9407 SHARON DR 2018-12-21 - Laserfiche WebLink

Proposed Site Information: 1. How will your project change the existing conditions? It will add 2,893sf of hard surface. 2. Please provide the following quantities of proposed hard surfaces in square feet: Proposed Roof Area: 616sf Proposed Other Hard Surfaces (pavement,gravel,etc.): 2,277sf 3. How will you manage rooftop runoff after the project is completed? We will install gutters,downspouts, and use rain barrels 4. How will you manage stormwater runoff from hard surfaces(driveways; paved pathways, patios,etc.)?Evaluate each type of hard surface separately. Driveway stormwater runoff will go to existing vegetation and overflow will go to street drain. 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 Storm water 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: High groundwater table doesn't allow for underground infiltration facilities, however infiltration will still be promoted.We will use BMP 12.50 Downspout Dispersion for managing stormwater from ro, of d CITY OF EVERETT 13200 Cedar Street I Everett,WA 98201 I 425-257-8810 I everettwa.gov