HomeMy WebLinkAboutSDP200900006 Calculations 2004-05-03HYDROLOGIC /HYDRAULIC CALCULATIONS
FOR
HOLLYMEAD TOWNCENTER SWM1
TR -55 Method
November 19, 2003
Rev: November 25, 2003
Rev: December 19, 2003
Rev: May 3, 2004
LOCATION:
Tax Map 36 Parcels 41 D
Albemarle County, Virginia
PREPARED BY:
Rivanna Engineering & Surveying, PLC
P.O. Box 7603
Charlottesville, VA 22906
P: 434.984.1599
F: 434.984.8863
INDEX
Summary:2
Pre - Development:
Flood Hydrographs:3 -6
Combined Hydrographs:7 -8
Post - Development:
Flood Hydrographs:9 -17
Routed Hydrographs:18 -20
Combined Hydrographs:21 -22
Outlet Structures:23 -32
Reservoir:33 -34
Temp. Sediment Basin Conditions:
Routed Hydrographs:35 -37
Reservoir:38 -39
NOTE: DA Slaps are at the end of this report.
Run -off Summary
Point of Pre -Dev Pre -Dev Pre -Dev Post - Post -Dev Post -Dev
Analysis DA 2 -Year 10 -Year Dev 2 -Year 10 -Year
DA
1 B & C 15.38 41.55 Z(Rtd.),6.24 21.3.4
W, X, & Y
HOLLYMEAD TOWN CENTER — SWM1
SUMMARY
Drainage Areas
The point of analysis for Stormwater Management Facility #1 is the outfall of the existing 4'x4' box
culvert that flows to the existing Gateway Pond. The drainage to this point has been defined with two
separate drainage areas. Drainage Area 'B' is the pre - development area that enters into the 4'x4' box
culvert on the west side of Route 29. Drainage Area 'C' is the pre - development area that enters into
the 4'x4' box culvert from a DI -7 drop inlet located in the median of Route 29. Drainage Area 'A' is the
pre - development drainage area that flows to an existing 24" CMP culvert that ultimately flows to Pond A
of the Forest Lakes Subdivision.
The post - development drainage areas for Stormwater Management Facility #1 consist of four individual
drainage areas. Drainage Area 'Z' is the entire post - development drainage area that flows into
SWM #1 which includes the Target and it's adjacent building, Timberwood Blvd. up to it's intersection
with Meeting Street, (Ridge Rd.), and Blocks I, II, VII, VIII, & IX of the proposed development areas for
Virginia Land Co. on the preliminary site plan. Drainage Areas W', 'X', & 'Y' are the uncontained areas
that will flow to the curb inlets on the Route 29 frontage improvements.
Outlet Structure & Routing
The outlet structure for the pond will consist of a 5' diameter standpipe with two culverts. One of the
culverts will be a 18" ductile iron pipe that will continue base flow through the existing 24" CMP to the
Forest Lakes pond. The 18" D.I.P. will have an invert of 511.59. The second culvert will be 36" RCP
with an invert of 516.00 and will flow to the existing 4'x4' box culvert that flows to the Gateway Pond
located between Holly Memorial Gardens and the Gateway Townhouses at Forest Lakes. The
standpipe rim is at an elevation of 525.50 and will have a 4' weir at an elevation of 523.75. In addition
there will be an 8" orifice with an invert elevation of 520.00.
During the 2yr storm event the pond will attain a water surface elevation of 523.16 and the outlet
structure will have a total outflow of 29.87 cfs. Of the total outflow 27.05 cfs will go to the 18" D.I.P.
supplying the flow to the Forest Lakes pond and 2.82 cfs will flow to the 36" RCP pipe resulting in a
combined peak flow of 6.24 cfs going through the 4'x4' box culvert to the Gateway Pond.
During the 10yr storm event the pond will attain a water surface elevation of 524.91 and the outlet
structure will have a total outflow of 48.94 cfs. Of the total outflow 28.66 cfs will go to the 18" D.I.P.
supplying the flow to the Forest Lakes pond and 20.32 cfs will flow to the 36" RCP pipe resulting in a
combined peak flow of 21.34 cfs going through the 4'x4' box culvert to the Gateway Pond.
While construction activities are taking place the pond will serve as a temporary sediment basin.
During the construction phase the 18" DIP pipe that will provide flow to the Forest Lakes pond will be
capped in order to prevent silt from entering the pond. The standpipe will be provided with a 15"
dewatering orifice with an invert elevation of 516.5. The flows shown going to the sediment basin
reflect full build -out conditions. Since the full volume of the pond can be used while the pond is being
used as a sediment basin the flows to the 4'x4' box culvert will be reduced considerably. The flow
calculations and pond volumes are provided in this report. Full build -out conditions were used because
they represent the worst -case scenario for the total volume of flow that will be going to the sediment
basin during construction.
Rivanna Engineering & Surveying, PLC Page 2
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HOLLYMEAD TOWN CENTER - SWM1
FLOOD HYDROGRAPH REPORT
Name:DA -B, 2 year
Type:Computed Flood
HYDROGRAPH INFORMATION]
Peak Flow (Qp)14.37 (cfs)
Time to Peak (Tp)726.00 (min)
Time of Base (Tb)1496.73 (min)
Volume 1.1866 (ac -ft)
Time Step 2.00 (min)
Flow Multiplier 1.00
UNIT HYDROGRAPH INFORMATION]
Type SCS Curvilinear
Peak Flow (Qp)64.13 (cfs)
Time to Peak (Tp)11.67 (min)
Time of Base (Tb)58.33 (min)
Volume 1.3755 (ac -ft)
Shape Factor 484.00
Time Step:2.00 (min)
Excess Rain 1.00 (in)
Lag Time 10.50 (min)
BASIN INFORMATION]
WEIGHTED WATERSHED AREA]
Description Area CN
Overall Approximation 16.4900 62
TIME CONCENTRATION -- User Defined]
Time of Concentration (Tc)17.50 (min)
RAINFALL DESCRIPTION]
Distribution Type SCS II
Total Precipitation 4.00 (in)
Return Period 2 (yr)
Storm Duration 24.00 (hr)
Rivanna Engineering & Surveying, PLC Page 3
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HOLLYMEAD TOWN CENTER - SWM1
FLOOD HYDROGRAPH REPORT
Name:DA -B, 10 year
Type:Computed Flood
HYDROGRAPH INFORMATION]
Peak Flow (Qp)39.73 (cfs)
Time to Peak (Tp)724.00 (min)
Time of Base (Tb)1496.73 (min)
Volume 2.8734 (ac -ft)
Time Step 2.00 (min)
Flow Multiplier 1.00
UNIT HYDROGRAPH INFORMATION]
Type SCS Curvilinear
Peak Flow (Qp)64.13 (cfs)
Time to Peak (Tp)11.67 (min)
Time of Base (Tb)58.33 (min)
Volume 1.3755 (ac -ft)
Shape Factor 484.00
Time Step:2.00 (min)
Excess Rain 1.00 (in)
Lag Time 10.50 (min)
BASIN INFORMATION]
WEIGHTED WATERSHED AREA]
Description Area CN
Overall Approximation 16.4900 62
TIME CONCENTRATION -- User Defined]
Time of Concentration (Tc)17.50 (min)
RAINFALL DESCRIPTION]
Distribution Type SCS II
Total Precipitation 6.00 (in)
Return Period 2 (yr)
Storm Duration 24.00 (hr)
Rivanna Engineering & Surveying, PLC Page 4
434) 984 -1599
HOLLYMEAD TOWN CENTER — SWM1
FLOOD HYDROGRAPH REPORT
Name:DA -C, 2 year
Type:Computed Flood
HYDROGRAPH INFORMATION]
Peak Flow (Qp)2.56 (cfs)
Time to Peak (Tp)718.00 (min)
Time of Base (Tb)1459.59 (min)
Volume 0.1075 (ac -ft)
Time Step 2.00 (min)
Flow Multiplier 1.00
UNIT HYDROGRAPH INFORMATION]
Type SCS Curvilinear
Peak Flow (Qp)8.17 (cfs)
Time to Peak (Tp)4.00 (min)
Time of Base (Tb)20.00 (min)
Volume 0.0597 (ac -ft)
Shape Factor 484.00
Time Step:2.00 (min)
Excess Rain 1.00 (in)
Lag Time 3.60 (min)
BASIN INFORMATION]
WEIGHTED WATERSHED AREA]
Description Area CN
Overall Approximation 0.7200 80
TIME CONCENTRATION -- User Defined]
Time of Concentration (Tc)6.00 (min)
RAINFALL DESCRIPTION]
Distribution Type SCS II
Total Precipitation 4.00 (in)
Return Period 2 (yr)
Storm Duration 24.00 (hr)
Rivanna Engineering & Surveying, PLC Page 5
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HOLLYMEAD TOWN CENTER - SWM1
FLOOD HYDROGRAPH REPORT
Name:DA -C, 10 year
Type:Computed Flood
HYDROGRAPH INFORMATION]
Peak Flow (Qp)4.64 (cfs)
Time to Peak (Tp)718.00 (min)
Time of Base (Tb)1459.59 (min)
Volume 0.2033 (ac -ft)
Time Step 2.00 (min)
Flow Multiplier 1.00
UNIT HYDROGRAPH INFORMATION]
Type SCS Curvilinear
Peak Flow (Qp)8.17 (cfs)
Time to Peak (Tp)4.00 (min)
Time of Base (Tb)20.00 (min)
Volume 0.0597 (ac -ft)
Shape Factor 484.00
Time Step:2.00 (min)
Excess Rain 1.00 (in)
Lag Time 3.60 (min)
BASIN INFORMATION]
WEIGHTED WATERSHED AREA]
Description Area CN
Overall Approximation 0.7200 80
TIME CONCENTRATION -- User Defined]
Time of Concentration (Tc)6.00 (min)
RAINFALL DESCRIPTION]
Distribution Type SCS II
Total Precipitation 6.00 (in)
Return Period 2 (yr)
Storm Duration 24.00 (hr)
Rivanna Engineering & Surveying, PLC Page 6
434) 984 -1599
HOLLYMEAD TOWN CENTER — SWM1
FLOOD HYDROGRAPH REPORT
Name:DA -B & DA -C, 2 year
Type:Combined
HYDROGRAPH INFORMATION]
Peak Flow (Qp)15.38 (cfs)
Time to Peak (Tp)724.00 (min)
Time of Base (Tb)1478.00 (min)
Volume 1.2941 (ac -ft)
Time Step 2.00 (min)
COMBINED HYDROGRAPH RECORDS]
Name:DA -B, 2 year
Type:Computed Flood
Peak Flow (Qp)14.37 (cfs)
Time to Peak (Tp)726.00 (min)
Time Step 2.00 (min)
Name:DA -C, 2 year
Type:Computed Flood
Peak Flow (Qp)2.56 (cfs)
Time to Peak (Tp)718.00 (min)
Time Step 2.00 (min)
Rivanna Engineering & Surveying, PLC Page 7
434) 984 -1599
HOLLYMEAD TOWN CENTER — SWM1
FLOOD HYDROGRAPH REPORT
Name:DA -B & DA -C, 10 year
Type:Combined
HYDROGRAPH INFORMATION]
Peak Flow (Qp)41.55 (cfs)
Time to Peak (Tp)724.00 (min)
Time of Base (Tb)1484.00 (min)
Volume 3.0768 (ac -ft)
Time Step 2.00 (min)
COMBINED HYDROGRAPH RECORDS]
Name:DA -B, 10 year
Type:Computed Flood
Peak Flow (Qp)39.73 (cfs)
Time to Peak (Tp)724.00 (min)
Time Step 2.00 (min)
Name:DA -C, 10 year
Type:Computed Flood
Peak Flow (Qp)4.64 (cfs)
Time to Peak (Tp)718.00 (min)
Time Step 2.00 (min)
Rivanna Engineering & Surveying, PLC Page 8
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HOLLYMEAD TOWN CENTER - SWM1
FLOOD HYDROGRAPH REPORT
Name:DA -W, 2 year
Type:Computed Flood
HYDROGRAPH INFORMATION]
Peak Flow (Qp)3.17 (cfs)
Time to Peak (Tp)716.00 (min)
Time of Base (Tb)1456.39 (min)
Volume 0.1338 (ac -ft)
Time Step 2.00 (min)
Flow Multiplier 1.00
UNIT HYDROGRAPH INFORMATION]
Type SCS Curvilinear
Peak Flow (Qp)8.17 (cfs)
Time to Peak (Tp)3.33 (min)
Time of Base (Tb)16.67 (min)
Volume 0.0498 (ac -ft)
Shape Factor 484.00
Time Step:2.00 (min)
Excess Rain 1.00 (in)
Lag Time 3.00 (min)
BASIN INFORMATION]
WEIGHTED WATERSHED AREA]
Description Area CN
None>
Overall Approximation 0.6000 93
TIME CONCENTRATION -- User Defined]
Time of Concentration (Tc)5.00 (min)
RAINFALL DESCRIPTION]
Distribution Type SCS II
Total Precipitation 4.00 (in)
Return Period 2 (yr)
Storm Duration 24.00 (hr)
Rivanna Engineering & Surveying, PLC Page 9
434) 984 -1599
HOLLYMEAD TOWN CENTER — SWM1
FLOOD HYDROGRAPH REPORT
Name:DA -W, 10 year
Type:Computed Flood
HYDROGRAPH INFORMATION]
Peak Flow (Qp)4.96 (cfs)
Time to Peak (Tp)716.00 (min)
Time of Base (Tb)1456.39 (min)
Volume 0.2191 (ac -ft)
Time Step 2.00 (min)
Flow Multiplier 1.00
UNIT HYDROGRAPH INFORMATION]
Type SCS Curvilinear
Peak Flow (Qp)8.17 (cfs)
Time to Peak (Tp)3.33 (min)
Time of Base (Tb)16.67 (min)
Volume 0.0498 (ac -ft)
Shape Factor 484.00
Time Step:2.00 (min)
Excess Rain 1.00 (in)
Lag Time 3.00 (min)
BASIN INFORMATION]
WEIGHTED WATERSHED AREA]
Description Area CN
None>
Overall Approximation 0.6000 93
TIME CONCENTRATION -- User Defined]
Time of Concentration (Tc)5.00 (min)
RAINFALL DESCRIPTION]
Distribution Type SCS II
Total Precipitation 6.00 (in)
Return Period 2 (yr)
Storm Duration 24.00 (hr)
Rivanna Engineering & Surveying, PLC Page 10
434) 984 -1599
HOLLYMEAD TOWN CENTER - SWM1
FLOOD HYDROGRAPH REPORT
Name:DA -W, 100 year
Type:Computed Flood
HYDROGRAPH INFORMATION]
Peak Flow (Qp)6.72 (cfs)
Time to Peak (Tp)716.00 (min)
Time of Base (Tb)1456.39 (min)
Volume 0.3055 (ac -ft)
Time Step 2.00 (min)
Flow Multiplier 1.00
UNIT HYDROGRAPH INFORMATION]
Type SCS Curvilinear
Peak Flow (Qp)8.17 (cfs)
Time to Peak (Tp)3.33 (min)
Time of Base (Tb)16.67 (min)
Volume 0.0498 (ac -ft)
Shape Factor 484.00
Time Step:2.00 (min)
Excess Rain 1.00 (in)
Lag Time 3.00 (min)
BASIN INFORMATION]
WEIGHTED WATERSHED AREA]
Description Area CN
None>
Overall Approximation 0.6000 93
TIME CONCENTRATION -- User Defined]
Time of Concentration (Tc)5.00 (min)
RAINFALL DESCRIPTION]
Distribution Type SCS II
Total Precipitation 8.00 (in)
Return Period 2 (yr)
Storm Duration 24.00 (hr)
Rivanna Engineering & Surveying, PLC Page 11
434) 984 -1599
HOLLYMEAD TOWN CENTER - SWM1
FLOOD HYDROGRAPH REPORT
Name:DA -X, 2 year
Type:Computed Flood
HYDROGRAPH INFORMATION]
Peak Flow (Qp)1.16 (cfs)
Time to Peak (Tp)716.00 (min)
Time of Base (Tb)1456.39 (min)
Volume 0.0469 (ac -ft)
Time Step 2.00 (min)
Flow Multiplier 1.00
UNIT HYDROGRAPH INFORMATION]
Type SCS Curvilinear
Peak Flow (Qp)2.99 (cfs)
Time to Peak (Tp)3.33 (min)
Time of Base (Tb)16.67 (min)
Volume 0.0183 (ac -ft)
Shape Factor 484.00
Time Step:2.00 (min)
Excess Rain 1.00 (in)
Lag Time 3.00 (min)
BASIN INFORMATION]
WEIGHTED WATERSHED AREA]
Description Area CN
None>
Overall Approximation 0.2200 93
TIME CONCENTRATION -- User Defined]
Time of Concentration (Tc)5.00 (min)
RAINFALL DESCRIPTION]
Distribution Type SCS II
Total Precipitation 4.00 (in)
Return Period 2 (yr)
Storm Duration 24.00 (hr)
Rivanna Engineering & Surveying, PLC Page 12
434) 984 -1599
HOLLYMEAD TOWN CENTER - SWM1
FLOOD HYDROGRAPH REPORT
Name:DA -X, 10 year
Type:Computed Flood
HYDROGRAPH INFORMATION]
Peak Flow (Qp)1.82 (cfs)
Time to Peak (Tp)716.00 (min)
Time of Base (Tb)1456.39 (min)
Volume 0.0781 (ac -ft)
Time Step 2.00 (min)
Flow Multiplier 1.00
UNIT HYDROGRAPH INFORMATION]
Type SCS Curvilinear
Peak Flow (Qp)2.99 (cfs)
Time to Peak (Tp)3.33 (min)
Time of Base (Tb)16.67 (min)
Volume 0.0183 (ac -ft)
Shape Factor 484.00
Time Step:2.00 (min)
Excess Rain 1.00 (in)
Lag Time 3.00 (min)
BASIN INFORMATION]
WEIGHTED WATERSHED AREA]
Description Area CN
None>
Overall Approximation 0.2200 93
TIME CONCENTRATION -- User Defined]
Time of Concentration (Tc)5.00 (min)
RAINFALL DESCRIPTION]
Distribution Type SCS II
Total Precipitation 6.00 (in)
Return Period 2 (yr)
Storm Duration 24.00 (hr)
Rivanna Engineering & Surveying, PLC Page 13
434) 984 -1599
HOLLYMEAD TOWN CENTER — SWM1
FLOOD HYDROGRAPH REPORT
Name:DA -X, 100 year
Type:Computed Flood
HYDROGRAPH INFORMATION]
Peak Flow (Qp)2.46 (cfs)
Time to Peak (Tp)716.00 (min)
Time of Base (Tb)1456.39 (min)
Volume 0.1097 (ac -ft)
Time Step 2.00 (min)
Flow Multiplier 1.00
UNIT HYDROGRAPH INFORMATION]
Number 3
Type SCS Curvilinear
Peak Flow (Qp)2.99 (cfs)
Time to Peak (Tp)3.33 (min)
Time of Base (Tb)16.67 (min)
Volume 0.0183 (ac -ft)
Shape Factor 484.00
Time Step:2.00 (min)
Excess Rain 1.00 (in)
Lag Time 3.00 (min)
BASIN INFORMATION]
WEIGHTED WATERSHED AREA]
Description Area CN
None>
Overall Approximation 0.2200 93
TIME CONCENTRATION -- User Defined]
Time of Concentration (Tc)5.00 (min)
RAINFALL DESCRIPTION]
Distribution Type SCS II
Total Precipitation 8.00 (in)
Return Period 2 (yr)
Storm Duration 24.00 (hr)
Rivanna Engineering & Surveying, PLC Page 14
434) 984 -1599
HOLLYMEAD TOWN CENTER - SWM1
FLOOD HYDROGRAPH REPORT
Name:DA -Y, 2 year
Type:Computed Flood
HYDROGRAPH INFORMATION]
Peak Flow (Qp)1.00 (cfs)
Time to Peak (Tp)716.00 (min)
Time of Base (Tb)1456.39 (min)
Volume 0.0400 (ac -ft)
Time Step 2.00 (min)
Flow Multiplier 1.00
UNIT HYDROGRAPH INFORMATION]
Type SCS Curvilinear
Peak Flow (Qp)2.59 (cfs)
Time to Peak (Tp)3.33 (min_)
Time of Base (Tb)16.67 (min)
Volume 0.0158 (ac -ft)
Shape Factor 484.00
Time Step:2.00 (min)
Excess Rain 1.00 (in)
Lag Time 3.00 (min)
BASIN INFORMATION]
WEIGHTED WATERSHED AREA]
Description Area CN
None>
Overall Approximation 0.1900 93
TIME CONCENTRATION -- User Defined]
Time of Concentration (Tc)5.00 (min)
RAINFALL DESCRIPTION]
Distribution Type SCS II
Total Precipitation 4.00 (in)
Return Period 2 (yr)
Storm Duration 24.00 (hr)
Rivanna Engineering & Surveying, PLC Page 15
434) 984 -1599
HOLLYMEAD TOWN CENTER - SWM1
FLOOD HYDROGRAPH REPORT
Name:DA -Y, 10 year
Type:Computed Flood
HYDROGRAPH INFORMATION]
Peak Flow (Qp)1.57 (cfs)
Time to Peak (Tp)716.00 (min)
Time of Base (Tb)1456.39 (min)
Volume 0.0669 (ac -ft)
Time Step 2.00 (min)
Flow Multiplier 1.00
UNIT HYDROGRAPH INFORMATION]
Type SCS Curvilinear
Peak Flow (Qp)2.59 (cfs)
Time to Peak (Tp)3.33 (min)
Time of Base (Tb)16.67 (min)
Volume 0.0158 (ac -ft)
Shape Factor 484.00
Time Step:2.00 (min)
Excess Rain 1.00 (in)
Lag Time 3.00 (min)
BASIN INFORMATION]
WEIGHTED WATERSHED AREA]
Description Area CN
None>
Overall Approximation 0.1900 93
TIME CONCENTRATION -- User Defined]
Time of Concentration (Tc)5.00 (min)
RAINFALL DESCRIPTION]
Distribution Type SCS II
Total Precipitation 6.00 (in)
Return Period 2 (yr)
Storm Duration 24.00 (hr)
Rivanna Engineering & Surveying, PLC Page 16
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HOLLYMEAD TOWN CENTER - SWM1
FLOOD HYDROGRAPH REPORT
Name:DA -Y, 100 year
Type:Computed Flood
HYDROGRAPH INFORMATION]
Peak Flow (Qp)2.13 (cfs)
Time to Peak (Tp)716.00 (min)
Time of Base (Tb)1456.39 (min)
Volume 0.0942 (ac -ft)
Time Step 2.00 (min)
Flow Multiplier 1.00
UNIT HYDROGRAPH INFORMATION]
Type SCS Curvilinear
Peak Flow (Qp)2.59 (cfs)
Time to Peak (Tp)3.33 (min)
Time of Base (Tb)16.67 (min)
Volume 0.0158 (ac -ft)
Shape Factor 484.00
Time Step:2.00 (min)
Excess Rain 1.00 (in)
Lag Time 3.00 (min)
BASIN INFORMATION]
WEIGHTED WATERSHED AREA]
Description Area CN
None>
Overall Approximation 0.1900 93
TIME CONCENTRATION -- User Defined]
Time of Concentration (Tc)5.00 (min)
RAINFALL DESCRIPTION]
Distribution Type SCS II
Total Precipitation 8.00 (in)
Return Period 2 (yr)
Storm Duration 24.00 (hr)
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HOLLYMEAD TOWN CENTER - SWM1
FLOOD HYDROGRAPH REPORT
Name:DA -Z Rtd., 2 year
Type:Reservoir: Modified Puls
HYDROGRAPH INFORMATION], (Includes flow to 18" D.I.P. to Forest Lakes Pond)
Peak Flow (Qp)29.87 (cfs)
Time to Peak (Tp)732.00 (min)
Time of Base (Tb)2296.00 (min)
Volume 7.3542 (ac -ft)
Time Step 2.00 (min)
Peak Elevation 523.1590 (ft)
Detention Time NA
RESERVOIR STRUCTURE INFORMATION]
Name SWM1 - Pond
Storage Type User - Defined Area
Maximum Storage 319287.6250 (cu ft)
Maximum Discharge 133.33 (cfs)
INFLOW HYDROGRAPH INFORMATION]
Name DA -Z, 2 year
Peak Flow (Qp)128.38 (cfs)
Time to Peak (Tp)720.00 (min)
Time of Base (Tb)1472.39 (min)
Volume 7.5394 (ac -ft)
Flow Multiplier 1.00
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HOLLYMEAD TOWN CENTER — SWM1
FLOOD HYDROGRAPH REPORT
Name:DA -Z Rtd., 10 year
Type:Reservoir: Modified Puls
HYDROGRAPH INFORMATION],(Includes flow to 18" D.I.P. to Forest Lakes Pond)
Peak Flow (Qp)48.98 (cfs)
Time to Peak (Tp)732.00 (min)
Time of Base (Tb)2316.00 (min)
Volume 11.9517 (ac -ft)
Time Step 2.00 (min)
Peak Elevation 524.9062 (ft)
Detention Time NA
RESERVOIR STRUCTURE INFORMATION]
Name SWM1 - Pond
Storage Type User - Defined Area
Maximum Storage 319287.6250 (cu ft)
Maximum Discharge 133.33 (cfs)
INFLOW HYDROGRAPH INFORMATION]
Name DA -Z, 10 year
Peak Flow (Qp)200.43 (cfs)
Time to Peak (Tp)720.00 (min)
Time of Base (Tb)1472.39 (min)
Volume 12.1369 (ac -ft)
Flow Multiplier 1.00
Rivanna Engineering & Surveying, PLC Page 19
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FLOOD HYDROGRAPH REPORT
Name:DA -Z Rtd., 100 year
Type:Reservoir: Modified Puls
HYDROGRAPH INFORMATION], (Includes flow to 18" D.I.P. to Forest Lakes Pond)
Peak Flow (Qp)97.93 (cfs)
Time to Peak (Tp)728.00 (min)
Time of Base (Tb)2328.00 (min)
Volume 16.5897 (ac -ft)
Time Step 2.00 (min)
Peak Elevation 526.1333 (ft)
Detention Time NA
RESERVOIR STRUCTURE INFORMATION]
Name SWM1 - Pond
Storage Type User - Defined Area
Maximum Storage 319287.6250 (cu ft)
Maximum Discharge 133.33 (cfs)
INFLOW HYDROGRAPH INFORMATION]
Name DA -Z, 100 year
Peak Flow (Qp)271.66 (cfs)
Time to Peak (Tp)720.00 (min)
Time of Base (Tb)1472.39 (min)
Volume 16.7749 (ac -ft)
Flow Multiplier 1.00
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HOLLYMEAD TOWN CENTER - SWM1
FLOOD HYDROGRAPH REPORT
Name:DA -Z RTD., DA -W, DA -X, & DA -Y (2year)
Type:Combined
HYDROGRAPH INFORMATION], (Includes flow to 18" D.I.P. to Forest Lakes Pond)
Peak Flow (Qp)37.05 (cfs)
Time to Peak (Tp)718.00 (min)
Time of Base (Tb)2246.00 (min)
Volume 7.5749 (ac -ft)
Time Step 2.00 (min)
COMBINED HYDROGRAPH RECORDS]
Name:DA -Z Rtd., 2 year
Type:Reservoir: Modified Puls
Peak Flow (Qp)29.87 (cfs)
Time to Peak (Tp)732.00 (min)
Time Step 2.00 (min)
Name:DA -W, 2 year
Type:Computed Flood
Peak Flow (Qp)3.17 (cfs)
Time to Peak (Tp)716.00 (min)
Time Step 2.00 (min)
Name:DA -X, 2 year
Type:Computed Flood
Peak Flow (Qp)1.16 (cfs)
Time to Peak (Tp)716.00 (min)
Time Step 2.00 (min)
Name:DA -Y, 2 year
Type:Computed Flood
Peak Flow (Qp)1.00 (cfs)
Time to Peak (Tp)716.00 (min)
Time Step 2.00 (min)
Rivanna Engineering & Surveying, PLC Page 21
434) 984 -1599
HOLLYMEAD TOWN CENTER - SWM1
FLOOD HYDROGRAPH REPORT
Name:DA -Z RTD., DA -W, DA -X, & DA -Y (10 year)
Type:Combined
HYDROGRAPH INFORMATION],(Includes flow to 18" D.I.P. to Forest Lakes Pond)
Peak Flow (Qp)54.00 (cfs)
Time to Peak (Tp)730.00 (min)
Time of Base (Tb)2264.00 (min)
Volume 12.3159 (ac -ft)
Time Step 2.00 (min)
COMBINED HYDROGRAPH RECORDS]
Name:DA -Z Rtd., 10 year
Type:Reservoir: Modified Puls
Peak Flow (Qp)48.98 (cfs)
Time to Peak (Tp)732.00 (min)
Time Step 2.00 (min)
Name:DA -W, 10 year
Type:Computed Flood
Peak Flow (Qp)4.96 (cfs)
Time to Peak (Tp)716.00 (min)
Time Step 2.00 (min)
Name:DA -X, 10 year
Type:Computed Flood
Peak Flow (Qp)1.82 (cfs)
Time to Peak (Tp)716.00 (min)
Time Step 2.00 (min)
Name:DA -Y, 10 year
Type:Computed Flood
Peak Flow (Qp)1.57 (cfs)
Time to Peak (Tp)716.00 (min)
Time Step 2.00 (min)
Rivanna Engineering & Surveying, PLC Page 22
434) 984 -1599
HOLLYMEAD TOWN CENTER - SWM1
OUTLET STRUCTURE REPORT
Type Stand Pipe
Name SWM1 - Outlet Structure
RATING CURVE LIMIT]
Minimum Elevation 511.0000 ft)
Maximum Elevation 527.5000 ft)
Elevation Increment 0.2500 ft)
STAND PIPE INFORMATION]
ORIFICE INFORMATION]
Diameter 4.00 ft)
Crest Length 12.57 ft)
Effective Crest Length 8.57 ft)
Orifice Coefficient 0.60
Fractional Open Area 0.83
ORIFICE EQUATION]
Q = Co *A((2gh) /k) ^0.5
DEFINITIONS]
Co Orifice Coefficient
A Wetted Area, sq ft)
WEIR INFORMATION]
Crest Elevation 525.5000 ft)
Weir Coefficient 3.33
Exponential 1.50
WEIR EQUATION]
Q = Cw * L * H ^exp
DEFINITIONS]
Cw Weir Coefficient
H Headwater depth above inlet control section invert ft
L Crest lenght ft
Rivanna Engineering & Surveying, PLC Page 23
434) 984 -1599
HOLLYMEAD TOWN CENTER - SWM1
OUTLET STRUCTURE REPORT
OPTIONAL WEIR INFORMATION]
Type Rectangular Weir Suppressed
WEIR INFORMATION]
Crest Length 4.00 ft)
Crest Elevation 523.7500 ft)
Weir Coefficient 3.33
Exponential 1.50
RECTANGULAR SUPRESSED EQUATION]
Q = Cw * L * H ^exp
DEFINITIONS]
Cw Weir Coefficient
H Headwater depth above inlet control section invert
L Crest lenght
Rivanna Engineering & Surveying, PLC Page 24
434) 984 -1599
HOLLYMEAD TOWN CENTER - SWM1
OUTLET STRUCTURE REPORT
OPTIONAL ORIFICE INFORMATION]
Type Circular Orifice
OPTIONAL ORIFICE INFORMATION]
Diameter 0.67 ft)
Invert Elevation 520.0000 ft)
Orifice Coefficient 0.60
Number of Openings 1
ORIFICE EQUATION]
Q = Co /k) ^0.5
DEFINITIONS]
Co Orifice Coefficient
A Wetted Area, cfs)
k 1
Rivanna Engineering & Surveying, PLC Page 25
434) 984 -1599
HOLLYMEAD TOWN CENTER - SWM1
OUTLET STRUCTURE REPORT
CULVERT INFORMATION]
Type Circular Concrete - Square Edge with Headwall
OUTLET STRUCTURE INFORMATION]
Diameter 36.00 in)
Invert Elevation 516.0000 ft)
Pipe Length 180.00 ft)
Slope 0.01
Manning's n Value 0.01
Orifice Coefficient 0.60
Tailwater Elevation 517.9000 ft)
Number of Barrels 1
UNSUBMERGED EQUATION]
H /Diam = Hc/ Diam +K *(Q /(A *Diam ^0.5)) ^M -0.5 *S
Coefficient K 0.01
Coefficient M 2.00
Q Maximum 42.85
SUBMERGED EQUATION]
H /Diam = c *(Q /(A *Diam ^0.5)) ^2 +Y -0.5 *S
Coefficient c 0.04
Coefficient Y 0.67
Q Minimum 48.97
DEFINITIONS]
H Headwater depth above inlet control section invert, ft)
Diam Interior height of culvert barrel, ft)
He Specific head at critical depth (dc +Vc ^2/2g), ft)
Q Discharge, cfs)
A Full cross sectional area of culvert barrel, sq ft)
S Culvert barrel slope, ft /ft)
Rivanna Engineering & Surveying, PLC Page 26
434) 984 -1599
HOLLYMEAD TOWN CENTER - SWM1
OUTLET STRUCTURE REPORT
STAND PIPE STAGE VS. DISCHARGE]
Elevation Stage Weirs Orifices Stand Pipe Culvert Total
ft)ft)cfs)cfs)cfs)cfs)cfs)
511.5000 0.5000 0.00 0.00 0.00 0.00 0.00
512.0000 1.0000 0.00 0.00 0.00 0.00 0.00
512.5000 1.5000 0.00 0.00 0.00 0.00 0.00
513.0000 2.0000 0.00 0.00 0.00 0.00 0.00
513.5000 2.5000 0.00 0.00 0.00 0.00 0.00
514.0000 3.0000 0.00 0.00 0.00 0.00 0.00
514.5000 3.5000 0.00 0.00 0.00 0.00 0.00
515.0000 4.0000 0.00 0.00 0.00 0.00 0.00
515.5000 4.5000 0.00 0.00 0.00 0.00 0.00
516.0000 5.0000 0.00 0.00 0.00 0.00 0.00
516.5000 5.5000 0.00 0.00 0.00 1.49 0.00
517.0000 6.0000 0.00 0.00 0.00 5.57 0.00
517.5000 6.5000 0.00 0.00 0.00 11.63 0.00
518.0000 7.0000 0.00 0.00 0.00 19.00 0.00
518.5000 7.5000 0.00 0.00 0.00 25.75 0.00
519.0000 8.0000 0.00 0.00 0.00 34.95 0.00
519.5000 8.5000 0.00 0.00 0.00 42.14 0.00
520.0000 9.0000 0.00 0.00 0.00 48.27 0.00
520.5000 9.5000 0.00 0.68 0.00 53.74 0.68
521.0000 10.0000 0.00 1.37 0.00 58.69 1.37
521.5000 10.5000 0.00 1.81 0.00 63.24 1.81
522.0000 11.0000 0.00 2.17 0.00 67.41 2.17
522.5000 11.5000 0.00 2.47 0.00 71.22 2.47
523.0000 12.0000 0.00 2.74 0.00 74.86 2.74
523.5000 12.5000 0.00 2.99 0.00 78.35 2.99
524.0000 13.0000 1.67 3.22 0.00 81.71 4.88
524.5000 13.5000 8.65 3.43 0.00 84.96 12.08
525.0000 14.0000 18.62 3.63 0.00 88.10 22.24
525.5000 14.5000 30.84 3.82 0.00 91.14 34.66
526.0000 15.0000 44.95 4.00 10.09 94.09 59.04
526.5000 15.5000 60.74 4.17 28.53 96.96 93.44
527.0000 16.0000 78.04 4.34 50.96 99.75 99.75
527.5000 16.5000 96.73 4.50 68.95 102.47 102.47
Rivanna Engineering & Surveying, PLC Page 27
434) 984 -1599
HOLLYMEAD TOWN CENTER - SWM1
OUTLET STRUCTURE REPORT
Type Stand Pipe
Name SWM1 - Forest Lakes Pipe
RATING CURVE LIMIT]
Minimum Elevation 511.0000 ft)
Maximum Elevation 528.0000 ft)
Elevation Increment 0.2500 ft)
STAND PIPE INFORMATION]
ORIFICE INFORMATION]
Diameter 1.30 ft)
Crest Length 4.08 ft)
Effective Crest Length 1.08 ft)
Orifice Coefficient 0.60
Fractional Open Area 1.00
ORIFICE EQUATION]
Q = Co *A((2gh) /k) ^0.5
DEFINITIONS]
Co Orifice Coefficient
A Wetted Area, sq ft)
WEIR INFORMATION]
Crest Elevation 524.6000 ft)
Weir Coefficient 3.33
Exponential 1.50
WEIR EQUATION]
Q = Cw * L * H ^exp
DEFINITIONS]
Cw Weir Coefficient
H Headwater depth above inlet control section invert ft
L Crest lenght ft
Rivanna Engineering & Surveying, PLC Page 28
434) 984 -1599
HOLLYMEAD TOWN CENTER - SWM1
OUTLET STRUCTURE REPORT
OPTIONAL WEIR INFORMATION]
Type Rectangular Weir Suppressed
WEIR INFORMATION]
Crest Length 3.00 ft)
Crest Elevation 520.0000 ft)
Weir Coefficient 3.33
Exponential 1.50
RECTANGULAR SUPRESSED EQUATION]
Q = Cw * L * H ^exp
DEFINITIONS]
Cw Weir Coefficient
H Headwater depth above inlet control section invert
L Crest lenght
Rivanna Engineering & Surveying, PLC Page 29
434) 984 -1599
HOLLYMEAD TOWN CENTER - SWM1
OUTLET STRUCTURE REPORT
OPTIONAL ORIFICE INFORMATION]
Type Rectangular Orifice
OPTIONAL ORIFICE INFORMATION]
Height 1.50 ft)
Width 1.50 ft)
Invert Elevation 520.0000 ft)
Orifice Coefficient 0.60
Number of Openings 1
ORIFICE EQUATION]
Q = Co *A((2gh) /k) ^0.5
DEFINITIONS]
Co Orifice Coefficient
A Wetted Area, cfs)
k 1
Rivanna Engineering & Surveying, PLC Page 30
434) 984 -1599
HOLLYMEAD TOWN CENTER - SWM1
OUTLET STRUCTURE REPORT
CULVERT INFORMATION]
Type Circular Concrete - Square Edge with Headwall
OUTLET STRUCTURE INFORMATION]
Diameter 18.00 in)
Invert Elevation 511.5900 ft)
Pipe Length 130.00 ft)
Slope 0.03
Manning's n Value 0.01
Orifice Coefficient 0.60
Tailwater Elevation 507.9700 ft)
Number of Barrels 1
UNSUBMERGED EQUATION]
H /Diam = Hc/ Diam +K *(Q /(A *Diam ^0.5)) ^M -0.5 *S
Coefficient K 0.01
Coefficient M 2.00
Q Maximum 7.58
SUBMERGED EQUATION]
H /Diam = c *(Q /(A *Diam ^0.5)) ^2 +Y -0.5 *S
Coefficient c 0.04
Coefficient Y 0.67
Q Minimum 8.66
DEFINITIONS]
H Headwater depth above inlet control section invert, ft)
Diam Interior height of culvert barrel, ft)
He Specific head at critical depth (dc +Vc ^2/2g), ft)
Q Discharge, cfs)
A Full cross sectional area of culvert barrel, sq ft)
S Culvert barrel slope, ft /ft)
Rivanna Engineering & Surveying, PLC Page 31
434) 984 -1599
HOLLYMEAD TOWN CENTER - SWM1
OUTLET STRUCTURE REPORT
STAND PIPE STAGE VS. DISCHARGE]
Elevation Stage Weirs Orifices Stand Pipe Culvert Total
ft)ft)cfs)cfs)cfs)cfs)cfs)
520.0000 9.0000 0.00 0.00 0.00 23.90 0.00
520.5000 9.5000 3.53 1.80 0.00 24.42 5.34
521.0000 10.0000 9.99 5.10 0.00 24.94 15.09
521.5000 10.5000 18.35 9.38 0.00 25.44 25.44
522.0000 11.0000 28.26 12.11 0.00 25.94 25.94
522.5000 11.5000 39.49 14.33 0.00 26.42 26.42
523.0000 12.0000 51.91 16.24 0.00 26.90 26.90
523.1600* 12.1600 56.32 16.79 0.00 27.05 27.05
523.5000 12.5000 65.41 17.96 0.00 27.37 27.37
524.0000 13.0000 79.92 19.52 0.00 27.83 27.83
524.5000 13.5000 95.36 20.97 0.00 28.28 28.28
524.9100 ** 13.9100 108.75 22.09 0.00 28.66 28.66
525.0000 14.0000 111.69 22.33 0.91 28.73 28.73
525.5000 14.5000 128.86 23.60 3.08 29.17 29.17
526.0000 15.0000 146.82 24.81 5.98 29.60 29.60
526.1300 * ** 15.1300 151.69 25.11 6.68 29.71 29.71
526.5000 15.5000 165.55 25.97 8.30 30.03 30.03
527.0000 16.0000 185.02 27.07 9.90 30.45 30.45
527.5000 16.5000 205.19 28.14 10.88 30.86 30.86
528.0000 17.0000 226.05 29.16 11.78 31.27 31.27
Water surface elevation obtained during 2yr storm event.
Water surface elevation obtained during 10yr storm event.
Water surface elevation obtained during 100yr storm event.
Rivanna Engineering & Surveying, PLC Page 32
434) 984 -1599
HOLLYMEAD TOWN CENTER - SWM1
RESERVOIR REPORT
Name: SWM1 - Pond
RATING CURVE LIMIT]
Minimum Elevation 511.0000 (ft)
Maximum Elevation 527.5000 (ft)
Elevation Increment 0.5000 (ft)
STAGE STORAGE INFORMATION]
Storage Method: User - Defined Storage
Input Method: Area
Number Elevation Area Ave Area Volume Cumulative
Volume
ft)sq ft)sq ft)cu ft)cu ft)
1 519.9000 0.0000 0.0000 0.0000 0.0000
2 520.0000 32269.0000 16134.5000 1613.4500 1613.4500
3 522.0000 37079.0000 34674.0000 69348.0000 70961.4500
4 524.0000 42135.0000 39607.0000 79214.0000 150175.4500
5 525.0000 44748.0000 43441.5000 43441.5000 193616.9500
6 526.0000 47094.5000 45921.2500 45921.2500 239538.2000
7 527.5000 50633.0000 48863.7500 73295.6250 312833.8250
DISCHARGE INFORMATION]
Structure Number: 1
Type:
Name:SWM1 - Outlet Structure
Structure Number: 2
Type:
Name:SWM1 - Forest Lakes Pipe
Rivanna Engineering & Surveying, PLC Page 33
434) 984 -1599
HOLLYMEAD TOWN CENTER - SWM1
RESERVOIR REPORT
RESERVOIR STAGE STORAGE /DISCHARGE]
Elevation Stage Area Storage
Discharge
ft)ft)sq ft)cu ft)cfs)
511.0000 0.0000 0.0000 0.0000 0.00
511.5000 0.5000 0.0000 0.0000 0.00
512.0000 1.0000 0.0000 0.0000 0.00
512.5000 1.5000 0.0000 0.0000 0.00
513.0000 2.0000 0.0000 0.0000 0.00
513.5000 2.5000 0.0000 0.0000 0.00
514.0000 3.0000 0.0000 0.0000 0.00
514.5000 3.5000 0.0000 0.0000 0.00
515.0000 4.0000 0.0000 0.0000 0.00
515.5000 4.5000 0.0000 0.0000 0.00
516.0000 5.0000 0.0000 0.0000 0.00
516.5000 5.5000 0.0000 0.0000 0.00
517.0000 6.0000 0.0000 0.0000 0.00
517.5000 6.5000 0.0000 0.0000 0.00
518.0000 7.0000 0.0000 0.0000 0.00
518.5000 7.5000 0.0000 0.0000 0.00
519.0000 8.0000 0.0000 0.0000 0.00
519.5000 8.5000 0.0000 0.0000 0.00
520.0000 9.0000 32269.0000 8067.2500 0.00
520.5000 9.5000 33471.5000 24502.3750 6.01
521.0000 10.0000 34674.0000 41538.7500 16.47
521.5000 10.5000 35876.5000 59176.3750 27.26
522.0000 11.0000 37079.0000 77415.2500 28.11
522.5000 11.5000 38343.0000 96270.7500 28.90
523.0000 12.0000 39607.0000 115758.2500 29.64
523.5000 12.5000 40871.0000 135877.7500 30.36
524.0000 13.0000 42135.0000 156629.2500 32.71
524.5000 13.5000 43441.5000 178023.3750 40.36
52 14, 0nnn 44748.0000 200070.7500 50.97
525.5000 14.5000 45921.2500 222738.0625 63.82
526.0000 15.0000 47094.5000 245992.0000 88.64
526.5000 15.5000 48274.0000 269834.1250 123.47
527.0000 16.0000 49453.5000 294266.0000 130.20
527.5000 16.5000 50633.0000 319287.6250 133.33
Maximum Storage 319287.6250 (cu ft)
Maximum Discharge 133.33 (cfs)
Rivanna Engineering & Surveying, PLC Page 34
434) 984 -1599
HOLLYMEAD TOWN CENTER — SWM1
SEDIMENT BASIN CONDITIONS
Name:DA -Z Rtd., 2 year
Type:Reservoir: Modified Puls
HYDROGRAPH INFORMATION]
Peak Flow (Qp)10.26 (cfs)
Time to Peak (Tp)756.00 (min)
Time of Base (Tb)2880.00 (min)
Volume 5.3140 (ac -ft)
Time Step 2.00 (min)
Peak Elevation 520.1476 (ft)
Detention Time NA
RESERVOIR STRUCTURE INFORMATION]
Name SWM1 - Pond
Storage Type User - Defined Area
Maximum Storage 433803.7500 (cu ft)
Maximum Discharge 99.97 (cfs)
INFLOW HYDROGRAPH INFORMATION]
Name DA -Z, 2 year
Peak Flow (Qp)128.38 (cfs)
Time to Peak (Tp)720.00 (min)
Time of Base (Tb)1472.39 (min)
Volume 7.5394 (ac -ft)
Flow Multiplier 1.00
Rivanna Engineering & Surveying, PLC Page 35
434) 984 -1599
HOLLYMEAD TOWN CENTER — SWM1
SEDIMENT BASIN CONDITIONS
Name:DA -Z Rtd., 10 year
Type:Reservoir: Modified Puls
HYDROGRAPH INFORMATION]
Peak Flow (Qp)24.75 (cfs)
Time to Peak (Tp)744.00 (min)
Time of Base (Tb)2880.00 (min)
Volume 9.9114 (ac -ft)
Time Step 2.00 (min)
Peak Elevation 523.2906 (ft)
Detention Time NA
RESERVOIR STRUCTURE INFORMATION]
Name SWM1 - Pond
Storage Type User - Defined Area
Maximum Storage 433803.7500 (cu ft)
Maximum Discharge 99.97 (cfs)
INFLOW HYDROGRAPH INFORMATION]
Name DA -Z, 10 year
Peak Flow (Qp)200.43 (cfs)
Time to Peak (Tp)720.00 (min)
Time of Base (Tb)1472.39 (min)
Volume 12.1369 (ac -ft)
Flow Multiplier 1.00
Rivanna Engineering & Surveying, PLC Page 36
434) 984 -1599
HOLLYMEAD TOWN CENTER — SWM1
SEDIMENT BASIN CONDITIONS
Name:DA -Z Rtd., 100 year
Type:Reservoir: Modified Puls
HYDROGRAPH INFORMATION]
Peak Flow (Qp)71.05 (cfs)
Time to Peak (Tp)732.00 (min)
Time of Base (Tb)2880.00 (min)
Volume 14.5493 (ac -ft)
Time Step 2.00 (min)
Peak Elevation 525.1790 (ft)
Detention Time NA
RESERVOIR STRUCTURE INFORMATION]
Name SWM1 - Pond
Storage Type User - Defined Area
Maximum Storage 433803.7500 (cu ft)
Maximum Discharge 99.97 (cfs)
INFLOW HYDROGRAPH INFORMATION]
Name DA -Z, 100 year
Peak Flow (Qp)271.66 (cfs)
Time to Peak (Tp)720.00 (min)
Time of Base (Tb)1472.39 (min)
Volume 16.7749 (ac -ft)
Flow Multiplier 1.00
Rivanna Engineering & Surveying, PLC Page 37
434) 984 -1599
HOLLYMEAD TOWN CENTER - SWM1
SEDIMENT BASIN CONDITIONS
Name: SWM1 - Pond
RATING CURVE LIMIT]
Minimum Elevation 511.0000 (ft)
Maximum Elevation 526.0000 (ft)
Elevation Increment 0.5000 (ft)
STAGE STORAGE INFORMATION]
Storage Method: User - Defined Storage
Input Method: Area
No. Elevation Area Ave Area Volume Cumulative Volume
ft)sq ft)sq ft)cu ft)cu ft)
1 511.0000 0.0000 0.0000 0.0000 0.0000
2 512.0000 15476.0000 7738.0000 7738.0000 7738.0000
3 514.0000 19245.0000 17360.5000 34721.0000 42459.0000
4 516.0000 23306.0000 21275.5000 42551.0000 85010.0000
5 518.0000 27647.0000 25476.5000 50953.0000 135963.0000
6 520.0000 32269.0000 29958.0000 59916.0000 195879.0000
7 522.0000 37079.0000 34674.0000 69348.0000 265227.0000
8 524.0000 42135.0000 39607.0000 79214.0000 344441.0000
9 525.0000 44748.0000 43441.5000 43441.5000 387882.5000
10 526.0000 47094.5000 45921.2500 45921.2500 433803.7500
Rivanna Engineering & Surveying, PLC Page 38
434) 984 -1599
HOLLYMEAD TOWN CENTER - SWM1
SEDIMENT BASIN CONDITIONS
DISCHARGE INFORMATION]
Name:SWM1- Sed. Basin Structure
RESERVOIR STAGE STORAGE /DISCHARGE]
Elevation Stage Area Storage Discharge
ft)ft)sq ft)cu ft)cfs)
511.0000 0.0000 0.0000 0.0000 0.00
511.5000 0.5000 7738.0000 1934.5000 0.00
512.0000 1.0000 15476.0000 7738.0000 0.00
512.5000 1.5000 16418.2500 15711.5625 0.00
513.0000 2.0000 17360.5000 24156.2500 0.00
513.5000 2.5000 18302.7500 33072.0625 0.00
514.0000 3.0000 19245.0000 42459.0000 0.00
514.5000 3.5000 20260.2500 52335.3125 0.00
515.0000 4.0000 21275.5000 62719.2500 0.00
515.5000 4.5000 22290.7500 73610.8125 0.00
516.0000 5.0000 23306.0000 85010.0000 0.00
516.5000 5.5000 24391.2500 96934.3125 0.00
517.0000 6.0000 25476.5000 109401.2500 1.10
517.5000 6.5000 26561.7500 122410.8125 3.58
518.0000 7.0000 27647.0000 135963.0000 5.53
518.5000 7.5000 28802.5000 150075.3750 6.93
519.0000 8.0000 29958.0000 164765.5000 8.09
519.5000 8.5000 31113.5000 180033.3750 9.10
520.0000 9.0000 32269.0000 195879.0000 10.01
520.5000 9.5000 33471.5000 212314.1250 10.85
521.0000 10.0000 34674.0000 229350.5000 11.63
521.5000 10.5000 35876.5000 246988.1250 12.35
522.0000 11.0000 37079.0000 265227.0000 13.04
522.5000 11.5000 38343.0000 284082.5000 14.59
523.0000 12.0000 39607.0000 303570.0000 20.17
523.5000 12.5000 40871.0000 323689.5000 28.05
524.0000 13.0000 42135.0000 344441.0000 37.63
524.5000 13.5000 43441.5000 365835.1250 48.64
525.0000 14.0000 44748.0000 387882.5000 60.90
525.5000 14.5000 45921.2500 410549.8125 89.24
526.0000 15.0000 47094.5000 433803.7500 99.97
Maximum Storage 433803.7500 (cu ft)
Maximum Discharge 99.97 (cfs)
Rivanna Engineering & Surveying, PLC Page 39
434) 984 -1599
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