PB94-963724
EPA/ROD/R01-94/100
May 1995
EPA Superfund
Record of Decision:
Old Southington Landfill
(O.U. 1), Southington, CT
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o
RECORD OF DECZSZON
OLD SOUTHZNGTON LANDFZLL SUPERFUND SITE
Southinqton, Connecticut
ZNTERIH REMEDIAL ACTION FOR
LIHZTED. SOURCE CONTROL
SEPTEMBER 1994
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RECORD OF DECISION
OLD SOUTHINGTON L;_~DFILL
Contents
TABLE OF CON'I'E~S
Paae Number
DECLARATION FOR THE RECORD OF DECISION
I.
II.
III.
IV.
V.
VI.
VII.
VIII.
IX.
X.
XI.
XII.
. . . . . .
. . iii
SITE NAME, LOCATION, AND DESCRIPTION
. . . . . .
. . .
SITE HISTORY & ENFORCEMENT ACTIVITIES.
A. Land Use and Response History
B. Enforcement History.
. . . . .
. . .
........
. . .
. . .
COMMuNITY PARTICIPATION.
. . .
. . .
SCOPE AND ROLE OF RESPONSE ACTION. . . . . . . . . . .
SUMMARY OF SITE CHARACTERISTICS
SUMMARY OF SITE RISKS. .
............
. . . . . .
. . .
. . . . . .
DEVELOPMENT AND SCREENING OF ALTERNATIVES. . . . . . .
A. Statutory Requirements/Response Objectives. . . .
B. Technology and Alternative Development and
Screening. . . . . . . . . . . . . . . . . . . . .
DESCRIPTION OF SOURCE CONTROL ALTERNATIVES. . . . . .
SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES
THE SELECTED REMEDY FOR LIMITED SOURCE CONTROL
. . . .
STATUTORY DETERMINATIONS. . . . . . . . . . . . . . .
A. The Selected Remedy is Protective of Human Health'
and the Environment. . . . . . . . . . . . . . .
The Selected Remedy AttainsARARs . . . . . . . . .
The Selected Remedial Action is Cost-Effective
The Selected Remedy Utilizes Permanent Solutions
and Alternative Treatment or Resource Recovery
Technologies to the Maximum Extent Practicable
E. The Selected Remedy does not satisfy the
Preference for Treatment which Permanently and
Significantly Reduces the Toxicity, Mobility or
Volume of the Hazardous Substances as a Principal
Element. . . . . . . . . . . . . . . . . . .
B.
c.
D.
DOCUMENTATION OF NO SIGNIFICANT DIFFERENCES
. . . . . .
XIII. STATE ROLE
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APPENDIX A
APPENDIX B
\PPENDIX C
APPENDIX D
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RESPONSIVENESS SUMMARY(~~\ ~~~~~~~~)
RISK ASSESSMENT TABLES 2 THROUGH 10
CONNECTICUT DEPARTMENT OF ENVIRONMENTAL
CONCURRENCE LETTER
ARARS TABLES
PROTECTION
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SITE NAME AND LOCATION
Old Southington Landfill
Old Turnpike and Rejean Road
southington'Connecticut
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected interim remedial
action for limited source control for the Old Southington
Landfill Superfund Site (Site), in Southington Connecticut. This
decision document was developed in accordance with the
Comprehensive Environmental Response, Compensation and Liability
Act of 1980 (CERCLA), as amended by the Superfund Amendments and
Reauthorization Act of 1986 (SARA) and with the National Oil and
Hazardous Substances Pollution Contingency Plan (NCP). The
remedy selected in this document will prevent or reduce the '
threat to human health and the environment posed by the presence
of the landfill through the implementation of a limited source
control, action. This decision is based upon the contents of the
Administrative Record for this Site. A copy 'of the
Administrative Record is available at the Southington Library, in
Southington, Connecticut and at the United States Environmental
Protection Agency's Office in Boston, MA.
The Connecticut Department of Environmental Protection concurs
with the selected remedial action.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substance from this
Site, if not addressed by implementing the response action
selected in this Record of Decision (ROD), may present a current
or potential threat to human health and the environment.
DESCRIPTION OF SELECTED REMEDY
The selected remedy addresses in part remediation of the source
of contamination at the Old Southington Landfill by eliminating
or reducing the risks posed by he presence of the landfill at the
Site. Subsequently, additional groundwater studies will be
performed and a final remedy will be selected that will address
'groundwater contamination at and off-site. A Record Of Decision
will be issued for the final groundwater remedy.
The major components 'of the selected remedy include:
Removing all residential and commercial structures from
the landfill and off-site relocation of all affected
residents and businesses;
Excavating and consolidating discrete semi-solid
materials from semi-solid disposal area 1 (SSDA1)
(including a two-foot buffer zone around these
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materials) to prevent wastes below the water table from
further contaminating the groundwater;
Constructing a .low permeability cap over all .of the
landfill area to reduce the amount of water entering
the site waste and implementing engineering controls to
minimize erosion and manage surface water run-on and
run-off.
Installing a gas collection and, if necessary,
treatment system to prevent landfill gas build-up under
the cap and to collect the landfill gases;
Implementing a monitoring plan to determine the long-
term effectiveness of the cap on groundwater, surface
water and sediment quality, and the effectiveness of
the soil gas collection system;
Developing and implementing institutional controls,
which could include fencing, to ensure the integrity of
the remedy by controlling future. site use and accessj
Performing five year reviews.
STATUTORY DETERMINATIONS
The selected remedy is protective of human health and the
environment, complies with Federal and State requirements that
are applicable or relevant and appropriate to the interim
remedial action, and is cost-effective. This limited source
control ir~erim remedial action utilizes permanent solutions and
alternati treatment technologies to the maximum extent
practicar The selected remedy does not satisfy the statutory
preference for remedies that employ treatment that reduces
toxicity, mobility, or volume as a principal element because
treatment of the entire landfil~ area is impracticable. The
selected remedy will reduce mobility of contaminants through its
containment features. Because this remedy will result in
contaminants remaining at the Site above levels that allow for
unlimited use and unrestricted exposure, the interim remedia1
action will be reviewed to the extent required by law to assure
that it continues to protect human health and the environment.
In addition, pursuant to this interim ROD, additional groundwater
studies will be required and shall proceed concurrently with the
implementation of this remedy. The purpose of these studies will
be to define the boundary of the plume and determine if the plume
is impacting any natural resource areas. Groundwater monitoring
data collected from the interim remedy will be reviewed by the
~gencies. This data, in conjunction with the results of the
additional groundwater studies, will be used to evaluate
groundwater remedial alternatives so that EPA, in consultation
with CTDEP, will be able to determine an appropriate final
remedy.
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The following represents the selection of a remedial action by
the United States Environmental Protection Agency, Region I, with
concurrence of the Connecticut Department of Environmental
Protection.
By:
~l~
..;
"\
\~~
Date:
<1 f 7...L I q 4-
'.
Title:
John P. DeVillars
Regional Administrator
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RECORD OF DECISION
I~;-:E?.I::1 RE=-!E:)I.~..L ,;I..CTICN FOR
LIMITED SvL~CE CONTROL
OLD SOwT~:NGTON L~~DFILL SUPE?.=w~~ SITE
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SITE N&~E, LOCATION, AND DESC?.IPTION
The 014 Southington Landfill S~?e=fund Site (Site) is
a?proxi~ately 11 ac=es and is located in Southington,
Connecticut, (see Figu=e 1). The site abuts Old Turnpike Road to
the west, Rejean Road to the nc=th, Black Pond with associated
~etlands t the east and northeast, and industries to the south
(see Figu: ~). The Site is lccated in a mixed industrial,
commercia. ~nd residential area. There are currently seven
commercial ..:...d industrial buildings, and t."o residential hOl:1es on
the Site. ~"o othe= homes were de~olished and re~oved from the
site, one in July 1993 and the other in January 1994. ~i
interwittent, unnamed stream flows westerly from Black Pond
through a culvert, under the landfill and Old Turnpike Road and
eventually discharges to a wetland west of the Site.'
A more complete description of the Site can be found in the
Remedial Investigation/Feasibility Study (RI/FS) Report Section
1.0. These documents are part of the Administrative Record which
is available at the Southington Library site ~epository, and at
the Environmental Protection Agency's Boston office.
II.
SITE HISTORY & ENFORC~~ENT ACTIVITIES
..
zo. .
"Land Use and Response History
There are currently two private residences located on the
r.orthern part of the Site. The Southern portion of the Site has
five commercial businesses and one town facility. Four of t.~ese
businesses have buildings located' within the footprint of the
landf~ll. They are: R.V. & Sons Welding, Northeast Machine,
Southington Metal Fabricating Company (three structures), and
Solo~on Casket Company. The landfill encompasses part of the
fifth business prope=ty, namely, Meriden Box, but the building is
not located on the landfill. The Town of southington owns and
operates the Parks and Recreation Building. It too is located on
the landfill.
The Old Southington Landfill operated as a municipal and
industrial landfill between 1920 and 1967. During that period,
~ixed residential, cOw~ercial a~d industrial solid a~d liquid
wastes were disposed of at the landfill. The northern, now
residential, area 0: the landfill ~as used primarily for disposal
and burning of municipal waste consisting primarily of wood and
construction debris. The southern, now industrial, area received
r.unicipal, commercial and industrial wastes. Two areas in the
southern portion of the landfill are known to have been used for
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SOURCE:
I
Ii
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FIGURE 1
OLD SOUTHINGTOH LANDFLL
StI'ERfUN) SITE
SCX1T1tNGTON, CONNECTICUT
o
1000
2000
LOCATION ~AP
COI+EC'nC1JT'
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e IJ08
e
CZ-14
I..SGEHJ:
AGURE 2
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'TIFI.S WCNTORN3 WELL. a.usTEM
SN3.E 1oICNT0RN1 wa.s.:
e
SSDA 1 . sa.SQU) iXsPosAa. Na
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100 - zoo
600
OLD SOUTHINGTON LANDRLL
SUPERFUND SITE
...
. .
WE1UN)S
SCAU: 1M n:::'
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the disposal of aqueous, semi-solid and semi-liquid wastes.
These areas, namely Semi-Solid Disposal Area 1 (SSDA1) and Semi-
Solid Disposal Area 2 (SSDA2), are located just east of Old
Turnpike Road as shown on Figure 2.
In 1967, the Town of Southington (Town) closed the landfill and
placed an approximately 2 foot thick soil cover over the Site.
In 1971, municipal Well No.5 was installed approximately 700
feet northwest of the Site. From the early 1970s to the 1980s,
the landfill property was subdivided, and developed into
residential, indu~trial and commercial properties. In 1979, W~ll
No.5 was deactivated due to exceedence of water supply
guidelines, including 1,1,1-trichloroethane by the Connecticut
Depart~ent of Public Health and Addiction Services (CT DPHAS),
(formerly called the Connecticut Department of Health Services) .
Well No.5 was decommissioned and municipal water was supplied to
the local community from another source.
Several preliminary investigations were .performed by the u.S.
Environmental Protection Agency (EPA) and the Connecticut
Department of Environmental Protection (CT DEP) in 1980.
Groundwater samples from two monitoring wells installed between
the Site and Well No.5 contained chlorinated volatile organic
compounds (VOCs). Soil samples from a manhole excavation on land
that had once been part of the landfill showed the presence of
chlorinated and non-chlorinated VOCs. In 1984, the Site was
formally listed on the National Priorities Lists (NPL).'
A more detailed description of the Site history and previous
investigations can be found in the Remedial Investigation Report
Section 1. 3 . 3 .
B.
Enforcement History
State Enforcement Activities
The Connecticut Health Department sampled Southington Production
Well No.5. on several occasions between December of 1978 ancl
March of 1979. Sampling indicated that Well No.5 was
contaminated with hazardous chlorinated organic compounds:,
including trichloroethylene and 1,.1,1-trichloroethane. As a
result of this contamination, Well No.5 was closed in August of
1979. .
On November 12, 1980, the Connecticut Department of Environmental
Protection collected soil samples of materials from a manhole
excavation in the industrial park which was built on the Site.
Contaminants detected include the hazardous substances
chlorobenzene, carbon tetrachloride, chloroform, toluene, and
xylene. .
On September 21, 1984, the Connecticut Department of
Environmental Protection (CT DEP) signed a Consent Order with the
Town of Southington. Under that Order~ as modified on December
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16, 1985, the Town was required to investigate a portion of the
contamination at the ~,~ndfill. Subsequently, GOldberg-Zoino &
Associates (GZA) was retained by the Tow~ to conduct a
hydrogeologic study pursuant to that Order.
In'August 1992, a~ agreement was signed by the Connecticut
. Department of Environmental Protection and the Town of
~.::,uthi.:-.~ ".... to implement a landfill gas monitoring and mitigation
plan at the Site. The plan is being administered by the
southington Fire Department and Potentially Responsible Parties.
The plan consists of monitoring all homes and businesses on site
for methane and'other landfill gases. If such gases are detected
inside the buildings, appropriate mitigating measures are taken
to prevent further gas migration. '
Federal Enforcement Activities
On September 29, 1987, three Potentially Responsible Parties
(PRPs), the Town of Southington, United Technologies Corporation,
Pratt & Whitney Division and Solvents Recovery Service of New
England, Inc. (SRSNE) signed an Administrative Order by Consent
to perform the RIfFS. At some time after 1987, SRSNE stopped
participating after it became insolvent. In 1989, General
Electric also agreed to participate in the performance of the
RIfFS. The RIfFS was completed in December 1993. In May 1994,
EPA issued an Addendum to the RIfFS. Both documents are part of
the Administrative Record.
In January 1993, EPA notified approximately 320 parties of their
potential liability with respect to the Site. The liability of
these parties was premised on evidence which suggested that these
PRPs either owned or ope~ated the facility, generated wastes that
were shipped to the facility, arranged for the disposal of wastes
at the facility, or transported wastes to the facility.
III. COMMUNITY PARTICIPATION
Throughout the site's history, community concern and involvement
has been high. EPA has kept the community and other interested
parties apprised of the Site activities through informational
meetings, fact sheets, press releases and public meetings.
In October 1988, EPA released a community relations plan which
outlined a program to address community concerns and keep
citizens informed and involved in remedial activities. On
December 14, 1988, EPA held an informational meeting in the
Southington Public Library in southington, Connecticut to
describe the plans for the Remedial Investigation and Feasibility
study. On August 26, 1992, EPA held a~ informational meeting in
Southington, Connecticut to discuss the methane gas problem at
the Site.
On May 23, 1994, EPA completed the administrative record which
includes documents that were used by EPA to propose the remedy
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for the Site. These documents are available for public review at
EPA's offices in Boston, Massachusetts and at the site repository
at the Southington Public Library in Southington, Connecticut.
EPA published a notice and brief description of the Proposed Plan
on June 1, 1994 in the Meridian Record Journal and on June 2,
1994 in the Southinaton Observer. The proposed plan was made
. available to the public on May 23, 1994 at the Southington PUblic
Library. .
On June 14, 1994, EPA held a public meeting to discuss the
results of the Remedial Investigation, the cleanup activities
presented in the Feasibility study and to present the Agency's
Proposed Plan. Also during this meeting, the Agency answered
questions from the public. From June 15, 1994 to July 14, 1994,
the Agency held a 30-day public comment period to accept written
comments on the alternatives present~d in the Feasibility Study,
the Proposed Plan, and on any other documents previously released
to the public. On June 29, 1994, residents of the Southington
community requested a 30-day extension of the public comment
period to August 13, 1994, which was granted by EPA.
On July 12, 1994, the Agency held a public hearing to discuss the
Proposed Plan and to accept oral comments. A transcript of this
hearing and comments, along with the Agency's response to
comments are included in the Responsiveness Summary found in
Appendix A of this Record of Decision (ROD).
IV.
SCOPE AND ROLE OF RESPONSE ACTION
The selected remedy is an interim remedy which will address, in
part, the source of contamination at the Site. Source control
remedies prevent or minimize the continued release of hazardous
substances to the environment and rely on the prevention of
exposure for the protection of human health and the environment.
Subsequent groundwater studies will be required that will define
the extent of the plume and determine if the plume is impacting
any downgradient natural resource areas. Monitoring data. .
collected from the interim remedy will also be used to evaluate
improvements in groundwater quality resulting from construction
of an impermeable cap and excavation and consolidation of
discrete materials found in SSDA1. EPA will determine when and
if a meaningful trend in groundwater quality has been
established. This information will be useful in developing
groundwater remedial alternatives that address groundwater
remediation at and off-site. The selection of any necessary
groundwater remediation will be addressed in a final remedy.
In summary, EPA's selected interim remedy includes: 1)
permanently relocating the affected businesses and residences and
removing. all buildings from the landfill, 2) excavating and
consolidating discrete, highly contaminated materials currently
located in semi-solid disposal area 1 (SSDA1) into a lined
disposal cell to .be constructed elsewhere within the landfill,
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3) constructing a low permeability cap over all of the landfill
area to reduce the amount of precipitation from contacting the
site waste, 4) placing waste from Black Pond underneath the cap,
5) installing a gas collection system (and potential treatment
system) to control landfill gas build-up under the cap and
migration off-site, 6) implementing a monitoring plan at and near
the Site to monitor the effectiveness of the limited source
control remedy by monitoring soil gas, groundwater, surface
water, and sediment, and, 7) implementing institutional controls
to restrict future use of the Site. Five year reviews of this'
limited source control plan will also be included as part of this
selected remedy. .
Potential future exposure to contaminated subsurface soils will
be minimized by capping the landfill with a low permeability
cover. Potential exp9sure to landfil~ gases will be minimized
through the installation of a gas collection system (and
potential treatment system) that will also control potential
migration of gases. The required long-term monitoring will
ensure that the selected source control remedy remains protective
of human health and the environment.
v.
SUMMARY OF SITE CHARACTERISTICS
Investigations were conducted at the site to determine the nature
and extent of contamination resulting from landfilling
activities. Actions undertaken. to meet this objective included:
conducting interviews with former landfill anQ town employees;
reviewing Town and state records; reviewing historical aerial
photographs of the Site; installing test borings to determine .the
landfill boundary; installing monitoring wells; and sampling
groundwater, surface water, sediment,. soil gas, and surface and
subsurface soils. .
The PRPs who signed the Administrative Order on Consent to
perform the RIfFS (RIfFS PRP Group), under EPA direction'and
oversight, initiated the first phase of field investigations to
determine the extent of landfill contamination in the fall of
~988, and completed them in November 1991. The RIfFS PRP Group
conducted the second phase of field investigations in May 1992;
this phase was completed in January 1993. Additional subsurface
soil investigations were conducted in October 199J at a location
referred to as Semi-Solid Disposal Area 1 (SSDA1), where disposal
of liquid and semi-solid wastes had occurred (see Figure 2 .for
SSDAl location).
The information gathered in all phases was used to prepare the
RIfFS for all aspects' of the Site. However, during the
evaluation of the RIfFS documents, EPA andCT DEP determined that
insufficient information on the extent and nature of the
groundwater contamination had been compiled. Additional
groundwater studies will be necessary in order to determine an
appropriate final remedy at the Site. Therefore, the RIfFS dated
December 1993, along with an addendum to the Feasibility Study
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(FS) that was prepared by the EPA and issued in May 1994, is
being used by EPA to select an interim remedy. The major
conclusions and results of this RI are summarized below. These
results are presented in detail in the RI Report (Volumes IA
through IE). .
Contaminant concentrations discussed below are compared to levels
in samples taken from areas not affected by the landfill, known
as background samples, or, in the case of groundwater samples, to
existing federal and state drinking water standards, known as
maximum contaminant levels (MCLs).
Subsurface Soil/Landfill Wastes
A total of 108 soil borings were drilled to determine the
boundaries of the landfill, the thickness of the landfill wastes,
and the types of contamination present in the subsurface soils
and landfill wastes. The borings were drilled to depths ranging
from 9 to 60 feet below ground surface. The approximate boundary
of the landfill is shown in Figure 2.
The test results indicated that different types of waste disposal
activities were conducted-in specific areas of the landfill. The
landfill area can generally be divided into the following areas
as shown on Figure 2: the northern area (currently residential),
the southern area (currently commercial/industrial) and two
Semi-Solid Waste Disposal Areas (SSDAs) known as SSDA1 and SSDA2.
The northern area of the landfill was primarily used for disposal
of wood stumps and construction-type debris such as glass, bricks
and asphalt. Some or all of the debris in this area was burned,
resulting in the formation of polynuclear aromatic hydrocarbons
(PAHs), a type of semi-volatile organic compounds (SVOCs).
Subsurface soils contain varying levels of PAHs.
The southern area of the landfill was used for the disposal of
both municipal, commercial, and industrial wastes. Soil samples
collected from borings in this area contained primarily metal,
paper, plastic, and glass. Chemical analysis of this area's
subsurface soils indicates a wide variety of contaminants
including volatile organic compounds (VOCs), SVOCs and metals.
Pesticides were also detected in a few of the samples.
SSDAI and SSDA2 were excavations located in the southern area of
the landfill that were used for a period of time for the disposal
of liquid and semi-solid industrial wastes. Samples collected
from SSDAI and SSDA2 contained high levels of VOCs such as
toluene, ethylbenzene, xylenes, 1,2-dichlorethene,
tetrachloroethene, and trichloroethene. Two visually distinct
industrial-type wastes designated as "discrete materials A and
B", were found in SSDAI. Discrete material A is a white,
Putty-like material, and discrete material B is a thick, brown,
grease-like material. Samples of these industrial-type materials
contained very high levels of VOCs and SVOCs. The high levels of
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contamination found in SSDA1 make this area a "hot spot" of
contamination in the landfill. Borings in SSDA2 did not"
encounter the discrete industrial-type wastes found in SSDA1.
Surface Soil
Forty surface soil samples were collected from the landfill area
and three ba: --~und locations. Sixteen of these were collected
from the northern area of the site. No VOCs were found in
surface soil samples collected in the northern area. However,
VOCs were found in several areas of the southern portion of the
landfill.
The major contaminants of concern found in surface soils were
SVOCs, which were detected in a large number of samples collected
across the Site. The majority of these SVOCs were PAHs which
were detected above background levels in both the northern and -
the southern areas. Low levels of pesticides were detected in
soil samples collected from the landfill surface in both the
northern and southern areas of the landfill.
Background levels of metals were detected in many of the surface
soil samples. Several samples collected in the southern
industrial area of the landfill were found to have contained
metals (arsenic, lead and mercury) that were above background
levels.
Landfill Gases
Methane and other landfill gases have been measured in soils at
the Old southington Landfill since 1985. In November 1991, EPA
was notified by CT DPHAS that gases were detected in floor cracks
of the Parks & Recreation Building, and that two employees from
the Southington Metal Fabricating Company had complained of
" illness (See Figure 2 for building locations). A landfill gas
monitoring and mitigation program is " in place at the landfill.
It is being administered by the RIfFS PRP Group and the
Southington Fire Department (SFD) through an agreement with CT
DEP and in consultation with the EPA, CT DPHAS, and the Agency
For Toxic Substances and Disease Registry (ATSDR). The program
consists of on-site alarms in every home and business with
regular monitoring by the SFD and Environmental Services and
Engineering Inc. (ESE) (RIfFS PRP Group consultant). If landfill
gases are detected migrating inside any of the homes or
businesses, appropriate measures are taken to mitigate the
problem. To date, methane has not been detected in any of the
homes on the landfill, but has been detected inside some of the
commercial buildings from time to time. This monitoring and
mitigation program is only a temporary one until the interim
remedy is implemented and the gas migration is permanently
controlled.
. Soil gases from the landfill have also been sampled for
combustible gases and VOCs as part of the RI. These samples were
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collected from two to eight feet below ground surface depending
on the elevation of the water table. Combustible gases were
measured at 110 locations. High levels of these gases were
recorded at about 55 test locations. Most of the high readings
were detected in the southern area of the landfill.
Soil gases were also measured for the presence of specific VOCs
at 23 of the locations. The highest levels of VOCs detected in
soil gas were found in the southern area of the landfill that
received municipal and industrial wastes. Of the sixteen soil
gas samples collected in the northern residential area of the
Site, seven were found to have detectible levels of VOCs. Some
of the VOCs detected include benzene, ethylbenzene, toluene,
vinyl chloride and xylenes.
Groundwater
Groundwater samples from 57 monitoring wells -installed in the
landfill study area (see Figure 2) were analyzed for VOCs, SVOCs,
Pesticides/PCBs, and Metals. Sampling results indicated that
several VOCs, including vinyl chloride, trichloroethene,
1,2-dichloroethene, ethylbenzene, toluene, and xylenes were
present in the groundwater both at the landfill and to the west
of the landfill (downgradient). Most of the VOCs were present at
levels many times higher than MCLs.
SVOCs in groundwater were detected at only two locations and were
generally found at much lower concentrations than the VOCs.
Some of the SVOCs found include dichlorobenzenes and various
types of phenol and phthalate compounds. Groundwater collected
from two locations just west of the landfill contained traces of
pesticides at concentrations below MCLs. Polychlorinated
Biphenyls (PCBs) were detected in one well at concentrations
above the MCL.
The groundwater sampling results indicated that metal
concentrations exceeded background levels in wells both at and
west of the landfill (downgradient). Many of these metals were
also found in several wells at levels that exceeded MCLs. These
included antimony, barium, beryllium, cadmium, chromium, copper,
lead, mercury, nickel, silver and thallium. Although an extensive
groundwater investigation has been performed in the vicinity of
the Site, additional groundwater studies are necessary before a
final remedy can be determined.
Surface Water
VOCs and SVOCs were found at levels below or near MCLs in surface
water samples collected from Black Pond and its outlet stream.
Most metals occurred at or below background levels and MCLs.
Antimony, cadmium, lead and thallium MCLs were each exceeded at
least once.
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Levels of metals dete=~ed ~.n surface water samples were also
compared to federal ambie~ water quality criteria (AWQC),
standards established to be protective of aquatic life. Copper,
lead and zinc exceeded these standards in some of the surface
w~ ~r samples that were collected.
Sediments
Sediment samples collected from Black Pond and its outlet stream
were found to contain VOCs such as carbon disulfide,
1,2-dichloroethene, toluene and trichloroethene. SVOC analysis
indicates the presence of PAHs at levels above background
concentrations. PCBs were also found in three of the sediment
samples collected. Concentrations of metals, including lead,
mercury, and vanadium were higher than background levels.
Hydroqeoloqy
The water table at the landfill varies from about 2 feet to 34
feet below the ground surface. It is shallower near the pond to
the north and deeper to the south of the site~ Landfill wastes
are +ocated both above and below the water table depending upon
the specific area of the Site. Based on the data collected
during the RI, ~it is estimated that approximately two-thirds of
the landfill waste is located above the water table. A portion
of the material in SSDA1 is located at or below the water table
(depending on seasonal water table fluctuations). All of the
material in SSDA2 is located above the water table. Waste
located below the water table acts as a continuing source of
contamination to the groundwater. Contaminated soils located
above the water table also act as a source of contamination to
groundwater as precipitation and snow melt infiltrate down
through the waste transporting contamination to it.
The regional groundwater flow is westerly toward the Quinnipiac
River. Studies undertaken thus far show that contaminated
groundwater in the unconsolidated aquifer migrates in a westerly
direction from the landfill. The majority of the unconsolidated
groundwater aquifer is comprised of sand which allows groundwater
to flow through the sand easily. The plume of contaminated
groundwater is known to have migrated to monitoring well clusters
B-308 and B-309 at the western edge of Chuck & Eddie's Used Auto
Parts, the property located directly west of the landfill (see
Figure 2).
VI.
SUMMARY OF SITE RISKS
A human health baseline risk assessment was performed to estimate
the probability and magnitude of potential adverse human health
and environmental effects from exposure to contaminants
associated with the Site. The public health risk assessment
followed a four step process: 1) contaminant identification,
which identified those hazardous substances which, given the
specifics of the site were of significant concern; 2) exposure
1>94-178
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assessment, which identified actual or potential exposure
pathways, characterized the potentially exposed populations, and
determined the extent of possible exposure; 3) toxicity
assessment, which considered the types and magnitude of adverse
health effects associated with exposure to hazardous substances;
and 4) risk characterization, which integrated the three earlier
steps to summarize the potential and actual risks posed by
hazardous substances at the Site, including carcinogenic and non-
carcinogenic risks. The results of the public health risk
assessment for the Old Southington Landfill Superfund Site are
discussed below followed by the conclusions-of the ecological
risk assessment.
Thirty-two chemicals in groundwater, 21 chemicals in northern
surface soils, 21 chemicals in southern surface soils, 20
chemicals in on-site sediments, 17 ~hemicals in off-site
sediments, 9 chemicals in surface water and 12 chemicals in air.
were selected as contaminants of concern for evaluation in the
risk assessment. Table 1 below presents the contaminants of
concern for groundwater. Tables 2 through 10 in Appendix B of
this Record of Decision presents the contaminants of concern for
all other media.
f)
These contaminants constitute a representative subset of the 42
chemicals in groundwater, 42 chemicals in northern surface soils,
36 chemicals in southern surface soil, 49 chemicals in on-site
sediment, 41 chemicals in off-site sediment, 23 chemicals in
surface water and 12 chemicals in air identified at the Site
during the Remedial Investigation. The contaminants of concern
were selected to represent potential Site related hazards based
on toxicity, concentration, frequency of detection, and mobility
and persistence in the environment. A summary of the health
effects of each of the contaminants of concern can be found in
Appendix D of the Human Health Risk Assessment Report (HHRA).
Potential human health effects associated with exposure to the
contaminants of concern were estimated quantitatively or
qualitatively through the development of several hypothetical
exposure pathways. These pathways were developed to reflect the
potential for exposure to hazardous substances based on the
present uses, potential future uses, and location of the Site.
Currently, the Site consists of residential, commercial and
industrial properties. Two residences are located in the
northern portion of the Site and seven commercial/industrial -
buildings are located on the southern portion of the Site. In
the future, the landfill will be capped so that industrial,
commercial, or residential use of the Site will not occur.
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TABLE 1: SUMMARY OF CONTAMINANTS
OF CONCERN IN GROUNDWATER
contaminants
of Concern
antimony
aroclor 1248
aroclor 1254
aroclor 1260
arsenic
barium
benzene
beryliium
Qis(2-ethylhexyl)
phthalate
butylbenzylphthalate
cadmium
carbon disulfide
chloroform
chromium, hexavalent (1)
chlordane (gamma)
l,2-dichloroethene
(total)
ethylbenzene
lead
manganese
mercury
methylene chloride
nickel
silver
tetrachloroethene
thallium
toluene
l,l,l-trichloroethane
trichloroethene
vanadium
vinyl chloride
xylenes (total)
zinc
Average
Concentration
(mer 11)
Maximum
Concentration
( mer 11)
0.84
0.001
0.014
0.008
0.05
19.4
0.066
0.04
Frequency
of Detection
0.06
0.0004
0.001
0.001
0.005
1.24
0.005
0.003
12/58
1/34
2/34
1/34
22/58
58/58
16/112
24/58
6/42
3/42
.13/58
13/112
21/112
31/58
2/34
0.03
0.008
0.03
0.008
0.009
0.11
0.00003
0.7
0.13
0.95
0.13
0.11
1.17
0.0001
1.08
0.31
0.45
4.79
0.0004
0.007
0.21
0.03
0.006
0.002
0.57
0.06
0.15
0.17
0.075
0.34
1.25
33
10
15.4
116
0.006
0.13
4.39
0.9
0.062
0.017
23
1.8
5.4
2.29
3.45
13
38.2
34/112
15/112
46/58
54/58
18/58
2/112
32/58
13/58
10/112
2/58
27/112
8/112
26/112
36/58
20/112
21/112
58/58
(1)
Based on total chromium analyses, assumed to be 100%
hexavalent chromium.
094-178
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Passive recreation might be allowed on the northern part of the
site, so long as the integrity of the cap and its' associated
components are not compromised. Currently, the land use north of
the Site is residential, west of the Site is mainly commercial
and industrial, south of the Site is a mixture of residential and
light industrial, and east of the Site are wetlands, some
industries and residences. In the future the land use in the
areas surrounding the Site is expected ,to stay essentially the
same with perhaps a small increase in residential development.
The following is a brief summary of the exposure pathways
evaluated. A more thorough description can be found in Section
4.0 of Volume 2A of the HHRA Report. To evaluate exposure to
contaminated groundwater, a young child (1-6 years), older child
(6-18 years) and an adult (18-30 years) were assumed to ingest 2
liters of water per day for a total of 30 years. Dermal contact
and incidental ingestion of northern surface soils was evaluated'
for a young child, an older child and an adult who would be
exposed 150 days per year for a total of 30 years. Dermal
contact and incidental ingestion of southern surface soils was
evaluated for an adult worker who would be exposed 250 days per
year for 25 years. Subsurface soils were not evaluated because
the presumptive remedy was used. Under the presumptive remedy
the Site will be capped and will prevent future exposure to
subsurface soils. There is no current exposure to subsurface
soils. For the inhalation pathway a model was used to predict
indoor and outdoor air concentrations of VOCs measured in
northern soils. For the northern part of the site, exposure was
evaluated for a young child, an older child and an adult who
would spend 16 hours per day indoors and 8 hours per day outdoors
for 350 days per year for a total of 30 years. A model was used
to predict indoor and outdoor air concentrations of volatile
compounds measured in southern soils and exposure was evaluated
for an adult worker who would spend 8 hours outdoors or 8 hours
indoors, depending on the jOb, for 250' days per year for 25
years.
Incidental ingestion and dermal contact with surface water while
swimming in Black Pond was evaluated for an older child and an
adult who would swim in the pond 36 days per year for a total of
24 years. Dermal contact with surface water while wading 'in
Black Pond and off-site wetlands was evaluated for a young child,
an older child and an adult who would wade 75 days per year for a
total of 30 years. Dermal contact with sediments in Black Pond
while s~imming was evaluated for an older child and an adult who
would s~im 36 days per year for a total of 24 years. Incidental
ingestion and dermal contact with sediments while wading was
evaluat~d for a young child, older child, and adult who would
wade in Black Pond on off-site wetlands for 75 days per year for
a total of 30 years. For each pathway evaluated,an average and
a reasonable maximum exposure estimate was generated
corresponding to exposure to the average and the maximum
concentration detected in that particular medium.
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Excess lifetime cancer risks were determined for each exposure
pathway by multiplying the exposure level with the chemical
specific cancer factor. Cancer potency factors have been
developed by EPA from epidemiological or animal studies to
reflect a conservative "upper bound" of the risk posed by
potentially carcinogenic compounds. That is, the true risk is
unlikely to be greater than the risk predicted. The resulting
risk estimates are expressed in scientific notation as a
probability (e.g. 1 x 10~ or l/l,OOO~OOO) and indicate (using
this example), that an average individual is not likely to have
greater than a one in a million chance of developing cancer over
70 years as a result of site-related exposure as defined by the
compound at the stated concentration. Current EPA practice
considers carcinogenic risks to be additive when assessing
exposure to a mixture of hazardous substances. .
The hazard index was also calculated for each pathway as EPA's
measure of the potential for non-carcinogenic health effects. A
hazard quotient is calculated by dividing the exposure level by
the reference dose (RfD) or other suitable benchmark for non-
carcinogenic health effects for an individual compound.
Reference doses have been developed by EPA to protect sensitive
individuals over the course of a lifetime and they reflect a
daily exposure level that is likely to be without an appreciable
risk of an adverse health effect. RfDs are derived from
epidemiological or animal studies and incorporate uncertainty
factors to help ensure that adverse health effects will not
occur. The hazard quotient is often expressed as a single value
(e.g. 0.3) indicating the ratio of the stated exposure as defined
to the reference dose value (in this example, the exposure as
characterized is approximately one third of an acceptable.
exposure level for the given compound). The hazard quotient is
only considered additive for compounds that have the same or
similar toxic endpoint and the sum is referred to as the hazard
index (HI). (For example: the hazard quotient for a compound
known to produce liver damage should not be added to a second
whose toxic endpoint is kidney damage).
Although to date, there has been no measurable inhalation or
explosion risk due to landfill gases or methane respectively,
such gases have been detected migrating into some of the
industrial buildings on the landfill. .In addition, two soil gas
monitoring wells located on two residential properties have shown
significant concentrations of methane during monitoring. Because
groundwater was the only pathway evaluated which exceeded EPA's
target risk range, this is the only pathway for which detailed
risks are presented below. Table 11 and 12 depict the
carcinogenic and non-carcinogenic risk summary for the
contaminants of concern in groundwater. evaluated to reflect
present and potential future-exposures from ingestion. These
risks correspond to the average and the reasonable maximum
exposure (RME) scenarios. Risks from all other pathways are
summarized in Table 13. For a more detailed analysis of the
risks from other pathways see Tables 4-2 through 4-6 in Volume 2A
0901-178
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TABLE 11
CARCINOGENIC RISKS FOR THE POSSIBLE FUTURE INGESTION
OF GROUNDWATER
Contaminant of Cone. Exposure Cancer Potency Risk Estimate
Concern (mg/L) Factor Factor
,
-------
TABLE 12
NONCARCINOGENIC RISKS FOR THE POSSIBLE FUTURE INGESTION
OF GROUNDWATER
Contaminant of Cone. Exposure-Roferenco-----TargeC---'-Tlazard au-otieni" ----
Concern (mg/L) Faclor Dose Endpolnl
ove max (Ukg/daY.l{mg/kgl!!Y) . of toxicity ave RME
antimony 0.056 0.841 0.043 0.0004 blood 6.0E +00 9.0E+01
aroclors 0.003 0.0229 0.043 0.00007 fetotox. 1.8E+00 1.4E+01
arsenic 0.0053 0.0474 0.043 0.0000 skin 7.6E-01 6.BE+00
barilKn 1.24 19.4 0.043 0.07 blood 7.6E-01 1.2E+01
beryllium 0.0032 0.0437 0.043 0.005 no obs err. 2.BE-02 3.BE-01
bis(2 - elhylhexyl)phthalate 0.0277 0.7 0.043 0.02 liver 6.0E-02 1.5E+00
butylbenzylpht halate 0.0064 0.13 0.043 0.2 wgt. gain 1.0E-03 2.0E-02
cadmium 0.0295 0.946 0.043 0.0005 kidney 2.5E+00 B.1E+01
carbon disulfide 0.0063 0.13 0.043 0.1 fetotox. 3.6E-03 5.6E-02
chlordane 0.00019 0.0000 0.043 0.00006 liver 1.4E-01 2.2E-01
chloroform 0.0099 0.11 0.043 0.01 liver 4.3E-02 4.7E-01
chromium 0.113 1.17 0.043 0.005 no obs. err 9.7E-01 1.0E+01
1,2-dichloroethene(total) 1.08 33 0.043 0.01 blood 4.6E+00 1.<1E+02
ethylbenzene 0.312 10 0.043 0.1 liver, kidney 1.3E-01 4.3E+OO
lead. " 0.449 15.4 0.043 NO CNS ND ND
mercury 0.0004 0.006 0.043 0.00034 kidney 5.1E-02 7.SE-01
methylene chloride 0.0073 0.128 0.043 0.06 liver 5.2E-03 O.2E-02
manganoso 4.79 116 0.043 0.005 CNS 4.1E+01 1.0E+03
nickel 0.211 4.39 0.043 0.02 wgt. loss 4.5E-01 9.4E +00
silver 0.0277 0.002 0.043 0.005 skin 2.4E-01 7.0E+OO
tetrachloroethene 0.0064 0.062 0.043 0.01 liver 2.8E -02 2.7E-01
thallium 0.0022 0.0166 0.043 0.00008 no obs. err. 1.2E+00 8.9E +00
toluene 0.566 23 0.043 0.2 liver, kidney 1.2E-01 4.9E+00
1,1,1 -trichloroethane 0.0581 1.8 0.043 0.09 liver 2.8E-02 8.6E-01
vanadium 0.174 2.29 0.043 0.007 no obs. eft. 1.1 E+OO 1.4E+01
xylenes 0.344 13 0.043 2 Wglloss 7.4E-03 2.8E-01
zinc 1.25 38.2 0.043 0.3 blood 1.8E -01 5.5E+OO
ENDPOINT His
HI Blood 12 248
HI liver 0.6 13
HI kidney 3 91
HI No obs. eff. 3 33
HI Wgt. loss 0.5 10
HI skIn 1 15
HI CNS 41 1000
HI felolox 2 14
. - Lead Is evaluated quantitatively by use 0' EPA's IEUBK Model, Version 0.5. See Human Heokh Risk Assessment.
-------
TABLE 13
SUMMARY OF RISK ESTIMATES FOR EXPOSURE
PATHWAYS NOT EXCEEDING EPA'S TARGET RISK RANGE
Exposure
Pathway
On-site Resident
(Surface soil north)
Soil 3.7E-05 1.4E-04 5.2E-01 6.9E-01
Indoor air 2.6E-07 1.6E -07 2.2E -03 4.1 E-03
Outdoor air B.6E-09 5.0E-08 7.0E-05 4.5E-04
Total 3.7E-05 1.4E-04 5.3E-01 7.0E-01
Outdoor worker
(Surface soil south)
soil 1.6E-05 5.9E-05 2.8E-02 5.2E-02
outdoor air 3.5E-06 1.3E"':05 1.4E-04 6.3E-04
total 2.0E-05 7.2E-05 2.8E-02 5.3E-02
Total Risk
aye RM E
Total Hazard Index
aye RME
Indoor worker
(Southern area)
indoor air 6.4E-06 2.3E-05 2.5E~04 1.2E-03
Swimmer
Sediment 1.8E -06 4.9E-06 1.5E-04 3.0E -04
Surface water 1.5E-08 1.8E-08 4.0E-02 1.5E-01
total 1.8E-06 4.9E-06 4.0E -02 1.6E-Q1
On-site wader
sediment 4.2E-05 1.1 E-04 3.1 E-02 1.0E-01
surface water 4.2E -09 5.1E-09 2.9E-03 1.1 E-02
total 4.2E -05 1.1E-04 3.4E-02 1.1 E-01
Off-site wader
sediment
surface water
1.1 E-05
4.2E -09
1.1 E-05
2.7E-05
5.1E-09
2.7E-05
5.9E-03
2.9E-03
8.8E-03
1.3E-02
1.1 E-02
-------
of the HHRA Report.
The only exposure pathway exceeding EPA's target risk range of
104 to 10~ is the ingestion of groundwater. The major
contributors to carcinogenic risk in groundwater are beryllium,
bis(2-ethylhexyl)phthalate, trichloroethene, vinyl chloride,
arsenic' and aroclors. The major contributors to noncarcinogenic
risk estimates are; antimony, barium, bis (2-ethylhexyl) phthalate,
cadmium, chromium, 1,2-dichloroethene, ethylbenzene, nickel,
silver, thallium, toluene, vanadium, arsenic, manganese, zinc and
aroclors. MCLs were exceeded for antimony, barium, beryll~um,
cadmium, chromium, mercury, nickel, thallium, 1,1,1-
trichloroethane, 1,2-dichloroethane, benzene, chloroform,
ethylbenzene, methylene chloride, tetrachloroethene, toluene,
trichloroethene, vinyl chloride, xylenes and aroclors. The
action level for lead was also exceeded.
Version 0.5 of the EPA's Integrated Uptake Biokinetic Model
(IUBK) was used to assess the health risks from potential
exposures to lead in groundwater and soil at the Site. The IUBK
"model predicts blood lead levels in children 0-6 years of age due
to exposures to lead in air, water, soil/dusts, and diet as well
as contributions from maternal sources. For this risk
assessment, average concentrations of lead in surface soils and
groundwater at the study site were used. The daily intakes of.
lead from air and diet" were the default-values provided in the
model. The lead concentration in household dust was assumed to
be the same as that of outdoor soil. Exposure ,variations are
specifically accounted for within the model by its application of
the geometric standard deviation (GSD) to calculate a
distribution of lead levels -for an exposed population. The
default GSD value was used to define exposure distributions.
The results of the IUBKmodel predict that 99.93% of children
drinking groundwater containing an average of 448ug of lead/L
would have blood lead levels greater 'than 10ugfdL. (Ten
micrograms per dL is the blood lead level below which the
occurrence of adverse health effects in children has not yet been
confirmed.) This exceeds EPA's target for blood lead in children
which states that no greater than 5% of the blood lead levels of
the population exposed shall exceed 10ug/dL.
Ecoloaical Risk Assessment
The focus of the ecological risk assessment was to determine the
Site's potential impact on environmental receptors such as birds,
small mammals, reptiles, amphibians and fish. The ecological risk
assessment included a delineation of wetlands, a qualitative
animal survey and an ecological hazard assessment of the study
area of the Old Southington Landfill. The initial step of the
ecological risk assessment involved identification and
preliminary characterization of potential physical and chemical
stressors, the ecosystems potentially at risk and ecological
effects. .
D94.178
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The physical stressors in the study area include the landfill and
residential and commercial/industrial properties. Chemical
stressors include volatile organic, semivolatile organic and
inorganic compounds, polychlorinated biphenyl compound (PCBs) and
. pesticides. The primary ecosystem considered in the risk
assessment was the aquatic system,(i.e., plants and animals
supported by Black Pond and the associated wetlands).
The potential ecological effects were evaluated semi-
quantitatively by comparing surface water concentrations of .
chemical stressors that were Constituents of Potential Concern
(CPC) to Ambient Water Quality Criteria (AWQC). Sediment
concentrations of CPC were compared to National Oceanic and
Atmospheric Administration (NOAA) sediment quality values or by
using the Equilibrium Partitioning Approach.
The risk assessment indicates that the potential risks to anima~s
are generally low and are associated with specific areas, .
including an isolated wetland area south of Black Pond, and
portions of the northern area of the Site. Overall, the study
area is affected by typical residential/urban activities in
addition to potential landfill impacts. Residential and urban
impacts could include street runoff containing oil, PAHs and
metals that drain into Black Pond. Residential usage of paints,
solvents, oil, gasoline, pesticides and other chemicals may also
impact Black Pond through surface runoff from areas where these
chemicals may have been spilled.
Actual or threatened releases of hazardous substances from the
Site, if not addressed by implementing the response action
selected in this ROD, may present an imminent and substantial
endangerment to the public health or welfare or the environment.
The proposed remedy once implemented would: immediately prevent
contact with the landfill waste; would effectively and
permanently control landfill gases, including methane; would
improve the quality of surface water in Black Pond, and would
improve the quality of groundwater until a final remedy for
groundwater can be selected.
VII. DEVELOPMENT AND SCREENING OF ALTERNATIVES
A.
Statutory Requirements/Response Objectives
Under its legal authorities, EPA's primary responsibility at
Superfund sites is to undertake re~edial actions that are
protective of human health and the environment. In addition,
Section 121 of CERCLA establishes several other statutory
requirements and preferences, including: a requirement that
EPA's remedial action, when complete, must comply with all
federal and more stringent state environmental standards,
requirements, criteria or limitations, unless a waiver is
invoked; a requirement that EPA select a remedial action that is
cost-effective and that utilizes permanent solutions and
alternative treatment technologies or resource recovery
D9-I-178
9/15/9-1
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technologies to the maximum extent practicable; and a preference
for:emedies in which treatment which permanently and
sigr., ~icantly reduces the volume, toxicity or mobility of the
hazar_ous substances is a principal element over remedies not
involving such treatment. Response alternatives were developed
to be consistent with these congressional mandates.
Using the information gathered from the RI and HHRA, and other
technical documents, EPA identified several source control
response objectives to use in developing alt~rnatives to prevent
or minimize the release of contaminants from the Site. The.
limited. source control objectives are:
°6.
1.
Minimize the current and future effects of landfill
contaminants on groundwater quality; specifically,
reduce to a minimum the amount of precipitation allowed
to infiltrate through the unsaturated waste column and
contaminate the groundwater; .
2.
Eliminate potential future risks to human health
through direct contact with landfill. contaminants by
maintaining a physical barrier; .
3.
Control surface water run-on, run-off and erosion at
the Site;
4.
Prevent risks from uncontrolled landfill gas migration
and emissions;
5.
Comply with state and federal applicable or relevant
and appropriate requirements (ARARs); and
Minimiz= potential impacts of implementing the selected
limited source control alternative on adjacent surface
waters and wetlands.
A comprehensive evaluation of containment and management of
contaminated groundwater migrating from the landfill will'be
addressed by the final response action. As part of this interim
remedy, subsequent qroundwater. studies will be necessary to
define the extent and nature of the plume and determine if the .
plume is impacting any natural resource areas downgradient of the
site. Monitoring data collected from the interim remedy will be
used to ev~luate improvements in groundwater quality resulting
from construction of the impermeable cap' and excavation and
consolidation of discrete materials A and B found in SSDA1. This
information will be useful in developing groundwater remedial
alternatives that address groundwater remediation at and off-
site. The selection of any necessary groundwater remediation
will be addressed. in a final remedy..
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B.
Technology and Alternative Development and Screening
CERCLA and the NCP set forth the process by which remedial
actions are evaluated and selected. Because many CERCLA
municipal landfill sites share similar characteristics, they lend
themselves to remediation by similar technologies. EPA has
established a number of expectations as to the types of
technologies that should be considered and alternatives that
should be developed; they are listed in the National Contingency
Plan (40 CFR 300.430(a) (1». For CERCLA municip~l landfill
sites, it is expected that;
. .
4.
5.
6.
~.
The principal threats posed by a site will be treated
wherever practical, such as in the case of remediation
of a hot spot.
2
Engineering controls such' as containment will' be used.
for waste that poses a relatively 'low long-term threat.
or where treatment is impractical. '
3.
A combination of methods will be used as appropriate to
achieve protection of human health and the environment.
An example of combined methods for municipal landfill
sites would be treatment of hot spot in conjunction
with containment (capping) of the landfill contents.
Institutional controls such as deed restrictions will
be used to supplement engineering con~rols, as
appropriate, to prevent exposure to hazardous wastes.
Innovative technologies will be considered when such
technologies offer the potential for superior treatment
performance or lower costs for performance similar to
that of demonstrated technologies.
Groundwater will be returned to beneficial uses
whenever practical, within a reasonable time, given the
particular circumstances of the site. .
The presumptive remedy for CERCLA municipal landfills was used at
this Site which relates primarily to containment (capping) of the
landfill waste and collection and, if necessary, treatment of
landfill gas. EPA has determined that such containment measures
are appropriate at municipal landfills that contain wastes that
pose a relatively low long-term threat or where treatment of the
entire waste mass is impracticable due to the volume and mixture
of wastes disposed of at the landfill.
Capping of the landfill waste along with collection and, if
necessary, treatment of landfill gases is the presumptive
containment remedy selected in the FS for this Site. In the FS,
this remedy is combineq with other remedial actions that address
source control of the landfill wastes. The presumptive remedy
1>94-178
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does not address exposure pathways outside of the source area
(landfill) such as groundwater. .
Groundwater alternatives were included in the FS Report. These
alternatives were based on insufficient data. Additional
groundwater studies must be performed as part of this interim
remedy before EPA,' in consultation with CT DEP, will make a
determination on any necessary groundwater remediation.
VI I I.
DESCRIPTION OF SOURCE CONTROL ALTERNATIVES
This section provides a narrative summary of each alternative
evaluated. There ~=e several other activities which are common
to all the limited source control alternatives considered, except
the no action alternative, SC1. These common activities include:
1) permanent relocation of the residences and businesses; 2)
institutional controls which could include fencing to limit
future Site activities; 3) groundwater monitoring; and 4)
five-year reviews of the remedial alternative. '
Alternative SC1:
No Action
The FS evaluated the No Action Alternative to serve as a baseline
for comparison with other remedial alternatives under
consideration. The RI/FS Addendum dated May 1994 makes a
correction to the No Action Alternative in the FS to point out
the following. Under the No Action Alternative, no treatment or
containment of solid waste would occur and no .effort would be
made to contain gas migration or restrict potential exposure to
site contaminants. The landfill waste would continue to leach
contaminants to groundwater. The objectives of this alternative
are to merely maintain the site as it currently exists and
conduct long-term monitoring of the groundwater with existing and
new monitoring wells. .
Estimated Time for Well ,Installation 1 month
Estimated Time of Operation: Not applicable
Estimated Capital Cost: $203,000
Estimated Operation and Maintenance Cost (net present worth):
$2,377,000
Estimated Total :ost (net present worth): $2,580,000
Alternative SC2A: CaD Northern Landfill Area with a Soil CaD and
Southern Area with a RCRA subtitle C Composite Cap
This alternative involves only capping the landfill area. The
northern part of the Site would be capped with a soil cap and the
southern part would be capped with a RCRA Subtitle C composite
cap. The soil cap would consist of a minimum of two feet of
granular soil which would be overlain by eight inches of topsoil
and vegetative cover. No soil gas collection/treatment system is
proposed on the northern part of the landfill in this
alternative.
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A RCRA Subtitle C composite cap, consisting of several low
permeability layers to prevent further leaching of contaminants
and to prevent direct contact with the wastes, would be
implemented in this area. A RCRA Subtitle C composite cap is
typically four to five feet thick and typically consists of six
layers of materials: a sandy fill layer placed on top of the
existing ground surface, a low permeability geocomposite layer
overlain by a second low permeability layer consisting of a
flexible membrane liner (FML), a geosynthetic drainage layer, a
layer of sand, and a layer of topsoil for a vegetative cover.
The cap would be approximately 10 acres in areal extent. This
alternative would'also incorporate institutional controls which
could include fencing, long-term groundwater, monitoring, and
Five-Year Reviews.
The soil cap and RCRA Subtitle C composite cap would prevent
human contact with contaminated soils. However, rain and snow,
melt would penetrate the soil cap, and eventually contact buried
wastes potentially causing contaminants to leach to the
groundwater. The RCRA subtitle C composite cap in the southern
area of the Site would be constructed with two low permeable
liners that would prevent the infiltration of rain and snow melt
into waste located above the water table. Thus, contaminants
would be prevented from leaching into the groundwater. However,
because groundwater would not be contained or treated, waste that
is located below the water table would continue to leach
contaminants that would migrate off-site to the west of Old
Turnpike Road.
Estimated Time for Design and Construction: 30 months
Estimated Time of Operation: 30 years
Estimated Cost of Permanent Relocation: $1,760,000
Estimated Capital Cost: $7,514,000
Estimated Operation and Maintenance Cost (net present worth):
$3,893,000
Estimated Total Cost (net present worth): $13,170,000
Alternative SC2B: Cap Northern Landfill Area with a Sinale-
Barrier Cap and Southern Area with a RCRA Subt~le C ComDos~
Cap
This alternative involves only capping the landfill area. This
capping would consist of two different types of low permeability
caps over specific areas. A single-barrier low permeability cap
would be constructed over the northern landfill area providing a
low permeability barrier. This cap would also prevent soluble
contaminants that may be present above the water table in this
area from contacting precipitation and in turn leaching into the
groundwater. Typically, a single-barrier cap consists of: a
bottom layer of sandy ,fill, a low permeable flexible membrane
liner (FML) which is a plastic-like material, then a geosynthetic
drainage layer, followed by another layer of sand, and finally, a
layer of topsoil for vegetative growth. The cap would cover an
area of approximately 2.5 acres.
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The southern area of the Site would be covered with a RCRA
Subtitle C composite cap as described for Alternative SC2A.
This alternative would include a soil gas collection/treatment
system throughout the entire landfill and incorporate the
institutional controls, which could include fencing, long-term
groundwater monitoring and Five-Year Reviews.
Estimated Time for Design and Construction:
Estimated Time of Operation: ..
Estimated Cost of Permanent Relocation:
Estimated Capital Cost:
Estimated .Operation and Maintenance Cost
(net present worth): .
Estimated Total Cost (net present worth) :
30 months
30 Years
$1,760,000
$8,138,000
$3,893,000
$13,791,000
Alternative SC6: CaD Northern Landfill Area with a Sinale-Barrier
CaD and Southern Area with a RCRA Subtitle C comDosite
caD/Excavate Discrete Material in SSDA1 and Consolidate in a
lined cell within the Southern Landfill Area
. This alternative would include capping as described for
Alternative SC2B, and soil gas collection/treatment, excavation
of the SSDA1 discrete materials A and B (estimated volume is 500
to 1,100 cubic yards) along .with a two-foot buffer zone around
these materials and consolidation of these materials in a low
permeability lined cell within the southern portion of the
landfill area. Institutional controls which could include
fencing, long-term groundwater, surface water,. sediment and soil
gas monitoring, and Five-Year Reviews would also be a part of
this alternative.
Excavating the SSDA1 discrete materials would serve to reduce the
potential migration of high levels of contaminants from these
wastes into the qroundwater.
Estimated Time for Design and Construction:
Estimated Time of Operation:
Estimated Cost of Permanent Relocation:
Estimated Capital Cost:
Estimated Operation and Maintenance Cost
(net present worth):
Estimated Total Cost (net present worth):
37 months
30 years
$1,760,000
$ 9,738,000
$4,537,000:
$16,035,000
Alternative SC7: CaD Northern Landfill with a Sinqle-Barrier Ca~
and Southern Area with a RCRA Subtitle C ComDosite CaD/Excavate
Discrete Material in SSDAl and Incinerate Off-Site
This alternative would include capping and soil gas
collection/treatment as descri~ed in SC2B, and. excavation and
off-site treatment (incineration) of the SSDA1 discrete materials
A and B (estimated volume is 500 to 1,100 cubic yards).
Institutional controls which could include fencing, long-term
groundwater monitoring, and Five-Year Reviews would also be a
part of this alternative.
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In the FS, it was determined that off-site incineration would be
the most effective means of treating the discrete materials which
are high in volatile and semi-volatile organic compounds.
However, there are a limited number of incinerators that accept
this type of waste, and incineration can be a costly
treatment/disposal method. In addition, there are a limited
number of facilities that can perform incineration.
'By excavating the SSDAl discrete materials, especially those
located below the water table, the potential for migration of
high levels of VOCs from SSDAl into groundwater would be
eliminated. Treatment of this material would result in a
permanent destruction of the VOC and SVOC contaminants. However,
metals would remain in the incinerator ash and may be considered
a hazardous waste that would need special handling and disposal.
Estimated Time for Design and Constructio~:
Estimated Time of Operation:
Estimated Cost of Permanent Relocation:
Estimated Capital Cost:
Estimated Operation and Maintenance 'Cost
(net present worth) :
Estimated Total Cost (net 'present worth}:
37 months
30 years
$1,760,000
$15,144,000
$3,893,500
$20,797,000
IX.
SUMMARY OF THE COMPARATIVE ANALYSIS OF ALTERNATIVES
Section 121{b) (1) of CERCLA presents several factors that, at a
minimum, EPA is required to consider in its assessment of
alternatives. Building upon these spe~ific statutory mandates,
the National Contingency Plan articulates nine evaluation
criteria to be used in assessing the individual remedial
alternatives. '
A detailed analysis was performed on the alternatives using the
nine evaluation criteria in order to select a site remedy. The
following is a summary of the comparison of each alternative's
strength and weakness with respect to the nine evaluation
criteria. These criteria are summarized as follows:
Threshold Criteria
The two threshold criteria described below must be met in order
for the alternatives to be eligible for selection in accordance
with the NCP.
1.
Overall protection of human health and the environment
addresses whether or not a remedy provides adequate
protection and describes how risks posed through each
pathway are eliminated, reduced or controlled through
treatment, engineering controls, or institutional'
controls. '
2.
'Compliance with applicable or relevant and appropriate
requirements (ARARS) addresses whether or not a remedy
will meet all the ARARs of other Federal and State
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environmental laws and/or provides grounds for invoking
a waiver.
primarv Balancinq Criteria
The following five criteria are utilized to compare and evaluate
the elements of one alternative to another that meet the
threshold criteria.
7.
3.
Long-term effectiveness and permanence addresses the
criteria that are utilized to assess alternatives for
the long-term effectiveness and permanence they afford,
along with the degree of certainty that they will prove
successful. .
4.
Reduction of toxicity, mobility, or volume (TKV)
through treatment addresses the degree to which
alternatives employ recycling or treatment that reduces
toxicity, mobility, or volume, including how treatment.
is used to address the principal threats posed by the
site. .
5.
Short-term effectiveness addresses the period of time
needed to achieve protection and any adverse impacts on
human health and the environment that may be posed
during the construction and implementation period,
until cleanup goals are achieved.
6.
Implementability addresses the technical and
administrative feasibility of a remedy, including the
availability of materials and services needed to
implement a particular option.
Cost includes estimated capital and Operation
maintenance (O&M) costs, as well as present-worth
costs. .
Modifvinq Criteria
The modifying criteria are used on the final evaluation of
remedial alternatives generally after EPA has received public
comment on the RIfFS and Proposed Plan.
8.
9.
State acceptance addresses the State's position and key
concerns related to the preferred alternative and other
alternatives, and the state's comments on ARARs or the
proposed use of waivers. )
community acceptance addresses the public's general
response to the alternatives described in the Proposed
'Plan and RIfFS report.
A detailed tabular assessment of each alternative according to
the nine criteria can be found in The Table entitled "EPA
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Addendum to RIfFS - Old Southington Landfill Superfund Site
comparative Analysis of Remedial Alternatives Operable Unit 1 -
Limited Source Control" of the RIfFS Addendum dated May 1994.
Following the detailed analysis of each individual alternative, a
comparative analysis was conducted focusing on the relative
performance of each alternative against the nine criteria.
The section below presents the nine criteria and a brief
narrative summary of the alternatives and the strengths and
weaknesses according to the detailed and comparative analysis.
1.
Overall Protection of Human Health and the Environment
The preamble to the National Contingency Plan (NCP) identifies
municipal landfills as a type of site where treatment of the
waste may be impracticable because of the size and heterogeneity
of the contents. EPA generally considers containment to be an
appropriate response action for large municipal landfills.
Because the Old Southinqton Landfill Site is a large municipal
landfill, the alternatives evaluated consider. containment to be
the appropriate response action for source control.
Alternative SC1, No Action, will not meet this criterion because
no measures would be taken to prevent potential exposure to Site
contaminants.
Alternatives SC6 and SC7 address source control , by capping the
landfill and excavation and consolidation of SSDAl discrete
materials and providing overall protection of human health and
the environment by preventing direct contact with contaminated
subsurface soils and controlling landfill gas migration and
emissions. The discrete industrial wastes found above and. below
the water table in SSDAl are removed and isolated in a low
permeability lined cell (SC6), or incinerated off-site (SC7),
preventing the potential for future migration of contaminants
from. these wastes into groundwater. Alternatives SC2A and SC2B,
are similar to Alternatives SC6 and SC7 in that they have the
same level of protection for the capping component. However,
alternatives SC2Aand SC2B do not provide for the excavation and
consolidation of SSDAl contaminants, and thus, do not prevent the
potential future migration of these contaminants into
groundwater.
2.
Compliance with Applicable or Relevant and Appropriate
Requirements (ARARs)
The No Action Alternative SC1, does not comply with the ARARs
identified because it will not satisfy the RCRA requirement to
minimize the potential for releases of hazardous contaminants to
the environment and it does not fully satisfy design, operating,
or closure and post-closure requirements for hazardous waste
. landfills.
1)94.17S
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Alternatives SC2A, SC2B, SC6 and SC7 will meet the closure
requirements for hazardous waste landfills in the southern area
of the landfill where a RCRA subtitle C composite cap will be
installed and will meet the closure requirements in the northern
part of the Landfill for RCRA Subtitle D Solid Waste landfills.
All other ARARs would be met by the alternatives. Groundwater
ARARs (e.g., Federal and State MCLs) will be addressed under the
final remedy.
3.
Long-term Effectiveness and Permanence
with the exception of the No Action Alternative, SC1, all of the
alternatives would provide long-term effectiveness. SCl would
not provide direct engineering controls to prevent direct contact
with contaminated soils and debris, nor control soil gas
migration, and would provide no additional protection of
groundwater from continued leaching of waste from the landfill.
The long-term effectiveness of landfill caps has been proven to
be excellent. The potential risks from exposure to contaminated
soils and debris are eliminated by a combination of the cap and
institutional controls. All of the alternatives except the No
Action Alternative significantly reduce infiltration of rain and
snow melt into the unsaturated wastes, resulting in an improve-
ment in groundwater quality over time. Alternatives SC2B, SC6
and SC7 are more effective than Alternative SC2A because they
include a single-barrier low permeable cap on the northern area
of the landfill rather than a soil cap. The soil cap does not
include a soil gas collection system and allows more infiltration
of rain and snow melt than does the single-barrier low
permeability cap. Groundwater will be addressed under the final
remedy.
Alternative SC6 is more effective in reducing potential risks
from the SSDAl industrial wastes by excavating and plac~ng them
in a lined cell than all other alternatives except SC7.
Alternative SC7 involves incineration of the SSDAl wastes which
eliminates the risks associated with these materials by
destroying the organic contaminants.
4.
Reduction of Toxicity, MObility, or Volume through Treatment
Alternatives SC2A, SC6 and SC2B (capping only) and Alternative
SCl (No Action) provide no treatment of landfill derived wastes
and consequently, no reduction in toxicity, mobility or volume
through treatment because treatment of the entire landfill area
is impracticable. However, Alternative SC6 does reduce the
mobility of contaminants in SSDAlwastes by excavation/placement
in a low permeable lined cell, eliminating direct contact of
these materials with groundwater. Of all of the source control
alternatives, Alternative SC7, which includes incineration of
SSDAl materials, would provide the most reduction in toxicity,
mobility or volume through treatment.
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5.
Short-term Effectiveness
Alternative SC1, No Action, would pose the least short-te~ risk
of adverse impacts on human health and the environment because it
does not include any disturbance of contaminated areas.
The short-term risks of Alternative SC6 and the other
alternatives that include capping are equivalent. The short-term
risks relate to airborne dust and volatilization of contaminants
during construction of the landfill cap. Excavation of
potentially contaminated wastes would occur primarily along Old
Turnpike Road and along the shore of Black Pond. Contaminants
may be reieased to Black Pond and the outlet streams during
excavation activities. Impacts to Black Pond and associated
wetlands due to the construction of Alternatives SC2A, SC2B, SC6,
and SC7 would be minimized to the extent possible by the design
and engineering controls.
Risks to construction workers and the area residents can be
controlled and minimized through the use of engineering controls
such as dust suppression techniques, access limitations during
specific activities, control of traffic on Old Turnpike Road, air
monitoring and compliance with a health and safety plan.
Standard construction practices and controls would be implemented
to minimize site soil erosion and siltation to Black Pond and the
outlet stream.
Alternatives SC6 and SC7 involve excavation of the SSDAl discrete
materials. The potential risk of exposure to workers and off-
site populations would be highest for Alternative SC7 due to the
potential release hazards associated with the excavation and
transportation of SSDAl materials to an off-site incineration
facility. Alternatives SC6 and SC7 would pose roughly the same
. short-term risks from excavation of the SSDAl materials. Worker
exposure to contaminated soils and both worker and community
exposure to hazardous volatile emissions is greater for these
actions than for the other alternatives. Consequently, the risk
of exposure to workers and off-site populations are worse under
Alternatives SC6 and SC7 than Alternatives SC2A and SC2B. The
risk can be controlled through the following. SSDAl
excavation/consolidation activities can be completed in a
relatively short period of time (approximately one week).
Furthermore, the risks associated with SC6 and SC7 would be
minimized through the implementation of: special engineering
precautions which can include dust suppression, access
limitations and control of traffic on Old Turnpike Road; air
monitoring and contingency planning for potential emergencies;
and compliance with a health and safety plan and federal and
state regulations.
All alternatives would result in similar increased traffic on Old
Turnpike Road from construction-related vehicular traffic, except
SC7, which would cause additional traffic due to the off-site
transportation of SSDAl waste for incineration.
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6.
Irnplementability
Alternative SC1, No Action, is the most easily implemented since
it requires no construction and minimal administrative approvals,
including institutional controls.
The various components of all of the alternatives for limited
source control are common elements of remedial projects that
could be readily implemented. Excavation and consolidation or
treatment of SSDAl materials, which are components of
Alternatives SC6 and SC7, are. easily implemented through the use
of standard construc~ion techniques and special procedures to
minimiz.e release of contaminants. Excavation and consolidation
components require additional precautions due to the hazardous
constituents present in the waste.
Alternative SC7 requires long distance transport of SSD~1
materials to an off-site incineration facility. The availability
of such facilities is dependent upon the facility's cap~city and
regulatory status at the time of disposal.
7.
Cost
The least costly of the alternatives would be the No Action
Alternative, SCl,'which includes no active efforts to contain the
contamination at the site. The difference in the total net
present worth of the least and most costly limited source 'control
alternatives is approximately $7.6 million (SC2A = $13,170,000;
SC2B = $13,791,000; SC6 = $16,035~000; and SC7 = $20,797,000).
The total cost of Alternative SC6 is $2.2 to $2.9 million greater
than Alternatives SC2B and SC2A, respectively. EPA believes that
the added cost for Alternative SC6 provides a greater overall
level of protection through the single barrier low permeability
cap and soil gas cOllection/treatment system in the northern
area, and through .excavation/consolidation of SSDA1 discrete
materials. The single barrier cap would be more effective in
preventing direct contact with contaminated soils and the gas
collection system would prevent landfill gases from migrating
off-site. Excavating SSDA1 materials and isolating them within a
lined cell within the landfill will effectively isolate these
materials and prevent them from contributing to future
groundwater contamination.
SC7 includes all of the components of Alternative SC6 and also
includes off-site incineration of the SSDAl materials. The total
cost of this alternative is approximately $4.8 million greater
than Alternative SC6. EPA believes that the additional cost of
incineration does not provide a significant additional benefit
for protection ofhurnan health in comparison to Alternative SC6.
In addition, other factors associated with incineration of the
waste such as the availability of treatment facilities, increased
truck traffic through town and the potential for the release of
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contaminan~s during off-site transportation make this option less
favorable.
The operation and maintenance cost of all of the source control
alternatives is approximately $3.9 to $4.5 million.
s.
state Acceptance
The State's comments on the Proposed Plan are provided in
Responsiveness Summary included in Appendix A. The State
with the Selected Remedy. Their letter of concurrence,
documenting the State's position on the Selected Remedy is
provided in Appendix C of this ROD.
9.
the
concurs
Community Acceptance
The comments received from the community on the RIfFS and the
. Proposed Plan during the public comment period and EPA's -
responses to these comments are summarized in the Responsiveness
Summary in Appendix A.
Based on written and oral comments received during the comment
period, there are opposing views with respect to the limited
source control remedy.- Responses to all public comments are
summarized in the Responsiveness Summary in Appendix A.
x.
THE SELECTED REMEDY FOR LIMITED SOURCE CONTROL
The selected remedy is Alternative SC6. The components of this
remedy are summarized in Section VIII of this ROD. In summary,
the selected remedy for limited source control consists of the
following components:
3.
4.
5.
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1.
Removing all residential and commercial structures from
the landfill and off-site relocation of all affected
residents and businesses;
2.
Excavating and consolidating discrete semi-solid
materials A and B from SSDAl including a two-foot -
buffer zone around these materials to prevent wastes
below the water table from further contaminating the
groundwater;
Constructing a low permeability cap over all of the
landfill area to reduce the amount of water entering'
the site waste;
Installing a gas collection and, if necessary,
treatment system to prevent landfill gas build up under
the cap and to collect the landfill gases;
Implementing' a monitoring plan to determine the long-
term effectiveness of the cap on groundwater, surface
-------
water, sediment quality, and the e:
soil gas collection/treatment system:
'Jeness of the
6.
Dev~.;pi~g and implemen~ ; -~s~ituti~ controls,
which could include fencing, to ensure .e integrity of
the remedy by controlling future site use and access;
and
7.
P~rforming Five Year Reviews.
The costs of-'-:a selected remedy are summarized below.
::..:..t: ima ted
Estimated
Cost of Permanent Relocation: $1,760,000
Capital Cost: $9,738,000 (exclusive of relocation
costs)
Operation & Maintenance Costs (net present worth):
$4,537,000
Total Cost (net present worth): $16,035,000
Estimated
Estimated
The EPA and CT DEP have carefully reviewed the remedial data and
evaluations relating to this Site, and have considered all public
comments received during the comment period. The agencies agree
that there is sufficient information available to proceed with a
limited source control remedy for the OlQ Southinqton Landfill.
These components are described below and are required to be
implemented under this interim ROD.
In addition, pursuant to this interim ROD, additional groundwater
studies will be required and shall proceed concurrently with the
implementation of this remedy. The purpose of these future
studies will be to define the boundary of the plur.~ and determine
if the plume is impacting any natural resource ar >. Ground-
. water monitoring data collected from the interim ,edy will be
reviewed by the Agencies. EPA will make a deterr. ~tion as to
when this data shows a meaningful reading of the effects of the
cap on groundwater. This data, in conjunction with the results
of the groundwater studies, will be used to evaluate groundwater
remedial alternatives so that EPA, in consultation with CTDEP,
will be able to determine an appropriate final remedy.
Removal of all Residential and Commercial structures From the
Landfill
Removing all of the residential and commercial structures from
the landfill and the off-site relocation of the affected
businesses and residences will be necessary prior to construction
of the cap at the Site. The permanent relocation of businesses
and residences will ensure the long-term integrity of the cap
which is necessary to prevent future re3:.eases of contaminants and
tp protect public health by eliminating the potential for future
exposure of residents and commercial workers to the landfill
contaminants. The permanent relocation of the businesses and
residences is environmentally preferable and more cost-effective
1)94.118
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than excavation of landfill wastes which would be necessary to
allow residences and businesses to remain on the Site.
Excavation and Consolidation of Discrete Semi-Solid Materials in
SSDA1 into a Lined CellOn Site
Semi~solid discrete materials A and B (estimated to be 500 to
1,100 cubic yards) found in SSDA1 along with a two-foot buffer
zone around these materials will be excavated and consolidated
into a lined cell. This cell would be placed above the water
table and located somewhere in the southern part of the landfill
beneath the RCRA Subtitle C composite cap. The cell will be
constructed to prevent infiltration of rainwater and snow melt to
these materials to prevent leaching into the groundwater.
Detailed criteria for handling these materials and construction
of the cell will be developed during remedial design to allow for
the use of the most current materials and procedures appropriate
for the specific Site conditions. '.
Because SSDA1 is located next to Old Turnpike Road, the road
would be closed off during excavation to allow sufficient space
for construction equipment and to prevent potential exposure to
VOC emissions. Controls to be implemented to minimize potential
worker and off-site population exposure to contaminated dust and
VOC emissions may include watering of the excavation, covering
spoil piles with plastic sheeting, access limitations, complete
or partial encapsulation of work area, adjusting the size of work
area, and compliance with a health and safety plan. An air
monitoring program will be required and incorporated into the
health and safety plan. .
The water table at the Site may have to be temporarily lowered to
facilitate the implementation of construction activities, such as
SSDA1 excavation. Consistent with expectations in the FS, the
effluent from this dewatering process will be remov~d to an off-
site disposal facility. If other disposal alternatives which
have environmental implications become warranted, further
analysis will be required.
Capping the Landfill
The northern, residential part of the landfill was used primarily
for disposal and burning of municipal waste consisting mainly of
wood and construction debris. The primary contaminants of
concern found in this area are PARs. EPA has selected a single-
barrier low permeability cap for this part of the landfill. .This
cap is puncture resistant and will effectively and reliably
prevent direct contact with the landfill waste. The cap will
also minimize infiltration of rainwater and snow melt into the
landfill waste. .
The southern portion of the landfill received mixed municipal,
commercial, and industrial waste. Approximately two-thirds of
this waste is located above the water table. In general, these
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materials are more soluble and more hazardous in nature than
those found in the northern part of the landfill. EPA has
selected a cap for this area that complies with the Resource
conservation and Recovery Act (RCRA) Subtitle C landfill closure
regulations. This cap will prevent direct contact with landfill
wastes and will minimize infiltration into the landfill waste;
.;~ificant improvement in the quality of groundwater is
expected.
Detailed design criteria for both caps will be developed during
remedial design to allow for the use of the most current
materials and procedures appropriate for the specific conditions
at this site. Both caps will include provisions for a gas
collection and, if necessary, treatment system. This component
of the cap will prevent unsafe exposure to landfill gases and
threats from potential methane explosion. Construction of
surface water run-on and run-off control measures will be
implemented to prevent erosion of the cap and on-site and off-
site flooding problems.
Additional testing of Black Pond is required during pre-design
and possibly during the construction phase to better define the
extent of waste in Black Pond that resulted from landfill
disposal practices. That waste will be excavated and placed
underneath the landfill cap. Landfill waste close to Old
Turnpike Road may need to be excavated and placed underneath the
cap. provisions for this work will be included in the design
report.
A comprehensive evaluation of rainfall data and Site parameters
is required to determine what changes construction of the cap may
have on surface water elevations of Black Pond. Based on this
evaluation, engineering measures may be necessary to ensure that
surface water elevations do not adversely impact neighboring
properties or wetlands associated with Black Pond. due to
construction activity. Furthermore, the,culvert that connects
Black Pond to the wetlands to the west is currently crushed and
is not functioning properly. Thus, based on the results of this
evaluation, this culvert.may need to be redesigned and
reconstructed or a comparable conduit(s) may be necessary to meet
the objectives set forth in the rainfall and site parameter
evaluation.
Gas Collection System
.A gas collection system will be installed throughout the entire
area of the landfill as a component of both caps. During pre-
design, a pilot study will be performed to determine whether
venting is appropriate or if treatment of landfill gases is
necessary. The pilot study will be performed on the southern
part of the landfill where higher concentrations of VOCs and
methane have been found. If venting is selected and later proves
not to be protective of human health or the environment, a gas
treatment system will be required.
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Long-term Monitoring Plan
A long-term monitoring plan is required to monitor the
effectiveness of the selected remedy. This plan will consist of
an appropriate number of groundwater monitoring wells and soil
gas monitoring wells around the entire landfill area. The number
and location of wells, sampling frequency, and sampling
parameters will be determined during design. Periodic surface
water and sediment sampling is also required in Black Pond and at
the outlet of the culvert or comparable conduit(s) that connects
Black Pond to the wetland area to the west of the site. The
frequency, locations, and parameters of this sampling will also-
be determined during design. The objective of the surface water
and sediment sampling" is to ensure that site related construction
work does not adversely impact Black Pond or downgradient wetland
areas. This information will also be used to determine the long-
term effectiveness of the cap.
Institutional controls
Institutional controls will be implemented at the Site to prevent
current or future use of contaminated groundwater and assure the
integrity of the cap and associated systems by limiting future
activities on the landfill. A Site security plan will be
developed and implemented to control future site use and access
to the Site.
Five Year Reviews
As provided in the NCP, EPA will review the Site at least once
every five years after the initiation of remedial action since
hazardous substances, pollutants and contaminants remain at the
Site. This will ensure that the remedial action continues to
protect human health and the environment.
XI.
STATUTORY DETERMINATIONS
The remedial action selected for implementation at the Old
Southinqton Landfill Site is consistent with CERCLA and the NCP.
The selected remedy is protective of human health and the
environment, attains ARARs and is cost-effective. This limited
source control remedial action utilizes permanent solutions and
alternative treatment technologies to the maximum extent
practicable. The selected remedy does not satisfy the statutory
preferenca for remedies that employ treatment that reduces
toxicity, mobility, or volume as a principal element because
treatment of the entire landfill area is impracticable. The
selected remedy will reduce mobility of contaminants through its
containment features. .
094-178
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A.
The Sele=ted Remedy is Protective of E
Environment
~n Health and the
The remedy at thi '~anently reduce the risks posed
to human h~-lth ana ;;.ae environ~~ .:~t through engineering controls
~"-= i~stitutional controls.
Capping of the landfill will provide protection of human health
and the environment by preventing direct contact with wastes that
contain VOCs, SVOCs, pesticides/PCBs and metals. Landfill gases
at the Site will be collectea to prevent off-site miqration and
eliminate potential explosion hazards. The cap will also prevent
erosion and potential transport of contaminated wastes into Black
Pond and the wetland areas. Excavation and consolidation of the
SSDAl discrete wastes prevents these wastes from acting as
potential long-term contributors to groundwater contamination.
Capping the landfill with a low permeability cover minimizes
infiltration of precipitation through the cap and significantly
reduces further leaching of contaminants from. wastes located
above the water table to the aquifer. A significant improvement
in groundwater quality' over the long-term is anticipated due to
the isolation of approximately two-thirds of the waste currently
above the water table under a low permeability cap. The aquifer
at the Site is very permeable and water flows through it very
quickly. This is a positive characteristic because the ability
of the aquifer to naturally flush contaminants is high. This
flushing ability, combined with the landfill cap, 'is expected to
create a significant improvement in groundwater quality over
time. .
B.
The Selected Remedy Attains'ARARS
This remedy will attain all applicable or relevant and
appropriate federal and state requirements that apply to ~e
Site. Environmental laws from which ARARs for the selected.
remedial action are'derived, and the specific ARARs include:
Action S1)ecific
Federal Reauirements
*
Resource Conservation and Recovery Act (RCRA) - Closure and
Post-Closure of Municipal Solid Waste Landfills, 40 CFR Part
258, Subpart F.
RCRA - Emergency Preparedness and prevention, 40 CFR Part
264, Subp-arts C, D.
RCRA - Crosure and Post-Closure Requirements, 40 CFR Part
264, Subpart G. .
Clean Air'Act - National Emission Standards for Hazardous
Air Pollutants (NESHAPs), 40 CFR Part 61.
*
*
*
090&-178
9/15/94
-------
*
*
state Reauirements
*
*
Solid Waste Management Regulations, RCSA 22a-209-1-15.
Hazardous Waste Management Regulations, RCSA 22a-449(c)-100-
110. . .
Air Pollution Regulations, Stationary Sources, CGS 22a-174-
3.
Air Pollution Regulations, Fugitive Dust Emissions, CGS 22a-
174-18[bJ.
Air Pollution Regulations, Control of Odors, CGS 22a-174-23.
Air Pollution Control Regulations, Incineration Regulations,
CGS 22a-174-18(c}.
Air Pollution Regulations, Hazardous Air POllutants, CGS
22a-174-29. .
Water Quality Standards, CGS 22a-426.
Water Pollutant Control Act, Permitting Requirements, CGS
22a-430-430(b}. .
Water Pollution Control Regulations,Permitting Regulations,
CGS 22a-430 1-8. .
*
*
*
*
*
*
*
*
Chemical SDecific
Federal Reauirements
*
None identified for this limited source control interim
remedy.
state Reauirements
*
None identified for this limited source control interim
remedy.
Location SDecific
Federal Reauirements
*
Protection of Wetlands, Executive Order No. 11990, 40 CFR
Part 6, Appendix A.
Clean Water Act S404 Dredge and Fill Activities, 40 CFR Part
230; 33 CFR Parts 320-328
Fish And Wildlife Coordination Act, 40 CFR Part 6
*
State Reauirements
Connecticut Inland Wetlands Regulations, RCSA 22a-39-1
through 15.
The following pOlicies, criteria, and guidance will also be
considered (TBC) during the implementation of the remedial
action:
094-178
9/15/94
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Action Soecific
*
USEPA ~~-~nical Guidance for Final Covers on Hazardous Waste
Landfi~.~ and Surface Impoundments, EPA/530-SW-89-047.
Clean Air Act - Non-methane organic compounds
(NMOCs) (Proposed Rule - 56 FR 24468, to be codified at 40
CFR Part 60, Subpart www) . .
*
Chemical Soecific
*
*
USEPA Human Health Assessment Cancer Slope Factors (CSFs).
USEPA Reference Doses (RfDs).
All the listed ARARs can be found in the tables included in
Appendix D of this Record of Decision. These tables provide a
brief synopsis of the ARARs and an explanation of the actions.
. necessary to meet the AR~s. These tables also indicate whether
the ARARs are applicabie or relevant and appropriate to the
actions to be taken at the Site. In addition to ARARs, the
tables describe the standards that are To-Be-Considered (TBC)
with respect to remedial actions.
The purpose of the remedy selected in this interim ROD is to
control, in part, the source of contamination. No qrouridwater
clean-up levels are established in this interim ROD. After
additional studies, as required under this interim remedy, have
been undertaken, a decision on the appropriate remedial action
with respect to groundwater will be set forth.in the final
remedy. .
This ROD establishes certain action-specific requirements for
groundwater including compliance with the Connecticut State Water
Quality Standards, which sets forth the antidegradation policy of
the state, as well as the Connecticut Water Pollution Control Act
and the Connecticut Water Pollution Control Regulations which are
described more completely in the tables in Appendix D. These
action-specific requirements shall apply to remedial activities
that result in discharges to groundwater and surface water, if
any should occur.
c.
The Selected Remedial Action is Cost-Effective
In EPA's judgment, the selected remedy is cost-effective, i.e.,
the remedy affords overall effectiveness proportional to its
costs. In selecting this remedy, once EPA identified
alternatives that are protective of human health and the
environment and that attain, or, as appropriate, waive ARARs, EPA
evaluated the overall effectiveness of each alternative by
assessing the relevant three criteria - long-term effectiveness
and permanence; reduction in toxicity, mobility, and volume
through treatment; and short-term effectiveness. The
relationship of the overall effectiveness of this remedial
al ternati ve was determined to be proportional to its costs.. The
094-178
9/15/94
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estimated costs of this remedial alternative are summarized
below.
Capital Costs: $9,738,000
Cost of Permanent Relocation: $1,760,000
Operation & Maintenance Costs: $4,537,000 (net present worth)
Total Cost: $16,035,000 (net present worth)
The total cost of the selected remedy is $2.2 to $2.9 million
greater than Alternatives SC2B and SC2A, respectively. EPA
believes that the added cost for the selected remedy SC6,
provides a greater overall" level of protection through the
single-barrier low permeability cap and soil gas
collection/treatment system in the northern area, and by
excavation and consolidation of SSDAl discrete materials. The
single-barrier cap will be more effective in preventing direct
contact with contaminated soils and the gas collection system
will prevent landfill gases from migrating off-site. Excavating
SSDAl materials and isolating them within a lined cell within the
landfill will effectively isolate these materials and prevent
them from contributing to future groundwater contamination.
Alternative SC7 includes all the components of the selected
remedy plus off-site incineration of the SSDA1 materials. The
total cost of SC7 is about $4.8 million greater than the selected
remedy. EPA believes the additional cost of incineration does
not provide a significant additional-benefit for protection of
human health in comparison to the selected remedy. In addition,
other factors associated with off-site waste incineration, such
as availability of treatment facilities and the potential for
release of contaminants during transportation make this option
less favorable.
D.
The Selected Remedy Utilizes Permanent Solutions and
Alternative Treatment or Resource Recovery Technologies to
the Maximum Extent Practicable
Once the Agency identified those alternatives that attain or, as
appropriate, waive ARARs and that are protective of human health
and the environment, EPA identified which alternative utilizes
permanent solutions and alternative treat~ent technologies or
resource recovery technologies to the maximum extent practicable.
This determination was made by deciding which one of the "
identified alternatives provides the best balance of trade-offs
among alternatives in terms of: 1) long-term effectiveness and
permanence; 2) reduction of toxicity, mobility or volume through
treatment"; 3) short-term effectiveness; 4) implementabilitYi and
5) cost. The balancing test emphasized long-term effectiveness
and permanence and the reduction of toxicity, mobility and volume
through treatment; and considered the preference for treatment as
a principal element, the bias against off-site land disposal of
untreated waste, and community and state acceptance. The
selected remedy provides the best balance of trade-offs among the
various alternatives.
D~J73
9/15/94
-------
The 'No Action alternative, SC1, is not protective of human health
and the environment. EPA evaluated alternatives SC2A, SC2B, SC6'
and SC7 to determine which one provided the best balance in
terms of the criteria presented above. Alternative SC6 was
selected as the limited source control remedy because of its
long-term effectiveness and it provides the most significant
benefits for the cost. The EPA has determined that it is not
practical to treat SSDAl "hot spot" materials because of the
relatively small volume of waste and the complexity of
contaminants which rules out most treatment processes with the
exception of incineration. Of all of the limited source control
alternatives only SC7 provides for treatment of waste to provide
a reduction in toxicity, mobility and volume of contaminants.
Metals contamination in the waste would not be addressed through
incineration. Due to the heterogeneity of the hot spot waste,
other treatment methods ~re relatively unsuitable. . Incineration
is significantly more costly than SC6. Alternative SC7 ~lso has'
additional problems associated with it which include: off-site
transportation' of highly contaminated materials onto public
roads, which could result in a traffic accident which could lead
to an uncontrolled exposure to these contaminants for some period
of time; increased truck traffic through Town; and limited
availability of treatment facilities. Overall, SC6 provides the
best balance of protectiveness to human health and the
environment for the cost.
During predesign, studies of landfill soil gases will determine
if natural venting or treatment of these gases is appropriate.
If treatment is selected, this would provide a small reduction in
TMV for this selected remedy.
E.
The Selected Remedy does not satisfy the Preference for
Treatment which Permanently and Significantly Reduces the
Toxicity, Mobility or Volume of the Hazardous Substances as
a principal ~lement because treatment of the entire landfill
area is impracticable. .
CERCLA and the NCP set forth the process by which remedial
actions are evaluated and selected. Because many CERCLA
municipal landfill sites share similar characteristics, they lend
themselves to remediation by similar technologies. EPA has
established a number of expectations as to the types of
technologies that should be considered and alternatives that.
should be developed; they are listed in the National Contingency
Plan (40 CFR 300.430(a)(1» and EPA Guidance Document "Conducting
Remedial Investigations/Feasibility Studies for CERCLA Municipal
Landfill sites" EPA/540/P-9l/001.
The selected remedy includes capping of the landfill waste. The
large volume and heterogeneity of waste of the Site makes
treatment impractical. Excavation and treatment ~f such a large
volume would also involve unacceptable risk to human health and
the environment and would not be cost effective.
[)94.178
9/1 5/94
-------
The selected alternative does utilize a combination of methods to
achieve protection of human health and the environment.
Excavation of the SSDAl discrete "hot spot" materials in
combination with capping and soil gas collection will address
principal threats. posed by potential exposure to contaminated
subsurface soils, groundwater below the Site and landfill soil
gases. Predesign studies will determine if landfill soil gas
will require treatment or could be vented to the atmosphere.
Groundwater will be further studied and the necessary response
action will be addressed in a final ROD. It.is expected that
installation of the impermeable landfill cap will result in a
significant gradual improvement of the groundwater quality down
.gradient of the landfill site. .
XII. DOC~ENTATION OF NO SIGNIFICANT DIFFERENCES
EPA presented a Proposed Plan (preferred Alt~rnative) for
remediation of the Site in May 1994~ As described in the
Proposed Plan (and previously in Section X of this ROD), the
limited source control alternative includes, among other things,
construction of a single-barrier low permeability cap over the
northern part of the landfill and a RCRA Subtitle C composite
barrier low permeability cap on the southern portion of the
landfill; excavation and consolidation of the SSDAl discrete
materials and placing these materials within a lined cell in the
southern part of the site; and installation of a gas collection
and, if necessary, treatment system; and a long-term monitoring
plan.
This interim remedy includes the following change from the
Proposed Plan. Under the Proposed Plan, EPA proposed to proceed
with two operable units. Under the first operable unit, EPA
proposed to implement limited source control by capping the Site.
EPA then proposed that groundwater studies be conducted and that
groundwater be addressed under a second operable unit.
Rather than proceed with two operable units, EPA has decided to
implement an interim remedy to address, in part, the source of
Site contamination by capping the Site. This interim remedy
requires that additional groundwater studies will be undertaken
concurrent with the implementation of the cap and will be
followed by a final remedy after the necessary additional studies
have been completed. This approach does not modify the scope,
performance or cost of ~he remedy. Further, EPA believes that.
this approach is more consistent with the implementation of a
limited source control alternative and effectively addresses
concerns expressed by the public about the necessity of taking
final action based on the groundwater studies that are required
under this interim remedy.
094-178
9/15/94
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XIII.
STATE ROLE
The Connecticut Department of Environmental Protection has
reviewed the various alternatives and has indicated its support
for the selected remedy. The State has also reviewed the RIfFS
Report-and Risk Assessment to determine if the selected remedy is
in compliance with applicable or relevant and appropriate State
environmental laws and regulations. The State of Connecticut
concurs with the selected remedy for the Old Southinqton Landfill
site. A copy of the declaration of concurrence is attached. as
Appendix C.
094-178
9/15/94
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APPENDIX B
RISK ASSESSMENT TABLES 2 THROUGH 10
D94-17S
-------
ContaminantsQf-o..
Concern
aceonaphthene ----
. acenaphthylene
anthracene
arsenic
benzo( a) anthracene
benzo(a)pyrene
benzo(b )fluoranthene
benzo(g, 11. i) perylene
benzo(k)fluoranthene
beryllium
cadmium
chrysene
dibenzo (a. h )anthracene
fluoranthene
fluorene
ind~no(11213-cd)pyrene
lead .
manganese
naphthalene
pllenantllren e
pyrene
TABLE 2 .
SUMMARY OF CONTAMINANTS OF CONCERN
IN NORTHERN AREA SURFACE SOILS .
-- Average'''' Maximum ''''0__. -Freque'ncy.of
Concentration Concentration Detection
....l!llilLIsID--. . (mg/kQ) .
0.27 1
0.27 1.3
0.33 1.1
1.42 2.6
1.16 4.6
0.71 3.5
1.1 5.7
0.3'2 1.2
0.8 3
0.46 0.66
0.33 1.1
1.1 4.1
0.33 1.3
1.96 706
0.26 0.79
0.57 2.8
32.9 177
324 408
0.21 0.46
1.46 5.5
, .99 8.2
--.--... .
1 2/1 i
8/17
12/1 7
5/8
16/17
15/1 7
16/17
13/17
16/17
818
2/8
1 6/1 7
1 1/1 7
17/17
10/17
. 15/17
8/8
8/8
7117
16/17
16/16
'."-....
-------
Con'tamlnantsof"
Concern
..... ,.--.-...
acenaphthene
acanapllthylene
anthracene
aroclor 1 254
aroclor 1260
arsenic
benzo(a)anthracene
benzo (a) pyrene
benzo(b)fluoranthene
benzo(g,h,i)perylene
benzo(k)fluoranthene
beryllium
chrysene
dibenzo(a,h)anthracene
fluoranthene
fluorene
indeno(1,2,3-cd)pyrene (.
lead
manganese
naphthalene
phenanthrene
pyrene
TABLE 3
SUMMARY OF CONTAMINANTS OF CONCERN
IN SOUTHERN AREA SURFACE SOILS
, Average Maximum
Concentration Concentration
--~- (mg/kg)
0.05 0.07
0.19 0.42
0.21 . 0.41
0.06 0.44
0.05 0.16
1.54 2.7
0.38 1.6
0.24 1
0.58 ' 2.1
0.32 .1.2
0.36 1.2
0.62 2,9
0.54 . 1.8
0.19 0.39
0.59 2.8
0.18' 0.24
0.29 1.2
57.5 372
324 418
, 0.06 0.09
0.49 2
0.67 4.5
Frequency of-
Detection
2/21
5/21
4/21
2/21
3/21
1 5/21
1 0/21
. 10/21
1 0/21
7/21
'0/21
13/21
1 0/21
5/21
1 3/21
2/21
9/21
21/21
8/8
4/21
11/21
-------
___0_- .
T AS LE 4
SUMMARY OF CONTAMINANTS OF CONCERN
IN ON-SITE SEDIMENTS .
.,. -Average---- H- r.iaximum .Frs'q'uency: Of- '.
Concentration Concentration Detection
. ...-.. ,__JD}.91kg) (mg/kg)
0.31 0.54
0.31 0.61
0.54 1.3
0.18 0.35
4.73 . 10.4
2.27 6.1
2.29. 5.6
2.97 8.8
0.98 1.7
2.29. .5.4
0.47 0.89
2.07 7.8
0.66 1.5
3.82 18
0.36 0.66
1.75 3.2
2793 11900
0.23 0.23
2.02 9.8
3.02 14
..--....-....
C'ontam inants"qf
Concern
acenaphthene
acenaphthylene
anthracene
aroclor 1260
arsen ic ,
benzo(a)anthracene
benzo(a)pyrene
benzo (b )fluoranthene
benzo(g,h,i)perylene
benzo(k)fluoranthene
beryllium'
chrysene
dibenzo (a, h)anU1racene
tluoranthene
fluorene
indeno(1,2,3-cd)pyrene
manganese
naphthalene
phenanthrene
pyrene
2/7
3/7
3/7
2/7
7/7
4/7
3n
4/7
3/7
3/7
3/7
6/7
3/7
7/7
3/7
3/7
7/7
'/7
7/7
-------
TABLE 6
SUMMARY OF CONTAMINANTS OF CONCERN
IN SURFACE WATER
-----. . u--x'ierage Maxlmum- - .
. concentration Concentration
.__.~. __(mg/LJ
0.09 0.27
0.006 0.015
. 0.002 0.01
0.0007 0.0007
0.002 0.002
0.005 . 0.009
0.57 2.21
0.003 0.003
0.03 0.24
con'tamina'nts ''Of
Concern
..... -...,-.-'"
barium
carbon disulfide
chromium (hexavalent) (1)
di - n - butylphthalate
1,3-dichlorobenzene
1,2-dichloroethene (total)
manganese
trich loroethene
zinc
'--Frequenc'y of ,-
Detection
11/11
4/11
2/11
2/11
2/1'
2/11
, 1/1 1
2/11
2/11
-------
Contaminants of
Concern
benzene
ethylbenzene
styrene
tetrachloroethene
toluene
1,1,1-trichloroethane
trichloroethene
xylenes
Contaminants of
Concern
benzene
ethylbenzene
styrene
tetrachloroethene
toluene
. 1,1, 1-trichloroethane
trichloroethene
xylenes
TAB LE 7
SUMMARY OF CONTAMINANTS OF CONCERN
IN OUTDOOR AIR IN THE NORTHERN AREA
Average Maxim~m. Frequency of
Concentration Concentration. Detection
(mg/m3) (mg/m3)
3. 7E -06 2.2: -05
4.9E-06 1.6E-05
3.5E-06 9.0E-06
1.6E-07 2.1 E-07
3.9E-05 2.7E-04
1.4E-06 9.2:-06
1.9E-07 4.9E-07
2.8E-05 9.8E-05
TABLES
SUMMARY OF CONTAMINANTS OF CONCERN
IN INDOOR AIR IN THE NORTHERN AREA
Average Maximum'
Concentration Concentration
(mg/m3) (mg/m3)
5.7E-05 3.4E-05
7.7E-05 2.5E-04
5.4E-05 1.4E-04
2.4E-06 3.2:-06
6.1E-04 1.1::-03
2.1 E-05 1.4E-04
2.9E-06 7.5::-06
4.3::-04 1.5::-03
717
717
217
117
717
717
317
717
Frequency of
Detection
717
717
217
117
717
717
3/7
-------
. TABLE 9
SUMMARY OF CONTAMINANTS OF CONCERN
IN OUTDOOR AIR IN THE SOUTHERN AREA
Average Maximum. Frequency of
Concentration Concentration Detection
(mg/m3) (mg/m3)
3.9::-05 2.1 E-04
3.4E-06 1.6E-05
9.4E-07 2.0E-06
3.2::-05 3.2E-04
2.SE-05 1.1 E-04
3.4E-05 3.5E-05
4.8E-05 2.0E-04
7.4E-06 3.8E-05
4.3E-06 8.5E-06
1.6E-04 5.8E-04
1.1 E-04 1.3E-03
TABLE 10
SUMMARY OF CONTAMINANTS OF CONCERN
IN INDOOR AIR IN THE SOUTHERN AREA
Average Maximum Frequency of
Concentration Concentration Detection
(mg/m3) (mg/m3)
2.2E-04 1.2E-03
1.SE-05 9.0::-05
5.2E-06 1.1 E-05
1.8E-041.EE-03
1.5E-04 5.9::-04
1.9E-04 1.9::-04
2.7E-04 1.1 ::-03
4.' E-05 2.' E-04
2.4E-05 4.7E-05
9.0E-04 3.2E-03
5.8E-04 7.3E-03
Contaminants of
Concern
benzene
cis-1,2-dichloroethene
trans -1.2 - dichloroethene
ethylbenzene
methylene chloride
styrene
toluene
'1,1,1-trichloroethane
trichloroethene
vinyl chloride
xylenes
Contaminants of
Concern
benzene
cis-1,2-dichloroethene
trans-1,2-dichloroethene
ethylbenzene
methylene chloride
styrene
toluene
'.',1-trichloroethane
trichloroethene
vinyl chloride
xylenes
18/21
8121
3/21
19/21
9121
2/21
21/21
9121
2/21
4/21
19/21
18/21
8/21
3/21.
19/21
9121
2/21
21/21
912'
2/21
4/21
-------
APPENDIX C
CONNECTICUT DEPARTMENT OF ENVIRONMENTAL PROTECTION
CONCURRENCE LETTER
D94.I7S
-------
!j STATE OF CONNECTICUT
~ DEPARTMENT OF ENVIRONMENTAL PROTECTION
~~~
~
:~.\\. \ IIIII'I/./~
.: r. . ~"-.' :::.
. --,1-.'.
-:; -'-'.c.i ~
~-=- ~
?';. ,""
"1~J\r\1~"
September 15, 1994
RECEiVED
John P. DeVillars
Regional Administrator
U.S. EPA Region I
J.F.K. Federal Building
Boston, MA 02203
SEP 2 1 1994
OFiiCE OF tHE ~~ PDMt\aS;,..AI;,.
Dear Mr. De Villars:
The Connecticut Department of Environmental Protection (CT DEP) CODCurs with the interim
remedial action for limited source control selected by EP A for the Old Southington Landfill
Superfund Site in Southington, Connecticut. The interim remedial action is described in detail
in the Proposed Plan dated May, 1994 and in the. Record of Decision dated September 1994.
Concurrence with EP A's selected interim remedial action for limited source control at the Old
Southington Landfill Site shall in no way affect the Commissioner's authority to institute any
proceeding to prevent or abate violations of law, prevent or abate pollution, recover costs and
natural resource damages, and to impose penalties for violations of law, including but not limited
to violations of any permit issued by the Commissioner.
, "
~erelY,
\~'1vl~(~
Timothy R.E. Keeney
Commissioner
r . .
TREK:CAL:c1
(PriDted OD Recycled Paper)
79 Elm Street. Hartford, CT 06106.5124
-------
o
APPENDIX D
. APPLICABLE OR RELEVANT AND
APPROPRIATE REQUIREMENTS
1)9.1..1 i 8
-------
~kdium
N/A
----
N/A
'»4.1111
qJI~JQ.4
RC(luircmCIlIIl
USEI' A 'Ium:ln Ile.nlth Assessmcnt
Cancer Siopc factors(eSFs)
USEI'A Rcrcrcllcc Doscs (RIDs)
TUC
Tue
TABLE J
OLD SOlrn IINGTON LANI)(i'ILL SUI'EItFUND SITE
CIIEI\IICAI.-SI'ECIFIC AHAn~ AND Tncs
Statns
Synupsill of RC(ltiircmcnt - ..
eSFs are devcloped by EPA fur hcalth effects
assessments or evaluation hy the 1-lum3n Health
Asscssmcnt Gruup (IIIIAG).
IUDs are duse levels developcd by EI' A fur use in Ihe
charnclcri7A11ioll of .-isks due 10 nun-carcinogens in
variuw; medin.
(\
--
:-:,':;! .i\dion- 16:00- -~iIce.t -io-: aiiain_A RA R".
lllese values present Ihe mosl up to dale cancer risk
polency infonnalion. eSFs were used 10 compute the
individual cancer risk resulting from exposure to
contaminRnts.
IUDs are Iypically employed 10 characleriz.e risks of
groundwaler conlaminanl exposure -(for ingeslion
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TAIII,E 2
OLI) SOl/TIIINGTON LANIWILL SlJl'EnFtJNI> srm
ACTION-SPECIFIC ARAHs ANI) TIICs
- -- -
Medium nt'clui rCnu'nl~ Strehls .s}'nop!;i~ of l{('cluill'lI1('nt Action to he lakcn 10 allain ARAR
WII~te h'.!kral RCRA- Clo!;\lre ~ncl I'ost- Relevant Ih'lluirl'~ inslallation nnd mainlenance of n rinnl cover The cap nnd associalcd sy!;tems in Ihe northern portion
Clo~ure (If Municipal Solid WAste and system that is designed to minimil.c infiltration And of the Site will be designed to meet or exceed the
l.aIllHill~ (,10 CFR l':1It 25R Suhpart Appropriate crosion. AI!;o rctJuires 1c.1chate collection, closure/posl-closure rccluiremenls for municipal !;olid
F). grcllliulwakr mIJnitming, and landfill gas moniloring. waste IrelttJfilis.
-
\\' ash' Vt~~I.c'I:i!I. IH'RA - E IIII' 1 geucy Rclev.lllt E~tahlishc~ requirements for minimi7.ing the possihility The interim remccly willmcct the !;uhstantive
'I', eparednc~s a 1111 I',cvcntion; a 1111 (If Ii re, cx "Iosion or release of hazardous material and rccluiremenls specified in Ihe!;e regulation!; through Ihe
Contingency Planning (40 CFR Part Appropriate contingency plan recluirements in the event of rire, preparalion and implementation of appropriate plans
}Ii,t Suhpmls <\ D). I'xplosion or release fmm 11 facility, IInd procedures.
Wasil' El~lknd RenA - Closure alltl Post. Rclevl1nt Details general recl"iremcnts for closllre AIIII posl- 111e CAp and associated syslems will be designed to
('IOSIIIC Rl'cluircmcnts (40 CFn I'art Alltl closure of ha1..1l'llous waste facililies. mcellhesc requiremenls.
2M Suhp:lll G), Appropriate
Wastl' USEP A TechnicAl Gllidance - Final TlJC Presents technical specifiealions for Ihe design of The cap and Rssocialcet systems in the southem portion
Covers on flalJudc)lJs Wasle lIIulli-layer covers at landfills where halJmlolls Wastes of Ihe Sile will be designed If) meet Ihese de!;ign
1.:IIuli ills lIIul SUII:ll'C wel.c disposed of. !lpecificaliolls.
IlilpOlllltllllcllts, EI' A/S JO-SW -89-
047.
Air Fcdcml CIc.111 Air Act - National Relevant Establishes cmissioll levels for cighllistcd hazardous 1111' gas colleclion and trealmenl syslem will be .
Emi!:sioll Standanls for Ilazuniolis alld air pollutants emitted from particular types or facilities. designcet to allain Ihe NESHAP numerical standards ror
Air I'oll(llallts (NESIIAl's), 40 CFR Approprinte polenliallandfill gases, including hcnl..cne and vinyl
1':lIt 61: chloride.
Ail fl'.d~T:JLClcan Air Act - Non- THC Rq:llialiolls woulcl require NMOC-specilic gA!: 11le proposed regulatiolls will he considcrccl in Ihe
1I...lh:lIlt~ III g:lllic l:ollll'0lln1Is l'ollcdioll nllli (:lIlItllll systCllls, lIIollitoring, nnd gAS design of the lAndfill gas collection allli tr~lt!llelit
(NfvIOC!:) (Proposed lUll' - 56 FR genemlioll estimates. The proposed nile would also system.
2446R, 10 he codified at 40 CFR eslahlish a pelfOrln:lllce stAndard for NMOCs cmissidns
1':111 60 511hp:lll WWW), from !IIunicipal solid wa!:le lAndfills.
\V:lsll' (clml"'f!!!:.!IJ 50licl WlIslc Applicnhle Establishes stundanls for the closure of solid WAste Those portions of the regulations that are !IIore
Mallagcment Regulations (RCSA dispo!:al oreas. slringent Ihan Ihe fceteral RCRA Sublille D regulations
27a-209.1 - 15) will be complied with.
. .
Wastl' C(.I!lIIl'Cfi(t~! IIAIJllllous Waste Relevant Establishes stalldards for the lIIanagcmenl and closure 1110se portions of Ihc regulalions Ihal arc more
Mnlla~ClIIl'nt Rl~gulntiolls (RCSA 111\(1 of 11I\1JlHlous waste fncililies. slringent Ihan Ihe federal RCRA Sublitlc C rcgulalions
nil +11)(t')-IOO - I W) . Appmpriale will be complied wilh.
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TABLE 2
OLD SOtITIIINGTON LANIWILL Stll'En""NI> SITE
ACTION-SPECIFIC AnAR~ ANI> TIICs
- - -
T\.1 cd i UIII RCtlui rClI1enl~ St:tIU~ Synop~i~ of RCcJllirelllent Action to be t:lken to Attllin ARAR
Air C"'lIIl'Cticut Air Pollution Applic:thle \{etluilc~ that st:ttionary sOllrces of air pollllt:tnts meet The landfill gas collection and treatment system, will be
R('gulalion~ - Stationary Sources spcci IInl standards prior to constmction and operation. designct.l to meet substantive standards establishct.l
(CGS 22a-174-3). May rccluirc controls to abatc pollntion. under these rcgulations.
Air Conlll'Cticut Air Pollution Applicahle Requires that reasonahle precautions be t:tkcn to Activities involving building demolilion and landfill cap
Rq:utatiolls - rugilivc 1>1I5t prcvent particulate mailer fmm hccoming airhome conslnlclion will be conducled in a m:tl1l1er \(j minimil.c
Emissions (C<..iS 22a-174-1 Rlhl). during dcmolition Rm.! construction activities ami fugilivc dust emissions from thc Site.
nl:lll'rial handling opemtions.
Air ~ :~_II!HC'(J.i.9!l Air Pollution Applicnhle Pwhihils the cmission of any suhst:mcc IIl:It constitutc.o; Site remediation aClivities will be planncd 10 contrnllhc
Regulat ious - <':ontlOl of Otllll s a nuisance hecause of ohjectionable odor. release of objectionable odors from the Site.
(CGS 22a-I74-23).
Air ~nncdicI!! Air Pollution Applicohle ESlablishes regulalions and emission ralcs for 1116 landfill gas collection and trealment syslcm, will be
Regulations - Incinl~ration (CGS incincrators. dcsigned to meet the substantive requiremcnts of these
22a-174-IRlc/). regulotions.
Air ~.9.m1('Cticut Air Pollution Applicahle Estnhlishc!; tcsting requircmcnls Rnd allowahlc Direct dischargc.c; to the air from the landfill gas
RC~~lIlations - Iialmdous Air cCJI\ccntrations for IIny stack cmis!;ion for the collection Rnd treatment system will be dcsigned to
Pollutauts «,(i5 7.711-17<1.7.11). t'onslilm'nts listcd. meet thr. suhstantivc rC(luircmcnts of these rcgulations
so that thc numeric criteria arc nol exceeded.
Waler Connl'Cticut Water Qualily Applicahlc ESlahlishes numeric and Rntidegradation criteria for Remedial activities will be consistent with the
Simulanis (WQS) (CGS 22a-426) glOundwatcr and surfllce water. anlidegradation criteria in the WQS. If any remedial
aclivitics occur thllt nre reguillted under theRC
provisions, the use of engineering controls and bcst
management practices may be required to prevent or
minimize adverse impacts to the waters of thc slale.
W lllel COIIIIl'Ct iCllt Woter Pollution Relevant ESlllhlishes dischargc pcrmit requircments. If 8n1 remedial activities resull in discharges 10
Control Act-Permitting nnd groundwater or surface waler rcgulaled under Ihis Act,
Reclnircmcnts (CGS 22a-430- Appropriatc they shall meet the requiremcnts of this Act.
4301hl).
Wilier Connccticut Walcr Pollution Relcvant Establishes permitting rccluiremcnts for discharges to If any remedial activities result in any direct discharges
Conlrol Regulat ions- Permilling and. sur-face water, groundwatcr Rnd rOTWs. to surface water or groundwater, they lIIust comply
Rt'gulations (22a-430 1-8) Al'pmpriatc with the substantive rccluirements in Ihese regulations.
Specific criteria may be established for dischargcs so
thot numcric criteria established in the WQS are not
violated.
'''''''.1 ,.
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TA nLl~ 3
ou> SUUTIIINGTON LANIWILL SUI'I~IUlUND SITE
LOCATION-SPECIFIC ARAlb AND TDC!>
.'
--. - ..-- n ..-. - _0.- --'. - ..-....--..- --. .~--. -. -. .- - - --.
Meclill/ll Rc'cJlli n~/IIl'nl:; StRIII!! Synopsis of Rcclui,cment Action.to.b~taken to aUnin ARAR
Wetlands Fcdcrul Executive Order on Applicabie Recluires federal agencies to avoid impacts associated TIle landfill cap and the dredging of waste materials
Protcction nf Wetlands (E.O. with the destruction or 105s of wetlands, minimize will be designed to minimize impacts to the shoreline of
IIC)'JO, 40 eFR P:IIt 6, ApI', A). plliential harlll, preserve Rnd enhance wetlands, and Dlack Pond. To the extent necessary, wetlands
avuid sUl'l'ol1 uf new construction in wetlands if a restoration and/or replication will be undertaken.
pr:lcticahle Alternative exists.
Wl'llands I'cd.~rul Clean Wilier Act ~404 - Applicahle RC
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