HomeMy WebLinkAboutERC_Windsor_Court_FINALDEPARTMENT OF COMMUNITY
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Project Location Map
ERC_Windsor Court_FINAL
ENVIRONMENTAL REVIEW COMMITTEE REPORT
ERC Meeting Date: December 8, 2025
Project File Number: PR25-000034
Project Name: Windsor Court Plat
Land Use File Number: LUA25-000148, PP, SA-H, ECF
Project Manager: Jill Ding, Senior Planner
Owner: Huy Tat, Elizabeth G. Tat, and Thuy Bich-Thi Nguyen, 19411 and 19505 108th
Ave SE, Renton, WA 98055
Applicant/Contact: Tom DeDonato, DeDonato Group, LLC, 10257 NE 64th St, Kirkland, WA 98033
Project Location: 19411 & 19505 108th Ave SE, Renton, WA 98055 (APNs 6623400232 &
6623400233)
Project Summary: The applicant is requesting Preliminary Plat approval, Environmental (SEPA)
Review, and Site Plan Review for the subdivision of an existing 111,381-square-
foot (2.56 acre) site into 20 lots for the future construction of single-family
residences and three (3) tracts (Tracts A, B, and C). The project site is
comprised of two (2) parcels located within the Residential-14 (R-14) zone. The
project site is currently developed with two (2) single-family residences and
associated detached accessory structures, all of which are proposed for
removal. Access to the site is proposed via a new 53-foot (53’) wide public right-
of-way off 108th Ave SE (SR 515). In addition, a 16-foot (16’) wide alley access
tract (Tract C) and a 20-foot (20’) wide secondary emergency access tract (Tract
B) are proposed along the northern portion of the property to provide
emergency access. According to COR Maps, a Wellhead Protection Area, Zone
1 Modified and slopes with grades between 15 percent (15%) and 25 percent
(25%) are mapped on the site. A Type F stream (Panther Creek) is mapped
offsite to the east.
Exist. Bldg. Area SF: N/A Proposed New Bldg. Area (footprint):
Proposed New Bldg. Area (gross):
N/A
N/A
Site Area: 111,381 sq. ft.
(2.56 acres)
Total Building Area GSF: N/A
STAFF
RECOMMENDATION:
Staff Recommends that the Environmental Review Committee issue a
Determination of Non-Significance - Mitigated (DNS-M).
Docusign Envelope ID: DF429B06-CA80-4493-87D6-C67576B95CF2
City of Renton Department of Community & Economic Development
Windsor Court Plat
Staff Report to the Environmental Review Committee
LUA25-000148, PP, SA-H, ECF
Report of December 8, 2025 Page 2 of 8
ERC_Windsor Court_FINAL
ENVIRONMENTAL REVIEW
In compliance with RCW 43.21C.240, the following environmental (SEPA) review addresses only those project
impacts that are not adequately addressed under existing development standards and environmental
regulations.
A. Environmental Threshold Recommendation
Based on analysis of probable impacts from the proposal, staff recommends that the Responsible
Officials:
Issue a DNS-M with a 14-day appeal period
B. Mitigation Measures
1. Construction on the project site shall comply with the recommendations of the submitted
Geotechnical Report, prepared by Terra Associates, Inc., dated July 23, 2024, revised December
30, 2024, and any future addenda.
2. The applicant’s geotechnical engineer shall submit a sealed letter stating that he/she has
reviewed the construction permit plans and in their opinion the plans and specifications meet the
intent of the report(s).
3. The applicant’s geotechnical engineer shall provide notes on the construction plans identifying
when on-site geotechnical engineer supervision of construction events is recommended.
4. The applicant shall submit an Inadvertent Discovery Plan prepared by a qualified professional
with the Civil Construction Permit for review and approval by the Current Planning Project
Manager prior to permit issuance. The applicant shall provide notification to Tribes’ cultural
committee prior to the start of construction.
C. Exhibits
Exhibit 1: Environmental Review Committee (ERC) Report
Exhibit 2: Conceptual Civil Plan Set, prepared by ESM Consulting Engineers, Inc., dated
November 11, 2025
Exhibit 3: SEPA Environmental Checklist
Exhibit 4: Geotechnical Report, prepared by Terra Associates, Inc., dated July 23, 2024,
revised December 30, 2024
Exhibit 5: Critical Areas & Stream Study, prepared by Wetland Resources, Inc., dated
February 4, 2025
Exhibit 6: Preliminary Technical Information Report (TIR) and Level 1 Downstream Analysis,
prepared by ESM Consulting Engineers, LLC, dated April 1, 2025, revised
November 11, 2025
Exhibit 7: Trip Generation, Trip Distribution, and Scoping Memorandum, prepared by
Kimley-Horn and Associates, Inc. (Kimley-Horn), dated November 18, 2024
Exhibit 8: Email Correspondence with the City of Kent
Exhibit 9: Washington State Department of Ecology (DOE) Comment Letter, dated June 4,
2025
Exhibit 10: Washington State Department of Ecology (DOE) City Email Response, dated June
4, 2025
Docusign Envelope ID: DF429B06-CA80-4493-87D6-C67576B95CF2
City of Renton Department of Community & Economic Development
Windsor Court Plat
Staff Report to the Environmental Review Committee
LUA25-000148, PP, SA-H, ECF
Report of December 8, 2025 Page 3 of 8
ERC_Windsor Court_FINAL
Exhibit 11: Duwamish Tribe Comment Letter, dated May 23, 2025
Exhibit 12: Duwamish Tribe City Email Response, dated June 2, 2025
Exhibit 13: King County Public Health Comment Letter, received June 4, 2025
Exhibit 14: King County Public Health City Email Response, dated June 6, 2025
Exhibit 15: Washington State Department of Transportation (DOT) Comment Form, dated
June 10, 2025
Exhibit 16: Washington State Department of Transportation (DOT) City Email Response,
dated June 12, 2025
Exhibit 17: Transportation Concurrency Test Memorandum, dated May 30, 2025
Exhibit 18: Advisory Notes
D. Environmental Impacts
The Proposal was circulated and reviewed by various City Departments and Divisions to determine
whether the applicant has adequately identified and addressed environmental impacts anticipated to
occur in conjunction with the proposed development. Staff reviewers have identified that the proposal is
likely to have the following probable impacts:
1. Earth
Impacts: The applicant submitted a Geotechnical Report, prepared by Terra Associates, Inc.,
dated July 23, 2024, revised December 30, 2024 (Exhibit 4), with the project application materials.
According to the submitted report, the site topography is relatively flat, with the exception of the
northeastern site corner, which slopes gently to moderately down to the northeast at an
approximate slope of 14-16 percent (14-16%). The southeastern portion of the project site abuts
an existing five to six-foot (5’-6’) high rockery along the 108th Ave SE right-of-way. Site vegetation
generally consists of grass lawn, landscape trees and shrubs, and mature coniferous trees. Total
earthwork proposed for the project construction would include approximately 7,602 cubic yards
of cut and 3,612 cubic yards of fill (Exhibit 3). Two (2) residences and a detached accessory
building are located on the north parcel and a single-family residence and detached accessory
building are located on the south parcel. All existing structures are proposed for removal.
Subsurface conditions were evaluated by excavating seven (7) test pits (TP-1 to TP-7) to depths
ranging from about seven feet (7’) to eight feet (8’) below the existing ground surface (bgs). The
native soils observed in the test pits were till-like glacial deposits consisting of silty sand with
gravel. The upper approximately one and one-half feet (1.5’) to two and one-half feet (2.5’) of soil
were generally in a medium dense and moist condition. Exceptions were observed in TP-2, where
the upper approximately five feet (5’) of soil was medium dense and dry, and in TP-3 where the
upper two and one-half feet (2.5’) of soil was moist to wet. The soils observed below these depths
were generally dense to very dense, weakly to strongly cemented, and moist. Approximately one
and one-half feet (1.5’) of medium dense, moist, silty sand with gravel fill overlying the native
deposits was observed in TP-1. The fill at this location appeared to be related to grading within the
yard area along the east side of the existing residence.
Ground water seepage was not observed in any of the test pits. However, mottling was observed
in the soils between depths of about one and one-half feet (1.5’) and four feet (4’), indicating that
they have been impacted by perched groundwater at times. The occurrence of shallow perched
groundwater is typical for sites underlain by relatively impermeable till and till-like soils. Perched
groundwater levels typically fluctuate with the highest levels anticipated during the wet winter
months.
Docusign Envelope ID: DF429B06-CA80-4493-87D6-C67576B95CF2
City of Renton Department of Community & Economic Development
Windsor Court Plat
Staff Report to the Environmental Review Committee
LUA25-000148, PP, SA-H, ECF
Report of December 8, 2025 Page 4 of 8
ERC_Windsor Court_FINAL
The geotechnical report included recommendations for site preparation and grading,
excavations, foundations, slab-on-grade floors, retaining walls, drainage, utility trenches, and
new pavement design. Staff recommends, as SEPA mitigation, that construction on the project
site comply with the recommendations of the submitted Geotechnical Report, prepared by Terra
Associates, Inc., dated July 23, 2024, revised December 30, 2024, and any future addenda. In
addition, staff recommends, as a mitigation measure, that the applicant’s geotechnical engineer
submit a sealed letter stating that he/she has reviewed the construction permit plans and in their
opinion the plans and specifications meet the intent of the report(s). Lastly, staff recommends,
as a mitigation measure, that the applicant’s geotechnical engineer provide notes on the
construction plans identifying when on-site geotechnical engineer supervision of construction
events is recommended.
Mitigation Measures:
1. Construction on the project site shall comply with the recommendations of the submitted
Geotechnical Report, prepared by Terra Associates, Inc., dated July 23, 2024, revised
December 30, 2024, and any future addenda.
2. The applicant’s geotechnical engineer shall submit a sealed letter stating that he/she has
reviewed the construction permit plans and in their opinion the plans and specifications meet
the intent of the report(s).
3. The applicant’s geotechnical engineer shall provide notes on the construction plans
identifying when on-site geotechnical engineer supervision of construction events is
recommended.
Nexus: State Environmental Policy Act (SEPA) Environmental Review; and RMC 4-4-060 Grading,
Excavation, and Mining Regulations.
2. Air
Impacts: It is anticipated that some temporary air quality impacts could be associated with site
work required to develop this site. Project development impacts during construction would
include primarily particulate matter and small amounts of carbon monoxide and oxides of
nitrogen, resulting from grading and exhaust from construction vehicles. Dust control would be
mitigated using temporary erosion control measures. A Temporary Erosion and Sedimentation
Control (TESC) plan and system would be developed and submitted to the city in accordance with
the city’s development regulations and with the Department of Ecology (DOE) Construction
Stormwater Pollution Prevention Plan (SWPPP). Should construction activities be undertaken
during the dry season, periodic watering, if necessary, could be implemented to control dust.
Following construction, vehicle emissions in the form of carbon monoxide and oxides of nitrogen
associated with the proposed residential development are anticipated to be very low. No further
site-specific mitigation for the identified impacts from typical vehicle and construction exhaust is
required.
Mitigation Measures: No further mitigation recommended.
Nexus: Not applicable.
3. Water
a. Surface Water (including streams, rivers, wetlands, lakes)
Impacts: A Critical Areas & Stream Study, prepared by Wetland Resources, Inc., dated
February 4, 2025 (Exhibit 5), was submitted with the project application materials. According
to the submitted study, no wetlands or streams are located within the boundaries of the
project site. Panther Creek, a Type F Stream, was observed approximately 155 feet (155’)
Docusign Envelope ID: DF429B06-CA80-4493-87D6-C67576B95CF2
City of Renton Department of Community & Economic Development
Windsor Court Plat
Staff Report to the Environmental Review Committee
LUA25-000148, PP, SA-H, ECF
Report of December 8, 2025 Page 5 of 8
ERC_Windsor Court_FINAL
north of the site and 106 feet (106’) east of the site, across 108th Ave SE. Panther Creek is
identified in existing available resources as providing habitat for both Coho and Coastal
Cutthroat. RMC 4-3-050 designates a 115-foot (115’) buffer and a 15-foot (15’) building
setback from the flagged ordinary high water mark (OHWM) of Type F Streams. In situations
where a stream enters a culvert, the buffer is measured perpendicular to its OHWM from the
end of the pipe along the open channel of the stream. Per RMC 4-3-050B.1.g no buffer is
projected onto the site from the portion of Panther Creek that is separated from the site by
108th Ave SE, a pre-existing road which separates the property from the critical area and
substantially prevents the upland property’s ability to perform buffer functions. To the north
of the site, the nearest portion of Panther Creek is approximately 155 feet (155’) from the
project site, which exceeds the 115-foot (115’) buffer and 15-foot (15’) building setback
requirement. No buffer is projected onto the subject site from Panther Creek. As a result, the
proposed development is not anticipated to have any impacts on the functions and values of
Panther Creek. No further mitigation is recommended.
Mitigation Measures: No further mitigation recommended.
Nexus: Not applicable.
b. Water Runoff (including stormwater)
Impacts: The applicant submitted a Preliminary Technical Information Report (TIR) and Level
1 Downstream Analysis, prepared by ESM Consulting Engineers, LLC, dated April 1, 2025,
revised November 11, 2025 (Exhibit 6), with the application. According to the City of Renton
Surface Water Design Manual (RSWDM), the project is located within the Conservation Flow
Control Area, matching forested site conditions, and is required to comply with Level 2 Flow
Control Standards. The site is also located within the Enhanced Basic Water Quality
treatment area. The downstream corridor consists of two (2) flow paths which do not combine
within one-quarter (1/4) mile downstream. Therefore, the project site contains two (2)
Threshold Discharge Areas (TDA #1 & TDA #2).
Stormwater discharging from the site at the northeast corner of the property (TDA #1) drains
into the 108th Ave SE right-of-way, sheet flows overland for approximately 15 feet (15’), and
then enters the City of Kent’s public storm system, a closed conveyance system located
beneath the street. This stormwater is then conveyed north along the conveyance system for
approximately 215 feet (215’) before draining into Panther Creek, a Type F stream. The
stormwater continues flowing north along the creek until reaching a distance of one-quarter
(1/4) mile downstream from the project site. Panther Creek eventually drains into Springbrook
Creek, which is a tributary of the Duwamish River.
Stormwater discharging from the site at the southwest corner of the property (TDA #2) drains
across 107th Ave SE (a private street) and enters a ditch on the west side of the street. These
flows are then conveyed south through a series of ditch and pipe elements to SE 196th St, and
then west along the street, eventually reaching the Springbrook Watershed. The flows are
conveyed further west through a conveyance pipe until reaching a distance of one-quarter
(1/4) mile downstream from the project site. These flows ultimately drain to North Fork
Springbrook Creek which drain to Springbrook Creek, a tributary to the Duwamish River.
A stormwater deviation application is being submitted to the City of Kent to request the
allowance of stormwater discharge from the site to be made at TDA #1 to 108th Ave SE
because the property is not allowed to discharge to the private road, 107th Ave SE. All runoff
generated from the developed basin is proposed to discharge to the City of Kent’s existing
public storm system located near the northeast corner of the site.
Docusign Envelope ID: DF429B06-CA80-4493-87D6-C67576B95CF2
City of Renton Department of Community & Economic Development
Windsor Court Plat
Staff Report to the Environmental Review Committee
LUA25-000148, PP, SA-H, ECF
Report of December 8, 2025 Page 6 of 8
ERC_Windsor Court_FINAL
Stormwater runoff from the proposed development would be collected in a series of catch
basins and routed via pipe conveyance systems to a stormwater detention vault within Tract
A. Pollution-generating surfaces would be routed to a proprietary enhanced media filter
system for water quality treatment. The detained and treated discharge will discharge to the
existing public system located near the northeast corner of the site.
The project proposal would be required to comply with the 2022 City of Renton Surface Water
Design Manual (RSWDM). It is anticipated that any impacts to surface water flows would be
adequately mitigated through the RSWDM, therefore no further mitigation is recommended.
Mitigation Measures: No further mitigation recommended.
Nexus: Not applicable.
4. Environmental Health
a. Environmental Health Hazards
Impacts: Staff received comments from the Washington State Department of Ecology (DOE)
(Exhibit 9) during the public comment period. Ecology records show there is an existing 500-
gallon, steel, underground storage tank (UST) located on the property within the area of
proposed work. The 500-gallon tank was closed in place as of May 7, 1986. It was requested
that the SEPA Environmental Checklist be updated to add the UST information to Section B.
Environmental Elements, Subsection 7 Environmental of the SEPA Checklist. As requested,
the applicant updated the Checklist (Exhibit 3) to include this information, and the Checklist
was re-sent to DOE. DOE further advised that the applicant would be subject to all regulations
per WAC 173-360A (notify the department of removal and perform a site assessment) if the
tank is removed as part of this project. It is anticipated that the appropriate regulatory
permitting requirements would adequately mitigate for impacts to the site regarding the
existing UST. Therefore, no further mitigation is recommended.
Mitigation Measures: No further mitigation recommended.
Nexus: Not applicable.
b. Noise
Impacts: During project construction, noise levels would temporarily increase near the
construction activity due to heavy equipment use and construction materials transport. It is
anticipated that any temporary or permanent noise impacts would be adequately mitigated
through the city’s adopted Noise Regulations, and thus, no further mitigation is
recommended.
Mitigation Measures: No further mitigation recommended.
Nexus: Not applicable.
5. Historic and Cultural Preservation
Impacts: No archaeological studies were submitted with the project application materials. Staff
did receive comments from the Duwamish Tribe (Exhibit 11) requesting that an archaeological or
cultural resources assessment, followed by an Inadvertent Discovery Plan (IDP), be prepared
prior to proposed construction activities due to the potential for archaeological resources being
discovered on the project site. To ensure that any archaeological deposits are managed
appropriately, staff recommends, as a SEPA mitigation measure, that the applicant submit an
Inadvertent Discovery Plan prepared by a qualified professional with the Civil Construction Permit
for review and approval by the Current Planning Project Manager prior to permit issuance. The
applicant shall provide notification to Tribes’ cultural committee prior to the start of construction.
Docusign Envelope ID: DF429B06-CA80-4493-87D6-C67576B95CF2
City of Renton Department of Community & Economic Development
Windsor Court Plat
Staff Report to the Environmental Review Committee
LUA25-000148, PP, SA-H, ECF
Report of December 8, 2025 Page 7 of 8
ERC_Windsor Court_FINAL
Mitigation Measures: The applicant shall submit an Inadvertent Discovery Plan (IDP) prepared
by a qualified professional with the Civil Construction Permit for review and approval by the
Current Planning Project Manager prior to permit issuance. The applicant shall provide
notification to Tribes’ cultural committee prior to the start of construction.
Nexus: City of Renton Comprehensive Plan Goals and Policies LU-AA, LU-44, and LU-45; Chapter
27.53 RCW, Archaeological Sites and Resources; Chapter 27.44 RCW, Indian Graves and
Records; Chapter 197-11 WAC, SEPA Rules; and Duwamish Tribe Comment, dated May 23, 2025.
6. Transportation
Impacts: A Trip Generation, Trip Distribution, and Scoping Memorandum, prepared by Kimley-
Horn and Associates, Inc. (Kimley-Horn), dated November 18, 2024 (Exhibit 7), was submitted
with the project application materials. The memo concluded that the proposed project would
result in eleven (11) net new AM and fifteen (15) net new PM peak hour trips. Access to the site
would be provided via a new public road off 108th Ave SE, which is a City of Kent public right-of-
way. The City of Kent has indicated that the proposed access off 108th Ave SE would require the
approval of a Deviation Request to Construction Standards Permit (REDR) from the 2021 City of
Kent Construction Standards. The applicant has submitted an application for the required
Deviation Request to the City of Kent and the application is currently under review.
Comments were received from the Washington State Department of Transportation (WSDOT)
(Exhibit 15) stating that design documentation and a developer agreement would be required for
any roadway impacts to 108th Ave SE (State Route 515) and requesting that the applicant reach
out to WSDOT for coordination. These comments were provided to the applicant, and thus, it
would be the applicant’s responsibility to obtain any and all necessary approvals from WSDOT
prior to the issuance of a Construction Permit.
Project construction is anticipated to begin in early 2026 and end in the middle of 2026.
Construction activity is proposed on weekdays between the hours of seven o’clock (7:00) a.m.
and eight o’clock (8:00) p.m.
A Transportation Concurrency Test (Exhibit 17) was issued for the proposal. It was concluded that
the proposal passed the Transportation Concurrency Test in accordance with RMC 4-6-070D. It
is anticipated that any new trips generated by the proposal would be adequately mitigated
through the payment of applicable Transportation Impact Fees at the time of Building Permit
issuance. Therefore, no further mitigation is recommended.
Mitigation Measures: No further mitigation recommended.
Nexus: Not applicable.
E. Comments of Reviewing Departments
The proposal has been circulated to City Department and Division Reviewers. Where applicable, their
comments have been incorporated into the text of this report and/or “Advisory Notes to Applicant.”
✓ Copies of all Review Comments are contained in the Official File and may be attached to this
report.
The Environmental Determination decision will become final if the decision is not appealed within the
14-day appeal period (RCW 43.21.C.075(3); WAC 197-11-680).
Environmental Determination Appeal Process: Appeals of the environmental determination must be
filed in writing on or before 5:00 p.m. on December 23, 2025. Appeals must be submitted electronically to
the City Clerk at cityclerk@rentonwa.gov or delivered to City Hall 1st floor Lobby Hub Monday through Friday.
Docusign Envelope ID: DF429B06-CA80-4493-87D6-C67576B95CF2
City of Renton Department of Community & Economic Development
Windsor Court Plat
Staff Report to the Environmental Review Committee
LUA25-000148, PP, SA-H, ECF
Report of December 8, 2025 Page 8 of 8
ERC_Windsor Court_FINAL
The appeal fee, normally due at the time an appeal is submitted, will be collected at a future date if your
appeal is submitted electronically. The appeal submitted in person may be paid on the first floor in our
Finance Department. Appeals to the Hearing Examiner are governed by RMC 4-8-110 and additional
information regarding the appeal process may be obtained from the City Clerk’s Office,
cityclerk@rentonwa.gov.
Docusign Envelope ID: DF429B06-CA80-4493-87D6-C67576B95CF2
CITY OF RENTON
DEPARTMENT OF COMMUNITY AND ECONOMIC DEVELOPMENT
STAFF REPORT TO THE ENVIRONMENTAL REVIEW COMMITTEE
EXHIBITS
Project Name:
Windsor Court Plat
Land Use File Number:
LUA25-000148, PP, SA-H, ECF
Date of Meeting
December 8, 2025
Staff Contact
Jill Ding
Senior Planner
Project Contact/Applicant
Tom DeDonato
DeDonato Group, LLC
10257 NE 64th St, Kirkland,
WA 98033
Project Location
19411 & 19505 108th Ave SE,
Renton, WA 98055 (APNs
6623400232 & 6623400233)
The following exhibits are included with the ERC Report:
Exhibit 1: Environmental Review Committee (ERC) Report
Exhibit 2: Conceptual Civil Plan Set, prepared by ESM Consulting Engineers, Inc., dated November
11, 2025
Exhibit 3: SEPA Environmental Checklist
Exhibit 4: Geotechnical Report, prepared by Terra Associates, Inc., dated July 23, 2024, revised
December 30, 2024
Exhibit 5: Critical Areas & Stream Study, prepared by Wetland Resources, Inc., dated February 4,
2025
Exhibit 6: Preliminary Technical Information Report (TIR) and Level 1 Downstream Analysis,
prepared by ESM Consulting Engineers, LLC, dated April 1, 2025, revised November 11,
2025
Exhibit 7: Trip Generation, Trip Distribution, and Scoping Memorandum, prepared by Kimley-Horn
and Associates, Inc. (Kimley-Horn), dated November 18, 2024
Exhibit 8: Email Correspondence with the City of Kent
Exhibit 9: Washington State Department of Ecology (DOE) Comment Letter, dated June 4, 2025
Exhibit 10: Washington State Department of Ecology (DOE) City Email Response, dated June 4, 2025
Exhibit 11: Duwamish Tribe Comment Letter, dated May 23, 2025
Exhibit 12: Duwamish Tribe City Email Response, dated June 2, 2025
Exhibit 13: King County Public Health Comment Letter, received June 4, 2025
Exhibit 14: King County Public Health City Email Response, dated June 6, 2025
Exhibit 15: Washington State Department of Transportation (DOT) Comment Form, dated June 10,
2025
Exhibit 16: Washington State Department of Transportation (DOT) City Email Response, dated June
12, 2025
Exhibit 17: Transportation Concurrency Test Memorandum, dated May 30, 2025
Exhibit 18: Advisory Notes
Docusign Envelope ID: DF429B06-CA80-4493-87D6-C67576B95CF2