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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 2 • 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 3 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 4 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.