DRAFT
ENVIRONMENTAL IMPACT STATEMENT
ON THE UPGRADING OF THE
BOSTON METROPOLITAN AREA
SEWERAGE SYSTEM
EXECUTIVE  SUMMARY
UNITED STATES ENVIRONMENTAL
PROTECTION AGENCY • REGION I
JOHN F. KENNEDY FEDERAL BUILDING • GOVERNMENT CENTER
BOSTON, MASSACHUSETTS • 02203

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EXECUTIVE SUMMARY
DRAFT
ENVIRONMENTAL IMPACT STATEMENT
ON THE UPGRADING OF THE
BOSTON METROPOLITAN AREA
SEWERAGE SYSTEM
PREPARED FOR
U. S. ENVIRONMENTAL PROTECTION AGENCY
REGION I
BOSTON, MASSACHUSETTS
BY
GREELEY AND HANSEN
AND
ENVIRONMENTAL ASSESSMENT COUNCIL, INC.
APPROVED BY:.
rri’t— 4 i ‘ i
William R. Adams, Jr. Date
Regional Administrator

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TABLE OF CONTENTS
Page
SUMMARY OF THE RECOMMENDED PLAN ii
I. INTRODUCTION 1
II. BACKGROUND 1
III. METHOD OF APPROACH 4
IV. PRELIMINARY AND INTERMEDIATE SCREENING 4
V. FINAL SCREENING 5
A. Deer Island —Broad Meadows 7
B. Deer Island- SquantunL 10
C. All Deer Island 12
D. Comparative Analysis 14
VI. OTHER OPTIONS 17
A. EMMA Plan 17
B. No Action Plan 18
C. Modified No Action Plan 19
VII. SELECTION OF THE RECOMMENDED PLAN 20
VIII. DESCRIPTION OF THE RECOMMENDED PLAN 22
IX. IMPACTS OF THE RECOMMENDED PLAN 32
A. Water Quality 32
B. Water Quantity 33
C. Air Quality 33
D. Noise 35
E. Biota 36
F. Socio-Economjc 38
G. Recreational and Scenic Areas 39
H. Sites of Special Significance 39
I. Significant Environmentally Sensitive Areas 40
X. MEASURES TO MITIGATE ADVERSE IMPACTS 41
XI. ADVERSE EFFECTS WHICH CANNOT BE AVOIDED 43
XII. IRREVERSIBLE AND IRRETRIEVABLE COMMITMENTS
OF RESOURCES 44
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SUMNARY OF THE RECOMMENDED PLAN
The Recommended Plan of this Environmental Impact State-
ment (Els) includes centralized treatment of the wastewaters
from the entire MSD service area at Deer Island. The existing
primary treatment plant at Deer Island will be expanded and
upgraded to provide secondary treatment for an average daily
wastewater flow of 586 mgd, which is estimated will require
treatment in the design year of 2000.
The existing interceptor system which serves the southern
MSD service area will be extended and relieved in order to
accomodate the anticipated increased wastewater flows from its
present tributary area and the possible addition of five com-
munities. This interceptor system will transport the waste—
waters from the southern service area to Nut Island, where the
wastewater will receive preliminary treatment at a new headworks.
The discharge from the headworks will flow through a submarine
pipeline-tunnel across Boston Harbor to Deer Island for treatment.
The northern interceptor system will be extended and
relieved to accomodate anticipated increased wastewater flows
from its present tributary area and the possible addition of
three communities. This wastewater will receive preliminary
treatment at four existing headworks and will be transported
to Deer Island for treatment.
The effluent from the secondary treatment plant at Deer
Island will be discharged through an outfall system to Boston
Harbor near President Roads. The existing Deer Island outfall
system will be upgraded and an additional outfall will be con-
structed for this purpose.
The primary sludge resulting from the primary phase of
treatment will be incinerated, and the resultant ash disposed
of, at Deer Island in accordance with the recommendations of
a separate Environmental Impact Statement which addressed
the issue of primary sludge disposal. The secondary sludge
will be disposed of by three methods, as follows:
1) Secondary sludge from the treatment of the northern
service area wastewater will be dewatered and
incinerated at Deer Island, and the resultant ash
will be transported by barge to Squantum Point where
an ash landfill will be located.
2) About half of the secondary sludge from the treatment
of the southern service area wastewater will be
dewatered at Deer Island and then transported to
Squantum Point where it will be composted. The
resulting compost product will be marketed or given
away.
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3) The remaining secondary sludge from the treatment of
the southern service area wastewater will be digested
and dewatered at Deer Island and then transported by
barge to Squantuin Point. At Squantuxn Point this
sludge will be loaded onto trucks which will dispose
of it at an MDC owned and operated sludge landfill.
The estimated construction cost of the Recommended Plan,
based on May 1978 prices, is $770,700,000. Operation and
maintenance costs are estimated to be $24,800,000 per year.
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COST OF RECOMMENDED PLAN 1
Wastewater Treatment 404,290,900
Facilities 2
Secondary SluJge Management 58,784,500
Interceptor System 3 307,620,000
Total Capital Costs 770,695,400
Amortized Capital Costs 4 59,782,800
Operation and Maintenance Costs 24,765,200
Total Annual Costs 84,548,000
Applicant’s share of Cap.
Cost (10%) 77,062,500
Applicant’s Share of
Amortized Cap. Cost 5,978,300
Applicant’s Share of
O & M Costs 24,765,200
Applicant’s Share of
Total Annual Cost 30,743,500
(1) Engineering News Record Construction Index = 2654
(2) Includes work at Nut Island and Outfall
(3) Includes submerged pipelines, tunnel and related pumping stations
(4) Assume average life of facilities = 30 years; Interest rate =
6-5/8 percent
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RESOURCE REQUIREMENTS AND OPERATION AND MAINTENANCE
COSTS OF THE RECOMIIENDED PLAN
Resource Wastewater Treatment Sludge Manage-
Requirements Plant xnent Facility
Manpower 298 86
Chlorine -Tons/Year 7,135
Fuel Oil-Gallons/Year 706,000 224,214
Electric Power-Kwhr/Year 196,571,000 27,482,675
Lime-Tons/Year 14,600
Ferric Chloride-Tons/Year 3,504
Polymer-Tons/Year 113
Annual Operation & Maintenance
Costs ($ Million) $17.14 $6.31
Interceptor System & Related
Pumping Stations
Annual Operation & Maintenance
Costs ($ Million) $1.31
Total Annual Operation & Maintenance
Costs ($ Million) $24.76
Note: If it is necessary to purchase wood chips to
serve as a bulking agent for the composting
operation, approximately 9,000 cubic meters
(12,000 cubic yards) of wood chips would be
required per year. At a cost of $6.00 per
cubic yard for wood chips, the resulting in-
crease in the annual operation and maintenance
costs for the sludge management facility
would be about $72,000 per year.
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I. INTRODUCTION
The purpose of this Environmental Impact Statement is to
develop the most environmentally acceptable, cost effective
wastewater management plan for the Eastern Massachusetts
Metropolitan Area. The study addresses various phases of
wastewater management including collection, treatment and
disposal of wastewaters, and treatment and disposal of
secondary sludge. Various wastewater management systems,
including the plan proposed in the Wastewater Engineering and
Management Plan for Boston Harbor-Eastern Massachusetts
Metro olitan Area (EMMA Study), were evaluated. The study
area included those commi:inities included in the enlarged MSD
service area as described in the EMMA Study, and shown on
Figure 1.
II. BACKGROUND
The Metropolitan District Commission presented a
comprehensive plan for wastewater management in its report,
Wastewater Engineering and Management Plan for Boston Harbor-
Eastern Massachusetts Metropolitan Area (EMMA Study). The
principal recommendations of that report to achieve clean
water goals established for Boston Harbor and its tributary
rivers are:
1) Upgrading the Deer Island and Nut Island treatment
plants from primary to secondary treatment.
2) Sludge disposal by means of incineration as
recommended in a 1973 report prepared for the MDC
entitled A Plan For Sludge Management .
3) Alleviating combined stormwater—sewage overflows.
4) Construction of two advanced waste treatment plants
on the Charles and Neponset Rivers.
5) Extension and improvement of the MDC’S interceptor
system.
The EMMA Study visualizes increasing the service area of
the Metropolitan Sewerage District (MSD) through the addition
of the towns of Lincoln, Lynnfield, and Weston*to the northern
MSD service area, presently served by the Deer Island Treat-
ment Plant, and the addition of Dover, Hopkinton, Sharon,
Sherborn and Southborough to the southern MSD service area,
presently served by the Nut Island Treatment Plant. The Deer
Island Treatment Plant would be expanded and upgraded to
provide secondary treatment for the increased flows from the
northern service area.
*Wt has since voted not to join the MSD.
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EXISTING MSD
SERVICE AREA
WESTON HAS VOTED NOT
TO JOIN THE MSD
LEGEND
COMMUNITIES WHICH WILL POSSIBLY BE
ADDED TO THE MSD SERVICE AREA
A PORTION OF HINGHAM IS PRESENTLY
SERVED BY THE MSD
POTENTIAL ENLARGED
MSD SERVICE AREA
NAISACHU$tTT$
SAY
FIGURE 1 STUDY AREA LOCATION

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Two inland advanced wastewater treatment plants, one
discharging to the Charles River and the other to the
Neponset River, would be constructed in the southern service
area, thereby reducing the extent of the expansion required at
Nut Island and providing low—flow augmentation for the rivers.
The satellite plant that would discharge to the Charles River
would serve Ashland, Framingham, Hopkinton, Natick, Sherborn
and Southborough as well as parts of Dover and Wellesley. The
other satellite plant would discharge to the Neponset River
and serve Sharon, Stoughton and Walpole, as well as parts of
Norwood and Canton. The remainder of the wastewater from the
southern service area would receive secondary treatment at
an expanded and upgraded Nut Island Treatment Plant.
The sludge generated at the Nut Island plant would be
pumped across Boston Harbor to Deer Island, where it would be
combined with the sludge from the Deer Island plant. The
sludge from both plants would be incinerated at Deer Island.
Modifications to the interceptor system have been
recommended to relieve existing overloaded conditions and to
provide adequate capacity for future flows. The extent of
this work is distributed throughout the service area, in
urban as well as suburban areas. Also, renovation or re-
placement of each of the ten MDC pumping stations along the
interceptor system has been recommended to replace existing
worn-out equipment in order to provide efficient and adequate
pumping capacity for future flows.
In September, 1976, EPA Region I contracted with the firms
of Greeley and Hansen and Environmental Assessment Council,
Inc. to assist in the preparation of an Environmental Impact
Statement for the upgrading of the MDC’S wastewater management
system. Various wastewater management alternatives, in
addition to the MDC’s Recommended Plan, were to be considered.
The EMMA Study considered all aspects of wastewater
management planning to provide recommendations for the con-
struction and/or rehabilitation of facilities needeci for eff-
ective wastewater management. This EIS is focused on those
aspects of the MDC’S Recommended Plan that deal with the
transportation, treatment and ultimate disposal of municipal
wastewaters. The factors considered are:
1) Interceptor system modifications required due to in-
creases in wastewater flow volume and alternative
treatment plant sites.
2) Environmental and engineering feasibility of con-
structir 1 g satellite treatment plants discharging to
inland waterways.
3) Alternative treatment plant sites and t eatment
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facility configurations for the major wastewater
treatment plants in the vicinity of Boston Harbor.
4) Alternative techniques for the treatment and dis-
posal of secondary sludge.
5) Wastewater treatment plant effluent discharge loca-
tions.
This EIS does not address the following items which are
included in the EMMA Study: Infiltration/Inflow analysis;
combined sewer overflow regulation; and primary sludge dis-
posal.
III. METHOD OF APPROACH
The method of approach used in this EIS was to divide the
wastewater management system into major subsystems which would
be further subdivided into major components. As an example,
the major subsystem of wastewater treatment facilities was
subdivided into facility locations, treatment processes and
discharge locations. All reasonable alternatives for each of
these subsystem components were then evaluated in the
preliminary screening phase. The preliminary screening process
eliminated all alternative components which were obviously
infeasible because of severe environmental impacts, technical
infeasibility or prohibitive costs.
The remaining alternative components were the combined
to form feasible subsystem alternatives. These alternatives
were then evaluated in the intermediate screening process.
In this phase, preliminary design and evaluation of facilities
and environmental assessments were used to eliminate the less
feasible alternative subsystems from further consideration.
The remaining subsystems were then combined to form
complete wastewater management systems which included waste-
water collection, treatment and disposal and sludge treat-
ment and disposal. In the final screening phase the
alternative wastewater management systems were analyzed in
detail in order to select the best alternative based on
environmental, technical and economic factors.
IV. PRELIMINARY AND INTERMEDIATE SCREENING
Two basic wastewater management systems were considered;
one which provides all wastewater treatment facilities in the
vicinity of Boston Harbor and one which includes inland
satellite plants on the Charles and Neponset Rivers in addition
to harbor area plants.
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During the preliminary and intermediate screening stages
of this study, various alternative coastal area treatment
plant sites, treatment plant discharge locations, wastewater
treatment processes, and sludge treatment and disposal methods
were investigated. During these screening stages, many alter-
natives were eliminated from further consideration due to one
or more of the following factors: severe negative environ-
mental impacts; technical infeasibility; and prohibitive
costs. The results of the preliminary and intermediate
screenings are summarized briefly below:
1) Coastal area treatment plant sites: Eleven sites
were considered, and all but three were eliminated.
2) Coastal treatment plant discharge points: Of the
four discharge points considered, three remained.
3) Satellite treatment plant sites: Over thirty sites
were considered for the two satellite plants, and
all but six were eliminated.
4) Satellite plant discharge points: Various discharge
points were considered along the Charles and Neponset
Rivers. It was determined that there was no feasible
combination of degree of treatment and discharge
location which would result in meeting water quality
criteria. Therefore, the concept of satellite treat-
ment systems was eliminated.
5) Wastewater treatment processes: Various methods of
secondary treatment were considered. The air act-
ivated sludge process was selected for the purposes
of this Study.
6) Sludge treatment and disposal: Numerous processes
for sludge thickening, stabilization, dewatering,
conversion and ultimate disposal were considered.
The preliminary and intermediate screenings resulted
in the formulation of three possible sludge management
alternatives.
V. FINAL SCREENING
The alternative wastewater management systems which
included inland satellite treatment plants were eliminated
from further consideration during the preliminary and inter-
mediate screening stages of the study. The remaining non-
satellite systems were: Treatment at Deer Island and Broad
Meadows; treatment at Deer Island and Suantum Point; and all
treatment at Deer Island. The secondary sludge management
alternatives for non—satellite systems which survived the
earlier screenings are:
Landfilling of chemically conditioned, digested, filter
pressed secondary sludge.
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Composting of chemically conditioned, undigested, filter
pressed secondary sludge.
Incineration of chemically conditioned, undigested,
filter pressed secondary sludge.
The least expensive of the remaining sludge disposal
alternatives is landfilling digested, dewatered sludge at a
landfill owned and operated by the MDC. Due to the nature of
the sludge, particularly the presence of heavy metals, leachate
from the landfill must be collected and treated. Landfilling
of sludge is the most land intensive method, requiring about 370
acres of land to dispose of all the secondary sludge generated
in the MSD service area.
Transporting all the dewatered secondary sludge to an in-
land sludge landfill requires considerable truck traffic from
the treatment plants to the landfill. Truck traffic would
have the greatest impact when transporting sludge from a plant
on Deer Island, since from 16 to 43 trucks, depending on the
size of the treatment plant and the capacity of trucks used,
would have to pass through the residential areas of Point
Shirley and Winthrop each day. The impact of truck traffic
would not be as great when transporting sludge from a plant at
either Squantum or Broad Meadows, where the number of trucks
required is less, 13 to 19 per day, and the plants are located
closer to major arteries.
Due to problems associated with leachate control, the
large land area requirements and the heavy volume of truck
traffic required, methods of sludge disposal other than land-
filling should be used where possible. The remaining feasible
sludge disposal options available are composting sludge to
produce a marketable or ‘ t give-away” product, and sludge in-
cineration with ash disposal in a controlled fill area.
Based on the experiences of other metropolitan areas and
preliminary investigation in this EIS, it is estimated that,
with an extensive promotional campaign, the MDC jurisdictional
area could support a market for approximately 20,000 dry tons
of compost per year. The compost production can be utilized as
a soil conditioner and applied to parks, highway median strips,
golf courses, cemeteries, residentaial lawns and other land-
scaped areas. Other possible outlets are commerical nurseries
and landscape contractors in the area. In addition to existing
park lands, the Boston Harbor Islands Comprehensive Plan (MAPC
1972) recommends the development of the Boston Harbor Islands
into major recreation and conservation areas. The land area
of these islands can provide an additional outlet for corn-
posted secondary sludge.
The estimated compost market of 20,000 dry tons per year
would dispose of approximately 25 percent of the secondary
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sludge generated at the MSD wastewater treatment plants. Based
on estimated sludge characteristics, the sludge from the south-
ern MSD service area wastewater will contain lower concentrations
of heavy metals than the sludge from the northern MSD service
area wastewater. Therefore, the compost should consist of
sludge from the southern service area, since this sludge is of
a better quality (lower heavy metals concentration) than the
sludge from the northern service area. It is estimated that
about half of the secondary sludge generated from the treat-
ment of the wastewater from the southern MSD service area could
be disposed of in the form of compost.
The sludge from the northern service area cannot be dis-
posed of as a composted product, since the available market
would be utilized to dispose of sludge from the southern ser-
vice area. Also, as discussed previously, the trucking of
sludge from Deer Island to a landfill will have a major nega-
tive impact on the residential areas adjacent to the Island.
A third alternative for disposing of the northern service area
sludge is incineration. Although the Boston Air Quality
Region is in a status of “non—attainment”, recent investigations
by the Massachusetts Division at Air Pollution Control have
determined that Deer Island is in a “clean zone” of the non—
attainment area. The incineration of the secondary sludge
from the northern MSD service area would produce approximately
125 cubic yards of ash residue per day. This residue, which
must be disposed of, is about 25 percent of the volume of
sludge which would require disposal under the landfill option.
It is felt that incineration is the most practical method of
disposing of the secondary sludge generated from the treatment
of the wastewater from the northern MSD service area.
The remaining half of the southern service area secondary
sludge still requires a method of disposal. Landfilling of
this remaining sludge would not have as severe impacts as
would the landfilling of all the secondary sludge generated
from the treatment of wastewater from the entire service area
or from the northern service area. A landfill area of about
84 acres would be required.
Following the intermediQ e screening process, three
alternative wastewater treatment plant systems were developed
for consideration during final screening.
A. Deer Island - Broad Meadows (See Figure 2)
This alternative includes expanding and upgrading the
existing Deer Island Treatment Plant to provide secondary
treatment for the northern MSD service area wastewater flows,
and the construction of a new treatment plant at Broad Meadows
to provide secondary treatment for the wastewater from the
southern MSD service area.
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DEER ISLAND WASTEWATER TREATMENT PLANT
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Sufficient land area is available on Deer Island to accommodate
the expanded and upgraded treatment facility. The proposed plant
expansion can be accomplished utilizing either the northern and
central portions of the island, or the southern and central por-
tions of the island. In addition, the selected sludge management
plan for the sludge produced at this plant requires an ash dis-
posal site. Adequate area is available for ash disposal in either
treatment plant configuration. In both expansion schemes, the
removal of both the prison and the drumlin are required to provide
adequate area for the treatment and ash disposal facilities. It
is recommended that for this plan, the northern plant expansion be
used and the ash disposal site located at the southern end of the
island. In this way the ash disposal site is located at the most
remote location on Deer Island.
The Broad Meadows site has adequate area to accommodate
the required treatment facilities and a composting operation
to compost at least half of the secondary sludge generated at
this treatment plant; however, an adequate buffer zone between
the treatment facilities and the nearby residences and school
could not be maintained. For this alternative, it is proposed
that the northwest corner of Squantum Point be utilized for
the composting operation. Composting half of the secondary
sludge generated at the treatment facilities at Broad Meadows
would require an area at Squantuni Point of about 21 acres.
The sludge would be transported from Broad Meadows to Squantum
by barge or by truck. The remaining secondary sludge from the
Broad Meadows facility would be trucked from the site to a
landfill.
The primary sludge produced at the treatment plant
serving the southern MSD service area would be pumped through
a pipeline across Boston Harbor to Deer Island, where it would
be dewatered and incinerated along with the primary sludge
produced at the treatment plant at Deer Island, as is re-
commended in a separate primary sludge management EIS.
The effluent from the Deer Island treatment plant would
discharge through the existing outfall system. The outfall
system requires some repair work to restore it to its design
capacity. Approximately 9,000 feet of force main and 4,000
feet of sewer would be required between Nut Island and the
Broad Meadows site in order to transport wastewater from Houghs
Neck and the Braintree-Weymouth pumping station to the treat-
ment facilities at Broad Meadows. The wastewater from the
High Level Sewer upstream of Broad Meadows would be diverted
to the new treatment plant. The effluent from this plant
would flow into the High Level Sewer downstream of the site,
and would be transported to the outfall system at Nut Island.
Since the High Level Sewer is not adequate to handle peak flows
from this plant, a relief pipeline would be required.
Preliminary analysis indicated that there is not adequate
space to locate a relief pipeline parallel to the High Level
Sewer through Houghs Neck, and therefore the required 114 inch
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diameter relief pipeline would be routed under Quincy Bay.
The relief pipeline crossing Quincy Bay will reach Nut
Island at a lower elevation than the High Level Sewer and,
therefore, a pumping station would be required at Nut Island
to lift the plant effluent from the relief pipeline to the
outfall system. During periods of peak flow and high tide, the
plant effluent from the High Level sewer and the relief pipeline
would require pumping in order to be discharged through the
outfall system. Therefore, the existing raw sewage pumping
station on Nut Island owuld be converted to an effluent pump-
ing station. The existing Nut Island outfalls would be
extended to a point in the harbor where the depth of water is
about 45 feet. The remaining facilities of the existing Nut
Island plant would be demolished.
B. Deer Island - Squantum (See Figure 3)
This alternative includes expanding and upgrading the
existing Deer Island treatment plant to provide secondary
treatment for the northern MSD service area wastewater flows,
and the construction of a new treatment plant at Squanturn
Point to provide secondary treatment for the wastewater from
the southern MSD service area.
The wastewater treatment, sludge disposal, and outfall
facilities for the northern service area are the same as
discussed under Alternative A.
The Squantum Point site is large enough to accommodate
a treatment plant to provide secondary treatment for the
wastewater from the southern service area, but there is in-
sufficient area for a composting operation. For this al-
ternative, it is proposed that Broad Meadows be utilized for
cornposting secondary sludge. The composting operation would
be located in the southwest corner of Broad Meadows so that
it is as far away from residential areas as possible. The
sludge could be transported from Squantum to Broad Meadows
either by barge or truck. The remaining secondary sludge
generated at the Squantum Point treatment plant would be
trucked to a landfill. The primary sludge would be pumped
to Deer Island and incinerated as in Alternative A.
A new influent sewer would be required to transport the
wastewater from the High Level Sewer to the treatment plant at
Squantum Point. About 21,400 feet of influent sewer would be re-
quired. In order to transport wastewater from Houghs Neck
and the Braintree-Weymouth Pumping Station to the new in-
fluent sewer, about 9,000 feet of force main and 6,000
feet of sewer would be required. The effluent from the
Squantum Point treatment plant would leave the plant through
two effluent pipelines. One effluent pipeline would connect
to the High Level Sewer downstream of the influent sewer
connection. From this point to Nut Island the High Level Sewer
10

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would serve as an effluent conduit. The second
effluent pipeline, which is required during periods of high
wastewater flows, would be routed across Quincy Bay to Nut
Island. An effluent pumping station would be required at
Nut Island to discharge the wastewater flow to the Nut Island
outfall system. An additional pumping station would be re-
quired to lift the flow from the Quincy Bay effluent pipeline
to the effluent pumping station, and the outfall system would
be extended to reach deeper water.
C. All Deer Island (See Figure 4)
This alternative includes expanding and upgrading the
existing Deer Island Treatment Plant to provide secondary
treatment for the was ewater from the entire MSD service
area. Due to different heavy metal characteristics of se-
condary sludge from the northern and southern service areas
and the decision-to dispose of the sludges by different methods,
it is necessary to xeep the secondary sludge from the
northern and southern service areas separate. In order to
accomplish this, it is necessary to keep the wastewaters from
the northern and southern service areas separate and to pro-
cess the secondary sludge from the two service areas separately.
Constructing the facilities which are required to pro-
vide secondary treatment for the wastewater from the entire
MSD service area on Deer Island requires utilizing the areas
currently occupied by the prison and the drumlin and all but
about 18 acres of the land south of the drumlin. While sludge
dewatering and incineration would be accomplished on Deer
Island, there is not enough area for ash disposal and corn-
posting operations. However, since this alternative utilizes
only one site for wastewater treatment, it would be possible
to utilize one of the sites which were considered for treatment
facilities in the previous two alternatives for the ash dis-
posal and composting operations. Due to the relatively
isolated location of the Squantum Point site as compared to
Broad Meadows, Squantum Point would be the better location
for the ash disposal and composting operations.
The portion of the High Level Sewer that passes through
the Houghs Neck section of Quincy requires relief in order to
be able to transport anticipated peak flows. Since there
does not appear to be adequate space to locate a relief sew-
er parallel to the High Level Sewer through Houghs Neck, the
required 114 inch diameter relief sewer would be routed un-
der Quincy Bay. This relief sewer will reach Nut Island at a
lower elevation than the High Level Sewer, and therefore a pump-
ing station would be required at Nut Island to lift the waste-
water from the relief sewer to a new headworks. This head-
works would be required at Nut Island in order to provide
12

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screening and grit removal prior to transporting the southern
service area wastewater across Boston Harbor to Deer Island.
In order to transport the wastewater from the new head-
works at Nut Island to the treatment facilities at Deer Island,
a submerged pipeline consisting of two 108 inch diameter pipes
across Quincy Bay and along Long Island would be required. From
the northern end of Long Island a deep rock tunnel, 150 inches
in diameter, would be constructed to carry the wastewaters to
Deer Island. Most of the existing facilities on Nut Island
would be demolished.
In addition to utilizing the existing outfall system at Deer
Island, a new outfall pipe would be required. This pipe would
be 120 inches in diameter and about 2100 feet long. Diffusers
added to the end of the outfall, in water at a depth of about
60 feet, would provide adequate dispersion of effluent.
D. Comparative Analysis
On inspection, it can be seen that the Deer Island-Broad
Meadows and the Deer Island-Squantuni alternatives are similar.
One area in which these alternatives differ greatly is the
need for additional interceptor construction. The Deer Island-
Squantum alternative requires an interceptor to convey waste—
water from the High Level Sewer to the Squantum Point plant.
This sewer is of substantial size, 10 feet by 14 feet, and is
over 4 miles in length. In addition, a parallel 144 inch
effluent pipeline would be required from the plant back to
the High Level Sewer. A second effluent pipeline would be
required for periods of peak flow. This effluent sewer would
be routed under Quincy Bay to Nut Island.
Since the High Level Sewer passes adjacent to the Broad
Meadows site, influent and effluent sewer requirements to
connect this site to the sewer are minimal. For the Deer
Island—Broad Meadows alternative, an effluent pipeline would
also be required under Quincy Bay to transport peak flows.
However, this pipeline would be less than half the length of
the effluent pipeline required under the Bay from a treatment
plant at Squantum.
A detailed field study undertaken to select the best
route for the parallel sewers required between the High Level
Sewer and Squantum and to evaluate the construction impacts on
the surrounding areas. The field evaluation indicated that the
effects of sewer construction between the High Level Sewer and
Squantum would be severe in spite of all reasonable attempts
to reduce impacts. Among the effects which are unavoidable are
the removal of mature roadside vegetation, traffic disruption,
and negative effects on local businesses due to extended street
closures.
The need for these additional sewers, including the
longer subaqueous crossing of Quincy Bay, weighs heavily
14

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against the Deer Island-Squantum alternative. In addition to
construction impacts, additional energy is required on a
continuous basis for wastewater pumping. It is estimated
that the Deer Island-Squantum alternative would require about
5.9 million kilowatt hours per year of electricity over and
above that required for the Deer Island-Broad Meadows alter-
native.
Given these facts, the Deer Island-Broad Meadows alter-
native emerges as the better of the two alternatives. The cost
estimates for the two alterantives (see Table 1) show that the
Deer Island-Squantum alternative involves approximately $3,500,000
per year additional cost (amortized capital cost and operation
and maintenance cost).
When comparing the Deer Island-Broad Meadows and the All
Deer Island alternatives, an immediate difference arises in
the number of sites which are required. The Deer Island—
Broad Meadows alternative requires three sites while the All
Deer Island alternative requires only two. The Broad Meadows
site is not needed for the latter alternative. The price
which must be paid to eliminate one site is that a major
harbor crossing is required. This component of the project
also involves significant environmental impacts.
With all the treatment facilities on Deer Island, further
advantages in routine operation and maintenance activities can
be realized. That is, a more efficient operation, in terms of
manpower and costs, will be realized. Energy costs also favor
the All Deer Island system. It is estimated that this alter-
native would use about 7.5 million kilowatt hours less electric
power annually than the Deer Island-Broad Meadows alternative.
With respect to outfall considerations, the All Deer Island
system would require the construction of an additional outfall
into President Roads to handle peak flows. This is comparably
offset (in terms of construction) by the extension of the Nut
Island outfall system required under the Deer Island-Broad
Meadows alternative. An important difference, however, is
that the All Deer Island system would completely remove all
sewage discharges from Quincy Bay and would add additional
effluent flow into President Roads. However, the Deer Island
outfall would extend into 60 feet of water depth which would
provide ample dilution.
Amendments to Public Law 92—500 in December, 1977 (PL95—
217) allows the requirement for secondary treatment to be
waived in certain coastal areas if eight specific statutory
requirements are fulfilled. Should this occur in the Boston
area, it is expected that some additional treatment beyond
primary would be required (perhaps chemical treatment to re-
duce metal concentrations) and a longer ocean outfall would
be needed to discharge the effluent out of the harbor. This
modification would favor the All Deer Island alternative, since
a single outfall to reach offshore waters would be more efficient
15

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TABLE 1
COMPARISON OF COSTS’
All Deer Deer Island— Deer Island-
Island Plan Broad Meadows Plan Squantum Plan
Wastewater treatment
Facilities 404,29 1,000 425,755,000 420,509,000
Secondary Sludge Management 58,785,000 64,144,000 64,144,000
Interceptor System 3 307,620,000 248,772,000 307,951,000
Total Capital Costs 770,696,000 738,671,000 792,604,000
Amortized Capital Costs 4 59,783,000 57,299,000 61,482,000
Operation and Maintenance Costs 24,765,000 25,961,000 26,233,000
Total Annual Costs 84,548,000 83,260,000 87,150,000
Applicant’s Share of
m Capital Cost (10%) 77,070,000 73,867,000 79,264,000
Applicant’s Share of
Amortized Capital Cost 5,978, 00 5,730,000 8,772,000
Applicant’s Share of
O & M Costs 24,765,000 25,961,000 26,233,000
Applicant’s Share of
Total Annual Cost 30,743,000 31,691,000 35,005,000
(1) Engineering News Record Construction Index = 2654
(2) Includes work at Nut Island and Outfall
(3) Includes submerged pipelines, tunnel and related pumping stations
(4) Assume average life of facilities = 30 years; Interest rate = 6—5/8 percent.

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than the extension of two outfalls, as would be necessary for
the Deer Island-Broad Meadows alternative. Also, since secon-
dary sludge would not be generated, there would be no need to
utilize the Squantum site. This would reduce the number of
sites used to one.
To summarize, the All Deer Island alternative is superior
in terms of the number of sites required; operation and main-
tenance advantages; lower energy costs; and a more favorable
outfall location. The Deer Island-Broad Meadows alternative
is superior in terms of pipeline construction.
In terms of estimated total annual cost, the two alter-
natives are relatively similar — about $83,300,000 for the
Deer Island-Broad Meadows alternative and about $84,500,000
for the All Deer Island alternative.
The All Deer Island alternative emerges as the better of
the two alternatives and is the recommended system.
VI. OTHER OPTIONS
Three additional wastewater management option which must
be considered prior to the selection of a Recommended Plan are:
The EMMA Plan; the No Action Plan; and the Modified No Action
Plan. These options are described below.
A. EMMA Plan
The MDC’s proposed wastewater management plan, as pre-
sented in the EMMA Study, includes secondary treatment plants
at Deer and Nut Islands and two advanced wastewater treatment
plants (providing a higher degree of treatment than secondary)
at inland locations.
The existing Deer Island Primary Treatment Plant would
be expanded and upgraded to provide secondary treatment to the
wastewater from the northern MSD service area. The proposed
facilities would be constructed to the north of the existing
facilities, and would require removing the prison and filling
about 14 acres of Boston Harbor.
The wastewater from the southern MSD service area would
receive treatment at three treatment plants. One of these
plants would be located on Nut Island. The existing Nut Is-
land Primary Treatment Plant would be expanded and upgraded to
provide secondary treatment. Nut Island is presently almost
completely occupied by the existing treatment plant, and the
additional facilities would be constructed on an area of fill
of about 28 acres in Quincy Bay.
The remaining wastewater from the southern service area
would receive treatment at two inland satellite advanced
17

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wastewater treatment plants. One of these plants would be
located along the Charles River and the other satellite
plant would be located along the Neponset River.
The sludge produced at the Nut Island plant would be
pumped through a force main across Boston Harbor to Deer Is-
land, where it would be dewatered and incinerated with the
sludge produced at the Deer Island plant. The resulting
ash from the incinerators would be disposed of in an ash
landfill. The sludge produced at the satellite plants would
undergo incineration at each plant.
Under this plan, modifications and additions would be
made to the existing interceptor sewer system. About 32
miles of sewers ranging in size from 12 to 66 inches in dia-
meter would be added to the northern interceptor sewer system,
and about 36 miles of sewers, from 21 to 78 inches in diameter,
would be added to the southern interceptor sewer system. In
addition, each of the ten pumping stations which are located
along the interceptor system would be renovated or replaced in
order to provide efficient operation and adequate capacity
for future flows.
The EMMA Plan also includes several combined sewer over-
flow regulation projects which would provide collection,
treatment and disposal facilities to replace the numerous
combined sewer overflows which presently discharge to Boston
Harbor and its tributaries.
B. No Action Plan
The No Action Plan assumes that no capital improvements
will be made to the existing wastewater management system.
Within the MSD system there presently exists about 225
miles of trunk sewers, serving over 5,000 miles of local
sewers; 12 pumping stations (including two at wastewater
treatment plants); four headworks; and two primary treat-
ment plants, one located at Nut Island and the other at Deer
Island. Consideration of the No Action Plan implies the con-
tinued use of the present system’s facilities with its present
levels of effluent discharge. The No Action Plan would provide
for operation and maintenance of the existing interceptors,
pumping stations, headworks and treatment plants in the MSD
service area. No additional towns would be added to the
service area and no interceptor relief would be provided.
Present pumping station, interceptor and treatment plant
capacities would remain limited. Present excess flows and
future additional flows would exceed the capabilities of the
existing facilities.
18

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The average daily flow presently entering the Nut Island Pri-
mary Treatment Plant is above the plant’s average design capacity.
Built in 1952, much of the original equipment is in need of
repair or replacement. Assuming the plant is maintained at
present levels, poorly treated wastewater will continue to be
discharged into Boston Harbor. Following digestion of the
plant’s sludge, the unchiorinated sludge is disposed of
through a pipeline extending into deep tidal water.
The Deer Island Primary Treatment Plant, constructed in
1968, is in relatively good condition. It is anticipated
that the quantity of wastewater reaching the plant will ex-
ceed its design capacity in the near future. The discharge
from the facility is a mixture of chlorinated effluent and
digested sludge which is released from the plant into President
Roads. Three emergency outfalls exist for high flow periods.
C. Modified No Action Plan
This Plan includes specific plans which have been made,
but are yet to be implemented, or are presently in the pro-
cess of being implemented. These include the regulation of
combined sewer overflows and the treatment and disposal of the
primary sludge generated at the wastewater treatment facili-
ties. Present combined sewer overflow regulation facilities
consist of the following:
1. The East Boston pumping stations and the North
Metropolitan Trunk Sewer which have a capacity
to divert about 120 mgd from upstream areas
to Chelsea Creek or to the Deer Island Treat-
ment Plant.
2. The Boston Calf Pasture pumping station which
diverts about 155 mgd of flow during periods
of wet weather to the holding tanks on Moon
Island prior to overflowing to Boston Harbor.
3. The Cottage Farm Chlorination and Detention Station
designed to treat up to 233 mgd prior to overflowing
into the Charles River Basin.
4. The Somerville Marginal Conduit Project which
is designed to treat about 160 mgd prior to
overflowing into the Mystic River tidal
waters.
5. The Charles River Marginal Conduit Project presently
under construction, to treat about 323 mgd prior to
discharge to the Harbor.
Approximately 125 combined sewer outlets presently dis-
charge to Boston Harbor and its tributaries. The proposed
19

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Combined Sewer Overflow Regulation Program will provide a sys-
tem to eliminate these discharges by collecting the flows and
providing treatment and disposal facilities. Treatment will
consist of screening, skimming, sedimentation, and chlorination.
Under the primary sludge management plan, the sludge from
the existing Nut Island Primary Treatment Plant will undergo
digestion prior to being pumped through a force main across
Boston Harbor to Deer Island. At Deer Island this digested
sludge will be combined with the primary sludge from the Deer
Island plant. The sludge will then be dewatered and
incinerated at Deer Island.
VII. SELECTION OF THE RECOMMENDED PLAN
A comparison of the All Deer Island, EMMA, No Action and
Modified No Action Plans was made so that a selection of a
recommended plan could be made.
With respect to water quality considerations, the All Deer
Island Plan is the only plan which will meet water quality
standards. This system will not affect water quality in inland
streams and will greatly improve the quality of the existing
effluent discharges. The EMMA Plan will similarly improve the
quality of the harbor discharges and will reduce their volumes
somewhat. The EMMA Plan, however, will cause degradation of
water quality in the Charles and Neponset Rivers. A
Neponset River discharge will cause its dissolved oxygen stand-
ard to be violated, while the Charles River discharge will
significantly increase the magnitude of projected water qual-
ity violations. The No Action Plan will result in the con-
tinued degradation of harbor waters. The Modified No Action
Plan will cause an improvement in ambient water quality con-
ditions, but degradation in the vicinity of the existing
primary discharges will persist. Overall, the All Deer Island
Plan is the best of the four systems with respect to water
quality.
In terms of water quantity, the All Deer Island Plan and
both No Action Plans will have a similar effect. That is,
they will result in the export of water from the Charles and
Neponset watersheds in the form of wastewater. For the Charles
River watershed, this loss will be approximately offset by
additional point source discharges to the river. For the Ne—
ponset River, an estimated export of 12 mgd has been
projected. The EMMA Plan, since it will result in the dis-
charge of treated effluent to the rivers, will result in sub-
stantially higher dry weather river flows than have occurred
in the past, but at the expense of water quality.
The effects of the No Action Plan on the area’s biotic
communities will represent a continuation of present trends.
That is, organisms associated with polluted waters will re—
20

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main. Increased degradation of water quality as a result of
increased pollutant loads will continue to damage the harbor’s
flora and fauna as well as the public’s use of them. The Mod-
ified No Action Plan will improve the situation except in the
vicinity of the existing primary treatment plant outfalls.
Both the EMMA Plan and the All Deer Island Plan will further
improve biotic conditions.
The EMMA Plan will require the use of two addtional sites
for facilities construction and specifies the filling of Quincy
Bay to expand the Nut Island plant and the filling of Boston
Harbor to expand the Deer Island plant. This is considered to
be a major impact. The All Deer Island Plan avoids filling the
harbor but requires the complete use of Deer Island plus a
major harbor crossing. Also, additional interceptor relief is
required for the All Deer Island Plan.
In terms of construction-related impacts, both the All
Deer Island Plan and the EMMA Plan will cause more disturbance
than either of the No Action Plans. Each of these systems will
produce its own set of characteristic construction impacts,
which cannot be easily separated.
As far as air quality characteristics are concerned, the
No Action Plan would result in the least air emissions followed
by the Modified No Action Plan. The Modified No Action Plan
represents an increase in emissions to the ambient air due to
the incineration of the primary sludge. Comparisons of the
emissions from primary and secondary sludge incineration for
the All Deer Island Plan and EMMA Plan indicates the All Deer
Island Plan would have less of an air quality impact. This is
based upon the lower quantities of emissions and the site location
of the All Deer Island Plan. This differential is offset,
however, by the need to establish a landfill for disposal of
digested sludge under the All Deer Island Plan.
The No Action Plan, while it is the least expensive and
has the least impact on air quality, is not considered feas-
ible. Existing primary sludge discharges to Boston Harbor,
poor efficiency of existing facilities, gross and visible
pollution from the Nut Island facility, and persistent bacter-
ial contamination of the harbor render this plan untenable
The Modified No Action Plan will improve water quality
conditions and benefit the harbor’s biota in a general sense,
but the gross pollution from the existing primary outfalls and
by-passes will persist. Pollution from primary sludge dis-
charges will be abated, however. This plan is significantly
less expensive than either the All Deer Island Plan or the
EMMA Plan and will be more favorable in terms of air quality
impacts and primary construction—related impacts. This plan
is rejected, however, on the basis of permitting unacceptable
water quality conditions to persist.
21

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The EMMA Plan and the All Deer Island Plan both further
improve water quality conditions in Boston Harbor. As described
previously, these alternatives vary in terms of their specific
impacts, but they can be separated on the basis of several
significant parameters. These include:
1. The violation of water quality standards in the
Neponset River and a further deterioration of the
Charles River under the EMMA Plan.
2. The need for 42 acres of fill in Boston Harbor under
the EMMA Plan.
3. The need for a major harbor crossing, additional
interceptor relief and drumlin removal under the All
Deer Island Plan.
Beside these factors,the other levels of impact are generally
similar, with some trade-offs existing between the plans. Costs
are approximately equal (see Table 2). While item #3 above
represents significant impacts, they can be justified in light
of the magnitude of the problem and it solution. Except for the
drumlin removal, these effects are short term. Items #1 and #2
however, represent long term impacts which are considered un-
acceptable. The solution of a wastewater management problem
should not create other water quality problems, and the loss
of 42 acres of Boston Harbor represents an irreversible
imoact which should not be accepted if a feasible alternative
exists. Therefore, the All Deer Island Plan was selected
as the best of the four systems.
VIII. DESCRIPTION OF THE RECOMMENDED PLAN
The wastewaters from the member communities of the MDC’S
Metropolitan Sewerage District will be treated at a secondary
wastewater treatment plant at Deer Island. The existing interceptor
system and related pumping stations will be expanded and mod-
ified as required to handle peak flows. The wastewater from
the southern interceptor system will recieve preliminary
treatment at a headworks at Nut Island and be transported to
Deer Island through a pipeline-tunnel system under Boston
Harbor. The secondary sludge produced at the Deer Island
Treatment Plant will be dewatered and disposed of by a com-
bination of incineration, composting, and direct landfilling.
The ash disposal and composting operations will take place at
Squantum Point. (See figures 5,6,7 and 8)
Prior to and during facilities planning special consider-
ation should be given to the effect c.f flow and waste reduction
measures on the flows used in the design of facilities. At
present,excessive infiltration/inflow conditions exist in both
the local sewer systems and in the MDC’S interceptors. A
thorough analysis of this condition is necessary to determine
how much of this excess flow can be removed cost effectively.
22

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TABLE 2
COMPARISON OF COSTS’
All Deer
Island Plan EMMA Plan
Wastewater reatment
Facilities’ 404,291,000 503,400,000 ’
Secondary Sludge Management 58,785,000 33,892,000’
Interceptor System 3 307,620,000 132 ,532,000
Total Capital Costs 770,696,000 669,824,000
Amortized Capital Costs 6 59,783,000 51,958,000
Operation and Maintenance Costs 24,765,000 30,447,000
Total Annual Costs 84,548,000 82,405,000
Applicant’s Share of
Capital Costs (10%) 77,070,000 66,982,000
Applicant’s Share of
Amortized Capital Cost 5,978,000 5,196,000
Applicant’s Share of
O & M Costs 24,765,000 30,447,000
Applicnat’s Share of
Total Annual Cost 30,743,000 35,643,000
(1) Engineering News Record Construction Index = 2654.
(2) Includes work at Nut Island and outfall.
(3) Includes submerged pipelines, tunnel and related pumping stations.
(4) From EMMA Study, adjusted to ENR CI of 2654.
(5) Includes satellite treatment plants,and satellite sludge management.
Adjusted to account for primary sludge.
(6) Assume average life of facilities = 30 years; Interest rate 6—5/8 percent.

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A recently completed tide gate rehabilitation program should
result in a reduction in the amount of seawater that enters
the interceptor system. The effects of that program should be
evaluated to determine the extent of its success.
Water conservation is another source of flow reduction
that should be employed. Through a conscientious area wide
water conservation program significant wastewater flow reduction
is possible. While it is recognized that such a program will
take several years to gain momentum, it could have a substantial
effect in reducing the impact of projected future flow increases.
The interceptor system presently serving the MSD is over-
loaded in some sections and in need of relief. The determination
of which sections require relief and the size of the relief
structures was accomplished by matching the hydraulic
capacities of the existing facilities with present and future
flow rates. The amount of excess flow determined the amount
of relief required. The interceptor modifications are de-
signed for a 50 year design life.
About 32 miles of interceptor relief are required in
the northern service area. The southern service area requires
about 56 miles of interceptor relief. Space constraints in
the Houghs Neck area necessitate that the sewer required to
relieve the High Level Sewer be placed under Quincy Bay.
This relief sewer requires a pumping station at its termination
at Nut Island to lift its flow to the same level as the waste—
water in the High Level Sewer.
The wastewater from the southern service area will be
transported from Nut Island to Deer Island via a submarine
pipeline and tunnel system across Boston Harbor. Before enter-
ing this pipeline-tunnel system, the wastewater should re-
ceive preliminary treatment to remove large objects and grit.
Therefore, a headworks is provided at Nut Island.
The Boston Harbor crossing consists of two 108 inch dia-
meter pipes installed under the bottom of the harbor between
Nut Island and the northern tip of Long Island, and a 150 inch
diameter deep rock tunnel under the President Roads Channel
between Long Island and Deer Island.
In order to meet NPDES permit requirements for wastewater
treatment plant discharges, secondary treatment is required.
This level of treatment will provide monthly average concen-
trations of BOD and suspended solids which are no more than 30
mg/l. This level of effluent discharge requires removal of
approximately 85 percent of incoming wastewater pollutants.
The air activated sludge process was selected to achieve this
level of effluent quality. The method of sludge disposal Se-
lected requires that the wastewater streams from the northern
and southern service areas be kept separate.
24

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PAGE NOT
AVAILABLE
DIGITALLY

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- J
I’
SCALE IN FEET
*
0
25
50
H
I
SCALE IN METERS
LEGEND
EXISTING FACILITIES
TO BE DEMOLISHED
0 EXISTING FACILITIES
TO BE MODIFIED
NEW FACILITIES
FACILITIES
TO BE DEMOLISHED
NEW SCREEN AND
GRIT CHAMBER
EXISTING SCREEN AND
GRIT CHAMBER BUILDING
TO BE MODIFIED
LIFT STATION
FIGURE 6 NUT ISLAND FACILITIES REQUIRED FOR RECOMMENDED PLAN

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300 0 300 600
TANKS
ADMINISTRATION
CHLORINE
BUILDING
FINAL
SETTLING
STATION
LEGEND
EXISTING WASTEWATER TREATMENT FACILITIES
OTHER EXISTING STRUCTURES
NEW WASTEWATER TREATMENT FACILITIES
REQUIRED - YEAR 2000
FUTURE EXPANSION - YEAR 2O O
PUMPING
STATION
SCALE IN FEET
10 9 100 200
SCALE IN METERS
FINAL
SETTLING
TANKS
DRUMLIN
OUTLINE
AERATION
TANKS
AREA FOR PRIMARY
SLUDGE ASH
DISPOSAL
0
I,
‘I
FIGURE 7 RECOMMENDED PLAN DEER ISLAND FACILITIES

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300
0 300 600
JORDAN
MARSH
WAR EHOUSE
200
0
SCALE N FEET
200
SCALE IN METERS
ASH DISPOSAL AREA
FIGURE 8 SQUANTUM POINT ASH LANDFILL AND
SLUDGE COMPOSTING AREA
400
MARINA

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Preliminary treatment of the northern service area wastewaters
will continue to be provided by the Ward Street, Columbus Park and
Chelsea Creek Headworks and the Winthrop Terminal Facility on
Deer Island. Wastewater from the southern service area will re-
ceive preliminary treatment at a new headworks at Nut Island. This
new headworks will include the existing Nut Island plant’s screening
and grit removal facilities, which will be renovated and modernized,
with additional facilities added to accommodate the increased flows
expected.
A pumping station located near the southern end of Deer Island
will lift the wastewater from the southern service area into pri-
mary treatment facilities. The existing primary treatment facili-
ties on Deer Island will be expanded with the addition of eight pri-
mary settling tanks for the northern flow, and eight primary sett-
ling tanks will be provided for the southern flow. Provision is
made for additional primary treatment facilities which will be re
quired for future flows.
Secondary treatment will be accomplished through the use
of twenty aeration tanks for the northern wastewater flow and
eleven aeration tanks for the southern wastewater flow.
Although the flows will be kept separate, a common air supply
will be used for both facilities. Provision is also made for
future expansion for this phase of treatment.
Final sedimentation tanks provide the other half of sec-
ondary treatment at Deer Island. Thirty—two tanks will be
provided for the northern wastewater flow, and fifteen tanks
will be provided for the southern wastewater flow, with
provision made for the addition of facilities for future flows.
Sludge collected from the northern flow final sedimentation
tanks will be either returned to the northern flow aeration tanks
for process control or wasted to the sludge management facility
for dewatering and incineration. Sludge collected from the
southern flow final sedimentation tanks will be either returned to
the southern flow aeration tanks for process control or wasted to
the sludge management facility for conditioning and dewatering
prior to composting or landfilling operations.
Disinfection will be accomplished through the use of chlorine
and a chlorine contact basin. Provision will be made for a 15
minute detention time at periods of peak flow. This is the first
place in the treatment process where the wastewaters from the north-
em and southern service areas are combined. Effluent discharge
is accomplished with an effluent pumping station and a modified
outfall structure.
Secondary sludge disposal will be accomplished using three
methods; incineration, landfill and composting. The
selection of the methods used was based on the characteristics
30

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of the sludge and the desire to prov:ide an acceptable alternative
to incineration of all the sludge.
The sludge that is wasted to the sludge management facility
will be thickened using air flotation thickeners, with separate
thickeners used for the northern and southern sludges. After thick-
ening, the southern sludge to be composted is conditioned with ferric
chloride and lime and is then dewatered in a filter press. The
resulting sludge cake is then loaded into containers for shipment
to Squantum Point by barge. The portion of the southern sludge to
be composted is approximately 23 percent of the total secondary sludge
produced, or about 50 percent of tfle southern secondary sludge. The
remaining southern sludge will be taken to anaerobic dig€stcrs after
thickening, where, in the absence of oxygen, microbial activity
produces a stable end product. The fuel value of the gas produced
in this process will be utilized to maintain an ader u&te digestion
temperature. After digestion, this sludge will be chemically con-
ditioned with ferric chloride and lime, dewatered using pressure
filtration, and barged in containers to Squantum Point. From
Squantum Point the sludge will be trucked to an MDC operated sludge
landfill.
The secondary sludge produced in the treatment of the northern
service area wastewaters will be chenically conditioned with lime
and ferric chloride following air flotation thickening. The re-
sulting material will then be dewatered in a pr€ sure filter. The
resulting sludge cake will be burned in multiple hearth incinerators.
The ash, and particulate matter from the air pollution control
equipment, will then be loaded into containers for barge shipment
to the Squantuiv Point ash landfill. Storage space .Ecr ash and
sludge will be provided at Deer Island for inclement weather
periods when daily barge shipments may not be possible.
Composting and ash landfill operations at Squantum will occur
within the confines of a landscaped earth embankment. The area
will be lined with an impermeable liner to prevert leachate from
mixing with local groundwater. A leachate collection system will
be constructed to collect all rainfall in the landfill area and
discharge it to the MDC interceptor in Squantum for return to the
treatment plant. Sufficient area will be proviaed at Squantum Point
for twenty years of ash storage. After several years cf operation
it may be necessary to compost sludge on tcp of ccmpleted ash land-
fill areas. When the landfill reaches its design height, it will
be covered with topsoil and may be converted to a recreational area.
Approximately 125 cubic yards cf ash material will be landf-lled
at Squantum Point each day. Compost production will Vary from 70
to 98 cubic yards per day depending on the type of bulking agent
used. The sludge volume which will be directly landfilled will
be approximately 227 cubic yards per day.
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IX. IMPACTS OF THE RECOMI ENDED PLAN
A. Water Quality
Implementation of the Recommended Plan will eliminate the dis-
charge of primary effluent and sewage overflows into the southern
portion of Boston Harbor. Cessation of the Nut Island treatment
plant operation should yield an immediate aesthetic improvement in
Quincy Bay due to the elimination of wet weather plant bypasses
which discharge floating debris and solids to near shore areas.
Elimination of the continuous primary effluent discharge removes
significant pollutant inputs from the southern portion of the Har-
bor and thus will have a long term positive impact upon its water
quality Productive shellfish beds, presently adversely influenced
by these bypasses should, over time, become useable.
Pretreatment removal of heavy metals, as well as removal by
the secondary facility, cannot be quantified at this time. Actual
removals will depend upon the success of the MDC in implementing
and enforcing its pretreatment program and the ability of the
secondary facility to remove the toxic materials. Unless inputs
are reduced, high concentrations of toxic metals in northern Boston
Harbor can be expected to continue.
Analysis has indicated a properly diffused discharge to Presi-
dent Roads will not violate water quality criteria. All outfalls
must include diffusers to ensure proper near field dilution of
the wastewater. Water quality impacts can be minimized if the
outfall system is designed to achieve the greatest dilution, in
excess of 50:1, that the hydrodynamics of President Roads will
permit.
The discharge of chlorinated secondary effluent into Boston
Harbor can have significant water quality impacts. The recommended
water quality criteria to protect marine organisms is 10 mg/i of
total residual chlorine. In addition to toxicity effects, residual
chlorine has been reported as impairing fish flavor. Chlorination
of wastewater also results in the formation of chlorinated organics.
Alternative disinfection processes or disinfecting only during the
summer may be utilized to mitigate these impacts.
Dredging operations for the required harbor crossings will
have a temporary negative impact upon water quality. Excavation of
bottom materials can cause increased water column turbidity and sus-
pended solids levels. Depending upon prevailing currents, these
effects may not be localized in the vicinity of the dredge site.
However, construction techniques are available to minimize these
impacts.
Disposal of dredge material will also present problems. In-
creased suspended solids and turbidity will occur at the disposal
site. Disposal of this material at an approved dumpsite will not
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eliminate these impacts; however, the use of an approved dredge
spoils disposal site will confine the impacts to an acceptable area.
The “foul area” of Massachusetts Bay appears to be an environment-
ally acceptable disposal site due to the existing degradation of
the area caused by previous dumping. Disposal of dredge spoils
back into the harbor for backfilling the trench following construc-
tion of the harbor crossing will cause additional water quality
impacts. Only material which is substantially free of colloidal
particles should be used for backfill.
Potential exists for long term adverse water quality impacts
from landfilling of sludge and incineration ash. Leaching of toxic
metals poses a potential threat to surface and groundwaters proxi-
mate to the disposal sites. Disposal of these materials by land—
filling in a “secured landfill” (one from which all leachate and
surface drainage is collected for treatment) will prevent these im-
pacts.
Interceptor relief programs will have a positive impact upon
water quality by eliminating overflows to the rivers from hydraulic-
ally overloaded sewers during wet periods.
In summary, the following water quality impacts are associated
with the recommended wastewater management plan. Positive impacts
resulting from the upgrading to secondary treatment and consolida-
tion of all treatment on Deer Island include improved quality in
southern harbor waters, reduced discharge of pollutants to Presi-
dent Roads, and the elimination of sludge discharges and inter-
ceptor overflows. Dredging activities will cause temporary nega-
tive impacts. In addition, potential negative water quality im-
pacts are associated with landfilling of incinerator ash and sec-
ondary sludge as well as wastewater chlorination, Negative un-
pacts may be reduced and deemed acceptable through institution of
proper mitigating procedures.
B. Water Quantity
The Recommended Plan will result in the export of about 57.5
mgd of water to Boston Harbor from local watersheds. This export
represents a negative impact upon those watersheds. Infiltration/
Inflow (I/I) represents a significant potential loss of local
water, especially from the Charles and Neponset Rivers where in-
terceptors run through sand and gravel deposits adjacent to the
rivers. These potential impacts may be mitigated through effective
water conservation and a vigorous program to correct excessive I/I.
C. Air Quality
The effects of the Recommended Plan on air quality will be
primarily due to the incineration of sludge, with transportation
related sources providing a secondary, and relatively minor, ad-
dition to pollutant emmissions. On the basis of air quality
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modelling it was determined that Prevention of Significant Deteriora-
tion Standards (PSD) would not be violated. With the exception of
the 24 hour maximum emmissions for sulfur dioxide, which uses 38
percent of the allowable PSD increment, 28 percent or less of the
allowable increment is used by sources from the Recommended Plan.
However, it is projected that National Ambient Air Quality Standards
(NAAQS) will be violated, for the 24-hour secondary particulate
standard only, due to background concentrations at certain monitoring
stations. Therefore, emission offsets may be required.
Examination of the annual sulfur dioxide projections shows
that the levels expected at Deer Island are well below the primary
and secondary air standards. The addition of sulfur dioxide con-
centrations from the Recommended Plan, as indicated by the air model,
would not cause a violation of any standard.
Transportation related emissions are a second source of air
pollutants resulting from the Recommended Plan. The sources of
these emissions are heavy duty vehicles, barge traffic and worker
related automobile traffic.
The annual number of miles traveled during construction for
heavy duty diesel trucks was estimated to be 39,000 miles (worst
case condition). This mileage was multiplied by emission factors
obtained from Supplement No. 5 for Compilation of Air Pollution
Emission Factors (USEPA, 1975). During the operation and main-
tenance (O&M) phase of the project the number of vehicle miles
traveled increases greatly due to the landfilling of sludge and
removal of compost. It is estimated over 1.5 million miles of
travel will occur annually. This includes about 1.2 million
miles of travel due to the removal of compost.
There would be a substantial increase in barge traffic due
to the Recommended Plan. Emissions were calculated for both the
construction and 0 & M phases of the project for barge related
emissions. Emissions were based upon the estimated number of
miles traveled and the emission factors from Compilation of Air
Pollutant Emission Factors, AP-42 (USEPA 1975).
Automobile emissions were calculated based upon vehicle miles
traveled by workers to and from work during the construction and
0 & M phases. It was assumed, as a worst case, that each worker
would drive to work alone and have a 30 mile round trip. Emission
factors were obtained from Supplement No. 5.
As a result of the above mentioned calculations, it was deter-
mined that transportation related emissions would cause an insig-
nificant addition of pollutants to the ambient air concentrations.
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D. Noise
Three sites were examined for noise related impacts; Deer
Island, Nut Island and Squantum. The State of Massachusetts has
no noise standards indicating specific noise levels, in decibels
which are acceptable or unacceptable. Theret .re,. the City of
Boston’s Noise Control Regulations were used as a guideline for
acceptable noise levels.
Winthrop is the nearest community with residences that may
be affected by noise from Deer Island. The nearest residence is
about 700 feet from the closest portion of the proposed plant.
Assuming that the highest noise level emanating from the completed
plant is 88 decibels, which has been measured and originates at
the main pumping station, a level of 50 dBA may be expected in the
vicinity of the nearest residence. This level is acceptable for
residential areas and therefore, it is not expected that noise
levels during the operation of the Deer Island Treatment Plant
would impact on local residences.
Noise levels at the Squantum site, due to facility operations,
should not impact any local residences. At present, the nearest
property to be impacted would be commerical in nature. The use of
equipment on site during operation is not expected to cause any
detrimental noise impacts. On Nut Island a lift station and head—
works are to be cons tructed. Noise levels during operation should
not impact upon adjacent residences.
The noise levels generated by construction equipment would not
have any significant impact at the Squantum site. On Deer Island,
noise levels should meet the City of Boston’s Construction Noise
Regulations at the Winthrop boundary. During the demolition of
existing facilities at Nut Island, impact noise may frequently
approach the maximum level specified in the Construction Noise
Regulations at the nearest property line.
At Squantum, approximately 125 vehicle round trips per day
would be made, removing compost and digested sludge and bringing
in treatment plant supplies for use at the Deer Island Treatment
Plant. The impact on surrounding areas should be minimal at
Squantum due to the existing commercial nature of the area and
the proximity to major transportation arteries. However, with
the possible residential use of the adjacent parcel, the potent-
ial for nuisance effects may increase.
Assuming all workers were to drive to the Deer Island site,
the roadways through Winthrop would become extremely congested
since the carrying capacity of the roads would be exceeded. Noise
levels through the community would be increased due to construc-
tion worker traffic.
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Noise levels would increase near Quincy Great Hill (Sea Avenue)
due to the increase in traffic to Nut Island. However, this should
occur only during periods of peak traffic flow. Sea Street should
not experience any noticeable increase in traffic or noise levels
due to construction at Nut Island, since it would produce a minimal
increase relative to the existing traffic volume.
The raised noise levels at Deer and Nut Islands due to con-
struction would be temporary in nature and would not pose a signif-
icant noise impact. Transportation noise may be perceived as a
nuisance during construction at the two island facilities. How-
ever, this noise would also be temporary. Squantum truck traffic
would produce a long term addition to noise levels. Nonetheless,
the impact on the surrounding area would be minimal due to the easy
access to major roads and the relative isolation of the site as it
now exists.
E. Biota
The Recommended Plan will impact upon existing biotic cornrnun-
ities in several ways. First, upgrading the existing primary dis-
charges into Boston Harbor and eliminating the sludge discharges
will significantly improve water quality conditions and thereby
positively affect estuarine biota. The elimination of a Oiiincy
Bay effluent discharge and the sludge discharges will positively
affect the bay by an immediate improvement in water quality. The
localized water quality improvements which are realized may even-
tually open areas which are presently closed to shellfish harvest.
In general, water quality improvements should improve the
diversity of species found within the harbor. Similarly, aquatic
biota should be benefited to some degree by the relief of inland
interceptors, which would minimize polluting overflows within
the river systems.
Another impact of the Recommended Plan is the displacement
(and loss) of biota due to the construction of sewerage facilities.
The entirety of Deer Island will be used for the development
of treatment plant facilities. In addition to the areas now
occupied by the prison and the treatment plant, Deer Island con-
tains a grassy drumlin and the highly disturbed Fort Dawes area at
the southern tip of the island. Some sections of the Fort Dawes
area are bare and rocky. A low, marshy area exists adjacent to the
rocky area.
The land adjacent to the existing treatment plant contains
large grassy expanses which roll over the area with small forbs
appearing occasionally. Young stands of trees exist, but they are
not important ecologically. Development on Deer Island will not
destroy any valuable biota.
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Approximately 70 acres of land at Squantum Point will be
affected by the proposed project. The vegetation on the site
is composed of a mixture of grasses with a variety of other an-
nuals, shrubs and trees being found scattered throughout. Meadow
areas, both wet and dry, are present. The wet areas are dominated
by expanses of grass. Large patches of bayberry shrubs are
also found in this area.
A small salt marsh exists around the perimeter of the Squantuin
site (water boundaries). While the complete loss of this marsh
would probably be insignificant surficially, too many acres of
marshland have already been lost. By careful planning during
the construction and operation phases of the project, this marsh
can be protected from loss.
Overall, development of the Squantum site will have a minimal
effect upon biotic communities. Provided that an effective barrier
is used to contain leachate from the ash landfill, adjacent aquatic
biota will be unaffected.
Approximately 10 acres of land on Long Island will be needed
as a staging area during the construction phase only. While areas
south of the State mental hospital are available, they are not
suitable due to the steep slopes which parallel the water/land
interface. The area north of the hospital is topographically
more suitable. Biotic impacts will not be significant and will be
short—term (the area will be restored following staging operations)
However, land ownership problems may be restrictive because the land
is under the jurisdiction of the hospital. If access to a site
north of the hospital cannot be gained, then staging operations
will have to be restricted to the other construction areas (Deer
Island and Nut Island).
Another component of the project which will cause significant
biotic impacts is the dredging of the harbor associated with the
construction of the harbor crossing and outfall pipelines. In terms
of displacing the benthic biotic community, approximately 80 acres
of harbor bottom (hence benthic organisms) lie in the direct path
of the pipelines and would be lost along with the dredge spoils.
An even greater area of harbor bottom would be affected by edi-
mentation. Many forms will be smothered while other forms will
adjust to the level of the sediment. While the short—term effects
would be significant, benthic recovery would occur over severaF
seasons. The placement of clean backfill over the pipes may result
in an ultimate improvement over existing conditions.
Other biotic impacts would result from the construction of
relief sewers and a landfill for digested sludge. While the loca-
tion and magnitude of these effects cannot be accurately deter-
mined at this point, they are expected to represent significant
displacements. In the case of relief sewers, construction rights—
of-way will be restored following construction, but significant
losses of mature vegetation would occur.
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F. Socio-Economjc
Implementation of the Recommended Plan can be expected to have
significant socio-economic impacts, both positive and negative. The
positive impacts will be primarily associated with construction
employment and increased commerical activity in the vicinity of the
staging areas.
Construction of the recommended project will require approxi-
mately 4,400 man—years of construction labor. At an average wage
rate of $25,000 per man year, this amounts to approximately $110
million in wages that would be dispersed over a two to four year
period. Substantial portions of this money would be spent locally,
thereby increasing employment in other sectors of the economy.
In addition, sustained employment of 385 persons for operation
and maintenance of the facilities would account for about $5,000,000
in regional income per year.
Other positive impacts of the proposed project result from the
availability of Nut Island for recreational purposes. This, plus
the elimination of a Quincy Bay discharge will greatly increase the
attractiveness of the Quincy Bay area for revenue-generating recrea-
tional uses.
Negative impacts associated with the Recommended Plan include
the removal of land from municipal tax rolls and possible devalua-
tion of property value or usefulness of the areas adjacent to the
Squantum site. Specifically, implementation of the Recommended Plan
would result in the removal of 70 acres of land from the tax rolls
of the City of Quincy. The loss of future taxes could be even
greater than present losses, not only because the Plan precludes
future residential development on the site, but also because the
location of facilities at Squantum could diminish the attractive-
ness of adjacent land for residential development. This adjacent
land is now zoned for Planned Unit Development. It is not possible
to quantify these potential losses accurately at this time, but
they could be significant. The specific reasons for this impact
relate to the operation of the site as a landfill (visual impact);
the increased vehicle traffic which will be involved in transport-
ing chemicals, sludge, and compost; and the- possible nuisance con-
ditions (mainly odors) from the composting activity. The proposed
project, by the inclusion of a berm in its design, will minimize
visual impacts. However, the placement of higii L± e residential
structures on the adjacent parcel would negate the shielding effect
of a berm for upper story residents.
Another potential negative impact is the localized effect of
street closures on local businesses in the vicinity of sewer line
construction. For the areas surrounding Boston Harbor, this does
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not seem to be a problem since very little construction will occur
in or near streets. However, for inland interceptor relief projects,
the potential for impact is significantly greater.
G. Recreational and Scenic Areas
The Recommended Plan will have both positive and negative
effects on recreational sites and recreation in the study area. Neg-
ative effects can be attributed to the total loss of Deer Island
for recreational use. The Boston Harbor Islands Comprehensive Plan
(MAPC, 1972) proposed recreational uses for those portions of the
Island not used by the EMMA Study’s recommended expansion. Spec-
ifically, the drumlin was suggested as a vantage point from which
the harbor can be viewed. The Fort Dawes area was recommended for
use as a passive recreational area. However, the presence of a
large treatment facility at the northern end of the Island is con-
sidered to diminish somewhat the value of an immediately adjacent
recreational area.
Positive recreational impacts will result from the demolition
of most of the Nut Island treatment facilities and the availability
of this area for recreational use. Also, in the future, the Squantum
site will be available for reversion to recreational use when the
design capacity of the ash landfill has been reached (about 20 years).
In a general sense, the recreational use of the harbor and the
inland rivers will be enhanced by the reduction in pollutant loads,
elimination of sludge discharges and the reduction in wastewater
overflows and bypasses.
On balance, the construction of the Recommended Plan would
appear to positively affect the status of recreational sites and
recreation in the study area. Although the future construction of
relief sewers may cause specific local adverse effects, these can
be mitigated through careful facilities planning.
H. Sites of Special Significance
Included under sites of special significance are designated
historic preservation areas, pre-historic aboriginal sites and
significant natural areas.
The construction of harbor—based facilities (treatment facili-
ties, bay crossings, outfalls) will not affect any documented or
recorded historic sites. Similarly, no known aboriginal sites are
recorded on either Deer Island or Squantum. However, a detailed
field survey of these areas, especially Deer Island, should be con-
ducted during facilities planning to determine if any unrecorded
aboriginal sites are present. While this is unlikely due to the ex-
tremely disturbed nature of both areas, the discovery of such a
site would require removal of artifacts or recording of data.
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With respect to significant natural areas, no sites on the
National E egistry of Natural Landmarks will be impacted by the pro-
posed action. One site (Deer Island) or the Massachusetts Land-
scape and Natural Areas Survey will be impacted as discussed pre-
viously.
I. Significant Environmentally Sensitive Areas
Significant and/or sensitive components of the environment and
the impacts of the Recommended Plan on these features are summarized
below:
Geology - Over one hundred drumlins have been identified as
distinctive geologic features in the Boston area. The Recommended
Plan impacts the two drumlins present on Deer Island. The Boston
Harbor Islands Plan will serve to protect the remaining drumlins
which form most of the Harbor’s Islands.
Surface Waters — Water quality will be positively impacted
by the Recommended Plan. In addition to water quality improvements,
no water areas will be lost by filling any harbor areas.
Recharge Areas - The proposed project will not involve the per-
manent construction of any facilities on recharge areas.
Wetlands - Construction at Deer Island and Squantum will not
result in the displacement of any salt marsh areas. Wetlands are
found on the perimeter of both sites but should be minimally affected
by facilities construction. A small wetland area exists within the
Squantum site but is not flushed by the tide. Hence, it makes no
contribution to the bay ecosystem. During relief sewer construction,
some inland freshwater wetlands may be temporarily disturbed. How-
ever, proper facilities planning should minimize these disturbances
and mitigate any long term effects.
Steeply S] çped Areas — It is not anticipated that any facilities
(except for minor segments of relief sewers) will be constructed
on steeply sloped areas.
Forests and Woodlands — Harbor facilities will not affect
forests and woodlands. Relief sewers will traverse wooded areas
to a significant degree and will impose significant effects.
Air Quality - Since Boston is designated as a non-attainment
area, every effort has been made to reduce air emissions from the
Recommended Plan. However, incineration still represents a major
method of sludge disposal 7 and it is possible that emission off-
sets will be required.
Habitat of Rare or Endangered Species - The Recommended Plan
will not result in the loss of any significant habitat for rare or
endangered species in the harbor area. Caution during facilities
planning can also eliminate this condition during relief sewer
construction.
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Public Use/Cultural Resource Sites - Cultural resource sites
will not be affected by the construcEi5n of harbor facilities.
Public use sites will be both negatively affected (Deer Island)
and positively affected (Nut Island).
X. MEASURES TO MITIGATE ADVERSE IMPACTS
The Recommended Plan is expected to result in a number of ad-
verse environmental impacts. Feasible recommendations which can
significantly minimize these impacts are listed below:
1. The possible adverse effects of wastewater chlorination
were presented earlier. Several alternatives exist which can serve
to both disinfect the effluent from the treatment plant and mini-
mize the adverse effects of chlorine. The simplest option is to
eliminate the chlorination step during that period of the year when
the harbor is little used for water—contact recreation, Labor Day
to Memorial Day. During the summer season, effluent could be both
chlorinated and then dechlorinated (using sulfur dioxide). Be-
cause seawater has been demonstrated to be a hostile environment
for sewage bacteria, the practice of chlorination only when human
contact with the diluted effluent may occur quickly has received
ever-increasing support. The additional cost of dechlorination
would be more than offset by the savings realized from the elimi-
nation of chlorination for nine months each year.
Other options include year round chlorination and dechlorina-
tion; the use of an alternative disinfectant during summer months
(such as permanganate or ozone); and the use of a low-level chlorine
dose (which could be quickly diffused to a sub-toxic level).
These alternatives should be examined with respect to cost
and feasibility during facilities planning. Environmental con-
siderations would seem to favor the first approach (chlorination
and dechlorination during the summer season only). In addition to
the water quality and biotic benefits, a savings in resources
(chemicals) and transport requirements will be realized. This
should be coupled with a coliform monitoring program to test the
efficacy of this approach and to safeguard the public health.
2. The Recommended Plan will continue the present practice
of exporting water from inland river basins to the harbor. An
analysis of water losses indicated that losses due to inflow and
infiltration (I/I) greatly exceed net water export quantities.
Hence, efforts which will reduce I/I will tend to mitigate the
effect of water export.
Water conservation programs (both voluntary and involuntary)
should be promoted.. The MDC, acting as both sewer and water author-
ity, is in an ideal position to advance this concept. The MDC
should actively campaign toward the education of the public con-
cerning the need for water conservation and what steps can be
economically and easily taken to save water.
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3. This project attempts to mitigate air quality impacts by
maximizing the disposal of sludge by marketing or giving away a
composted product. Therefore, the success of the composting opera-
tion is important in ultimately keeping air emissions as low as
possible. In order to enhance the feasibility of this program,
the MDC should actively publicize the availability and virtues of
composted sludge. This includes providing leaflets instructing
the public in its proper use and contacting other institutions,
agencies, and commercial organizations concerning the use of corn—
posted sludge. Since the use of coinposted sludge is a relatively
new idea c,n this scale, the program must be actively promoted. In
order to enhance the quality (hence, the usefulness and market
potential) of the composted sludge, the MDC should investigate
additional methods of reducing its metal content.
In addition to providing composted sludge for public pick-up
at Squantum, the MDC should truck compost to dispersed distribution
sheds located through the study area. These sheds could be located
on MDC parkiand or other public land. This will greatly reduce
traffic into Squantum; reduce total travel and air emissions; and
increase the market for compost.
4. In order to mitigate the effects of dredging in the harbor,
the use of a specially designed dredging barge shoi ld be investigated.
The barge wculd be equipped with legs which are lowered to stabilize
the barge once it is properly positioned. Steel sheeting is then
driven around the front and sides of the barge and the trench sec-
tion within the sheeting is excavated. This method will reduce the
volume of material excavated, decreasing the number of barge trips
necessary for disposal and the cost of the harbor crossing. The
volume of backfill required also will be reduced, as well as the
cosL of this operation. In addition, localized sedimentation and
siltation impacts will be limited to the area within the sheeting.
Under actual operating conditions elsewhere, the cost of this method
has been shown to be competitive with other, more conventional
dredging techniques.
5. To further mitigate impacts on the adjacent PtJD zone at
Squantum, ccmposting operations should be conducted on that part
of the site farthest from the PUD zone. Also, the berm nearest the
PUD zone should be well screened with vegetation to shield the site
to a maximum extent possible. Ash placed in the landfill should be
wetted and covered as needed to prevent dust and wind erosion.
Optimum operating procedures can be developed using the successful
techniques used at other ash landfill sites already in operation.
Coir post piles should not be broken down for movement to curing areas
when the prevailing wind is in the direction of the PUD zone.
6. In order to minimize the effect of increased traffic through
Winthrop to Deer Island, the maximum use of water transportation to
move materials and machinery is recommended. The feasibility of
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bringing construction workers to the site via shuttle bus should
also be investigated. If workers can be brought in from outlying
parking areas, daily traffic could potentially be reduced from
2000 vehicle round trips to 50 vehicle round trips (at 40 workers
per bus).
7. To mitigate impacts upon the seasonal recreational use of
the harbor, construction activities should be scheduled to avoid
intensively used recreational areas during the peak-use season.
8. To minimize the loss of terrestrial biota during the con-
struction of relief sewers, every effort should be made to mini-
mize the right-of-way used, particularly in heavily vegetated areas.
9. To ensure that the sludge landfill does not contaminate
underlying groundwaters, a series of monitoring wells should be in-
stalled around the landfill site. A water quality sampling program
should be maintained to guard against the degradation of ground-
water.
10. Current construction contracting procedures used by the
MDC, and the size of the proposed construction project, preclude the
award of a single contract for the construction of the treatment
plant at Deer Island. There is a need for centralized control of
all construction activity in order to reduce the impacts of con-
struction on nearby communities, particularly through the use of
barges for delivery of mechanical equipment and construction
materials. It is recommended that a construction managment con-
sultant be engaged throughout the design and construction periods to
schedule and enforce timely completion of each phase of work.
Cooperation between contractors is necessary in order to make barging
an economical method of transporting equipment and materials.
XI. ADVERSE EFFECTS WHICH CANNOT BE AVOIDED
It is recognized that the Recommended Plan will result in some
adverse impacts on the environment which cannot be mitigated or
avoided. These are summarized below in qualitative terms.
While water quality conditions are expected to generally im-
prove, the proposed effluent discharge will still introduce organic
and inorganic pollutants to Boston Harbor. Specifically, the total
loading of cadmium, mercury and nickel into President Roads from
the effluent discharge will increase marginally over present condi-
tions. (This ignores the present sludge discharge). However, these
metals should be quickly diluted to acceptable levels.
Other unavoidable water quality effects include the introduc-
tion of silt, organics and metals to the harbor from the disturbed
bottom muds during dredging operations.
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The increased export of water from inland river basins to the
harbor can be viewed as an adverse effect. Strictly speaking, this
effect is avoidable through water conservation measures and through
the reduction of inflow and infiltration. However, it is not likely
that this effect will be completely mitigated by these measures.
Hence, net water export will probably represent an adverse effect.
This impact should be manageable and, if sincere efforts are made
by the MDC and the public, it should be minimal. In any event,
severe impacts on local water supplies and river flOws are not fore-
seen.
The Recommended Plan attempts to minimize air quality impacts
through the use of alternate sludge disposal methods, thereby rely-
ing on sludge incineration to the least degree feasible. However,
air emissions from sludge incineration will be significant and will
represent an unavoidable adverse effect. Similarly, air emissions
resulting from additional barge, truck and automobile traffic are
unavoidable.
Noise impacts during construction (especially along inter-
ceptor sewers) are unavoidable. However, during facilities opera-
tion, noise impacts should be minimal.
Unavoidable adverse impacts on the area’s biota will result
from the permanent displacement of existing biotic communities at
Deer Island, Squantum and the sludge landfill. Unavoidable short-
term impacts will result from dredging the harbor and the construc-
tion of relief sewers through vegetated areas. Additional short-
term effects may result from the use of a Long Island site for
staging operations.
With respect to socio-economic effects, the negative fiscal
impact of taking the Squantum site for a tax exempt use is unavoid-
able. Also, the recommended use of the Squantum site may hamper a
developer in marketing units in the adjacent PUD zone. At such
time when residents occupy the PUD zone, high-rise residents will
be affected by the visual impact of the ash landfill and compost
operation.
In terms of recreational and secenic areas, the loss of Deer
Island (particularly the drumlins) for recreational purposes
represents an unavoidable adverse impact.
XII. IRREVERSIBLE AND IRRETRIEVABLE
COMMITMENTS OF RESOURCES
The construction, operation and maintenance of the Recommended
Plan is expected to result in the irreversible and irretrievable
commitments of certain resources. The major resources include
land, energy, chemicals, dollars and labor. In addition to these
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items, other resources which are difficult to quantify will also be
committed. These include such things as cement, aggregate, back-
fill, etc. They are, however, reflected as costs.
Labor - Labor is considered a resource whose commitment to
this project is irreversible. That is, once labor (which could be
spent in other ways) is committed to this project, it is a resource
that has been expended in an irretrievable manner. This project
will require approximately 4,400 person-years for the construction
of the proposed facilities (this does not include inland relief
sewers). For operation and maintenance, a permanent staff of
about 384 persons will be needed.
Energy - The energy requirement of the proposed facilities
(luring the operational phase is approximately 224 million kilowatt
hours per year. In addition, about 930,000 gallons of fuel oil
will be needed annually for the proposed plan.
Land - Approximately 210 acres of land at Deer Island will be
permanently committed to wastewater treatment use. Seventy acres
at Squantum will be reversibly committed. That is, when the ash
landfill reaches its design capacity, it will be restored and can re-
vert to an alternate use, such as recreational development.
The construction of relief sewers will require permanent ease-
ments which can restrict the use of land through which the rights-of-
way pass.
Chemical Resources — For operational purposes, chemicals are
required, in bulk, for disinfection and treatment. These commit-
ments are quantified below. The estimate for chlorine is not adjusted
in accordance with a seasonal chlorination program.
Chlorine, tons/year 7,135
Lime, tons/year 14,600
Ferric Chloride, tons/year 3,500
Polymer, tons/year 113
Dollars - Dollars are included here in the sense that once
money is appropriated, it can be considered a resource with alter-
native uses. Dollars also represent a common basis with which other
resources can be quantified. In this sense, the cost of a project
represents the sum tot 1 of all resources committed to a project.
The total capital cost of the Recommended Plan is est3mated at $771
million, with annual operation and maintenance costs estimated
at $24.8 million.
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