Metro Wastewater Management / Summary Draft
Environmental
Impact
Statement
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SUMMARY DRAFT EIS
FOR METRO
WASTEWATER
MANAGEMENT STUDY
The U.S. Environmental Pro-
tection Agency (EPA) has given the
Municipality of Metropolitan Seattle
(Metro) a grant to plan Wastewater
Treatment improvements for a 620
square mile area of the Lake
Washington/Green River Basin
(see Figure 1).
The plan defines a preferred
long-term Wastewater Manage-
ment program for the area. Metro
will apply to EPA for additional
grants to construct the facilities.
Federal Law requires preparation
of an Environmental Impact State-
ment (EIS) to inform the public
about the potential impacts of the
program.
This document is a summary of
the full 250 page EIS prepared for
the Draft Wastewater Management
Plan.
WHY THE NEED FOR A
MANAGEMENT PLAN?
D The Renton Wastewater
Treatment Plant has reached its
capacity and cannot accommodate
additional flow. Based on popula-
tion forecasts by the Puget Sound
Council of Governments (PSCOG),
and service area enlargement,
Metro will have to treat 101 million
gallons per day (MGD) of waste-
water by the year 2000, compared
to present flows of 40 MGD.
D The Renton plant's current
level of treatment must be improved
to prevent increased future flows
from degrading water quality in the
Green/Duwamish River, or else the
plant's effluent must be discharged
FIGURE"!. SERVICE AREAS
SEWER SERVICE AREA
SEWER SERVICE AREA (NON-METRO)
NON-SEWER AREA (LONG-TERM LAND USE CERTAIN)
NON-SEWER AREA (LONG-TERM LAND USE UNCERTAIN)
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directly to Puget Sound.
D Currently, many of the homes
in the study area use septic sys-
tems, which have the potential to
adversely affect water quality. Much
new development will continue to
use septic systems.
WHAT ARE THE ALTERNATIVES?
Metro initially developed 15
long-term alternatives and selected
four final alternatives for further
consideration.
D ALTERNATIVE A-1 —Cen-
tralized processing at Renton plant
with nitrification (ammonia removal)
and continued discharge to the
Green/Duwamish River.
D ALTERNATIVE A-3—Cen-
tralized processing at the Renton
plant with discharge of secondary
effluent to Puget Sound off the
Point Pulley area.
D ALTERNATIVE A-5—Cen-
tralized processing at the Renton
plant with discharge of secondary
effluent to Puget Sound off Alki
Point.
D ALTERNATIVE B-1—Cen-
tralized processing at the Renton
plant with nitrification and con-
struction of a new secondary
treatment plant in the Ken more
area which would discharge to
Puget Sound at Richmond Beach.
Following further evaluation,
Metro staff selected Alternative A-3
or A-5 as the preferred long-term
wastewater management program
(these alternatives differ only in the
Puget Sound outfall location).
Components of the preferred
program (See Figure 2) include:
collection system changes (con-
struction of the Redmond
connection and North Creek/
Hollywood connection to convey
wastewater from the north part of
the study area, which is now treated
at West Point, to the Renton plant);
expansion of the Renton treatment
plant to 99 MOD capacity; con-
struction of a tunnel and outfall to
convey effluent to Puget Sound;
and installation of solids processing
facilities at the Renton plant
(Renton sludge is currently
discharged via a force main to
Metro's West Point plant).
Construction of the preferred
program projects would be phased;
Phase 1 construction would occur
between 1981 and 1985, and Phase
2 construction would occur
between 1986 and 1993.
FIGURE 2. ALTERNATIVES A-3 & A-5 (PREFERRED PROGRAM)
Redmond
Connection
North Creek/
Hollywood
Connection
Sammamish Lake Lake Sawyer
Lake Youngs
Lake Tapps
Green/Duamish River
Elliott Bay
WEST POINT SERVICE AREA
RENTON 2000 SERVICE AREA
TREATMENT PLANT D
EFFLUENT OUTFALL
SERVICE AREA TRANSFER FACILITIES
PUMP STATION
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WHAT ARE THE IMPACTS
OF LONG-TERM
WASTEWATER
ALTERNATIVES?
The Draft EIS fully evaluates all
the possible impacts of the long-
term Wastewater Management
Alternatives including:
L J Cost
[J Construction impacts
U Water quality and biological
impacts
11 Growth impacts
11 Resource use impacts
i .1 Recreation impacts
Cost vs. water quality benefits
will be a main basis for selecting a
long-term alternative.
Table 1 lists the costs of each of
the alternatives.
Alternative A-1 (nitrification) has
the least capital (construction) cost.
Increases in the Metro monthly
charge assuming 75% funding from
EPA, would be $2.50 per month.
These increases would be used to
pay for the local share of the con-
struction costs and ongoing
operation and maintenance costs. If
EPA funding were less than 75%
local costs would be expected to be
greater.
The preferred program with Point
Pulley discharge (A-3) has the next
lowest capital costs. More of the
costs of this alternative are grant
eligible, however, so that the
increase in monthly charge would
be only $2.10 per month.
Both the Alki Point discharge
option (A-5), and the Kenmore
treatment plant option (B-1), would
be considerably more expensive
and for both the increase in monthly
charge would be $2.60.
TABLE 1. COMPARISONS OF COSTS OF ALTERNATIVES
Point Putley
Alki Point
iPuget
[Sound
PREFERRED
PROGRAM
Renton
Plant
(Green Duarrasti I
(Rivers
ALTERNATIVE
A-1
Kenmore
Plant
[Green Duamish J
(Rivers
ALTERNATIVE
B-1
0
NO
PROJECT
Capital cost
($ million)
310 (A-3)
410 (A-5)
262
323
Annual operation
and maintenance
costs ($ million)
8.9 (A-3)
9.3 (A-5)
12.6
11.4
Slight
increase
Present worth
cost ($ million)
279 (A-3)
357(A-5)
267
329
Increase in
Metro monthly charge,
assuming 75% grant funding
2.10 (A-3)
2.60 (A-5)
2.50
2,60
Slight
increase
Assuming 50%
grant funding
3.20 (A-3)
4.00 (A-5)
3.50
3.70
Slight
increase
Assuming 0%
grant funding
5.50 (A-3)
7.00 (A-5)
5.40
6.10
Slight
Increase
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Table 2 summarizes the water
quality impacts of each of the
alternatives.
If "No Project" were implemented
the long-term impacts on Green/
Duwamish River water quality
would be adverse. Specifically,
quality of the river water could
become toxic to existing fisheries.
The runs of steelhead, cutthroat
trout, and salmon in the Green/
Duwamish River are among the
largest in the Puget Sound and are
valued at about $5 million annually.
The river below the Renton plant is
a migration route for juvenile
salmon and trout en route to the
ocean and for adults returning to
spawn higher in the watershed.
The preferred program would
avoid Green/Duwamish River
water quality and fisheries impacts
by diverting Renton effluent to
Puget Sound. Based on previous
studies no major impacts on the
Sound are predicted by the pro-
posed diversion.
If Alternatives A-1 or B-1 were
selected, some but not all of these
problems would be avoided.
Implementation of the preferred
program appears the best way to
protect the Green/Duwamish River
water quality.
CONSTRUCTION IMPACTS
Each of the alternatives would
have short-term construction and
site-related impacts, most of which
would be minor. Construction of the
tunnel and outfall from either the
Renton plant (under the preferred
program) or the Kenmore plant
(Alternative B-1) could have more
serious short-term impacts on
recreation, traffic, or spoils
disposal. Mitigation measures are
available to reduce these impacts.
Alternative A-1 would avoid the
TABLE 2. COMPARISON OF MAJOR WATER QUALITY
IMPACTS OF ALTERNATIVES
TYPE OF IMPACT
PREFERRED
PROGRAM
Point Pulley
Alki Point
Puget
Sound
ALTERNATIVE A-1
Renton
Plant
ALTERNATIVE 8-1
Kenmore
Plant
NO PROJECT
Long-term impacts on
Green/Duwamish River
Future water quality problems and
risks to salmon migration are
avoided by diversion of effluent
to Puget Sound.
Ammonia and dissolved oxygen
problems would be solved
through nitrification. Temperature
standards, DOE effluent dilution
guidelines, and permit limits for
certain heavy metals would be
exceeded. Fish migration could be
adversely affected.
Major ammonia and dissolved
oxygen problems would occur, in
addition to those impacts shown
for A-1 and B-1. River water
quality could become toxic
to salmon.
Long-term impacts on Puget
Sound
No major impacts expected.
Localized increases in turbidity,
ammonia, and heavy metals could
occur near outfall. Alki Point (A-5)
discharge preferred to Point
Pulley (A-3) discharge due to
shorter effluent residence time in
Puget Sound.
No major impacts expected from
Green/Duwamish River
discharge, which eventually
enters Puget Sound.
No major impacts expected.
Localized increases in turbidity,
ammonia, and heavy metals could
occur near outfall.
Impacts of Green/Duwamish
River discharge when it would
enter Puget Sound are unknown.
impacts of constructing a tunnel
and outfall to Puget Sound.
INTERIM WATER QUALITY
IMPACTS
Any of the alternatives (except
the No Project Alternative) would
take a minimum of 5 years to
design and build. During this time,
short-term deterioration in Green/
Duwamish River water quality can
be expected as sewage flows
continue to increase beyond the
Renton treatment plant's treatment
capacity.
Temperature, dissolved oxygen,
and ammonia water quality
standards would be violated, and
DOE effluent dilution guidelines
would continue to be exceeded.
Deteriorating water quality would
increase the risks of impaired
salmon migration or fish kills.
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SECONDARY IMPACTS
The processes of growth and
urbanization have major effects on
the environment. The Lake
Washington/Green River Basin
study area has grown rapidly over
the last decade, and this rapid
growth is projected to continue in
the future.
EPA policies require the agency
to consider the secondary (indirect)
environmental impacts of waste-
water projects that receive federal
construction grants. These
secondary impacts are caused by
the community growth which
wastewater facilities are con-
structed to accommodate. The
secondary impacts of a project may
often be more significant than the
The secondary impacts of
a project may often be
more significant than the
project's direct impacts.
farmlands; and 4) development of
wetlands and floodplains. EPA
policies and programs require that
these impacts be mitigated where
possible.
MITIGATION MEASURES
As revealed by their previous
discussion, a number of adverse
impacts could accompany imple-
mentation of Metro's Wastewater
Management Plan. The most
important available mitigation
measure for these adverse impacts
are listed below. Not all these
measures are the responsibility of
EPA or Metro. Although EPA
approval of Metro's Plan is not
contingent on actions which are the
responsibility of other agencies, it is
desirable that all potential
mitigation measures be displayed
for public review and comment.
CONSTRUCTION AND
SITE-RELATED IMPACTS OF
TUNNELS AND OUTFALLS
RECREATIONAL USE IMPACTS
D Schedule construction during
off-peak recreational periods.
TRAFFIC IMPACTS
[J Reroute traffic around
construction sites and provide
flagmen.
SPOILS DISPOSAL IMPACTS
D Use spoils for fill or dispose of
spoils in an acceptable location.
project's direct impacts.
Because Metro has relied on
local land use policies in desig-
nating the sewer service area, and
on PSCOG population projections
to project wastewater flows, the
proposed wastewater system
improvements will not "cause" the
growth projected by other agencies,
but rather will assist in its accom-
modation. Although neither Metro
nor EPA is institutionally
"responsible" for causing growth
and its accompanying secondary
impacts within the study area, the
philosophy that.EISs are full
disclosure documents dictates that
such secondary impacts be
examined in these documents.
Secondary impacts analyzed in
the EIS include air quality, surface
water and biology, groundwater,
land use, public service systems,
and public finance. The results of
the secondary impact analysis are
summarized in Table 3. Of partic-
ular concern to EPA are: 1) water
quality deterioration and losses of
migratory salmon and trout. This
could result from urbanization-
induced nonpoint source pollution;
2) risks to groundwater or surface
water from inadequately sited,
operated, or maintained on-site
systems; 3) conversion of prime
TABLE 3. SUMMARY OF SECONDARY IMPACTS
IMPACT AREA IMPACT
Air quality Population projections used for wastewater management planning are
consistent with those used for Puget Sound Air Quality Management
Plan (AQMP). Therefore, increased emissions from study area growth
have been accounted for in the AQMP.
Surface water Water quality deterioration and anadromous fish losses are occuring
and biology now because of urbanization, and could continue in the future.
High-growth subdrainage basins will be particularly affected.
Groundwater Risks to groundwater (and surface water) from inadequately sited,
operated or maintained on-site systems in nonsewer area will occur.
Land Use Between 3,950 and 5,213 acres of prime farmland could be converted
D Prime to nonfarm uses over the next 20 years in Sammamish Valley, Lower
farmland Green River Valley, and Upper Green River Valley agricultural districts.
conversion
D Sensitive Study area growth could occur on soil-related sensitive areas,
areas wetlands, and floodplains. High-growth subdrainage basins which
contain relatively large acreages of these sensitive areas would be
particularly affected.
Public Service Study area growth will increase demands on public services such as
Systems wastewater management, water supply, drainage, solid waste
management, recreation, social services, transportation, and electricity
and gas.
Public finance Study area growth will increase both public costs and revenues, and
I could create fiscal problems for some local government.
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WATER QUALITY IMPACTS
SHORT-TERM IMPACTS ON
GREEN/DUWAMISH RIVER
D Increase treatment by
1) Fast track implementation of
plant expansion*
2) Interim nitrification with
existing facilities
3) Constructing special
nitrification facilities
D Divert flow by
1) Diversion of additional 3 MGD
to West Point via sludge mains*
2) Diversion of 10 MGD raw
sewage to West Point via
Riverton-Renton pump station,
and/or
3) Diversion of effluent for land
disposal on 2750 acres.
D Reduce dilution of influent
waste flow to increase effec-
tiveness of diversion by
1) Reduced summer flushing*
2) Local agency infiltration
control, and/or
3) Water conservation
D Reduce in-river impact by
1) Interim river flow
augmentation, and/or
2) Fish diversion or hatchery
construction
D Reduce influent pollutant
load by
1) Pre-nitrification in the
Kent/Auburn lagoons
2) Sewer Moritorium
LONG-TERM IMPACTS ON
PUGET SOUND (ASSUMING
PREFERRED PROGRAM IS
IMPLEMENTED)
D For heavy metals and other
toxicant risks, complete Metro
toxicant study (currently underway)
and implement recommendations.
D Complete oceanographic and
biological studies proposed by
Metro for alternative outfall location.
SECONDARY IMPACTS
AIR QUALITY
D Continue to implement
regional Air Quality Maintenance
Plan
SURFACE WATER QUALITY
AND FISHERIES IMPACTS DUE
TO URBANIZATION
D Continue to implement Metro
208 areawide water quality
planning
D Continue to implement local
nonpoint source control programs
GROUNDWATER AND
SURFACE WATER IMPACTS
FROM ON-SITE SYSTEMS
D Establish comprehensive
on-site system management
program
D Provide adequate staffing,
funding, and enforcement
D Encourage experimentation
with alternative technologies
D Establish public education
programs
D Determine ground water
carrying capacity
D Establish institutional
agreements for on-site system
management
D Designate additional King
County prime farmlands for
protection under the Sewerage
General Plan
D Conduct detailed prime
farmland assessments in the future
state-required EISs for interceptor
sewers connecting to the Renton
plant
DEVELOPMENT ON WETLANDS
AND FLOODPLAINS
D Continue to implement King
County sensitive areas policies
D Continue to implement local
floodplain management programs
and federal flood insurance
programs
D Continue to implement King
County's Sewerage General Plan
and Metro Resolution 3380 policies,
which prohibit sewering designated
wetlands and floodplains
D Conduct detailed wetlands and
floodplains assessments in future
state-required EISs for interceptor
sewers connecting to the Renton
plant
LOSS OF PRIME FARMLANDS
D Continue to implement King
County Purchase of Development
Rights Program
D Continue to implement King
County's Sewerage General Plan
and Metro Resolution 3380 policies,
which prohibit sewering of desig-
nated farmlands
PUBLIC SERVICES AND
FINANCE
D Continue to implement existing
local plans and policies
ADDITIONAL
ALTERNATIVES
AVAILABLE TO EPA
•Proposed for implementation by
Metro
EPA may develop additional
structural or administrative
alternatives as part of the EIS. In
the case of this Metro plan, EPA has
determined that Metro has already
examined a full range of long range
structural alternatives. EPA
adminis-
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