6406 HIGHLAND DR 2022-04-19 - Laserfiche WebLink

Proposed Site Information: 1. How will your project change the existing conditions? The project will increase the impervious surface onsite due to a larger house foot print and the addition of a new driveway.The use of the land will stay the same. 2. Please provide the following quantities of proposed hard surfaces in square feet: Proposed Roof Area: 2,708 SF Proposed Other Hard Surfaces(pavement,gravel,etc.): Proposed Driveway=609 SF 3. How will you manage rooftop runoff after the project is completed? The rooftop runoff will be directed to splash blocks for dispersion.The water will flow through natural vegetation and into a small swale.Any large flows can over top into the existing city storm drain.See Drainage Plan for more detail. 4. How will you manage stormwater runoff from hard surfaces(driveways,paved pathways, patios,etc.)?Evaluate each type of hard surface separately. The driveway will be sloped to sheet flow runoff through vegetation and into the onsite swale/stormwater conveyance system.All sidewalks onsite are covered by the roof area. 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 Ill,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.) )