SW6220101_Design Calculations_20231113 (4)

4D Site Solutions, Inc.
DESIGN REQUIREMENTS:
A. Pass the storm event
Creekside Oaks South-Detention Pond#1 Pre-Development Runoff-100-yr
Drainage Area,(DA)= 19.03 acres
Intensity,(I)= 5.09 inches/hr
Composite Runoff Coefficient,(C)=> 0.31
Maximum Release Rate,(Qloo)=> 30.03 cfs
Creekside Oaks South-Detention Pond#1 Post-Development Runoff-100-yr
Drainage Area,(DA)= 19.03 acres
Intensity,(I)= 9.92 inches/hr
Composite Runoff Coefficient,(C)=> 0.60
Peak Release Rate,(Qloo)=> 113.27 cfs
Detention Pond Stage-Storage Function
Contour Contour Incr. Accum. Stage
Elev. Area Storage Storage(S) (Z)
(ft) (sf) (cf) (cf) (ft) In(S) In(Z) Z est
287.0 21,182 - - -
287.5 23,464 11,162 11,162 0.50 9.32 -0.69 0.55
288.0 24,626 12,023 23,184 1.00 10.05 0.00 1.04
288.5 25,803 12,607 35,791 1.50 10.49 0.41 1.51
289.0 26,993 13,199 48,990 2.00 10.80 0.69 1.98
289.5 28,198 13,798 62,788 2.50 11.05 0.92 2.46
290.0 29,417 14,404 77,192 3.00 11.25 1.10 2.94
290.5 30,650 15,017 92,209 3.50 11.43 1.25 3.43
291.0 31,897 15,637 107,845 4.00 11.59 1.39 3.93
291.5 33,158 16,264 124,109 4.50 11.73 1.50 4.44
292.0 34,433 16,898 141,007 5.00 11.86 1.61 4.96
292.5 35,722 17,539 158,546 5.50 11.97 1.70 5.49
293.0 37,026 18,187 176,733 6.00 12.08 1.79 6.03
293.5 38,344 18,843 195,575 6.50 12.18 1.87 6.58
294.0 39,676 19,505 215,080 7.00 12.28 1.95 7.15
294.5 41,022 20,175 235,255 7.50 12.37 2.01 7.72
Regression Output:
b= 1.15 (X Variable Coeff)
Ks= 22,246 (eY-intercept)
Stage-Storage Equation is of the form:S=(Ks)(Z)b
printed: 11/1/2023 1.00 PM Page 1 of 3

4D Site Solutions, Inc.
Primary Spillway
Barrel
Number of Barrels= 1
Dia.of Barrel= 30 inches
Area of Barrel,(Ab)= 4.91 sf
Pipe Length,(L)= 70 feet
Friction Coeff.,(Kp)= 0.00786
Inv.of Barrel= 285.00 feet
Riser
Elev.of Riser Crest= 292.50 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= 3.00 inches
Number of Orifices= 1
Area of Orifice,(Ab)= 0.05 sf
Orifice Coefficient(CO= 0.60
Inv.of Orifice= 287.00 feet
Length of weir 1.00 feet
Top of weir= 289.55 feet
Weir Coefficient(Cw)= 3.00
Emergency Spillway
Width of Spillway(Approx.)= 25 feet
Weir Coefficient= 3.3
Crest Elevation= 293.50 feet
Summary of Results
Maximum Release Rate,(Qloo)= 30.03 cfs
Release Rate,(Q1oo)= 91.18 cfs
Normal Water Surface Elev.= 287.00 feet
Water Surface Elev.@ Outlet(Q100)= 293.68 feet
printed: 11/1/2023 1.00 PM Page 2 of 3

4D Site Solutions, Inc.
Inflow Hydrograph-100-yr
Peak Inflow,(Qp)_> 113.27 cfs
Time to Peak Calculation: CN= 83 P= 8.35 in. S= 2.05 in.
Q*= 6.31 in. (depth of runoff)
Vol= 436,037 cf (vol.of runoff)
Time to Peak,(Tp)=> 46.2 minutes
(SCS TR-55)
printed: 11/1/2023 1:00 PM Page 3 of 3