12815 19TH AVE SE 2018-01-02 MF Import

EVERETT PUBLIC SCHOOLS SILVER LAKE ELEMENTARY PARKING LOT EXPANSION TARGETED DRAINAGE REPORT Section 1 —Site Drainage Narrative January 6, 2003 Introduction The Silver Lake Elementary School is located in the S4VI/4 of the SW I/4 of Section 32, Township 29, Range 5 East, in Snohomish County, Washington as shown in Figure 1 — Site Vicinity tblap. The Soil Survey of Snohomish County Area Washington identifies site soils on the site as Alderwood -Urban Land Complex. The Everett Public Schools proposes to construct a new parking lot, two new access points, one redeveloped access points, and to provide minor sidewalk, entry, striping and signage improvements. This Targeted Drainage Plan has been prepared in support of SE -PA and Conditional Use Permit documents. Existing Site Conditions The existing School Property Area is just over I I Acres and the existing Lot 7 Area is just over - Acre. Existing structures and site features include a daycare/church facility, five school buildings including one covered play area, three portables, courtyard area, four parking areas, and playGelds. The site is currently accessed from SR-527 in two locations. The school has very limited pedestrian and student access. Existing Area Calculations Approximately 41% and 59% of the Existing PDA is impervious and pervious respectively. Approximately 19% of the Existing PDA is Pollution Generating Impervious Surface (PGIS). Approximately 36% of the Existing PDA is Pollution Generating Pervious Surface (PGPS). Mill See Existing Area Calculations inAppendix A. Section 2 — Risk & Erosion Control Targeted lhainage Report for EverettPublic Schools January 6. 2003 Silver take Elementary Parking Lot Expansion Page 2 of 7 0y: Pencet Engineering