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conveyed through a surface mounted pipe down the off -site slope to the west. It will be released <br />to a ditch alongside the Boeing rail spur where it will flow to a regional detention pond and <br />eventually into Japanese Gulch Creek. Drainage released to Pre -Basins B and C will be <br />conveyed by existing ravines that drain to Edgewater Creek. Run-on that currently enters the <br />southeastern corner of the site from off -site (Pre -Basin C Run -On) will be directed through a <br />constructed swale into a catch basin, under 36th Avenue West, to the existing stormwater <br />conveyance ditch on the neighboring property to the east. This conveyance also flows to <br />Edgewater Creek. <br />Stormwater detention will be designed to match pre -development hydrologic conditions. <br />Stormwater in post -developed conditions should have very little, if any, detectable effect on <br />downstream systems such as Japanese Gulch Creek and Edgewater Creek. Stormwater will be <br />treated using precast underground vaults with filter cartridges meeting the water quality <br />requirements of the City of Everett. This method of filtration will remove metals and other <br />pollutants prior to being released from the site. The preliminary stormwater plan sizes the <br />detention vaults with a cumulative live storage capacity of approximately 750,000 cubic feet. <br />The system will be designed using the Western Washington continuous simulation hydrology <br />model (WWHM). <br />The drainage plan for this site is being prepared in accordance with the 2010 City of Everett <br />Stormwater Management Manual, which is based on the 2005 DOE Stormwater Manual. The <br />applicant will apply for a NPDES permit when all other permits are reviewed and approved. <br />Biological treatment using bioswales or rain gardens requires a great deal of land that would limit <br />the development potential on the subject site, ultimately decreasing its economic viability. <br />Biological treatment has therefore been determined to be an unreasonable stormwater treatment <br />alternative for this site. <br />4.4.3 Clearing and Grading <br />Grading work to level the site will be extensive. The entire development area will be mass <br />graded to accommodate construction of the proposed buildings and associated pavement. <br />Grading will include the elimination 10,823 square feet (0.25 acres) of Category II and III <br />wetlands (DOE, City of Everett classification) through excavation. The wetlands lie on higher <br />areas of the site that will be excavated and moved to the lower areas of the site to provide a <br />relatively level final grade. Total grading quantity will be approximately 300,000 cubic yards on <br />site. No export is planned, nor is any fill planned to be imported to the site, other than clean <br />crushed rock to create a subsurface for the drive aisles and parking areas. <br />Wetland vegetation to be impacted includes red alder, western red <br />creeping buttercup, lady fern, salmonberry, soft rush, toad rush, <br />vegetation currently considered buffer will be removed and includes <br />ocean spray, western sword fern, creeping buttercup, reed canary <br />western red cedar, and stinging nettle. <br />Biological Evaluation <br />Soundview Business Campus <br />20 <br />cedar, trailing blackberry, <br />end slough sedge. On -site <br />big -leaf maple, red alder, <br />grass, salmonberry, salal, <br />WRI #14109 <br />Revision #2: October 2, 2015 <br />