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CW February 7,1990 <br /> , <br /> Merrill and Ring Creek is located to the west of this site, but <br /> approximately 10 of the site is tributary to the creek. The <br /> hlocated on this site and <br /> approximately of 01.0 Phillips Ces reek the t- tributary to Phillips <br /> creek.approximately <br /> 5 k acres1.4 oftltie Lhe ite atern tributary to Glenwood <br /> ortion of the site <br /> and . Wetlandsy 5 <br /> Creek. Wetlands associated Phillips <br /> and Glenwood <br /> Creek <br /> are on the site,as as springs in the Glenwood Creek Basin. <br /> In 1982, City Council adopted a drainage plan for south Everett <br /> which included these three basins. The Plan sets forth goals, <br /> policies,anti Construction projects for each of the three basins. <br /> The applicant's proposed storm drainage system would utilizeon-site <br /> retentioncand <br /> combinationlgof to infiltration extent <br /> st rmwater detention <br /> ystems a Detailed soils analysis would be submitted with detailed <br /> systems. time of <br /> engineering <br /> and SEPO building <br /> fora the tindividual phases of L ve development. <br /> uilding <br /> Based o .those rreports, Public Works would determine where <br /> infiltration would be acceptable. <br /> An infiltration system would collect storm drainage in a perforated <br /> conveyance pipe which would allow storm drainage to drain into,the <br /> ground directly. The portion of the stormp dated ge rips ichis nvvyanot <br /> absorbed into the ground through the per pconv <br /> system would be Collected in a series of open ditches, ladthe <br /> en <br /> trenches <br /> or of percolationthe sormstructures drainage which <br /> wouldinto Inf M1e grountl. <br /> Biofiltration would occur naturally via theopercolation process. <br /> where infiltration is not feasible, -site detention wouldbe <br /> per001detl. Drainagtemrom thesuitece gzppntlbe cenSOId vial se der where <br /> toimo ldebe de ya g noun <br /> it would be detained for a time and released eta td not exceeding <br /> that Of the increase, bu eloped site. The overall at e e same of oless <br /> untl eprbut the to of release would through h ram a <br /> than the preleveloped site. Biofiltration syanOgrasthes hops <br /> ned <br /> wales would be provided. Storm drainage conveyance from star loan <br /> of slopesswould incorporate a tightlinetl system to conveywater <br /> water velocities in tie aters would be utilized minimize <br /> CONCLUSIONS, system. <br /> The South Everett Drainage Basins Plan is the appropriate policy <br /> document which applies to storm drainage improvements fox this <br /> site. Det ailetl soils analyses will be required before the City <br /> defenderswhether on-site detention of provided. <br /> ooxmwater or retention end <br /> Ainfiltran ofpreTenti inclutlesetn conditions water which ill be would implement The Concomitant <br /> in <br /> they South Everett Drainage Basins Plan. These conditions regulate <br /> erosion,water filtration and peak storm flows. Based on Compliance <br /> with these conditions,the ps <br /> would ropol would be in conformanaterce with the <br /> impactins <br /> s Ve ett bDrainae e dequxtely ltisegatetl. and surface rdrainage <br />