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Technical Information Report July 2015 <br /> Everett Self-Storage <br /> ESC Design Calculations <br /> Temporary Sediment Trap <br /> Description:Sediment trap located in Basin B4 <br /> Design Method: Rational Method <br /> Design Event: 2-year <br /> Design Summary <br /> Top Berm Temporary Pond Elevation: 424.0 ft <br /> Width: 4.0 ft <br /> Emergency Overflow Spillway: Elevation: 423.0 ft <br /> Min.Req.Length:` 6.0 ft <br /> Design Length: 6.0 ft <br /> Pond Bottom: Elevation: 420.0 ft <br /> Surface Area: Required: 1,030 ftz <br /> Provided: 1,100 ftZ <br /> Rational Method Calculations Land Surface C Area(Ac.) <br /> Developed Basin Area: 2.64 AC. Lawn 0.25 2.50 <br /> 2-year ppt. 1.55 in Forest 0.10 0.00 <br /> 1 0-year ppt. 2.25 in Gravel 0.80 0.00 <br /> 100-year ppt. 3.25 in Total 0.25 2.50 <br /> Rainfall per City of Everett Stormwater Management Manual Table%.4 <br /> Time of Concentration <br /> Segment L(ft) kR S(ft/ft) Tc(min) <br /> 1 600 10.1 0.0200 7.00 <br /> 2 <br /> 3 <br /> Total 7.00 <br /> TC=L/60(k R'sgrt(S))per COE SWMM <br /> kR per KCSWDM TableS.7 <br /> Peak Runoff Rates <br /> Storm Event aR I ba iR I(in/hr) Q(cfs) <br /> 2-year 1.58 0.58 0.51 0.79 0.50 <br /> 1 0-yearl 2.44 0.64 0.70 1.58 0.99 <br /> 1 00-yearl 2.61 1 0.63 0.77 2.49 1.56 <br /> as and bR per KCSWDM Table 3.2.18 <br /> Pond Design <br /> Surface Area Required: A,= 2080-Qd_ ft' <br /> A,= 1,030 ftZ at bottom of spillway <br /> Emergency Overflow Spillway: Q1OOD= 1.56 cfs <br /> H = 0.30 ft min.0.2 ft per KCSWDM S.3.1.2 <br /> L= (QIOOD/(3.21 H3/Z))-2.4Hz eqn. 5-2 KCSWDM 5.3.1.2 <br /> L= 6 ft min 6ft per KCSWDM 5.3.1.2 <br /> 14114 Everett Storage TIR Revised 0715.doc 40 <br />