1304 80TH ST SW EVERETT SCHOOL DISTRICT 2018-01-02 MF Import

Everett School District— Bus Facility March 24, 2006 — Storm Drainage Report P E Page 5 III. OFFSITE ANALYSIS Level 1 Downstream Analysis Task 1. Study Area Definition and Maps For purposes of the following tasks 2, 3, 4 and 5, the study area shall extend downstream to a point on the drainage system where the proposed project site constitutes a minimum of 15% of the total tributary drainage area, but not less than 1/4 mile. The 5.2 acre Everett School District project site is comprised of two parcels and is located at 1220 8& Street SW and 1304 80`" Street SW (Tax Parcel #'s 00392200001802, and 00392200001902 respectively) In Everett, WA 98203. This site is furthermore situated within the SW Quarter of Section 11, Township 28 North, Range 4 East, W.M., In Snohomish County, Washington. Task 2. Resource Review A resource review was conducted to determine potential problems downstream of the project site. The following is a list of references used in gathering information for the downstream analysis. • Site Survey by Harmsen Associates, Inc., November 13, 2003 • Snohomish County SCOPI Data • Field Inspections completed by PACE, September 28, 2005 and November 11, 2005. Task 3. Field Inspection A Level 1 downstream analysis was conducted In the early afternoon on November 11, 2005. Weather was cloudy with drizzle and temperatures in the low 40's. Approximately 1/4 to +/x Inch of rain had fallen the previous 24 hours. The downstream analysis was performed to assess potential offsite drainage Impacts associated with development of the project site, and to propose appropriate midgations of those Impacts as necessary. Please see Figure 2 for a map of the downstream flow path. Task 4, Drainage System Description The existing on site stormwater runoff conveyance system currently discharges stormwater at the northeast corner of the project site. The discharged stormwater is released Into an existing wetland located on neighboring property just east of the project site. See Appendix G for further information regarding this wetland. Stormwater exits the wetland toward the north across 80`" Street SW through a 15"concrete culvert for approximately 160 feet. Stormwater flows Into a type 2 catch basin located in the parking lot of the Hot Shots golf range. This catch basin receives flow from the golf