SW6240601_Design Calculations_20240830 (12)

4D Site Solutions,
DESIGN REQUIREMENTS:
A. Pass the storm event
I17-Wet Pond#2 Pre-Development Run1 II
Drainage Area,(DA)= 34.59 acres
Intensity,(I)= 8.08 inches/hr
Composite Runoff Coefficient,(C)_> 0.33
Maximum Release Rate,(Q100)_> 92.23 cfs
Pond#2 Post-Development Runoff II
Drainage Area,(DA)= 34.59 acres
Intensity,(I)= 10.20 inches/hr
Composite Runoff Coefficient,(C)_> 0.68
Peak Release Rate,(Q100)_> 239.92 cfs
Detention Pond Stage Storage Function
Contour Contour Incr. Accum. Stage
Elev. Area Storage Storage(S) (Z)
00 (sf) (cf) (cf) 00 In(S) In(Z) Z est
180.5 33,368 - - -
181.0 35,670 17,260 17,260 0.50 9.76 -0.69 0.53
......................................... .............................................
181.5 36,921 18,148 35,407 1.00 10.47 0.00 1.02
182.0 38,114 18,759 54,166 1.50 10.90 0.41 1.50
183.0 40,552 39,333 93,499 2.50 11.45 0.92 2.46
184.0 43,056 41,804 135,303 3.50 11.82 1.25 3.44
185.0 45,627 44,342 179,645 4.50 12.10 1.50 4.44
186.0 48,264 46,946 226,590 5.50 12.33 1.70 5.48
187.0 50,967 49,616 276,206 6.50 12.53 1.87 6.56
188.0 53,715 52,341 328,547 7.50 12.70 2.01 7.68
Regression Output:
b= 1.10 (X Variable Coeff)
Ks- 34,645 (eY-i ter-pt)
Stage-Storage Equation is of the form:S=(Ks)(Z)b
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4D Site Solutions,
Primary
Barrel
Number of Barrels= 1
Dia.of Barrel= 30 inches
Area of Barrel,(Ab)= 4.91 sf
Pipe Length,(L)= 100 feet
Friction Coeff,(Kp)= 0.00786
Inv.of Barrel= 177.80 feet
Riser
Elev.of Riser Crest= 186.50 feet
Rectangular
Length Weir— 36 inches Width Weir— 48 inches
Total Weir Length= 14.00 feet
Area of Riser= 12.00 sq.ft.
Orifice in Riser
Dia.of Orifice= 4.70 inches
Number of Orifices= 1
Area of Orifice,(Ab)= 0.12 sf
Orifice Coefficient(Cd)= 0.60
Inv.of Orifice= 180.50 feet
Length of weir— 3.40 feet
Top of weir— 182.78 feet
Weir Coefficient(Cw)— 3.00
Emergency
Width of Spillway(Approx.)= 30 feet
Weir Coefficient= 3.3
Crest Elevation= 187.00 feet
Summary .
Maximum Release Rate,(Q100)= 92.23 cfs
Release Rate,(Q100)= 208.70 cfs
Normal Water Surface Elev.= 180.50 feet
Water Surface Elev.g Outlet(Qloo)= 187.60 feet
printed:4/29/2024 11:58 AM Page 2 of 3

4D Site Solutions,
Inflowi ig II
Peak Inflow,(Qp)=> 239.92 cfs
Time to Peak Calculation: CN= 78 P= 8.28 in. S= 2.82 in.
Q*= 5.65 in. (depth of runoff)
vol— 709,476 cf (vol.of runoff)
Time to Peak,(Tp)_> 35.5 minutes
(SCS TR-55)
printed:4/29/2024 11:58 AM Page 3 of 3