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SR_WoldeERC_FINAL
ENVIRONMENTAL REVIEW COMMITTEE REPORT
ERC Meeting Date: April 1, 2024
Project File Number: PR22-000260
Project Name: Wolde Critical Area Restoration
Land Use File Number: LUA24-000040, ECF, CAE
Project Manager: Andrew Van Gordon, Associate Planner
Owner: Elias Wolde, 13701 SE May Valley Rd, Renton, WA 98059
Applicant/Contact: Kerrie McArthur, Confluence Environmental Company, 146 N Canal St Suite 111,
Seattle, WA 98103
Project Location: 13701 SE May Valley Rd, Renton, WA 98059 (APN 3424059113)
Project Summary: The applicant is requesting a Critical Areas Exemption and Environmental Review
for removal of an unpermitted retaining wall, stairs, paved patio and associated site
improvements for the benefit of site restoration. Per COR Maps development
occurred within the 100-year flood hazard area, floodway, sensitive slopes and
protected slopes and their associated buffers. Development also occurred within
the buffer of May Creek; May Creek is classified as a Type F, fish bearing stream.
Proposed restoration is in response to CODE22-000071.
Exist. Bldg. Area SF: 4,920 sq. ft. Proposed New Bldg. Area (footprint):
Proposed New Bldg. Area (gross):
0 sq. ft.
0 sq. ft.
Site Area: 22,771 sq. ft.
(0.52 acre)
Total Building Area GSF: 4,920 sq. ft.
STAFF
RECOMMENDATION:
Staff Recommends that the Environmental Review Committee issue a
Determination of Non-Significance - Mitigated (DNS-M).
DocuSign Envelope ID: ABD8D32C-16ED-4293-9B4E-C0989EDCD6FC
City of Renton Department of Community & Economic Development
Wolde Critical Area Restoration
Staff Report to the Environmental Review Committee
LUA24-000040, ECF, CAE
Report of April 1, 2024 Page 2 of 7
SR_WoldeERC_FINAL
PART ONE: PROJECT DESCRIPTION / BACKGROUND
On March 2, 2022, CODE22-000071 was opened due to a report of a patio along the bank of May Creek (Exhibit
12); May Creek is located on the southern portion of the site A site inspection revealed that an unpermitted patio
area had been constructed within critical areas. Unpermitted work with the critical areas includes a retaining wall,
stairs, clearing, grading and paving. This work occurred on the southern portion of the property on and below a
slope roughly located in the center of the property. A detached dwelling and associated accessory
structures/development occur upslope (north) of the project area.
Per City of Renton (COR) maps this work occurred within the 100-year flood hazard area, floodway, sensitive and
protected slopes. May Creek is classified as a Type F, fish bearing stream and includes habitat conservation areas.
Proposed restoration includes removal of the unpermitted improvements, regrading to before the unpermitted
work was completed, removal of invasive species, retention of native vegetation and replanting of native
vegetation.
PART TWO: 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 Measure
1. The applicant shall provide an Inadvertent Discoveries Plan (IDP) prepared by a qualified
professional. The IDP shall be submitted with the civil construction permit application for review and
approval by the Current Planning Project Manager prior to permit issuance. Notice shall be provided
to Concerned Tribes to have a tribal monitor on-site if archaeological work or monitoring is performed.
C. Exhibits
Exhibit 1: Environmental Review Committee (ERC) Report
Exhibit 2: Site Plan
Exhibit 3: Stream Buffer Revised Mitigation Plan, prepared by Confluence Environmental
Company, dated August 2023
Exhibit 4: Preliminary Arborist Report, prepared by Tree Solutions Inc. dated July 7, 2022
Exhibit 5: SEPA Environmental Checklist
Exhibit 6: Geotechnical Report, prepared by The Concept Group dated January 18, 2023
Exhibit 7: Base Flood Elevation Study, prepared by Aspect Consulting, LLC dated July 28, 2022,
revised October 11, 2023
Exhibit 8: Residential Geotechnical Mitigation Report, prepared by The Concept Group dated
June 27, 2023
Exhibit 9: Critical Area Study, prepared by Confluence Environmental Company dated August
2023
DocuSign Envelope ID: ABD8D32C-16ED-4293-9B4E-C0989EDCD6FC
City of Renton Department of Community & Economic Development
Wolde Critical Area Restoration
Staff Report to the Environmental Review Committee
LUA24-000040, ECF, CAE
Report of April 1, 2024 Page 3 of 7
SR_WoldeERC_FINAL
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: As shown on the site plan (Exhibit 2), unpermitted development occurred within the 115-foot
(115’) critical area stream buffer coming as close as within one-foot (1’) of the ordinary high water
mark (OHWM) of May Creek. Development includes:
• Grading.
• Placement of gravel.
• Placement of flagstone pavers.
• Installation of a stairway from the northern, upper portion of the property down to the
southern, lower portion.
• Installation of two (2) retaining walls: one (1) four-foot (4’) wall at the base of the slope
and a three-foot (3’) tall wall adjacent to May Creek on the south side of the unpermitted
work.
Per the SEPA Environmental Checklist (Exhibit 5) approximately 3,307 square feet of area was graded
for the project. One thousand six hundred and fifty-four (1,654) cubic feet of gravel and 1,082 square
feet of flagstone pavers were placed. This does not include the work completed for the stairs which
included regrading and pavers. Amounts were not included related to work to construct the stairs or
the retaining walls.
Per the geotechnical report, prepared by The Concept Group, dated January 18, 2023 (Exhibit 6)
concurs that development occurred within the defined critical areas. Soil conditions are identified as
Everett very gravelly sandy loam. This soil series consists of gravelly sandy glacial outwash overlaying
glacial till. The slope extending from the upper area where the dwelling is located down to the
unpermitted work is approximately 23 feet (23’) tall with a slope grade of approximately 35 percent
(35%) with a portion in the center of the west side of the slope with grades between 40 and 50 percent
(40-50%). Site observations found that the existing slope and developed conditions to be stable with
no visible morphology of surface or landslide activity and no observed erosion on either bank side of
May Creek due to the activity.
A Base Flood Elevation Study, prepared by Aspect Consulting, LLC (Aspect) dated July 28, 2022 (revised
October 11, 2023) (Exhibit 7) identifies the base flood elevation upstream as 281.9 feet (281.9’) and
downstream as 270.0 feet (270.0’). 2016 LiDAR and a recent survey data were used to develop cross
sections for the unpermitted development. Based on previous LiDAR observations May Creek is
gradually migrating southward. Aspect believes this is a natural process rather than a response to patio
construction. Based on the modeling two (2) instances of base flood elevation rise occurred due to the
Exhibit 10: Duwamish Tribe comment dated March 4, 2024
Exhibit 11: Staff Response to Duwamish Tribe
Exhibit 12: Warning of Violation dated March 8, 2022
Exhibit 13: Advisory Notes
DocuSign Envelope ID: ABD8D32C-16ED-4293-9B4E-C0989EDCD6FC
City of Renton Department of Community & Economic Development
Wolde Critical Area Restoration
Staff Report to the Environmental Review Committee
LUA24-000040, ECF, CAE
Report of April 1, 2024 Page 4 of 7
SR_WoldeERC_FINAL
patio construction; both are on the project property but do not extend off-site. Except for the southern
edge of the patio fill, the unpermitted development is outside of the pre-project floodplain. The
estimated total volume of encroachment fill in the pre-project floodplain is approximately eight (8)
cubic yards.
A follow up Residential Geotechnical Mitigation Report from The Concept Group dated June 27, 2023,
(Exhibit 8) provided recommendations for removal of the unpermitted work and invasive species. An
appropriate erosion control system to collect and filter all surface run off through either silt fencing or
a series of properly placed and secured straw bales; a system of berms and drainage ditches around
construction areas is expected to provide an adequate collection system. As part of the removal of
English Ivy on the slope, it should be removed in stages and replaced with a native deep rooting vine
or ground cover to protect the slope. If all of the ivy is removed at once the face of the slope should be
protected with a jute matt or other erosion blanket material to allow planting on or through the
material. Removal of materials such as the masonry, concrete and backfill will need to occur by hand
with the restored surface vegetated with native species of shrubs and plants with surface armoring
such as logs, rocks, or other natural materials included. To restore the slope grade, the backfill material
used behind the wall should be placed onto the cut and graded to match the existing slope. Backfill
material should be keyed into the slope and compacted to a non-yielding condition. Surface vegetation
should be restored using native, low maintenance deep rooting species. Grades greater than 30
percent (30%) should be covered with jute matting or other surface erosion blanket which will allow
planting through the material. It is anticipated that the City’s Critical Area Regulations and grading
regulations would adequately mitigate impacts of the proposed restoration.
Mitigation Measures: No further mitigation is recommended.
Nexus: Not applicable.
2. Water
a. Wetland, Streams, Lakes
Impacts: May Creek, a Type F stream, is located on the southern portion of the property flowing
from east to west. Type F are waters that are known to be used by fish or meet the physical criteria
to be potentially used by fish and that have a perennial or seasonal flows. A Type F stream has a
115-foot (115’) critical area buffer width with a 15-foot (15’) structure setback beyond the buffer.
Per the Critical Area Study, prepared by Confluence Environmental Company, dated August 2023,
(Exhibit 9) the Washington Department of Fish and Wildlife (WDFW) SalmonScape (2022a) maps
the reach of May Creek within and adjacent to the property have documented presence of coastal
cutthroat trout, steelhead trout with documented spawning of sockeye salmon and coho salmon.
While WDFW does not identify the documented presence of Chinook Salmon, May Creek is listed
as gradient accessible to them. Prior to the unpermitted development, the project area included
small walls along the western and eastern property boundaries with fencing, a brick fireplace, two
(2) black cottonwood trees, sword fern and English ivy on the abutting slope, and various
herbaceous vegetation which appears to have been kept in check through mowing and other
maintenance. Downstream, the riparian area is forested with a mix of black cottonwood, Douglas
fir and western red cedar. The understory is a mixture of native vegetation such as salmonberry,
Indian plum and sword fern with some invasive species such as English Ivy and Himalayan
blackberry. Upstream, the riparian area is forested with a mix of black cottonwood and western
red cedar trees. The understory is sparsely vegetated with a mix of native vegetation such as Indian
plum and sword fern and herbaceous vegetation.
Unpermitted development occurred within the 115-foot (115’) critical area stream buffer coming
as close as within one-foot (1’) of the OHWM of May Creek including grading, fill, installation of
pavers, retaining walls and stairway. Per the SEPA Environmental Checklist, approximately 3,307
square feet of area was graded for the project. One thousand six hundred and fifty-four (1,654)
DocuSign Envelope ID: ABD8D32C-16ED-4293-9B4E-C0989EDCD6FC
City of Renton Department of Community & Economic Development
Wolde Critical Area Restoration
Staff Report to the Environmental Review Committee
LUA24-000040, ECF, CAE
Report of April 1, 2024 Page 5 of 7
SR_WoldeERC_FINAL
cubic feet of gravel and 1,082 square feet of flagstone pavers were placed. This does not include
the work completed for the stairs which included regrading and pavers. Amounts were not
included related to work to construct the stairs or the retaining walls. The Base Flood Elevation
Study identifies the base flood elevation upstream as 281.9 feet (281.9’) and downstream as 270.0
feet (270.0’). 2016 LiDAR and recent survey data were used to develop cross sections for the
unpermitted development. Based on previous LiDAR observations May Creek is gradually migrating
southward. Aspect believes this is a natural process rather than a response to patio construction.
Based on the modeling, two (2) instances of base flood elevation rise occurred due to the patio
construction; both are on the project property and do no extend off-site. Except for the southern
edge of the patio fill, the unpermitted development is outside of the pre-project floodplain. The
estimated total volume of encroachment fill in the pre-project floodplain is approximately eight (8)
cubic yards.
All restoration work would occur within the 115-foot (115’) critical area buffer. Per the Stream
Buffer Revised Mitigation Plan, authored by Confluence Environmental Company, dated August
2023 (Exhibit 3), 7,000 square feet of onsite stream buffer would be impacted. Restoration work
would include removal of the entire patio, retaining walls, stairs and gravel. The area would be
regraded, topsoil will be installed, and native vegetation will be planted. Grading and topsoil
installation would occur in the summer and fall with plantings in the fall. All removal work would
occur by hand with no machines within the 115-foot (115’) critical area buffer. It is anticipated that
the City’s Critical Area Regulations and grading regulations would adequately mitigate impacts of
the proposed restoration.
Mitigation Measures: No further mitigation is recommended.
Nexus: Not applicable.
3. Vegetation
Impacts: Existing vegetation within the critical area buffer include two (2) black cottonwood trees
within the patio area, English ivy, sword ferns and one (1) each of a Douglas fir, Western Redcedar and
a Bigleaf Maple on the slope. Per the Preliminary Arborist Report, prepared by Tree Solutions Inc, dated
July 7, 2022 (Exhibit 4) of these five (5) trees, three (3) are landmark trees: a 42-inch (42”) Diameter at
Breast Height (DBH) Douglas fir, a 39.6-inch (39.6”) DBH Black cottonwood, a 74-inch (74”) DBH Black
cottonwood. The arborist visited the site May 11, 2022.
All five (5) trees are listed in good health condition with fair to good structural condition. The retaining
wall at the bottom of the slope was installed within the tree protection zone (TPZ) of the Douglas Fir.
The stairway was also built adjacent to the tree as close as six inches (6”) from the base. Root
disturbance from the work was observed including one (1) two-inch (2”) diameter root with exposed
damage 10 feet (10’) from the tree base. The retaining wall at the bottom of the slope was constructed
up to the base of the Bigleaf Maple. Based on the cut in the slope the arborist believes the majority of
the structural roots on the south side of the tree were cut possibly as close as right at the tree base.
The two (2) Black cottonwoods had tree wells installed with lighting conduits; the trunk flares were
buried by fill. The original soil level was used as the subbase for patio. Root cuts were observed towards
the creek bed where the retaining wall closest to the creek was constructed. Offsite trees were within
the impacted area. Construction impacts should be limited to six (6) times the DBH in distance from
the trunk of trees to maintain structural stability. The arborist concluded that the majority of the
impacts were outside of this area and likely limited to feeder roots. English ivy is located on the slope
and is climbing the trees.
The on-site trees appear to be in stable condition, however, the exact impacts to all trees are
undetermined at the time of the authoring of the report as there was no documentation of root cutting
during the development nor was an arborist present to monitor construction or assess root impacts.
In the arborist’s experience, trees can take three to five (3-5) years before displaying signs of negative
DocuSign Envelope ID: ABD8D32C-16ED-4293-9B4E-C0989EDCD6FC
City of Renton Department of Community & Economic Development
Wolde Critical Area Restoration
Staff Report to the Environmental Review Committee
LUA24-000040, ECF, CAE
Report of April 1, 2024 Page 6 of 7
SR_WoldeERC_FINAL
impact from construction activity. It is recommended that the invasive English Ivy be removed, the
trees be assessed for retention during demolition with continued assessment during the next three to
five (3-5) years.
As part of the proposed mitigation plan, the English ivy would be removed, and 7,000 square feet of
the critical area buffer would be replanted with native trees, shrubs and herbaceous plants. Proposed
plantings include Western red cedar, Western hemlock, Douglas-fir, Pacific Dogwood, salal, baldhip
rose, red flowering currant, ocean-spray, evergreen huckleberry, bleeding heart, sword fern, western
starflower and meadow seed mix. A five (5) year monitoring and maintenance plan is included with the
mitigation plan. It is anticipated that the City’s Critical Area regulations would adequately mitigate
impacts of the restoration.
Mitigation Measures: No further mitigation is recommended.
Nexus: Not applicable.
4. Historic and Cultural Preservation
Impacts: The City received public comment from the Duwamish Tribe dated March 4, 2024 (Exhibit
10), that the project is located within an area that the Tribe considers culturally significant and has a
moderate probability to have unknown archaeological deposits. The project is located within
approximately two-and-a-half (2.5) miles of two (2) Duwamish place names and adjacent to May Creek.
The DAHP WISAARD predictive model indicates that a survey is recommended with a moderate risk for
encountering cultural resources. As such, the Tribe requests an Inadvertent Discovery Plan (IDP)
especially if excavation cuts below the gravel fill into alluvium. In addition, the Tribe would also like to
be notified if any archaeological work or monitoring is performed and be provided the opportunity to
be present if or when an archaeologist is on site.
The current proposal did not receive comment from the Washington State Department of Archaeology
and Historic Preservation. Due to the proximity to place names and May Creek, staff recommends as a
mitigation measure, that the applicant provide an Inadvertent Discoveries Plan (IDP) prepared by a
qualified professional. The IDP shall be submitted with the civil construction permit application for
review and approval by the Current Planning Project Manager prior to permit issuance. Notice shall be
provided to Concerned Tribes to have a tribal monitor on-site if archaeological work or monitoring is
performed.
Mitigation Measures:
1. The applicant shall provide an Inadvertent Discoveries Plan (IDP) prepared by a qualified
professional. The IDP shall be submitted with the civil construction permit application for
review and approval by the Current Planning Project Manager prior to permit issuance. Notice
shall be provided to Concerned Tribes to have a tribal monitor on-site if archaeological work
or monitoring is performed.
Nexus: City of Renton Comprehensive Goals and Policies, L-AA and L-46; Chapter 27.53 RCW,
Archeological Sites and Resources; Chapter 27.44 RCW, Indian Graves and Records; Chapter 197-11
WAC, SEPA Rules
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).
DocuSign Envelope ID: ABD8D32C-16ED-4293-9B4E-C0989EDCD6FC
City of Renton Department of Community & Economic Development
Wolde Critical Area Restoration
Staff Report to the Environmental Review Committee
LUA24-000040, ECF, CAE
Report of April 1, 2024 Page 7 of 7
SR_WoldeERC_FINAL
Environmental Determination Appeal Process: Appeals of the environmental determination must be filed in
writing on or before 5:00 p.m. on April 15, 2024. 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. 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: ABD8D32C-16ED-4293-9B4E-C0989EDCD6FC
CITY OF RENTON
DEPARTMENT OF COMMUNITY AND ECONOMIC DEVELOPMENT
STAFF REPORT TO THE ENVIRONMENTAL REVIEW COMMITTEE
EXHIBITS
Project Name:
Wolde Critical Area Restoration
Land Use File Number:
LUA24-000040, ECF, CAE
Date of Meeting
April 1, 2024
Staff Contact
Andrew Van Gordon
Associate Planner
Project Contact/Applicant
Kerrie McArthur
Confluence Environmental
Company
146 N Canal St Suite 111,
Seattle, WA 98103
Project Location
13701 SE May Valley Rd, Renton,
WA 98059 (APN 3424059113)
The following exhibits are included with the ERC Report:
Exhibit 1: Environmental Review Committee (ERC) Report
Exhibit 2: Site Plan
Exhibit 3: Stream Buffer Revised Mitigation Plan, prepared by Confluence Environmental Company,
dated August 2023
Exhibit 4: Preliminary Arborist Report, prepared by Tree Solutions Inc. dated July 7, 2022
Exhibit 5: SEPA Environmental Checklist
Exhibit 6: Geotechnical Report, prepared by The Concept Group dated January 18, 2023
Exhibit 7: Base Flood Elevation Study, prepared by Aspect Consulting, LLC dated July 28, 2022, revised
October 11, 2023
Exhibit 8: Residential Geotechnical Mitigation Report, prepared by The Concept Group dated June 27,
2023
Exhibit 9: Critical Area Study, prepared by Confluence Environmental Company dated August 2023
Exhibit 10: Duwamish Tribe comment dated March 4, 2024
Exhibit 11: Staff Response to Duwamish Tribe
Exhibit 12: Warning of Violation dated March 8, 2022
Exhibit 13: Advisory Notes
DocuSign Envelope ID: ABD8D32C-16ED-4293-9B4E-C0989EDCD6FC