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Home My WebLink AboutWPO200400011 Calculations 2005-07-01 .. �._w etdschttot tietke i } f HYDROLOGIC/HYDRAULIC CALCULATIONS - 6o FOR Luxor Subdivision & Road Networks February 4, 2004 Rev. August 3, 2004 Rev. October 19, 2004 , a 09 Rev. November 29, 2004 Rev. June 6, 2005 Rev: July 1, 2005 LOCATION: Tax Map 78 Parcels 12B Albemarle County, Virginia PREPARED BY: Rivanna Engineering & Surveying, PLC 1350 Stony Point Rd. Charlottesville, VA 22911 P: 434.984.1599 JUL 0 6 2005 F: 434.984.8863 Run-off Summary Point of Pre-Dev Pre-Dev Pre-Dev Post - Post-Dev Post-Dev Analysis DA 2-Year 10-Year Dev Rtd. 2- Rtd. 10- DA Year Year Outfall 3 3 26.23 37.24 3 Post 13.54 23.56 Outfall 2 2 75.35 109.77 2 Post & 61.28 66.20 SWM#3 Outfall 1 1 120.98 175.31 Fontana 103.63 139.30 Pond, 1, & SWM2 ' 93•13 lob I O��gALTH o�G ,' J o� / V.,. TI THY RAY MILLER 0402 030542 SSI)NA',046 Luxor Subdivision Index Index: 2 Summary: 3 Stormwater Management Pond #3 Pre-Development: Flood Hydrographs: 4-9 Post-Development: Flood Hydrographs: 10-15 Outlet Structures: 16-18 Reservoir: 19 Routed Hydrographs: 20-25 Westminster Canterbury Pond, SWM #2 Pre-Development: Flood Hydrographs: 26-31 Post-Development: Flood Hydrographs: 32-43 Outlet Structures: 44-45 Reservoir: 46-47 Routed Hydrographs: 48-55 Stormwater Management Pond #1 Pre-Development: Flood Hydrographs: 54-65 Post-Development: Flood Hydrographs: 66-83 Outlet Structures: 84-85 Reservoir: 86 Routed Hydrographs: 87-92 Uncontained Hydrographs: 93-99 Combined Hydrographs: 99-102 NOTE: DA Maps are part of the Luxor Stormwater Management Plans. Rivanna Engineering&Surveying, PLC Page 2 (434)984-1599 Luxor Subdivision Summary Stormwater Management Facility #3 will provide water quality and volume control measures for portions of existing Westminster Canterbury and Ashcroft Subdivision currently handled by Stormwater Management Facility #2 and future residential and commercial areas. The BMP measures for this facility will consist of an aquatic bench, forebays, and extended detention. Stormwater Management Facility #2 is an existing stormwater management facility designed to provide water quality and volume control measures for Westminster Canterbury and Fontana. Post-construction, Facility #2 will provide water quality and volume control measures for Luxor Phase 1&2 and parts of the Fontana Subdivision in addition to receiving the routed flow from Facility #3. The BMP measures for this facility consist of forebays and extended detention. Stormwater Management Facility #1 will provide water quality and volume control measures for the North Pantops Commercial area, the Fontana Subdivision, and Phases 2 & 3 of the Luxor Subdivision. The construction of Facility #1 and the road network for Luxor Subdivison will consist of the removal of the existing Fontana Pond currently serving portions of the Fontana Subdivison. The area currently flowing to the Fontana Pond will be redirected to Facility #1. The BMP measures for this facility will consist of forebays, an aquatic bench, and extended detention. Rivanna Engineering&Surveying,PLC Page 3 (434)984-1599 Luxor Subdivision Stormwater Management Facility#3 Pre-Development Hydrograph Report Name: DA-3, 2yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow ((a) = 26.23 (cfs) Time to Peak (Tp) = 17.00 (min) Time of Base (Tb) = 42.50 (min) Volume = 0.77 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 0.77 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef Westminster (Undeveloped) 9.10 0 0.30 Ashcroft 3.30 0 0.40 Woods/Brush 14.30 0 0.30 Overall Approximation 26.70 NA 0.31 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 17.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 0.88 (in) Return Period = 2 (yr) Storm Duration = 0.28 (hr) Rivanna Engineering&Surveying, PLC Page 4 (434)984-1599 Luxor Subdivision Stormwater Management Facility#3 Pre-Development Hydrograph Report DA-3, 2yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.05 0.00 1.54 2 2.00 0.05 0.10 1.54 3.09 3 3.00 0.05 0.16 1.54 4.63 4 4.00 0.05 0.21 1.54 6.17 5 5.00 0.05 0.26 1.54 7.71 6 6.00 0.05 0.31 1.54 9.26 7 7.00 0.05 0.36 1.54 10.80 8 8.00 0.05 0.42 1.54 12.34 9 9.00 0.05 0.47 1.54 13.88 10 10.00 0.05 0.52 1.54 15.43 11 11.00 0.05 0.57 1.54 16.97 12 12.00 0.05 0.62 1.54 18.51 13 13.00 0.05 0.68 1.54 20.06 14 14.00 0.05 0.73 1.54 21.60 15 15.00 0.05 0.78 1.54 23.14 16 16.00 0.05 0.83 1.54 24.68 17 17.00 0.05 0.88 1.54 26.23 18 18.00 0.00 0.88 -1.03 25.20 19 19.00 0.00 0.88 -1.03 24.17 20 20.00 0.00 0.88 -1.03 23.14 21 21.00 0.00 0.88 -1.03 22.11 22 22.00 0.00 0.88 -1.03 21.08 23 23.00 0.00 0.88 -1.03 20.06 24 24.00 0.00 0.88 -1.03 19.03 25 25.00 0.00 0.88 -1.03 18.00 26 26.00 0.00 0.88 -1.03 16.97 27 27.00 0.00 0.88 -1.03 15.94 28 28.00 0.00 0.88 -1.03 14.91 29 29.00 0.00 0.88 -1.03 13.88 30 30.00 0.00 0.88 -1.03 12.86 31 31.00 0.00 0.88 -1.03 11.83 32 32.00 0.00 0.88 -1.03 10.80 33 33.00 0.00 0.88 -1.03 9.77 34 34.00 0.00 0.88 -1.03 8.74 35 35.00 0.00 0.88 -1.03 7.71 36 36.00 0.00 0.88 -1.03 6.69 37 37.00 0.00 0.88 -1.03 5.66 38 38.00 0.00 0.88 -1.03 4.63 39 39.00 0.00 0.88 -1.03 3.60 40 40.00 0.00 0.88 -1.03 2.57 41 41.00 0.00 0.88 -1.03 1.54 42 42.00 0.00 0.88 -1.03 0.51 43 42.50 0.00 0.88 -0.51 0.00 Rivanna Engineering&Surveying,PLC Page 5 (434)984-1599 Luxor Subdivision Stormwater Management Facility#3 Pre-Development Hydrograph Report Name: DA-3, l0yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 37.24 (cfs) Time to Peak (Tp) = 17.00 (min) Time of Base (Tb) = 42.50 (min) Volume = 1.09 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 1.09 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef Westminster (Undeveloped) 9.10 0 0.30 Ashcroft 3.30 0 0.40 Woods/Brush 14.30 0 0.30 Overall Approximation 26.70 NA 0.31 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 17.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 1.25 (in) Return Period = User Defined (yr) Storm Duration = 0.28 (hr) Rivanna Engineering&Surveying,PLC Page 6 (434)984-1599 Luxor Subdivision Stormwater Management Facility#3 Pre-Development Hydrograph Report DA-3, l0yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.07 0.00 2.19 2 2.00 0.07 0.15 2.19 4.38 3 3.00 0.07 0.22 2.19 6.57 4 4.00 0.07 0.30 2.19 8.76 5 5.00 0.07 0.37 2.19 10.95 6 6.00 0.07 0.44 2.19 13.14 7 7.00 0.07 0.52 2.19 15.33 8 8.00 0.07 0.59 2.19 17.52 9 9.00 0.07 0.66 2.19 19.71 10 10.00 0.07 0.74 2.19 21.90 11 11.00 0.07 0.81 2.19 24.10 12 12.00 0.07 0.89 2.19 26.29 13 13.00 0.07 0.96 2.19 28.48 14 14.00 0.07 1.03 2.19 30.67 15 15.00 0.07 1.11 2.19 32.86 16 16.00 0.07 1.18 2.19 35.05 17 17.00 0.07 1.25 2.19 37.24 18 18.00 0.00 1.25 -1.46 35.78 19 19.00 0.00 1.25 -1.46 34.32 20 20.00 0.00 1.25 -1.46 32.86 21 21.00 0.00 1.25 -1.46 31.40 22 22.00 0.00 1.25 -1.46 29.94 23 23.00 0.00 1.25 -1.46 28.48 24 24.00 0.00 1.25 -1.46 27.02 25 25.00 0.00 1.25 -1.46 25.56 26 26.00 0.00 1.25 -1.46 24.10 27 27.00 0.00 1.25 -1.46 22.63 28 28.00 0.00 1.25 -1.46 21.17 29 29.00 0.00 1.25 -1.46 19.71 30 30.00 0.00 1.25 -1.46 18.25 31 31.00 0.00 1.25 -1.46 16.79 32 32.00 0.00 1.25 -1.46 15.33 33 33.00 0.00 1.25 -1.46 13.87 34 34.00 0.00 1.25 -1.46 12.41 35 35.00 0.00 1.25 -1.46 10.95 36 36.00 0.00 1.25 -1.46 9.49 37 37.00 0.00 1.25 -1.46 8.03 38 38.00 0.00 1.25 -1.46 6.57 39 39.00 0.00 1.25 -1.46 5.11 40 40.00 0.00 1.25 -1.46 3.65 41 41.00 0.00 1.25 -1.46 2.19 42 42.00 0.00 1.25 -1.46 0.73 43 42.50 0.00 1.25 -0.73 0.00 Rivanna Engineering&Surveying, PLC Page 7 (434)984-1599 Luxor Subdivision Stormwater Management Facility#3 Pre-Development Hydrograph Report Name: DA-3, 1O0yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 53.96 (cfs) Time to Peak (Tp) = 17.00 (min) Time of Base (Tb) = 42.50 (min) Volume = 1.58 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 1.58 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef Westminster (Undeveloped) 9.10 0 0.30 Ashcroft 3.30 0 0.40 Woods/Brush 14.30 0 0.30 Overall Approximation 26.70 NA 0.31 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 17.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 1.82 (in) Return Period = 100 (yr) Storm Duration = 0.28 (hr) Rivanna Engineering&Surveying,PLC Page 8 (434)984-1599 Luxor Subdivision Stormwater Management Facility#3 Pre-Development Hydrograph Report DA-3, 100yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.11 0.00 3.17 2 2.00 0.11 0.21 3.17 6.35 3 3.00 0.11 0.32 3.17 9.52 4 4.00 0.11 0.43 3.17 12.70 5 5.00 0.11 0.53 3.17 15.87 6 6.00 0.11 0.64 3.17 19.04 7 7.00 0.11 0.75 3.17 22.22 8 8.00 0.11 0.86 3.17 25.39 9 9.00 0.11 0.96 3.17 28.57 10 10.00 0.11 1.07 3.17 31.74 11 11.00 0.11 1.18 3.17 34.91 12 12.00 0.11 1.28 3.17 38.09 13 13.00 0.11 1.39 3.17 41.26 14 14.00 0.11 1.50 3.17 44.44 15 15.00 0.11 1.60 3.17 47.61 16 16.00 0.11 1.71 3.17 50.78 17 17.00 0.11 1.82 3.17 53.96 18 18.00 0.00 1.82 -2.12 51.84 19 19.00 0.00 1.82 -2.12 49.73 20 20.00 0.00 1.82 -2.12 47.61 21 21.00 0.00 1.82 -2.12 45.49 22 22.00 0.00 1.82 -2.12 43.38 23 23.00 0.00 1.82 -2.12 41.26 24 24.00 0.00 1.82 -2.12 39.15 25 25.00 0.00 1.82 -2.12 37.03 26 26.00 0.00 1.82 -2.12 34.91 27 27.00 0.00 1.82 -2.12 32.80 28 28.00 0.00 1.82 -2.12 30.68 29 29.00 0.00 1.82 -2.12 28.57 30 30.00 0.00 1.82 -2.12 26.45 31 31.00 0.00 1.82 -2.12 24.33 32 32.00 0.00 1.82 -2.12 22.22 33 33.00 0.00 1.82 -2.12 20.10 34 34.00 0.00 1.82 -2.12 17.99 35 35.00 0.00 1.82 -2.12 15.87 36 36.00 0.00 1.82 -2.12 13.75 37 37.00 0.00 1.82 -2.12 11.64 38 38.00 0.00 1.82 -2.12 9.52 39 39.00 0.00 1.82 -2.12 7.41 40 40.00 0.00 1.82 -2.12 5.29 41 41.00 0.00 1.82 -2.12 3.17 42 42.00 0.00 1.82 -2.12 1.06 43 42.50 0.00 1.82 -1.06 0.00 Rivanna Engineering&Surveying,PLC Page 9 (434)984-1599 Luxor Subdivision Stormwater Management Facility#3 Post-Development Hydrograph Report Name: DA-3, Post 2yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 71.29 (cfs) Time to Peak (Tp) = 15.00 (min) Time of Base (Tb) = 37.50 (min) Volume = 1.84 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 1.84 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef Townhomes 9.10 0 0.75 1/2acre Lots 14.90 0 0.50 Westminster 10.60 0 0.65 Overall Approximation 34.60 NA 0.61 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 15.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 0.84 (in) Return Period = 2 (yr) Storm Duration = 0.25 (hr) Rivanna Engineering&Surveying,PLC Page 10 (434)984-1599 Luxor Subdivision Stormwater Management Facility#3 Post-Development Hydrograph Report DA-3, Post 2yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.06 0.00 4.75 2 2.00 0.06 0.11 4.75 9.50 3 3.00 0.06 0.17 4.75 14.26 4 4.00 0.06 0.22 4.75 19.01 5 5.00 0.06 0.28 4.75 23.76 6 6.00 0.06 0.33 4.75 28.51 7 7.00 0.06 0.39 4.75 33.27 8 8.00 0.06 0.45 4.75 38.02 9 9.00 0.06 0.50 4.75 42.77 10 10.00 0.06 0.56 4.75 47.52 11 11.00 0.06 0.61 4.75 52.28 12 12.00 0.06 0.67 4.75 57.03 13 13.00 0.06 0.72 4.75 61.78 14 14.00 0.06 0.78 4.75 66.53 15 15.00 0.06 0.84 4.75 71.29 16 16.00 0.00 0.84 -3.17 68.12 17 17.00 0.00 0.84 -3.17 64.95 18 18.00 0.00 0.84 -3.17 61.78 19 19.00 0.00 0.84 -3.17 58.61 20 20.00 0.00 0.84 -3.17 55.44 21 21.00 0.00 0.84 -3.17 52.28 22 22.00 0.00 0.84 -3.17 49.11 23 23.00 0.00 0.84 -3.17 45.94 24 24.00 0.00 0.84 -3.17 42.77 25 25.00 0.00 0.84 -3.17 39.60 26 26.00 0.00 0.84 -3.17 36.43 27 27.00 0.00 0.84 -3.17 33.27 28 28.00 0.00 0.84 -3.17 30.10 29 29.00 0.00 0.84 -3.17 26.93 30 30.00 0.00 0.84 -3.17 23.76 31 31.00 0.00 0.84 -3.17 20.59 32 32.00 0.00 0.84 -3.17 17.43 33 33.00 0.00 0.84 -3.17 14.26 34 34.00 0.00 0.84 -3.17 11.09 35 35.00 0.00 0.84 -3.17 7.92 36 36.00 0.00 0.84 -3.17 4.75 37 37.00 0.00 0.84 -3.17 1.58 38 37.50 0.00 0.84 -1.58 0.00 Rivanna Engineering&Surveying, PLC Page 11 (434)984-1599 Luxor Subdivision Stormwater Management Facility#3 Post-Development Hydrograph Report Name: DA-3, Post l0yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 100.49 (cfs) Time to Peak (Tp) = 15.00 (min) Time of Base (Tb) = 37.50 (min) Volume = 2.60 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 2.60 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef Townhomes ✓ 9.10 0 0.75 1/2acre Lots ✓14.90 0 0.50 Westminster 10.60 0 0.65 Overall Approximation 34.60 NA 0.61 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 15.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 1.18 (in) Return Period = User Defined (yr) Storm Duration = 0.25 (hr) Rivanna Engineering&Surveying,PLC Page 12 (434)984-1599 Luxor Subdivision Stormwater Management Facility#3 Post-Development Hydrograph Report DA-3, Post l0yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.08 0.00 6.70 2 2.00 0.08 0.16 6.70 13.40 3 3.00 0.08 0.24 6.70 20.10 4 4.00 0.08 0.31 6.70 26.80 5 5.00 0.08 0.39 6.70 33.50 6 6.00 0.08 0.47 6.70 40.20 7 7.00 0.08 0.55 6.70 46.89 8 8.00 0.08 0.63 6.70 53.59 9 9.00 0.08 0.71 6.70 60.29 10 10.00 0.08 0.78 6.70 66.99 11 11.00 0.08 0.86 6.70 73.69 12 12.00 0.08 0.94 6.70 80.39 13 13.00 0.08 1.02 6.70 87.09 14 14.00 0.08 1.10 6.70 93.79 15 15.00 0.08 1.18 6.70 100.49 16 16.00 0.00 1.18 -4.47 96.02 17 17.00 0.00 1.18 -4.47 91.56 18 18.00 0.00 1.18 -4.47 87.09 19 19.00 0.00 1.18 -4.47 82.62 20 20.00 0.00 1.18 -4.47 78.16 21 21.00 0.00 1.18 -4.47 73.69 22 22.00 0.00 1.18 -4.47 69.22 23 23.00 0.00 1.18 -4.47 64.76 24 24.00 0.00 1.18 -4.47 60.29 25 25.00 0.00 1.18 -4.47 55.83 26 26.00 0.00 1.18 -4.47 51.36 27 27.00 0.00 1.18 -4.47 46.89 28 28.00 0.00 1.18 -4.47 42.43 29 29.00 0.00 1.18 -4.47 37.96 30 30.00 0.00 1.18 -4.47 33.50 31 31.00 0.00 1.18 -4.47 29.03 32 32.00 0.00 1.18 -4.47 24.56 33 33.00 0.00 1.18 -4.47 20.10 34 34.00 0.00 1.18 -4.47 15.63 35 35.00 0.00 1.18 -4.47 11.17 36 36.00 0.00 1.18 -4.47 6.70 37 37.00 0.00 1.18 -4.47 2.23 38 37.50 0.00 1.18 -2.23 0.00 Rivanna Engineering&Surveying, PLC Page 13 (434)984-1599 Luxor Subdivision Stormwater Management Facility#3 Post-Development Hydrograph Report Name: DA-3, Post 10Oyr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 144.99 (cfs) Time to Peak (Tp) = 15.00 (min) Time of Base (Tb) = 37.50 (min) Volume = 3.75 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 3.75 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef Townhomes 9.10 0 0.75 1/2acre Lots 14.90 0 0.50 Westminster 10.60 0 0.65 Overall Approximation 34.60 NA 0.61 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 15.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 1.70 (in) Return Period = 100 (yr) Storm Duration = 0.25 (hr) Rivanna Engineering&Surveying,PLC Page 14 (434)984-1599 Luxor Subdivision Stormwater Management Facility#3 Post-Development Hydrograph Report DA-3, Post 100yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.11 0.00 9.67 2 2.00 0.11 0.23 9.67 19.33 3 3.00 0.11 0.34 9.67 29.00 4 4.00 0.11 0.45 9.67 38.66 5 5.00 0.11 0.57 9.67 48.33 6 6.00 0.11 0.68 9.67 57.99 7 7.00 0.11 0.79 9.67 67.66 8 8.00 0.11 0.91 9.67 77.33 9 9.00 0.11 1.02 9.67 86.99 10 10.00 0.11 1.13 9.67 96.66 11 11.00 0.11 1.25 9.67 106.32 12 12.00 0.11 1.36 9.67 115.99 13 13.00 0.11 1.47 9.67 125.65 14 14.00 0.11 1.59 9.67 135.32 15 15.00 0.11 1.70 9.67 144.99 16 16.00 0.00 1.70 -6.44 138.54 17 17.00 0.00 1.70 -6.44 132.10 18 18.00 0.00 1.70 -6.44 125.65 19 19.00 0.00 1.70 -6.44 119.21 20 20.00 0.00 1.70 -6.44 112.77 21 21.00 0.00 1.70 -6.44 106.32 22 22.00 0.00 1.70 -6.44 99.88 23 23.00 0.00 1.70 -6.44 93.44 24 24.00 0.00 1.70 -6.44 86.99 25 25.00 0.00 1.70 -6.44 80.55 26 26.00 0.00 1.70 -6.44 74.10 27 27.00 0.00 1.70 -6.44 67.66 28 28.00 0.00 1.70 -6.44 61.22 29 29.00 0.00 1.70 -6.44 54.77 30 30.00 0.00 1.70 -6.44 48.33 31 31.00 0.00 1.70 -6.44 41.88 32 32.00 0.00 1.70 -6.44 35.44 33 33.00 0.00 1.70 -6.44 29.00 34 34.00 0.00 1.70 -6.44 22.55 35 35.00 0.00 1.70 -6.44 16.11 36 36.00 0.00 1.70 -6.44 9.67 37 37.00 0.00 1.70 -6.44 3.22 38 37.50 0.00 1.70 -3.22 0.00 Rivanna Engineering&Surveying,PLC Page 15 (434)984-1599 Luxor Subdivision Stormwater Management Facility#3 Outlet Structure Report Type : Stand Pipe Name : SWM #3 Riser [RATING CURVE LIMIT] Minimum Elevation = 480.00 (ft) Maximum Elevation = 492.00 (ft) Elevation Increment = 0.50 (ft) [STAND PIPE INFORMATION] [ORIFICE INFORMATION] Diameter = 4.00 (ft) Crest Length = 12.57 (ft) Effective Crest Length = 10.07 ' (ft) Orifice Coefficient = 0.60 Fractional Open Area = 0.83 [ORIFICE EQUATION] I(t Q = Co*A( (2gh)/k)^0.5 [DEFINITIONS] Co = Orifice Coefficient A = Wetted Area, (sq ft) [WEIR INFORMATION] Crest Elevation = 491.50 (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 [WEIR INFORMATION] Structure Number : 1 Type : Rectangular Weir Suppressed [WEIR INFORMATION] Crest Length = 2.50 (ft) tS4` Crest Elevation = 490.00 (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 length Rivanna Engineering&Surveying, PLC Page 16 (434)984-1599 Luxor Subdivision Stormwater Management Facility#3 Outlet Structure Report SW #3 Riser [ORIFICE INFORMATION] Structure Number : 1 Type : Circular Orifice [OPTIONAL ORIFICE INFORMATION] Diameter = 1.00 (ft) Invert Elevation = 488.00 (ft) Orifice Coefficient = 0.60 Number of Openings = 2 [ORIFICE EQUATION] Q = Co*A( (2gh)/k)^0.5 [DEFINITIONS] Co = Orifice Coefficient A = Wetted Area, (cfs) k = 1 [CULVERT INFORMATION] Type : Circular Concrete - Square Edge with Headwall [OUTLET STRUCTURE INFORMATION] Diameter = 36.00 (in) Invert Elevation = 480.00 (ft) Pipe Length = 179.00 (ft) Slope = 0.08 Manning's n Value = 0.01 Orifice Coefficient = 0.60 Tailwater Elevation = 468.40 (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 17 (434)984-1599 Luxor Subdivision Stormwater Management Facility#3 Outlet Structure Report SWM #3 Riser [STAND PIPE STAGE VS. DISCHARGE] Elevation Stage Weirs Orifices Stand Pipe Culvert Total (ft) (ft) (cfs) (cfs) (cfs) (cfs) (cfs) 488.00 8.00 0.00 0.00 0.00 87.56 0.00 488.50 8.50 0.00 1.89 0.00 91.07 1.89 489.00 9.00 0.00 5.35 0.00 94.46 5.35 489.50 9.50 0.00 7.56 0.00 97.72 7.56 490.00 10.00 0.00 9.26 0.00 100.88 9.26 490.50 10.50 2.94 10.69 0.00 103.95 13.64 491.00 11.00 8.32 11.95 0.00 106.92 20.28 491.50 11.50 15.29 13.09 0.00 109.82 28.39 492.00 12.00 24.72 14.14 11.85 112.64 49.54 Rivanna Engineering&Surveying,PLC Page 18 (434)9841599 Luxor Subdivision Stormwater Management Facility#3 Reservoir Report Name: SWM Facility #3 [RATING CURVE LIMIT] Minimum Elevation = 480.00 (ft) Maximum Elevation = 496.00 (ft) Elevation Increment = 0.50 (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) 1 488.00 0.00 0.00 0.00 0.00 2 488.01 24363.00 12181.50 60.91 60.91 3 490.00 30597.00 27480.00 54822.60 54883.51 4 492.00 36748.00 33672.50 67345.00 122228.51 5 494.00 44802.00 40775.00 81550.00 203778.51 6 496.00 51306.00 48054.00 96108.00 299886.51 [DISCHARGE INFORMATION] Structure Number: 1 Type: Name: SWM #3 Riser [RESERVOIR STAGE STORAGE/DISCHARGE] Elevation Stage Area Storage Discharge (ft) (ft) (sq ft) (cu ft) (cfs) 488.00 8.00 0.00 0.00 0.00 488.50 8.50 25909.78 6477.45 1.89 489.00 9.00 27472.19 19822.94 5.35 489.50 9.50 29034.59 33949.63 7.56 490.00 10.00 30597.00 48857.53 9.26 490.50 10.50 32134.75 64540.47 13.64 491.00 11.00 33672.50 80992.28 20.28 491.50 11.50 35210.25 98212.97 28.39 492.00 12.00 36748.00 116202.53 49.54 492.50 12.50 38761.50 135079.91 81.55 493.00 13.00 40775.00 154964.03 115.02 493.50 13.50 42788.50 175854.91 120.71 494.00 14.00 44802.00 197752.53 123.28 494.50 14.50 46428.00 220560.03 125.80 495.00 15.00 48054.00 244180.53 128.28 495.50 15.50 49680.00 268614.03 130.70 496.00 16.00 51306.00 293860.53 133.08 Maximum Storage = 293860.53 (cu ft) Maximum Discharge = 133.08 (cfs) Rivanna Engineering&Surveying, PLC Page 19 (434)984-1599 Luxor Subdivision Stormwater Management Facility#3 Routed Hydrograph Report Name: SWM3, 2yr Type: Reservoir: Modified Puls [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 13.54 (cfs) Time to Peak (Tp) = 33.00 (min) Time of Base (Tb) = 1280.00 (min) Volume = 1.84 (ac-ft) Time Step = 1.00 (min) Peak Elevation = 490.49 (ft) Detention Time = NA [RESERVOIR STRUCTURE INFORMATION] Name = SWM Facility #3 Storage Type = User-Defined Area Maximum Storage = 293860.53 (cu ft) Maximum Discharge = 133.08 (cfs) [INFLOW HYDROGRAPH INFORMATION] Name = DA-3, Post 2yr Peak Flow (Qp) = 71.29 (cfs) Time to Peak (Tp) = 15.00 (min) Time of Base (Tb) = 37.50 (min) Volume = 1.84 (ac-ft) Flow Multiplier = 1.00 [EQUATION] (I1+I2) + (2(S1)/dt)-01 = (2(S2)/dt)+02 Where: I1 = Previous inflow I2 = Current inflow S1 = Previous storage S2 = Current storage dt = Time increment 01 = Previous outflow 02 = Current outflow A = (I1 + I2) B = (2 (S1) / dt) - 01 C = (2 (S2) / dt) + 02 [Computation of Reservoir Outflow Table of Modified Puls Method] Intv Time Inflow A B C Outflow Storage Elev (min) (cfs) (cfs) (cfs) (cfs) (cfs) (cu ft) (ft) 1 1.00 4.75 4.75 0.00 282.63 0.04 141.33 488.01 2 2.00 9.50 14.26 282.63 1125.60 0.16 562.88 488.04 3 3.00 14.26 23.76 1125.60 2519.21 0.37 1259.79 488.10 4 4.00 19.01 33.27 2519.21 4453.88 0.65 2227.26 488.17 5 5.00 23.76 42.77 4453.88 6920.22 1.01 3460.62 488.27 6 6.00 28.51 52.28 6920.22 9909.02 1.45 4955.23 488.38 7 7.00 33.27 61.78 9909.02 13411.66 1.95 6706.80 488.51 8 8.00 38.02 71.29 13411.66 17423.18 2.47 8712.82 488.58 9 9.00 42.77 80.79 17423.18 21938.67 3.05 10970.86 488.67 10 10.00 47.52 90.30 21938.67 26950.37 3.70 13477.03 488.76 Rivanna Engineering&Surveying,PLC Page 20 (434)984-1599 Luxor Subdivision Stormwater Management Facility#3 Routed Hydrograph Report SWM3, 2yr Intv Time Inflow A B C Outflow Storage Elev (min) (cfs) (cfs) (cfs) (cfs) (cfs) (cu ft) (ft) 11 11.00 52.28 99.80 26950.37 32450.61 4.41 16227.51 488.87 12 12.00 57.03 109.30 32450.61 38431.87 5.19 19218.53 488.98 13 13.00 61.78 118.81 38431.87 44903.01 5.76 22454.38 489.09 14 14.00 66.53 128.31 44903.01 51877.51 6.31 25941.91 489.22 15 15.00 71.29 137.82 51877.51 59354.31 6.89 29680.60 489.35 16 16.00 68.12 139.40 59354.31 66855.71 7.48 33431.59 489.48 17 17.00 64.95 133.07 66855.71 73916.32 7.90 36962.11 489.60 18 18.00 61.78 126.73 73916.32 80548.65 8.28 40278.46 489.71 19 19.00 58.61 120.39 80548.65 86756.90 8.64 43382.77 489.82 20 20.00 55.44 114.06 86756.90 92543.96 8.97 46276.46 489.91 21 21.00 52.28 107.72 92543.96 97911.68 9.29 48960.48 490.00 22 22.00 49.11 101.38 97911.68 102838.22 9.98 51424.10 490.08 23 23.00 45.94 95.05 102838.22 107305.99 10.60 53658.29 490.15 24 24.00 42.77 88.71 107305.99 111322.61 11.16 55666.88 490.22 25 25.00 39.60 82.37 111322.61 114895.56 11.66 57453.61 490.27 26 26.00 36.43 76.04 114895.56 118032.21 12.10 59022.15 490.32 27 27.00 33.27 69.70 118032.21 120739.80 12.47 60376.14 490.37 28 28.00 30.10 63.37 120739.80 123025.46 12.79 61519.13 490.40 29 29.00 26.93 57.03 123025.46 124896.19 13.05 62454.62 490.43 30 30.00 23.76 50.69 124896.19 126358.88 13.26 63186.07 490.46 31 31.00 20.59 44.36 126358.88 127420.30 13.41 63716.85 490.47 32 32.00 17.43 38.02 127420.30 128087.13 13.50 64050.31 490.48 33 33.00 14.26 31.68 128087.13 128365.89 13.54 64189.72 490.49 34 34.00 11.09 25.35 128365.89 128263.05 13.52 64138.29 490.49 35 35.00 7.92 19.01 128263.05 127784.93 13.46 63899.19 490.48 36 36.00 4.75 12.67 127784.93 126937.77 13.34 63475.55 490.47 37 37.00 1.58 6.34 126937.77 125727.69 13.17 62870.43 490.45 38 38.00 0.00 1.58 125727.69 124254.96 12.96 62133.96 490.42 39 39.00 0.00 0.00 124254.96 122712.44 12.75 61362.60 490.40 40 40.00 0.00 0.00 122712.44 121195.53 12.54 60604.03 490.37 41 41.00 0.00 0.00 121195.53 119703.80 12.33 59858.06 490.35 42 42.00 0.00 0.00 119703.80 118236.83 12.12 59124.48 490.33 43 43.00 0.00 0.00 118236.83 116794.22 11.92 58403.07 490.30 44 44.00 0.00 0.00 116794.22 115375.56 11.72 57693.64 490.28 45 45.00 0.00 0.00 115375.56 113980.46 11.53 56995.99 490.26 46 46.00 0.00 0.00 113980.46 112608.51 11.34 56309.92 490.24 47 47.00 0.00 0.00 112608.51 111259.34 11.15 55635.25 490.22 48 48.00 0.00 0.00 111259.34 109932.57 10.97 54971.77 490.19 49 49.00 0.00 0.00 109932.57 108627.83 10.78 54319.31 490.17 50 50.00 0.00 0.00 108627.83 107344.75 10.60 53677.68 490.15 51 51.00 0.00 0.00 107344.75 106082.97 10.43 53046.70 490.13 52 52.00 0.00 0.00 106082.97 104842.13 10.26 52426.19 490.11 53 53.00 0.00 0.00 104842.13 103621.90 10.08 51815.99 490.09 54 54.00 0.00 0.00 103621.90 102421.93 9.92 51215.92 490.08 55 55.00 0.00 0.00 102421.93 101241.88 9.75 50625.81 490.06 56 56.00 0.00 0.00 101241.88 100081.41 9.59 50045.50 490.04 57 57.00 0.00 0.00 100081.41 98940.22 9.43 49474.83 490.02 58 58.00 0.00 0.00 98940.22 97817.97 9.28 48913.62 490.00 59 59.00 0.00 0.00 97817.97 96709.38 9.20 48359.29 489.98 60 60.00 0.00 0.00 96709.38 95608.89 9.14 47809.01 489.96 61 61.00 0.00 0.00 95608.89 94515.89 9.08 47262.49 489.95 62 62.00 0.00 0.00 94515.89 93430.35 9.02 46719.68 489.93 63 63.00 0.00 0.00 93430.35 92352.21 8.95 46180.58 489.91 64 64.00 0.00 0.00 92352.21 91281.41 8.89 45645.15 489.89 65 65.00 0.00 0.00 91281.41 90217.91 8.83 45113.37 489.87 Rivanna Engineering&Surveying,PLC Page 21 (434)984-1599 Luxor Subdivision Stormwater Management Facility#3 Routed Hydrograph Report Name: SWM3, l0yr Type: Reservoir: Modified Puls [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 23.56 (cfs) Time to Peak (Tp) = 32.00 (min) Time of Base (Tb) = 1301.00 (min) Volume = 2.60 (ac-ft) Time Step = 1.00 (min) Peak Elevation = 491.20 (ft) Detention Time = NA [RESERVOIR STRUCTURE INFORMATION] Name = SWM Facility #3 Storage Type = User-Defined Area Maximum Storage = 293860.53 (cu ft) Maximum Discharge = 133.08 (cfs) [INFLOW HYDROGRAPH INFORMATION] Name = DA-3, Post l0yr Peak Flow (Qp) = 100.49 (cfs) Time to Peak (Tp) = 15.00 (min) Time of Base (Tb) = 37.50 (min) Volume = 2.60 (ac-ft) Flow Multiplier = 1.00 [EQUATION] (I1+I2) + (2(S1)/dt)-01 = (2(S2)/dt)+02 Where: I1 = Previous inflow I2 = Current inflow S1 = Previous storage S2 = Current storage dt = Time increment 01 = Previous outflow 02 = Current outflow A = (11 + I2) B = (2 (S1) / dt) - 01 C = (2 (S2) / dt) + 02 [Computation of Reservoir Outflow Table of Modified Puls Method] Intv Time Inflow A B C Outflow Storage Elev (min) (cfs) (cfs) (cfs) (cfs) (cfs) (cu ft) (ft) 1 1.00 6.70 6.70 0.00 398.40 0.06 199.23 488.02 2 2.00 13.40 20.10 398.40 1586.70 0.23 793.47 488.06 3 3.00 20.10 33.50 1586.70 3551.18 0.52 1775.85 488.14 4 4.00 26.80 46.89 3551.18 6278.38 0.92 3139.65 488.24 5 5.00 33.50 60.29 6278.38 9755.05 1.42 4878.23 488.38 6 6.00 40.20 73.69 9755.05 13969.19 2.02 6985.61 488.52 7 7.00 46.89 87.09 13969.19 18912.89 2.66 9457.78 488.61 8 8.00 53.59 100.49 18912.89 24577.98 3.40 12290.69 488.72 9 9.00 60.29 113.89 24577.98 30953.32 4.22 15478.77 488.84 10 10.00 66.99 127.28 30953.32 38027.96 5.14 19016.55 488.97 11 11.00 73.69 140.68 38027.96 45810.22 5.83 22908.03 489.11 Rivanna Engineering&Surveying,PLC Page 22 (434)984-1599 Luxor Subdivision Stormwater Management Facility#3 Routed Hydrograph Report SWM3, l0yr Intv Time Inflow A B C Outflow Storage Elev (min) (cfs) (cfs) (cfs) (cfs) (cfs) (cu ft) (ft) 12 12.00 80.39 154.08 45810.22 54314.87 6.50 27160.68 489.26 13 13.00 87.09 167.48 54314.87 63539.98 7.22 31773.60 489.42 14 14.00 93.79 180.88 63539.98 73486.07 7.88 36746.98 489.59 15 15.00 100.49 194.28 73486.07 84160.02 8.49 42084.25 489.77 16 16.00 96.02 196.51 84160.02 94894.75 9.10 47451.92 489.95 17 17.00 91.56 187.58 94894.75 104985.71 10.28 52497.99 490.12 18 18.00 87.09 178.64 104985.71 114391.30 11.59 57201.45 490.27 19 19.00 82.62 169.71 114391.30 123109.34 12.80 61561.07 490.41 20 20.00 78.16 160.78 123109.34 131143.39 14.05 65578.72 490.53 21 21.00 73.69 151.85 131143.39 138477.37 15.54 69246.45 490.64 22 22.00 69.22 142.92 138477.37 145106.37 16.87 72561.62 490.74 23 23.00 64.76 133.98 145106.37 151047.26 18.07 75532.67 490.83 24 24.00 60.29 125.05 151047.26 156316.52 19.14 78167.83 490.91 25 25.00 55.83 116.12 156316.52 160930.22 20.07 80475.14 490.98 26 26.00 51.36 107.19 160930.22 164898.12 20.97 82459.55 491.04 27 27.00 46.89 98.25 164898.12 168229.15 21.75 84125.45 491.09 28 28.00 42.43 89.32 168229.15 170939.02 22.39 85480.71 491.13 29 29.00 37.96 80.39 170939.02 173045.04 22.89 86533.97 491.16 30 30.00 33.50 71.46 173045.04 174564.05 23.25 87293.65 491.18 31 31.00 29.03 62.53 174564.05 175512.38 23.47 87767.92 491.20 32 32.00 24.56 53.59 175512.38 175905.95 23.56 87964.76 491.20 33 33.00 20.10 44.66 175905.95 175760.21 23.53 87891.87 491.20 34 34.00 15.63 35.73 175760.21 175090.19 23.37 87556.78 491.19 35 35.00 11.17 26.80 175090.19 173910.49 23.09 86966.79 491.17 36 36.00 6.70 17.86 173910.49 172235.32 22.70 86129.01 491.15 37 37.00 2.23 8.93 172235.32 170078.48 22.19 85050.34 491.12 38 38.00 0.00 2.23 170078.48 167585.49 21.60 83803.54 491.08 39 39.00 0.00 0.00 167585.49 165029.86 21.00 82525.43 491.04 40 40.00 0.00 0.00 165029.86 162545.45 20.42 81282.93 491.01 41 41.00 0.00 0.00 162545.45 160126.55 19.91 80073.23 490.97 42 42.00 0.00 0.00 160126.55 157766.69 19.43 78893.06 490.94 43 43.00 0.00 0.00 157766.69 155463.32 18.97 77741.15 490.90 44 44.00 0.00 0.00 155463.32 153215.10 18.51 76616.81 490.87 45 45.00 0.00 0.00 153215.10 151020.70 18.07 75519.38 490.83 46 46.00 0.00 0.00 151020.70 148878.83 17.64 74448.23 490.80 47 47.00 0.00 0.00 148878.83 146788.24 17.21 73402.73 490.77 48 48.00 0.00 0.00 146788.24 144747.70 16.80 72382.25 490.74 49 49.00 0.00 0.00 144747.70 142756.00 16.40 71386.20 490.71 50 50.00 0.00 0.00 142756.00 140811.99 16.01 70414.00 490.68 51 51.00 0.00 0.00 140811.99 138914.51 15.62 69465.07 490.65 52 52.00 0.00 0.00 138914.51 137062.46 15.25 68538.85 490.62 53 53.00 0.00 0.00 137062.46 135254.74 14.88 67634.81 490.59 54 54.00 0.00 0.00 135254.74 133490.31 14.53 66752.42 490.57 55 55.00 0.00 0.00 133490.31 131768.11 14.18 65891.14 490.54 56 56.00 0.00 0.00 131768.11 130087.14 13.84 65050.49 490.52 57 57.00 0.00 0.00 130087.14 128444.07 13.55 64228.81 490.49 58 58.00 0.00 0.00 128444.07 126832.00 13.32 63422.66 490.46 59 59.00 0.00 0.00 126832.00 125246.69 13.10 62629.90 490.44 60 60.00 0.00 0.00 125246.69 123687.70 12.88 61850.29 490.41 61 61.00 0.00 0.00 123687.70 122154.60 12.67 61083.63 490.39 62 62.00 0.00 0.00 122154.60 120646.95 12.46 60329.70 490.37 63 63.00 0.00 0.00 120646.95 119164.32 12.25 59588.29 490.34 64 64.00 0.00 0.00 119164.32 117706.32 12.05 58859.18 490.32 65 65.00 0.00 0.00 117706.32 116272.51 11.85 58142.18 490.30 Rivanna Engineering&Surveying,PLC Page 23 (434)984-1599 Luxor Subdivision Stormwater Management Facility#3 Routed Hydrograph Report Name: SWM3, 1O0yr Type: Reservoir: Modified Puls [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 50.63 (cfs) Time to Peak (Tp) = 30.00 (min) Time of Base (Tb) = 1315.00 (min) Volume = 3.75 (ac-ft) Time Step = 1.00 (min) Peak Elevation = 492.02 (ft) Detention Time = NA [RESERVOIR STRUCTURE INFORMATION] Name = SWM Facility #3 Storage Type = User-Defined Area Maximum Storage = 293860.53 (cu ft) Maximum Discharge = 133.08 (cfs) [INFLOW HYDROGRAPH INFORMATION] Name = DA-3, Post 100yr Peak Flow (Qp) = 144.99 (cfs) Time to Peak (Tp) = 15.00 (min) Time of Base (Tb) = 37.50 (min) Volume = 3.75 (ac-ft) Flow Multiplier = 1.00 [EQUATION] (I1+I2) + (2(S1)/dt)-01 = (2(S2)/dt)+02 Where: I1 = Previous inflow I2 = Current inflow Si = Previous storage S2 = Current storage dt = Time increment 01 = Previous outflow 02 = Current outflow A = (I1 + I2) B = (2 (S1) / dt) - 01 C = (2 (S2) / dt) + 02 [Computation of Reservoir Outflow Table of Modified Puls Method] Intv Time Inflow A B C Outflow Storage Elev (min) (cfs) (cfs) (cfs) (cfs) (cfs) (cu ft) (ft) 1 1.00 9.67 9.67 0.00 574.83 0.08 287.46 488.02 2 2.00 19.33 29.00 574.83 2289.33 0.33 1144.83 488.09 3 3.00 29.00 48.33 2289.33 5123.74 0.75 2562.24 488.20 4 4.00 38.66 67.66 5123.74 9058.61 1.32 4529.97 488.35 5 5.00 48.33 86.99 9058.61 14075.96 2.04 7039.00 488.52 6 6.00 57.99 106.32 14075.96 20163.00 2.82 10082.91 488.64 7 7.00 67.66 125.65 20163.00 27307.00 3.75 13655.37 488.77 8 8.00 77.33 144.99 27307.00 35491.65 4.81 17748.23 488.92 9 9.00 86.99 164.32 35491.65 44716.62 5.74 22361.18 489.09 10 10.00 96.66 183.65 44716.62 54997.15 6.55 27501.85 489.27 11 11.00 106.32 202.98 54997.15 66335.82 7.44 33171.63 489.47 Rivanna Engineering&Surveying,PLC Page 24 (434)984-1599 Luxor Subdivision Stormwater Management Facility#3 Routed Hydrograph Report SWM3, 100yr Intv Time Inflow A B C Outflow Storage Elev (min) (cfs) (cfs) (cfs) (cfs) (cfs) (cu ft) (ft) 12 12.00 115.99 222.31 66335.82 78736.79 8.18 39372.49 489.68 13 13.00 125.65 241.64 78736.79 92207.17 8.95 46108.06 489.91 14 14.00 135.32 260.97 92207.17 106696.50 10.51 53353.51 490.14 15 15.00 144.99 280.31 106696.50 122121.93 12.67 61067.30 490.39 16 16.00 138.54 283.53 122121.93 137451.29 15.33 68733.31 490.63 17 17.00 132.10 270.64 137451.29 151675.10 18.20 75846.65 490.84 18 18.00 125.65 257.75 151675.10 164788.84 20.94 82404.89 491.04 19 19.00 119.21 244.87 164788.84 176794.97 23.77 88409.37 491.22 20 20.00 112.77 231.98 176794.97 187704.27 26.34 93865.30 491.37 21 21.00 106.32 219.09 187704.27 197523.41 29.05 98776.23 491.52 22 22.00 99.88 206.20 197523.41 206101.58 34.10 103067.84 491.63 23 23.00 93.44 193.31 206101.58 213348.68 38.36 106693.52 491.74 24 24.00 86.99 180.43 213348.68 219355.42 41.89 109698.66 491.82 25 25.00 80.55 167.54 219355.42 224206.32 44.75 112125.54 491.89 26 26.00 74.10 154.65 224206.32 227980.17 46.97 114013.57 491.94 27 27.00 67.66 141.76 227980.17 230750.36 48.60 115399.48 491.98 28 28.00 61.22 128.88 230750.36 232581.83 49.73 116315.78 492.00 29 29.00 54.77 115.99 232581.83 233524.21 50.53 116787.37 492.02 30 30.00 48.33 103.10 233524.21 233640.16 50.63 116845.39 492.02 31 31.00 41.88 90.21 233640.16 233009.67 50.10 116529.88 492.01 32 32.00 35.44 77.33 233009.67 231695.05 49.15 115872.10 491.99 33 33.00 29.00 64.44 231695.05 229733.24 48.00 114890.62 491.96 34 34.00 22.55 51.55 229733.24 227158.66 46.49 113602.58 491.93 35 35.00 16.11 38.66 227158.66 224013.07 44.63 112028.85 491.88 36 36.00 9.67 25.78 224013.07 220335.38 42.47 110188.92 491.83 37 37.00 3.22 12.89 220335.38 216161.85 40.02 108100.93 491.77 38 38.00 0.00 3.22 216161.85 211712.89 37.40 105875.14 491.71 39 39.00 0.00 0.00 211712.89 207380.51 34.85 103707.68 491.65 40 40.00 0.00 0.00 207380.51 203343.38 32.48 101687.93 491.60 41 41.00 0.00 0.00 203343.38 199581.38 30.26 99805.82 491.54 42 42.00 0.00 0.00 199581.38 196068.93 28.31 98048.62 491.50 43 43.00 0.00 0.00 196068.93 192719.68 27.52 96373.60 491.45 44 44.00 0.00 0.00 192719.68 189463.75 26.76 94745.25 491.40 45 45.00 0.00 0.00 189463.75 186298.54 26.01 93162.27 491.35 46 46.00 0.00 0.00 186298.54 183221.51 25.29 91623.40 491.31 47 47.00 0.00 0.00 183221.51 180230.23 24.58 90127.40 491.27 48 48.00 0.00 0.00 180230.23 177322.29 23.90 88673.09 491.22 49 49.00 0.00 0.00 177322.29 174495.37 23.23 87259.30 491.18 50 50.00 0.00 0.00 174495.37 171747.22 22.58 85884.90 491.14 51 51.00 0.00 0.00 171747.22 169075.64 21.95 84548.80 491.10 52 52.00 0.00 0.00 169075.64 166478.50 21.34 83249.92 491.07 53 53.00 0.00 0.00 166478.50 163953.72 20.75 81987.23 491.03 54 54.00 0.00 0.00 163953.72 161498.35 20.18 80759.27 490.99 55 55.00 0.00 0.00 161498.35 159105.65 19.70 79562.68 490.96 56 56.00 0.00 0.00 159105.65 156770.23 19.23 78394.73 490.92 57 57.00 0.00 0.00 156770.23 154490.72 18.77 77254.75 490.89 58 58.00 0.00 0.00 154490.72 152265.78 18.32 76142.05 490.85 59 59.00 0.00 0.00 152265.78 150094.11 17.88 75056.00 490.82 60 60.00 0.00 0.00 150094.11 147974.42 17.45 73995.94 490.79 61 61.00 0.00 0.00 147974.42 145905.48 17.04 72961.26 490.76 62 62.00 0.00 0.00 145905.48 143886.07 16.63 71951.35 490.73 63 63.00 0.00 0.00 143886.07 141915.00 16.23 70965.62 490.70 64 64.00 0.00 0.00 141915.00 139991.12 15.84 70003.48 490.67 65 65.00 0.00 0.00 139991.12 138113.30 15.46 69064.38 490.64 66 66.00 0.00 0.00 138113.30 136280.43 15.09 68147.76 490.61 Rivanna Engineering&Surveying,PLC Page 25 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Pre-Development Hydrograph Report Name: DA-2, 2yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 75.35 (cfs) Time to Peak (Tp) = 30.00 (min) Time of Base (Tb) = 75.00 (min) Volume = 3.89 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 3.89 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef Fontana 38.20 0 0.30 Ashcroft 31.00 0 0.30 Westminster 9.10 0 0.30 Luxor 33.70 0 0.30 Overall Approximation 112.00 NA 0.30 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 30.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 1.11 (in) Return Period = 2 (yr) Storm Duration = 0.50 (hr) [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.04 0.00 2.51 2 2.00 0.04 0.07 2.51 5.02 3 3.00 0.04 0.11 2.51 7.53 4 4.00 0.04 0.15 2.51 10.05 5 5.00 0.04 0.19 2.51 12.56 6 6.00 0.04 0.22 2.51 15.07 7 7.00 0.04 0.26 2.51 17.58 8 8.00 0.04 0.30 2.51 20.09 9 9.00 0.04 0.33 2.51 22.60 10 10.00 0.04 0.37 2.51 25.12 11 11.00 0.04 0.41 2.51 27.63 12 12.00 0.04 0.44 2.51 30.14 13 13.00 0.04 0.48 2.51 32.65 Rivanna Engineering&Surveying,PLC Page 26 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Pre-Development Hydrograph Report DA-2, 2yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 14 14.00 0.04 0.52 2.51 35.16 15 15.00 0.04 0.56 2.51 37.67 16 16.00 0.04 0.59 2.51 40.19 17 17.00 0.04 0.63 2.51 42.70 18 18.00 0.04 0.67 2.51 45.21 19 19.00 0.04 0.70 2.51 47.72 20 20.00 0.04 0.74 2.51 50.23 21 21.00 0.04 0.78 2.51 52.74 22 22.00 0.04 0.82 2.51 55.25 23 23.00 0.04 0.85 2.51 57.77 24 24.00 0.04 0.89 2.51 60.28 25 25.00 0.04 0.93 2.51 62.79 26 26.00 0.04 0.96 2.51 65.30 27 27.00 0.04 1.00 2.51 67.81 28 28.00 0.04 1.04 2.51 70.32 29 29.00 0.04 1.07 2.51 72.84 30 30.00 0.04 1.11 2.51 75.35 31 31.00 0.00 1.11 -1.67 73.67 32 32.00 0.00 1.11 -1.67 72.00 33 33.00 0.00 1.11 -1.67 70.32 34 34.00 0.00 1.11 -1.67 68.65 35 35.00 0.00 1.11 -1.67 66.98 36 36.00 0.00 1.11 -1.67 65.30 37 37.00 0.00 1.11 -1.67 63.63 38 38.00 0.00 1.11 -1.67 61.95 39 39.00 0.00 1.11 -1.67 60.28 40 40.00 0.00 1.11 -1.67 58.60 41 41.00 0.00 1.11 -1.67 56.93 42 42.00 0.00 1.11 -1.67 55.25 43 43.00 0.00 1.11 -1.67 53.58 44 44.00 0.00 1.11 -1.67 51.91 45 45.00 0.00 1.11 -1.67 50.23 46 46.00 0.00 1.11 -1.67 48.56 47 47.00 0.00 1.11 -1.67 46.88 48 48.00 0.00 1.11 -1.67 45.21 49 49.00 0.00 1.11 -1.67 43.53 50 50.00 0.00 1.11 -1.67 41.86 51 51.00 0.00 1.11 -1.67 40.19 52 52.00 0.00 1.11 -1.67 38.51 53 53.00 0.00 1.11 -1.67 36.84 54 54.00 0.00 1.11 -1.67 35.16 55 55.00 0.00 1.11 -1.67 33.49 56 56.00 0.00 1.11 -1.67 31.81 57 57.00 0.00 1.11 -1.67 30.14 58 58.00 0.00 1.11 -1.67 28.46 59 59.00 0.00 1.11 -1.67 26.79 60 60.00 0.00 1.11 -1.67 25.12 61 61.00 0.00 1.11 -1.67 23.44 62 62.00 0.00 1.11 -1.67 21.77 63 63.00 0.00 1.11 -1.67 20.09 64 64.00 0.00 1.11 -1.67 18.42 65 65.00 0.00 1.11 -1.67 16.74 66 66.00 0.00 1.11 -1.67 15.07 Rivanna Engineering&Surveying,PLC Page 27 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Pre-Development Hydrograph Report Name: DA-2, l0yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 109.77 (cfs) Time to Peak (Tp) = 30.00 (min) Time of Base (Tb) = 75.00 (min) Volume = 5.67 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 5.67 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef Fontana 38.20 0 0.30 Ashcroft v- 31.00 0 0.30 Westminster v" 9.10 0 0.30 Luxor L. 33.70 0 0.30 isicftt �ics,_,A ,.,rc,AOu Overall Approximation 112.00 NA 0.30 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 30.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 1.62 (in) Return Period = User Defined (yr) Storm Duration = 0.50 (hr) [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.05 0.00 3.66 2 2.00 0.05 0.11 3.66 7.32 3 3.00 0.05 0.16 3.66 10.98 4 4.00 0.05 0.22 3.66 14.64 5 5.00 0.05 0.27 3.66 18.30 6 6.00 0.05 0.32 3.66 21.95 7 7.00 0.05 0.38 3.66 25.61 8 8.00 0.05 0.43 3.66 29.27 9 9.00 0.05 0.49 3.66 32.93 10 10.00 0.05 0.54 3.66 36.59 11 11.00 0.05 0.59 3.66 40.25 12 12.00 0.05 0.65 3.66 43.91 13 13.00 0.05 0.70 3.66 47.57 Rivanna Engineering&Surveying, PLC Page 28 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Pre-Development Hydrograph Report DA-2, l0yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 14 14.00 0.05 0.76 3.66 51.23 15 15.00 0.05 0.81 3.66 54.89 16 16.00 0.05 0.86 3.66 58.55 17 17.00 0.05 0.92 3.66 62.20 18 18.00 0.05 0.97 3.66 65.86 19 19.00 0.05 1.03 3.66 69.52 20 20.00 0.05 1.08 3.66 73.18 21 21.00 0.05 1.13 3.66 76.84 22 22.00 0.05 1.19 3.66 80.50 23 23.00 0.05 1.24 3.66 84.16 24 24.00 0.05 1.30 3.66 87.82 25 25.00 0.05 1.35 3.66 91.48 26 26.00 0.05 1.40 3.66 95.14 27 27.00 0.05 1.46 3.66 98.79 28 28.00 0.05 1.51 3.66 102.45 29 29.00 0.05 1.57 3.66 106.11 30 30.00 0.05 1.62 3.66 109.77 31 31.00 0.00 1.62 -2.44 107.33 32 32.00 0.00 1.62 -2.44 104.89 33 33.00 0.00 1.62 -2.44 102.45 34 34.00 0.00 1.62 -2.44 100.01 35 35.00 0.00 1.62 -2.44 97.58 36 36.00 0.00 1.62 -2.44 95.14 37 37.00 0.00 1.62 -2.44 92.70 38 38.00 0.00 1.62 -2.44 90.26 39 39.00 0.00 1.62 -2.44 87.82 40 40.00 0.00 1.62 -2.44 85.38 41 41.00 0.00 1.62 -2.44 82.94 42 42.00 0.00 1.62 -2.44 80.50 43 43.00 0.00 1.62 -2.44 78.06 44 44.00 0.00 1.62 -2.44 75.62 45 45.00 0.00 1.62 -2.44 73.18 46 46.00 0.00 1.62 -2.44 70.74 47 47.00 0.00 1.62 -2.44 68.30 48 48.00 0.00 1.62 -2.44 65.86 49 49.00 0.00 1.62 -2.44 63.42 50 50.00 0.00 1.62 -2.44 60.98 51 51.00 0.00 1.62 -2.44 58.55 52 52.00 0.00 1.62 -2.44 56.11 53 53.00 0.00 1.62 -2.44 53.67 54 54.00 0.00 1.62 -2.44 51.23 55 55.00 0.00 1.62 -2.44 48.79 56 56.00 0.00 1.62 -2.44 46.35 57 57.00 0.00 1.62 -2.44 43.91 58 58.00 0.00 1.62 -2.44 41.47 59 59.00 0.00 1.62 -2.44 39.03 60 60.00 0.00 1.62 -2.44 36.59 61 61.00 0.00 1.62 -2.44 34.15 62 62.00 0.00 1.62 -2.44 31.71 63 63.00 0.00 1.62 -2.44 29.27 64 64.00 0.00 1.62 -2.44 26.83 65 65.00 0.00 1.62 -2.44 24.39 66 66.00 0.00 1.62 -2.44 21.95 Rivanna Engineering&Surveying,PLC Page 29 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Pre-Development Hydrograph Report Name: DA-2, 1O0yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 161.44 (cfs) Time to Peak (Tp) = 30.00 (min) Time of Base (Tb) = 75.00 (min) Volume = 8.34 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 8.34 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef Fontana 38.20 0 0.30 Ashcroft 31.00 0 0.30 Westminster 9.10 0 0.30 Luxor 33.70 0 0.30 Overall Approximation 112.00 NA 0.30 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 30.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 2.38 (in) Return Period = 100 (yr) Storm Duration = 0.50 (hr) [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.08 0.00 5.38 2 2.00 0.08 0.16 5.38 10.76 3 3.00 0.08 0.24 5.38 16.14 4 4.00 0.08 0.32 5.38 21.53 5 5.00 0.08 0.40 5.38 26.91 6 6.00 0.08 0.48 5.38 32.29 7 7.00 0.08 0.56 5.38 37.67 8 8.00 0.08 0.64 5.38 43.05 9 9.00 0.08 0.71 5.38 48.43 10 10.00 0.08 0.79 5.38 53.81 11 11.00 0.08 0.87 5.38 59.20 12 12.00 0.08 0.95 5.38 64.58 13 13.00 0.08 1.03 5.38 69.96 Rivanna Engineering&Surveying,PLC Page 30 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Pre-Development Hydrograph Report DA-2, 1O0yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 14 14.00 0.08 1.11 5.38 75.34 15 15.00 0.08 1.19 5.38 80.72 16 16.00 0.08 1.27 5.38 86.10 17 17.00 0.08 1.35 5.38 91.49 18 18.00 0.08 1.43 5.38 96.87 19 19.00 0.08 1.51 5.38 102.25 20 20.00 0.08 1.59 5.38 107.63 21 21.00 0.08 1.67 5.38 113.01 22 22.00 0.08 1.75 5.38 118.39 23 23.00 0.08 1.83 5.38 123.77 24 24.00 0.08 1.91 5.38 129.16 25 25.00 0.08 1.99 5.38 134.54 26 26.00 0.08 2.06 5.38 139.92 27 27.00 0.08 2.14 5.38 145.30 28 28.00 0.08 2.22 5.38 150.68 29 29.00 0.08 2.30 5.38 156.06 30 30.00 0.08 2.38 5.38 161.44 31 31.00 0.00 2.38 -3.59 157.86 32 32.00 0.00 2.38 -3.59 154.27 33 33.00 0.00 2.38 -3.59 150.68 34 34.00 0.00 2.38 -3.59 147.09 35 35.00 0.00 2.38 -3.59 143.51 36 36.00 0.00 2.38 -3.59 139.92 37 37.00 0.00 2.38 -3.59 136.33 38 38.00 0.00 2.38 -3.59 132.74 39 39.00 0.00 2.38 -3.59 129.16 40 40.00 0.00 2.38 -3.59 125.57 41 41.00 0.00 2.38 -3.59 121.98 42 42.00 0.00 2.38 -3.59 118.39 43 43.00 0.00 2.38 -3.59 114.80 44 44.00 0.00 2.38 -3.59 111.22 45 45.00 0.00 2.38 -3.59 107.63 46 46.00 0.00 2.38 -3.59 104.04 47 47.00 0.00 2.38 -3.59 100.45 48 48.00 0.00 2.38 -3.59 96.87 49 49.00 0.00 2.38 -3.59 93.28 50 50.00 0.00 2.38 -3.59 89.69 51 51.00 0.00 2.38 -3.59 86.10 52 52.00 0.00 2.38 -3.59 82.52 53 53.00 0.00 2.38 -3.59 78.93 54 54.00 0.00 2.38 -3.59 75.34 55 55.00 0.00 2.38 -3.59 71.75 56 56.00 0.00 2.38 -3.59 68.17 57 57.00 0.00 2.38 -3.59 64.58 58 58.00 0.00 2.38 -3.59 60.99 59 59.00 0.00 2.38 -3.59 57.40 60 60.00 0.00 2.38 -3.59 53.81 61 61.00 0.00 2.38 -3.59 50.23 62 62.00 0.00 2.38 -3.59 46.64 63 63.00 0.00 2.38 -3.59 43.05 64 64.00 0.00 2.38 -3.59 39.46 65 65.00 0.00 2.38 -3.59 35.88 66 66.00 0.00 2.38 -3.59 32.29 Rivanna Engineering&Surveying,PLC Page 31 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Post-Development Hydrograph Report Name: DA-2, Post 2yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 133.22 (cfs) Time to Peak (Tp) = 25.00 (min) Time of Base (Tb) = 62.50 (min) Volume = 5.74 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 5.74 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef Fontana (1/2 acre Lots) 36.40 0 0.50 Townhomes 18.10 0 0.75 Woods/Brush 25.60 0 0.30 Future 1/2 acre lots 5.20 0 0.50 Undeveloped 4.70 0 0.30 Commercial 11.30 0 0.85 Overall Approximation 101.30 NA 0.52 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 25.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 1.04 (in) Return Period = 2 (yr) Storm Duration = 0.42 (hr) [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.04 0.00 5.33 2 2.00 0.04 0.08 5.33 10.66 3 3.00 0.04 0.12 5.33 15.99 4 4.00 0.04 0.17 5.33 21.32 5 5.00 0.04 0.21 5.33 26.64 6 6.00 0.04 0.25 5.33 31.97 7 7.00 0.04 0.29 5.33 37.30 8 8.00 0.04 0.33 5.33 42.63 9 9.00 0.04 0.37 5.33 47.96 10 10.00 0.04 0.41 5.33 53.29 11 11.00 0.04 0.46 5.33 58.62 Rivanna Engineering&Surveying,PLC Page 32 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Post-Development Hydrograph Report DA-2, Post 2yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 12 12.00 0.04 0.50 5.33 63.95 13 13.00 0.04 0.54 5.33 69.28 14 14.00 0.04 0.58 5.33 74.61 15 15.00 0.04 0.62 5.33 79.93 16 16.00 0.04 0.66 5.33 85.26 17 17.00 0.04 0.71 5.33 90.59 18 18.00 0.04 0.75 5.33 95.92 19 19.00 0.04 0.79 5.33 101.25 20 20.00 0.04 0.83 5.33 106.58 21 21.00 0.04 0.87 5.33 111.91 22 22.00 0.04 0.91 5.33 117.24 23 23.00 0.04 0.95 5.33 122.57 24 24.00 0.04 1.00 5.33 127.90 25 25.00 0.04 1.04 5.33 133.22 26 26.00 0.00 1.04 -3.55 129.67 27 27.00 0.00 1.04 -3.55 126.12 28 28.00 0.00 1.04 -3.55 122.57 29 29.00 0.00 1.04 -3.55 119.01 30 30.00 0.00 1.04 -3.55 115.46 31 31.00 0.00 1.04 -3.55 111.91 32 32.00 0.00 1.04 -3.55 108.36 33 33.00 0.00 1.04 -3.55 104.80 34 34.00 0.00 1.04 -3.55 101.25 35 35.00 0.00 1.04 -3.55 97.70 36 36.00 0.00 1.04 -3.55 94.15 37 37.00 0.00 1.04 -3.55 90.59 38 38.00 0.00 1.04 -3.55 87.04 39 39.00 0.00 1.04 -3.55 83.49 40 40.00 0.00 1.04 -3.55 79.93 41 41.00 0.00 1.04 -3.55 76.38 42 42.00 0.00 1.04 -3.55 72.83 43 43.00 0.00 1.04 -3.55 69.28 44 44.00 0.00 1.04 -3.55 65.72 45 45.00 0.00 1.04 -3.55 62.17 46 46.00 0.00 1.04 -3.55 58.62 47 47.00 0.00 1.04 -3.55 55.07 48 48.00 0.00 1.04 -3.55 51.51 49 49.00 0.00 1.04 -3.55 47.96 50 50.00 0.00 1.04 -3.55 44.41 51 51.00 0.00 1.04 -3.55 40.86 52 52.00 0.00 1.04 -3.55 37.30 53 53.00 0.00 1.04 -3.55 33.75 54 54.00 0.00 1.04 -3.55 30.20 55 55.00 0.00 1.04 -3.55 26.64 56 56.00 0.00 1.04 -3.55 23.09 57 57.00 0.00 1.04 -3.55 19.54 58 58.00 0.00 1.04 -3.55 15.99 59 59.00 0.00 1.04 -3.55 12.43 60 60.00 0.00 1.04 -3.55 8.88 61 61.00 0.00 1.04 -3.55 5.33 62 62.00 0.00 1.04 -3.55 1.78 63 62.50 0.00 1.04 -1.78 0.00 Rivanna Engineering&Surveying,PLC Page 33 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Post-Development Hydrograph Report Name: DA-2, Post l0yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 192.75 (cfs) Time to Peak (Tp) = 25.00 (min) Time of Base (Tb) = 62.50 (min) Volume = 8.30 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 8.30 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef Fontana (1/2 acre Lots) 36.40 0 0.50 Townhomes 18.10 0 0.75 Woods/Brush 25.60 0 0.30 Future 1/2 acre lots 5.20 0 0.50 Undeveloped 4.70 0 0.30 Commercial 11.30 0 0.85 Overall Approximation 101.30 NA 0.52 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 25.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 1.50 (in) Return Period = User Defined (yr) Storm Duration = 0.42 (hr) [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.06 0.00 7.71 2 2.00 0.06 0.12 7.71 15.42 3 3.00 0.06 0.18 7.71 23.13 4 4.00 0.06 0.24 7.71 30.84 5 5.00 0.06 0.30 7.71 38.55 6 6.00 0.06 0.36 7.71 46.26 7 7.00 0.06 0.42 7.71 53.97 8 8.00 0.06 0.48 7.71 61.68 9 9.00 0.06 0.54 7.71 69.39 10 10.00 0.06 0.60 7.71 77.10 11 11.00 0.06 0.66 7.71 84.81 Rivanna Engineering&Surveying,PLC Page 34 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Post-Development Hydrograph Report DA-2, Post 10yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 12 12.00 0.06 0.72 7.71 92.52 13 13.00 0.06 0.78 7.71 100.23 14 14.00 0.06 0.84 7.71 107.94 15 15.00 0.06 0.90 7.71 115.65 16 16.00 0.06 0.96 7.71 123.36 17 17.00 0.06 1.02 7.71 131.07 18 18.00 0.06 1.08 7.71 138.78 19 19.00 0.06 1.14 7.71 146.49 20 20.00 0.06 1.20 7.71 154.20 21 21.00 0.06 1.26 7.71 161.91 22 22.00 0.06 1.32 7.71 169.62 23 23.00 0.06 1.38 7.71 177.33 24 24.00 0.06 1.44 7.71 185.04 25 25.00 0.06 1.50 7.71 192.75 26 26.00 0.00 1.50 -5.14 187.61 27 27.00 0.00 1.50 -5.14 182.47 28 28.00 0.00 1.50 -5.14 177.33 29 29.00 0.00 1.50 -5.14 172.19 30 30.00 0.00 1.50 -5.14 167.05 31 31.00 0.00 1.50 -5.14 161.91 32 32.00 0.00 1.50 -5.14 156.77 33 33.00 0.00 1.50 -5.14 151.63 34 34.00 0.00 1.50 -5.14 146.49 35 35.00 0.00 1.50 -5.14 141.35 36 36.00 0.00 1.50 -5.14 136.21 37 37.00 0.00 1.50 -5.14 131.07 38 38.00 0.00 1.50 -5.14 125.93 39 39.00 0.00 1.50 -5.14 120.79 40 40.00 0.00 1.50 -5.14 115.65 41 41.00 0.00 1.50 -5.14 110.51 42 42.00 0.00 1.50 -5.14 105.37 43 43.00 0.00 1.50 -5.14 100.23 44 44.00 0.00 1.50 -5.14 95.09 45 45.00 0.00 1.50 -5.14 89.95 46 46.00 0.00 1.50 -5.14 84.81 47 47.00 0.00 1.50 -5.14 79.67 48 48.00 0.00 1.50 -5.14 74.53 49 49.00 0.00 1.50 -5.14 69.39 50 50.00 0.00 1.50 -5.14 64.25 51 51.00 0.00 1.50 -5.14 59.11 52 52.00 0.00 1.50 -5.14 53.97 53 53.00 0.00 1.50 -5.14 48.83 54 54.00 0.00 1.50 -5.14 43.69 55 55.00 0.00 1.50 -5.14 38.55 56 56.00 0.00 1.50 -5.14 33.41 57 57.00 0.00 1.50 -5.14 28.27 58 58.00 0.00 1.50 -5.14 23.13 59 59.00 0.00 1.50 -5.14 17.99 60 60.00 0.00 1.50 -5.14 12.85 61 61.00 0.00 1.50 -5.14 7.71 62 62.00 0.00 1.50 -5.14 2.57 63 62.50 0.00 1.50 -2.57 0.00 Rivanna Engineering&Surveying,PLC Page 35 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Post-Development Hydrograph Report Name: DA-2, Post 100yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 282.39 (cfs) Time to Peak (Tp) = 25.00 (min) Time of Base (Tb) = 62.50 (min) Volume = 12.16 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 12.16 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef Fontana (1/2 acre Lots) 36.40 0 0.50 Townhomes 18.10 0 0.75 Woods/Brush 25.60 0 0.30 Future 1/2 acre lots 5.20 0 0.50 q Undeveloped 4.70 0 � � s�r+ ' " . i, ' /1et.e� Commercial 11.30 0 0.85 Overall Approximation 101.30 NA 0.52 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 25.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 2.20 (in) Return Period = 100 (yr) Storm Duration = 0.42 (hr) [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.09 0.00 11.30 2 2.00 0.09 0.18 11.30 22.59 3 3.00 0.09 0.26 11.30 33.89 4 4.00 0.09 0.35 11.30 45.18 5 5.00 0.09 0.44 11.30 56.48 6 6.00 0.09 0.53 11.30 67.77 7 7.00 0.09 0.62 11.30 79.07 8 8.00 0.09 0.70 11.30 90.37 9 9.00 0.09 0.79 11.30 101.66 10 10.00 0.09 0.88 11.30 112.96 11 11.00 0.09 0.97 11.30 124.25 Rivanna Engineering&Surveying,PLC Page 36 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Post-Development Hydrograph Report DA-2, Post 100yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 12 12.00 0.09 1.06 11.30 135.55 13 13.00 0.09 1.14 11.30 146.85 14 14.00 0.09 1.23 11.30 158.14 15 15.00 0.09 1.32 11.30 169.44 16 16.00 0.09 1.41 11.30 180.73 17 17.00 0.09 1.50 11.30 192.03 18 18.00 0.09 1.58 11.30 203.32 19 19.00 0.09 1.67 11.30 214.62 20 20.00 0.09 1.76 11.30 225.92 21 21.00 0.09 1.85 11.30 237.21 22 22.00 0.09 1.93 11.30 248.51 23 23.00 0.09 2.02 11.30 259.80 24 24.00 0.09 2.11 11.30 271.10 25 25.00 0.09 2.20 11.30 282.39 26 26.00 0.00 2.20 -7.53 274.86 27 27.00 0.00 2.20 -7.53 267.33 28 28.00 0.00 2.20 -7.53 259.80 29 29.00 0.00 2.20 -7.53 252.27 30 30.00 0.00 2.20 -7.53 244.74 31 31.00 0.00 2.20 -7.53 237.21 32 32.00 0.00 2.20 -7.53 229.68 33 33.00 0.00 2.20 -7.53 222.15 34 34.00 0.00 2.20 -7.53 214.62 35 35.00 0.00 2.20 -7.53 207.09 36 36.00 0.00 2.20 -7.53 199.56 37 37.00 0.00 2.20 -7.53 192.03 38 38.00 0.00 2.20 -7.53 184.50 39 39.00 0.00 2.20 -7.53 176.97 40 40.00 0.00 2.20 -7.53 169.44 41 41.00 0.00 2.20 -7.53 161.91 42 42.00 0.00 2.20 -7.53 154.38 43 43.00 0.00 2.20 -7.53 146.85 44 44.00 0.00 2.20 -7.53 139.31 45 45.00 0.00 2.20 -7.53 131.78 46 46.00 0.00 2.20 -7.53 124.25 47 47.00 0.00 2.20 -7.53 116.72 48 48.00 0.00 2.20 -7.53 109.19 49 49.00 0.00 2.20 -7.53 101.66 50 50.00 0.00 2.20 -7.53 94.13 51 51.00 0.00 2.20 -7.53 86.60 52 52.00 0.00 2.20 -7.53 79.07 53 53.00 0.00 2.20 -7.53 71.54 54 54.00 0.00 2.20 -7.53 64.01 55 55.00 0.00 2.20 -7.53 56.48 56 56.00 0.00 2.20 -7.53 48.95 57 57.00 0.00 2.20 -7.53 41.42 58 58.00 0.00 2.20 -7.53 33.89 59 59.00 0.00 2.20 -7.53 26.36 60 60.00 0.00 2.20 -7.53 18.83 61 61.00 0.00 2.20 -7.53 11.30 62 62.00 0.00 2.20 -7.53 3.77 63 62.50 0.00 2.20 -3.77 0.00 Rivanna Engineering&Surveying,PLC Page 37 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Combined Hydrograph Report Name: DA-2 & SWM3, 2yr Type: Combined [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 144.88 (cfs) Time to Peak (Tp) = 25.00 (min) Time of Base (Tb) = 1280.00 (min) Volume = 7.58 (ac-ft) Time Step = 1.00 (min) [COMBINED HYDROGRAPH RECORDS] Name: DA-2, Post 2yr Type: Modified Rational Peak Flow (Qp) = 133.22 (cfs) Time to Peak (Tp) = 25.00 (min) Time Step = 1.00 (min) Name: SWM3, 2yr Type: Reservoir: Modified Puls Peak Flow (Qp) = 13.54 (cfs) Time to Peak (Tp) = 33.00 (min) Time Step = 1.00 (min) [Combined Hydrograph Flow Values] Interval Time Outflow (min) (cfs) 1 1.00 5.37 2 2.00 10.82 3 3.00 16.35 4 4.00 21.97 5 5.00 27.65 6 6.00 33.42 7 7.00 39.25 8 8.00 45.10 9 9.00 51.01 10 10.00 56.99 11 11.00 63.03 12 12.00 69.14 13 13.00 75.04 14 14.00 80.91 15 15.00 86.83 16 16.00 92.74 17 17.00 98.50 18 18.00 104.20 19 19.00 109.89 20 20.00 115.55 21 21.00 121.20 22 22.00 127.21 23 23.00 133.17 24 24.00 139.06 25 25.00 144.88 26 26.00 141.77 27 27.00 138.59 28 28.00 135.36 29 29.00 132.07 30 30.00 128.72 31 31.00 125.31 Rivanna Engineering&Surveying,PLC Page 38 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Combined Hydrograph Report DA-2 & ST443, 2yr [Combined Hydrograph Flow Values] Interval Time Outflow (min) (cfs) 32 32.00 121.85 33 33.00 118.34 34 34.00 114.77 35 35.00 111.15 36 36.00 107.48 37 37.00 103.76 38 38.00 100.00 39 39.00 96.24 40 40.00 92.47 41 41.00 88.71 42 42.00 84.95 43 43.00 81.20 44 44.00 77.45 45 45.00 73.70 46 46.00 69.96 47 47.00 66.22 48 48.00 62.48 49 49.00 58.74 50 50.00 55.01 51 51.00 51.28 52 52.00 47.56 53 53.00 43.84 54 54.00 40.12 55 55.00 36.40 56 56.00 32.68 57 57.00 28.97 58 58.00 25.26 59 59.00 21.64 60 60.00 18.02 61 61.00 14.41 62 62.00 10.79 63 63.00 8.95 64 64.00 8.89 65 65.00 8.83 66 66.00 8.77 67 67.00 8.71 68 68.00 8.65 69 69.00 8.59 70 70.00 8.54 71 71.00 8.48 72 72.00 8.42 73 73.00 8.36 74 74.00 8.31 75 75.00 8.25 76 76.00 8.19 77 77.00 8.14 78 78.00 8.08 79 79.00 8.03 80 80.00 7.97 Rivanna Engineering&Surveying,PLC Page 39 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Combined Hydrograph Report Name: DA-2 & SWM3, 10yr Type: Combined [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 212.82 (cfs) Time to Peak (Tp) = 25.00 (min) Time of Base (Tb) = 1301.00 (min) Volume = 10.89 (ac-ft) Time Step = 1.00 (min) [COMBINED HYDROGRAPH RECORDS] Name: DA-2, Post 10yr Type: Modified Rational Peak Flow (Qp) = 192.75 (cfs) Time to Peak (Tp) = 25.00 (min) Time Step = 1.00 (min) Name: SWM3, 10yr Type: Reservoir: Modified Puls Peak Flow (Qp) = 23.56 (cfs) Time to Peak (Tp) = 32.00 (min) Time Step = 1.00 (min) [Combined Hydrograph Flow Values] [The time interval is 1.00 min] Interval Time Outflow (min) (cfs) 1 1.00 7.77 2 2.00 15.65 3 3.00 23.65 4 4.00 31.76 5 5.00 39.97 6 6.00 48.28 7 7.00 56.63 8 8.00 65.08 9 9.00 73.61 10 10.00 82.24 11 11.00 90.64 12 12.00 99.02 13 13.00 107.45 14 14.00 115.82 15 15.00 124.14 16 16.00 132.46 17 17.00 141.35 18 18.00 150.37 19 19.00 159.30 20 20.00 168.26 21 21.00 177.45 22 22.00 186.50 23 23.00 195.41 24 24.00 204.18 25 25.00 212.82 26 26.00 208.58 27 27.00 204.23 28 28.00 199.73 29 29.00 195.08 30 30.00 190.30 Rivanna Engineering&Surveying,PLC Page 40 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Combined Hydrograph Report DA-2 & SWM3, l0yr [Combined Hydrograph Flow Values] Interval Time Outflow (min) (cfs) 31 31.00 185.38 32 32.00 180.34 33 33.00 175.16 34 34.00 169.86 35 35.00 164.45 36 36.00 158.91 37 37.00 153.26 38 38.00 147.54 39 39.00 141.79 40 40.00 136.07 41 41.00 130.42 42 42.00 124.80 43 43.00 119.20 44 44.00 113.60 45 45.00 108.02 46 46.00 102.45 47 47.00 96.89 48 48.00 91.33 49 49.00 85.79 50 50.00 80.26 51 51.00 74.74 52 52.00 69.22 53 53.00 63.72 54 54.00 58.22 55 55.00 52.73 56 56.00 47.25 57 57.00 41.82 58 58.00 36.45 59 59.00 31.09 60 60.00 25.73 61 61.00 20.38 62 62.00 15.03 63 63.00 12.25 64 64.00 12.05 65 65.00 11.85 66 66.00 11.65 67 67.00 11.46 68 68.00 11.27 69 69.00 11.08 70 70.00 10.90 71 71.00 10.72 72 72.00 10.54 73 73.00 10.36 74 74.00 10.19 75 75.00 10.02 76 76.00 9.86 77 77.00 9.69 78 78.00 9.53 79 79.00 9.37 80 80.00 9.24 81 81.00 9.18 82 82.00 9.12 83 83.00 9.05 84 84.00 8.99 Rivanna Engineering&Surveying, PLC Page 41 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Combined Hydrograph Report Name: DA-2 & SWM3, 100yr Type: Combined [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 327.14 (cfs) Time to Peak (Tp) = 25.00 (min) Time of Base (Tb) = 1315.00 (min) Volume = 15.90 (ac-ft) Time Step = 1.00 (min) [COMBINED HYDROGRAPH RECORDS] Name: SWM3, 100yr Type: Reservoir: Modified Puls Peak Flow (Qp) = 50.63 (cfs) Time to Peak (Tp) = 30.00 (min) Time Step = 1.00 (min) Name: DA-2, Post 100yr Type: Modified Rational Peak Flow (Qp) = 282.39 (cfs) Time to Peak (Tp) = 25.00 (min) Time Step = 1.00 (min) [Combined Hydrograph Flow Values] Interval Time Outflow (min) (cfs) 1 1.00 11.38 2 2.00 22.93 3 3.00 34.63 4 4.00 46.50 5 5.00 58.51 6 6.00 70.60 7 7.00 82.82 8 8.00 95.17 9 9.00 107.41 10 10.00 119.51 11 11.00 131.69 12 12.00 143.73 13 13.00 155.79 14 14.00 168.65 15 15.00 182.10 16 16.00 196.06 17 17.00 210.23 18 18.00 224.27 19 19.00 238.39 20 20.00 252.26 21 21.00 266.26 22 22.00 282.60 23 23.00 298.16 24 24.00 312.99 25 25.00 327.14 26 26.00 321.83 27 27.00 315.93 28 28.00 309.54 29 29.00 302.81 30 30.00 295.37 31 31.00 287.31 Rivanna Engineering&Surveying,PLC Page 42 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Combined Hydrograph Report DA-2 & SWM3, 100yr [Combined Hydrograph Flow Values] Interval Time Outflow (min) (cfs) 32 32.00 278.83 33 33.00 270.15 34 34.00 261.11 35 35.00 251.72 36 36.00 242.03 37 37.00 232.04 38 38.00 221.90 39 39.00 211.82 40 40.00 201.91 41 41.00 192.17 42 42.00 182.69 43 43.00 174.37 44 44.00 166.07 45 45.00 157.79 46 46.00 149.54 47 47.00 141.30 48 48.00 133.09 49 49.00 124.89 50 50.00 116.71 51 51.00 108.55 52 52.00 100.41 53 53.00 92.29 54 54.00 84.19 55 55.00 76.18 56 56.00 68.18 57 57.00 60.19 58 58.00 52.21 59 59.00 44.24 60 60.00 36.28 61 61.00 28.33 62 62.00 20.39 63 63.00 16.23 64 64.00 15.84 65 65.00 15.46 66 66.00 15.09 67 67.00 14.73 68 68.00 14.38 69 69.00 14.03 70 70.00 13.70 71 71.00 13.45 72 72.00 13.23 73 73.00 13.01 74 74.00 12.79 75 75.00 12.58 76 76.00 12.37 77 77.00 12.17 78 78.00 11.96 79 79.00 11.77 80 80.00 11.57 81 81.00 11.38 82 82.00 11.19 83 83.00 11.00 84 84.00 10.82 85 85.00 10.64 Rivanna Engineering&Surveying,PLC Page 43 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Outlet Structure Report Type : Stand Pipe Name : SWM #2 Riser [RATING CURVE LIMIT] Minimum Elevation = 427.21 (ft) Maximum Elevation = 444.00 (ft) Elevation Increment = 0.25 (ft) [STAND PIPE INFORMATION] [ORIFICE INFORMATION] Diameter = 5.00 (ft) Crest Length = 15.71 (ft) Effective Crest Length = 15.71 (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 = 434.84 (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 44 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Post-Development Report SWM #2 Riser [CULVERT INFORMATION] Type : Circular Concrete - Square Edge with Headwall [OUTLET STRUCTURE INFORMATION] Diameter = 28.00 (in) Invert Elevation = 427.21 (ft) Pipe Length = 180.00 (ft) Slope = 0.03 Manning's n Value = 0.01 Orifice Coefficient = 0.60 Tailwater Elevation = 424.14 (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 = 22.86 [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 = 26.13 [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) [STAND PIPE STAGE VS. DISCHARGE] Elevation Stage Weirs Orifices Stand Pipe Culvert Total (ft) (ft) (cfs) (cfs) (cfs) (cfs) (cfs) 434.21 7.00 0.00 0.00 0.00 50.15 0.00 434.71 7.50 0.00 0.00 0.00 52.39 0.00 435.21 8.00 0.00 0.00 11.77 54.54 11.77 435.71 8.50 0.00 0.00 42.45 56.60 42.45 436.21 9.00 0.00 0.00 83.88 58.60 58.60 436.71 9.50 0.00 0.00 119.30 60.53 60.53 437.21 10.00 0.00 0.00 145.49 62.39 62.39 437.71 10.50 0.00 0.00 160.10 64.21 64.21 438.21 11.00 0.00 0.00 173.49 65.97 65.97 438.71 11.50 0.00 0.00 185.91 67.69 67.69 439.21 12.00 0.00 0.00 197.56 69.37 69.37 439.71 12.50 0.00 0.00 208.55 71.00 71.00 440.21 13.00 0.00 0.00 219.00 72.60 72.60 440.71 13.50 0.00 0.00 228.96 74.17 74.17 441.21 14.00 0.00 0.00 238.52 75.70 75.70 441.71 14.50 0.00 0.00 247.70 77.20 77.20 442.21 15.00 0.00 0.00 256.56 78.68 78.68 442.71 15.50 0.00 0.00 265.12 80.08 80.08 443.21 16.00 0.00 0.00 273.41 81.15 81.15 443.71 16.50 0.00 0.00 281.46 82.21 82.21 Rivanna Engineering&Surveying,PLC Page 45 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Reservoir Report Name: Existing Westsninister Pond (#2) [RATING CURVE LIMIT] Minimum Elevation = 427.21 (ft) Maximum Elevation = 444.00 (ft) Elevation Increment = 0.20 (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) 1 434.84 0.00 0.00 0.00 0.00 2 434.85 57970.00 28985.00 144.93 144.93 3 436.00 70995.00 64482.50 74477.29 74622.21 4 438.00 78780.00 74887.50 149775.00 224397.21 5 440.00 86752.00 82766.00 165532.00 389929.21 6 442.00 97560.00 92156.00 184312.00 574241.21 7 444.00 109513.00 103536.50 207073.00 781314.21 [DISCHARGE INFORMATION] Structure Number: 1 Type: Name: SWM #2 Riser Structure Number: 2 Type: Trapezoidal Weir Name: SWM #2 Overflow [RESERVOIR STAGE STORAGE/DISCHARGE] Elevation Stage Area Storage Discharge (ft) (ft) (sq ft) (cu ft) (cfs) 434.84 7.60 0.00 0.00 0.00 435.01 7.80 59830.71 5983.07 3.67 435.21 8.00 62086.13 18174.76 11.77 435.41 8.20 64341.54 30817.52 22.51 435.61 8.40 66596.95 43911.37 35.34 435.81 8.60 68852.36 57456.30 49.97 436.01 8.80 71033.92 71444.93 57.81 436.21 9.00 71812.42 85729.56 58.60 436.41 9.20 72590.92 100169.90 59.38 436.61 9.40 73369.42 114765.93 60.14 436.81 9.60 74147.93 129517.67 60.90 437.01 9.80 74926.42 144425.10 61.65 437.21 10.00 75704.92 159488.24 62.39 437.41 10.20 76483.42 174707.07 63.13 437.61 10.40 77261.92 190081.61 63.85 437.81 10.60 78040.43 205611.84 64.57 438.01 10.80 78819.86 221297.87 65.27 438.21 11.00 79617.06 237141.56 65.97 438.41 11.20 80414.26 253144.70 66.67 438.61 11.40 81211.46 269307.27 67.35 438.81 11.60 82008.66 285629.28 68.03 439.01 11.80 82805.86 302110.73 68.70 Rivanna Engineering&Surveying,PLC Page 46 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Reservoir Report Existing Westminister Pond (#2) [RESERVOIR STAGE STORAGE/DISCHARGE] Elevation Stage Area Storage Discharge (ft) (ft) (sq ft) (cu ft) (cfs) 439.21 12.00 83603.06 318751.62 69.37 439.41 12.20 84400.26 335551.96 70.03 439.61 12.40 85197.46 352511.73 70.68 439.81 12.60 85994.66 369630.94 71.33 440.01 12.80 86806.04 386911.01 71.97 440.21 13.00 87886.84 404380.30 72.60 440.41 13.20 88967.64 422065.75 73.23 440.61 13.40 90048.44 439967.35 73.86 440.81 13.60 91129.24 458085.12 74.48 441.01 13.80 92210.04 476419.05 75.09 441.21 14.00 93290.84 494969.14 75.70 441.41 14.20 94371.64 513735.39 76.31 441.61 14.40 95452.44 532717.79 76.91 441.81 14.60 96533.24 551916.36 77.50 442.01 14.80 97619.76 571331.66 78.09 442.21 15.00 98815.06 590975.15 78.68 442.41 15.20 100010.36 610857.69 79.26 442.61 15.40 101205.66 630979.29 79.84 442.81 15.60 102400.97 651339.96 80.29 443.01 15.80 103596.26 671939.68 80.73 443.21 16.00 104791.56 692778.46 81.16 443.41 16.20 105986.86 713856.30 81.58 443.61 16.40 107182.16 735173.21 82.00 443.81 16.60 108377.47 756729.17 82.42 Maximum Storage = 777428.76 (cu ft) Maximum Discharge = 82.82 (cfs) Rivanna Engineering&Surveying,PLC Page 47 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Routed Hydrograph Report Name: SWM2, 2yr Type: Reservoir: Modified Puls [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 61.28 (cfs) Time to Peak (Tp) = 48.00 (min) Time of Base (Tb) = 1297.00 (min) Volume = 7.58 (ac-ft) Time Step = 1.00 (min) Peak Elevation = 436.91 (ft) Detention Time = NA [RESERVOIR STRUCTURE INFORMATION] Name = Exist Westminister Pond #2 Storage Type = User-Defined Area Maximum Storage = 777428.76 (cu ft) Maximum Discharge = 82.82 (cfs) [INFLOW HYDROGRAPH INFORMATION] Name = DA-2 & SWM3, 2yr Peak Flow (Qp) = 144.88 (cfs) Time to Peak (Tp) = 25.00 (min) Time of Base (Tb) = 1280.00 (min) Volume = 7.58 (ac-ft) Flow Multiplier = 1.00 [EQUATION] (I1+I2) + (2(S1)/dt)-01 = (2(S2)/dt)+02 Where: I1 = Previous inflow I2 = Current inflow S1 = Previous storage S2 = Current storage dt = Time increment 01 = Previous outflow 02 = Current outflow A = (I1 + I2) B = (2 (S1) / dt) - 01 C = (2 (S2) / dt) + 02 [Computation of Reservoir Outflow Table of Modified Puls Method] Intv Time Inflow A B C Outflow Storage Elev (min) (cfs) (cfs) (cfs) (cfs) (cfs) (cu ft) (ft) 1 1.00 5.37 5.37 0.00 316.30 0.10 158.20 434.82 2 2.00 10.82 16.19 316.30 1258.60 0.39 629.49 434.83 3 3.00 16.35 27.18 1258.60 2813.84 0.86 1407.35 434.86 4 4.00 21.97 38.32 2813.84 4969.27 1.52 2485.40 434.89 5 5.00 27.65 49.62 4969.27 7712.45 2.36 3857.41 434.94 6 6.00 33.42 61.07 7712.45 11031.22 3.38 5517.30 434.99 7 7.00 39.25 72.67 11031.22 14908.65 4.65 7456.65 435.03 8 8.00 45.10 84.35 14908.65 19322.74 6.11 9664.43 435.07 9 9.00 51.01 96.12 19322.74 24255.89 7.75 12131.82 435.11 10 10.00 56.99 108.01 24255.89 29695.39 9.56 14852.48 435.16 Rivanna Engineering&Surveying,PLC Page 48 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Routed Hydrograph Report SWM2, 2yr [Computation of Reservoir Outflow Table of Modified Puls Method] Intv Time Inflow A B C Outflow Storage Elev (min) (cfs) (cfs) (cfs) (cfs) (cfs) (cu ft) (ft) 11 11.00 63.03 120.03 29695.39 35628.94 11.54 17820.24 435.20 12 12.00 69.14 132.17 35628.94 42013.30 14.18 21013.74 435.25 13 13.00 75.04 144.17 42013.30 48786.05 17.06 24401.55 435.31 14 14.00 80.91 155.95 48786.05 55910.81 20.09 27965.45 435.36 15 15.00 86.83 167.74 55910.81 63364.27 23.37 31693.82 435.42 16 16.00 92.74 179.57 63364.27 71102.62 27.16 35564.89 435.48 17 17.00 98.50 191.24 71102.62 79078.82 31.07 39554.95 435.54 18 18.00 104.20 202.70 79078.82 87267.03 35.09 43651.06 435.61 19 19.00 109.89 214.09 87267.03 95627.80 39.58 47833.69 435.67 20 20.00 115.55 225.43 95627.80 104124.03 44.17 52084.10 435.73 21 21.00 121.20 236.74 104124.03 112743.96 48.83 56396.40 435.79 22 22.00 127.21 248.41 112743.96 121604.17 51.86 60828.02 435.86 23 23.00 133.17 260.38 121604.17 130845.65 54.45 65450.05 435.92 24 24.00 139.06 272.22 130845.65 140480.27 57.15 70268.71 435.99 25 25.00 144.88 283.94 140480.27 150605.39 58.02 75331.71 436.06 26 26.00 141.77 286.65 150605.39 160824.51 58.30 80441.41 436.14 27 27.00 138.59 280.36 160824.51 170633.04 58.58 85345.81 436.20 28 28.00 135.36 273.95 170633.04 180025.57 58.83 90042.20 436.27 29 29.00 132.07 267.43 180025.57 188996.86 59.07 94527.96 436.33 30 30.00 128.72 260.79 188996.86 197541.39 59.30 98800.35 436.39 31 31.00 125.31 254.03 197541.39 205654.01 59.52 102856.76 436.45 32 32.00 121.85 247.17 205654.01 213329.74 59.72 106694.73 436.50 33 33.00 118.34 240.20 213329.74 220563.51 59.91 110311.71 436.55 34 34.00 114.77 233.11 220563.51 227350.30 60.09 113705.19 436.60 35 35.00 111.15 225.93 227350.30 233685.33 60.25 116872.79 436.64 36 36.00 107.48 218.64 233685.33 239564.04 60.40 119812.22 436.68 37 37.00 103.76 211.25 239564.04 244981.77 60.54 122521.16 436.72 38 38.00 100.00 203.77 244981.77 249934.73 60.67 124997.70 436.75 39 39.00 96.24 196.24 249934.73 254421.57 60.79 127241.18 436.78 40 40.00 92.47 188.71 254421.57 258443.35 60.89 129252.12 436.81 41 41.00 88.71 181.18 258443.35 262002.05 60.98 131031.51 436.83 42 42.00 84.95 173.66 262002.05 265099.60 61.06 132580.33 436.85 43 43.00 81.20 166.15 265099.60 267737.84 61.12 133899.48 436.87 44 44.00 77.45 158.65 267737.84 269918.54 61.18 134989.86 436.88 45 45.00 73.70 151.15 269918.54 271643.49 61.22 135852.35 436.89 46 46.00 69.96 143.66 271643.49 272914.44 61.25 136487.85 436.90 47 47.00 66.22 136.17 272914.44 273733.15 61.27 136897.21 436.91 48 48.00 62.48 128.70 273733.15 274101.36 61.28 137081.32 436.91 49 49.00 58.74 121.22 274101.36 274020.80 61.28 137041.04 436.91 50 50.00 55.01 113.76 274020.80 273493.19 61.27 136777.23 436.91 51 51.00 51.28 106.30 273493.19 272520.23 61.24 136290.74 436.90 52 52.00 47.56 98.84 272520.23 271103.61 61.21 135582.41 436.89 53 53.00 43.84 91.39 271103.61 269245.02 61.16 134653.09 436.88 54 54.00 40.12 83.95 269245.02 266946.14 61.10 133503.62 436.86 55 55.00 36.40 76.51 266946.14 264208.62 61.04 132134.83 436.85 56 56.00 32.68 69.08 264208.62 261034.12 60.96 130547.54 436.82 57 57.00 28.97 61.65 261034.12 257424.33 60.86 128742.60 436.80 58 58.00 25.26 54.23 257424.33 253381.03 60.76 126720.89 436.77 59 59.00 21.64 46.90 253381.03 248910.82 60.64 124485.73 436.74 60 60.00 18.02 39.66 248910.82 244020.64 60.52 122040.58 436.71 61 61.00 14.41 32.43 244020.64 238712.40 60.38 119386.39 436.67 62 62.00 10.79 25.20 238712.40 232987.43 60.24 116523.83 436.63 63 63.00 8.95 19.75 232987.43 226953.58 60.08 113506.83 436.59 64 64.00 8.89 17.85 226953.58 220824.89 59.92 110442.41 436.55 Rivanna Engineering&Surveying,PLC Page 49 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Routed Hydrograph Report Name: SWM2, l0yr Type: Reservoir: Modified Puls [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 66.20 (cfs) Time to Peak (Tp) = 53.00 (min) Time of Base (Tb) = 1319.00 (min) Volume = 10.89 (ac-ft) Time Step = 1.00 (min) Peak Elevation = 438.28 (ft) Detention Time = NA [RESERVOIR STRUCTURE INFORMATION] Name = Exist Westminister Pond #2 Storage Type = User-Defined Area Maximum Storage = 777428.76 (cu ft) Maximum Discharge = 82.82 (cfs) [INFLOW HYDROGRAPH INFORMATION] Name = DA-2 & SWM3, l0yr Peak Flow (Qp) = 212.82 (cfs) Time to Peak (Tp) = 25.00 (min) Time of Base (Tb) = 1301.00 (min) Volume = 10.89 (ac-ft) Flow Multiplier = 1.00 [EQUATION] (I1+I2) + (2(S1)/dt)-01 = (2(S2)/dt)+02 Where: I1 = Previous inflow I2 = Current inflow S1 = Previous storage S2 = Current storage dt = Time increment 01 = Previous outflow 02 = Current outflow A = (I1 + 12) B = (2 (S1) / dt) - 01 C = (2 (S2) / dt) + 02 [Computation of Reservoir Outflow Table of Modified Puls Method] Intv Time Inflow A B C Outflow Storage Elev (min) (cfs) (cfs) (cfs) (cfs) (cfs) (cu ft) (ft) 1 1.00 7.77 7.77 0.00 457.54 0.14 228.84 434.82 2 2.00 15.65 23.42 457.54 1820.44 0.56 910.50 434.84 3 3.00 23.65 39.30 1820.44 4069.47 1.25 2035.36 434.88 4 4.00 31.76 55.41 4069.47 7185.85 2.20 3594.03 434.93 5 5.00 39.97 71.73 7185.85 11151.27 3.42 5577.35 435.00 6 6.00 48.28 88.26 11151.27 15940.67 4.99 7972.83 435.04 7 7.00 56.63 104.92 15940.67 21523.60 6.85 10765.23 435.09 8 8.00 65.08 121.71 21523.60 27875.78 8.96 13942.37 435.14 9 9.00 73.61 138.69 27875.78 34978.00 11.32 17494.66 435.20 10 10.00 82.24 155.85 34978.00 42776.16 14.51 21395.33 435.26 Rivanna Engineering&Surveying,PLC Page 50 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Routed Hydrograph Report S M2, l0yr [Computation of Reservoir Outflow Table of Modified Puls Method] Intv Time Inflow A B C Outflow Storage Elev (min) (cfs) (cfs) (cfs) (cfs) (cfs) (cu ft) (ft) 11 11.00 90.64 172.88 42776.16 51189.92 18.08 25604.00 435.33 12 12.00 99.02 189.66 51189.92 60166.90 21.90 30094.40 435.40 13 13.00 107.45 206.47 60166.90 69649.64 26.45 34838.04 435.47 14 14.00 115.82 223.27 69649.64 79575.00 31.32 39803.16 435.55 15 15.00 124.14 239.96 79575.00 89899.36 36.48 44967.92 435.63 16 16.00 132.46 256.60 89899.36 100565.70 42.25 50303.97 435.70 17 17.00 141.35 273.81 100565.70 111562.06 48.19 55805.12 435.79 18 18.00 150.37 291.72 111562.06 123033.98 52.26 61543.12 435.87 19 19.00 159.30 309.67 123033.98 135135.80 55.65 67595.73 435.95 20 20.00 168.26 327.55 135135.80 147970.69 57.95 74014.32 436.05 21 21.00 177.45 345.71 147970.69 161735.93 58.33 80897.13 436.14 22 22.00 186.50 363.95 161735.93 176548.38 58.74 88303.56 436.25 23 23.00 195.41 381.91 176548.38 192388.36 59.16 96223.76 436.36 24 24.00 204.18 399.59 192388.36 209236.83 59.61 104648.22 436.47 25 25.00 212.82 417.01 209236.83 227075.13 60.08 113567.61 436.59 26 26.00 208.58 421.41 227075.13 245121.40 60.55 122590.98 436.72 27 27.00 204.23 412.81 245121.40 262597.15 60.99 131329.07 436.83 28 28.00 199.73 403.95 262597.15 279489.14 61.42 139775.28 436.95 29 29.00 195.08 394.81 279489.14 295782.55 61.83 147922.19 437.06 30 30.00 190.30 385.38 295782.55 311462.92 62.21 155762.56 437.16 31 31.00 185.38 375.68 311462.92 326516.27 62.58 163289.42 437.26 32 32.00 180.34 365.72 326516.27 340929.02 62.92 170495.97 437.35 33 33.00 175.16 355.50 340929.02 354688.00 63.25 177375.63 437.44 34 34.00 169.86 345.02 354688.00 367780.49 63.56 183922.02 437.53 35 35.00 164.45 334.31 367780.49 380194.02 63.85 190128.94 437.61 36 36.00 158.91 323.36 380194.02 391916.69 64.12 195990.41 437.69 37 37.00 153.26 312.17 391916.69 402936.98 64.38 201500.68 437.76 38 38.00 147.54 300.80 402936.98 413245.34 64.61 206654.98 437.82 39 39.00 141.79 289.33 413245.34 422838.40 64.83 211451.61 437.88 40 40.00 136.07 277.86 422838.40 431718.43 65.03 215891.73 437.94 41 41.00 130.42 266.49 431718.43 439892.99 65.21 219979.10 437.99 42 42.00 124.80 255.22 439892.99 447370.63 65.38 223718.00 438.04 43 43.00 119.20 244.00 447370.63 454155.98 65.53 227110.76 438.08 44 44.00 113.60 232.80 454155.98 460252.31 65.66 230158.99 438.12 45 45.00 108.02 221.62 460252.31 465662.76 65.78 232864.27 438.16 46 46.00 102.45 210.47 465662.76 470390.43 65.89 235228.16 438.19 47 47.00 96.89 199.33 470390.43 474438.39 65.98 237252.18 438.21 48 48.00 91.33 188.22 474438.39 477809.75 66.05 238937.90 438.23 49 49.00 85.79 177.12 477809.75 480507.58 66.11 240286.84 438.25 50 50.00 80.26 166.05 480507.58 482534.78 66.15 241300.47 438.26 51 51.00 74.74 154.99 482534.78 483894.24 66.18 241980.21 438.27 52 52.00 69.22 143.96 483894.24 484588.79 66.20 242327.50 438.27 53 53.00 63.72 132.94 484588.79 484621.26 66.20 242343.73 438.28 54 54.00 58.22 121.94 484621.26 483994.42 66.18 242030.30 438.27 55 55.00 52.73 110.95 483994.42 482711.01 66.16 241388.58 438.26 56 56.00 47.25 99.98 482711.01 480773.75 66.11 240419.93 438.25 57 57.00 41.82 89.07 480773.75 478187.62 66.06 239126.84 438.23 58 58.00 36.45 78.27 478187.62 474961.17 65.99 237513.58 438.21 59 59.00 31.09 67.55 474961.17 471100.44 65.90 235583.17 438.19 60 60.00 25.73 56.83 471100.44 466607.65 65.80 233336.73 438.16 61 61.00 20.38 46.12 466607.65 461484.92 65.69 230775.31 438.13 62 62.00 15.03 35.41 461484.92 455734.35 65.56 227899.96 438.09 63 63.00 12.25 27.28 455734.35 449512.01 65.43 224788.72 438.05 64 64.00 12.05 24.30 449512.01 443127.57 65.29 221596.43 438.01 Rivanna Engineering&Surveying,PLC Page 51 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Routed Hydrograph Report Name: SWM2, 100yr Type: Reservoir: Modified Puls [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 73.24 (cfs) Time to Peak (Tp) = 55.00 (min) Time of Base (Tb) = 1332.00 (min) Volume = 15.90 (ac-ft) Time Step = 1.00 (min) Peak Elevation = 440.41 (ft) Detention Time = NA [RESERVOIR STRUCTURE INFORMATION] Name = Existing Westminister Pond (#2) Storage Type = User-Defined Area Maximum Storage = 777428.76 (cu ft) Maximum Discharge = 82.82 (cfs) [INFLOW HYDROGRAPH INFORMATION] Name = DA-2 & SWM3, 100yr Peak Flow (Qp) = 327.14 (cfs) Time to Peak (Tp) = 25.00 (min) Time of Base (Tb) = 1315.00 (min) Volume = 15.90 (ac-ft) Flow Multiplier = 1.00 [EQUATION] (I1+I2) + (2(S1)/dt)-01 = (2(S2)/dt)+02 Where: I1 = Previous inflow I2 = Current inflow S1 = Previous storage S2 = Current storage dt = Time increment 01 = Previous outflow 02 = Current outflow A = (I1 + I2) B = (2 (S1) / dt) - 01 C = (2 (S2) / dt) + 02 [Computation of Reservoir Outflow Table of Modified Puls Method] Intv Time Inflow A B C Outflow Storage Elev (min) (cfs) (cfs) (cfs) (cfs) (cfs) (cu ft) (ft) 1 1.00 11.38 11.38 0.00 670.25 0.21 335.23 434.82 2 2.00 22.93 34.31 670.25 2666.59 0.82 1333.70 434.85 3 3.00 34.63 57.56 2666.59 5960.56 1.83 2981.19 434.91 4 4.00 46.50 81.14 5960.56 10524.40 3.23 5263.81 434.99 5 5.00 58.51 105.02 10524.40 16323.12 5.12 8164.12 435.05 6 6.00 70.60 129.11 16323.12 23314.06 7.44 11660.75 435.10 7 7.00 82.82 153.42 23314.06 31460.86 10.15 15735.50 435.17 8 8.00 95.17 177.99 31460.86 40710.15 13.63 20361.89 435.24 9 9.00 107.41 202.58 40710.15 50963.61 17.99 25490.80 435.33 10 10.00 119.51 226.91 50963.61 62128.60 22.76 31075.68 435.41 Rivanna Engineering&Surveying,PLC Page 52 (434)984-1599 Luxor Subdivision Westminster Canterbury Pond, SWM #2 Routed Hydrograph Report SWM2, 1O0yr [Computation of Reservoir Outflow Table of Modified Puls Method] Intv Time Inflow A B C Outflow Storage Elev (min) (cfs) (cfs) (cfs) (cfs) (cfs) (cu ft) (ft) 11 11.00 131.69 251.20 62128.60 74110.56 28.64 37069.60 435.51 12 12.00 143.73 275.42 74110.56 86819.06 34.87 43426.96 435.60 13 13.00 155.79 299.52 86819.06 100168.85 42.03 50105.44 435.70 14 14.00 168.65 324.45 100168.85 114131.37 49.58 57090.47 435.80 15 15.00 182.10 350.76 114131.37 128962.45 53.92 64508.19 435.91 16 16.00 196.06 378.16 128962.45 144941.02 57.87 72499.44 436.02 17 17.00 210.23 406.29 144941.02 162345.18 58.35 81201.76 436.15 18 18.00 224.27 434.50 162345.18 181381.72 58.87 90720.29 436.28 19 19.00 238.39 462.66 181381.72 202043.45 59.42 101051.44 436.42 20 20.00 252.26 490.65 202043.45 224315.91 60.01 112187.96 436.57 21 21.00 266.26 518.52 224315.91 248188.36 60.63 124124.50 436.74 22 22.00 282.60 548.87 248188.36 273805.59 61.28 136933.43 436.91 23 23.00 298.16 580.77 273805.59 301256.84 61.96 150659.40 437.09 24 24.00 312.99 611.16 301256.84 330447.70 62.67 165255.18 437.29 25 25.00 327.14 640.14 330447.70 361290.44 63.41 180676.93 437.49 26 26.00 321.83 648.98 361290.44 392575.61 64.14 196319.87 437.69 27 27.00 315.93 637.76 392575.61 423102.48 64.83 211583.66 437.89 28 28.00 309.54 625.47 423102.48 452809.90 65.50 226437.70 438.07 29 29.00 302.81 612.34 452809.90 481651.90 66.13 240859.02 438.26 30 30.00 295.37 598.18 481651.90 509569.94 66.74 254818.34 438.43 31 31.00 287.31 582.68 509569.94 536487.74 67.31 268277.52 438.60 32 32.00 278.83 566.14 536487.74 562346.62 67.85 281207.24 438.76 33 33.00 270.15 548.99 562346.62 587113.19 68.35 293590.77 438.91 34 34.00 261.11 531.26 587113.19 610756.73 68.83 305412.78 439.05 35 35.00 251.72 512.83 610756.73 633238.99 69.28 316654.14 439.18 36 36.00 242.03 493.75 633238.99 654524.64 69.70 327297.17 439.31 37 37.00 232.04 474.07 654524.64 674580.86 70.09 337325.48 439.43 38 38.00 221.90 453.94 674580.86 693383.83 70.46 346727.14 439.54 39 39.00 211.82 433.71 693383.83 710931.35 70.79 355501.07 439.64 40 40.00 201.91 413.73 710931.35 727241.17 71.10 363656.13 439.74 41 41.00 192.17 394.08 727241.17 742336.51 71.39 371203.95 439.83 42 42.00 182.69 374.86 742336.51 756245.87 71.64 378158.76 439.91 43 43.00 174.37 357.05 756245.87 769057.48 71.88 384564.68 439.98 44 44.00 166.07 340.44 769057.48 780844.88 72.10 390458.49 440.05 45 45.00 157.79 323.86 780844.88 791613.18 72.29 395842.73 440.11 46 46.00 149.54 307.33 791613.18 801367.22 72.47 400719.84 440.17 47 47.00 141.30 290.84 801367.22 810111.70 72.63 405092.17 440.22 48 48.00 133.09 274.39 810111.70 817851.40 72.77 408962.08 440.26 49 49.00 124.89 257.98 817851.40 824590.93 72.89 412331.91 440.30 50 50.00 116.71 241.61 824590.93 830334.69 72.99 415203.84 440.33 51 51.00 108.55 225.27 830334.69 835087.00 73.07 417580.04 440.36 52 52.00 100.41 208.97 835087.00 838852.11 73.14 419462.62 440.38 53 53.00 92.29 192.70 838852.11 841634.19 73.19 420853.69 440.40 54 54.00 84.19 176.48 841634.19 843438.29 73.22 421755.76 440.41 55 55.00 76.18 160.37 843438.29 844273.17 73.24 422173.21 440.41 56 56.00 68.18 144.36 844273.17 844146.37 73.24 422109.80 440.41 57 57.00 60.19 128.37 844146.37 843061.29 73.22 421567.25 440.40 58 58.00 52.21 112.39 843061.29 841021.32 73.18 420547.25 440.39 59 59.00 44.24 96.45 841021.32 838029.81 73.13 419051.47 440.38 60 60.00 36.28 80.52 838029.81 834090.06 73.06 417081.56 440.35 61 61.00 28.33 64.61 834090.06 829205.34 72.97 414639.15 440.33 62 62.00 20.39 48.72 829205.34 823378.89 72.87 411725.88 440.29 63 63.00 16.23 36.62 823378.89 816839.56 72.75 408456.15 440.26 64 64.00 15.84 32.07 816839.56 810041.38 72.63 405057.00 440.22 Rivanna Engineering&Surveying,PLC Page 53 (434)984-1599 Luxor Subdivision Stormwater Management Pond #1 Pre-Development Hydrograph Report Name: DA-1, 2yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow ((a) = 120.98 (cfs) Time to Peak (Tp) = 26.00 (min) Time of Base (Tb) = 65.00 (min) Volume = 5.42 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 5.42 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef Fontana 2.50 0 0.30 Commercial 9.50 0 0.75 Montessori 5.40 0 0.50 Roads 1.00 0 0.90 Future Uncontained 18.70 0 0.32 Woods/Brush 40.40 0 0.30 Fontana & Avemore a a) Aeue ere Existing Town & Country 1.90 0 0.70 U, .,,) Cccter.+ Overall Approximation 140.90 NA 0.35 Cl4Le./ 7!c cp C OTc. [TIME CONCENTRATION -- User Defined] 11,6 Time of Concentration (Tc) = 26.00 (min) [RAINFALL DESCRIPTION] 11a=J Distribution Type = Synthetic Total Precipitation = 1.05 (in) Return Period = 2 (yr) Storm Duration = 0.43 (hr) Rivanna Engineering&Surveying,PLC Page 54 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Pre-Development Hydrograph Report DA-1, 2yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.04 0.00 4.65 2 2.00 0.04 0.08 4.65 9.31 3 3.00 0.04 0.12 4.65 13.96 4 4.00 0.04 0.16 4.65 18.61 5 5.00 0.04 0.20 4.65 23.26 6 6.00 0.04 0.24 4.65 27.92 7 7.00 0.04 0.28 4.65 32.57 8 8.00 0.04 0.32 4.65 37.22 9 9.00 0.04 0.36 4.65 41.88 10 10.00 0.04 0.41 4.65 46.53 11 11.00 0.04 0.45 4.65 51.18 12 12.00 0.04 0.49 4.65 55.83 13 13.00 0.04 0.53 4.65 60.49 14 14.00 0.04 0.57 4.65 65.14 15 15.00 0.04 0.61 4.65 69.79 16 16.00 0.04 0.65 4.65 74.45 17 17.00 0.04 0.69 4.65 79.10 18 18.00 0.04 0.73 4.65 83.75 19 19.00 0.04 0.77 4.65 88.41 20 20.00 0.04 0.81 4.65 93.06 21 21.00 0.04 0.85 4.65 97.71 22 22.00 0.04 0.89 4.65 102.36 23 23.00 0.04 0.93 4.65 107.02 24 24.00 0.04 0.97 4.65 111.67 25 25.00 0.04 1.01 4.65 116.32 26 26.00 0.04 1.05 4.65 120.98 27 27.00 0.00 1.05 -3.10 117.87 28 28.00 0.00 1.05 -3.10 114.77 29 29.00 0.00 1.05 -3.10 111.67 30 30.00 0.00 1.05 -3.10 108.57 31 31.00 0.00 1.05 -3.10 105.47 32 32.00 0.00 1.05 -3.10 102.36 33 33.00 0.00 1.05 -3.10 99.26 34 34.00 0.00 1.05 -3.10 96.16 35 35.00 0.00 1.05 -3.10 93.06 36 36.00 0.00 1.05 -3.10 89.96 37 37.00 0.00 1.05 -3.10 86.85 38 38.00 0.00 1.05 -3.10 83.75 39 39.00 0.00 1.05 -3.10 80.65 40 40.00 0.00 1.05 -3.10 77.55 41 41.00 0.00 1.05 -3.10 74.45 42 42.00 0.00 1.05 -3.10 71.34 43 43.00 0.00 1.05 -3.10 68.24 44 44.00 0.00 1.05 -3.10 65.14 45 45.00 0.00 1.05 -3.10 62.04 46 46.00 0.00 1.05 -3.10 58.94 47 47.00 0.00 1.05 -3.10 55.83 48 48.00 0.00 1.05 -3.10 52.73 49 49.00 0.00 1.05 -3.10 49.63 50 50.00 0.00 1.05 -3.10 46.53 51 51.00 0.00 1.05 -3.10 43.43 52 52.00 0.00 1.05 -3.10 40.33 53 53.00 0.00 1.05 -3.10 37.22 Rivanna Engineering&Surveying,PLC Page 55 (434)984-1599 Luxor Subdivision Stormwater Management Pond #1 Pre-Development Hydrograph Report Name: DA-1, l0yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow ((a) = 175.31 (cfs) Time to Peak (Tp) = 26.00 (min) Time of Base (Tb) = 65.00 (min) Volume = 7.85 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 7.85 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef Fontana 2.50 0 0.30 Commercial 9.50 0 0.75 Montessori 5.40 0 0.50 Roads 1.00 0 0.90 Future Uncontained 18.70 0 0.32 Woods/Brush 40.40 0 0.30 Fontana & Avemore 61.50 0 0.30 Existing Town & Country 1.90 0 0.70 Overall Approximation 140.90 NA 0.35 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 26.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 1.53 (in) Return Period = User Defined (yr) Storm Duration = 0.43 (hr) Rivanna Engineering&Surveying,PLC Page 56 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Pre-Development Hydrograph Report DA-1, l0yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.06 0.00 6.74 2 2.00 0.06 0.12 6.74 13.49 3 3.00 0.06 0.18 6.74 20.23 4 4.00 0.06 0.23 6.74 26.97 5 5.00 0.06 0.29 6.74 33.71 6 6.00 0.06 0.35 6.74 40.46 7 7.00 0.06 0.41 6.74 47.20 8 8.00 0.06 0.47 6.74 53.94 9 9.00 0.06 0.53 6.74 60.68 10 10.00 0.06 0.59 6.74 67.43 11 11.00 0.06 0.65 6.74 74.17 12 12.00 0.06 0.70 6.74 80.91 13 13.00 0.06 0.76 6.74 87.66 14 14.00 0.06 0.82 6.74 94.40 15 15.00 0.06 0.88 6.74 101.14 16 16.00 0.06 0.94 6.74 107.88 17 17.00 0.06 1.00 6.74 114.63 18 18.00 0.06 1.06 6.74 121.37 19 19.00 0.06 1.12 6.74 128.11 20 20.00 0.06 1.17 6.74 134.85 21 21.00 0.06 1.23 6.74 141.60 22 22.00 0.06 1.29 6.74 148.34 23 23.00 0.06 1.35 6.74 155.08 24 24.00 0.06 1.41 6.74 161.83 25 25.00 0.06 1.47 6.74 168.57 26 26.00 0.06 1.53 6.74 175.31 27 27.00 0.00 1.53 -4.50 170.82 28 28.00 0.00 1.53 -4.50 166.32 29 29.00 0.00 1.53 -4.50 161.83 30 30.00 0.00 1.53 -4.50 157.33 31 31.00 0.00 1.53 -4.50 152.83 32 32.00 0.00 1.53 -4.50 148.34 33 33.00 0.00 1.53 -4.50 143.84 34 34.00 0.00 1.53 -4.50 139.35 35 35.00 0.00 1.53 -4.50 134.85 36 36.00 0.00 1.53 -4.50 130.36 37 37.00 0.00 1.53 -4.50 125.86 38 38.00 0.00 1.53 -4.50 121.37 39 39.00 0.00 1.53 -4.50 116.87 40 40.00 0.00 1.53 -4.50 112.38 41 41.00 0.00 1.53 -4.50 107.88 42 42.00 0.00 1.53 -4.50 103.39 43 43.00 0.00 1.53 -4.50 98.89 44 44.00 0.00 1.53 -4.50 94.40 45 45.00 0.00 1.53 -4.50 89.90 46 46.00 0.00 1.53 -4.50 85.41 47 47.00 0.00 1.53 -4.50 80.91 48 48.00 0.00 1.53 -4.50 76.42 49 49.00 0.00 1.53 -4.50 71.92 50 50.00 0.00 1.53 -4.50 67.43 51 51.00 0.00 1.53 -4.50 62.93 52 52.00 0.00 1.53 -4.50 58.44 53 53.00 0.00 1.53 -4.50 53.94 Rivanna Engineering&Surveying,PLC Page 57 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Pre-Development Hydrograph Report Name: DA-1, 10Oyr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 257.07 (cfs) Time to Peak (Tp) = 26.00 (min) Time of Base (Tb) = 65.00 (min) Volume = 11.51 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 11.51 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef Fontana 2.50 0 0.30 Commercial 9.50 0 0.75 Montessori 5.40 0 0.50 Roads 1.00 0 0.90 Future Uncontained 18.70 0 0.32 Woods/Brush 40.40 0 0.30 Fontana & Avemore 61.50 0 0.30 Existing Town & Country 1.90 0 0.70 Overall Approximation 140.90 NA 0.35 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 26.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 2.24 (in) Return Period = 100 (yr) Storm Duration = 0.43 (hr) Rivanna Engineering&Surveying,PLC Page 58 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Pre-Development Hydrograph Report DA-1, 100yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.09 0.00 9.89 2 2.00 0.09 0.17 9.89 19.77 3 3.00 0.09 0.26 9.89 29.66 4 4.00 0.09 0.34 9.89 39.55 5 5.00 0.09 0.43 9.89 49.44 6 6.00 0.09 0.52 9.89 59.32 7 7.00 0.09 0.60 9.89 69.21 8 8.00 0.09 0.69 9.89 79.10 9 9.00 0.09 0.77 9.89 88.99 10 10.00 0.09 0.86 9.89 98.87 11 11.00 0.09 0.95 9.89 108.76 12 12.00 0.09 1.03 9.89 118.65 13 13.00 0.09 1.12 9.89 128.54 14 14.00 0.09 1.21 9.89 138.42 15 15.00 0.09 1.29 9.89 148.31 16 16.00 0.09 1.38 9.89 158.20 17 17.00 0.09 1.46 9.89 168.09 18 18.00 0.09 1.55 9.89 177.97 19 19.00 0.09 1.64 9.89 187.86 20 20.00 0.09 1.72 9.89 197.75 21 21.00 0.09 1.81 9.89 207.64 22 22.00 0.09 1.89 9.89 217.52 23 23.00 0.09 1.98 9.89 227.41 24 24.00 0.09 2.07 9.89 237.30 25 25.00 0.09 2.15 9.89 247.19 26 26.00 0.09 2.24 9.89 257.07 27 27.00 0.00 2.24 -6.59 250.48 28 28.00 0.00 2.24 -6.59 243.89 29 29.00 0.00 2.24 -6.59 237.30 30 30.00 0.00 2.24 -6.59 230.71 31 31.00 0.00 2.24 -6.59 224.11 32 32.00 0.00 2.24 -6.59 217.52 33 33.00 0.00 2.24 -6.59 210.93 34 34.00 0.00 2.24 -6.59 204.34 35 35.00 0.00 2.24 -6.59 197.75 36 36.00 0.00 2.24 -6.59 191.16 37 37.00 0.00 2.24 -6.59 184.57 38 38.00 0.00 2.24 -6.59 177.97 39 39.00 0.00 2.24 -6.59 171.38 40 40.00 0.00 2.24 -6.59 164.79 41 41.00 0.00 2.24 -6.59 158.20 42 42.00 0.00 2.24 -6.59 151.61 43 43.00 0.00 2.24 -6.59 145.02 44 44.00 0.00 2.24 -6.59 138.42 45 45.00 0.00 2.24 -6.59 131.83 46 46.00 0.00 2.24 -6.59 125.24 47 47.00 0.00 2.24 -6.59 118.65 48 48.00 0.00 2.24 -6.59 112.06 49 49.00 0.00 2.24 -6.59 105.47 50 50.00 0.00 2.24 -6.59 98.87 51 51.00 0.00 2.24 -6.59 92.28 52 52.00 0.00 2.24 -6.59 85.69 53 53.00 0.00 2.24 -6.59 79.10 Rivanna Engineering&Surveying,PLC Page 59 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Pre-Development Hydrograph Report Name: DA-Fontana, 2yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 32.05 (cfs) Time to Peak (Tp) = 16.00 (min) Time of Base (Tb) = 40.00 (min) Volume = 0.88 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 0.88 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef <None> Overall Approximation 32.85 NA 0.30 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 16.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 0.86 (in) Return Period = 2 (yr) Storm Duration = 0.27 (hr) Rivanna Engineering&Surveying,PLC Page 60 (434)984-1599 Luxor Subdivision Stormwater Management Pond #1 Pre-Development Hydrograph Report DA-Fontana, 2yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.05 0.00 2.00 2 2.00 0.05 0.11 2.00 4.01 3 3.00 0.05 0.16 2.00 6.01 4 4.00 0.05 0.22 2.00 8.01 5 5.00 0.05 0.27 2.00 10.01 6 6.00 0.05 0.32 2.00 12.02 7 7.00 0.05 0.38 2.00 14.02 8 8.00 0.05 0.43 2.00 16.02 9 9.00 0.05 0.48 2.00 18.03 10 10.00 0.05 0.54 2.00 20.03 11 11.00 0.05 0.59 2.00 22.03 12 12.00 0.05 0.65 2.00 24.04 13 13.00 0.05 0.70 2.00 26.04 14 14.00 0.05 0.75 2.00 28.04 15 15.00 0.05 0.81 2.00 30.04 16 16.00 0.05 0.86 2.00 32.05 17 17.00 0.00 0.86 -1.34 30.71 18 18.00 0.00 0.86 -1.34 29.38 19 19.00 0.00 0.86 -1.34 28.04 20 20.00 0.00 0.86 -1.34 26.71 21 21.00 0.00 0.86 -1.34 25.37 22 22.00 0.00 0.86 -1.34 24.04 23 23.00 0.00 0.86 -1.34 22.70 24 24.00 0.00 0.86 -1.34 21.36 25 25.00 0.00 0.86 -1.34 20.03 26 26.00 0.00 0.86 -1.34 18.69 27 27.00 0.00 0.86 -1.34 17.36 28 28.00 0.00 0.86 -1.34 16.02 29 29.00 0.00 0.86 -1.34 14.69 30 30.00 0.00 0.86 -1.34 13.35 31 31.00 0.00 0.86 -1.34 12.02 32 32.00 0.00 0.86 -1.34 10.68 33 33.00 0.00 0.86 -1.34 9.35 34 34.00 0.00 0.86 -1.34 8.01 35 35.00 0.00 0.86 -1.34 6.68 36 36.00 0.00 0.86 -1.34 5.34 37 37.00 0.00 0.86 -1.34 4.01 38 38.00 0.00 0.86 -1.34 2.67 39 39.00 0.00 0.86 -1.34 1.34 40 40.00 0.00 0.86 -1.34 0.00 Rivanna Engineering&Surveying,PLC Page 61 (434)984-1599 Luxor Subdivision Stormwater Management Pond #1 Pre-Development Hydrograph Report Name: DA-Fontana, l0yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 45.35 (cfs) Time to Peak (Tp) = 16.00 (min) Time of Base (Tb) = 40.00 (min) Volume = 1.25 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 1.25 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef <None> Overall Approximation 32.85 NA 0.30 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 16.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 1.22 (in) Return Period = User Defined (yr) Storm Duration = 0.27 (hr) Rivanna Engineering&Surveying,PLC Page 62 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Pre-Development Hydrograph Report DA-Fontana, l0yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.08 0.00 2.83 2 2.00 0.08 0.15 2.83 5.67 3 3.00 0.08 0.23 2.83 8.50 4 4.00 0.08 0.30 2.83 11.34 5 5.00 0.08 0.38 2.83 14.17 6 6.00 0.08 0.46 2.83 17.01 7 7.00 0.08 0.53 2.83 19.84 8 8.00 0.08 0.61 2.83 22.67 9 9.00 0.08 0.68 2.83 25.51 10 10.00 0.08 0.76 2.83 28.34 11 11.00 0.08 0.84 2.83 31.18 12 12.00 0.08 0.91 2.83 34.01 13 13.00 0.08 0.99 2.83 36.84 14 14.00 0.08 1.06 2.83 39.68 15 15.00 0.08 1.14 2.83 42.51 16 16.00 0.08 1.22 2.83 45.35 17 17.00 0.00 1.22 -1.89 43.46 18 18.00 0.00 1.22 -1.89 41.57 19 19.00 0.00 1.22 -1.89 39.68 20 20.00 0.00 1.22 -1.89 37.79 21 21.00 0.00 1.22 -1.89 35.90 22 22.00 0.00 1.22 -1.89 34.01 23 23.00 0.00 1.22 -1.89 32.12 24 24.00 0.00 1.22 -1.89 30.23 25 25.00 0.00 1.22 -1.89 28.34 26 26.00 0.00 1.22 -1.89 26.45 27 27.00 0.00 1.22 -1.89 24.56 28 28.00 0.00 1.22 -1.89 22.67 29 29.00 0.00 1.22 -1.89 20.78 30 30.00 0.00 1.22 -1.89 18.89 31 31.00 0.00 1.22 -1.89 17.01 32 32.00 0.00 1.22 -1.89 15.12 33 33.00 0.00 1.22 -1.89 13.23 34 34.00 0.00 1.22 -1.89 11.34 35 35.00 0.00 1.22 -1.89 9.45 36 36.00 0.00 1.22 -1.89 7.56 37 37.00 0.00 1.22 -1.89 5.67 38 38.00 0.00 1.22 -1.89 3.78 39 39.00 0.00 1.22 -1.89 1.89 40 40.00 0.00 1.22 -1.89 0.00 Rivanna Engineering&Surveying,PLC Page 63 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Pre-Development Hydrograph Report Name: DA-Fontana, 100yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 65.68 (cfs) Time to Peak (Tp) = 16.00 (min) Time of Base (Tb) = 40.00 (min) Volume = 1.81 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 1.81 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef <None> Overall Approximation 32.90 NA 0.30 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 16.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 1.76 (in) Return Period = 100 (yr) Storm Duration = 0.27 (hr) Rivanna Engineering&Surveying,PLC Page 64 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Pre-Development Hydrograph Report DA-Fontana, 100yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.11 0.00 4.10 2 2.00 0.11 0.22 4.10 8.21 3 3.00 0.11 0.33 4.10 12.31 4 4.00 0.11 0.44 4.10 16.42 5 5.00 0.11 0.55 4.10 20.52 6 6.00 0.11 0.66 4.10 24.63 7 7.00 0.11 0.77 4.10 28.73 8 8.00 0.11 0.88 4.10 32.84 9 9.00 0.11 0.99 4.10 36.94 10 10.00 0.11 1.10 4.10 41.05 11 11.00 0.11 1.21 4.10 45.15 12 12.00 0.11 1.32 4.10 49.26 13 13.00 0.11 1.43 4.10 53.36 14 14.00 0.11 1.54 4.10 57.47 15 15.00 0.11 1.65 4.10 61.57 16 16.00 0.11 1.76 4.10 65.68 17 17.00 0.00 1.76 -2.74 62.94 18 18.00 0.00 1.76 -2.74 60.20 19 19.00 0.00 1.76 -2.74 57.47 20 20.00 0.00 1.76 -2.74 54.73 21 21.00 0.00 1.76 -2.74 51.99 22 22.00 0.00 1.76 -2.74 49.26 23 23.00 0.00 1.76 -2.74 46.52 24 24.00 0.00 1.76 -2.74 43.78 25 25.00 0.00 1.76 -2.74 41.05 26 26.00 0.00 1.76 -2.74 38.31 27 27.00 0.00 1.76 -2.74 35.57 28 28.00 0.00 1.76 -2.74 32.84 29 29.00 0.00 1.76 -2.74 30.10 30 30.00 0.00 1.76 -2.74 27.36 31 31.00 0.00 1.76 -2.74 24.63 32 32.00 0.00 1.76 -2.74 21.89 33 33.00 0.00 1.76 -2.74 19.16 34 34.00 0.00 1.76 -2.74 16.42 35 35.00 0.00 1.76 -2.74 13.68 36 36.00 0.00 1.76 -2.74 10.95 37 37.00 0.00 1.76 -2.74 8.21 38 38.00 0.00 1.76 -2.74 5.47 39 39.00 0.00 1.76 -2.74 2.74 40 40.00 0.00 1.76 -2.74 0.00 Rivanna Engineering&Surveying,PLC Page 65 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Post-Development Hydrograph Report Name: DA-1, Post 2yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 73.23 (cfs) Time to Peak (Tp) = 20.00 (min) Time of Base (Tb) = 50.00 (min) Volume = 2.52 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 2.52 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef Townhomes 3.20 0 0.75 Commercial 21.20 0 0.85 Undeveloped (Steep) 7.20 0 0.35 Existing Fontana 2.20 0 0.50 Town & Country 2.15 0 0.70 Overall Approximation 35.95 NA 0.71 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 20.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 0.95 (in) Return Period = 2 (yr) Storm Duration = 0.33 (hr) Rivanna Engineering&Surveying, PLC Page 66 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Post-Development Hydrograph Report DA-1, Post 2yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.05 0.00 3.66 2 2.00 0.05 0.09 3.66 7.32 3 3.00 0.05 0.14 3.66 10.98 4 4.00 0.05 0.19 3.66 14.65 5 5.00 0.05 0.24 3.66 18.31 6 6.00 0.05 0.28 3.66 21.97 7 7.00 0.05 0.33 3.66 25.63 8 8.00 0.05 0.38 3.66 29.29 9 9.00 0.05 0.43 3.66 32.95 10 10.00 0.05 0.47 3.66 36.62 11 11.00 0.05 0.52 3.66 40.28 12 12.00 0.05 0.57 3.66 43.94 13 13.00 0.05 0.62 3.66 47.60 14 14.00 0.05 0.66 3.66 51.26 15 15.00 0.05 0.71 3.66 54.92 16 16.00 0.05 0.76 3.66 58.58 17 17.00 0.05 0.81 3.66 62.25 18 18.00 0.05 0.85 3.66 65.91 19 19.00 0.05 0.90 3.66 69.57 20 20.00 0.05 0.95 3.66 73.23 21 21.00 0.00 0.95 -2.44 70.79 22 22.00 0.00 0.95 -2.44 68.35 23 23.00 0.00 0.95 -2.44 65.91 24 24.00 0.00 0.95 -2.44 63.47 25 25.00 0.00 0.95 -2.44 61.03 26 26.00 0.00 0.95 -2.44 58.58 27 27.00 0.00 0.95 -2.44 56.14 28 28.00 0.00 0.95 -2.44 53.70 29 29.00 0.00 0.95 -2.44 51.26 30 30.00 0.00 0.95 -2.44 48.82 31 31.00 0.00 0.95 -2.44 46.38 32 32.00 0.00 0.95 -2.44 43.94 33 33.00 0.00 0.95 -2.44 41.50 34 34.00 0.00 0.95 -2.44 39.06 35 35.00 0.00 0.95 -2.44 36.62 36 36.00 0.00 0.95 -2.44 34.17 37 37.00 0.00 0.95 -2.44 31.73 38 38.00 0.00 0.95 -2.44 29.29 39 39.00 0.00 0.95 -2.44 26.85 40 40.00 0.00 0.95 -2.44 24.41 41 41.00 0.00 0.95 -2.44 21.97 42 42.00 0.00 0.95 -2.44 19.53 43 43.00 0.00 0.95 -2.44 17.09 44 44.00 0.00 0.95 -2.44 14.65 45 45.00 0.00 0.95 -2.44 12.21 46 46.00 0.00 0.95 -2.44 9.76 47 47.00 0.00 0.95 -2.44 7.32 48 48.00 0.00 0.95 -2.44 4.88 49 49.00 0.00 0.95 -2.44 2.44 50 50.00 0.00 0.95 -2.44 0.00 Rivanna Engineering&Surveying,PLC Page 67 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Post-Development Hydrograph Report Name: DA-1, Post l0yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow ((p) = 104.88 (cfs) Time to Peak (Tp) = 20.00 (min) Time of Base (Tb) = 50.00 (min) Volume = 3.61 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 3.61 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef Townhomes 3.20 0 0.75 Commercial 21.20 0 0.85 Undeveloped (Steep) 7.20 0 0.35 Existing Fontana 2.20 0 0.50 Town & Country 2.15 0 0.70 Overall Approximation 35.95 NA 0.71 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 20.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 1.36 (in) Return Period = User Defined (yr) Storm Duration = 0.33 (hr) Rivanna Engineering&Surveying,PLC Page 68 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Post-Development Hydrograph Report DA-1, Post l0yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.07 0.00 5.24 2 2.00 0.07 0.14 5.24 10.49 3 3.00 0.07 0.20 5.24 15.73 4 4.00 0.07 0.27 5.24 20.98 5 5.00 0.07 0.34 5.24 26.22 6 6.00 0.07 0.41 5.24 31.46 7 7.00 0.07 0.48 5.24 36.71 8 8.00 0.07 0.54 5.24 41.95 9 9.00 0.07 0.61 5.24 47.19 10 10.00 0.07 0.68 5.24 52.44 11 11.00 0.07 0.75 5.24 57.68 12 12.00 0.07 0.81 5.24 62.93 13 13.00 0.07 0.88 5.24 68.17 14 14.00 0.07 0.95 5.24 73.41 15 15.00 0.07 1.02 5.24 78.66 16 16.00 0.07 1.09 5.24 83.90 17 17.00 0.07 1.15 5.24 89.14 18 18.00 0.07 1.22 5.24 94.39 19 19.00 0.07 1.29 5.24 99.63 20 20.00 0.07 1.36 5.24 104.88 21 21.00 0.00 1.36 -3.50 101.38 22 22.00 0.00 1.36 -3.50 97.88 23 23.00 0.00 1.36 -3.50 94.39 24 24.00 0.00 1.36 -3.50 90.89 25 25.00 0.00 1.36 -3.50 87.40 26 26.00 0.00 1.36 -3.50 83.90 27 27.00 0.00 1.36 -3.50 80.41 28 28.00 0.00 1.36 -3.50 76.91 29 29.00 0.00 1.36 -3.50 73.41 30 30.00 0.00 1.36 -3.50 69.92 31 31.00 0.00 1.36 -3.50 66.42 32 32.00 0.00 1.36 -3.50 62.93 33 33.00 0.00 1.36 -3.50 59.43 34 34.00 0.00 1.36 -3.50 55.93 35 35.00 0.00 1.36 -3.50 52.44 36 36.00 0.00 1.36 -3.50 48.94 37 37.00 0.00 1.36 -3.50 45.45 38 38.00 0.00 1.36 -3.50 41.95 39 39.00 0.00 1.36 -3.50 38.45 40 40.00 0.00 1.36 -3.50 34.96 41 41.00 0.00 1.36 -3.50 31.46 42 42.00 0.00 1.36 -3.50 27.97 43 43.00 0.00 1.36 -3.50 24.47 44 44.00 0.00 1.36 -3.50 20.98 45 45.00 0.00 1.36 -3.50 17.48 46 46.00 0.00 1.36 -3.50 13.98 47 47.00 0.00 1.36 -3.50 10.49 48 48.00 0.00 1.36 -3.50 6.99 49 49.00 0.00 1.36 -3.50 3.50 50 50.00 0.00 1.36 -3.50 0.00 Rivanna Engineering&Surveying,PLC Page 69 (434)984-1599 Luxor Subdivision Stormwater Management Pond #1 Post-Development Hydrograph Report Name: DA-1, Post 100yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 152.74 (cfs) Time to Peak (Tp) = 20.00 (min) Time of Base (Tb) = 50.00 (min) Volume = 5.26 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 5.26 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef Townhomes 3.20 0 0.75 Commercial 21.20 0 0.85 Undeveloped (Steep) 7.20 0 0.35 Existing Fontana 2.20 0 0.50 Town & Country 2.15 0 0.70 Overall Approximation 35.95 NA 0.71 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 20.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 1.98 (in) Return Period = 100 (yr) Storm Duration = 0.33 (hr) Rivanna Engineering&Surveying,PLC Page 70 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Post-Development Hydrograph Report DA-1, Post 100yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.10 0.00 7.64 2 2.00 0.10 0.20 7.64 15.27 3 3.00 0.10 0.30 7.64 22.91 4 4.00 0.10 0.40 7.64 30.55 5 5.00 0.10 0.49 7.64 38.19 6 6.00 0.10 0.59 7.64 45.82 7 7.00 0.10 0.69 7.64 53.46 8 8.00 0.10 0.79 7.64 61.10 9 9.00 0.10 0.89 7.64 68.73 10 10.00 0.10 0.99 7.64 76.37 11 11.00 0.10 1.09 7.64 84.01 12 12.00 0.10 1.19 7.64 91.64 13 13.00 0.10 1.28 7.64 99.28 14 14.00 0.10 1.38 7.64 106.92 15 15.00 0.10 1.48 7.64 114.56 16 16.00 0.10 1.58 7.64 122.19 17 17.00 0.10 1.68 7.64 129.83 18 18.00 0.10 1.78 7.64 137.47 19 19.00 0.10 1.88 7.64 145.10 20 20.00 0.10 1.98 7.64 152.74 21 21.00 0.00 1.98 -5.09 147.65 22 22.00 0.00 1.98 -5.09 142.56 23 23.00 0.00 1.98 -5.09 137.47 24 24.00 0.00 1.98 -5.09 132.37 25 25.00 0.00 1.98 -5.09 127.28 26 26.00 0.00 1.98 -5.09 122.19 27 27.00 0.00 1.98 -5.09 117.10 28 28.00 0.00 1.98 -5.09 112.01 29 29.00 0.00 1.98 -5.09 106.92 30 30.00 0.00 1.98 -5.09 101.83 31 31.00 0.00 1.98 -5.09 96.74 32 32.00 0.00 1.98 -5.09 91.64 33 33.00 0.00 1.98 -5.09 86.55 34 34.00 0.00 1.98 -5.09 81.46 35 35.00 0.00 1.98 -5.09 76.37 36 36.00 0.00 1.98 -5.09 71.28 37 37.00 0.00 1.98 -5.09 66.19 38 38.00 0.00 1.98 -5.09 61.10 39 39.00 0.00 1.98 -5.09 56.00 40 40.00 0.00 1.98 -5.09 50.91 41 41.00 0.00 1.98 -5.09 45.82 42 42.00 0.00 1.98 -5.09 40.73 43 43.00 0.00 1.98 -5.09 35.64 44 44.00 0.00 1.98 -5.09 30.55 45 45.00 0.00 1.98 -5.09 25.46 46 46.00 0.00 1.98 -5.09 20.37 47 47.00 0.00 1.98 -5.09 15.27 48 48.00 0.00 1.98 -5.09 10.18 49 49.00 0.00 1.98 -5.09 5.09 50 50.00 0.00 1.98 -5.09 0.00 Rivanna Engineering&Surveying,PLC Page 71 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Post-Development Hydrograph Report Name: DA-Fontana Pond, 2yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 55.32 (cfs) Time to Peak (Tp) = 15.00 (min) Time of Base (Tb) = 37.50 (min) Volume = 1.43 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 1.43 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef 1/2acre Lots 32.85 0 0.50 Overall Approximation 32.85 NA 0.50 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 15.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 0.84 (in) Return Period = 2 (yr) Storm Duration = 0.25 (hr) Rivanna Engineering&Surveying,PLC Page 72 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Post-Development Hydrograph Report DA-Fontana Pond, 2yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.06 0.00 3.69 2 2.00 0.06 0.11 3.69 7.38 3 3.00 0.06 0.17 3.69 11.06 4 4.00 0.06 0.22 3.69 14.75 5 5.00 0.06 0.28 3.69 18.44 6 6.00 0.06 0.33 3.69 22.13 7 7.00 0.06 0.39 3.69 25.82 8 8.00 0.06 0.45 3.69 29.50 9 9.00 0.06 0.50 3.69 33.19 10 10.00 0.06 0.56 3.69 36.88 11 11.00 0.06 0.61 3.69 40.57 12 12.00 0.06 0.67 3.69 44.26 13 13.00 0.06 0.72 3.69 47.94 14 14.00 0.06 0.78 3.69 51.63 15 15.00 0.06 0.84 3.69 55.32 16 16.00 0.00 0.84 -2.46 52.86 17 17.00 0.00 0.84 -2.46 50.40 18 18.00 0.00 0.84 -2.46 47.94 19 19.00 0.00 0.84 -2.46 45.49 20 20.00 0.00 0.84 -2.46 43.03 21 21.00 0.00 0.84 -2.46 40.57 22 22.00 0.00 0.84 -2.46 38.11 23 23.00 0.00 0.84 -2.46 35.65 24 24.00 0.00 0.84 -2.46 33.19 25 25.00 0.00 0.84 -2.46 30.73 26 26.00 0.00 0.84 -2.46 28.28 27 27.00 0.00 0.84 -2.46 25.82 28 28.00 0.00 0.84 -2.46 23.36 29 29.00 0.00 0.84 -2.46 20.90 30 30.00 0.00 0.84 -2.46 18.44 31 31.00 0.00 0.84 -2.46 15.98 32 32.00 0.00 0.84 -2.46 13.52 33 33.00 0.00 0.84 -2.46 11.06 34 34.00 0.00 0.84 -2.46 8.61 35 35.00 0.00 0.84 -2.46 6.15 36 36.00 0.00 0.84 -2.46 3.69 37 37.00 0.00 0.84 -2.46 1.23 38 37.50 0.00 0.84 -1.23 0.00 Rivanna Engineering&Surveying,PLC Page 73 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Post-Development Hydrograph Report Name: DA-Fontana Pond, l0yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 77.98 (cfs) Time to Peak (Tp) = 15.00 (min) Time of Base (Tb) = 37.50 (min) Volume = 2.01 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 2.01 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef 1/2acre Lots 32.85 0 0.50 Overall Approximation 32.85 NA 0.50 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 15.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 1.18 (in) Return Period = User Defined (yr) Storm Duration = 0.25 (hr) Rivanna Engineering&Surveying,PLC Page 74 (434)984-1599 Luxor Subdivision Stormwater Management Pond #1 Post-Development Hydrograph Report DA-Fontana Pond, l0yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.08 0.00 5.20 2 2.00 0.08 0.16 5.20 10.40 3 3.00 0.08 0.24 5.20 15.60 4 4.00 0.08 0.31 5.20 20.80 5 5.00 0.08 0.39 5.20 25.99 6 6.00 0.08 0.47 5.20 31.19 7 7.00 0.08 0.55 5.20 36.39 8 8.00 0.08 0.63 5.20 41.59 9 9.00 0.08 0.71 5.20 46.79 10 10.00 0.08 0.78 5.20 51.99 11 11.00 0.08 0.86 5.20 57.19 12 12.00 0.08 0.94 5.20 62.39 13 13.00 0.08 1.02 5.20 67.59 14 14.00 0.08 1.10 5.20 72.78 15 15.00 0.08 1.18 5.20 77.98 16 16.00 0.00 1.18 -3.47 74.52 17 17.00 0.00 1.18 -3.47 71.05 18 18.00 0.00 1.18 -3.47 67.59 19 19.00 0.00 1.18 -3.47 64.12 20 20.00 0.00 1.18 -3.47 60.65 21 21.00 0.00 1.18 -3.47 57.19 22 22.00 0.00 1.18 -3.47 53.72 23 23.00 0.00 1.18 -3.47 50.26 24 24.00 0.00 1.18 -3.47 46.79 25 25.00 0.00 1.18 -3.47 43.32 26 26.00 0.00 1.18 -3.47 39.86 27 27.00 0.00 1.18 -3.47 36.39 28 28.00 0.00 1.18 -3.47 32.93 29 29.00 0.00 1.18 -3.47 29.46 30 30.00 0.00 1.18 -3.47 25.99 31 31.00 0.00 1.18 -3.47 22.53 32 32.00 0.00 1.18 -3.47 19.06 33 33.00 0.00 1.18 -3.47 15.60 34 34.00 0.00 1.18 -3.47 12.13 35 35.00 0.00 1.18 -3.47 8.66 36 36.00 0.00 1.18 -3.47 5.20 37 37.00 0.00 1.18 -3.47 1.73 38 37.50 0.00 1.18 -1.73 0.00 Rivanna Engineering&Surveying,PLC Page 75 (434)984-1599 Luxor Subdivision Stormwater Management Pond #1 Post-Development Hydrograph Report Name: DA-Fontana Pond, 10Oyr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 112.52 (cfs) Time to Peak (Tp) = 15.00 (min) Time of Base (Tb) = 37.50 (min) Volume = 2.91 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 2.91 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef 1/2acre Lots 32.85 0 0.50 Overall Approximation 32.85 NA 0.50 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 15.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 1.70 (in) Return Period = 100 (yr) Storm Duration = 0.25 (hr) Rivanna Engineering&Surveying,PLC Page 76 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Post-Development Hydrograph Report DA-Fontana Pond, 100yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.11 0.00 7.50 2 2.00 0.11 0.23 7.50 15.00 3 3.00 0.11 0.34 7.50 22.50 4 4.00 0.11 0.45 7.50 30.00 5 5.00 0.11 0.57 7.50 37.51 6 6.00 0.11 0.68 7.50 45.01 7 7.00 0.11 0.79 7.50 52.51 8 8.00 0.11 0.91 7.50 60.01 9 9.00 0.11 1.02 7.50 67.51 10 10.00 0.11 1.13 7.50 75.01 11 11.00 0.11 1.25 7.50 82.51 12 12.00 0.11 1.36 7.50 90.01 13 13.00 0.11 1.47 7.50 97.51 14 14.00 0.11 1.59 7.50 105.01 15 15.00 0.11 1.70 7.50 112.52 16 16.00 0.00 1.70 -5.00 107.52 17 17.00 0.00 1.70 -5.00 102.51 18 18.00 0.00 1.70 -5.00 97.51 19 19.00 0.00 1.70 -5.00 92.51 20 20.00 0.00 1.70 -5.00 87.51 21 21.00 0.00 1.70 -5.00 82.51 22 22.00 0.00 1.70 -5.00 77.51 23 23.00 0.00 1.70 -5.00 72.51 24 24.00 0.00 1.70 -5.00 67.51 25 25.00 0.00 1.70 -5.00 62.51 26 26.00 0.00 1.70 -5.00 57.51 27 27.00 0.00 1.70 -5.00 52.51 28 28.00 0.00 1.70 -5.00 47.51 29 29.00 0.00 1.70 -5.00 42.51 30 30.00 0.00 1.70 -5.00 37.51 31 31.00 0.00 1.70 -5.00 32.50 32 32.00 0.00 1.70 -5.00 27.50 33 33.00 0.00 1.70 -5.00 22.50 34 34.00 0.00 1.70 -5.00 17.50 35 35.00 0.00 1.70 -5.00 12.50 36 36.00 0.00 1.70 -5.00 7.50 37 37.00 0.00 1.70 -5.00 2.50 38 37.50 0.00 1.70 -2.50 0.00 Rivanna Engineering&Surveying,PLC Page 77 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Combined Hydrograph Report Name: DA-Fontana Pond & DA-1 & SWM2, 2yr Type: Combined [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 160.26 (cfs) Time to Peak (Tp) = 20.00 (min) Time of Base (Tb) = 1297.00 (min) Volume = 11.51 (ac-ft) Time Step = 1.00 (min) [COMBINED HYDROGRAPH RECORDS] Name: DA-Fontana Pond, 2yr Type: Modified Rational Peak Flow (Qp) = 55.32 (cfs) Time to Peak (Tp) = 15.00 (min) Time Step = 1.00 (min) Name: DA-1, Post 2yr Type: Modified Rational Peak Flow (Qp) = 73.23 (cfs) Time to Peak (Tp) = 20.00 (min) Time Step = 1.00 (min) Name: SWM2, 2yr Type: Reservoir: Modified Puls Peak Flow (Qp) = 61.28 (cfs) Time to Peak (Tp) = 48.00 (min) Time Step = 1.00 (min) [Combined Hydrograph Flow Values] Interval Time Outflow (min) (cfs) 1 1.00 7.45 2 2.00 15.08 3 3.00 22.91 4 4.00 30.92 5 5.00 39.10 6 6.00 47.47 7 7.00 56.08 8 8.00 64.89 9 9.00 73.87 10 10.00 83.03 11 11.00 92.34 12 12.00 102.32 13 13.00 112.54 14 14.00 122.91 15 15.00 133.52 16 16.00 138.50 17 17.00 143.61 18 18.00 148.81 19 19.00 154.48 20 20.00 160.26 21 21.00 160.01 22 22.00 158.22 23 23.00 155.90 24 24.00 153.69 25 25.00 149.77 Rivanna Engineering&Surveying,PLC Page 78 (434)984-1599 Luxor Subdivision Stormwater Management Pond #1 Combined Hydrograph Report DA-Fontana Pond & DA-1 & SWM2, 2yr [Combined Hydrograph Flow Values] Interval Time Outflow (min) (cfs) 26 26.00 145.15 27 27.00 140.52 28 28.00 135.87 29 29.00 131.21 30 30.00 126.54 31 31.00 121.86 32 32.00 117.16 33 33.00 112.45 34 34.00 107.73 35 35.00 102.99 36 36.00 98.24 37 37.00 93.48 38 38.00 89.94 39 39.00 87.61 40 40.00 85.27 41 41.00 82.92 42 42.00 80.56 43 43.00 78.18 44 44.00 75.79 45 45.00 73.40 46 46.00 70.99 47 47.00 68.57 48 48.00 66.13 49 49.00 63.69 50 50.00 61.24 51 51.00 61.21 52 52.00 61.18 53 53.00 61.13 54 54.00 61.07 55 55.00 61.00 56 56.00 60.92 57 57.00 60.83 58 58.00 60.72 59 59.00 60.61 60 60.00 60.48 61 61.00 60.35 62 62.00 60.20 63 63.00 60.04 64 64.00 59.88 65 65.00 59.72 66 66.00 59.56 67 67.00 59.40 68 68.00 59.24 69 69.00 59.07 70 70.00 58.91 71 71.00 58.75 72 72.00 58.58 73 73.00 58.42 74 74.00 58.25 75 75.00 58.09 76 76.00 57.92 77 77.00 57.29 78 78.00 55.67 79 79.00 54.10 Rivanna Engineering&Surveying,PLC Page 79 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Combined Hydrograph Report Name: DA-Fontana Pond & DA-1 & SWM2, 10yr Type: Combined [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 223.47 (cfs) Time to Peak (Tp) = 20.00 (min) Time of Base (Tb) = 1319.00 (min) Volume = 16.49 (ac-ft) Time Step = 1.00 (min) [COMBINED HYDROGRAPH RECORDS] Name: DA-Fontana Pond, l0yr Type: Modified Rational Peak Flow (Qp) = 77.98 (cfs) Time to Peak (Tp) = 15.00 (min) Time Step = 1.00 (min) Name: DA-1, Post l0yr Type: Modified Rational Peak Flow (Qp) = 104.88 (cfs) Time to Peak (Tp) = 20.00 (min) Time Step = 1.00 (min) Name: SWM2, l0yr Type: Reservoir: Modified Puls Peak Flow (Qp) = 66.20 (cfs) Time to Peak (Tp) = 53.00 (min) Time Step = 1.00 (min) [Combined Hydrograph Flow Values] Interval Time Outflow (min) (cfs) 1 1.00 10.58 2 2.00 21.44 3 3.00 32.57 4 4.00 43.97 5 5.00 55.62 6 6.00 67.63 7 7.00 79.92 8 8.00 92.47 9 9.00 105.27 10 10.00 118.88 11 11.00 132.88 12 12.00 147.13 13 13.00 162.10 14 14.00 177.39 15 15.00 192.98 16 16.00 200.50 17 17.00 208.20 18 18.00 214.13 19 19.00 219.29 20 20.00 223.47 21 21.00 216.88 22 22.00 210.33 23 23.00 203.79 24 24.00 197.27 25 25.00 190.78 Rivanna Engineering&Surveying, PLC Page 80 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Combined Hydrograph Report DA-Fontana Pond & DA-1 & SWM2, 10yr [Combined Hydrograph Flow Values] Interval Time Outflow (min) (cfs) 26 26.00 184.28 27 27.00 177.77 28 28.00 171.23 29 29.00 164.67 30 30.00 158.09 31 31.00 151.50 32 32.00 144.88 33 33.00 138.25 34 34.00 131.59 35 35.00 124.92 36 36.00 118.23 37 37.00 111.52 38 38.00 106.53 39 39.00 103.25 40 40.00 99.95 41 41.00 96.64 42 42.00 93.31 43 43.00 89.96 44 44.00 86.60 45 45.00 83.22 46 46.00 79.83 47 47.00 76.42 48 48.00 73.00 49 49.00 69.56 50 50.00 66.11 51 51.00 66.14 52 52.00 66.15 53 53.00 66.15 54 54.00 66.14 55 55.00 66.11 56 56.00 66.07 57 57.00 66.01 58 58.00 65.94 59 59.00 65.86 60 60.00 65.76 61 61.00 65.64 62 62.00 65.52 63 63.00 65.38 64 64.00 65.24 65 65.00 65.09 66 66.00 64.95 67 67.00 64.81 68 68.00 64.66 69 69.00 64.52 70 70.00 64.37 71 71.00 64.22 72 72.00 64.07 73 73.00 63.92 74 74.00 63.77 75 75.00 63.62 76 76.00 63.47 77 77.00 63.32 78 78.00 63.17 79 79.00 63.02 Rivanna Engineering&Surveying,PLC Page 81 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Combined Hydrograph Report Name: DA-Fontana Pond & DA-1 & SWM2, 100yr Type: Combined [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 300.24 (cfs) Time to Peak (Tp) = 20.00 (min) Time of Base (Tb) = 1332.00 (min) Volume = 24.03 (ac-ft) Time Step = 1.00 (min) [COMBINED HYDROGRAPH RECORDS] Name: SWM2, 100yr Type: Reservoir: Modified Puls Peak Flow (Qp) = 73.24 (cfs) Time to Peak (Tp) = 55.00 (min) Time Step = 1.00 (min) Name: DA-Fontana Pond, 100yr Type: Modified Rational Peak Flow (Qp) = 112.52 (cfs) Time to Peak (Tp) = 15.00 (min) Time Step = 1.00 (min) Name: DA-1, Post 100yr Type: Modified Rational Peak Flow (Qp) = 152.74 (cfs) Time to Peak (Tp) = 20.00 (min) Time Step = 1.00 (min) [Combined Hydrograph Flow Values] Interval Time Outflow (min) (cfs) 1 1.00 15.34 2 2.00 31.09 3 3.00 47.23 4 4.00 63.77 5 5.00 80.79 6 6.00 98.24 7 7.00 116.08 8 8.00 134.68 9 9.00 154.16 10 10.00 174.05 11 11.00 195.04 12 12.00 216.39 13 13.00 238.66 14 14.00 261.32 15 15.00 280.88 16 16.00 287.56 17 17.00 290.68 18 18.00 293.83 19 19.00 297.02 20 20.00 300.24 21 21.00 290.76 22 22.00 281.32 23 23.00 271.91 24 24.00 262.53 25 25.00 253.17 Rivanna Engineering&Surveying,PLC Page 82 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Combined Hydrograph Report DA-Fontana Pond & DA-1 & SWM2, 1O0yr [Combined Hydrograph Flow Values] Interval Time Outflow (min) (cfs) 26 26.00 243.80 27 27.00 234.41 28 28.00 224.98 29 29.00 215.52 30 30.00 206.03 31 31.00 196.51 32 32.00 186.95 33 33.00 177.37 34 34.00 167.75 35 35.00 158.11 36 36.00 148.44 37 37.00 138.74 38 38.00 131.51 39 39.00 126.75 40 40.00 121.97 41 41.00 117.16 42 42.00 112.32 43 43.00 107.47 44 44.00 102.59 45 45.00 97.70 46 46.00 92.78 47 47.00 87.85 48 48.00 82.90 49 49.00 77.92 50 50.00 72.93 51 51.00 73.02 52 52.00 73.09 53 53.00 73.13 54 54.00 73.17 55 55.00 73.18 56 56.00 73.18 57 57.00 73.16 58 58.00 73.12 59 59.00 73.07 60 60.00 73.00 61 61.00 72.91 62 62.00 72.81 63 63.00 72.69 64 64.00 72.57 65 65.00 72.45 66 66.00 72.32 67 67.00 72.20 68 68.00 72.07 69 69.00 71.94 70 70.00 71.81 71 71.00 71.68 72 72.00 71.55 73 73.00 71.42 74 74.00 71.29 75 75.00 71.16 76 76.00 71.03 77 77.00 70.90 78 78.00 70.76 79 79.00 70.63 Rivanna Engineering&Surveying,PLC Page 83 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Outlet Structure Report Structure Number : 1 Type : Stand Pipe Name : SWM #1 Riser [RATING CURVE LIMIT] Minimum Elevation = 402.00 (ft) Maximum Elevation = 422.00 (ft) Elevation Increment = 0.25 (ft) [STAND PIPE INFORMATION] [ORIFICE INFORMATION] Diameter = 6.00 (ft) Crest Length = 1$_B5 (ft) Effective Crest Length = (i8.855)__ (ft) Orifice Coefficient = 0:70 r` Fractional Open Area = 0.83 11'. [ORIFICE EQUATION] Q = Co*A( (2gh)/k)^0.5 11 'Y'4, [DEFINITIONS] Co = Orifice Coefficient A = Wetted Area, (sq ft) [WEIR INFORMATION] Crest Elevation = 417.80 (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 [OPTIONAL ORIFICE INFORMATION] Structure Number : 1 Type : Rectangular Orifice [OPTIONAL ORIFICE INFORMATION] Height = 1.75 (ft) Width = 2.00 (ft) Invert Elevation = 415.00 (ft) Orifice Coefficient = 0.60 Number of Openings = 4 [ORIFICE EQUATION] Q = Co*A( (2gh)/k)^0.5 [DEFINITIONS] Co = Orifice Coefficient A = Wetted Area, (cfs) k = 1 Rivanna Engineering&Surveying,PLC Page 84 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Outlet Structure Report SWM #1 Riser [CULVERT INFORMATION] Type : Circular Concrete - Square Edge with Headwall [OUTLET STRUCTURE INFORMATION] Diameter = 60.00 (in) Invert Elevation = 402.00 (ft) Pipe Length = 150.00 (ft) Slope = 0.03 Manning's n Value = 0.01 Orifice Coefficient = 0.60 Tailwater Elevation = 0.00 (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 = 153.67 [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 = 175.62 [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) [STAND PIPE STAGE VS. DISCHARGE] Elevation Stage Weirs Orifices Stand Pipe Culvert Total (ft) (ft) (cfs) (cfs) (cfs) (cfs) (cfs) 415.00 13.00 0.00 0.00 0.00 306.81 0.00 415.50 13.50 0.00 9.63 0.00 314.60 9.63 416.00 14.00 0.00 27.23 0.00 322.21 27.23 416.50 14.50 0.00 50.02 0.00 329.64 50.02 417.00 15.00 0.00 71.47 0.00 336.90 71.47 417.50 15.50 0.00 85.90 0.00 344.02 85.90 418.00 16.00 0.00 98.23 5.61 350.99 103.84 418.50 16.50 0.00 109.17 36.76 357.82 145.93 419.00 17.00 0.00 119.12 82.51 364.52 201.63 419.50 17.50 0.00 128.29 138.30 371.11 266.59 420.00 18.00 0.00 136.85 181.67 377.58 318.52 420.50 18.50 0.00 144.91 216.53 383.94 361.44 421.00 19.00 0.00 152.54 235.73 390.19 388.27 421.50 19.50 0.00 159.81 253.48 396.35 396.35 422.00 20.00 0.00 166.76 270.06 402.41 402.41 Rivanna Engineering&Surveying,PLC Page 85 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Outlet Structure Report Reservoir Number: 1 Name: SWM Facility #1 [RATING CURVE LIMIT] Minimum Elevation = 402.00 (ft) Maximum Elevation = 422.00 (ft) Elevation Increment = 0.25 (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) 1 415.00 0.00 0.00 0.00 0.00 2 415.10 72051.00 36025.50 3602.55 3602.55 3 416.00 77362.00 74706.50 67235.85 70838.40 4 418.00 89904.00 83633.00 167266.00 238104.40 5 420.00 105457.00 97680.50 195361.00 433465.40 6 422.00 118650.00 112053.50 224107.00 657572.40 [DISCHARGE INFORMATION] Structure Number: 1 Type: Name: SWM #1 Riser [RESERVOIR STAGE STORAGE/DISCHARGE] Elevation Stage Area Storage Discharge (ft) (ft) (sq ft) (cu ft) (cfs) 415.00 13.00 0.00 0.00 0.00 415.50 13.50 74411.44 27535.47 9.63 416.00 14.00 77362.00 65478.83 27.23 416.50 14.50 80497.50 104943.71 50.02 417.00 15.00 83633.00 145976.33 71.47 417.50 15.50 86768.50 188576.71 85.90 418.00 16.00 89904.00 232744.83 103.84 418.50 16.50 93792.25 278668.90 145.93 419.00 17.00 97680.50 326537.08 201.63 419.50 17.50 101568.75 376349.40 266.59 420.00 18.00 105457.00 428105.83 318.52 420.50 18.50 108755.25 481658.90 361.44 421.00 19.00 112053.50 536861.08 388.27 421.50 19.50 115351.75 593712.40 396.35 422.00 20.00 118650.00 652212.83 402.41 Maximum Storage = 652212.83 (cu ft) Maximum Discharge = 402.41 (cfs) Rivanna Engineering&Surveying,PLC Page 86 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Routed Hydrograph Report Name: SWM1, 2yr Type: Reservoir: Modified Puls [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 76.29 (cfs) Time to Peak (Tp) = 44.00 (min) Time of Base (Tb) = 1380.00 (min) Volume = 11.51 (ac-ft) Time Step = 1.00 (min) Peak Elevation = 417.16 (ft) Detention Time = NA [RESERVOIR STRUCTURE INFORMATION] Name = SWM Facility #1 Storage Type = User-Defined Area Maximum Storage = 652212.83 (cu ft) Maximum Discharge = 402.41 (cfs) [INFLOW HYDROGRAPH INFORMATION] Name = DA-Fontana Pond & DA-1 & SWM2, 2yr Peak Flow (Qp) = 160.26 (cfs) Time to Peak (Tp) = 20.00 (min) Time of Base (Tb) = 1297.00 (min) Volume = 11.51 (ac-ft) Flow Multiplier = 1.00 [EQUATION] (I1+I2) + (2(S1)/dt)-Ol = (2(S2)/dt)+02 Where: I1 = Previous inflow I2 = Current inflow S1 = Previous storage S2 = Current storage dt = Time increment 01 = Previous outflow 02 = Current outflow A = (11 + I2) B = (2 (S1) / dt) - 01 C = (2 (S2) / dt) + 02 [Computation of Reservoir Outflow Table of Modified Puls Method] Intv Time Inflow A B C Outflow Storage Elev (min) (cfs) (cfs) (cfs) (cfs) (cfs) (cu ft) (ft) 1 1.00 7.45 7.45 0.00 441.74 0.08 220.91 415.01 2 2.00 15.08 22.53 441.74 1768.53 0.33 884.43 415.02 3 3.00 22.91 37.99 1768.53 3983.20 0.74 1991.97 415.05 4 4.00 30.92 53.82 3983.20 7088.09 1.32 3544.71 415.10 5 5.00 39.10 70.02 7088.09 11085.01 2.07 5543.54 415.15 6 6.00 47.47 86.57 11085.01 15975.28 2.98 7989.13 415.22 7 7.00 56.08 103.54 15975.28 21767.94 4.00 10885.97 415.27 8 8.00 64.89 120.97 21767.94 28476.71 5.13 14240.92 415.32 9 9.00 73.87 138.76 28476.71 36107.82 6.42 18057.12 415.37 10 10.00 83.03 156.90 36107.82 44662.97 7.87 22335.42 415.43 Rivanna Engineering&Surveying,PLC Page 87 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Routed Hydrograph Report SWM1, 2yr [Computation of Reservoir Outflow Table of Modified Puls Method] Intv Time Inflow A B C Outflow Storage Elev (min) (cfs) (cfs) (cfs) (cfs) (cfs) (cu ft) (ft) 11 11.00 92.34 175.37 44662.97 54143.30 9.47 27076.38 415.49 12 12.00 102.32 194.67 54143.30 64553.14 11.66 32282.40 415.56 13 13.00 112.54 214.86 64553.14 75897.05 14.10 37955.57 415.64 14 14.00 122.91 235.45 75897.05 88171.96 16.73 44094.34 415.72 15 15.00 133.52 256.43 88171.96 101359.12 19.86 50689.49 415.81 16 16.00 138.50 272.02 101359.12 115088.61 23.28 57555.94 415.90 17 17.00 143.61 282.11 115088.61 129010.05 26.75 64518.40 415.99 18 18.00 148.81 292.42 129010.05 143110.32 30.60 71570.46 416.08 19 19.00 154.48 303.29 143110.32 157394.27 34.56 78714.42 416.17 20 20.00 160.26 314.74 157394.27 171884.08 38.62 85961.35 416.26 21 21.00 160.01 320.27 171884.08 186203.60 42.92 93123.26 416.35 22 22.00 158.22 318.23 186203.60 199895.86 47.03 99971.45 416.44 23 23.00 155.90 314.12 199895.86 212857.73 50.99 106454.36 416.52 24 24.00 153.69 309.58 212857.73 225075.70 54.90 112565.30 416.59 25 25.00 149.77 303.45 225075.70 236472.41 58.55 118265.48 416.66 26 26.00 145.15 294.92 236472.41 246937.14 61.90 123499.52 416.73 27 27.00 140.52 285.67 246937.14 256505.18 64.26 128284.72 416.79 28 28.00 135.87 276.39 256505.18 265268.40 66.05 132667.22 416.84 29 29.00 131.21 267.09 265268.40 273268.47 67.68 136668.07 416.89 30 30.00 126.54 257.76 273268.47 280522.42 69.16 140295.79 416.93 31 31.00 121.86 248.40 280522.42 287046.73 70.48 143558.61 416.97 32 32.00 117.16 239.02 287046.73 292858.83 71.64 146465.24 417.01 33 33.00 112.45 229.61 292858.83 297982.09 72.56 149027.33 417.04 34 34.00 107.73 220.18 297982.09 302436.82 73.36 151255.09 417.06 35 35.00 102.99 210.72 302436.82 306235.67 74.04 153154.85 417.09 36 36.00 98.24 201.23 306235.67 309390.95 74.60 154732.77 417.10 37 37.00 93.48 . 191.72 309390.95 311914.79 75.05 155994.92 417.12 38 38.00 89.94 183.42 311914.79 313892.16 75.40 156983.78 417.13 39 39.00 87.61 177.55 313892.16 315479.17 75.69 157777.43 417.14 40 40.00 85.27 172.88 315479.17 316755.64 75.92 158415.78 417.15 41 41.00 82.92 168.19 316755.64 317726.68 76.09 158901.38 417.15 42 42.00 80.56 163.48 317726.68 318397.27 76.21 159236.74 417.16 43 43.00 78.18 158.74 318397.27 318772.35 76.28 159424.31 417.16 44 44.00 75.79 153.98 318772.35 318856.82 76.29 159466.56 417.16 45 45.00 73.40 149.19 318856.82 318655.51 76.26 159365.88 417.16 46 46.00 70.99 144.38 318655.51 318173.11 76.17 159124.64 417.16 47 47.00 68.57 139.55 318173.11 317414.24 76.03 158745.14 417.15 48 48.00 66.13 134.70 317414.24 316383.43 75.85 158229.64 417.15 49 49.00 63.69 129.82 316383.43 315085.11 75.62 157580.36 417.14 50 50.00 61.24 124.93 315085.11 313523.62 75.34 156799.48 417.13 51 51.00 61.21 122.45 313523.62 311848.10 75.04 155961.57 417.12 52 52.00 61.18 122.39 311848.10 310204.52 74.75 155139.63 417.11 53 53.00 61.13 122.30 310204.52 308590.90 74.46 154332.68 417.10 54 54.00 61.07 122.20 308590.90 307005.27 74.17 153539.72 417.09 55 55.00 61.00 122.07 307005.27 305445.75 73.89 152759.82 417.08 56 56.00 60.92 121.92 305445.75 303910.48 73.62 151992.05 417.07 57 57.00 60.83 121.75 303910.48 302397.54 73.35 151235.44 417.06 58 58.00 60.72 121.55 302397.54 300905.02 73.08 150489.05 417.05 59 59.00 60.61 121.33 300905.02 299431.17 72.82 149751.99 417.04 60 60.00 60.48 121.09 299431.17 297974.29 72.56 149023.42 417.04 61 61.00 60.35 120.83 297974.29 296532.75 72.30 148302.53 417.03 62 62.00 60.20 120.55 296532.75 295104.95 72.05 147588.50 417.02 63 63.00 60.04 120.24 295104.95 293689.37 71.79 146880.58 417.01 64 64.00 59.88 119.92 293689.37 292284.89 71.54 146178.22 417.00 Rivanna Engineering&Surveying,PLC Page 88 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Routed Hydrograph Report Name: SWM1, 10yr Type: Reservoir: Modified Puls [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 93.13 (cfs) Time to Peak (Tp) = 42.00 (min) Time of Base (Tb) = 1401.00 (min) Volume = 16.49 (ac-ft) Time Step = 1.00 (min) Peak Elevation = 417.77 (ft) Detention Time = NA [RESERVOIR STRUCTURE INFORMATION] Name = SWM Facility #1 Storage Type = User-Defined Area Maximum Storage = 652212.83 (cu ft) Maximum Discharge = 402.41 (cfs) [INFLOW HYDROGRAPH INFORMATION] Name = DA-Fontana Pond & DA-1 & SWM2, l0yr Peak Flow (Qp) = 223.47 (cfs) Time to Peak (Tp) = 20.00 (min) Time of Base (Tb) = 1319.00 (min) Volume = 16.49 (ac-ft) Flow Multiplier = 1.00 [EQUATION] (I1+I2) + (2(S1)/dt)-01 = (2(S2)/dt)+02 Where: I1 = Previous inflow I2 = Current inflow S1 = Previous storage S2 = Current storage dt = Time increment 01 = Previous outflow 02 = Current outflow A = (I1 + I2) B = (2 (S1) / dt) - 01 C = (2 (S2) / dt) + 02 [Computation of Reservoir Outflow Table of Modified Puls Method] Intv Time Inflow A B C Outflow Storage Elev (min) (cfs) (cfs) (cfs) (cfs) (cfs) (cu ft) (ft) 1 1.00 10.58 10.58 0.00 627.80 0.12 313.96 415.01 2 2.00 21.44 32.02 627.80 2513.69 0.47 1257.08 415.03 3 3.00 32.57 54.01 2513.69 5662.28 1.06 2831.67 415.08 4 4.00 43.97 76.54 5662.28 10077.37 1.88 5039.63 415.14 5 5.00 55.62 99.59 10077.37 15762.03 2.94 7882.48 415.22 6 6.00 67.63 123.25 15762.03 22729.33 4.16 11366.75 415.28 7 7.00 79.92 147.55 22729.33 30997.48 5.56 15501.52 415.34 8 8.00 92.47 172.39 30997.48 40575.01 7.18 20291.09 415.40 9 9.00 105.27 197.74 40575.01 51465.55 9.02 25737.29 415.48 10 10.00 118.88 224.14 51465.55 63682.07 11.48 31846.78 415.56 Rivanna Engineering&Surveying, PLC Page 89 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Routed Hydrograph Report SWM1, 10yr [Computation of Reservoir Outflow Table of Modified Puls Method] Intv Time Inflow A B C Outflow Storage Elev (min) (cfs) (cfs) (cfs) (cfs) (cfs) (cu ft) (ft) 11 11.00 132.88 251.76 63682.07 77233.30 14.38 38623.84 415.65 12 12.00 147.13 280.01 77233.30 92113.41 17.57 46065.49 415.75 13 13.00 162.10 309.23 92113.41 108313.08 21.59 54167.34 415.85 14 14.00 177.39 339.49 108313.08 125825.50 25.95 62925.73 415.97 15 15.00 192.98 370.37 125825.50 144624.09 31.02 72327.56 416.09 16 16.00 200.50 393.48 144624.09 164179.65 36.44 82108.05 416.21 17 17.00 208.20 408.70 164179.65 183974.74 42.25 92008.49 416.34 18 18.00 214.13 422.33 183974.74 203880.07 48.23 101964.15 416.46 19 19.00 219.29 433.42 203880.07 223717.27 54.46 111885.87 416.59 20 20.00 223.47 442.75 223717.27 243362.91 60.76 121711.83 416.71 21 21.00 216.88 440.35 243362.91 262208.42 65.42 131136.92 416.82 22 22.00 210.33 427.21 262208.42 279771.79 69.00 139920.40 416.93 23 23.00 203.79 414.11 279771.79 296141.41 72.23 148106.82 417.03 24 24.00 197.27 401.06 296141.41 311371.41 74.95 155723.18 417.12 25 25.00 190.78 388.06 311371.41 325506.17 77.48 162791.82 417.20 26 26.00 184.28 375.06 325506.17 338574.99 79.73 169327.36 417.28 27 27.00 177.77 362.05 338574.99 350612.56 81.66 175347.11 417.35 28 28.00 171.23 349.00 350612.56 361645.39 83.43 180864.41 417.41 29 29.00 164.67 335.90 361645.39 371690.11 85.04 185887.57 417.47 30 30.00 158.09 322.77 371690.11 380766.47 86.43 190426.45 417.52 31 31.00 151.50 309.59 380766.47 388897.59 87.62 194492.60 417.57 32 32.00 144.88 296.38 388897.59 396102.12 88.67 198095.39 417.61 33 33.00 138.25 283.13 396102.12 402393.85 89.58 201241.71 417.64 34 34.00 131.59 269.84 402393.85 407786.30 90.37 203938.34 417.68 35 35.00 124.92 256.51 407786.30 412292.88 91.02 206191.95 417.70 36 36.00 118.23 243.15 412292.88 415926.70 91.55 208009.12 417.72 37 37.00 111.52 229.75 415926.70 418700.60 91.96 209396.28 417.74 38 38.00 106.53 218.05 418700.60 420730.55 92.25 210411.40 417.75 39 39.00 103.25 209.77 420730.55 422223.75 92.63 211158.19 417.76 40 40.00 99.95 203.20 422223.75 423283.38 92.90 211688.14 417.76 41 41.00 96.64 196.59 423283.38 423920.13 93.07 212006.60 417.77 42 42.00 93.31 189.94 423920.13 424145.05 93.13 212119.09 417.77 43 43.00 89.96 183.27 424145.05 423968.74 93.08 212030.91 417.77 44 44.00 86.60 176.56 423968.74 423401.59 92.93 211747.26 417.76 45 45.00 83.22 169.82 423401.59 422453.82 92.69 211273.25 417.76 46 46.00 79.83 163.05 422453.82 421135.32 92.34 210613.83 417.75 47 47.00 76.42 156.25 421135.32 419446.15 92.06 209769.11 417.74 48 48.00 73.00 149.42 419446.15 417382.04 91.76 208736.90 417.73 49 49.00 69.56 142.56 417382.04 414945.64 91.41 207518.53 417.72 50 50.00 66.11 135.67 414945.64 412141.64 91.00 206116.32 417.70 51 51.00 66.14 132.25 412141.64 409182.59 90.57 204636.58 417.68 52 52.00 66.15 132.29 409182.59 406277.36 90.15 203183.75 417.67 53 53.00 66.15 132.31 406277.36 403423.32 89.73 201756.53 417.65 54 54.00 66.14 132.29 403423.32 400617.90 89.32 200353.61 417.63 55 55.00 66.11 132.25 400617.90 397858.56 88.92 198973.74 417.62 56 56.00 66.07 132.18 397858.56 395142.81 88.53 197615.67 417.60 57 57.00 66.01 132.08 395142.81 392468.25 88.14 196278.19 417.59 58 58.00 65.94 131.96 392468.25 389832.45 87.75 194960.10 417.57 59 59.00 65.86 131.80 389832.45 387233.02 87.38 193660.20 417.56 60 60.00 65.76 131.62 387233.02 384667.61 87.00 192377.31 417.54 61 61.00 65.64 131.40 384667.61 382133.98 86.63 191110.31 417.53 62 62.00 65.52 131.16 382133.98 379629.94 86.27 189858.11 417.51 63 63.00 65.38 130.90 379629.94 377153.53 85.91 188619.72 417.50 64 64.00 65.24 130.62 377153.53 374705.49 85.52 187395.50 417.49 Rivanna Engineering&Surveying,PLC Page 90 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Routed Hydrograph Report Name: SWM1, 100yr Type: Reservoir: Modified Puls [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 143.47 (cfs) Time to Peak (Tp) = 37.00 (min) Time of Base (Tb) = 1415.00 (min) Volume = 24.03 (ac-ft) Time Step = 1.00 (min) Peak Elevation = 418.47 (ft) Detention Time = NA [RESERVOIR STRUCTURE INFORMATION] Name = SWM Facility #1 Storage Type = User-Defined Area Maximum Storage = 652212.83 (cu ft) Maximum Discharge = 402.41 (cfs) [INFLOW HYDROGRAPH INFORMATION] Name = DA-Fontana Pond & DA-1 & SWM2, 100yr Peak Flow (Qp) = 300.24 (cfs) Time to Peak (Tp) = 20.00 (min) Time of Base (Tb) = 1332.00 (min) Volume = 24.03 (ac-ft) Flow Multiplier = 1.00 [EQUATION] (I1+I2) + (2(S1)/dt)-01 = (2(S2)/dt)+02 Where: Il = Previous inflow 12 = Current inflow S1 = Previous storage S2 = Current storage dt = Time increment 01 = Previous outflow 02 = Current outflow A = (I1 + 12) B = (2 (Sl) / dt) - 01 C = (2 (S2) / dt) + 02 [Computation of Reservoir Outflow Table of Modified Puls Method] Intv Time Inflow A B C Outflow Storage Elev (min) (cfs) (cfs) (cfs) (cfs) (cfs) (cu ft) (ft) 1 1.00 15.34 15.34 0.00 910.20 0.17 455.19 415.01 2 2.00 31.09 46.43 910.20 3644.68 0.68 1822.68 415.05 3 3.00 47.23 78.33 3644.68 8210.58 1.53 4106.04 415.11 4 4.00 63.77 111.00 8210.58 14613.86 2.73 7308.29 415.20 5 5.00 80.79 144.56 14613.86 22870.85 4.19 11437.52 415.28 6 6.00 98.24 179.03 22870.85 33005.92 5.90 16505.91 415.35 7 7.00 116.08 214.33 33005.92 45033.65 7.93 22520.79 415.43 8 8.00 134.68 250.76 45033.65 58973.01 10.47 29491.74 415.53 9 9.00 154.16 288.84 58973.01 74839.89 13.87 37426.88 415.63 10 10.00 174.05 328.21 74839.89 92635.22 17.69 46326.46 415.75 Rivanna Engineering&Surveying,PLC Page 91 (434)9841599 Luxor Subdivision Stormwater Management Pond#1 Routed Hydrograph Report SWM1, 100yr [Computation of Reservoir Outflow Table of Modified Puls Method] Intv Time Inflow A B C Outflow Storage Elev (min) (cfs) (cfs) (cfs) (cfs) (cfs) (cu ft) (ft) 11 11.00 195.04 369.09 92635.22 112358.59 22.60 56190.59 415.88 12 12.00 216.39 411.44 112358.59 133998.66 28.08 67013.37 416.02 13 13.00 238.66 455.05 133998.66 157534.85 34.60 78784.72 416.17 14 14.00 261.32 499.98 157534.85 182934.26 41.94 91488.10 416.33 15 15.00 280.88 542.20 182934.26 209938.97 50.05 104994.51 416.50 16 16.00 287.56 568.44 209938.97 237500.87 58.88 118779.88 416.67 17 17.00 290.68 578.24 237500.87 264699.38 65.93 132382.65 416.84 18 18.00 293.83 584.50 264699.38 291524.48 71.40 145797.94 417.00 19 19.00 297.02 590.85 291524.48 318117.27 76.16 159096.71 417.16 20 20.00 300.24 597.26 318117.27 344537.56 80.69 172309.12 417.31 21 21.00 290.76 591.00 344537.56 370065.99 84.78 185075.38 417.46 22 22.00 281.32 572.08 370065.99 393999.30 88.36 197043.83 417.60 23 23.00 271.91 553.23 393999.30 416390.99 91.62 208241.31 417.72 24 24.00 262.53 534.44 416390.99 437164.58 96.51 218630.55 417.84 25 25.00 253.17 515.70 437164.58 456223.26 101.46 228162.36 417.95 26 26.00 243.80 496.97 456223.26 473514.38 107.23 236810.81 418.04 27 27.00 234.41 478.21 473514.38 488946.56 113.67 244530.12 418.13 28 28.00 224.98 459.39 488946.56 502523.77 119.34 251321.56 418.20 29 29.00 215.52 440.50 502523.77 514315.84 124.54 257220.19 418.27 30 30.00 206.03 421.55 514315.84 524358.08 129.55 262243.82 418.32 31 31.00 196.51 402.54 524358.08 532709.73 133.72 266421.73 418.37 32 32.00 186.95 383.46 532709.73 539465.30 137.09 269801.19 418.40 33 33.00 177.37 364.32 539465.30 544713.93 139.71 272426.82 418.43 34 34.00 167.75 345.12 544713.93 548539.76 141.62 274340.69 418.45 35 35.00 158.11 325.87 548539.76 551021.97 142.86 275582.42 418.47 36 36.00 148.44 306.55 551021.97 552235.15 143.46 276189.30 418.47 37 37.00 138.74 287.17 552235.15 552249.73 143.47 276196.60 418.47 38 38.00 131.51 270.24 552249.73 551277.57 142.98 275710.28 418.47 39 39.00 126.75 258.26 551277.57 549663.92 142.18 274903.05 418.46 40 40.00 121.97 248.71 549663.92 547588.50 141.14 273864.82 418.45 41 41.00 117.16 239.12 547588.50 545075.16 139.89 272607.52 418.43 42 42.00 112.32 229.48 545075.16 542146.42 138.43 271142.43 418.42 43 43.00 107.47 219.79 542146.42 538823.68 136.77 269480.22 418.40 44 44.00 102.59 210.06 538823.68 535127.44 134.93 267631.18 418.38 45 45.00 97.70 200.29 535127.44 531076.98 132.91 265604.94 418.36 46 46.00 92.78 190.48 531076.98 526690.57 130.72 263410.64 418.34 47 47.00 87.85 180.63 526690.57 521985.60 128.37 261056.99 418.31 48 48.00 82.90 170.75 521985.60 516978.31 125.87 258552.09 418.28 49 49.00 77.92 160.82 516978.31 511684.00 123.23 255903.62 418.25 50 50.00 72.93 150.86 511684.00 506094.49 120.83 253107.66 418.22 51 51.00 73.02 145.95 506094.49 500495.00 118.49 250306.75 418.19 52 52.00 73.09 146.10 500495.00 495177.75 116.27 247647.01 418.16 53 53.00 73.13 146.22 495177.75 490126.90 114.16 245120.53 418.14 54 54.00 73.17 146.30 490126.90 485327.40 112.16 242719.78 418.11 55 55.00 73.18 146.35 485327.40 480764.97 110.26 240437.62 418.08 56 56.00 73.18 146.36 480764.97 476426.02 108.45 238267.23 418.06 57 57.00 73.16 146.34 476426.02 472297.64 106.72 236202.18 418.04 58 58.00 73.12 146.28 472297.64 468367.57 105.08 234236.33 418.02 59 59.00 73.07 146.19 468367.57 464616.93 103.64 232360.29 418.00 60 60.00 73.00 146.07 464616.93 461001.37 102.70 230552.03 417.98 61 61.00 72.91 145.91 461001.37 457487.47 101.79 228794.63 417.96 62 62.00 72.81 145.72 457487.47 454070.14 100.90 227085.52 417.94 63 63.00 72.69 145.50 454070.14 450744.69 100.04 225422.36 417.92 Rivanna Engineering&Surveying,PLC Page 92 (434)984-1599 Luxor Subdivision Stormwater Management Pond #1 Uncontained Hydrograph Report Name: DA-1, Uncontained 2yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 53.01 (cfs) Time to Peak (Tp) = 20.00 (min) Time of Base (Tb) = 50.00 (min) Volume = 1.83 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 1.83 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef Impervious Areas 0.70 0 0.90 Unimproved Areas 18.00 0 0.30 Avemore & Unimproved Areas 22.20 0 0.30 Town & Country (Future) 4.00 0 0.70 Fontana 6.00 0 0.50 Overall Approximation 50.90 NA 0.36 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 20.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 0.95 (in) Return Period = 2 (yr) Storm Duration = 0.33 (hr) Rivanna Engineering&Surveying,PLC Page 93 (434)984-1599 Luxor Subdivision Stormwater Management Pond #1 Uncontained Hydrograph Report DA-1, Uncontained 2yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.05 0.00 2.65 2 2.00 0.05 0.09 2.65 5.30 3 3.00 0.05 0.14 2.65 7.95 4 4.00 0.05 0.19 2.65 10.60 5 5.00 0.05 0.24 2.65 13.25 6 6.00 0.05 0.28 2.65 15.90 7 7.00 0.05 0.33 2.65 18.55 8 8.00 0.05 0.38 2.65 21.20 9 9.00 0.05 0.43 2.65 23.85 10 10.00 0.05 0.47 2.65 26.50 11 11.00 0.05 0.52 2.65 29.15 12 12.00 0.05 0.57 2.65 31.80 13 13.00 0.05 0.62 2.65 34.45 14 14.00 0.05 0.66 2.65 37.10 15 15.00 0.05 0.71 2.65 39.75 16 16.00 0.05 0.76 2.65 42.40 17 17.00 0.05 0.81 2.65 45.05 18 18.00 0.05 0.85 2.65 47.71 19 19.00 0.05 0.90 2.65 50.36 20 20.00 0.05 0.95 2.65 53.01 21 21.00 0.00 0.95 -1.77 51.24 22 22.00 0.00 0.95 -1.77 49.47 23 23.00 0.00 0.95 -1.77 47.71 24 24.00 0.00 0.95 -1.77 45.94 25 25.00 0.00 0.95 -1.77 44.17 26 26.00 0.00 0.95 -1.77 42.40 27 27.00 0.00 0.95 -1.77 40.64 28 28.00 0.00 0.95 -1.77 38.87 29 29.00 0.00 0.95 -1.77 37.10 30 30.00 0.00 0.95 -1.77 35.34 31 31.00 0.00 0.95 -1.77 33.57 32 32.00 0.00 0.95 -1.77 31.80 33 33.00 0.00 0.95 -1.77 30.04 34 34.00 0.00 0.95 -1.77 28.27 35 35.00 0.00 0.95 -1.77 26.50 36 36.00 0.00 0.95 -1.77 24.74 37 37.00 0.00 0.95 -1.77 22.97 38 38.00 0.00 0.95 -1.77 21.20 39 39.00 0.00 0.95 -1.77 19.44 40 40.00 0.00 0.95 -1.77 17.67 41 41.00 0.00 0.95 -1.77 15.90 42 42.00 0.00 0.95 -1.77 14.13 43 43.00 0.00 0.95 -1.77 12.37 44 44.00 0.00 0.95 -1.77 10.60 45 45.00 0.00 0.95 -1.77 8.83 46 46.00 0.00 0.95 -1.77 7.07 47 47.00 0.00 0.95 -1.77 5.30 48 48.00 0.00 0.95 -1.77 3.53 49 49.00 0.00 0.95 -1.77 1.77 50 50.00 0.00 0.95 -1.77 0.00 Rivanna Engineering&Surveying,PLC Page 94 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Uncontained Hydrograph Report Name: DA-1, Uncontained l0yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 75.91 (cfs) Time to Peak (Tp) = 20.00 (min) Time of Base (Tb) = 50.00 (min) Volume = 2.61 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 2.61 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef Impervious Areas 0.70 0 0.90 Unimproved Areas 18.00 0 0.30 Avemore & Unimproved Areas 22.20 0 0.30 Town & Country (Future) 4.00 0 0.70 Fontana 6.00 0 0.50 Overall Approximation 50.90 NA 0.36 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 20.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 1.36 (in) Return Period = User Defined (yr) Storm Duration = 0.33 (hr) Rivanna Engineering&Surveying,PLC Page 95 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Uncontained Hydrograph Report DA-1, Uncontained l0yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.07 0.00 3.80 2 2.00 0.07 0.14 3.80 7.59 3 3.00 0.07 0.20 3.80 11.39 4 4.00 0.07 0.27 3.80 15.18 5 5.00 0.07 0.34 3.80 18.98 6 6.00 0.07 0.41 3.80 22.77 7 7.00 0.07 0.48 3.80 26.57 8 8.00 0.07 0.54 3.80 30.36 9 9.00 0.07 0.61 3.80 34.16 10 10.00 0.07 0.68 3.80 37.96 11 11.00 0.07 0.75 3.80 41.75 12 12.00 0.07 0.81 3.80 45.55 13 13.00 0.07 0.88 3.80 49.34 14 14.00 0.07 0.95 3.80 53.14 15 15.00 0.07 1.02 3.80 56.93 16 16.00 0.07 1.09 3.80 60.73 17 17.00 0.07 1.15 3.80 64.52 18 18.00 0.07 1.22 3.80 68.32 19 19.00 0.07 1.29 3.80 72.12 20 20.00 0.07 1.36 3.80 75.91 21 21.00 0.00 1.36 -2.53 73.38 22 22.00 0.00 1.36 -2.53 70.85 23 23.00 0.00 1.36 -2.53 68.32 24 24.00 0.00 1.36 -2.53 65.79 25 25.00 0.00 1.36 -2.53 63.26 26 26.00 0.00 1.36 -2.53 60.73 27 27.00 0.00 1.36 -2.53 58.20 28 28.00 0.00 1.36 -2.53 55.67 29 29.00 0.00 1.36 -2.53 53.14 30 30.00 0.00 1.36 -2.53 50.61 31 31.00 0.00 1.36 -2.53 48.08 32 32.00 0.00 1.36 -2.53 45.55 33 33.00 0.00 1.36 -2.53 43.02 34 34.00 0.00 1.36 -2.53 40.49 35 35.00 0.00 1.36 -2.53 37.96 36 36.00 0.00 1.36 -2.53 35.43 37 37.00 0.00 1.36 -2.53 32.90 38 38.00 0.00 1.36 -2.53 30.36 39 39.00 0.00 1.36 -2.53 27.83 40 40.00 0.00 1.36 -2.53 25.30 41 41.00 0.00 1.36 -2.53 22.77 42 42.00 0.00 1.36 -2.53 20.24 43 43.00 0.00 1.36 -2.53 17.71 44 44.00 0.00 1.36 -2.53 15.18 45 45.00 0.00 1.36 -2.53 12.65 46 46.00 0.00 1.36 -2.53 10.12 47 47.00 0.00 1.36 -2.53 7.59 48 48.00 0.00 1.36 -2.53 5.06 49 49.00 0.00 1.36 -2.53 2.53 50 50.00 0.00 1.36 -2.53 0.00 Rivanna Engineering&Surveying,PLC Page 96 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Uncontained Hydrograph Report Name: DA-1, Uncontained 100yr Type: Modified Rational [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 110.56 (cfs) Time to Peak (Tp) = 20.00 (min) Time of Base (Tb) = 50.00 (min) Volume = 3.81 (ac-ft) Time Step = 1.00 (min) Flow Multiplier = 1.00 [RATIONAL HYDROGRAPH INFORMATION] Flow Multiplier = 1.00 Receding Limb Factor = 1.50 [APPROXIMATE STORAGE] Maximum Outflow = 0.00 (cfs) Maximum Storage = 3.81 (cu ft) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN Runoff Coef Impervious Areas 0.70 0 0.90 Unimproved Areas 18.00 0 0.30 Avemore & Unimproved Areas 22.20 0 0.30 Town & Country (Future) 4.00 0 0.70 Fontana 6.00 0 0.50 Overall Approximation 50.90 NA 0.36 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 20.00 (min) [RAINFALL DESCRIPTION] Distribution Type = Synthetic Total Precipitation = 1.98 (in) Return Period = 100 (yr) Storm Duration = 0.33 (hr) Rivanna Engineering&Surveying,PLC Page 97 (434)984-1599 Luxor Subdivision Stormwater Management Pond #1 Uncontained Hydrograph Report DA-1, Uncontained 100yr [Hydrograph Flow Values: Time vs. Flow] Time Time Incremental Cumulative Incremental Design Interval Rainfall Rainfall Outflow Outflow (min) (in) (in) (cfs) (cfs) 1 1.00 0.00 0.10 0.00 5.53 2 2.00 0.10 0.20 5.53 11.06 3 3.00 0.10 0.30 5.53 16.58 4 4.00 0.10 0.40 5.53 22.11 5 5.00 0.10 0.49 5.53 27.64 6 6.00 0.10 0.59 5.53 33.17 7 7.00 0.10 0.69 5.53 38.69 8 8.00 0.10 0.79 5.53 44.22 9 9.00 0.10 0.89 5.53 49.75 10 10.00 0.10 0.99 5.53 55.28 11 11.00 0.10 1.09 5.53 60.81 12 12.00 0.10 1.19 5.53 66.33 13 13.00 0.10 1.28 5.53 71.86 14 14.00 0.10 1.38 5.53 77.39 15 15.00 0.10 1.48 5.53 82.92 16 16.00 0.10 1.58 5.53 88.45 17 17.00 0.10 1.68 5.53 93.97 18 18.00 0.10 1.78 5.53 99.50 19 19.00 0.10 1.88 5.53 105.03 20 20.00 0.10 1.98 5.53 110.56 21 21.00 0.00 1.98 -3.69 106.87 22 22.00 0.00 1.98 -3.69 103.19 23 23.00 0.00 1.98 -3.69 99.50 24 24.00 0.00 1.98 -3.69 95.82 25 25.00 0.00 1.98 -3.69 92.13 26 26.00 0.00 1.98 -3.69 88.45 27 27.00 0.00 1.98 -3.69 84.76 28 28.00 0.00 1.98 -3.69 81.07 29 29.00 0.00 1.98 -3.69 77.39 30 30.00 0.00 1.98 -3.69 73.70 31 31.00 0.00 1.98 -3.69 70.02 32 32.00 0.00 1.98 -3.69 66.33 33 33.00 0.00 1.98 -3.69 62.65 34 34.00 0.00 1.98 -3.69 58.96 35 35.00 0.00 1.98 -3.69 55.28 36 36.00 0.00 1.98 -3.69 51.59 37 37.00 0.00 1.98 -3.69 47.91 38 38.00 0.00 1.98 -3.69 44.22 39 39.00 0.00 1.98 -3.69 40.54 40 40.00 0.00 1.98 -3.69 36.85 41 41.00 0.00 1.98 -3.69 33.17 42 42.00 0.00 1.98 -3.69 29.48 43 43.00 0.00 1.98 -3.69 25.80 44 44.00 0.00 1.98 -3.69 22.11 45 45.00 0.00 1.98 -3.69 18.43 46 46.00 0.00 1.98 -3.69 14.74 47 47.00 0.00 1.98 -3.69 11.06 48 48.00 0.00 1.98 -3.69 7.37 49 49.00 0.00 1.98 -3.69 3.69 50 50.00 0.00 1.98 -3.69 0.00 Rivanna Engineering&Surveying,PLC Page 98 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Uncontained Hydrograph Report Name: SWM1 & DA-1 Uncontained, 2yr Type: Combined [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 103.63 (cfs) Time to Peak (Tp) = 27.00 (min) Time of Base (Tb) = 1380.00 (min) Volume = 13.18 (ac-ft) Time Step = 1.00 (min) [COMBINED HYDROGRAPH RECORDS] Name: SWM1, 2yr Type: Reservoir: Modified Puls Peak Flow (Qp) = 76.29 (cfs) Time to Peak (Tp) = 44.00 (min) Time Step = 1.00 (min) Name: DA-1, Uncontained 2yr Type: Modified Rational Peak Flow (Qp) = 53.01 (cfs) Time to Peak (Tp) = 20.00 (min) Time Step = 1.00 (min) [Combined Hydrograph Flow Values] Interval Time Outflow (min) (cfs) 1 1.00 2.73 2 2.00 5.62 3 3.00 8.67 4 4.00 11.89 5 5.00 15.26 6 6.00 18.80 7 7.00 22.45 8 8.00 26.20 9 9.00 30.11 10 10.00 34.17 11 11.00 38.38 12 12.00 43.10 13 13.00 48.12 14 14.00 53.34 15 15.00 58.97 16 16.00 64.96 17 17.00 70.99 18 18.00 77.31 19 19.00 83.82 20 20.00 90.39 21 21.00 92.76 22 22.00 95.01 23 23.00 97.05 24 24.00 99.07 25 25.00 100.88 26 26.00 102.40 27 27.00 103.63 28 28.00 103.62 29 29.00 103.44 30 30.00 103.11 31 31.00 102.64 Rivanna Engineering&Surveying, PLC Page 99 (434)984-1599 Luxor Subdivision Stormwater Management Pond #1 Combined Hydrograph Report SWM1 & DA-1 Uncontained, 2yr [Combined Hydrograph Flow Values] Interval Time Outflow (min) (cfs) 32 32.00 102.02 33 33.00 101.27 34 34.00 100.31 35 35.00 99.20 36 36.00 97.98 37 37.00 96.65 38 38.00 95.23 39 39.00 93.74 40 40.00 92.20 41 41.00 90.61 42 42.00 88.96 43 43.00 87.27 44 44.00 85.53 45 45.00 83.74 46 46.00 81.90 47 47.00 80.02 48 48.00 78.08 49 49.00 76.11 50 50.00 74.09 51 51.00 73.82 52 52.00 73.55 53 53.00 73.28 54 54.00 73.03 55 55.00 72.77 56 56.00 72.52 57 57.00 72.27 58 58.00 72.03 59 59.00 71.79 60 60.00 71.55 61 61.00 71.29 62 62.00 71.03 63 63.00 70.76 64 64.00 70.50 65 65.00 70.24 66 66.00 69.99 67 67.00 69.73 68 68.00 69.48 69 69.00 69.23 70 70.00 68.99 71 71.00 68.74 72 72.00 68.50 73 73.00 68.26 74 74.00 68.02 75 75.00 67.78 76 76.00 67.54 77 77.00 67.30 78 78.00 67.04 79 79.00 66.75 80 80.00 66.42 81 81.00 66.07 82 82.00 65.69 83 83.00 65.26 84 84.00 64.79 85 85.00 64.27 Rivanna Engineering&Surveying,PLC Page 100 (434)984-1599 Luxor Subdivision Stormwater Management Pond#1 Combined Hydrograph Report Name: SWM1 & DA-1 Uncontained, 10yr Type: Combined [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 139.30 (cfs) Time to Peak (Tp) = 24.00 (min) Time of Base (Tb) = 1401.00 (min) /1 1 ,,L� - Volume = 18.89 (ac-ft) �(/t� Time Step = 1.00 (min) 411"4- HYDROGRAPH RECORDS] i^ Name: SWM1, 10yr Type: Reservoir: Modified Puls Peak Flow (Qp) = 93.13 (cfs) Time to Peak (Tp) = 42.00 (min) Time Step = 1.00 (min) Name: DA-1, Uncontained 10yr Type: Modified Rational Peak Flow (Qp) = 75.91 (cfs) Time to Peak (Tp) = 20.00 (min) Time Step = 1.00 (min) [Combined Hydrograph Flow Values] Interval Time Outflow (min) (cfs) 1 1.00 3.91 2 2.00 8.05 3 3.00 12.41 4 4.00 17.01 5 5.00 21.84 6 6.00 26.83 7 7.00 31.98 8 8.00 37.35 9 9.00 42.94 10 10.00 49.06 11 11.00 55.69 12 12.00 62.60 13 13.00 70.23 14 14.00 78.29 15 15.00 86.94 16 16.00 96.03 17 17.00 105.40 18 18.00 115.03 19 19.00 124.81 20 20.00 134.74 21 21.00 137.47 22 22.00 138.41 23 23.00 139.11 24 24.00 139.30 25 25.00 139.21 26 26.00 138.94 27 27.00 138.36 28 28.00 137.54 29 29.00 136.56 30 30.00 135.43 31 31.00 134.14 Rivanna Engineering&Surveying,PLC Page 101 (434)984-1599 Luxor Subdivision Stormwater Management Pond #1 Combined Hydrograph Report SWM1 & DA-1 Uncontained, l0yr [Combined Hydrograph Flow Values] Interval Time Outflow (min) (cfs) 32 32.00 132.62 33 33.00 130.97 34 34.00 129.19 35 35.00 127.29 36 36.00 125.27 37 37.00 123.12 38 38.00 120.87 39 39.00 118.55 40 40.00 116.17 41 41.00 113.74 42 42.00 111.25 43 43.00 108.70 44 44.00 106.10 45 45.00 103.44 46 46.00 100.74 47 47.00 97.98 48 48.00 95.17 49 49.00 92.31 50 50.00 89.39 51 51.00 88.99 52 52.00 88.60 53 53.00 88.21 54 54.00 87.83 55 55.00 87.45 56 56.00 87.08 57 57.00 86.72 58 58.00 86.36 59 59.00 86.00 60 60.00 85.63 61 61.00 85.25 62 62.00 84.88 63 63.00 84.51 64 64.00 84.14 65 65.00 83.78 66 66.00 83.42 67 67.00 83.07 68 68.00 82.72 69 69.00 82.38 70 70.00 82.03 71 71.00 81.70 72 72.00 81.36 73 73.00 81.03 74 74.00 80.71 75 75.00 80.38 76 76.00 80.06 77 77.00 79.74 78 78.00 79.43 79 79.00 79.12 80 80.00 78.79 81 81.00 78.45 82 82.00 78.11 83 83.00 77.78 84 84.00 77.45 85 85.00 77.13 Rivanna Engineering&Surveying,PLC Page 102 (434)984-1599 WATER QUALITY VOLUME CALCULATIONS FOR LUXOR SUBDIVISION STORMWATER MANAGEMENT PLANS July 1, 2005 LOCATION: Tax Map 78, Parcel 11 Albemarle County, Virginia PREPARED BY: Rivanna Engineering & Surveying, PLC 1350 Stony Point Rd. Charlottesville, VA 22911 P: 434.984.1599 F: 434.984.8863 Lx o c Sv✓ ■ Vo 0-7 /01 J 200 s Lvb* 15`� -15 4b6 3, \'"io z-1-01 790 4�o 23, 705 333 4�a Z4,53a 7 90,45 c,, y1� sue, c1(.4 (0 , 5-4A-al `S C,C,, 1 Y3 aG�7 ,S-1 Vic? � �a�. � A LA'aZO.S U > 1,7S1.5- i-t30 3,V/i 7 a3, Aso L}3a 19f4-73 SS, 3 SO 3s, D-1 Coo) (o7(o .2S 435.5 4S,CM1 VCS\13 � t.�s��tV\o = 33i�.3 � = �c1 . \ �{3 a\G , $ii t o e ', ,/o\uwl.L. el' . ;r YGt;\■k-s Va\o.tv\.2. p \ QQ.c‘f‘QU (5a.\ d3 = 1 C,0C, °1 -fit ' au V✓QJ = 35, 4 S't a3a , 3oz-v.(o cvSS\ vo\L A 4._.. a is A cb\e_ 23a , z04-.c. Vt's - a}L,irk qi = ice, ,A-53 EMERGENCY SPILLWAY CALCULATIONS FOR LUXOR SUBDIVISION STORMWATER MANAGEMENT PLANS July 1, 2005 LOCATION: Tax Map 78, Parcel 11 Albemarle County,Virginia PREPARED BY: Rivanna Engineering & Surveying, PLC 1350 Stony Point Rd. Charlottesville, VA 22911 P: 434.984.1599 F: 434.984.8863 0.. 0 200 FHWA Urban Drainage Design Program, HY-22 HYDRAULIC PARAMETERS OF OPEN CHANNELS Trapezoidal, Rectangular, or Triangular X-Section Date: 07/01/2005 Project No. . Project Name. : Luxor Computed by : Rivanna Engineering Project Description Stormwater Pond #2 Forebay Spillway INPUT PARAMETERS 1 . Channel Slope (ft/ft) 0 . 0200 2 . Channel Bottom Width (ft) 2 . 00 3 . Left Side Slope (Horizontal to 1) 2 . 00 4 . Right Side Slope (Horizontal to 1) 2 . 00 5 . Manning' s Coefficient 0 . 050 6. Discharge (cfs) 100 . 00 7 . Depth of Flow (ft) 2 . 63 OUTPUT RESULTS Cross Section Area (Sqft) 19. 09 Average Velocity (ft/sec) 5 . 24 Top Width (ft) 12 . 52 Hydraulic Radius (ft) 1 . 39 Froude Number 0 . 75 BMP CALCULATIONS FOR LUXOR SUBDIVISION STORMWATER MANAGEMENT PLANS July 1, 2005 LOCATION: Tax Map 78, Parcel 11 Albemarle County, Virginia PREPARED BY: Rivanna Engineering & Surveying, PLC 1350 Stony Point Rd. Charlottesville, VA 22911 P: 434.984.1599 F: 434.984.8863 Ak 0(s) 2%15 Short Version BMP Computations For Worksheets 2- 6 Albemarle County Water Protection Ordinance: Modified Simple Method Plan: Luxor Subdivision Water Resources Area: Development Area Preparer: Rivanna Engineering Date: 7/1/2005 Project Drainage Area Designation DA#2 L storm pollutant export in pounds, L= [P(Pj)Rv/12] [C(A)2.72] Rv mean runoff coefficient, Rv=0.05+0.009(1) Pj small storm correction factor,0.9 I percent imperviousness P annual precipitation,43"in Albemarle A project area in acres in subject drainage area, A= 100.10 C pollutant concentration,mg/I or ppm target phosphorus f factor applied to RR ✓ required treatment volume in cy,0.5"over imperv.area= A(1)43560(0.5/12)/27 RR required removal, L(post)-f x L(pre) %RR removal efficiency, RR100/L(post) Impervious Cover Computation (values in feet&square feet) Item pre-development Area post-development Area Roads Length Width subtotal Length Width subtotal O 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Driveways Length Width no. subtotal Length Width no. subtotal and walks 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Parking Lots 1 2 3 4 1 2 3 4 0 Structures Area no. subtotal Area no. subtotal 0 0 0 0 0 0 O 0 0 0 0 0 O 0 0 0 Actively-grazed pasture& Area Area yards and cultivated turf 0 x 0.08= 0 2405781 x 0.08= 192462.5 Active crop land Area Area x0.25= 0 x0.25= 0 Other Impervious Areas 0 1954575 Impervious Cover 0% 49% l(pre) l(post) Rv(post) V 0.49 3313.3 New Development(For Development Areas,existing impervious cover<=20%) C f I(pre)* Rv(pre) L(pre) L(post) RR % RR Area Type 0.70 1.00 20% 0.23 141.34 303.05 161.72 53% Development Area 0.35 1.00 0% 0.05 15.36 151.53 136.16 90% Drinking Water Watersheds 0.40 1.00 1% 0.06 20.72 173.17 152.46 88% Other Rural Land *min.values Redevelopment(For Development Areas,existing impervious cover>20%) C f I(pre)* Rv(pre) L(pre) L(post) RR % RR Area Type 0,70 0.90 20% 0.23 141.34 303.05 175.85 58% Development Area 0.35 0.85 0% 0.05 15.36 151.53 138.47 91% Drinking Water Watersheds 0.40 0.85 1% 0.06 20.72 173.17 155.56 90% Other Rural Land Interim Manual, Page 70 rev.31 March 1998 GEB Short Version BMP Computations For Worksheets 2 - 6 Albemarle County Water Protection Ordinance: Modified Simple Method Plan: Luxor Subdivision Water Resources Area: Development Area Preparer: Rivanna Engineering Date: 7/1/2005 Project Drainage Area Designation DA#1 L storm pollutant export in pounds, L= [P(Pj)Rv/12][C(A)2.72] Rv mean runoff coefficient, Rv=0.05+0.009(1) Pj small storm correction factor,0.9 I percent imperviousness P annual precipitation,43"in Albemarle A project area in acres in subject drainage area, A= 43.05 C pollutant concentration,mg/I or ppm target phosphorus f factor applied to RR ✓ required treatment volume in cy,0.5"over imperv.area= A(1)43560(0.5/12)/27 RR required removal , L(post)-f x L(pre) %RR removal efficiency, RR100/L(post) Impervious Cover Computation (values in feet&square feet) Item pre-development Area post-development Area Roads Length Width subtotal Length Width subtotal O o 0 0 0 0 o o 0 0 0 0 0 0 0 0 0 0 0 0 Driveways Length Width no. subtotal Length Width no. subtotal and walks 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Parking Lots 1 2 3 4 1 2 3 4 0 Structures Area no. subtotal Area no. subtotal O 0 0 0 0 0 o o 0 0 0 0 o 0 0 0 Actively-grazed pasture& Area Area yards and cultivated turf 0 x 0.08= 0 1578995 x 0.08= 126319.6 Active crop land Area Area x0.25= 0 x0.25= 0 Other Impervious Areas 0 296263 Impervious Cover 0% 23% l(pre) ((post) Rv(post) V 0.25 652.1 New Development(For Development Areas,existing impervious cover<=20%) C f I(pre)* Rv(pre) L(pre) L(post) RR %RR Area Type 0.70 1.00 20% 0.23 60.79 66.81 6.03 9% Development Area 0.35 1.00 0% 0.05 6.61 33.41 26.80 80% Drinking Water Watersheds 0.40 1.00 1% 0.06 8.91 38.18 29.27 77% Other Rural Land *min.values Redevelopment(For Development Areas,existing impervious cover>20%) C f I(pre)* Rv(pre) L(pre) L(post) RR % RR Area Type 0.70 0.90 20% 0.23 60.79 66.81 12.11 18% Development Area 0.35 0.85 0% 0.05 6.61 33.41 27.79 83% Drinking Water Watersheds 0.40 0.85 1% 0.06 8.91 38.18 30.61 80% Other Rural Land Interim Manual, Page 70 rev.31 March 1998 GEB FOREBAY VOLUME CALCULATIONS FOR LUXOR SUBDIVISION STORMWATER MANAGEMENT PLANS July 1, 2005 LOCATION: Tax Map 78, Parcel 11 Albemarle County,Virginia PREPARED BY: Rivanna Engineering & Surveying, PLC 1350 Stony Point Rd. Charlottesville, VA 22911 P: 434.984.1599 F: 434.984.8863 \\ ? Qc (' c tc■ cb ' -4'• 07.-4 c v1^44-ter-e, Q.1 c,L(e_.s bCM CZ, \.Ao t tA• 009 ve3,..)% ) -70\ S'rb.r cAy._ Ce0 Q_ D. as- 11 oc' o ,gs,cc-t (4, 0, OCIC ',Pr\CA',6-\---CA■•!1 Lose_ crV . 7" qce_\i..)CALS , di(e4 t417 -7 \ Q3 2414-0 ;IC' e_ \wc.0 RECEIVrD BMP CALCULATIONS JAN 07 2005 COMMUNITY DEVELOPMENT FOR LUXOR SUBDIVISION November 29, 2004 Rev: January 6, 2005 LOCATION: Tax Map 78, Parcel 12 Rivanna District Albemarle County,Virginia PREPARED BY: Rivanna Engineering & Surveying, PLC 1350 Stony Point Rd. Charlottesville, VA 22911 P: 434.984.1599 F: 434.984.8863 Short Version BMP Computations For Worksheets 2 - 6 Albemarle County Water Protection Ordinance: Modified Simple Method Plan: Luxor Subdivision Water Resources Area: Development Area Preparer: Rivanna Engineering Date: 1/6/2005 Project Drainage Area Designation DA#1 L storm pollutant export in pounds, L=[P(Pj)Rv/12] [C(A)2.72] Rv mean runoff coefficient, Rv=0.05+0.009(1) Pj small storm correction factor,0.9 I percent imperviousness P annual precipitation,43"in Albemarle A project area in acres in subject drainage area, A= 93.45 C pollutant concentration, mg/I or ppm target phosphorus f factor applied to RR V,. required treatment volumc..in cy,.,0.5".over imperv.area= A(1)43560(0,5/120? RR regwred removal , L(post)-f x L(pre) %RR removal efficiency, RR100/L(post) Impervious Cover Computation(values in feet&square feet) Item pre-development Area post-development Area Roads Length Width subtotal r Length Width subtotal O 0 0 0 0 0 O 0 0 0 0 0 O 0 0 0 o 0 0 0 Driveways Length Width no. subtotal Length Width no. subtotal and walks 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 O 0 Parking Lots 1 2 3 4 1 2 3 4 0 Structures Area no. subtotal Area no. subtotal 0 0 p 0 0 0 O 0 0 0 0 0 o 0 0 0 Actively-grazed pasture& Area Area yards and cultivated turf 0 x 0.08= 0 2379845 x 0.08= 190387.6 Active crop land Area Area x025= 0 x0.25= 0 Other Impervious Areas 0 1690837 Impervious Cover 0% 46% / _ !''� l(pre) l(post) Rv(post) "/".--- V 0.47 903.1 w„ New Development(For Development Areas,existing impervious cover<=20%) C f I (pre)* Rv(pre) L(pre) L(post) RR % RR Area Type 0.70 1,00 20% 0.23 131.95 267.30 135.35 51% Development Area 0.35 1.00 0% 0.05 14.34 133.65 119.31 89% Drinking Water Watersheds 0.40 1.00 1% 0.06 19.34 152.74 133.40 87% Other Rural Land *min.values Redevelopment(For Development Areas,existing impervious cover>20%) C f I(pre)* Rv(pre) L(pre) L(post) RR % RR Area Type 0.70 0.90 20% 0.23 131.95 267.30 148.54 56% Development Area 0.35 0.85 0% 0.05 14.34 133.65 121.46 91% Drinking Water Watersheds 0.40 0.85 1% 0.06 19.34 152.74 136.30 89% Other Rural Land Interim Manual, Page 70 rev.31 March 1998 GEB Short Version BMP Computations For Worksheets 2 -6 Albemarle County Water Protection Ordinance: Modified Simple Method Plan: Luxor Subdivision Water Resources Area: Development Area Preparer: Rivanna Engineering Date: 11/16/2004 Project Drainage Area Designation DA#2 L storm pollutant export in pounds, L=[P(Pj)Rv/12][C(A)2.72] Rv mean runoff coefficient, Rv=0.05+0.009(1) Pj small storm correction factor,0.9 I percent imperviousness P annual precipitation,43"in Albemarle A project area in acres in subject drainage area, A= 49.70 C pollutant concentration,mg/I or ppm target phosphorus f factor applied to RR ✓ required treatment volume in cy,0.5"over imperv.area= A(I)43560(0.5/12)/27 RR required removal , L(post)-f x L(pre) %RR removal efficiency, RR100/L(post) Impervious Cover Computation(values in feet&square feet) Item pre-development Area post-development Area Roads Length Width subtotal Length Width subtotal O 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Driveways Length Width no. subtotal Length Width no. subtotal and walks 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 Parking Lots 1 2 3 4 1 2 3 4 0 Structures Area no. subtotal Area no. subtotal O 0 0 0 0 0 O 0 0 0 0 0 O 0 0 0 Actively-grazed pasture& Area Area yards and cultivated turf 0 x 0.08= 0 1604932 x 0.08= 128394.6 Active crop land Area Area x0.25= 0 x0.25= 0 Other Impervious Areas 0 560000 Impervious Cover 0% 32% l(pre) l(post) Rv(post) V 0.34 1062.3 New Development(For Development Areas,existing impervious cover<=20%) C f I(pre)* Rv(pre) L(pre) L(post) RR % RR Area Type 0.70 1.00 20% 0.23 70.17 102.57 32.40 32% Development Area 0.35 1.00 0% 0.05 7.63 51.29 43.66 85% Drinking Water Watersheds 0.40 1.00 1% 0.06 10.29 58.61 48.33 82% Other Rural Land *min.values Redevelopment(For Development Areas,existing impervious cover>20%) C f I(pre)* Rv(pre) L(pre) L(post) RR %RR Area Type 0.70 0.90 20% 0.23 70.17 102.57 39.41 38% Development Area 0.35 0.85 0% 0.05 7.63 51.29 44.80 87% Drinking Water Watersheds 0.40 0.85 1% 0.06 10.29 58.61 49.87 85% Other Rural Land Interim Manual,Page 70 rev.31 March 1998 GEB Short Version BMP Computations For Worksheets 2 -6 Albemarle County Water Protection Ordinance: Modified Simple Method Plan: Luxor Subdivision Water Resources Area: Development Area Preparer: Rivanna Engineering Date: 1/6/2005 Project Drainage Area Designation DA#3 L storm pollutant export in pounds, L= [P(Pj)Rv/12] [C(A)2.72] Rv mean runoff coefficient, Rv=0.05+0.009(1) Pj small storm correction factor,0.9 I percent imperviousness P annual precipitation,43"in Albemarle A project area in acres in subject drainage area, A= 34.60 C pollutant concentration, mg/I or ppm target phosphorus f factor applied to RR ✓ required treatment volume in cy,0.5"over imperv.area= A(1)43560(0.5/12)/27 RR required removal, L(post) -f x L(pre) %RR removal efficiency, RR100/L(post) Impervious Cover Computation(values in feet&square feet) Item pre-development Area post-development Area Roads Length Width subtotal Length Width subtotal O 0 0 0 0 0 O 0 0 0 0 0 O 0 0 0 o 0 0 0 Driveways Length Width no. subtotal Length Width no. subtotal and walks 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 O 0 Parking Lots 1 2 3 4 1 2 3 4 0 Structures Area no. subtotal Area no. subtotal O 0 0 0 0 0 O 0 0 0 0 0 O 0 0 0 Actively-grazed pasture& Area Area yards and cultivated turf 0 x 0.08= 0 960676 x 0.08= 76854.08 Active crop land Area Area x0.25= 0 x0.25= 0 Other Impervious Areas 546500 Impervious Cover 0% 41% l(pre) l(post) Rv(post) V 0.42 962.0 New Development(For Development Areas,existing impervious cover<=20%) C f I(pre)* Rv(pre) L(pre) L(post) RR % RR Area Type 0.70 1.00 20% 0.23 48.85 89.69 40.83 46% Development Area 0.35 1.00 0% 0.05 5.31 44.84 39.53 88% Drinking Water Watersheds 0.40 1.00 1% 0.06 7.16 51.25 44.09 86% Other Rural Land *min.values Redevelopment(For Development Areas,existing impervious cover>20%) C f I(pre)* Rv(pre) L(pre) L(post) RR % RR Area Type 0.70 0.90 20% 0.23 48.85 89.69 45.72 51% Development Area 0.35 0.85 0% 0.05 5.31 44.84 40.33 90% Drinking Water Watersheds 0.40 0.85 1% 0.06 7.16 51.25 45.16 88% Other Rural Land Interim Manual, Page 70 rev.31 March 1998 GEB