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� <br /> � <br /> 1 Section One <br /> O•ff-Site Analysi� Storm watcr tinm offsite arc.is does not enter the site. Tl�e site is a <br /> natural high spot. Any sunroundinr drainage is collected �vithin the <br /> � adjacent road and conveyed dircctly to thc regional de:ention <br /> � facility. <br /> I Analysis and Dssign of Tliis site contains rno separate drainage basins. For this reason, <br /> � RequirE�d Erosion and ��'e have hvo distinct sediment traps. During construction the stonn <br /> Sedime�nt Control ��'ater runoff will be conveyed b;i open ditch to the appropriate <br /> � BMPS sedimcnt trap. <br /> � Analysis and Design of This site contains m�o dislinct drainage basins. The westem basin <br /> Required Runoff (Basin A) has its peai: rate BMPs met by the exi�ting regional <br /> Control BMPs stormwater detention facility and discharges into thc Powder Mill <br /> I Gulch Creek Basin. �Ve ha��e confimied that volumc �eas provided <br /> for tliis property. Stonn water runoff from the roof surfaces does <br /> not require water quality treatrnent. Therefore, roof drainage is <br /> I com�eyed in a separate pipe net���ork and not mixed with the <br /> parking lot druinage. Drainage Gom the parking lots is com�.yed <br /> to n slormfilter manhole. City of Gverett standards require <br /> treatment of up to 6 month storni (0.99 inches). Flows above the <br /> I 6-month storm are also passed through the stormfilter prior to <br /> being routed to the regional detention pond. See Ap,�endix B for <br /> calculations for sizing the stonnfilter vault. <br /> IThe eastern basin (Basin I3) [hat disciiarges into Narbeck Creek is <br /> both detained and treated prior to release by using a detention <br /> I vault nnd a stormfilter vaulL The stonnfilter manhole was sized by <br /> Contech Stormwater Solutions, lnc. per ti�e City of Everett design <br /> criteria. The stornm�ater is then conveyed through approx. 6�0' of <br /> offsite bypass pipc to a pre-existing com�eyance system [hat <br /> outfalls directly into \'arbeck Creek. See Appendix B for <br /> calculations for the sizing oCthe dctention vaidt and the stormfilter <br /> facility. <br /> Other Permits NPDES Permit, Forest Practice, 13uilding Permit <br /> Miscellaneous Forms All supporting cnlculations and ���orkshee[s are induded i • <br /> and Worksheets eppcndices. <br /> � <br /> i Srair�n�Center(.o�38—S(ormDrr.innteRepa•t r: roci�„ro�,n�r��rc.„,�r,o3,n9n;-r�:mx��o.r.�loo�-ot-a�-,ro.,�.repon�ltFt7seD.�oc <br /> I P<l l/Pncific, lnc. ��'oveurber 6, 2006/Pnge 2 <br />