2405 MAPLE ST 2023-06-28 - Laserfiche WebLink

MAPLE ST Section 1 Project Overview This Storm Drainage Report is for the construction of a single-family residence on the property located at 2405 Maple Street, Everett, Washington 98201. More generally,the property is located within Section 20,Township 29, Range 5, W.M. See Vicinity Map below. The site consists of a single parcel (29052000400900) with area of 0.11 acres. The site is bounded by Maple St to the west, a gravel alley to the east and low density residential to the north and south. The site contains an existing single- family residence with impervious rooftop and gravel Garfield Park driveway, as well as a mix of pervious lawn, few trees, and residential landscaping. The existing structures will be demolished, and proposed improvements include construction of a single residence, detached garage (under separate permit) driveway and utility services. 102405 Maple Street Site drainage consists of sheet flow downward to the east and southeast, away from the existing residence. Storm runoff is collected by roof downspouts and are conveyed to the combined sewer system within the alley. This drainage Vicinity Map not to scale pattern will be maintained in the developed condition.There is no upstream basin which contributes runoff to the site. Soils on the subject property were evaluated using the USDA Web Soil Survey.According to the USDA information the site is underlain by "Alderwood-Urban land complex, 2 to 8%slopes". This soil type is categorized as a till soil and is typically not conducive for infiltration. A copy of the USDA Web Soil Survey is included in the Appendix of this report for reference. Drainage elements were designed in accordance with the City of Everett Design and Construction Standards and Specifications for Development section 6-10.1 and 2019 Department of Ecology Stormwater Management Manual for Western Washington (2019 DOE Manual). The project will comply with Minimum Requirements 1-5 for new development as indicated on Figure 1-3.2 Redevelopment Flow Chart, included on the following pages. See below for project totals.Totals were evaluated using best available resources such as site plan, aerial maps and survey. Existing Impervious Onsite 2,227 ft2 Replaced Impervious Onsite 2,227 ft2 New Impervious Onsite 233 ft2 New+ Replaced Impervious Onsite 2,460 ft2 Drainage for the roof area will be mitigated via roof downspouts and footing drains to the combined sewer system per Section 6-10.1 of the COE Design Specifications. JOB#19-336 Storm Drainage Report 1.1