905 80TH ST SW MTORRES AMERICA 2018-09-18

4229 St.NE.Suite 204 Marys 6 e WA 98270 Phone(860}657-4709 BergEngineering FAX (360)657-4779 ebergw zvr rizon.net March 12, 2007 Jane Zimmerman City of Everett 3200 Cedar Street Everett, WA 98201 Re: Drainage Report — Hardeson Rd Business Pk— Phase 1 — SEPA 06-067 Site Address — 75th St. SW @ Hardeson Rd. For Hardeson Road, LLC — BE05018 The 16.33-acre property is located in the southwest quadrant of the 75th St, SW/ Hardeson Road intersection in the City of Everett. The property contains no significant impervious areas, and is covered with brush and second growth trees. A drainage course (-6% gradient) conveys runoff from 80th St SW and properties south and bisects the property collecting in a Category II wetland located along the NE boundary of the property. Drainage then flows into the City storm system (48") within Hardeson Rd. This City system flows northerly emptying into Merrill and Ring Creek, which in turn discharges into Possession Sound. Site soils are classified as: 5,6 —Alderwood — Urban land complex — (Type C Soil) This submittal is Phase 1 of an ultimate business park development proposed for the property. The scope of Phase 1 is to provide an alternate path for the subject drainage course bisecting the property from south to north. This will be accomplished by installing an 18" storm drain system near the east properly line and will intercept drainage entering the property from the south (80th St SW and offsite properties contributing). This system will divert some runoff (-1 cfs) from the estimated offsite flow (12.11 cfs) to a new grass channel that will be located near the previously mentioned wetland. The remainder of this offsite flow will discharge into the natural drainage course into the subject wetland by `bubbling up" and spreading out over 4"-6" quarry spalls placed around CB2 performing an energy dissipater function. A 2-cell wet pond is also provided to handle the ultimate stormwater requirements for the site.