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<br />WORKSHElOT 4: Graphical Peak Discharge Method
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<br />. Project: Cottage Villas Calculated By: CNC
<br />Project No. 92-111 Date: 10-22-92
<br />Location: Arden Hills Checked By:
<br />File: TR-55,WRl Date:
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<br />Drainaae Basin:
<br />Predevelopment Condition
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<br />Peak Discharge Calculations
<br />1, Data:
<br />Drainage Area, Aa 2.50 acre
<br />Drainage Area, Am 0,0039 sq, mile
<br />Runoff Curve Number, Cn 60
<br />Time of Concentmtion, Tc 0.25 hr,
<br />Rainfall Distribution Type II Q,IA,II, III)
<br />Pond and swamp areas spread
<br />throughout watershed 0,00 (percent of Am)
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<br />2, Frequency, year I Stann *1 1 I Stann *210 I Stann *1300 I
<br />. ':::::;:::::::::::::::::::::::;::::::::::::::::::;:::::;::::~::::::::::::::::::::;::::::::;
<br />3. Rainfall, P (24-hour), inches 2,4 I 4? ! 5,9 I
<br />;:::;:;:::::::::::;:::::::::):::;:;:;:::::::::::::::::::::~::::::::::::::::;:::;:;::::::1
<br />4. Initial Abstraction, la, inches 1,333 I 1,333 I 1,333 I
<br />(L 't ff) .. .. .. ' .. - .. --l' " " " - .. " , . 'l" , . " .. .. , 1
<br />asses pnor 0 runo :-:.;....-:..-:.............. ............................. .......................:.:.:.
<br />;;::::t:::::=::::::\:::t:::::::::::::::::\:::::::: ':::{/::::\\:::{1
<br />5. Compute lalP t 0,556 I 0,317 t 0,226 I
<br />;.',;.'.',',','.','.',..',',' ,'.',',.,'..,'.',',',',',',', """-",-",-""""",,,,1
<br />,',,""""'" ,<"""'" -"" ,.""""",. ,<
<br />6, Unit Peak Discharge, qu, csmJin .' """""i~~T-"""""""'~~~"I".."""'.".,"~'~~"1
<br />(Use Tc & laJP with ex, 4-11)
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<br />7, Runoff, Q, inch
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<br />8, Pond and swamp adjustment factor, Fp 1,0 I 1,0 I ' , ,- 1.ll i
<br />(Use pe",ent pond &swamp area r-:-:'..-"'-"',.,""',.'t,",.,"",.,"""",.,",'-}'-',-,',',',-.',',',',',',',',
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<br />:: ~=~e:~2~:::::~ss~~~; area_) r,:;::'l,j;!;\:!<;!';;\:j;:tl;.!,,::l:'!,:l,:'::'::j',l,ll!;,i,;::i,;:[:,:rl:\,;:!:,lll
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<br />9, Peak discharge, qp = qu*Am*Q*Fp, CFS (;.:-:-:-:,;.;.;.:,~:~;.(<,:-:,;.;.:<,:-:,:~:t(-:,:-:-:-:-:-:-:,:-~:~;'1
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<br />. TR-55
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