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ORDINANCE NO
AN ORDINANCE of the City of Kent,
Washington, adopting the CITY OF KENT
201 WASTE WATER FACILITY PLAN, and
directing the filing of three copies
thereof with the Kent Citv Clerk.
THE CITY COUNCIL OF THE CITY OF KENT, WASHINGTON,
DO HEREBY ORDAIN AS FOLLOWS:
Section 1. There is hereby adopted by reference
as if fully set forth herein that certain.plan known as the "CITY
OF KENT 201 WASTE WATER FACILITIES PLAN."
Section 2. Three copies of the plan shall be filed'
with the Kent City Clerk and shall be available for public inspec-
tion.
Section 3. This Ordinance shall take effect five
(5) days after its passage, approval and publication as provided
by 1 aw . -�
:.�
ISABEL HOGAN, MAOOR
ATTEST:
MARIE JENG23- , CITY CLERK
PROVED AS TO FORM:
1 0. 1 -.1
DONALD E. MIRK, CITY ATTORNEY
PASSED the of day of 1.TtXVt-RLbez, -1-9,91$":
APPROVED the day of -
PUBLISHED the day of 9eC�
I hereby certify that this is a true copy of
Ordinance No. " /,:;8, , passed by the City Council of the
City of Kent, Washington, and approved by the Mayor of the City
of Kent as hereon indicated.
(SEAL)
MARI NSEN CITY CLERK
CITY`
KENT
Zoe Wastewater
Facilities Plan
•4 0 ,•OOp
lot�tY=; • rpt �r
prepared by
URS Company
FACILITIES PLAN
FOR
THE CITY OF KENT
WASHINGTON
BY
URS COMPANY
SEATTLE, WASHINGTON
MARCH 21, 1977
TABLE OF CONTENTS
�- FOR THE CITY OF KENT FACILITIES PLAN
Page
1
1.
INTRODUCTION
Authorization
1
1
Purpose
5
Scope
6
�.,
Planning Area
6
Need for Planning
8
History of Sewerage Service
in the Study Area
9
References
2.
SUMMARY AND RECOMMENDATIONS
10
3.
PLANNING CONSIDERATIONS
13
Planning Participation and
Coordination
13
Regulatory Constraints and
Permit Requirements
15
Water Quality Objectives and Effluent Limitations
17
Federal Level
18
19
State Level
26
Local/Regional Level
28
u
References
4.
PLANNING AREA DESCRIPTION
30
General Description
30
r'
Natural Conditions
30
Soils and Geology
33
36
Climate
38
Air Quality
38
Noise
40
Water Quality
42
—
Vegetation and Animal
Life
44
Endangered Species
44
Rare Species
Pa e
Social Conditions
45
Population
45
Housing -
47
Land Use
47
Services and Facilities
51
Police
51
Fire
51
Water
52
Sewage
52 `
Highways
53
Schools
53
Parks and Recreation
53
Archaeological or Historical Significance
54
Summary of Environmental Concerns
54
References
55
5. EXISTING WASTEWATER SYSTEM CONDITION, FLOWS AND
56
POLLUTANT LOADS
Introduction
56
General System Conditions and Performance
56
Existing Condition
57
Collection System
57
Unsewered Areas
58
Sewage Treatment Facility
59
Summary
60
6. INFILTRATION/INFLOW ANALYSIS
61
Previous Studies
61
Summary of Completed I/I Analysis
62
Garrison Creek Interceptor
62 --
100th Avenue Interceptor
62
Linda Heights Pump Station
63
Metro Auburn Interceptor
63
Relationship to Total System
65
Conclusion
66 --
Page
7. FORECASTS OF FLOWS AND WASTE LOADS
69
8. DEVELOPMENT AND EVALUATION OF ALTENATIVE
73
PLAN ELEMENTS
Introduction
73
Regionalization
73
Waste Management Techniques
74
Flow Reduction
74
System Extension and Alternatives
74
Area A
76
Area B
76
Area C
76
Areas B-1 and C-1
77
.. Area D
77
Area E
77
Area F
78
Area G
78
Area H
79
Area I
79
Area J (Lake Fenwick Area)
80
Star Lake Area
80
Area K
82
Area L
82
.. Area M
82
Summary
83
9. PUBLIC PARTICIPATION
84
Page
10. ENVIRONMENTAL ASSESSMENT
86
Introduction
86
Description of the Proposed Action
86
Alternatives to the Proposed Action
86
Environmental Impact of the Proposed Action
88
Physical Impacts
90
Biological Impacts
90
Social Impacts
91
Economic Impacts
92
Construction Impacts
93
Adverse Impacts and Mitigating Measures
93
Unavoidable Adverse Impacts
94
Local Short -Term Uses Versus Long -Term
95
Productivity
Irreversible and Irretrievable Commitment
96
of Resources
Public Involvement
96
References
97
LIST OF TABLES
Number
Title
Page
1
Regulatory Reasons for Facilities Plans
2
2
State of Washington Water Quality Standards
20
For Class AA "Extraordinary" Waters
3
State of Washington Water Quality Standards
22
,.
For Class A "Excellent" Waters
4
State of Washington Water Quality Standards
24
For Class B "Good" Waters
5
Ambient Air Quality Standards
39
,_. 6
Rare, Threatened or Endangered Animals Whose
44
Range Includes the Green River Sewerage Area
7
Anadromous Fish Natural Production
45
8
Estimated Population of the Planning Area
46
-- 9
Population Characteristics
46
10
Land Use Areas (1965 and 1973)
48
11
Projected Wastewater Flows
72
12
Cost Estimates for Star Lake Area Service
81
-r
Alternatives
13
Potential Areas of Environmental Impact
87
LIST OF FIGURES
Number Title
1 Vicinity Map
2 Planning Area Boundaries
3 Planning Area Topography
4 Soil/Slope Septic Tank Suitability
5 King County Agricultural Lands
6 Proposed Future Service Areas
Page
31
32
34
37
49
86
CHAPTER 1
INTRODUCTION
This draft facilities plan presents the evaluation of alternative
methods of meeting the wastewater disposal needs of the City of Kent,
Washington. Preparation of a facilities plan is required if federal
w funding will be involved in the construction of wastewater intercep-
tion or treatment facilities.
This facilities plan will be concerned primarily with the collec-
tion aspect of wastewater since all wastewater generated within the
City of Kent is treated by the Municipality of Metropolitan Seattle
(METRO). The wastewater is transported via Metro's Valley Interceptor
to the Renton Wastewater Treatment Plant where it is treated and
discharged into the Duwamish River which flows into Puget Sound.
AUTHORIZATION
The development of this facilities plan is pursuant to a
contractual agreement dated February 2, 1976 and amended November
29, 1976 between the City of Kent and URS Company. The agreement
..� between the City of Kent and URS Company was finalized after the
City received grant approval from the Environmental Protection
Agency.
PURPOSE
This facilities plan presents a number of alternatives, together
with the most appropriate plan for accomodating the wastewater needs
of the City of Kent. A major purpose of this plan is to guide the
1
City of Kent in its decision making regarding providing wastewater
collection and interception facilities in the future. The City of
Kent like many other communities in south King County is a growing
community. This growth, however, cannot be accommodated unless
wastewater collection and treatment are provided for. Since Metro
is the agency responsible for treating wastewater generated in the
City of Kent, this plan will aid Metro in its planning efforts to
meet the treatment needs of Kent as well as the other participating
jurisdictions.
Aside from the reasons mentioned, there are regulatory reasons
for developing this plan. The following table summarizes those
reasons.
TABLE 1
REGULATORY REASONS FOR FACILITIES PLANS
Agency/Document
Federal Water Pollution
Control Act Amendments
of 1972 (Public Law
92-500); Section 201
Summary of Requirements
1. Insure that the facility integrates
as much as possible facilities for
treatment, disposal or utilization
of all wastes;
2. Insure that alternative waste manage-
ment techniques have been studies
and evaluated;
3. Insure that best practical treatment
will be provided over project life;
2
TABLE 1 (Continued)
Agency/Document Summary of Requirements
4. Take into account and allow for
application of later technology to
- eliminate discharge of pollutants;
5. Insure that adequate infiltration/
inflow analysis is performed.
National Environmental Overall - insure that environmental
Policy Act of 1969 quality objectives are adequately con -
(Public Law 91-190) sidered. Specific - "...to improve and
NEPA coordinate Federal plans, functions,
programs, and resources to the end that
the Nation may:
1. fulfill the responsibilities of each
generation as trustee of the environ-
ment for succeeding generations;
2. assure for all Americans safe, health-
ful, productive, and aesthetically and
culturally pleasing surroundings;
3. attain the widest range of beneficial
uses of the environment without
degradation, risk to health or safety,
or other undesirable and unintended
consequences;
3
TABLE 1 (Continued)
Agency/Document
Summary of Requirements
4.
preserve important historic, cultural,
and natural aspects of our national
heritage, and maintain, wherever
possible, an environment which
supports diversity and variety of
individual choice;
5.
achieve a balance between population
and resource use which will permit
high standards of living and a wide
sharing of life's amenities; and
6.
enhance the quality of renewable
resources and approach the maximum
attainable recycling of depletable
resources."
Environmental 1.
Insure that the environmental impact,
Protection Agency
both adverse and beneficial, of any
alternative is adequately examined
in accordance with the objectives of
NEPA Guidelines established for the
development of environmental impact
statements for facilities plans.
4
Agency/Document
Washington Water
Pollution Control
Planning Regulations
SCOPE
TABLE 1 (Continued)
Summary of Requirements
2. Impact on wetlands must be avoided,
rare species of fish and wildlife
protected.
1. Regulations outline minimum plan
requirements and plan adoption
procedures.
The scope of this study is as follows:
1. Identification of the wastewater collection and treatment
needs of the planning area. This includes an assessment
of existing practices and anticipated future wastewater
flows and characteristics. Water quality and public
health related requirements are evaluated and also those
concerning treatment needs and effluent limitations.
2. The development of alternative plans for meeting identified
needs.
3. An assessment of alternative plans based on cost effective-
ness, water quality effects, environmental and community
impacts and implementation requirements.
4. The identification of a recommended plan for implementation.
F1
PLANNING AREA
The planning area which includes the City of Kent is located in
south King County, Washington. To the north the area is bounded by
S. 180th Street which is th boundary with the City of Renton; to the
south the area is bounded by S. 277th Street which is the boundary _
with the City of Auburn; to the west the area is bounded by Inter-
state 5, and to the east by 124th Avenue S.E. Figure 1 shows the
location of the planning area with respect to the major population'
centers in Puget Sound, while Figure 2 shows the boundaries of the
planning area and the City of Kent. Both figures appear in Chapter 4.
The boundaries of the planning area have been determined by
physical as well as jurisdictional considerations. The City of Kent
including the commercial and industrial areas is situated in the.
lowlands of the Green River. Two large residential areas are
located northeast of the City and west-southwest on the slopes of
the hills forming the natural walls of the Green River Valley. The
planning area contains large tracts of undeveloped as well as
undevelopable land. The potential for all type of development will
continue in the future as it has in the past several years.
NEED FOR PLANNING
The need for developing this facilities plan stems from regu-
latory as well as planning consideration.
Pursuant to the former, Title II of the Federal Water Pollution
Control Act Amendments (PL 92-500) of 1972 authorizes the award of --
construction grants for wastewater interceptor and treatment works.
2
The award of these grants creates a contractual obligation of the
United States for payment of the federal share of the construction
costs of such projects.
Pursuant to the requirements of the above Act. the Environmental
Protection Agency has promulgated a three-step grant process for the
award of such federal assistance. Step I constitutes a "Facilities
Plan"; Step II constitutes the plans and specifications for whatever
project(s) are decided upon in Step I; Step III consists of the
actual construction of the project(s) or any segment(s) thereof.
Facilities planning (Step I), therefore constitutes an essen-
tial element of the construction of publicly owned wastewater
treatment works. Facilities planning consists of the development of
v- those necessary plans which are directly related to the construction
of treatment works, in compliance with Section 201 of the Act.
Facilities planning will determine what is the need for the sewage
facilities and by a systematic evaluation of feasible alternatives
will also determine the most cost-effective means of meeting those
needs.
Participation by the EPA to the extent of 75% of the cost of
construction of interceptor and treatment facilities, and by the State
of Washington to the extent of 15% in those same costs is not possible
without a facilities plan developed pursuant to the appropriate
federal and state regulations.
The rate of growth over the past several years has been fairly
stable in the City of Kent as well as the service area within the
boundaries of the planning area. Between 1960 and 1970 the City's
7
population increased from 9,017 to about 16,300 or an increase of
about 80% in ten years. Proper planning of wastewater facilities
under such conditions is needed in order to accommodate growth in an
orderly and manageable fashion. The 1977 population for the City
of Kent is estimated at 18,000.
HISTORY OF SEWERAGE SERVICE IN THE STUDY AREA
• The sewerage system of the City of Kent has been designed and
constructed in accordance with the growing needs of the City as
development occurred. As early as 1963 URS, (at that time known as
Hill & Ingman) completed an engineering report on sewage collection,
treatment, and disposal for the City of Kent. The report resulted
in recommendations which enabled the City to continue to meet it's
growing sewerage needs.
In July, 1967 the City turned over the treatment responsibility
to Metro and thereby became a part of the Metro system. In 1966 the
first utility local improvement district (ULID) was established.
Throughout the late sixties and early seventies the City as well as
Metro constructed a number of large interceptors including the 212th
Street Interceptor, Mill Creek Interceptor and the Garrison Creek `r
Interceptor.
The collection system of the City has been constructed largely
by developers in accordance with the specifications of the City.
It is expected that future extensions to the existing system in
areas which are presently unsewered will be constructed under the
same procedures.
E
REFERENCES
1. "Federal Water Pollution Control Act Amendments of 1972", Public
-- Law 92-500, passed over President's veto, October 18, 1972.
2. "National Environmental Policy Act of 196911, Public Law 91-190,
enacted by Congress, January 1, 1970.
3. "Manual for Preparation of Environmental Impact Statements for
Wastewater Treatment Works, Facilities Plans, and 208 Areawide
Waste Treatment Management Plans", EPA, July, 1974.
4. "Preparation of Environmental Impact Statement", EPA, Code of
Federal Regulations, Title 40, Chapter 1, Part 6, April 14, 1975
and Council on Environmental Quality, Chapter V, Part 1500,
August 1, 1973.
_. 5. "Environmental Protection Agency Administrator's Decision
Statement Number 4 on Policy to Protect the Nation's Wetlands",
February 21, 1973.
6. "Conservation of Endangered Species and Other Fish and Wildlife",
CFR, Title 50, May 19, 1972.
7. "Washington State Environmental Policy Act of 1971", Washington
-- Administrative Code 372-68.
8. "Washington State Environmental Policy Act of 1971", Revised
Code of Washington, Chapter 43.21 C.
W.
9. "Washington Water Quality Standards", WAC Chapter 173-201,
June 19, 1973, amended November 16, 1973.
�j
CHAPTER 2
SUMMARY AND RECOMMENDATIONS
•- This chapter presents a brief statement consisting of a summary
and recommendations for the Kent Facilities Plan. Following a
public hearing scheduled for June 6, 1977, at 8:00 P.M. in the
Council Chambers of the City of Kent and review of the comments of
agencies and interested parties, a final facilities plan will be
prepared. Barring unforeseen circumstances the final facilities
plan will be issued July 8, 1977.
In accordance with guidelines promulgated by EPA this Facilities
�. Plan has addressed a number of issues which are summarized in the
following paragraphs:
1. It has provided City officials with information on the
�., regulatory requirements for planning and construction of
sewerage facilities. This information will assist the
City officials in their decision making regarding extend-
ing sewerage facilities to where they may be needed.
Facilities Plans constitute a prerequisite for the
construction of any sewerage facilities where state or
federal assistance is involved.
2. It has provided City officials for decision making infor-
mation on environmental, historical and socio-economic
conditions in the planning area. Generally, environmental
�. conditions in the planning area show a quality environment
and further extending sewerage service will have no
discernible adverse impacts on those conditions.
10
3. It has provided the City officials with information on the
general conditions of the existing sewerage system and its
performance. This information will assist City officials
in their decision making regarding the utilization of the
system and its extension. Generally speaking the system
throughout the planning area is in good condition with
some exceptions in the older section of the Kent downtown
area.
4. In compliance with the regulatory requirements .this plan
has evaluated the extent of infiltration inflow into the
existing sewerage system. It has been determined that it
is not cost effective to replace any of the existing
sewerage system.
5. To aid the City officials in meeting the sewerage needs of
the planning area this plan has provided an estimate,
based on future growth and annexation, of future wastewater
loads. The estimates for the years 1980, 1990, and 2000
are 3.25, 4.75 and 6.51 mgd respectively.
6. The alternatives presented in this plan will provide a
framework for servicing presently unsewered areas within
the planning area and aid the City officials in land use
planning decisions. It is possible to provide sewerage
service to practically everywhere within the planning area
at varying costs Although it may be desirable that some
areas for one reason or another should never be intensively
developed.
11
6. (continued)
Specifically, the sizing of lines to serve the portion of
Area I situated west of the Auburn Interceptor and south
of the Green River, and Area M situated north of S. 212th
Street and west of the Green River should be carefully
reviewed prior to design and construction to determine
if their size is actually necessary in relation to
anticipated land use, and will not be built until the
absolute need occurs.
7. The environmental impacts associated with extending sewerage
service have been presented together with adverse impacts
and mitigating measures. Further developments necessitating
sewerage service, although will fulfill social and economic
needs, may result in adverse effects on air quality, increased
levels of noise, potential for flood damage and soil erosion.
With proper planning and control these impacts may be
substantially ameliorated.
8. This document will serve as a tool for coordinating
sewerage service with adjoining municipalities such as
Cascade Sewer District, City of Auburn, City of Renton,
City of Tukwila, Metro and others.
9. It is recommended that the Kent's City Council adopt this
facilities plan (after finalization) as a prerequisite for
federal and state assistance in meeting the City's future
sewerage needs.
12
CHAPTER 3
PLANNING CONSTRAINTS
The purpose of this chapter is to discuss several considerations
relevant to the formulation and evaluation of alternatives, to point
out those agencies who have jurisdictional authority over the plan
W and its implementation and to point out some of the rules, regulations
and permits relevant to the formulation of this plan.
PLANNING PARTICIPATION AND COORDINATION
A variety of governmental agencies are involved with different
r.
aspects of planning, selecting, financing, and operating wastewater
facilities. Presented below is a list and short description of the
major decision making entities associated with sewerage facilities
._ for the planning area.
o Environmental Protection Agency (EPA) - the lead federal
agency responsible for financing the planning and construc-
tion of wastewater collection and treatment systems; reivews
plans and evaluates environmental impacts of each project.
o U.S. Army Corps of Engineers - responsible for navigable
waters; issues permits for construction in tidelands.
o Washington State Department of Ecology (DOE) - the lead
state agency responsible for environmental matters; deter-
mines water quality criteria and effluent limitations;
administers the National Pollutant Discharge Elimination
System (NPDES); assists in funding of publicly owned waste
treatment systems.
13
o Washington State Department of Fisheries - responsible
for the food -fish resources of the State; in conjunction -
with the Department of Game issues a hydraulics permit for
construction either in or affecting fish habitats in fresh
or saltwater areas.
o Washington State Department of Game - responsible for
wildlife throughout the State; jointly responsible with
the Department of Fisheries for issuance of hydraulic
permits.
o Washington State Department of Social and Health Services
(DSHS) - reviews and regulates engineering designs, reports
and plans for construction of new waste treatment plants
or expansions to existing plants.
o Municipality of Metropolitan Seattle (METRO) - The agency
responsible for treatment of all wastewater from the study
area as well as other municipalities in Puget Sound. �-
o City of Renton shares the northern boundary of the study
area and is a participant in the Metro system.
o City of Tukwila shares the same Metro interception and
treatment facilities with the City of Kent.
o City of Auburn is also part of the Metro system. The City
forms the southern boundary of the study area and shares w
with the City of Kent Metro's valley interceptor and
treatment facilities.
o City of Des Moines is also a Metro participant.
14
o Cascade Sewer District shares with the City of Kent inter-
ceptor facilities which lead to Metro's Valley Interceptor
and Treatment Plant.
o Des Moines Sewer District borders the study area to the
west where drainage basins cross over the study area
boundary.
o Lakehaven Sewer District borders the study area to the
southwest where the District shares the responsibility for
studying the feasibility of providing sewerage service to
the Star Lake sub -basin, which is also a part of this
facilities plan study area.
o King County is the local government, other than the City
of Kent, in whose jurisdiction a substantial part of the
study area is located.
- REGULATORY CONSTRAINTS AND PERMIT REQUIREMENTS
The recommended plan must conform to many rules and regulations,
some of which were summarized in Chapter 1. Each of the many agencies
which gives its approval has its own requirements and criteria against
which the plan is judged. In particular, the EPA's Facilities Plan
Guidelines, (Reference 1), Construction Grants Regulations, (Refer-
ence 2), and Environmental Impact Statement Regulations, (Reference
3) affect the content of the Facilities Plan, since the federal
government shares in the funding of wastewater facilities. The
federal participation is presently 75% of the grant eligible costs
(such as treatment plants, interceptors and outfalls) and the state
15
participates in 15% of the same eligible costs. It is the responsi-
bility of the local residents to pay the remaining 10%, in addition -�
to the costs of land acquisition, building collector sewers, and
operation and maintenance of wastewater treatment facilities. In
the case of collector sewer laterals, the governments will only
participate in the funding of rehabilitation or replacement that is
shown to be economically preferable to accommodating infiltration/
inflow in the existing sewers. The governments normally do not
participate in collector sewers in areas being sewered for the first "
time under the present situation.
The Construction Grant process involves three steps as follows:
1. Step I - Facilities Planning
2. Step II - Preparation of Engineering Design and
Specifications.
3. Step III - Construction
Funding is allocated for each step following approval of the
results of the previous work..
Many permits are required prior to construction of the proposed
facilities, among them:
o State of Washington Department of Fisheries and Department
of Game permits for work in streams used by anadromous
fish for spawning or migration.
o U.S. Army Corps of Engineers permit for work near navigable
waters.
o Easements, building and conditional use permits, and all
other standard permits.
-- o Appropriate Municipal and State Shoreline Management
Substantial Development permit.
In addition, the present National Pollutant Discharge Elimina-
tion System (NPDES) permit for each existing municipal discharge
will be revised to reflect the progress toward compliance with
secondary treatment requirements.
WATER QUALITY'OBJECTIVES AND EFFLUENT LIMITATIONS
It should be pointed at the outset that this facilities plan is
indirectly concerned with the treatment aspect of the wastewater
generated in the planning area since wastewater is disposed of,
untreated, to the Metro Valley Interceptor where it is treated at
Metro's wastewater treatment facilities in Renton prior to release
into the Duwamish River. This plan therefore will not concentrate
on, neither ignore the treatment aspect of wastewater since the
planning area contributes incrementally to the wastewater load
treated by Metro's facilities.
A variety of laws, regulations, and policies at all levels of
government define the quality objectives for receiving waters and
the general environment. These objectives as well as natural
conditions and public concerns provide the goals, parameters, and
-» constraints for the planning and construction of wastewater inter-
ceptor and treatment facilities. The following discussion will
describe briefly some of the more important objectives affecting
17
water quality in the Duwamish River and the Green River within the
study area. The water quality objectives will be discussed under
the federal, state and local/regional levels.
Federal Level
Goals for publicly owned wastewater treatment facilities have
been delineated by the Federal Water Pollution Control Act Amendments
of 1972 (PL 92-500) and they include the following schedule:
1. For plants in existence on July 1, 1977, the provision of
secondary treatment is required;
2. Best Practicable Waste Treatment Technology (BPWTT) is
required by July 1, 1983;
3. The goal of elimination of pollutant discharge into
navigable waters by 1985 has been established.
Further, by July 1, 1977, compliance with other or more stringent
liminations or requirements to achieve state or federal standards,
objectives, or schedules is required.
To assist communities in meeting these goals and requirements,
the Federal Water Pollution Control Act Amendments of 1972 authorized
grants for sewage treatment works. The grants are awarded at each
step of a three -stage process referred to earlier.
Since the grants involve distribution of federal funds, the
provisions of the National Environmental Policy Act of 1969 (NEPA)
requiring the Environmental Protection Agency (EPA) to conduct an
M
environmental analysis must be met. The analysis includes and
evaluation of the potential environmental impacts associated with
-y the project.
The EPA further controls discharge of treated wastes from
treatment plants by requiring plants to obtain a permit according to
-- the procedures of the National Pollutant Discharge Elimination
System (NPDES). The system is administered in Washington by the
Department of Ecology (DOE).
.r State Level
The Department of Ecology has established water quality criteria
for the waters of Washington State. The Department also determines
effluent limitations for permit issuance. Puget Sound in which the
treated effluent from the study area is finally disposed of is rated
Class AA (Extraordinary). The Duwamish River from mouth to the
confluence with the Black River is rated "Class B". From the con-
fluence with the Black River upstream to the limit of tidal influence
it is rated "Class A" with the following exceptions: total coliform
organisms shall not exceed median values of 1000 with less than 20%
of samples exceeding 2400 when associated with an fecal source. The
Green River is rated "Class AA".
The following tables show the water quality standards for the
above classes.
19
N11
TABLE 2
STATE OF WASHINGTON WATER QUALITY STANDARDS
FOR CLASS
AA "EXTRAORDINARY" WATER
Water Quality Parameter
Standard
Total Coliform Organisms
Median values not to exceed 50 (Fresh-
(MPN/100 ml)
water) or 70 (Marine water) with less
than 10% of samples exceeding 230 when _
associated with any fecal source.
Dissolved Oxygen
Not more than 9.2 mg/l (Freshwater)
or 7.0 mg/l (Marine water). -�
Total Dissolved Gas
Not to exceed 110% of saturation at
any point of sample collection.
Temperature
Not to exceed 60°F (Freshwater) or
55°F (Marine water) due in part to
measurable (0.5°F) increases resulting
from human activities. -
pH
To be within the range of 6.5 to 8.5
(Freshwater) or 7.0 to 8.5 (Marine
water) with an induced variation of --
less than 0.1 units.
Turgidity (Jackson
Not to exceed 5 JTU over natural
Turbidity Units)
conditions.
N11
TABLE 2 (Continued)
Water Quality Parameter Standard
Toxic Radio -active or To be less than those which may
--. Deleterious Materials affect public health, the natural
Concentration aquatic environment or the desir-
ability of the water for any
usage.
Aesthetic Values Not to be impaired by the presence
of materials of their effects,
excluding those of natural origin,
which offend the senses of sight,
small, touch or taste.
21
22
TABLE 3
STATE OF WASHINGTON WATER QUALITY STANDARDS r
FOR CLASS
A (EXCELLENT) WATERS
Water Quality Parameter
Standard
Total Coliform Organisms
Median value not to exceed 240 (Fresh-
(MPN/100 ml)
water) or 70 (Marine water) with less
than 20% of samples over 1000 (230
for Marine water). r
Dissolved Oxygen
Greater than 8.0 (6.0, Marine waters).
Total Dissolved Gas
Not more than 110% of saturation
due to non -natural causes.
Temperature
Not to exceed 65°F (Freshwater) or
61°F (Marine waters) due to human -.
activities.
Increase due to one source less than
0.5°F; increase due to all sources -
less than 2.0°F.'
pH
6.5 to 8.5 (Freshwater) or 7.0 to
8.5 (Marine waters) with an induced
variation less than 0.25.
Turgidity (Jackson
Not to exceed 5 JTU over natural
Turbidity Units)
conditions. --
22
TABLE 3 (Continued)
Water Qualit Parameter Standard
Toxic, Radio -active or Less than the concentration affect -
Deleterious Materials ing public health, the natural
Concentration aquatic environment or the desir-
Aesthetic Values
ability of the water for any
usage.
Not impaired by materials or effects,
excluding natural causes, which
offend the senses of sight, small,
touch or taste.
23
TABLE 4
STATE OF WASHINGTON WATER QUALITY STANDARDS
FOR CLASS B (GOOD) WATERS
Water Quality Parameter Standard
Total Coliform Organisms Median value not to exceed 1000
(MPN/100 ml) less than 10% of samples.over 2400.
Dissolved Oxygen Greater than 6.5 (5.0, Marine waters),
24
or 70% saturation, whichever is
greater.
Total Dissolved Gas
Same as A.
Temperature
Not to exceed 70°F (Freshwater) or
66°F (Marine waters) due to human
activities.
6.5 to 8.5 (Freshwater) or 7.0 to
pH
8.5 (Marine waters) with an induced
variation less than 0.5.
Turgidity (Jackson
Not to exceed 10 JTU over natural
Turbidity Units)
conditions.
Toxic Radio -active or
Less than the concentration affect -
Deleterious Materials
ing public health, the natural
Concentration
aquatic environment or the desir-
ability of the water for any
characteristic water use.
24
TABLE 4 (Continued)
Water Quality Parameter Standard
Aesthetic Values Not reduced by dissolved, suspended,
floating, or submerged matter
excluding natural causes, so as to
affect water use or taint flesh of
edible species.
25
The Department of Ecology who administers the National Pollutant
Discharge Elimination System (NPDES) has issued a permit under this
system to the City of Kent (Permit No. WA -002939-4). The permit,
under certain conditions, recognizes the possibility of certain
overflows and bypasses from the two pump stations in the City of
Kent's system. These are Linda Heights P.S., and Aero -Kent (Spring-
wood) P.S. The permit also lists the industrial users who discharge _
their untreated effluent into the system. The overall purpose of
the permit is to effectuate compliance with the effluent limitations
specified in PL 92-500 in accordance with a specified schedule.
Local/Regional Level
At the local and regional levels, policies, goals, and objec-
tives are found virtually in all the existing and proposed plans
such as wastewater comprehensive plans, areawide management plans,
basin plans, solid waste management plans, land use plans, shoreline
master programs, and subdivision regulations.
In considering the impact and relevancy of local and regional
plans four factors appear pertinent. These are: health conditions,
recreational uses of the Green and Duwamish Rivers as well as Puget
Sound, sports and commercial fish populations, and land use in the
Green River Valley.
Health considerations constitute a primary issue in facilities
planning especially in new and unsewered areas. The study area is
substantially sewered and the health hazards associated with sewage _
are at an absolute minimum under normal operating conditions. The
NEV
Metro plant at Renton where the wastewater from the study area is
treated is capable of achieving secondary treatment.
•— In accordance with the conditions of the NPDES permit issued to
the City of Kent overflows and bypasses are allowed only under
emergency conditions such as equipment failure.
r- The recreational uses of the Green River within the study area
are not adversely affected by the existing system nor are they
likely to be affected in the future. The recreational uses of the
Duwamish River as the receiving water especially below the point of
discharge is not suitable to contact sports such as swimming. This,
however, is due largely to the other industrial and commercial uses
of the river.' Likewise no ill effects on sports fish population in
the Green River within the study area have occurred.
The cause effect relationship between sewerage facilities and
land use has been well documented and is often self fulfilling. The
land use plan, including the zoning map of the City of Kent is an
important factor in the formulation of this plan, not only within
the boundaries of the City of Kent but rather throughout the area
considered to be the area of interest (influence) by the City of
Kent. In this regard the Planning Department of the City of Kent
-� plays an important role.
The final contribution to quality objectives is the various
concerns and opinions of the resident populations and elected
— officials.
27
REFERENCES
1. "Guidance for Facilities Planning", EPA, January, 1974; and
"Guidance for Preparing a Facility Plan Municipal Wastewater
Treatment Works Construction Grants Program", EPA, Revised
May, 1975.
2. "Construction Grants for Waste Treatment Works", EPA, CFR Title
40, Chapter 1, Subchapter B, Part 35, February 11, 1974.
3. "Preparation of Environmental Impact Statement", EPA, Code of
Federal Regulations, Title 40, Chapter 1, Part 6, April 14, 1975
and Council on Environmental Quality, Chapter V, Part 1500,
August 1, 1975.
4. "Washington Water Quality Standards", WAC Chapter 173-201,
June 29, 1973, amended November 16, 1973.
5. "Secondard Treatment Information", EPA, CFR Title 40, Sub-
chapter D, Part 133, August 17, 1972.
6. "National Environmental Policy Act of 1969", Public Law 91-190,
enacted by Congress, January 1, 1970.
7. "Manual for Preparation of Environmental Impact Statements for
Wastewater Treatment Works, Facilities Plans, and 208 Areawide
Waste Treatment Management Plans", EPA, July, 1974.
8. "Environmental Protection Agency Administrator's Decision
Statement Number 4 on Policy to Protect the Naton's Wetlands",
February 21, 1973.
RN
9. "Conservation of Endangered Species and Other Fish and Wildlife",
CFR, Title 50, May 19, 1972.
10. "Washington State Environmental Policy Act of 1971", Revised
Code of Washington, Chapter 43.21 C.
29
CHAPTER 4
ENVIRONMENTAL INVENTORY
GENERAL DESCRIPTION
The Kent Planning Area encompasses the incorporated city of
Kent plus some additional unincorporated areas within the jurisdic-
tion of King County. Figure 1 shows the location of the Planning
�. Area; Figure 2 shows its boundaries The area covers approximately
-- 32 square miles. Land use in the Planning Area includes a mix of
residential, commercial, and light industrial uses. The area's
proximity to the employment centers throughout the Seattle -Tacoma
area makes it well suited to commuter -oriented residential develop-
ment. Industrial growth is expanding along the Kent Valley floor
transforming the use from agriculture to light industrial use. Kent
is close to Seattle and Tacoma, Sea -Tac International Airport, two
major transcontinental rail lines, two major inter -state freeways,
and lots of flat industrially zoned land which contribute to
attracting new industry to the Kent area. The area will continue
to experience economic and population growth for the next several
decades.
At present about 20 square miles within the planning area are
served by the City of Kent.
,.., NATURAL CONDITIONS
The principal topographic features are the upland plateaus
rising from both sides of the Green River Valley. The valley
�.. itself connects the adjoining cities of Auburn to the south and
CIN
Tukwila and Renton to the north. The valley is about 2-1/2 miles
... wide with an elevation ranging from 20 to 30 feet above sea level
before it ascends to two bordering hills. The West Hill rises
quickly to about 300-400 feet with a steep slope while the East Hill
rises to about 400 feet with a much more gentle slope. Because of
the East Hill's gentle slope, more development has occurred there.
A topographic map has been included and appears as Figure 3.
The Planning Area itself has been defined by topography. The
W area contains all drainage basins which flow toward Kent. The basic
drainage pattern after water leaves the hills and moves to the
valley is for it to move northward, as does the Green River toward
Tukwila and Renton.
Soils and Geology
The geology of the Puget Sound area is primarily the result of
processes which occurred during the Vashon period of the great
Fraser glaciation about 15,000 years ago. The major portion of the
region was covered by ice several thousand feet thick. As the ice
-' moved, it compressed the underlying earth and carved it into the
valleys and ridges present today. In addition, the glacier scraped
r. away the pre-existing soil of the area. As the ice retreated, it
left behind the geologic and soil types characteristic of glaciated
areas. The geology of the planning area is predominantly very
dense and consolidated material called glacial till over varying
thicknesses of clay, sand, or bedrock. The till is overlain by
erosional material. (See Reference 2 for an interesting discussion
of local geology.)
33
The surficial geology of the Green River Valley is composed
entirely of alluvium -sedimentary material deposited by streams and
lakes. This alluvium deposit is of recent origin, accumulating over
W- the past 4,500 years, and it contains numerous and various layers of
clay, silt, sand, gravel, and peat. The Green-Duwamish Valley
alluvium deposit offers some of the most fertile soils in the
Pacific Northwest.
Several fault lines exist on the slopes of the East and West
Hills, northeast, northwest, and Southwest of the Kent city limits.
These fault lines lend evidence to the instability of the region's
slopes.
Soil composition and characteristics are very important when
planning optimum land uses for a region. Developing improper uses
for certain soil types will require expensive man-made alterations
of the natural environment in order to sustain the desired incom-
patible land use. The nature of the soil determines drainage
bearing capacity, and wastewater "accommodability".
The Kent lowland soils are generally homogeneous consisting of
primarily three nearly identically textured, alluvial soils: the
Puyallup, Puget, and Sultan soils. There are several different
types of soil within each individual soil series. The East and
West Hills, like the lowland, are basically homogeneous, but
they consist primarily of one soil series, the Alderwood series.
Generally, the soil types of the Kent lowland are unsuitable
for urban and industrial uses. Because of the drainage problems
and low bearing capacity of valley soils, home sites, septic tank
35
filter fields, sewage lagoons, sanitary landfills and heavy build-
ing sites are unsuitable land uses unless expensive, man-made
compensations are constructed. The Alderwood soil of the East and
West Hills are generally unsatisfactory for septic tank filter
fields, but do offer a high bearing capacity suitable for home and _
heavy building sites.
Figure 4 shows that most of the Planning Area, in the valley
and on the hillsides, has soils that are moderately or severely
limited for septic tank/drainfield use. Development in such areas
requires sewers.
Climate
The planning area is influenced by the West Coast Marine
climate which is characterized by mild, wet winters and cool,
relatively dry summers. Nearly all precipitation occurs as rain-
fall, although snow does occur each year. Approximately 75% of the
rainfall occurs between October 1 and April 1, with a mean annual
precipitation of 34.1 inches in Kent.
Temperatures are moderated by the proximity of Puget Sound.
The mean annual temperature in Kent is 51.7 degrees F. while the
maximum and minimum recorded readings are 100 degrees and -5
degrees respectively.
The prevailing winds in the region are from the south in the
fall and winter, gradually shifting to the north in late spring and
summer.
36
Legend
Severe Limitations
Moderate Limitations
"INEENEEN' Slight Limitations
rtZ—LIJNorrIth
0 % % % 1
Figure 4
Soil/Slope Septic Tank Suitability
Air Quality
The Puget Sound Air Pollution Control Agency routinely moni-
tors the air quality at a station in Kent. Table 5 summarizes the
recently collected data for the site. Comparison of these data
with standards established to protect public health reveals that the
air quality at these locations is well within the primary standards
with the exception of photochemical oxidants. Kent recorded viola- `✓
tions of the photochemical oxidant standard for five hours during
1975.
The low wind speeds in the area, high frequency of low level
inversions, and the constraining effects of the valley walls tend to
trap locally -generated emissions. This results in poorer air ~
quality than in areas adjacent to Puget Sound having the same
emission density. Examination of the Puget Sound area confirms that
the lower emission density in the Kent area results in air quality
comparable to that in many other areas in Seattle and Tacoma with
higher emission source densities. Air duality is threatened onlv
during "inversions" when air pollutants are trapped and concentrate
within the "walls" of the valley and below the "ceiling" of the
"inversion". Methods to minimize concentrations of suspended -
particulates include eliminating slash burning, improving mass
transit thus reducing automobile traffic, and converting from fossil
fuel to electricity for heating and technological improvements.
Noise
No known noise studies have been conducted in the Kent Plan-
ning Area. However, the area has evolved from a very quiet rural
farming community to an urbanized and suburban community. Increased
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noise in an urbanizing area can usually be attributed to increased
traffic, especially truck traffic, and increased highway speeds.
With the construction of major freeways in the area and the addition
of truck traffic associated with industrial development, the once
quiet town is quickly becoming a bustling urban center.
Water Quality
Protection and improvement of water quality are primary con-
cerns of this plan. This section covers water quality of both
surface waters and groundwater. Water quality is discussed from the
perspective of how improper sewage disposal or treatment may be
degrading water quality. The status of each significant body of
water wihtin the planning area will be discussed.
Lake Fenwick lies in a small valley in the southwestern area of
Kent. (See Figure 1.) The lake is approximately 20 acres in size -�
and is the focal point for a 642 acre drainage basin located in the
Cambridge residential area. It is 31 feet deep and contains an `+
estimated 285 acre feet of water. The lake drains southeasterly
into the Green River Valley. Severe sediment damage has occurred in
Lake Fenwick in recent years caused by residential development to
the west. Suspended sediment in the lake has lowered water quality
in the past and is a concern. (Reference 3)
Star Lake lies southwest of Lake Fenwick, just outside the Kent
City limits. (See Figure 1.) The 34 acre lake is fed by a 370
acre drainage basin in which there is considerable residential land -
use dependent on septic tanks for sewage disposal; runoff from two
40
major roads in the area also flows toward the lake. Metro studies
of nutrient levels indicate significant enrichment; nuisance algal
blooms are becoming more likely. Monitoring by the Seattle -King
-� County Health Department has revealed bacterial contamination during
the summer. (Reference 10)
The Green River flows from the Cascade Mountains to Puget
Sound. The river meanders basically from south to north with a
peak discharge of 11,400 cfs. The river averages about f50 feet
in width through Kent. The river flooded annually.before the Howard
Hanson Dam and man-made levees and dikes were built in 1962. Much
of the low-lying area along the Green River has been identified as
having severe drainage problems, including local flooding during
high flood stages, (Reference 11) In the vicinity of Kent, State
water quality standards fbr dissolved oxygen, temperature, nutrients,
and bacteria have been violated at least once every two years. Low
stream flows during warm summer months appear to be the cause.
Bio -chemical oxygen demand from point discharges of wastewater does
not.appear to be significant. Other pollutants encountered include
�. coliforms, nitrate -nitrogen, and algae. Total coliform standards
are violated frequently each year; sources of contamination appear
to originate upstream in the Green River system. Nutrient levels
are high enough to support algal growths. Nuisance aquatic growths
r
have been observed downstream from the Kent -Highlands landfill site
and are thought to be associated with this source. (Reference 7)
Mill Creek flows northwesterly through the southeast area of
Kent, draining a basin of approximately 1,000 acres. The creek
drains an area that has undergone major land use changes from that
41
W
of rural forested farmland to that of rather intensively developed
commercial and residential development. Velocities in the Creek -'
vary from 20 cfs to 150 cfs during the year. As urbanization of
the Mill Creek Basin continues, the summer flows will lessen as
ground water sources dry up. The City of Kent is presently
developing a detention pond to detain excess storm runoff
and maintain summer flows.
Groundwater in the valley and on the upland hills is replen-
ished by precipitation during the wet winter months and ultimately
discharges to the Green River. The City of Kent relies on ground
water reached through wells and springs which are located east of
the town on the plateau. Groundwater quality in the Kent area is
very good.
Vegetation and Animal Life
Much of the land within.the area is semi -urban in character,
and as such represents an alteration of the naturally occurring �-
ecosystem. Some limited sections of second growth forest do exist,
and the plant and animal life typically associated with this eco-
system occur in these locations. Much of the indigenous vegetation
has been replaced by floral species valued for landscaping. In
these areas the fauna was also affected. Most large animals have
been displaced or destroyed due to urbanization-. Thus, the remaining
species are limited to those that were able to adapt to the changed -
condition and are able to exist in close proximity to man.
The study area falls within the Humid Transitional Life Zone
which extends from sea level to about 3,000 feet in elevation. r
42
In the Green River Valley permanent and seasonal wetlands are the
�-. most important habitats. On the surrounding plateaus the dominant
habitat is a mixed (coniferous -deciduous) forest. Deciduous
forests, brushlands and wetlands are also found on the plateaus.
Some rare and endangered species are found within the study area
and are listed on Table 6.
The project area includes several lakes, rivers, and streams
that, together with their characteristic shoreline vegetation,
provide necessary habitat for such waterfowl as herons and osprey,
mammals favoring aquatic or semi -aquatic habitats (e.g. marsh
shrew, Townsend's mole, beaver), amphibians and fish.
Although the Green River Basin contains both warm and cold
water fishes, data and information sufficient for critical evalua-
tion is available only on the cold water group. Anadromous salmonids
making up this group are chinook, coho, and chum salmon, steelhead,
searun cutthroat, rainbow, and Dolly Varden trout, all of which
spawn in the river.
The state maintains and operates the Green River Salmon
Hatchery on Big Soos Creek near Auburn. Fall chinook and coho
salmon and some chum are propagated at the Green River facility.
Most of the fish produced here are released into the Green River.
Total fish production data of the hatchery and the natural
habitat are presented in Table 7.
43
TABLE 6
RARE, THREATENED OR ENDANGERED ANIMALS
WHOSE RANGE INCLUDES THE GREEN RIVER SEWERAGE AREA
AMPHIBIANS
Northwest Pond Turtle
BIRDS
Western Grebe
Double -crested Cormorant
Great Blue Heron
*Green Heron
Whistling Swan
*Aleutian Canada Goose
Sharp -Shinned Hawk
Cooper's Hawk
Bald Eagle
Marsh Hawk
*Osprey
Gyrfalcon
*Peregrine Falcon
*Pigeon Hawk
Sparrow Hawk
Barn Owl
*Spotted Owl
*Black Swift
*Anna's Hummingbird
*Bank Swallow
Purple Martin
*Winter Wren
Bewick's Wren
*Western Bluebird
*Hermit Warbler
Western Meadowlark
*Purple Finch
*Pine Grosbeak
*White -winged Crossbill
*Golden -crowned Sparrow
MAMMALS
*Keen's Brown Bat
*Red Bat
*Townsend's Meadow Mouse
*Red Fox
Clemmys marmorata marmorata
Aechmophorus occidentalis
Phalacrocorax auritus
Ardea herodias
Butorides virescens
Olor columbianus
Branta canadensis leuco areia
Accipiter striatus
Accipiter cooperii
Haliaeetus leucocephalus
Circus cyaneus
Pandion haliaetus
Falco rusticolus
Falco peregrinus
Falco columbarius
Falco sparverius
Tyto alba
Strix Occidentalis
Cpseloides niger
Calypte anna
Riparia riparia
Progne subis
Troglodytes troglodytes
Thryomanes bewickii
Sialia mexicana
Dendroica occidentalis
Sturnella neglecta
Carpodacus purpureus
Pinicola enucletor
Loxia leucoptera
Zonotrichia atricapilla
Myotis keeni keeni
Lasiurus borea "is-teliotis
Microtus townsendi
Vulpes vulpes fulva
* Species on preliminary list of rare and endangered animals in
Washington State, prepared by the U.S. Bureau of Sport Fisheries
and Wildlife (Olympia).
44
TABLE 7
.., ANADROMOUS FISH NATURAL PRODUCTION
(HARVEST PLUS ESCAPEMENT),
CEDAR -GREEN BASINS
(Reference 7)
Species
Range
Average (Annual)
-� Chinook
4,200-31,240
13,960
Coho
56,900-296,000
162,400
Chum
7,440-86,410
33,360
Sockeye
48,000-190,000
90,000
Summer Steelhead
40-280
130
59,100
Winter Steelhead
42,600-79,100
Searun cutthroat 2
43,800-80,500
61,000
�- Searun Dolly Varden
1 Period involved in
determining fish numbers is
1956-1965.
Exceptions: sockeye
salmon (1964-1967), searun
trout (1962-1966).
2 Production limited
and therefore not determined.
SOCIAL CONDITIONS
Population
Population projections for the planning area have been taken
from the Kent Comprehensive Plan. (Reference 2) The Kent Compre-
hensive Plan in turn utilized projections from the Interim Regional
Development Plan which were updated in 1973 by -the Puget Sound
Council of Governments' Activity Allocation Model. The Activity
Model projects population for each census tract. The boundaries of
the Planning Area and the census tracts do not coincide. Therefore,
assumptions as to the number of people and land area within the
planning area today had to be made before any projections could be
made. For the facilities plan planning area, the past and future
population estimates are given in Table 8.
45
TABLE 8
ESTIMATED POPULATION OF PLANNING AREA
Year Population
1970 17,500
1980 22,000
1990 30,000
2000 41,000
In 1976 the City of Kent estimated that there were 3.2 people
per single family dwelling unit and 2.0 people per multiple dwelling
family unit (apartment) within the City of Kent. The trend for the
number of people per dwelling unit to decrease is expected to
continue.
The following table indicates how the population of Kent
differs from that of Washington State as a whole. As can be seen
from the table, the median family income of a Kent family is higher;
the median amount of education received is insignificantly smaller;
and Kent residents are more mobile.
TABLE 9
POPULATION CHARACTERISTICS
Median Family Income
Median years of School
Different House - Same
County between 1965 and 1970
Class of Worker
Private or Salaried
Government
Self -Employed
Agriculture
46
Washington
Kent
State
$11,473
$10,407
12.3
12.4
59%
24%
82%
70%
12%
18%
5%
8%
1%
4%
Housing
Kent is typical of the region in that almost 75% of Kent's
housing units are single-family residences; the percentage of
multi -family dwellings is increasing; the overall vacancy rate is
currently low; and housing costs are rising rapidly. Kent's
housing differs from that of the region in that it generally is in
better condition, since most of it (40.6%) was built from 1960 to
-� 1970; the ratio of owner -occupants to renter -occupants is 2:1.
The Kent area will experience considerable population and
household growth in the future. The exact timing of this growth is
dependent upon many factors - construction of utilities, the
effects of the gasoline shortage, the local and regional economy,
etc., according to the Kent Comprehensive Plan - Resource Data
document. (Reference 3).
Land Use
Historically, the Green River Valley has been used for agri-
cultural purposes because of its excellent soil. However, because
of its location near Seattle -Tacoma, the Sea -Tac Airport, and two
�. railway lines, recent decisions to locate new freeways to improve
accessibility, new utilities, and flood control devices constructed
in the Valley, it has been transformed into an industrial area with
residential areas lining the hillsides. Increasing property taxes
r. forced many farmers to sell their lands to speculators when farming
was no longer profitable. Much of the undeveloped land is owned by
speculators who lease land to farmers until they want to develop it
to a more intensive land use. Most of the valley floor is zoned
for industrial use now. The trend for the valley to become more
47
urbanized will continue. A study completed in 1974 by Corff and
Shapiro, Inc. showed how the 33,320 acres of the Green River Valley
had changed since 1965. The following table was taken from their
report:
TABLE 10
LAND USE
AREAS, 1965
AND 1973
(Reference 7)
USE
1965
1973
%
CHANGE
Industrial
1,150
3,130
+
172%
Power Lines
230
250
230
700
+
0%
180%
Commercial
Residential
2,420
4,220
+
74%
- Tract
- Non -Tract
3,690
3,990
+
8%
- Multi -Family
80
160
+
100%
- Mobile Homes
20
210
+
950%
Agriculture
14,370
9,020
Open Space
- Wooded
5,560
4,160
-
25%
- Non -Wooded
3,290
2,700
-
18%
Site Preparation
840
1,540
+
83%
Institutional
340
530
+
55%
Parks - Recreation
150
430
+
186%
Transportation - Freeways
80
920
+1,050%
Gravel Quarries
250
700
+
180%
Water
600
630
+
13%
TOTAL
33,320
33,320
---
King County has recently proposed an agricultural lands policy
which designates land throughout the county to be preserved for
agriculture. Three areas adjacent to Kent (see Figure 5) are so
designated by this policy statement. The City of Kent can affect
the agriculture designation of an area by what it permits adjacent
to it. Adjacent to Area "B", Kent has zoned the property mainly
"residential agriculture" and "industrial agriculture" with a small
portion zoned "garden density multi -family" and "medium density multi-
family" which are compatible. Adjacent to Area "A", Kent has zoned
ON
U
I LLIA
�o
w
S 212nd St
w
in
d
COQ
CO
0
�es� zr Ja
?� S 240th St SE 240th St
N
KENT w
$, W Meeker
a
Q
B
SE 256th -Sy "
�enr
La
w
w
e
�
C
N
¢
,P
y
00 S
W
C-71
S 272nd St
St
SE
272nd
St r
to Lake Road co
Planning Area Boundary
^
288th St S
.
Legend
Miles
Agricultural Areas Designated
FLFLINorth
0
'/4
'/z
La • 1
by King County
Figure 5
King County Agricultural Lands
property "Residential Agriculture" to the south and "Industrial Park
District" to the east across the river. "Residential Aariculture"
is compatible. An "Industrial Park District" would typically not be
compatible and would tend to influence the adjacent lands to be
industrially used; however, in this instance the river separates the
two uses. Area "C" is adjacent to land zoned "multi -family" and
"limited industrial", which are incompatible uses; however, the
river again separates the uses, thus making them more compatible
than anticipated. Some of the existing adopted King County agricul-
tural policies state that:
o "Sewer and water local improvement district assessments
on agricultural land are frequently detrimental to the
operation of farms in King County."
o In order to preserve agricultural lands, sprawled develop-
ment should be avoided and the urban center development
concept should be adopted.
o "King County shall approve those connections to sewer
interceptors reviewed by the County only when such
action shall not adversely affect the agricultural ._
potential of the District".
o "King County shall not approve rezone applications for
more intensive use classifications for any of the Agricul-
tural Lands of County Significance" as designated.
o Boundaries surrounding designated "Agricultural Land of
County Significance" can be revised when the County --
6111
Council finds that the continued economic viability of
W
farm operations conducted in these subareas changes.
o Agriculture lands designated shall not be divided into
parcels of less than 10 acres.
Generally, the City of'Kent's zoning is compatible with
adjacent agricultural lands designated by the proposed King County
Agricultural Ordinance.
r. The Kent Comprehensive Plan (Reference 2) notes the following
land use policies:
o The West and East Hills should be used for residential
development.
o The city should concentrate facilities and services in
new areas to minimize sprawled development.
o Adequate sewerage facilities should be provided adjacent
to waterways.
-- SERVICES AND FACILITIES
Police
The bulk of the planning area lies within the jurisdiction
of the City of Kent. There are 25 officers, 5 detectives, and
5 patrol units assigned to the Kent Police Department.
Fire
Fire protection in the planning area is provided by the City
of Kent. The department employs 31 paid firemen and 35 volunteers,
51
and operates 6 engines, 5 utility vehicles, 1 aid car and 1 heavy
duty rescue vehicle.
Water r
Service is provided by the City of Kent. The source of the
water supply is from springs.. There is a reserve capacity in the
system to meet future additional demand. The average water demand —
is 5 million gpd with a peak demand of 8 million gpd. The storage
capacity is 18 million gallons with a pumping capacity of 11
million gpd.
Sewage
Service is provided by the City of Kent. Treatment is provided
by METRO, a county wide sewer agency. The Kent Comprehensive Plan
(Reference 2) identifies as its second goal the provision "for a
planned, coordinated and efficient sanitary sewer system." The
objectives it lists to support this goal are as follows:
Objective 1
Complete and implement a comprehensive sanitary sewer
plan encompassing both facilities and services.
Objective 2 --
Coordinate closely with METRO and local sewer districts
to insure that adequate and efficient sewer service is
available to all the Kent area.
52
Objective 3
Finance and develop the sanitary sewer system based on
�- planned development patterns and land decisions.
Objective 4
Develop an equitable rate structure which encourages an
adequate sewer system.
Highways
Interstate Highways 5 and 405 and State Route 167 presently
provide excellent access to Kent and its surrounding area. These
freeways were all constructed between 1965 and 1970 and have
contributed most to Kent's recent growth and transformation.
Schools
The planning area is served by the Kent School District which
has 15 elementary schools, 4 junior high schools, and two senior
high schools. The 1976 enrollment of the Kent public schools
numbered 15,500. Higher education can be provided to the area's
residents from Green River Community College in Auburn or Highline
Community College in Midway. Six universities are also within easy
�- commuting distance of the area.
Parks and Recreation
Recreational facilities include three community parks, one
private and one public golf course, and a thoroughbred horse race
track.
53
ARCHAEOLOGICAL AND HISTORICAL SITES
A search of archaeological and/or historical site records by
the Washington State Department of Recreation revealed that archaeo-
logical and historical resources are present in the Kent Planning
Area (Reference 9).
SUMMARY OF ENVIRONMENTAL CONCERNS
The most important environmental concerns for planning in the
area are as follows:
o The soil types present in much of the planning area impose
moderate to severe limitations on the ability of septic
tank systems to provide adequate wastewater treatment and
disposal.
o Conversion of prime agricultural land to residential use
should be avoided.
o Protection and improvement of water quality of both ground
water and surface waters, particularly Lake Fenwick and
Star Lake. `
54
REFERENCES
1. U.S. Department of Commerce Bureau of the Census, 1970 Charac-
teristics of the Population - Washington, Vol. 1, Part 49.
2. Kent Planning Department, Kent Comprehensive Plan, September,
1976.
3. Kent Planning Department, Kent Comprehensive Plan - Resource
Data, Draft #1, March, 1976.
4. King County Ordinance 76-1073, King County Agricultural
Districts, 1976.
.� 5. U.S. Department of Agriculture, Soil Survey of King County,
Washington, November, 1973.
6. Puget Sound Air Pollution Control Agency, 1975 Air Quality Data
-. Summary for Counties of King, Kitsa , Pierce, and Snohomish,
July, 1976.
7. U.S. Environmental Protection Agency, Final Environmental
Impact Statement - Auburn Interceptor (Green River Sewerage__
Area), June 13, 1975.
8. Washington State Department of Commerce amd Economic Development,
-- A Standard Community Industrial Survey for Kent, February, 1973.
9. Correspondence from Jeanne M. Welch, Acting State Historic
Preservation Officer, State of Washington, February 3, 1977.
10. Lakehaven Sewer District, Star Lake Facilities Plan, April, 1976.
11. River Basin Coordinating Committee, Urban Drainage Study,
Appendix A, Vol. 2, December, 1974.
55
CHAPTER 5
EXISTING WASTEWATER SYSTEM CONDITION,
FLOWS AND POLLUTANT LOADS
INTRODUCTION
For the most part, the City of Kent is served by an adequate
sewerage system. The main interceptor system is basically complete
in the areas presently occupied. A substantial portion of the
sewers in the older downtown areas are in need of repair and/or
replacement to reduce infiltration/inflow but are functioning
without presenting a health problem. The main areas of concern are
the portions of the entire service area where growth is expected to
occur.
GENERAL SYSTEM CONDITIONS AND PERFORMANCE
The sewage collection and interceptor system serving the City
of Kent is in general adequately sized and in good condition with
the exception of the older portion of the City where an infiltration/
inflow problem exists. These older lines are being replaced through
-- an on-going program by the City.
The main portion of the newer collection system and virtually
all of the interceptors have been planned and constructed within
-- the past 15 years, and were designed based on projected ultimate
densities. The system is functioning with a minimum amount of
maintenance and is not subject to overloading.
011
One potential future problem concerns Metro's Mill Creek
Interceptor and the interceptor upstream from S264th Street and
104th Avenue S. to S. 256th Street and 116th Avenue S. This inter-
ceptor receives sewage pumped from the Cascade Sewer District's Soos
Creek drainage basin, and from the housing development of Timberlane
to the east. Also, there is planning being undertaken by King
County to determine the feasibility of delivering sewage from the
Black Diamond - Lake Sawyer area. This will be discussed under a
subsequent portion of this chapter. ._
In general, the performance of the system is good with no
significant problems that are not being dealt with the City in an
orderly and continuing manner. The existing system is shown on
the system layout appended to this report.
EXISTING CONDITION,
Collection System
As previously stated, the collection system, with exception of
the older downtown area, is in good to excellent condition, is
adequately sized, and is functioning with very little maintenance.
Where infiltration and/or inflow exists, some lines are surcharged
during wet weather, but are not subject to overflow problems. These
lines require an inordinately large amount of maintenance, but the
problem is gradually being overcome by replacement of the deteri-
orated sewers.
Downstream from these areas the interceptor system is large
enough to accommodate these high flows with little impact.
57
Unsewered Areas
Within the study area of this report, there are several unsewered
areas; however, in most cases the drainage patterns have been estab-
lished and the basic interceptor network has been constructed to
receive the flows from these areas when development occurs. These
areas, for the most part, are located along the outer fringes of the
•-- natural drainage basins tributary to the Green River Valley, and can
be served by extending the existing gravity system.
The southerly portion of the study area, encompassing the
�- valley floor and portions of the West Hill area will require some
pumping to provide service. In particular, the area aLvur►u LdRC
Fenwick will require pumping and the area around Star Lake if it is
to be served through the Kent system. The Auburn Interceptor, now
nearing completion, will provide the trunk line necessary for the
extension of laterals and interceptors required to serve the valley
floor and tributary uplands.
The southeast portion of the study area extends into the
drainage basin naturally tributary to the Soos Creek drainage basin.
The City presently serves the housing development known as Springwood
and now being managed by the King County Housing Authority. This
development is within the Soos Creek drainage basin, but is pumped
westerly into the Kent system. Also, there is substantial development
existing principally in the Derbyshire area east of 116th Avenue S.
and south of S. 272nd Street. While the natural drainage pattern is
-- easterly to the Soos Creek area which is not presently served by a
gravity interceptor line, the need for sewer service may cause the
development of a pumping system westerly over the drainage divide
into the Kent system.
58
At this point it should be noted that a substantial area around
Lake Meridian and northerly is being served by Cascade Sewer District,
and the sewage is being pumped from the Soos Creek drainage jDasin
westerly along S.E. 256th Street into the Kent system. Also, the
possibility of sewer service for the Black Diamond -Lake Sawyer area M
is being explored with discharge into the Cascade Sewer District and
then into the Kent system. Until such time as an interceptor is
constructed from the Soos Creek area to the Auburn Interceptor, any
additions to the Cascade Sewer District tributary to the S.E. 256th
Street pumping station will hasten the time when the City of Kent
and Metro's Mill Creek Interceptor system will reach capacity.
While the Soos Creek area is not a natural part of the Kent
system, future development will affect the City's ability to serve
the East Hill Service area south of S. 248th Street.
Sewage Treatment Facility
All sewage generated in the Kent service area is treated at --
Metro's Renton Treatment Plant. The City's collection system is
discharged into Metro's Interceptor network in the Valley and
ultimately into an existing 72 inch trunk line extending north from
S. 216th Street and 76th Avenue S. to the Renton plant. No change
in the agreement is anticipated.
At the present time, the City serves approximately 12,335
customers and customer equivalents. Based on 225 gpd per customer
or equivalent, the sewage flow generated within the system would be .�
approimately 2.8 mgd, exclusive of any extraneous flows entering the
system through infiltration and inflow.
59
SUMMARY
The City of Kent collection system as it now exists is adequately
sized and in good condition with the exception of the older portions
previously noted. The main area of need is the devlopment of a plan
which will provide the guidance for the extension of the system to
all areas considered to be a logical part of drainage basin. This
could include service to limited areas not tributary to the natural
.. basin, but which through physical impediments or timing should
become a part of the Kent system.
W
CHAPTER 6
INFILTRATION/INFLOW ANALYSIS
PREVIOUS STUDIES
r In conjunction with sewer system projects constructed by the
City of Kent, and other agencies, the City has conducted four
.� infiltration/inflow analyses for substantial portions of the City's
sewage collection and interceptor system. These studies were
undertaken at various times as a part of the process of establishing
.� eligibility for Environmental Protection Agency and Department of
Ecology construction grants.
Three of the infiltration/inflow analyses were completed in
. 1973, and were prepared for the following projects:
1. Garrison Creek Interceptor
2. Linda Heights Pump Station Modifications
-� 3. 100th Avenue Interceptor
The fourth study was completed in 1974 and was prepared in
conjunction with the Metro -Auburn Interceptor project. This study
-- covered the older portion of the City's collection system, and a
substantial amount of relatively new system. For the most part, the
systems studies are located in the Valley floor and are subject to
high groundwater tables.
The results of these studies have been summarized and are being
presented in a condensed form for the purpose of unifying the findings
of the studies previously completed.
61
SUMMARY OF COMPLETED I/I ANALYSIS
As mentioned, four independent I/I analyses have been completed
on portions of the City of Kent sewerage system. The areas studied, -
which collectively comprise approximately 40% of the total system
are shown on Figure 7. A summary of each study is as follows:
Garrison Creek Interceptor
This study cover the Plats of Stockton and Kenton Firs located
southeasterly of 124th Avenue on S.E. 100th Street, and was done in
conjunction with the Garrison Creek Interceptor project constructed
by the City. The study covered approximately 6,360 feet of 8" pipe
and 700 feet of 12" and 18" interceptor, all installed in the period
from 1969 to 1972. This system is in the East Hill area of the City
at an elevation of approximately 400'.
An analysis of the flows showed that this system is entirely
free of infiltration and inflow.
100th Avenue Interceptor
This study consisted of an analysis of the system tributary to
the Hines pumping station then in existence. The 100th Avenue
Interceptor constructed by the City has subsequently intercepted the
flow to the pump station and now flows by gravity to the Garrison
Creek Interceptor at the intersection of 100th Avenue S.E. and S.E.
124th Street.
The study covered approximately 30,000 feet of 8" concrete pipe
and 1,400 feet of 12" concrete pipe. The area is located generally
62
east of 104th Avenue S.E. and south of S.E. 224th Street in the East
Hill area of the City. Elevations in the area range from approxi-
mately 380' to 450' above mean sea level.
The results of the flow analyses from this area showed a minor
and insignificant amount of infiltration and inflow occurring only
in February of the year under study. This month had a period of excep-
tionally high rainfall, and excessive flow was attributed to a plugged
storm drain line which caused a ponding of water over manholes.
Linda Heights Pump Station
This study was undertaken in conjunction with a project upgrad-
ing the Linda Heights Pump Station serving an area on the West Hill
of Kent. The area served is located generally between S. 240th and
S. 252nd Streets and between Interstate 5 and 36th Avenue S.
The system studied consist of approximately 17,000 feet of 8"
pipe constructed in 1959 and 1960. The elevations in the study area
range from 400' to 500' above mean sea level.
.- An analysis of the flows in the study area showed virtually no
correlation between rainfall and flows generated. Since the flows
closely approximated the anticipated theoretical flow for the
system, it was concluded that infiltration and inflow are not a
problem in this area.
Metro -Auburn Interceptor
-• The I/I Analysis performed for this project was by far the most
extensive study of the four completed to -date, both from the stand-
point of amount of pipe, and from flows generated.
The area studied consisted of three independent sub -systems;
the James Street system, the Smith Street system, and the South
system. The sub -systems serve all of the old area of the City and a
substantial amount of more recent developments. The age of the pipe
ranges from more than sixty years old, to virtually new construction.
The older pipe is vitrified clay and some concrete, while the new
pipe is concrete with some cast iron.
The size and -approximately combined length of the pipe in the
three systems is as follows:
Size Approximate Length
6"
8,540'
8"
76,650'
10"
7,250'
12"
14,550'
14"
3,500'
18"
190'
24"
3,000'
The footage of pipe in each sub -system is as follows:
James Street System 12,820'
= 2.43 mi.
Smith Street System 66,900'
= 12.67 mi.
South System 35,660'
= 6.75 mi.
Total
21.85 miles
The James Street System is located primarily in the valley
floor, and while some of the pipe is relatively new, much of the
system is of older construction. Variations from theoretical
anticipated flows range from 700% during dry periods to 1150% during
wet periods.
Approximately 50% of the Smith Street System is located on
Scenic Hill at elevations of from 50' to 350' above mean sea level.
The Scenic Hill system is geographically part of the East Hill System.
64
While a substantial amount of the pipe in this area is old, infiltra-
tion and inflow were found to be insignificant. The remaining
portion of the system is old pipe located in the valley floor.
Variations from theoretical flows range from 550% to 700%; the
decrease in variation from the James Street System being attributed
to the influence of the lack of I/I from the Scenic Hill area.
Virtually all of the South system is located in the valley
floor, but has been constructed within the past 15 years. A substan-
tial portion of the South System, tributary to.the Horseshoe Acres
pump station, was constructed in 1971 and 1972. The flow analysis
of the South System showed an insignificant amount of infiltration
and inflow.
While the study of the three sub -systems showed a large amount
of infiltration and inflow, it also disclosed that the problem is
basically confined to the older portions of the system. Pipe
installed within the past 15 to 20 years is generally in good
condition with little or no infiltration/inflow problems. This is
particularly true in the higher elevations.
Despite the presence of a large amount of extraneous flows in
the older parts of the system, a cost-effective analysis disclosed
that these flows were not excessive by definition. A significant
factor in this analysis was the low cost of treatment by Metro.
RELATIONSHIP TO TOTAL SYSTEM
The City of Kent System consists of approximately 445,000 feet
of pipe, or some 84 miles. Of this amount, 171,500 feet, or 32.5
65
miles have been studied under the previously summarized I/I Analyses.
This constitutes slightly under 40% of the total system. Also, of
this 32.5 miles, 12.5 miles have been constructed since 1970, or 22%.
The City of Kent is located in two characteristically different
areas with relationship to topography and groundwater conditions;
the Green River Valley floor, and the uplands on each side which
fall fairly abruptly to the valley. The East Hill System and the
West Hill System already referred to are in the higher elevation
areas above the valley. These areas are well -drained and not
subject to any significant high groundwater conditions. Of the
total 84 miles of system, approximately 53 miles are located on the
East and West Hills. Of this 53 miles, approximately 16.5 miles
have been investigated under previous studies, or approximately
one-third. The remaining 31 miles of the total system are located
on the valley floor. Of this 31 miles, approximately 16 miles have
been investigated under the previous studies, or approximately 50%.
CONCLUSIONS
From the information developed in the studies summarized, it
was evident that the portions of the systems investigated on the -�
East and West Hill are free from excessive infiltration/inflow. As
noted, approximately one-third of East and West Hill systems were
investigated. These areas were studied in conjunction with construc-
tion projects and as such, could be considered randomly selected
since location, pipe condition or groundwater conditions were not
factors involved in their selection. Since virtually all of the
systems located on the East and West Hills are above 150 feet
M.
elevation, were installed within the past 20 years for the most
part, and are subject to similar groundwater conditions, it is
concluded that the portions studied are representative of the entire
higher level systems and not subject to.excessive infiltration or
inflow.
This conclusion is further substantiated by inteviews with
Sewer Department personnel. A large amount of the East and West
Hill Systems have been televised with no indication of infiltration
conditions. Also, the Department conducts a thorough and continuous
,., inspection program which has revealed that the only areas where
infiltration/inflow conditions exist are in the old portion of the
" downtown system already investigated under previous studies. Also,
for the past ten years, the City has televised all new construction
prior to acceptance. As a part of their construction practices, all
pipe installed is fill tested for leakage prior to installation, and
the completed sewer is air tested prior to television and acceptance.
Since a substantial amount of the Hill systems were installed in
accordance with these procedures, the likelihood of leakage is
further minimized.
-- In the valley system, approximately 50% of the same 31 miles of
sewer pipe comprising the system have been investigated. The pipe
subject to infiltration and inflow has been noted under previous
studies. The portion of the system not covered under the previous
studies, approximately 15 miles, is located primarily in the valley
- northerly of S. 240th Street. Virtually all of this system has been
installed subsequent to 1967, and was installed utilizing construc-
tion methods previously noted. For the most part, this portion of
67
the system consists of larger diameter pipe (12" through 27").
Routine maintenance and inspection of the system by the Sewer
Department has not disclosed any evidence of infiltration or inflow.
Although the area is subject to high groundwater conditions, the -`
City Sewer Department Superintendent has stated that this system is
in very good condition and he has found nothing that would indicate
any significant amount of infiltration or inflow.
In summary, an assessment of the studies completed to date
indicates that the only areas subject to infiltration and inflow in
the entire Kent Sewage Collection System have been identified. A1 -
though the quantities of infiltration and inflow in the deteriorated
portions of the old system were found to be substantial, it was —
determined that it was not cost effective to correct the problem due
to the low cost of treatment by Metro. These findings were concurred
with by the agencies reviewing the studies.
Although rehabilitation and/or replacement was not found to be
cost effective, the City is proceeding with a program of replacement
in the problem area, and has replaced several thousand feet of old
pipe within the past few years. This is a continuing program, and
it is anticipated by the City that within the next few years, all of
the older pipe will be replaced under the improvement program.
CHAPTER 7
FORECASTS OF FLOWS AND WASTELOADS
Under the present agreement between the City of Kent and Metro,
charges for sewage treatment and related costs are based on the
number of single family residences served together with commercial
-- and industrial usage converted to residential equivalents on the
basis of 900 cu. ft. of water per month consumed equaling one
equivalent.
At the present time the City has 3,600 single family customers
and 8,733 residential equivalents for a total of 12,333 customers and
equivalents. Included in this number are multiple family residences.
Forecasts of flows and wasteloads result directly from -popula-
tion estimates and forecasts. Sewage flows on a per capita basis
are assumed to remain fairly constant at 900 cu. ft. per month per
single family residence.
Using 12,333 single family equivalents at an average flow rate
of 900 cu. ft. per month, the total flow would amount to 2.8 million
gallons per day (mgd).
The population of the study area as detailed in Chapter 6 in
this report is as follows:
Year
Population
1970
17,500
-- 1980
22,000
1990
30,000
2000
41,000
69
The above population data in themselves are not sufficient to
calculate the total sewerage flow from within the study area since
the population gives no indication of the flow resulting from commer-
cial, industrial, institutional and multi -family sources expressed
as equivalents. It may, however, be assumed that the growth in the
above sectors or sources will keep pace with the normal population --
growth. For projecting future flows, the same ratio between the
single family residences as a source of wastewater and the other
sources, namely industrial, commercial, institutional and multi-
family as another source of wastewater will be maintained constant
throughout the planning period.
Another source of difficulty in projecting future flows is that
the area presently served by the City of Kent does not include all
the study area. The City will no doubt continue to grow by annexing
areas adjacent to the City from within the study area. it is doubt-
ful that by the year 2000 the city limits will grow far enough to
include all the study area. An assumption, however, can be made
that half the area outside the city limits but within the planning
area will be within the City of Kent by the year 2000. The growth
is assumed to occur uniformly over the planning period.
The following calculations can be made for sewerage flows for
the years 1980, 1990 and 2000.
The rate of population growth which yields the figures shown in
the above table is 3.2% compounded annually.
The flow from 3,600 residences at 900 cu. ft. per month is equal
to 0.8 mgd. The industrial/commercial, etc., sources therefore
comprise 2.0 mgd of the 2.8 mgd total flow.
Ild
Projection of the 3,600 residences assumed to exist in December
1976 to 1980 at a rate of 3.2% yields 3,957 residences. Assuming a
single family residence contains 3.6 persons, the total number of
people would be 14,250. The population of the study area in 1980
will be 22,000. The population growth due to annexation is assumed
to be 8% of the difference, or 620 for a total of 14,870 which is
equivalent to 4,130 residences which will yield a flow of 0.93 mgd.
The industrial/commercial sector, keeping the same ration as 1976
will be 2.32 mgd for a total 3.25 mgd.
�.. In 1990 the number of single family residences at a 3.2% growth
rate will be 5,420, respresenting a population of 19,500. The total
population will, however, be 30,000. The increase in population due
to annexation will be 21%. (8% for the first 3 years and 21% for
the 10 years between 1980 and 1990, thus leaving 21% for the period
between 1990 and 2000 for a total of 50% growth by annexation). The
increase due to this element will be 2200 for a total population by
�- 1990 of 21,700. This figure is equivalent to 6028 residences,
yielding a flow of 1.36 mgd. The industrial/cv,Lu«eLt lay
W using the same ratio as 1976, will be 3.39 mgd for a total flow of
4.75 mgd.
In the year 2000 the number of single family residences at 3.2%
growth rate will be 7,430. The population this number represents is
26,750. Growth by annexation will be equivalent to 3,000 for a
total population of 29,750. This figure represents 8,264 residences
resulting in a flow of 1.86 mgd. The industrial/commercial section,
keeping the same ratio as 1976 will be 4.65 mgd for a total flow of
6.51 mgd.
71
The following table summarizes expected waste flows for the
years 1980, 1990 and 2000. —.
TABLE 11
PROJECTED WASTEWATER FLOWS
Residential Ind./Comm. Total
Year Flow mgd Flow mgd Flow mgd
1980 0.93 2.32 3.25 W
1990 1.36 3.39 4.75
2000 1.86 4.65 6.51
The flow for any of the intermediate years may be calculated
by interpolation.
72
CHAPTER 8
.r DEVELOPMENT AND EVALUATION OF ALTERNATIVE PLAN ELEMENTS
INTRODUCTION
Since the pattern of the City of Kent's existing collection
and interceptor system is basically established and implemented,
the development of a number of fundamental alternative plans is not
necessary. The various aspects of facilities planning will be
discussed as they pertain to the operation of the Kent system.
REGIONALIZATION
Within the planning area covered in this report, virtually all
of the area under study is naturally tributary to the Kent system.
The Star Lake area in the southwestern part of the study area could
be serviced by the Kent System or through the Lakehaven Sewer
District; however the manner of service to this area is simply a
matter of economy and timing and is not truly a regionalization
consideration.
The City of Kent system is a part of a regionalization plan
developed by Metro, and regionalization considerations have already
r. been developed and the system constructed, or in the process of
construction. While the full system for the region has not been
`r fully completed, the basic planning has been done and the ultimate
development of the City of Kent System will not affect the region-
alization plan already established.
73
WASTE MANAGEMENT
Since the flows from the Kent system are treated at Metro's
Renton Treatment Plant, waste management techniques are not a part
of this study. Any analysis of the treatment facility will be made
by Metro as the necessity arises.
FLOW REDUCTION
Observations of flows made during the infiltration/inflow
analysis for the Kent system showed that the major areas subject to
extraneous flows from storm and ground water were located in the
older portions of the downtown area. As previously mentioned, the
City is in the process of replacing these older lines, and antici-
pates that replacement will be basically complete within the next
few years. Good maintenance and repair practices will keep infil-
tration and inflow to a minimum in existing lines. The City's --
construction requirements are such that new construction is well
controlled and flow measurements from newer lines shows that
infiltration/inflow is not a problem.
SYSTEM EXTENSION AND ALTERNATIVES
For the most part, the service area of the City can be served
by gravity flow systems. Also the pattern of much of the inter-
ceptor and collection system has been established and the major _
lines constructed. In some of the unsewered areas, additional lift
stations may be required. -
74
From a study of the map showing the existing system of the
City and the service area, it is readily apparent that the un-
sewered areas are located around the periphery of the existing
system. These unsewered areas range in size from approximately 100
acres to several hundred acres and are tributary to different
portions of the existing system. For the most part, these areas
can be served by extending existing lines; one notable exception
being the area lying south of the Green River to S. 277th Street,
and extending from the Star Lake area east to the Green River. The
construction of the Auburn Interceptor makes it possible to serve
this area without pumping long distances into the existing City
system north of the Green River.
In order to determine line sizing and possible routing, these
... areas were considered on a case by case basis, and a method of
service developed. Some of the areas are relatively small and can
be served by an 811, 10" or 12" line. The actual location of lines
of this size can best be determined when plans for development are
known and feasible locations can be identified. Also projecting 8"
and 10" lines locations into an undeveloped area is of little value
until development patterns become somewhat established. Location
�- of larger trunk lines, where possible routes are limited by topog-
raphy and geogrpahical features, are more meaningful, and approximate
locations have been established.
-� In order to facilitate identification of areas under discussion,
they have been shaded on the proposed system map to show extent, and
lettered for identification purposes. These areas commence at the
northeast corner of the service area and progress clockwise, and
are shown in the map appended to this report.
.�
75
Area A
Area A covers approximately 160 acres. The natural slope of `
the ground, which is very slight is to the north. A single 15"
pipe on minimum slope would be sufficient to serve the area. An
existing 12" line extends northerly along the east margin of E.
Valley Highway and easterly for about 1000 feet, about 400 feet
south of S. 188th Street. Due to the length of the area, this line --
probably can serve only the southerly portion. An additional 12"
line will be needed to serve the remainder of the area and should be
routed across E. Valley Highway and extended northerly to the
existing 36" Metro line on S. 180th Street.
Cascade District has shown a need for a line in this general
vicinity to serve the area east of the Valley Freeway. This line is
shown in two segments one of which is to be constructed by Cascade W
Sewer District while the other to be constructed as a joint facility.
Area B
Area B covers approximately 110 acres. The existing 15"
crossing of E. Valley Highway at 192nd Street, and an 8" crossing
approximately 1320 feet south have adequate capacity to serve the
area. Until development is proposed, definite locations for interior
lines cannot be established since there are no interior roads. The
only natural obstacle will be the Springbrook Creek Crossing.
Area C
Area C covers approximate 110 acrs. A 10" and a 12" line
immediately east of and parallel with E. Valley Highway provide
service to the south half. There is an existing 12" on S. 200th
76
which has been extended across E. Valley Highway to serve the
northerly portion. here again, any attempt to show interior
collection or service lines across undeveloped property would be
.,, merely schematic and of little value in final planning.
Areas B-1 and C-1
The areas comprise approximately 80 acres total, extending in
a narrow strip one mile long along the east margin of the Valley
Freeway. Cascade Sewer District is proposing a trunk line in this
area. If development occurs, the most feasible method of service
— would be into the proposed Cascade trunk line. This would eliminate
at least two or more costly crossings of the Freeway.
Area D
Area D covers approximately 250 acres located between S. 218th
Street and S. 208th Street, and from 92nd Avenue South to the East
Valley Highway, together with an area located between 92nd Avenue S.
�-- and 100th Avenue S.E. and between 97th Place S. and S. 208th Street.
The area west of the Valley Freeway is tributary to existing lines
W
along E. Valley Highway, S. 208th Street and S. 218th Street. In
order to serve the area east of the Valley Freeway, through which
Garrison Creek flows, a crossing of the Valley Freeway will be
required. A 10" pipe would adequately serve east of the Freeway for
the balance of Area D.
Area E
Area E covers approximately 600 acres extending generally
from 92nd Avenue S. to 108th Avenue S. and from S. 224th Street to
S. 208th Street. This area, for the most part is tributary to the
77
Garrison Creek Interceptor at S. 218th Street and 93rd Avenue S.,
the most westerly and northwesterly portion would be tributary to
the proposed crossing of the Valley Freeway in Area D.
A proposed collection system has been layed out for Area E
which will provide service for the now existing development. If -�
new streets are platted prior to actual installation, changes will
undoubtedly occur. Under the proposed system, the area can be
served for the most part by 8" lines, with some 10".
Area F
Area F consists of approximately 300 acres. This area is
tributary to the 100 Avenue S. Interceptor and to the Garrison --
Creek Interceptor. Sufficient routes are available to allow this
area to be served by 8" lines.
Area G
Area G consists of approximately 1000 acres tributary to the
Mill Creek Interceptor and extends generally from S. 248th Street
to S. 277th Street, and from 104th Avenue S. to 116th Avenue S.
The collection system for this area consists primarily of 8" pipe,
with some 10" to 15" in the area approaching the beginning of the
Mill Creek Interceptor. One lift station is proposed to serve
approximately 100 acres in the southwest corner of the service
area. This lift station could be eliminated if a suitable route _
along easements or future streets could be obtained to Woodland Way
along the southwesterly side at the Mill Creek drainage way.
FV]
Area H
Area H covers aproximately 1200 acres extending from approxi-
mately S.E. 248th Street to S.E. 277th Street and from 116th Avenue
S.E. to 132nd Avenue S.E. A small area lies east of 132nd Avenue
S.E. in the vicinity of S.E. 272nd Street.
The total area is naturally tributary to the Soos Creek
drainage basin; however, it appears at this time that it will be
many years before the Soos Creek Interceptor will be constructed
-- southwesterly into the Auburn Interceptor. In the meantime, any
sewered development in the area can flow by gravity to an existing
pump station located southwesterly of the intersection of 132nd
Avenue S.E. and S.E. 272nd Street.
Area I
Area I consists of approximately 2000 acres in the Valley
floor from the Green River south to S. 277th Street. of this
amount, approximately 700 acres are within the city limits of Kent.
This total area has very poor drainage for the most part. The area
within the County is zoned for agricultural purposes, and may
remain in this classification. However, if development occurs, a
system of serving the area has been developed which will not
require pumping. The proposed system has been predicated on the
assumption that if development occurs, substantial fill will be
necessary in the very low areas to obtain surface drainage and thus
would provide sufficient cover over the piping system. Because of
the minimum slopes which must be maintained, slow development with
low flows could result in the necessity for frequent cleaning until
-- adequate flows are accumulated.
79
Area J (Lake Fenwick Area)
Area J covers approximately 225 acres including the surface
area of Lake Fenwick. Much of the area surrounding the Lake is too
steep to permit building. Approximately 100 acres could possibly
be developed if sewer service were provided. The natural drainage
pattern is southeasterly from the south end of the Lake. If the
valley floor to the east and south develops, the valley system
would provide a route to the Auburn Interceptor. if this does not
occur, the most economical method of discharge would be through a
tight line to the Auburn Interceptor. A six inch line would be
adequate to serve the area. A careful analysis will be needed to -'
determine if potential customers would provide adequate flow to
maintain sufficient velocity.
Star Lake Area
While the Star Lake area is mostly within the Lakehaven Sewer
District, gravity service could be provided by routing the trunk to
serve the area into the Auburn Interceptor. The City of Kent was
requested by the Department of Ecology to Study the Star Lake area
as a part of this plan. --
It can be assumed that the basic collection system required
for the area would remain unchanged for the most part regardless of
the disposition of the sewage after collection and that significant
items for comparison would be in the cost of installing pumping
facilities and force mains versus the cost of serving by a gravity r
system. This comparison must be made on the basis of providing
ultimate service. The following comparison is made on the basis of
the facilities that would be needed under service to the Lakehaven
Sewer District as opposed to service to the Auburn Interceptor.
AN
TABLE 12
COST ESTIMATES FOR STAR LAKE AREA SERVICE ALTERNATIVES
1. Collection System
a. Cost difference of 2400'
of 18" pipe for pumping
system versus 12" for
gravity system ( see plan)
b. Cost difference of 2000'
of 15" pipe for pumping
systems versus 10" for
gravity system (see plan)
2. Pump Station
3. Force main 10"
4. 10, 000' of 10" gravity
trunk line
4.a 10, 000' of tight line
5. 5,000' of 12' tight line
across valley to Auburn
Interceptor
Pumping
Tight
Station Gravity
Line
(Lakehaven (Auburn
(Auburn
S. D. Interceptor)
Interceptor)
$17,000 0
$26,000 0
*273,000 0
*87,000 0
450,000 180,000
115,000 115,000
6. Boring under Valley 20,000 20,000
Freeway
-403,000 585,000 315,000
*From Star Lake Facilities Plan - Lakehaven Sewer District - Hart, Williams, and Roth
The above table shows that the least costly method of serving
the Star Lake area is the construction of 10" and 12" tight lines to
the Auburn interceptor. This is followed by pumping to Lake Haven
Sewer District and finally a gravity line to the Auburn Interceptor
being the most expensive. Also, a brief analysis shows that energy
costs for the proposed pump station would be approximately $180,000
dollars over a fifty year period based on maximum density in twenty
years, and assuming present day energy costs.
81
Expansion of the valley system from the Auburn Interceptor could
change the initial construction costs; however, the greatest expense
is in the 10,000 feet of 10" line over steep terrain down to the
valley floor where significant development is not likely to occur.
Area K
This area consists of approximately 390 acres. The westerly
side is quite steep and a substantial portion would not appear
suitable for development. For the purpose of determining a design
flow, 300 acres of usable area was assumed. Area K does not have a
natural drainage outlet and during wet periods, water ponds in the
southeasterly portion. In order to provide service to Area K, a
pump station would be required, and a force main crossing of the
Green River.
Area L
Area L covers approximately 840 acres. Again much of the area
would appear to be unsuitable for development, particularly since
the City of Seattle operates a sanitary landfill on the hillside in
the west central portion, and much of the total area is steep. For
design purposes 500 acres has been assumed as usable. This area
can be made tributary to the existing line on S. 212th east of the
Green River by installing an inverted syphon across the river.
Area M
This area covers approximately 470 acres, most of which could
be developed. The natural flow is to the north and east. Assuming --
82
that this area will develope to some extent an. inverted syphon across
the Green River would be needed and a gravity line to the West Valley
Highway would be required. S. 196th St. would be the logical location
for the syphon and gravity line with sizing dependent on the extent
of development.
.. SUMMARY
Sewage flows from the City of Kent are treated at Metro's Renton
Treatment Plant. There is nothing at present that would indicate
°- any change in the foreseeable future. In view of this, no discussion
of treatment facilities is included in this plan.
The primary focus of this study is the system extensions that
will be required to provide service within the boundaries of the nat-
ural service areas of the City. The general nature of the unsewered
areas and the existing system available to serve these areas have
been discussed in the preceeding portion of this chapter, on an area
by area basis. A system of new facilities has been developed and is
shown on the map appended to this report. The proposed system is
quite detailed in the areas where sufficient development has occurred
to establish street patterns. In the areas which are largely
., undeveloped, only major lines are shown, and in some cases are
somewhat schematic in nature.
From the standpoint of alternatives to the system shown, there
- is nothing significant which can be presented which would provide
the City with meaningful choices. Obviously, minor alternatives in
routing may be desirable as development occurs and street patterns
emerge. Also, there is no specific timetable for construction of
the proposed system. Installation of sewers will occur along with
-- development, or where failure of existing septic tank systems
becomes a significant problem and action is required.
83
CHAPTER 9
-' PUBLIC PARTICIPATION AND AGENCY COORDINATION
A public hearing is scheduled to be held on June 6, 1977 at
8:00 P.M. in the Council Chambers of the City of Kent. Testimony
will be received from the public regarding any of the contents of
this Facilities Plan. Furthermore, this plan is being forwarded to
a number of local, state and .federal agencies who may have interest
or jurisdiction over the provisions of this plan. Their comments
along with any of the citizens' comments will be addressed and
included in the final facilities plan which is scheduled to be
issued on July 8, 1977.
This draft facilities plan has been sent for review and
comment to the following agencies.
Clifford V. Smith, Jr.
Regional Administrator
Environmental Protection Agency
1200 Sixth Avenue
Seattle, Washington 98101
Director
Washington Department of Game
600 North Capitol Way
Olympia, Washington 98501
Director
Washington Department of Fisheries
Room 115, Central Administration
Building
Olympia, Washington 98501
" King County
Division of Land Use Management
King County Courthouse
_. Seattle, Washington 98104
Seattle -King County Health Service
Southwest District Office
10821 - 8th Southwest
Seattle, Washington 98146
E3]
King County
Public Works Department
King County Administration
Building
Seattle, Washington 98104
Des Moines City Manager
21630 - 11th South
Des Moines, Washington 98188
Governmental Services
Puget Sound Council of
Governments
216 First Avenue South
Seattle, Washington 98104
U.S. Army Engr. District -
Seattle
Col. Raymond J. Eineigi
4735 East Marginal Way South
Seattle, Washington 98134
Washington Department of
Ecology
4350 - 150th N.E.
Redmond, Washington 98052
Mr. Al Koch, P.E.
Washington Department of Social
and Health Services
Sanitary Engineering Division
1312 Smith Tower
Seattle, Washington 98104
Office of Archaeology and
Historic Preservation
Box 1128
Olympia, Washington 98504
METRO
600 1st Avenue
Seattle, Washington 98101
Director of Public Works
City of Renton
200 Mill Avenue South
Renton, Washington 98055
Director of Public Works
City of Tukwila
14475 59th Avenue South
Tukwila, Washington 98168
99
Director of Public Works
City of Auburn
20 "A" Street N.W.
Auburn, Washington 98002
Director of Public Works
City of Des Moines
216 - 11th Avenue South
Des Moines, Washington 98188
District Manager
Lakehaven Sewer District
P.O. Box 3046
30459 S. Military Road
Federal Way, Washington 98003
District Manager
Cascade Sewer District
10828 S.E. 176th
Renton, Washington 98055
District Manager
Des Moines Sewer District
P.O. Box 98704
Des Moines, Washington 98188
CHAPTER 10
ENVIRONMENTAL IMPACT ASSESSMENT - A SUMMARY
INTRODUCTION
The Environmental Impact Assessment is an integral part of a
facilities plan. As a result, portions of it will be found through-
out the document. In this particular plan, various segments of the
Environmental Impact Assessment are presented in Chapters 4, 8 and
9. The purpose of this Chapter will be to evaluate the impact of
the Proposed Action and to identify where in the document can be
found key information for addressing the eight major question areas
identified by the guidelines (References 1, 2). These question
areas are as follows.
DESCRIPTION OF THE PROPOSED ACTION
The reader is referred to Chapter 8 for the description of the
alternative plan elements and service areas. For ease of reference,
approximate boundaries of the proposed service areas are shown in
Figure 6.
ALTERNATIVES TO THE PROPOSED ACTION
The selected plan described in Chapter 8 divides the proposed
service areas shown in Figure 6 into several sub -basins. Sewers may
ultimately be constructed in any one of these areas, or in any
-- combination of these areas. Within each drainage area, different
configurations of lines could serve each area depending upon how
they develop.
ENVIRONMENTAL IMPACT OF THE PROPOSED ACTION
The environmental impacts of the Proposed Action and the no
... action alternative are evaluated below. Where appropriate, impacts
of servicing individual sub -drainage areas are specified. Within
any given service area, the environmental impact varies insignifi-
cantly with the configuration of collection system. The impact
assessment is based on information presented in Chapters 4 and 8,
particularly the land use trends, policies aimed at preservation of
agricultural' lands in unincorporated King County, and population
-- projections.
Table 13 lists all potential areas of impact that were evaluated
for each alternative. Only those areas expected to experience
significant impact are discussed. These potential impact areas may
be divided into several general categories as follows:
o Physical
4- o Biological
o Social
W.Y. .
o Economic
o Construction
Within each of these divisions, impacts may be termed "primary"
and "secondary". These terms are defined by the EPA as follows
W✓
(Reference 3):
Primary - ."those (effects) directly related to construction
and operation of the project.
MK
TABLE 13
POTENTIAL AREAS OF ENVIRONMENTAL IMPACT
PHYSICAL
Resource Utilization
Energy Consumption
Air Quality
Noise
Groundwater Quality
Other Water Quality
Solid Waste
BIOLOGICAL
Terrestrial Biota:
Flora
Fauna, Mammals
Fauna, Other Forms
Aquatic Biota: Fish
Avian Biota: Terrestrial
Unique and Endangered Species or habitats
Total Ecosystem Stability
SOCIAL
Aesthetics _
Health
Safety
Odor
Insect Pests
Archaeological/Historical/Cultural
Recreational Opportunities
Open Space
Traffic
Compatibility with Existing Land Use
Compatibility with Planned Future Land Use
Population Size/Density
Potential for Population Growth
ECONOMIC/FISCAL
Employment
Tax Base
Tax Rate/User Charges --
Property Values
Housing
Municipal Service Costs/Public Debt ..�
Demand for Public Services
Economic Activity
CONSTRUCTION FACTORS
General Interference
Biota Distruption:
Terrestrial
Aquatic
Water Quality
Economic Activity
Resource Use/Energy Use
89
Secondary - "indirect or induced changes in population, and
�- economic and land use; and other environmental
effects resulting from these changes in land use,
population, and economic growth.
Physical Impacts
�. The proposed action would impact the physical environment by
requiring use of material resources for pipes and pump stations,
where required (see Chapter 8); operation of pumping stations
would consume energy. The water quality of Star Lake and Lake
W Fenwick might improve if a sewerage system is constructed in their
respective areas as described in Chapter 8. Bacterial contamination
of Star Lake would probably decrease. Extensive development around
. these lakes would probably not be permitted without sewer collection
systems; hence, the impact of taking no action on water quality
would probably be minimal. Much of the area within Kent for which
sewer service is proposed is zoned industrial; industrial development
could not take place without sewer service. Such development might
cause further degradation of air quality by increasing vehicular
traffic and by direct emissions. Increased traffic might also raise
-� noise levels.
Neither resource use nor energy consumption would increase if
no action is taken, nor would air quality be affected.
Biological Impacts
The main impact of the proposed action on the biological
environment would be loss of habitat due to development stimulated
W
or made possible by provision of sewer service. (Such development
.E
would be consistent with current zoning.) Further residential
development would reduce habitats available for the terrestrial
biota in the wooded areas around Star Lake, Lake Fenwick, and
Garrison Creek; however, development of the latter two areas would
probably be limited by the steep slopes. Low-lying areas contain-
ing ponded water and cattail marshes would be eliminated by planned
industrial development, reducing habitat for waterfowl and other
aquatic fauna. Such habitat is now found in proposed service areas
along E. Valley Highway, and south and west of the Green River; much
of this land is used for agriculture.
Social Impacts
Provision of sewer service would probably encourage population
growth and industrial or residential development in at least some of
the proposed service areas, since much of'the area is unsuited to
use of septic tanks because of soil type and seasonal high water
table. Provision of sewer service to Star Lake and Lake Fenwick
would probably encourage residential development in these areas. In
contrast, industrial development in the City of Kent will probably
be influenced to a far greater degree by economic factors than by
availability of sewer service.
Development stimulated by the availability of a sewer service
would have an impact on the social environment. Local population
growth and industrial development would increase the traffic loads
on existing roadways and demand for public services such as schools,
fire and police protection, water supply, and power. Since much of "
the anticipated growth is industrial rather than residential,
secondary impacts would include need for additional housing to the
31
extent that the industrial development creates more jobs than can be
filled from the local labor market. Loss of agricultural land (in
areas I, L, and M) would be inconsistent with King County Agricul-
tural Policy. In addition, development will continue to reduce open
space and accelerate the change in the aesthetic character of the
impacted areas. No archaeological or historic resources would be
affected (Reference 4).
The no action alternative would avoid the impacts discussed
above.
Economic Impacts
-- Construction of sewers would place an economic burden on
present residents in the areas to be served, requiring them to pay
assessments and monthly service charges; increase property values
in areas where residential or industrial development is thereby
made more attractive; increase the property tax base; and increase
demand for public services to the extent that development in
presently undeveloped and unsewered areas is induced. Increases in
revenue to local government would probably exceed costs of additional_
services, especially in Kent, where most of the new development
would be industrial. Extension of service to any of the areas
proposed above would require action by the local property owners to
initiate a service request.
.- All of these impacts would be avoided under the no action
alternative.
01
Construction Impacts
Implementation of the proposed plan would entail several
short-term impacts during construction. These would include --
typical nuisances - noise, dust, traffic hindrance, vehicle emis-
sions, consumption of fossil fuels. Additional impacts would occur
during construction along the lake shores and across the Green
River (areas K, L, and M). Impacts of laying sewers in the river
bed and in the littoral zone of lakes include increased sedimenta- _
tion and turbidity, distruption of littoral and benthic biota,
possible disruption of anadromous fish; appropriate timing and
methods should minimize these impacts, particularly those affecting
the fish. Temporary disruption of agriculture is another probable
impact dependent on timing of construction activity., Construction
of lines to serve some areas (e.g. Garrison Creek, Lake Fenwick,
Star Lake) would require removal of vegetation in heavily wooded
areas with steep slopes, resulting in erosion unless appropriate
measures are taken.
ADVERSE IMPACTS AND MITIGATING MEASURES
Adverse impacts of the proposed action include increased
energy consumption, some loss of habitat for terrestrial flora and
fauna, construction nuisances, increased costs for local residents,
and disruption of aquatic habitats where the lines cross the Green
River and where service to lakeside homes can only be provided by
placing the sewer in the lake itself. Secondary adverse impacts
include degradation of air quality, increases in loads on roads and
public services, possible loss of agricultural land and open space.
93
Implementation of the following measures would mitigate some
of those impacts.
1. All appropriate measures, such as timing of construction
activities to create minimal disturbance, or special
design, should be used to minimize construction inter-
ference. This is particularly important with respect to
river crossing and construction in the littoral zone of
the lakes.
2. Appropriate action by local governments may prevent loss
of agricultural land to development. Sewer lines passing
through agricultural land should be sized and constructed
so that connection is not possible.
3. Adequate planning by local agencies and governments may
minimize secondary impacts of increased growth.
UNAVOIDABLE ADVERSE IMPACTS
The following impacts cannot be entirely avoided:
1. Typical nuisances associated with construction will
occur: noise, dust, traffic hindrance, vehicle emis-
sions.
2. A financial burden will be placed upon local residents to
construct, operate, and maintain the sewage collection
systems.
94
LOCAL SHORT-TERM USES VERSUS LONG-TERM PRODUCTIVITY
The direct elimination of natural habitat will be limited to
the small amount of land removed from its present use at those pump �-
stations where flooding requires above ground construction; there-
fore, local short-term uses will be limited to those sites upon W
which surface facilities will be built, along with the natural
resources and materials associated with operation and maintenance
of the proposed facilities.
Removal of prime agricultural land in King County from agri-
cultural use should also be considered here, even though it is a
secondary effect.
Those agricultural lands within the City of Kent are zoned for
residential or industrial use and will presumably be lost to
residential or industrial use if the proposed action is imple-
mented; larger areas of agricultural land within King County that
the county wishes to preserve as agricultural land may be lost if
sewer connections are permitted and zoning is altered.
Thus, implementation of the proposed action in areas including
prime agricultural land would favor short-term use rather than
long-term productivity. In the non-agricultural sections, the
long-term productivity of the lands would be minimally affected by
the proposed short-term uses.
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IRREVERSIBLE AND IRRETRIEVABLE COMMITMENT OF RESOURCES
..r
The following commitment of resources will be made.
1. The economic resources used to construct, operate, and
maintain the facilities.
2. The material resources used to construct, operate, and
maintain the facilities.
3. Loss of King County agricultural land to residential and
industrial development, to the extent that those areas
are sewered, if provision of sewer service is permitted.
4. The land upon which above -grade pump station facilities
are placed.
..� PUBLIC INVOLVEMENT
The reader is referred to Chapter 9 for the summary of public
involvement that has and will occur regarding the proposed facilities.
96
REFERENCES
1.
U.S. Environmental Protection
Agency, "Manual for Preparation
of Environmental Impact Statements for Wastewater Treatment
Works, Facilities Plans, and 208
Areawide Waste Treatment
Management Plans", July 1974.
2.
U.S. Environmental Protection
Agency, "Preparation of Environ-
mental Impact Statements", Code
of Federal Regulations, Title
40, Chapter 1, Part 6, in the
Federal Register 17 July 1974;
and Title 40, Chapter V, Part
1500 in the Federal Register y
August 1, 1974.
3.
U.S. Environmental Protection
Agency, "Memorandum to Regions -�
on Consideration of Secondary
Environmental Effects in the
Construction Grant Process, 6
June 1975.
4.
Welch, Jeanne M., State Historic
Preservation Office; personal
communication dated 3 February
1977.
97