2531 COLBY AVE 2016-01-01 MF Import

� � STORMWATER S1TE PLAN I � (Comprchensive Hydraulic Report) � ' I. PROJECT OVERVIEW This report details the stom� drainage design for the IIanner [3ank Do�mtown Everett project. � The project is in do�timtown fiverett, at Lots 13, 14, 15, and 16, Block 5G2, Rucker's First Plat of Cverett. It is locatcd at the northeast comer of intersection of Colby Avcnue and 26'h Street. Thc � projccl site is adjaccnt to a concretc alley on the east. A commcrcial/residedtial mixed-use building bordcrs the sitc on the north. Colby Avenue and 26'" Strcet border the projcct site on the �vcst and south, respccti��ely. ' 'rhe tolal arca of the projcct sitc is 0.25 acres. It is curccntly an asphalt-paved parking lot. Thc proposed project is to build a hvo-slory bank building witli drive-tl�rough at Ihc site. Sitc I impro��cments include stonn drainage, utility scrvices to thc building, dri�-athrough azea rcgrading and repaving, eaisting allcy rcpaving, and damagcd sidc��alk replacement. � See Pigure l, Vicinity Map, for the projcct location. I II. PRELIMINARY CONI)ITIONS SUMMARY � I;xistine Conditions 'llte projecl site is currently a parking lot pavcd with asphalt. On-site soils consist primarily of I fill material over advance ouh��ash dcposits. 'I'hc till laycr varies from 6 to 16 fcet deep. Thc �ill generally consisls af ineditun dcnse sand with sill and gravel. � The site gently slopes from ��cst to east at slopes less than 2 perccnt. Stormwater drains as shect flow from thc west to a catch basin near thc �uidpoint of the eastcrn property linc. Water collected by the catch basin is then conveyed and discharged into a combined sewer line under � the concrete alley. Tlie combincd sewcr line in the alley conreys watcr souds to the sewer main in 26�" Strect. Prom there, water Ilows cast�vard and eventua�ly discharges to the city treatment plant. � No ofT-site drainage enters tlie site. �lows Gom 26�h Slreet, Colby A��euue,and the alley drain to the strcet slomi system. Drainage on the adjacent lot to Ihe �:orth is coilected and conveycd to Ithe combined sewcr in the alley or the stonn system in Colby Avcnue. There is neither a detention nor a water quality treatment faciliq� on tye silc. ISce Pigurc 2, L'•sistiag '1'opography and Sitc Coudilious. I Danner l3ank and Mortgage Ccnter, Bvcreu I Septembcr 2008 � 5lonnwatcr Sitc Plan , ,, ,