HomeMy WebLinkAboutECF_Environmental_Checklist_180309_v1tQ King County
Department of Natural Resources and Parks • Wastewater Treatment Division
Environmental Services • 201 South Jackson Street, MS KSC-NR-0505
Seattle, WA 98104-3855
DETERMINATION OF NONSIGNIFICANCE
TITLE OF PROPOSAL: South Plant Biogas and Heating Systems Improvements
DESCRIPTION OF PROPOSAL: The King County Wastewater Treatment Division (KCWTD) proposes to replace the existing biogas
upgrading system (BUS) and heating systems at KCWTD's South Treatment Plant (STP) in Renton, WA. The project will improve the
plant's ability to produce biomethane gas, which can be used as fuel, from the wastewater treatment process. The project will also improve
the plant's heating systems to mot'e reliably meet process and space heating demands. The project includes construction of the Heat and
Energy Recovery Building (HERB), a new thermal oxidizer, heating system improvements within the existing Digester Equipment
Building, stormwater management facilities, and utility connections. Project construction is scheduled to begin in mid-2019, and the new
biogas and heating system is scheduled to be operational by the end of 2021.
LOCATION OF PROPOSAL, INCLUDING STREET ADDRESS, IF ANY: The proposed project is located in Renton W A, at 1200
Monster Road SW. The project will occupy King County Parcel Numbers 2423049097 and 2423049006, which are located in NE Quarter-
Section, Section 24, Township 23 North, Range 9 East.
SEP A Responsible Official:
Position/Title:
Address:
Proponent and Lead Agency:
Contact Person:
Issue Date:
Mark Isaacson
Director, King County Wastewater Treatment Division
King County ID1epartment ofNatural Resources and Parks
Wastewater TUatment Division
Jacob Sheppard, Water Quality Planner
King County Wastewater Treatment Division
201 South Jackson Street, MS KSC-NR-0505
Seattle, WA 98104
phone: (206) 477-5395; e-mail: jacob.sheppard@kiligcounty.gov
March 9, 2018
The State Environmental Policy Act (SEP A) lead agency for this proposal has determined that it does not have a probable significant
adverse impact on the environment. An environmental impact statement is not required under RCW 43.21C.030(2)(c). This decision was
made after review of a completed enviromnental checklist, the environmental reports listed in Section A.8 of the environmental checklist,
and other information on file with the lead agency. This infmmation is available to the public on request.
[g) This Determination ofNonsignificance (DNS) is issued under WAC 197-11-340 (2); the lead agency will not act on this proposal for
14 days from the issue date. Comments must be submitted by March 23, 2018. Submit comments to Katherine Fischer, Supervisor,
Environmental Services, King County Wastewater Treatment Division, 201 South Jackson Street, MS KSC-NR-0505, Seattle, WA 98104-
3855. Contact Jacob Sheppard, Water Quality Planner, at (206) 477-5395 or jacob.sheppard@kingcounty.gov for questions or information
on how to submit comments electronically.
[g) The King County Wastewater Treatment Division recently submitted a conditional use permit application for this project to the City of
Renton. Therefore, there is no administrative appeal of this DNS pursuant to RCW 43.21 C.075, WAC 197-11-680, KCC 20.44.120, and
King County Public Rule 7-4-1. The public rule may be viewed at http://www.kingcounty.gov/about/policies/rules/utilities/put741pr.aspx
or contact Jacob Sheppard, Water Quality Plam1er, at (206) 477-5395 or jacob.sheppard@kingcounty.gov to obtain a copy of the rule.
[Statutory authority: RCW 43.21 C.llO. 84-05-020 (Order DE 83-39), § 197-11-970, filed 2/10/84, effective 4/4/84.]
Department of Natural Resources and Parks
Wastewater Treatment Division
King Street Center, KSC-NR-0505
201 South Jackson Street
Seattle, WA 98104
Environmental Checklist
for
South Plant Biogas and Heating Systems Improvements
February 9, 2018
Prepared in compliance with the State Environmental Policy Act (SEPA)
(RCW 43.21C), the SEPA Rules (WAC 197-11), and Chapter 20.44 King
County Code, implementing SEPA in King County procedures.
This information is available in accessible formats upon request at
(206) 477-5371 (voice) or 711 (TTY).
ENVIRONMENTAL CHECKLIST
A. BACKGROUND
1. Name of proposed project, if applicable:
South Plant Biogas and Heating Systems Improvements
2. Name of applicant:
King County Department of Natural Resources and Parks
Wastewater Treatment Division
3. Address and phone number of applicant and contact person:
King County Department of Natural Resources and Parks
Wastewater Treatment Division
Environmental Services Unit
KSC-NR-0505
201 S. Jackson Street
Seattle, WA 98104
CONTACT: Jacob Sheppard, Environmental Planner
Phone: (206) 477-5395
Email: jacob.sheppard@kingcounty.gov
4. Date checklist prepared:
February 9, 2018
5. Agency requesting checklist:
King County Department of Natural Resources and Parks
Wastewater Treatment Division
6. Proposed timing or schedule (including phasing, if applicable):
Project construction is scheduled to begin in mid-2019. The new biogas and heating
system is scheduled to be operational by the end of 2021. A minor element of the
project, the installation of a third heating boiler, will occur in a future construction
contract with a schedule yet to be determined.
7. Do you have any plans for future additions, expansions, or further activity
related to or connected with this proposal? If yes, explain.
No
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SEPA Environmental Checklist South Plant Biogas and Heating Systems Improvements
8. List any environmental information you know about that has been prepared, or
will be prepared, directly related to this proposal.
Brown and Caldwell. South Plant Biogas and Heat Systems Improvements Project
Trip Generation Memo. November, 2017.
Brown and Caldwell. Phase I Environmental Site Assessment. March, 2017.
Davido Consulting Group. Technical Information Report (Full Drainage Review).
King County South Treatment Plant – Biogas and Heat Systems Improvements.
January, 2018.
Environmental Science Associates. South Treatment Plant Biogas and Heat Systems
Improvements Project: Wetland Assessment Report. January, 2018.
Environmental Science Associates. Cultural Resources Background Investigation.
March, 2017.
Russell and Lambert. Tree Report: King County South Treatment Plant Biogas and
Heat Systems Improvements. December, 2017.
Shannon and Wilson, Inc. Revised Geotechnical Report, King County South
Treatment Plant Biogas and Heat Systems Improvements, Renton, Washington.
January, 2017.
Shannon and Wilson, Inc. Addendum to Geotechnical Report, King County South
Treatment Plant Biogas and Heat Systems Improvements, Renton, Washington.
March, 2017.
Shannon and Wilson, Inc. Geotechnical Report Addendum, Biogas and Heat Systems
Improvements Projects, King County South Treatment Plant, Renton, Washington.
December, 2017.
9. Do you know whether applications are pending for governmental approvals of
other proposals directly affecting the property covered by your proposal? If yes,
explain.
None known
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10. List any government approvals or permits that will be needed for your proposal,
if known.
City of Renton
• Land Use Permits, including:
o Conditional Use Permit
o Site Plan Review
o Critical Areas Review
o Street Frontage Improvements Waiver
o Shoreline Exemption
• Building Permits, including:
o Building Permit
o Civil Construction Permit
o Drainage Review and Approval
Puget Sound Clear Air Agency (PSCAA)
• Notice of Construction
Washington Department of Ecology (Ecology)
• National Pollutant Discharge Elimination System (NPDES) Construction
Stormwater General Permit
11. Give brief, complete description of your proposal, including the proposed uses
and the size of the project and site. There are several questions later in this
checklist that ask you to describe certain aspects of your proposal. You do not
need to repeat those answers on this page.
King County proposes to replace the existing biogas upgrading system (BUS) and
heating systems at King County Wastewater Treatment Division’s South Treatment
Plant (STP) in Renton, WA. The project will improve the plant’s ability to produce
biomethane gas, which can be used as fuel, from the wastewater treatment process.
The project will also improve the plant’s heating systems to more reliably meet
process and space heating demands. The project includes construction of the Heat and
Energy Recovery Building (HERB), a new thermal oxidizer, heating system
improvements within the existing Digester Equipment Building, stormwater
management facilities, and utility connections. Each of these project elements are
described in further detail below.
Heat and Energy Recovery Building (HERB). The project includes the construction
of a new building west of the existing Solids Motor Control Center (MCC) Building,
in the northern part of the plant property, to house the BUS and new boilers for the
plant’s heating system. The approximately 9,782 square foot building will be located
within an unused area, previously designated for plant expansion, currently comprised
of lawn overtopping a mound formed by previously-placed construction fill. The site
slopes gradually to the east towards the existing Solids MCC Building and is
maintained as lawn grass over the mounded spoils. Previously placed spoils will be
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removed and the existing slope will be re-graded as part of building construction. The
building will be primarily reinforced concrete, with an architectural finish similar to
existing buildings at the plant. Spaces in the HERB will include gas compression
rooms, a boiler room, a control room, an electrical room, a bathroom, a gas analyzer
room, and space for heating, ventilation, and air conditioning (HVAC) equipment. The
County currently plans to install two new boilers in the HERB in the initial
construction contract for this project, and one additional boiler in the HERB in a future
contract. Some equipment will be located outside, along the west exterior of the
HERB. The new facility will include up to 10 parking stalls on the north side of the
building.
Existing utility tunnels that run under the nearby Digester Equipment Building will be
extended to provide utilities to the new building. New low pressure sludge gas (LSG),
waste gas, and high-pressure sludge gas (HSSG) pipes will be routed underground
along the plant’s driveway (Road N) between the existing waste gas burners and the
current BUS. All utilities in the road will be installed using open-cut construction
methods. New electrical equipment will be installed in the Solids MCC Building and
the new building.
Thermal Oxidizer. The project will include installation of new thermal oxidizer
equipment located outside on a new concrete pad (approximately 2,437 square feet)
immediately south of the existing waste gas burners. The thermal oxidizer will
combust waste gas from the BUS. The primary feature of the thermal oxidizer is an
elevated stack alongside a horizontal oxidation chamber.
Other Heating System Improvements. New effluent-source heat pumps (referred to as
heat extractors [HXTs]) will replace the plant’s existing HXTs and will be located in
the lower floor of the existing Digester Equipment Building. Heating system upgrades
will not require construction outside of the building. Heating system improvements
will include the replacement of existing hot water and effluent water pumps.
The existing BUS, HXTs, and hot water boiler will be removed as part of the project.
See Figure 2 for a site plan of the project.
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12. Location of the proposal. Give sufficient information for a person to understand
the precise location of your proposed project, including a street address, if any,
and section, township, and range, if known. If a proposal would occur over a
range of area, provide the range or boundaries of the site(s). Provide a legal
description, site plan, vicinity map, and topographic map, if reasonably available.
While you should submit any plans required by the agency, you are not required
to duplicate maps or detailed plans submitted with any permit applications
related to this checklist.
The proposed project is located in Renton WA, at 1200 Monster Road SW. The
project will occupy King County Parcel Numbers 2423049097 and 2423049006,
which are located in NE Quarter-Section, Section 24, Township 23 North, Range 9
East.
See Figure 1 for a vicinity map of the project.
B. ENVIRONMENTAL ELEMENTS
1. Earth
a. General description of the site
(circle one): Flat, rolling, hilly, steep slopes, mountainous, other __________.
b. What is the steepest slope on the site? (approximate percent slope)?
The steepest slopes on the site are approximately 25%.
c. What general types of soils are found on the site? (for example, clay, sand,
gravel, peat, muck)? If you know the classification of agricultural soils,
specify them and note any agricultural land of long-term commercial
significance and whether the proposal results in removing any of these soils.
In general, the site overlies previous fill consisting of silty sand with gravel to a
depth of approximately 25 feet. The fill layer is underlain by native sand, silt,
and gravel to a depth of approximately 80 feet.
Neither the project site nor its surroundings contain agricultural land of long-
term commercial significance.
d. Are there surface indications or history of unstable soils in the immediate
vicinity? If so, describe.
No.
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e. Describe the purpose, type, total area, and approximate quantities and total
affected area of any filling, excavation, and grading proposed. Indicate
source of fill.
Approximately 2.4 acres of the approximately 50-acre STP property will be cut
and graded in order to re-grade the existing slope at the new building site, install
the concrete foundation for the building, pave the exterior equipment areas
adjacent to the building, install the concrete pad for the thermal oxidizer, and
create storm water treatment and detention facilities. In addition, trenches will
be cut and filled in order to install utility lines on the site.
Approximately 17,000 cubic yards of soil will be excavated, all of which will be
used onsite. The spoils will be placed on an approximately one-acre area south
of the digesters located within an open lawn area in the center of the STP
property. Spoils will be compacted and seeded to match existing grades and
vegetation type.
For all excavation activities, subsequent backfill will consist of native soil to the
greatest extent possible, supplemented by clean fill when required by permit
conditions or engineering specifications.
f. Could erosion occur as a result of clearing, construction, or use? If so,
generally describe.
Some localized erosion could occur during clearing and construction. However,
erosion control measures will be used to minimize the potential for this to occur.
See Section B.1.h below for typical Best Management Practices (BMPs) and
other measures that could be utilized to minimize the potential for erosion.
Erosion is not expected to occur as a result of the completed facility.
g. About what percent of the site will be covered with impervious surfaces
after project construction (for example, asphalt or buildings)?
Approximately 4% of the project’s 2.4-acre area of disturbance is covered with
impervious surfaces. After project construction, approximately 18% of the site
will be covered with impervious surfaces, including approximately 0.22 acre of
buildings and approximately 1.29 acres of new and replaced concrete and
asphalt surfaces.
h. Proposed measures to reduce or control erosion, or other impacts to the
earth, if any:
Temporary erosion and sedimentation control measures will be employed
throughout project construction, including prior to all clearing, excavation,
filling, grading, and other soil-disturbing activities in the project area. These
control measures will be identified in the project plans and construction
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specifications and will be implemented as required by the City of Renton,
Ecology, and other permitting agencies.
Typical measures that may be used include installing filter fabric fences and
other sediment barriers, placing silt traps in storm drain inlets, covering soil
stockpiles and exposed soils, and using settling facilities to prevent sediment
from leaving the site.
Additional best management practices (BMPs) and other measures could include
the following:
• Designation of personnel to inspect and maintain temporary erosion and
sediment control measures
• Use of appropriate means such as stabilized entrances and wheel washes
to minimize tracking of sediment onto roadways by construction vehicles
• Regular street cleaning for mud and dust control
• Disposing of excess excavated soil at an approved disposal site as soon as
practical
• Restoration of disturbed areas by repaving or replanting as soon as
practical after construction is completed
Spoils placed onsite will be compacted, seeded, and temporarily covered with
plastic or blankets where needed in order to prevent erosion.
2. Air
a. What types of emissions to the air would result from the proposal during
construction, operation, and maintenance when the project is completed? If
any, generally describe and give approximate quantities if known.
Project construction will involve temporary, mobile source air emissions (NOx,
VOC, CO, PM10, PM2.5), including diesel exhaust from construction equipment
and dust generated by earth-moving activities. The exhaust emissions will be
intermittent and spread across the project area. They are not expected to affect
attainment of air quality standards in the project area.
The BUS will convert biogas (a byproduct of the wastewater treatment process)
into pipeline-quality, renewable natural gas (biomethane) by separating the
carbon dioxide and other constituents from the methane in the biogas. This
process results in a waste gas stream (composed mostly of carbon dioxide) that
will be combusted in the thermal oxidizer. Combustion of the waste gas, as well
as the combustion of biogas to fuel the completed facility’s boilers, can result in
the conversion of certain compounds into air pollutants.
Air pollutants will be controlled through the use of hydrogen sulfide removal
systems and ultra-low NOx burners on the boilers. The thermal oxidizer will
result in a destruction removal efficiency of 99% of the methane in the waste gas
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stream. Destruction removal efficiency is the percentage that represents the
number of molecules of a compound removed or destroyed in an incinerator
relative to the number of molecules that entered the system.
The project will initially install two boilers. The County plans to install one
additional boiler at STP in a future contract. The expected air emissions from the
two new boilers and the thermal oxidizer, and the future state of three boilers
and thermal oxidizer, are as follows (using maximum values for the project’s
design year):
Air Emissions Emission Values
2 Boilers + Thermal Oxidizer 3 Boilers + Thermal Oxidizer
(future state)
Sulfur dioxide (SO2) 9.22 tpy 9.76 tpy
Nitrogen oxides (NOx) 2.21 tpy 2.61 tpy
Carbon monoxide (CO) 4.04 tpy 5.42 tpy
Dioxide (O2) 3% by volume wet 3% by volume wet
Notes: tpy = tons per year
The County is currently operating a gas-fired boiler at STP, which will be
decommissioned once the project is operational. Decommissioning this boiler
will eliminate the following emissions: SO2 (-0.95 tpy); NOx (-3.13 tpy); and
CO (-2.38 tpy). As a result, net emissions will be lower than those presented in
the table above.
A Notice of Construction (NOC) application will be submitted to PSCAA for
the project. The NOC application will demonstrate the use of best available
control technology (BACT) on the new equipment and project compliance with
the National Ambient Air Quality Standards (NAAQS) and any other applicable
state and local ambient air quality standards for these pollutants. Project
emissions are not expected to significantly impact air quality locally or
regionally.
See Attachment 1 for a King County Greenhouse Gas Emissions Worksheet
prepared for the project.
b. Are there any off-site sources of emissions or odor that may affect your
proposal? If so, generally describe.
There are no known off-site sources of air emissions or odors that may affect the
project.
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c. Proposed measures to reduce or control emissions or other impacts to air, if
any:
During construction, BMPs will be implemented to control dust. Types of BMPs
that will be used may include street sweeping, watering exposed soil surfaces,
and covering soil stockpiles to help minimize the amount of fugitive dust and
particulate pollution to the surrounding areas.
Construction equipment-related emissions will be reduced by requiring proper
maintenance of equipment, using electrically-powered equipment where
practical, and avoiding prolonged idling of vehicles and equipment.
To reduce or control emission during operation of the completed facility,
hydrogen sulfide removal systems, ultra-low NOx burners, and a thermal
oxidizer will be installed. Additionally, the completed facility will be set back a
sufficient distance from surrounding properties and public rights of way to make
detectable odors unlikely.
3. Water
a. Surface Water:
1) Is there any surface water body on or in the immediate vicinity of the
site (including year-round and seasonal streams, saltwater, lakes,
ponds, or wetlands)? If yes, describe type and provide names. If
appropriate, state what stream or river it flows into.
Springbrook Creek, a Type S water (shoreline of the state), is located east
of STP, approximately 450 feet from the proposed HERB, and
approximately 250 feet from the proposed spoils placement site. One
wetland (Wetland A), a 1,248 square-foot Category IV wetland, has been
identified in the immediate vicinity of the project. No other surface water
is present on or in the immediate vicinity of the site.
Waterworks Gardens, located north of the project site across an access
road, is a complex of connected wetponds and a Category II wetland that
provides stormwater detention and treatment for much of the STP
property.
2) Will the project require any work over, in, or adjacent to (within 200
feet) the described waters? If yes, please describe and attach available
plans.
The proposed project has been located and designed to avoid impacts to
wetland areas and associated buffers. The project site is effectively
disconnected from the offsite Waterworks Gardens wetland by a
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permanent road (Road “N”) and other developed surfaces. No impacts are
proposed to wetlands or wetland buffers as a result of this project. No fill
will be placed in wetlands or other waters of the U.S.
Spoils placement will require the construction of a temporary construction
entrance that will be within 200 feet of Springbrook Creek. The work will
not affect the creek.
3) Estimate the amount of fill and dredge material that would be placed
in or removed from surface water or wetlands and indicate the area of
the site that would be affected. Indicate the source of fill material.
No fill or dredge material will be placed in or removed from surface
waters or wetlands.
4) Will the proposal require surface water withdrawals or diversions?
Give general description, purpose, and approximate quantities if
known.
No.
5) Does the proposal lie within a 100-year floodplain? If so, note location
on the site plan.
A portion of the temporary construction entrance for spoils placement will
be within the 100-year floodplain (as shown in Figure 2). The construction
entrance will be removed and restored to previous grade at project
completion.
6) Does the proposal involve any discharges of waste materials to surface
waters? If so, describe the type of waste and anticipated volume of
discharge.
No.
b. Ground Water:
1) Will ground water be withdrawn, from a well for drinking water or
other purposes? If so, give a general description of the well, proposed
uses, and approximate quantities withdrawn from the well. Will water
be discharged to ground water? Give general description, purpose,
and approximate quantities if known.
Temporary dewatering of excavated areas may be required during
construction. If dewatering is required, the quantity of groundwater
withdrawn may vary widely depending on seasonal and local geological
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factors. Based on geotechnical information collected for this project and
other projects in the vicinity, the County does not anticipate that
substantial dewatering will be required.
No water will be discharged directly to groundwater as a result of the
project.
2) Describe waste material that will be discharged into the ground from
septic tanks or other sources, if any (for example: Domestic sewage;
industrial, containing the following chemicals...; agricultural; etc.).
Describe the general size of the system, the number of such systems,
the number of houses to be served (if applicable), or the number of
animals or humans the system(s) are expected to serve.
No waste material related to the project will be discharged into the ground
from septic tanks or other sources.
c. Water Runoff (including storm water):
1) Describe source of runoff (including storm water) and method of
collection and disposal, if any (include quantities, if known). Where
will this water flow? Will this water flow into other waters? If so,
describe.
At present, the surface water in the project area flows into STP’s
stormwater conveyance and treatment system, which includes multiple
biofiltration swales, catch basins, pipes, a large pump station, and a series
of wetponds and wetlands in Waterworks Gardens.
During construction, the primary source of water runoff onto and off of
work areas will be stormwater. Stormwater drainage patterns may be
altered during construction due to vegetation clearing and surface
compaction. Stormwater runoff during construction will be managed to
prevent runoff from leaving the site using storm water BMPs such as those
described below in Section B.3.d.
When the project is completed, stormwater will run off from the building
roof and other impervious areas such as pavement, and will be collected
and routed to a new detention vault before being discharged to STP’s
existing stormwater system. The existing stormwater system routes water
runoff to a series of wetponds and wetlands, where the water is cleaned
and returned to local waterbodies including Springbrook Creek.
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2) Could waste materials enter ground or surface waters? If so,
generally describe.
During construction, the County will implement BMPs to prevent
introduction of contaminants into ground and surface waters, which could
include:
• Storing fuels and other potential contaminants in secured
containment areas
• Containing equipment, materials, and wash water associated with
construction
• Conducting regular inspections, maintenance, and repairs of fuel
hoses, hydraulically operated equipment, lubrication equipment,
and chemical/petroleum storage containers
• Maintaining spill containment and clean up material at
construction sites
• Establishing a communication protocol for handling spills
After the facility is completed, runoff from new parking areas has the
potential to contain small amounts of motor oil, diesel fuel, hydraulic
fluid, or other materials typical of parking areas and roadways. The
completed facility’s stormwater management system, in combination with
STP’s existing stormwater system, will effectively prevent pollution from
entering local water bodies.
3) Does the proposal alter or otherwise affect drainage patterns in the
vicinity of the site? If so, describe.
Drainage patterns on the site itself will be altered from the addition of
impervious surfaces and conveyance of stormwater runoff. The completed
facility’s stormwater detention system will have sufficient capacity to
capture and restrict the rate of flow of stormwater into STP’s existing
stormwater system. As a result of STP’s on-site stormwater management,
the proposed project will not affect drainage patterns in the vicinity of the
site.
d. Proposed measures to reduce or control surface, ground, and runoff water,
and drainage pattern impacts, if any:
Stormwater management during and after construction will comply with all
applicable permits and government approvals, including requirements and
guidelines from the City of Renton, King County, and Ecology. In particular,
King County will meet performance standards included within the 2017 City of
Renton Surface Water Manual and City Amendments. Stormwater management
BMPs will be used during construction to control stormwater runoff. Examples
of typical BMPs that could be used during construction are presented in Section
B.1.h above.
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The completed facility will include a detention system that will capture
stormwater runoff from the parking and other pollution-generating surface areas
of the site.
4. Plants
a. Check or circle types of vegetation found on the site:
deciduous tree: alder , maple, aspen, other: ash, sweet gum, crabapple, pear,
cottonwood
evergreen tree: fir , cedar , pine, other : Norway spruce
shrubs: salal, Oregon grape
grass
pasture
crop or grain
orchards, vineyards, or other permanent crops
wet soil plants: cattail, buttercup , bulrush, skunk cabbage, other
water plants: water lily, eelgrass, milfoil, other types of vegetation
b. What kind and amount of vegetation will be removed or altered?
Approximately 2.4 acres of vegetated land will be cleared to build the proposed
facility. The majority of vegetation to be removed consists of maintained lawn.
Of the 180 assessed trees located near the project site, 28 trees with a diameter
at breast height (DBH) greater than six inches are proposed for removal. Of
these, 26 trees will be removed due to impacts of construction and two trees will
be removed due to the poor condition of the trees which makes their location
near the project a high risk. The City of Renton requires that approximately
10% of significant trees surveyed on the project site be retained. The project
proposes to retain 84% of the existing significant trees on site.
With the exception of the 9,782 square-foot area which will contain the
footprint of the new building, the 2,437 square-foot area which will contain the
footprint of the thermal oxidizer pad, and the 22,398 square feet of other new or
replaced concrete and asphalt surface areas for the building driveway, parking,
walkways, and concrete equipment pads, all vegetated areas throughout the
project will be replanted.
c. List threatened or endangered species known to be on or near the site.
There are no threatened or endangered plants known to be on or near the site.
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d. Proposed landscaping, use of native plants, or other measures to preserve
or enhance vegetation on the site, if any:
The proposed landscape design includes plantings adjacent to the new building
and new paved areas and in stormwater treatment and detention facilities. It
responds to grading of the eastern portion of the hill in the center of the project
site to provide a level area for the new building. The regraded hill will be
stabilized with a selection of drought-tolerant shrubs and groundcovers. Other
areas of disturbance will be restored with a grass and herbaceous plant seed mix
similar to the existing groundcover found on the site. Landscape plantings will
be a combination of native Pacific Northwest species and drought-resistant
ornamentals. Plants will be selected for adaptation to the different growing
conditions present across the project site, including shaded areas within and
adjacent to existing stands of mature trees, sunny areas within new landscape
buffers and plantings adjacent to paved areas, and seasonally wet areas within
the storm water treatment areas.
The number of trees requiring removal is within the City of Renton’s tree
retention threshold for industrial zones.
Construction activities will follow vegetation protection BMPs including:
• Minimizing clearing to the extent necessary to complete the project
• Clearly marking the extent of clearing before construction begins
• Installing and maintaining tree protection fencing to protect the critical
root zone of all trees to be retained.
• Replanting vegetated areas as soon as practicable after construction
activities are complete
e. List all noxious weeds and invasive species known to be on or near the site.
No noxious weeds are known to be located on the site. However, tansy ragwort
and spotted knapweed are documented as being located on neighboring parcels
(within 400 and 1,150 feet, respectively) (King County, 2016). Invasives on the
project site are limited to sporadic, herbaceous species.
5. Animals
a. List any birds and other animals which have been observed on or near the
site or are known to be on or near the site.
The project site does not include significant habitat for birds or mammals,
although small mammals and some urban-adapted bird species are expected to
occur in the general area and at the site. Washington Department of Fish and
Wildlife’s Priority Habitats and Species list does not list priority species on the
site. However, the Black River Riparian Forest contains the largest document
great blue heron rookery in the Puget Sound Region. The Black River wetlands
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SEPA Environmental Checklist South Plant Biogas and Heating Systems Improvements
and Springbrook Creek also provide habitat numerous other waterfowl species,
as well as a variety of fish species (Chinook, coho, resident coastal cutthroat,
steelhead, and winter steelhead).
b. List any threatened or endangered species known to be on or near the site.
Chinook and steelhead are federally-listed, threatened species that occur in the
Springbrook Creek segment of the Black River, which is also federally-
designated as critical habitat.
c. Is the site part of a migration route? If so, explain.
The project site is within the Pacific Flyway avian migration route.
d. Proposed measures to preserve or enhance wildlife, if any:
Impacts to wildlife are not anticipated as a result of this proposal; therefore, no
special measures to preserve wildlife are proposed.
e. List any invasive animal species known to be on or near the site.
None known
6. Energy and Natural Resources
a. What kinds of energy (electric, natural gas, oil, woodstove, solar) will be
used to meet the completed project's energy needs? Describe whether it will
be used for heating, manufacturing, etc.
The completed facility will use electricity and natural gas. The facility will
require energy for heating, lighting, and the operation of equipment.
b. Would your project affect the potential use of solar energy by adjacent
properties? If so, generally describe.
The completed facility will not affect the potential use of solar energy by
adjacent properties.
c. What kind of energy conservation features are included in the plans of this
proposal? List other proposed measures to reduce or control energy
impacts, if any:
Because biogas is produced from raw materials (in this case, municipal waste) it
is a source of renewable energy. Biogas is used for energy onsite, as well as sold
through the Puget Sound Energy natural gas utility infrastructure for use as
renewable natural gas. Some of the overarching goals for the new biogas
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upgrading system are to minimize the amount of electricity used to produce
biomethane while producing a gas that meets PSE gas quality requirements.
In addition, new mechanical systems will meet or exceed the minimum
efficiency requirements identified in the Washington Non-residential Energy
Code. The following energy efficiency measures, required by the Washington
Non-residential Energy Code or recommended to achieve the highest degree of
energy efficiency for systems, will be implemented where appropriate:
• Mechanical equipment that meets the minimum efficiency requirements of
the Washington Non-residential Energy Code
• Motors that meet the minimum efficiency requirements of the Washington
Non-residential Energy Code (with premium-efficiency motors contingent
on availability)
• Mechanical cooling equipment that uses economizers or free air cooling
• Deadband, setback, shutoff, and optimum start controls on HVAC systems
• Duct sealing and insulation
• Additional commissioning for HVAC systems designed to measure and
track energy usage and efficiency
7. Environmental Health
a. Are there any environmental health hazards, including exposure to toxic
chemicals, risk of fire and explosion, spill, or hazardous waste, that could
occur as a result of this proposal? If so, describe.
1) Describe any known or possible contamination at the site from
present or past uses.
A Phase I Environmental Site Assessment (ESA) was conducted for the
project site in March 2017. The Phase I ESA revealed no evidence of
contamination on the project site. The site was developed in 1965 as a
wastewater treatment facility, and prior, was undeveloped land. There are
five leaking underground storage tanks (LUSTs) located within the
vicinity of the project site, but none are located in the project area and
there is no confirmed groundwater contamination associated with the
LUSTs.
2) Describe existing hazardous chemicals/conditions that might affect
project development and design. This includes underground
hazardous liquid and gas transmission pipelines located within the
project area and in the vicinity.
There are no hazardous chemicals or conditions in the vicinity that might
affect project development or design.
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3) Describe any toxic or hazardous chemicals that might be stored, used,
or produced during the project's development or construction, or at
any time during the operating life of the project.
Construction-related materials such as fuel and hydraulic fluid will be
stored and used on site during construction. BMPs will be implemented
during construction to minimize the potential for spills or mechanical
failures to occur, and to minimize the potential for adverse effects from
hazardous chemicals to workers or nearby residents.
The completed facility will process and convey biogas, which is
flammable and may be hazardous to human health. The facility and
conveyance system will be sealed and designed to minimize the risk of
ignition of or human exposure to biogas.
4) Describe special emergency services that might be required.
None
5) Proposed measures to reduce or control environmental health
hazards, if any:
As described in items B.1.h and B.3.d. above, BMPs and other measures
will be used to avoid or contain and control any accidental spills or
releases of hazardous materials during project construction. Project plans
and construction specifications include measures to safely handle and
dispose of contaminated materials. No sources of contaminated materials
are known to be on the project site. However, if unexpectedly encountered
during construction, contaminated materials will be removed from the
work area and transported to a permitted disposal site. If groundwater is
encountered during construction, it may be assessed for petroleum
contamination associated with LUSTs located in proximity to the project
site.
The contractor will prepare a health and safety plan as a deliverable for the
proposed project prior to the start of construction. This plan will comply
with all applicable health regulations and will detail measures to control
environmental health hazards.
Once operational, facility staff will adhere to environmental safety
requirements and guidelines as prescribed by King County. These
requirements and guidelines include BMPs for the proper storage,
handling, disposal, and clean-up of hazardous materials.
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b. Noise
1) What types of noise exist in the area which may affect your project
(for example: traffic, equipment, operation, other)?
Noise in the project area will not affect the project.
2) What types and levels of noise would be created by or associated with
the project on a short-term or a long-term basis (for example: traffic,
construction, operation, other)? Indicate what hours noise would
come from the site.
Construction noise will likely exceed existing background noise levels.
Noise levels will vary depending on the specific equipment used for
particular activities. Based on previous construction projects, typical noise
levels can be expected to range from about 70 to 90 dBA measured at a
distance of 50 feet from the source. Throughout project construction,
short-term, intermittent construction related noise may include engine and
mechanical equipment noises associated with the use of heavy equipment
such as bulldozers, excavators, cranes, haul trucks, generators, chainsaws,
and air compressors.
Construction-related noises will be limited to construction hours allowable
by the City of Renton’s noise control code. If work outside of daytime
working hours is required, an application for a variance will be submitted
to the City of Renton.
In the completed facility, mechanical equipment will generate noise during
the day and night. None of the noises generated on the completed facility
will exceed the City of Renton’s maximum permissible sound level for the
site’s zoning or that of nearby receiving sites.
3) Proposed measures to reduce or control noise impacts, if any:
All construction and facility operation activities will be consistent with the
City of Renton noise control code. All impacts from noise generated by
construction will be short-term and temporary in nature. Construction
BMPs will be used to minimize construction noise and could include:
• Using effective vehicle mufflers, engine intake silencers, and engine
enclosures, and shutting off equipment when not in use
• Using temporary noise barriers around stationary equipment
• Positioning noise-generating equipment in the project area so that it
is as far away as possible from sensitive receptors
• Notifying residents and businesses near the project site of upcoming
noisy construction activities
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• 24-hour construction hotline to promptly respond to questions and
complaints
Sound generated by facility operations will be attenuated and muffled by
vegetation and distance. Because the maximum predicted acoustical level
of noise at the property line of adjacent properties is below code limits, no
additional mitigation is proposed.
8. Land and Shoreline Use
a. What is the current use of the site and adjacent properties? Will the
proposal affect current land uses on nearby or adjacent properties? If so,
describe.
The site is currently occupied by King County’s South Treatment Plant.
Adjacent properties include commercial and industrial sites. The proposed
project will not affect current land uses on adjacent or nearby properties.
b. Has the project site been used as working farmlands or working forest
lands? If so, describe. How much agricultural or forest land of long-term
commercial significance will be converted to other uses as a result of the
proposal, if any? If resource lands have not been designated, how many
acres in farmland or forest land tax status will be converted to nonfarm or
nonforest use?
Historic aerial photographs suggest the project area was part of a farm between
the late 1930s and late 1950s. The site has not been used as agricultural land
since that time, and is not designated as agricultural land of long-term
commercial significance. The project will not result in conversion of farm or
forest land to a nonfarm or nonforest use.
1) Will the proposal affect or be affected by surrounding working farm
or forest land normal business operations, such as oversize equipment
access, the application of pesticides, tilling, and harvesting? If so,
how:
No.
c. Describe any structures on the site.
The area of STP that contains the project site currently includes numerous
industrial buildings associated with wastewater treatment, administrative
buildings, and access roads.
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d. Will any structures be demolished? If so, what?
No.
e. What is the current zoning classification of the site?
Industrial Heavy (IH)
f. What is the current comprehensive plan designation of the site?
The site is located within the designated Employment Area (EA).
g. If applicable, what is the current shoreline master program designation of
the site?
The proposed project will occur outside of the shoreline. However, a temporary
construction entrance will be installed to provide access to the spoils site. This
temporary construction entrance will occur within a portion of the shoreline for
Springbrook Creek, designated as Shoreline High Intensity.
h. Has any part of the site been classified as a critical area by the city or
county? If so, specify.
One Category IV wetland (Wetland A) is located on the site. Wetland A is a
small (1,248 square-foot) depressional wetland located within a swale at the
south end of the grassy slope where the proposed HERB will be located. In
addition, an off-site wetland is mapped north of the project area within
Waterworks Gardens. No work will occur within either wetland or their
regulated buffers.
A flood hazard area associated with Springbrook Creek is mapped on a portion
of the project site. A portion of the temporary construction entrance will be
located within this area, but no permanent facilities or fill will be located within
the mapped floodplain. See item B.3.a above for a summary of surface waters.
The project site also contains two geologic hazard areas: a moderate Coal Mine
Hazard Area and a high Seismic Hazard Area.
i. Approximately how many people would reside or work in the completed
project?
Approximately 140 people currently work at STP. The new system will not
result in additional staff being employed.
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j. Approximately how many people would the completed project displace?
None
k. Proposed measures to avoid or reduce displacement impacts, if any:
None
l. Proposed measures to ensure the proposal is compatible with existing and
projected land uses and plans, if any:
Construction of the project will not conflict with existing land use plans and
policies; however, a number of permits or approvals will be required. Site Plan
Review is required for all development in the EA designation, and sewage
disposal and treatment plants also require a Conditional Use Permit in the IH
zone. The City of Renton is being consulted to ensure that the project is
compatible with existing and projected land uses and plans. King County will
prepare a Critical Area Report in accordance with City of Renton submittal
requirements in order to protect the onsite wetland and to address coal mine and
seismic hazard areas.
The City of Renton anticipates that the surrounding area will continue to be
used for commercial and light industrial uses. Therefore, the completed facility
is not expected to be incompatible with existing or future land use plans for the
area.
m. Proposed measures to ensure the proposal is compatible with nearby
agricultural and forest lands of long-term commercial significance, if any:
None
9. Housing
a. Approximately how many units would be provided, if any? Indicate
whether high, middle, or low-income housing.
None
b. Approximately how many units, if any, would be eliminated? Indicate
whether high, middle, or low-income housing.
None
c. Proposed measures to reduce or control housing impacts, if any:
None
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10. Aesthetics
a. What is the tallest height of any proposed structure(s), not including
antennae; what is the principal exterior building material(s) proposed?
The anticipated maximum building height for the HERB is approximately 30
feet; the thermal oxidizer will consist primarily of an exhaust stack
approximately 32 feet tall. The new building will consist of cast-in-place
concrete exterior walls and a steel-joist-supported roof. The exterior walls will
have a pattern of joints and textures that match the nearby cogeneration facility,
as well as other buildings at the site. Doors, frames, windows, and louvers will
be aluminum. A canopy roof will be provided to shelter the outdoor equipment.
b. What views in the immediate vicinity would be altered or obstructed?
Views of the site will remain generally the same. The size of the overall Plant
will not change and character of the site will continue to be that of an industrial
operation.
c. Proposed measures to reduce or control aesthetic impacts, if any:
Modifications or additions to existing structures will be designed to blend with
the existing architecture character by using similar massing and materials.
Where possible, the color of building materials will be integral to the material or
provided with a factory finish to minimize painted surfaces.
11. Light and Glare
a. What type of light or glare will the proposal produce? What time of day
would it mainly occur?
Project construction will take place largely during daylight hours. Temporary
site lighting may be used at the beginning and end of work days during
construction when daylight hours are short.
The completed project will require sufficient light for safety and security.
Outside areas that are currently lit at night include entry and exit driveways,
truck staging and parking areas, and building entrances. As part of the
completed project, the entrances to the HERB will be lit similar to existing site
lighting.
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SEPA Environmental Checklist South Plant Biogas and Heating Systems Improvements
b. Could light and glare from the finished project be a safety hazard or
interfere with views?
No. The site is surrounded by buildings to the west, east, and south with similar
exterior lighting.
c. What existing off-site sources of light or glare may affect your proposal?
None
d. Proposed measures to reduce or control light and glare impacts, if any:
All exterior lights will be focused or shielded as necessary to cast light only in
areas that require it and to minimize light spilling onto neighboring properties.
12. Recreation
a. What designated and informal recreational opportunities are in the
immediate vicinity?
Waterworks Gardens is a King County-owned eight-acre park located north of
the project area. The main feature of the gardens are wetlands established to
provide storm water treatment for STP.
Other recreational opportunities in the general vicinity include Springbrook
Trail, a 2.3-mile trail that parallels the eastern boundary of the 50-acre STP site
until it crosses Oakesdale Ave SW and enters the Black River Riparian Forest
and Wetland. The Black River Riparian Forest is a 93-acre refuge that is popular
for birdwatching.
b. Would the proposed project displace any existing recreational uses? If so,
describe.
No.
c. Proposed measures to reduce or control impacts on recreation, including
recreation opportunities to be provided by the project or applicant, if any:
None
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SEPA Environmental Checklist South Plant Biogas and Heating Systems Improvements
13. Historic and Cultural Preservation
a. Are there any buildings, structures, or sites, located on or near the site that
are over 45 years old listed in or eligible for listing in national, state, or
local preservation registers located on or near the site? If so, specifically
describe.
No buildings, structures, or sites that are listed in or eligible for listing in
preservation registers have been identified on the project site, or within 0.5 miles
of the project site.
Two unevaluated historic properties are within or adjacent to the project site.
The first is South Treatment Plant itself, described as “Renton Sewage
Treatment Plant” in the Washington Department of Archaeology and Historic
Preservation (DAHP) database, which was constructed 1965, and is therefore
over 45 years old. South Treatment Plant was recorded on a DAHP Historic
Property Inventory form in 2010, but no determination has been made regarding
eligibility for listing in the National Register of Historic Places (NRHP). An
update to this inventory form may be required by DAHP. The second
unevaluated historic property is the Graphic Packaging International factory,
located adjacent to STP at 601 Monster Road SW. The building, constructed in
1956, was recorded in the Historic Property Inventory as part of an import of
county assessor data, but no recommendation has been made regarding its
eligibility for listing in the NRHP. However, the building is outside of the view-
shed of the project, and no impact is anticipated.
b. Are there any landmarks, features, or other evidence of Indian or historic
use or occupation? This may include human burials or old cemeteries. Are
there any material evidence, artifacts, or areas of cultural importance on or
near the site? Please list any professional studies conducted at the site to
identify such resources.
No landmarks, features, or other evidence of Indian or historic use have been
identified on the project site; however, there are several nearby sites, including
precontact- and historic-era sites. Historic resources are railroad grades and
historic debris scatters. Precontact resources are village sites, including sites
where human burials have been identified. Three of the village sites have been
determined eligible for listing on the NRHP. Environmental Science Associates
completed a Cultural Resources Background Investigation for the project site.
Based on proximity of the project site to recorded archaeological sites, its
location above the former Black River channel and near the confluence with the
Green (White) River, and the presence of ethnographic sites within the vicinity,
it is likely that people used the landforms contained within the project area
during the precontact and ethnographic periods. However, due to the previous
development of STP, which involved large-scale earth work, the likelihood for
intact archaeological sites is diminished.
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SEPA Environmental Checklist South Plant Biogas and Heating Systems Improvements
c. Describe the methods used to assess the potential impacts to cultural and
historic resources on or near the project site. Examples include consultation
with tribes and the department of archeology and historic preservation,
archaeological surveys, historic maps, GIS data, etc.
The project was screened by the King County Historic Preservation Program for
the presence of cultural and historic resources within the project area and the
probability of an inadvertent discovery of cultural resources during project
construction. This screening included a review of historic registers, databases
including the DAHP records database (“WISAARD”), historic maps and
reports, and predictive GIS modeling. Environmental Science Associates also
conducted an in-depth review of existing cultural resources reports and
databases.
d. Proposed measures to avoid, minimize, or compensate for loss, changes to,
and disturbance to resources. Please include plans for the above and any
permits that may be required.
King County will prepare an inadvertent discovery plan (IDP) for project
construction. The IDP will provide guidance to contractors for identifying
potential cultural resources, and establish procedures to follow in the event of
the unanticipated discovery of potential cultural resources in order to protect the
discovery until it can be assessed by a professional archaeologist.
14. Transportation
a. Identify public streets and highways serving the site or affected geographic
area, and describe proposed access to the existing street system. Show on
site plans, if any.
The site is bordered by SW Grady Way and I-405 to the south, Oakesdale
Avenue SW to the east and north, and Monster Road SW to the west. The
primary access to the northern portion of STP, where the project will be
developed, is via SW 7th Street. However, there are additional driveways located
off of Monster Road SW, Longacres Drive SW, and SW Grady Way.
b. Is the site or affected geographic area currently served by public transit? If
so, generally describe. If not, what is the approximate distance to the
nearest transit stop?
The 50-acre STP site is served by public transit. King County Metro stops for
the 161 and 280 are located on SW Grady Way and the Tukwila Station for
Amtrak and the Sounder Train are located a mile to the south of STP.
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SEPA Environmental Checklist South Plant Biogas and Heating Systems Improvements
c. How many additional parking spaces would the completed project or non-
project proposal have? How many would the project or proposal eliminate?
The new facility will include up to 10 parking stalls on the north side of the
building. The project will not eliminate any existing parking spaces.
d. Will the proposal require any new or improvements to existing roads,
streets, pedestrian, bicycle, or state transportation facilities, not including
driveways? If so, generally describe (indicate whether public or private).
No such improvements are included as part of this proposal.
e. Will the project use (or occur in the immediate vicinity of) water, rail, or air
transportation? If so, generally describe.
No.
f. How many vehicular trips per day would be generated by the completed
project or proposal? If known, indicate when peak volumes would occur
and what percentage of the volume would be trucks (such as commercial
and nonpassenger vehicles). What data or transportation models were used
to make these estimates?
Project construction will require approximately 750 truck trips over
approximately two years, in order to deliver materials including concrete,
asphalt, and other building materials. No vehicular trips will be generated by the
completed project because the project will not result in additional employment
or an increased need for plant employees to enter or exit the site beyond existing
conditions.
g. Will the proposal interfere with, affect or be affected by the movement of
agricultural and forest products on roads or streets in the area? If so,
generally describe.
No.
h. Proposed measures to reduce or control transportation impacts, if any:
Long-term transportation impacts are not anticipated; therefore, mitigation
measures have not been developed.
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15. Public Services
a. Would the project result in an increased need for public services (for
example: fire protection, police protection, public transit, health care,
schools, other)? If so, generally describe.
No.
b. Proposed measures to reduce or control direct impacts on public services, if
any:
None
16. Utilities
a. Circle utilities currently available at the site:
lelectricifYI, !natural gasl, 1\Vatei), !refuse servic~, ltelephon~, !sanitary sewe~,
septic system, other ___ _
b. Describe the utilities that are proposed for the project, the utility providing
the service, and the general construction activities on the site or in the
immediate vicinity which might be needed.
The project will primarily involve extensions of the existing utilities located on
site. Existing utility tunnels that mn under the Digester Equipment Building will
be extended to provide utilities to the new HERB. New low pressure sludge gas
(LSG), waste gas, and high-pressure sludge gas (HSSG) pipes will be routed
underground along the plant's driveway (Road N) between the existing waste
gas burners and the current BUS. All utilities in the driveway will be installed
using open-cut constmction methods. New electrical equipment will be installed
in the Solids MCC Building and new HERB. Electric and natural gas service on
the site is provided by Puget Sound Energy, water and refuse service is provided
by City of Renton, and wastewater service is provided by King County.
C. SIGNATURE
The above answ!r~14e tru~ and complete to the. best o~ ~y knowledge. I understand
that the lead agepcy IS r lymg on them to make Its decision.
Signature: c?;,., F
Katherine Fischer, Environmental Programs Managing Supervisor
King County WTD
Date Submitted: :J J? I /! g"
; ;
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SEPA Environmental Checklist South Plant Biogas and Heating Systems Improvements
Figure 1. Vicinity map
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SEPA Environmental Checklist South Plant Biogas and Heating Systems Improvements
Figure 2. Site plan
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SEPA Environmental Checklist South Plant Biogas and Heating Systems Improvements
Attachment 1. King County greenhouse gas emissions worksheet
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