1722 100TH ST SW 2025-11-07 - Laserfiche WebLink

The proposed asphalt driveways (2,535 sf) will take access from 100th Street Southwest off the northern property line and extend to two concrete parking areas (645 sf, see Figure 4). The proposed driveways and parking areas are classified as pollution generating impervious surfaces (PGIS). Stormwater runoff will sheet flow to the south through a 2 ft transition zone and a minimum of 10 ft vegetated flow path per every 20 feet of contributing surface,from the discharge point to the nearest property line, per SMMWW Volume V, Chapter 3, BMP T5.12 and Chapter 11, BMP T5.13. All on-site disturbed areas,not covered with impervious surface,will have amended soils installed as required per SMMWW Volume V, Chapter 11, BMP T5.13. Due to the type of topsoil and existing vegetation on-site, the proposed project will stock pile topsoil for final stabilization. A "Compost and Topsoil Calculation Worksheet for the Pre-Approved Amendment Rate"has been attached to this report for the convenience of the contractor and/or property owner (Refer to Section IV). OFF-SITE ANALYSIS Upstream Analysis: Based on on-site field observations and county contour maps, there is no upstream basin area for the project site (Figure 4: Off-Site Basin Map). Due to the crown in the road, surface stormwater is not expected to flow onto the site from beyond 100th Street Southwest. Downstream Analysis: Stormwater runoff from the site will discharge along the southern property line(See Figure 4). Stormwater runoff will sheet flow through existing grass approximately 65 ft, then southeast, along the northern side of Dakota Way, approximately 55 ft to an existing catch basin(Figure 5: Drainage Inventory Map). The existing municipal storm drainage system conveys Swamp Creek, a Non-fish habitat Seasonal Stream, to the south side of Dakota Way (Figure 6: Stream Inventory Map). Swamp Creek is conveyed south on the surface and through the storm drainage system beyond 1/4 mile from the project site. The downstream flow path consists of developed SFR lots with lawn and landscaping, and greenbelts of native vegetation. The proposed project is not expected to have adverse impacts to downstream properties. COMPLIANCE WITH APPLICABLE MINIMUM REQUIREMENTS Based on SMMWW,Volume 1,Figure I-3.1,and Everett Municipal Code 14.28.030,this proposed new development project will comply with Minimum Requirements #1 through #9 (Figure 7: Minimum Requirements Flow Chart). The purpose of the requirements is to prevent and control adverse impacts of the drainage and stormwater on the public health, safety and general welfare. To meet these requirements, a Construction Stormwater Pollution Prevention Plan (SWPPP) has been provided. The following addresses Minimum Requirements 1 to 9: