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P.n:trv tli: IxptO <br />sumi c�ino�o�m;� <br />rurn� nwen.......: <br />RAINFALL 7VPL ...: <br />PRECIPITATION....: <br />iIIAE INIENVAL....: <br />!:r,���: r.�i�.�.�,a io v�.,.. <br />i.ea acro•: ans�rio�rv�: a.on ��- <br />TYPEtA PEflV <br />2.10 inc�oc AREA..: 1.82 Acrc: <br />f0.a0 min CN....: 73.00 <br />TC....: 40.60 min <br />�NS�FACIION COEFF: 0.20 <br />ir,Reach � Sheet l: 300.00 ns:0.2400 p2yr: 1.60 a:0.09Uo <br />P[�N RATE: 0.05 cto VOL: 0.06 �c�1t TIIAE: 967 :-:ri <br />UASIN ID: Ex100 <br />SCUH AiETHO�OLOGY <br />TOT�L AREA.......: <br />�AINF�LL TVPE....: <br />PNFCIPITATION....: <br />TIM[ INTERVAL....: <br />�,,. <br />bll.OU <br />f'v.00 <br />Fcr.: r: <br />ni n <br />NAIAE: Existing 100-year <br />1.98 Acres OFSEFLOWS: 0.00 c�c <br />TVPEtA PEflV �'•' <br />3.00 inches APEA..: 1.82 �cres �....�,�-.. . <br />70.0� min CN....: )9.00 �6������ <br />TC....: 48,G0 nin 15.00 n.� <br />Af35iflAG7I0N GOEFP: 0.20 <br />TcRcach - Shaot L: 800.00 no:0.2400 p2yr: 1.60 c:0.0200 <br />P[AK f1ATG: 0.f5 cfs VOL: �.14 �c-ft iI�[: 490 mtn <br />This information provides values for comparison with runoff generated by the final <br />developed site conditions. <br />POST-DEVELOPMENT QUANTITY COfJTROL <br />Development of the site creates three sub-basins within the site: Northern Tier, Central <br />Core and Southern Tier (see Basin Descriptron: on page 1). The following sections <br />describe treatment for each of these sub-basins. <br />Tha Central Core: Rain Gardens <br />Stormwater quantity will be controlled primarily by a series of seven rain gardens <br />following recommendations of the "Low Impact Development Technical Guidance <br />It4anual for Puget Sound." <br />I he seven rain gardens provide a retentron volume (i.e.; not directly released) of 1590 <br />cubic feet that is treated and attenuated by infiitration into the engineered soil. Table 1 <br />shows the calculation of runoff, storage and discharge within the Central Core based <br />upon an SBUH Type-1A storm event. The results (displayed in the gray cells at the <br />bottom right) are provided for the 6-month "water quality" storm, and the 2-, 10- and <br />100-year storm events. <br />Catchbasins collect runoff and direct it to the rain gardens. A FF20F Tee within each <br />catchbasin provides emergency spill protection. Yard drains located at the edge of the <br />rain garden maintain the peak storage depth of 18-inches, while underdrains collect <br />infiltrated runoff and prevent prolonged saturation of the soil that would impair the health <br />and effectiveness of ihe rain garden. <br />HEAR7HSTONE L.4NE 7 DRAINAGE REPORT <br />APRIL 2006 <br />