Superfund Proposed Plan
Grasse River Superfund Site
Massena, St. Lawrence County, New York
&EPA
Region 2 September 2012
PURPOSE OF THIS DOCUMENT
This Proposed Plan describes the remedial alternatives considered for the Grasse River
Superfund Site (Site), also known as the Alcoa Aggregation Superfund Site, and identifies
the preferred remedial alternative with the rationale for this preference.
This Proposed Plan was developed by the U.S. Environmental Protection Agency (EPA)
in consultation with the New York State Department of Environmental Conservation
(NYSDEC) and the Saint Regis Mohawk Tribe (SRMT). EPA is issuing the Proposed Plan
as part of its public participation responsibilities under Section 117(a) of the
Comprehensive Environmental Response, Compensation, and Liability Act of 1980, as
amended (CERCLA), and Section 300.430(f)(2) of the National Oil and Hazardous
Substances Pollution Contingency Plan (NCP). The nature and extent of the
contamination at the Site and the remedial alternatives summarized in this Proposed Plan
are described in greater detail in three documents: the Comprehensive Characterization of
the Lower Grasse River (CCLGR), Addendum to CCLGR, and Analysis of Alternatives.
These documents, as well as others, are part of publicly-available administrative record
file. EPA encourages the public to review these documents to gain a more
comprehensive understanding of the Site and the Superfund activities that have been
conducted at the Site.
This Proposed Plan is being issued to inform the public of EPA's preferred remedy and to
solicit public comments pertaining to all of the remedial alternatives evaluated, including
the preferred alternative.
EPA's preferred remedy consists of dredging polychlorinated biphenyl (PCB)-
contaminated sediment from the near shore portion of the river containing PCBs at
concentrations at or above 1 milligram per kilogram (mg/kg) (estimated to be 109,000
cubic yards) and backfilling of the dredged area to grade. The preferred remedy also
includes the placement of an armored cap over 59 acres of PCB-contaminated sediment
in the upper two miles of the main channel of the Grasse River, where the sediment
column is susceptible to scouring due to severe ice jam events, and placement of one foot
of capping material over approximately 225 acres of PCB-contaminated sediments in a
five mile stretch of the river immediately downstream of where the armored cap will be
placed. Dredged sediment will be dewatered and stabilized prior to disposal in Alcoa
Inc.'s (Alcoa's) on-site Toxic Substances Control Act (TSCA) and Resource Conservation
and Recovery Act (RCRA)-permitted landfill, and potentially at an off-site permitted landfill.
Institutional controls such as fish consumption advisories will remain in place (although
perhaps modified as needed) until the concentrations of PCBs in fish tissue are at an
acceptable level. Measures to reconstruct impacted habitat would also be implemented,
including habitat assessment and surveys during remedial design. The design will address
placement of habitat recovery material and aquatic vegetation. The preferred remedy
includes long-term monitoring of the capped areas to ensure the stability of the cap and
that the caps are functioning as designed. Long-term monitoring of fish, water column,
and sediment to determine when Remediation Goals are reached, and also monitoring the
reconstruction of habitat will be performed.
The remedy described in this Proposed Plan is the preferred remedy for the Site.
Changes to the preferred remedy, or a change from the preferred remedy to another
remedy, may be made if public comments or additional data indicate that such a change
will result in a more appropriate remedial action. The final decision regarding the selected
remedy will be made after EPA has taken into consideration all public comments. EPA is
soliciting public comment on all of the alternatives considered in the Proposed Plan and in
the detailed analysis section of the Analysis of Alternatives report because EPA may
select a remedy other than the preferred remedy.
MARK YOUR CALENDAR
The public comment period on
the Proposed Plan closes on
November 15, 2012.
Public Meetings
Monday, October 29, 2012 at 7:00
P.M.:
Office for the Aging - Seniors
Dining Hall
29 Business Park Road
Akwesasne, NY 13655
Tuesday, October 30, 2012 at 7:00
P.M.:
Massena Town Hall
Board Room #30
60 Main Street
Massena, NY 13662
Public Information Sessions
Monday, October 29, 2012 at
1:00 - 3:00 P.M.:
St. Regis Mohawk School
385 Church St., Akwesasne, NY.
Tuesday, October 30, 2012 at
1:00 - 3:00 P.M.:
Massena Town Hall
Board Room #30
60 Main Street
Massena, NY 13662
Community Role in the
Selection Process
EPA relies on public input to
ensure that the concerns of the
community are considered in
selecting an effective remedy
for each Superfund site. To this
end, this Proposed Plan has
been made available to the
public for a public comment
period which begins with the
issuance of this Proposed Plan
and concludes on November
15, 2012.
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INFORMATION REPOSITORIES
The administrative record file, which contains copies of the
Proposed Plan and supporting documentation is available at the
following locations:
Massena Public Library
41 Glenn Street, Massena, NY 13662
315-769-9914
Hours: Mon & Fri, 9:30 am - 5:00 pm;
Tues - Thurs, 9:00 am - 8:30 pm; Sat & Sun, closed
St. Regis Mohawk Tribe -Environment Division
449 Frogtown Road
Akwesasne, NY 13655
By Appointment: 518-358-5937
Akwesasne Library
321 State Route 37
Akwesasne, NY 13655
518-358-2240
USEPA-Region 2
Superfund Records Center
290 Broadway, 1 Floor
New York, NY 10007-1866
212-637-4308
Hours: Mon - Fri, 9:00 A.M. - 5:00 P.M.
As noted above, public meetings and public information
sessions will be held during the comment period to
provide information regarding the Site investigations, the
alternatives considered and the preferred remedy, as well
as to receive public comments. The public meetings will
include a formal presentation by EPA of the preferred
remedy and other cleanup options for the Site. The
information sessions will be less formal, and provide the
public a chance to receive printed information and discuss
the cleanup options with EPA representatives on a one-
on-one basis.
Comments received at the public meetings, as well as
written comments, will be documented in the
Responsiveness Summary Section of the Record of
Decision (ROD), the document that formalizes the
selection of the remedy.
Written comments on this Proposed Plan should be
addressed to:
Young S. Chang, Remedial Project Manager
U.S. Environmental Protection Agency
290 Broadway, 20th Floor
New York, NY 10007-1866
Fax: (212)637-3966
E-mail: Chang.Young@epa.gov
SITE BACKGROUND
Site Description
The Site is located along the northern boundary of New
York State in Massena, and includes the Grasse River
Study Area. The Grasse River Study Area includes
approximately 7.2 miles of the lower Grasse River from the
intersection of the Massena Power Canal (Power Canal)
and the Grasse River, to the confluence of the Grasse and
St. Lawrence Rivers. This 7.2 mile stretch of the Grasse
River is referred to as the "Site" for purposes of this
Proposed Plan. The Grasse River Study Area also
includes the Power Canal, approximately 1.3 miles of the
Lower Grasse River upstream of the confluence of the
Grasse River and the Power Canal, Robinson Creek
(which discharges to the St. Lawrence River) and the
Unnamed Tributary (see Figure 1 Grasse River Study
Area Location Map). The Site poses an increased risk to
human health and the environment due to the presence of
PCB contamination in Grasse River sediment. The Power
Canal is not proposed for remediation in this Proposed
Plan, but will continue to be monitored.
EPA issued an Administrative Order to Alcoa in
September 1989, calling for the investigation of the Alcoa
Study Area to determine the nature and extent of
hazardous substances contamination, develop and screen
alternatives for cleanup, and design and implement a
remedial action to be selected by EPA. For purposes of
the investigation, the river was divided by transects (T)
where each transect represented one-tenth of a mile. In
most of the Site reports the river is divided into 72
transects (T1 through T72). In addition, the Analysis of
Alternatives report separately considered the near shore
and main channel areas of the Grasse River in order to
evaluate remedial alternatives. "Near shore" is defined for
purposes of the Site as the area between the upland and
the location where the gentle slope along the shoreline
meets the steep slope of the main channel side walls. In
general the near shore areas have water depth of five feet
or less during normal summer flow and extend
approximately 25 feet from shore.
The Alcoa Massena-West Plant (Alcoa West Facility) is
located on the north shore of the lower Grasse River, east
of the Power Canal, and is bounded to the north by the St
Lawrence River. Two other large manufacturing facilities,
the Alcoa Massena-East Plant (formerly Reynolds Metals
Company (RMC)) and the former General Motors Central
Foundry Division (GM) plant are located within two miles
east of the confluence of Grasse and St. Lawrence
Rivers.1 The United States maintains that Akwesasne, the
Reynolds Metals Co and General Motors-Central Foundry
Division, including sediment in the St. Lawrence River are
also Superfund sites, in which EPA oversees the cleanup
under CERCLA.
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Mohawk territory of the federally-recognized SRMT, as
described in the 1796 Treaty with the Seven Nations of
Canada, 7 Stat. 55, includes land on both banks of the
Grasse River, as well as land located along the St.
Lawrence River downstream of the Site, together known
as the Indian Meadows.
The Power Canal, constructed between 1898 and 1903,
connects the Massena Intake Dam on the St. Lawrence
River to the former Power Dam at the Power
Canal/Grasse River confluence. The lower Grasse River
was significantly deepened in the early 1900s by the
Aluminum Company of America (now Alcoa, Inc.) to
accommodate discharge from the Power Canal. The
discharge had enough energy to prevent significant
sediment deposition until the 1950s when the Power
Canal was taken out of service; as a result, the river
became much more quiescent and sediments began to
accumulate. The power generation from the Power Canal
stopped operation when the joint U.S. and Canadian
development project of the St. Lawrence River completed
the construction of the Eisenhower Locks System and of
the Moses-Saunders Power Dam (FDR Project), which
began supplying hydroelectric power in 1958.
As a result of the early 1900's deepening of the lower
Grasse River by the Aluminum Company of America, the
physical and ecological characteristics of the lower Grasse
River were altered. The Site has relatively steep side
slopes, a relatively flat bottom, and minimal floodplains. It
is wide (400 to 600 feet) and deep (15 to 25 feet at mid-
channel). The majority of the vegetation in the river
occurs in the near shore zones.
Due to the early dredging of the lower Grasse River and
construction of the FDR Project in the 1950's, the river
within the study area acts as a backwater of the St.
Lawrence River. The velocity of the lower Grasse River is
generally low. Average velocities are estimated to be
about 0.1 to 0.2 feet per second and approximately a
factor of 10 higher during high-flow events. These low
velocities are a consequence of the large cross-sectional
area in comparison to the river flow (average flow is about
1,100 cubic feet per second). When flows are low,
especially in the late spring and summer, the lower Grasse
River has periods of stratification with cooler (more dense)
St. Lawrence River water moving upstream, beneath the
warmer (less dense) Grasse River water. In addition, the
water surface elevations fluctuate (approximately 1 ft) as a
result of water releases within the St. Lawrence Seaway.
Outfalls and tributaries within the study area add an
incremental flow to the river of less than one percent.
The Grasse River is a New York State Class B fresh
surface water which means the best usages for the river
are "primary and secondary contact recreation and fishing.
These waters shall be suitable for fish, shellfish, and
wildlife propagation and survival". (6 NYCRR § 701.7)
The lower Grasse River is used for various recreational
activities such as fishing, boating, and water sports.
However, a fish consumption advisory issued initially in
1990 and updated annually by the New York State
Department of Health (NYSDOH) currently indicates that
no species offish from the lower Grasse River (i.e., mouth
of Grasse River to the Power Canal) should be eaten
because of PCBs in the fish. In the Massena Power Canal
the recommendation is no more than one meal per month
of smallmouth bass for men over 15 years and women
over 50 years, but for children under the age of 15 years
and women up to age 50 years, the advice is eat none.
Grasse River water is also used for domestic purposes
(watering lawns and gardens) and agriculture (irrigating
crops). The Grasse River is not currently used as a public
water supply. There is no commercial transportation use
of the river.
What are PCBs?
The contaminants of concern at the Grasse River Site are
polychlorinated biphenyls, or "PCBs."
Due to their non-flammability, chemical stability, high boiling
point, and electrical insulating properties, PCBs were widely
used in many industrial and commercial applications including
electrical, heat transfer, and hydraulic equipment; as plasticizers
in paints, plastics, and rubber products; in pigments, dyes, and
carbonless copy paper; and many other industrial applications.
The Alcoa West Facility started using PCBs in hydraulic oils for
their fire retardant properties in 1950s after a fatal fire accident at
another Alcoa plant.
PCBs are a group of chemicals consisting of 209 individual
compounds, known as congeners. PCBs were sold in mixtures
containing dozens of congeners. These commercial mixtures
were known in the U.S. as Aroclors.
Although manufacturing of PCBs was banned in 1979, they can
still be released into the environment from poorly maintained
hazardous waste sites that contain PCBs; leaks or releases from
electrical transformers containing PCBs; and disposal of PCB-
containing consumer products into landfills not designed to
handle hazardous waste. PCBs may also be released into the
environment by the burning of some wastes in municipal and
industrial incinerators. At the Site, the ongoing source of PCBs
currently is the PCB-contaminated sediment in the river.
PCBs are classified by EPA as probable human carcinogens and
are linked to other adverse health effects such as developmental
effects, reduced birth weights and reduced ability to fight
infection.
The Grasse River contains a diversity of habitats that
supports a variety of species and is a corridor for species
to travel between the "upper" river (upstream of Massena)
and the St. Lawrence River. The State of New York has
designated the Grasse River as a Significant Coastal Fish
and Wildlife Habitat based on the significance of the
habitats in the river in supporting cool and warm water fish
populations including muskellunge, smallmouth bass,
northern pike, walleye, bullhead, yellow perch, and lake
sturgeon. Observations of both adult and juvenile
muskellunge indicate that the Grasse River likely supports
a spawning population of resident muskellunge and may
serve as a spawning ground for fish residing in the St.
Lawrence River. Multiple studies conducted by academic
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researchers have demonstrated the successful spawning,
juvenile rearing, and adult population of lake sturgeon, a
New York State (NYS)-listed threatened species, in the
Grasse River. Additional state- and federally-listed
species have been documented in or around the Grasse
River. Documented species include the NYS-listed
endangered black tern; NYS-listed threatened bald eagle,
Blanding's turtle, common tern, eastern sand darter,
mooneye, and upland sandpiper; and, NYS-listed species
of special concern osprey and wood turtle. Indiana bats
are both federally- and NYS-listed endangered species
known to exist in St. Lawrence County. Many regulated
(such as sport fish, waterfowl, mink, turtle, birds) species
are known to frequent the impacted areas. The ecological
risk assessment (discussed below) has shown that PCB
contamination poses a risk to the species at the Site, and
that remediation is expected to reduce or eliminate those
risks.
The United States maintains that land reserved to the
SRMT by the 1796 Treaty includes the Indian Meadows
described above. EPA notes, however, that the lands
reserved by the 1796 Treaty are currently in dispute.
Canadian St. Regis Band of Mohawk Indians v. State of
New York, etai, 5:82-cv-783 (N.D.N.Y.). Fishing, hunting,
harvesting and spiritual ceremonies are among the
activities that have been historically and are now
conducted by the SRMT in the lower Grasse River and the
Indian Meadows. The lower Grasse River and the Indian
Meadows are of significant cultural significance to the
SRMT.
Primary land uses in the vicinity of the lower Grasse River,
including the Indian Meadows and the Town of Massena,
include residential, agricultural, industrial, recreational and
tribal activities. It is expected that future uses of these
areas will be similar to the current uses.
Site History
The 2,700-acre Alcoa West Facility is an aluminum
production and fabrication plant that has been in operation
since 1903. The facility is east of the Power Canal and
north of the lower Grasse River. Alcoa's past production
processes generated various waste materials, including
hydraulic oils that contained PCBs. In the 1950s,
coincident with the Power Canal being taken out of
service, Alcoa began using and discharging PCBs through
outfalls to the Grasse River, the Power Canal, and the
Unnamed Tributary. The PCBs accumulated in sediment
that became deposited on top of bedrock in the river. PCB
discharges to the lower Grasse River decreased
significantly after Alcoa stopped using PCBs in the mid-
1970's, and as a result the sediment deposited in the
lower Grasse River since that time has contained lower
PCB concentrations than the sediments that were
deposited before Alcoa stopped using PCBs. Storm water
and treated wastewater from the Alcoa facility are
discharged from permitted outfalls that flow into the lower
Grasse River, the Power Canal, the Unnamed Tributary,
and Robinson Creek. Historically, PCBs also were
released into the river through these outfalls.
As a result of these past disposal practices, NYSDEC
determined that select areas throughout the facility posed
a significant threat to public health and the environment.
Under a 1985 NYSDEC Order, Alcoa conducted a land-
based cleanup program from 1991 to 2001, which
included the elimination or mitigation of sources of
contamination to the Grasse River. Concurrently with the
land-based cleanup program, Alcoa has made several site
improvements in relation to its State Pollution Discharge
Elimination System (SPDES) permit. Some of the upland
based efforts included: remediation of 18 separate
disposal areas, including 37 acres of landfills and 100
acres of lagoons; construction of Alcoa's on-site Secure
Landfill to dispose of excavated material; remediation of
the Unnamed Tributary; and, cleaning of underground
utilities that are part of the storm water/waste water
collection system. Through these efforts, Alcoa has
significantly reduced its discharges and controlled the
upland sources of PCBs to the Site.
The original sources of the PCB contamination in the
lower Grasse River were the discharges from the Alcoa
plant outfalls. The Alcoa West Facility presently has five
permitted outfalls that discharge stormwater and treated
wastewater; three discharge to the lower Grasse River,
one to the Power Canal, and one to Robinson Creek.
Outfall 001 is the main plant outfall. PCB discharges from
this outfall have declined from 60 grams per day
(grams/day) in 1990 to 1.9 grams/day in 1999 to 0.8
grams/day in 2003; since 2004, PCBs have not been
detected in the outfall samples with the exception of a
one-time detection of 0.08 micrograms per liter in 2009.
Although plant facility discharges were important
contributors to lower Grasse River PCBs in the past,
upland remediation efforts completed in 2001 have
significantly reduced PCB discharges to the river.
However, small but measurable discharges under Alcoa's
SPDES permit continued to occur until 2003 when Alcoa
conducted additional work to further reduce the PCB
discharges from Outfall 001 under a NYSDEC order. The
PCB-containing sediments in Unnamed Tributary were
removed in 1998, significantly decreasing continued
contaminant inputs from this historical source of PCBs to
the lower Grasse River. PCB data collected from
several shallow and deep groundwater monitoring wells,
coupled with the limited discharge rate, indicate that
groundwater is not a significant source of PCBs to the
lower Grasse River.
Alcoa's early investigation of the Site under the terms of
the 1989 EPA Administrative Order identified significantly
elevated PCB concentrations in an area of Grasse River
sediment located adjacent to wastewater Outfall 001. As
a result, EPA amended the Administrative Order in May
1995 to require Alcoa to conduct a Non-Time-Critical
Removal Action (NTCRA) to address the PCB-
contaminated sediment within a one-acre area around the
outfall (see Figure 2 Locations of Lower Grasse River
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Pilot/Demonstration Projects). Alcoa conducted the
NTCRA between July and September, 1995. Hydraulic
dredging was used to remove most of the sediments,
which were dewatered and disposed of in Alcoa's TSCA
and RCRA-permitted, double-lined, on-site landfill.
Approximately 3,000 cubic yards (cy) of sediment,
boulders and debris were removed, which represented
about 20 percent (8,000 pounds (lbs)) of the total PCB
mass in the river. However, it was not possible to remove
all of the PCB-contaminated sediments in this area, due
mainly to the presence of cobbles and boulders on the
river bottom.
Because in-place capping of contaminated sediments has
been one remedial technology under consideration, Alcoa
conducted a capping pilot study (CPS) between July and
October 2001. The study involved the placement of clean
cap material over a seven-acre area in a 750-foot stretch
of the river about one mile downstream of Outfall 001 (see
Figure 2). Several different cap designs with various cap
materials and placement techniques were used. The
capping pilot study demonstrated that a cap could be
constructed successfully in the lower Grasse River without
significant mixing of the cap material with the underlying
sediment or causing PCB releases to the water column.
However, the targeted cap thickness could not always be
achieved on the steep side slopes in the area of the pilot
study. Monitoring after the first year showed that the cap
thickness remained stable.
During post-placement monitoring of the CPS, it was
discovered that an "ice jam" event in 2003 scoured
sediment in the river to a depth of up to four feet, including
erosion of parts of the cap material and underlying
contaminated sediment. The ice jam was an accumulation
of ice in the river channel that caused higher flow rates
under the ice jam toe, which resulted in some localized
scour of the river bottom. Prior to the 2003 ice jam event,
the occurrence of scour from ice jams was not known to
the project team and therefore the CPS had not been
designed to withstand such great forces. As a result,
further investigation was initiated in 2003, which revealed
that severe ice jam events can cause scouring of the river
bottom sediments in the upper 1.8 miles of the lower river
(upstream ofT19). Through several lines of evidence, the
project team discovered that ice jam events severe
enough to cause measureable scour have occurred in the
lower Grasse River at least four times over the past 40 to
50 years.
Based on an updated conceptual site model, Alcoa
performed a Remedial Options Pilot Study (ROPS) in
2005. The ROPS (see Figure 2) included a one-acre
armored cap, 24,400 cy (approximate) of main channel
dredging, 1,600 cy of near shore dredging/backfilling to
grade, and one-half of acre of thin-layer (3 to 6 inches)
capping in the southern near shore area. Extensive
monitoring of all components was conducted during and
following implementation. The study revealed that
dredging in the main channel of the Site was difficult due
to the presence of cobbles and boulders and irregular river
bottom conditions. It also revealed that the typical main
channel sediment profile contains the highest PCB
concentrations at the lowest depth of the sediment
column. This most highly contaminated sediment is
present over hard bottom materials such as bedrock,
glacial till, and/or marine clay which prevent over-
dredging, thereby resulting in PCB residuals with high
PCB concentrations that require capping even after an
extensive dredging effort. However, these conditions were
not present in the northern near shore area, where
dredging was much more successful because conditions
allowed for more complete removal of contaminated
sediments. Placement of a cap by use of thin layered
capping over part of the southern near shore was
successfully demonstrated. However, post monitoring did
discover some areas where the thin layer cap material
was absent due to lack of cap installation. A 25-inch
armored cap over an acre area consisting of sand/topsoil,
gravel, and armor stone was successfully placed in the
main channel (and is still intact).
In the fall of 2006, an activated carbon pilot study (ACPS)
was conducted in a 0.5-acre area to evaluate the ability to
deliver activated carbon to in-river sediments and the
effectiveness of activated carbon in reducing the
bioavailability of PCBs to biota. The ACPS demonstrated
that activated carbon can be successfully applied into the
river sediments. No measurable changes in the water
column PCBs were observed adjacent to or downstream of
the pilot area, with only minor increases in total suspended
solids (TSS) measured. Post-construction monitoring
revealed that the placed carbon is stable in the fine
sediments.
Alcoa, in coordination with EPA, initiated a community
involvement program in 2001 in order to communicate with
the public about the project status. As part of the program
a Community Advisory Panel, composed of community
members and local, state, and federal government
representatives, was formed to serve as a forum for the
exchange of project-related information and to create
opportunities for the community to express its interests and
concerns regarding the Site. Alcoa and EPA conducted
several public meetings and availability sessions prior to
the implementation of various pilot and demonstration
projects.
RESULTS OF THE REMEDIAL INVESTIGATION
Summary of Sampling Results and Other
Investigations
For the investigation of the Site, Alcoa has conducted
numerous studies, summarized in the CCLGR Report of
April 2001 and Addendum to the CCLGR of April 2009
(collectively referred to as the "Final CCLGR Report").
The investigations included sediment sampling, river flow
and water quality studies, fish and biota sampling, a
habitat survey, sediment erosion studies, laboratory PCB
studies, source investigations, and studies regarding ice
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jam and scour. Data were obtained from the following
major study programs: (1) an initial River and Sediment
Investigation (1991-1994); (2) the NTCRA in 1995 as
mentioned above; (3) a Supplemental Remedial Studies
program (1995-present); (4) Sediment Probing Programs
in 1992, 1998, and 2001; (5) Supplemental Sediment
Sampling (2000-2001, and 2006-2007); (6) the CPS of
2001 as mentioned above; (7) the River Ice Evaluation of
2003-2004; (8) Bathymetric Surveys of 2003 to 2005; (9)
the ROPS of 2005 as mentioned above; (10) River Ice
Monitoring (2004 to present); (11) the Ice Control
Structures Evaluation (2005-2009); (12) the Activated
Carbon Pilot Study (2006); (13) the Ice Breaking
Demonstration Project (2007); and (14) the Near Shore
Sampling Program (2010). Additional investigations and
modeling were conducted to study the fate and transport
of the PCBs at the Site. As a result of these
investigations, pilots, and demonstration projects,
approximately 15 acres of river sediment have been
capped and 29,000 cy of PCB-contaminated sediment and
15,200 pounds of PCB mass have been removed from the
river. Based on the results of the studies listed above, the
7.2 miles of the lower Grasse River have been determined
to be the area of primary concern. Summaries of some of
the major findings of these studies are presented in this
Plan. More detail can be found in the Final CCLGR
Report, the Analysis of Alternatives Report and other
documents in the administrative record file.
Sediment
Over 5,000 sediment samples have been collected at the
Site to determine the nature and extent of PCB-
contaminated sediment.
Deposits of sediment exist on most of the bottom of the
Site. In most areas of the Site, soft sediment deposits are
underlain by bedrock or glacial till. These sediment
deposits typically range from 0 to 5 feet in depth, with
isolated pockets up to 10 feet deep. The upstream half
mile of the 7.2 mile Site (in T1-T5) has a thin veneer of
sand and gravel over bedrock. PCB concentrations in the
sediment core data collected from the main channel of the
river from 1991 through 2007 indicate that the maximum
PCB concentrations tend to be at depth. The sediment
data collected from the near shore (2010) indicated that
the peak sediment PCB concentrations above 1 mg/kg
generally occur within the top 1 to 1.5 feet of sediment.
Based on the investigations, it is estimated that
approximately 1.7 million cy of sediment are contaminated
with measurable PCBs over a 325 acre area.
The main channel in the T1 to T21 transects of the river
are prone to potential scouring of sediment from severe
ice jam events, which can mobilize PCBs.2 The estimated
2 Ice jam-related scour is primarily of concern from T1 to T19.
For purposes of developing remedial alternatives, however,
T21 was used to define the downstream extent of the
Grasse River that is potentially subject to ice jam-related
scour because a contiguous sediment deposit runs from T19
volume of contaminated sediment in the main channel is
approximately 330,000 cy over a 59-acre area, with PCB
concentrations ranging from non-detect (ND) to 3,106
mg/kg, with an average concentration of 82 mg/kg.
Sampling data to date have been inconclusive in
demonstrating a lack of scouring in the near shore zone
and scouring in the upper two miles of the near shore is
possible in the future. The near shore from T1 to T21
contains approximately 25,900 cy of contaminated
sediment over a 10-acre area with PCB concentrations
ranging from ND to 3,070 mg/kg and an average
concentration of 68 mg/kg.
For the remainder of the Site (T21 to T72), the
investigations concluded that the contaminated sediment
in the main channel and near shore is stable even under
extreme flow conditions. Mathematical modeling
assuming maximum erosion indicated that a 100-year
flood event would result in about 0.9 cm (0.35 inch) net
erosion, and a 500-year flood event would result in
between 1 and 1.5 cm (0.39 to 0.59 inches) of net erosion.
It is primarily the surface sediment in this region that has
the greatest potential impact on the biota. The surface
sediment was defined for the purposes of the Analysis of
Alternatives Report as the top 6 inches in the main
channel and the top 12 inches in the near shore sediment.
The estimated contaminated sediment in the main channel
from T21 to T72 is approximately 1.2 million cy over a
225-acre (approximate) area with PCB concentrations
ranging from ND to 1,063 mg/kg and an average
concentration of 57 mg/kg. The concentration of sediment
in the top 6 inches ranges from ND to 558 mg/kg, with an
average concentration of 22 mg/kg. The contaminated
sediment in the near shore from T21 to T72 is
approximately 82,800 cy over a 31-acre area with PCB
concentrations ranging from ND to 313 mg/kg and an
average of 14 mg/kg. The sediment concentrations in the
top 12 inches range from ND to 167 mg/kg with an
average concentration of 8 mg/kg.
Water Column
The water column has been monitored for PCBs at
several transects (see Figure 3, Water Column
Monitoring Locations). Since the mid-1990s, over 2,000
water column samples have been collected. PCB
concentrations in the water column exhibit distinct
seasonal patterns, with concentrations typically being
highest in the summer and lowest in the late fall (note
that water column data are not collected in the winter
to T21, and any remedy would be expected to address the
contiguous deposit as a whole. T21 is included in both the
upstream (T1-T21) and downstream (T21-T72) reaches
because the contiguous sediment deposit does not cover all
of T21, and it therefore may be necessary to apply the
upstream and downstream cleanup criteria to separate
areas within T21, depending on the specific sediment
characteristics in a particular location. Application of the
cleanup criteria in T21 will be determined during remedial
design.
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months when the river is covered with ice).
The data collected upstream of the Site at the Main
Street Bridge (WC-MSB) between 2006 and 2011
indicate average PCB concentrations of about 0.2
nanograms per liter (ng/L) (concentrations range from
non-detect to 3 ng/L). The Power Canal also releases a
small flow of water to the lower Grasse River upstream of
the Alcoa West Facility. The water column PCB
concentrations in the Power Canal averaged 7.9 ng/L in
1998 and 1.9 ng/L in 2002.
Within the Site, at water column monitoring station
WC007 near T16, the average summertime PCB
concentrations have declined from approximately 115
ng/L in 1996 to about 20 ng/L in 2007. At water column
monitoring station WC131/WC007A between T22 and
T23, PCB concentrations declined from approximately
200 ng/L in 1996 to about 8 ng/L in 2011. At WC011
near T38, PCB concentrations declined from 130 ng/L in
1997 to approximately 12 ng/L in 2011.
Though the PCB concentrations in the water column
have dramatically decreased over the years due mostly
to upland source controls, and outfall and tributary
remediation, and partially due to natural sedimentation
and in-river pilot work and demonstrations, the data also
indicate that PCBs in sediment pore water3 at the Site are
a persistent, widespread, and diffuse source of PCBs to
the water column.
Fish
PCB concentrations observed in fish are a result of
exposure to PCBs in water and surface sediment,
through an aquatic food chain or a benthic food chain,
respectively.
Alcoa has collected more than 3,000 fish samples
consisting of three species (smallmouth bass, brown
bullhead, and spot tail shiner) over a period of 17 years.
The fish are collected in the fall of each year in three
different stretches (Upper, Middle and Lower) of the Site
and in the background stretch of the Grasse River. PCBs
have rarely been detected in any of the three fish species
collected from the background stretch. Within the Site,
PCBs are consistently found in fish tissue although
concentrations have decreased since the early 1990s
mostly due to various remedial actions that have
occurred since that time, although the rate of decline has
decreased since 2001. The average concentration of
PCB concentrations in smallmouth bass fillets have
decreased from 17 mg/kg (ranging from 1.4 to 67 mg/kg)
in 1993 to about 0.7 mg/kg (ranging from non-detect to 2
ppm) in 2011. Average PCB concentrations in brown
bullhead fillets have also decreased from 8.1 mg/kg (with
a range of 0.9 to 35 mg/kg) in 1993 to 0.8 mg/kg (ranging
Pore water is the subsurface water in the sediment interstice
or in between the pores of the sediment grains.
WHAT IS RISK AND HOW IS IT CALCULATED?
A Superfund baseline human health risk assessment is an
analysis of the potential adverse health effects caused by
hazardous substance releases from a site in the absence of any
actions to control or mitigate these under current- and future-land
uses. A four-step process is utilized for assessing site-related
human health risks for reasonable maximum exposure scenarios.
Hazard Identification: In this step, the chemicals of potential
concern at the site in various media (i.e., soil, groundwater,
surface water, and air) are identified based on such factors as
toxicity, frequency of occurrence, and fate and transport of the
contaminants in the environment, concentrations of the
contaminants in specific media, mobility, persistence, and
bioaccumulation.
Exposure Assessment: In this step, the different exposure
pathways through which people might be exposed to the
contaminants in air, water, soil, etc. identified in the previous step
are evaluated. Examples of exposure pathways include incidental
ingestion of and dermal contact with contaminated soil and
ingestion of and dermal contact with contaminated groundwater.
Factors relating to the exposure assessment include, but are not
limited to, the concentrations in specific media that people might
be exposed to and the frequency and duration of that exposure.
Using these factors, a "reasonable maximum exposure" (RME)
scenario, which portrays the highest level of human exposure that
could reasonably be expected to occur, is calculated.
Toxicity Assessment: In this step, the types of adverse health
effects associated with chemical exposures and the relationship
between magnitude of exposure (dose) and severity of adverse
effects (response) are determined. Potential health effects are
chemical-specific and may include the risk of developing cancer
over a lifetime or other non-cancer health hazards, such as
changes in the normal functions of organs within the body (e.g.,
changes in the effectiveness of the immune system). Some
chemicals are capable of causing both cancer and non-cancer
health hazards.
Risk Characterization: This step summarizes and combines
outputs of the exposure and toxicity assessments to provide a
quantitative assessment of site risks for all chemicals of
potential concern (COPCs). Exposures are evaluated based on
the potential risk of developing cancer and the potential for non-
cancer health hazards. The likelihood of an individual developing
cancer is expressed as a probability. For example, a 10"4 cancer
risk means a "one-in-ten-thousand excess cancer risk"; or one
additional cancer may be seen in a population of 10,000 people
as a result of exposure to site contaminants under the conditions
identified in the Exposure Assessment. Current Superfund
regulations for exposures identify the range for determining
whether remedial action is necessary as an individual excess
lifetime cancer risk of 10"4 to 10"6, corresponding to a
one-in-ten-thousand to a one-in-a-million excess cancer risk. For
non-cancer health effects, a "hazard index" (HI) is calculated. An
HI represents the sum of the individual exposure levels compared
to their corresponding reference doses (RfDs). The key concept
for a non-cancer HI is that a threshold (measured as an HI of less
than or equal to 1) exists below which non-cancer health hazards
are not expected to occur. The goal of protection is 10"6 for
cancer risk and an HI of 1 for a non-cancer health hazard.
Chemicals that exceed a 10"4 cancer risk or an HI of 1 are typically
those that will require remedial action at a site and are referred to
as COCs in the ROD.
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from non-detect to 2 mg/kg) in 2011. PCB levels in
whole-body spottail shiner collected from areas that have
undergone the most substantial remediation including
from near Outfall 001 and near the Unnamed Tributary
decreased from an average of 5.1 mg/kg (with a range of
3 to 5.7 mg/kg) in 1998/1999 to about an average of 1.9
mg/kg (with a range of 1.1 to 3) in 2011. All fish tissue
data provided above are on a wet weight basis. In more
recent years the amount of lipids in fish tissue samples
has decreased, potentially due to analytical changes,
providing some uncertainty to the PCB tissue
concentrations.
Because PCBs tend to accumulate in fatty tissues, it is
also important to examine PCB concentrations in fish on
a lipid (fat) basis for trend analysis. Similar decreases to
wet weight fish tissue concentrations discussed above
have also been observed in the lipid basis data. Overall,
lipid-normalized PCB concentrations in both smallmouth
bass and brown bullhead have decreased by more than
90 percent since the mid-1990s. By comparison, lipid-
normalized PCB concentrations in young-of-year spottail
shiner have decreased by 55 to 60 percent since the mid-
1990s. Lipid-based concentrations would also be
affected by analytical uncertainties. The remediation of
the Alcoa West Plant through the NYSDEC Order for
land-based cleanup and the reduction of PCBs in the
outfall discharges have provided the greatest contribution
towards the decrease of PCB concentrations in fish.
However, a fish consumption advisory issued by the
NYSDOH currently indicates that no species of fish from
the lower Grasse River should be eaten.
SUMMARY OF SITE RISKS
Based upon the results of the Final CCLGR, a baseline
risk assessment was conducted for the Site to estimate
the risks associated with current and future site conditions.
A baseline risk assessment is an analysis of the potential
adverse human health and ecological effects caused by
hazardous substance releases from a site assuming no
further actions to control or mitigate exposure to these
hazardous substances are taken.
Human Health Risk Assessment
As part of the investigation, a Baseline Human Health
Risk Assessment (BHHRA) was conducted to estimate
the risks and hazards associated with the current and
future effects of contaminants on human health. The
BHHRA includes the 1993 Revised Risk Assessment
ALCOA Study Area (TRC); the 2002 Update to the 1993
Revised Risk Assessment (Alcoa); and the 2012
Addendum4 to assess non-PCB chemical contaminants.
4 The Addendum was conducted to take into consideration
changes in toxicity factors (reference doses and cancer
slope factors) that were identified by USEPA in 2009 and
additional updates in 2010. The Addendum can be found in
the Appendix G of the 2012 Analysis of Alternatives Report.
The BHHRA evaluated exposure to sediment, surface
water and fish at the Site. The reaches that represent
background conditions (i.e. Reaches 1 and 2) located
upstream of the Alcoa West Facility were also evaluated.
The primary COPCs for the Site are PCBs, with exposure
to PCBs via consumption of fish from the lower Grasse
River posing the greatest risk.
A four-step human health risk assessment process was
used for assessing site-related cancer risks and non-
cancer health hazards. The four-step process comprises:
Hazard Identification of COPCs, Exposure Assessment,
Toxicity Assessment, and Risk Characterization (see
"What Is Risk and How Is It Calculated" box on the
previous page).
The BHHRA evaluated potential risks to receptors under
current and future land use scenarios. The current
NYSDOH Grasse River fish consumption advisory was
not considered in the assessment since the BHHRA does
not consider such an institutional control in the definition
of potential exposure scenarios.
Consistent with EPA policy and guidance, cancer risks
and non-cancer health hazards were evaluated for the
reasonably maximally exposed (RME) individual and the
central tendency exposed (CTE) individual. The RME is
considered the maximum exposure that is reasonably
estimated to occur at a site and is not a worst-case
scenario. The CTE, which is the average exposure to an
individual, is also provided for further characterization.
Potential current and future receptors that may be
exposed to the Grasse River include: adults from the
local population and the Mohawk Nation who may fish
and consume their catch; recreational users of the River
including adults, adolescents, and young children who
may camp near or swim in the River; and Mohawk adult
anglers who may contact sediments when pulling gillnets
from the water. Routes of exposure under current/future
conditions include: consumption of fish and incidental
ingestion and dermal contact with sediments and surface
water.
In furtherance of EPA's current Environmental Justice
policy, known as EJ 2014, Region 2 has identified
Akwesasne, the territory of the SRMT, as a Potential
Environmental Justice Community. Members of the
SRMT have been burdened by the environmental and
health impacts of pollution in the local river systems,
including the Grasse River, due primarily to the
consumption of local fish contaminated with PCBs.
Members of the SRMT consume such fish at higher rates
than the general population. The potential for adverse
health impacts from consumption of fish contaminated
with PCBs is well documented.
The BHHRA evaluated the following specific reaches of
the River (see Figure 4):
• Reaches 1 and 2, located upstream of the Alcoa
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West Facility, for exposures to sediment and
surface water by swimmers and consumption of
fish by local anglers;
• Reaches 4 through 8, located adjacent to and/or
downstream of the Alcoa West Facility, for
exposures to sediment and surface water by
swimmers and consumption of fish by local
anglers; and,
• Reaches 7 and 8, located further downstream, for
consumption offish by Mohawk anglers.
Reach 3 is located in the Power Canal (Reach 3) and was
analyzed in the 1993 Revised Risk Assessment ALCOA
Study Area. However, as mentioned above, the Power
Canal is not within the scope of this Proposed Plan but will
continue to be monitored.
Exposure point concentrations in fish, sediment and
surface water were estimated using either the maximum
detected concentration of a contaminant or the 95%,
97.5% or 99% upper-confidence limit (UCL) of the
average concentration. Chronic daily intakes were
calculated based on exposures to the RME individual.
The RME is intended to represent a conservative
exposure scenario that is still within the range of possible
exposures. A CTE or average exposure is also provided.
A complete evaluation of all exposure scenarios can be
found in the BHHRA.
A summary of PCB risks and hazards to anglers
consuming fish, organized by reach, is as follows:
• Reaches 1 and 2. The risk for the RME
individual was 3 x 10"5 (3 in 100,000) and is
within the acceptable risk range. The risks to the
local adult angler (person fishing) in Reaches 1
and 2 were 3 x 10" (3 in 10,000,000) for the CTE
individual and are less than the risk range.
The non-cancer Hazard Index (HI) for the RME
individual is 1.6 and the CTE individual is 0.1.
The non-cancer HI for the RME individual is
above the goal of protection. The non-cancer HI
of 1 for the CTE individual is within the goal of
protection.
• Reaches 4 through 8. The risks to the local adult
angler fishing in Reaches 4 through 8 were 3 x
10" (3 in 1,000) for the RME adult individual and
3x10"5 for the CTE individual. The risks to the
RME individual exceeded the risk range and for
the CTE individual were within the acceptable
risk range.
The non-cancer HI for the RME individual is 160
and for the CTE individual is 9.9. The non-
cancer HI for the RME and CTE individual was
above the goal of protection.
• Reaches 7 and 8. The risks to the local adult
Mohawk angler fishing in Reaches 7 and 8 were
2 x 10"2 (2 in 100) for the RME adult individual
and 7 x 10"4 (7 in 10,000) for the CTE individual.
The risks to the CTE and RME individual are
above the acceptable risk range.
The non-cancer HI for the RME individual is 615
and for the CTE individual is 67. The non-cancer
HI for the RME and CTE individual is above the
goal of protection.
The non-cancer health hazards for a young child (1 to 6
years of age) would be approximately 1.6 times higher
than that of an adult assuming an ingestion rate of 1/3 of
that of the adults for all stretches of the River. The non-
cancer hazards for the adolescent (7 to 18 years) would
be approximately 1.1 to 1.2 times higher than the adult
Hazard Index assuming an ingestion rate of 2/3 that of
the adult for all stretches of the River. The non-cancer
hazards in all reaches for the adolescent and young child
are above the goal of protection.
The cancer risks to the young child and adolescent are
lower than those of the adult based on differences in
ingestion rate, bodyweight, and exposure duration. The
calculated risks for the young child and adolescent in
Reaches 4 through 8, including a separate analysis for
Reaches 7 and 8, remain above the risk range of 10"4 to
10"6.
A summary of risks and hazards to recreational users of
the lower Grasse River exposed to sediment and surface
water are organized by reach as follows:
• Reaches 4-8. The risks to the local recreational
user of the River in Reaches 4 through 8 were 3
x 10"7 for the adult, 1 x 10"6 for the adolescent;
and 3 x 10"7 for the child. The risks to the RME
individual were 2 x 10"6 for the adult, 1 x 10"5 for
the adolescent, and 4 x 10"6 for the child. The
total risks to the RME and CTE individuals were
within the risk range.
The non-cancer HI for the recreational user of the
River in Reaches 4 to 8 were 0.2 for the adult,
0.6 for the adolescent, and 0.4 for the child. The
non-cancer HI for the RME individual was 0.43
for the adult, 1.6 for the adolescent, and 1.1 for
the child. The non-cancer HI for the CTE
individuals was within the goal of protection. The
hazards to the RME individual were above the
goal of protection for the adolescent and child.
The HI for the adult was within the goal of
protection.
• Reaches 7 and 8. The risks to the Mohawk
angler exposed to sediment through the use of
gill nets in Reaches 7 and 8 were 3 x 10"5 for
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RME individual and within the risk range. The
risks for the CTE adult were 4 x 10~6 and within
the risk range.
The non-cancer HI for the recreational user of the
River in Reaches 7 and 8 was 0.4 for the adult
CTE individual and was within the goal of
protection. The non-cancer HI for the RME
individual was 0.8 for the adult and was within the
goal of protection.
The re-evaluation of the cancer risks and non-cancer HI
associated with other contaminants in fish, sediments,
and surface water is provided in the 2010 Addendum to
the BHHRA. This Addendum provides updated
calculations of risks and hazards for non-PCB COPCs at
the Site that were identified in the 1993 Risk Assessment.
The revised estimates are based on changes in the
toxicity factors since the original risk assessment of 1993.
Risks from dioxin toxic equivalents (TEQ) are within the
upper bounds of the risk range and these exposures
occurred in Reaches 4 through 8. The cancer risks
associated with non-PCB COPCs from ingestion of fish
within Reaches 4 through 8 were 1.4 x 10~4. The non-
cancer HI for the adult angler within Reach 4 to 8 was 3,
which exceeds the goal of protection. Both risks and
hazards related to dioxin TEQ are significantly less than
those posed by PCBs.
Ecological Risk Assessment
This section summarizes the results of the Ecological
Risk Assessment (ERA) process and is based on the July
2010 Ecological Risk Analysis Update (ERAU) report
(Lockheed-Martin/SRC). The July 2010 report combines
into a single report the ERA that was conducted for the
Lower Grasse River Study Area in 1993 (TRC
Environmental Corporation) and the additional ecological
risk analysis incorporating data for sediment, surface
water, river bank sediment, whole body fish tissue, and
invertebrate tissue data collected through 2008,
immediately prior to the commencement of the ERA in
2009.
The process used for assessing site-related ecological
risks includes:
Problem Formulation - a qualitative evaluation of
contaminant release, migration, and fate; identification of
COCs, receptors, exposure pathways, and known
ecological effects of the contaminants; and selection of
endpoints for further study;
Exposure Assessment - a quantitative evaluation of
contaminant release, migration, and fate; characterization
of exposure pathways and receptors; and measurement
or estimation of exposure point concentrations;
Ecological Effects Assessment - literature reviews, field
studies, and toxicity tests, linking contaminant
concentrations to effects on ecological receptors; and
Risk Characterization - measurement or estimation of
both current and future adverse effects.
This process is described in Ecological Risk Assessment
Guidance for Superfund: Process for Designing and
Conducting Ecological Risk Assessments (EPA, 1997).
The lower Grasse River is home to a wide variety of
aquatic and riparian habitats and is located within the St.
Lawrence Plain ecological zone of New York State. This
zone can be characterized as a gently rolling agricultural
landscape interspersed with small woodland areas. A
habitat assessment to determine the site-specific habitats
and species that may be affected by the alternatives has
not yet been completed however will be performed during
the design. The Grasse River lies within the Upper Saint
Lawrence River watershed. It is a large, medium-gradient
river characterized by riffles and pools flowing over
bedrock, cobble, and gravel substrate. In 1994, the New
York Department of State's Division of Coastal
Resources designated the Grasse River from its
confluence with the St. Lawrence River to the Madrid
Dam a significant coastal fish and wildlife habitat
(NYDOS 1994). The assessment endpoints that were
selected for the Grasse River ERA are survival, growth,
and reproduction of aquatic organisms, piscivorous (fish-
eating) bird and mammal populations, and insectivorous
(insect-eating) mammal populations.
PCBs, including dioxin-like PCBs, are the contaminants
of concern for the ERA based on the results of earlier
investigations. Ecological exposure to PCBs is primarily
an issue of bioaccumulation through the food chain. Risk
to fish was evaluated by comparing measured
concentrations of PCBs and dioxin-like PCB congeners in
fish tissue with concentrations reported in published
studies that identified adverse effects. Food chain
models were used to calculate risk to upper trophic level
piscivorous birds (belted kingfisher), mammals (mink),
and insectivorous mammals (little brown bat) from
consumption offish and aquatic invertebrates.
For the food chain estimates of risks, the complete
exposure pathways and exposure parameters (e.g., body
weight, prey ingestion rate, home range) used to
calculate the concentrations or dietary doses to which the
receptors of concern may be exposed were obtained
from EPA sources and the scientific literature. Site-
specific PCB concentrations in fish, invertebrates, and
sediment were used to model the food-chain risks.
Measures of toxicological effects were selected based on
Lowest Observed Adverse Effects Levels (LOAELs)
and/or No Observed Adverse Effects Levels (NOAELs)
from laboratory and/or field-based studies as reported in
the scientific literature. Reproductive effects were
generally the most sensitive endpoints for animals
exposed to PCBs.
Conclusions from the 2010 ERAU are provided below.
For purposes of the updated risk analysis, current data
10
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were defined as data collected from 2003 to 2008 in the
T1 to T19 transects and data collected from 2000 to 2008
in the T20 to T72 transects. In the T1 to T19 transects,
data collected prior to the ice jam scour of 2003 were not
included in the analysis. Additional details are provided
in the final ERAU (EPA, July 2010).
The Ecological Risk Assessment indicates that aquatic
organisms and piscivorous and insectivorous receptors
are at risk from adverse reproductive, growth, or survival
effects from exposure to PCBs in sediments and/or prey.
The major findings of the ERAU include:
Sediment: Available information indicates
unacceptable risks to aquatic organisms from
exposure to the mean concentrations of
Aroclors 1016, 1221, 1232, 1242, 1248,
1254, and 1260, total PCBs, and dioxin-like
PCB congeners.
Surface water: Available information
indicates unacceptable risk to aquatic
organisms from exposure to the mean
measured concentrations of total PCBs and
dioxin-like PCB congeners.
Fish: Available information indicates
unacceptable risks for adverse ecological
effects (i.e., reduced survival, growth and/or
reproduction) from exposure of fish to total
PCBs and dioxin-like PCB congeners.
• Food chain: Unacceptable risks were
estimated for piscivorous birds and mammals
from dietary exposure to Aroclors 1232, 1248,
1254, and 1260, and total PCBs; and to
insectivorous mammals from dietary exposure
to Aroclors 1248 and 1260 and total PCBs.
Based upon the results of the investigations reported in
the CCLGR and the Addendum CCLGR and the risk
assessments, EPA has determined that the preferred
alternative identified in this Proposed Plan or one of the
other active measures considered and identified in this
Proposed Plan is necessary to protect public health,
welfare, or the environment from actual or threatened
releases of hazardous substances into the environment.
SCOPE AND ROLE OF ACTION
The primary objective of this action is to address the PCB-
contaminated sediments in the lower Grasse River.
Removal, capping, and natural recovery5 of these
sediments will reduce PCB concentrations in biota
including fish tissue, thereby reducing potential human
health and ecological risks. In addition, remediation of the
The current average rate of sedimentation in the main
channel is from 0.2 to 0.7 centimeters per year.
sediment will control this source of PCBs to the water
column which contributes to fish tissue concentrations,
and transports PCBs downstream. An important early
step in sediment cleanup is source control. Upland source
control for the Site has been completed, as mentioned
above in the Site History section. The Power Canal is not
within the scope of this Proposed Plan but will continue to
be monitored.
Alcoa investigated potential PCB sources to the river,
including sources upstream of the Site that enter the
Upper Grasse River, plant outfalls, the Unnamed
Tributary, groundwater discharges to the river, and river
sediments. Two potential upstream sources exist: the
Grasse River upstream of the Massena Dam and the
Power Canal. Studies indicate that the PCB flux from
these upstream sources currently contributes a very
small fraction of the total PCBs in the lower Grasse River.
However, after cleanup of the lower Grasse River, these
upstream sources combined with the influence of residual
concentrations will influence the ability of all remedial
alternatives to meet two water standards.
Although plant facility discharges were important
contributors to lower Grasse River PCBs in the past,
upland remediation efforts completed in 2001 have
significantly reduced PCB discharges to the river.
However, small but measurable discharges under Alcoa's
SPDES permit continued to occur until 2003 when Alcoa
conducted additional work to further reduce the PCB
discharges from Outfall 001 under a NYSDEC order. The
PCB-containing sediments in Unnamed Tributary were
removed in 1998, significantly decreasing continued
contaminant inputs from this historical source of PCBs to
the lower Grasse River. PCB data collected from
several shallow and deep groundwater monitoring wells,
coupled with the limited discharge rate, indicate that
groundwater is not a significant source of PCBs to the
lower Grasse River.
Buried sediments with high PCB concentrations in the
upper two miles of the main channel can be scoured
during severe ice jam events. The 2003 ice jam event,
which appears to have been the most severe jam in the
past 50 years, had caused scour in approximately 15
percent of this region. PCB concentrations in surface
sediments of the Site are broadly and variably distributed.
This distribution pattern of surface sediment PCBs and
monitoring data suggest that the surface sediment source
is diffuse and that the widespread diffusive flux from the
surface sediments is currently the primary source of
PCBs to the water column and biota. Therefore, a large
area of the river bottom must be addressed for any
remedy to be effective.
The PCBs in the surface and subsurface sediment in the
near shore areas are expected to present a greater direct
and indirect exposure potential to affected fish and
wildlife than the sediments in the main channel. The near
shore sediments are expected to include a greater
density of rooted vegetation, use by semi-aquatic species
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such as mink and wading birds, and a greater variety of
habitat types. These uses are likely to result in greater
penetration of the sediments by biological activity, a
greater variety of species sensitivity, and an exposure
potential to a greater number of species. Additionally,
there is expected to be a greater impact from above
grade placement of capping materials resulting in
significant or complete filling of the water column,
preventing recovery of the affected habitats.
REMEDIAL ACTION OBJECTIVES
Remedial action objectives are specific goals to protect
human health and the environment. These objectives are
based on available information and standards, such as
applicable or relevant and appropriate requirements
(ARARs), to-be-considered (TBC) guidance, and site-
specific risk-based levels established using the risk
assessments. There are no federal or New York State
cleanup standards for PCB-contamination in sediment.
The following remedial action objectives have been
established for the Site:
1. Reduce the cancer risks and non-cancer health
hazards for people eating fish from the Grasse
River by reducing the concentration of PCBs in
fish. The risk-based preliminary remediation goal
(PRG) for the protection of human health is 0.05
mg/kg (wet weight) PCBs in fish fillet based on
non-cancer hazard indices for the RME adult fish
consumption rate of one half-pound meal per
week (equivalent to 32 grams per day, this level is
protective of cancer risks as well). The risk-based
PRG for the protection of Mohawk human health
is 0.01 mg/kg PCBs in fish fillet based on non-
cancer hazard indices for the adult tribal
subsistence population with a consumption rate of
142 grams per day. Other interim target
concentrations are 0.26 mg/kg PCBs in fish fillet,
which is protective for cancer risks for the adult
avid angler at a fish consumption rate of one half-
pound meal per month and 0.36 mg/kg PCBs in
fish fillet, which is protective of the CT or average
angler, who consumes one half-pound meal every
two months.
2. Reduce the risks to ecological receptors by
reducing the concentration of PCBs in fish. The
risk-based PRG for the ecological exposure
pathway is a range in whole-body fish (brown
bullhead and spottail shiner) PCB concentrations
of 0.22 to 0.44 mg/kg (wet weight) based on the
NOAEL and the LOAEL for consumption of fish by
the mink. The ecological PRG is considered
protective of all the ecological receptors evaluated
because it was developed for the mink, the
piscivorous mammal calculated to be at greatest
risk from PCBs at the Site. In addition, a range
from 0.1 to 0.2 mg/kg (wet weight) PCBs in brown
bullhead fillet was developed based on the
NOAEL and LOAEL for consumption of fish by the
mink.
3. Minimize the current and potential future
bioavailability of the PCBs in sediments. PCBs in
sediments may become bioavailable by various
mechanisms (e.g., pore water diffusion,
bioturbation, biological activity, benthic food
chains, ice jam event scour, etc). Minimizing the
degree to which such mechanisms may make
PCBs bioavailable (e.g., through removal or
containment) will reduce PCB levels in biota and
the associated risks to human health and the
environment.
4. Protect the ecosystem of the lower Grasse River.
The remedy will protect the ecosystem and
replace and/or reconstruct habitat impacted by
remedial activities in order to re-establish
appropriate conditions for supporting the fish and
wildlife of the river. The remedy will be monitored
for ecosystem recovery through the measurement
and analysis of appropriate physical, chemical,
and biological parameters.
5. Minimize the long-term transport of PCBs from the
lower Grasse River to the St. Lawrence River.
PCBs that are transported downstream in the
water column are available to biota, contributing to
the risks from the Site. Downstream transport
also may move PCBs from contaminated areas to
clean areas and from the lower Grasse River to
the St. Lawrence River.
As noted above, the Power Canal (Reach 3) is not within
the scope of this Proposed Plan but will continue to be
monitored.
SUMMARY OF REMEDIAL ALTERNATIVES
CERCLA § 121(b)(1), 42 U.S.C. § 9621(b)(1), mandates
that remedial actions must be protective of human health
and the environment, be cost-effective, and utilize
permanent solutions and alternative treatment
technologies and resource recovery alternatives to the
maximum extent practicable. Section 121(b)(1) also
establishes a preference for remedial actions which
employ, as a principal element, treatment to permanently
and significantly reduce the volume, toxicity, or mobility of
the hazardous substances, pollutants and contaminants at
a site. CERCLA § 121(d), 42 U.S.C. § 9621(d), further
specifies that a remedial action must attain a level or
standard of control of the hazardous substances,
pollutants, and contaminants, which at least attains
ARARs under federal and state laws, unless a waiver can
be justified pursuant to CERCLA § 121(d)(4), 42 U.S.C. §
9621(d)(4).
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Detailed Analysis
Detailed descriptions of the ten remedial alternatives for
addressing the contamination associated with the Site can
be found in the Analysis of Alternatives report. With the
exception of the No Further Action Alternative, all of these
alternatives involve dredging, capping, or monitored
natural recovery, or combinations thereof.
All of the alternatives, except Alternative 1 (No Further
Action) and Alternative 2 (Monitored Natural Recovery),
include the development of a habitat reconstruction plan.
The objective of the habitat reconstruction plan would be
to identify impacts to habitat and species from the remedy,
identify habitat re-establishments goals, provide design
specifications for habitat recovery, and provide the scope
for monitoring of habitat recovery. The plan would be
developed and implemented during design and remedy
implementation, and would include the following
components:
• A) Habitat assessment study for affected species
to assess the river for habitats that are present
and use of the habitats by aquatic and semi-
aquatic species. The study would include a
survey for the presence of federal and state listed
aquatic species and the habitats used by these
species in the remedial area. Additionally, the
study would document the habitat characteristics
(including but not limited to temperature regime,
substrate type, structure, plant species and
density) of all areas affected by the remedy and
identify any fish and wildlife concentration areas.
Collected data would be used to determine the
habitats affected by the remedy, any actions
necessary to eliminate or minimize impacts to
listed species, measures needed to protect
existing habitats, and develop design
specifications for the replacement and recovery of
the all affected habitats following the remedy.
• B) Identification of habitat recovery material over
capped areas and/or return to grade. Placement
of clean substrate on top of the cap to allow for
habitat re-establishment and species use, except
where the material placed for the cap would be of
sufficient quality and thickness to allow for
omitting an additional habitat layer. The design of
the thickness of the habitat layer of the cap should
consider, in addition to other things, the potential
for burrowing animals to compromise the integrity
of the cap. The habitat recovery material would
be free of contaminants and would not require
significant maintenance once habitat has been re-
established. After placement of the habitat
recovery material, the initial grade should be
returned in near shore areas and main channel
areas should be returned to a stable condition.
The most appropriate substrate type would be
determined based on the information collected
during the habitat assessment and may vary
depending on habitat re-establishment and
species requirements or habitat reconstruction
goals.
• C) Design for restoration of vegetation. In areas
disturbed by the remedy or implementation of the
remedy, vegetation would be re-established
through a mixture of appropriate active planting
and seeding and passive measures to allow for
healthy and diverse habitat. Vegetation
placement would be determined during the
design.
• D) Monitoring habitat and biota recovery: A
monitoring plan would assess the success of
habitat re-construction materials, plantings, and
recovery of biota. The monitoring plan would
include baseline sampling and corrective actions
pertaining to habitat reconstruction, should they
be necessary. Additionally, monitoring of PCBs in
biota would be conducted to track the success of
the remedy in reducing PCBs in the areas
affected by the remedy. Monitoring would be
specifically designed to track changes in PCB
concentrations in aquatic and semi-aquatic
species relevant to the Site.
Listed below are additional elements that are common to
all alternatives:
• All of the alternatives, except Alternatives 1 and 2,
would include provisions for habitat assessment,
re-establishment and monitoring. The following
elements would be developed during the remedial
design phase and incorporated in a habitat re-
construction plan for the Site: habitat assessment
and survey for listed or sensitive species; habitat
assessment and use study for general species;
habitat recovery material over capped areas
and/or return to grade; restoration of vegetation;
monitoring of re-establishment success; and
monitoring of PCBs in biota.
• A Phase 1A Cultural Resource Assessment will
be conducted during the pre-remedial design prior
to any disturbance and/or in-river work.
• The construction time for each alternative reflects
only the time required to construct or implement
the remedy and does not include the time required
to design the remedy or procure contracts for
design and construction.
• All of the alternatives assume contaminants
remaining on-site above levels that would allow
for unrestricted use and unlimited exposure and,
therefore, CERCLA requires that the Site be
reviewed at least once every five years. Costs
associated with five-year reviews are included in
all of the alternative present-worth cost estimates
except for No Further Action Alternative 1.
• All alternatives define the near shore surface
sediment depth as the top 12 inches and the main
13
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channel surface sediment depth as the top 6
inches.
• All alternatives with the exception of Alternatives 1
and 2 would include air monitoring to ensure that
remedy implementation is protective.
• For cost estimating purposes, all alternatives with
a dredging component assume use of a hydraulic
dredge for the main channel and use of a
mechanical dredge for the near shore. For the
dewatering process, the cost estimate assumes
the use of plate and frame filter press, belt filter
press, solid-bowl evaporator, hydrocyclone, and
gravity thickener or settling basin. For water
treatment, granular activated carbon is assumed.
However, once a remedy has been selected, the
most appropriate and effective equipment will be
determined during the design phase and utilized
during construction.
• For cost estimating purposes, all alternatives
assumed the armored cap to be 25 inches and the
main channel cap to be 12 inches of sand/topsoil
cap as designed in the ROPS. However, during
design, the composition and thickness of the
capping material will be optimized to promote
reliability and efficacy of the cap;
• For all alternatives where dredging is proposed,
the cost estimate assumes up to 100,000 cy of in-
situ dredged sediment will be disposed of in an
existing on-site permitted TSCA/RCRA landfill.
The cost estimates for alternatives with greater
quantities of dredged material assume the volume
exceeding 100,000 cy will be transported off-site
for disposal at a permitted TSCA/RCRA landfill.
The remedial alternatives are:
Alternative 1: No Further Action
The Superfund program requires that the "no-action"
alternative be considered as a baseline for comparison
with the other alternatives. The no-action alternative does
not include any physical remedial measures beyond those
response actions already implemented to address the
problem of sediment contamination at the Site.
Present-Worth Cost: $0
Construction Time: 0 years
Alternative 2: Monitored Natural Recovery
The Monitored Natural Recovery (MNR) alternative relies
on naturally occurring processes to reduce the toxicity,
mobility, and volume of the contaminants in the lower
Grasse River sediments. Natural recovery processes may
include biodegradation, biotransformation, bioturbation,
diffusion, dilution, adsorption, volatilization, chemical
reaction or destruction, resuspension, downstream
transport, and burial by cleaner material. Long-term
monitoring of sediment, water column, and fish would be
included in this alternative to confirm that contaminant
reduction is occurring and that the reduction is achieving
the Remedial Action Objectives.
Institutional controls, in the form of continuation of fish
consumption advisories would be implemented as long-
term control measures as part of the MNR alternative. A
review of site conditions would be conducted at five-year
intervals, as required by CERCLA.
Present-Worth Cost: $3,400,000
Construction Time: 0 years
Alternative 3: Capping
This alternative includes: the placement of a 25-inch
armored cap over the T1-T21 main channel sediments (59
acres) where either the segment length weighted average
(SLWA) or the maximum surface sediment PCB
concentration is greater than or equal to 1 mg/kg6; the
placement of a 12-inch main channel cap over main
channel sediments between T21 and T72 (approximately
225 acres) with maximum surface sediment PCB
concentrations greater than or equal to 1 mg/kg;
placement of a 6-inch near shore cap over sediments in
the near shore areas between T1 and T21 (10 acres) with
SLWA or maximum surface sediment PCB concentrations
greater than or equal to 1 mg/kg; and placement of a near
shore cap (6-inch) over sediments in the near shore areas
between T21 and T72 (31 acres) with maximum surface
sediment PCB concentrations greater than or equal to 1
mg/kg. The SLWA is used to identify PCBs at depth, and
is one of the criteria for triggering remediation in T1-T21
because of the potential for scour in those transects.
(Refer to the Analysis of Alternatives Report for more
details on the armored cap, and near shore and main
channel cap materials.)
After construction is completed, the remedy would be
monitored over the long term. This alternative also relies
on institutional controls, such as the fish consumption
advisories and restrictions on activities that could
compromise the integrity of the cap (such as anchoring
which can disturb the cap), and sedimentation in achieving
the Remedial Action Objectives. If monitoring reveals any
portion of the caps has been eroded, damaged areas
would require maintenance/replacement. A review of site
conditions would be conducted at five-year intervals, as
required by CERCLA.
6 "Maximum surface sediment PCB concentration greater
than or equal to 1 mg/kg" means a PCB concentration of 1
mg/kg or greater in any core segment collected from surface
sediments.
14
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Present-Worth Cost: $114,400,000
Construction Time: 3 years
Alternative 4: T1-T21 Near Shore (NS) Dredging and
Backfill to Grade, T21-T72 NS Capping, T1-T21 Main
Channel (MC) Armored Capping and T21-T72 MC
Capping
Alternative 4 includes: the placement of a 25-inch armored
cap over the T1-T21 main channel sediments where either
the SLWA or the maximum surface sediment PCB
concentrations is greater than or equal to 1 mg/kg; the
placement of a 12-inch main channel cap over main
channel sediments between T21 and T72 with maximum
surface sediment PCB concentrations greater than or
equal to 1 mg/kg; dredging of near shore sediment
between T1 and T21 with SLWA or maximum surface
sediment PCB concentrations greater than or equal to 1
mg/kg, followed by backfill to grade; and placement of a
near shore cap (6-inch) over sediments in the near shore
areas between T21 and T72 with maximum surface
sediment PCB concentrations greater than or equal to 1
mg/kg. This alternative includes 59 acres of armored cap,
approximately 225 acres of main channel cap, 31 acres of
near shore cap, 26,000 in-situ cy of sediment dredged in
the near shore followed by backfilling to pre-dredging
grade in the dredged area. (Refer to Table 2 below in the
Reduction in Toxicity, Mobility, or Volume Through
Treatment section for estimated volumes dredged and
areas capped.)
After construction is completed, the remedy would be
monitored over the long term. This alternative also relies
on institutional controls, such as the fish consumption
advisories and restrictions on activities that could
compromise the integrity of the cap (such as anchoring
which can disturb the cap), and sedimentation in achieving
the Remedial Action Objectives. If monitoring reveals any
portion of the caps has been eroded, damaged areas
would require maintenance/replacement. A review of site
conditions would be conducted at five-year intervals, as
required by CERCLA.
Present-Worth Cost: $147,000,000
Construction Time: 3 years
Alternative 5: T1-T72 NS Surface Sediment PCBs >10
mg/kg Dredging and Capping between 1 mg/kg and 10
mg/kg, T1-T21 MC Armored Capping and T21-T72 MC
Capping
Alternative 5 includes: the placement of a 25-inch armored
cap over the T1-T21 main channel sediments where either
the SLWA or the maximum surface sediment PCB
concentration is greater than or equal to 1 mg/kg; the
placement of a 12-inch main channel cap over main
channel sediments between T21 and T72 with maximum
surface sediment PCB concentrations greater than or
equal to 1 mg/kg; dredging of near shore sediment
between T1 and T21 with SLWA or maximum surface
sediment PCB concentrations greater than or equal to 10
mg/kg, followed by 6-inch capping of near shore sediment
between T1 and T21 with PCB concentrations greater
than or equal to 1 mg/kg and less than 10 mg/kg; and
dredging of near shore sediment between T21 and T72
with maximum surface sediment PCB concentrations
greater than or equal to 10 mg/kg, followed by 6-inch
capping of near shore sediment between T21 and T72
with PCB concentrations greater than or equal to 1 mg/kg
and less than 10 mg/kg. This alternative includes 59
acres of armored cap, approximately 225 acres of main
channel cap, 31 acres of near shore cap, 46,000 in-situ cy
of sediment dredged in the near shore and 13 acres
backfilled to grade. The 28 acres of the remaining near
shore area between T1 and T72 that is not addressed by
dredging/backfilling would be capped.
After construction is completed, the remedy would be
monitored over the long term. This alternative also relies
on institutional controls, such as the fish consumption
advisories and restrictions on activities that could
compromise the integrity of the cap (such as anchoring
which can disturb the cap), and sedimentation in achieving
the Remedial Action Objectives. If monitoring reveals any
portion of the caps has been eroded, damaged areas
would require maintenance/replacement. A review of site
conditions would be conducted at five-year intervals, as
required by CERCLA.
Present-Worth Cost: $175,000,000
Construction Time: 4 years
Alternative 6: T1-T72 NS Dredging and Backfill to
Grade, T1-T21 MC Armored Capping and T21-T72 MC
Capping
Alternative 6 includes: the placement of a 25-inch armored
cap over the T1-T21 main channel sediments where either
the SLWA or the maximum surface sediment PCB
concentrations is greater than or equal to 1 mg/kg; the
placement of a 12-inch main channel cap over main
channel sediments between T21 and T72 with maximum
surface sediment PCB concentrations greater than or
equal to 1 mg/kg; dredging of near shore sediment
between T1 and T21 with SLWA or maximum surface
sediment PCB concentrations greater than or equal to 1
mg/kg, followed by backfill to grade; and, dredging near
shore sediment between T21 and T72 with maximum
surface sediment PCB concentrations greater than or
equal to 1 mg/kg, followed by backfill to grade. This
alternative includes 59 acres of armored cap,
approximately 225 acres of main channel cap, 109,000 in-
situ cy of sediment dredged in the near shore and 41
acres backfilled to grade.
After construction is completed, the remedy would be
monitored over the long term. This alternative also relies
on institutional controls, such as the fish consumption
15
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advisories and restrictions on activities that could
compromise the integrity of the cap (such as anchoring
which can disturb the cap), and sedimentation in achieving
the Remedial Action Objectives. If monitoring reveals any
portion of the caps has been eroded, damaged areas
would require maintenance/replacement. A review of site
conditions would be conducted at five-year intervals, as
required by CERCLA.
Present-Worth Cost: $243,000,000
Construction Time: 4 years
Alternative 7: T1-T72 NS Dredging and Backfill to
Grade, T1-T19.5 Select MC Dredging, T1-T21 MC
Armored Capping, and T21-T72 MC Capping
Alternative 7 includes: dredging of main channel
sediments from Work Zones 2 and 3 (approximately T7.5
to T9.5) defined in the ROPS and T16.5 to T19.5;
placement of a 25-inch armored cap over the dredged
portion of the main channel sediments where residuals
sediment PCB concentrations greater than or equal to 1
mg/kg; placement of an armored cap over remaining
sediments in the main channel between T1 and T21 with
SLWA or maximum sediment PCB concentrations greater
than or equal to 1 mg/kg; the placement of a 12-inch main
channel cap over main channel sediments between T21
and T72 with maximum surface sediment PCB
concentrations greater than or equal to 1 mg/kg; dredging
of near shore sediment between T1 and T21 with SLWA
or maximum surface sediment PCB concentrations
greater than or equal to 1 mg/kg, followed by backfill to
grade; and dredging of near shore sediment between T21
and T72 with maximum surface sediment PCB
concentrations greater than or equal to 1 mg/kg, followed
by backfill to grade. This alternative includes 150,000 in-
situ cy of sediment dredged from main channel, 59 acres
of armored cap, approximately 225 acres of main channel
cap, 109,000 in-situ cy of sediment dredged in the near
shore and 41 acres backfilled to grade.
Though a great amount of sediment in the main channel is
dredged in this alternative, due to the site conditions and
based on information from site-specific pilot studies and
other dredging sites, it is anticipated that residual
sediments with PCB concentrations greater than or equal
to 1 mg/kg will remain after dredging, requiring an
armored cap.
After construction is completed, the remedy would be
monitored over the long term. This alternative also relies
on institutional controls, such as the fish consumption
advisories and restrictions on activities that could
compromise the integrity of the cap (such as anchoring
which can disturb the cap), and sedimentation in achieving
the Remedial Action Objectives. If monitoring reveals any
portion of the caps has been eroded, damaged areas
would require maintenance/replacement. A review of site
conditions would be conducted at five-year intervals, as
required by CERCLA.
Present-Worth Cost: $352,000,000
Construction Time: 5 years
Alternative 8: T1-T21 NS Dredging and Backfill to
Grade, T1-T21 MC Dredging and Armored Capping
Residuals, and T21-T72 NS and MC Capping
Alternative 8 includes: dredging of main channel and near
shore between T1 to T21 with SLWA or maximum surface
sediment PCB concentrations greater than or equal to 1
mg/kg; placement of a 25-inch armored cap over the
dredged portion of the main channel sediments where
residuals sediment PCB concentrations greater than or
equal to 1 mg/kg; placement of backfill to grade in the
dredged near shore; the placement of a 12-inch main
channel cap over main channel sediments between T21
and T72 with maximum surface sediment PCB
concentrations greater than or equal to 1 mg/kg; and
placement of a near shore cap (6-inch) over sediments in
the near shore areas between T21 and T72 with maximum
surface sediment PCB concentrations greater than or
equal to 1 mg/kg. This alternative includes 329,000 in-situ
cy of sediment dredged from the main channel, 59 acres
of armored cap, approximately 225 acres of main channel
cap, 26,000 in-situ cy of sediment dredged in the near
shore and 10 acres backfilled to grade, and an additional
31 acres of near shore would be capped.
Though a great amount of sediment in the main channel is
dredged in this alternative, due to the site conditions and
based on site-specific pilot studies and experiences at
other dredging sites, it is anticipated that residual
sediments with PCB concentrations greater than or equal
to 1 mg/kg will remain after dredging that require an
armored cap after dredging.
After construction is completed, the remedy would be
monitored over the long term. This alternative also relies
on institutional controls, such as the fish consumption
advisories and restrictions on activities that could
compromise the integrity of the cap (such as anchoring
which can disturb the cap), and sedimentation in achieving
the Remedial Action Objectives. If monitoring reveals any
portions of the caps have been eroded, damaged areas
would require maintenance/replacement. A review of site
conditions would be conducted at five-year intervals, as
required by CERCLA.
Present-Worth Cost: $388,000,000
Construction Time: 8 years
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Alternative 9: T1-T72 NS Dredging and Backfill to
Grade, T1-T46 Select MC Dredging, T1-T21 MC
Armored Capping, and T21-T72 MC Capping
Alternative 9 includes: dredging of main channel
sediments from Work Zones 2 and 3 (approximately T7.5
to T9.5) as defined in the ROPS and T16.5 to T19.5, T27
to T37, and T43 to T46; placement of a 25-inch armored
cap over the dredged portion of the main channel
sediments where the residual sediment PCB
concentration is greater than or equal to 1 mg/kg;
placement of an armored cap over remaining undredged
sediments in the main channel between T1 and T21 with
SLWA or maximum sediment PCB concentrations greater
than or equal to 1 mg/kg; the placement of a 12-inch main
channel cap over main channel sediments (undredged
and residuals) between T21 and T72 with maximum
surface sediment PCB concentrations greater than or
equal to 1 mg/kg; dredging of near shore sediment
between T1 and T21 with SLWA or maximum surface
sediment PCB concentrations greater than or equal to 1
mg/kg, followed by backfill to grade; and, dredging near
shore sediment between T21 and T72 with maximum
surface sediment PCB concentrations greater than or
equal to 1 mg/kg, followed by backfill to grade. This
alternative includes 525,000 in-situ cy of sediment
dredged from the main channel, 59 acres of armored cap,
approximately 225 acres of main channel cap, 109,000 in-
situ cy of sediment dredged in the near shore and 41
acres backfilled to grade.
Though a great amount of sediment in the main channel is
dredged in this alternative, due to the site conditions and
based on information from site-specific pilot studies and
other dredging sites, it is anticipated that residual
sediments with PCB concentrations greater than or equal
to 1 mg/kg will remain, requiring an armored cap or main
channel cap, as appropriate, after dredging.
After construction is completed, the remedy would be
monitored over the long term. This alternative also relies
on institutional controls, such as the fish consumption
advisories and restrictions on activities that could
compromise the integrity of the cap (such as anchoring
which can disturb the cap), and sedimentation in achieving
the Remedial Action Objectives. If monitoring reveals any
portions of the caps have been eroded, damaged areas
would require maintenance/replacement. A review of site
conditions would be conducted at five-year intervals, as
required by CERCLA.
Alternative 10: T1-T72 NS Dredging and Backfill to
Grade, T1-T72 MC Dredging, T1-T21 MC Armored
Capping, and T21-T72 MC Capping
Alternative 10 includes: dredging areas of the main
channel and near shore between T1 to T21 which have
SLWA or maximum surface sediment PCB concentrations
greater than or equal to 1 mg/kg; placement of a 25-inch
armored cap over the dredged portion of the main channel
sediments between T1 and T21 with PCB residuals of
greater than or equal to 1 mg/kg; backfilling the dredged
near shore area between T1 to T21 to grade; dredging
sediments in the main channel between T21 to T72 with
maximum surface sediment PCB concentrations greater
than or equal to 1 mg/kg; placement of a main channel
cap over dredged portions of the main channel between
T21 and T72 with residuals greater than or equal to 1
mg/kg; and dredging of near shore sediment between T21
and T72 with maximum surface sediment PCB
concentrations greater than or equal to 1 mg/kg, followed
by backfill to grade. This alternative includes 1,555,000
in-situ cy of sediment dredged from the main channel, 59
acres of armored cap, approximately 225 acres of main
channel cap, 109,000 in-situ cy of sediment dredged in the
near shore and 41 acres backfilled to grade.
Though a great amount of sediment in the main channel is
dredged in this alternative due to the site conditions and
based on information from site-specific pilot studies and
other dredging sites, it is anticipated that residual
sediments with PCB concentrations greater than or equal
to 1 mg/kg will remain, requiring an armored cap or main
channel cap, as appropriate, after dredging.
After construction is completed, the remedy would be
monitored over the long term. This alternative also relies
on institutional controls, such as the fish consumption
advisories and restrictions on activities that could
compromise the integrity of the cap (such as anchoring
which can disturb the cap), and sedimentation in achieving
the Remedial Action Objectives. If monitoring reveals any
portions of the caps have been eroded, damaged areas
would require maintenance/replacement. A review of site
conditions would be conducted at five-year intervals, as
required by CERCLA.
Present-Worth Cost:
Construction Time:
$1,274,000,000
18 years
Present-Worth Cost:
Construction Time:
$589,000,000
7 years
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NINE EVALUATION CRITERIA FOR SUPERFUND REMEDIAL ALTERNATIVES
Overall protection of human health and the environment determines whether an alternative eliminates, reduces, or controls threats to
public health and the environment through institutional controls, engineering controls, or treatment.
Compliance with ARARs evaluates whether the alternative would meet all of the applicable or relevant and appropriate requirements of
federal and state environmental statutes and other requirements that pertain to the site, or provide grounds for invoking a waiver.
Long-term effectiveness and permanence considers the ability of an alternative to maintain protection of human health and the
environment over time.
Reduction of toxicity, mobility, or volume through treatment is the anticipated performance of the treatment technologies an alternative
may employ.
Short-term effectiveness considers the period of time needed to implement an alternative and the risks the alternative may pose to
workers, residents, and the environment during implementation.
Implementability is the technical and administrative feasibility of implementing the alternative, including the availability of materials and
services.
Cost includes estimated capital and annual operation and maintenance costs, as well as present-worth costs. Present worth cost is the
total cost of an alternative over time in terms of today's dollar value. Cost estimates are expected to be accurate within a range of +50 to -
30 percent.
State acceptance considers whether the State agrees with the EPA's analyses and recommendations, as described in the RI/FS and
Proposed Plan.
Community acceptance will be assessed in the ROD and refers to the public's general response to the alternatives described in the
Proposed Plan and the RI/FS reports. Comments received on the Proposed Plan are an important indicator of community acceptance.
COMPARATIVE ANALYSIS OF ALTERNATIVES
In selecting a remedy for a site, EPA considers the factors
set forth in CERCLA § 121, 42 U.S.C. § 9621, by
conducting a detailed analysis of the viable remedial
alternatives pursuant to the NCP at 40 CFR §
300.430(e)(9), EPA's Guidance for Conducting Remedial
Investigations and Feasibility Studies, OSWER Directive
9355.3-01, and EPA's A Guide to Preparing Superfund
Proposed Plans, Records of Decision, and Other Remedy
Selection Decision Documents, OSWER 9200.1-23.P.
The detailed analysis consists of an assessment of the
individual alternatives against each of the nine evaluation
criteria (see box above) and a comparative analysis
focusing upon the relative performance of each alternative
against those criteria.
A comparative analysis of these alternatives based upon
the evaluation criteria noted below follows.
Overall Protection of Human Health and the
Environment
Overall protection of human health and the environment
at the Site would be achieved by reducing the PCB
concentrations in fish and other biota. To accomplish this
reduction, remedial alternatives need to address the
diffusive flux of PCBs from surface sediments, and
control sediment stability through dredging, capping, and
natural recovery. Each of the alternatives presented,
except Alternative 1 (No Further Action) and Alternative 2
(Monitored Natural Recovery), would provide some level
of protection of human health and the environment
through a combination of active remediation and
monitored natural recovery. Alternative 1 (No Further
Action) would not be protective of human health and the
environment since it would not address the PCBs in the
sediments, which present human health and ecological
risks.
Alternative 2 (Monitored Natural Recovery) relies on
natural processes such as sedimentation to cover the
surface sediment with cleaner sediment from upstream,
in order to reduce the PCB concentration at the sediment
surface and reduce risk. However, periodic ice jam-
related scour events could result in remobilization of
PCBs and would therefore present a continued risk to
human health and the environment even after cleaner
sediments are deposited over the PCBs.
Alternative 3 (Capping) relies on effective cap placement
and maintenance to isolate PCB-containing sediments,
while Alternatives 4 through 10 rely on a combination of
dredging and capping, followed by monitoring and
maintenance of the caps, for the protection of human
health and the environment. Dredging generally relies
upon effective removal of contaminated sediment and low
PCB residual concentrations. For the main channel,
none of the alternatives presented rely solely on dredging
because the residuals would most likely exceed the PCB
sediment action level of 1 mg/kg, thus requiring the main
channel to be capped even after dredging.
The projected times that it would take under each of the
alternatives to reach the fish Preliminary Remediation
Goal (PRG) and the interim target concentrations in the
Remedial Action Objectives have been modeled and are
provided on Table 1.
The fish PRG is 0.05 mg/kg PCBs (wet weight) in fillet.
The fish PRG to protect Mohawk human health is 0.01
mg/kg. The difference is attributable to the greater fish
consumption rate used in the calculation for the Mohawk
population than the average fish consumption rate of the
non-Mohawk adult population. EPA has identified an
interim target concentration of 0.26 mg/kg PCBs in fillet
18
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based on the average consumption rate of one half
pound meal per month, and another interim target
concentration of 0.36 mg/kg based on the average
consumption rate of one half pound meal every two
months. Currently, the fish consumption advisory is
established as, "eat none" for the lower Grasse River.
For all alternatives, after remedy implementation,
NYSDOH would review post-remediation fish PCB data
and will consider relaxing the current fish advisory based
on their review. NYSDOH and NYSDEC Fish and
Wildlife staff also would be involved in post-remediation
fish sampling and analysis program design.
Although the time frames vary for alternatives 2 through
10, these alternatives are projected to provide reduced
PCB concentrations in fish over variable time frames, and
therefore offer varying degrees of protection of human
health and the environment. Alternatives 3 through 10,
which include measures to prevent remobilization of
PCBs in the main channel sediment vulnerable to ice
jam-related scour would provide greater protection than
Alternatives 1 and 2.
As can be seen in Table 1, none of the alternatives meet
the human health PRG of 0.05 mg/kg PCBs within the
30-year modeling time frame. Because capping can be
performed more quickly than dredging, the alternatives
with the greatest amounts of dredging take longer to
achieve the other target concentrations, because fish
continue to be exposed to PCBs in the sediment over the
longer construction time frame. Though it was not
modeled, none of the alternatives are anticipated to meet
the Mohawk human health PRG of 0.01 mg/kg within the
30-year modeling time frame, because it is lower than the
fish tissue level of 0.05 mg/kg.
Again, all of the active remedies presented in Alternatives
3 through 10 are expected to provide substantial risk
reduction compared to Alternatives 1 and 2, which
provide no active cleanup of the river. Alternatives 4, 5,
and 6 show the best predicted combined short and long-
term risk reduction.
Compliance with ARARs
The federal chemical-specific ARARs for PCBs in the
water column are the 0.001 ug/L federal Clean Water Act
(CWA) ambient water quality criterion for navigable
water, and the 0.014 ug/L federal CWA criterion
continuous concentration (CCC) [chronic] for freshwater
aquatic life. The NYS surface water quality standards for
PCBs are 0.12 ng/L for protection of wildlife and 0.001
ng/L for protection of human consumers offish.
Alternatives 3 through 10 would meet the CWA ambient
water criterion of 0.001 ug/L and the CWA CCC of 0.014
ug/L. However, the NYS surface water quality standard
of 0.12 ng/L and the 0.001 ng/L standard for protection of
human consumers of fish are not expected to be met by
any of the alternatives. This is due to Site background
PCB loading conditions and contributions from the Power
Canal, which have been accounted for in the model
projections. As such, a technical impracticability waiver
would be required for these ARARs under any of the
alternatives.
Because there is no active remediation associated with
the sediment for Alternatives 1 and 2, action-specific and
location-specific ARARs do not apply. Alternatives 3
through 10 would comply with action-specific ARARs
(e.g. CWA Section 401 and 404; TSCA Section 6(e) and
40 CFR Part 761; RCRA Section 3004; Section 10 of the
Rivers and Harbors Act; New York State ECL Article 3,
Title 3 and Article 27, Titles 7 and 9) and location-specific
ARARs (e.g., Endangered Species Act; Fish and Wildlife
Coordination Act; National Historic Preservation Act;
Coastal Zone Management Act; and New York State
Freshwater Wetlands Law). With regard to the location-
specific ARARs of New York State ECL Article 15, Title 5,
Article 17, Title 3 and 6 NYCRR Part 608 (regarding
placement of fill in navigable waters), Alternatives 6, 7, 9
and 10 are expected to be more likely to meet this ARAR
because they do not alter the bathymetry of the Grasse
River to the same extent as Alternatives 3, 4, 5 and 8
because Alternatives 6, 7, 9 and 10 do not include
capping that alter the near-shore bathymetry. Additional
assessment of remedial impacts will be necessary to
Table 1: Time (years) to Reach Target Concentration (mg/kg)
in Fish
Alternatives
0.05
0.26
0.36
1. No Further Action
> 30
> 30
> 30
2. MNR
> 30
> 30
> 30
3. Capping
> 30
7
6
4. T1-T21 NS Dredge and
> 30
7
6
Backfill, T21-T72 NS
Capping, and T1-T72 MC
Capping
5. T1-T72 NS Surface
> 30
8
7
Sediment PCBs > 10 mg/kg
Dredge and Cap between 1
mg/kg and 10 mg/kg, and
T1-T72 MC Cap
6. T1-T72 NS Dredge and
Backfill, T1-T72 MC
> 30
8
7
Capping
7. T1-T72 NS Dredge and
Backfill, T1-T19.5 Select
> 30
14
10
MC Dredge and Cap
Residuals, and Rest of MC
Capping
8. T1-T21 NS Dredge and
Backfill, T1-T21 MC Dredge
and Cap Residuals, and
> 30
19
13
T21-T72 NS and MC
Capping
9. T1-T72 NS Dredge and
> 30
17
13
Backfill, T1-T46 Select MC
Dredge and Cap Residuals,
and Rest of MC Capping
10. Dredging/Capping
> 30
23
20
Note: ">" = greater than
19
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determine the precise actions necessary for Alternatives
3 through 10 to meet the substantive requirements of the
location-specific ARAR of New York State ECL Article 11
Title 5 (New York State Endangered Species Act) and 6
NYCRR Part 182. A more detailed Analysis of potential
effects on wetlands and floodplains associated with the
preferred remedial alternative would be performed during
the remedial design, as necessary to ensure compliance
with Executive Orders 11990 (Protection of Wetlands)
and 11988 (Floodplain Management). More details and
the full list of ARARs and TBCs are available in the
Analysis of Alternatives report.
The SRMT has promulgated a 0.1 mg/kg cleanup
standard for PCBs in sediments. Tribal Council
Resolution No. 89-19 and Tribal Council Resolution No.
2007-72. EPA and the SRMT are currently discussing,
on a government-to-government basis, whether the
SRMT's sediment cleanup standard will be applied as a
"relevant and appropriate" requirement for the cleanup.
The SRMT cleanup standard is significantly lower than
EPA's proposed action levels for sediment cleanup (i.e.,
>1 mg/kg PCB surface or SLWA concentration) in this
Proposed Plan and may not be technically practicable to
achieve. Because it is doubtful that the SRMT sediment
standard can be achieved, and may therefore need to be
waived due to technical impracticability if it is identified as
an ARAR, EPA does not believe that the SRMT sediment
standard would necessarily lead to a remedy that is
different from the preferred remedy in this Proposed Plan.
EPA calculated the PRG of 0.01 mg/kg PCBs in fish
tissue for protection of Mohawk health using a fish
consumption rate for Mohawk subsistence anglers, which
is higher than the average fish consumption rate of the
non-Mohawk population.
Long-Term Effectiveness and Permanence
Reduction of Residual Risk
The No Further Action and MNR alternatives (Alternatives
1 and 2, respectively) remove no PCBs from the Grasse
River and include no active measures to reduce residual
risk at the Site. Under both alternatives, the degraded
condition of surficial sediment and surface water quality
will continue for decades, with no improvements other
than from sedimentation. Neither option would prevent
mobilization of PCBs in the main channel sediments that
are vulnerable to ice jam-related scour. Each of these
alternatives therefore would allow for the continued
exposure to PCB contamination over the long-term.
Alternative 3 actively reduces residual risk by isolating
PCBs in surface sediment under a cap. Alternatives 4
through 10 all reduce residual risk through various
combinations of dredging and capping. Alternatives 3
through 10 provide similar long-term risk reduction.
Removal of PCB-contaminated sediment if done
completely such that no sediments with PCB
concentrations above 1 mg/kg remain is considered more
permanent than capping, which requires long-term
maintenance of the cap. Complete removal of PCB-
contaminated sediment is possible in the near-shore, but
cannot be achieved in the main channel due to site-
specific conditions. The alternatives with greater amounts
of dredging are also projected to take longer to achieve
the RAOs interim target for PCBs in fish (0.26 mg/kg
PCBs in fillet based on the average consumption rate of
one half pound meal per month, and 0.36 mg/kg based on
the average consumption rate of one half pound meal
every two months) because capping can be more quickly
implemented than dredging.
Adequacy and Reliability of Controls
Sediment capping, sediment removal (dredging and
excavation), habitat replacement/backfilling, and off-site
disposal/treatment of removed sediments are all reliable
and proven technologies. Proper design, placement, and
maintenance of the caps are required for their
effectiveness, continued performance, and reliability. Cap
monitoring and maintenance programs would provide for
reasonable reliability, and any TSCA-permitted landfills
into which dredged PCBs are placed also would be
monitored and maintained over the long-term. The fish
consumption advisories would continue to provide some
measure of protection of human health until PCB
concentrations in fish are reduced to the point where the
fish consumption advisories can be relaxed or lifted.
Neither the No Further Action nor the MNR Alternative
includes any engineering controls to address PCB
contamination at the Site. Alternatives 3 through 10 all
reduce exposure to PCBs in surface sediments and
improve water quality through active measures. The
alternatives that have a dredging component in the main
channel (Alternatives 7 through 10) will permanently
remove various volumes of sediment and the associated
mass of PCBs from the river. Active Alternatives 3
through 10 also rely on capping for long-term
effectiveness. Alternatives 3 through 10 include
placement of an armored cap to provide a long-term
effective means of sequestering the PCB-contaminated
sediments buried beneath the main channel in areas
prone to scour from severe ice jam events in the river, and
also rely on the main channel cap in the lower T21 to T72
transects to address availability of PCBs in main channel
sediments.
Evaluations of propeller wash and scour from recreational
boats and placement of anchors on the cap show that
these activities are not expected to significantly impact the
overall stability of a main channel cap or an armored cap;
however, institutional controls, such as restrictions on
activities that could compromise the integrity of the cap
(such as anchoring which can disturb the cap), and long-
term monitoring would be necessary to ensure long-term
integrity of the cap.
PCBs isolated under the cap would migrate into the cap
very slowly via molecular diffusion, and the fastest
20
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Table 2: Volume of Dredging and Area Capped'
Alternatives
Dredging
Volume
in Main
Area
Capped
in Main
Dredging
Volume
in Near
Channel
Channel
Shore
(cy)
(acre)
(cy)
1. No Further Action
0
0
0
2. MNR
0
0
0
3. Capping
0
284
0
4. T1-T21 NS Dredge and
0
284
25,900
Backfill, T21-T72 NS
Capping, and T1-T72 MC
Capping
5. T1-T72 NS Surface
0
284
46,100
Sediment PCBs > 10
mg/kg Dredge and Cap
between 1 mg/kg and 10
mg/kg, and T1-T72 MC
Cap
6. T1-T72 NS Dredge and
0
284
108,700
Backfill, T1-T72 MC
Capping
7. T1-T72 NS Dredge and
149,600
284
108,700
Backfill, T1-T19.5 Select
MC Dredge and Cap
Residuals, and Rest of MC
Capping
8. T1-T21 NS Dredge and
329,000
284
25,900
Backfill, T1-T21 MC
Dredge and Cap
Residuals, and T21-T72
NS and MC Capping
9. T1-T72 NS Dredge and
524,500
284
108,700
Backfill, T1-T46 Select MC
Dredge and Cap
Residuals, and Rest of MC
Capping
10. Dredging/Capping
1.554
million
284
108,700
migration rate would still be slower than the rate at which
sediments will naturally accumulate on top of the cap.
Molecular diffusion is therefore not expected to
compromise the effectiveness of the cap.
Dredging in the near shore under Alternatives 4 through 6
would be more effective than dredging in the main
channel because contaminated near shore sediment can
be fully captured by dredging, as demonstrated by
ROPS. Alternatives 4 and 5 will each leave behind
greater near shore contamination (albeit under a cap)
than the Alternative 6. Therefore, Alternatives 6, 7, 9 and
10, which include the most near shore dredging, would
be more effective and permanent in re-establishing
valuable habitat for varied species in the near shore than
Alternatives 3, 4, 5, and 8, which include capping in the
near shore. Near shore areas that are dredged will be
backfilled with clean material to grade to provide
appropriate depth of sediment to allow for habitat re-
establishment and species use.
Reduction in Toxicity. Mobility, or Volume Through
Treatment
The No Further Action and MNR alternatives do not
involve any containment or removal of contaminants from
the Site. Both rely on natural attenuation processes
such as burial (sedimentation) by cleaner sediments to
reduce the concentration of PCBs in the sediment and
surface water. Mobility is not reduced by Alternative 1 or
2 because neither alternative sequesters and protects
sediment in the main channel that is susceptible to
scouring from severe ice jam events, and neither actively
retards the flux of PCBs from the sediment to the water
column.
Alternatives 4 through 10 will permanently remove various
volumes of sediment from the river (see Table 2) through
dredging, although not through treatment. Dredged
sediment would be transported to and disposed of at an
existing on-site TSCA/RCRA landfill and/or off-site to a
permitted TSCA/RCRA landfill. Alternatives 4 through 10
will include treatment of water generated by the dredging
and sediment handling processes to meet NYSDEC
discharge limits prior to discharge.
Placement of caps, which is a component of Alternatives 3
through 10, would provide reduction of mobility of the
contaminated sediment in the river through isolation of
PCBs contained beneath the cap, not through treatment.
Also in active Alternatives 3 through 10, after construction
of the remedy is completed, sedimentation will provide
further (but slower) reductions in the toxicity of PCBs in
the remaining sediment and surface water.
Short-Term Effectiveness
The No Further Action and MNR alternatives (Alternatives
1 and 2) do not involve any capping, dredging, or other
construction activities that could present a risk to workers
or the public. In addition, neither alternative increases the
potential for direct contact with or ingestion and inhalation
of PCBs from the surface water and sediment.
For the remaining alternatives, Alternative 3, which relies
on capping and MNR, would have the lowest short-term
impact to the workers, the environment, and the
community based on the construction duration (three
years) and minimal exposure to contaminated sediment at
7 The area to be capped in the near shore for Alternative 3 is
41 acres, for Alternative 4 is 31 acres, and for Alternatives 1,
2, 6-10 is none. The area to be backfilled in the near shore
after dredging for Alternative 4 is 10 acres, for Alternatives
6-10 is 41 acres. Alternative 5 has some dredging in the
near shore, however since the dredging is to 10 ppm and
not to a 1ppm cleanup level, the activity after dredging is
capping and not backfill. Alternative 5 has 41 acres to be
capped after dredging.
21
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depth. Some of the impacts associated with Alternative 3
would include disruption to the recreational boating, road
congestion from vehicles needed to bring equipment,
materials and workers to the Site, and short-term
ecosystem impacts from cap placement. A typical
construction season includes six months for the actual in-
river construction season (May - October) plus a month
before and a month after for mobilization/demobilization.
Alternatives 4 through 6 are expected to have greater
short-term impacts than Alternatives 1 through 3, but
fewer short-term impacts than Alternatives 7 through 10,
which include significant amounts of main channel
dredging. The construction durations are from three to
four years and the short-term impacts would include the
impacts outlined above for Alternative 3 (Capping).
Additionally, since Alternatives 4, 5, and 6 include
dredging, resuspension and release of PCBs in the river
will likely increase PCB concentrations in the water
column and fish tissue during the in-river remedial
operations and for a short period of time after dredging;
however, experience at other sites has shown that while
fish tissue concentrations often increase during dredging
projects, the fish tissue concentrations return to, pre-
dredging concentrations and then generally decline within
a few years after dredging ends. Also with dredging,
additional transportation congestion would occur on the
river from transporting up to 100,000 cy of dredged
material to the on-site landfill
Alternatives 7 through 9 have greater short-term impacts
than all alternatives except Alternative 10. Impacts would
be similar to those outlined for Alternatives 4 through 6,
except impacts would occur for longer construction
duration, 5 to 8 years. Also, the larger volume of sediment
requiring disposal at an off-site landfill would mean
increased truck traffic on the road beyond the disposal
facility and the Site.
Alternative 10 has the highest short-term impacts from
dredging and capping because it has the longest time
frame for construction (18 years). The magnitude of
potential short-term impacts associated with dredging
would increase greatly for this alternative in all respects
(environmental impacts, community impacts, and worker
safety) because of the dredge volume (approximately
1,663,000 in-situ cy) and duration.
The risks to remediation workers and nearby populations
under all of the active alternatives would, however, be
mitigated by following appropriate health and safety
protocols, by exercising sound engineering practices, and
by utilizing proper protective equipment. Work areas in
the river would be isolated (access restricted), with an
adequate buffer zone so the recreational water craft can
safely avoid such areas.
There may be some short-term temporary impacts to
aquatic and wildlife habitat, particularly in the near shore
for Alternatives 4 through 10, as a result of temporary
habitat removal through dredging. Habitat
replacement/backfilling measures would be implemented
to mitigate these impacts. A monitoring program would be
established to verify the attainment of the habitat
construction objectives set during the remedial design. A
habitat assessment and survey for listed or sensitive
species and a use study for general species would be
conducted during remedial design.
Implementabilitv
In general, all alternatives are considered to be
technically feasible within the lower Grasse River.
Design and implementation of both capping and dredging
are administratively feasible, as no permits are required
for in-river activities (although such activities would
comply with substantive requirements of otherwise
required permits), and construction would be performed
in accordance with ARARs. Permits would be obtained
as needed for off-site work.
There are no implementability issues for the No Further
Action and MNR alternatives, which do not involve any
active remediation.
Based on site-specific experience during the CPS and
ROPS, the design and placement of armored, main
channel, and near shore caps/backfill (components of all
active remedial alternatives) are expected to be
technically implementable. Some of the larger dredging
alternatives (Alternatives 7 through 10) would require
significant off-site landfill capacity for the dredged
sediments. Since all of the active alternatives require
significant quantities of capping material, coordination
with multiple cap material sources may be required to
support the project. Alternative 10, which requires the
greatest amount of dredging, has a greater uncertainty
regarding the local availability of necessary materials,
equipment, supplies, and services including landfill
capacity and capping materials over the extended project
period.
Dredging of various sediment volumes is a component of
the Alternatives 4 through 10. Operational problems with
the hydraulic horizontal auger dredge were encountered
during the NTCRA and ROPS in the main channel area.
The presence of complex site bottom conditions and
debris is expected to reduce the practicability and/or
efficiency of removing sediment from targeted main
channel areas in Alternatives 7 through 10. These
limitations would be present for all main channel dredging
alternatives; Alternative 6 does not have any main
channel dredging.
Unlike dredging in the main channel, dredging in the near
shore under Alternatives 4 through 10 would be more
effective because the contaminated sediment can be fully
captured by dredging as demonstrated by ROPS. Near
shore areas that are dredged will be backfilled with clean
material to grade to provide appropriate depth of
sediment to allow for habitat re-establishment and
species use.
22
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Cost
The present-worth costs were calculated using a discount
rate of seven percent and a thirty-year time interval for the
post-construction monitoring and maintenance period.
The estimated capital, long term monitoring, operation
and maintenance (O&M), and present-worth costs for
each of the alternatives are presented in the table below.
As can be seen from the Table 3, costs progressively
increase from Alternative 1 through Alternative 10.
Within the active Alternatives 3 through 10, the
progressive cost increases are primarily driven by
increasing amounts of dredging specified under the
alternatives.
State Acceptance
NYSDEC acceptance of the preferred alternative will be
addressed in the ROD following review of comments
received on the Proposed Plan.
Tribal Acceptance
Tribal acceptance of the preferred alternative by the St.
Regis Mohawk Tribe will be addressed in the ROD
following review of comments received on the Proposed
Plan, and continuing government-to-government
consultation.
Community Acceptance
Community acceptance of the preferred alternative will be
addressed in the ROD following review of the public
comments received on the Proposed Plan.
PREFERRED REMEDY
EPA's preferred remedy is Alternative 6: T1-T72 Near
Shore Dredge and Backfill to Grade and T1-T72 MC
Capping (see Figure 5). This alternative includes the
following components:
• Dredging of near shore sediment between T1 and
T21 with SLWA or maximum surface sediment
PCB concentrations greater than or equal to 1
mg/kg, followed by backfill to grade;
• Dredging of near shore sediment between T21
and T72 with maximum surface sediment PCB
concentrations greater than or equal to 1 mg/kg,
followed by backfill to grade;
• Placement of an armored cap over the T1-T21
main channel sediments where either the SLWA
or the maximum surface sediment PCB
concentrations is greater than or equal to 1
mg/kg. During design, the composition and
thickness of the capping material will be
Table 3: Cost Comparison
Alternatives
Capital
(million)
Long term
Monitoring/
O&M
(present
worth,
million)
Total
Present
Worth
(million)
1. No Further Action
$0
$0
$ 0
2. MNR
$0
$3.4
$ 3.4
3. Capping
$74.2
$10.2
$ 114.1
4. T1-T21 NS Dredge
and Backfill, T21-T72 NS
Capping, and T1-T72 MC
Capping
$97.6
$10.6
$ 147.2
5. T1-T72 NS Surface
Sediment PCBs > 10
mg/kg Dredge and Cap
between 1 mg/kg and 10
$117.3
$11.0
$ 175.2
mg/kg, and T1-T72 MC
Cap
6. T1-T72 NS Dredge
and Backfill, T1-T72 MC
$165.2
$11.8
$ 243.1
Capping
7. T1-T72 NS Dredge
and Backfill, T1-T19.5
Select MC Dredge and
$242.7
$11.8
$ 351.6
Cap Residuals, and Rest
of MC Capping
8. T1-T21 NS Dredge
and Backfill, T1-T21 MC
Dredge and Cap
Residuals, and T21-T72
$269.6
$10.6
$ 388.0
NS and MC Capping
9. T1-T72 NS Dredge
and Backfill, T1-T46
Select MC Dredge and
Cap Residuals, and Rest
$411.9
$11.9
$ 588.5
of MC Capping
10. Dredging/Capping
$901.2
$11.9
$ 1,273.5
optimized to promote reliability and efficacy of
the cap;
• Placement of a main channel cap over sediments
between T21 and T72 with maximum surface
sediment PCB concentrations greater than or
equal to 1 mg/kg. During design, the composition
and thickness of the capping material will be
optimized to promote reliability and efficacy of the
cap;
• Within the near shore area targeted for dredging,
the goal is to remove all of the PCB-contaminated
sediments within these area, leaving a residual of
less than 1 mg/kg;
• Treatment of water generated by the dredging and
sediment handling processes to meet NYSDEC
discharge limits;
• Frequent monitoring at least one or two times per
year of fish, water, and sediment to determine
when Preliminary Remediation Goals are reached
23
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and implementation (or modification) of
appropriate institutional controls, until goals are
met;
• A Phase 1A Cultural Resource Assessment will
be conducted during the pre-remedial design prior
to any disturbance and/or in-river work;
• Development of a habitat reconstruction plan. The
objective of the habitat reconstruction plan would
be to identify impacts to habitat and species from
the remedy, identify habitat re-establishments
goals, provide design specifications for habitat
recovery, and provide the scope for monitoring of
habitat recovery. The plan would be developed
and implemented during design and remedy
implementation, and would include the following
components:
• A) Habitat assessment study for affected
species would be conducted to assess the
river for habitats that are present and use of
the habitats by aquatic and semi-aquatic
species. The study would include a survey for
the presence of federal and state listed
aquatic species and the habitats used by
these species in the remedial area.
Additionally, the study will document the
habitat characteristics (including but not
limited to temperature regime, substrate type,
structure, plant species and density) of all
areas affected by the remedy and identify any
fish and wildlife concentration areas.
Collected data would be used to determine
the habitats affected by the remedy, any
actions necessary to eliminate or minimize
impacts to listed species, measures needed to
protect existing habitats, and develop design
specifications for the replacement and
recovery of the all affected habitats following
the remedy.
• B) Identification of habitat recovery material
over capped areas and/or return to grade.
Placement of clean substrate on top of the
cap to allow for habitat re-establishment and
species use, except where the material placed
for the cap would be of sufficient quality and
thickness to allow for omitting an additional
habitat layer. The design of the thickness of
the habitat layer of the cap should consider, in
addition to other things, the potential for
burrowing animals to compromise the integrity
of the cap. The habitat recovery material
would be free of contaminants and would not
require significant maintenance once habitat
has been re-established. After placement of
the habitat recovery material, the initial grade
should be returned in near shore areas and
main channel areas should be returned to a
stable condition. The most appropriate
substrate type will be determined based on
the information collected during the habitat
assessment and may vary depending on
habitat re-establishment and species
requirements or habitat reconstruction goals.
• C) Design for restoration of vegetation. In
areas disturbed by the remedy or
implementation of the remedy, vegetation
would be re-established through a mixture of
appropriate active planting and seeding and
passive measures to allow for healthy and
diverse habitat. Vegetation placement would
be determined during the design; and
• D) Monitoring habitat and biota recovery. A
monitoring plan would assess the success of
habitat re-construction materials, plantings,
and recovery of biota. The monitoring plan
would include baseline sampling and
corrective actions pertaining to habitat
reconstruction, should they be necessary.
Additionally, monitoring of PCBs in biota
would be conducted to track the success of
the remedy in reducing PCBs in the areas
affected by the remedy. Monitoring would be
specifically designed to track changes in PCB
concentrations in aquatic and semi-aquatic
species relevant to the Site;
• Air monitoring to ensure that remedy
implementation is protective; and
• Institutional controls, such as the fish consumption
advisories and restrictions on activities that could
compromise the integrity of the cap (such as
anchoring which can disturb the cap).
This alternative includes 59 acres of armored cap,
approximately 225 acres of main channel cap,
approximately 109,000 in-situ cy of sediment dredging in
the near shore, and 41 acres backfilled to grade. Most of
the dredged material (up to about 100,000 cy) would be
disposed in the on-site permitted Secured Landfill. During
the design, the design team will evaluate the feasibility of
expanding the on-site Secured Landfill to accommodate
approximately 9,000 additional cy of dredged material.
The design team also will consult with the appropriate
state and federal permitting authorities regarding
substantive requirements for such expansion. In the event
that it is not feasible to expand the existing on-site landfill,
the additional 9,000 cy of dredged material will be
disposed at an off-site permitted TSCA/RCRA landfill.
Based on current information, the 59-acre main channel
area estimated for armored capping is from T1 to T21.
However, during the design further investigation may be
necessary in the vicinity of T35, T37, T46, and any other
areas where evidence of periodic high energy has been
observed in the cores such that these areas may require
more than a 12-inch sand/topsoil main channel cap. As
with all areas of remediation, EPA will optimize the
dredging and capping components during remedial design
24
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to maximize the immediate risk reduction and long-term
effectiveness.
Based on anticipated dredge material production rates,
the current estimated construction period will extend over
four construction seasons and include dredging,
backfilling, and capping. It is anticipated that it will take
two years for remedial design and mobilization, so that
dredging may begin in 2015. Prior to construction, a
remedial design would be developed that specifies details
regarding the construction and implementation of the
remedy. Design plans would include Site health and
safety measures for the workers and a Community Health
and Safety Plan for the surrounding community. In
addition, habitat assessment would be conducted during
the design. Habitat would be reconstructed during
implementation of the remedy in accordance with the site-
specific habitat reconstruction plan.
After construction is completed, this alternative relies on
institutional controls (such as restrictions on activities that
could compromise the integrity of the cap such as
anchoring which can disturb the cap), long-term
monitoring,, and sedimentation to achieve the Remedial
Action Objectives. The fish consumption advisories will
continue to provide some measure of protection of human
health until PCB concentrations in fish are reduced to the
point where they can be relaxed or lifted. If monitoring
reveals any portion of the various caps has been eroded,
damaged areas would require maintenance/replacement.
If any portion of a capped area has been eroded,
monitoring and sampling will determine whether other
areas have been contaminated with PCBs released from
the damaged areas. Additional enhanced capping may be
undertaken to cover any areas that sampling shows
surface sediment PCB concentrations greater than or
equal to 1 mg/kg. Monitoring will also be conducted to
measure the success of habitat re-establishment. A
review of site conditions would be conducted at least once
every five-years, as required by CERCLA.
The present-worth cost for Alternative 6 was estimated in
the Analysis of Alternatives Report to be approximately
$243.1 million.
RATIONALE FOR SELECTION OF PREFERRED
ALTERNATIVE
The selection of the preferred alternative is accomplished
through the evaluation of the nine criteria as specified in
the NCP. EPA has evaluated the alternatives against the
first seven criteria. New York State is still evaluating
EPA's preferred remedy as presented in this Proposed
Plan. Consultation with SRMT regarding the Proposed
Plan was initiated prior to the release of the Proposed
Plan; however, the SRMT's acceptance of the preferred
remedy will be assessed during the comment period.
Community Acceptance will be evaluated after the
Proposed Plan is issued.
The preferred Alternative 6 is protective of human health
and the environment. Risk is reduced through removal of
PCB-contaminated sediment from the near shore area,
and by isolating PCBs in the main channel under caps.
PCB-contaminated sediments in the scour-prone areas of
the main channel will be isolated and stabilized by the
armored cap, which will protect those sediments from
future ice jam events. The modeling projects that the
target concentration of 0.36 mg/kg in fish, which is
protective of the average adult who consumes one fish
meal every two months, would be attained in seven years
from the start of the active remediation. The target
concentration of 0.26 mg/kg in fish, which is protective of
the average adult who consumes one fish meal per
month, would be attained eight years after the start of
active remediation. These time periods are significantly
shorter compared to Alternatives 1 (No Further Action)
and 2 (MNR), under which attainment of the targets are
greater than the 30-year modeling time frame. The time
frames also are significantly shorter than the projected
times to reach the target concentrations under Alternatives
7-10, which include main channel dredging. The
protectiveness of the preferred alternative is further
enhanced through the implementation of institutional
controls, such as the fish consumption advisories.
According to the model projections, none of the
alternatives will meet the human health PRG of 0.05
mg/kg PCBs within the 30-year modeling time frame.
Also, although it was not modeled, none of the
alternatives, including Alternative 6, are anticipated to
meet the lower Mohawk human health PRG of 0.01 mg/kg
within the 30-year modeling time frame.
The preferred alternative is also protective of the
environment, because it would reduce the PCB
concentrations in fish to concentrations that are within the
range of 0.22 to 0.44 mg/kg (wet weight) in whole-body
fish and a range from 0.1 to 0.2 mg/kg (wet weight) PCBs
in brown bullhead fillet within the 30-year modeled time
frame, which are the PRGs for ecological exposure. Thus,
the preferred alternative is protective of the birds, fish, and
mammals that live in and near the lower Grasse River.
The preferred Alternative 6 is the most cost-effective of
the remedial alternatives for the risk reduction achieved.
Alternatives 1 and 2 are not sufficiently protective of
human health and the environment. While Alternatives 3,
4, and 5 are less expensive than Alternative 6, they raise
concerns regarding the change in the near shore
bathymetry. The preferred alternative is more cost-
effective than Alternatives 7 through 10, which include
more dredging at a higher cost but which are projected to
take longer to reach the interim target levels for PCBs in
fish.
The preferred Alternative 6 maximizes the benefit gained
from successful dredging in the near shore where minimal
or no residual PCBs are anticipated, such that near shore
capping after dredging will not be needed. The preferred
alternative would permanently and reliably remove
25
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approximately 109,000 cy of contaminated sediments from
the near shore. The area where the near shore is
dredged will be backfilled to grade and habitat
reconstruction will re-establish valuable and diverse
habitat for biota.
The preferred alternative will comply with the location-
specific and action-specific ARARs identified, as well as
the two out of four chemical-specific ARARs. However,
two chemical-specific ARARs are not expected to be met
due to site background PCB loading conditions.
Therefore, it is expected that technical impracticability
waivers will be required for the NYS water quality PCB
standards for the protection of human consumers of fish
(0.001 ng/L) and for the protection of wildlife (0.12 ng/L).
EPA is considering whether to treat the SRMT's sediment
cleanup standard 0.1 mg/kg for PCBs in sediments as a
"relevant and appropriate" requirement for the cleanup. It
is doubtful that the SRMT sediment standard can be
achieved, and it is expected that a technical
impracticability waiver would be required if the SRMT
standard is identified as an ARAR. Even the most
aggressive dredging alternatives would require these
same waivers.
The preferred alternative is technically and
administratively feasible and implementable. All of the
necessary personnel, equipment, and services required
are expected be readily available.
The preferred alternative will be protective of human
health and the environment, will achieve target
concentrations for PCBs in fish faster than alternatives
that include dredging of the main channel, is protective in
the long-term, complies with ARARs (with two justified
waivers), and is cost-effective. The preferred alternative
includes dredging of near shore areas where dredging
can effectively remove contaminated sediments from the
environment, and effectively isolates PCBs in the main
channel, where highly contaminated sediment is present
over hard bottom material such as bedrock, glacial till,
and/or marine clay that interferes with effective dredging.
EPA believes that, the preferred remedy will provide the
best balance of tradeoffs among alternatives with respect
to the evaluating criteria.
The environmental benefits of the preferred remedy may
be enhanced by consideration, during the design, of
technologies and practices that are sustainable in
accordance with EPA Region 2's Clean and Green Energy
Policy and NYSDEC's Green Remediation Policy8. This
will include consideration of green remediation
technologies and practices.
In furtherance of EPA's current Environmental Justice
policy, known as EJ 2014, Region 2 has identified
Akwesasne, the territory of the SRMT, as a Potential
8 See http://epa.aov/reaion2/superfund/areen remediation and
http://vwvw.dec.nv.gov/docs/remediation hudson pdfZder31.pdf.
Environmental Justice Community. Members of the
SRMT have been burdened by the environmental and
health impacts of pollution in the local river systems,
including the Grasse River, due primarily to the
consumption of local fish contaminated with PCBs.
Members of the SRMT consume such fish at higher rates
than the general population. The potential for adverse
health impacts from consumption of fish contaminated
with PCBs is well documented.
In order to decrease these environmental and health
burdens, and mitigate harm, EPA is proposing an
enhanced post-remedial monitoring and action plan
regarding the levels of pollutants in fish, wildlife habitat,
and the permanence and effectiveness of the remedy for
the Grasse River including in particular the cap. If such
monitoring indicates that an element of the remedy has
failed, or is not achieving the interim targets set out in the
Proposed Plan, and/or that the remedy is not protective of
human health and the environment, then EPA will take
appropriate further action to achieve an effective and
protective outcome.
Based on information currently available, EPA believes
the preferred alternative meets the threshold criteria and
provides the best balance of tradeoffs among the
alternatives with respect to the balancing and modifying
criteria. EPA expects the preferred alternative to satisfy
the following statutory requirements of CERCLA §121(b):
1) be protective of human health and the environment; 2)
comply with ARARs (or justify a waiver); 3) be cost-
effective; 4) utilize permanent solutions and alternative
treatment technologies or resource recovery technologies
to the maximum extent practicable; and 5) satisfy the
preference for treatment as a principal element (or justify
not meeting the preference). EPA's statutory preference
for treatment was considered as part of this preferred
remedy. EPA does not believe that treatment of the
sediments is practicable or cost effective given the
widespread nature of the sediment contamination in the
Grasse River and the high volume of sediment that is
being addressed.
26
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REFERENCE: MASSENA, NEW YORK-ONTARIO USGS QUAD. 1964 RAQUETTE RIVER, NEW YORK-ONTARIO USGS QUAD. 1964
Approximate Scale: 1" = 3,000'
GRASSE RIVER STUDY AREA
MASSENA, NEW YORK
GRASSE RIVER STUDY AREA
LOCATION MAP
FIGURE IS FROM THE ALTERNATIVES
OF ANALYSIS REPORT, COURTESY
OF ALCOA
-------
APPROXIMATE 2007 ICE BREAKING-
Si f=
LI. O
1' k
z o
O
5 01
H CT
15
i <0 I
o o
I
LEGEND:
DIRECTION OF RIVER FLOW
1992 SEDIMENT PROBING TRANSECTS
NOTE:
1. BASE MAP TAKEN FROM PLANIMETRIC MAPPING
PREPARED BY L0CKW00D MAPPING, INC. USING
11/9/92 AERIAL PHOTOGRAPHY. RIVER OUTLINE
EXTENDING FROM THE ROUTE 37 BRIDGE
APPROXIMATELY 6000 FEET DOWNSTREAM (SOUTHWEST
GRASSE RIVER STRETCH) DERIVED FROM BASEMAP
PREPARED BY ECOLOGY AND ENVIRONMENT, INC. AND
SHOULD BE CONSIDERED APPROXIMATE ONLY.
GRAPHIC SCALE
GRASSE RIVER STUDY AREA
MASSENA, NEW YORK
LOCATIONS OF LOWER GRASSE RIVER
PILOT/DEMONSTRATION PROJECTS
FIGURE IS FROM THE
ANALYSIS OF ALTERNATIVES REPORT,
COURTESY OF ALCOA
-------
DONDERO
tributary
WC012
OUTFALL
002 ^/^
MASSENA
INTAKE DAM
IWPPMil
OUTFALL
001
BRIDGE 218
£>/P0WER
/ DAM
DWWTP/
RIVER
WQ131 SEE NOTE 2)
WC011
LEGEND:
DIRECTION OF RIVER FLOW
1992 SEDIMENT PROBING TRANSECTS
WATER COLUMN
SAMPLING LOCATION
NOTES:
1. BASEMAP TAKEN FROM PLANIMETRIC MAPPING PREPARED BY LOCKWOOD
MAPPING, INC. USING 11/9/92 AERIAL PHOTOGRAPHY. RIVER OUTLINE
EXTENDING FROM THE ROUTE 37 BRIDGE APPROXIMATELY 6000 FEET
DOWNSTREAM (SOUTHWEST GRASSE RIVER STRETCH) DERIVED FROM
BASEMAP PREPARED BY ECOLOGY AND ENVIRONMENT. INC. AND SHOULD
BE CONSIDERED APPROXIMATE ONLY.
2. WATER COLUMN SAMPLES HAVE BEEN COLLECTED AT WC131 SINCE 2000.
BETWEEN 1996 AND 1999. SAMPLES WERE COLLECTED FROM WC007A,
WHICH IS LOCATED APPROXIMATELY 500 FEET DOWNSTREAM OF WC131.
3000*
GRAPHIC SCALE
6000*
GRASSE RIVER STUDY AREA
MASSENA, NEW YORK
FIGURE IS FROM THE
ANALYSIS OF ALTERNATIVES REPORT,
COURTESY OF ALCOA
WATER COLUMN MONITORING
LOCATIONS
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CO - C: \D_Drive\alcgra\GI S\Alternatives_maps_20120523. mxd
GRAPHIC SCALE
850 1,700
~ Feet
3,400
LEGEND
Near Shore Capping
Capping
Armored Capping
Dredging / Capping
Dredging / Annored Capping
Dredging / Backfilling to Grade
~~ Sediment Type
Grasse River + Tributaries Shoreline
—¦ Roads
Dams
Alcoa Buildings
—- Bridges
Sediment Probing Transects
Figure 5
Alternative 6:
T1-T72 Near Shore
Dredging/Backfilling and
Main Channel Capping
Figure is from the
Analysis of Alternative Report,
courtesy of Alcoa.
Sept. 201;2
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