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Home My WebLink AboutWPO201700081 Calculations WPO VSMP 2017-12-12 BROOKDALE STORMWATER MANAGEMENT CALCULATIONS HAMRICK ENGINEERING, P.C. 156 LAUREL HILL ROAD VERONA, VIRGINIA 24482 DATE: 12-12-17 11‘131Nd013/130 14400, �I.LINnWw03 BLOT 5 0 83,E C3/V3332! DESIGN NARRATIVE Project Location, Description & Justification The subject property is located between the south side of Country Green Road and the north side of Mountainwood Road. Access to the property is via Country Green Road and Mountainwood Road. The total acreage of the project is 5.756 acres. The property is bound by a planned residential development to the west side and a vacant residential property on the east side. The proposed site development consists of 96 apartment units contained within four buildings. The developed site also includes a community building, along with all of the associated parking and utilities. To facilitate the project, Albemarle County issued a zoning certification for 96 units on September 26, 2017. Natural Resources and Existing Conditions Development of the site has been contemplated for a number of years. The site has been disturbed by grading operations in the past as evidenced by existing manmade earthen berms and the age of some of the trees. The ground cover consists of dense trees, thick underbrush, and grass. The Albemarle County Service Authority has a sewer main running through the property and water mains in both Country Green Road and Mountainwood Road. Power lines are also located on the Sift"' No karst or wetland features are located on the property. In addition no known rare, threatened or endangered species have been located on the property or downstream of the property. Stormwater Management Quantity The purpose of the following stormwater calculation is to document the proposed stormwater management system will reduce the post developed runoff from the on-site generated 1-year, 2-year, and 10-year, 24 hour storm events below the release rate established by the Virginia Energy Balance Equation. A stormwater detention basin was chosen as the BMP to act as the stormwater quantity control device. Hydrographs 1 and 2 establish the 2-year and 25-year combined runoff from both on- site and off-site areas directed to the stormwater facility during its function as a temporary sediment basin. Hydrographs 3 and 4 show the routing results of these storm events. Hydrograph numbers 5, 6, and 7 represent the on-site pre-developed runoff for the 1, 2, and 10-year, 24 hour events. Hydrographs 8, 9, 10, and 11 represent the on-site post-developed runoff from the 1 , 2, 10, and 100-year, 24 hour events. Hydrographs 12, 13, and 14 show the routing results for the on-site 1, 2, and 10-year storm events. As shown by the calculations, the peak flow from these hydrographs is less than the allowable release rate established by the Virginia Energy Balance Equation. Thus, all State and Albemarle County requirements have been satisfied. Flooding Hydrographs 15 and 16 represent the off-site runoff for the10-year and 100-year, 24 hour storm events. Hydrographs 17 and 18 combine hydrographs 15 and 10 and 16 and 11 to establish the total 10-year and 100-year runoff directed to the stormwater facility. Hydrographs 19 and 20 routes the total 10-year and 100-year events through the basin determining the basin size and outfall structures are adequately sized to control the flooding hydrographs within the basin and that all down stream drainage components are adequate to pass the flooding events. Quality Offsite nutrient credits will be purchased to satisfy the 5.11 pounds of phosphorus per year that must be removed from the development. Adequate Downstream System Runoff from this project is directed to an existing 42-inch storm sewer system under Mountainwood Road. This existing storm sewer and the existing ditch it discharges into are both adequate. Soils The general project soils are defined under separate cover within the attached Stormwater Pollution Prevention Plan and specifically within the project geotechnical report. STORMWATER MANAGEMENT CALCULATIONS Drainage Area Total on-site area to detention basin = 5.76 acres Precipitation Data for 24-hour Storms 1 year = 3.05 inches 2year = 3.69 inches 10yr = 5.58 inches 100year = 9.16 inches Soil Hydrologic Group Soils are in the C hydrologic group Existing Runoff Coefficients 7.76 acres woods & grass combo @ CN=72 Proposed Runoff Coefficients Sow' 0.53 acres forest/open space @ CN=70 2.48 acres in managed turf @ CN=74 2.75 acres roof top & pavement @ CN=98 5.76 acre total Ccomp = 85 Time of Concentration Existing Conditions 65 LF sheet flow over woods & grass at C=0.20 w/ 4.62% slope, TC=13.25 min 1180 LF ditch flow w/ H=63.15', TC=6.0 min Total TC = 13.25+ 6.0 = 19.25 min (use 19.0 min) Proposed Conditions 22 LF sheet flow over grass at C=0.20 w/ 12.50% slope, TC=6.80 min 209 LF pipe flow w/ H=18.04', TC = 1.25 min x 0.20 = 0.25 min 857 LF ditch flow w/ H=36.74', TC = 4.90 min Total TC = 6.80 + 0.25 +4.90 = 11 .95 min (use 12.0 min) Allowable Release Rate from the Energy Balance Equation Hydrographs 5, 6, and 7 calculate the pre-development runoff quantities for the 1-year, Skr' 2-year, and 10-year, 24 hour rainfall events. The results are as follows: 1 year = 4.85 cfs = q,pre 2year = 7.41 cfs = g2pre 1 Oyear = 16.72 cfs = q,opre The pre-developed RV or Q in inches can be computed as follows: Q = (P - 0.2S)2/ (P + 0.8S) Where Q = runoff depth in inches P = rainfall depth in inches or 3.05" for 1 yr, 3.69" for 2yr & 5.58" for 10yr S = potential maximum retention after runoff begins in inches CN = curve number Where S = 1000/CN - 10 or 1000/72 - 10 = 3.89 Thus: Q1pre= (3.05 - (0.2 x 3.89))2/ (3.05 + (0.8 x 3.89)) = 0.84 Similarly Q2pre= 1 .25 Q10pre= 2.65 From the results from the State RRM spreadsheet the RV or Q in inches is given as Q1post = 1.63 Q2post = 2.18 Q1Opost = 3.91 The energy balance equation which determines the allowable release rate can be solved as follows: q,post = (0.80 x (glpre x Q1pre)) / Qlpost = (0.80 x (4.85 x 0.84)) / 1 .63 = 2.00 cfs g2post = (0.80 x (g2pre X Q2re)) / Q2post = (0.80 x (7.41 x 1.25)) / 2.18 = 2.18 cfs Cllopost = (0.80 x (g10pre x Qlopre)) / Qiopost = (0.80 x (16.72 x 2.65)) / 3.91 = 9.07 cfs Routing Results 1 yr post release rate = 1 .81 cfs < 2.00 (hydrograph no. 12) 2yr post release rate = 2.09 cfs < 2.18 (hydrograph no. 13) 10yr post release rate = 8.67 cfs < 9.07 (hydrograph no. 14) The total 10-year event is contained within the pond and exits the facility through the principal spillway. (See hydrograph 19) The total 100-year event is contained within the pond and exits the facility through both the principal and emergency spillway. (See hydrograph 20) -lydrograph Summary Report Page 1 Hyd. Hydrograph Peak Time Time to Volume Return Inflow Maximum Maximum Hydrograph No. type flow interval peak period hyd(s) elevation storage description (origin) (cfs) (min) (min) (cuft) (yrs) (ft) (cuft) 1 SCS Runoff 27.8 6 726 112,705 2 ---- 2-yr construction 2 SCS Runoff 62.0 6 726 255,873 25 ---- 25-yr construction 3 Reservoir 25.9 6 732 112,705 2 1 460.15 57,687 2-yr construction 4 Reservoir 61.4 6 732 255,872 25 2 460.64 62,588 25-yr construction 5 SCS Runoff 4.8 6 726 16,426 1 ---- lyr Pre 6 SCS Runoff 7.4 6 726 24,444 2 ---- 2yr Pre 7 SCS Runoff 16.7 6 720 52,013 10 ---- 10yr Pre 8 SCS Runoff 10.4 6 720 31,958 1 ---- 1yr Post 9 SCS Runoff 13.9 6 720 42,787 2 ---- 2yr Post 10 SCS Runoff 24.8 6 720 76,600 10 ---- 10yr Post 11 SCS Runoff 45.4 6 720 143,819 100 ---- 100yr Post 12 Reservoir 1.8 6 744 31,958 1 8 453.60 12,564 1yr Route 13 Reservoir 2.1 6 750 42,787 2 9 454.68 17,803 2yr Route 14 Reservoir 8.7 6 738 76,600 10 10 456.58 28,948 10yr Route 15 SCS Runoff 36.5 6 726 147,762 10 ---- 10-yr offsite 16 SCS Runoff 70.5 6 726 288,673 100 ---- 100-yr offsite Combine 59.0 6 726 224,362 10 10+ 15 Total 10yr 18 Combine 111.1 6 726 432,491 100 11 +16 Total 100yr 19 Reservoir 44.4 6 732 224,362 10 17 459.51 51,959 Total 10yr 20 Reservoir 102.6 6 726 432,491 100 18 461.01 66,326 Total 100yr P ' file: BROOKDALE.GPW IDF file: Alebmarle.IDF Run date: 12-14-2017 Hydrograph Report Page 1 English Hyd. No. 1 2-yr construction Hydrograph type = SCS Runoff Peak discharge = 27.81 cfs Storm frequency = 2 yrs Time interval = 6 min Drainage area = 13.19 ac Curve number = 87 Basin Slope = 4.8 % Hydraulic length = 2396 ft Tc method = LAG Time of conc. (Tc) = 23.1 min Total precip. = 3.69 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Total Volume=112,705 cuft Hydrograph Discharge Table Time -- Outflow (hrs cfs) 12.00 22.38 12.10 27.81 « 12.20 27.16 12.30 22.09 12.40 16.75 Swore ...End Hydrograph Report Page 1 English Hyd. No. 2 25-yr construction Hydrograph type = SCS Runoff Peak discharge = 62.02 cfs Storm frequency = 25 yrs Time interval = 6 min Drainage area = 13.19 ac Curve number = 87 Basin Slope = 4.8 % Hydraulic length = 2396 ft Tc method = LAG Time of conc. (Tc) = 23.1 min Total precip. = 6.86 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Total Volume=255,873 cuft Hydrograph Discharge Table Time -- Outflow (hrs cfs) 12.00 51.05 12.10 62.02 « 12.20 59.62 12.30 47.96 ...End Slaw' Hydrograph Report Page 1 English Hyd. No. 3 2-yr construction rt Hydrograph type = Reservoir Peak discharge = 25.93 cfs Storm frequency = 2 yrs Time interval = 6 min Inflow hyd. No. = 1 Reservoir name = POND SB Max. Elevation = 460.15 ft Max. Storage = 57,687 cuft Storage Indication method used. Total Volume=112,705 cuft Hydrograph Discharge Table Time Inflow Elevation Clv A Clv B Clv C Clv D Wr A Wr B Wr C Wr D Outflow (hrs) cfs ft cfs cfs cfs cfs cfs cfs cfs cfs cfs 12.20 27.16 460.15 72.72 1.80 24.14 25.93 « 12.30 22.09 460.13 72.63 1.79 22.82 24.61 12.40 16.75 460.03 72.27 1.77 17.76 19.53 ...End Softie ..End r Reservoir Report Page 1 English Reservoir No. 1 - POND SB bikawiPond Data Pond storage is based on known contour areas Stage / Storage Table Stage Elevation Contour area Incr. Storage Total storage ft ft sgft cuft cuft 0.00 449.43 200 0 0 0.60 450.00 2,200 684 684 2.60 452.00 3,318 5,518 6,202 4.60 454.00 4,644 7,962 14,164 6.60 456.00 6,118 10,762 24,926 8.60 458.00 7,796 13,914 38,840 10.60 460.00 9,555 17,351 56,191 11.60 461.00 10,473 10,014 66,205 12.33 461.76 11,491 8,017 74,222 Culvert / Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] Rise in = 30.0 6.0 0.0 0.0 Crest Len ft = 15.7 20.0 0.0 0.0 Span in = 30.0 6.0 0.0 0.0 Crest El.ft = 459.51 460.51 0.00 0.00 No. Barrels = 1 1 0 0 Weir Coeff. = 3.00 3.00 0.00 0.00 Sliwinvert El.ft = 449.43 456.28 0.00 0.00 Eqn. Exp. = 1.50 1.50 0.00 0.00 Length ft = 43.0 0.3 0.0 0.0 Multi-Stage = Yes No No No Slope% = 4.07 0.00 0.00 0.00 N-Value = .010 .013 .000 .000 Orif. Coeff. = 0.60 0.60 0.00 0.00 Multi-Stage = Yes No No Tailwater Elevation = 0.00 ft Note:All outflows have been analyzed under inlet and outlet control. Stage / Storage / Discharge Table Stage Storage Elevation Clv A Clv B Clv C Clv D Wr A Wr B Wr C Wr D Discharge ft cuft ft cfs cfs cfs cfs cfs cfs cfs cfs cfs 0.00 0 449.43 0.00 0.00 --- --- 0.00 0.00 --- --- 0.00 0.60 684 450.00 2.31 0.00 --- --- 0.00 0.00 --- --- 0.00 2.60 6,202 452.00 27.15 0.00 --- --- 0.00 0.00 --- --- 0.00 4.60 14,164 454.00 43.06 0.00 --- --- 0.00 0.00 --- --- 0.00 6.60 24,926 456.00 54.51 0.00 --- --- 0.00 0.00 --- --- 0.00 8.60 38,840 458.00 63.94 1.15 --- --- 0.00 0.00 --- --- 1.15 10.60 56,191 460.00 72.15 1.76 --- --- 16.15 0.00 --- --- 17.92 11.60 66,205 461.00 75.92 0.00 --- --- 85.66 20.58 --- --- 96.50 12.33 74,222 461.76 78.66 0.00 --- --- 158.96 83.85 --- --- 162.52 Hydrograph Report Page 1 English i. Hyd. No. 4 25-yr construction rt Hydrograph type = Reservoir Peak discharge = 61.37 cfs Storm frequency = 25 yrs Time interval = 6 min Inflow hyd. No. = 2 Reservoir name = POND SB Max. Elevation = 460.64 ft Max. Storage = 62,588 cuft Storage Indication method used. Total Volume=255,872 cuft Hydrograph Discharge Table Time Inflow Elevation Clv A Clv B Clv C Clv D Wr A Wr B Wr C Wr D Outflow (hrs) cfs ft cfs cfs cfs cfs cfs cfs cfs cfs cfs 12.00 51.05 460.43 73.79 1.87 41.53 43.40 12.10 62.02 « 460.62 74.50 1.91 54.98 2.24 59.13 12.20 59.62 460.64 74.58 1.92 56.53 2.92 61.37« 12.30 47.96 460.54 74.20 1.89 49.22 0.64 51.75 12.40 35.90 460.39 73.63 1.86 38.71 40.57 ...End Reservoir Report Page 1 English Reservoir No. 1 - POND SB ' Pond Data Pond storage is based on known contour areas Stage / Storage Table Stage Elevation Contour area Incr. Storage Total storage ft ft sgft cuft cuft 0.00 449.43 200 0 0 0.60 450.00 2,200 684 684 2.60 452.00 3,318 5,518 6,202 4.60 454.00 4,644 7,962 14,164 6.60 456.00 6,118 10,762 24,926 8.60 458.00 7,796 13,914 38,840 10.60 460.00 9,555 17,351 56,191 11.60 461.00 10,473 10,014 66,205 12.33 461.76 11,491 8,017 74,222 Culvert / Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] IDI Rise in = 30.0 6.0 0.0 0.0 Crest Len ft = 15.7 20.0 0.0 0.0 Span in = 30.0 6.0 0.0 0.0 Crest El.ft = 459.51 460.51 0.00 0.00 ii_No. Barrels = 1 1 0 0 Weir Coeff. = 3.00 3.00 0.00 0.00 141.'Invert El.ft = 449.43 456.28 0.00 0.00 Eqn. Exp. = 1.50 1.50 0.00 0.00 Length ft = 43.0 0.3 0.0 0.0 Multi-Stage = Yes No No No Slope% = 4.07 0.00 0.00 0.00 N-Value = .010 .013 .000 .000 Orif. Coeff. = 0.60 0.60 0.00 0.00 Multi-Stage = Yes No No Tailwater Elevation = 0.00 ft Note:All outflows have been analyzed under inlet and outlet control. Stage / Storage / Discharge Table Stage Storage Elevation Clv A Clv B Clv C Clv D Wr A Wr B Wr C Wr D Discharge ft cuft ft cfs cfs cfs cfs cfs cfs cfs cfs cfs 0.00 0 449.43 0.00 0.00 --- --- 0.00 0.00 --- --- 0.00 0.60 684 450.00 2.31 0.00 --- --- 0.00 0.00 --- --- 0.00 2.60 6,202 452.00 27.15 0.00 --- --- 0.00 0.00 --- --- 0.00 4.60 14,164 454.00 43.06 0.00 --- --- 0.00 0.00 --- --- 0.00 6.60 24,926 456.00 54.51 0.00 --- --- 0.00 0.00 --- --- 0.00 8.60 38,840 458.00 63.94 1.15 --- --- 0.00 0.00 --- --- 1.15 10.60 56,191 460.00 72.15 1.76 --- --- 16.15 0.00 --- --- 17.92 11.60 66,205 461.00 75.92 0.00 --- --- 85.66 20.58 --- --- 96.50 12.33 74,222 461.76 78.66 0.00 --- --- 158.96 83.85 --- --- 162.52 Hydrograph Report Page 1 English Hyd. No. 5 1 yr Pre Hydrograph type = SCS Runoff Peak discharge = 4.85 cfs Storm frequency = 1 yrs Time interval = 6 min Drainage area = 5.76 ac Curve number = 72 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 19 min Total precip. = 3.05 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Total Volume=16,426 cuft Hydrograph Discharge Table Time -- Outflow (hrs cfs) 12.00 4.66 12.10 4.85 « 12.20 3.34 ...End Hydrograph Report Page 1 English Hyd. No. 6 2yr Pre Hydrograph type = SCS Runoff Peak discharge = 7.41 cfs Storm frequency = 2 yrs Time interval = 6 min Drainage area = 5.76 ac Curve number = 72 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 19 min Total precip. = 3.69 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Total Volume=24,444 cuft Hydrograph Discharge Table Time -- Outflow (hrs cfs) 12.00 7.39 12.10 7.41 « 12.20 4.98 ...End Stool ` .v' Hydrograph Report Page 1 English Hyd. No. 7 10yr Pre Hydrograph type = SCS Runoff Peak discharge = 16.72 cfs Storm frequency = 10 yrs Time interval = 6 min Drainage area = 5.76 ac Curve number = 72 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 19 min Total precip. = 5.58 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Total Volume=52,013 cuft Hydrograph Discharge Table Time -- Outflow (hrs cfs) 11.90 10.78 12.00 16.72 « 12.10 15.94 12.20 10.38 ...End Sar ' Hydrograph Report Page 1 English Hyd. No. 8 1 yr Post Hydrograph type = SCS Runoff Peak discharge = 10.37 cfs Storm frequency = 1 yrs Time interval = 6 min Drainage area = 5.76 ac Curve number = 85 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 12 min Total precip. = 3.05 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Total Volume=31,958 cuft Hydrograph Discharge Table Time -- Outflow (hrs cfs) 11.90 6.86 12.00 10.37« 12.10 9.75 12.20 6.28 ...End Hydrograph Report Page 1 English Hyd. No. 9 Sbo, 2yr Post Hydrograph type = SCS Runoff Peak discharge = 13.93 cfs Storm frequency = 2 yrs Time interval = 6 min Drainage area = 5.76 ac Curve number = 85 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 12 min Total precip. = 3.69 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Total Volume=42,787 cuft Hydrograph Discharge Table Time -- Outflow (hrs cfs) 11.90 9.41 12.00 13.93 « 12.10 12.93 ...End Hydrograph Report Page 1 English Hyd. No. 10 10yr Post Hydrograph type = SCS Runoff Peak discharge = 24.76 cfs Storm frequency = 10 yrs Time interval = 6 min Drainage area = 5.76 ac Curve number = 85 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 12 min Total precip. = 5.58 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Total Volume=76,600 cuft Hydrograph Discharge Table Time -- Outflow (hrs cfs) 11.90 17.28 12.00 24.76 « 12.10 22.52 ...End Stir' Hydrograph Report Page 1 English Hyd. No. 11 100yr Post Hydrograph type = SCS Runoff Peak discharge = 45.39 cfs Storm frequency = 100 yrs Time interval = 6 min Drainage area = 5.76 ac Curve number = 85 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 12 min Total precip. = 9.16 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Total Volume=143,819 cuft Hydrograph Discharge Table Time -- Outflow (hrs cfs) 11.90 32.47 12.00 45.39 « 12.10 40.66 ...End Hydrograph Report Page 1 English 4yd. No. 12 %oi1 yr Route Hydrograph type = Reservoir Peak discharge = 1 .81 cfs Storm frequency = 1 yrs Time interval = 6 min Inflow hyd. No. = 8 Reservoir name = POND 1 Max. Elevation = 453.60 ft Max. Storage = 12,564 cuft Storage Indication method used. Total Volume=31,958 cuft Hydrograph Discharge Table Time Inflow Elevation Clv A Clv B Clv C Clv D Wr A Wr B Wr C Wr D Outflow (hrs) cfs ft cfs cfs cfs cfs cfs cfs cfs cfs cfs 12.00 10.37 « 451.86 25.81 1.34 1.34 12.10 9.75 452.68 33.39 1.58 1.58 12.20 6.28 453.25 37.90 1.73 1.73 12.30 3.31 453.53 39.86 1.80 1.80 12.40 1.89 453.60 40.37 1.81 1.81 « 12.50 1.62 453.59 40.33 1.81 1.81 12.60 1.36 453.56 40.13 1.81 1.81 12.70 1.17 453.52 39.79 1.79 1.79 12.80 1.05 453.46 39.36 1.78 1.78 12.90 0.97 453.39 38.88 1.76 1.76 3.00 0.91 453.31 38.34 1.74 1.74 13.10 0.85 453.24 37.77 1.73 1.73 13.20 0.80 453.15 37.17 1.71 1.71 13.30 0.75 453.07 36.54 1.68 1.68 13.40 0.72 452.99 35.89 1.66 1.66 13.50 0.68 452.90 35.21 1.64 1.64 13.60 0.65 452.81 34.51 1.62 1.62 13.70 0.62 452.73 33.79 1.59 1.59 13.80 0.59 452.64 33.05 1.57 1.57 13.90 0.56 452.55 32.29 1.54 1.54 14.00 0.54 452.46 31.51 1.52 1.52 14.10 0.51 452.37 30.72 1.49 1.49 14.20 0.49 452.28 29.89 1.47 1.47 14.30 0.48 452.19 29.08 1.44 1.44 14.40 0.47 452.11 28.22 1.42 1.42 14.50 0.46 452.02 27.38 1.39 1.39 14.60 0.45 451.91 26.36 1.36 1.36 14.70 0.44 451.80 25.28 1.32 1.32 14.80 0.44 451.69 23.95 1.28 1.28 14.90 0.43 451.58 22.60 1.25 1.25 15.00 0.42 451.47 21.03 1.21 1.21 15.10 0.41 451.37 19.50 1.18 1.18 15.20 0.40 451.27 17.97 1.14 1.14 15.30 0.39 451.18 16.53 1.11 1.11 ...End Reservoir Report Page English Reservoir No. 2 - POND 1 b*ariPond Data Pond storage is based on known contour areas Stage / Storage Table Stage Elevation Contour area Incr. Storage Total storage ft ft sqft cuft cuft 0.00 449.43 200 0 0 0.60 450.00 2,200 684 684 2.60 452.00 3,318 5,518 6,202 4.60 454.00 4,644 7,962 14,164 6.60 456.00 6,118 10,762 24,926 8.60 458.00 7,796 13,914 38,840 10.60 460.00 9,555 17,351 56,191 11.60 461.00 10,473 10,014 66,205 12.33 461.76 11,491 8,017 74,222 Culvert/ Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] Rise in = 30.0 6.0 10.0 30.0 Crest Len ft = 15.7 25.0 0.0 0.0 Span in = 30.0 6.0 10.0 30.0 Crest El.ft = 459.51 460.51 0.00 0.00 No. Barrels = 1 1 2 1 Weir Coeff. = 3.00 3.00 3.00 0.00 Invert El.ft = 449.43 449.43 454.70 456.60 Eqn. Exp. = 1.50 1.50 1.50 0.00 Length ft = 43.0 0.3 0.3 0.3 Multi-Stage = Yes No No No Slope% = 4.07 0.00 0.00 0.00 N-Value = .010 .013 .013 .013 Orif. Coeff. = 0.60 0.60 0.60 0.60 Multi-Stage = Yes Yes Yes Tailwater Elevation = 3.24 ft Note:All outflows have been analyzed under inlet and outlet control. Stage / Storage / Discharge Table Stage Storage Elevation Clv A Clv B Clv C Clv D Wr A Wr B Wr C Wr D Discharge ft cuft ft cfs cfs cfs cfs cfs cfs cfs cfs cfs 0.00 0 449.43 0.00 0.00 0.00 0.00 0.00 0.00 --- --- 0.00 0.60 684 450.00 2.31 0.53 0.00 0.00 0.00 0.00 --- --- 0.53 2.60 6,202 452.00 27.15 1.38 0.00 0.00 0.00 0.00 --- --- 1.38 4.60 14,164 454.00 43.06 1.91 0.00 0.00 0.00 0.00 --- --- 1.91 6.60 24,926 456.00 54.51 2.24 4.86 0.00 0.00 0.00 --- --- 7.10 8.60 38,840 458.00 63.94 2.43 8.92 11.85 0.00 0.00 --- --- 23.20 10.60 56,191 460.00 72.15 1.92 10.65 34.65 16.15 0.00 --- --- 63.38 11.60 66,205 461.00 75.92 3.04 16.87 75.92 85.66 25.72 --- --- 101.64 12.33 74,222 461.76 78.66 3.15 17.48 78.66 158.96 104.82 --- --- 183.48 Hydrograph Report Page 1 English Hyd. No. 13 2yr Route Hydrograph type = Reservoir Peak discharge = 2.09 cfs Storm frequency = 2 yrs Time interval = 6 min Inflow hyd. No. = 9 Reservoir name = POND 1 Max. Elevation = 454.68 ft Max. Storage = 17,803 cuft Storage Indication method used. Total Volume=42,787 cuft Hydrograph Discharge Table Time Inflow Elevation Clv A Clv B Clv C Clv D Wr A Wr B Wr C Wr D Outflow (hrs) cfs ft cfs cfs cfs cfs cfs cfs cfs cfs cfs 12.00 13.93 « 452.54 32.22 1.54 1.54 12.10 12.93 453.60 40.40 1.81 1.81 12.20 8.26 454.29 44.89 1.97 1.97 12.30 4.31 454.57 46.64 2.03 2.03 12.40 2.45 454.66 47.17 2.05 0.03 2.08 12.50 2.09 454.68 47.24 2.05 0.04 2.09 « 12.60 1.76 454.67 47.18 2.05 0.03 2.08 12.70 1.51 454.64 47.01 2.04 0.02 2.06 12.80 1.35 454.60 46.76 2.03 2.03 12.90 1.25 454.55 46.47 2.02 2.02 Iii_.„13.00 1.17 454.49 46.14 2.01 2.01 13.10 1.09 454.43 45.79 2.00 2.00 13.20 1.02 454.37 45.40 1.99 1.99 13.30 0.97 454.31 44.99 1.97 1.97 13.40 0.92 454.24 44.57 1.96 1.96 13.50 0.87 454.17 44.12 1.94 1.94 13.60 0.83 454.09 43.66 1.93 1.93 13.70 0.79 454.02 43.18 1.91 1.91 13.80 0.75 453.92 42.56 1.89 1.89 13.90 0.72 453.82 41.88 1.86 1.86 14.00 0.69 453.72 41.18 1.84 1.84 14.10 0.66 453.61 40.47 1.82 1.82 14.20 0.63 453.51 39.73 1.79 1.79 14.30 0.61 453.40 39.00 1.77 1.77 14.40 0.60 453.30 38.24 1.74 1.74 14.50 0.59 453.20 37.49 1.72 1.72 14.60 0.58 453.10 36.72 1.69 1.69 14.70 0.57 453.00 35.96 1.66 1.66 14.80 0.56 452.90 35.18 1.64 1.64 14.90 0.55 452.80 34.41 1.61 1.61 15.00 0.53 452.70 33.61 1.59 1.59 15.10 0.52 452.61 32.83 1.56 1.56 15.20 0.51 452.52 32.01 1.54 1.54 15.30 0.50 452.42 31.21 1.51 1.51 15.40 0.49 452.33 30.38 1.48 1.48 15.50 0.48 452.24 29.55 1.46 1.46 4414.10, Continues on next page... 2yr Route Page 2 Hydrograph Discharge Table ikiiiiiiTime Inflow Elevation Clv A Clv B Clv C Clv D Wr A Wr B Wr C Wr D Outflow (hrs) cfs ft cfs cfs cfs cfs cfs cfs cfs cfs cfs 15.60 0.46 452.16 28.70 1.43 1.43 15.70 0.45 452.07 27.84 1.41 1.41 15.80 0.44 451.98 26.94 1.38 1.38 15.90 0.43 451.86 25.82 1.34 1.34 16.00 0.42 451.74 24.59 1.30 1.30 16.10 0.41 451.63 23.25 1.26 1.26 ...End Reservoir Report Page 1 English Reservoir No. 2 - POND 1 illoimiPond Data Pond storage is based on known contour areas Stage / Storage Table Stage Elevation Contour area Incr. Storage Total storage ft ft sqft cuft cuft 0.00 449.43 200 0 0 0.60 450.00 2,200 684 684 2.60 452.00 3,318 5,518 6,202 4.60 454.00 4,644 7,962 14,164 6.60 456.00 6,118 10,762 24,926 8.60 458.00 7,796 13,914 38,840 10.60 460.00 9,555 17,351 56,191 11.60 461.00 10,473 10,014 66,205 12.33 461.76 11,491 8,017 74,222 Culvert / Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] Rise in = 30.0 6.0 10.0 30.0 Crest Len ft = 15.7 25.0 0.0 0.0 Span in = 30.0 6.0 10.0 30.0 Crest El.ft = 459.51 460.51 0.00 0.00 No. Barrels = 1 1 2 1 Weir Coeff. = 3.00 3.00 3.00 0.00 nvert El.ft = 449.43 449.43 454.70 456.60 Eqn. Exp. = 1.50 1.50 1.50 0.00 Length ft = 43.0 0.3 0.3 0.3 Multi-Stage = Yes No No No Slope% = 4.07 0.00 0.00 0.00 N-Value = .010 .013 .013 .013 Orif. Coeff. = 0.60 0.60 0.60 0.60 Multi-Stage = Yes Yes Yes Tailwater Elevation = 3.24 ft Note:All outflows have been analyzed under inlet and outlet control. Stage / Storage / Discharge Table Stage Storage Elevation Clv A Clv B Clv C Clv D Wr A Wr B Wr C Wr D Discharge ft cuft ft cfs cfs cfs cfs cfs cfs cfs cfs cfs 0.00 0 449.43 0.00 0.00 0.00 0.00 0.00 0.00 --- --- 0.00 0.60 684 450.00 2.31 0.53 0.00 0.00 0.00 0.00 --- --- 0.53 2.60 6,202 452.00 27.15 1.38 0.00 0.00 0.00 0.00 --- --- 1.38 4.60 14,164 454.00 43.06 1.91 0.00 0.00 0.00 0.00 --- --- 1.91 6.60 24,926 456.00 54.51 2.24 4.86 0.00 0.00 0.00 --- --- 7.10 8.60 38,840 458.00 63.94 2.43 8.92 11.85 0.00 0.00 --- --- 23.20 10.60 56,191 460.00 72.15 1.92 10.65 34.65 16.15 0.00 --- --- 63.38 11.60 66,205 461.00 75.92 3.04 16.87 75.92 85.66 25.72 --- --- 101.64 12.33 74,222 461.76 78.66 3.15 17.48 78.66 158.96 104.82 --- --- 183.48 Hydrograph Report Page 1 English Hyd. No. 14 10yr Route Hydrograph type = Reservoir Peak discharge = 8.67 cfs Storm frequency = 10 yrs Time interval = 6 min Inflow hyd. No. = 10 Reservoir name = POND 1 Max. Elevation = 456.58 ft Max. Storage = 28,948 cuft Storage Indication method used. Total Volume=76,600 cuft Hydrograph Discharge Table Time Inflow Elevation Clv A Clv B Clv C Clv D Wr A Wr B Wr C Wr D Outflow (hrs) cfs ft cfs cfs cfs cfs cfs cfs cfs cfs cfs 12.10 22.52 455.86 53.80 2.22 4.04 6.26 12.20 14.19 456.46 56.84 2.30 6.09 0.00 8.39 12.30 7.28 456.58 57.39 2.32 6.35 0.00 8.67 « 12.40 4.10 456.43 56.68 2.30 6.02 0.00 8.32 12.50 3.49 456.21 55.59 2.26 5.50 7.76 12.60 2.93 455.99 54.48 2.24 4.83 7.07 12.70 2.51 455.74 53.18 2.20 3.67 5.86 12.80 2.24 455.52 52.00 2.17 3.33 5.50 ...End Nitro' ..End o' Reservoir Report Page 1 English Reservoir No. 2 - POND 1 Pond Data Pond storage is based on known contour areas Stage / Storage Table Stage Elevation Contour area Incr. Storage Total storage ft ft sgft cuft cuft 0.00 449.43 200 0 0 0.60 450.00 2,200 684 684 2.60 452.00 3,318 5,518 6,202 4.60 454.00 4,644 7,962 14,164 6.60 456.00 6,118 10,762 24,926 8.60 458.00 7,796 13,914 38,840 10.60 460.00 9,555 17,351 56,191 11.60 461.00 10,473 10,014 66,205 12.33 461.76 11,491 8,017 74,222 Culvert / Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] Rise in = 30.0 6.0 10.0 30.0 Crest Len ft = 15.7 25.0 0.0 0.0 Span in = 30.0 6.0 10.0 30.0 Crest El.ft = 459.51 460.51 0.00 0.00 No. Barrels = 1 1 2 1 Weir Coeff. = 3.00 3.00 3.00 0.00 tih.►"Invert El.ft = 449.43 449.43 454.70 456.60 Eqn. Exp. = 1.50 1.50 1.50 0.00 Length ft = 43.0 0.3 0.3 0.3 Multi-Stage = Yes No No No Slope% = 4.07 0.00 0.00 0.00 N-Value = .010 .013 .013 .013 Orif. Coeff. = 0.60 0.60 0.60 0.60 Multi-Stage = Yes Yes Yes Tailwater Elevation = 3.24 ft Note:All outflows have been analyzed under inlet and outlet control. Stage / Storage / Discharge Table Stage Storage Elevation Clv A Clv B Clv C Clv D Wr A Wr B Wr C Wr D Discharge ft cuft ft cfs cfs cfs cfs cfs cfs cfs cfs cfs 0.00 0 449.43 0.00 0.00 0.00 0.00 0.00 0.00 --- --- 0.00 0.60 684 450.00 2.31 0.53 0.00 0.00 0.00 0.00 --- --- 0.53 2.60 6,202 452.00 27.15 1.38 0.00 0.00 0.00 0.00 --- --- 1.38 4.60 14,164 454.00 43.06 1.91 0.00 0.00 0.00 0.00 --- --- 1.91 6.60 24,926 456.00 54.51 2.24 4.86 0.00 0.00 0.00 --- --- 7.10 8.60 38,840 458.00 63.94 2.43 8.92 11.85 0.00 0.00 --- --- 23.20 10.60 56,191 460.00 72.15 1.92 10.65 34.65 16.15 0.00 --- --- 63.38 11.60 66,205 461.00 75.92 3.04 16.87 75.92 85.66 25.72 --- --- 101.64 12.33 74,222 461.76 78.66 3.15 17.48 78.66 158.96 104.82 --- --- 183.48 Hydrograph Report Page 1 English Hyd. No. 15 Nave 10-yr offsite Hydrograph type = SCS Runoff Peak discharge = 36.46 cfs Storm frequency = 10 yrs Time interval = 6 min Drainage area = 11.62 ac Curve number = 81 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 21 min Total precip. = 5.58 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Total Volume=147,762 cuft Hydrograph Discharge Table Time -- Outflow (hrs cfs) 12.00 29.29 12.10 36.46 « 12.20 35.65 12.30 29.02 12.40 22.04 ...End Hydrograph Report Page 1 English Hyd. No. 16 100-yr offsite Hydrograph type = SCS Runoff Peak discharge = 70.46 cfs Storm frequency = 100 yrs Time interval = 6 min Drainage area = 11 .62 ac Curve number = 81 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = USER Time of conc. (Tc) = 21 min Total precip. = 9.16 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Total Volume=288,673 cult Hydrograph Discharge Table Time -- Outflow (hrs cfs) 12.00 57.73 12.10 70.46 « 12.20 67.95 12.30 54.79 ...End Hydrograph Report Page 1 English Hyd. No. 17 Total 10yr Hydrograph type = Combine Peak discharge = 58.98 cfs Storm frequency = 10 yrs Time interval = 6 min 1st inflow hyd. No. = 10 2nd inflow hyd. No. = 15 Total Volume=224,362 cuft Hydrograph Discharge Table Time 1st Inflow + 2nd Inflow = Outflow (hrs) cfs cfs cfs 11.90 17.28 18.70 35.98 12.00 24.76 « 29.29 54.05 12.10 22.52 36.46 « 58.98 « 12.20 14.19 35.65 49.83 12.30 7.28 29.02 36.30 ...End Stool Hydrograph Report Page 1 English Hyd. No. 18 Some Total 100yr Hydrograph type = Combine Peak discharge = 111.12 cfs Storm frequency = 100 yrs Time interval = 6 min 1st inflow hyd. No. = 11 2nd inflow hyd. No. = 16 Total Volume=432,491 cuft Hydrograph Discharge Table Time 1st Inflow + 2nd Inflow = Outflow (hrs) cfs cfs cfs 11.90 32.47 38.00 70.48 12.00 45.39 « 57.73 103.13 12.10 40.66 70.46 « 111.12 « 12.20 25.33 67.95 93.28 12.30 12.83 54.79 67.62 ...End r' Hydrograph Report Page 1 English Hyd. No. 19 Total 10yr Hydrograph type = Reservoir Peak discharge = 44.44 cfs Storm frequency = 10 yrs Time interval = 6 min Inflow hyd. No. = 17 Reservoir name = POND 1 Max. Elevation = 459.51 ft Max. Storage = 51,959 cuft Storage Indication method used. Total Volume=224,362 cuft Hydrograph Discharge Table Time Inflow Elevation Clv A Clv B Clv C Clv D Wr A Wr B Wr C Wr D Outflow (hrs) cfs ft cfs cfs cfs cfs cfs cfs cfs cfs cfs 12.10 58.98 « 458.96 68.00 2.33 10.29 25.06 37.68 12.20 49.83 459.51 70.23 2.26 11.01 30.46 0.71 44.44« 12.30 36.30 459.47 70.06 2.27 10.96 30.07 0.44 43.74 12.40 26.13 459.05 68.38 2.32 10.42 26.07 38.80 12.50 18.72 458.53 66.19 2.39 9.70 19.37 31.46 ...End Reservoir Report Page 1 English Reservoir No. 2 - POND 1 Slow'Pond Data Pond storage is based on known contour areas Stage / Storage Table Stage Elevation Contour area Incr. Storage Total storage ft ft sqft cuft cuft 0.00 449.43 200 0 0 0.60 450.00 2,200 684 684 2.60 452.00 3,318 5,518 6,202 4.60 454.00 4,644 7,962 14,164 6.60 456.00 6,118 10,762 24,926 8.60 458.00 7,796 13,914 38,840 10.60 460.00 9,555 17,351 56,191 11.60 461.00 10,473 10,014 66,205 12.33 461.76 11,491 8,017 74,222 Culvert / Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] Rise in = 30.0 6.0 10.0 30.0 Crest Len ft = 15.7 25.0 0.0 0.0 Span in = 30.0 6.0 10.0 30.0 Crest El.ft = 459.51 460.51 0.00 0.00 No. Barrels = 1 1 2 1 Weir Coeff. = 3.00 3.00 3.00 0.00 .11rr.r►Invert El.ft = 449.43 449.43 454.70 456.60 Eqn. Exp. = 1.50 1.50 1.50 0.00 Length ft = 43.0 0.3 0.3 0.3 Multi-Stage = Yes No No No Slope% = 4.07 0.00 0.00 0.00 N-Value = .010 .013 .013 .013 Orif. Coeff. = 0.60 0.60 0.60 0.60 Multi-Stage = Yes Yes Yes Tailwater Elevation = 3.24 ft Note:All outflows have been analyzed under inlet and outlet control. Stage / Storage / Discharge Table Stage Storage Elevation Clv A Clv B Clv C Clv D Wr A Wr B Wr C Wr D Discharge ft cuft ft cfs cfs cfs cfs cfs cfs cfs cfs cfs 0.00 0 449.43 0.00 0.00 0.00 0.00 0.00 0.00 --- --- 0.00 0.60 684 450.00 2.31 0.53 0.00 0.00 0.00 0.00 --- --- 0.53 2.60 6,202 452.00 27.15 1.38 0.00 0.00 0.00 0.00 --- --- 1.38 4.60 14,164 454.00 43.06 1.91 0.00 0.00 0.00 0.00 --- --- 1.91 6.60 24,926 456.00 54.51 2.24 4.86 0.00 0.00 0.00 --- --- 7.10 8.60 38,840 458.00 63.94 2.43 8.92 11.85 0.00 0.00 --- --- 23.20 10.60 56,191 460.00 72.15 1.92 10.65 34.65 16.15 0.00 --- --- 63.38 11.60 66,205 461.00 75.92 3.04 16.87 75.92 85.66 25.72 --- --- 101.64 12.33 74,222 461.76 78.66 3.15 17.48 78.66 158.96 104.82 --- --- 183.48 Hydrograph Report Page 1 English Hyd. No. 20 Total 100yr Hydrograph type = Reservoir Peak discharge = 102.58 cfs Storm frequency = 100 yrs Time interval = 6 min Inflow hyd. No. = 18 Reservoir name = POND 1 Max. Elevation = 461 .01 ft Max. Storage = 66,326 cuft Storage Indication method used. Total Volume=432,491 cuft Hydrograph Discharge Table Time Inflow Elevation Clv A Clv B Clv C Clv D Wr A Wr B Wr C Wr D Outflow (hrs) cfs ft cfs cfs cfs cfs cfs cfs cfs cfs cfs 12.00 103.13 460.24 73.07 1.24 6.92 31.12 29.39 68.67 12.10 111.12 « 461.01 75.96 3.04 16.88 75.96 86.63 26.62 102.58 « 12.20 93.28 461.01 75.94 3.04 16.88 75.94 86.17 26.20 102.14 12.30 67.62 460.65 74.61 2.98 16.58 74.61 57.26 4.06 78.67 12.40 48.29 460.13 72.65 1.36 7.57 34.05 23.08 66.05 ...End Reservoir Report Page 1 English Reservoir No. 2 - POND 1 Pond Data Pond storage is based on known contour areas Stage / Storage Table Stage Elevation Contour area Incr. Storage Total storage ft ft sqft cuft cuft 0.00 449.43 200 0 0 0.60 450.00 2,200 684 684 2.60 452.00 3,318 5,518 6,202 4.60 454.00 4,644 7,962 14,164 6.60 456.00 6,118 10,762 24,926 8.60 458.00 7,796 13,914 38,840 10.60 460.00 9,555 17,351 56,191 11.60 461.00 10,473 10,014 66,205 12.33 461.76 11,491 8,017 74,222 Culvert / Orifice Structures Weir Structures [A] [B] [C] [D] [A] [B] [C] [D] Rise in = 30.0 6.0 10.0 30.0 Crest Len ft = 15.7 25.0 0.0 0.0 Span in = 30.0 6.0 10.0 30.0 Crest El.ft = 459.51 460.51 0.00 0.00 No. Barrels = 1 1 2 1 Weir Coeff. = 3.00 3.00 3.00 0.00 ✓Invert El.ft = 449.43 449.43 454.70 456.60 Eqn. Exp. = 1.50 1.50 1.50 0.00 Length ft = 43.0 0.3 0.3 0.3 Multi-Stage = Yes No No No Slope% = 4.07 0.00 0.00 0.00 N-Value = .010 .013 .013 .013 Orif. Coeff. = 0.60 0.60 0.60 0.60 Multi-Stage = Yes Yes Yes Tailwater Elevation = 3.24 ft Note:All outflows have been analyzed under inlet and outlet control. Stage / Storage / Discharge Table Stage Storage Elevation Clv A Clv B Clv C Clv D Wr A Wr B Wr C Wr D Discharge ft cuft ft cfs cfs cfs cfs cfs cfs cfs cfs cfs 0.00 0 449.43 0.00 0.00 0.00 0.00 0.00 0.00 --- --- 0.00 0.60 684 450.00 2.31 0.53 0.00 0.00 0.00 0.00 --- --- 0.53 2.60 6,202 452.00 27.15 1.38 0.00 0.00 0.00 0.00 --- --- 1.38 4.60 14,164 454.00 43.06 1.91 0.00 0.00 0.00 0.00 --- --- 1.91 6.60 24,926 456.00 54.51 2.24 4.86 0.00 0.00 0.00 --- --- 7.10 8.60 38,840 458.00 63.94 2.43 8.92 11.85 0.00 0.00 --- --- 23.20 10.60 56,191 460.00 72.15 1.92 10.65 34.65 16.15 0.00 --- --- 63.38 11.60 66,205 461.00 75.92 3.04 16.87 75.92 85.66 25.72 --- --- 101.64 12.33 74,222 461.76 78.66 3.15 17.48 78.66 158.96 104.82 --- --- 183.48 I . � , r 4 o & CO / 46 % a in 7° E / \ p I 2 6 m K w I 1 0 0 0 0 / o o e 0 0 I Cn m I C-e- 2 ) > 1 c ■ \ G p } o ■ o ¥ w , ?:u I § g j E I Cl) c vl 0 o o o § 0 6 C I E co o w i I c o cu I E 2 $ § % 0 0 0 2 \ k § 0 0 N 2 I k § < 6 0 6 s / N / § 2 / / @ $ N Z — o \ _41) 1 % C - - . e _ 4, ■ k le F c k J P I 2 2 0 I 2 ,at § _ s- = E 3 a < cu E to I k \ § o — o E c, o o 0 % Q c : _ a) m Q SA , a) 2 I 4c k C ce > } g § k ( _ c ag c E eu cu cc § k co § \ J2 . k \ \ O.- bo , ' E c \ o 2 ; . > - a § § a z § I > w » . w Q w I e Cr 2 $ & E % 2 2 2 § § � I o _ U. 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I 0. a < M c c c L U L L IC f. o0 u Ce d ..0.1 i C C cc L L 3 C) L L 1E W L T > C1 131 to c N I> 14414Mall 4, I = m IC H I Slaw' BROOKDALE TEMPORARY SEDIMENT BASIN CALCULATIONS w1 HAMRICK ENGINEERING, P. C. 156 LAUREL HILL ROAD VERONA, VIRGINIA 24482 DATE: 12-12-2017 Temporary Sediment Basin Design Area = 13.19 acres, (8.64 off-site and 4.55 on-site) Use a composite runoff curve value of 87 representing 4.55 acres of bare dirt at CN=93 and 8.64 in apartments at CN=84. Thus Q2 = 27.81 (hydrograph # 1) Q25 = 62.02 (hydrograph # 2) Model outlet structure with 6" orifice invert at 456.28 and assume beginning basin water surface elevation is at invert elevation. Top of structure is 459.51, which begins weir flow. Pipe outfall is 43 L. F. of 30" at 4.07% slope. Per the attached storage elevation curve and routing calculations the basin, as designed, meets or exceeds all required criteria. 1992 3.14 TEMPORARY SEDIMENT BASIN DESIGN DATA SHEET (with or without an emergency spillway) Project 0/ 4l ci Basin # /a� / Location AZ,-f4 . / Go rte,e r- o/ s t Total area draining to basin: /3, /7 acres. Basin Volume Design Wet Storage: 1. Minimum required volume = 67 cu. yds. x Total Drainage Area (acres). 67 cu. yds. x /3,/9 acres = 883. 73 cu. yds. = Z 3, SW.®. c. • 2. Available basin volume = 1S3.73' cu. yds. at elevation ¢5Z,2Y. (From storage - elevation curve) 3. Excavate /,oov cu. yds. to obtain required volume*. * Elevation corresponding to required volume = invert of the dewatering orifice. 4. Available volume before cleanout required. 33 cu. yds. x /3JJ9 acres = ¢3S,z7 cu. yds. _ //, ?5-2 - Z 9 5. Elevation corresponding to cleanout level = ¢S"3, 7 7. (From Storage - Elevation Curve) 6. Distance from invert of the dewatering orifice to cleanout level = Z. 5t ft. (Min. = 1.0 ft.) Dry Storage: 7. Minimum required volume = 67 cu. yds. x Total Drainage Area (acres). 67 cu. yds. x /3,/9 acres = $83. ?_3 cu. yds. = Z 3, 860.9/ c.i III - 112 1992c. 3.14 8. Total available basin volume at crest of riser* = / 76?, 4 cu. yds. at elevation 4 fT,S®. (From Storage - Elevation Curve) * Minimum = 134 cu. yds./acre of total drainage area. 9. Diameter of dewatering orifice = (v in. 10. Diameter of flexible tubing = g in.(diameter of dewatering orifice plus 2 inches). Preliminary Design Elevations 11. Crest of Riser = 4 5-V. 5/ Top of Dam = ¢ca,00 Design High Water = Q . 6¢ YYY Upstream Toe of Dam = 44-9. 43 ice,, Basin Shape 12. Length of Flow L = /__-.4 s - 3 5 f Effective Width We 3°- ¢i If > 2, baffles are not required If < 2, baffles are required Runoff 13. Q2 = Z?. b cfs (From Chapter 5)Lit.(A.r oI rt Pkr1 1,'\ 62s s 14. Q25 = cfs (From Chapter 5) IAyet rt r4 Principal Spillway Design 15. With emergency spillway, required spillway capacity Qp = Q2 = �� g cfs. (riser and barrel) Without emergency spillway,required spillway capacity Qp = Q25 = cfs.(riser and barrel) III - 113 1992 3.14 16. With emergency spillway: Assumed available head (h) = ft. (Using Q2) h = Crest of Emergency Spillway Elevation - Crest of Riser Elevation Without emergency spillway: Assumed available head (h) = ft. (Using Q25) h = Design High Water Elevation - Crest of Riser Elevation 17. Riser diameter (Di) = in. Actual head (h) = ft. 41/4 (From Plate 3.14-8.) Note: Avoid orifice flow conditions. 18. Barrel length (1) = ft. Head (H) on barrel through embankment = ft. (From Plate 3.14-7). 19. Barrel diameter = in. •,, (From Plate 3.14-B [concrete pipe] or Plate 3.14-A [corrugated pipe]). 20. Trash rack and anti-vortex device Diameter = inches. Height = inches. `„ (From Table 3.14-D). •,.) Emergency Spillway Design 21. Required spillway capacity Qe = Q25 - Qp = cfs. 22. Bottom width (b) = ft.; the slope of the exit channel (s) = ft./foot; and the minimum length of the exit channel (x) = ft. (From Table 3.14-C). III - 114 1992 3.14 Anti-Seep Collar Design 23. Depth of water at principal spillway crest (Y) = ft. Slope of upstream face of embankment (Z) = :1. - 4 Slope of principal spillway barrel (Sb) = % Q► Length of barrel in saturated zone (Ls) = ft. a 24. Number of collars required = dimensions = (from Plate 3.14-12). 3 Final Design Elevations 25. Top of Dam = 2 0 Design High Water = .6'64- Emergency 6°6Emergency Spillway Crest = 46C- Principal 'aPrincipal Spillway Crest = 4-69. / Dewatering Orifice Invert = 46'6-.2g Cleanout Elevation = 453. 77 Elevation of Upstream Toe of Dam or Excavated Bottom of "Wet Storage ;� ,� Area" (if excavation was performed) = 4I` '" ,4-j • III - 115 Stage (ft) 0 O 01 0 cn O ^ yk®►� ( '\\ I. o•t � a l II �i // 752. 29 -'' i tN % 14, N �`f� �� 0 0 L3, 8' '-7/ C.S ;,o MICPGv,IfiT T' sry Bey E (I) i 0 1 1 I O Slave 0 O 1 CP moll o ! 4'72./. ¢L 44a ! Z3/ S040, 9/ c,els q/d7 O I O O { 0 1 Co 0 O 0 0 BROOKDALE STORM SEWER CALCULATIONS HAMRICK ENGINEERING, P.C. 156 LAUREL HILL ROAD VERONA, VIRGINIA 24482 DATE: 12-12-17 co 3 J Z d 3 - C- U. cE � d o co CD Cr o tf �J N 2 r c• C 4! h d 0- O r NC.) a 0 C 0 N a t o N. 0 00) co.cGN). 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