4201 RUCKER AVE COMMUNITY HEALTH CENTER 2019-04-10

Proposed Site Information: 1. How will your project change the existing conditions? As it relates to drainage,the site will not be changed very much at all.We are planning to reuse both catch basins with very little change to the existing paving and drainage patterns. The main parking lot will change orientation, however the drainage patterns will be maintained via surface drainage to the existing catch basins. (See attached Site Drainage Plan.) Parking lot islands will be added in the accessory lot, but not affect the overall drainage to the existing catch basin servicing the lot. 2. Please provide the following quantities of proposed hard surfaces in square feet: Proposed Roof Area: 9,981 SF(No change). Proposed Other Hard Surfaces(pavement,gravel,etc.): 26,015 SF(net loss of impervious surfaces) 3. How will you manage rooftop runoff after the project is completed? There will be no change to the existing system.The current system currently drains via drains(internal to the building)and into the combined sewer system. 4. How will you manage stormwater runoff from hard surfaces(driveways,paved pathways, patios,etc.)?Evaluate each type of hard surface separately. There will not be any major change to the overall management of stormwater runoff.The existing catch basins will be maintained.The overall effect of the changes that we are proposing will actually lessen the amount of impervious surfaces by nearly 900 SF and therefore the amount of stormwater proportionately. 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 Page 4 of CITY OF EVERETT 13200 Cedar Street I Everett, WA 98201 142.5-257-8810 I everettwa.gov ,