The URL can be used to link to this page

Home My WebLink AboutSW3210301_Design Calculations (Stormwater - Phase 2)_20210309 ¸ ¸ National Flood Hazard Layer FIRMette Legend 34°59'33.10"N SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT Without Base Flood Elevation (BFE) Zone A, V, A99 Zone AE, AO, AH, VE, AR With BFE or Depth SPECIAL FLOOD Regulatory Floodway HAZARD AREAS 0.2% Annual Chance Flood Hazard, Areas of 1% annual chance flood with average depth less than one foot or with drainage Zone X areas of less than one square mile Future Conditions 1% Annual Zone X Chance Flood Hazard Area with Reduced Flood Risk due to Zone X Levee. See Notes. OTHER AREAS OF Zone D Area with Flood Risk due to Levee FLOOD HAZARD NO SCREEN Zone X Area of Minimal Flood Hazard Effective LOMRs OTHER AREAS Zone D Area of Undetermined Flood Hazard Channel, Culvert, or Storm Sewer GENERAL STRUCTURES Levee, Dike, or Floodwall 20.2 Cross Sections with 1% Annual Chance B 17.5 Water Surface Elevation 8 Coastal Transect Base Flood Elevation Line (BFE) Limit of Study Jurisdiction Boundary Coastal Transect Baseline OTHER Profile Baseline FEATURES Hydrographic Feature Digital Data Available No Digital Data Available MAP PANELS Unmapped Ü The pin displayed on the map is an approximate point selected by the user anddoes not represent an authoritative property location. This map complies with FEMA's standards for the use of digital flood maps if it is not void as described below. The basemap shown complies with FEMA's basemap accuracy standards The flood hazard information is derived directly from the authoritative NFHL web services provided by FEMA. This map was exported on 12/9/2019 at 2:06:16 PM and does not reflect changes or amendments subsequent to this date and time. The NFHL and effective information may change or become superseded by new data over time. This map image is void if the one or more of the following map elements do not appear: basemap imagery, flood zone labels, legend, scale bar, map creation date, community identifiers, USGS The National Map: Orthoimagery. Data refreshed April, 2019. FIRM panel number, and FIRM effective date. Map images for 34°59'3.62"N Feet unmapped and unmodernized areas cannot be used for 1:6,000 regulatory purposes. 02505001,0001,5002,000 388953/1113 DSFTTXJOE!XFTMFZ!DIBQFM!.!QIBTF!13 QSF.EFWFMPQNFOU!CBTJOT!NPEFM 388953/1113 DSFTTXJOE!XFTMFZ!DIBQFM!.!QIBTF!13 QPTU.EFWFMPQNFOU!CBTJOT!NPEFM Post-Development 002 - Year Page 1 Project Description File Name ...................................................27842.0002 - Post Development.SPF Project Options Flow Units ...................................................CFS Elevation Type ............................................Elevation Hydrology Method ......................................SCS TR-55 Time of Concentration (TOC) Method ........SCS TR-55 Link Routing Method ...................................Hydrodynamic Enable Overflow Ponding at Nodes ............YES Skip Steady State Analysis Time Periods ..NO Analysis Options Start Analysis On ........................................Dec 03, 202000:00:00 End Analysis On .........................................Dec 04, 202000:00:00 Start Reporting On ......................................Dec 03, 202000:00:00 Antecedent Dry Days ..................................0days Runoff (Dry Weather) Time Step ................0 01:00:00 days hh:mm:ss Runoff (Wet Weather) Time Step ...............0 00:05:00 days hh:mm:ss Reporting Time Step ...................................0 00:05:00 days hh:mm:ss Routing Time Step ......................................15seconds Number of Elements Qty Rain Gages .................................................1 Subbasins....................................................3 Nodes..........................................................5 Junctions ............................................1 Outfalls ...............................................3 Flow Diversions ..................................0 Inlets ..................................................0 Storage Nodes ...................................1 Links............................................................5 Channels ............................................0 Pipes ..................................................1 Pumps ................................................0 Orifices ...............................................2 Weirs ..................................................2 Outlets ................................................0 Pollutants ....................................................0 Land Uses ...................................................0 Rainfall Details SNRain GageDataData SourceRainfallRainStateCountyReturnRainfallRainfall IDSourceIDTypeUnitsPeriodDepthDistribution (years)(inches) 1Time SeriesTS-002IntensityinchesNorth CarolinaUnion23.50SCS Type III 24-hr Post-Development 002 - Year Page 2 Subbasin Summary SNSubbasinAreaPeak RateWeightedTotalTotalTotalPeakTime of IDFactorCurveRainfallRunoffRunoffRunoffConcentration NumberVolume (ac)(in)(in)(ac-in)(cfs)(days hh:mm:ss) 1POST-DEVELOPMENT-BASIN-SUB-01B44.990.0085.923.502.0994.1297.52 0 00:05:00 2UNDISTURBED-BASIN-SUB-01A23.790.0079.003.501.5737.2523.79 0 00:33:05 3UNDISTURBED-BASIN-SUB-0213.140.0070.543.501.0413.648.32 0 00:31:48 Post-Development 002 - Year Page 3 Node Summary SNElementElementInvertGround/RimInitialSurchargePondedPeakMax HGLMaxMinTime ofTotalTotal Time IDTypeElevation(Max)WaterElevationAreaInflowElevationSurchargeFreeboardPeakFloodedFlooded ElevationElevationAttainedDepthAttainedFloodingVolume AttainedOccurrence (ft)(ft)(ft)(ft)(ft²)(cfs)(ft)(ft)(ft)(days hh:mm)(ac-in)(min) 1Jun-03Junction561.00570.200.000.001.0018.17562.170.008.030 00:000.000.00 2EMERG-Out-01Outfall540.000.00540.00 3Out-01Outfall540.0040.76540.00 4Out-02Outfall556.008.32556.00 5Pond-03Storage Node561.00571.00565.001.0095.93568.030.000.00 Post-Development 002 - Year Page 4 Link Summary SNElementElementFromTo (Outlet)LengthInletOutletAverageDiameter orManning'sPeakDesign FlowPeak Flow/Peak FlowPeak FlowPeak FlowTotal TimeReported IDType(Inlet)NodeInvertInvertSlopeHeightRoughnessFlowCapacityDesign FlowVelocityDepthDepth/SurchargedCondition NodeElevationElevationRatioTotal Depth Ratio (ft)(ft)(ft)(%)(in)(cfs)(cfs)(ft/sec)(ft)(min) 1Outlet-Pipe-03PipeJun-03Out-0175.00561.00560.001.330042.0000.013018.17116.170.167.431.050.300.00Calculated 2CS-Rim-03OrificePond-03Jun-03561.00561.0060.0000.00 3WQ-Orifice-03OrificePond-03Jun-03561.00561.005.0001.13 4Spillway-03WeirPond-03EMERG-Out-01561.00540.000.00 5Weir-03AWeirPond-03Jun-03561.00561.0017.04 Post-Development 002 - Year Page 5 Subbasin Hydrology Subbasin : POST-DEVELOPMENT-BASIN-SUB-01B Input Data Area (ac) ........................................................................44.99 Peak Rate Factor ..........................................................0.00 Weighted Curve Number ...............................................85.92 Rain Gage ID .................................................................Rain Gage-001 Composite Curve Number AreaSoilCurve Soil/Surface Description(acres)GroupNumber Paved parking & roofs13.67B98.00 > 75% grass cover, Good14.69B61.00 Future-Paved parking & roofs16.63B98.00 Composite Area & Weighted CN44.9985.92 Time of Concentration TOC Method : SCS TR-55 Sheet Flow Equation : Tc = (0.007 * ((n * Lf)^0.8)) / ((P^0.5) * (Sf^0.4)) Where : Tc = Time of Concentration (hr) n = Manning's roughness Lf = Flow Length (ft) P = 2 yr, 24 hr Rainfall (inches) Sf = Slope (ft/ft) Shallow Concentrated Flow Equation : V = 16.1345 * (Sf^0.5) (unpaved surface) V = 20.3282 * (Sf^0.5) (paved surface) V = 15.0 * (Sf^0.5) (grassed waterway surface) V = 10.0 * (Sf^0.5) (nearly bare & untilled surface) V = 9.0 * (Sf^0.5) (cultivated straight rows surface) V = 7.0 * (Sf^0.5) (short grass pasture surface) V = 5.0 * (Sf^0.5) (woodland surface) V = 2.5 * (Sf^0.5) (forest w/heavy litter surface) Tc = (Lf / V) / (3600 sec/hr) Where: Tc = Time of Concentration (hr) Lf = Flow Length (ft) V = Velocity (ft/sec) Sf = Slope (ft/ft) Channel Flow Equation : V = (1.49 * (R^(2/3)) * (Sf^0.5)) / n R = Aq / Wp Tc = (Lf / V) / (3600 sec/hr) Where : Tc = Time of Concentration (hr) Lf = Flow Length (ft) R = Hydraulic Radius (ft) Aq = Flow Area (ft²) Wp = Wetted Perimeter (ft) V = Velocity (ft/sec) Sf = Slope (ft/ft) n = Manning's roughness User-Defined TOC override (minutes): 5.00 Subbasin Runoff Results Total Rainfall (in) ...........................................................3.50 Total Runoff (in) .............................................................2.09 Peak Runoff (cfs) ...........................................................97.52 Weighted Curve Number ...............................................85.92 Time of Concentration (days hh:mm:ss) ........................0 00:05:00 Post-Development 002 - Year Page 6 Subbasin : POST-DEVELOPMENT-BASIN-SUB-01B Post-Development 002 - Year Page 7 Subbasin : UNDISTURBED-BASIN-SUB-01A Input Data Area (ac) ........................................................................23.79 Peak Rate Factor ..........................................................0.00 Weighted Curve Number ...............................................79.00 Rain Gage ID .................................................................Rain Gage-001 Composite Curve Number AreaSoilCurve Soil/Surface Description(acres)GroupNumber Woods, Fair23.79D79.00 Composite Area & Weighted CN23.7979.00 Time of Concentration FlowpathFlowpathFlowpath Sheet Flow ComputationsABC Manning's Roughness :.40.000.00 Flow Length (ft) :1000.000.00 Slope (%) :2.730.000.00 2 yr, 24 hr Rainfall (in) :3.500.000.00 Velocity (ft/sec) :0.090.000.00 Computed Flow Time (min) :18.130.000.00 FlowpathFlowpathFlowpath Shallow Concentrated Flow ComputationsABC Flow Length (ft) :7900.000.00 Slope (%) :.30.000.00 Surface Type :UnpavedUnpavedUnpaved Velocity (ft/sec) :0.880.000.00 Computed Flow Time (min) :14.960.000.00 Total TOC (min) ..................33.09 Subbasin Runoff Results Total Rainfall (in) ...........................................................3.50 Total Runoff (in) .............................................................1.57 Peak Runoff (cfs) ...........................................................23.79 Weighted Curve Number ...............................................79.00 Time of Concentration (days hh:mm:ss) ........................0 00:33:05 Post-Development 002 - Year Page 8 Subbasin : UNDISTURBED-BASIN-SUB-01A Post-Development 002 - Year Page 9 Subbasin : UNDISTURBED-BASIN-SUB-02 Input Data Area (ac) ........................................................................13.14 Peak Rate Factor ..........................................................0.00 Weighted Curve Number ...............................................70.54 Rain Gage ID .................................................................Rain Gage-001 Composite Curve Number AreaSoilCurve Soil/Surface Description(acres)GroupNumber Pasture, grassland, or range, Good3.13B61.00 -9.65-74.00 -0.37-61.00 Composite Area & Weighted CN13.1570.54 Time of Concentration FlowpathFlowpathFlowpath Sheet Flow ComputationsABC Manning's Roughness :.40.000.00 Flow Length (ft) :1000.000.00 Slope (%) :.670.000.00 2 yr, 24 hr Rainfall (in) :3.500.000.00 Velocity (ft/sec) :0.050.000.00 Computed Flow Time (min) :31.800.000.00 Total TOC (min) ..................31.80 Subbasin Runoff Results Total Rainfall (in) ...........................................................3.50 Total Runoff (in) .............................................................1.04 Peak Runoff (cfs) ...........................................................8.32 Weighted Curve Number ...............................................70.54 Time of Concentration (days hh:mm:ss) ........................0 00:31:48 Post-Development 002 - Year Page 10 Subbasin : UNDISTURBED-BASIN-SUB-02 Post-Development 002 - Year Page 11 Pipe Input SNElementLengthInletInletOutletOutletTotalAveragePipePipePipeManning'sEntranceExit/BendAdditionalInitialFlapNo. of IDInvertInvertInvertInvertDropSlopeShapeDiameter orWidthRoughnessLossesLossesLossesFlowGateBarrels ElevationOffsetElevationOffsetHeight (ft)(ft)(ft)(ft)(ft)(ft)(%)(in)(in)(cfs) 1Outlet-Pipe-0375.00561.000.00560.0020.001.001.3300CIRCULAR42.00042.0000.01300.50000.50000.00000.00No1 Post-Development 002 - Year Page 12 Pipe Results SNElementPeakTime ofDesign FlowPeak Flow/Peak FlowTravelPeak FlowPeak FlowTotal TimeFroudeReported IDFlowPeak FlowCapacityDesign FlowVelocityTimeDepthDepth/SurchargedNumberCondition OccurrenceRatioTotal Depth Ratio (cfs)(days hh:mm)(cfs)(ft/sec)(min)(ft)(min) 1Outlet-Pipe-0318.170 12:38116.170.167.430.171.050.300.00Calculated Post-Development 002 - Year Page 13 Storage Nodes Storage Node : Pond-03 Input Data Invert Elevation (ft) ....................................................................561.00 Max (Rim) Elevation (ft) ............................................................571.00 Max (Rim) Offset (ft) .................................................................10.00 Initial Water Elevation (ft) .........................................................565.00 Initial Water Depth (ft) ...............................................................4.00 Ponded Area (ft²) ......................................................................1.00 Evaporation Loss ......................................................................0.00 Outflow Weirs SNElementWeirFlapCrestCrestLengthWeir TotalDischarge IDTypeGateElevationOffsetHeightCoefficient (ft)(ft)(ft)(ft) 1Spillway-03TrapezoidalNo570.509.5050.000.503.33 2Weir-03ARectangularNo566.805.804.003.403.33 Outflow Orifices SNElementOrificeOrificeFlapCircularRectangularRectangularOrificeOrifice IDTypeShapeGateOrificeOrificeOrificeInvertCoefficient DiameterHeightWidthElevation (in)(in)(in)(ft) 1CS-Rim-03BottomRectangularNo60.0060.00570.200.63 2WQ-Orifice-03SideCIRCULARNo5.00565.000.61 Output Summary Results Peak Inflow (cfs) .......................................................................95.93 Peak Lateral Inflow (cfs) ...........................................................95.93 Peak Outflow (cfs) ....................................................................18.17 Peak Exfiltration Flow Rate (cfm) .............................................0.00 Max HGL Elevation Attained (ft) ...............................................568.03 Max HGL Depth Attained (ft) .....................................................7.03 Average HGL Elevation Attained (ft) .........................................566.51 Average HGL Depth Attained (ft) ..............................................5.51 Time of Max HGL Occurrence (days hh:mm) ...........................0 12:38 Total Exfiltration Volume (1000-ft³) ...........................................0.000 Total Flooded Volume (ac-in) ...................................................0 Total Time Flooded (min) .........................................................0 Total Retention Time (sec) .......................................................0.00 Post-Development 010 - Year Page 1 Project Description File Name ...................................................27842.0002 - Post Development.SPF Project Options Flow Units ...................................................CFS Elevation Type ............................................Elevation Hydrology Method ......................................SCS TR-55 Time of Concentration (TOC) Method ........SCS TR-55 Link Routing Method ...................................Hydrodynamic Enable Overflow Ponding at Nodes ............YES Skip Steady State Analysis Time Periods ..NO Analysis Options Start Analysis On ........................................Dec 03, 202000:00:00 End Analysis On .........................................Dec 04, 202000:00:00 Start Reporting On ......................................Dec 03, 202000:00:00 Antecedent Dry Days ..................................0days Runoff (Dry Weather) Time Step ................0 01:00:00 days hh:mm:ss Runoff (Wet Weather) Time Step ...............0 00:05:00 days hh:mm:ss Reporting Time Step ...................................0 00:05:00 days hh:mm:ss Routing Time Step ......................................15seconds Number of Elements Qty Rain Gages .................................................1 Subbasins....................................................3 Nodes..........................................................5 Junctions ............................................1 Outfalls ...............................................3 Flow Diversions ..................................0 Inlets ..................................................0 Storage Nodes ...................................1 Links............................................................5 Channels ............................................0 Pipes ..................................................1 Pumps ................................................0 Orifices ...............................................2 Weirs ..................................................2 Outlets ................................................0 Pollutants ....................................................0 Land Uses ...................................................0 Rainfall Details SNRain GageDataData SourceRainfallRainStateCountyReturnRainfallRainfall IDSourceIDTypeUnitsPeriodDepthDistribution (years)(inches) 1Time SeriesTS-010IntensityinchesNorth CarolinaUnion105.20SCS Type III 24-hr Post-Development 010 - Year Page 2 Subbasin Summary SNSubbasinAreaPeak RateWeightedTotalTotalTotalPeakTime of IDFactorCurveRainfallRunoffRunoffRunoffConcentration NumberVolume (ac)(in)(in)(ac-in)(cfs)(days hh:mm:ss) 1POST-DEVELOPMENT-BASIN-SUB-01B44.990.0085.925.203.65164.03165.63 0 00:05:00 2UNDISTURBED-BASIN-SUB-01A23.790.0079.005.202.9870.7745.60 0 00:33:05 3UNDISTURBED-BASIN-SUB-0213.140.0070.545.202.2329.3018.97 0 00:31:48 Post-Development 010 - Year Page 3 Node Summary SNElementElementInvertGround/RimInitialSurchargePondedPeakMax HGLMaxMinTime ofTotalTotal Time IDTypeElevation(Max)WaterElevationAreaInflowElevationSurchargeFreeboardPeakFloodedFlooded ElevationElevationAttainedDepthAttainedFloodingVolume AttainedOccurrence (ft)(ft)(ft)(ft)(ft²)(cfs)(ft)(ft)(ft)(days hh:mm)(ac-in)(min) 1Jun-03Junction561.00570.200.000.001.0052.95563.290.006.910 00:000.000.00 2EMERG-Out-01Outfall540.000.00540.00 3Out-01Outfall540.0098.29540.00 4Out-02Outfall556.0018.86556.00 5Pond-03Storage Node561.00571.00565.001.00163.92569.520.000.00 Post-Development 010 - Year Page 4 Link Summary SNElementElementFromTo (Outlet)LengthInletOutletAverageDiameter orManning'sPeakDesign FlowPeak Flow/Peak FlowPeak FlowPeak FlowTotal TimeReported IDType(Inlet)NodeInvertInvertSlopeHeightRoughnessFlowCapacityDesign FlowVelocityDepthDepth/SurchargedCondition NodeElevationElevationRatioTotal Depth Ratio (ft)(ft)(ft)(%)(in)(cfs)(cfs)(ft/sec)(ft)(min) 1Outlet-Pipe-03PipeJun-03Out-0175.00561.00560.001.330042.0000.013052.95116.170.469.451.980.560.00Calculated 2CS-Rim-03OrificePond-03Jun-03561.00561.0060.0000.00 3WQ-Orifice-03OrificePond-03Jun-03561.00561.005.0001.39 4Spillway-03WeirPond-03EMERG-Out-01561.00540.000.00 5Weir-03AWeirPond-03Jun-03561.00561.0051.56 Post-Development 010 - Year Page 5 Subbasin Hydrology Subbasin : POST-DEVELOPMENT-BASIN-SUB-01B Input Data Area (ac) ........................................................................44.99 Peak Rate Factor ..........................................................0.00 Weighted Curve Number ...............................................85.92 Rain Gage ID .................................................................Rain Gage-001 Composite Curve Number AreaSoilCurve Soil/Surface Description(acres)GroupNumber Paved parking & roofs13.67B98.00 > 75% grass cover, Good14.69B61.00 Future-Paved parking & roofs16.63B98.00 Composite Area & Weighted CN44.9985.92 Time of Concentration TOC Method : SCS TR-55 Sheet Flow Equation : Tc = (0.007 * ((n * Lf)^0.8)) / ((P^0.5) * (Sf^0.4)) Where : Tc = Time of Concentration (hr) n = Manning's roughness Lf = Flow Length (ft) P = 2 yr, 24 hr Rainfall (inches) Sf = Slope (ft/ft) Shallow Concentrated Flow Equation : V = 16.1345 * (Sf^0.5) (unpaved surface) V = 20.3282 * (Sf^0.5) (paved surface) V = 15.0 * (Sf^0.5) (grassed waterway surface) V = 10.0 * (Sf^0.5) (nearly bare & untilled surface) V = 9.0 * (Sf^0.5) (cultivated straight rows surface) V = 7.0 * (Sf^0.5) (short grass pasture surface) V = 5.0 * (Sf^0.5) (woodland surface) V = 2.5 * (Sf^0.5) (forest w/heavy litter surface) Tc = (Lf / V) / (3600 sec/hr) Where: Tc = Time of Concentration (hr) Lf = Flow Length (ft) V = Velocity (ft/sec) Sf = Slope (ft/ft) Channel Flow Equation : V = (1.49 * (R^(2/3)) * (Sf^0.5)) / n R = Aq / Wp Tc = (Lf / V) / (3600 sec/hr) Where : Tc = Time of Concentration (hr) Lf = Flow Length (ft) R = Hydraulic Radius (ft) Aq = Flow Area (ft²) Wp = Wetted Perimeter (ft) V = Velocity (ft/sec) Sf = Slope (ft/ft) n = Manning's roughness User-Defined TOC override (minutes): 5.00 Subbasin Runoff Results Total Rainfall (in) ...........................................................5.20 Total Runoff (in) .............................................................3.65 Peak Runoff (cfs) ...........................................................165.63 Weighted Curve Number ...............................................85.92 Time of Concentration (days hh:mm:ss) ........................0 00:05:00 Post-Development 010 - Year Page 6 Subbasin : POST-DEVELOPMENT-BASIN-SUB-01B Post-Development 010 - Year Page 7 Subbasin : UNDISTURBED-BASIN-SUB-01A Input Data Area (ac) ........................................................................23.79 Peak Rate Factor ..........................................................0.00 Weighted Curve Number ...............................................79.00 Rain Gage ID .................................................................Rain Gage-001 Composite Curve Number AreaSoilCurve Soil/Surface Description(acres)GroupNumber Woods, Fair23.79D79.00 Composite Area & Weighted CN23.7979.00 Time of Concentration FlowpathFlowpathFlowpath Sheet Flow ComputationsABC Manning's Roughness :.40.000.00 Flow Length (ft) :1000.000.00 Slope (%) :2.730.000.00 2 yr, 24 hr Rainfall (in) :3.500.000.00 Velocity (ft/sec) :0.090.000.00 Computed Flow Time (min) :18.130.000.00 FlowpathFlowpathFlowpath Shallow Concentrated Flow ComputationsABC Flow Length (ft) :7900.000.00 Slope (%) :.30.000.00 Surface Type :UnpavedUnpavedUnpaved Velocity (ft/sec) :0.880.000.00 Computed Flow Time (min) :14.960.000.00 Total TOC (min) ..................33.09 Subbasin Runoff Results Total Rainfall (in) ...........................................................5.20 Total Runoff (in) .............................................................2.98 Peak Runoff (cfs) ...........................................................45.60 Weighted Curve Number ...............................................79.00 Time of Concentration (days hh:mm:ss) ........................0 00:33:05 Post-Development 010 - Year Page 8 Subbasin : UNDISTURBED-BASIN-SUB-01A Post-Development 010 - Year Page 9 Subbasin : UNDISTURBED-BASIN-SUB-02 Input Data Area (ac) ........................................................................13.14 Peak Rate Factor ..........................................................0.00 Weighted Curve Number ...............................................70.54 Rain Gage ID .................................................................Rain Gage-001 Composite Curve Number AreaSoilCurve Soil/Surface Description(acres)GroupNumber Pasture, grassland, or range, Good3.13B61.00 -9.65-74.00 -0.37-61.00 Composite Area & Weighted CN13.1570.54 Time of Concentration FlowpathFlowpathFlowpath Sheet Flow ComputationsABC Manning's Roughness :.40.000.00 Flow Length (ft) :1000.000.00 Slope (%) :.670.000.00 2 yr, 24 hr Rainfall (in) :3.500.000.00 Velocity (ft/sec) :0.050.000.00 Computed Flow Time (min) :31.800.000.00 Total TOC (min) ..................31.80 Subbasin Runoff Results Total Rainfall (in) ...........................................................5.20 Total Runoff (in) .............................................................2.23 Peak Runoff (cfs) ...........................................................18.97 Weighted Curve Number ...............................................70.54 Time of Concentration (days hh:mm:ss) ........................0 00:31:48 Post-Development 010 - Year Page 10 Subbasin : UNDISTURBED-BASIN-SUB-02 Post-Development 010 - Year Page 11 Pipe Input SNElementLengthInletInletOutletOutletTotalAveragePipePipePipeManning'sEntranceExit/BendAdditionalInitialFlapNo. of IDInvertInvertInvertInvertDropSlopeShapeDiameter orWidthRoughnessLossesLossesLossesFlowGateBarrels ElevationOffsetElevationOffsetHeight (ft)(ft)(ft)(ft)(ft)(ft)(%)(in)(in)(cfs) 1Outlet-Pipe-0375.00561.000.00560.0020.001.001.3300CIRCULAR42.00042.0000.01300.50000.50000.00000.00No1 Post-Development 010 - Year Page 12 Pipe Results SNElementPeakTime ofDesign FlowPeak Flow/Peak FlowTravelPeak FlowPeak FlowTotal TimeFroudeReported IDFlowPeak FlowCapacityDesign FlowVelocityTimeDepthDepth/SurchargedNumberCondition OccurrenceRatioTotal Depth Ratio (cfs)(days hh:mm)(cfs)(ft/sec)(min)(ft)(min) 1Outlet-Pipe-0352.950 12:30116.170.469.450.131.980.560.00Calculated Post-Development 010 - Year Page 13 Storage Nodes Storage Node : Pond-03 Input Data Invert Elevation (ft) ....................................................................561.00 Max (Rim) Elevation (ft) ............................................................571.00 Max (Rim) Offset (ft) .................................................................10.00 Initial Water Elevation (ft) .........................................................565.00 Initial Water Depth (ft) ...............................................................4.00 Ponded Area (ft²) ......................................................................1.00 Evaporation Loss ......................................................................0.00 Outflow Weirs SNElementWeirFlapCrestCrestLengthWeir TotalDischarge IDTypeGateElevationOffsetHeightCoefficient (ft)(ft)(ft)(ft) 1Spillway-03TrapezoidalNo570.509.5050.000.503.33 2Weir-03ARectangularNo566.805.804.003.403.33 Outflow Orifices SNElementOrificeOrificeFlapCircularRectangularRectangularOrificeOrifice IDTypeShapeGateOrificeOrificeOrificeInvertCoefficient DiameterHeightWidthElevation (in)(in)(in)(ft) 1CS-Rim-03BottomRectangularNo60.0060.00570.200.63 2WQ-Orifice-03SideCIRCULARNo5.00565.000.61 Output Summary Results Peak Inflow (cfs) .......................................................................163.92 Peak Lateral Inflow (cfs) ...........................................................163.92 Peak Outflow (cfs) ....................................................................52.95 Peak Exfiltration Flow Rate (cfm) .............................................0.00 Max HGL Elevation Attained (ft) ...............................................569.52 Max HGL Depth Attained (ft) .....................................................8.52 Average HGL Elevation Attained (ft) .........................................567.02 Average HGL Depth Attained (ft) ..............................................6.02 Time of Max HGL Occurrence (days hh:mm) ...........................0 12:30 Total Exfiltration Volume (1000-ft³) ...........................................0.000 Total Flooded Volume (ac-in) ...................................................0 Total Time Flooded (min) .........................................................0 Total Retention Time (sec) .......................................................0.00 Post-Development 025 - Year Page 1 Project Description File Name ...................................................27842.0002 - Post Development.SPF Project Options Flow Units ...................................................CFS Elevation Type ............................................Elevation Hydrology Method ......................................SCS TR-55 Time of Concentration (TOC) Method ........SCS TR-55 Link Routing Method ...................................Hydrodynamic Enable Overflow Ponding at Nodes ............YES Skip Steady State Analysis Time Periods ..NO Analysis Options Start Analysis On ........................................Dec 03, 202000:00:00 End Analysis On .........................................Dec 04, 202000:00:00 Start Reporting On ......................................Dec 03, 202000:00:00 Antecedent Dry Days ..................................0days Runoff (Dry Weather) Time Step ................0 01:00:00 days hh:mm:ss Runoff (Wet Weather) Time Step ...............0 00:05:00 days hh:mm:ss Reporting Time Step ...................................0 00:05:00 days hh:mm:ss Routing Time Step ......................................15seconds Number of Elements Qty Rain Gages .................................................1 Subbasins....................................................3 Nodes..........................................................5 Junctions ............................................1 Outfalls ...............................................3 Flow Diversions ..................................0 Inlets ..................................................0 Storage Nodes ...................................1 Links............................................................5 Channels ............................................0 Pipes ..................................................1 Pumps ................................................0 Orifices ...............................................2 Weirs ..................................................2 Outlets ................................................0 Pollutants ....................................................0 Land Uses ...................................................0 Rainfall Details SNRain GageDataData SourceRainfallRainStateCountyReturnRainfallRainfall IDSourceIDTypeUnitsPeriodDepthDistribution (years)(inches) 1Time SeriesTS-025IntensityinchesNorth CarolinaUnion256.10SCS Type III 24-hr Post-Development 025 - Year Page 2 Subbasin Summary SNSubbasinAreaPeak RateWeightedTotalTotalTotalPeakTime of IDFactorCurveRainfallRunoffRunoffRunoffConcentration NumberVolume (ac)(in)(in)(ac-in)(cfs)(days hh:mm:ss) 1POST-DEVELOPMENT-BASIN-SUB-01B44.990.0085.926.104.50202.28201.62 0 00:05:00 2UNDISTURBED-BASIN-SUB-01A23.790.0079.006.103.7789.6557.78 0 00:33:05 3UNDISTURBED-BASIN-SUB-0213.140.0070.546.102.9438.5825.21 0 00:31:48 Post-Development 025 - Year Page 3 Node Summary SNElementElementInvertGround/RimInitialSurchargePondedPeakMax HGLMaxMinTime ofTotalTotal Time IDTypeElevation(Max)WaterElevationAreaInflowElevationSurchargeFreeboardPeakFloodedFlooded ElevationElevationAttainedDepthAttainedFloodingVolume AttainedOccurrence (ft)(ft)(ft)(ft)(ft²)(cfs)(ft)(ft)(ft)(days hh:mm)(ac-in)(min) 1Jun-03Junction561.00570.200.000.001.0071.35563.840.006.360 00:000.000.00 2EMERG-Out-01Outfall540.000.00540.00 3Out-01Outfall540.00128.50540.00 4Out-02Outfall556.0024.97556.00 5Pond-03Storage Node561.00571.00565.001.00199.97570.220.000.00 Post-Development 025 - Year Page 4 Link Summary SNElementElementFromTo (Outlet)LengthInletOutletAverageDiameter orManning'sPeakDesign FlowPeak Flow/Peak FlowPeak FlowPeak FlowTotal TimeReported IDType(Inlet)NodeInvertInvertSlopeHeightRoughnessFlowCapacityDesign FlowVelocityDepthDepth/SurchargedCondition NodeElevationElevationRatioTotal Depth Ratio (ft)(ft)(ft)(%)(in)(cfs)(cfs)(ft/sec)(ft)(min) 1Outlet-Pipe-03PipeJun-03Out-0175.00561.00560.001.330042.0000.013071.35116.170.6110.092.410.690.00Calculated 2CS-Rim-03OrificePond-03Jun-03561.00561.0060.0000.16 3WQ-Orifice-03OrificePond-03Jun-03561.00561.005.0001.50 4Spillway-03WeirPond-03EMERG-Out-01561.00540.000.00 5Weir-03AWeirPond-03Jun-03561.00561.0069.68 Post-Development 025 - Year Page 5 Subbasin Hydrology Subbasin : POST-DEVELOPMENT-BASIN-SUB-01B Input Data Area (ac) ........................................................................44.99 Peak Rate Factor ..........................................................0.00 Weighted Curve Number ...............................................85.92 Rain Gage ID .................................................................Rain Gage-001 Composite Curve Number AreaSoilCurve Soil/Surface Description(acres)GroupNumber Paved parking & roofs13.67B98.00 > 75% grass cover, Good14.69B61.00 Future-Paved parking & roofs16.63B98.00 Composite Area & Weighted CN44.9985.92 Time of Concentration TOC Method : SCS TR-55 Sheet Flow Equation : Tc = (0.007 * ((n * Lf)^0.8)) / ((P^0.5) * (Sf^0.4)) Where : Tc = Time of Concentration (hr) n = Manning's roughness Lf = Flow Length (ft) P = 2 yr, 24 hr Rainfall (inches) Sf = Slope (ft/ft) Shallow Concentrated Flow Equation : V = 16.1345 * (Sf^0.5) (unpaved surface) V = 20.3282 * (Sf^0.5) (paved surface) V = 15.0 * (Sf^0.5) (grassed waterway surface) V = 10.0 * (Sf^0.5) (nearly bare & untilled surface) V = 9.0 * (Sf^0.5) (cultivated straight rows surface) V = 7.0 * (Sf^0.5) (short grass pasture surface) V = 5.0 * (Sf^0.5) (woodland surface) V = 2.5 * (Sf^0.5) (forest w/heavy litter surface) Tc = (Lf / V) / (3600 sec/hr) Where: Tc = Time of Concentration (hr) Lf = Flow Length (ft) V = Velocity (ft/sec) Sf = Slope (ft/ft) Channel Flow Equation : V = (1.49 * (R^(2/3)) * (Sf^0.5)) / n R = Aq / Wp Tc = (Lf / V) / (3600 sec/hr) Where : Tc = Time of Concentration (hr) Lf = Flow Length (ft) R = Hydraulic Radius (ft) Aq = Flow Area (ft²) Wp = Wetted Perimeter (ft) V = Velocity (ft/sec) Sf = Slope (ft/ft) n = Manning's roughness User-Defined TOC override (minutes): 5.00 Subbasin Runoff Results Total Rainfall (in) ...........................................................6.10 Total Runoff (in) .............................................................4.50 Peak Runoff (cfs) ...........................................................201.62 Weighted Curve Number ...............................................85.92 Time of Concentration (days hh:mm:ss) ........................0 00:05:00 Post-Development 025 - Year Page 6 Subbasin : POST-DEVELOPMENT-BASIN-SUB-01B Post-Development 025 - Year Page 7 Subbasin : UNDISTURBED-BASIN-SUB-01A Input Data Area (ac) ........................................................................23.79 Peak Rate Factor ..........................................................0.00 Weighted Curve Number ...............................................79.00 Rain Gage ID .................................................................Rain Gage-001 Composite Curve Number AreaSoilCurve Soil/Surface Description(acres)GroupNumber Woods, Fair23.79D79.00 Composite Area & Weighted CN23.7979.00 Time of Concentration FlowpathFlowpathFlowpath Sheet Flow ComputationsABC Manning's Roughness :.40.000.00 Flow Length (ft) :1000.000.00 Slope (%) :2.730.000.00 2 yr, 24 hr Rainfall (in) :3.500.000.00 Velocity (ft/sec) :0.090.000.00 Computed Flow Time (min) :18.130.000.00 FlowpathFlowpathFlowpath Shallow Concentrated Flow ComputationsABC Flow Length (ft) :7900.000.00 Slope (%) :.30.000.00 Surface Type :UnpavedUnpavedUnpaved Velocity (ft/sec) :0.880.000.00 Computed Flow Time (min) :14.960.000.00 Total TOC (min) ..................33.09 Subbasin Runoff Results Total Rainfall (in) ...........................................................6.10 Total Runoff (in) .............................................................3.77 Peak Runoff (cfs) ...........................................................57.78 Weighted Curve Number ...............................................79.00 Time of Concentration (days hh:mm:ss) ........................0 00:33:05 Post-Development 025 - Year Page 8 Subbasin : UNDISTURBED-BASIN-SUB-01A Post-Development 025 - Year Page 9 Subbasin : UNDISTURBED-BASIN-SUB-02 Input Data Area (ac) ........................................................................13.14 Peak Rate Factor ..........................................................0.00 Weighted Curve Number ...............................................70.54 Rain Gage ID .................................................................Rain Gage-001 Composite Curve Number AreaSoilCurve Soil/Surface Description(acres)GroupNumber Pasture, grassland, or range, Good3.13B61.00 -9.65-74.00 -0.37-61.00 Composite Area & Weighted CN13.1570.54 Time of Concentration FlowpathFlowpathFlowpath Sheet Flow ComputationsABC Manning's Roughness :.40.000.00 Flow Length (ft) :1000.000.00 Slope (%) :.670.000.00 2 yr, 24 hr Rainfall (in) :3.500.000.00 Velocity (ft/sec) :0.050.000.00 Computed Flow Time (min) :31.800.000.00 Total TOC (min) ..................31.80 Subbasin Runoff Results Total Rainfall (in) ...........................................................6.10 Total Runoff (in) .............................................................2.94 Peak Runoff (cfs) ...........................................................25.21 Weighted Curve Number ...............................................70.54 Time of Concentration (days hh:mm:ss) ........................0 00:31:48 Post-Development 025 - Year Page 10 Subbasin : UNDISTURBED-BASIN-SUB-02 Post-Development 025 - Year Page 11 Pipe Input SNElementLengthInletInletOutletOutletTotalAveragePipePipePipeManning'sEntranceExit/BendAdditionalInitialFlapNo. of IDInvertInvertInvertInvertDropSlopeShapeDiameter orWidthRoughnessLossesLossesLossesFlowGateBarrels ElevationOffsetElevationOffsetHeight (ft)(ft)(ft)(ft)(ft)(ft)(%)(in)(in)(cfs) 1Outlet-Pipe-0375.00561.000.00560.0020.001.001.3300CIRCULAR42.00042.0000.01300.50000.50000.00000.00No1 Post-Development 025 - Year Page 12 Pipe Results SNElementPeakTime ofDesign FlowPeak Flow/Peak FlowTravelPeak FlowPeak FlowTotal TimeFroudeReported IDFlowPeak FlowCapacityDesign FlowVelocityTimeDepthDepth/SurchargedNumberCondition OccurrenceRatioTotal Depth Ratio (cfs)(days hh:mm)(cfs)(ft/sec)(min)(ft)(min) 1Outlet-Pipe-0371.350 12:28116.170.6110.090.122.410.690.00Calculated Post-Development 025 - Year Page 13 Storage Nodes Storage Node : Pond-03 Input Data Invert Elevation (ft) ....................................................................561.00 Max (Rim) Elevation (ft) ............................................................571.00 Max (Rim) Offset (ft) .................................................................10.00 Initial Water Elevation (ft) .........................................................565.00 Initial Water Depth (ft) ...............................................................4.00 Ponded Area (ft²) ......................................................................1.00 Evaporation Loss ......................................................................0.00 Outflow Weirs SNElementWeirFlapCrestCrestLengthWeir TotalDischarge IDTypeGateElevationOffsetHeightCoefficient (ft)(ft)(ft)(ft) 1Spillway-03TrapezoidalNo570.509.5050.000.503.33 2Weir-03ARectangularNo566.805.804.003.403.33 Outflow Orifices SNElementOrificeOrificeFlapCircularRectangularRectangularOrificeOrifice IDTypeShapeGateOrificeOrificeOrificeInvertCoefficient DiameterHeightWidthElevation (in)(in)(in)(ft) 1CS-Rim-03BottomRectangularNo60.0060.00570.200.63 2WQ-Orifice-03SideCIRCULARNo5.00565.000.61 Output Summary Results Peak Inflow (cfs) .......................................................................199.97 Peak Lateral Inflow (cfs) ...........................................................199.97 Peak Outflow (cfs) ....................................................................71.35 Peak Exfiltration Flow Rate (cfm) .............................................0.00 Max HGL Elevation Attained (ft) ...............................................570.22 Max HGL Depth Attained (ft) .....................................................9.22 Average HGL Elevation Attained (ft) .........................................567.26 Average HGL Depth Attained (ft) ..............................................6.26 Time of Max HGL Occurrence (days hh:mm) ...........................0 12:28 Total Exfiltration Volume (1000-ft³) ...........................................0.000 Total Flooded Volume (ac-in) ...................................................0 Total Time Flooded (min) .........................................................0 Total Retention Time (sec) .......................................................0.00 36.ZS DBQBDJUZ 5!JO0IS JOMFU TQSFBE Water Quality Calculations Cresswind - Wesley Chapel Project No. 27842.002 WET POND 03 Project/Drainage Area:45.00AcresRequired Water Quality Volume:107,158Cubic Feet Impervious Area:30.30Acres(Project Area (Acres) X 43,560 SF X 1"/12 = Required Cubic Feet Volume) 67.3%Percent ImperviousRunoff Coeifficient:Rv= .05+0.9 (I) =0.66 (Required Collection of First 1" of Rainfall from the Project Site and Release over a Minimum 48 Hour (Maximum 120 Hours) in Cubic Feet Per Second) Min. 48-Hour Release Rate:0.620CFSRequired Orifice Size:5.00Drawdown Time (Hours):46.78 Water Quality ElevationOrifice Flow Calculation Elev.AreaStorageQ=CA*sqrt(2gh) d (ft)(sf)(cu. ft)C=0.62(Sharp Orifice) d 565.0048,889.000.00A =0.136sf 2 ft/s 571.0072,688.00364,731.00g =32.174 ElevationPond DepthStorageh =1.76ft (ft)(ft)(cu. ft)Q =0.636cfs 565.000.000.00 566.761.76107,157.60 571.006.00364,731.00 Average Depth Calculation Vpp Designed @ Elevation565.00 132,396.00 SA Designed @ Elevation 565.00 48,889.00 Area of wet pond at the bottom of the shelf 45,439.00 Dmax over shelf 0.50 Perimeter of Permanent Pool 1,160.00 Width of submerged part of shelf 3.00 Volume over the shelf only 870.00 Average Depth 2.89 SA/DA Method Drainage Area45.00acres Table value 2.09 Surface Area Required 40,968.18 square feet Stage Storage Calculations Cresswind - Wesley Chapel Project No. 27842.0002 WET POND 03 FOREBAY 01 VOLUME CONTOUR AREA INC. VOL. AVG. CUM. VOL. AVG. END CONTOUR ELEVDEPTH (FT) (SF)END (CU. FT.)(CU. FT.) 5612,474N/AN/A0 5622,87612,6752,675 5633,30613,0915,766 5643,76713,5369,302 564.54,1280.51,97411,276 5654,6480.52,19413,470 FOREBAY 02 VOLUME CONTOUR AREA INC. VOL. AVG. CUM. VOL. AVG. END CONTOUR ELEVDEPTH (FT) (SF)END (CU. FT.)(CU. FT.) 5612,342N/AN/A0 5622,7391.002,5412,541 5633,6551.002,9525,493 5643,6201.003,3938,886 564.53,9370.501,88910,775 5654,5270.502,11612,891 TOTAL FOREBAY VOLUME:CU. FT. 26,361 PERCENTAGE OF PERMANENT POOL VOLUME: 19.91% PERMANENT POOL VOLUME CONTOUR AREA INC. VOL. AVG. CUM. VOL. AVG. END CONTOUR ELEVDEPTH (FT) (SF)END (CU. FT.)(CU. FT.) 56129,035N/AN/A0 56230,958129,99729,997 56332,924131,94161,938 56434,934133,92995,867 564.536,1620.517,774113,641 56538,8600.518,756132,396 PERMANENT POOL VOLUME:CU.FT 132,396 TEMPORARY PONDING ZONE CONTOUR AREA INC. VOL. AVG. CUM. VOL. AVG. END CONTOUR ELEVDEPTH (FT) (SF)END (CU. FT.)(CU. FT.) 56548,889N/AN/A0 565.552,3960.525321.0025,321 56654,1400.526,63451,955 56757,739155,940107,895 56861,391159,565167,460 56965,091163,241230,701 57068,845166,968297,669 57172,687170,766368,435 TEMPORARY PONDING ZONE VOLUME:CU. FT. 368,435 Cresswind Wesley Chapel - Phase 02Job:J-27842.0002 KH Wesley Chapel, LLCDate:2/18/21 Thomas & Hutton Engineering Co.Revised: Anti-Flotation Design Considerations By:MSK ANTI-FLOTATION DESIGN CONSIDERATIONS FOR: Wet Pond 02 CONTROL STUCTURE ELEVATIONS Top Structure Elevation:570.20 Bottom Structure Elevation:561.00 CONTROL STRUCTURE FLOTATION Buoyant Force Calculate submerged volume: V =(A x H) scscs Where: V = Submerged volume (cf) s L = Length of control structure (ft)=6.00 ft cs W = Width of Control structure (ft)=6.00 ft cs ACross-sectional area of control structure (ft)=36.00 ft cs = H = Height of control structure (ft)=9.20 ft cs Solve equation for V: s V = (A x H)=331.20 cf scscs Calculate buoyant force: F =V bswater Where: F = buoyant force (lbf) b = Specific weight of water=62.40 lbf/cf water F = 20,667lbf b Z:\\27842\\27842.0002\\Engineering\\Calculations and Reports\\Storm Water\\Anti Flotation\\27842.0002 - Wet Pond 03 - Anti Flotation Page 1 of 3 Design Calculations.xlsx Cresswind Wesley Chapel - Phase 02Job:J-27842.0002 KH Wesley Chapel, LLCDate:2/18/21 Thomas & Hutton Engineering Co.Revised: Anti-Flotation Design Considerations By:MSK Downward Force Calculate Downward Force of Control Structure (V- V - V Fd = cs weirorifice cs Where: Wt = Weight of control structure (lbs) cs = Specific weight of concrete=140.00 lbf/cf concrete A = Cross-sectional area of control structure (ft)=36.00 ft cs H = Height of control structure (ft)=9.20 ft cs T = Wall thickness of control structure (ft)=0.50 ft cs V = Volume of control structure (cf)=101.20 cf cs W = Width of weir (ft)=4.00 ft weir H =Height of weir opening (ft)=3.40 ft weir A =Area of weir opening(ft)=13.60 sf weir V =Volume of weir=6.80 cf weir DIA =Diameter of orifice opening (in)=5.00 in orifice A =Area of orifice opening (sf)=0.136 sf orifice V =Volume of orifice opening (sf)=0.068 cf orifice Fd = 13,206lbf cs Size Anti-Flotation Footing to Resist Bouyant Force Fd + Fd> F csft b Fd = (L x W x D ftbbb)concrete Where: Fd = downward force of control structure (lbf)=13206 lbf cs F = buoyant force (lbf)=20667 lbf b = Specific weight of concrete=77.60 lbf/cf concrete L =Length of Concrete Block=12.00 ft b W = Width of Concrete Block=12.00 ft b D =Depth of Concrete Block=12.00 in b Fd = downward force of anti-flotation footing (lbf)=11174 lbf ft Z:\\27842\\27842.0002\\Engineering\\Calculations and Reports\\Storm Water\\Anti Flotation\\27842.0002 - Wet Pond 03 - Anti Flotation Page 2 of 3 Design Calculations.xlsx Cresswind Wesley Chapel - Phase 02Job:J-27842.0002 KH Wesley Chapel, LLCDate:2/18/21 Thomas & Hutton Engineering Co.Revised: Anti-Flotation Design Considerations By:MSK Fd + Fd =lbf > F = 2438120667lbf OK csftb Factor of Safety Confirm anti-flotation block is sized for minimum factor of safety (F) of 1.10. s F=(Fd + Fd)/F scsftb =1.18> 1.10 OK Z:\\27842\\27842.0002\\Engineering\\Calculations and Reports\\Storm Water\\Anti Flotation\\27842.0002 - Wet Pond 03 - Anti Flotation Page 3 of 3 Design Calculations.xlsx