20191352 Ver 1_07_SCM Calcs_20191004

STORMWATER CONTROL MEASURE “A”
CALCULATIONS

FLEX BUILDINGS – TW ALEXANDER
MPP-18020
Flex Buildings - TW Alexander
MPP-18020
STORMWATER CONTROL MEASURE
SSFxn Above NP
G. Harrell
9/12/2019
STAGE-STORAGE FUNCTION - ABOVE NORMAL POOL
Average Incremental Accumulated Estimated
Contour Contour Contour Contour Stage
Contour Stage Area Area Volume Volume w/ S-S Fxn
(feet)(feet)(SF)(SF)(CF)(CF)(feet)
357.0 0.00 8,098
357.5 0.50 9,814 8956 4478 4478 0.51
358.0 1.00 10,359 10087 5043 9521 0.99
360.0 3.00 12,682 11521 23041 32562 2.91
362.0 5.00 15,231 13957 27913 60475 5.01
363.0 6.00 16591 15911 15911 76386 6.15
1.13845211 9.17579333
9660.42894
KS =9660
b =1.1385
y = 9660.4x1.1385
R² = 0.9996
0
10000
20000
30000
40000
50000
60000
70000
80000
90000
0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00Storage (CF)Stage (feet)
Storage vs. Stage
Flex Buildings - TW Alexander
MPP-18020
STORMWATER CONTROL MEASURE
Surface Area Calculation
G. Harrell
9/12/2019
WET DETENTION BASIN SUMMARY
From Stormwater Best Management Practices Manual . NCDENR: Division of Water Quality.
Enter the drainage area characteristics ==>
5.41 acres
4.01 acres
Note The basin must be sized to treat all impervious surface runoff draining into the pond, not just the impervious
surface from on-site development.
Drainage area =5.41 acres @ 74.1%impervious
Estimate the surface area required at pond normal pool elevation ==>
Wet Detention Basins are based on an minimum average depth of =3.00 feet (hard coded)
From the DWQ BMP Handbook, the required SA/DA ratio for 85%TSS Removal ==>
3.0 3.00 3.5
Lower Boundary =>70.0 2.88 2.64
Site % impervious =>74.1 3.08 3.08 2.82
Upper Boundary =>80.0 3.36 3.07
Therefore, SA/DA required =3.08
Surface area required at normal pool =7,257 ft2
=0.17 acres
Surface area provided at normal pool =8,098 ft2
Total drainage area to pond =
Total impervious area to pond =
Flex Buildings - TW Alexander
MPP-18020
STORMWATER CONTROL MEASURE
WQV Calculation
G. Harrell
9/12/2019
DETERMINATION OF WATER QUALITY VOLUME
WQ V = (P)(R V )(A)/12
where,
WQV = water quality volume (in acre-ft)
RV = 0.05+0.009(I) where I is percent impervious cover
A = area in acres
P = rainfall (in inches)
Input data:
Total area, A =5.41 acres
Impervious area =4.01 acres
Percent impervious cover, I =74.1 %
Rainfall, P =1.00 inches
Calculated values:
RV =0.72
WQV =0.32 acre-ft
=14089 cf.
ASSOCIATED DEPTH IN POND
WQV =14089 cf.
Stage / Storage Data:
Ks =9660
b =1.138
Zo =357.00
Volume in 1" rainfall =14089 cu. ft
Calculated values:
Depth of WQv in Basin =1.39 ft
=16.72 inches
Elevation =358.39 ft
Flex Buildings - TW Alexander
MPP-18020
STORMWATER CONTROL MEASURE
WQV Drawdown Calculation
G. Harrell
9/12/2019
DRAWDOWN ORIFICE DESIGN
D orifice =1.75 inch
# orifices =1
Ks =9660
b =1.1385
Cd orifice =0.60
Normal Pool Elevation =357.00 feet
Volume @ Normal Pool =0 cf
Orifice Invert =357.00 feet
WSEL @ 1" Runoff Volume =358.39 feet
WSEL Vol. Stored Orifice Flow Avg. Flow Incr. Vol.Incr. Time
(feet)(cf)(cfs)(cfs)(cf)(sec)
358.39 14089 0.092
358.27 12706 0.088 0.090 1383 15352
358.15 11341 0.083 0.086 1365 15936
358.03 9995 0.079 0.081 1345 16613
357.91 8672 0.073 0.076 1324 17413
357.79 7372 0.068 0.071 1299 18382
357.67 6100 0.062 0.065 1272 19590
357.55 4860 0.055 0.059 1240 21164
357.43 3657 0.048 0.052 1203 23353
357.31 2501 0.039 0.043 1156 26749
357.18 1409 0.027 0.033 1093 33361
Drawdown Time =2.41 days
By comparison, if calculated by the average head over the orifice
(assuming average head is half the total depth), the result would be:
Average driving head on orifice = 0.660 feet
Orifice composite loss coefficient = 0.600
Cross-sectional area of siphon = 0.017 sf
Q =0.0653 cfs
Drawdown Time = Volume / Flowrate / 86400 (sec/day)
Drawdown Time = 2.50 days
Storm Event: 1 YearLabel: SCM A
Return Event: 1 yearsSubsection: Elevation-Area Volume Curve
Volume (Total)
(ft³)
Volume
(ft³)
A1+A2+sqr
(A1*A2)
(ft²)
Area
(ft²)
Planimeter
(ft²)
Elevation
(ft)
0008,0980.0357.00
4,4714,47126,8279,8140.0357.50
9,5145,04330,25610,3590.0358.00
32,51623,00234,50312,6820.0360.00
60,39027,87441,81115,2310.0362.00
76,29615,90647,71816,5910.0363.00
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM A
Return Event: 1 yearsSubsection: Outlet Input Data
Requested Pond Water Surface Elevations
ft357.00Minimum (Headwater)
ft0.10Increment (Headwater)
ft363.00Maximum (Headwater)
Outlet Connectivity
E2
(ft)
E1
(ft)
OutfallDirectionOutlet IDStructure Type
363.00358.75CulvertForwardOrificeOrifice-Circular
363.00361.00CulvertForwardRiserInlet Box
363.00357.00CulvertForwardWQ OrificeOrifice-Circular
363.00356.50TWForwardCulvertCulvert-Circular
(N/A)(N/A)TailwaterTailwater Settings
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM A
Return Event: 1 yearsSubsection: Outlet Input Data
Structure ID: Riser
Structure Type: Inlet Box
1Number of Openings
ft361.00Elevation
ft²16.0Orifice Area
0.6Orifice Coefficient
ft16.00Weir Length
(ft^0.5)/s3.00Weir Coefficient
1.0K Reverse
0.0Manning's n
0.0Kev, Charged Riser
FalseWeir Submergence
FalseOrifice H to crest
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM A
Return Event: 1 yearsSubsection: Outlet Input Data
Structure ID: Culvert
Structure Type: Culvert-Circular
1Number of Barrels
in24.00Diameter
ft47.00Length
ft47.01Length (Computed Barrel)
ft/ft0.021Slope (Computed)
Outlet Control Data
0.013Manning's n
0.5Ke
0.0Kb
0.0Kr
ft0.00Convergence Tolerance
Inlet Control Data
Form 1Equation Form
0.0098K
2.0000M
0.0398C
0.6700Y
1.1T1 ratio (HW/D)
1.3T2 ratio (HW/D)
-0.5Slope Correction Factor
Use unsubmerged inlet control 0 equation below T1 elevation.
Use submerged inlet control 0 equation above T2 elevation
In transition zone between unsubmerged and submerged inlet
control,
interpolate between flows at T1 & T2...
ft358.80T1 Elevation ft³/s15.55T1 Flow
ft359.09T2 Elevation ft³/s17.77T2 Flow
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM A
Return Event: 1 yearsSubsection: Outlet Input Data
Structure ID: WQ Orifice
Structure Type: Orifice-Circular
1Number of Openings
ft357.00Elevation
in1.75Orifice Diameter
0.6Orifice Coefficient
Structure ID: Orifice
Structure Type: Orifice-Circular
1Number of Openings
ft358.75Elevation
in6.00Orifice Diameter
0.6Orifice Coefficient
Structure ID: TW
Structure Type: TW Setup, DS Channel
Free OutfallTailwater Type
Convergence Tolerances
30Maximum Iterations
ft0.01Tailwater Tolerance
(Minimum)
ft0.50Tailwater Tolerance
(Maximum)
ft0.01Headwater Tolerance
(Minimum)
ft0.50Headwater Tolerance
(Maximum)
ft³/s0.001Flow Tolerance (Minimum)
ft³/s10.000Flow Tolerance (Maximum)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM A
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
(no Q: Orifice,Riser,WQ
Orifice,Culvert)
0.00(N/A)0.00357.00
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.01357.10
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.03357.20
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.04357.30
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.05357.40
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.05357.50
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.06357.60
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.06357.70
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.07357.80
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.07357.90
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.08358.00
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.08358.10
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.09358.20
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.09358.30
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.09358.40
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.10358.50
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.10358.60
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.10358.70
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.10358.75
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.11358.80
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.16358.90
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.25359.00
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.36359.10
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.50359.20
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.64359.30
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.72359.40
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.79359.50
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM A
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.86359.60
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.92359.70
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.98359.80
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.03359.90
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.08360.00
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.13360.10
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.18360.20
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.22360.30
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.26360.40
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.31360.50
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.35360.60
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.38360.70
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.42360.80
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.46360.90
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.49361.00
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)3.04361.10
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)5.84361.20
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)9.46361.30
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)13.73361.40
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)18.51361.50
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)23.57361.60
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)28.84361.70
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)31.42361.80
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)31.82361.90
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)32.20362.00
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)32.58362.10
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)32.96362.20
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM A
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)33.34362.30
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)33.71362.40
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)34.07362.50
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)34.43362.60
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)34.79362.70
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)35.14362.80
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)35.50362.90
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)35.85363.00
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM A (IN)
Return Event: 1 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft357.00Elevation (Water Surface,
Initial)
ft³0Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s23.02Flow (Peak In) min721.00Time to Peak (Flow, In)
ft³/s1.14Flow (Peak Outlet) min782.00Time to Peak (Flow, Outlet)
ft360.13Elevation (Water Surface,
Peak)
ft³34,143Volume (Peak)
Mass Balance (ft³)
ft³0Volume (Initial)
ft³51,943Volume (Total Inflow)
ft³0Volume (Total Infiltration)
ft³31,370Volume (Total Outlet
Outflow)
ft³20,557Volume (Retained)
ft³-16Volume (Unrouted)
%0.0Error (Mass Balance)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 2 YearLabel: SCM A (IN)
Return Event: 2 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft357.00Elevation (Water Surface,
Initial)
ft³0Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s27.07Flow (Peak In) min721.00Time to Peak (Flow, In)
ft³/s1.38Flow (Peak Outlet) min782.00Time to Peak (Flow, Outlet)
ft360.69Elevation (Water Surface,
Peak)
ft³41,569Volume (Peak)
Mass Balance (ft³)
ft³0Volume (Initial)
ft³63,475Volume (Total Inflow)
ft³0Volume (Total Infiltration)
ft³41,839Volume (Total Outlet
Outflow)
ft³21,613Volume (Retained)
ft³-22Volume (Unrouted)
%0.0Error (Mass Balance)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 10 YearLabel: SCM A (IN)
Return Event: 10 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft357.00Elevation (Water Surface,
Initial)
ft³0Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s34.75Flow (Peak In) min721.00Time to Peak (Flow, In)
ft³/s9.08Flow (Peak Outlet) min732.00Time to Peak (Flow, Outlet)
ft361.29Elevation (Water Surface,
Peak)
ft³49,900Volume (Peak)
Mass Balance (ft³)
ft³0Volume (Initial)
ft³93,434Volume (Total Inflow)
ft³0Volume (Total Infiltration)
ft³69,238Volume (Total Outlet
Outflow)
ft³24,156Volume (Retained)
ft³-40Volume (Unrouted)
%0.0Error (Mass Balance)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 25 YearLabel: SCM A (IN)
Return Event: 25 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft357.00Elevation (Water Surface,
Initial)
ft³0Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s38.29Flow (Peak In) min721.00Time to Peak (Flow, In)
ft³/s18.68Flow (Peak Outlet) min728.00Time to Peak (Flow, Outlet)
ft361.50Elevation (Water Surface,
Peak)
ft³52,991Volume (Peak)
Mass Balance (ft³)
ft³0Volume (Initial)
ft³111,086Volume (Total Inflow)
ft³0Volume (Total Infiltration)
ft³85,377Volume (Total Outlet
Outflow)
ft³25,662Volume (Retained)
ft³-47Volume (Unrouted)
%0.0Error (Mass Balance)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM A (IN)
Return Event: 100 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft357.00Elevation (Water Surface,
Initial)
ft³0Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s43.00Flow (Peak In) min721.00Time to Peak (Flow, In)
ft³/s29.52Flow (Peak Outlet) min725.00Time to Peak (Flow, Outlet)
ft361.73Elevation (Water Surface,
Peak)
ft³56,274Volume (Peak)
Mass Balance (ft³)
ft³0Volume (Initial)
ft³139,138Volume (Total Inflow)
ft³0Volume (Total Infiltration)
ft³111,643Volume (Total Outlet
Outflow)
ft³27,443Volume (Retained)
ft³-52Volume (Unrouted)
%0.0Error (Mass Balance)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM A
Return Event: 100 yearsSubsection: Elevation-Area Volume Curve
Volume (Total)
(ft³)
Volume
(ft³)
A1+A2+sqr
(A1*A2)
(ft²)
Area
(ft²)
Planimeter
(ft²)
Elevation
(ft)
0008,0980.0357.00
4,4714,47126,8279,8140.0357.50
9,5145,04330,25610,3590.0358.00
32,51623,00234,50312,6820.0360.00
60,39027,87441,81115,2310.0362.00
76,29615,90647,71816,5910.0363.00
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM A
Return Event: 100 yearsSubsection: Outlet Input Data
Requested Pond Water Surface Elevations
ft357.00Minimum (Headwater)
ft0.10Increment (Headwater)
ft363.00Maximum (Headwater)
Outlet Connectivity
E2
(ft)
E1
(ft)
OutfallDirectionOutlet IDStructure Type
363.00358.75CulvertForwardOrificeOrifice-Circular
363.00361.00CulvertForwardRiserInlet Box
363.00357.00CulvertForwardWQ OrificeOrifice-Circular
363.00356.50TWForwardCulvertCulvert-Circular
(N/A)(N/A)TailwaterTailwater Settings
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM A
Return Event: 100 yearsSubsection: Outlet Input Data
Structure ID: Riser
Structure Type: Inlet Box
1Number of Openings
ft361.00Elevation
ft²16.0Orifice Area
0.6Orifice Coefficient
ft16.00Weir Length
(ft^0.5)/s3.00Weir Coefficient
1.0K Reverse
0.0Manning's n
0.0Kev, Charged Riser
FalseWeir Submergence
FalseOrifice H to crest
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM A
Return Event: 100 yearsSubsection: Outlet Input Data
Structure ID: Culvert
Structure Type: Culvert-Circular
1Number of Barrels
in24.00Diameter
ft47.00Length
ft47.01Length (Computed Barrel)
ft/ft0.021Slope (Computed)
Outlet Control Data
0.013Manning's n
0.5Ke
0.0Kb
0.0Kr
ft0.00Convergence Tolerance
Inlet Control Data
Form 1Equation Form
0.0098K
2.0000M
0.0398C
0.6700Y
1.1T1 ratio (HW/D)
1.3T2 ratio (HW/D)
-0.5Slope Correction Factor
Use unsubmerged inlet control 0 equation below T1 elevation.
Use submerged inlet control 0 equation above T2 elevation
In transition zone between unsubmerged and submerged inlet
control,
interpolate between flows at T1 & T2...
ft358.80T1 Elevation ft³/s15.55T1 Flow
ft359.09T2 Elevation ft³/s17.77T2 Flow
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM A
Return Event: 100 yearsSubsection: Outlet Input Data
Structure ID: WQ Orifice
Structure Type: Orifice-Circular
1Number of Openings
ft357.00Elevation
in1.75Orifice Diameter
0.6Orifice Coefficient
Structure ID: Orifice
Structure Type: Orifice-Circular
1Number of Openings
ft358.75Elevation
in6.00Orifice Diameter
0.6Orifice Coefficient
Structure ID: TW
Structure Type: TW Setup, DS Channel
Free OutfallTailwater Type
Convergence Tolerances
30Maximum Iterations
ft0.01Tailwater Tolerance
(Minimum)
ft0.50Tailwater Tolerance
(Maximum)
ft0.01Headwater Tolerance
(Minimum)
ft0.50Headwater Tolerance
(Maximum)
ft³/s0.001Flow Tolerance (Minimum)
ft³/s10.000Flow Tolerance (Maximum)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM A
Return Event: 100 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
(no Q: Orifice,Riser,WQ
Orifice,Culvert)
0.00(N/A)0.00357.00
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.01357.10
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.03357.20
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.04357.30
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.05357.40
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.05357.50
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.06357.60
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.06357.70
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.07357.80
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.07357.90
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.08358.00
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.08358.10
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.09358.20
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.09358.30
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.09358.40
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.10358.50
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.10358.60
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.10358.70
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.10358.75
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.11358.80
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.16358.90
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.25359.00
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.36359.10
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.50359.20
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.64359.30
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.72359.40
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.79359.50
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM A
Return Event: 100 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.86359.60
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.92359.70
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.98359.80
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.03359.90
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.08360.00
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.13360.10
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.18360.20
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.22360.30
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.26360.40
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.31360.50
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.35360.60
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.38360.70
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.42360.80
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.46360.90
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.49361.00
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)3.04361.10
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)5.84361.20
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)9.46361.30
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)13.73361.40
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)18.51361.50
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)23.57361.60
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)28.84361.70
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)31.42361.80
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)31.82361.90
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)32.20362.00
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)32.58362.10
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)32.96362.20
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM A
Return Event: 100 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)33.34362.30
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)33.71362.40
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)34.07362.50
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)34.43362.60
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)34.79362.70
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)35.14362.80
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)35.50362.90
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)35.85363.00
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM A (IN)
Return Event: 100 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft361.00Elevation (Water Surface,
Initial)
ft³45,815Volume (Initial)
ft³/s1.49Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s1.49Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s43.00Flow (Peak In) min721.00Time to Peak (Flow, In)
ft³/s31.21Flow (Peak Outlet) min725.00Time to Peak (Flow, Outlet)
ft361.79Elevation (Water Surface,
Peak)
ft³57,249Volume (Peak)
Mass Balance (ft³)
ft³45,815Volume (Initial)
ft³139,138Volume (Total Inflow)
ft³0Volume (Total Infiltration)
ft³157,459Volume (Total Outlet
Outflow)
ft³27,443Volume (Retained)
ft³-52Volume (Unrouted)
%0.0Error (Mass Balance)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Project Date 9/12/2019
Project No.Designer CGH
Outlet ID
Flow, Q10-yr 9.1 cfs
Slope, S 2.13 %
Pipe Diameter, Do 24 inches
Pipe Diameter, Do 2.0 feet
Number of pipes 1
Pipe separation 0 feet
Manning's n 0.013
Zone from graph above =2
Outlet pipe diameter 24 in.Length =12.0 ft.
Outlet flowrate 9.1 cfs Width =6.0 ft.
Outlet velocity 9.0 ft/sec Stone diameter =6 in.
Material =Class B Thickness =22 in.
Zone Material Diameter Thickness Length Width
1 Class A 3 9 4 x D(o)3 x D(o)
2 Class B 6 22 6 x D(o)3 x D(o)
3 Class I 13 22 8 x D(o)3 x D(o)
4 Class I 13 22 8 x D(o)3 x D(o)
5 Class II 23 27 10 x D(o)3 x D(o)
6 Class II 23 27 10 x D(o)3 x D(o)
7
1. Calculations based on NY DOT method - Pages 8.06.05 through 8.06.06 in NC Erosion Control Manual
2. Outlet velocity based on full-flow velocity
DESIGN OF RIPRAP OUTLET PROTECTION WORKSHEET
Flex Buildings - TW Alexander
MPP-18020
SCM A
Special study required
9.0 ft/sec
0
5
10
15
20
25
0 1 2 3 4 5 6 7 8 9 10Velocity (ft/sec)Pipe diameter (ft)
Figure 8.06.b.1
Zone 1 Zone 2
Zone 3
Zone 4
Zone 5
Zone 6 Zone 7
SCM - Rip Rap Outlet Protection Design9/12/2019

STORMWATER CONTROL MEASURE “B”
CALCULATIONS

FLEX BUILDINGS – TW ALEXANDER
MPP-18020
Flex Buildings - TW Alexander
MPP-18020
STORMWATER CONTROL MEASURE
SSFxn Above NP
G. Harrell
9/12/2019
STAGE-STORAGE FUNCTION - ABOVE NORMAL POOL
Average Incremental Accumulated Estimated
Contour Contour Contour Contour Stage
Contour Stage Area Area Volume Volume w/ S-S Fxn
(feet)(feet)(SF)(SF)(CF)(CF)(feet)
354.0 0.00 13,800
354.5 0.50 16,226 15013 7507 7507 0.51
355.0 1.00 16,984 16605 8303 15809 0.99
356.0 2.00 18,644 17814 17814 33623 1.96
358.0 4.00 21,463 20054 40107 73730 3.97
360.0 6.00 24,379 22921 45842 119572 6.13
1.111752985 9.67629062
15935.27717
KS =15935
b =1.1118
y = 15935x1.1118
R² = 0.9997
0
20000
40000
60000
80000
100000
120000
140000
0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00Storage (CF)Stage (feet)
Storage vs. Stage
[PROJECT NAME]
[PROJECT NUMBER]
STORMWATER CONTROL MEASURE
Surface Area Calculation
[DESIGNER/ENGINEER]
9/12/2019
WET DETENTION BASIN SUMMARY
From Stormwater Best Management Practices Manual . NCDENR: Division of Water Quality.
Enter the drainage area characteristics ==>
9.16 acres
5.78 acres
Note The basin must be sized to treat all impervious surface runoff draining into the pond, not just the impervious
surface from on-site development.
Drainage area =9.16 acres @ 63.1%impervious
Estimate the surface area required at pond normal pool elevation ==>
Wet Detention Basins are based on an minimum average depth of =3.00 feet (hard coded)
From the DWQ BMP Handbook, the required SA/DA ratio for 85%TSS Removal ==>
3.0 3.00 3.5
Lower Boundary =>60.0 2.40 2.22
Site % impervious =>63.1 2.55 2.55 2.35
Upper Boundary =>70.0 2.88 2.64
Therefore, SA/DA required =2.55
Surface area required at normal pool =10,163 ft2
=0.23 acres
Surface area provided at normal pool =13,800 ft2
Total drainage area to pond =
Total impervious area to pond =
[PROJECT NAME]
[PROJECT NUMBER]
STORMWATER CONTROL MEASURE
WQV Calculation
[DESIGNER/ENGINEER]
9/12/2019
DETERMINATION OF WATER QUALITY VOLUME
WQ V = (P)(R V )(A)/12
where,
WQV = water quality volume (in acre-ft)
RV = 0.05+0.009(I) where I is percent impervious cover
A = area in acres
P = rainfall (in inches)
Input data:
Total area, A =9.16 acres
Impervious area =5.78 acres
Percent impervious cover, I =63.1 %
Rainfall, P =1.00 inches
Calculated values:
RV =0.62
WQV =0.47 acre-ft
=20536 cf.
ASSOCIATED DEPTH IN POND
WQV =20536 cf.
Stage / Storage Data:
Ks =15935
b =1.112
Zo =354.00
Volume in 1" rainfall =20536 cu. ft
Calculated values:
Depth of WQv in Basin =1.26 ft
=15.07 inches
Elevation =355.26 ft
[PROJECT NAME]
[PROJECT NUMBER]
STORMWATER CONTROL MEASURE
WQV Drawdown Calculation
[DESIGNER/ENGINEER]
9/12/2019
DRAWDOWN ORIFICE DESIGN
D orifice =2.25 inch
# orifices =1
Ks =15935
b =1.1118
Cd orifice =0.60
Normal Pool Elevation =354.00 feet
Volume @ Normal Pool =0 cf
Orifice Invert =354.00 feet
WSEL @ 1" Runoff Volume =355.26 feet
WSEL Vol. Stored Orifice Flow Avg. Flow Incr. Vol.Incr. Time
(feet)(cf)(cfs)(cfs)(cf)(sec)
355.26 20536 0.143
355.15 18550 0.136 0.140 1985 14216
355.04 16586 0.129 0.133 1964 14819
354.93 14645 0.121 0.125 1941 15524
354.82 12730 0.113 0.117 1915 16367
354.71 10843 0.104 0.108 1887 17400
354.60 8989 0.094 0.099 1854 18712
354.49 7173 0.083 0.089 1816 20462
354.38 5402 0.071 0.077 1771 22986
354.27 3688 0.055 0.063 1713 27157
354.16 2054 0.032 0.044 1635 37549
Drawdown Time =2.37 days
By comparison, if calculated by the average head over the orifice
(assuming average head is half the total depth), the result would be:
Average driving head on orifice = 0.581 feet
Orifice composite loss coefficient = 0.600
Cross-sectional area of siphon = 0.028 sf
Q =0.1014 cfs
Drawdown Time = Volume / Flowrate / 86400 (sec/day)
Drawdown Time = 2.34 days
Storm Event: 1 YearLabel: SCM B
Return Event: 1 yearsSubsection: Elevation-Area Volume Curve
Volume (Total)
(ft³)
Volume
(ft³)
A1+A2+sqr
(A1*A2)
(ft²)
Area
(ft²)
Planimeter
(ft²)
Elevation
(ft)
00013,8000.0354.00
7,4987,49844,99016,2260.0354.50
15,8008,30249,81116,9840.0355.00
33,60817,80853,42318,6440.0356.00
73,68240,07460,11121,4630.0358.00
119,49345,81168,71724,3790.0360.00
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM B
Return Event: 1 yearsSubsection: Outlet Input Data
Requested Pond Water Surface Elevations
ft354.00Minimum (Headwater)
ft0.10Increment (Headwater)
ft360.00Maximum (Headwater)
Outlet Connectivity
E2
(ft)
E1
(ft)
OutfallDirectionOutlet IDStructure Type
360.00355.75CulvertForwardOrificeOrifice-Circular
360.00358.00CulvertForwardRiserInlet Box
360.00354.00CulvertForwardWQ OrificeOrifice-Circular
360.00353.50TWForwardCulvertCulvert-Circular
(N/A)(N/A)TailwaterTailwater Settings
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM B
Return Event: 1 yearsSubsection: Outlet Input Data
Structure ID: Culvert
Structure Type: Culvert-Circular
1Number of Barrels
in30.00Diameter
ft56.00Length
ft56.00Length (Computed Barrel)
ft/ft0.009Slope (Computed)
Outlet Control Data
0.013Manning's n
0.5Ke
0.0Kb
0.0Kr
ft0.00Convergence Tolerance
Inlet Control Data
Form 1Equation Form
0.0098K
2.0000M
0.0398C
0.6700Y
1.2T1 ratio (HW/D)
1.3T2 ratio (HW/D)
-0.5Slope Correction Factor
Use unsubmerged inlet control 0 equation below T1 elevation.
Use submerged inlet control 0 equation above T2 elevation
In transition zone between unsubmerged and submerged inlet
control,
interpolate between flows at T1 & T2...
ft356.39T1 Elevation ft³/s27.16T1 Flow
ft356.76T2 Elevation ft³/s31.05T2 Flow
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM B
Return Event: 1 yearsSubsection: Outlet Input Data
Structure ID: Riser
Structure Type: Inlet Box
1Number of Openings
ft358.00Elevation
ft²16.0Orifice Area
0.6Orifice Coefficient
ft16.00Weir Length
(ft^0.5)/s3.00Weir Coefficient
1.0K Reverse
0.0Manning's n
0.0Kev, Charged Riser
FalseWeir Submergence
FalseOrifice H to crest
Structure ID: WQ Orifice
Structure Type: Orifice-Circular
1Number of Openings
ft354.00Elevation
in2.25Orifice Diameter
0.6Orifice Coefficient
Structure ID: Orifice
Structure Type: Orifice-Circular
1Number of Openings
ft355.75Elevation
in6.00Orifice Diameter
0.6Orifice Coefficient
Structure ID: TW
Structure Type: TW Setup, DS Channel
Free OutfallTailwater Type
Convergence Tolerances
30Maximum Iterations
ft0.01Tailwater Tolerance
(Minimum)
ft0.50Tailwater Tolerance
(Maximum)
ft0.01Headwater Tolerance
(Minimum)
ft0.50Headwater Tolerance
(Maximum)
ft³/s0.001Flow Tolerance (Minimum)
ft³/s10.000Flow Tolerance (Maximum)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM B
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
(no Q: Orifice,Riser,WQ
Orifice,Culvert)
0.00(N/A)0.00354.00
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.01354.10
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.04354.20
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.06354.30
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.07354.40
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.08354.50
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.09354.60
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.10354.70
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.11354.80
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.12354.90
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.13355.00
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.13355.10
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.14355.20
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.15355.30
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.15355.40
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.16355.50
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.16355.60
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.17355.70
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.17355.75
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.18355.80
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.23355.90
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.32356.00
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.44356.10
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.58356.20
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.72356.30
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.80356.40
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.87356.50
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM B
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.94356.60
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.01356.70
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.06356.80
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.12356.90
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.17357.00
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.22357.10
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.27357.20
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.32357.30
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.36357.40
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.40357.50
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.44357.60
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.48357.70
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.52357.80
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.56357.90
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.60358.00
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)3.14358.10
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)5.94358.20
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)9.55358.30
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)13.83358.40
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)18.68358.50
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)23.94358.60
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)29.62358.70
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)35.66358.80
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)41.96358.90
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)48.10359.00
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)48.82359.10
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)49.44359.20
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM B
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)50.04359.30
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)50.64359.40
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)51.24359.50
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)51.82359.60
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)52.40359.70
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)52.98359.80
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)53.55359.90
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)54.11360.00
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM B (IN)
Return Event: 1 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft354.00Elevation (Water Surface,
Initial)
ft³0Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s36.68Flow (Peak In) min721.00Time to Peak (Flow, In)
ft³/s1.23Flow (Peak Outlet) min785.00Time to Peak (Flow, Outlet)
ft357.13Elevation (Water Surface,
Peak)
ft³55,490Volume (Peak)
Mass Balance (ft³)
ft³0Volume (Initial)
ft³82,067Volume (Total Inflow)
ft³0Volume (Total Infiltration)
ft³44,385Volume (Total Outlet
Outflow)
ft³37,646Volume (Retained)
ft³-37Volume (Unrouted)
%0.0Error (Mass Balance)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 2 YearLabel: SCM B (IN)
Return Event: 2 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft354.00Elevation (Water Surface,
Initial)
ft³0Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s43.58Flow (Peak In) min721.00Time to Peak (Flow, In)
ft³/s1.50Flow (Peak Outlet) min785.00Time to Peak (Flow, Outlet)
ft357.74Elevation (Water Surface,
Peak)
ft³68,245Volume (Peak)
Mass Balance (ft³)
ft³0Volume (Initial)
ft³101,129Volume (Total Inflow)
ft³0Volume (Total Infiltration)
ft³56,950Volume (Total Outlet
Outflow)
ft³44,122Volume (Retained)
ft³-56Volume (Unrouted)
%0.1Error (Mass Balance)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 10 YearLabel: SCM B (IN)
Return Event: 10 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft354.00Elevation (Water Surface,
Initial)
ft³0Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s56.89Flow (Peak In) min721.00Time to Peak (Flow, In)
ft³/s12.72Flow (Peak Outlet) min750.00Time to Peak (Flow, Outlet)
ft358.37Elevation (Water Surface,
Peak)
ft³81,809Volume (Peak)
Mass Balance (ft³)
ft³0Volume (Initial)
ft³151,033Volume (Total Inflow)
ft³0Volume (Total Infiltration)
ft³98,103Volume (Total Outlet
Outflow)
ft³52,860Volume (Retained)
ft³-70Volume (Unrouted)
%0.0Error (Mass Balance)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 25 YearLabel: SCM B (IN)
Return Event: 25 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft354.00Elevation (Water Surface,
Initial)
ft³0Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s63.08Flow (Peak In) min721.00Time to Peak (Flow, In)
ft³/s26.64Flow (Peak Outlet) min729.00Time to Peak (Flow, Outlet)
ft358.65Elevation (Water Surface,
Peak)
ft³87,879Volume (Peak)
Mass Balance (ft³)
ft³0Volume (Initial)
ft³180,590Volume (Total Inflow)
ft³0Volume (Total Infiltration)
ft³124,576Volume (Total Outlet
Outflow)
ft³55,937Volume (Retained)
ft³-76Volume (Unrouted)
%0.0Error (Mass Balance)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM B (IN)
Return Event: 100 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft354.00Elevation (Water Surface,
Initial)
ft³0Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s71.33Flow (Peak In) min721.00Time to Peak (Flow, In)
ft³/s45.49Flow (Peak Outlet) min726.00Time to Peak (Flow, Outlet)
ft358.96Elevation (Water Surface,
Peak)
ft³94,887Volume (Peak)
Mass Balance (ft³)
ft³0Volume (Initial)
ft³227,696Volume (Total Inflow)
ft³0Volume (Total Infiltration)
ft³168,970Volume (Total Outlet
Outflow)
ft³58,647Volume (Retained)
ft³-80Volume (Unrouted)
%0.0Error (Mass Balance)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM B
Return Event: 100 yearsSubsection: Elevation-Area Volume Curve
Volume (Total)
(ft³)
Volume
(ft³)
A1+A2+sqr
(A1*A2)
(ft²)
Area
(ft²)
Planimeter
(ft²)
Elevation
(ft)
00013,8000.0354.00
7,4987,49844,99016,2260.0354.50
15,8008,30249,81116,9840.0355.00
33,60817,80853,42318,6440.0356.00
73,68240,07460,11121,4630.0358.00
119,49345,81168,71724,3790.0360.00
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM B
Return Event: 100 yearsSubsection: Outlet Input Data
Requested Pond Water Surface Elevations
ft354.00Minimum (Headwater)
ft0.10Increment (Headwater)
ft360.00Maximum (Headwater)
Outlet Connectivity
E2
(ft)
E1
(ft)
OutfallDirectionOutlet IDStructure Type
360.00355.75CulvertForwardOrificeOrifice-Circular
360.00358.00CulvertForwardRiserInlet Box
360.00354.00CulvertForwardWQ OrificeOrifice-Circular
360.00353.50TWForwardCulvertCulvert-Circular
(N/A)(N/A)TailwaterTailwater Settings
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM B
Return Event: 100 yearsSubsection: Outlet Input Data
Structure ID: Culvert
Structure Type: Culvert-Circular
1Number of Barrels
in30.00Diameter
ft56.00Length
ft56.00Length (Computed Barrel)
ft/ft0.009Slope (Computed)
Outlet Control Data
0.013Manning's n
0.5Ke
0.0Kb
0.0Kr
ft0.00Convergence Tolerance
Inlet Control Data
Form 1Equation Form
0.0098K
2.0000M
0.0398C
0.6700Y
1.2T1 ratio (HW/D)
1.3T2 ratio (HW/D)
-0.5Slope Correction Factor
Use unsubmerged inlet control 0 equation below T1 elevation.
Use submerged inlet control 0 equation above T2 elevation
In transition zone between unsubmerged and submerged inlet
control,
interpolate between flows at T1 & T2...
ft356.39T1 Elevation ft³/s27.16T1 Flow
ft356.76T2 Elevation ft³/s31.05T2 Flow
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM B
Return Event: 100 yearsSubsection: Outlet Input Data
Structure ID: Riser
Structure Type: Inlet Box
1Number of Openings
ft358.00Elevation
ft²16.0Orifice Area
0.6Orifice Coefficient
ft16.00Weir Length
(ft^0.5)/s3.00Weir Coefficient
1.0K Reverse
0.0Manning's n
0.0Kev, Charged Riser
FalseWeir Submergence
FalseOrifice H to crest
Structure ID: WQ Orifice
Structure Type: Orifice-Circular
1Number of Openings
ft354.00Elevation
in2.25Orifice Diameter
0.6Orifice Coefficient
Structure ID: Orifice
Structure Type: Orifice-Circular
1Number of Openings
ft355.75Elevation
in6.00Orifice Diameter
0.6Orifice Coefficient
Structure ID: TW
Structure Type: TW Setup, DS Channel
Free OutfallTailwater Type
Convergence Tolerances
30Maximum Iterations
ft0.01Tailwater Tolerance
(Minimum)
ft0.50Tailwater Tolerance
(Maximum)
ft0.01Headwater Tolerance
(Minimum)
ft0.50Headwater Tolerance
(Maximum)
ft³/s0.001Flow Tolerance (Minimum)
ft³/s10.000Flow Tolerance (Maximum)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM B
Return Event: 100 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
(no Q: Orifice,Riser,WQ
Orifice,Culvert)
0.00(N/A)0.00354.00
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.01354.10
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.04354.20
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.06354.30
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.07354.40
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.08354.50
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.09354.60
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.10354.70
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.11354.80
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.12354.90
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.13355.00
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.13355.10
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.14355.20
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.15355.30
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.15355.40
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.16355.50
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.16355.60
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.17355.70
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.17355.75
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.18355.80
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.23355.90
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.32356.00
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.44356.10
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.58356.20
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.72356.30
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.80356.40
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.87356.50
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM B
Return Event: 100 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.94356.60
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.01356.70
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.06356.80
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.12356.90
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.17357.00
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.22357.10
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.27357.20
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.32357.30
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.36357.40
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.40357.50
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.44357.60
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.48357.70
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.52357.80
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.56357.90
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.60358.00
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)3.14358.10
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)5.94358.20
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)9.55358.30
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)13.83358.40
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)18.68358.50
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)23.94358.60
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)29.62358.70
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)35.66358.80
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)41.96358.90
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)48.10359.00
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)48.82359.10
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)49.44359.20
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM B
Return Event: 100 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)50.04359.30
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)50.64359.40
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)51.24359.50
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)51.82359.60
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)52.40359.70
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)52.98359.80
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)53.55359.90
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)54.11360.00
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM B (IN)
Return Event: 100 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft358.00Elevation (Water Surface,
Initial)
ft³73,682Volume (Initial)
ft³/s1.60Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s1.60Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s71.33Flow (Peak In) min721.00Time to Peak (Flow, In)
ft³/s48.59Flow (Peak Outlet) min725.00Time to Peak (Flow, Outlet)
ft359.07Elevation (Water Surface,
Peak)
ft³97,417Volume (Peak)
Mass Balance (ft³)
ft³73,682Volume (Initial)
ft³227,696Volume (Total Inflow)
ft³0Volume (Total Infiltration)
ft³242,651Volume (Total Outlet
Outflow)
ft³58,647Volume (Retained)
ft³-80Volume (Unrouted)
%0.0Error (Mass Balance)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Project Date 9/12/2019
Project No.Designer CGH
Outlet ID
Flow, Q10-yr 12.7 cfs
Slope, S 0.89 %
Pipe Diameter, Do 30 inches
Pipe Diameter, Do 2.5 feet
Number of pipes 1
Pipe separation 0 feet
Manning's n 0.013
Zone from graph above =2
Outlet pipe diameter 30 in.Length =15.0 ft.
Outlet flowrate 12.7 cfs Width =7.5 ft.
Outlet velocity 7.1 ft/sec Stone diameter =6 in.
Material =Class B Thickness =22 in.
Zone Material Diameter Thickness Length Width
1 Class A 3 9 4 x D(o)3 x D(o)
2 Class B 6 22 6 x D(o)3 x D(o)
3 Class I 13 22 8 x D(o)3 x D(o)
4 Class I 13 22 8 x D(o)3 x D(o)
5 Class II 23 27 10 x D(o)3 x D(o)
6 Class II 23 27 10 x D(o)3 x D(o)
7
1. Calculations based on NY DOT method - Pages 8.06.05 through 8.06.06 in NC Erosion Control Manual
2. Outlet velocity based on full-flow velocity
DESIGN OF RIPRAP OUTLET PROTECTION WORKSHEET
Flex Buildings - TW Alexander
MPP-18020
SCM B
Special study required
7.1 ft/sec
0
5
10
15
20
25
0 1 2 3 4 5 6 7 8 9 10Velocity (ft/sec)Pipe diameter (ft)
Figure 8.06.b.1
Zone 1 Zone 2
Zone 3
Zone 4
Zone 5
Zone 6 Zone 7
SCM - Rip Rap Outlet Protection Design9/12/2019

STORMWATER CONTROL MEASURE “C”
CALCULATIONS

FLEX BUILDINGS – TW ALEXANDER
MPP-18020
Flex Buildings - TW Alexander
MPP-18020
STORMWATER CONTROL MEASURE
SSFxn Above NP
G. Harrell
9/12/2019
STAGE-STORAGE FUNCTION - ABOVE NORMAL POOL
Average Incremental Accumulated Estimated
Contour Contour Contour Contour Stage
Contour Stage Area Area Volume Volume w/ S-S Fxn
(feet)(feet)(SF)(SF)(CF)(CF)(feet)
352.0 0.00 16,887
352.5 0.50 19,811 18349 9175 9175 0.51
353.0 1.00 20,732 20272 10136 19310 0.99
354.0 2.00 22,598 21665 21665 40975 1.95
356.0 4.00 26,488 24543 49086 90061 3.96
358.0 6.00 30,605 28547 57093 147154 6.15
1.113659061 9.876302293
19463.61868
KS =19464
b =1.1137
y = 19464x1.1137
R² = 0.9996
0
20000
40000
60000
80000
100000
120000
140000
160000
0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00Storage (CF)Stage (feet)
Storage vs. Stage
[PROJECT NAME]
[PROJECT NUMBER]
STORMWATER CONTROL MEASURE
Surface Area Calculation
[DESIGNER/ENGINEER]
9/12/2019
WET DETENTION BASIN SUMMARY
From Stormwater Best Management Practices Manual . NCDENR: Division of Water Quality.
Enter the drainage area characteristics ==>
10.74 acres
8.50 acres
Note The basin must be sized to treat all impervious surface runoff draining into the pond, not just the impervious
surface from on-site development.
Drainage area =10.74 acres @ 79.1%impervious
Estimate the surface area required at pond normal pool elevation ==>
Wet Detention Basins are based on an minimum average depth of =3.25 feet (hard coded)
From the DWQ BMP Handbook, the required SA/DA ratio for 85%TSS Removal ==>
3.0 3.25 3.5
Lower Boundary =>70.0 2.88 2.64
Site % impervious =>79.1 3.32 3.18 3.03
Upper Boundary =>80.0 3.36 3.07
Therefore, SA/DA required =3.18
Surface area required at normal pool =14,851 ft2
=0.34 acres
Surface area provided at normal pool =16,887 ft2
Total drainage area to pond =
Total impervious area to pond =
[PROJECT NAME]
[PROJECT NUMBER]
STORMWATER CONTROL MEASURE
WQV Calculation
[DESIGNER/ENGINEER]
9/12/2019
DETERMINATION OF WATER QUALITY VOLUME
WQ V = (P)(R V )(A)/12
where,
WQV = water quality volume (in acre-ft)
RV = 0.05+0.009(I) where I is percent impervious cover
A = area in acres
P = rainfall (in inches)
Input data:
Total area, A =10.74 acres
Impervious area =8.50 acres
Percent impervious cover, I =79.1 %
Rainfall, P =1.00 inches
Calculated values:
RV =0.76
WQV =0.68 acre-ft
=29705 cf.
ASSOCIATED DEPTH IN POND
WQV =29705 cf.
Stage / Storage Data:
Ks =19464
b =1.114
Zo =352.00
Volume in 1" rainfall =29705 cu. ft
Calculated values:
Depth of WQv in Basin =1.46 ft
=17.54 inches
Elevation =353.46 ft
[PROJECT NAME]
[PROJECT NUMBER]
STORMWATER CONTROL MEASURE
WQV Drawdown Calculation
[DESIGNER/ENGINEER]
9/12/2019
DRAWDOWN ORIFICE DESIGN
D orifice =2.75 inch
# orifices =1
Ks =19464
b =1.1137
Cd orifice =0.60
Normal Pool Elevation =352.00 feet
Volume @ Normal Pool =0 cf
Orifice Invert =352.00 feet
WSEL @ 1" Runoff Volume =353.46 feet
WSEL Vol. Stored Orifice Flow Avg. Flow Incr. Vol.Incr. Time
(feet)(cf)(cfs)(cfs)(cf)(sec)
353.46 29705 0.230
353.33 26830 0.219 0.225 2875 12803
353.21 23986 0.207 0.213 2844 13346
353.08 21176 0.195 0.201 2810 13983
352.95 18404 0.181 0.188 2772 14743
352.82 15674 0.167 0.174 2730 15677
352.70 12992 0.151 0.159 2682 16864
352.57 10366 0.134 0.142 2626 18453
352.44 7806 0.113 0.123 2560 20753
352.31 5331 0.088 0.101 2476 24584
352.18 2970 0.049 0.069 2360 34447
Drawdown Time =2.15 days
By comparison, if calculated by the average head over the orifice
(assuming average head is half the total depth), the result would be:
Average driving head on orifice = 0.674 feet
Orifice composite loss coefficient = 0.600
Cross-sectional area of siphon = 0.041 sf
Q =0.1630 cfs
Drawdown Time = Volume / Flowrate / 86400 (sec/day)
Drawdown Time = 2.11 days
Storm Event: 1 YearLabel: SCM C
Return Event: 1 yearsSubsection: Elevation-Area Volume Curve
Volume (Total)
(ft³)
Volume
(ft³)
A1+A2+sqr
(A1*A2)
(ft²)
Area
(ft²)
Planimeter
(ft²)
Elevation
(ft)
00016,8870.0352.00
9,1659,16554,98919,8110.0352.50
19,30010,13560,80920,7320.0353.00
40,95821,65864,97522,5980.0354.00
89,99249,03573,55226,4880.0356.00
147,03657,04385,56530,6050.0358.00
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM C
Return Event: 1 yearsSubsection: Outlet Input Data
Requested Pond Water Surface Elevations
ft352.00Minimum (Headwater)
ft0.10Increment (Headwater)
ft358.00Maximum (Headwater)
Outlet Connectivity
E2
(ft)
E1
(ft)
OutfallDirectionOutlet IDStructure Type
358.00353.75CulvertForwardOrificeOrifice-Circular
358.00356.00CulvertForwardRiserInlet Box
358.00352.00CulvertForwardWQ OrificeOrifice-Circular
358.00351.50TWForwardCulvertCulvert-Circular
(N/A)(N/A)TailwaterTailwater Settings
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM C
Return Event: 1 yearsSubsection: Outlet Input Data
Structure ID: Culvert
Structure Type: Culvert-Circular
1Number of Barrels
in24.00Diameter
ft53.00Length
ft53.00Length (Computed Barrel)
ft/ft0.009Slope (Computed)
Outlet Control Data
0.013Manning's n
0.5Ke
0.0Kb
0.0Kr
ft0.00Convergence Tolerance
Inlet Control Data
Form 1Equation Form
0.0098K
2.0000M
0.0398C
0.6700Y
1.2T1 ratio (HW/D)
1.3T2 ratio (HW/D)
-0.5Slope Correction Factor
Use unsubmerged inlet control 0 equation below T1 elevation.
Use submerged inlet control 0 equation above T2 elevation
In transition zone between unsubmerged and submerged inlet
control,
interpolate between flows at T1 & T2...
ft353.81T1 Elevation ft³/s15.55T1 Flow
ft354.10T2 Elevation ft³/s17.77T2 Flow
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM C
Return Event: 1 yearsSubsection: Outlet Input Data
Structure ID: Riser
Structure Type: Inlet Box
1Number of Openings
ft356.00Elevation
ft²16.0Orifice Area
0.6Orifice Coefficient
ft16.00Weir Length
(ft^0.5)/s3.00Weir Coefficient
1.0K Reverse
0.0Manning's n
0.0Kev, Charged Riser
FalseWeir Submergence
FalseOrifice H to crest
Structure ID: WQ Orifice
Structure Type: Orifice-Circular
1Number of Openings
ft352.00Elevation
in2.75Orifice Diameter
0.6Orifice Coefficient
Structure ID: Orifice
Structure Type: Orifice-Circular
3Number of Openings
ft353.75Elevation
in8.00Orifice Diameter
0.6Orifice Coefficient
Structure ID: TW
Structure Type: TW Setup, DS Channel
Free OutfallTailwater Type
Convergence Tolerances
30Maximum Iterations
ft0.01Tailwater Tolerance
(Minimum)
ft0.50Tailwater Tolerance
(Maximum)
ft0.01Headwater Tolerance
(Minimum)
ft0.50Headwater Tolerance
(Maximum)
ft³/s0.001Flow Tolerance (Minimum)
ft³/s10.000Flow Tolerance (Maximum)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM C
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
(no Q: Orifice,Riser,WQ
Orifice,Culvert)
0.00(N/A)0.00352.00
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.01352.10
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.05352.20
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.09352.30
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.11352.40
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.12352.50
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.14352.60
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.15352.70
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.16352.80
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.18352.90
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.19353.00
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.20353.10
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.21353.20
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.22353.30
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.23353.40
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.23353.50
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.24353.60
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.25353.70
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.25353.75
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.28353.80
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.45353.90
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.76354.00
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.19354.10
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.71354.20
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)2.32354.30
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)2.97354.40
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)3.53354.50
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM C
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)3.90354.60
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)4.24354.70
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)4.56354.80
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)4.85354.90
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)5.12355.00
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)5.38355.10
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)5.64355.20
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)5.87355.30
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)6.10355.40
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)6.32355.50
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)6.53355.60
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)6.74355.70
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)6.94355.80
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)7.13355.90
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)7.32356.00
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)9.01356.10
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)11.95356.20
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)15.69356.30
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)19.58356.40
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)23.35356.50
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)27.03356.60
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)30.27356.70
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)31.38356.80
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)31.77356.90
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)32.16357.00
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)32.54357.10
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)32.91357.20
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM C
Return Event: 1 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)33.30357.30
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)33.66357.40
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)34.03357.50
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)34.39357.60
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)34.75357.70
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)35.11357.80
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)35.45357.90
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)35.80358.00
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 1 YearLabel: SCM C (IN)
Return Event: 1 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft352.00Elevation (Water Surface,
Initial)
ft³0Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s44.96Flow (Peak In) min721.00Time to Peak (Flow, In)
ft³/s4.73Flow (Peak Outlet) min754.00Time to Peak (Flow, Outlet)
ft354.86Elevation (Water Surface,
Peak)
ft³61,059Volume (Peak)
Mass Balance (ft³)
ft³0Volume (Initial)
ft³101,035Volume (Total Inflow)
ft³0Volume (Total Infiltration)
ft³62,536Volume (Total Outlet
Outflow)
ft³38,472Volume (Retained)
ft³-27Volume (Unrouted)
%0.0Error (Mass Balance)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 2 YearLabel: SCM C (IN)
Return Event: 2 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft352.00Elevation (Water Surface,
Initial)
ft³0Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s53.02Flow (Peak In) min721.00Time to Peak (Flow, In)
ft³/s6.00Flow (Peak Outlet) min754.00Time to Peak (Flow, Outlet)
ft355.36Elevation (Water Surface,
Peak)
ft³73,356Volume (Peak)
Mass Balance (ft³)
ft³0Volume (Initial)
ft³123,779Volume (Total Inflow)
ft³0Volume (Total Infiltration)
ft³84,463Volume (Total Outlet
Outflow)
ft³39,283Volume (Retained)
ft³-34Volume (Unrouted)
%0.0Error (Mass Balance)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 10 YearLabel: SCM C (IN)
Return Event: 10 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft352.00Elevation (Water Surface,
Initial)
ft³0Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s68.36Flow (Peak In) min721.00Time to Peak (Flow, In)
ft³/s14.56Flow (Peak Outlet) min751.00Time to Peak (Flow, Outlet)
ft356.27Elevation (Water Surface,
Peak)
ft³97,213Volume (Peak)
Mass Balance (ft³)
ft³0Volume (Initial)
ft³182,988Volume (Total Inflow)
ft³0Volume (Total Infiltration)
ft³142,184Volume (Total Outlet
Outflow)
ft³40,759Volume (Retained)
ft³-45Volume (Unrouted)
%0.0Error (Mass Balance)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 25 YearLabel: SCM C (IN)
Return Event: 25 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft352.00Elevation (Water Surface,
Initial)
ft³0Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s75.45Flow (Peak In) min721.00Time to Peak (Flow, In)
ft³/s23.76Flow (Peak Outlet) min731.00Time to Peak (Flow, Outlet)
ft356.51Elevation (Water Surface,
Peak)
ft³103,793Volume (Peak)
Mass Balance (ft³)
ft³0Volume (Initial)
ft³217,920Volume (Total Inflow)
ft³0Volume (Total Infiltration)
ft³176,593Volume (Total Outlet
Outflow)
ft³41,276Volume (Retained)
ft³-50Volume (Unrouted)
%0.0Error (Mass Balance)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM C (IN)
Return Event: 100 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft352.00Elevation (Water Surface,
Initial)
ft³0Volume (Initial)
ft³/s0.00Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.00Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s84.90Flow (Peak In) min721.00Time to Peak (Flow, In)
ft³/s31.84Flow (Peak Outlet) min730.00Time to Peak (Flow, Outlet)
ft356.92Elevation (Water Surface,
Peak)
ft³115,149Volume (Peak)
Mass Balance (ft³)
ft³0Volume (Initial)
ft³273,474Volume (Total Inflow)
ft³0Volume (Total Infiltration)
ft³231,797Volume (Total Outlet
Outflow)
ft³41,622Volume (Retained)
ft³-55Volume (Unrouted)
%0.0Error (Mass Balance)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM C
Return Event: 100 yearsSubsection: Elevation-Area Volume Curve
Volume (Total)
(ft³)
Volume
(ft³)
A1+A2+sqr
(A1*A2)
(ft²)
Area
(ft²)
Planimeter
(ft²)
Elevation
(ft)
00016,8870.0352.00
9,1659,16554,98919,8110.0352.50
19,30010,13560,80920,7320.0353.00
40,95821,65864,97522,5980.0354.00
89,99249,03573,55226,4880.0356.00
147,03657,04385,56530,6050.0358.00
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM C
Return Event: 100 yearsSubsection: Outlet Input Data
Requested Pond Water Surface Elevations
ft352.00Minimum (Headwater)
ft0.10Increment (Headwater)
ft358.00Maximum (Headwater)
Outlet Connectivity
E2
(ft)
E1
(ft)
OutfallDirectionOutlet IDStructure Type
358.00353.75CulvertForwardOrificeOrifice-Circular
358.00356.00CulvertForwardRiserInlet Box
358.00352.00CulvertForwardWQ OrificeOrifice-Circular
358.00351.50TWForwardCulvertCulvert-Circular
(N/A)(N/A)TailwaterTailwater Settings
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM C
Return Event: 100 yearsSubsection: Outlet Input Data
Structure ID: Culvert
Structure Type: Culvert-Circular
1Number of Barrels
in24.00Diameter
ft53.00Length
ft53.00Length (Computed Barrel)
ft/ft0.009Slope (Computed)
Outlet Control Data
0.013Manning's n
0.5Ke
0.0Kb
0.0Kr
ft0.00Convergence Tolerance
Inlet Control Data
Form 1Equation Form
0.0098K
2.0000M
0.0398C
0.6700Y
1.2T1 ratio (HW/D)
1.3T2 ratio (HW/D)
-0.5Slope Correction Factor
Use unsubmerged inlet control 0 equation below T1 elevation.
Use submerged inlet control 0 equation above T2 elevation
In transition zone between unsubmerged and submerged inlet
control,
interpolate between flows at T1 & T2...
ft353.81T1 Elevation ft³/s15.55T1 Flow
ft354.10T2 Elevation ft³/s17.77T2 Flow
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM C
Return Event: 100 yearsSubsection: Outlet Input Data
Structure ID: Riser
Structure Type: Inlet Box
1Number of Openings
ft356.00Elevation
ft²16.0Orifice Area
0.6Orifice Coefficient
ft16.00Weir Length
(ft^0.5)/s3.00Weir Coefficient
1.0K Reverse
0.0Manning's n
0.0Kev, Charged Riser
FalseWeir Submergence
FalseOrifice H to crest
Structure ID: WQ Orifice
Structure Type: Orifice-Circular
1Number of Openings
ft352.00Elevation
in2.75Orifice Diameter
0.6Orifice Coefficient
Structure ID: Orifice
Structure Type: Orifice-Circular
3Number of Openings
ft353.75Elevation
in8.00Orifice Diameter
0.6Orifice Coefficient
Structure ID: TW
Structure Type: TW Setup, DS Channel
Free OutfallTailwater Type
Convergence Tolerances
30Maximum Iterations
ft0.01Tailwater Tolerance
(Minimum)
ft0.50Tailwater Tolerance
(Maximum)
ft0.01Headwater Tolerance
(Minimum)
ft0.50Headwater Tolerance
(Maximum)
ft³/s0.001Flow Tolerance (Minimum)
ft³/s10.000Flow Tolerance (Maximum)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM C
Return Event: 100 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
(no Q: Orifice,Riser,WQ
Orifice,Culvert)
0.00(N/A)0.00352.00
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.01352.10
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.05352.20
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.09352.30
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.11352.40
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.12352.50
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.14352.60
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.15352.70
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.16352.80
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.18352.90
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.19353.00
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.20353.10
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.21353.20
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.22353.30
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.23353.40
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.23353.50
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.24353.60
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.25353.70
WQ Orifice,Culvert (no
Q: Orifice,Riser)
0.00(N/A)0.25353.75
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.28353.80
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.45353.90
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)0.76354.00
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.19354.10
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)1.71354.20
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)2.32354.30
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)2.97354.40
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)3.53354.50
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM C
Return Event: 100 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)3.90354.60
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)4.24354.70
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)4.56354.80
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)4.85354.90
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)5.12355.00
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)5.38355.10
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)5.64355.20
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)5.87355.30
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)6.10355.40
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)6.32355.50
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)6.53355.60
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)6.74355.70
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)6.94355.80
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)7.13355.90
Orifice,WQ Orifice,Culvert
(no Q: Riser)
0.00(N/A)7.32356.00
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)9.01356.10
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)11.95356.20
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)15.69356.30
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)19.58356.40
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)23.35356.50
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)27.03356.60
Orifice,Riser,WQ
Orifice,Culvert
0.00(N/A)30.27356.70
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)31.38356.80
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)31.77356.90
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)32.16357.00
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)32.54357.10
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)32.91357.20
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM C
Return Event: 100 yearsSubsection: Composite Rating Curve
Composite Outflow Summary
Contributing StructuresConvergence Error
(ft)
Tailwater Elevation
(ft)
Flow
(ft³/s)
Water Surface
Elevation
(ft)
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)33.30357.30
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)33.66357.40
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)34.03357.50
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)34.39357.60
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)34.75357.70
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)35.11357.80
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)35.45357.90
Riser,Culvert (no Q:
Orifice,WQ Orifice)
0.00(N/A)35.80358.00
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Storm Event: 100 YearLabel: SCM C (IN)
Return Event: 100 yearsSubsection: Level Pool Pond Routing Summary
Infiltration
No InfiltrationInfiltration Method
(Computed)
Initial Conditions
ft353.75Elevation (Water Surface,
Initial)
ft³35,368Volume (Initial)
ft³/s0.25Flow (Initial Outlet)
ft³/s0.00Flow (Initial Infiltration)
ft³/s0.25Flow (Initial, Total)
min1.00Time Increment
Inflow/Outflow Hydrograph Summary
ft³/s84.90Flow (Peak In) min721.00Time to Peak (Flow, In)
ft³/s32.04Flow (Peak Outlet) min730.00Time to Peak (Flow, Outlet)
ft356.97Elevation (Water Surface,
Peak)
ft³116,609Volume (Peak)
Mass Balance (ft³)
ft³35,368Volume (Initial)
ft³273,474Volume (Total Inflow)
ft³0Volume (Total Infiltration)
ft³267,164Volume (Total Outlet
Outflow)
ft³41,622Volume (Retained)
ft³-55Volume (Unrouted)
%0.0Error (Mass Balance)
9/12/2019MPP-18020
G HarrellMPP18020.ppc
Project Date 9/12/2019
Project No.Designer CGH
Outlet ID
Flow, Q10-yr 14.6 cfs
Slope, S 0.94 %
Pipe Diameter, Do 24 inches
Pipe Diameter, Do 2.0 feet
Number of pipes 1
Pipe separation 0 feet
Manning's n 0.013
Zone from graph above =2
Outlet pipe diameter 24 in.Length =12.0 ft.
Outlet flowrate 14.6 cfs Width =6.0 ft.
Outlet velocity 7.0 ft/sec Stone diameter =6 in.
Material =Class B Thickness =22 in.
Zone Material Diameter Thickness Length Width
1 Class A 3 9 4 x D(o)3 x D(o)
2 Class B 6 22 6 x D(o)3 x D(o)
3 Class I 13 22 8 x D(o)3 x D(o)
4 Class I 13 22 8 x D(o)3 x D(o)
5 Class II 23 27 10 x D(o)3 x D(o)
6 Class II 23 27 10 x D(o)3 x D(o)
7
1. Calculations based on NY DOT method - Pages 8.06.05 through 8.06.06 in NC Erosion Control Manual
2. Outlet velocity based on full-flow velocity
DESIGN OF RIPRAP OUTLET PROTECTION WORKSHEET
Flex Buildings - TW Alexander
MPP-18020
SCM C
Special study required
7.0 ft/sec
0
5
10
15
20
25
0 1 2 3 4 5 6 7 8 9 10Velocity (ft/sec)Pipe diameter (ft)
Figure 8.06.b.1
Zone 1 Zone 2
Zone 3
Zone 4
Zone 5
Zone 6 Zone 7
SCM - Rip Rap Outlet Protection Design9/12/2019