding accumulation time.
The substantive standards of the listed
sections would be applicable to the
residual waste generated by the
treatment of soils and sediments if the
waste generated by the treatment
system(s) is a RCRA-hazardous waste.
The substantive standards of the listed
sections would be applicable to
excavated soils if they are to be disposed
in an onsite landfill.
3. Standard for
Closure and Post-
Closure
DRGHW Part 264
Subpart G (Sections
264.110-264.120)
40 CFR Part 264 Subpart
G (§§264.110-264.112)
Applicable
Establishes standards for closure and
post-closure of hazardous waste
management facilities
The substantive provisions of this
subpart are applicable to the capping of
the contaminated soil at the site.
Requirements for storage of hazardous
waste in storage containers.
4. Requirements
for Use and
Management of
Containers
DRGHW Part 264
Subpart I (§§264.170-
264.179)
40 CFR Part 264 Subpart
I (§§264.170-264.179)
Applicable
The applicable substantive provisions of
this subpart are applicable for temporary
storage containers and on-site treatment
systems.
5. Standards for
owners and
operators of
facilities that store
or treat hazardous
waste in waste
piles
DRGHW Part 264
Subpart L (§§ 264.250-
264.259)
40 CFR Part 264 Subpart
L(§§ 264.250-264.259)
Applicable
Requirements for storage or treatment
of hazardous waste in waste piles.
The substantive provisions of this
subpart are applicable to any soil and
sediment that are excavated and stored
in waste piles prior to or during
treatment.
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Table 2
Applicable or Relevant and Appropriate Requirements (ARARs)
for Standard Chlorine of Delaware Operable Unit 3 Alternatives 2A, 2B and 2C
(Page 6 of 8)
ARAR
Legal Citation
ARAR Class
Requirement Synopsis
Applicability to Proposed Remedies
6. Standards for
owners and
operators of
facilities that store
or dispose of
hazardous waste in
landfills
DRGHW Part 264
Subpart N (§§ 264.300-
through 264.317)_
40 CFR Part 264 Subpart
N (§§ 264.300 through
264.317)
Applicable
Requirements for storage or disposal of
hazardous waste in landfills.
The substantive requirements of this
subpart are applicable to onsite
landfilling of soils and sediments. The
requirement to construct a liner system
will be waived. Instead, any cap will be
tied into the soil bentonite containment
barrier that was installed as part of the
IGR. This barrier is keyed into a low
permeability layer that lies between the
contaminated soils of the Columbia
Formation and the underlying drinking
water aquifer (the Potomac). This
method of construction will isolate any
contaminated OU-3 soils left under the
cap from surrounding uncontaminated
areas. As a result, the capping
alternative will attain a standard of
performance that is equivalent to the
standards that would be attained through
the construction of a liner system as
allowed under 40 CFR §
300.430(f)(l)(ii)(C)(4).
7. Air emission
standards for
process vents for
owners and
operators of
facilities that treat
or dispose of
hazardous waste.
DRGHW part 264,
Subpart AA(§§ 264.1030
-264.1034)
40 CFR Subpart AA (§§
264.1030-1034)
Applicable
Applies to process vents associated
with air stripping operations that
manage hazardous wastes.
The substantive requirements of this
subpart are applicable to treatment
options that result in air emissions of
VOCs.
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Table 2
Applicable or Relevant and Appropriate Requirements (ARARs)
for Standard Chlorine of Delaware Operable Unit 3 Alternatives 2A, 2B and 2C
(Page 7 of 8)
ARAR
Legal Citation
ARAR Class
Requirement Synopsis
Applicability to Proposed Remedies
8. Standards
Applicable to
transporters of
Hazardous Waste
DRGHW Part 263,
Subpart C
40 CFR Part 263, Subpart
C
Applicable
Establishes standards for the cleanup
of hazardous waste discharged during
transportation.
The substantive provisions of this
subpart would be applicable to residual
waste generated by the treatment of soils
and sediments, if such waste is spilled
onsite during transportation.
Delaware Regulations
Governing Hazardous
Substance Cleanup,
9/96, as amended
02/2002
Subsection 9.3
Applicable
Establishes surface water cleanup
levels.
Applicable to the cleanup of soils,
groundwater that discharges to water
bodies, and surface water at the site.
State of Delaware
Regulations Governing
the Construction and
Use of Wells, February
1997
Sections 1-6, 8-10
Applicable
Contains requirements governing the
location, design, installation, use,
disinfection, modification, repair, and
abandonment of all wells and
associated pumping equipment.
Any GETS or monitoring well
modifications or repairs needed to
implement OU3 remedy will be done in
accordance with the substantive
requirements of the well regulations. No
permits will be obtained for onsite work.
State of Delaware
Statute Regarding
Licensing of Water
Well Contractors,
Pump Installer
Contractors, Drillers,
Pump Installers, Septic
Tank Installers, Liquid
Waste Treatment Plant
Operators and Liquid
Waste Haulers.
7 Del. Code §6023
Applicable
Requires that those who install,
maintain, repair, and remove wells and
associated pumping equipment be
licensed.
Any GETS or monitoring well
modifications or repairs needed to
implement the OU3 remedy will be done
by qualified workers.
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Table 2
Applicable or Relevant and Appropriate Requirements (ARARs)
for Standard Chlorine of Delaware Operable Unit 3 Alternatives 2A, 2B and 2C
(Page 8 of 8)
ARAR
Legal Citation
ARAR Class
Requirement Synopsis
Applicability to Proposed Remedies
Delaware Sediment and
Stormwater
Regulations, 01/23/91,
as amended April 11,
2005
Section 1-3, 10, 11, 12,
13, 15
Applicable
Establishes a statewide sediment and
Stormwater management program.
The substantive provisions of this
regulation are applicable to Stormwater
from the site. No permits or plans will
be obtained or prepared.
Delaware Air Quality
Management
Regulations
Air Quality Management
Regulations Number
1102 (Section 11.6), 3
(sections 3 and 11), 6, 19,
24
Applicable
Regulation No. 1102 sets forth the
permitting requirements for equipment
and construction activities that may
discharge air contaminants into the
atmosphere. Regulation No. 3, sections
3 and 11, establish ambient air quality
standards for particulates. Regulation
No. 6 limits paniculate emissions from
excavation/ construction operations.
Regulation No. 19 requires that
odorous air contaminants be
controlled. Regulation No.24 requires
the control of emissions of the volatile
organic compounds.
Applicable to potential releases from
soil vapor extraction (SVE), soil gas
capture systems, excavation work, or
other remedial actions. If air stripper,
SVE, or soil gas system emissions
exceed 15 Ibs/day, the substantive
requirements of regulation No. 24 must
be met. In addition, the emissions must
meet the Ambient Air Quality Standards
set forth in Regulation No. 3. Dust
suppression measures must also be in
place to ensure that excavation and
construction activities meet the
regulation requirements. Furthermore,
the substantive requirements of
Regulation No. 1102 must be met.
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