4320 THOMSON AVE 2023-08-10 - Laserfiche WebLink

Thomson Residence March 5, 2021 Stormwater Site Plan Report Section I, Page 1 Section I — Project Overview Section I Summary Narrative Existing Conditions Developed Conditions Minimum Requirements The proposed project consists of the construction of a single-family residential building with an associated driveway and rockery on a 0.21 ac lot located in Everett, WA. This report has been written in accordance with the Everett Design and Construction Standards and Specifications (herein referred to as the Everett Manual) and the 2014 Department of Ecology Stormwater Management Manual for Western Washington (herein referred to as the SWMMWW). The project will have a total of 3,723 sf of new/replaced hard surfaces and have 6,452 sf of total land disturbance. There is an existing house, driveway, and associated walkways on site which will be demolished. The project is in the combined sewer area of Everett and will abide by the design requirements of Chapter 6.10 of the Everett Manual. In addition, the project is required to address Minimum Requirements #1-9 of the SWMMWW since it adds less than 5,000 sf of new/replaced hard surface area. A full Department of Ecology (DOE) Stormwater Pollution Prevention Plan (SWPPP) is not required since the project parcel is less than an acre. Site Address: 4320 Thomson Dr, Everett, WA 98203 Parcel Number: 00605501600303 Zoning: R-1 Watershed: Combined Sewer Existing Conditions The existing site is a developed parcel of 0.21 ac with a small single family residential building and an associated walkway and driveway. The existing house, driveway, and walkways are located on the northeast quadrant of the site, and the rest of the site remains undeveloped. The site is entirely on a steep slope which slopes up to the west from Thomson Dr. The site borders single family residences to the north, south, and west and borders Thomson Dr. to the east. The developed area of the site is landscaped with grass and a few shrubs, and the rest of the site is overgrown with blackberry bushes and native vegetation. All existing improvements on -site will be demolished in the proposed condition. Developed Conditions I,n the developed condition, the project will demolish the existing house, driveway and walkway and clear the entire eastern half of the property for construction. A new single-family residence will be constructed with an attached garage, driveway, and rockery. Soils on -site were found to be well -drained, and the Geotech report found infiltration to be feasible. However, due to horizontal site constraints, infiltration 250 4th Avenue South, Suite 200 Edmonds, WA 98020 ENGINEERING ph. 425.778.8500 1 C 425.778.5536 www.cgengineering.com