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SOUNDVIEW TECHNOLOGY CENTER EVERETT, WA <br /> TESC Pond- Basin C <br /> Tribut ry Area: 6.01 acres (to vault#2) <br /> Flow Frequency <br /> Flow(cfs) 0701 <br /> 2 Year = 1. 9259 <br /> 5 Year = 2 . 6256 <br /> 10 Year = 3.1404 <br /> 25 Year = 3.8517 <br /> 50 Year = 4.4274 <br /> 100 Year = 5.0439 <br /> 10-year flowrate: 3.14 CFS <br /> The required surface area was calculated using the following equation: <br /> SA = 2 x Q 7o/0.00096 <br /> = 2 x 3.74/0.00096 <br /> = 6,543 s f=AS <br /> This equation results in a surface area of 6,543 SF. The pond was designed with a surface area of 7,000 SF at <br /> the top of the sediment storage, which exceeds the minimum requirements for the 70-year flow. The required <br /> area of the orifice was calculated using the following equation: <br /> Ao =AS(2h)05/0.6 x 3600Tgo.5 <br /> =6,543 x(2(3.5))05/[0.6 x 3600 x 24 x 32.2o.5] <br /> = 0.0522 s f <br /> Converted to the required diameter using the following calculation: <br /> D = 73.54 x Ao0.5 <br /> = 73.54 x 0.052215 <br /> = 3.09" z 3-7/8" <br /> The sediment pond will have a 3.5'minimum depth from top of riser to bottom of live pond along with 7'of <br /> free board and 7.5'of sediment storage for a total depth of 6.0'. <br /> TESC Pond- Basin D <br /> Tribut ry Area: 1.70 acres (to system #1) <br /> Flow Frequency <br /> Flow(cfs) 0701 <br /> 2 Year = 0.5448 <br /> 5 Year = 0.7427 <br /> 10 Year = 0.8883 <br /> 25 Year = 1.0895 <br /> 50 Year = 1.2523 <br /> 100 Year = 1.4267 <br /> 10-year flowrate: 0.89 CFS <br /> The required surface area was calculated using the following equation: <br /> SA = 2 x Q 7o/0.00096 <br /> = 2 x a89/0.00096 <br /> = 7,857 sf=AS <br /> SEPTEMBER 23, 2022 STORMWATER DRAINAGE REPORT PAGE 41 <br />