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I <br /> Preliminary Stormwater Site Plan Everett, WA <br /> I <br /> Record Id: COMBO <br /> IDescrip: Prototype Structure Increment 0.10 ft <br /> Start E l. 100.0000 ft Max E l. 109.0000 ft <br /> IList of Discharge Structures: MORIFICE1 <br /> MORIFICE2 <br /> I Record Id: MORIFICE1 (Powdermill Gulch Creek) <br /> Descrip: Prototype Structure Increment 0.10 ft I <br /> Start El. 100.0000 ft Max El. 109.0000 ft <br /> Orif Coeff 0.62 Lowest Orif El. 0.00 <br /> ILowest Diam 0.9000 in Dist to next 6.7500 ft <br /> D2 5.0000 in Dist to next 0.0000 ft <br /> I Record Id: MORIFICE2 (Edgewater Creek) <br /> I Descrip: Prototype Structure Increment 0.10 ft <br /> Start El. 100.0000 ft Max El. 109.0000 ft <br /> Orif Coeff 0.62 Lowest Orif El. 0.00 I <br /> Lowest Diam 2.6700 in Dist to next 6.7500 ft <br /> D2 12.0000 in Dist to next 0.0000 ft <br /> I <br /> The rating curves for the multiple orifice structures were used to check the release rates to <br /> 1 the individual basins. To determine the peak flow, the peak stage of the pond for each <br /> design storm was compared to the multiple orifice discharge at the corresponding <br /> I <br /> elevation. <br /> Powdermill Gulch Creek: <br /> ' Design Storm Pond Stage Stage Discharge Rating Curve Max Discharge <br /> 2 year 106.6898 106.7000 ft 0.0569 cfs 0.1235/2=0.0618 cfs <br /> 10 year 107.2560 107.3000 ft 0.5625 cfs 0.5683 cfs <br /> I <br /> 100 year 108.1421 108.2000 ft 0.8799 cfs 0.9360 cfs <br /> Edgewater Creek: <br /> I <br /> Design Storm Pond Stage Stage Discharge Rating Curve Max Discharge <br /> 2 year 106.6898 106.7000 ft 0.5008 cfs 0.5076/2+0.2470= <br /> 0.5008 cfs <br /> I 10 year 107.2560 107.2500 ft 3.2806 cfs 2.2315+ 1 .1366= <br /> 3.3681 cfs <br /> 100 year 108.1421 108.2000 ft 5.2595 cfs 3.6595+ 1 .8721 = <br /> 5.5316 cfs <br /> I <br /> PACLAND Job# 50175001 Page 13 <br />