SUPERFUND
Cleaning Up New England
PROPOSED PLAN
Nyanza Chemical Waste Dump
Sudtury River, MA
U.S. EPA | HAZARDOUS WASTE PROGRAM AT EPA NEW ENGLAND
THE SUPERFUND PROGRAM protects human
health and the environment by locating, investigating, and cleaning up
abandoned hazardous waste sites and engaging communities throughout
the process. Many of these sites are complex and need long-term cleanup
actions. Those responsible for contamination are held liable for cleanup
costs. EPA strives to return previously contaminated land and ground-
water to productive use.
YOUR OPINION COUNTS:
OPPORTUNITIES TO COMMENT ON THE PLAN
EPA is accepting public comment on this
proposal from June 25 2010 through July 26,
2010. The following two public informational
meetings will include a presentation describing
the proposed plan, followed by a question and
answer session.
A supplemental public informational meeting
will focus on the computer model (its calibra-
tion, sensitivity, and sources of uncertainty)
that was developed to evaluate different
remedial alternatives.
EPA will begin a formal 30-day public com-
ment period. A Public Hearing has been
scheduled for 7:00 p.m. Monday, July 19,
2010 at the Framingham Town Library
and the public has an opportunity to make
oral comments for EPA to consider. You may
also submit written comments - see page 11
to find out how.
Public Informational Meeting - Sudbury
Monday, June 21, 2010 at 7:00 p.m.
National Wildlife Refuge Complex (GMNWR)
73 Weir Hill Road, Sudbury, MA
Public Informational Meeting - Framingham
Tuesday, June 22, 2010 at 7:00 p.m.
Framingham Town Library
49 Lexington Street, Framingham, MA
Informational Meeting on Computer Modeling
Thursday, June 24, 2010 at 7:00 p.m.
National Wildlife Refuge Complex (GMNWR)
73 Weir Hill Road, Sudbury, MA
For further information about these meet-
ings, call Jim Murphy of EPA's Community
Affairs office at (617) 918-1028, or toll-free at
1-888-372-7341,
THE PROPOSED PLAN
AT A GLANCE
After careful study of the impacts of mercury
released to the Sudbury River from the Nyanza
Chemical Waste Dump Superfund site, and in
consideration of the contaminant reduction ac-
complished by cleanup activities at other parts
of the site, EPA proposes the following cleanup
actions for the Sudbury River, which EPA has
defined as "Operable Unit 4" (or "OU4") of the
Nyanza site. This Proposed Cleanup Plan address-
es mercury contamination in fish tissue, which
is where mercury from the river accumulates.
These contaminated fish pose an unacceptable
health risk to recreational anglers who consume
them. There are no other unacceptable risks to
humans or to animals and plants in the river. Con-
sistent with actions at other contaminated sedi-
ment sites, this proposed cleanup plan relies on
a combination of different cleanup alternatives
that apply only to specific "reaches" of the river
(refer to the attached map). The Proposed OU4
Cleanup action consists of:
continued >
KEY CONTACTS:
DANIEL KEEFE
Project Manager
(617) 918-1327
keefe.daniel@epa.gov
JIM MURPHY
Superfund Community
Involvement
(617) 918-1028
murphy.jim@epa.gov
DAVID BUCKLEY
MassDEP Project Manager
(617) 556-1184
david.buckley@state.ma.us
GENERAL INFO:
EPA NEW ENGLAND
5 Post Office Square
Suite 100
Boston, MA 02109-3912
(617) 918-1111
www.epa.gov/region 1/
TOLL-FREE
CUSTOMER SERVICE
1-888-EPA-7341
&EPA
United States
Environmental Protection
Agency New England
printed on 100% recycled paper, with a minimum of 50% post-consumer waste, using vegetable-based inks
EPA-901-F-00-000
June 2010
SDMS DocID 466645
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SUPERFUND | HAZARDOUS WASTE PROGRAM AT EPA NEW ENGLAND
PROPOSED PLAN
INTRODUCTION & HISTORY
The Nyanza Site was occupied from 1917 through 1978 by several companies that manu-
factured, among other things, textile dyes and dye intermediates. During the period of
operation, large volumes of chemical waste were disposed in burial pits, below ground
containment structures, and various lagoons scattered throughout the "Hill" section of the
site. Wastes included partially treated process water, chemical sludge, solid process wastes,
solvent recovery distillation residue, numerous organic and inorganic chemicals including
mercury, and other products. Process chemicals that could not be reused or recycled
were also disposed of on-site or discharged into the Sudbury River through a small stream
referred to as Chemical Brook.
Mercury was used as a catalyst in the production of textile dyes from 1917 to 1978. Ap-
proximately 2.3 metric tons (2,300 kg) of mercury were used per year from 1940 to 1970,
with a total of 45 to 57 metric tons of mercury released to the Sudbury River during this
period. From 1970 until the facility closed in 1978, wastes were treated on-site and waste-
water was discharged to Ashland's town sewer system. These revised treatment practices
reduced the quantity of mercury released to the Sudbury River to between 23 and 30 kg
per year or about 200 kg (440 pounds) during the final eight-year period.
In 1982, the Nyanza site was placed on the National Priorities List (NPL) by the U.S. EPA.
EPA has since divided the site into four operable units, or OUs. This division into OUs
has allowed EPA to have different teams work separately on discrete parts of the site.
OU1 consists of the former Nyanza plant, inclusive of the landfill at the site; OU2 addresses
contaminated groundwater; OUS addresses contamination in the Eastern Wetland,
Chemical Brook, Trolley Brook and Outfall Creek; and OU4 addresses contamination in
the Sudbury River.
EPA has completed the cleanup actions selected for OU 1 (consolidation of sludges under an
impermeable cap) and OUS (removal of contaminated sediments in the wetland, brook and
creek). Cleanup work is ongoing at OU2 (extraction of contaminants from groundwater
and installation of systems to mitigate vapors that might otherwise pass from contaminated
groundwater into overlying homes). The cleanup action proposed in this plan is for OU4,
the Sudbury River.
EPA has been studying the Sudbury River since the mid-1990s, issuing several research
papers, three risk assessments, a computer model that shows how mercury moves through
the river into fish, and most recently the feasibility study that led to this proposed plan.
Because OU4 is large - the river spans 26 miles from the Nyanza site to its confluence with
the Assabet River - the study area was divided into 10 "reaches." A "reach" typically rep-
resents a section of the river with a specific set of hydrological properties - an impounded
area, a fast flowing area or, in the case of Great Meadows National Wildlife refuge, an
expansive wetland.
Enhanced Natural Recovery (ENR)
consisting of the addition of a 6-inch
layer of sand in a portion of Reach 3
(i.e., Framingham Reservoir 2) with the
highest levels of mercury contamination
in sediment. The addition of a sand layer
effectively accelerates natural recovery
processes by which contaminated
sediment are normally buried and
diluted.
Monitored Natural Recovery (MNR) in
other reaches of the river. Throughout
much of the river, fish are expected to
become safe for regular consumption
within a reasonable timeframe through
natural recovery and without any active
remediation; EPA would continue to take
samples to monitor this progress.
Limited Action for Reach 8 including
monitoring of contamination levels in fish
to insure they are stable or declining,
even if they do not decline to levels that
would permit regular consumption by
recreational anglers.
"Institutional Controls" throughout the
river - i.e., community outreach as well
as posting and maintenance of signs
advising against fish consumption where
fish are unsafe for regular consumption.
There are currently multiple State fishing
advisories due to mercury.
No Action for Reaches 5 and 7 since
there are no unacceptable risks to either
a child or an adult recreational angler in
these reaches.
Reviews will also be conducted every
five years to evaluate the effectiveness
and adequacy of the remedial measure.
The cost of the proposed remedy is estimated at
$8.5 million. A more detailed description of the
proposed plan begins on page 7.
EPA is also seeking comment on EPA's finding
that the cleanup represents the least-damaging
practical alternative regarding potential impacts
to the aquatic environment in and around the
river. Page 9 contains more detail regarding
this finding. This Proposed Plan summarizes
parts of the Draft Feasibility Study. The entire
text of the Feasibility Study can be found at
www.epa.gov/region1/superfund/sites/
nyanza. In September 2010, EPA expects to
have reviewed all public comments and will issue
a Record of Decision (ROD) describing the cho-
sen cleanup plan. The ROD and a summary of
responses to public comments will then be made
available to the public via the internet and at the
site information repositories and at the Ashland
Public Library.
In accordance with the Comprehensive Envi-
ronmental Response, Compensation, and Li-
ability Act (Section 117), the statute which cre-
page 2
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SUPERFUND | HAZARDOUS WASTE PROGRAM AT EPA NEW ENGLAND
PROPOSED PLAN
Remedial Alternatives Summary
Nyanza Chemical Waste Dump Superfund Site
Operable Unit 4 - Sudbury River
Ashland, Massachusetts
Alternatives
Alternative 1
Alternative 2
Alternative 3A
Alternative 3B
Alternative 3C
Alternative 4A
Alternative 4B
Alernative 5A
Alternative 5B
Alternative 5C
Alternative 5D
Remedial Action
No Action
Limited Action (LA)
Sitewide Monitored Natural Recovery (MNR)
Enhanced Natural Recovery in Reach 3 > 10ppm
Enhanced Natural Recovery in Reaches 3, 4 and
6 > 2ppm
In Situ Containment in Reach 3
In Situ Containment in Reaches 3, 4 and 6
Dredging > 10ppm in Reach 3
Dredging > 10ppm in Reach 3, In Situ Capping in
Reaches 3, 4 and 6
Dredging > 2ppm in Reach 3
Dredging > 2ppm in Reaches 3, 4 and 6
Sudbury River Reaches
2
NA
LA
MNR
MNR
MNR
MNR
MNR
MNR
MNR
MNR
MNR
3
NA
LA
MNR
Thin Layer
Placement
Thin Layer
Placement
Capping
Capping
Partial
Removal
Partial
Removal/
Capping
Removal
Removal
4
NA
LA
MNR
MNR
Thin Layer
Placement
MNR
Capping
MNR
Capping
MNR
Removal
5
NA
LA
NA
NA
NA
NA
NA
NA
NA
NA
NA
6
NA
LA
MNR
MNR
Thin Layer
Placement
MNR
Capping
MNR
Capping
MNR
Removal
7
NA
LA
NA
NA
NA
NA
NA
NA
NA
NA
NA
8
NA
LA
LA
LA
LA
LA
LA
LA
LA
LA
LA
9
NA
LA
MNR
MNR
MNR
MNR
MNR
MNR
MNR
MNR
MNR
10
NA
LA
MNR
MNR
MNR
MNR
MNR
MNR
MNR
MNR
MNR
Notes:
1) Reach 1 is upstream of the Nyanza source area and therefore is not included in this summary.
2) Since there was no actionable risk identified for Reaches 5 and 7 they are not included in this summary.
Hg = total mercury
MeHg = methylmercury
mg/kg = milligrams per kilogram
MNR = Monitored Natural Recovery
ated EPA's Superfund program, and the National
Contingency Plan Section 300.430(f)(2), this
document summarizes EPA's cleanup proposal.
For detailed information on the options evaluat-
ed for the site, see the Feasibility Study available
for review at the information repositories at the
Ashland Town Library and EPA's Five Post Office
Square office in Boston.
MERCURY:
WHERE IT COMES FROM,
WHAT IT DOES
Mercury in the environment comes from specific or
"point" sources such as Nyanza, from atmospheric
sources, and from other diffuse or "non-point"
sources. Combustion of municipal solid waste and
combustion of fossil fuels for power generation are
prime examples of atmospheric sources of mercu-
ry. Nationally, the northeast has been recognized
as an area of increased atmospheric deposition of
mercury. Recently there have been significant re-
gional and federal efforts to limit non-point sources
of mercury, including EPA's Clean Air Mercury
Rule, which creates performance standards and
establishes permanent, declining caps on mercury
emissions.
page 3
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SUPERFUND | HAZARDOUS WASTE PROGRAM AT EPA NEW ENGLAND
PROPOSED PLAN
Despite these efforts, mercury remains present in
the environment at levels that have led the Massa-
chusetts Department of Public Health (MassDPH)
to maintain a State-wide fishing advisory. The State-
wide advisory warns children and women who
are or may become pregnant (i.e., the populations
most sensitive to mercury) not to consume fish
from any body of fresh water in the State.
At the Sudbury River, the former Nyanza facility
presents an additional source of mercury. Thus, the
concentration of mercury in the Sudbury River sed-
iment (and as methylmercury in the surface water
and fish) is a combination of mercury from historic
Nyanza discharges as well as more recent atmo-
spheric deposition. Since 1986, in addition to the
state-wide fish advisory, MassDPH has established
a Sudbury River-specific fish advisory, which warns
all segments of the population (not just children and
women who are or may become pregnant) against
consumption offish from the Sudbury River. Both
advisories remain in effect today.
HOW MERCURY AFFECTS
YOUR HEALTH
There are several different types of mercury.
Although some are more dangerous than
others, all are toxic. While mercury does not pres-
ent a cancer risk to human health, it does have a
number of non-cancer health affects. Depending on
the type and amount, exposures to mercury can
damage the nervous system, brain, kidneys, liver
and immune system. One form of mercury, meth-
ylmercury, is extremely poisonous and can damage
the brain even at low levels of exposure. Children
are most sensitive to mercury toxicity The devel-
oping brains and nervous systems of children are
very sensitive to mercury and may be irreversibly
damaged by it. Children and adults can be exposed
to methylmercury by eating certain types of fish.
Children can also be exposed to mercury in the
womb if their mothers eat foods contaminated
with this toxin. Because of the high sensitivity to
developing children, mothers who are pregnant, or
may become pregnant, are similarly at an increased
risk for negative health effects from the consump-
tion of mercury-contaminated fish.
The concentration of mercury in fish and the associ-
ated risk to humans from consumption offish is not
directly proportional to the concentration of total
mercury in sediment. Most of the mercury that is
absorbed by fish is mercury that has combined with
organic matter in the river to form methylmercury,
a compound which is more "bio-available" (and
more toxic) than pure mercury. Certain parts of
the river are more efficient than others at convert-
ing pure or elemental mercury into methylmercury
- for example, the expansive wetlands in the Great
Meadows National Wildlife Meadows (Reach 8)
are an environment that is particularly efficient at
converting elemental mercury into the methylmer-
cury that tends to end up in fish tissue. This means
that fish in this part of the river have relatively high
mercury (i.e., methylmercury) concentrations even
though the sediment there is far less contaminated
than the sediment in other parts of the river.
RISK - WHY IS CLEANUP
NEEDED?
The only significant site-related risk to humans comes
from consuming mercury-contaminated fish on a fre-
quent basis (i.e., more than 25 meals per year). In a
risk assessment completed in 1999, EPA determined
that direct contact (e.g., swimming, wading, walking)
or incidental ingestion of mercury in surface water
or sediment was well below the level that would con-
stitute a significant risk to human health. EPA also
determined in a prior assessment that there were
no other Nyanza-related contaminants in the river
other than mercury that might constitute a signifi-
cant risk to humans.
The human health risk from the consumption of
mercury-contaminated fish was reported in the
2006 Supplemental Human Health Risk Assessment
and other follow-up studies. In EPAs determination
of human health risk, the average concentration of
mercury in fish within each reach was measured. This
was done by collecting 10 bass, 10 perch, and 10
catfish from each reach - more than 300 fish from
all 10 reaches. These particular species offish were
used because they are caught frequently and are tar-
get species for consumption. The human health as-
sessment also includes exposure assumptions - that
is, how much fish a person might eat in a year. Us-
ing data from comparable studies in Maine, EPA as-
sumed that a recreational angler; that is, the person
most likely to eat the most fish taken from the river,
would eat 50 fish meals per year, half of which would
come from the Sudbury River. This assumption is
conservative - for example, it assumes that children
would consume fish at this frequency notwithstand-
ing the state-wide fish advisory that warns children and
women who are or might become pregnant from eat-
ing any fish caught in any freshwater body in the State.
The risk assessment also calculated risks to subsis-
tence anglers - people assumed to rely on fish from
the Sudbury River for all or most of their protein in-
take. However, because EPA has found no evidence
of subsistence fishing in the Sudbury River, EPA has
decided not to base cleanup decisions on subsistence
fishing scenarios.
EPA uses standard toxicological data and other as-
sumptions (e.g., human body weight, fish filet weight)
to develop reach-specific "hazard index" (or "HI")
figures for non-cancer effects on human health; one
for a child and one for an adult, based on consump-
tion offish caught from each reach of the river. The
higher the HI, the higher the risk. Generally, an HI
greater than 1.0 indicates an unacceptable exposure
from eating fish in a given reach. The His for each
reach for both children and adult recreational anglers
are listed in the table below:
Hazard Index
C
Reach 1*
Reach 2
Reach 3
Reach 4
Reach 5
Reach 6
Reach 7
Reach 8
Reach 9
Reach 10
*Reach 1 is upstream of the Nyanza site and is one
of two reference areas.
1.0
1.8
2.1
1.3
0.9
1.3
1.0
1.3
1.5
1.4
0.5
1.0
1.2
0.7
0.4
0.7
0.5
0.7
0.9
0.7
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SUPERFUND | HAZARDOUS WASTE PROGRAM AT EPA NEW ENGLAND
PROPOSED PLAN
In general, risks throughout the river are low;
Reach 3 (Framingham Reservior 2) presents the
greatest risk. Specifically Reaches 2, 3, 4, 6, 8, 9,
and 10 were found to pose varying degrees of
risks to a child recreational angler. Only Reach 3
was found to pose an unacceptable risk to both
a child and adult recreational angler. The maxi-
mum HI for children was 2.1 and attributable
to fish caught and consumed from Reach 3. The
His for the other reaches were between 1 and
2, with Reaches 1, 5, and 7 at or below 1.0 for
children and adults.
EPA also evaluated whether contamination in
the river poses an unacceptable risk to the en-
vironment - that is to say animals which inhabit
or utilize the river - and found that it did not
pose a risk. The 2008 Final Supplemental Base-
line Ecological Risk Assessment reports the re-
sults of these studies. The assessment measured
the concentration of mercury in various media
(blood, feathers, eggs) for animals living in the
Sudbury River watershed as well as those which
reside in sediment (crayfish and mussels) and
surface water (fish). These concentrations were
then compared to literature values - i.e., values
in published research found to have "no effects"
or "low effects" on certain species. The majority
(225 out of more than 229 measurement end-
points) of the concentrations from the Sudbury
River samples were either below the "no effects
level" or below the "low effects level." Thus, the
ecological risk assessment concluded that con-
tamination in the Sudbury River is not likely to
result in population-level risk to animals or other
organisms in or adjacent to this resource.
RISK SUMMARY:
The only significant risk to human health
is from eating fish contaminated with
mercury, except in Reaches 5 and 7
where there are no risks to human
health. There is also no significant risk to
animals or other organisms in or
adjacent to the river.
There are no risks to human health from
direct contact (e.g., swimming, wading,
walking) or incidental ingestion of
mercury in surface water or sediment in
any part of the river.
EPA assumes that the maximum reason-
able exposure to mercury is to a child
and adult recreational angler, who is
assumed to consume 50 fish meals per
year, half of which are assumed to come
from the Sudbury River, consisting of
equal parts of 3 local species (bass,
perch and catfish)
Based on the preceding, a likelihood of
adverse health effects for the following
receptors were documented:
X to a child (in 7 reaches); and
X to an adult (in 1 reach).
REMEDIAL ACTION
OBJECTIVES FOR
SUDBURY RIVER
EPA has determined that the risk to recreation-
al anglers is an unacceptable threat to human
health. The OU4 Feasibility Study was devel-
oped to identify cleanup options to address
this threat. A first step in this process was to
develop remedial action objectives (RAOs) -
goals by which cleanup alternatives identified
in the Feasibility Study can be evaluated. The
RAOs for the Sudbury River are (1) to prevent
the ingestion of mercury-contaminated fish to
the extent that such ingestion would result in
an unacceptable risk to human health; and (2)
to reduce the amount of mercury available to
fish in sediment and/or surface water to ensure
mercury concentration in fish tissue no longer
presents an unacceptable risk, except in Reach
8. According to the risk calculations described
above, mercury concentrations in fish must
be reduced to 0.48 parts per million (ppm, or
milligrams per kilogram) to avoid unacceptable
risks to a child recreational anglers, the most
sensitive population.
The first RAO focuses on mercury concentra-
tions in fish, because the only unacceptable risk
is from consumption of these fish; prevention of
consumption is one way to achieve the neces-
sary risk reduction. The second RAO focuses on
Sudbury River
sediment and/or surface water. This is because
sediment cleanups are one of the more effective
ways (apart from discouraging fish consumption)
of cleaning up surface water, which in turn is es-
sentially the only way to make fish tissue less
contaminated and safe for human consumption.
This second RAO has an exception for Reach
8, the Great Meadows Wildlife Refuge. In this
reach, sediment concentrations are low (gener-
ally between 1 and 3 ppm), yet fish tissue con-
centrations remain marginally above safe levels
(HH1.3 for a child angler). EPA believes that
the risk in Reach 8 is largely attributable not to
Nyanza mercury in sediment, but a) to ongo-
ing mercury deposits from the atmosphere and
other non-point sources and b) to the chemical
and biological conditions in this wetland, which
convert even small amounts of mercury in the
reach into significant concentrations of methyl-
mercury in fish. In fact, it appears that even if
natural recovery processes eliminated unaccept-
able risks to human health attributable to Nyan-
za-related mercury, fish from this Reach might
still be unsafe to eat due to ongoing atmospheric
page 5
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SUPERFUND | HAZARDOUS WASTE PROGRAM AT EPA NEW ENGLAND
PROPOSED PLAN
pollution. On this basis, EPA has determined that
it is inappropriate to clean up sediment and/or
surface water in Reach 8, because doing so is un-
likely to significantly reduce fish tissue concentra-
tions. EPA's only goal in Reach 8, therefore, is
the first RAO, which aims to prevent ingestion of
contaminated fish,
EPA believes that, over time, risks in Reach 8
from Nyanza-related contamination should at-
tenuate, but hydrological factors make fish in
this reach vulnerable to even small amounts of
mercury contamination, whether from the atmo-
sphere or other non-point sources. As part of
its proposed remedy for the river, EPA will con-
tinue to monitor fish tissue data to ensure that
fish tissue concentrations in Reach 8 decrease or
at least remain more or less stable over time.
EPA will also ensure that institutional controls
remain in place to advise against consumption of
contaminated fish.
DESCRIPTION OF CLEANUP
ALTERNATIVES FOR THE
SUDBURY RIVER
In the Feasibility Study (FS) EPA considered a
full range of options to address contamination
and risks at a Superfund site before selecting a
remedy Only those alternatives that meet EPA's
threshold criteria of protecting human health and
complying with other environmental laws are
summarized below, except that a "no action" al-
ternative is also presented as a baseline. A more
detailed description and analysis of each alter-
native developed is presented in the Feasibility
Study, which is also available for public comment.
The cleanup options, or remedial alternatives, that
were evaluated in detail and were considered for
the Sudbury River are summarized below.
Alternative 1: No Action
The No Action alternative would not involve any
type of work other than Five Year Reviews (i.e.,
reports every five years by EPA on conditions in
the river). No monitoring data would be generat-
ed and no institutional controls (beyond those in
existence) would be implemented to potentially
reduce or limit the consumption of contaminated
fish. EPA is required to evaluate this alternative
by EPA's Superfund regulations, so as to provide
a baseline for comparison to other alternatives.
Alternative 1 Cost: $ 0
Alternative 2: Limited Action
The Limited Action alternative is the same as
Alternative 1, but relies on institutional controls
Sudbury River
- e.g., posting offish advisory signs, public out-
reach and education - as a means of discourag-
ing fish consumption and thereby reducing the
risk to human health and may include monitor-
ing. There are naturally-occurring processes that
are expected to reduce mercury concentrations
in sediment and ultimately to reduce concentra-
tions of mercury in fish. These processes include
physical processes (sedimentation and burial of
contaminated sediments) and biological (bio-
degradation) and chemical (sorption) processes
that act together to reduce the risk posed by a
contaminant. In most reaches, fish contamination
would decline to acceptable levels within a rea-
sonable timeframe - i.e., within approximately
30 years through these natural processes. But
in Reach 3 it is expected to take more than 70
years, and in Reach 8 fish contamination is ex-
pected to remain at unacceptable levels for a
much longer period of time due to atmospheric
sources of mercury.
Alternative 2 Cost: $ 192,000
Alternative 3: Monitored Natural Recovery
and Enhanced Natural Recovery
Three variations of this alternative were evalu-
ated (Alternatives 3A, 3B, and 3C). Alternative
3A utilizes Monitored Natural Recovery (MNR)
for all reaches except Reach 8. This would con-
sist of monitoring natural processes to confirm
that reductions in fish tissue concentrations are
occurring in those reaches where reductions are
expected. Monitoring would also be conducted
in Reach 8 to insure concentrations are stable
or decreasing. Institutional controls (signs, public
outreach) would also be implemented. Alterna-
tives 3B and 3C are similar to Alternative 3A,
except they contemplate the placement of a thin
layer of sand on top of more highly contaminat-
ed sediments. The use of a sand layer in conjunc-
tion with monitoring is referred to as Enhanced
Natural Recovery (ENR). In Alternative 3B a
6-inch thin layer of sand would be placed at loca-
tions in Reach 3 where total mercury in surface
sediment uniformly exceeds 10 ppm, which con-
stitutes about 70% of the reach. Alternative 3C
evaluated the placement of sand over sediments
with mercury above 2 ppm; this includes all of
Reach 3, and large portions of Reach 4 and 6.
Under alternatives 3B and 3C, the level of mer-
cury contamination in fish in all reaches except
Reach 8 is expected to decline to acceptable lev-
els within a reasonable timeframe (i.e., less than
30 years).
Alternative 3A Cost: $1,070,000
Alternative 3B Cost: $8,500,000
Alternative 3C Cost: $22,190,000
Alternative 4: In-situ Containment
Alternatives 4A and 4B are similar to Alternative
3A; however they consist of two variations of
"in-situ containment." In-situ containment relies
on the installation of an isolation barrier over
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SUPERFUND | HAZARDOUS WASTE PROGRAM AT EPA NEW ENGLAND
PROPOSED PLAN
contaminated sediment. In-situ containment is
different from a thin layer of sand: while the
sand would mix with and dilute contaminated
sediment, the in-situ containment would function
to prevent direct contact with contaminated
sediment, reducing resuspension and providing
chemical and physical isolation of contaminants.
Alternative 4A would apply the barrier over
sediments in Reach 3 only (Reservoir 2) where
mercury concentrations exceed 2 ppm; Alterna-
tive 4B would apply the barrier over sediments
exceeding 2 ppm of mercury in Reaches 3, 4 and
6. Institutional controls (signs, public outreach)
would also be implemented and regular monitor-
ing would be included in both alternatives. Under
alternatives 4A and 4B, fish contamination in all
reaches except Reach 8 is expected to decline to
acceptable levels within a reasonable timeframe
(i.e., less than 30 years).
Alternative 4A Cost: $24,310,000
Alternative 4B Cost: $48,910,000
Alternative 5: Sediment Removal
Alternatives 5A through 5D consist of four
variations of a sediment removal. Sediment
removal (via dredging) relies on the physical
removal of mercury-contaminated sediments
to reduce the mercury concentration in fish.
Some of the removal alternatives would be
implemented in tandem with other technolo-
gies, such as containment. Specifically, Alter-
native 5A contemplates removal of sediment
with mercury greater than 10 ppm (regard-
less of depth) and would apply only to Reach
3 (Reservoir 2). Alternative 5B evaluates the
effectiveness of removing Reach 3 sediments
with mercury greater than 10 ppm and capping
lesser-contaminated portions of Reach 3 as well
as portions of Reach 4 and Reach 6. Alternative
5C contemplates sediment removal in Reach
3 where mercury is greater than 2 ppm - ef-
fectively the entire reach. Alternative 5D, the
most comprehensive removal alternative, evalu-
ates removal of sediment having mercury con-
centration greater than 2 ppm from Reaches 3,
4 and 6. In all of these alternatives, institutional
controls (signs, public outreach) would be im-
plemented along with regular monitoring activi-
ties. Under all these alternatives, 5A through
5D, fish contamination in all reaches except
Reach 8 is expected to decline to acceptable
levels within a reasonable timeframe (i.e., less
than 30 years).
Alternative 5A Cost: $59,710,000
Alternative SB Cost: $88,510,000
Alternative 5C Cost: $99,820,000
Alternative 5D Cost: $213,920,000
A CLOSER LOOK
AT EPA'S PROPOSAL
After careful study of the remedial alternatives
evaluated for the Sudbury River, EPA proposes
Alternative 3B as the final remedy. This is based
on EPAs analysis of the nine criteria for remedy
selection prescribed by the National Contingency
Plan (NCP); this analysis is provided on page 9.
Alternative 3B includes:
Enhanced Natural Recovery (ENR), or
the placement of 6-inch layer of sand
over sediments in Reach 3 that have at
least 10 ppm of mercury contamination,
to be followed by regular monitored
natural recovery. This area is located
north of the Fountain Street Bridge and
extends to the Reservoir No. 2
(Brackett Reservoir) dam.
Monitoring of natural recovery processes
(MNR) in the other reaches of the river,
excluding Reach 8 (Great Meadows
National Wildlife Refuge) and Reaches 5
and 7 (where there is no significant risk).
Monitoring of Reach 8 to ensure
mercury concentrations in fish tissue
are stable or decreasing. (This
monitoring program is not referred to
as MNR because it is unclear whether
natural processes are adequate to allow
this part of the river to fully recover.)
Implementation of institutional controls
(i.e., posting offish advisory signs and
public outreach to discourage excessive
consumption of contaminated fish)
throughout the river.
Periodic Five-Year Reviews of remedy
protectiveness and performance.
ENR: Enhanced Natural Recovery consists
of the placement of a thin layer of sand over
existing contaminated sediment that exceeds
mercury concentrations of 10 ppm. The sand
would be placed in the downstream section of
Reservoir 2, located in Reach 3 between Foun-
tain Street and the Reservoir No. 2 Dam. The
area is estimated to be approximately 84 acres;
it is the only part of the river, other than Reach 8,
where natural processes alone are not expected
to be adequate over a reasonable period of time
to eliminate unacceptable risks from consuming
fish. The placement of sand in this quantity is
anticipated to be equal to approximately 400
years of natural sedimentation, which should
result in a significant dilution of mercury concen-
trations in sediment and thus in lower fish tissue
contamination. Because excess water from the
reservoir flows over the dam continually (even
in non-flood conditions), adding sand to the
bottom is not expected to increase the surface
water level in the reservoir or result in any loss
of any flood storage capacity. During pre-design
studies, additional analysis regarding grain size
and sediment stability may be required as well
as studies to determine the optimum substrate
to encourage re-colonization of the sand layer
by benthic organisms.
MNR: Monitored Natural Recovery is pro-
posed for other river reaches, excluding Reach
8, Reach 5, and Reach 7 (the latter two due to
the lack of actionable risk in those reaches). Ac-
cording to EPAs computer model, fish tissue con-
tamination is projected to continue to attenuate
such that the target fish tissue concentration of
mercury (which should allow for unlimited recre-
ational angling) should be achieved in a reasonable
amount of time (i.e., less than 30 years) in the
reaches where MNR is proposed. This is unlike
Reach 3, where MNR alone is not expected to
achieve the target fish tissue concentration with-
out the enhancements identified above. It should
be noted that certain reaches (i.e., Reaches 2, 9,
and 10) were not part of the computer model's
simulation of MNR. However, the rate of natu-
ral recovery in these reaches is anticipated to be
similar to the modeled reaches, and thus these
reaches should attain remedial goals over similar
timeframes (i.e., less than 30 years).
page 7
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PROPOSED PLAN
Fish Tissue Monitoring: A baseline of fish
tissue concentrations was established during
previous site investigation studies. As part of the
proposed remedy, monitoring will be conducted
in all reaches (except possibly Reaches 5 and 7,
where there is no unacceptable risk to human
health) and will likely consist of the collection of
a single species (bass) every five years and three
species (bass, perch and catfish) every 10 years
so as to allow for the recalculation of human
health risk. The first round of monitoring activi-
ties will be performed five years after the Record
of Decision is issued.
Limited Action in Reach 8: The Great Mead-
ows National Wildlife Refuge is a unique hydro-
logical environment encompassing 3,600 total
acres, of which approximately 1,100 aces are
routinely (annually) flooded. As discussed above,
wetlands, like those in GMNWR, have a signifi-
cantly higher rate of methylation than other river
environments. The wetlands are very efficient at
converting mercury contamination into methyl
mercury, where it is much more readily absorbed
into the food chain. Concentrations of mercury
in fish in Reach 8 are elevated even though the
sediment concentration of mercury is relatively
low (between 1 and 3 ppm). Because of this
efficient methylation, and because of on-going
atmospheric deposition of mercury, EPAs com-
puter model predicts that even a very extensive
attempt to excavate contaminated sediments
would result in only marginal reductions in fish
tissue concentrations. In light of these facts, and
in light of the relatively low risks, EPA proposes
to rely on institutional controls (signs, public
outreach discouraging consumption of contami-
nated fish from the Sudbury River) to address
contamination in Reach 8. EPA will continue to
monitor Reach 8, to verify that fish tissue con-
centrations are declining or stable. EPA believes
that, over time, risks in Reach 8 from Nyanza-
related contamination will attenuate but that fish
may continue to be contaminated at unsafe lev-
els, due to the interaction between atmospheric
pollution and conditions in the reach that tend to
favor mercury accumulation in fish tissue.
Institutional Controls:
The current state fishing advisory and local Sud-
bury River fish advisory will function as a compo-
nent of informing the population against eating
mercury-contaminated fish taken from the Sud-
bury River. If these measures were discontinued,
EPA would evaluate the need for additional mea-
sures. EPA will also implement a public outreach
and education program and install signs to en-
sure safe consumption habits are followed.
Five-Year Reviews:
EPA would perform Five-Year Site reviews to
confirm the effectiveness and adequacy of the
above measures.
IMPACTS TO THE LOCAL
COMMUNITY DURING
REMEDY IMPLEMENTATION
Remedial activities are expected to have minimal
impact on the adjacent communities of Ashland
and Framingham. Alternative 3B - Enhanced
Natural Recovery (ENR) entails the placement
of an approximately 6-inch-thick layer of sand in
the downstream portion of Reach 3 (Reservoir
No. 2) between the Fountain Street bridge and
the Reservoir No. 2 Dam (refer to attached Fig-
ure); this area is approximately 84 acres. This
will involve the use of heavy equipment, trans-
portation of materials used for capping, and
construction of a temporary staging area. Traf-
fic and noise impacts will be minimized to the
extent possible. Monitoring activities will be con-
ducted every five years and will have virtually no
impacts on the community.
A variety of potential staging and work areas
were evaluated in the FS; however, one area
looks to be the most favorable and is included
in this Proposed Plan to illustrate one poten-
tial option for implementation of the proposed
remedy. This area is approximately 2.5 acres
and is located just south of the Sudbury River
and Fountain Street (near the Fountain Street
Bridge). Materials could be delivered to this area
by road or possibly by rail. Sand delivery by rail
may be both cost effective as well as reduce im-
pacts to local traffic patterns. The use of rail or
trucking and the specific staging location will be
developed during the remedial design phase of
the cleanup.
The staging area may consist of a large dock on
piers and will be used to store and transfer sand
to the actual placement equipment. Depending
on the location of the waterfront staging area
as well as method of sand delivery (rail versus
truck) a conveyor system could be used to move
material from the primary staging area (south
of Fountain Street) to the waterfront staging
area. In that way re-routing of traffic on Fountain
Street could likely be avoided. The placement
of the sand can be completed using a variety of
methods. It is likely that sand from the water-
front staging area would be transferred to a mo-
bile (floating) barge. The mobile barge would be
used to applied sand to the bottom sediments
via hydraulic (wet) methods such as a by mixing
sand with water and applying as a slurry through
a pipe, or by mechanical (dry) methods such as
broadcast spreading - such as is typically used
when fertilizing. A variety of equipment is available
Sudbury River
page 8
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SUPERFUND | HAZARDOUS WASTE PROGRAM AT EPA NEW ENGLAND
PROPOSED PLAN
that can be used for both and the final methodol-
ogy will be determined during remedial design.
Since some intrusive work would be required,
best work practices would be utilized to protect
surrounding environmental receptors from erod-
ing soil and/or sediment as well as stormwater
run-off from staged materials. Engineering con-
trols such as hay bales or silt curtain would be
implemented as a means of reducing the trans-
port of contaminated sediments adjacent to the
work areas. Traffic control plans will be devel-
oped in coordination with local police and noise
will be minimized to the extent possible. Air
monitoring will be conducted during the work
and engineering controls such as misting will be
used if necessary for dust suppression.
It is estimated that Alternative 3B would require
2 years for construction and implementation.
PUBLIC NOTICE OF
IMPACTS TO WETLANDS
AND AQUATIC RESOURCES
Several state and federal laws regulate activities
in and around floodplains, wetlands and rivers,
including the remedial action proposed in this
plan. For example, under a federal wetlands ex-
ecutive order, EPA is required to minimize the
destruction, loss or degradation of wetlands and
to preserve and enhance the natural and ben-
eficial values of wetlands. Using these principles,
EPA is further required to select the least en-
vironmentally damaging practicable alternative
for reducing environmental risks at the site. Simi-
larly, EPA is also required by Section 404 of the
Clean Water Act to avoid discharging fill mate-
rial into rivers if there is a practicable alterna-
tive that would have less adverse impact on the
aquatic ecosystem. EPA has determined that the
proposed remedy is a discharge of fill material,
and it involves unavoidable adverse impacts to
wetlands and aquatic resources, primarily in the
form of the deposition of the thin sand layer in
Reach 3, which is a federally-regulated wetland.
EPA has evaluated the applicable regulations,
including Section 404 of the Clean Water Act,
and identified the proposed action as the least
damaging practical alternative to protect feder-
ally regulated wetlands and aquatic resources
from contamination in sediments and surface
water. EPA expects that the thin sand layer will
help prevent mercury from bioaccumulating in
fish and other organisms, and that the impacts
to the river bottom from putting down the layer
will be temporary and minor; benthic organisms
will quickly re-colonize the sand layer. Other al-
ternatives considered for Reach 3 either would
do nothing about mercury in the river or would
have short-term impacts on the benthic environ-
ment that would either be as severe (e.g., in-situ
containment) or more severe (e.g., dredging).
See "Compliance with Applicable or Relevant
and Appropriate Requirements (ARARs)" be-
low for further discussion on wetland impacts.
Through this Proposed Plan, EPA is also solicit-
ing public comment concerning its determination
that the alternative chosen for Reach 3 is the
least damaging practicable alternatives for pro-
tecting wetland resources.
HOW DOES EPA CHOOSE
A FINAL CLEANUP PLAN?
EPA uses nine criteria to compare alternatives
and select a final cleanup plan. Of the nine, pro-
tection of human health and the environment
and compliance with other environmental laws
(known as applicable or relevant and appropri-
ate requirements, or "ARARs") are considered
threshold requirements that must be met by the
selected remedy. EPA balances its consideration
of alternatives with respect to long-term effec-
tiveness and permanence; reduction of toxicity,
mobility or volume through treatment; short-
term effectiveness; implementability; and cost.
State and community concerns are modifying
criteria and may prompt EPA to modify the pre-
ferred alternative or choose another alternative.
Following are definitions of the nine criteria.
1. Overall protection of human health and
the environment: Will it protect you
and the plant and animal life on and
near the site? EPA will not choose a plan
that does not meet this basic criterion.
2. Compliance with Applicable or Relevant
and Appropriate Requirements (ARARs):
Does the alternative meet all federal and
state environmental statutes, regulations
and requirements?
3. Long-term effectiveness and
permanence: Will the effects of the
cleanup plan last or could contamination
cause future risk?
4. Reduction of toxicity, mobility or
volume through treatment: Using
treatment, does the alternative reduce
the harmful effects of the contaminants,
the spread of contaminants, and the
amount of contaminated material?
5. Short-term effectiveness: How soon will
site risks be adequately reduced? Could
the cleanup cause short-term hazards to
workers, residents or the environment?
6. Implementability: Is the alternative
technically feasible? Are the right goods
and services (i.e. treatment machinery,
space at an approved disposal facility)
available for the plan?
7. Cost: What is the total cost of an
alternative over time?
8. State acceptance: Do state
environmental agencies agree with
EPA's proposal?
9. Community acceptance: What
objections, suggestions or
modifications does the public offer
during the comment period?
EVALUATION OF
ALTERNATIVES UNDER
THE NINE CRITERIA
This section summarizes EPA's evaluation of
how well each of the cleanup alternatives de-
scribed above (including the alternative
page 9
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SUPERFUND | HAZARDOUS WASTE PROGRAM AT EPA NEW ENGLAND
PROPOSED PLAN
proposed in this plan) meets the first seven
criteria. A fuller description is provided in the
Feasibility Study Report. Once comments from
the state and the community are received, EPA
will select the final cleanup plan.
Overall Protection of Human Health
and the Environment
Alternative 1 (No Action) does not protect hu-
man health in that it allows for unlimited expo-
sure to contaminated fish (not withstanding the
fishing advisories which may be maintained by
others agencies). All the other alternatives pro-
tect human health and the environment. How-
ever, Alternatives 2 and 3A are less protective
because they merely discourage fish consump-
tion through fish advisories and public outreach,
without doing anything to accelerate the natural
attenuation of contamination in fish. These two
alternatives also rely on routine monitoring to
ensure that fish tissue levels are decreasing (or,
in the case of Reach 8, decreasing or remaining
stable). All other alternatives (including 3B, the
alternative proposed in this plan) protect human
health and the environment by reducing the avail-
ability of mercury to fish in portions of the river,
thus leading to a reduction in mercury in fish tis-
sue over time. These alternatives also include fish
advisories, public outreach and monitoring.
Compliance with Applicable or Relevant
and Appropriate Requirements (ARARs)
Despite the absence of active remediation, Al-
ternatives 1, 2, and 3A would meet ARARs. All
other alternatives are also expected to comply
with ARARs, except for ARARs related to mini-
mizing impacts on wetlands and related aquatic
resources. The wetlands order, Section 404 of
the Clean Water Act and several other state
laws require EPA to avoid adverse impacts to
wetlands and other aquatic environments, unless
there is no practicable alternative with lesser ef-
fects. Alternatives 1, 2 and 3A would not cause
impacts; however, they would also do nothing
to reduce mercury in fish tissue, particularly in
Reach 3 in a reasonable amount of time. All the
active remediation alternatives (Alternatives 3B
through 5D) have an adverse impact - the thin
sand layer, the cap, and the dredging all consti-
tute a temporary degradation of the river bot-
tom environment, which is a wetland. Thus the
question is which alternative constitutes the
practicable alternative with the least adverse
effects on the aquatic environment. EPA has
determined that Alternative 3B (the proposed
remedy), which would place a thin layer of sand
over sediments in Reach 3, and Alternative 4A,
which would place an "in situ containment" cap
over Reach 3, have essentially the same impact
on the aquatic environment, and constitute the
alternatives that have the least adverse impact.
Like the other active remediation alternatives,
these alternatives reduce fish tissue contamina-
tion to acceptable levels in much of the river
within a reasonable timeframe. They differ from
the other active remediation alternatives in two
significant ways: (1) more than the other active
remediation alternatives, Alternatives 3B and 4A
have impacts on only a small portion of the river,
i.e., Reach 3, (2) they do not involve significant
re-suspension of contaminated sediments, as do
the removal/dredging technology contemplated
by Alternatives 5A through 5D. On this basis,
EPA believes that Alternatives 3B and 4A are the
active remediation alternative that best comply
with the wetlands executive order, Section 404
and the state wetlands regulations.
Long-term Effectiveness and Permanence
Under the No Action alternative, long-term
risks would remain unaddressed. All other alter-
natives rely, in varying degrees, on institutional
controls such as the posting of warning signs for
long-term effectiveness. Since these types of con-
trols are not enforceable and compliance with
such warnings is difficult to track, alternatives
that rely more heavily on these controls (such
as Alternatives 2) may be less effective in the
long-term compared to other, more active alter-
natives. The active remedial alternatives (Alter-
natives 3B through 5D) are expected to reduce
fish tissue mercury concentrations and, there-
fore, would achieve protectiveness sooner than
Alternatives 1, 2 and 3A. The removal alterna-
tives (Alternatives 5A through 5D) are expected
to take longer to attain protectiveness due to po-
tential resuspension of contaminated sediment,
but do result in the permanent removal of more
contaminated sediment from the river. To ensure
the long-term protectiveness of Alternatives 3B,
3C, 4A, and 4B, further design work would be
necessary to ensure the stability and integrity
of sand or other capping materials to be placed
in the river pursuant to these alternatives.
Long-term maintenance and monitoring activi-
ties would be conducted as necessary.
Reduction of toxicity, mobility
and volume through treatment
The alternatives that do not contemplate active
remediation (Alternatives 1, 2, and 3A) do not
reduce toxicity, mobility or volume of mercury
in the river. All other alternatives partially satisfy
this criterion: the thin sand layer (3B and 3C)
and the cap (4A and 4B) reduce the mobility
and toxicity of mercury significantly - reducing
the amount that is capable of bio-accumulating
in fish and thereby controlling the only threat
to human health in the river. The dredging and
removal alternatives (5A through 5D) are more
effective still at meeting this criterion, removing
significant quantities of mercury from the river
entirely; however, the material must be removed
and disposed offsite.
Short-term effectiveness/impacts
As no active remediation is proposed for Alter-
native 1, this would not result in any short-term
risks to on-site workers or adverse effects to
the environment or community during imple-
mentation. The time required to implement
Alternative 2 would be minimal since it only in-
volves maintaining institutional controls. Alter-
native 3A adds a monitoring component, which
would allow for verification of the effectiveness
of the site-wide remedy; this monitoring would
pose few short-term risks to workers during im-
plementation as sampling techniques employed
would be traditional and non-harmful to the en-
vironment or surrounding community. Alterna-
tive 2 could also include monitoring activities.
The remaining alternatives all have short-term
impacts. The alternatives that limit active reme-
diation to Reach 3 (Alternative 3B, 4A, 5A and
5C) would obviously have fewer short-term
impacts than the alternatives that propose re-
mediation across several reaches (Alternatives
4B, 3C, 5B, and 5D). A more significant differ-
ence is that the sand and capping alternatives
(3B, 3C, 4A, 4B) may have fewer short-term
page 10
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SUPERFUND | HAZARDOUS WASTE PROGRAM AT EPA NEW ENGLAND
PROPOSED PLAN
impacts than the dredging alternatives (5A, 5B,
5C, 5D), because it is faster and easier to place
material over a riverbed than to dredge it up.
With the dredging alternatives there is also
the potential for sediment re-suspension, which
could cause a temporary elevation in fish tissue
concentrations. Overall, among the alternatives
that go beyond monitoring and institutional con-
trols, the proposed alternative (3B) appears to
have the fewest short-term impacts, because put-
ting down a thin sand layer is relatively simple and
because this activity would be limited to Reach 3.
Implementability
Implementability is primarily related to three fac-
tors: technical feasibility (i.e., can it be constructed,
is it reliable); administrative feasibility; and the
availability of services and materials to implement
the remedy. All the alternatives are readily imple-
mentable and rely on established technologies,
though the larger the scope of the remedy, the
greater the effort required to construct. Alterna-
tives 5A through 5D are relatively large construc-
tion projects, but projects as large or larger have
been conducted at numerous sites across the
country. Thin-layer capping (Alternatives 3B and
3C) and in-situ containment (Alternatives 4A and
4B) have also been successfully completed at oth-
er sites and employ readily available technologies
and materials. There is also sufficient land area for
staging as well as road and rail access to the site.
Cost
Costs for each alternative are outlined above.
Alternative 1 (No Action) is the least costly of
proposed alternative to implement. Alternatives
2 (Limited Action) and Alternative 3A (MNR)
requires little cost to complete compared to ac-
tive remediation. Comparing the active remedial
alternatives, Alternative 3B is the least costly,
followed by 3C, 4A, 4B, 5A, 5B, 5C and 5D in
ascending order.
State Acceptance
State acceptance will be evaluated based on com-
ments the State submits during the comment period.
Community Acceptance
Community acceptance will be evaluated based on
comments submitted during the comment period.
WHY EPA RECOMMENDS
THIS CLEANUP PROPOSAL
EPA proposes Alternative 3B, MNR with Enhanced
Natural Recovery via thin layer sand capping, with
Limited Action in Reach 8 for several reasons. First, it
is protective and more effective than the alternatives
that don't involve active remediation (Alternatives 1,
2, and 3A). Whereas Alternative 3B takes active steps
to reduce the contamination in fish in the most con-
taminated reach of the river, Alternatives 1, 2 and 3A
rely mainly on fish advisories to discourage consump-
tion of contaminated fish although Alternative 3A
also adds a monitoring component. Second, except
in Reach 8, Alternative 3B is expected to reduce fish
contamination to acceptable levels to approximately
the same extent as the other, more intensive alterna-
tives evaluated, yet it costs much less than any other
active remediation alternatives. Third, it has the least
impact on wetlands of any active remediation alterna-
tive, in that it buries and dilutes mercury that would
otherwise remain available for methylation, it has con-
struction impacts on smallest area of the river of all ac-
tive alternatives, and it does not involve re-suspension
of contaminated sediments. With regard to Reach 8,
EPA believes that Limited Action is the best alterna-
tive given the amount of risk reduction that would be
achieved with active remediation in light of the rela-
tively low concentrations of mercury in the sediment.
EPA believes that Alternative 3B meets the two
threshold criteria of overall protection of human
health and the environment and compliance with
ARARs and represents the best balance of the other
criteria and, thus, is proposing this remedy for state
and public comment.
NEXT STEPS
This summer/fall, EPA expects to have reviewed
and evaluated all comments received on this pro-
posal and will sign a Record of Decision, which is
a document that describes the chosen cleanup
plan. The Record of Decision and a summary of re-
sponses to any public comments (the Responsive-
ness Summary) will then be made available to the
public at the Ashland Public Library and at EPAs
Records Center in Boston, and via the internet.
EPA will announce the final decision on the cleanup
plan through the local media and via EPAs website.
HOW YOU CAN
COMMENT ON EPA'S
CLEANUP PROPOSAL
During the 30-day formal comment period,
EPA will accept formal written comments
and hold a hearing to accept formal verbal
comments. EPA uses public comments to
improve the cleanup proposal. To make a
formal comment you need only speak during
the Public Hearing on July 19, 2010 at 7 pm
at the Framingham Town Hall or submit writ-
ten comments during the 30-day comment
period no later than July 26, 2010.
Provide EPA with your written comments
about the Proposed Plan, postmarked no
later than July 25, 2010 to:
Daniel Keefe, Project Manager
U.S. EPA New England
5 Post Office Square, Suite 100
Mail code: OSRR07-1
Boston, MA 02109-3912
Or, submit comments by e-mail to:
keefe.daniel@epa.gov or
Fax comments to: 617-918-0327.
Although EPA cannot respond to comments
submitted at the Public Hearing, EPA will
respond to both your oral and written com-
ments in the written Responsiveness Sum-
mary that will be included with the Record
of Decision. EPA will review the transcript of
all formal comments received at the hearing,
and all written comments received during the
formal comment period, before making a final
cleanup decision.
The fact that EPA responds to formal com-
ments in writing at the time the Record of
Decision is issued, does not mean that EPA
cannot answer questions. EPA will be hold-
ing three informational meetings in June as
indicated on page 1 to answer any questions
about the Proposed Plan.
Your formal comment will become part of the
official public record. The transcript of comments
and EPAs written responses will be issued in a
document called a Responsiveness Summary
when EPA releases the final cleanup decision.
page 11
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SUDBURY RIVER REACHES
-------
Alternatives Comparison
Nyanza Chemical Waste Dump Superfund Site
Operable Unit 4 -Sudbury River, Ashland, Massachusetts
Timeframe to Implement *
Timeframe to Remediation Goals**
Comparison Criteria
Overall Protectiveness
Compliance with ARARs
Long-Term Effectiveness
Reduction of TMV
Short-Term Effectiveness
Implementability
Cost (in Millions)
State Acceptance
Community Acceptance
Alt. 1
No Action
0 Years
>70 Years
m
0
m
m
m
0
$0.0
Alt. 2
Limited
Action
2 Years
>70 Years
S
0
S
m
s
0
$0.2
Alt. 3A
Sitewide MNR
2 Years
>70 Years
S
0
S
H
S
0
$1.1
Alt. 3B
ENR in Reach
3 > 10ppm
3 Years
<30 Years
0
0
0
s
0
0
$8.5
Alt. 3C
ENR in
Reaches 3, 4,
6 > 2ppm
4 Years
<30 Years
0
S
0
S
0
0
$20.8
Alt. 4A
In Situ
Containment
in Reach 3
3 Years
<30 Years
0
0
0
S
0
0
$24.3
Alt. 4B
In Situ
Containment
in Reaches 3,
4 and 6
4 Years
<30 Years
0
S
0
S
0
0
$48.9
Alt. 5A
Dredging >
10ppm in
Reach 3
3 Years
<30 Years
0
S
0
s
0
0
$59.7
AltSB
Dredging >
10ppm in
Reach 3, In
Situ
Containment
in Reaches 3,
4 and 6
4 Years
<30 Years
0
S
0
s
0
0
$88.5
Alt. 5C
Dredging >
2ppm in
Reach 3
4 Years
<30 Years
0
S
0
S
0
0
$99.8
Alt. 5D
Dredging >
2ppm in
Reaches 3, 4
and 6
5 Years
<30 Years
0
S
0
S
0
0
$213.5
To Be Determined After Public Comment Period
To Be Determined After Public Comment Period
Notes: 0 S IE
Alt = Alternative Meets Partially Meets Fails to Meet the
TMV = Toxicity, Mobility and Volume Criteria Criteria Criteria
* Includes a 1 to 2 Year Period to Complete Remedial Design
** Defined to mean attainment of both remedial action objectives: a) prevent consumption of contmainated fish through advisories; and b) reduction of mercury in fish to acceptable levels (except in Reach 8).
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Contaminant Legend
Surfieial Sedimen! Sample
Average Segment Surface
Total Mercury (mg.'fcg)
lit kg
j 1 Segment 3
-J Avg = 5.7 m^-kg
Segment -4
Avg = 9.5 nrg'kq
Segment 5
Avg * 27.9 nig'Kg
D:ita: 03/29; 10
RnvJukin No. OD
Railroad
County B
' Municipal Boundary
Secdnda
Local Ro
id/. Access Ra
Highway&^Major Roads - - Vehicular Trail
Primary Read. Limited Access
Primary Road. Not Limited Access
1 Segment Break
1 Surface Water
] Reach 2
Reach 3
Reach 4
FIGURE B
CONTAMINANT DISTRIBUTION
NYANZA CHEMICAL WASTE DUMP
SUPER FUND SITE
OU4 - SUDBURY RIVER
ASHLAND. MASSACHUSETTS
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AREA OF DETAIL: POTENTIAL STAGING AREA
Conveyor Belt Delivery
System to Sand Barge
Drawn By DttC I Clwsk*J Bv 5WH
Legend
* Railroad ,
Cwtity Bondary Secondary Road
" Municipal Boundary Local Road, Access Ramp '
Highways/Major RoatfS Vehicular Trail
- Primary Road. Lim(ted Accafifi
Primary Road. Not Limited Access
" Reach 2
ReschS
Reach 4
POTENTIAL STAGING AREA DETAIL
REACH 3 SEGMENTS
NYANZA CHEMICAL WASTE DUMP
SUPERFUND SITE
OU4 - SUDBURY RIVER
ASHLAND. MASSACHUSETTS
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