&EPA
United States
Environmental Protection Agency
Region 1
JFK Federal Building
Boston, Mass. 02203
         Executive Summary

         Final Supplemental
   Environmental Impact Statement
            November 1989
      Long-Term Residuals Management
          for Metropolitan Boston

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The U.S. Environmental Protection Agency has
just released the Final Supplemental Environmental
Impact Statement (SEIS) on Long-Term Residuals
Management for Metropolitan Boston. This Final
SETS responds to comments received on the Draft
SEIS issued on May 19, 1989, and incorporates new
information and analyses provided since then.
Since the release of the Draft SEIS in May 1989,
there have been several modifications to the Mas-
sachusetts Water Resources Authority (MWRA)
recommended plan including elimination of corn-
posting as a residuals management technology; a
slight reduction in the landfill footprint to provide a
buffer between the proposed Walpole-MCI landfill
and abutting prison; design specifications for the
proposed landfill; designation of an alternative truck
route to the Walpole-MCI site for periods of high
truck traffic; and a plan for extending water and sewer
utilities to the Walpole-MCI site. In addition, EPA
has conducted expanded technical evaluations of
several issues including sludge quality, ground and
surface water impacts at the Walpole-MCI site,
property values and construction impacts. Based on
the additional environmental evaluation of sites and
residuals management options, and with addition of
several recommendations and mitigation measures
outlined in the Final SEIS, EPA confirms its original
acceptance of MWRA’s preferred plan: digestion at
Deer Island, dewatering and heat-drying at the Quin-
cy Fore River Staging Area and landfihling at the
Walpole-MCI site.
A 60 day public comment period will commence
on December 8, 1989, with formal notification in the
Federal Register, and end February 6, 1990. Written
comments on the Final SEIS will be accepted
throughout the 60 day comment period. After the 60
day public comment period ends, all public com-
ments will be reviewed and considered for the
Record of Decision to be released in the spring of
1990.
The Final SEIS is available for your review at the
repositories listed below:
Boston Public Library, Boston
Hough’s Neck Community Center, Quincy
Maiden Public Library, Malden
MWRA Public Library, Charlestown.
Norfolk Public Library, Norfolk
Revere Public Library, Revere
State House Library, Boston
Stoughton Public Library, Stoughton
Thayer Public Library, Braintree
Thomas Crane Public Library, Quincy
U.S. EPA Library, JFK Building, Boston
Walpole Public Library, Walpole
Winthrop Public Library, Winthrop
WRITFEN PUBLIC COMMENT MAY BE
SUBMiT lED UNTIL FEBRUARY 6,1990 TO:
Ann Rodney
U.S. EPA, Region I
MEP- 1900C
JFK Federal Building
Boston, MA 02203
617-565-4424
0
Long-Term Residuals Management for
Metropolitan Boston
Final Supplemental Environmental Impact Statement
November 1989 U.S. Environmental Protection Agency, Region I

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United Slates
Environmental Protection
Agency
Region I
John f  Kennedy Federal Building
Boaton. MA 02203-2211
Postage and
Fees Paid
Environmental
Protection
Agency
EPA-335
                                                                     Official BinliMM
                                                                     Penalty for Private U«e
                                                                     $300

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            Executive Summary

            Final Supplemental
   Environmental Impact Statement
               November 1989
       Long-Term Residuals Management
            for Metropolitan Boston
                   Prepared by:

                   United States
              Environmental Protection Agency
                    Region 1
                 JFK Federal Building
                 Boston, Mass. 02203


                Technical Assistance by:
                   Metcalf&Eddy
PaulG. Keougb /   ^             Date
Acting Regional Administrator
U.S. EPA, Region I

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EXECUTIVE SUMMARY
BACKGROUND AND PURPOSE
This Final Supplemental Environmental Impact Statement (SEIS) is the second of
two documents that constitute an analysis by the Environmental Protection
Agency (EPA) of the Massachusetts Water Resources Authority’s (MWRA’s) long-
term residuals management plan for Boston Harbor. The purpose of both the
first document of EPA’S analysis, the Draft SEIS, and this Final SEIS is
threefold: 1) to fulfill EPA’s commitment for additional environmental
analysis, as specified in the 1986 Record of Decision on the siting of MWRA’s
new wastewater treatment plant; 2) to ensure compliance with the provisions of
the National Environmental Policy Act and Clean Water Act; and 3) to provide
an independent analysis of’ the MWRA’s residuals management plan and its
Environmental Impact Report/Facilities Plan (EIR/FP).
The Draft SEIS developed and screened residuals management alternatives by
evaluating a variety of potential sites and processing technologies. The
Draft SEIS and this Final SEIS address questions related to the long term
method of processing, reusing and disposing of residuals generated as by-
products of the new Deer Island treatment plant, which will serve the entire
MWRA service area (Figure 1). In particular this SEIS addresses:
• the location and method for disposing of grit and screenings removed
from the wastewater stream at the remote headworks;
• the location and method for digesting and dewatering sludge from the
Deer Island treatment plant;
• the location and method for processing sludge for reuse or disposal;
and
• the transportation of residuals from Deer Island and the remote
headworks to the processing and disposal sites.
Several acceptable alternatives were presented in the Draft SEIS (Table 1),
which was released in May 1989. This was followed by a period in which both
government agencies and the general public were invited to comment on the
document. During this period three public hearings were held and nearly 200
comment letters were received. This Final SEIS presents and responds to those
comments; it also contains a review and evaluation of’ modifications to the
MWRA-proposed residuals management plan and new information that has become
available since the release of the Draft SEIS. Additional technical analysis
of the issues that were of greatest concern to EPA and the commentors has also
been performed and the results are contained herein.
The Draft SEIS is not reproduced in this document, but modifications of and
additions to it are contained in the Final SEIS as necessary. A reexamination
of the conclusions and recommendations made by EPA in the Draft SEIS is made
in this document, taking into account public and agency comments and the
technical information and modifications generated since the release of the
Draft SEIS. Additional mitigation measures and recommendations are made as
necessary.

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FIGURE 1. MWRA SERVICE AREA
Source: MDC, 1979 and MWRA, RMFP, DEIR, 1, 2, 1989

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TABLE 1. ACCEPTABLE RESIDUALS MANAGEMENT ALTERNATIVES
Site Transfer
Dewater
Heat Dry
Combust
Compost
Landfill
Walpole MCI
X
Rowe Quarry
X
Stoughton
X
X
Quincy FRSP 1
X
X
X
X
Spectacle Island
X
X
X
X
Deer Island
X
X
X
MODIFICATIONS TO THE PROPOSED ACTION
Five substantive modifications have been made to the MWRA-recommended plan
since the release of the Draft SEIS: composting was eliminated as a residuals
management technology; the landfill footprint was reduced slightly to provide
a buffer between the proposed Walpole-MCI landfill and the abutting prison; a
modification of the EPA—recommended alternate Walpole truck route was
incorporated into the plan; more detailed provisions were made for supplying
water and sewer services to the Walpole-MCI site; and more detail was
developed on design specifications of the proposed landfill.
Residuals Management Technologies
At the time that the Draft SEIS was released, MWRA had recommended a residuals
management plan that included compostirig one third of the sludge and heat
drying the remainder. MWRA has more recently decided to eliminate composting
from the plan and heat dry all of the sludge cake, on the basis that
composting could cause significant odors, traffic and land use impacts. M 1 4RA
has also finalized its decision on a dewatering technology, deciding to
install solid bowl “high solids” centrifuges, thus the solids content of the
dewatered sludge is expected to be at least 25 percent and could be as high as
29 percent. The belt filter presses used during the interim residuals
management program, which dewater sludge to a lower solids content, will be
retained as backup.
The elimination of the composting as a second processing technology reduces
the redundancy and flexibility in the sludge processing system and increases
the importance of 1) having reliable, sufficient capacity in the heat drying
system; 2) marketing most of the heat dried pellets; and 3) having a reliable
backup method for disposing of unmarketable sludge product. In the event that
one or more of the heat drying trains is not operational, or if the
centrifuges produce a sludge cake that it not at least 25 percent solids, the
currently planned six heat drying units will not provide sufficient capacity
to pelletize all of the sludge after 1999. Therefore, as MWRA has proposed
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that excess dewatered sludge be disposed of in the minor residuals landfill,
the potential impacts of eliminating composting are primarily associated with
the ultimate capacity of the landfill.
Landfill Capacity
Given the reliance on the residuals landfill as a backup technology, it must
be able to accommodate sludge cake during heat dryer down—time due to
breakdowns and maintenance, excess sludge cake that can not be accommodated by
the heat driers if dewatering equipment performance is less than predicted,
and non-marketable heat dried pellets. The landfill capacity used for these
purposes depends upon the percentage solids in the sludge cake and the
required quantity of bulking agent required to stabilize the sludge cake.
Under a middle range scenario in which sludge cake of 25 percent solids is
landfilled at a 2:1 ratio of bulking agent to sludge cake, no pellets are
landfilled, and one heat drying unit is inoperable, the landfill will be
filled in approximately 20.5 years, k.5 years short of the project life. If
25 percent of the pellets produced needed to be landfilled the useful life
would be reduced to approximately 12.5 years, or one-half the project
period. The Final SEIS contains a full analysis of potential landfill
scenarios.
To address this situation, EPA and the MWRA have signed an agreement in which
MWRA has committed to a specific rate of use of the Available Remaining
Capacity (ACR) of the landfill to ensure that there is sufficient capacity for
the entire planning period (1995-2025).
Walpole Truck Route and Utilities
MWRA has also committed to the use of a second truck route to the Walpole-MCI
site in the event that more than 21 trucks per day are needed for disposal of
residuals at the landfill. A similar alternative route was described and
recommended in EPA’s Draft SEIS. A sufficient number of alternatives have
been provided to ensure that MWRA can provide utilities to the Walpole site
without disrupting local water and sewer service, including the use of water
storage facilities and dedicated water or sewer lines.
Landfill Design Details
MWRA’s proposed landfill design will include a system of double liners,
leachate collection systems, and runoff control systems. The primary leachate
collection system, which will be installed above the upper synthetic liner,
will collect leachate from open cells. A second leachate collection system
will be installed between the upper and lower (clay) liner, and will serve as
a leak detection system for the upper liner. Existing runoff patterns will be
maintained wherever possible by dikes, trenches and berms designed to divert
runoff from exposed portions of the landfill.
EXPANDED TECHNICAL EVALUATIONS
EPA supplemented its technical evaluation of the MWRA-recommended plan with
additional analyses of’ the following issues: sludge quality, ground and

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surface water quality, residential property values arid construction
activities.
Sludge Quality
Analysis of an additional seven months of sludge quality data from the Deer
Island and Nut Island monitoring programs confirmed the analysis provided in
the Draft SEIS for most pollutants. The only substantial difference found was
for molybdenum. The Massachusetts limit for molybdenum application on non-
agricultural and non—grazing lands is kO mg/kg. The new analysis found an
average concentration for molybdenum (Ifl mg/kg) that was higher than the
earlier average (26 mg/kg) and exceeds the land application standard. When
adjusted for secondary treatment, the predicted molybdenum concentration would
be 108 mg/kg. Should these predicted concentrations be accurate, they could
inhibit marketing or distribution of the sludge pellet product in
Massachusetts.
Groundwater
Potential contamination of two private welluields near the Walpole—MCI site
was evaluated. Contamination could occur in the event that the landfill
double liner and double leachate collections systems fail, leachate penetrates
at least 25 feet of unsaturated soils, is not detected by monitoring wells and
travels 800 feet or more to the wells. A computer model was used to simulate
the transport of a plume of contamination to evaluate the potential effects on
the private welifields and was run until peak contaminant concentrations were
observed. Peak pollutant concentrations at the private wells were predicted
to be below the Massachusetts groundwater criteria, even under the worst case
scenario of a fifty percent leak for ten years. The time required to reach
peak concentrations at the public or private wells would be more than
sufficient for any unexpected contamination to be remediated.
Surface Water
Additional investigations were conducted for this Final SEIS in order to
determine a range of flows which could be expected for the Stop River;
estimates were derived for the ten-year, seven-day low flow and the two-year
flood. These extreme conditions were used to predict a range of potential
contaminant concentrations in the Stop River that could potentially occur as a
result of a landfill leak at the Walpole-MCI site. The two—year flood flow is
over 6,000 times greater than the maximum potential leachate flow; thus
leachate concentrations would be sufficiently diluted so that no adverse water
quality impacts would be expected.
Water quality impacts under low flow conditions from a potential undetected,
unmitigated leak in the Walpole-MCI landfill were evaluated using the same
computer model of groundwater contaminant transport as used in the private
well analysis described above. Under low flow, worst case conditions, the
peak concentrations above background are all predicted to be well below the
applicable freshwater standards; the time required to reach these peak
concentrations is on the order of hundreds to hundreds of thousands of years.
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Property Values
No information was found specifically for effects of a sludge landfill on
property values; however, inferences were drawn from studies of other
negatively perceived facilities, such as airports, sanitary landfills,
highways and power plants. In general, the studies showed that environmental
factors usually account for only a small proportion of housing price
differentials. The major determinants of the differences between prices of
different properties at a particular point in time are house quality and size,
lot size, characteristics of the municipality and quality of services. Major
determinants of the difference in the price of a single property over time are
demand, interest rates and the regional economy.
The only quantifiable relationship found between environmental factors and
property value was for excessive noise (above 75 dBA). Excessive noise at the
Walpole-MCI site during active construction and closure of three of the
landfill cells could affect three properties on Winter Street. However, the
literature indicates that should negative effects on property values occur the
impacts are lessened once the impacts are mitigated; thus it is not expected
that the Walpole-MCI landfill would have any significant long-term effects on
property values.
cOIISTRUCTION ACTIVITIES
Construction activities could cause temporary impacts on the areas surrounding
the residuals sites; however, most of these impacts can be mitigated or will
have no long—term adverse effects.
Potential fugitive dust impacts at the Walpole-MCI site can be controlled by
using standard dust control techniques such as water spray, hay, mulch, dust
suppressants, or revegetation. Excess truck traffic can be mitigated by using
the alternate Pine Street route to the site.
MWRA has indicated that meteorological and dust monitoring equipment will be
installed at the Quincy FRSA site during construction of the residuals
facilities to monitor volatile organic compound (VOC) and particulate matter
in the air. Dust control measures at this site would include, in addition to
the measures described above, revision of the work pattern or temporary
reduction in the excavation area. Excavation will be minimized by the use of
pile-supported foundations for all residuals facilities at the Quincy FRSA.
In addition, excavated contaminated soil would be handled and disposed of in
accordance with Massachusetts Department of Environmental Protection
guidelines. Contaminant levels in pumped groundwater associated with
dewatering will be closely monitored and the water will be treated, if
necessary, before discharge into the Fore River. Construction activities that
would exceed noise level significance criteria should be limited to daytime,
weekday periods.
Residuals facilities at Deer Island are to be located at the southern portion
of the island, away from residential areas; therefore construction of these
facilities is not expected to have significant impacts.
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COIO NTS
After the release of the Draft SEIS, EPA held three public hearings and
distributed the draft document to an extensive mailing list and several public
repositories in order to allow for public and agency review. Another 5,000
people or agencies were notified by mail that the document was available for
review. Nearly 200 comment letters were received from Federal and State
agencies, local officials, a pre-established Citizens Advisory Committee (CP 1 C)
and the general public. These comments addressed all aspects of the Draft
SEIS, including its technical and legal scope and adequacy, the alternatives
considered, the analyses conducted, the decision—making methodology and the
recommendations made. The vast majority of the comments received addressed
(in order of occurrence): ground and surface water impacts (particularly at
the Walpole-MCI site); adherence to state and federal policies and
regulations; the proposed landfill design; air quality and odors at all sites;
the quality of the residuals materials and public health. A list of issues
was developed from the comment letters and each issue is addressed in the
Final SEIS.
ACCEPTABILITY OF MWRA-RECOMMENDED PLAN
Based on the additional environmental evaluation of sites and residuals
management options, EPA confirms its original acceptance of’ the
site/technology alternatives described in the Draft SEIS (Table 1). In
addition, EPA believes that the MWRA-recomrnended residuals processing plan of
dewatering and heat-drying at the Quincy FRSA and landfilling at the Walpole-
MCI site is environmentally acceptable.
As discussed in the Draft SEIS, EPA supports the goal of 100 percent reuse of
sludge and believes that it is imperative that sufficient sludge product
distribution takes place to ensure that sludge discharge to Boston Harbor does
not resume. In fact, MWRA’s recommended plan is built around the supposition
that distribution and marketing of’ sludge product will be successful. To that
end, and because the exact amount of sludge product that will be marketed is
somewhat uncertain, in the Draft SEIS EPA outlined five steps that would help
guarantee adequate distribution of the sludge pellets; actions taken by MWRA
to address the steps is described below.
1. MWRA has committed in its Final EIR that if’ it needs to use the
Walpole-MCI landfill for backup sludge disposal, it will preserve
landfill capacity by heat drying the sludge prior to landfilling or
by other means as discussed in the recently established EPA/MWRA
agreement on landfill capacity (see page 5 of this Executive
Summary).
2. MWRA has committed in the Final EIR to negotiate with the
Massachusetts Department of Public Works (which maintains the state
highway system), the Department of Environmental Management (which
maintains the state park system) and other government agencies to
use MWRA’s heat dried sludge product for their fertilizing and soil
enhancement needs.
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3. MWRA has not yet obtained a classification from the Massachusetts
DEP (formerly DEQE) of the compost being produced by the Deer Island
pilot plant, or begun a program of significant distribution of the
product. Although composting is no longer included in the long—term
residuals management program, MWHA should continue to pursue
classification and distribution of the compost in order to establish
itself as a producer of beneficial sludge products and to
demonstrate its ability to successfully negotiate the regulatory
process and market its product.
4. MWRA has not yet established a plan for confirming, through
additional sludge and influent monitoring, the projected levels of
metals which will potentially exceed regulatory standards for
distribution of sludge products (mercury, copper, cadmium and
molybdenum). Such a plan must be prepared and implemented, and if
exceedances are projected, a plan for reducing these levels through
pretreatment, source reduction or targeted enforcement should be
formulated.
5. MWRA presented in the Final EIR the outline of a marketing strategy
which involves market and applied research, quality monitoring,
toxics reduction and program administration and planning. The
methods that will be used to contact potential buyers, to advertise
and transport its product, and to assist buyers in obtaining
appropriate permits must be addressed as well.
MWRA must continue to pursue these five steps in order to ensure the long-term
viability of its recommended plan.
Additional reconnnendatioris developed as a result of’ the analyses undertaken in
this Final SEIS relate primarily to preservation of landfill capacity, and
because emergency and excess sludge could constitute the largest quantity of
material to be landfilled, to the effectiveness of the heat drying trains.
Because all six of the proposed heat drying units will be required to process
sludge in the maximum months, the heat drying facilities should have the
flexibility to allow for full use of all operational heat drying .inits
regardless of which centrifuges are operational. In addition, the performance
of the residuals processing trains (centrifuges and heat dryers) should be
closely monitored prior to implementation of secondary wastewater treatment
(1999) in order to assess their performance level. After 1999, less than
optimum performance would render the proposed residuals processing facilities
incapable of heat drying all of the sludge; thus space for at least two
additional heat drying trains or other residuals processing facilities should
be reserved at the Quincy FRSA. As discussed earlier in this document, MWRA
and EPA have signed an agreement regarding husbanding of the landfill to
ensure adequate capacity throughout the 25 year planning period. EPA ’s
acceptance of MWRA’s plan is conditioned on MWRA adherence to that agreement.
Additional recommended mitigation measures are related to protection of
groundwater resources at the Walpole-MCI site, and are described below. The
existing monitoring wells on the site should be used to collect background
data between now and initiation of the landfill construction, and to help
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define the exact number, spacing and location of the permanent monitoring
wells. Also in this time frame, piezometers should be installed to determine
in more detail the overall groundwater flow patterns. Generally, monitoring
wells should be located along the slope between the landfill and the eastern
side of’ the Stop River and adjacent to the Stop River impoundment, along the
northern boundary of the site between the landfill and the private wells, and
along the western site boundary between the landfill and the Neponset Sole
Source Aquifer. A cluster of wells at some locations might be necessary in
order to obtain samples at various depths of the aquifer. A well should be
located upgradient of the site to provide representative background water
quality data and bedrock wells will be needed to monitor flow in fractured
bedrock.
All materials which are to be deposited in the landfill should be monitored,
including soil used in the construction f the landfill liner, leachate
collection arid capping systems, residuals and residuals products.
The water quality monitoring wells should be sampled at least quarterly and
compared to background data, particularly for contaminants that are known to
be found in the residuals such as metals and total organic carbon, and for
contaminants that have low retardation factors; sampling should be refined as
necessary. Samples should be analyzed to the most current water quality
standards and guidelines. The private wells near the site should be sampled,
at MWRA’s cost, upon reasonable request by the homeowners.
A sampling and testing program should be developed to monitor surface water;
although no contamination is expected to occur, surface waters should be
monitored at regular intervals. The Stop River should be sampled above, below
and adjacent to the site. The Stop River impoundment should also be monitored
at various locations.
A combination of state of the art technology and rigorous environmental
monitoring is expected to provide complete mitigation of impacts from the
proposed residuals landfill at the Walpole-MCI site. However, a detailed
contingency plan must be prepared prior to construction of the landfill that
would identify all appropriate design features and monitoring that would be
required to prevent contamination of the site and surrounding areas. The
contingency plan should also include a discussion of measures to be taken in
the event that remedial action is necessary. These measures should include,
in the event of contamination, MWRA remediation or replacement of public and
private water supplies.
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