1508 100TH ST SW 2018-01-02 MF Import

1. PROJECT OVERVIEW This document is intended to provide engineering infonnation necessary to support the SFR buildinq� permit application to the City of Everetl for this property. The site is located at 14xx 100' St SW, Everett, WA 98204, refer to figure 1 for a vicinity map. The parcel area is approximately 0.18 acres. The parcel is bordered to the north by 100'" St. SW, and the new SFR will take access uH of the existing roadway near the middle of the site. The new SFR will be located 11-feet west of the eastern property line and 20-feet south of the R.O.W. This project proposes to construct less than 2,500 si of new impervious surfaces. Since this parcel is less tlian t acre in size per?he COE 2010 stormwater manual the existing conditions will be mudeled as they are in the current/developed condition. Therefore, Minimum requirements 1-5 apply to all of the new impervious surfaces for this project along with all the disturbed pervious suriaces. Th�s 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 frorr, the site during construction. Refer to Sections 4 and 5 for a detailed discussion. Figures 2 8 3 are provided to show the existing and developed basins and runoff conditions for this site. The runoH in the existing condition will spread over the pervious and impervious surfaces as sheet flow and drain to the east or west where it is collected by shallow swales and conveyed sou!h and off the site. With all of the site runoN being collected in the existing stream channel south of the site. The runoH within the roadway is collecled by a conveyance system but the outfall to this system was not located. The general soil conditions (or lhis property as mapped by the NCSC web-soil survey were found to be Alderwood-Urban Land Complex type soils. liowever, the site has been completely graded under a pravious permit and it appears fill has been placed over tF�e majority of the site with all of the site in a disturbed/compacted condition. Therefore, dispersion and soil amendments will be used and sized based on the soils found on the site. The drainage design has been laid out per the COE 2010 Stormwater Management Manual. Due to the size of this project only Minimum requirements 1-5 apply to the proposed drainage design as noted above. Included on the tollowing page is a copy of the MR flow chart out of the COE Drainage Manual showing how the applicable minimum requiremenis were determmed � na,�� in�i' i oi io sr�a t2-tzo5-to I /� , � � Der 2012 Page� .