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'BB-Iq-96 15: 2� FROM:TREPANIER ENGINEERING ID�2P6 25y 5558 <br /> PAGE p/7 <br /> .I. �' <br /> ' Trepwneer Engineeri� <br /> � Professiunal Civil Enginee�ing � <br /> � �RF� <br /> DRAINA�E C?,I�C.'ULATIONS O� <br /> FDZ '� � <br /> WASHINGTON FEDERAL' SAVINGS �7ZI,DING <br /> Job 95-063 <br /> January 31, 1996 � �� <br /> PRp�7ECT SCA�B�lARY � 8/2/96 _' <br /> This proposed project will include �he constzuction of a <br /> 5, 000 square foot, single-story, retail and bank building <br /> and less than 10,000 square feet og paved parkiu� <br /> lot/driveway area. The 0.56 acre site is located in the <br /> City of Everett, at the interseCtion of 19th Avenue anCl <br /> 109th St. SE. The drainaqe system will be desiqned <br /> according to the City of Eaerett Standards. <br /> EXISTING CONDITYONS <br /> The site has recently been cleared. Aerial photoqraphs show <br /> the previous long-term exista.ng aite as having been ocCupied <br /> with a single family residence, r�ardge and two outbuildings. <br /> Total existing ii¢pervious surface is approximately 3, OU0 <br /> square feet_ The site also has appraximately 3,000 square <br /> feet of forest with the remain�ler of the site covered with <br /> grass. Topography of the site slopes down to the northwest <br /> at approximately 5�, Runoff sheetflow� from the site in the <br /> northwesterly riirection into the south roadway ditch of <br /> 104th St. SE, where it flows west fos 200 feet and into a <br /> approx�tely 0.5o acre wetlan� ,�rea (on Costco property) . <br /> The wetland drains to the south for approximat�:ly one-half <br /> mile and into Si].ver Lake. <br /> DEVELOPED CONDITIONS <br /> The developed site will be desiqned to drai�Lstcrm <br /> runoff �rom impervious surfaces i.nto a x 60' x 18" <br /> shallow detention pond located in the pa area. <br /> This pond will be con>tructed with a concrete bottom and t'J,fC <br /> �oncrete sidewalls. Outflow will be controlZed k�y an <br /> orifice control tee housed ia a Type-1A ca��h basin located �� <br /> in a lazidscaped area. This catch basin releases the outflow <br /> to an area drain which drains through a sidewalk drain and <br /> into the above-mentioned roadway ditch. <br /> 14?l' 4ewitt • Everett,lh'ashingron 98201 • F�-•-r- � <br /> ^6) 259•5556 • ' ^6)259-5558 <br />