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Evercu LDS Parking Lot Expansion <br />Storm Drainage Report <br />Off -Site Convevance Cauacity Analvsis <br />Please refer to Figures 421 and 4B - OjjSire Conveyance F..rhinir to aid in the following discussion. <br />Flow Calculations (StormShed Output SBUH Method) <br />Precipitation for the 6-mo, 2-yr, 10-yr, 25-yr, and the 100-yr 24-hr stonn events are 0.99", 1.55", 2,25", <br />2.6", and 3.25", respectively. <br />EXISTING ONSITE Event Summary: (ONSITE EXISTING) <br />BasinlD Peak Q Peak T Peak Vol Area Method Raintype Event <br />Drainage Area: EXISTING ONSITE <br />Hyd Method: <br />SBUH Hyd <br />Peak Factor: <br />484.00 <br />Storm Dur: <br />24.00 hrs <br />Area CN <br />Pervious <br />0.0000 ac 86.00 <br />Impervious <br />3.2500 as 98.00 <br />Total <br />3.2500 ac <br />ac <br />Loss Method: SCS CN Number <br />SCS Abs: 0.20 <br />Intv: 10.00 min <br />TC <br />0.00 his <br />0.08 hrs <br />Supporting Data: <br />Impervious CN Data: <br />Impervious 98.00 3.2500 ac <br />Impervious TC Data: <br />Flow type: Description: Length: Slope: Coeff: Travel Time <br />Fixed assumed 0.00 If 0.00% 50000 5.00 min <br />DEVELOPED Event Summary: (ONSITE DEVELOPED + UPSTREAM BASIN B) <br />SasiWD Peak Q <br />Peak T <br />Peak Vol Area Method Raintype Event <br />(Cfs) <br />(hrs) <br />(ac-ft) ac /Loss <br />DEVELOPED 0.17 <br />8.00 <br />0.0638 1.41 SBUH/SCS TYPE1A 6 month <br />DEVELOPED 0.31 <br />8.00 <br />0.1180 1.41 SBUH/SCS TYPEIA 2yr <br />Drainage Area: DEVELOPED <br />Hyd Method: <br />SBUH Hyd <br />Peak Factor: <br />484.00 <br />Storm Dur: <br />24.00 hrs <br />Area CN <br />Pervious <br />0.5700 ac 86.00 <br />Impervious <br />0.8400 ac 98.00 <br />Total <br />1.4100 ac <br />Supporting Data: <br />Pervious CN Data: <br />Lawn 86.00 <br />Offsile - Lawn 86.00 <br />Impervious CN Data: <br />Pavement+C&G 98.00 <br />Loss Method: SCS CN Number <br />SCS Abs: 0.20 <br />Intv: 10.00 min <br />TC <br />0.50 hrs <br />0.10 his <br />0.1900 ac <br />0.3800 ac <br />0.4600 ac <br />Pa2006106113 Everett LDS Parkin0 1.01ITexnS10rm Report,i06113 Drainage Report Revised 01.10.03.doa <br />Page 9 of 36 <br />