HomeMy WebLinkAboutC_ERC_Determination_Agency_Letter_ThunderHillsSewer_181221.pdf
cc: King County Development and Environmental Services Jalaine Madura, Seattle Public Utilities
Wendy Weiker, Puget Sound Energy Matthew Gilbert, City of Kent
Boyd Powers, Department of Natural Resources Ramin Pazooki, WSDOT, NW Region
Gretchen Kaehler, Office of Archaeology & Historic Preservation Duwamish Tribal Office
Shirley Marroquin, King County Wastewater Treatment Division US Army Corp. of Engineers
Karen Walter, Fisheries, Muckleshoot Indian Tribe (digital) Jack Pace, City of Tukwila (digital)
Laura Murphy, Muckleshoot Cultural Resources Program (digital) Misty Blair, Department of Ecology (digital)
Larry Fisher, Department of Fish and Wildlife (digital) Steve Osguthorpe, City of Newcastle (digital)
WS Department of Ecology, Environmental Review Section (digital) Gary Kriedt, Metro Transit (digital)
SEPA Center, WS Department of Natural Resources (digital) Andy Swayne, Puget Sound Energy (digital)
December 21, 2018
Washington State
Department of Ecology
Environmental Review Section
PO Box 47703
Olympia, WA 98504-7703
Subject: ENVIRONMENTAL (SEPA) THRESHOLD DETERMINATION
Transmitted herewith is a copy of the Environmental Determination for the following project reviewed by the
Environmental Review Committee (ERC) on December 17, 2018:
SEPA DETERMINATION: Determination of Non-Significance - Mitigated (DNS-M)
PROJECT NAME: Thunder Hills Sewer Interceptor Rehabilitation, PR18-000551
PROJECT NUMBER: LUA18-000678, ECF
Appeals of the environmental determination must be filed in writing on or before 5:00 p.m. on January 4, 2019,
together with the required fee with: Hearing Examiner, City of Renton, 1055 South Grady Way, Renton, WA 98057.
Appeals to the Examiner are governed by RMC 4-8-110 and information regarding the appeal process may be
obtained from the City Clerk’s Office, (425) 430-6510.
Please refer to the enclosed Notice of Environmental Determination for complete details. If you have questions,
please call me at (425) 430-6598.
For the Environmental Review Committee,
Jill Ding
Senior Planner
Enclosure: ERC Determination, Mitigation Measures/Advisory Notes, Notice of Environmental Determination, and Environmental Checklist
(select recipients)
DEPARTMENT OF COMMUNITY
AND ECONOMIC DEVELOPMENT
SIGNATURES:
Gregg Zimmerman, Administrator Date Rick M. Marshall, Administrator Date
Public Works Department Renton Regional Fire Authority
Kelly Beymer, Administrator Date C.E. Vincent, Administrator Date
Community Services Department Department Of Community & Economic Development
ENVIRONMENTAL (SEPA) DETERMINATION OF
NON-SIGNIFICANCE - MITIGATED (DNS-M)
PROJECT NUMBER: LUA18-000678, ECF
APPLICANT: Dave Christensen, City of Renton - Wastewater Utility /
Dchristensen@Rentonwa.gov / 1055 S Grady Way, Renton, WA 98057
PROJECT NAME: Thunder Hills Sewer Interceptor Rehabilitation
PROJECT DESCRIPTION: The applicant is requesting Environmental (SEPA) Review for improvements to
approximately 2,050 lineal feet of sewer main. The sewer line would be improved through a mix of parallel HDPE pipelines and
rehabilitation of the existing line using a cured-in-place lining technology. In addition, improvements are proposed to the 37,574
square foot maintenance access road and slope stability measures are proposed to alleviate erosion in the future. The project
site includes Thunder Hills Creek, a type Np stream with a 75-foot buffer, and seven tributary streams, all classified as Type Ns
streams with 50-foot buffers. There are six wetlands (Wetlands A-F). Of the six wetlands, four (Wetlands B, D, E, and F) would
have a standard buffer of 100 feet, Wetland A would have a standard buffer of 75 feet, and Wetland C would have a standard
buffer of 50 feet. The proposal would include 20,703 square feet of temporary wetland and stream buffer impacts, 1,332 square
feet of wetland impacts (Wetland E and F), and 41,000 permanent buffer impacts including the removal of 36 trees. The project
site includes RM-F and R-8 zoning designations. Access to the site would be provided via a gated entrance off of Grant Ave S
and S 18th St as well as an existing entrance at the cleared PSE easement access along S 18th St.
PROJECT LOCATION: Gated entrance at Grant Ave S and S 18th St and runs the length of Thunder Hills
Creek North just up to before it goes under I-405
LEAD AGENCY: City of Renton
Environmental Review Committee
Department of Community & Economic Development
The City of Renton Environmental Review Committee has determined that it does not have a probable significant adverse
impact on the environment. An Environmental Impact Statement (EIS) is not required under RCW 43.21C.030(2)(c).
Conditions were imposed as mitigation measures by the Environmental Review Committee under their authority of
Section 4-9-070D Renton Municipal Code. These conditions are necessary to mitigate environmental impacts identified
during the environmental review process. Because other agencies of jurisdiction may be involved, the lead agency will not
act on this proposal for fourteen (14) days.
Appeals of the environmental determination must be filed in writing on or before 5:00 p.m. on January 4, 2019. Appeals
must be filed in writing together with the required fee with: Hearing Examiner, City of Renton, 1055 South Grady Way,
Renton, WA 98057. Appeals to the Examiner are governed by RMC 4-8-110 and more information may be obtained from
the Renton City Clerk’s Office, (425) 430-6510.
PUBLICATION DATE: December 21, 2018
DATE OF DECISION: December 17, 2018
DocuSign Envelope ID: B8D5474C-3764-4AAB-9F39-921E42EA7ABF
12/17/2018 | 2:58 PM PST12/17/2018 | 3:21 PM PST
12/17/2018 | 2:54 PM PST
DEPARTMENT OF COMMUNITY & ECONOMIC DEVELOPMENT
Planning Division
1055 South Grady Way, 6th Floor | Renton, WA 98057 | 425-430-7200, ext. 2
www.rentonwa.gov
DETERMINATION OF NON-SIGNIFICANCE – MITIGATED (DNS-M)
MITIGATION MEASURES AND ADVISORY NOTES
PROJECT NUMBER: LUA18-000678, ECF
APPLICANT: Dave Christensen, City of Renton - Wastewater Utility /
Dchristensen@Rentonwa.gov / 1055 S Grady Way, Renton, WA 98057
PROJECT NAME: Thunder Hills Sewer Interceptor Rehabilitation
PROJECT DESCRIPTION: The applicant is requesting Environmental (SEPA) Review for
improvements to approximately 2,050 lineal feet of sewer main. The sewer line would be improved through a mix
of parallel HDPE pipelines and rehabilitation of the existing line using a cured-in-place lining technology. In
addition, improvements are proposed to the 37,574 square foot maintenance access road and slope stability
measures are proposed to alleviate erosion in the future. The project site includes Thunder Hills Creek, a type Np
stream with a 75-foot buffer, and seven tributary streams, all classified as Type Ns streams with 50-foot buffers.
There are six wetlands (Wetlands A-F). Of the six wetlands, four (Wetlands B, D, E, and F) would have a standard
buffer of 100 feet, Wetland A would have a standard buffer of 75 feet, and Wetland C would have a standard
buffer of 50 feet. The proposal would include 20,703 square feet of temporary wetland and stream buffer impacts,
1,332 square feet of wetland impacts (Wetland E and F), and 41,000 permanent buffer impacts including the
removal of 36 trees. The project site includes RM-F and R-8 zoning designations. Access to the site would be
provided via a gated entrance off of Grant Ave S and S 18th St as well as an existing entrance at the cleared PSE
easement access along S 18th St.
PROJECT LOCATION: Gated entrance at Grant Ave S and S 18th St and runs the length of
Thunder Hills Creek North just up to before it goes under I-405
LEAD AGENCY: The City of Renton
Department of Community & Economic Development
Planning Division
MITIGATION MEASURES:
1. Project construction shall comply with the recommendations outlined in the Geotechnical Report,
prepared by Stantec, dated February 13, 2015.
ADIVISORY NOTES:
The following notes are supplemental information provided in conjunction with the administrative land use
action. Because these notes are provided as information only, they are not subject to the appeal process for the
land use actions.
DEPARTMENT OF COMMUNITY
AND ECONOMIC DEVELOPMENT
Page 1 of 2 LUA18-000678
ADVISORY NOTES TO APPLICANT
The following notes are supplemental information provided in conjunction with the administrative land use
action. Because these notes are provided as information only, they are not subject to the appeal process for
the land use action.
Planning:
(Contact: Name, 425-430-6598, jding@rentonwa.gov)
1. RMC section 4-4-030.C.2 limits haul hours between 8:30 am to 3:30 pm, Monday through Friday unless
otherwise approved by the Development Services Division.
2. Commercial, multi-family, new single family and other nonresidential construction activities shall be
restricted to the hours between seven o’clock (7:00) a.m. and eight o’clock (8:00) p.m., Monday through
Friday. Work on Saturdays shall be restricted to the hours between nine o’clock (9:00) a.m. and eight
o’clock (8:00) p.m. No work shall be permitted on Sundays.
3. Within thirty (30) days of completion of grading work, the applicant shall hydroseed or plant an
appropriate ground cover over any portion of the site that is graded or cleared of vegetation and where
no further construction work will occur within ninety (90) days. Alternative measures such as mulch,
sodding, or plastic covering as specified in the current King County Surface Water Management Design
Manual as adopted by the City of Renton may be proposed between the dates of November 1st and
March 31st of each year. The Development Services Division’s approval of this work is required prior to
final inspection and approval of the permit.
4. A National Permit Discharge Elimination System (NPDES) permit is required when more than one acre is
being cleared.
5. The applicant will be required to submit a Final Stream Mitigation Report and Maintenance and
Monitoring proposal. In addition, the applicant will be required to comply with all the code requirements
of RMC 4-3-050 Critical Areas. This includes, but is not limited to, providing the City with a site
restoration surety device and, later, a maintenance and monitoring surety device.
6. The applicant may not fill, excavate, stack or store any equipment, dispose of any materials, supplies or
fluids, operate any equipment, install impervious surfaces, or compact the earth in any way within the
area defined by the drip line of any tree to be retained.
7. Retaining walls over 4 feet in height require a building permit. Any retaining walls proposed over 6 feet
in height require the approval of a Modification in accordance with RMC 4-9-250D.
8. This permit is shall comply with the Bald and Golden Eagle Protection Act. The permitted is responsible
for adhering to the U.S. Fish and Wildlife Service National Bald Eagle Management Guidelines (2007) and
/or your U.S. Fish and Wildlife Service permit.
Development Engineering:
(Contact: Name, 425-430-7382, afowler@rentonwa.gov)
1. See Attached Development Engineering Memo dated December 7, 2018
Fire Authority:
(Contact: Corey Thomas, 425-430-7024, cthomas@rentonwa.gov)
1. None
Technical Services:
(Contact: Amanda Askren, 425-430-7369, aaskren@rentonwa.gov)
EXHIBIT 7
ADVISORY NOTES TO APPLICANT
Page 2 of 2 LUA18-000678
1. Easements documents to be reviewed upon consultant completion. Comments will be provided prior
to recording of said easement documents.
Community Services:
(Contact: Leslie Betlach, 425-430-6619, lbetlach@rentonwa.gov)
1. None
Police:
(Contact: Cyndie Parks, 425-430-7521, cparks@rentonwa.gov)
1. None
Building:
(Contact: Craig Burnell, 425-430-7290, cburnell@rentonwa.gov)
1. None
DEPARTMENT OF COMMUNITY
& ECONOMIC DEVELOPMENT
M E M O R A N D U M
DATE: December 7, 2018
TO:Jill Ding, Planner
FROM:Ann Fowler, Civil Plan Reviewer
SUBJECT: Utility and Transportation Comments for Thunder Hills Sewer
Interceptor Rehabilitation
Thunder Hills Creek from Grant Ave S/S 18th Street to I-405
LUA18-000551
I have reviewed the application for the Thunder Hills Sewer Interceptor Rehabilitation at Thunder
Hills Creek from Grant Ave S/S 18th Street to I-405 and have the following comments:
EXISTING CONDITIONS
The site is approximately 2.18 acres in size and is irregular in shape. The site consists of an existing
sewer interceptor alignment through the Thunder Hills Creek valley along with a gravel improved
access roadway located adjacent to the existing stream.
CODE REQUIREMENTS
SURFACE WATER
1. A geotechnical report, dated February 13, 2015, completed by Stantec, for the site has
been provided. The submitted report describes the site is a Severe Erosion Hazard area.
Erosion control measures will need to be in place prior to starting grading activities on the
site. Geotechnical recommendations presented need to be address within the project
plans.
2. Temporary erosion and sediment control plans are required and shall be in accordance
with the City of Renton Surfacewater Design Manual.
3. A Construction Stormwater General Permit from Department of Ecology will be required
since grading and clearing of the site exceeds one acre.
4. A Stormwater Pollution Prevention Plan (SWPPP) is required for the project site and shall
be submitted with the Civil Construction Permit Application.
5. Wet Season requirements found in Appendix D of the 2017 City of Renton Surface Water
Design Manual (RSWDM) shall be adhered to for construction occurring between October
1st and April 30th.
6. All work proposed outside of the applicant’s property will require a temporary
construction easement prior to any permits being issued.
TRANSPORTATION
Thunder Hills Sewer Interceptor Rehabilitation – LUA18-000551
Page 2 of 2
1. Any work within or affecting traffic within the City right-of-way will require an approved
traffic control from the City.
2. Paving and trench restoration shall comply with the City’s Trench Restoration and Overlay
Requirements.
3. The right of way shall remain unobstructed when possible. No stockpiles are allowed in
the right of way. All truck maneuvering and materials storage shall occur on-site.
4. City streets shall be kept clean at all times and shall be swept in a timely manner. Truck
washing and / or other measures as approved by the Public Works Inspector may be
required for the duration of the project.
5. Construction hours outside of right of way: 7:00 AM to 8:00 PM Monday thru Friday and
9:00 AM to 8:00 PM on Saturday. Saturday work is by permission only. No work is allowed
on Sunday.
6. Construction hours inside of right of way: Follow approved traffic control plan. Saturday
work is by permission only. No work is allowed on Sunday.
7. Right of way haul hours: 8:30 AM to 3:30 PM Monday thru Friday. Hauling on Saturday is
by permission only. No hauling is allowed on Sunday.
GENERAL COMMENTS
1. Maximum exposed retaining wall height is 6-ft in residential zones and 8-ft in commercial
zones and shall be setback a minimum of 3-ft from the right-of-way as outlined in RMC 4-
4-040 – Fences, Hedges and Retaining Walls. A modification request is required to exceed
the height limitations outlined in City code.
2. A civil construction permit for the utility repairs is required. Civil construction plans shall
conform to the City Renton Drafting Standards. A licensed Civil Engineer shall prepare
the civil plans. Please visit the City’s website for submittal requirements:
https://rentonwa.gov/cms/One.aspx?portalId=7922741&pageId=9687014
3. A landscaping plan shall be included with the civil plan submittal.
DEPARTMENT OF COMMUNITY & ECONOMIC DEVELOPMENT
Planning Division
1055 South Grady Way, 6th Floor | Renton, WA 98057 | 425-430-7200, ext. 2
www.rentonwa.gov
OF ENVIRONMENTAL DETERMINATION
ISSUANCE OF A DETERMINATION OF NON-SIGNIFICANCE - MITIGATED (DNS-M)
POSTED TO NOTIFY INTERESTED PERSONS OF AN ENVIRONMENTAL ACTION
DNS-M: The City Of Renton Environmental Review Committee (ERC) has determined that the proposed action has
probable significant impacts that can be mitigated through mitigation measures.
DATE OF NOTICE OF ENVIRONMENTAL
DETERMINATION:
December 21, 2018
PROJECT NAME/NUMBER: Thunder Hills Sewer Interceptor Rehabilitation /
LUA18-000678, ECF
PROJECT LOCATION: Gated entrance at Grant Ave S and S 18th St and runs the length of Thunder
Hills Creek North just up to before it goes under I-405
LOCATION WHERE APPLICATION MAY
BE REVIEWED:
Applicant documents are available online through the City of Renton
Document Center website. See also https://bit.ly/2QQkU3Q
PROJECT DESCRIPTION: The applicant is requesting Environmental (SEPA) Review for improvements
to approximately 2,050 lineal feet of sewer main. The sewer line would be improved through a mix of parallel HDPE
pipelines and rehabilitation of the existing line using a cured-in-place lining technology. In addition, improvements are
proposed to the 37,574 square foot maintenance access road and slope stability measures are proposed to alleviate
erosion in the future. The project site includes Thunder Hills Creek, a type Np stream with a 75-foot buffer, and seven
tributary streams, all classified as Type Ns streams with 50-foot buffers. There are six wetlands (Wetlands A-F). Of the
six wetlands, four (Wetlands B, D, E, and F) would have a standard buffer of 100 feet, Wetland A would have a standard
buffer of 75 feet, and Wetland C would have a standard buffer of 50 feet. The proposal would include 20,703 square feet
of temporary wetland and stream buffer impacts, 1,332 square feet of wetland impacts (Wetland E and F), and 41,000
permanent buffer impacts including the removal of 36 trees. The project site includes RM-F and R-8 zoning designations.
Access to the site would be provided via a gated entrance off of Grant Ave S and S 18th St as well as an existing entrance
at the cleared PSE easement access along S 18th St.
Appeals of the environmental determination must be filed in writing on or before 5:00 p.m. on January 4, 2019,
together with the required fee with: Hearing Examiner, City of Renton, 1055 South Grady Way, Renton, WA 98057.
Appeals to the Examiner are governed by City of RMC 4-8-110 and information regarding the appeal process may be
obtained from the Renton City Clerk’s Office, (425) 430-6510.
PUBLIC HEARING: If the Environmental Determination is appealed, a public hearing will be set
and all parties notified.
NOTICE
DEPARTMENT OF COMMUNITY
AND ECONOMIC DEVELOPMENT
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 1 of 23
ENV ENVIRONMENTAL CHECKLIST
Planning Division
1055 South Grady Way-Renton, WA 98057
Phone: 425-430-7200 | www.rentonwa.gov
Purpose of checklist:
Governmental agencies use this checklist to help determine whether the environmental impacts of your
proposal are significant. This information is also helpful to determine if available avoidance, minimization
or compensatory mitigation measures will address the probable significant impacts or if an environmental
impact statement will be prepared to further analyze the proposal.
Instructions for applicants:
This environmental checklist asks you to describe some basic information about your proposal. Please
answer each question accurately and carefully, to the best of your knowledge. You may need to consult
with an agency specialist or private consultant for some questions. You may use “not applicable” or
"does not apply" only when you can explain why it does not apply and not when the answer is unknown.
You may also attach or incorporate by reference additional studies reports. Complete and accurate
answers to these questions often avoid delays with the SEPA process as well as later in the decision-
making process.
The checklist questions apply to all parts of your proposal, even if you plan to do them over a period of
time or on different parcels of land. Attach any additional information that will help describe your proposal
or its environmental effects. The agency to which you submit this checklist may ask you to explain your
answers or provide additional information reasonably related to determining if there may be significant
adverse impact.
Instructions for Lead Agencies:
Please adjust the format of this template as needed. Additional information may be necessary to
evaluate the existing environment, all interrelated aspects of the proposal and an analysis of adverse
impacts. The checklist is considered the first but not necessarily the only source of information needed to
make an adequate threshold determination. Once a threshold determination is made, the lead agency is
responsible for the completeness and accuracy of the checklist and other supporting documents.
Use of checklist for nonproject proposals:
For nonproject proposals (such as ordinances, regulations, plans and programs), complete the applicable
parts of sections A and B plus the SUPPLEMENTAL SHEET FOR NONPROJECT ACTIONS (part D). Please
completely answer all questions that apply and note that the words "project," "applicant," and "property or
site" should be read as "proposal," "proponent," and "affected geographic area," respectively. The lead
agency may exclude (for non-projects) questions in Part B - Environmental Elements –that do not
DEPARTMENT OF COMMUNITY
AND ECONOMIC DEVELOPMENT
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 2 of 23
contribute meaningfully to the analysis of the proposal.
A. Background [HELP]
1. Name of proposed project, if applicable:
Thunder Hills Sanitary Sewer Replacement Project
2. Name of applicant:
City of Renton
3. Address and phone number of applicant and contact person:
1055 S. Grady Way
Renton, WA 98057-3232
425.430.7212
Dave Christensen, Wastewater Utility Engineering Manager
4. Date checklist prepared:
September 12, 2018. Project design at time of preparation is 90%.
5. Agency requesting checklist:
City of Renton
6. Proposed timing or schedule (including phasing, if applicable):
Project construction is anticipated to begin in June 2019 and be completed by September 2019,
with construction activities to commence during normal business hours (Monday through Friday,
8am to 5pm).
7. Do you have any plans for future additions, expansion, or further activity related to or
connected with this proposal? If yes, explain.
No. There are no plans for future additions, expansions or further activity related to or connected
with this proposal.
8. List any environmental information you know about that has been prepared, or will be
prepared, directly related to this proposal.
• Thunder Hills Sanitary Sewer Interceptor and Alternatives Analysis Basis of Design
Report – Carollo Engineers, Inc. (July 2016)
• Technical Memorandum: Summary of Sensitive Area Impacts – The Watershed
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 3 of 23
Company (October 21, 2015)
• Technical Memorandum: Geotechnical Investigation – Stantec Consulting Services
Inc. (February 13, 2015)
• Technical Memorandum: Preliminary Erosion Hazard Evaluation – Stantec
Consulting Services Inc. (February 13, 2015)
• Technical Memorandum: Flow Analysis – Stantec Consulting Services Inc. (February
24, 2015)
• Technical Memorandum: Operations & Maintenance Study – Stantec Consulting
Services Inc. (November 13, 2015)
• Technical Memorandum: Permitting Assessment Alternatives No. 1 & 2 – Stantec
Consulting Services Inc. (October 19, 2015)
• Technical Memorandum: Remaining Useful Life (RUL) & Rehabilitation Analysis –
Stantec Consulting Services Inc. (February 13, 2015)
• Technical Memorandum: (Draft) Risk Analysis – Stantec Consulting Services Inc.
(February 24, 2015)
• Stream and Wetland Delineation Report – The Watershed Company (October 12,
2015)
• Rockery Wall Recommendations – Stantec Consulting Services Inc. (November 1,
2016)
• Mitigation Plan (90% design) – The Watershed Company (June 2018)
• Landscaping and Planting Plan (90% design) – The Watershed Company (June
2018)
• Technical Memorandum: Springbrook Creek Mitigation Bank Use Plan – The
Watershed Company (November 2, 2017)
• Technical Memorandum: Wetland and Stream/Wetland Buffer Mitigation Cost
Estimates (December 4, 2017)
• Cultural Resource Assessment Report – The Watershed Company (August 11,
2017)
• No-Effect Letter Report for ESA-Listed Species – The Watershed Company (October
20, 2017)
• Critical Areas Report – The Watershed Company (April 3, 2018)
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.
There are no other applications known to be pending that would affect the proposal.
10. List any government approvals or permits that will be needed for your proposal, if
known.
• City of Renton Grading Permit
• City of Renton Right-of-Way Permit(s)
• City of Renton Rockery Building Permit(s)
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 4 of 23
• City of Renton Environmental Review (SEPA checklist)
• City of Renton Critical Area Exemption
• City of Renton Administrative Modification
• City of Renton Land Use Master Application
• BP Olympic Pipeline Design Plans Submission Checklist and Equipment Inventory
List
• BP Olympic Pipeline notification prior to project work within 10 feet of pipeline
• Puget Sound Energy Easement Agreement
• Joint Aquatic Resources Permit Application (JARPA)
• Washington Department of Ecology NPDES Construction Stormwater Permit
• Washington State Department of Transportation Limited Access Right-of-Way Permit
• Washington State Department of Fish and Wildlife Hydraulic Project Approval (HPA)
• King County Wastewater Treatment Division Approval
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. (Lead agencies may modify this form to include additional
specific information on project description.)
The Thunder Hills Sanitary Sewer Interceptor collects sewage from the Rolling Hills
neighborhood and is located southeast of Renton City Hall. The interceptor connects to sewer
mains that ultimately flow to the King County South Wastewater Treatment Plant. The
proposed Thunder Hills Sanitary Sewer Interceptor Replacement project includes the segment
from near the intersection of Grant Avenue South and South 18th Street to near I-405 running
through a small canyon created by Thunder Hills Creek.
Thunder Hills Creek is in a steep, narrow ravine that is incised from stream flows. The
Thunder Hills Sanitary Sewer Interceptor traverses along and crosses under Thunder Hills
Creek within this ravine. A maintenance road and trails for access to the sewer main are also
located along the creek alignment.
The existing sewer main was originally constructed in 1965 and consists of 10-inch, 12-inch
and 18-inch concrete, asbestos cement, and ductile iron pipe. In 2014 an inspection was
conducted to determine the condition of the existing line. Grease buildup, separated pipe
joints, broken lip sections, corrosion of cast iron fittings, concrete lining spalling, heavy scale
deposits, minor root intrusion, and a sag in one portion of the line were found as a result of the
line inspection. In addition, the existing line was not constructed with adequate manholes to
allow for proper maintenance of the system.
The ravine’s hillside has slumped in several places and erosion created by the creek has
compromised the stability of the maintenance access road and has narrowed the existing
maintenance access road in various locations. Past stream bank stabilization measures
implemented by the City have included rock gabion walls and placing rock rip rap in the
stream, along the stream bank and where the hillside has slumped. Issues with erosion
impacts continue to be a problem for the stream bank and hillside.
Due to the deterioration of the sewer interceptor caused by erosion and slope sloughing
impacts to the sewer line, as well as inadequate manhole access, the City is proposing to
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 5 of 23
make improvements to approximately 2,050 lineal feet of sewer main. The sewer line will be
improved through a mix of parallel HDPE pipelines and rehabilitation of the existing line using
a cured-in-place (CIPP) lining technology. Additionally, due to erosion, slope sloughing and
inadequate width of the maintenance access road, the City is proposing to improve
approximately 37,574 square feet of maintenance access road, and stabilize slopes to help
alleviate potential, future erosion issues.
Approximately 1,205 lineal feet (LF) of 12-inch HDPE sewer line would be installed parallel to
the old line from approximately Station 4+40 to 12+20 and 12+35 to 16+60 utilizing traditional
trench construction methods. The remaining portion of the existing sewer line (approximately
845 LF) will be rehabilitated using CIPP technology. There is also one section of the line that
has a longer than desired spacing between manholes (approximately 1,300), which would
make it difficult to install the CIPP lining, as well as allow the City maintenance of this section.
Thus, another manhole would be installed behind the Berkshire Apartments.
The project includes improving the existing maintenance access road from the portion of the
interceptor south of I-405 to roughly Station 30+83. Station 1+00 to station 7+25 of the
improvements will be narrow (7’ wide) with just enough width to allow the City’s “easement”
machine in this area to perform maintenance. From Station 7+25 south, proposed
improvements include adding a turnaround at Station 7+50, building a new access road
across PSE property at Station 16+00, and rebuilding the entrance road at Station 30+83 (See
Civil Plans dated 9-12-2018). The maintenance access road improvements would encompass
approximately 37,574 square feet. The maintenance access road improvements will be
constructed adjacent to Thunder Hills Creek and will generally be in the existing location of the
maintenance access road. Due to the limited width of the project alignment, the contractor will
be required to utilize small excavation equipment to demolish the existing paved areas and
build the new maintenance access road. The project specifications and plans will detail
measures the contractor will be required to adhere to in excavating, filling, compacting, and
grading the maintenance access road improvements in close proximity to identified streams
and wetlands. Locally imported structural fill will consist of sand and gravel (quarry spall 2” –
4”) and less than 5% fines, with a maximum thickness of 12" and a minimum of 95%
compaction. Approximately the first 150' of the access road entrance will be asphalt paved as
well as a 12' wide access on PSE Parcel No. 2023059013.
Several different structures will be constructed to alleviate future erosion/undercutting of the
roadway and sewer line: Four-foot gabion walls would be constructed on the north side of the
ravine between Stations 1+00 and 2+50. A rock buttress would be constructed utilizing large
quarry rock (4-man size or larger) on the north side of the ravine between Station 2+50 and
Station 5+50. Between Stations 3+80 and Station 5+50 several rockeries would be
constructed on the north and south sides of the ravine. Rockeries will be constructed of Ultra
or ecology block and will be tiered where possible. These structures will all be embedded into
dense native soils or hard sandstone per the Geotechnical Engineer's recommendations for
the project.
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.
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 6 of 23
The project is in the City of Renton, Washington and runs the length of Thunder Hills Creek,
commencing at a gated, paved entrance at the intersection of Grant Avenue South and South
18th Street, extending northwest to I-405. See attached vicinity map.
B. Environmental Elements [HELP]
1. Earth [help]
a. General description of the site:
(circle one): Flat, rolling, hilly, steep slopes, mountainous, other: evidence of past landslide
activity is evident on the west slope of Station 5+50 and 3+50, and in an area north of
Station 2+50 on the west slope.
b. What is the steepest slope on the site (approximate percent slope)?
The slopes extending downward into the Thunder Hills Creek valley between Stations 0+25 and
6+40 are very steep, with magnitudes of 100 to 150 percent. There are localized slope areas
that are near vertical (200 percent magnitude) to overturned due to excavation, sloughing,
and/or landslide activity. Generally, slope magnitudes south of this area range from 40 to 100
percent.
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.
The Natural Resources Conservation Service (NRCS) maps for King County indicate that the
ravine and adjacent side slopes are underlain by Alderwood and Kitsap soils (very steep),
Alderwood gravelly sandy loam (8% to 30% slopes) and Beausite gravelly sandy loam (15% to
30% slopes). There are no agricultural soils on the site.
Soils within the north portion of the site consist of silty-sands and sandy-silts derived from
weathering of the underlying sandstone and siltstone. Toward the south, the soils are silty-sand
with gravel, consistent with glacial till.
d. Are there surface indications or history of unstable soils in the immediate vicinity? If
so, describe.
Yes, there are several areas along the project alignment which show signs of soil movement or
erosion. These are primarily confined to the west side of the ravine north of Station 5+50.
Landslide activity and surface erosion has occurred in this area within the past 50 years
(approximately). The movements include sliding of colluvium and highly weathered bedrock
from the underlying hard bedrock. Slide thicknesses range from 1 to 3 feet in thickness, 10 to 30
feet in width, and up to 40 feet long. Additionally, there is ongoing erosion along the stream
banks and within the channel. In general, the rate of erosion is moderate along some of the
banks and relatively slow within the channel.
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.
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 7 of 23
For the proposed trench construction, suitable native soil excavated from the trenches will be
used as backfill where possible. Locally-sourced, imported fill, consisting of a sand and gravel
mixture with a maximum grain size of 3 inches and less than 5 percent fines, may be
necessary if the native soils are unsuitable in some areas. Additional grading will also occur in
improving maintenance access to the interceptor. Access roads/trails will be regraded for
better maintenance access and to lessen erosion along the existing interceptor alignment.
Rockeries will also be installed as an erosion protection measure in supporting the hillside
adjacent to the maintenance access road. Rock buttresses may also be installed to support
the access road and prevent lateral pipe movements and erosion or undercutting of the sewer
line. Total excavation will be approximately 1,550 cubic yards (cy) of cut and 711 cy of fill.
f. Could erosion occur as a result of clearing, construction, or use? If so, generally
describe.
The potential exists for soil erosion to occur during construction as a result of earth disturbance
associated with clearing, grading, and trench digging. Where soil is exposed or fill material is
stockpiled there is the potential for wind or surface water runoff to pick up soil particles and
transport them off site. Erosion and sediment control measures detailed in Section 8.3 of the
“Rockery Wall Recommendations” report (November 1, 2016) are summarized in B.1.h (below).
Once construction is complete, erosion is not expected as disturbed areas will be re-vegetated
or will be stabilized with gravel.
g. About what percent of the site will be covered with impervious surfaces after project
construction (for example, asphalt or buildings)?
The existing gravel maintenance access road/trail is approximately 27,780 square feet (sf).
Proposed gravel improvements will expand this to approximately 34,161 sf, adding
approximately 6,981 sf of new gravel maintenance access road/trail. The existing portion of the
maintenance access road/trail that is paved (asphalt) is approximately 1,713 sf. Proposed
improvements will expand this paved (asphalt) surface to approximately 5,439 sf, adding
approximately 3,726 sf of new asphalt. The percent of impervious surfaces (asphalt) after
project construction is approximately 5%.
h. Proposed measures to reduce or control erosion, or other impacts to the earth, if any:
To minimize the erosion and sediment runoff impacts from excavation, grading, and trenching
activities required of the project, the work will be performed during the dry season (June through
September). Temporary erosion and sedimentation control (TESC) requirements are detailed in
the construction plans for this project. A stormwater pollution prevention plan (SWPPP) will be
prepared for implementation by the contractor for project construction and will include necessary
TESC Best Management Practices (BMPs) to be incorporated into construction of the project as
applicable. Clearing limits have been defined on the construction plans, and the construction
specifications include provisions detailing suitable construction activities. Any runoff generated
by dewatering discharge will be treated through construction of a sediment trap if there is
sufficient space. If space is limited, other filtration methods will need to be incorporated.
Additional perimeter erosion and sediment control features such as double-silt fencing will be
added to reduce the possibility of sediment entering the surface water. All other trench and
excavation widths and depths will be kept to a minimum during construction. Immediate backfill
of trenches, along with timely restoration, will further reduce erosion potential. Project
specifications also include approved agency permits and associated requirements and timeline
restrictions.
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 8 of 23
2. Air [help] 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.
There will be emissions of dust generated during construction from earth movement and
disturbance. Dust from construction is generally composed of larger particles that settle rapidly.
Dust can be spread over a larger area by strong winds or by construction vehicles entering and
leaving the site. Dust can also be spread by trucks carrying soil either to or from the site during
construction. Given the deep ravine geology of the project location with dense vegetation cover,
the dust is expected to be generally confined to the vicinity of the project area. There will also be
temporary exhaust emissions from construction vehicles and excavation equipment.
Additionally, temporary odor would be generated from the CIPP process which would be
detected in the immediate vicinity of the project. However, these pipes will be installed in a
trenchless manner and covered as quickly as possible, thereby minimizing the duration of the
odor.
b. Are there any off-site sources of emissions or odor that may affect your proposal? If
so, generally describe.
It is possible that some exhaust emissions from I-405, north end of the project, will contribute to
the emissions of construction vehicles during the construction of the project. The project will only
last a few months with minimal construction and truck vehicles added to the area. Annual
average daily traffic (AADT) for I-405 at Mile Post 3.04 (north end of the project), is
approximately 100,000 vehicles (https://www.interstate-guide.com/i-405_aadt.html#washington).
As a result, the emissions from the temporary construction and truck vehicles at this project site
will be orders of magnitude less than that of continuous I-405 vehicle emissions.
c. Proposed measures to reduce or control emissions or other impacts to air, if any:
Measures used to reduce emissions of dust include but are not limited to the following:
• Excessive dust will be reduced by spraying water over the disturbed soil area as needed
throughout the duration of the excavation and maintenance access road improvement process.
• Double-silt fencing will be erected along Thunder Hills Creek to capture any eroded material and
prevent it from reaching the creek.
• A rock spall pad will be constructed at the point(s) of ingress and egress for construction
equipment to help prevent the spread of dust to the adjacent roadways (gated site entrance at
Grant Ave S and S 18th Street and at the cleared PSE easement access along S 18th Street).
• Trucks transporting excavated or fill material will be covered or have adequate
freeboard to prevent dust and particulates from being blown out of the truck.
• Vehicles and equipment will be required to meet all local, state and federal regulations
for emissions.
3. Water [help]
a. Surface Water: [help]
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, wetlands)? If
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 9 of 23
yes, describe type and provide names. If appropriate, state what stream or river it
flows into.
Thunder Hills Creek, seven small tributaries to the creek, and six wetlands occur in the
immediate vicinity of the project site. For the project, Thunder Hills Creek was
designated as Stream A, the remaining tributaries were designated as Streams B-H, and
the six wetlands on site were designated Wetlands A-F (as noted in the Stream and
Wetland Delineation Report (included in SEPA package submittal).
Thunder Hills Creek is a perennial stream that flows north-northwest through the ravine
formed by the creek. The portion of this creek that is adjacent to the project area flows
through the ravine, and eventually crosses under I-405 via a 48” diameter culvert. The
creek becomes Rolling Hills Creek (a tributary of the Black River) which flows through a
combination of storm drain pipes and open channels. connecting to Rolling Hills Creek,
which is a tributary of the Black River. Over time the City of Renton has placed rock
riprap in the channel and positioned rock gabion baskets along portions of the creek
bank to control erosion. The creek is not fish-bearing and there is a total fish passage
barrier in the vicinity of the I-405 crossing.
The tributaries to Thunder Hills Creek are small, seasonally-flowing streams that collect
stormwater runoff, some of which are also fed by groundwater seeps or upstream
wetlands. They generally flow in open channels and are mostly dry during the summer
with the exception of Stream E located in the upstream portion of the project area, which
contained flow during a site visit in August. None of the tributary streams are fish-
bearing.
Wetland A is associated with Stream E and borders the pedestrian trail that runs along
Thunder Hills Creek (the trail forms a partial impoundment of Stream E, which flows
through the wetland). This is a forested, depressional wetland rated as Category 3.
Surface water from Stream E, localized ground water and water impounded by the trail
contribute to the wetland hydrology.
Wetland B is a small riverine wetland that contains forested and emergent vegetation
types. This wetland receives its hydrology from the overbank flooding of Thunder Hills
Creek as well as from localized groundwater. The wetland is rated as a Category 2
wetland.
Wetland C is made up of scrub-shrub and emergent vegetation. It is the only wetland
rated as a Category 4 wetland. This wetland is located on a bench above Thunder Hills
Creek and is disconnected hydraulically. Its hydrology comes from ground water
seepage.
Wetlands D, E and F are all Category 3 wetlands. Wetland D is a small riverine wetland
with emergent vegetation. It receives its hydrology from Thunder Hills Creek and
localized ground water. Wetland E is a disturbed wetland that formed on fill that was
once the stream channel for Thunder Hills Creek. It is a depressional wetland with
scrub-shrub and emergent vegetation. Wetland F has emergent vegetation and is a
slope wetland hydraulically supported by a hillside seep.
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.
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 10 of 23
The proposed project will require work within 200 feet of all above listed streams and
wetlands on site. Work will take place intermittently along the banks of Thunder Hills
Creek (landward of the ordinary high water mark) so that stream bank and maintenance
road stabilization measures can be constructed. Work will also occur in the remaining
stream buffers as well as all of the wetland buffers. Two wetlands will be directly
impacted by fill material (gravel maintenance access path improvement), further
described in 3.a.3 (below).
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.
It will be necessary to remove some material from the Thunder Hills Creek stream bank
in areas that require erosion control improvements such as rock buttresses as discussed
in Section B.1.e. Any imported suitable structural fill (as discussed in Section B.1.e.)
required during this process will be obtained from an approved local vendor. Additionally,
gravel will also be obtained from an approved vendor and will be imported to repair the
existing maintenance access road/trail. Temporary and permanent impacts to wetland
and stream buffers that occur during fill and dredge activities will be mitigated on site
utilizing the planting schedule (various native groundcover, shrubs, and trees) noted in
the Impacts and Mitigation Plan (included in SEPA package submittal), resulting in
approximately 42,945 sf of buffer mitigation through vegetation re-planting.
Wetland E will have approximately 17 sf, and Wetland F will have approximately 1,315 sf
of disturbed area for construction of the proposed interceptor improvements. Wetland F
sits in the original alignment for the access road along the northwest portion of the
interceptor alignment. This wetland appears to be originating from a seep in the trail due
to lack of maintenance of the road, is generally comprised of compacted soil, and has
invasive vegetation (Himalayan blackberry and English ivy) encroaching into this area.
The grading in these wetlands is due to the increasing need to stabilize the area
surrounding Thunder Hills Creek. Proposed improvements have been kept as minimal as
possible. Temporary and permanent impacts to wetland and stream buffers will be
mitigated on site utilizing the planting schedule noted in the Impacts and Mitigation Plan
(included in SEPA package submittal), as well as provide wetland mitigation banking or in
lieu of fee for mitigation of the unavoidable permanent impacts to wetlands and their
buffers.
4) Will the proposal require surface water withdrawals or diversions? Give general
description, purpose, and approximate quantities if known.
The project will not require any surface water withdrawals. Cofferdams will be used to
provide temporary bypass to divert water around the large woody debris installation
areas.
5) Does the proposal lie within a 100-year floodplain? If so, note location on the site
plan.
According to FEMA Firm Map, there is no 100-year floodplain associated with Thunder
Hills Creek.
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.
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 11 of 23
The project would not involve any discharges of waste materials to the streams or
wetlands in the project area, due to proper BMP installation noted in B.1.h and as noted
in the TESC construction plans for the project area.
b. Ground Water: [help]
1) Will groundwater 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 groundwater? Give
general description, purpose, and approximate quantities if known.
No ground water will be withdrawn for drinking water use. In areas where the trenching
will occur below the water table, shallow groundwater may need to be pumped out of the
trench as necessary to complete sewer pipe replacement. In these instances, any
withdrawn ground water would be allowed to infiltrate back into the ground.
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 materials will be discharged into the ground.
c. Water runoff (including stormwater):
1) Describe the 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.
The only sources of runoff are from storm water and temporary discharge from
dewatering activities. Storm water or dewatering water would infiltrate naturally back into
the ground at the project area.
2) Could waste materials enter ground or surface waters? If so, generally describe.
There is a slight potential for minor construction related spills such as drips of oil or fuel if
construction vehicles or equipment are fueled at the site, which could enter ground water
or Thunder Hills Creek. However, measures would be put in place to minimize and
contain any spills.
3) Does the proposal alter or otherwise affect drainage patterns in the vicinity of the
site? If so, describe.
Wetland E will have approximately 17 sf, and Wetland F will have approximately 1,315 sf
of disturbed area for construction of the proposed interceptor improvements. Wetland F
sits in the original alignment for the access road along the northwest portion of the
interceptor alignment. This wetland appears to be originating from a seep in the trail due
to lack of maintenance of the road, is generally comprised of compacted soil, and has
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 12 of 23
invasive vegetation (Himalayan blackberry) encroaching into this area. The drainage
pattern in the vicinity of the site is not anticipated to be affected by the 17 sf of
disturbance in Wetland E due to the small size of that fill. The drainage patter near the
site is also not anticipated to be significantly affected by the 1,315 sf of disturbance in
Wetland F since that wetland is a product of a seep in the trail due to lack of maintenance
in the road and maintenance for the project should help to better direct the water from the
seep into the creek and nearby pervious ground.
d. Proposed measures to reduce or control surface, ground, and runoff water, and
drainage pattern impacts, if any:
The erosion and sediment controls and SWPPP/BMPs noted above (under Section
B.1.h) would control surface water runoff impacts. In addition, any fueling of construction
equipment or vehicles will take place in a designated area away from Thunder Hills
Creek that has containment measures established. Any trucks or construction
equipment will be on site for only as long as they are needed and removed from the area
and vicinity of Thunder Hills Creek and wetlands as soon as possible.
4. Plants [help]
a. Check the types of vegetation found on the site:
_x__ deciduous tree: red alder, bigleaf maple, Oregon ash, hazelnut, Sitka willow
_x__ evergreen tree: fir, cedar, pine,
_x__ shrubs: Indian plum, evergreen blackberry, salmonberry, salal, sword ferns,
ladyfern
_x__ grasses
____ pasture
____ crop or grain
____ Orchards, vineyards or other permanent crops.
_x__ wet soil plants: buttercup, panicled bullrush, skunk cabbage, horsetail, American
speedwell, coastal hedgenettle, fowl mannagrass, impatiens sp.,
reed canarygrass
____water plants:
_x__other types of vegetation: night shade, Himalayan blackberry, English ivy, Japanese
knotweed, youth on age, bigflower tellima
b. What kind and amount of vegetation will be removed or altered?
Vegetation will be removed from the improved maintenance access road/trail areas, at the
turnaround areas, and along the maintenance access road. Most of the vegetation to be
removed consists of ivy, blackberries, ferns, salal, grasses and other shrubs. Additionally, 40
trees (see the Existing Site plans and Critical Areas Report), that are located directly in
grading or maintenance access path areas are proposed to be removed. Approximately 0.9
acres of vegetation will be removed throughout the project area. However, temporary and
permanent impacts to wetland and stream buffers will be mitigated on site utilizing the
planting schedule (various native groundcover, shrubs, and trees) noted in the Impacts and
Mitigation Plan (included in SEPA package submittal), resulting in approximately 42,945 sf of
buffer mitigation through vegetation re-planting.
c. List threatened and endangered species known to be on or near the site.
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 13 of 23
During the wetland delineation in 2015 and in the recent March 2018 site visit by Stantec
biologists, no rare, threatened or endangered plant species were noted. A query of the
Washington Department of Natural Resources Natural Heritage Program Database and site
reconnaissance indicated that there are no rare, threatened or endangered species of plants
are located on or near the site.
d. Proposed landscaping, use of native plants, or other measures to preserve or
enhance vegetation on the site, if any:
Prior to construction, clearing and grading limits will be delineated on plans and onsite to limit
vegetation removal and/or disturbance. Where applicable, any disturbed areas will be
replanted or hydro-seeded and allowed to naturally re-vegetate. Additionally, temporary and
permanent impacts to wetland and stream buffers will be mitigated on site utilizing the
planting schedule noted in the Impacts and Mitigation Plan (included in SEPA package
submittal).
e. List all noxious weeds and invasive species known to be on or near the site.
English ivy, evergreen blackberry and Himalayan blackberry grow along the project route.
5. Animals [help] 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.
Examples include:
birds: hawk, songbirds
mammals: deer, squirrels, mice, voles
fish: non-fish berring stream due to downstream fish passage blockage
b. List any threatened and endangered species known to be on or near the site.
No ESA listed species are known to occur in the immediate vicinity of the project area. A
query of the U.S. Fish and Wildlife IPaC Trust Resources Database (draft report attached
with this application) indicated that four federally threatened species, one federally proposed
threatened species, and 13 species of migratory birds could potentially be located near the
site. The federally threatened species that were noted in the IPaC report include bull trout,
marbled murrelet, streaked horned lark, and yellow-billed cuckoo. The proposed threatened
species that was noted in the IPaC report is the North American wolverine. The database
indicated that there is no critical habitat for any of these species found within the project
location.
The 10 species of migratory birds identified as birds of conservation concern (BCC) that may
be located in the area include: bald eagle, great blue heron, lesser yellowlegs, long-billed
curlew, olive-sided flycatcher, red-throated loon, rufous hummingbird, semipalmated
sandpiper, short-billed dowitcher, and western screech-owl.
c. Is the site part of a migration route? If so, explain.
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 14 of 23
Yes, as the site is located within the Puget Sound region, and the entire Puget Sound region
is part of the Pacific Flyway (https://www.audubon.org/pacific-flyway).
d. Proposed measures to preserve or enhance wildlife, if any:
Although Thunder Hills Creek is not a fish-bearing stream, the cedars from on-site tree
removal will be used to create large woody debris within the creek (an aspect of quality fish
habitat) near the northern end of the site. This will be done in the event that the fish barrier is
somehow removed in the future.
e. List any invasive animal species known to be on or near the site.
There are no known invasive animal species on or near the site.
6. Energy and Natural Resources [help]
a. What kinds of energy (electric, natural gas, oil, wood stove, solar) will be used to meet
the completed project's energy needs? Describe whether it will be used for heating,
manufacturing, etc.
Beyond gasoline and diesel for running construction equipment, no energy resources will be
required for the completed project.
b. Would your project affect the potential use of solar energy by adjacent properties?
If so, generally describe.
The project will require the removal of several trees located within the exiting maintenance
path, within the grading areas, and to make way for the improvements for the maintenance
path. The removal of these trees will decrease the shade coverage for some portions of the
nearby properties, allowing these properties to consider installation of photovoltaic
harnessing of solar energy.
c. What kinds of energy conservation features are included in the plans of this
proposal? List other proposed measures to reduce or control energy impacts, if any:
Construction vehicle idling will be minimized to reduce gasoline and diesel consumption.
7. Environmental Health [help] 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.
There is a potential for spills of oil or fuel to occur from construction equipment or vehicles
during fueling or operations.
1) Describe any known or possible contamination at the site from present or past
uses.
There are no known (past or present) contaminants at the site.
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 15 of 23
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.
A 20” diameter petroleum pipeline owned by BP Olympic Pipeline is located near the
center of the project (at approximately 15+00). The existing sewer interceptor currently
crosses at least two feet beneath the petroleum pipeline alignment, approximately 12
feet below ground surface.
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.
Oil and fuel will be utilized for construction equipment.
4) Describe special emergency services that might be required.
It is not anticipated that any special emergency services will be required by the
completed project. In the event of an emergency, local fire, aid or rescue services and
personnel may be required during construction.
5) Proposed measures to reduce or control environmental health hazards, if any:
Any fueling of construction equipment or vehicles will take place in a designated area
away from Thunder Hills Creek. In the event of an unintentional leak from a construction
vehicle on site, containment measures will be established (e.g., silt fence and/or straw
wattles). Work at the BP Olympic pipeline crossing location will be coordinated with BP
Olympic Pipeline and will adhere to BP Olympic’s construction requirements (including
but not limited to performing vacuum excavation or hand digging within 24-inches of the
pipeline) for that aspect of the proposed project.
b. Noise 1) What types of noise exist in the area which may affect your project (for example:
traffic, equipment, operation, other)?
Typical urban noise (dogs barking, people talking, doors closing) and traffic noise from I-405
can be heard at the project site. However, existing sounds and noise levels will have no
effect on 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 equipment will generate short-term noise increases during regular business
hours only (typically 8am to 5 pm). It is anticipated that work will only occur Monday through
Friday. There will be no long-term noise as a result of the proposed project.
3) Proposed measures to reduce or control noise impacts, if any:
The contractor may implement the following mitigation measures for construction noise:
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 16 of 23
• Construction operations can be scheduled or timed to keep average sound levels
low. Those activities producing the highest noise levels can be scheduled to
coincide with the highest ambient noise levels such as peak traffic periods, as much
as possible.
• Construction hours will be limited to specific times in accordance with City noise
ordinances.
• Equipment will not be left idling when not in use.
8. Land and Shoreline Use [help]
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 actual site is located down within a ravine. Currently the site is utilized as a sewer main
and existing maintenance access road/trail, which runs along Thunder Hills Creek. There are
single-family (across the street on Eagle Ridge Road to the southwest of the project site) and
multi-family residences (along the ravine where the project site is located), as well as open
space/recreation areas surrounding the project alignment. The project area is crossed by
Puget Sound Energy high voltage electrical lines (above ground) and a 20” diameter BP
Olympic petroleum pipeline (approximately 12” beneath the ground surface with at least 2
feet separation between the pipeline and existing sewer). The project will have no effect on
any of the current uses of this site or the adjacent 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?
It is unknown if the site has been used for any agricultural practices or working forest lands in
the past and it is not currently used for those purposes. Given the steep slope nature of the
ravine that the maintenance path and Thunder Hills Creek reside in, it is highly unlikely that
any aspect of the project site has been used as farmland or working forest lands.
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. There are no surrounding working farm or forested lands in relation to the project site.
c. Describe any structures on the site.
There are three foot bridges that cross Thunder Hills Creek and some rock gabion walls
adjacent to Thunder Hills Creek. Up at the top of the ravine, roughly 100+ feet on either side
of the project site, there are several apartment complex buildings far from where the
construction activities will take place.
d. Will any structures be demolished? If so, what?
No structures will be demolished during the construction activities at the project site.
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 17 of 23
e. What is the current zoning classification of the site?
The ravine where the project site resides runs through several tax parcels, the majority of
which are zoned RM-F (residential multi-family), with some vacant RM-F land at the corner of
South 18th Street and Grant Avenue South. The zoning of the small portion of the northern
end of the site is R-8 (residential, 8 dwelling units per acre) as well as vacant.
f. What is the current comprehensive plan designation of the site?
According to the City of Renton COR Maps viewer
(http://rp.rentonwa.gov/HTML5Public/Index.HTML?viewer=CORMaps), the comprehensive
plan designation of the site is residential high density with a small portion at the north end of
the project site designated as residential medium density.
g. If applicable, what is the current shoreline master program designation of the site?
Thunder Hills Creek is not designated as a shoreline environment within Renton’s Shoreline
Master Program or within the City of Renton COR Maps system.
h. Has any part of the site been classified as a critical area by the city or county? If so,
specify.
According to the King County iMap tool (https://gismaps.kingcounty.gov/iMap/), portions of
the project site contain the following environmentally sensitive areas classifications: erosion
hazard and coal mine hazard. The City of Renton sensitive area maps
(http://rp.rentonwa.gov/HTML5Public/Index.HTML?viewer=CORMaps) indicate sensitive
areas cover most of the site and are classified as coal mine, erosion, and landslide hazard
area. The As noted in the Geotechnical Investigation Technical Memorandum (Stantec,
2015), there is evidence of shallow landslide activity along portions of the slow west of the
access maintenance path, and most of the slopes that extend into the Thunder Hills Creek
ravine can be classified as geologically hazardous (steep slope/landslide hazards). The
project site also contains Thunder Hills Creek (classified as a Type Np stream per RMC 4-3-
050.G.7.a), tributary streams and wetlands (as described further in the 2015 Stream and
Wetland Delineation Report for the site), which are classified as critical areas.
i. Approximately how many people would reside or work in the completed project?
Although the project site runs through various privately owned residential multi-family parcels,
the project site is located deep down within a ravine where no people currently reside or work
or will work at the completed project.
j. Approximately how many people would the completed project displace?
The project will not displace any people. The maintenance access path adjacent to the creek
is utilized by pedestrians through most of the project area. Upon completion of the project,
the path can still be accessible both to maintenance equipment as well as local residential
pedestrians.
k. Proposed measures to avoid or reduce displacement impacts, if any:
Not applicable, the project will not displace any people.
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 18 of 23
L. Proposed measures to ensure the proposal is compatible with existing and projected
land uses and plans, if any:
Utility installation, maintenance and use is allowed within the RM-F and R-8 zone
classifications and are considered compatible with applicable land use plans; thus, no
measures are proposed.
m. Proposed measures to reduce or control impacts to agricultural and forest lands of
long-term commercial significance, if any:
Not applicable, as there are no nearby agricultural or forest lands of long-term commercial
significance.
9. Housing [help]
a. Approximately how many units would be provided, if any? Indicate whether high,
middle, or low-income housing.
Not applicable, as the project is a sewer replacement and maintenance access road
improvement, and with no housing affected.
b. Approximately how many units, if any, would be eliminated? Indicate whether high,
middle, or low-income housing.
Not applicable, as the project is a sewer replacement and maintenance access road
improvement, and with no housing affected.
c. Proposed measures to reduce or control housing impacts, if any:
Not applicable, as the project is a sewer replacement and maintenance access road
improvement, and with no housing affected.
10. Aesthetics [help]
a. What is the tallest height of any proposed structure(s), not including antennas; what is
the principal exterior building material(s) proposed?
Not applicable, as no structure, building, or antennas will be constructed for this project.
b. What views in the immediate vicinity would be altered or obstructed?
Not applicable, as all project activities will occur deep down into a ravine along Thunder Hills
Creek, well below any views from the multi-family residences surrounding the ravine.
c. Proposed measures to reduce or control aesthetic impacts, if any:
Not applicable, as there will be no aesthetic impacts because of the project.
11. Light and Glare [help]
a. What type of light or glare will the proposal produce? What time of day would it
mainly occur?
No light or glare will be produced by the project.
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 19 of 23
b. Could light or glare from the finished project be a safety hazard or interfere with
views?
Not applicable, as there will be no light or glare because of the project.
c. What existing off-site sources of light or glare may affect your proposal?
No existing sources of light or glare will affect the proposal.
d. Proposed measures to reduce or control light and glare impacts, if any:
Not applicable, as there will be no light or glare because of the project.
12. Recreation [help]
a. What designated and informal recreational opportunities are in the immediate
vicinity?
Philip Arnold Park, Talbot Hill Reservoir Park, Thomas Teasdale Park, Cedar River Park,
Burnett Linear Park, and Tiffany Park are all located within a mile of the project site. There is
also an open, grassy area on Eagle Ridge Drive near the Eagle Ridge Apartments used for
dog walking. The existing maintenance access road is also currently utilized by local
pedestrians as a walking trail.
b. Would the proposed project displace any existing recreational uses? If so, describe.
The maintenance access road will be temporarily closed and will not be accessible by the
public during construction. Once construction is complete the access road will be re-opened
to public access.
c. Proposed measures to reduce or control impacts on recreation, including recreation
opportunities to be provided by the project or applicant, if any:
No measures are proposed given that the project construction work will be temporary, and
the maintenance access path will be improved and open to public access at completion of
the project.
13. Historic and cultural preservation [help]
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 ? If so, specifically describe.
As part of the 2017 Cultural Resource Assessment Report (Stantec), a 0.5-mile search
radius was used to locate sites within survey proximity of the project area. According to the
Washington Information Sysytem for Architectural and Archeological Records Database
(WISAARD), there are no properties in the vicinity of the project site that are listed on the
National Historic Register. There is one listing on the Washington Heritage Register, Renton
Coal Mine Hoist Foundation, located across I-405 from the project area at the intersection of
Grady Way and South Benson Road.
There are several multi-family residences near the site that have been in place over 50 years
and are eligible for listing but have not been evaluated for eligibility to be included in the
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 20 of 23
historic register. These multi-family residences are clustered to the southwest and northeast
of the project area in proximity to I-405 including along 108th Avenue SE to the south, and
Mill Avenue South, South 6th Street and Cedar Avenue South to the north.
A review of the Department of Archaeology and Historic Preservation’s (DAHP)
archaeological database indicated the presence of two sites in the general project area. The
nearest, an archaeological district associated with past coal mining activity, is located to the
north and outside of the ravine where replacement of the sewer project will take place. The
other site is located to the south of the project site along SR-515.
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.
A review of the DAHP’s WISSARD database did not reveal any evidence of cultural or
historic use or occupation at the project site. The site is located near historic coal mining
activities, but there is no indication that coal mining took place on the site itself. Desktop
analysis and field survey work was conducted by archaeologists in July 2017 to identify
potential cultural material (evidence, artifacts, etc.) or areas of cultural importance on or near
the site. The resulting Cultural Resource Assessment Report (Stantec 2017), was reviewed
and approved by a Registered Professional Archaeologist (RPA). No historic or pre-contact
cultural material was identified within the project area. Previous manipulation of the
landscape for the construction of the sewer lines in 1965 and erosional control and stream
modification has disturbed or displaced any potential cultural material in the project area.
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.
As described in the 2017 Cultural Resource Assessment Report (Stantec), the project area
was surveyed again beginning from the northern end of the project area near I-405. No
cultural material was identified on the surface of the project area or in exposed erosional cut
banks. Only one location was identified as a potential location for a subsurface testing
(shovel test probe [STP]). The DAHP’s WISSARD database was accessed for
archaeological, cultural and historical resources. No consultation was conducted with area
tribes.
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.
No measures are proposed as no disturbance to any resources is anticipated because of the
project.
14. Transportation [help]
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 project site is accessed at the south end of the alignment at the intersection of Grant
Avenue South and South 18th Street.
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 21 of 23
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 closest King County metro bus stop to the project site is located less than ¼ mile to the
south at South Puget Drive and Grant Avenue South.
c. How many additional parking spaces would the completed project or non-project
proposal have? How many would the project or proposal eliminate?
Not applicable, as the project will not add or remove any 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).
The gated sewer maintenance access road will be improved, which is also used as an
unofficial walking trail by the community. No improvements to hard paved roads or state
transportation facilities will be required because of the project.
e. Will the project or proposal use (or occur in the immediate vicinity of) water, rail, or air
transportation? If so, generally describe.
The project does not occur in the immediate vicinity of water, rail or air transportation and will
therefore not utilize any of this type of transportation.
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?
Given that the project is replacement of existing sewer lines, there is not anticipated to be
any needed maintenance activities for the first few years after installation is complete. When
maintenance or monitoring is required, there will be trips to the site for maintenance activities,
involving one or two vehicles perhaps one or two times in a month.
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.
The project would have no effect on agricultural or forest lands.
h. Proposed measures to reduce or control transportation impacts, if any:
No measures are proposed.
15. Public Services [help]
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, the project will not increase the need for public services.
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 22 of 23
b.Proposed measures to reduce or control direct impacts on public services, if any.
Not applicable as the project will not have direct impacts on public services.
16. Utilities [help] a.Circle utilities currently available at the site:
electricity, natural gas, water, refuse service, telephone, sanitary sewer, septic system,
other - tv cable
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 is a sewer utility improvement project of the City of Renton’s existing sewer
system located along Thunder Hills Creek. No additional utility construction or installation
is associated with or proposed for the project.
C. Signature [HELP]
The above answers are true and complete to the best of my knowledge. I understand that the
lead agency is relying on them to make its decision.
Signature: ___________________________________________________
Name of signee: Kristi Rettmann
Position and Agency/Organization: permitting Coordinator - Stantec Consulting Services, Inc.
Date Submitted: October 3, 2018
D. Supplemental sheet for nonproject actions [HELP]
(IT IS NOT NECESSARY to use this sheet for project actions) Because these questions are very general, it may be helpful to read them in conjunction
with the list of the elements of the environment.
When answering these questions, be aware of the extent the proposal, or the types of
activities likely to result from the proposal, would affect the item at a greater intensity or
at a faster rate than if the proposal were not implemented. Respond briefly and in
general terms.
1.How would the proposal be likely to increase discharge to water; emissions to air; pro-
duction, storage, or release of toxic or hazardous substances; or production of noise?
Proposed measures to avoid or reduce such increases are:
2.How would the proposal be likely to affect plants, animals, fish, or marine life?
SEPA Environmental checklist (WAC 197-11-960) July 2016 Page 23 of 23
Proposed measures to protect or conserve plants, animals, fish, or marine life are:
3. How would the proposal be likely to deplete energy or natural resources?
Proposed measures to protect or conserve energy and natural resources are:
4. How would the proposal be likely to use or affect environmentally sensitive areas or
areas designated (or eligible or under study) for governmental protection; such as parks,
wilderness, wild and scenic rivers, threatened or endangered species habitat, historic or
cultural sites, wetlands, floodplains, or prime farmlands?
Proposed measures to protect such resources or to avoid or reduce impacts are:
5. How would the proposal be likely to affect land and shoreline use, including whether it
would allow or encourage land or shoreline uses incompatible with existing plans?
Proposed measures to avoid or reduce shoreline and land use impacts are:
6. How would the proposal be likely to increase demands on transportation or public
services and utilities?
Proposed measures to reduce or respond to such demand(s) are:
7. Identify, if possible, whether the proposal may conflict with local, state, or federal laws or
requirements for the protection of the environment.