1427 100TH ST SW 2025-03-03 - Laserfiche WebLink

HUITTZOLLARS HUITT-ZOLLARS,INC. • 1102 Broadway,Suite 301 . Tacoma,WA 98402 . 253.627.9131 phone • 253.627.4730 fax . huitt-zollars.com Lawn and landscape areas: Based on List#1, the project proposes using amended soil for areas of lawn or landscaping and that are not proposed for hard surfaces. Post Construction Soil Quality and Depth BMP T5.13 is proposed for the project.The perimeter of the site is landscaped.The contractor shall retain topsoil on site in a designated, controlled area, not adjacent to public resources and critical areas,to be reapplied to other portions of the site where feasible and where the retained (including if amended)topsoil meets the criteria of BMP T5.13. The retained soil shall be used in areas proposed for landscaping or lawn and shall have a minimum organic content of 10%dry weight in planting beds, and 5%organic matter content in turf areas, and a pH from 6.0 to 8.0 or matching the pH of the undisturbed soil.The topsoil depth must be at minimum 8" unless prevented by tree roots, and the top 4" of underlain soils must be scarified to avoid stratified layer, where feasible. If the retained soil does not meet the criteria of BMP T5.13,the contractor is to amend the retained topsoil to meet requirements. Roofs: The site does not contain a roof. Other Hard Surfaces: • Full Dispersion o The proposed project cannot use Full Dispersion because a native vegetation flow path of sufficient length does not exist onsite. • Permeable Pavement, Rain Gardens, Bioretention o Due to the existing pavement on-site being retained and the slow infiltration rate (see Soils discussion in Section 3 below), infiltration-based LID BMPS are not feasible. • Sheet Flow, Concentrated Flow Dispersion o Runoff from the proposed pavement will be collected in the City storm drain system (curb and gutter to catch basin inlets).There is no opportunity to disperse runoff from the propose new pavement. SECTION 3: EXISTING CONDITIONS SUMMARY Topography and Ground Cover The project area consists of an existing asphalt entry drive that generally slopes southwest.The existing topography ranges from a high in the northeastern corner of the site of approximately 570.8'to a low on the southwestern edge of the site of 566.2'. Land Use and Cover: The project site, as shown on the plans, is largely developed in existing conditions. Existing impervious pavement covers the majority of the project site with landscaping (mostly grass) adjacent to the driveway.The target surface for LID and flow control is the 1,394 SF of new hard surface pavement and sidewalk.There is 1,572 SF of new pollution generating impervious Fairway Estates MHC Entry Huitt-Zollars Stormwater Drainage Report December 15,2023 Everett,Washington Page 3