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