3rd party wetland review - creekwood - ESA - 5-9-23
2801 Alaskan Way
Suite 200
Seattle, WA 98121
206.789.9658 phone
206.789.9684 fax
esassoc.com
memorandum
date May 9, 2023
to Evan Lewis, Associate Planner City of Federal Way
from Maggie Bradshaw and Jessica Redman, PWS
subject Creekwood Plat – Wetland and Fish and Wildlife Assessment and Buffer Enhancement Plan
Review
Introduction
At the request of the City of Federal Way (City), Environmental Science Associates (ESA) reviewed the Wetland
and Fish and Wildlife Habitat Assessment and Buffer Enhancement Plan – Creekwood Plat dated December 2022
(hereinafter referred to as the Habitat Assessment) prepared by Soundview Consultants (SVC) for the site located
at the end of 22nd Avenue SW in Federal Way, Washington. ESA biologists also conducted a site visit on March
8, 2023, to assess the site and verify site conditions. The approximately 20-acre forested site is comprised of a
single tax parcel (King County Tax Parcel 1221039037). The parcel is currently undeveloped and contains steep
slopes, wetlands, and streams, including a salmonid-bearing tributary to Lakota Creek. A utility easement is
located along the southern portion of the site. The applicant, Amalani LLC, proposes to subdivide the site into 20
single-family lots with associated infrastructure including internal site access and parking, utilities, and
stormwater infrastructure. ESA reviewed the 2022 Habitat Assessment for compliance with Federal Way Revised
Code (FWRC) Chapter 19.145 – Environmentally Critical Areas. ESA only reviewed wetlands and streams on
the property. Other critical areas, such as geological hazards, are not part of this review.
ESA previously reviewed development application materials for this proposal in December 2017 and March
2021, including earlier versions of the Wetland and Fish and Wildlife Habitat Assessment – Creekwood Plat
(prepared by SVC, dated May 2017 and November 2020). Findings were presented to the City in the technical
memorandum titled Creekwood Plat – Wetland and Fish and Wildlife Assessment Review (dated March 11,
2021).
The focus of this review memorandum (memo) is the Habitat Assessment and accompanying Creekwood
Preliminary Plan Set (developed by Barghausen Consulting Engineers and dated December 21, 2022) and the
Creekwood Preliminary Plat Landscape Plan Set (developed by Barghausen Consulting Engineers and dated
December 22, 2022). ESA’s review was limited to streams and wetlands. The review of other types of critical
areas, such as geological hazards, is outside of this scope. In addition to the Habitat Assessment, ESA reviewed
the following documents for pertinent information about critical areas on the site:
• Limited Phase II Environmental Site Assessment – Tacoma Smelter Plume Soil Sampling, Creekwood
Plat, Earth Solutions NW LLC, August 3, 2022 (Phase II ESA)
Creekwood Plat – Wetland and Fish and Wildlife Assessment and Buffer Enhancement Plan Review
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• Proposed Creekwood Plat Geotechnical Engineering Report, GeoResources, December 30, 2022
(Geotechnical Report)
• Preliminary Technical Information Report – Creekwood, Barghausen Consulting Engineers, January 3,
2023 (TIR)
Summary of Habitat Assessment and Supporting Documentation
Wetland and Fish and Wildlife Habitat Assessment and Buffer Enhancement Plan – Creekwood Plat,
Soundview Consultants, December 16, 2022 (Habitat Assessment)
SVC previously conducted critical area assessments for regulated wetlands, waterbodies, and fish and wildlife
habitat in 2013, 2014, and a follow-up investigation in 2017. The Creekwood Plat project previously received a
Mitigated Determination of Non-significance (MDNS) from the City (File No. 14-100958-00-SE). However,
previous wetland and ordinary high water (OHW) determinations did not receive final approval by the city.
The 2022 Habitat Assessment documented three wetlands (Wetlands B, D, and E/F), three drainages (Drainage
W, X, and Y), one stream (Stream Z), and one non-regulated seep (Seep C) on the site. Additionally, two
wetlands (Wetlands A and G) were identified off-site. All wetlands were classified as Category IV slope wetlands
and assigned 50-foot buffers in accordance with FWRC 19.145.420. Stream Z was classified as a Type F (fish-
bearing) stream; Drainage Y was classified partially as a Type F water to the point where it meets Stream Z, and
as a Type Np (non-fish bearing, perennial) water where the drainage narrows; Drainages W and X were classified
as Type Np waters. Stream Z was assigned a 100-foot buffer and all other drainages were assigned 50-foot
buffers in accordance with FWRC 19.145.270.
No direct impacts to any regulated wetlands or waterbodies are proposed for this project. However, the proposed
project includes 6,115 square feet of impacts to the buffer of Drainage Y as a result of the construction of Road
A, which provides access to the site. Of the 6,115 square feet of impacts, 148 square feet are permanent impacts
and the remaining 5,967 are temporary impacts. The Habitat Assessment includes a buffer enhancement plan that
includes 59,167 square feet of buffer enhancement and an additional 5,967 square feet of buffer restoration
following the temporary impacts. The buffer enhancement strategy for Drainage Y is to remove non-native
species and debris, and plant the understory with native shrubs and groundcover. The northern end of Drainage Y,
around the origination point, will be graded and planted with a native seed mix for erosion control. These
enhancement measures are intended to improve habitat functions as well as water quality functions by limiting
erosion and allowing for better infiltration of precipitation and runoff into the soil. The Habitat Assessment
addresses all criteria under which the city may approve a stream buffer intrusion as listed in FWRC 19.145.330
and mitigation criteria listed in FWRC 19.145.140.
The Habitat Assessment addressed all relevant comments from ESA’s review of the previous report which
included: adding the origination point of Drainage Y to all plan sheets; listing specific best management practices
(BMPs) that will be utilized during construction of the project; details on all applicable local, state, and federal
permits that are anticipated to be required for the proposed project; and a detailed buffer enhancement plan. Other
recommendations made by ESA are no longer relevant due to changes in the project plan. For example, instead of
installing a Geoweb Slope Protection System where Road A crosses the ravine, erosion protection will be
improved by filling, grading, and stabilizing the ravine where Drainage Y is located with a vegetative erosion
control mix.
Creekwood Plat – Wetland and Fish and Wildlife Assessment and Buffer Enhancement Plan Review
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Limited Phase II Environmental Site Assessment – Tacoma Smelter Plume Soil Sampling, Creekwood
Plat, Earth Solutions NW LLC, August 3, 2022 (Phase II Environmental Site Assessment)
A limited Phase II Environmental Site Assessment was conducted on the site to assess potential shallow soil
contamination associated with fallout from the former Asarco Smelter in Tacoma, Washington. The Phase II
Environmental Site Assessment sampling found elevated levels of arsenic above the Model Toxics Control Act
(MTCA) Method A cleanup levels for unrestricted land use in composite duff soils. The Phase II Environmental
Site Assessment recommends that duff across areas planned for residential development be diluted according to
Washington State Department of Ecology (Ecology) guidelines.
Proposed Creekwood Plat Geotechnical Engineering Report, GeoResources, December 30, 2022
(Geotechnical Report)
The Geotechnical report noted that erosion was observed at the northern end of the ravine that begins just south of
the end of 22nd Avenue SW (at the origination of Drainage Y). This erosion appeared to be related to uncontrolled
discharge of stormwater runoff from the adjacent plat, dumping of yard waste into the ravine, and a previous
culvert that discharged above the ravine. Erosion was also observed on the east side of the ravine caused by
exposed, unvegetated soils.
On March 16, 2017, a landslide occurred approximately 700 feet north of the site. However, it was determined
that the topography, surface water runoff, and soil conditions differ in the landslide area from the main
Creekwood Plat site and that the area of the slide should have no impact on the proposed project. The more
steeply sloped portions of the site were identified as erosion hazard areas and landslide hazard areas.
Preliminary Technical Information Report, Barghausen Consulting Engineers, January 3, 2023 (TIR)
The TIR was reviewed for relevant stormwater and hydrology information relating to wetlands. The TIR
indicated that stormwater will be detained onsite within and underground detention vault and treated for water
quality using a Modular Wetland System (or approved equal system). Within the TIR, Modular Wetland System
refers to an engineered biofiltration system that will be installed downflow of the stormwater vault, and not a
regulated wetland. The system will discharge into an existing tightline storm system before it outflows into a
tributary to Lakota Creek. The TIR and Preliminary Sewer and Water Plan (Sheet 9 of the Creekwood
Preliminary Plan Set) show a new conveyance that will connect to an existing storm drain that flows into
Drainage Y. Additionally, runoff created from areas of slope that will be graded to create a level slope will bypass
the detention facility and flow into Drainage Y at the same point of convergence. The detention vault has been
sized to mitigate the bypassed area, and design flow rates for the mitigated developed drainage basin are shown as
less than the predeveloped flow rates. The conveyance system analysis and calculations are not provided in this
report, but the TIR indicates that they will be provided during final engineering.
The TIR does not specifically address potential hydrologic changes to any of the on-site wetlands, though the
project does not plan to add to or change the hydrology of any of the on-site wetlands, or wetlands on adjacent
sites.
Comments and Recommendations
1. ESA agrees with the boundaries of the wetland and stream/drainages, with the exception of the boundary
for Wetland E/F (see bullet below) Flags for wetland boundaries and data plots were confirmed during
the site visit.
Creekwood Plat – Wetland and Fish and Wildlife Assessment and Buffer Enhancement Plan Review
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2.According to the Habitat Assessment, the area for Wetland E/F is listed as 9,351 square feet. This is 308
square feet smaller than the area listed in the 2020 version of the Habitat Assessment. No explanation for
the decrease in size is given, though SVC did note that minor boundary adjustments were made
throughout the site to reflect most recent conditions. During the site visit, ESA biologists observed skunk
cabbage (Lysichitum americanus) and saturated soils along the northern boundary of Wetland E/F, which
match the previously drawn boundary in both size and shape. ESA recommends the previously drawn
boundary be used in the Habitat Assessment and the Preliminary Plan sheets, as it is more similar to the
boundaries observed at the site.
3.ESA agrees with the classification and assigned buffers for the wetlands and stream/drainages, except for
Wetland E/F. Wetlands B, D, and E/F were rated as slope wetlands and scored between 13 and 15 points.
In the review of the rating forms, two points should be added to each of the wetland’s water quality
functions sections. The wetlands discharge to Lakota Creek, which is 303(d)-listed stream for bacteria-
fecal coliform (Listing ID 15830). The site is approximately 10,000 feet upstream of the listed water; and
therefore should receive a point for Questions S 3.1 and S 3.2. The increase of two points did not change
the rating score for Wetlands B and D. However, the additional points changed the score of Wetland E/F
from 14 to 16 points, and from a Category IV to a Category III wetland. Per FWRC 19.145.420(2),
Category III buffers with a habitat score of six, are required a 150-foot buffer. ESA recommends the
Habitat Assessment and the Preliminary Plat sheets be revised to include the correct buffer width for
Wetland E/F.
4.The Preliminary Plat sheets do not show the correct rating category for the wetlands. We note the
following inconsistencies:
o Wetlands B and E/F are labeled as “Cat.II.” Wetland B should be labeled as “Cat. IV.” Wetland
E/F should be labeled as “Cat III” (see #3 above) and the buffer should be increased to 150 feet.
o Wetland D is labeled as “unregulated” but should be labeled as “Cat. IV” and have a 50-foot
buffer.
o The buffer measurement for Lakota Creek near Wetland B is labeled as “100’ Wetland Buffer”
but should be labeled “100’ Stream Buffer.”
ESA recommends the Preliminary Plat sheets be revised to show the correct wetland categories and
buffer widths.
5.ESA believes the buffer enhancement plan to be sufficient to mitigate for permanent and temporary
impacts to the buffer of Drainage Y. Additionally, the buffer enhancement plan complies with the
requirements of FWRC 19.145.330.