Planning 2017-06-22 Item 4 - Foster High School Expansion and Birth to Kindergarten - Attachment D: SEPA Mitigated Determination of Nonsignificance by Tukwila School District (5/9/2017)

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PROPONENT AND LEAD AGENCY: Tukwila School District RESPONSIBLE OFFICIAL: Dr. Judith Berry, Deputy Superintendent & SEPA Official Tukwila School District 4640 South 144th Street Tukwila, WA 98168 berryj(7a,tukwila.wed net. edu The Responsible Official for the Tukwila School District hereby makes the following findings and conclusions based on a review of the environmental checklist and attachments (SEPA Checklist); other information on file with the District and City of Tukwila; and the policies designated by the Tukwila School District as a basis for the exercise of substantive authority under the Washington State Environmental Policy Act (SEPA) pursuant to RCW 43.21C.060. Copies of the documents pertaining to this SEPA MDNS are available for review at the District website at https: // tukwilaschools .org /wp- content/uploads /2017 /01 /SEPANOTICE2017.pdf, or during regular business hours at the Tukwila School District at the address listed above. FINDINGS OF FACT General 1. The SEPA Checklist was made available for public review and comment from January 19, 2017, through February 20, 2017. A Notice of SEPA Consultation was published in the Daily Journal of Commerce, posted on the site, and mailed to interested agencies, property owners, and residents within 500 feet of the property on January 19, 2017. Comments were received from the City Planning, Public Works, and Fire Departments. 2. The Foster High School and Showalter Middle School sites are currently operating as schools and the use will not change as a result of this proposal. The Birth -to- Kindergarten Site is currently District ballfields. Construction of the Foster High School Additions and New Birth -to- Kindergarten Center will begin in winter of 2018. Construction of Showalter Middle School Additions will begin in Spring of 2019. 3. The existing District technology building located on the Foster High School site will be demolished. Four portables (8 classrooms) on the Foster High School site and two portables on the Showalter Middle School site will also be removed. Earth 4. The Foster High School /Showalter Middle School parcel is relatively flat in grade and fully developed, and includes basic landscaping. The Birth -to- Kindergarten Center consists of a flat area with two ballfields and a heavily wooded /sloped area at the far east edge of the parcel. All sites have a thin layer of topsoil with a reworked layer of glacial till underneath that has likely been placed as fill from previous grading. The fill is loose to medium dense, silty sand, with gravel. Intact, dense glacial till was found underlying the fill. Site instability as a result of soils is not expected. 5. According to the City of Tukwila Sensitive Areas Map, small pockets of Type 2 slopes (between 15 and 40 percent) and Type 3 slopes (between 15 and 40 percent composed of relatively impermeable soils, or lopes over 40 percent). No development is proposed within these sensitive areas. 6. For the Foster High School Site there will be approximately 8,760 cubic yards of cut and 6,150 cubic yards of fill. For the Showalter Middle School site, the estimated cut and fill is less than 2,500 cubic yards of fill. For the New Birth -to- Kindergarten Center, there will be an estimated 12,000 cubic yards of cut and 2,000 cubic yards of fill. 7. Foster High School currently has an impervious surface coverage of 64 %, which will be slightly reduced to 63% upon completion. Showalter Middle School is currently 75% impervious and will not change. Birth -to- Kindergarten site is will be approximately 40% impervious upon completion. 104