2021 LEXINGTON AVE 2018-03-07 - Laserfiche WebLink

. 1. PROJECT OVERVIEW This document is intended to provide engineering information necessary to support the building permit application to the City of Everett for the new duplex and driveways proposed on this lot. The site is located at 2021 Lexington Ave SE, Everett, WA 98203; refer to Figure 1 for a vicinity map. The parcel area is approximately 0.22 acres. The site is developed and contains an existing SFR (to be replaced with the new duplex), driveway (to be removed) and a couple sheds. Oaks Ave right-of-way runs along the east side of the property and Lexington Ave right-of-way runs along the south side of the property. The slope of the site is flat to moderate averages approximately 7 percent down to the east. The proposed duplex will be located approximately 30 feet from the existing alley to the west. The proposed driveways will take access from the existing alley to the west. This project proposes to construct less than 5,000 sf of new impervious surfaces with the net increase in impervious surfaces totaling approximately 1,833 sf. The site previously contained approximately 2,084 sf and the site after final construction will contain approximately 3,917 sf. However, since this project proposes to construct more than 2,000 sf of new plus replaced impervious surfaces, minimum requirements 1-5 apply to all � of the new and replaced impervious surfaces for this project along with all the disturbed � pervious surfaces. This proposal does not meet any of the land-use criteria that require specific source control for the final use and a SWPPP has been prepared to address the runoff from the site during construction. Refer to Sections 4 and 5 for a detailed discussion. Figures 2 & 3 are provided to show the existing and developed basins and runoff conditions for this site. The runoff in the existing condition spreads over the pervious surfaces to the east and drains toward the right-of-way of Oakes Ave. In the developed conditions all of the runoff from the new roofs will be dispersed on-site and sheet flow over existing lawn and amended soils toward the eastern property line. The dispersal system will allow for roof runoff to disperse over vegetated surFaces for the maximum length of flow path on-site before being collected by the vegetated right-of-way and existing catch basin found on the west side of Oakes Ave. See Section 7 for a detailed discussion. Due to the size of this project only Minimum requirements 1-5 apply to the proposed drainage design as noted above. Included on the following page is a copy of the MR flow chart out of the COE Drainage Manual showing how the applicable minimum requirements were determined. Haack—Lexington Duplex 16-1112 January 2017 Page 3