United States
Environmental Protection
Agency
Office of
Emergency and
Remedial Response
EPA/ROD/R02-92/170
March 1992
SEPA Superfund
Record of Decision:
General Motors/Central
Foundry Division , NY
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NOTICE
The appendices listed in the index that are not found in this document have been removed at the request of
the issuing agency. They contain material which supplement but adds no further applicable information to
the content of the document All supplemental material is, however, contained in the administrative record
for this site.
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50272-101
REPORT DOCUMENTATION
PAGE
1. REPORT NO.
EPA/ROD/R02-92/170
3. Recipient's Accession No.
4. Title and Subtitle
SUPERFUND RECORD OF DECISION
General Motors/Central Foundry Division, NY
Second Remedial Action - Final
5. Report Date
03/31/92
7. Author(s)
8. Performing Organization Rept No.
9. Performing Organization Name and Address
10. Project/Task/Work Unit No.
11. Contract(C) or Grant(G) No.
(C)
(G)
12. Sponsoring Organization Name and Address
U.S. Environmental Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
13. Type of Report & Period Covered
800/000
15. Supplementary Notes
PB93-963803
16. Abstract (Limit: 200 words)
The 270-acre General Motors/Central Foundry Division site is an aluminum casting plant
in Massena, St. Lawrence County, New York. The site is bordered on the north by the
St. Lawrence River; on the east by the St. Regis River Mohawk Indian Reservation, which
includes Turtle Creek and wetlands; on the south by the Raquette River; and on the west
by a manufacturing plant. Land use in the area is mixed industrial and residential,
with the nearest residence located 300 feet from the site. The site contains at least
seven areas that were used previously as waste disposal areas. From 1959 to 1980,
hydraulic fluids containing PCBs were used in the manufacturing process at the plant.
During the 1960's and 1970's, PCB oil-laden wastewater was discharged onsite into four
industrial lagoons, resulting in PCB-laden sludge. The sludge from these lagoons was
• removed periodically and placed in the unlined North and East Disposal Areas and in the
Industrial Landfill. Solid industrial wastes were also placed in the Industrial
Landfill. In 1975, a berm surrounding the East Disposal Area was breached and water
and sludge flowed to the St. Regis Mohawk Indian Reservation and Turtle Creek. Visible
spill material was removed from the Reservation and relocated to the site property.
From 1985 to 1989, General Motors investigations detected contamination in soil,
(See Attached Page)
17. Document Analysis a. Descriptors
Record of Decision - General Motors/Central Foundry Division, NY
Second Remedial Action - Final
Contaminated Media: soil, sludge, debris, gw
Key Contaminants: VOCs (TCE) , other organics (PAHs, PCBs, phenols)
b. Identifiers/Open-Ended Terms
c. COSATI Field/Group
18. Availability Statement
19. Security Class (This Report)
None
20. Security Class (This Page)
None
21. No. of Pages
86
22. Price
(See ANSI-Z39.18)
See Instructions on Reverse
OPTIONAL FORM 272 (4-77)
(Formerly NTIS-35)
Department of Commerce
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EPA/ROD/R02-92/170
General Motors/Central Foundry Division, NY
Second Remedial Action - Final
Abstract (Continued)
sludge, debris, sediment, ground water and surface water.. In 1988, an interim cap was
placed over the industrial landfill. A 1990 ROD addressed most affected areas of the
site, including the St. Lawrence River System sediments, contaminated ground water, soils
on the facility and the St. Regis Mohawk Indian Reservation, and material at four lagoons
and the North Disposal Area. This ROD provides the final remedy for the contaminated
soil, sludge, debris, and groundwater at the East Disposal Area and the Industrial
Lagoon. The primary contaminants of concern are VOCs, including TCE; and other organics,
including PCBs, phenols, and PAHs.
The selected remedial action for this site includes excavating 174,000 cubic yards of
soil, sludge, debris, and all visibly oily soil containing greater than or equal to
500 mg/kg PCBs from the East Disposal Area, followed by onsite treatment by either
biological, thermal, or other treatment as determined by the results of treatability
studies performed as part of remedy for OU1, disposing of debris offsite; consolidation
and containment of soil with PCBs below 500 mg/kg in the East Disposal Area along with
the treated soil and sludge; followed by covering with a composite cover; recontouring,
regrading, and containing contaminated material from the Industrial Lagoon onsite with a
composite cover; installing a slurry wall and runoff collection system to control ground
water migration from the East Disposal Area and the Industrial Lagoon, treating ground
water using air stripping to remove VOCs and carbon adsorption to remove PCBs with onsite
discharge to the St. Lawrence River; monitoring ground water, surface water, and air; and
implementing institutional controls, including deed restrictions, to discourage use as a
residential area. The estimated present worth cost for this remedial action ranges from
$31,000,000 to $45,000,000, which includes an annual O&M cost of $567,000 for years 0-2
and $200,000 for years 3-28.
PERFORMANCE STANDARDS OR GOALS: The chemical-specific clean-up goal for treated soil
residuals is 10 mg/kg for PCBs, which is an onsite residual disposal ARAR waiver of the
TSCA regulation concerning landfill requirements of 2 mg/kg for PCBs; for sludge with
initial PCB >500 mg/kg, clean-up residual level is 2 mg/kg (TSCA). Ground water clean-up
goals are based on SDWA and state standards, and include PCB 0.1 ug/1, TCE 5 ug/1, and
total phenols I ug/1.
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SITE
Name:
Location:
MRS Score:
NPL Rank:
EPA Contact:
ROD
Date Signed:
Remedy:
Capital Cost:
ROD FACT SHEET
General Motors - Central Foundry Division (second
operable unit)
Massena, St. Lawrence County, New York
Group 5
350
Lisa Carson, (212) 264-6857
3/31/92
*•
Excavation and treatment of sludge, visibly oily
soil, and highly contaminated soil in the East
Disposal Area; in-place containment of less
contaminated soils and control of groundwater in
the East Disposal Area through the use of a
composite cap and a slurry wall, and; recontouring
and regrading followed by containment of
contaminated material and groundwater control in
the Industrial Landfill through the use of a
composite cap and slurry wall.
$ 28,000,000 - $ 42,000,000 (Costs will depend on
the type of treatment technology used at the Site.
Costs range from $ 28 million for solidification
to $ 42 million for incineration.)
O & M/Year:
Present Worth
LEAD
Potentially Responsible Party
$ 567,000 (years l and 2); $200,000 (year 3 - 30)
$ 31,000,000 - 45,000,000
Main PRP:
WASTE
Type:
Media:
Origin:
General Motors Corporation
PCBs
Sediments, soil, sludges, and groundwater
On-site disposal of PCBs used in hydraulic fluids
Est. Quantity: Approximately 598,000 cubic yards of PCS
contaminated material addressed in this ROD
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DECLARATION FOR THE RECORD OF DECISION
SITE NAME AND LOCATION
General Motors Corporation - Central Foundry Division Site
Massena, St. Lawrence County, New York
STATEMENT OF BASIS AND PURPOSE
This decision document presents the selected remedial action for
the second operable unit for the General Motors - Central Foundry
Division Superfund Site, in Massena, New York, which was chosen
in accordance with the requirements of the Comprehensive
Environmental Response, Compensation and Liability Act of 1980
(CERCLA), as amended by the Superfund Amendment and
Reauthorization Act of 1986 (SARA), and the National Oil and
Hazardous Substances Pollution Contingency Plan (NCP). This
decision document summarizes the factual and legal basis for
selecting the second operable unit remedy for this Site.
The New York State Department of Environmental Conservation has
not concurred on the selected remedy. The information supporting
this remedial action decision is contained in the Administrative
Record for this Site, the index of which is appended to this
.document.
ASSESSMENT OF THE SITE
Actual or threatened releases of hazardous substances at or from
this Site, if not addressed by implementing the response action
selected in this Record of Decision, may present an imminent and
substantial endangerment to public health, welfare, or the
environment.
DESCRIPTION OF THE REMEDY
This action or "operable unit" is the second of two operable
units that were planned for the Site. The first operable unit
Record of Decision, dated December 17, 1990, addressed the
threats resulting from the majority of the areas of the Site
including: contaminated sediments and soils in the St. Lawrence
and Raquette Rivers, Turtle Creek, and associated riverbanks and
wetlands (the St. Lawrence River System); runoff from the East
Disposal Area; contaminated sludges, soil, and debris in the
North Disposal Area, in and around the four Industrial Lagoons,
and in other areas on General Motors' (G.M.) property;
contaminated soil on the St. Regis Mohawk Reservation; and
contaminated groundwater associated with the Site.
This second operable unit Record of Decision addresses the
remaining areas of the Site by utilizing a mixed
treatment/containment remedy in the East Disposal Area and
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containment of the Industrial Landfill at the Site. The
combination of this second operable unit Record of Decision and
the December 17, 1990 first operable unit Record of Decision
comprise a comprehensive remedy for the Site.
The major components of the second operable unit selected remedy
include:
Excavation of soil containing polychlorinated biphenyls
(PCBs) at concentrations at or above 500 parts per
million, all sludge, and all visibly oily soil from the
East Disposal Area at the Site;
Consolidation and in-place containment of less
contaminated soils (containing PCBs at concentrations
above 10 ppm and below 500 ppm) in the East Disposal
Area and control of groundwater migration from the East
Disposal Area through the use of a composite cap and a
slurry wall. (The slurry wall is contingent on the
results of additional groundwater testing to be
conducted during design. See page 41 of the ROD
Decision Summary.);
Recontouring, regrading, and containment of
contaminated material in the Industrial Landfill and
control of groundwater migration from the Industrial
Landfill through the use of a composite cap and slurry
wall (The slurry wall is contingent on the results of
additional groundwater testing to be conducted during
design.);
Treatment of excavated material from the East Disposal
Area by either biological treatment (or another
innovative treatment technology which has been
demonstrated to achieve Site treatment goals) or
thermal destruction to be determined by the U. S.
Environmental Protection Agency (EPA) following first
operable unit treatability testing. Treatability
testing was previously selected as part of the first
operable unit Record of Decision and EPA will base its
decision on the results of that testing. Treatment
residuals will be disposed on-site. (During first
operable unit treatability testing, other innovative
PCS treatment technologies will be tested concurrently
with biological treatment so that EPA will have
additional information in the event that biological
treatment proves to be unsatisfactory for treatment of
any Site material.) EPA will select the treatment
technologies to be employed, in consultation with
NYSDEC and the St. Regis Mohawk Tribe.
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iii
DECLARATION
The selected remedy is protective of human health and the
environment, complies with Federal and State requirements that
are legally applicable or relevant and appropriate to the
remedial action (or provides grounds for invoking a waiver of
these requirements), and is cost effective. This remedy utilizes
permanent solutions and alternative treatment technologies to the
maximum extent practicable and satisfies the statutory preference
for remedies which employ treatment that reduces toxicity,
mobility, or volume as a principal element.
Because this remedy will result in hazardous substances remaining
on-site above health-based levels in the Industrial Landfill and
East Disposal Area, a review will be conducted within at least
five years after commencement of remedial action and every five
years thereafter to ensure that the remedy continues to provide
adequate^protection of human health and the environment.
Con&tantine Sidamon-Eristoff
^Regional Administrator, Regiq,
U. S. Environmental Protect!
Da
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DECISION SUMMARY
GENERAL MOTORS - CENTRAL FOUNDRY DIVISION SITE
MASSENA, NEW YORK
UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
REGION II
NEW YORK
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TABLE OF CONTENTS
SITE NAME, LOCATION, AND DESCRIPTION 1
SITE HISTORY AND ENFORCEMENT ACTIVITIES 2
HIGHLIGHTS OF COMMUNITY PARTICIPATION .... 4
SCOPE AND ROLE OF RESPONSE ACTION 4
SUMMARY OF SITE CHARACTERISTICS 6
SUMMARY OF SITE RISKS 9
DESCRIPTION OF ALTERNATIVES . . 13
SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES 30
DESCRIPTION OF THE SELECTED REMEDY 38
STATUTORY DETERMINATIONS ... 42
ATTACHMENTS .
APPENDIX 1 - FIGURES
APPENDIX 2 - TABLES
APPENDIX 3 - ESTIMATED SLURRY WALL COSTS
APPENDIX 4 - RESPONSIVENESS SUMMARY
APPENDIX 5 - ADMINISTRATIVE RECORD INDEX
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1
SITE NAME. LOCATION. AND DESCRIPTION
The General Motors - Central Foundry Division (G.M.) Site is
located on Rooseveltown Road in St. Lawrence County in Massena,
New York. The Site consists of several waste areas at an active
G.M. manufacturing facility along with contaminated soils on
G.M.'s property and on the St. Regis Mohawk Reservation,
contaminated sediments in the St. Lawrence and Raquette Rivers
and in Turtle Creek, associated riverbanks and wetlands, and
contaminated groundwater.
The G.M. facility is bordered on the north by the St. Lawrence
River, on the east by the St. Regis Mohawk Indian Reservation, on
the south by the Raquette River and on the west by the Reynolds
Metals Company and property owned by Conrail (see Figure 1).
Land use in the area surrounding the Site consists of mixed
residential and.industrial uses. The Reynolds Metals Company
facility and another facility west of the Site owned by the
Aluminum Company of America are presently under investigation by
the U. S. Environmental Protection Agency (EPA) and the New York
State Department of Environmental Conservation (NYSDEC). The
nearest residence is located on the St. Regis Mohawk Indian
Reservation approximately 300 feet from the G.M. facility
boundary. St. Lawrence River flows are controlled by the Moses-
Saunders Power Dam, located approximately four miles upstream
from the Site.
The G.M. facility consists of approximately 270 acres of
industrial and undeveloped land. Wetlands lie east of the
facility in the area surrounding Turtle Creek. There are no
federally listed endangered or threatened species known to
inhabit the St. Lawrence River. However, the River does support
a number of New York State listed endangered, threatened and
special concern fish species. The River and adjacent habitats
also provide nesting for a variety of water birds and shorebirds.
Federally listed endangered falcons and bald eagles have been
reported in the Massena area.
The Site, as defined by EPA, consists of several major areas
which are depicted schematically in Figure 2. The North and East
Disposal Areas and the Industrial Landfill contain soil, debris,
and sludge. The four unlined Industrial Lagoons contain liquids,
sludges, and solids and are referred to as the 350,000 gallon,
500,000 gallon, 1.5 million gallon and 10 million gallon lagoons.
The Site also includes contaminated sediments, riverbanks, and
associated wetlands of the St. Lawrence River, the Raquette River
and Turtle Creek (formerly called the unnamed tributary on the
St. Regis Mohawk Reservation) (these water bodies and associated
areas are collectively referred to as the St. Lawrence River
System), contaminated soil .on the St. Regis Mohawk Indian
Reservation, contaminated soil on G.M. property not associated
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with the specific disposal areas already mentioned, and
contaminated groundwater.
Groundwater flow generally reflects surface topography and flows
north toward the St. Lawrence River and northeast to Turtle
Creek. Turtle Creek and the adjacent wetlands serve as discharge
areas for shallow groundwater flow. There is also some limited
shallow groundwater flow south toward the Raguette River. A few
residents on Raquette Point rely on groundwater as a drinking
water supply. The majority of the Raquette Point residents obtain
water from a public water supply system which has its intake in
the St. Lawrence River at the mouth of the Raquette River,
approximately 1.5 miles downriver from the G.M. facility.
In general, the East Disposal Area and Industrial Landfill are
underlain by 20 to 30 feet of glaciolacustrine marine deposit and
glacial till (see Figure 3). These materials are underlain by a
lower glaciofluvial deposit which is approximately 10 to 15 feet
thick and which is underlain by another 40 to 60 feet of glacial
till. The average hydraulic conductivity of the lower
glaciofluvial deposit is somewhat higher than that of the glacial
till layers. Bedrock at the Site is generally located
approximately 120 to 140 feet below the natural ground surface.
SITE HISTORY AND ENFORCEMENT ACTIVITIES
G.M. has operated an aluminum casting plant at the Site since
1959. Until 1980, polychlorinated biphenyls (PCBs) were a
component of hydraulic fluids used in diecasting machines at the
G.M. facility. PCBs provided protection against fire and thermal
degradation in the high temperature environment of the diecasting
machines. G.M. no longer uses the diecasting process or PCBs at
the facility.
In the early 1960's, as part of routine operations, wastewater
containing PCB-laden oil passed through the 1.5 million gallon
lagoon and then to the St. Lawrence River. In 1968-1969, a lined
interceptor lagoon was added adjacent to the 1.5 million gallon
lagoon. This lined lagoon was subsequently buried and is
considered by EPA to be a part of the North Disposal Area. In
1976, a wastewater treatment system was installed at the plant.
In that system, wastewater was sent to the 350,000 gallon lagoon
for solids settling. Treated water was pumped to the 500,000
gallon and 10 million gallon lagoons for reuse as plant process
water. Periodically, water was discharged to the St. Lawrence
River from the 1.5 million gallon lagoon. The 1.5 million gallon
lagoon was not used for settling after 1976; however, water
passed through the 1.5 million gallon lagoon, which contained PCB
sludges, prior to discharge to the St. Lawrence River after 1976.
After further modifications to G.M.'s wastewater treatment
process, the 350,000 gallon lagoon was taken out of service in
1980. All four lagoons are subject to the PCB disposal
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requirements under the Toxic Substances Control Act (TSCA)
because they received and contain PCBs above regulated
concentrations and were in use as part of G.M.'s wastewater
treatment process after February 17, 1978, the cut off date for
cleanup and disposal of contamination that occurred prior to the
PCS regulations.
During operations, PCB laden sludge from the 1.5 million gallon
lagoon and from the wastewater treatment plant was periodically
removed to the North and East Disposal Areas and to the
Industrial Landfill. The Industrial Landfill has also received
foundry sand, soil and concrete excavated during plant
construction, diecasting machines, and solid industrial waste.
The Landfill was covered with an interim cap in 1987-1988. The
North Disposal Area also received construction debris, soil and
tree stumps. The East Disposal Area contains soil and sludge
along with construction debris and concrete. The North and East
Disposal Areas and the Industrial Landfill were not lined.
In 1975, a berm surrounding the East Disposal Area was breached.
Water and sludge flowed east to the St. Regis Mohawk Reservation
and to Turtle Creek. Visible spill material was removed from the
Reservation to G.M. property. In 1970, PCB contaminated soil
excavated during plant expansion was placed on the north bank of
the Raquette River. In addition, G.M. discharged surface water
runoff to the Raquette River until 1989 under a State Pollutant
Discharge Elimination System (SPDES) permit.
The G.M. Site was placed on the Superfund National Priorities
List (NPL) in September 1983 as a result of G.M.'s past waste
disposal practices. G.M. indicated a willingness to perform the
Remedial Investigation and Feasibility Study (RI/FS) for the
Site. On April 16, 1985, EPA and G.M. entered into an
Administrative Order on Consent (Index No. II CERCLA-50201) for
G.M.'s performance of the RI/FS. Draft and Phase II RI reports
were submitted to EPA in May 1986 and May 1988, respectively.
G.M. performed additional river sampling in February 1989 and
submitted a report on the additional sampling to EPA in May 1989.
On June 9, 1989, EPA approved the RI report, which consists of
the draft RI report, the Phase II RI report and the sediment
sampling report, for the Site. The RI report delineated those
areas in need of remediation throughout the Site. G.M. submitted
the draft FS report to EPA in November 1989.
The FS and first phase (or "first operable unit") Proposed Plan
for the G.M. Site were released to the public in March 1990. A
public comment period was held from March 21, 1990 through June
18, 1990 to accept comments on the first operable unit Proposed
Plan. On December 17, 1990, EPA signed the first operable unit
Record of Decision (ROD). The contents of the first operable
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unit ROD are discussed in the section "Scope and Role of Response
Action" which begins on page 4 of this document.
G.M. also entered into a 1985 Consent Order with EPA under the
authority of TSCA. In addition to payment of penalties for
failure to comply with certain TSCA regulations, G.M. agreed to
cleanup and close an abandoned PCB contaminated pump house on-
site. On March 12, 1991, EPA issued a TSCA complaint to G.M
charging improper off site disposal of PCB contaminated sludges.
This complaint has not yet been settled.
HIGHLIGHTS OF COMMUNITY PARTICIPATION
The second operable unit Proposed Plan for the G.M. Site was
released to the public on May 28, 1991. This document, along
with the RI and FS, were made available to the public in
information repositories maintained at EPA Region II offices in
New York city, at the Massena Public Library, and at the St.
Regis Mohawk Tribal Building. The notice of availability of
these documents was published in the Massena Daily Courier-
Observer on May 28, 1991 and in the People's Voice and the
Indian Times on May 24, 1991. A public comment period was held
from May 28, 1991 through July 29, 1991. The public comment
period was extended once upon the request of several interested
citizens. Notice of the extension was published in the
newspapers listed above on June 21, 1991.
Public meetings were held on June 25, 1991 at the Massena Town
Hall and on June 26, 1991 at the Mohawk School in Akwesasne. At
these meetings, representatives from EPA answered questions and
received comments on EPA's second operable unit Proposed Plan and
the other remedial alternatives under consideration. Responses
to comments received during the public comment period and at the
public meetings are included in the Responsiveness Summary which
is appended to this ROD. The Responsiveness Summary and ROD,
along with the Administrative Record for the Site, are available
at the information repositories referenced above.
SCOPE AND ROLE OF RESPONSE ACTION
In selecting a remedy for the G.M. Site, EPA divided the Site
into two phases or "operable units." Using two operable units,
EPA could better factor community concerns into its decision-
making process for cleanup of the Industrial Landfill. In August
1990, EPA .issued its "Guidance on Remedial Actions for Superfund
Sites with PCB Contamination," OSWER Directive 9355.4-01, August
1990. This guidance, commonly called "the PCB Guidance,"
recommends that when considering cleanup of areas which contain
large volumes of PCB contaminated material, a cleanup alternative
which combines treatment of highly contaminated material with
containment of less contaminated material be evaluated.
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The first operable unit ROD presents the selected remedy for most
areas of the G.M. Site, including the contaminated St. Lawrence
River System sediments, contaminated groundwater, soils on the
G.M. facility and on the St. Regis Mohawk Reservation, and
material in the four Industrial Lagoons and the North Disposal
Area at the Site. The second operable unit, which is the subject
of this ROD, addresses remediation of material in the East
Disposal Area and the Industrial Landfill at the Site.
The first operable unit selected remedy includes: dredging and
excavation of sediments and soils from PCB contaminated areas in
the St. Lawrence and Raguette Rivers and associated riverbanks
and wetlands with PCB concentrations above 1 part per million
(ppm); dredging and excavation of sediments and soils with PCB
concentrations above 0.1 ppm from Turtle Creek and the Raguette
River on the Reservation, and associated riverbanks and wetlands;
interim surface runoff control to prevent migration of
contamination from the East Disposal Area; excavation of PCB
contaminated sludge, soil, and debris with PCB concentrations
above io ppm in the North Disposal Area, in and around the four
Industrial Lagoons, and in other areas on General Motors
property; excavation of PCB contaminated soil on the St. Regis
Mohawk Reservation adjacent to the G.M. facility with PCB
concentrations above 1 ppm; recovery and treatment of
contaminated groundwater downgradient from the Site with
discharge of treated groundwater to the St. Lawrence River; and
treatment of dredged/excavated material by either biological
treatment (or another innovative treatment technology) or thermal
destruction. The treatment technology will be determined by EPA
following treatability testing. Treatment residuals are to be
disposed on the G.M. Site. Other innovative PCB treatment
technologies will be tested concurrently with biological .
treatment so that EPA will have additional information in the
event that biological treatment proves to be unsatisfactory for
treatment of any Site material.
In developing the first operable unit ROD, EPA evaluated
available data in the RI and FS reports for the G.M. Site. EPA
also analyzed the Site to ensure consistency with its PCB
Guidance. EPA determined that the first operable unit ROD remedy
was consistent with the PCB Guidance.
EPA is willing to consider data gathered during design and/or
implementation of the first operable unit remedy in order to
ascertain whether such data confirm that the first operable unit
remedy is consistent with the PCB Guidance. Consistent with the
PCB Guidance, EPA believes that each of the following types of
materials are not amenable to containment without prior
treatment: sludge; oily waste; soil with PCB concentrations
above 500 ppm; soil with phenol concentrations above 50 ppm;
material which is saturated with water; soil which contains PCBs
at concentrations below 500 ppm but which cannot be practicably
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segregated from sludge, oily waste, or soil with PCB
concentrations above 500 ppm; and/or, soil with PCB
concentrations between 10 and 500 ppm which is not described by
any of the above-listed characteristics, but which is of
insignificant volume such that treatment of such soil is cost-
effective. Based on data available in the RI and FS, EPA
believes that treatment of the above types of material will
result in a significant (on the order of 90%) reduction of the
PCB mass addressed in the first operable unit ROD.
In order to expedite Site cleanup, the second operable unit
remedy for the East Disposal Area and the Industrial Landfill
will be consistent with the remedy selected in the first operable
unit ROD. The remediation of the entire G.M. Site will be
complete only after EPA has implemented remedial actions for both
operable units. The final remediation of the Site is intended to
address the entire Site with regard to the principal threats to
human health and the environment posed by the Site. The findings
of the Risk Assessment are discussed in the section entitled
"Summary of Site Risks" which begins on page 9 of this document.
SUMMARY Or SITE CHARACTERISTICS
Contaminant Characteristics
Based on sampling and analyses conducted during the RI/FS, there
are four major contaminants at the G.M. Site - PCBs, polyaromatic
hydrocarbons (PAHs), phenols and volatile organic compounds
(VOCs). At the G.M. Site, PAHs, phenols, and VOCs were found at
much lower concentrations and in fewer samples than PCBs and,
consequently, pose lower risks than PCBs. Therefore, the primary
contaminant of concern at the Site is PCBs. Any method of
treatment or containment selected for the Site will also be
effective for PAHs, phenols, and VOCs. For these reasons, PCBs
have, in most cases, driven the remedy selection at this Site,
although EPA intends to address all contaminants during the
cleanup of the Site.
PCBs tend to bioaccumulate in human and animal fatty tissue and
are classified by EPA as probable human carcinogens. The major
target organs of PCB exposure are the liver and skin.
Occupational exposure to relatively high concentrations of PCBs
have resulted in changes in blood levels of liver enzymes and
skin effects such as chloracne. PCBs have produced liver tumors
in laboratory studies of rats. In addition, PCBs cause adverse
reproductive effects in laboratory animals at low levels and may
cause similar results in humans.
Affected Media
This section summarizes the quantities and types of contamination
found in the East Disposal Area and the Industrial Landfill and
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associated groundwater, the areas of the Site under consideration
in this ROD. Table 1 summarizes the types of contaminants and
their concentrations in several areas of the Site.
East Disposal Area
It is estimated that the East Disposal Area consists of
approximately 174,000 cubic yards of soil, debris and sludge with
PCB concentrations greater than 10 ppm. The highest PCB
concentration detected in the East Disposal Area is 41,000 ppm.
Phenols were detected in East Disposal Area samples with a
maximum phenol concentration of 11,000 ppm.
The estimated volumes of contaminated soil and sludge associated
with various PCB contamination levels for the East Disposal Area
are given below. The volumes in the second column represent the
estimated total -volume of material with concentrations above the
corresponding contamination level. These volumes and additional
volume estimates will be verified during the remedial design and
remedial action phases of the project.
PCB Contamination Level
10,000 ppm
2000 ppm
1000 ppm
500 ppm
50 ppm
25 ppm
10 ppm
TOTAL
Total Volume of Soil,
Sludge, and Debris
6,000 yd3
30,000 yd3
48,000 yd3
59,000 yd3
100,000 yd3
150,000 yd3
174.000 yd3
174,000 yd3
The pattern of PCB contamination in the East Disposal Area is
generally consistent with the history of past disposal practices
in that area. PCB contaminated sludges were originally pumped to
a bermed disposal area east of the plant to provide a sludge
settling basin. Most of the PCBs observed in the East Disposal
Area are found within the original sludge disposal area. This
basin was approximately 3 acres in size. When the berm was
breached in the summer of 1975, water and sludge flowed east
toward the Reservation. The data also identify a tongue of PCB
contaminated soil to the east of the original disposal area which
is the remains of the 1975 breach (see Figure 4). Two smaller,
less contaminated areas of PCB contamination were also identified
to the southwest of the original disposal area and south of the
Industrial Landfill.
The East Disposal Area was filled, in part, with construction
debris and soil in 1977. As a result, debris and concrete were
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noted in several East Disposal Area borings. Due to the
presence of the debris and boulders, excavation in some locations
in the East Disposal Area nay be technically complex.
Groundwater beneath the East Disposal Area contains low levels of
PCBs and phenols (see Table 1). The highest level of PCBs
detected in East Disposal Area groundwater is 1.7 parts per
billion (ppb). The highest level of phenols detected in East
Disposal Area groundwater is 60 ppb. These levels were detected
in wells screened in the lower glaciofluvial layer.
Industrial Landfill
The Industrial Landfill contains approximately 424,000 cubic
yards of soil, debris and sludge with PCB concentrations greater
than 10 ppm. Of this amount, there are approximately 50,000 -
100,000 cubic yards of soil with PCB concentrations above 500 ppm
buried in the Industrial Landfill. The highest PCB concentration
detected in the Industrial Landfill is 4,300 ppm. Phenols were
detected in three Industrial Landfill samples with a maximum
phenol concentration of 51 ppm. The Landfill rises approximately
35 feet above natural ground level.
Unlike the East Disposal Area, no localized areas of high level
PCB contamination (known as "PCB hotspots") were found in the
Industrial Landfill. Historically, the Industrial Landfill
received foundry sand, soil, construction debris, and solid
waste, in addition to PCB contaminated sludge, lubricants,
caustic waste, degreasers, and aluminum dross. Based on
historical information, it is believed that the volume of sludge
disposed in the Landfill was much less than that disposed in the
East Disposal Area.
The Industrial Landfill presently has an interim vegetated clay
cover which was placed on the Landfill in 1988. The majority of
the highly PCB contaminated material in the Landfill is covered
by several feet (between 5 and 15 feet) of material with lower
PCB concentrations.
The highest level of PCBs detected in groundwater beneath the
Industrial Landfill is 1.3 ppm. VOCs were also detected in some
Industrial Landfill groundwater samples with maximum vinyl
chloride, dichloroethylene, and trichloroethylene concentrations
of 50 ppb, 686 ppb and 50 ppb, respectively.
Potential Routes of Migration and Exposure
Contamination may migrate from uncovered areas, including the
East Disposal Area, into groundwater, surface water, and off the
G.M. facility. Contaminated soil may be ingested or may come
into dermal contact with workers or trespassers. The
volatilization of PCBs from the East Disposal Area is also a
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potential route of exposure. PCBs carried in surface water-
runoff may migrate to the Reservation. In addition, PCBs in soil
may be ingested by wildlife and begin to bioaccumulate within the
food chain, eventually accumulating within human fatty tissue.
SUMMARY OF SITE RISKS
EPA conducted a baseline risk assessment to evaluate the
potential risks to human health and the environment associated
with the G.M. Site in its current state. The qualitative and
quantitative information on risks to human health presented in
this section is based on EPA's "Baseline Risk Assessment for the
G.M./Massena Site" which, in turn, was based on the "Superfund
Public Health Evaluation Manual" (U.S. EPA, 1986). Qualitative
information on environmental risks is based on a recent draft
study of contaminants in wildlife performed by NYSDEC and the St.
Regis Mohawk Tribe and preliminary natural resource surveys
performed by NYSDEC, the St. Regis Mohawk Tribe, the U.S.
Department of the Interior, and the National Oceanic and
Atmospheric Administration.
Contaminant Identification and Exposure Assessment
Because PCBs are the primary contaminant of concern at the G.M.
Site, EPA's baseline risk assessment for the Site reviewed the
human health risks resulting from exposure to PCBs in East
Disposal Area and Industrial Landfill soils and associated
groundwater. The potential routes of human exposure to East
Disposal Area and Industrial Landfill contamination are the
ingestion of wildlife containing PCBs, infant ingestion of breast
milk which contains PCBs due to bioaccumulation, ingestion of
contaminated drinking water (potential future exposure route),
ingestion of and dermal contact with PCB contaminated soil, and
inhalation of dust carrying PCBs. Inhalation of dust was not
quantitatively evaluated in the Baseline Risk Assessment and will
not be discussed further here. Exposed populations include
residents of the St. Regis Mohawk Indian Reservation, Canadians
who are downriver of the Site, and G.M. workers.
A major assumption of the EPA risk assessment was that the G.M.
Site would not be developed for residential uses in the future.
In addition, because the St. Regis Mohawk Indian Reservation
contains the closest residential population to the Site, the St.
Regis Mohawk Tribe was considered the exposed population for the
purposes of determining the exposure assumptions used in the risk
assessment. Table 2 presents the exposure parameters used by EPA
in its baseline risk assessment. Most probable and worst case
exposures were evaluated.
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Toxicity Assessment
Under current EPA guidelines, the likelihood of carcinogenic
(cancer causing) and non-carcinogenic effects due to exposure to
site chemicals are considered separately.
Potential carcinogenic risks were evaluated using the cancer
slope factors developed by EPA for the contaminants of concern.
Cancer slope factors (SFs) have been developed by EPA's
Carcinogenic Risk Assessment Verification Endeavor for estimating
excess lifetime cancer risks associated with exposure to
potentially carcinogenic chemicals. SFs, which are expressed in
units of (mg/kg-day)'1, are multiplied by the estimated intake of
a potential carcinogen, in mg/kg-day, to generate an upper-bound
estimate of the excess lifetime cancer risk associated with
exposure to the compound at that intake level. The term "upper
bound" reflects the conservative estimate of the risks calculated
from the SF. Use of this approach makes the underestimation of
the risk highly unlikely. The SF value for PCBs is 7.7 (mg/kg-
day)'1. This value, based on animal tests of several PCB
mixtures, was calculated for the oral route of exposure but was
used in EPA's risk assessment for all routes due to the absence
of dermal and inhalation SFs for PCBs. EPA's current policy is
to use one SF value for all commercial PCB mixtures.
Non-carcinogenic risks were assessed using a hazard index
approach, based on a comparison of expected contaminant intakes
and safe levels of intake (Reference Doses). Reference doses
(RfDs) have been developed by EPA for indicating the potential
for adverse health effects. RfDs, which are expressed in units
of mg/kg-day, are estimates of daily exposure levels for humans
which are thought to be safe over a lifetime (including sensitive
individuals). The current RfD for PCBs is 0.0001 mg/kg-day. EPA
is in the process of reviewing the RfD for PCBs.
Baseline Human Health Risk Characterization
Excess lifetime cancer risks for the Site were determined by
multiplying the intake levels (given in Table 2) with the SF for
PCBs, 7.7 (mg/kg-day)'1. These risks are probabilities that are
expressed in scientific notation (e.g... 1 x 10"6). An excess
lifetime cancer risk of 1 x lO"6 indicates that as a plausible
upper bound, an individual has not greater than an additional one
in one million chance of developing cancer as a result of Site-
related exposure to PCBs over a 70-year period under the specific
exposure conditions presented at the Site. EPA considers risks
in the range 10"* to 10"6 to be generally acceptable.
For known or suspected carcinogens, EPA considers excess upper
bound individual lifetime cancer risks of between 10"* to 10"* to
be acceptable. This level indicates that an individual has not
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greater than a one in ten thousand to one in a million chance of
developing cancer as a result of site-related exposure to a
carcinogen over a 70-year period under specific exposure
conditions at the Site.
Table 3 presents a summary of the total carcinogenic risks and
the carcinogenic risks posed by each exposure pathway under
consideration in this ROD for residents of the St. Regis Mohawk
Tribe. It can be seen from Table 3 that the most probable and
worst case risks associated with ingestion of wildlife are 1.7 x
10'2 and 2.4 x 10'2, respectively. These risks are considered
unacceptable by EPA and are much greater than the risks
associated with the other exposure pathways evaluated. The
cumulative most probable upper bound cancer risk at the G.M. Site
(excluding the risks from ingestion of fish) is 1.8 x 10'2.
Hence, the risks for carcinogens at the Site are considered
unacceptable by EPA. The estimated total cancer risks are
primarily due to ingestion of wildlife which has bioaccumulated
PCBs.
Estimated intakes of chemicals from environmental media (e.g..
the amount of a chemical ingested from contaminated drinking
water) are compared with the RfD to derive the hazard quotient
for the contaminant in the particular medium. The pathway hazard
index (HI) is obtained by adding the hazard quotients for all
compounds for a particular pathway that impact a particular
receptor population. The cumulative HI is obtained by adding the
pathway His for all compounds across all media that impact a
particular receptor population. A HI greater than 1 indicates
that the potential exists for non-carcinogenic health effects to
occur as a result of site-related exposures. The HI provides a
useful reference point for gauging the potential significance of
multi-contaminant exposures within a single medium or across
media.
Table 4 presents a summary of the pathway His and the cumulative
HI for the G.M. Site. The cumulative HI at the G.M. Site
(excluding fish ingestion) is 22.8 for the most probable case
scenario and 36 for the worst case scenario. Hence, the HI at
the Site exceeds the recommended maximum value of 1. The most
probable and worst case His for wildlife ingestion are 21.7 and
31.1, respectively. As with carcinogenic effects, the non-
carcinogenic effects associated with ingestion of wildlife are
considered unacceptable by EPA and are much greater than the
effects associated with the other pathways evaluated.
Environmental Risks
EPA, NYSDEC, the St. Regis Mohawk Tribe, and the natural resource
trustees are continuing to assess the risks posed to the
environment by the Site. NYSDEC and the St. Regis Mohawk Tribe,
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in a recent study of PCB concentrations in area wildlife,
observed elevated PCB levels in several specimens/ including
frogs, snapping turtles, geese, and ducks.
Based on the currently available information, there are presently
unquantified risks to the environment from the Site. PCBs have
been detected in area wildlife and in wetlands which provide
habitat for water birds and other wildlife.
New York State, the St. Regis Mohawk Tribe, the U.S. Department
of Commerce, and the U.S Department of the Interior are each
natural resource trustees pursuant to the Comprehensive
Environmental Response, Compensation and Liability Act of 1980
(CERCLA) with trustee interests in the river system and environs
as a result of the impacts noted in this ROD as well as other
impacts to natural resources which have been observed. The
trustees are currently in the preliminary stages of the natural
resource damage'assessment process.
Uncertainties
The procedures and inputs used to assess risks in this
evaluation, as in all such assessments, are subject to a wide
variety of uncertainties. In general, the main sources of
uncertainty include:
environmental chemistry sampling and analysis;
environmental parameter measurement;
fate and transport modeling;
exposure parameter estimation; and,
toxicological data.
Uncertainty in environmental sampling arises in part from the
potentially uneven distribution of chemicals in the media
sampled. Consequently, there is significant uncertainty as to
the actual levels present. Environmental chemistry analysis
error can stem from several sources including the errors inherent
in the analytical methods and characteristics of the matrix being
sampled.
Uncertainties in the exposure assessment are related to estimates
of how often an individual would actually come in contact with
the chemicals of concern, the period of time over which such
exposure would occur, and in the models used to estimate the
.concentrations of the chemicals of concern at the point of
exposure.
Uncertainties in toxicological data occur in extrapolating both
from animals to humans and from high to low doses of exposure, as
well as from the difficulties in assessing the toxicity of a
mixture of chemicals. One of the greatest sources of uncertainty
in the G.M. Site Baseline Risk Assessment was the use of the oral
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SF for PCBs due to the absence of dermal and inhalation SFs for
PCBs. Uncertainties are addressed by making conservative
assumptions concerning risk and exposure parameters throughout
the assessment. As a result, the Baseline Risk Assessment
provides upper bound estimates of the risks to populations near
the Site, and is unlikely to underestimate actual risks related
to the Site.
More specific information concerning public health risks,
including a quantitative evaluation of the degree of risk
associated with various exposure pathways, is presented in the
Baseline Risk Assessment Report.
Risk Summary
Actual or threatened releases of hazardous substances at or from
the Site, if not addressed by implementing the response action
selected in this ROD, may present an imminent and substantial
endangerment to public health, welfare, or the environment.
DESCRIPTION OF ALTERNATIVES
Remedial alternatives are presented in this section for the East
Disposal Area and the Industrial Landfill at the Site. Because
several of the alternatives include treatment or containment of
PCBs, discussions of PCB treatment technologies and containment
technologies are presented as an introduction. This is followed
by a discussion of cleanup levels selected by EPA for these areas
of the Site.
Treatment Technologies
Six methods of treatment for Site soil, sludges and sediments
were examined: biological destruction, chemical destruction,
chemical extraction, thermal destruction (incineration), thermal
extraction and solidification. Each of these treatment
technologies has been tested at other hazardous waste sites.
Although some have been found to be effective in treating PCBs
and other contaminants, each technology, with the exception of
thermal destruction, would require a pilot or field testing
program before full-scale use at this Site. Thermal destruction
would require trial incinerator burns to establish operating
conditions.
It should be noted, however, that testing of innovative treatment
technologies was included as part of the first operable unit ROD
for the G.M. Site. EPA intends that the results of the first
operable unit treatability testing program will satisfy most, if
not all, of the treatability testing data requirements for the
entire G.M. Site such that additional treatability studies will
not be required during design of the second operable unit remedy.
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Biological Treatment
Biological destruction of PCBs using naturally occurring or
scientifically engineered bacteria was determined to be a
potentially feasible alternative for the remediation of
contaminated soils, sediments, and sludges at the Site. At the
G.M. Site, biological treatment would involve processing
excavated soils and sludges or dredged sediment in slurry form in
above-ground batch reactors. Preprocessing would be necessary to
remove bulky items. Bacteria and nutrients would be added to the
tanks and the tanks would be mechanically aerated and agitated.
The bacteria would degrade PCBs to nonhazardous products.
Preliminary bench-scale tests of Site soil by G.M. have
demonstrated up to 82% reduction of PCBs, from 291 ppm to 52 ppm,
after several months of anaerobic and aerobic biological
treatment. Such a reduction, while promising, would not result
in levels which are sufficiently low for cleanup or destruction.
G.M. is continuing biological treatment tests in an effort to
achieve greater reductions in PCB concentrations.
Because biological treatment would be performed on material in
slurry form, a large quantity of water would be used during
treatment and produced during subsequent dewatering operations.
This water would be discharged to the St. Lawrence River in
compliance -with SPDES requirements which currently require that
PCB concentrations in the discharge be non-detectable, down to
the method detection level, using EPA Laboratory Method Number
608. Because PCB volatilization is a concern, if necessary, the
reactors would be covered or fitted with emissions control
equipment. Major applicable or relevant and appropriate
requirements for biological treatment are federal Clean Air Act
(CAA) and New York State air quality standards along with
Resource Conservation and Recovery Act (RCRA) hazardous waste
treatment regulations and TSCA disposal requirements.
Biological treatment is an innovative technology. Approximately
six months to one year would be required for preliminary testing
and technology development. In addition, biological treatment
may not be effective in reducing PCB concentrations in those
materials with initially high PCB concentrations to levels
required for cleanup or disposal.
Chemical Destruction
This technology employs a chemical dechlorination process to
treat contaminated soils, sludges, and sediments. For example,
in the proprietary KPEG process, PCB contaminated materials are
reacted with several reagents, including potassium hydroxide and
polyethylene glycol or similar chemicals to remove the chlorine
atoms from PCBs. If successful, this process converts PCBs to a
glycol-substituted biphenyl compound which is less toxic than
PCBs. Full-scale process equipment is currently available.
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For this Site, chemical dechlorination would be performed in a
batch mixed reactor at approximately 300°F with an excess of
reagent. The vendor of this process.believes that, based on work
at other sites, residual PCB concentrations as low as 2 ppm are
achievable. Site-specific testing of chemical dechlorination
would be required in order to determine the effectiveness of the
technology with respect to G.M. Site material.
Preprocessing is necessary to remove bulky items. Water, used to
wash treated solids, would be discharged to the St. Lawrence
River in compliance with SPDES requirements. Because PCB
volatilization is a concern, if necessary, the reactors would be
covered or fitted with emissions control equipment. Major
applicable or relevant and appropriate requirements for chemical
destruction are federal CAA and New York State air quality
standards along.with RCRA hazardous waste treatment regulations
and TSCA disposal requirements.
Chemical Extraction
At the G.M. Site, the evaluation of chemical extraction was based
on the proprietary B.E.S.T. (Basic Extractive Sludge Treatment)
process. Other similar processes are also available. This
technology involves concentrating PCBs found in large volumes of
solids and sludges into smaller volumes of an oily extract
through the use of triethylamine, a solvent. The PCB rich
extract must then be disposed. Preprocessing is necessary to
remove bulky items. Full-scale process equipment is currently
available.
The vendor reports that, based on information from other sites,
solids residual concentrations less than 0.1 ppm PCB are
possible. Tests on sludge (not from the G.M. Site) showed PCB
concentrations of 130 ppm in treated sludge with an initial PCB
concentration of 5800 ppm. Site-specific testing of chemical
extraction would be required in order to determine the
effectiveness of the technology with respect to G.M. Site
material.
Process water would be treated and discharged to the St. Lawrence
River in compliance with SPDES requirements. Major applicable or
relevant and appropriate requirements for chemical extraction are
TSCA disposal requirements, federal and State air quality
standards, and RCRA hazardous waste treatment regulations. The
PCB extract would be treated and disposed on-site or transported
off-site for disposal, if necessary.
Thermal Destruction
Thermal destruction technology involves the incineration of solid
material. After material processing, sorting and, if necessary,
dewatering, solids and sludges are fed to the incinerator. A
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rotary kiln incinerator was used to develop cost estimates,
however, the particular type of incinerator to be used would be
determined during design. Incinerators are commercially
available and have achieved the 99.9999% destruction removal
efficiency required by TSCA.
Scrubber water would be treated and discharged to the St.
Lawrence River in compliance with SPDES requirements. Major
applicable or relevant and appropriate requirements for thermal
destruction are TSCA and RCRA incineration and disposal
requirements, and federal and State air quality standards.
Incinerator ash would be tested and, if found to be non-
hazardous, backfilled on-site.
Thermal Extraction
Thermal extraction involves the volatilization of organics from a
solid or sludge waste stream under lower temperature conditions
than those of incineration. The organic contaminants are not
destroyed during this extraction process; rather another
treatment process would be necessary to permanently destroy the
condensed liquid PCB extract. Full-scale experimental and pilot-
scale thermal extraction units are available. Vendor pilot
studies have reduced PCBs from an initial concentration of 18,000
ppm to less than 0.1 ppm.
Scrubber water would be treated and discharged to the St.
Lawrence River in compliance with SPDES requirements. Major
applicable or relevant and appropriate requirements for thermal
extraction are TSCA disposal requirements, RCRA treatment
requirements, and federal and State air quality requirements.
The PCB extract would be treated and disposed on-site or
transported off-site for disposal, if necessary.
Solidification
Solidification of the excavated material involves the physical
encapsulation, chemical reaction, or both, of the contaminated
material. A commercially available additive is mixed with the
waste to create a slurry which is allowed to harden to a solid
material. This solid material can then be disposed.
Solidification is used to limit the leachability, or "leaking",
of the PCBs into the environment. There is no data on
destruction of PCBs during the solidification process.
Because PCB volatilization during solidification is a concern, if
necessary, emissions control equipment would be required. Major
applicable or relevant and appropriate requirements for
solidification are CAA and New York State air quality standards
along with TSCA and RCRA disposal requirements. Solidified
material would require cover and long-term maintenance since PCBs
would not be permanently destroyed.
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The treatment options discussed above can be used separately or
in combination with each other to treat soils, sludges and
sediments at the Site. For example, because biological treatment
may not be effective on highly concentrated wastes, in the first
operable unit ROD, EPA evaluated a mixed treatment alternative
which involves incineration of material contaminated with PCBs
over 500 ppm and biological treatment of material with PCB
concentrations below 500 ppm.
Solids Containment Technologies
EPA has evaluated two types of in-place containment systems for
PCB contaminated solids. These containment systems consist of
two types of covers or "caps" which blanket contaminated
material: a soil cover and a synthetic composite cover.
Soil Cover
The soil cover system evaluated consists of containing
contaminated materials in place with a cover consisting of one
layer of a synthetic geotextile material, two feet of clay and
six inches of topsoil. The surface of the soil cover would then
be vegetated. Prior to capping, the materials would be
consolidated, compacted and graded, as necessary.
The cover would be designed to meet applicable New York State
solid waste disposal requirements, CAA and New York State air
quality standards, and relevant and appropriate New York State
and RCRA hazardous waste disposal and closure requirements. It
would not meet TSCA disposal requirements since TSCA requires a
composite cover, as described below.
Composite Cover
The composite cover system evaluated consists of containing
contaminated materials in place with a cap composed of the
following materials: three feet of clay, one layer of flexible
membrane liner, one layer of drainage material, one layer of
geotextile, eighteen inches of rooting zone soil and six inches
of topsoil. The surface of the composite cover would also be
vegetated. Prior to capping, the materials would be
consolidated, compacted and graded, as necessary.
The cover would be designed to meet applicable TSCA disposal
requirements, applicable New York State waste disposal
requirements, CAA and New York State air quality standards, and
relevant and appropriate New York State and RCRA hazardous waste
disposal and closure requirements.
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Groundwater Containment Technology
EPA evaluated a slurry wall system to redirect and contain
groundwater flow in the East Disposal Area and the Industrial
Landfill. At the G.M. Site, the slurry wall would be installed
by excavating a trench approximately forty feet deep around the
area to be contained. (A depth of approximately forty feet is
required to eliminate groundwater flow through the shallow,
permeable lower glaciofluvial deposit which lies beneath the
Industrial Landfill and the East Disposal Area (see Figure 3)).
The trench would then be backfilled with a bentonite/water/soil
slurry which would hold the trench open and create an impermeable
barrier layer on the trench walls, which would block the flow of
groundwater into and out of the contained area. Figure 5 depicts
the approximate location of the slurry wall. By constructing the
slurry wall so that it blocks the flow of groundwater into and
out of the East.Disposal Area and the Industrial Landfill and by
extracting groundwater inside the slurry wall, the amount of
contaminated groundwater flowing from the Site to the St.
Lawrence River and Turtle Creek would be reduced.
Pumping wells would be installed inside the slurry wall to
control the groundwater level inside the slurry wall and to help
prevent groundwater from leaving the contained area. Monitoring
wells would be placed inside and outside the slurry wall's
perimeter to monitor the effectiveness of the slurry wall. The
water extracted by the pumping wells inside the slurry wall would
be treated in a wastewater treatment system (most likely with a
combination of air stripping and carbon adsorption) to remove
VOCs and PCBs. Treated water would be discharged to the St.
Lawrence River in compliance with SPDES.requirements.
Additional data collection would be required prior to
construction of a slurry wall system at the G.M. Site (see page
40). Such data would confirm that the volume and flow rate of
contaminated groundwater to be collected inside the slurry wall
will be sufficient to make the slurry wall cost effective. EPA
would consider alternatives to the slurry wall system if data and
analysis demonstrate that the present worth costs of the slurry
wall system are significantly higher than those of any proposed
alternative. Any proposed alternative must, at a minimum, meet
the objectives of the groundwater extraction system selected as
part of the first operable unit ROD and be as protective as the
slurry wall system.
The major applicable or relevant and appropriate requirements
associated with the slurry wall and the pumping wells are
relevant and appropriate Safe Drinking Water Act Maximum
Contaminant Levels (MCLs), applicable New York State groundwater
quality standards, and RCRA treatment and land disposal
requirements which are applicable if the groundwater treatment
residuals are RCRA hazardous wastes.
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Cleanup/ Treatment, and Treatment Residual Levels for tbe Site
EPA has chosen cleanup levels, treatment levels, and treatment
residual levels for PCBs and other chemicals in the East Disposal
Area and the Industrial Landfill at this Site. Cleanup levels
are those levels above which some action (i.e... treatment or
containment) must be implemented. Treatment levels are those
levels above which treatment must be performed to reduce
contaminant mobility, toxicity, or volume. Residual levels are
those levels which must be met in the residual of any treatment
process which is employed to remediate the Site. Second operable
unit Site cleanup levels, treatment levels, and residual levels
for all contaminants of concern are specified in Table 5. If
necessary to ensure protection of human health and the
environment, EPA may, based on the results of additional site
characterization during remedial design, develop cleanup,
treatment, or residual levels for other contaminants of concern.
EPA has selected a soil/sludge PCS cleanup level of 10 ppm on the
G.M. facility. All soil/sludge in the East Disposal Area and the
Industrial Landfill with PCB concentrations above 10 ppm must be
addressed during remediation through either treatment or
containment. The 10 ppm PCB cleanup level is based, in part, on
EPA's risk assessment for the alternatives considered for the
Site which indicates that 10 ppm is protective of human health,
particularly the Mohawk population, and on EPA's August 1990 PCB
guidance which recommends soil PCB cleanup levels between 10 ppm
and 25 ppm in industrial areas. EPA has selected a cleanup level
on the lower end of this range because access to remediated areas
will be unlimited to G.M. personnel as well as to wildlife,
because contaminants in on-site soils impact groundwater and
surface water quality, and because surface contaminants can be
transported off-site in Site runoff or as windborne dust.
EPA estimates that there are 174,000 cubic yards of sludges and
soils in the East Disposal Area contaminated with PCBs above 10
ppm which are being addressed in this ROD. In addition, EPA
anticipates that the estimated 424,000 cubic yards of material
currently within the boundaries of the Industrial Landfill are
contaminated with PCBs at concentrations above 10 ppm. Thus, EPA
anticipates that the entire volume of material currently in the
Industrial Landfill will be addressed in this ROD.
In general, EPA expects to use a combination of methods,
including treatment and containment to address wastes at
Superfund sites. Specifically, EPA expects to use treatment to
address the "principal threats" posed by a site. Principal
threats generally include liquids, areas with high concentrations
of toxic compounds, and highly mobile materials. Further, EPA
expects to use engineering controls, such as containment systems,
to address waste that poses a relatively low long-term threat.
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At the G.M. Site in the East Disposal Area and the Industrial
Landfill, principal threats include sludge with PCB
concentrations above 10 ppm, visibly oily soil with PCB
concentrations above 10 ppm, and non-oily soil with PCB
concentrations above 500 ppm. Sludge and visibly oily soil with
PCB concentrations above 10 ppm contain significant amounts of
oil and/or solvents which may mobilize PCBs and are therefore
considered principal threats by EPA. Soil in the East Disposal
Area and the Industrial Landfill with PCB concentrations above
500 ppm is deemed to be a principal threat in accordance with
EPA's PCB Guidance which states that principal threats at
industrial facilities generally include soil with PCB
concentrations above 500 ppm.
Based on the available data, EPA has concluded that principal
threat material in the East Disposal Area is generally segregable
from material in that area which does not constitute a principal
threat. Therefore, for the East Disposal Area, EPA has evaluated
an alternative which includes treatment of principal threat
material fi.e.. sludge with PCB concentrations above 10 ppm,
visibly oily soil with PCB concentrations above 10 ppm, and soil
with PCB concentrations above 500 ppm) and containment of
material which does not constitute a principal threat. EPA has
also evaluated an alternative for the East Disposal Area with a
soil/sludge treatment level of 10 ppm PCBs. By evaluating two
alternatives with different treatment levels, EPA can compare
alternatives associated with full and partial treatment of the
East Disposal Area.
The available data indicate that the majority of the material in
the Industrial Landfill is debris, foundry sand, and soil.
Further, soil with PCB concentrations above 500 ppm in the
Industrial Landfill is generally buried under much less
contaminated material and is therefore inaccessible. Therefore,
in the Industrial Landfill, EPA does not believe that segregation
of principal threat material from material which does not
constitute a principal threat is technically practicable. For
this reason, EPA has evaluated only one soil treatment level in
the Industrial Landfill, 10 ppm. By evaluating a soil treatment
level of 10 ppm, EPA is comparing treatment of the entire
Industrial Landfill to containment of the entire Industrial
Landfill.
In general, EPA has selected a 10 ppm PCB treatment residual
level for soil/sludge on the G.M. facility and a 2 ppm PCB
treatment residual level for sludge with initial PCB
concentrations above 500 ppm on the G.M. facility. These levels
are consistent with the PCB cleanup level for the G.M. facility.
This is appropriate because treated soil would be deposited on
the G.M. facility after treatment. However, EPA may, in
consultation with the State and the Tribe, adjust the treatment
residual level upward based on the results of treatability
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testing in order to minimize the need to use incineration to
treat G.M. Site material. For example, if the best innovative
treatment technology results in a treatment residual which
contains 20 ppm PCBs, EPA may determine that a treatment residual
of 20 ppm PCBs is preferable to the use of incineration to
achieve a treatment residual of 10 ppm or less PCBs.
TSCA regulations require that sludges with PCB concentrations
above 500 ppm be incinerated in a TSCA compliant incinerator or
be treated by a method equivalent to incineration. Therefore, in
compliance with TSCA, the treatment residual level for any
sludges with initial PCB concentrations above 500 ppm is 2 ppm
rather than 10 ppm.
Any groundwater extracted from the Site would be treated to
comply with SPDES requirements before it would be discharged to
the St. Lawrence River. The treatment levels for groundwater are
given in Table 5. These levels are based on New York State SPDES
requirements which regulate the levels of contaminants which may
be discharged to the waters of New York State. This is
appropriate since groundwater will be discharged to the St.
Lawrence River following treatment.
East Disposal Area
The remedial alternatives evaluated for the East Disposal Area
include: no action, capping and groundwater containment,
excavation and on-site treatment of all contaminated materials
(using one of the treatment technologies outlined above), mixed
treatment/containment of contaminated materials, and excavation
of contaminated material with on-site disposal.
Alternative El: No Action for the East Disposal Area
Capital Cost: $ 60,000
Operation and Maintenance (O&M) Costs: $ 127,000/year
Present Worth Cost: $ 2 million
Time to Implement: 1 year
CERCLA requires that the "no action" alternative be considered at
Superfund sites. This alternative consists of allowing the
174,000 cubic yards of contaminated soils, sludges and solids in
the East Disposal Area to remain in their present state. No
additional waste materials would be placed in the East Disposal
Area. While periodic monitoring would be performed, no actions
would be taken to remove or contain contaminated material.
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Alternative E2; Capping/Groundwater Containment of the East
Disposal Area
Capital Cost: $ 2 - 4 million (without
slurry wall)
$ 6 - 8 million (with
slurry wall)
Operation and Maintenance Costs:
Present Worth Cost:
Time to Implement:
$ 435,000/year (without
slurry wall)
$ 200,000/year
slurry wall)
$ 9 - 11 million
slurry wall)
$ 9 - 11 million (with
slurry wall)
4 years
(with
(without
This alternative consists of consolidation, compaction, and
grading of 174,000 cubic yards of East Disposal Area soils with
PCB concentrations above 10 ppm to provide positive surface
drainage (to ensure that surface water drains from the East
Disposal Area) and capping with either a soil cover or a
composite cover. In addition, if warranted based on the results
of additional groundwater testing, the East Disposal Area and the
Industrial Landfill would be surrounded with a slurry wall. A
surface water runoff collection system would also be installed
around the East Disposal Area and- the Industrial Landfill.
Revegetation of the cover, regular cover inspection, and cover
maintenance would also be required. Dust suppression measures
would be implemented during cover construction.
EPA would consider alternatives to the slurry wall system if data
and analysis demonstrate that the present worth costs of the
slurry wall system are significantly higher than those of any
proposed alternative. Any proposed alternative must, at a
minimum, meet the objectives of the groundwater extraction system
selected as part of the first operable unit ROD and be as
protective as the slurry wall system.
Pumping wells would be installed inside the slurry wall. The
water from the pumping wells and surface water runoff would be
treated in a wastewater treatment system, as necessary, with a
combination of air stripping to remove the volatile organic
compounds and carbon adsorption to remove PCBs. Other
groundwater treatment technologies could be used if further
groundwater treatment is required. Treated water would be
discharged to the St. Lawrence River in compliance with SPDES
requirements. Deed restrictions would be placed on the G.M.
property to discourage its use as a residential area in the
future. Revegetation of the area and groundwater monitoring
would complete the remediation. A review would be conducted
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within at least five years after commencement of remedial action
and every five years thereafter to ensure that the remedy
continues to provide adequate protection of human health and the
environment.
Major ARARs related to the solids containment component of this
alternative are applicable TSCA disposal requirements, applicable
New York State solid waste disposal requirements, and relevant
and appropriate RCRA and New York State hazardous waste disposal
and closure requirements. Major ARARs associated with the slurry
wall and pumping wells are relevant and appropriate Safe Drinking
Water Act Maximum Contaminant Levels (MCLs), applicable New York
State groundwater quality standards, and RCRA treatment and land
disposal requirements which are applicable if the groundwater
treatment residuals are RCRA hazardous wastes.
The present worth costs of this alternative (including the costs
for a slurry wall around both the East Disposal Area and the
Industrial Landfill) are $ 9 million for a soil cover and $ 11
million for a composite cover. The present worth cost of this
alternative excluding the costs of the slurry wall are $ 9
million for a soil cover and $ 11 million for a composite cover.
These costs estimates are based, in part, on assumptions about
the affect of the slurry wall on groundwater volumes given in
Appendix 3. Additional data collection will be required to
verify these assumptions. This alternative would require
approximately four years to construct following completion of
remedial design which will take approximately one year.
Alternative E3; Excavation and On-Site Treatment of All
Contaminated Materials in the East Disposal Area
Capital Cost:
Operation and Maintenance Costs:
Present Worth Cost:
Time to Implement:
$ 33 - 86 million
$ 102,000 - 165,000/year
$ 34 - 87 million
1-5 years
This alternative consists of excavating 174,000 cubic yards of
contaminated soil, debris and sludge in the East Disposal Area
with concentrations above 10 ppm PCBs and treating them with one
or a combination of the six treatment methods discussed above.
In general, the goal of the treatment would be to reduce PCB
concentrations below 10 ppm.
Solids would be preprocessed to reduce particle size. Large
contaminated objects which could not be treated would be disposed
in a facility which meets all TSCA requirements, as necessary.
Treated material which is not considered under RCRA or New York
State regulations would be disposed in areas on G.M. property and
covered with a vegetated soil cap which complies with New York
State and TSCA chemical waste landfill requirements. Excavated
areas on G.M.'s property would be covered to reduce erosion and
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prevent migration. These areas would be graded to prevent any
surface water runoff from G.M. property and restored to support
vegetation. A long-term groundwater monitoring program would
also be implemented.
Major ARARs associated with this alternative are applicable TSCA
disposal requirements, relevant and appropriate RCRA treatment
regulations, applicable New York State solid waste disposal
requirements, relevant and appropriate RCRA and New York State
hazardous waste disposal and closure requirements, and CAA and
New York State air quality standards.
The range of costs associated with this alternative is given in
Table 6. Present worth costs range from $ 34 million to $ 87
million. Implementation times for this alternative range from
one year (for solidification) to five years,.depending on the
type of treatment employed. .These times do not include time
required to design any required treatment units which will take
up to two years.
Alternative E4; Mixed Treatment/Containment of East Disposal
Area Materials
Capital Cost:
Operation and Maintenance Costs:
Present Worth Cost:
Time to Implement:
$ 20 - 33 million
(without slurry wall)
$24-38 million (with
slurry wall)
$ 250,000 - 600,000/year
(without slurry wall)
$ 15,000 - 367,000/year
(with slurry wall)
$ 24 - 38 million
(without slurry wall)
$24-38 million (with
slurry wall)
1-3 years
This alternative consists of excavation of principal threat
material in the East Disposal Area (i.e.. soils with PCB
concentrations above 500 ppm, all sludge, and all visibly oily
soil) and treatment of this material by one or a combination of
the six treatment methods discussed above. In general, the
principal threat material is found in the vicinity of the
original disposal pit (see Figure 4). An estimated 59,000 cubic
yards of material would be excavated. Due to past disposal
practices, this volume includes overlying soils with PCB
concentrations below 500 ppm which had been placed over material
with PCB concentrations above 500 ppm or which cannot be easily
separated from highly contaminated material.
The excavated material would be treated and then backfilled into
the East Disposal Area to be used as grading material. In
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general, the goal of the treatment would be to reduce PCB
concentrations below 10 ppm. Any bulk debris encountered during
excavation would be stockpiled in a manner which would prevent
migration of wastes from the debris. Depending on the extent and
nature of its contamination, the bulk debris would, if necessary,
be cleaned of gross contamination or shipped off-site for
disposal in a facility licensed to accept PCB contaminated
materials. The remaining untreated soil and debris in the East
Disposal Area with PCB concentrations above 10 ppm (approximately
115,000 cubic yards) and the bulk debris would then be
consolidated, graded to provide surface drainage, compacted,
covered with a composite cover. In addition, if warranted based
on the results of additional groundwater testing, the East
Disposal Area and the Industrial Landfill would be surrounded by
a slurry wall. A surface water runoff collection system would
also be installed around the East Disposal Area and the
Industrial Landfill.
EPA would consider alternatives to the slurry wall system if data
and analysis demonstrate that the present worth costs of the
slurry wall system are significantly higher than those of any
proposed alternative. Any proposed alternative must, at a
minimum, meet the objectives of the groundwater extraction system
selected as part of the first operable unit ROD and be as
protective as the slurry wall system.
Pumping wells would be installed inside the slurry wall. The
water from the pumping wells and surface water runoff would be
treated in a wastewater treatment system, as necessary, with a
combination of air stripping to remove the volatile organic
compounds and carbon adsorption to remove PCBs. Other
groundwater treatment technologies could be used if further
groundwater treatment is required. Treated water would be
discharged to the St. Lawrence River in compliance with SPDES
requirements. Deed restrictions would be placed on the G.M.
property to discourage its use as a residential area in the
future. Revegetation of the East Disposal Area and groundwater
monitoring would complete the remediation. A review would be
conducted within at least five years after commencement of
remedial action and every five years thereafter to ensure that
the remedy continues to provide adequate protection of human
health and the environment.
Major ARARs associated with the solids treatment component of
this alternative are applicable TSCA disposal requirements,
relevant and appropriate RCRA treatment regulations, applicable
New York State solid waste disposal requirements, relevant and
appropriate RCRA and New York State hazardous waste disposal and
closure requirements, and CAA and New York State air quality
standards. Major ARARs associated with the slurry wall and
pumping wells are relevant and appropriate Safe Drinking Water
Act Maximum Contaminant Levels (MCLs), applicable New York State
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groundwater quality standards, and RCRA treatment and land
disposal requirements which are applicable if the groundwater
treatment residuals are RCRA hazardous wastes.
Present worth costs (including the costs for a slurry wall around
both the East Disposal Area and the Industrial Landfill) range
from $ 24 million to $ 38 million. Present worth costs
(excluding the costs of the slurry wall) range from $ 24 million
to $ 38 million. These costs estimates are based, in part, on
assumptions about the affect of the slurry wall on groundwater
volumes given in Appendix 3. Additional data collection will be
required to verify these assumptions. Implementation times for
this alternative range from one year (for solidification) to
three years, depending on the type of treatment employed. These
times do not include time required to design any required
treatment units which will take up to two years.
Alternative E5: Excavation and On-Site Disposal of Solids in the
East Disposal Area
Capital Cost: $ 24 million
Operation and Maintenance Costs: $ 192,000/year
Present Worth Cost: $ 27 million
Time- to Implement: 3 years
This alternative consists of excavation of 174,000 cubic yards of
contaminated soils, debris and sludges in the East Disposal Area
followed by placement of these materials in an on-site double-
lined landfill located on G.M. property.
A landfill would be constructed on the Site in compliance with
federal and state regulations governing landfill construction.
The landfill would be bermed and designed so that the base of the
landfill was above the groundwater table. Contaminated material
would then be excavated and transported to the on-site landfill
for disposal. Following disposal, the landfill would be covered
and closed according to federal and state regulations. Deed
restrictions would be placed on the G.M. property to discourage
its use as a residential area in the future. A review would be
conducted within at least five years after commencement of
remedial action and every five years thereafter to ensure that
the remedy continues to provide adequate protection of human
health and the environment.
Excavated areas on G.M.'s property would be covered to reduce
erosion and prevent migration. Maintenance of the landfill would
include upkeep of the landfill cover and an access road, leachate
treatment, and semi-annual groundwater monitoring. Treated
leachate would be discharged to the St. Lawrence River in
compliance with SPDES requirements.
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Major ARARs for this alternative are RCRA closure requirements
which are relevant and appropriate for the wastes at the Site,
applicable New York State solid waste disposal requirements,
relevant and appropriate New York State hazardous waste disposal
and closure requirements, and TSCA disposal requirements which
are applicable at this Site. The present worth cost of this
alternative is $ 27 million. Implementation time is
approximately three years following completion of remedial design
which will take approximately one year.
Industrial Landfill
The remedial alternatives evaluated for the Industrial Landfill
include: no action, capping and groundwater containment,
excavation and on-site treatment of all contaminated materials
(using one of the treatment technologies outlined above), and
excavation of contaminated material with on-site disposal. EPA
did not evaluate a mixed treatment/containment remedial
alternative for the Industrial Landfill because EPA believes that
segregation of principal threat material from material which is
not a principal threat in the Industrial Landfill is technically
impracticable.
Alternative LI; No Action for the Industrial Landfill
Capital Cost:
Operation and Maintenance Costs:
Present Worth Cost:
Time to Implement:
$ 60,000
$ 127,000/year
$ 2 million
1 year
This alternative consists of allowing the 424,000 cubic yards of
contaminated material in the Industrial Landfill to remain, in its
present state. The interim cover installed on the Landfill would
remain in place, with no upgrading of the cover. Periodic
monitoring would be performed.
Alternative L2; Capping/Groundwater Containment of the
Industrial Landfill
Capital Cost:
Operation and Maintenance Costs:
Present Worth Cost:
Time to Implement:
$ 2 - 4 million (without
slurry wall)
$ 6 - 8 million (with
slurry wall)
$ 435,000/year (without
slurry wall)
$ 200,000/year (with
slurry wall)
$ 9 - 11 million (without
slurry wall)
$ 9 - 11 million (with
slurry wall)
4 years
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This alternative consists of upgrading the existing interim
Industrial Landfill cover with either a soil cover or a composite
cover. In addition, if warranted based on the results of
additional groundwater testing, the East Disposal Area and the
Industrial Landfill would be surrounded by a slurry wall. A
surface water runoff collection system would also be installed
around the East Disposal Area and the Industrial Landfill. The
existing topsoil which is part of the interim cover on the
Industrial Landfill would be removed and replaced following
capping.
EPA would consider alternatives to the slurry wall system if data
and analysis demonstrate that the present worth costs of the
slurry wall system are significantly higher than those of any
proposed alternative. Any proposed alternative must, at a
minimum, meet the objectives of the groundwater extraction system
selected as part of the first operable unit ROD and be as
protective as the slurry wall system.
The Industrial Landfill would be regraded and the slope would be
adjusted to comply with RCRA requirements. In the case of the
soil cover, an additional foot of compacted clay and six inches
of topsoil would then be added to the Landfill. In the case of
the composite cover, the following materials would be added to
the Industrial Landfill following topsoil removal: one foot of
clay, one layer of flexible membrane liner, one layer drainage
material, one layer geotextile, eighteen inches of rooting zone
soil and six inches of topsoil. Revegetation of the cover,
regular cover inspection, and cover maintenance would also be
required. Dust suppression measures would be implemented during
cover construction.
Pumping wells would be installed inside the slurry wall. The
water from the pumping wells and surface water runoff would be
treated in a wastewater treatment system, as necessary, with a
combination of air stripping to remove the volatile organic
compounds and carbon adsorption to remove PCBs. Other
groundwater treatment technologies could be used if further
groundwater treatment is required. Treated water would be
discharged to the St. Lawrence River in compliance with SPDES
requirements. Deed restrictions would be placed on the G.M.
property to discourage its use as a residential area in the
future. Revegetation of the Industrial Landfill and groundwater
monitoring would complete the remediation. A review would be
conducted within at least five years after commencement of
remedial action and every five years thereafter to ensure that
the remedy continues to provide adequate protection of human
health and the environment.
Major applicable or relevant and appropriate requirements (ARARs)
related to the solids containment component of this alternative
are applicable TSCA disposal requirements, applicable New York
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State solid waste disposal requirements, and relevant and
appropriate RCRA and New York State hazardous waste disposal and
closure requirements. Major ARARs associated with the slurry
wall and pumping wells are relevant and appropriate Safe Drinking
Water Act Maximum Contaminant Levels (MCLs), applicable New York
State groundwater quality standards, and RCRA treatment and land
disposal requirements which are applicable if the groundwater
treatment residuals are RCRA hazardous wastes.
The present worth costs of this alternative (including the costs
for a slurry wall around both the East Disposal Area and the
Industrial Landfill) are $ 9 million for a soil cover and $ 11
million for a composite cover. The present worth costs of this
alternative excluding the costs for the slurry wall are $ 9
million for a soil cover and $ 11 million for a composite cover.
These costs estimates are based, in part, on.assumptions about
the affect of the slurry wall on groundwater volumes given in
Appendix 3. Additional data collection will be required to
verify these assumptions. This alternative would require
approximately four years to complete following completion of
remedial design which will take approximately one year.
Alternative L3; Excavation and On-Site Treatment of All
Contaminated Materials in the Industrial Landfill
Capital Cost:
Operation and Maintenance Costs:
Present Worth Cost:
Time to Implement:
$ 61 - 202 million
$ 102,000 - 165,000/year
$ 61 - 203 million
1-12 years
This alternative consists of excavating the 424,000 cubic yards
of contaminated soils, debris and sludges in the Industrial
Landfill with PCB concentrations above 10 ppm and treating them
with one of the six treatment methods discussed above. In
general, the goal of the treatment would be to reduce PCB
concentrations below 10 ppm.
Solids would be preprocessed to reduce particle size. Large
contaminated objects which could not be treated would be disposed
in a facility which meets -all TSCA requirements, as necessary.
Treated material which is not considered under RCRA or New York
State regulations would be disposed in areas on G.M. property and
covered with a vegetated soil cap which complies with New York
State and TSCA chemical waste landfill requirements. Excavated
areas on G.M. property would be covered to reduce erosion and
prevent migration. These areas would be graded to prevent any
surface water runoff from G.M. property and restored to support
vegetation. A long-term groundwater monitoring program would
also be implemented.
Major ARARs associated with this alternative are applicable TSCA
disposal requirements, relevant and appropriate RCRA treatment
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regulations, applicable New York State solid waste disposal
requirements, relevant and appropriate RCRA and New York State
hazardous waste disposal and closure requirements, and CAA and
New York State air quality standards. The range of costs
associated with this alternative is given in Table 7. Present
worth costs range from $ 61 million to $ 203 million.
Implementation times for this alternative range from one year
(for solidification) to twelve years, depending on the type of
treatment employed following completion of remedial design and
treatment system construction which will take up to two years.
Alternative L4; Excavation and On-Site Disposal of Solids in the
East Disposal Area !
Capital Cost: $ 32 million
Operation and Maintenance Costs: $ |192,000/year
Present Worth Cost: $ |34 million
Time to Implement: 3 years
This alternative consists of excavation of 424,000 cubic yards of
contaminated soil, debris and sludges in the Industrial Landfill
with PCB concentrations above 10 ppm followed by placement of
these materials in an on-site engineered landfill located on
G.M.'s property.
A landfill would be constructed on the Site in compliance with
federal and state regulations governing landfill construction.
The landfill would be bermed and would be designed so that the
base of the landfill was above the groundwater table.
Contaminated material would then be excavated and transported to
the on-site landfill for disposal. Following disposal, the
landfill would be covered and closed according to federal and
state regulations. Deed restrictions would be placed on the G.M.
property to discourage its use as a residential area in the
future. A review would be conducted within at least five years
after commencement of remedial action and every five years
thereafter to ensure that the remedy continues to provide
adequate protection of human health and the environment.
Excavated areas on G.M.'s property would be covered to reduce
erosion and prevent migration. Maintenance of the landfill would
include upkeep of the landfill cover and an access road, leachate
treatment, and semi-annual groundwater monitoring. Treated
leachate would be discharged to the St. Lawrence River in
compliance with SPDES requirements.
Major ARARs for this alternative are RCRA closure requirements
which are relevant and appropriate for the wastes at the Site,
applicable New York State solid waste disposal requirements,
relevant and appropriate New York State hazardous waste disposal
and closure requirements, and TSCA disposal requirements which
are applicable at this Site. The present worth cost of this
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alternative is $ 34 million. Implementation time is
approximately three years following completion of remedial design
which will take approximately one year.
SUMMARY OF COMPARATIVE ANALYSIS OF ALTERNATIVES
In accordance with the National Contingency Plan (NCP), a
detailed analysis of each alternative was performed. The purpose
of the detailed analysis was to objectively assess the
alternatives with respect to nine evaluation criteria that
encompass statutory requirements and include other gauges of the
overall feasibility and acceptability of remedial alternatives.
The analysis was comprised of an individual assessment of the
alternatives against each criterion and a comparative analysis
designed to determine the relative performance of the
alternatives and identify major trade-offs, that is, relative
advantages and disadvantages, among them.
The nine evaluation criteria against which the alternatives were
evaluated are as follows:
Threshold Criteria - The first two criteria must be satisfied in
order for an alternative to be eligible for selection.
1. Overall Protection of Human Health and the Environment
addresses whether 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) is used to determine whether each
alternative will meet all of its federal and state
ARARs. When an ARAR is not met, the detailed analysis
should discuss whether one of the six statutory waivers
is appropriate.
Primary Balancing Criteria - The next five "primary balancing
criteria" are to be used to weigh major trade-offs among the
different hazardous waste management strategies.
3. Long-term Effectiveness and Permanence focuses on any
residual risk remaining at the Site after the
completion of the remedial action. This analysis
includes consideration of the degree of threat posed by
the hazardous substances remaining at the Site and the
adequacy of any controls (for example, engineering and
institutional) used to manage the hazardous substances
remaining at the Site. .
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4. Reduction of Toxicity, Mobility, or Volume Through
Treatment is the anticipated performance of the
treatment technologies a particular remedy may employ.
5. Short-term Effectiveness addresses the effects of the
alternative during the construction and implementation
phase until the remedial response objectives are met.
6. Implementability addresses the technical and
administrative feasibility of implementing an
alternative and the availability of various services
and materials required during its implementation.
7. Cost includes estimated capital, and operation and
maintenance costs, both translated to a present worth
basis. The detailed analysis evaluates and compares
the cost of the respective alternatives, but draws no
conclusions as to the cost effectiveness of the
alternatives. Cost effectiveness is determined in the
remedy selection phase, when cost is considered along
with the other balancing criteria.
Modifying Criteria - The final two criteria are regarded as
"modifying criteria," and are to be taken into account after the
above criteria have been evaluated. They are generally to be
focused upon after public comment is received.
8. State and Tribe Acceptance reflects the statutory
requirement to provide for substantial and meaningful
State and Tribal involvement.
9. Community Acceptance refers to the community's comments
on the remedial alternatives under consideration, along
with the Proposed Plan. Comments received during the
public comment period, and the EPA's responses to those
comments, are summarized in the Responsiveness Summary
which is attached to this ROD.
The following is a summary of the comparison of each
alternative's strengths and weaknesses with respect to the nine
evaluation criteria.
Overall Protection of Human Health and the Environment
With the exception of the no action alternative for the East
Disposal Area, Alternative El, each of the alternatives for the
East Disposal Area and Industrial Landfill, if properly
implemented, operated, and maintained, protects human health and
the environment. Although the alternatives differ in the degree
of protection they afford, all reduce excess carcinogenip health
risks to humans to levels within the acceptable EPA range of 10"*
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to 10"6. The risks associated with Alternative LI, the no action
alternative for the. Industrial Landfill, are acceptable, in part,
because the interim cap placed on the Industrial Landfill in 1988
has been effective thus far. It should be noted, however, that
this interim measure is not considered to be protective of human
health in the long-term.
Since Alternative El, the no action alternative for the East
Disposal Area, is not protective, it will not be considered in
the remainder of this analysis.
Compliance with Applicable or Relevant and Appropriate
Requirements (ARARs)
With the exception of the no action alternatives, all
alternatives comply with ARARs or provide the grounds for
invoking an ARAR waiver as noted below.
Alternative E3; Excavation and On-Site Treatment of All
Contaminated Materials in the East Disposal Area and Alternative
L3; Excavation and On-Site Treatment of All Contaminated
Materials in the Industrial Landfill
According to TSCA disposal regulations and policy, all treatment
residuals with PCB concentrations above 2 ppm must be disposed in
a TSCA chemical waste landfill. However, EPA anticipates
disposing of. treatment residuals on G.M. property in a disposal
facility which will include, at a minimum, a vegetated soil cap.
EPA anticipates that treatment residuals will generally have PCB
concentrations below 10 ppm. Therefore, depending on the type of
disposal facility ultimately selected during design, these
alternatives require that, in accordance with TSCA regulations
(40 CFR 761.75(c)(4)), EPA waive certain TSCA chemical waste
landfill requirements for treatment residuals with PCB
concentrations above 2 ppm. These TSCA chemical landfill
requirements would be waived because treatment residuals which
generally have PCB concentrations below 10 ppm do not present an
unreasonable risk of injury to health or the environment from
PCBs. EPA bases this finding on its risk assessment and the EPA
August 1990 PCB guidance which indicate that 10 ppm is protective
of human health at the Site.
In addition, TSCA regulations require that sludges with PCB
concentrations above 500 ppm be incinerated in a TSCA compliant
incinerator or be treated by a method equivalent to incineration.
In compliance with TSCA, any sludges with initial PCB
concentrations above 500 ppm which cannot be treated by an
innovative technology to achieve PCB residuals below 2 ppm must
be incinerated.
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Alternative LI: No Action for the Industrial Landfill.
Alternative E2: Capping/Groundwater Containment of the East
Disposal Area. Alternative L2; Cappina/Groundwater Containment
of the Industrial Landfill, and Alternative E4; Mixed
Treatment/Containment of East Disposal Area Materials
New York State groundwater quality standards for PCBs require
that Site groundwater be remediated to reduce PCB concentrations
to 0.1 ppb. However, the small volume of groundwater beneath the
Site in the area between the St. Lawrence River and the slurry
wall in these alternatives (see Figure 5) may not meet New York
State standards. This is due to the fact that, although the
slurry wall will be located as close to the St. Lawrence River as
possible, it will not capture contaminated groundwater outside
its perimeter. If, after implementation of the remedy for the
G.M. Site, it is technically impracticable to collect and/or
treat this small volume of groundwater, EPA would be required to
waive New York State groundwater quality standards in groundwater
between the slurry wall and the St. Lawrence River on the grounds
that they are technically impracticable to achieve in that area.
In addition, the Industrial Landfill interim cover and the soil
cover options for the East Disposal Area and Industrial Landfill
do not comply with relevant and appropriate TSCA and RCRA
hazardous waste landfill closure requirements.
Long-Term Effectiveness and Permanence
In general, remedies which include excavation and treatment
(e.g.. Alternatives E3, E4, and L3) are more permanent and
effective over the long-term than remedies which include
containment. Containment and capping remedies (i.e..
Alternatives E2, E5, L2, and L4) provide a lower degree of
permanence in remediating contamination at the Site since
contaminated material would be left on-site indefinitely. Thus,
the more treatment included in an alternative, the better that
alternative meets this criterion. For this reason, excavation
and on-site treatment of all contaminated materials in the East
Disposal Area and Industrial Landfill (Alternatives E3 and L3)
best meet this criterion. However, Alternative E4, mixed
treatment/containment of the East Disposal Area, includes
treatment of the principal threat in the East Disposal Area and,
therefore, also meets this criterion.
Alternatives E5 and L4, excavation and on-site disposal of solids
in the East Disposal Area and the Industrial Landfill without
treatment, is much less permanent than treatment of contaminated
material in these areas. The long-term effectiveness of
groundwater containment (i.e^, Alternatives E2, E4, and L2)
depends on the stability of the slurry wall (or the groundwater
extraction system if no slurry wall is required). Long-term
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35
monitoring and maintenance of covered areas would be required and
these areas would not be usable once capped.
With respect to the treatment alternatives, Alternatives E3, E4,
and L3, incineration is a permanent and effective technology
since it results in destruction of PCBs. Of all the technologies
considered, it is likely that incineration will meet required
treatment levels.
.Chemical extraction, biological treatment, chemical destruction
and thermal extraction technologies have the potential to
permanently remediate the Site; however, uncertainties exist
because these technologies have not been proven in the past.
Treatability studies would be necessary during the design phase
to ensure long-term effectiveness of these alternatives. Recent
G.M. tests of biological treatment have not resulted in PCB
reductions which meet the Site soil/sludge residual level of 10
ppm. Solidification is less permanent than other treatment
technologies considered and solidified material would require
long-term management.
Reduction of Toxicity, Mobility or Volume (through Treatment)
Biological treatment, chemical destruction, and thermal
destruction (contained in Alternatives E3, E4, and L3) perform
best with respect to this criterion because they reduce toxicity,
mobility, and volume of contaminants through treatment. Chemical
and thermal extraction reduce the volume of toxic contaminants.
Further treatment of the extracted toxic material reduces
toxicity and mobility of the contamination. Solidification
reduces only the mobility of toxic contaminants. For this reason,
solidification is the treatment technology which performs worst
with respect to this criterion. Containment alternatives and
alternatives that do not include treatment (i.e.. Alternatives
E2, E5, L2, and L4) do not meet this criterion; although
containment alternatives can reduce contaminant mobility, they do
not employ treatment to do so.
Short-Term Effectiveness
Solids containment alternatives which can be implemented quickly
with moderate amounts of dust generation perform best with
respect to this criterion. Thus, capping of the East Disposal
Area and the Industrial Landfill without excavation and treatment
of contaminated material (i.e.. Alternatives E5 and L4) are the
alternatives which are most effective in the short term. Any
alternatives which incorporate Site excavation, such as treatment
alternatives (Alternatives E3, E4, and L3) or alternatives which
include slurry wall construction (Alternatives E2, E4, and L2),
would be accompanied by an increase in dust generation during
excavation. Although mitigative measures would be used, the
emission of contaminated dust during excavation is much greater
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36
than during containment activities where the contaminated soils
would remain relatively undisturbed.
Because the effectiveness of biological treatment in treating
PCBs is relatively unproven, implementation of this technology
could take longer than implementation of other treatment
technologies. Biological treatment, thermal destruction,
chemical destruction, thermal extraction, and solidification (as
found in Alternatives E3, E4, and L3) result in air emissions
which will have a short-term effect on the community and Site
workers. The short-term excess cancer risks to the adult Mohawk
population during implementation of certain remedial alternatives
are presented in Table 8. Community and worker exposure'would be
minimized by the use of construction methods that minimize air
emissions and surface water runoff; also, protective equipment
that minimizes workers' contact with the contaminated materials
would be utilized. Air quality would be monitored during
remediation. Risks to G.M. workers would be lower than those for
remediation workers.
The population downwind of the G.M. facility and G.M. workers
could be impacted by excavation of the East Disposal Area and/or
Industrial Landfill and emissions from treatment equipment;
precautions to minimize potential impacts will be included in the
design phase for the remediation of the Site. If necessary,
these precautions may include temporary relocation of Raquette
Point residents. Any impacted areas will be restored after
excavation, if necessary. Residual impacts to adjacent wetlands
may remain after excavation.
Completion of pilot treatability studies, remedial design, and
treatment system construction will take up to two years. The
time required to treat all East Disposal Area material would
range between one and ten years, depending on the type of
treatment employed. (Solidification could be accomplished in
approximately one year.) The time required to treat all
Industrial Landfill material would range between one and 15
years, depending on the type of treatment employed. A
combination of treatment and containment for East Disposal Area
material (Alternative E4) would require one to three years to
complete after design, depending on the type of treatment
selected. Industrial Landfill containment (including slurry wall
construction) could be completed in two years.
Implementability
All of the alternatives are implementable from an engineering
standpoint. However, there are some inherent difficulties which
may be encountered during implementation of some alternatives.
Generally, alternatives which include in-place containment of
wastes involve less materials handling than alternatives which
include excavation and treatment of wastes; they are therefore
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37
easier to implement. Thus, Alternatives E2, and L2, capping with
groundwater containment in the East Disposal Area and the
Industrial Landfill without excavation and treatment of
contaminated material, are the alternatives which are most easily
implemented. Accordingly, Alternative E4, mixed
treatment/containment in the East Disposal Area, is easier to
implement than Alternatives E3, E5, and L3, excavation and
treatment or on-site disposal of all contaminated materials in
the East Disposal Area and Industrial Landfill.
Construction of the slurry wall in Alternatives E2, E4, and L2,
while implementable, may present some difficulties. For
instance, precautions must be taken to ensure that wastes are not
disturbed during slurry wall related excavation in the vicinity
of the East Disposal Area and Industrial Landfill. Such wastes,
if disturbed, could contaminate groundwater in these areas. In
addition, the slurry wall must be designed to ensure that it does
not serve as a conduit which introduces contamination at depth
into previously uncontaminated aquifers.
Excavation in the East Disposal Area (e.g.. in Alternatives E3,
E4, and E5) could be hampered by the large boulders and pieces of
concrete, foundry equipment, and demolition debris which are
visible on the surface of the East Disposal Area. Similarly,
significant amounts of debris could be unearthed during
excavation of some areas of the East Disposal Area. During
investigations of the G.M. Site, several soil borings in the East
Disposal Area showed the presence of debris.
Alternatives E3, E4, and L3 will require treatability studies to
optimize the design and operating parameters for the treatment
system. EPA intends that the results of the first operable unit
treatability testing program will satisfy most, if not all, of
the treatability testing data requirements for the entire G.M.
Site such that additional treatability studies will not be
required during design of the second operable unit remedy.
Because the effectiveness of biological treatment in treating
PCBs is relatively unproven, the implementability of this
technology could be lower than that of other treatment
technologies. If innovative technologies are not found to be
implementable, other more proven technologies, such as
incineration, could be used to treat soils, sludges and
sediments. Full-scale equipment and vendors are available for
chemical destruction, chemical extraction, thermal destruction,
and solidification.
Cost
The costs associated with the alternatives were presented in the
discussion of each alternative and in Tables 6 and 7. These
costs are estimates and may change as a result of design and
construction modifications. Remedial costs for the East Disposal
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38
Area range from $ 9 million (for containment with a soil cover)
to $ 87 million (for incineration of all material in the East
Disposal Area). Remedial costs for the Industrial Landfill range
from $ 9 million for containment with a soil cover) to $ 203
million (for incineration of all material in.the Industrial
Landfill).
Capital costs include fixed costs (costs associated with
equipment mobilization and Site preparation) and non-fixed costs
(costs associated with treatment of a specific disposal area).
Capital costs are only incurred once for each treatment
technology. Thus, significant savings (in fixed costs) from
those costs displayed in the Tables 6 and 7 will result whenever
the same treatment technology is used for two different disposal
areas on the G.M. Site.
State and Tribe.Acceptance
New York State has expressed a preference for permanent remedies
which include excavation and permanent treatment of the majority
(on the order of 90%) of the PCB mass at the Site. The St. Regis
Mohawk Tribe has indicated that its primary concerns are
protection of the Mohawk people's health and environment through
expeditious cleanup of the Site. To this end, they support the
permanent treatment of all contaminated material in the East
Disposal Area and Industrial Landfill and comprehensive controls
which ensure that there will be no further migration of
contamination from the G.M. Site onto the Reservation or into the
waters utilized by the Mohawk people.
The Site, as defined by EPA, presents unique dangers to the
resources and people of the St. Regis Mohawk Tribe who have a
cultural and spiritual link to the St. Lawrence environment.
Special consideration must be given to Native American concerns
in evaluating and remediating the Site. The Tribe views all
containment remedies as interim measures only.
Community Acceptance
Comments from the community submitted during the public comment
period indicate that the community has varying opinions regarding
remediation of the East Disposal Area and Industrial Landfill at
the Site. Many citizens, including many Mohawks, expressed a
desire for complete removal and treatment of all contamination at
the Site. Other citizens, many of them residents of Massena,
supported a G.M. plan for Site remediation which included
containment of the Industrial Landfill and the East Disposal
Area. Community comments are responded to in detail in the
Responsiveness Summary which is an appendix to this document.
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39
DESCRIPTION OF THE SELECTED REMEDY
The major components of the selected remedy for the second
operable unit include: .
Excavation and permanent treatment of soil containing PCBs
at concentrations at or above 500 parts per million, all
sludge, and all visibly oily soil from the East Disposal
Area at the Site
Non-oily soil with PCB concentrations above 500 ppm, all
sludge, and all visibly oily soil will be excavated from the
East Disposal Area and treated to permanently destroy PCBs
and other contaminants. An estimated 59,000 cubic yards of
material will be excavated and treated. Due to past
disposal practices, this volume may include non-oily soil
with PCB concentrations below 500 ppm which cannot be
segregated from principal threat material.
The type of treatment to be used will be determined on the
basis of treatability tests during design of the first
operable unit remedy. In general, the goal of the treatment
process will be to reduce PCB concentrations below 10 ppm
PCBs (see residual levels in Table 5). If any material
cannot be treated to meet the treatment residual level using
biological treatment alone, incineration or one of the other
innovative technologies tested during design which has been
demonstrated to achieve Site treatment goals will be used to
treat it. If necessary to ensure protection of human health
and the environment, EPA will, based on the results of
additional site characterization during remedial design,
develop cleanup, treatment, or residual levels for other
contaminants of concern.
During remediation, surface water runoff will be collected,
treated, if necessary, and discharged to the St. Lawrence
River in compliance with SPDES requirements to minimize off-
site migration of contaminants via runoff. Bulk items which
are not amenable to treatment will be separated, stockpiled
and disposed in a facility which meets all TSCA
requirements, as necessary. EPA may elect not to excavate
parts of the East Disposal Area if debris, boulders,
cobbles, or other bulk items make excavation technically
impracticable. Treated soils will be backfilled in the East
Disposal Area, used to grade the remainder of the untreated
material in the East Disposal Area, and covered with a
composite cap. The East Disposal Area will be maintained
permanently.
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40
Prior to remediation, a wetlands assessment, floodplains
assessment, cultural resources survey, and a statement of
consistency with the New York Coastal Zone Management
Program will be required.
Consolidation and in-place containment of less contaminated
soils (with PCS concentrations below 500 ppm) in the East
Disposal Area at the Site
Non-oily soil with PCB concentrations above 10 ppm and below
500 ppm in the East Disposal Area will be consolidated,
regraded, and contained using a composite cover.
Approximately 115,000 cubic yards of material will be
contained in the East Disposal Area along with treated soils
backfilled in the East Disposal Area and bulk debris. The
East Disposal Area cover will be maintained permanently.
Groundwater. and air will be monitored to ensure that PCBs
and other contaminants are not migrating from the East
Disposal Area. Monitoring will continue as long as
contaminants are present in the East Disposal Area. The
containment area will be fenced and marked consistent with
TSCA regulations.
Recontouring, regradina and containment of contaminated
material in the Industrial Landfill
The estimated 424,000 cubic yards of contaminated material
in the Industrial Landfill will be contained with a
composite cover. The Industrial Landfill will be regraded
and the slope will be adjusted to comply with federal and
state requirements. The following materials will be added
to the Industrial Landfill following topsoil removal: one
foot of clay, one layer of flexible membrane liner, one
layer drainage material, one layer geotextile, eighteen
inches of rooting zone soil and six inches of topsoil.
Revegetation of the cover will be required. The cover will
be maintained. Groundwater and air will be monitored to
ensure that PCBs and other contaminants are not migrating
from the Industrial Landfill. Monitoring will continue as
long as contaminants are present in the Industrial Landfill.
The containment area will be fenced and marked consistent
with TSCA regulations.
PCB sludge, oily PCB contaminated soil, or non-oily soil
hotspots containing greater than 500 ppm PCBs may be exposed
during Landfill regrading and slope adjustment. If any of
these materials are encountered, they will be treated in a
manner similar to comparable material excavated from the
East Disposal Area. During remediation, surface water
runoff will be collected, treated, if necessary, and
discharged to the St. Lawrence River in compliance with
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41
SPDES requirements to minimize off-site migration of
contaminants via runoff.
Deed restrictions will be placed on G.M.'s property to
discourage its use as a residential area in the future.
Because PCB contaminated .soils will remain on-site in the
East Disposal Area and the Industrial Landfill, a review
will be conducted within five years after construction
begins, and every five years thereafter, to ensure that the
remedy continues to provide adequate protection of human
health and the environment.
Control of groundwater migration from the East Disposal Area
and Industrial Landfill through the use of a slurry wall
Contingent upon the results of additional data collection
(as further explained below), the East Disposal Area and
Industrial Landfill will be surrounded by a slurry wall (see
Figure 5) and runoff collection system. Pumping wells will
be installed inside the slurry wall. A comprehensive
surface water control system (including surface water runoff
collection, treatment, if necessary, and discharge to the
St. Lawrence River in compliance with SPDES requirements)
will be installed to ensure that contaminants are not
migrating off-site via runoff. The water from the pumping
wells and any surface water runoff will be treated, as
necessary, in a wastewater treatment system with a
combination of air stripping to remove volatile organic
compounds and carbon adsorption to remove PCBs. Treated
water will be discharged to the St. Lawrence River in
compliance with State SPDES requirements. During and after
remediation, groundwater and surface water will be
monitored.
EPA will consider alternatives to the slurry wall system if
data and analysis demonstrate that the present worth costs
of the slurry wall system are significantly higher than
those of any proposed alternative. Any proposed alternative
must, at a minimum, meet the objectives of the groundwater
extraction system selected as part of the first operable
unit ROD and be as protective as the slurry wall system.
Based on the currently available data, EPA believes that the
slurry wall will prove cost-effective because it will
significantly reduce the volume of contaminated groundwater
which will be extracted from the Site. EPA estimates that,
without a slurry wall, the volume of contaminated
groundwater that will need to be collected downgradient of
the Industrial Landfill is on the order of 2,000,000 gallons
per year. By comparison, EPA estimates that the volume of
contaminated groundwater which would be collected within the
slurry wall (assuming no recharge from beneath the slurry
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42
wall or from the St. Lawrence River) is on the order of
150,000 gallons per year. If data taken during design prove
that these estimates are essentially correct, then the
additional costs associated with construction of the slurry
wall would be offset within 10 years by the savings in
water treatment costs. An estimate of the cost savings is
presented in Appendix 3.
Testing of other PCS treatment technologies
As part of the first operable unit ROD, other innovative PCS
treatment technologies are to be tested concurrently with
biological destruction so that EPA will have additional
information in the event that biological destruction proves
to be unsatisfactory for treatment of any Site material.
EPA intends that the results of the first operable unit
treatability testing program will satisfy most, if not all,
of the treatability testing data requirements for the entire
G.M. Site such that additional treatability studies will not
be required during design of the second operable unit
remedy.
Biological treatment or an innovative treatment technology
will be used wherever EPA determines it to be viable and
implementable. In the event that biological treatment will
require a prolonged period to implement or is ineffective in
attaining the Site soil/sludge residual level (given in
Table 5) for a certain area of the Site or for certain Site
materials, other innovative PCB treatment technologies
(which have been demonstrated to achieve Site treatment
goals during the first operable unit treatability testing
program) or incineration may be employed. The criteria used
to judge the treatment technologies during treatability
testing include effectiveness, time to full-scale
implementation, and cost. EPA will select the treatment
technologies to be employed, in consultation with NYSDEC and
the St. Regis Mohawk Tribe.
The total present worth cost of the second operable unit selected
remedy ranges from $ 31 - $ 45 million, depending on the type of
treatment implemented for East Disposal Area material. These
costs do not include the $ 78 million associated with the first
operable unit remedy. A breakdown of estimated costs associated
with the selected remedy is presented in Table 9.
STATUTORY DETERMINATIONS
Protection of Human Health and the Environment
The selected remedy protects human health and the environment
through the permanent treatment of the principal threat material
in the East Disposal Area and through containment of less
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43
contaminated material and groundwater. The interim cap on the
Industrial Landfill is currently protective of human health and
the environment but does not meet ARARs. Treatment residuals
will be covered. Bulk items which are not amenable to treatment
will be separated, stockpiled, and disposed in a facility which
meets all TSCA requirements, as necessary. Following
implementation of the first and second operable unit selected
remedy, the excess cancer risk to the adult Mohawk population
will be on the order of 10'7.
Compliance with ARARs
A list of ARARs for the selected remedy is presented in Table 10.
The selected remedy complies with these ARARs or provides the
grounds for invoking a waiver as described below.
According to TSCA disposal regulations and policy, soil treatment
residuals with PCB concentrations above 2 ppm must be disposed in
a TSCA chemical waste landfill. However, in accordance with TSCA
regulations, EPA is waiving certain TSCA chemical waste landfill
requirements for East Disposal Area soil treatment residuals with
PCB concentrations above 2 ppm, provided they meet the Site
treatment residual goal of 10 ppm. Specifically, provided the
residuals are soils with a low water content and PCB
concentrations below 10 ppm (or a higher level if, based on the
results of treatability testing, EPA deems such a level is
warranted in order to minimize the use of incineration at the
Site), EPA is waiving the TSCA requirements regarding landfill
location and the TSCA requirement for a leachate collection
system. These TSCA chemical landfill requirements are being
waived under TSCA (40 CFR 761.75(c)(4)) because soil treatment
residuals which meet Site cleanup standards do not present an
unreasonable risk of injury to health or the environment from
PCBs.
According to New York State hazardous waste disposal regulations
at 6 NYCRR Part 370, all treatment residuals which satisfy the
New York State definition of hazardous waste must be disposed in
a landfill which meets New York State requirements. EPA does not
anticipate that treatment residuals will be hazardous (e.g.. have
PCB concentrations above 10 ppm). However, all treatment
residuals will be considered solid waste under New York State
regulations at 6 NYCRR Part 360. New York State solid waste
regulations, while mandating several requirements, including the
use of a liner and leachate collection system, allow for less
stringent requirements based on the "potential pollution" of the
waste (6 NYCRR Part 360-2.14(a)).
During design, plans will be finalized for the disposal of
residuals. These plans will include certain provisions to ensure
proper residuals disposal. Further, the residuals will be placed
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44
in a manner to ensure that they are not in contact with the
shallow groundwater aquifer. The cap will be constructed and
maintained to prevent erosion and graded to direct runoff from
the capped area. Should certain treatment residuals be hazardous
or require greater protection than discussed above, EPA in
consultation with New York State and the St. Regis Mohawk Tribe,
will impose appropriate requirements in the finalized residuals
treatment and disposal design plans.
In addition, TSCA regulations require that sludges with PCB
concentrations above 500 ppm be incinerated in a TSCA compliant
incinerator or be treated by a method equivalent to incineration.
In compliance with TSCA, any East Disposal Area sludges with
initial PCB concentrations above 500 ppm which cannot be treated
by an innovative technology to achieve PCB residuals below 2 ppm
will be incinerated.
New York State groundwater quality standards for PCBs require
that Site groundwater be remediated to reduce PCB concentrations
to 0.1 ppb. However, the small volume of groundwater beneath the
Site in the area between the St. Lawrence River and the slurry
wall in these alternatives (see Figure 5) may not meet New York
State standards. This is due to the fact that, although the
slurry wall will be located as close to the St. Lawrence River as
possible, it will not capture contaminated groundwater outside
its perimeter.
EPA has therefore determined and is hereby documenting that,
after implementation of the remedy for the G.M. Site, if it is
technically impracticable to collect and/or treat this small
volume of groundwater, EPA will waive New York State groundwater
quality standards in groundwater between the slurry wall and the
St. Lawrence River on the grounds that they are technically
impracticable to achieve in that area. Because EPA has
documented its use of such a waiver in this ROD, further public
notification of the waiver will not be required. However, EPA
will consult with New York State and the St. Regis Mohawk Tribe
regarding the use of the technical impracticability waiver for
groundwater.
Cost Effectiveness
The selected remedy is cost effective because it has been
demonstrated to provide overall effectiveness proportional to its
costs. The present worth of the selected alternative is $ 31 -
45 million. EPA has selected an alternative which includes the
use of innovative technologies (if they prove effective in
treating.East Disposal Area material) and, as a last resort,
incineration. This is a cost effective remedy since innovative
technologies are generally less expensive than incineration.
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45
Mixed treatment/containment of the East Disposal Area is
approximately three times more expensive than containing all East
Disposal Area material. However, this is a cost effective remedy
since EPA estimates it will result in a significant reduction, on
the order of 90%, in PCB mass in the East Disposal Area. The
selected East Disposal Area remedy is also cost effective
„compared to treatment of all East Disposal Area material.
Treatment of all East Disposal Area material would add another
$ 4 million to $ 57 million to remedial costs; however, the
additional costs would result in treatment of only the remaining
10% of the PCB mass in the East Disposal Area.
Containment of the Industrial Landfill is cost effective since
the interim cap on the Industrial Landfill is currently
protective of human health and the environment. The upgrading of
the Landfill cap is thus the most cost effective way to comply
with federal and State ARARs.
EPA will consider alternatives to the slurry wall system if data
and analysis provided demonstrate that the present worth costs of
the slurry wall system are significantly higher than those of any
proposed alternative. Any proposed alternative must, at a
minimum, meet the objectives of the groundwater extraction system
selected as part of the first operable unit ROD and be as
protective as the slurry wall system.
Utilization of Permanent Solutions and Alternative Treatment
Technologies to the Maximum Extent Practicable
EPA has determined that the selected remedy represents the
maximum extent to which permanent solutions and treatment
technologies can be used in a cost effective manner for the
second operable unit at the G.M. Site. Of those alternatives
that are protective of human health and the environment and meet
ARARs, the selected remedy provides the best balance of tradeoffs
in terms of long-term effectiveness and permanence, reduction in
toxicity, mobility, and volume through treatment, short-term
effectiveness, implementability, and cost while also considering
the statutory preference for treatment as a principal element and
considering State, Tribe and community acceptance.
The selected remedy for the East Disposal Area offers a higher
degree of permanence than containment alternatives. Because PCBs
are highly persistent in the environment, removal and treatment
of principal threat material provides the most effective way of
assuring long-term protection. In addition, the use of
biological treatment (or another innovative treatment technology)
or incineration) and groundwater treatment results in the
reduction of toxicity and mobility of PCBs. Although there are
short-term impacts associated with the selected remedy, these can
be mitigated and will not pose an unacceptable risk to the
surrounding community, G.M. workers, or remediation workers.
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46
Biological treatment and the other innovative treatment
technologies present some difficulties in implementation since
they must be tested during design. However, incineration is a
proven technology for the destruction of PCBs which can be used
if necessary to ensure destruction of contaminated materials.
Biological treatment is the least costly of all treatment
alternatives evaluated. Therefore, use of biological treatment
where it is effective minimizes the cost of the selected
alternative provided treatability tests show that it performs in
a manner comparable to the other technologies considered. In
addition, EPA favors the development of innovative technologies.
The selection of treatment is consistent with Superfund program
expectations that highly toxic, persistent wastes are a priority
for treatment which ensures long-term effectiveness. The
selection of containment for less toxic, less mobile material in
the East Disposal Area and for the Industrial Landfill is
consistent with the Superfund program expectation that
engineering controls be used to address material that poses a
relatively low long-term threat or where treatment is
impracticable. Highly contaminated material in the Industrial
Landfill is inaccessible. In addition, the Industrial Landfill
poses no current risk to human health or the environment.
Groundwater containment using a slurry wall is an effective way
of minimizing off-site migration of contaminated groundwater to
the St. Lawrence River system or to the St. Regis Mohawk
Reservation.
Preference for Treatment as a Principal Element
By treating non-oily soil with PCB concentrations above 500 ppm,
all sludge, and all visibly oily soil in the East Disposal Area,
the selected remedy satisfies the statutory preference for
remedies that employ treatment as a principal element for the
principal threat posed by the East Disposal Area and Industrial
Landfill at the Site.
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APPENDIX 1
FIGURES
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12
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APPENDIX 2
TABLES
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two p«l»»rn» of
rnnrmlmt lorn wild ifrplh >r«
rvlrimt. Oor trxflc«lr»
conrvnlratlon wllli
I* •! lr*f thin 10
fi»*» try • rfrplh of II tfft. thr
•rconrf InrfirntFA concmtrBtlon
of » 25 rP» •' • ?0-foot dpplfl.
«DC.
with th« «ncn>tlon of PCC «nrf
POE In IMO
fwo boring Kcount**! for tf<«
only quimllf l*bl« «(n«rv*tlonm>l . ? nvlhylphrnol .
•nil 4-OT>ltiytfifc«noD. lh«
concent rot Ion* of
nw« •vsoclatvd with
•TV** of post MMte t«ct«rf In
turflcUl •oil* •rut borlnf
•wplv«. All MM*, with the
•nc*ptlon of '7-«etfiyl*
iwphthaltnr, ner* itetectcrf belon
tto HOI.
$/$
08
^
oce
PC(
ict
NCR
vnti
vc
Sulmirfac*
*«|OM Hrthorf 0«l«cllon Unit
of
of
Ethyl
Volmlle
Vinyl
Vlplirnyla
ArtMitlc Hyifrocarbom
Rrvlvlon:
-------
***" * ««l«»ll«»f»l
<•••«••? •" »i n •« i-
<*• no •»-.-t%»
•Mietin MT a
•••• •••••Mil
rhtti.ilntrt
*: 'V •» .' n |,M «.•/»•
S/V I*, to If „„ ,..,,,
Nrtnl*
b. Crowd
. (AST 0ISMKM MCA
. Soil*
(MH
ffot«l>
WKS
•HOI
(1/Vt
OC(
PCC
K€
NTK
me*
vc
rcn'w
«•*••
0«t«ctlan
of
«t
tetritrhloro*thyl
fthyl KM one
Volatile Or f (wile
Vinyl CMorltV
Palychlarlnnlrtl •Iphmyl*
AreMilic Nyrfrotm-tmn*
S: See
MIUA, Hot Detected to 0.00*1
Si lip to 41.000 n» («0/«8)
NrrfiiM • I? p»««
$/$: lip to SO.OOO n» (Br/09)
H«dl«« • 7.5 ppn
ft MTK «f> to t.OI rv* O/8)
S/S: Rylctw up to 0.000 &m
totuene n> to 0.01
trair fhtbulaf cmfiminifv wrrr
«Vt«r«rd in •iirflcitl ^oM unrf
Imrinq lr!t. Ounnt I (I IthI F
rtwicmtmtlom of |*>lfi»l»t*
tn*KNnt« tur*r*6 frn»rvrtl •« tancmtrntlom
In tMclvromf
comtltumt
for
Concentration*
co«pw l«on to
|n
IM* I II.
Nrat of tK* Kit «•*•
within |h« bnunforlrt .f
lhr«« •cMltlon.il or«»» od|«c«n«
to the •!««•» dlmpoMl •«*•«
ocre otto drf lord.
ft«o«« I ontf HIM* II •! r««utt«
InrflcotMl ttt« pr«««nc« of «l«v«n
VOCs. ttwse concentration* or*
low onrf do not wn-ront further
1907
-------
t«mr ?
9MM»T (W III
mi: CID
mcciro
— •*"' J_l» •' «• • "C. »J_
Phrnnl*
S: lip |n M.OOO nn
s/s: tip to n.nnn n*» it/tni
Phrnnl imtl
(ihrnnli
In «oH
I
nrrv
OTMttfS
thrre Jitfnt Mulrrt
l*> urrr
tmrinq
| results lnrticn:e
s: nun to o.* np»
S: Up to * nji
S/S: Uf> to 8 pjM
Se«
to 0.0017
U|> to 0.06
dtlf»r»nt
«*r* o>t«ct*d In toll
•nd *lud«« IMP)*!. nil Of
thr«« CURIUM«H cnrr««pnral to
p*it MMU dltpmd.
co»|Mir»bl« to twckoroml.
Detected In flrct rowd of
•••pi Ing but could not be
confirmed fay three tUbsequtnt
roundi.
fuo round* of fho«e I •! re«ull«
Indicated presence of pttenola.
Ihe two roundi of PhMe II •!
Irvflcotctf no detectoble phenol •.
Surfuce
•rlon H^lhod Detection I Nit
Mwtwr ol Siwples Oet«ct«tf/Nwtor
l,?-lr*n«-dithloro«tli|rlcne
fetrnr.hlororthylvne
of Swfilef «n«lrt*d
Hrlhyl Cthxl Rrton*
Volatile Organic Cowpoundf
Vinyl Chloride
folychlorlrwtcfl llpncnyU
folynuclcM- AroMatlc HynVocvrbom
•evl*lon:Move»t»er 1
-------
uuiir I
If O* Ml HUM IS
IMC-CIO MSStMA
1. INDUSIIIIM.
•. SotU/Uaito
OMSUtUTMIS
f€i» (total)
•ABU t»«ia«acf
S: I»P to *> nm
Median • 1.7 npa>
S/S: lip to *IOO f(m (00/90)
Median • t.r «•
voc«
S/S: tec up to 1.1 pp* (2/12)
rt»meU/$ to 8 PP>
S/Sl U|p to 51 W»
Si
S/S: Up to 3 fpm
St Up to 4
up to »
08
S ^°
Qo
S
S/S
•MDl
«t/9>
OCC
PCE
ICC
WK
¥OC»
VC
Surface
Method Detection Halt
of $w*ile« Oetected/Ni«t>er of Staple* Analyted
t.?-lr«n«-dirhloroetliylen«
telrachloroethylrn*
trichlororthylme
Nrlhyl Ctliyl Ketone
Volatile Organic Coapotmta
Vinyl CMorlrft
rolycMorlnated UpKenyU
rolynuclacr *roa»tlc Hydrocarbon*
Ten different VOC» utre detected
In boring ia>v>lea. Of fourteen
detectable value* In toll boring
an^plea, 9 Hera found In two
aiMplea. Contaninat Ion la
generally Isolated and at IOM
level*.
2.4-dlvathylplienol. 4-
aKlhylpttenol and fjhenol were
detected In MM •oil boring
•awptea.
fifteen different *M* Mere
detected In toll boring and
•urfaca «oll •••pie*. tuenty-
three of 32 oh*ervatlona of M«a
wre MH. One awple accounted
tor 1) of 52 PlW occurrence*.
tour phtkalate* Mere detected In
•oil boring and iurface toll
•aiple* lro» thU area, tn five
of the 18 «a«ple*. the
concentration* or* below HDL.
•evUlent
IWf
-------
9WMMT M •!
(MC-CIB IMSSIM
Mircito AIM
Nrliils
Sr* Cmwrnt*
•IS
ttttf . |li«
ornirrrnt* of Irorr »rl
«o
(Ml UMM)
to i.j rr-
T3
go
TO 73
QO
zc:
*/s
fwoi
ore
vot*
vc
•*••»
Surface
Nelltail 0«l«cl
MMnot i/Substltuted rtwnoU
MM* (Ml ?«•)
rtilnaUte* (*everal well*)
Nrlalt
of f«if>1e«
1.? OCI up to 0.«M
<«/*>
tec up i« «.o%o pf
(4/61
vc o.a%o «»
Up to 0.074 |
Up to 0.1M |
Up to 0.08?
Only «*«plr«o.
Only toB|>l*« fro» M«ll MI-tM
•bowed o comlttcnt fMttvrn of
VOC occurr«nc*. Hiose M II
dot* ihoMcd lower
concentration*.
Contentrotlon* drcre»*ed fro*
Hiose I HI result* lo Wiwe II
III result*.
four MM* drtected In fW-?M In
ffiaie I end rat ffiose M.
PfitMlate* Mere *e«n In the
ffi»i» I Ml but not In W»»»e II
•I tMplInf of well*.
•II MCT« wJtMn botkfroural
cone entral lorn.
Nflhyl MM (rl
Volvlllv Organic
Vinyl CMoriitr
PolynucUvr «r
-------
IMMf 7 (mat •••!>»
•MMWMf m •• M MN IS
1HT. CIO
*.
lip In no u»
(19/19)
• II lnqnnn* urtf fmmt lo
PCH« In nnrf/nr l»mr.tlli s
within th* Iftonon* «tirf
«tfly Mf|m:<^«l lo
voc»
•\)
o
00
22 >;;'J
QD
Z<^
^>:
*
v<
•MM
«1/V|
occ
W€
ICf
MTI
•flow Nfllmil 0«l«ctlan Halt
Nu4M>r of Siwpl
1.7- Iram-rfifhlorovlhylcnr
rrr •«• to A r
Inliirnf ««t to /A r*» (H/U)
in <». to I
»r up io ? r
> lo I.) «!• <4/U>
Up to 76.000 n» t««/H>
Up lo 10 (*«• O/U»
UP t« sr
of SMf>l«*
Nrltiyl (Ihyl (rlonr
VolMllv Organic Co«f>m»iiH
Vinyl CMorlrfp
rolycMorliwlMl •Iphrmyl*
- Aroaatic NyoVot*rhotM
Ihlrlwn wne* wrr* oVtrctfil In
doll «ntf/or (Imtyei fro* th«
ti»9Oon are*. VDC* thoxfrf up
•nit ottm «nrf wrrv •tnrroMy •!
conrvnlral Ions In
fro* the J^O.nm-aallon
(ly,( iflffrrmt VOC*
Mi>rv oVt*cl*d fro* *luoV« (ran
thv 50O.OOO tultoo Itxymm. flv*
different vats wprr T« ol the
. tliitFCn ol Jf r«fwrt«l
orcurrrnrr* of MM* «rr« of
conc«ntratlom below th« KM.
Only «n» |Atfial«t« MM
In t»»« 1>0, 000
In ttiv I.) N-f«t t«fnon. |M>
*rrr oVleclrtt In the
-------
IMNf ? (Cra
SIMM*? a* •! •Iranis
«W-CfD MASUM
ftmciio
b. Soil*
OMSMJIRNIS
Mi1rosmfi|4trftylMiitnr
Mi-tuts
PIB* I lot nil
In ?MI ffm (i/Ul
Sre Camrnts
S: <%» to ?IIO w> 411/111
NXfim* » /.* pn*
S/S: •»> l« «l r
O»MIIIIS
OrtrrlrtJ In Ihp 150.000 «•!! on
luijooo.
flrvm of 7) Mrtitl*
bacl^roivirf, nolHhly C, Ft>. H9.
PC« concmlrctians rtngtd tram
•not to ;m nw.
voc*
Mtenots/SUbMltuted Hienols
S: Mo dried*
s/s: me up to o.i n« «/»>
S: No drivels
S/S: l%> lo 4 «w
»lv« «DC» Mrrv drlvclvd In* toll
•••pics. Hilh lh» «*c«fillon of
MR. •)! v»lur« of VDC* M»r*
lets lh«n 0.01 ffm.
All concfnlrstlom of co^munrfi
In IM< tf were otnervrrf
brloM (lie MM. wllh Ih*
mrrplton of ptwnol In one
•wt
rtilMUte*
S
S/S
Surface
NeUll
Below Nridorf 0«l«cllon H"U
Nurfwr of Siwpln PvtectMf/Nurfirr «f SMpl«« Amlyitd
c
L>-*a«
•=*• 1
o«
Mil
VOC*
vc
lelrcrhloroelhylcne
Irlrhlororltiylfne
Nrlhyl f l
Volalllr Or«mlc
Vtnyl CMoridr
S:
s/S: Mo
S:
S/S:
to If
See
SI* MM Mrre oVl«cl«
-------
tMNf 7
aniim nt at
ij«r cio
ftmr.trn
c. Ground Untrr
rr.ru
HP in n.mu
<*t
!•»«> HI I rfntn from MU71H
Una,
rounfi or BTWC split ti«vilcs.
o
oo
70 70
S
5/S
Surface
OCE
PCf
tec
vori
vc
ff.t't
•«•••
Rrlow Hr(hod Ortvctlon tlnlt
of Smiles 0*trctnf/Nu4«vr of SwfitM
frlchlororthylrne
Mr thy I (thy! K«ton»
Volntll* Organic CoifMNnih
Vinyl ChlorJde
PolytMorlrmlrd •Iprtrnyl*
f>olynucl«*r Aromtlc
19fr9
-------
fNMt 7
9»«w*T
ow: c»o Mivwm
_Mrj|
V SI. lAIMrHCC
SIDIMTNI
S: "O - S./OO (1fl/W)
Hnltnn - 74 pfm
vacs
Phenol s/Sdbst I tuted Phmols
fhthalates
MTR U|> to 0.0321 rr- U« Oeteeted/Nutor of
1.7 Irnm-dicMocoHhylene
TetrMchlornelhylene
Trlchloroelhylene
Hethyl fthyl Retone
Volatile Organic Co^xmndt
Vinyl Chloride
rolychlorlnated llphenyU
folynucletr AronBtlc Hydrocarbons
Sec
Nercwry «ml •elenlu* wero Mbov*
local tMclfrowirf concentration!!
but Ml thin thote reported for
tollt In Men fork.
Anolyted
Zof.St MO:lltt:iMO)Olt.rcv
•evl«lon:Nove*t>er
-------
tomr
nr «i
Atrrcuo ««rii
Cfmf IIINMt*
_•«•« ji HI«• «w:»l_
Ma*tit tivtt.
IT.H* (tntnl)
. Srdinents
b. Soils on River ftw*
S: 0.14
7.5 i?/4)
a '1.5 PP"
S: ».?? - J? tin/Ill
Mrdim* * t.f ^M
In
locnlltrd"
•t out fill I
II rfrlrcl of 740
Mm found.
T. orr-sitr sons
UIHUIMT)
S: M>
40
flrrflwt a
flie npatUI dlMrlhutlon of re**
Indicate* (hut rwtoff over •
Hulled ore* In the southeast
corner of the CMC-cr» facility
ims the prlnwry route by which
Mlfroted fro* the facility.
VOCs
•Ms
HithcUtes
Netols
S: K« «*>to 0.9 ft*> O/W)
S: Wtn (1/151
St INH. (15/151
t: •MM • r.V9 pp« (1/19)
See
Ho •*!•!• «er« Identified •bow
bockfround levels.
•o
O
00
22 73
QO
s
s/s
•wi
Surface
oct
fee
•WK
vc
**•••
•»»••
Method Detection limit
Nurfwr of Simple* Oetected/Nurfjer of Softies Anolyted
1.?-frims-dichlnroethylerw
tetrochloroethylene
Trichlororlhylme
Nethyl f thyl Rrtone
Volollle Orqunlc Cmfmmds
Vinyl Chloride
folychlorlmted •Ipnenyls
folynuclenr Arowitle Nydroorbom
Revision:
1909
-------
TABLE 2
SUMMARY OF EXPOSURE ASSUMPTIONS AND EXPOSURES
VIA ALL PATHWAYS FOR THE G.M. SITE
Pathway
Wildlife Consumption
Consumption •
Wildlife Concentration
Exposure
Soil Ingestion and
Soil Dermal Contact
Soil Ingestion
Soil Concentration
Exposure
Water Ingestioo
Ingestion
Water Concentration
Exposure
Most Probable
Worst Case
6.6 g/day
23 mg/kg
0.002 mg/kg-day
39 mg/day (child)
10 mg/day (adult)
0.065 mg/kg
1.1 x 10"'mg/kg-day
1.4 I/day
l.Opg/1
2 x 10"5 mg/kg-day
6.6 g/day
33 mg/kg
0.003 mg/kg-day
200 mg/day (child)
100 mg/day (adult)
3.3 mg/kg
3.5 x 10"' mg/kg-day
2.0 I/day
7.5 ngfl
2.1 x 10"4 mg/kg-day
-------
TABLE 2 (com.)
SUMMARY OF EXPOSURE ASSUMPTIONS AND EXPOSURES
VIA ALL PATHWAYS FOR THE G.M. SITE
Pathway Most Probable Worst Case
Breast Milk
Ingestion 800 ml/day 800 ml/day
Milk Concentration 0.07 mg/1 •• 0.22 mg/1
Exposure 8.9 x 10"5 mg/kg-day 2.8 x 10"* mg/kg-day
where: g = grams
mg = milligrams
kg = kilograms
1 = liters
tig = micrograms
ml = milliliter
Source: "Baseline Risk Assessment for GM/Massena Site," prepared by Gradient
Corporation for the U. S. Environmental Protection Agency, September 15, 1989.
-------
TABLES
SUMMARY OF CARCINOGENIC RJSKS TO ADULT MOHAWKS
Pathway Most Probable Worst Case
Wildlife Consumption
Soil Ingestion/
Derma! Contact
Water Ingestion
Breast Milk
1.7 xlO"2
8.5 x ID"7
1.5 xlO*
6.8x10*
2.4 x ia:
2.7xl(rs
1.7 x ias
2.2 x ias
TOTAL l.Sxia2 2.7 x 10-2
Source: "Baseline Risk Assessment for GM/Massena Site," prepared by Gradient
Corporation for the U. S. Environmental Protection Agency, September 15, 1989.
-------
TABLE 4
SUMMARY OF NONCARCINOGENIC EFFECTS ON ADULT MOHAWKS
Pathway Most Probabjg Worst Case
Pathway HI Pathway HI
Wildlife Consumption 21.7 31.1
Soil Ingestion/ 1.1 x 10"3 3.5 x ICr2
Dermal Contact
Water Ingestion 0.2 2.1
Breast Milk 8.9 x 10"1 2.8
CUMULATIVE HI 22.8 36.0
where: HI = hazard index
Source: "Baseline Risk Assessment for GM/Massena Site," prepared by Gradient
Corporation for the U. S. Environmental Protection Agency, September 15, 1989.
-------
TABLES
G.M. SITE SECOND OPERABLE UNIT
CLEANUP, TREATMENT, AND RESIDUAL LEVELS
Medium
Sludge, Visibly Oily Soil
Non-oily Soil on
G.M. Property
Groundwater
Collected Site
Surface Water
Runoff
Contaminant
PCBs
PCBs
PCBs
Total Phenols
1,2 DCE
TCE
VC
PCBs
Total Phenols
1,2 DCE
TCE
VC
Cleanup
Level
lOppm
lOppm
0.1 ppb
Ippb
5 ppb
5 ppb
2 ppb
Treatment
JVC
lOppm
500 ppm
0.1 ppb
Ippb
5 ppb
5 ppb
2 ppb
65 ppt ***
Ippb
50 ppb
3 ppb
300 ppt
Residual
Level1"
10 ppm**
10 ppm
65 ppt ***
Ippb
50 ppb
3 ppb
300 ppt
65 ppt ***
Ippb
50 ppb
3 ppb
300 ppt
where: ppm = pans per million
ppb = parts per billion
ppt = parts per trillion
1,2 DCE = l,2-(trans)-dichloroethylene
TCE = trichloroethylene
VC = vinyl chloride
* Residual levels are those levels which must be met in the residual of any treatment
process which is employed to remediate the Site.
In compliance with TSCA regulations, sludge with initial PCB concentrations above 500
ppm is subject to a 2 ppm residual level.
Water would be treated to comply with SPDES which currently requires that PCB
concentrations in the discharge be non-detectable, down to the method detection level,
using EPA Laboratory Method Number 608.
**
***
-------
TABLE 6
COSTS ASSOCIATED WITH EXCAVATION AND ON-SITE TREATMENT OF
MATERIALS IN THE EAST DISPOSAL AREA WITH
PCB CONCENTRATIONS ABOVE 10 PPM
Alternative
Excavation and
Biological
Treatment
Excavation and
Chemical
Destruction
Excavation and
Chemical
Extraction
Excavation and
Thermal
Destruction
Excavation and
Thermal
Extraction
Excavation and
Solidification
Construction Cost
ISM)
33
76
55
86
76
39
Annual O&M
Cost rSK/veart
102
165
165
165
165
165
Present Worth
Costs TSM)
34
77
56
87
77
40
where: O&M = operation and maintenance
$M = millions of dollars
$K = thousands of dollars
Source:
Draft Feasibility Study for G.M. Site, November 1989
-------
TABLE?
COSTS ASSOCIATED WITH EXCAVATION AND ON-SITE TREATMENT OF
MATERIALS IN THE INDUSTRIAL LANDFILL WITH
PCB CONCENTRATIONS ABOVE 10 PPM
Alternative
Excavation and
Biological
Treatment
Excavation and
Chemical
Destruction
Excavation and
Chemical
Extraction
Excavation and
'Thermal
Destruction
Excavation and
Thermal
Extraction
Excavation and
Solidification
Construction Cost
fSM)
61
176
125
202
176
87
Annual O&M
Cost fSK/vear>
102
165
165
165
165
165
Present Worth
Costs (SM)
61
177
126
203
177
where: O&M = operation and maintenance
$M = millions of dollars
SK = thousands of dollars
Source: Draft Feasibility Study for G.M. Site, November 1989
-------
TABLE 8
ESTIMATED WORST CASE TRANSIENT CANCER RISKS AND
NONCARCINOGEN1C EFFECTS FOR
ADULT INDIANS DURING
IMPLEMENTATION OF CERTAIN REMEDIAL ACTIONS
Alternative Transient Cancer Transient Noncarcinogenic
Risks to Effects on •
Adult Indians Adult Indians
fflazard Index)
Capping of the East 2.9 x lO"6 3.7 x 1&S
Disposal Area .
Capping of the Industrial 9.1 x 104 1.2 x 104
Landfill
Excavation and Treatment 7.8 x 10"* 5.5 x 10"J
of Material in the East
Disposal Area with PCB
Concentrations above
10 ppm
Excavation and Treatment 2.8 x Itf* 3.0 x
of Material in the Industrial
Landfill with PCB
Concentrations above
10 ppm
Source: "Risk Assessment for Five Remedial Alternatives at the G.M. Site," prepared by
Gradient Corporation for the U. S. Environmental Protection Agency, April 2,
1990.
-------
TABLE 9
SUMMARY OF COSTS OF SELECTED SECOND OPERABLE UNIT REMEDY
Component of
Selected
Remedy
Mixed
Treatment/
Containment of
Material in the
East Disposal
Area ***
Capping (with a
composite
cover)/
Croundwater
Containment of
the Industrial
Landfill***
Construction
Cost (SM)
24 -38****
8
O&M Costs
(SK/vear*)
367 (2 years)
15 (28 years)
200 (30 years)
Present Worth
CostfSM)**
24 - 38****
11
TOTAL
*»»»»
28 - 42****
567 (years 1 - 2)
200 (years 3 •
28)
31 - 45****
**
***
****
*****
O&M begins after completion of construction.
Based on an assumed discount rate of five percent
Includes cost for slurry wall around both the Industrial Landfill and the East
Disposal Area.
Costs will depend on the type of technology employed to treat material in the
East Disposal Area with PCB concentrations above 500 ppm.
Reflects the cost savings associated with installation of a single slurry wall around
both the East Disposal Area and the Industrial Landfill. .
-------
TABLE 10
MAJOR APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS,
AMONG OTHERS, ASSOCIATED WITH THE SECOND OPERABLE UNIT
SELECTED REMEDY
Chemical-Specific ARARs
• Safe Drinking Water Act
Maximum Contaminant Level (MCL) for PCBs, trichloroethylene, vinyl chloride,
1,2 - trans-dichloroethylene
• Clean Air Act
National Primary and Secondary Ambient Air Quality Standards at 40 CFR Pan
50 ' .
• New York State Requirements
Groundwater regulations at 6 NYCRR Pan 703
Surface water regulations at 6 NYCRR Pan 701, including Appendix 31
Air quality standards at 6 NYCRR Pan 257
Action-Specific ARARs
• Toxic Substances Control Act
40 CFR 761.60-79 PCB disposal requirements
• Resource Conservation and Recovery Act
Closure requirements at 40 CPU 264 Subpans G, K, L, and N
Groundwater monitoring requirements at 40 CFR 264 Subpan F
Incineration requirements in 40 CFR 264 Subpan 0
Design and operating requirements for waste piles at 40 CFR 264 Subpart L
Design and operating requirements for a landfills at 40 CFR 264 Subpart N
• Design and operating requirements for tank at 40 CFR Subpart J
Generator requirements at 40 CFR 262
-------
TABLE 10 (com.)
MAJOR APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS,
AMONG OTHERS, ASSOCIATED WITH THE SECOND OPERABLE UNIT
SELECTED REMEDY
Transporter requirements at 40 CFR 263
Land Disposal Restrictions (for hazardous treatment residuals only) at 40 CFR 268
• Clean Water Act
Best Available technology and monitoring requirements at 40 CFR 122.44(a, e, i)
Best Management Practices program requirements at 40 CFR 125.100
• Clean Air Act
Standards of Performance for Incinerators at 40 CFR 60 Subpart E
• New York State Requirements
Solid Waste Management Facility regulations at 6 NYCRR Pan 360
Final status standards for hazardous waste facilities at 6 NYCRR Pan 373-2
Implementation of National Permit Discharge Elimination System at 6 NYCRR
750-757
Location-Specific ARARs
• Executive Orders 11988 and 11990
Floodplains management and protection of wetlands at 40 CFR 6.302 and 40 CFR
6, Appendix A
• Fish and Wildlife Coordination Act
Protection of endangered species and wildlife at 33 CFR Parts 320-330 and 40
CFR 6.302
• National Wildlife Historical Preservation Act
Preservation of historic properties at 36 CFR 65 and 36 CFR 800
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TABLE 10 (cont.)
MAJOR APPLICABLE OR RELEVANT AND APPROPRIATE REQUIREMENTS,
AMONG OTHERS,
ASSOCIATED WITH THE SELECTED REMEDY
• Endangered Species Act
Protection of endangered species at 50 CFR 200, 50 CFR 402
• Wild and Scenic Act
Protection of recreational river at 40 CFR 6.302(e)
• Coastal Zone Management Act
Conduct activities in manner consistent with State program
• New York State Requirements
Wetlands land use regulations at 6 NYCRR Pan 661
Freshwater wetlands requirements at 6 NYCRR 662-665
Endangered species requirements at 6 NYCRR 182
Coastal zone management policies at 1 NYCRR Part 600
"To Be Considered" Requirements
• Toxic Substances Control Act
40 CFR 761.120-135 PCB Spill Policy
• New York State Requirements
Guidance for control of toxic air contaminants at Air Guide 1
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APPENDIX 3
ESTIMATED SLURRY WALL COSTS
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Central Motors CFD
Hydraulic Evaluation; Question - How much less water will need
to be treated If & slurry wall 1$ placed around the
Industrial Landfill?
Case 1: Cap only.
dater volume needing treatment 1s assumed to bo groundwater
discharging to St. Lawrence River downoradltnt c>f Industrial
Landfill.
Q • water volume discharging to rlvtr Vn cm H
KT * hydrauHt conducUvUy of IU1 unit
K$ e : hydraulic conductivity of glactofluvlal unit
A- « cross-sectional area of fill unit at discharge zone.
(Length of discharge rone x unit saturated thickness)
AG * cross-sectional >rea of gUcicfluvlal unit it discharge jcne
(Length of discharge zone x unit thickness)
1 * typical gradient across landfill to discharge point
cm/s
KG * 2.0xlO*3 cm/s
AT - 15750 ft2 « l.AxlO7 cm2
A = 5250 ft2 * 4.8xlOe cm2
(total discharge) e Q *
) (4.8xl06)
rnVi * 2.8xl02 cmVfc
3.0xl02 cm3/* * 300 cmVs = 0.3 1/s
x 86,400*/d
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Case 2; Cap and slurry wall «ncapsulatlon.
Water volume needing treatment U assumed to be equal to the
amount of water infiltrating through the cap of a cap and
slurry wall encapsulation system.
Vj * volume of water Infiltrates through cap
A^ « area of cap 1n ft
RA • rainfall (annual) In ft/yr
EC s cap efficiency, in % infiltrating
AC • S&0,000 ft2
RA * 2.75 ft/yr
Ec * 0.02
« (380,000 ft2) (2.75 ft/yr) (0.02)
* 20,900 ftVyr
» 156,300 gal/yr
of Case ! vs. Case 2
Case 1 (C&p only encapsulate on) treatment costs
This remedy requires that 2.5x10 gal/yr of water be
treated. At $0.10 per gallon, 1t will cost $2K),000 per
year to treat.
Case. 2JCap_ and slurry wall encapsulation) treatment costs
This remedy requires that 155,300 gaVy of water will be
treated. At $0.10 per gallon, tt will cost $1S,630.
U-^e 1 UiMUl Costs
The cost of Installing the new cap on the Industrial
Landfill 1s estimated at $7.1 million.
Case 2 Capital Costs
The cost of Installing the new cap on the Industrial
Landfill and Installing a slurry wall, keyed Into the till
btneath the lower gladofluvlal unit, 1s $7,1 million (cap)
plus $1.24 million (slurry wall), or $6.34 million.
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Cost of Slurry Mall
C« Cost
P* unit price of slurry wall installation, 5n $/vsf
(Vertical square foot)
L= Length of slurry wall
D« average depth of slurry wall
P« $10/vsf C* PxLxD
L* 3,100 ft. « ($10/v$p)(3100)(40)
D* 40 ft. « $1.24xl06
The maintenance and monUoHna cost* for tach cast (cap
repair, plumbing/electrical repairs, etc.) should be
comparable. The major point to be made In thl* evaluation
s opposed to the additional $234,000
annual «xptns* of water treatment that wlll-fet required if
no slurry wall H installed.
It becomes readily apparent that the installation of the
slurry wall system, by significantly reducing the volume of
water required to be treated, will pay for itself within
5-10 years.
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