3317 WETMORE AVE BASE FILE 2020-05-21

Proposed Site Information: 1. How will your project change the existing conditions? Built up and impervious area will be increased. 2. Please provide the following quantities of proposed hard surfaces in square feet: Proposed Roof Area: 2264 square feet. Proposed Other Hard Surfaces(pavement,gravel,etc.): 1796 square feet impervious 3. How will you manage rooftop runoff after the project is completed? Roof drain will be collected and dispersed onto the surface using splash block, will sheet flow through landscaped area twards Wetmore Ave. buffer vegetation. 4. How will you manage stormwater runoff from hard surfaces(driveways, paved pathways, patios,etc.)?Evaluate each type of hard surface separately. Run off from the hard surfaces disperses into the adjacent landscaped/vegetated area and collected by a French drain to be connected to roof drains system. Plan for Permanent On-Site Stormwater Management: You are required to "infiltrate, retain, and disperse stormwater" on your site to the maximum extent you can without causing erosion or flooding.The goal is to get stormwater runoff in contact with vegetated surfaces as much as possible before discharging to downstream conveyance systems. See Volume III, Chapter 12 of the 2010 Stormwater Management Manual for stormwater facility requirements: https://everettwa.gov/DocumentCenter/Home/View/1214 1. Determine which options you must use for managing stormwater from rooftops via downspout disconnect by considering the following Best Management Practices (BMPs) in order: • BMP 12.30 On-site Infiltration Areas • BMP 12.40 Raingardens • BMP 12.50 Downspout Dispersion Notes: a. If location criteria can be met, but sizing criteria cannot,you must implement the BMPs to the maximum extent you can without causing erosion or flooding. Pre-sized facilities have been designed to meet 100% mitigation. Facilities may be able to be installed to achieve some stormwater mitigation. b. Other innovative downspout control BMPs such as rain barrels,ornamental ponds, downspout cisterns, dry wells, or other downspout water storage devices may also be used with prior approval by the City of Everett.These are options to consider after the above listed BMPs are evaluated. 2. Determine which options you must use for managing stormwater from hard surfaces(driveways, paved pathways, etc.) by considering the following for each type of hard surface proposed: • BMP 12.60 Concentrated Flow Dispersion • BMP 12.70 Sheet Flow Dispersion Note: Propose an alternative stormwater management plan if none of the above BMPs can feasibly be installed. (Examples:Shallow vegetated swale, perforated pipe stub-out, etc.) Provide your Evaluation below and Show where these will take place on a site map: ROOF TOPS: --- CP-age �.. ( Page 4 of —8-1) CITY OF EVER_TT 3200 Ceddr Street _verett, WA382( 42.5-257, 8310 ev��et t,. a:gov—