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STORMWATER SITE PLAN <br />EVERETT COMMUNITY COLLE6E HOUSING - BROADWAY <br />SEPTEMBER 11, 2015 <br />PAGE 11 <br />staff, this area is not prone to CSO's or basement flooding. To that end, existing conditions will <br />be the current site conditions. <br />EXISTING BASIN <br />The existing basin consists of 0.35 acres and contains the following surfaces: <br />Impervious Roofs and Drives: 0.19 ac <br />Pervious Lawn on Till: 0.16 ac <br />Flow Rates: <br />2 yr 0.07 cfs <br />10 yr 0.12 cfs <br />100 yr 0.20 cfs <br />PROPOSED BASIN <br />The proposed basin consists of 0.35 acres and contains the following surfaces: <br />Impervious Roofs and Drives: 0.27 ac <br />Pervious Lawn on Till: 0.01 ac <br />BYPASS BASIN <br />A portion of the site cannot be detained due to topography. The bypass basin consists of 0.07 <br />acres and contains the following surfaces: <br />Impervious Drives: <br />Pervious Lawn on Till: <br />0.04 ac <br />0.03 ac <br />The bypass basin is accounted in the design of the detention system as it discharges to the POC <br />along with the discharge from the detention system. <br />Flow Rates: (Combined Proposed and Bypass) <br />2 yr 0.10 cfs <br />10 yr 0.16 cfs <br />100 yr 0.24 cfs <br />This indicates that there is less then 0.1 cfs change between the existing and proposed <br />conditions. A detention system is proposed to reduce proposed flows to the durations of the <br />existing flows. <br />I':'\�'��rk'I'rojril>:'pIS IS 170K�v l3ru�id��:i�'('I I>O('SF�oiBr��;iih��i� Uriin;i!trli-171).d��i <br />