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HomeMy WebLinkAboutWPO201300032 Calculations 2021-02-19HYDROLOGIC/HYDRAULIC CALCULATIONS FOR CASCADIA BLOCKS 4-7 SWM-2 LTH 19A, Deecember 1, 2014 ��7 REV: June 10, 2015 O DUSTIN E. GGRECENE ? REV: February 18, 2021 c, A Lic. No. 55833 LOCATION: �o z�4V Tax Map 62, Parcel 25 Tax Map 78, Parcels 59 & 59A S7oNAL V:t G Tax Map 78E, Parcel H1 Rio District, Albemarle County, Virginia PREPARED BY: Roudabush, Gale & Associates, Inc 999 Second Street SE Charlottesville, VA 22902 P: 434.977.0205 INDEX Summary: Approved Calculations: Flood Hydrographs: Post -Development: SWM-2 Inflow: SWM-2 Routed: SWM-2 Pond Report: 2-4 5-32 33-37 38-42 43 Pond Conversion Narrative The purpose of this amendment is to convert the sediment basin facility immediately adjacent to route 20 north into the permanent wet pond facility that will provide stormwater management water quantity and quality control for the 60.77 acre Cascadia subdivision. The northeastern portion of the pond bottom and the eastern 2:1 pond upland slope was located in cut with depths of up to 30. Significant rock was encountered in these locations at the pond elevations, which was fairly hard rock, but was also fairly rippable. The contractor ripped as much of the rock as feasible using a hoe ram but encountered refusal at bedrock. For this reason, the provided pond volume is approximately 90% of the originally approve plans. The permanent pool has been lowered and the outlet structures have been updated so that the stormwater facility performs with the intent of the original approved plans and calculations. Original Design outlet structure parameters Permanent Pool = 350.0', 3" orifice 6" Orifice = 354.40' 60" Crest Riser = 355.70' 16' Emergency Spillway = 356.10' Barrel = 346.0', 68.28' — 30" HDPE @ 1.9% As -Built outlet structure parameters: Permanent Pool = 350.38', 3" orifice 6" Orifice = N/A in sediment basin phase 60" Crest Riser = 356.08' 18' Emergency Spillway = 356.63' Barrel = 346.57', 66' — 30" HDPE @ 2.83% Proposed outlet structure parameters: Permanent Pool = 349.60', 3" orifice 25 deg V-notch Weir = 353.80' 60" Crest Riser = 355.90' 48' Emergency Spillway = 356.00' Barrel = 346.57', 66' — 30" HDPE @ 2.83% Predeveloped, Allowable Flows: Q1.5 = 0.52 cfs Q2.0 = 0.67 cfs Q10 = 8.98 cfs Postdeveloped, Updated Flows: Q1.5 = 0.52 cfs Q2.0 = 0.60 cfs Q10=8.91cfs In addition to meeting the above release rate requirements, the following conditions will also be met: 1. Detain the WQV (P Runoff) and release over 48 hours. 2. Detain the 1 year 24-hour storm and release over 24 hours. Detention of the WOV (V Runoff) and release over 48 hours: WQV = 35,861 cf. Average Flow Rate to Achieve 48 Hour Draw Down: Q = 35,861 cf. / 172,800 sec. Q = 0.208 cfs Orifice Size Needed: A = Q / [64.32 X (h/2)]^1/2 * (0.6) Average h = P; Q = 0.208 cfs A = 0.0611 sf. d = 2 (A/3.14)^1/2 = 0.279 ft. => 3.348 In. Orifice provided =3.0 in. <3.348 in. Detention of the 1 year 24-hour storm and release over 24 hours: 1 year 24-hour storm volume = 227,359 cf. Average Flow Rate to Achieve 24 Hour Draw Down: Q = 227,359 cf. / 86,400 sec. Q = 2.63 cfs Routed Flow for 1-year 24-hour storm = 0.47 efs maximum < 2.63 cfs. Rom sow ems, Inuvrantal Sho1w Total Storage 01) (fl) (soft) (CLd0 (autU 0 0.00 344,00 701 0.000 - 0000 1 1.00 345.00 10,634 4,6B8 4,688 2 2.00 346.00 27,340 4340 23.028 - 3 3.00 347.00 29,861 28.588 51.616 4 4.00 348,00 32,448 31,142 82.759 5 I 5.00 349.00 41.096 36.693 119.442 6 5.60 349.60 422.57 25,003 144.444 7 6.00 350.00 46.756 17,793 162ZS 8 7.00 351.00 49247 47.991 210.229 9 8.00 moo 52.144 50.684 260.913 10 9.00 353.00 55.072 53,596 314.509 ~11 10.00 354.00 57.337 56.195 370.704 12 11.00 355.00 59,608 59.463 429,197 13 12.00 356.00 61.928 60.758 499.925 U 13.00 357.00 64.230 63.069 552.994 15 14.00 358.00 66.617 65.413 618.407 Updated SWM-2 Stage Storage Quality Volume Required = 4 * (WQV) for 65% Removal Efficiency WQ Volume = (1/2in) / 12 * Impervious Area (sqft) = 35,861 cuft (4) * (1/2in) / 12 * 451,761 sqft +408,897 sqft = 143,443 cuft 349.60' - 144,444 cult > 143,443 cuft OK CASCADIA SUBDIVISION HYDROLOGICIHYDRAULIC CALCULATIONS FOR CASCADIA SUBDIVISION - BLOCKS 1-3 December 1, 2014 Revised: June 10, 2015 LOCATION: Tax Map 62, Parcel 25 Tax Map 78, Parcels 59 & 59A Tax Map 78E, Parcel H1 Rio District, Albemarle County, Virginia DEVELOPER: Cascadia Development, LLC. 170 South Pantops Drive Charlottesville, Virginia 22903 PREPARED BY: Dominion Engineering 8 Design, LLC 172 South Pantops Drive Charlottesville, VA 22911 P: 434.979.8121 F: 434.979.1681 INDEX Summary: 2-7 Unit Hydrographs 8-9 Pre -Development: Hydrographs: DA-Pond 2 10-12 Post -Development - Pond-2: Hydrographs: DA-Pond 2 13-17 Water Quality Volume Report: _ 18 SWM-2 & Outlet Structure: _ 19-24 Routed Hydrographs: 25-29 APPROVED by the Albemarle County Community D v opment Department Date W/0 1S �nr��rrr�la�■� CASCADIA SUBDIVISION *Drainage Area Maps are included on Storm Water Management Plan Run -Off Summary Pond 2 Proposed Pond 2 is an approved wet pond facility with an aquatic bench that will provide stormwater quality and detention. Pond 2 was designed for full build out of future Town District phase with an estimated 300,000 sf. of impervious area. The proposed design for the Town District, blocks 1-3, has a total impervious cover of 408,897 sf. The estimated overall drainage area for pond 2 has also increased slightly from 45.54 acres to 46.90 acres. Please refer to the following calculations which will demonstrate that the pond design as approved will accommodate the additional impervious cover and drainage area Because it has been determined that there are inadequate channels downstream, the allowable release rate is determined per Albemarle County Design Standards Manual, Section F. lowering the allowable release rate to a fraction of the pre -forested conditions run-off determined by the calculation below: Q(allowable) <= Qf(Vf / VPost), where Of is flow from the site in a well forested condition (Cn=51), Vf is volume from the site in a well forested condition, and VPost is volume from the site in post -development conditions. In addition to meeting the above release rate requirements, the following conditions will also be met 1. Detain the WQV (1" Runoff) and release over 46 hours 2. Detain the 1 year 24-hour storm and release over 24 hours. CASCADIA SUBDIVISION Pre -Development Conditions: 1.5 Yr. Pre -Development Run -Off (Cn=51) = DA-A = 3.16 cfs 1.5 Yr. Pre -Development Run -Off Volume = 42,253 Sq. Ft. 2 Yr. Pre -Development Run -Off (Cn=51) = DA-A = 3.83 cfs 2 Yr. Pre -Development Run -Off Volume = 47,045 Sq. Ft. 10 Yr. Pre -Development Run -Off (Cn=51) = DA-A = 27.83 cfs 10 Yr. Pre -Development Run -Off Volume = 172,498 Sq. Ft. Post -Development Conditions: 1.5 Yr. Post -Development Run -Off Volume = DA-X = 249,163 Sq. Ft. 2 Yr. Post -Development Run -Off Volume = DA-X = 261,796 Sq. Ft. 10 Yr. Post -Development Run -Off Volume = DA-X = 518,800 Sq. Ft. Allowable Release Rate: Q1.5 (allowable) = 3.16(42,2531256,568) = 0.520 cfs Q2 (allowable) = 3.83(47,045 / 269,636) = 0.668 cfs Q10 (allowable) = 27.83(172,4981534,481) = 8.982 cfs Post -Development Release Rate Summary: Q1.5 Post -Development Routed = 0,48 cfs < 0.520 cfs Q2 Post -Development Routed = 0.52 cfs < 0.668 cfs Q10 Post -Development Routed = 8.83 cfs < 8.982 cfs CASCADIA SUBDIVISION Detention of the WQV 11" Runoff and release over 48 hours: WQV = 35,861 cf. Average Flow Rate to Achieve 48 Hour Draw Down Q = 35,861 cf. / 172,800 sec. Q = 0.208 cfs Orifice Size Needed: A = Q / 164.32 X (h/2)]A1 /2 ' (0.6) Average h = 1'; Q = 0.208 cfs A = 0.0611 sf. d = 2 (A/3.14)A1/2 = 0.279 ft. => 3.348 In. Orifice provided = 3.0 in. < 3.348 in. Detention of the 1 year 24-hour storm and release over 24 hours: 1 year 24-hour storm volume = 231,303.6 cf. (see hydrograph below) Average Flow Rate to Achieve 24 Hour Draw Down: Q = 231.303.6 cf. / 86,400 sec. Q = 2.677 cfs Routed Flow for 1-year 24-hour storm = 0.46 cfs maximum < 2.677 cfs. ( Please Refer Calculations on following Pages ) 4 �� t s r. -- .,I� �__ _ • �; •� CASCADIA SUBDIVISION Map Unit Legend Albamule County, Vlrglnia (VA003) Map Unit Symbol Map Unit Name Acres In A01 Percent of A01 12C Catoctin sill loam, 7l0 15 percent slopes 0.9 2 0% 12E Catoctin sill loam, 25 to 45 percent slopes 62 13 1% 710 Rabun clay loam, 2 to 7 percent slopes 6.5 13 8% 71 C Rabun clay loam, 7 to 15 percent slopes 9.7 20 6% 71D Rabun clay loam, 15 to 25 percent slopes 85 180% 72B3 Rabun clay, 2 to 7 percent slopes, severely eroded 05 1 1% 72C3 Rabun clay, 7 to 15 percent slopes, severely eroded 5.0 10 5% 72D3 Rabun clay, 15 to 25 percent slopes, severely eroded 34 7 3% 72E3 Rabun clay, 25 to 45 percent slopes, severely eroded 26 5 5% 79B Stan silt loam, 2 to 7 percent slopes 38 B 1°/ Totals for Area of Interest 47.0 100.0% Hydrologic Group B Soils: 71B 13.8% 71C 20.6% 71D 18.0% 72B3 1.1 % 72C3 10.5% 72D3 7.3% 72E3 5.5% 76.8% Hydrologic Group C Soils: 12C 2.0% 12E 13.1% 798 8.1% 23.2% Weighted Cn Values: Pavement, Buidling, Patios, Sidewalks: 98 Fair Pasture / Yards: 62 Wooded Area: 57 Gravel: 86 CASCADIA SUBDIVISION Cn Value Calculations: DA-Pond 2 Pre -Development For 1.5-Year, 2-Year & 10-Year Storm Calculations: Cn=51 per Albemarle County Design Standards Manual, Section F. DA-Pond 2 Post -Development (46.90 Acres From Blocks 4-7: Houses (Cn=98) — 4.270 Acres Lead Walks / Patios (Cn=98) — 0.250 Acre Roads (Cn=98) — 3.400 Acre Walks (Cn=98) - 0.550 Acre Neighborhood Center / Amenities (Cn=98) — 0.551 Acre Driveways (Cn=98) —1.350 Acre Proposed Yard (Cn=62) — 5.893 Acre Wooded Area (Cn=57) — 3.000 Acres Parks I Utility Strips (Cn=62) — 1.800 Acres Proposed Blocks 1-3 Buildings (Cn=98) - 4.482 Roads/Parking (Cn=98) - 2.990 Acres Sidewalks (Cn=98) - 1.012 Acre Driveways (Cn=98) - 1.093 Acres Wooded Area (Cn=57) — 2.377 Acres Grass Areas (Cn=62) — 14.072 Acres 19.948 (98) + 21_575(62)+ 5.377(57) = 77.10 => 77 46.90 CASCADIA SUBDIVISION Name: DA-Pond 2 - Pre -Forested Condition (Cn=51) Type: SCS Curvilinear Unit Hydrograph [UNIT HYDROGRAPH INFORMATION] Peak Flow (Qp) = 91.85 (cfs) Time to Peak (Tp) = 23.02 (min) Time of Base (Tb) = 115.10 (min) Volume = 3.89 (ac-ft) Shape Factor = 484.00 Time Step = 2.00 (min) Excess Rain = 1.00 (in) Storm Duration = 4.59 (min) Lag Time = 20.72 (min) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] ------------------------------------------------------ Description Area CN ------------------------------------------------------ Overall Approximation 46.60 51 [TIME CONCENTRATION -- TR-551 SHEET FLOW Manning's Roughness Coef. (n) = 0.40 2-yr 24-hr Rainfall (R) = 3.70 (in) Flow Length (L) = 300.00 (ft) Land Slope (S) = 0.15 (ft/ft) Travel Time of Sheet Flow = 21.48 (min) SHALLOW FLOW K Coefficient (K) = 0.35 Flow Length (L) = 835.00 (ft) watercourse Slope (S) = 0.22 (ft/ft) Travel Time of Shallow Flow = 8.48 (min) Velocity (V) = 1.64 (ft/s) CHANNEL FLOW Hydraulic Radius (R) = 0.26 (ft) Manning's Roughness Coef. (n) 0.03 Flow Length (L) = 1570.00 (ft) Channel Slope (S) = 0.08 (ft/ft) Travel Time of Channel Flow = 4.57 (min) [TIME OF CONCENTRATION] Time of Concentration (Tc) = 34.53 (min) 8 CASCADIA SUBDIVISION Name: Pond 2 - Poet -Development Type: SCS Curvilinear Unit Hydrograph (UNIT HYDROGRAPH INFORMATION] Peak Flow (Qp) = 118.80 (cfs) Time to Peak (Tp) = 17.91 (min) Time of Base (Tb) = 89.56 (min) Volume = 3.92 (ac-ft) Shape Factor = 484.00 Time Step = 2.00 (min) Excess Rain = 1.00 (in) Storm Duration = 3.57 (min) Lag Time = 16.12 (min) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] ------------------ Description Area CN - - - - ---------------------------------- Overall Approximation 46.90 77 [TIME CONCENTRATION -- TR-55] SHEET FLOW Manning's Roughness Coef. (n) = 0.40 2-yr 24-hr Rainfall (R) = 3.70 (in) Flow Length (L) = 300.00 (ft) Land Slope (S) = 0.19 (ft/ft) Travel Time of Sheet Flow = 19.54 (min) SHALLOW FLOW K_Coefficient (K) = 0.35 Flow Length (L) = 430.00 (ft) Watercourse Slope (S) = 0.20 (ft/ft) Travel Time of Shallow Flow = 4.58 (min) Velocity (V) = 1.57 (ft/s) CHANNEL FLOW Hydraulic Radius (R) 0.27 (ft) Manning's Roughness Coef. (n) = 0.01 Flow Length (L) = 1765.00 (ft) Channel Slope (S) 0.05 (ft/ft) Travel Time of Channel Flow 2.75 (min) [TIME OF CONCENTRATION] Time of Concentration (To) = 26.87 (min) 0 CASCADIA SUBDIVISION Name: DA-Pond 2 Pre -Forested 1.5-Year (Cn-51) Type: Computed Flood [HYDROGRAPH INFORMATION] Peak Flow (Qp) 3.16 (cfs) Time to Peak (Tp) = 746.00 (min) Time of Base (Tb) = 1552.59 (min) Volume = 0.97 (ac-ft) Time Step = 2.00 (min) Flow Multiplier = 1.00 [UNIT HYDROGRAPH INFORMATION] Number = 3 Type = SCS Curvilinear Peak Flow (Qp) = 91.85 (cfs) Time to Peak (Tp) = 23.02 (min) Time of Base (Tb) = 115.10 (min) Volume = 3.89 (ac-ft) Shape Factor = 484.00 Time Step: = 2.00 (min) Excess Rain = 1.00 (in) Lag Time = 20.72 (min) [BASIN INFORMATION] I [WEIGHTED WATERSHED AREA] ---------------------------------------------------- Description Area CN ------------------------------------------------------ Overall Approximation 46.60 51 i [TIME CONCENTRATION -- User Defined] Time of Concentration (To) = 34.53 (min) [RAINFALL DESCRIPTION] Distribution Type = SCS II I Total Precipitation = 3.60 (in) Return Period = 1.5 (yr) Storm Duration = 24.00 (hr) 10 C CASCADIA SUBDIVISION Name: DA-Pond 2 Pre -Forested 2-Year (Cn-51) Type: Computed Flood [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 3.83 (ofs) Time to Peak (Tp) = 746.00 (min) Time of Base (Tb) = 1552.59 (min) Volume = 1.08 (ac-ft) Time Step = 2.00 (min) Flow Multiplier = 1.00 [UNIT HYDROGRAPH INFORMATION] Number = 3 Type = SCS Curvilinear Peak Flow (Qp) = 91.85 (cfs) Time to Peak (Tp) = 23.02 (min) Time of Base (Tb) = 115.10 (min) Volume 3.89 (ac-ft) Shape Factor 484.00 Time Step: = 2.00 (min) Excess Rain = 1.00 (in) Lag Time = 20.72 (min) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] ------------------------------------------ Description Area CN ------------------------------------------ Overall Approximation 46.60 51 [TIME CONCENTRATION -- User Defined] 1 Time of Concentration (Tc) = 34.53 (min) I [RAINFALL DESCRIPTION] g Distribution Type = SCS II l Total Precipitation 3.70 (in) { Return Period 2 (yr) Storm Duration = 24.00 (hr) it CASCADIA SUBDIVISION Name: DA-Pond 2 Pre -Forested 10-Year (Cn=51) Type: Computed Flood [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 27.83 (cfs) Time to Peak (Tp) = 738.00 (min) Time of Base (Tb) = 1552.59 (min) Volume = 3.96 (ac-ft) 9 Time Step 2.00 (min) Flow Multiplier _ 1.00 [UNIT HYDROGRAPH INFORMATION] Number = 3 Type = SCS Curvilinear Peak Flow (Qp) = 91.85 (cfs) Time to Peak (Tp) = 23.02 (min) Time of Base (Tb) = 115.10 (min) Volume = 3.89 (ac-ft) Shape Factor = 484.00 Time Step: = 2.00 (min) Excess Rain = 1.00 (in) Lag Time = 20.72 (min) [BASIN INFORMATION] [WEIGHTED ------------------------------------------------------ WATERSHED AREA] Description Area CN ------------------------------------------------------ Overall Approximation 46.60 51 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) - 34.53 (min) [RAINFALL DESCRIPTION] Distribution Type = SCS II Total Precipitation = 5.60 (in) Return Period = 10 (yr) Storm Duration = 24.00 (hr) 12 ' . V. CASCADIA SUBDIVISION Name: DA-Pond 2 Post -Development 1-Year Type: Computed Flood [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 57.41 (cfs) Time to Peak (Tp) = 730.00 (min) i Time of Base (Tb) = 1526.16 (min) Volume = 5.31 (ac-ft) Time Step = 2.00 (min) f Flow Multiplier = 1.00 I [UNIT HYDROGRAPH INFORMATION] Number = 1 Type = SCS Curvilinear Peak Flow (Qp) = 118.80 (cfs) Time to Peak (Tp) = 17.91 (min) Time of Base (Tb) = 89.56 (min) Volume = 3.92 (ac-ft) Shape Factor = 484.00 Time Step: = 2.00 (min) Excess Rain = 1.00 (in) Lag Time = 16.12 (min) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] ------------------------------------------------------ Description Area CN --------------------------------- Overall Approximation 46.90 77 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 26.87 (min) [RAINFALL DESCRIPTION] Distribution Type SCS II Total Precipitation = 3.40 (in) Return Period = 1 (yr) Storm Duration = 24.00 (hr) 13 CASCADIA SUBDIVISION Name: DA-Pond 2 Post -Development 1.5-Year Type: Computed Flood [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 64.07 (cfs) Time to Peak (Tp) = 730.00 (min) Time of Base (Tb) = 1526.16 (min) Volume = 5.89 (ac-ft) Time Step = 2.00 (min) Flow Multiplier = 1.00 [UNIT HYDROGRAPH INFORMATION] Number = 1 Type = SCS Curvilinear Peak Flow (Qp) = 118.80 (cfs) Time to Peak (Tp) = 17.91 (min) Time of Base (Tb) = 89.56 (min) Volume = 3.92 (ac-ft) Shape Factor = 484.00 Time Step: = 2.00 (min) Excess Rain = 1.00 (in) Lag Time = 16.12 (min) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN ------------------------------------------------------ Overall Approximation 46.90 77 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) 26.87 (min) [RAINFALL DESCRIPTION] Distribution Type = SCS II Total Precipitation = 3.60 (in) Return Period = 1.5 (yr) Storm Duration = 24.00 (hr) 14 ( CASCADIA SUBDIVISION Name: DA-Pond 2 Post -Development 2-Year Type: Computed Flood [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 67.45 (efs) Time to Peak (Tp) = 730.00 (min) Time of Base (Tb) = 1526.16 (min) Volume = 6.19 (ac-ft) Time Step = 2.00 (min) Flow Multiplier = 1.00 [UNIT HYDROGRAPH INFORMATION] Number = 1 Type = SCS Curvilinear Peak Flow (Qp) = 118.80 (cfs) Time to Peak (Tp) = 17.91 (min) Time of Base (Tb) = 89.56 (min) Volume = 3.92 (ac-ft) Shape Factor = 484.00 Time Step: = 2.00 (min) Excess Rain = 1.00 (in) Lag Time = 16.12 (min) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] ------------------------------------------------------ Description Area ------------------------------------------------------ CN Overall Approximation 46.90 77 [TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 26.87 (min) [RAINFALL DESCRIPTION) Distribution Type = SCS II Total Precipitation = 3.70 (in) Return Period = 2 (yr) Storm Duration = 24.00 (hr) 15 i CASCADIA SUBDIVISION Name: DA-Pond 2 Post -Development 10-Year Type: Computed Flood [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 136.37 (cfs) Time to Peak (Tp) 728.00 (min) Time of Base (Tb) - 1526.16 (min) 1 Volume 12.27 (ac-ft) Time Step 2.00 (min) Flow Multiplier '+I = 1.00 [UNIT HYDROGRAPH INFORMATION] Number 1 Type SCS Curvilinear Peak Flow (Qp) = 118.80 (cfs) Time to Peak (Tp) 17.91 (min) Time of Base (Tb) _ 89.56 (min) Volume = 3.92 (ac-ft) Shape Factor = 484.00 i Time Step: = 2.00 (min) Excess Rain 1.00 (in) Lag Time 16.12 (min) [BASIN INFORMATION] ------------[WEIGHTED WATERSHED AREA] ---------------------------------- Description Area CN ------------------------------------------------------ Overall Approximation I 46.90 77 (TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 26.87 (min) [RAINFALL DESCRIPTION] j Distribution Type = SCS II Total Precipitation = 5.60 (in) Return Period = 10 (yr) Storm Duration = 24.00 (hr) EEO CASCADIA SUBDIVISION Name: DA-Pond 2 Post -Development 100-Year Type: Computed Flood [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 272.55 (ofs) Time to Peak (Tp) = 728.00 (min) Time of Base (Tb) = 1526.16 (min) Volume - 24.64 (ac-ft) Time Step = 2.00 (min) Flow Multiplier = 1.00 [UNIT HYDROGRAPH INFORMATION] Number = 1 Type = SCS Curvilinear Peak Flow (Qp) = 118.80 (c£s) Time to Peak (Tp) = 17.91 (min) Time of Base (Tb) = 89.56 (min) Volume = 3.92 (ac-ft) Shape Factor = 484.00 Time Step: = 2.00 (min) Excess Rain = 1.00 (in) Lag Time = 16.12 (min) [BASIN INFORMATION] [WEIGHTED WATERSHED AREA] Description Area CN --------- Overall Approximation 46.90 77 (TIME CONCENTRATION -- User Defined] Time of Concentration (Tc) = 26.87 (min) [RAINFALL DESCRIPTION] Distribution Type = SCS II Total Precipitation = 9.10 (in) Return Period = 100 (yr) Storm Duration = 24.00 (hr) 17 4 1 , 4 CASCADIA SUBDIVISION RESERVOIR REPORT Name: Pond 2 (Retention Basin w/Aquatic Bench) ( WATER QUALITY VOLUME REPORT ) Name: Pond 2 - Storage [RATING CURVE LIMIT] Minimum Elevation = Maximum Elevation = Elevation Increment = [STAGE STORAGE INFORMATION] Storage Method: User -Defined Storage Input Method: Area Number Elevation Area Ave Area Volume 345.00 (ft) 358.00 (ft) 0.20 (ft) Volume Cumulative (ft) (sq ft) (sq ft) (cu ft) (cu ft) 1 344.99 0.00 0.00 0.00 0.00 2 345.00 28234.00 14117.00 141.17 141.17 3 346.00 30604.00 29419.00 29419.00 29560.17 4 348.00 35380.00 32992.00 65984.00 95544.17 5 348.50 39242.00 37311.00 18655.50 114199.67 6 350.00 50655.00 44948.50 67422.75 181622.42 7 352.00 56835.00 53745.00 107490.00 289112.42 8 354.00 60195.00 58515.00 117030.00 406142.42 9 356.00 64854.00 62524.50 125049.00 531191.42 10 358.00 69602.00 67228.00 134456.00 665647.42 11 358.33 76850.00 73226.00 24164.58 689812.00 Quality Volume Required - 4X(WQ Volume) For 65% Removal Efficiency WQ Volume = (1/21n)/12 X impervious area (Sq. Ft.) (4)(1/2in)/12 X 451,761 Sq. Ft. + 408,897 Sq Ft.(Proposed Blocks 1-3) = 143,443 Cu. Ft. Provided Water Quality Volume (Elev.=351) = 181,622.42 cu. Ft. Pool Depth Zones: Depth Zone Elevation Surface Area Percentage of Wet Storage Area 0' - 1.51 350.00 - 348.50 11,413 of. 22.5% 1.5' - 2' 348.50 - 348.00 3,862 of. 7.6% 2' - 6' 348.00 - 345.00 35,380 of. 69.9% (Please Refer to approved Stormwater Management plan for Cascadia Blocks 4-7 for additional pool depth zone calculations) 18 . , k CASCADIA SUBDIVISION RESERVOIR REPORT Reservoir Number: 2 Name: Pond 2 [RATING CURVE LIMIT] Minimum Elevation Maximum Elevation Elevation Increment [STAGE STORAGE INFORMATION] Storage Method: User -Defined Storage Input Method: Area Number Elevation Area Ave Area Volume 344.50 (ft) 358.33 (ft) 0.20 (ft) Volume Cumulative (ft) (sq ft) =-=-=--0.00 (sq ft) (cu ft) (cu ft) -----=---349.99-------0.00 1 D 00 --------0.00------------ 2 350.00 50655.00 25327.50 253.27 253.27 3 352.00 56835.00 53745.00 107490.00 107743.27 4 354.00 60195.00 58515.00 117030.00 224773.27 5 356.00 64854.00 62524.50 125049.00 349822.27 6 358.00 69602.00 67228.00 134456.00 484278.27 7 358.33 11427.00 70514.50 23269.78 507548.06 [RESERVOIR STAGE STORAGE/DISCHARGE] Elevation -------------------------------------------------- Stage Area Storage -------------- Discharge (ft) (£t) --------------- (sq ft) (cu ft) (cfs) ------------------------------------------------------------------------------- 349.90 5.40 0.00 0.00 0.00 350.10 5.60 50964.00 5096.40 0.02 350.30 5.80 51582.00 15351.00 0.10 350.50 6.00 52200.00 25729.20 0.14 350.70 6.20 52818.00 36231.00 0.18 350.90 6.40 53436.00 46856.40 0.21 351.10 6.60 54054.00 57605.40 0.23 351.30 6.80 54672.00 68478.00 0.26 351.50 7.00 55290.00 79474.20 0.28 351.70 7.20 55908.00 90594.00 0.30 351.90 7.40 56526.00 101837.40 0.31 352.10 7.60 57003.00 113190.30 0.33 352.30 7.80 57339.00 124624.50 0.35 352.50 8.00 57675.00 136125.90 0.36 352.70 8.20 58011.00 147694.50 0.38 352.90 8.40 58347.00 159330.30 0.39 353.10 8.60 58683.00 171033.30 0.41 353.30 8.80 59019.D0 182803.50 0.42 353.50 9.00 59355.00 194640.90 0.43 353.70 9.20 59691.00 206545.50 0.45 353.90 9.40 60027.00 218517.30 0.46 354.10 9.60 60427.95 230562.79 0.47 354.30 9.80 60893.85 242694.97 0.48 354.50 10.00 61359.75 254920.33 0.55 19 CASCADIA SUBDIVISION 354.70 10.20 61825.65 267238.87 0.96 354.90 10.40 62291.55 279650.59 1.46 355.10 10.60 62757.45 292155.49 1.79 355.30 10.80 63223.35 304753.57 2.06 355.50 11.00 63689.25 317444.83 2.29 355.70 11.20 64155.15 330229.27 2.49 355.90 11.40 64621.05 343106.89 7.36 356.10 11.60 65091.40 356078.14 16.09 356.30 11.80 65566.20 369143.90 32.33 356.50 12.00 66041.00 382304.62 55.40 356.70 12.20 66515.80 395560.30 84.03 356.90 12.40 66990.60 40B910.94 117.83 357.10 12.60 67465.40 422356.54 142.00 357.30 12.80 67940.20 435897.10 167.11 357.50 13.00 68415.00 449532.62 195.83 357.70 13.20 68889.80 463263.10 228.22 357.90 13.40 69364.60 477088.54 264.35 358.10 13.60 70155.03 491040.50 304.30 358.30 13.80 71261.09 505182.12 348.14 Maximum Storage = 507322.44 (cu ft) Maximum Discharge 355.06 (cfs) 20 CASCADIA SUBDIVISION Structure Number Type Name [RATING CURVE LIMIT] Minimum Elevation Maximum Elevation Elevation Increment (STAND PIPE INFORMATION] [ORIFICE INFORMATION] OUTLET STRUCTURE REPORT 1 Stand Pipe STAND PIPE = 344.50 (ft) 356.33 (ft) 0.20 (ft) Diameter = 5.00 Crest Length = 15.71 Effective Crest Length = 15.71 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 = 355.70 Weir Coefficient = 3.33 Exponential = 1.50 [WEIR EQUATION] Q = Cw * L * H^exp (ft) (ft) (ft) (ft) [DEFINITIONS] Cw = Weir Coefficient H = Headwater depth above inlet control section invert ft L = Crest lenght ft [OPTIONAL ORIFICE INFORMATION] ----------------------------------------------------------------------- ---.. Type : Circular Orifice [OPTIONAL ORIFICE INFORMATION] Diameter = 0.25 (ft) Invert Elevation = 350.00 (ft) Orifice Coefficient = 0.60 Number of Openings = 1 [ORIFICE EQUATION] Q — Co*A((2gh)/k)^0.5 2] A CASCADIA SUBDIVISION [DEFINITIONS] Co - Orifice Coefficient A = Wetted Area, (cfs) k = 1 Structure Number : 2 Type : Circular Orifice [OPTIONAL ORIFICE INFORMATION] Diameter = 0.50 (ft) Invert Elevation = 354.40 (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 = 30.00 (in) Invert Elevation = 346.00 (ft) Pipe Length = 75.00 (ft) Slope = 0.02 Manning's n Value = 0.01 Orifice Coefficient = 0.60 Tailwater Elevation = 344.58 (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 = 27.16 [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 = 31.05 [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) 22 . f, CASCADIA SUBDIVISION [STAND PIPE STAGE VS. DISCHARGE] Elevation Stage Weirs Orifices Stand Pipe Culvert Total (ft) (ft) (cfs) (cfs) (cfs) (cfs) (cfs) 349.90 5.40 0.00 0.00 0.00 36.88 0.00 350.10 5.60 0.00 0.02 0.00 38.48 0.02 350.30 5.80 0.00 0.10 0.00 40.03 0.10 350.50 6.00 0.00 0.14 0.00 41.51 0.14 350.70 6.20 0.00 0.18 0.00 42.95 0.18 350.90 6.40 0.00 0.21 0.00 44.33 0.21 351.10 6.60 0.00 0.23 0.00 45.68 0.23 351.30 6.80 0.00 0.26 0.00 46.98 0.26 351.50 7.00 0.00 0.28 0.00 48.26 0.28 351.70 7.20 0.00 0.30 0.00 49.50 0.30 351.90 7.40 0.00 0.31 0.00 50.70 0.31 352.10 7.60 0.00 0.33 0.00 51.88 0.33 352.30 7.80 0.00 0.35 0.00 53.04 0.35 352.50 8.00 0.00 0.36 0.00 54.17 0.36 352.70 8.20 0.00 0.38 0.00 55.27 0.38 352.90 8.40 0.00 0.39 0.00 56.36 0.39 353.10 8.60 0.00 0.41 0.00 57.42 0.41 353.30 8.80 0.00 0.42 0.00 58.47 0.42 353.50 9.00 0.00 0.43 0.00 59.49 0.43 353.70 9.20 0.00 0.45 0.00 60.50 0.45 353.90 9.40 0.00 0.46 0.00 61.50 0.46 354.10 9.60 0.00 0.47 0.00 62.47 0.47 354.30 9.80 0.00 0.48 0.00 63.43 0.48 354.50 10.00 0.00 0.55 0.00 64.38 0.55 354.70 10.20 0.21 0.96 0.00 65.31 0.96 354.90 10.40 1.09 1.46 0.00 66.24 1.46 355.10 10.60 2.35 1.79 0.00 67.14 1.79 355.30 10.80 3.90 2.06 0.00 68.04 2.06 355.50 11.00 5.69 2.29 0.00 68.92 2.29 355.70 11.20 7.68 2.49 0.00 69.80 2.49 355.90 11.40 9.87 2.68 4.68 70.66 7.36 356.10 11.60 12.24 2.85 13.23 71.51 16.09 356.30 11.80 14.76 3.01 24.31 72.35 27.33 356.50 12.00 17.44 3.17 37.43 73.18 40.60 356.70 12.20 20.27 3.31 52.31 74.01 55.62 356.90 12.40 23.23 3.45 68.76 74.82 72.21 357.10 12.60 26.33 3.58 86.65 75.62 75.62 357.30 12.80 29.55 3.71 101.22 76.42 76.42 357.50 13.00 32.89 3.83 114.58 77.21 77.21 357.70 13.20 36.35 3.95 127.94 77.99 77.99 357.90 13.40 39.93 4.07 140.17 78.76 78.76 358.10 13.60 41.75 4.18 146.40 79.53 79.53 358.30 13.80 0.00 4.29 152.38 80.28 80.28 358.33 13.83 0.00 4.30 153.26 80.40 80.40 23 CASCADIA SUBDIVISION OUTLET STRUCTURE REPORT Type : Trapezoidal Weir Name : Weir [RATING CURVE LIMIT] Minimum Elevation = 356.00 (ft) Maximum Elevation = 358.33 (ft) Elevation Increment = 0.10 (ft) [OUTLET STRUCTURE INFORMATION] Crest Length = 16.00 (ft) Angle of Walls = 157.0000 Crest Elevation = 356.10 (ft) Weir Coefficient = 3.33 Exponential = 1.50 [TRAPEZOIDAL EQUATION] Q = Cw * ( L + 0.8H * tan ( ang/2.0 ) ) * H^exp [DEFINITIONS] Cw, = Weir Coefficient H = Headwater depth above inlet control section invert L = Crest lenght ang = Angle of the walls [MAXIMUM DISCHARGE] Q = 274.67 (cfs) [WEIR STAGE VS. DISCHARGE] Elevation (ft) Stage (ft) Discharge (cis) 356.10 0.10 0.00 356.20 0.20 1.73 356.30 0.30 5.00 356.40 0.40 9.40 356.50 0.50 14.80 356.60 0.60 21.15 356.70 0.70 28.41 356.80 0.80 36.57 356.90 0.90 45.62 357.00 1.00 55.55 357.10 1.10 66.37 357.20 1.20 78.09 357.30 1.30 90.69 357.40 1.40 104.20 357.50 1.50 118.62 357.60 1.60 133.96 357.70 1.70 150.23 357.80 1.80 167.44 357.90 1.90 185.59 358.00 2.00 204.69 358.10 2.10 224.77 358.20 2.20 245.82 358.30 2.30 267.86 358.33 2.33 274.67 24 << . CASCADIA SUBDIVISION j Name: Routing - Pond 2 1-Year 1 Type: Reservoir: Modified Puls [HYDROGRAPH INFORMATION] Peak Flow (Qp) - 0.45 (cfa) Time to Peak (Tp) = 1464.00 (min) Time of Base (Tb) = 2880.00 (min) Volume = 1.27 (ac-ft) Time Step = 2.00 (min) Peak Elevation = 353.80 (ft) Detention Time = NA [RESERVOIR STRUCTURE INFORMATION] Number = 2 Name = Pond 2 Storage Type = User -Defined Area Maximum Storage = 507322.44 (cu ft) Maximum Discharge = 355.06 (cfs) [INFLOW HYDROGRAPH INFORMATION] Number = 21 Name = Pond 2 Post 1-Year Peak Flow (Qp) = 57.41 (cfs) Time to Peak (Tp) = 730.00 (min) Time of Base (Tb) = 1526.16 (min) Volume = 5.31 (ac-ft) Flow Multiplier = 1.00 25 ► f T CASCADIA SUBDIVISION Name: Type: J (HYDROGRAPH INFORMATION] Peak Flow (Qp) Time to Peak (Tp) Time of Base (Tb) Volume Time Step Peak Elevation Detention Time Routing - Pond 2 1.5-Year Reservoir: Modified Puls [RESERVOIR STRUCTURE INFORMATION] Number Name Storage Type Maximum Storage Maximum Discharge [INFLOW HYDROGRAPH INFORMATION] Number Name Peak Flow (Qp) Time to Peak (Tp) Time of Base (Tb) Volume Flow Multiplier = 0.48 (ofs) = 1464.00 (min) 2880.00 (min) 1.34 (ac-ft) 2.00 (min) 354.20 (ft) NA 2 = Pond 2 User -Defined Area = 507322.44 (cu ft) 355.06 (cfs) = 4 = Pond 2 Post 1.5-Year 64.07 (cfs) = 730.00 (min) 1526.16 (min) = 5.89 (ac-ft) = 1.00 0 r CASCADIA SUBDIVISION Name: Routing - Pond 2 2-Year Type: Reservoir: Modified Puls [HYDROGRAPH INFORMATION] Peak Flow (Qp) = 0.52 (cfs) Time to Peak (Tp) = 1462.00 (min) Time of Base (Tb) = 2680.00 (min) Volume = 1.39 (ac-ft) Time Step = 2.00 (min) Peak Elevation = 354.40 (ft) Detention Time = NA [RESERVOIR STRUCTURE INFORMATIONS Number = 2 Name = Pond 2 Storage Type = User -Defined Area Maximum Storage = 507322.44 (cu ft) Maximum Discharge = 355.06 (cfs) [INFLOW HYDROGRAPH INFORMATION] Number = 5 Name = Pond 2 Post 2-Year Peak Flow (Qp) = 67.45 (cfs) Time to Peak (Tp) = 730.00 (min) Time of Base (Tb) = 1526.16 (min) Volume = 6.19 (ac-ft) Flow Multiplier = 1.00 27 M r t a CASCADIA SUBDIVISION Name: Type: [HYDROGRAPH INFORMATION] Peak Flow (Qp) Time to Peak (Tp) Time of Base (Tb) Volume Time Step Peak Elevation Detention Time Routing - Pond 2 10-Year Reservoir: Modified Puls [RESERVOIR STRUCTURE INFORMATION] 8.83 (cfe) 836.00 (min) 2880.00 (min) 6.79 (ac-ft) 2.00 (min) 355.96 (ft) NA Number = 2 Name = Pond 2 Storage Type = User -Defined Area Maximum Storage = 507322.44 (cu ft) Maximum Discharge = 355.06 (cfs) [INFLOW HYDROGRAPH INFORMATION] Number = 6 Name = Pond 2 Post 10-Year Peak Flow (Qp) = 136.37 (cfs) Time to Peak (Tp) = 728.00 (min) Time of Base (Tb) = 1526.16 (min) Volume = 12.27 (ac-ft) Flow Multiplier = 1.00 28 CASCADIA SUBDIVISION Name: Routing - Pond 2 100-Year Type: Reservoir: Modified Puls [HYDROGRAPH INFORMATION] - Peak Flow (Qp) 168.64 (cfs) Time to Peak (Tp) 742.00 (min) Time of Base (Tb) 2880.00 (min) Volume 19.15 (ac-ft) Time Step 2.00 (min) Peak Elevation 357.31 (ft) Detention Time NA [RESERVOIR STRUCTURE INFORMATION] Number = 2 Name = Pond 2 Storage Type = User -Defined Area Maximum Storage = 507322.44 (cu ft) Maximum Discharge = 355.06 (cfs) [INFLOW HYDROGRAPH INFORMATION] Number = 7 Name = Pond 2 Post 100-Year Peak Flow (Qp) = 272.55 (cfs) Time to Peak (Tp) = 728.00 (min) Time of Base (Tb) = 1526.16 (min) Volume = 24.64 (ac-ft) Flow Multiplier = 1.00 FM 33 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Wednesday, 02 / 17 / 2021 Hyd. No. 1 S W M-2 Inflow Hydrograph type = SCS Runoff Peak discharge = 60.26 cfs Storm frequency = 1 yrs Time to peak = 12.17 hrs Time interval = 2 min Hyd. volume = 227,359 cuft Drainage area = 46.900 ac Curve number = 77 Basin Slope = 0.0% Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 26.90 min Total precip. = 3.40 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 SWM-2 Inflow Q (ds) Hyd. No. 1 -- 3 Year Q (cfs) 70.00 70.00 60.00 60.00 50.00 50.00 40.00 40.00 30.00 30.00 20.00 20.00 10.00 10.00 0.00 000 0 2 4 6 8 10 12 14 16 18 20 22 24 26 Hyd No. 1 Time (hrs) 34 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Wednesday, 02 11712021 Hyd. No. 1 SW M-2 Inflow Hydrograph type = SCS Runoff Peak discharge = 67.21 cfs Storm frequency = 1.5 yrs Time to peak = 12.17 hrs Time interval = 2 min Hyd. volume = 252,253 cuft Drainage area = 46.900 ac Curve number = 77 Basin Slope = 0.0% Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 26.90 min Total precip. = 3.60 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 SWM-2 Inflow Q (Cfs) Hyd. No. 1 -- 1 Year Q (Cfs) 70.00 70.00 60.00 60.00 50.00 50.00 40.00 40.00 30.00 30.00 20.00 20.00 10.00 10.00 000 000 0 2 4 6 8 10 12 14 16 18 20 22 24 26 — Hyd No. 1 Time (hrs) 35 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil MOD 2019 by Autodesk, Inc. v2020 Wednesday, 02 11712021 Hyd. No. 1 SWM-2 Inflow Hydrograph type = SCS Runoff Peak discharge = 70.73 cfs Storm frequency = 2 yrs Time to peak = 12.17 hrs Time interval = 2 min Hyd. volume = 264,912 cuft Drainage area = 46.900 ac Curve number = 77 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 26.90 min Total precip. = 3.70 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 SWM-2 Inflow Q (cfS) Hyd. No. 1 -- 2 Year Q (cfs) 80.00 80.00 70.00 70.00 60.00 60.00 50.00 50.00 40.00 40.00 30.00 30.00 20.00 20.00 10.00 10.00 0.00 000 0 2 4 6 8 10 12 14 16 18 20 22 24 26 Hyd No. 1 Time (hrs) - 36 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3082019 by Autodesk, Inc. v2020 Wednesday, 02117 12021 Hyd. No. 1 S W M-2 Inflow Hydrograph type = SCS Runoff Peak discharge = 143.02 cfs Storm frequency = 10 yrs Time to peak = 12.13 hrs Time interval = 2 min Hyd. volume = 524,935 cuft Drainage area = 46.900 ac Curve number = 77 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 26.90 min Total precip. = 5.60 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 SWM-2 Inflow Q (cfs) Hyd. No. 1 -- 10 Year Q (cfs) 160.00 160.00 140.00 140.00 120.00 120.00 100.00 100.00 80.00 80.00 60.00 60.00 40.00 40.00 20.00 20.00 000 000 0 2 4 6 8 10 12 14 16 18 20 22 24 26 Hyd No. 1 Time (hrs) 37 Hydrograph Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Wednesday, 02 / 17 / 2021 Hyd. No. 1 SWM-2 Inflow Hydrograph type = SCS Runoff Peak discharge = 285.07 cfs Storm frequency = 100 yrs Time to peak = 12.13 hrs Time interval = 2 min Hyd. volume = 1,054,480 cuft Drainage area = 46.900 ac Curve number = 77 Basin Slope = 0.0 % Hydraulic length = 0 ft Tc method = User Time of conc. (Tc) = 26.90 min Total precip. = 9.10 in Distribution = Type II Storm duration = 24 hrs Shape factor = 484 Q (cfs 320.00 M IrI1Ia 240.00 PilIrIrIel 160.00 120.00 40.00 SWM-2 Inflow Hyd. No. 1 -- 100 Year Q (cfs) 320.00 240.00 200.00 160.00 `KIMI 40.00 0.00 1 1 0.00 0 2 4 6 8 10 12 14 16 18 20 22 24 26 — Hyd No. 1 Time (hrs) Hydrograph Report 38 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Wednesday, 0211712021 Hyd. No. 3 SWM-2 Routed Hydrograph type = Reservoir Peak discharge = 0.470 cfs Storm frequency = 1 yrs Time to peak = 24.37 hrs Time interval = 2 min Hyd. volume = 123,533 cuft Inflow hyd. No. = 1 - SWM-2 Inflow Max. Elevation = 353.67 ft Reservoir name = Pond #2 Adjusted Max. Storage = 207,912 cuft Storage Indication method used SWM-2 Routed Q (cfs) Hyd. No. 3 -- 3 Year Q (Cfs 70.00 70.00 60.00 60.00 50.00 50.00 40.00 40.00 30.00 30.00 20.00 20.00 10.00 - - - - 10.00 0.00 000 0 10 20 30 40 50 60 70 SO 90 100 Time (hrs) — Hyd No. 3 —Hyd No. 1 Total storage used = 207,912 tuft Hydrograph Report 39 Hydraflow Hydrographs Extension for Aulodesk® Civil 3D®2019 by Autodesk, Inc. v2020 Wednesday. 02 / 17 / 2021 Hyd. No. 3 SWM-2 Routed Hydrograph type = Reservoir Peak discharge = 0.520 cfs Storm frequency = 1.5 yrs Time to peak = 24.33 hrs Time interval = 2 min Hyd. volume = 131,454 cuft Inflow hyd. No. = 1 - SWM-2 Inflow Max. Elevation = 354.09 ft Reservoir name = Pond #2 Adjusted Max. Storage = 231,561 cuft Storage Indication method used SWM-2 Routed Q (Cfs) Hyd. No. 3 -- 1 Year Q (Cfs 70.00 70.00 60.00 60.00 50.00 50.00 40.00 40.00 30.00 30.00 20.00 20.00 10.00 10.00 0.00 0 00 0 10 20 30 40 50 60 70 SO 90 100 Time (hrs) — Hyd No. 3 —Hyd No. 1 Total storage used = 231,561 cult Hydrograph Report X10 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Wednesday, 02 / 17 / 2021 Hyd. No. 3 SWM-2 Routed Hydrograph type = Reservoir Peak discharge = 0.598 cfs Storm frequency = 2 yrs Time to peak = 24.33 hrs Time interval = 2 min Hyd. volume = 136,518 cuft Inflow hyd. No. = 1 - SWM-2 Inflow Max. Elevation = 354.29 ft Reservoir name = Pond #2 Adjusted Max. Storage = 243,023 cuft Storage Indication method used. SWM-2 Routed Q (Cfs) Hyd. No. 3 — 2 Year Q (Cfs 80.00 80.00 70.00 70.00 60.00 60.00 50.00 50.00 40.00 40.00 30.00 30.00 20.00 20.00 10.00 10.00 0.00 000 0 10 20 30 40 50 60 70 80 90 100 Time (hrs) — Hyd No. 3 —Hyd No. 1 Total storage used = 243,023 cult Hydrograph Report 41 Hydraflow Hydrographs Extension for Autodesk® Civil 3DV 2019 by Autodesk, Inc. v2020 Wednesday, 0211712021 Hyd. No. 3 SWM-2 Routed Hydrograph type = Reservoir Peak discharge = 8.913 cfs Storm frequency = 10 yrs Time to peak = 14.07 hrs Time interval = 2 min Hyd. volume = 370,867 cuft Inflow hyd. No. = 1 - SWM-2 Inflow Max. Elevation = 356.03 ft Reservoir name = Pond #2 Adjusted Max. Storage = 347,487 cuft Storage Indication method used Q (cfs) 160.00 140.00 120.00 100.00 80.00 60.00 40.00 20.00 0.00 0 10 Hyd No. 3 SWM-2 Routed Hyd. No. 3 — 10 Year EMMO M�l 20 30 40 50 60 70 80 90 — Hyd No. 1 Total storage used = 347,487 cuft 100VVV Time (hrs) Hydrograph Report 42 Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Hyd. No. 3 SWM-2 Routed Hydrograph type = Reservoir Peak discharge Storm frequency = 100 yrs Time to peak Time interval = 2 min Hyd. volume Inflow hyd. No. = 1 - SWM-2 Inflow Max. Elevation Reservoir name = Pond #2 Adjusted Max. Storage Storage Indication method used Q (cis 320.00 280.00 240.00 200.00 160.00 120.00 40.00 SWM-2 Routed Hyd. No. 3 — 100 Year Wednesday, 02117 / 2021 = 227.44 cfs = 12.27 hrs = 898,514 cuft = 357.00 ft = 408,647 cuft Q (cfs) 320.00 280.00 240.00 200.00 160.00 120.00 80.00 40.00 0.00 0.00 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 Time (hrs) — Hyd No. 3 —Hyd No. 1 Total storage used = 408,647 cult Pond Report 43 Hydra6ow Hydrographs Extension for Autodesk® Civil 3DO 2019 by Autodesk, Inc. v2020 Wednesday, 02! 1712021 Pond No. 3 - Pond #2 Adjusted Pond Data Contours -User-defined contour areas. Average end area method used for volume calculation. Begining Elevation = 349.60 ft Stage / Storage Table Stage (ft) Elevation (ft) Contour area (sgft) Incr. Storage (tuft) Total storage (tuft) 0.00 349.60 42,257 0 0 0.40 350.00 46.756 17,803 17,803 1.40 351.00 49,247 48,002 65,804 2.40 352.00 52,144 50,696 116,500 3.40 353.00 55,072 53,608 170,108 4.40 354.00 57,337 56,205 226,312 5.40 355.00 59,608 58,473 284,785 6.40 356.00 61,928 60,768 345,553 7.40 357.00 64,230 63,079 408,632 8.40 368.00 66.617 65,424 474,055 Culvert / Orifice Structures [A] [B] [C] [PrfRsr] Rise (in) = 30.00 3.00 Inactive Inactive Span (in) = 30.00 3.00 0.00 0.00 No. Barrels = 1 1 1 1 Invert El. (ft) = 346.57 349.60 0.00 0.00 Length (ft) = 66.00 0.00 0.00 0.00 Slope (%) = 2.83 0.00 0.00 n/a N-Value = .013 .013 .013 n/a Orifice Coeff. = 0.60 0.60 0.60 0.60 Multi -Stage = n/a Yes Yes Yes Stage (ft) 10.00 8.00 6.00 - 4.00 - 2.00 - 000- weir structures [A] [B] [C] [D] Crest Len (ft) = 15.71 0.00 48.00 0.00 Crest El. (ft) = 355.90 353.80 356.00 0.00 Weir Coeff. = 3.33 0.56 3.33 3.33 Weir Type = Rect 25 degV Ciplti - Multi -Stage = Yes Yes No No Exfil.(in/hr) = 0.000 (by Contour) TW Elev. (ft) = 0.00 Nole:Culvert/Orifice curfews are analyzed under inlet Cie) and mtlet fact control. Weir risers checked for orifice conditions(ic) and mbmergence(a). Stage / Discharge Elev (ft) 359.60 357.60 355.60 353.60 351.60 34960 0.0 50.0 100.0 150.0 200.0 250.0 300.0 350.0 400.0 450.0 500.0 550.0 Total Q Discharge (cfs)