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Home My WebLink About20060796 Ver 2_13052-BMP Packet 10-31-14_20141104 BMP DRY DETENTION POND DESIGNCALCULATIONS WATERFORD ON THE ROCKY RIVER – PH 4 Kannapolis, Cabarrus County, North Carolina Prepared for: Lennar Carolinas, LLC 11230 Carmel Commons Blvd. Charlotte, NC 28226 Prepared by: DPR Associates, Inc. 420 Hawthorne Lane Charlotte, NC 28204 P. 704-332-1204 F. 704-332-1210 www.dprassociates.net DPR Project No.: 13052 May 23, 2014 Rev. October 8, 2014 10-08-2014 _____________________ _____________________ DPR Associates, Inc. David D. Sherrill, PE WATERFORD ON THE ROCKY RIVER – PH 4 TABLE OF CONTENTS I. BMP/ DRY DETENTION POND DESIGN SUMMARY II. BMP EXHIBITS AND CALCULATIONS - Vicinity Map - Aerial Photo - Pre-Development Drainage and TOC Map - Post-Development Drainage Map - Soils Maps – Overall Site - Impervious Area Calculations - Run-Off Curve Number III. BMP DRY DETENTION POND DESIGN AND CALCULATIONS - Water Quality Volume - Pond Volume & Surface - Orifice Sizing & Dewatering Calcs - Bouyance Weight of Anchor Calcs IV. BMP HYDROGRAGH ANALYSIS - Hydrograph Summary Report - Hydrograph Pond Report - Hydrograph Report V. BMP APPENDIX - USGS Map - Post-Construction Storm Water Ordinance Map - Run-Off Curve Number Chart I. BMP/DPDS ETENTION ONDESIGN UMMARY Waterford on the Rocky River – Ph. 4 Subdivision BMP DRY POND DESIGN SUMMARY DPR Project No. 13052 October 20, 2014 The enclosed calculation package is to show the results of the BMP design for the proposed Waterford, Phase 4 development. This development is located in Kannapolis (Cabarrus County), North Carolina, off of Jim Johnson Road just north of NC Highway 73. The subject site is approximately 35.6 acres and the existing conditions consist of rolling topography of woods and grass lands that drain towards Rocky River. There is an existing buffer along the river designated as River Stream Overlay District that varies from 25’ to 65’ from top of bank and shall be undisturbed. The site will be developed as a single family subdivision. Phase 4 is part of the previous approved 2006 overall plan of approximate 160 ac. No stormwater management plan was required at the time. The overall build-upon-area (BUA) is less than 24%. The intent of the proposed storm water BMP design for Phase 4 was to provide a TSS removal to a practical extent. The 2 BMP dry detention ponds were proposed to handle the First-Inch rainfall volume of the drainage area on the east side of the project and designed per standards in the NCDENR BMP manual. Additional measures such as grass swales feeding into the BMP ponds and the concrete level spreaders were proposed. The existing vegetative buffer within the River Stream Overlay District zone was to remain undisturbed to provide extra water quality treatment and to function as a filter to further remove pollutants. Two BMP facilities are proposed for the site. BMP – Dry Pond #1 drainage area is approximately 2.5 ac., BMP – Dry Pond #2 drainage area is approximately 16.5 ac. These BMP facilities are designed to treat and control the 1-Inch of runoff volume. The watershed basins st and hydraulic path feeding into the conveyance system were delineated using survey topo and existing conditions. With this information, hydraulic lengths, time of concentrations (TOC), and basin slopes were determined. ToC of 5 min. was used for all post-developed conditions. The composite curve numbers (CN) were calculated based on the hydrologic soil types and groups from the U.S. Department of Agriculture, SCS Cabarrus County for the pre-developed and post- developed conditions. The total impervious areas of the development were also calculated. The water quality volume of the 1 st –Inch of rainfall was quantified using the Schueler simple method. Hydraflow Hydrograph models were developed to determine the peak flows and peak times for the 1-inch, 6-hour storm event using SCS Unit Hydrograph for the 6-hour storm distribution and the Kannapolis rainfall intensity in inches per hour. The 10-yr and larger storm events were analyzed, though no peak discharge controls were proposed for these larger storm events. Each BMP pond was sized to contain the runoff volume for the 1 inch of rainfall of a 6- st hour storm. A hybrid form of level spreader was implemented along the top of dam to alleviate overflow for storm events with volumes greater than the 1 st inch. The enclosed calculation package will highlight the results of the stormwater plan for the proposed residential development. Detailed maps, calculations, results and details are included. Please see the enclosed Construction Documents and details for additional information. The estimated pollutant removal calculation (for TSS) is on the following page. T:\PROJECTS\2013 PROJECTS\13052\CALCS\BMP\13052-BMP Narrative.doc With the combined use of dry detention ponds, grass swales, level spreader outfalls and a 30’ min. riparian buffer, based on the formula for BMP’s in series in chapter 3 of the NCDENR Stormwater Management manual, the expected final TSS removal at each BMP is 88% (see below). T:\PROJECTS\2013 PROJECTS\13052\CALCS\BMP\13052-BMP Narrative.doc II. BMPEC XHIBITS AND ALCULATIONS Waterford Ph. 4DPR ASSOCIATESPrepared by : DDS DPR Job #: 13052Time of ConcentrationChecked by: HVN Location: Kannapolis, NC(Pre-Developed)Date: 3-28-14 Rev.: 10-8-14 Time of Concentration Calculation BMP #1 Sheet Flow grass Surface Description (table 3-1) n , Manning's roughness coeff.0.24 L , Flow Length (L<= 300 ft)150(ft.) (CMSWDM # 2.6.5.2) P , Two-yr 24-hr rainfall3.48(in.) 2 Elevation (upper) =670 Elevation (lower) =657 s , Land Slope (%) 0.087(ft./ft.) 0.40.2 VSL , Velocity = 0.22()()0.2253(ft./sec.) 0.80.50.4 TnLPS10.53 Time of Concentration, = 0.42() / =(min.) (CMSWDM # 2.6.5.3) T2 Shallow Concentrated Flow unpaved Surface Description (paved/unpaved) L, Flow Length375.0(ft.) (CMSWDM # 2.6.5.4) Elevation (upper) =657 Elevation (lower) =639 s, Watercourse slope0.048(ft./ft.) c , Manning's surface coeff. 16.13(ft/sec.) 0.5 c V, Average velocity = (S) 3.53(ft/sec.) Time of Concentration, = L / (60 x V) = 1.77 T(min.) (CMSWDM # 2.6.5.3) t Channel Flow: Wetted Perimeter =15.00Bottom Width (ft) =2.4 Hydraulic Radius =1.1Side Slope (X:1) = 3.0 Manning's Coefficient (n) =0.048Depth (ft) =2.0 Elevation (upper) =641Flow Length (ft) =4 Elevation (lower) =640.1Channel Area (sf) =16.7 Channel Slope (%) =0.225 Velocity (fps) =1.58 (CMSWDM # 2.6.5.5) 0.04 T(t) (min.) =(min.) Time =12 (min.) Total Time of Concentration, T =12.30 (min.) C Hydraulic Length = 529 Basin Slope = 0.060 T:\PROJECTS\2013 PROJECTS\13052\CALCS\BMP\13052-TOC-Pre-Devl.xls Sheet: 1 of 1 Waterford Ph. 4DPR ASSOCIATESPrepared by: DDS DPR Job #: 13052Time of ConcentrationChecked by: HVN Location: Kannapolis, NC(Pre-Developed)Date: 3-7-2014 Rev.: 10-8-14 Time of Concentration Calculation BMP #2 Sheet Flow grass Surface Description (table 3-1) n , Manning's roughness coeff.0.24 L , Flow Length (L<= 300 ft)200(ft.) (CMSWDM # 2.6.5.2) P , Two-yr 24-hr rainfall3.48(in.) 2 Elevation (upper) =711 Elevation (lower) =701 s , Land Slope (%) 0.050(ft./ft.) 0.40.2 VSL , Velocity = 0.22()()0.1915(ft./sec.) 0.80.50.4 TnLPS16.51 Time of Concentration, = 0.42() / =(min.) (CMSWDM # 2.6.5.3) T2 Shallow Concentrated Flow unpaved Surface Description (paved/unpaved) L, Flow Length1000.0(ft.) (CMSWDM # 2.6.5.4) Elevation (upper) =701 Elevation (lower) =663 s, Watercourse slope0.038(ft./ft.) c , Manning's surface coeff. 16.13(ft/sec.) 0.5 c V, Average velocity = (S) 3.15(ft/sec.) Time of Concentration, = L / (60 x V) = 5.30 T(min.) (CMSWDM # 2.6.5.3) t Channel Flow: Wetted Perimeter =34.14Bottom Width (ft) =12.0 Hydraulic Radius =2.3Side Slope (X:1) = 3.0 Manning's Coefficient (n) =0.048Depth (ft) =3.5 Elevation (upper) =663Flow Length (ft) =400 Elevation (lower) =641Channel Area (sf) =78.8 Channel Slope (%) =0.055 Velocity (fps) =1.27 (CMSWDM # 2.6.5.5) 5.25 T(t) (min.) =(min.) Time =22 (min.) Total Time of Concentration, T =21.81 (min.) C Hydraulic Length = 1,600 Basin Slope = 0.044 T:\PROJECTS\2013 PROJECTS\13052\CALCS\BMP\13052-TOC-Pre-Devl.xls Sheet: 1 of 1 Project: Waterfod - Ph. 4 DPR ASSOCIATES, INC Prepared by: DDS DPR Job #: 13052Checked by: HVN Impervious Estimates Location: Kannapolis, NCDate: 6-24-14 Travertine - BMP #1 Rev.: 10-8-14 Estimated Impervious Area Breakdown - PHASE 4-Travertine Trail - BMP #1 3,400 sf x 8.5 lots………………………………………………………………………28,900 sq ft=0.66 ac (Avg. lot pad = 2,710 sf + 18'x25' D/W + 4'x10' sidewalk + 100 sf patio + 100 sf misc. allocation) Streets: Streets: Streets & Sidewalks0,000 sq ft=0.00 ac 00,000 sq ft=0.00 ac 0,000 sq ft=0.00 ac …0,000 sq ft=0.00 ac Sidewalk (one side Phase 4B only):…………………………………………… Additional Impervious (Driveway within street R/W) (Approx. 20 ft x 8 ft x 50 lots): ………………………………………………0,000 sq ft=0.00 ac 0,000 sq ft0.00 ac Sub-Total Pond @ W. S. …………………………………………………………………….. 0,000 sq ft=0.00 ac Existing: 0,000 sq ft=0.00 ac Total Impervious Are28,900 sq ft=0.66 ac a ………………………………………………………………… BMP 2 Site Area=…………………………………………….…………………………………………………..2.50 ac 24% Threshold………………………….…………………………………………………..0.60 ac BMP Watershed Area=………………..…………..………………………………………………………………..2.50 ac Impervious Area Summary Imperv. Area% of Imp. Area of % of Imp. Area of (Ac) Site AreaWS Area Single Family0.6626.54%26.54% Streets0.000.00%0.00% Pond @ WS0.000.00%0.00% Existing0.000.00%0.00% Total0.6626.54%26.54% T:\PROJECTS\2013 PROJECTS\13052\CALCS\BMP\13052-Impervious Calcs.xlsplotted: 10/15/2014Sheet 1 of 1 Project: WATERFORD - PH 4 B DPR ASSOCIATES, INC Prepared by: DDS DPR Job #: 13052Checked by: HVN Impervious Estimates Location: Kannapolis, NCDate: 6-24-14 Travertine - BMP #2 Rev.: 10-8-14 Estimated Impervious Area Breakdown - PHASE 4-B only (Travertine Trail) 3,400 sf x 41.5 lots………………………………………………………………………141,100 sq ft=3.24 ac (Avg. lot pad = 2,710 sf + 18'x25' D/W + 4'x10' sidewalk + 100 sf patio + 100 sf misc. allocation) Streets: Streets: Streets & Sidewalks94,928 sq ft=2.18 ac 00,000 sq ft=0.00 ac 0,000 sq ft=0.00 ac …0,000 sq ft=0.00 ac Sidewalk (one side Phase 4B only):…………………………………………… Additional Impervious (Driveway within street R/W) (Approx. 20 ft x 8 ft x 50 lots): ………………………………………………10,000 sq ft=0.23 ac 104,928 sq ft2.41 ac Sub-Total Pond @ W. S. …………………………………………………………………….. 0,000 sq ft=0.00 ac Existing: 0,000 sq ft=0.00 ac Total Impervious Are246,028 sq ft=5.65 ac a ………………………………………………………………… BMP 2 Site Area=…………………………………………….…………………………………………………..15.40 ac 24% Threshold………………………….…………………………………………………..3.70 ac BMP Watershed Area=………………..…………..………………………………………………………………..15.40 ac Impervious Area Summary Imperv. Area% of Imp. Area of % of Imp. Area of (Ac) Site AreaWS Area Single Family3.2421.03%21.03% Streets2.4115.64%15.64% Pond @ WS0.000.00%0.00% Existing0.000.00%0.00% Total5.6536.68%36.68% T:\PROJECTS\2013 PROJECTS\13052\CALCS\BMP\13052-Impervious Calcs.xlsplotted: 10/15/2014Sheet 1 of 1 Project: Waterford Ph. 4Prepared by: DDS DPR ASSOCIATES, INC DPR Job No.: 13052Checked by: HVN RUN-OFF CURVE NUMBER Location: KannapolisDate: 10-08-2014 (Charlotte-Meck Storm Water Design Manual Pre-Developed CN for BMP #1 Total Drain. Area (Ac.) 1.50 Percentage Site Soil TypeSoil Groupof Basin CeB, ChA0% B EnB, PoDC100% Hydrologic Soil Group Use d Percent of CN for WeightedCNWeightedTotalWeighted Land UseNo. AcresDrainage AreaGroup BCNGroup CCNWeighted CN CN % Grass land (Good Cond.)0.0%610.07474.074.00.0 0 Wood (Good Cond.)1.5100.0%550.07070.070.070.0 100%70.0 Tota 1.5 l Composite Curve Number (CN): 70 Post-Developed CN for BMP #1 Total Drain. Area (Ac.) 2.60 Percentage Site Soil TypeSoil Groupof Basin CeB, ChA12% B EnB, PoDC88% Hydrologic Soil Group Used Percent of CN for WeightedCNWeightedTotalWeighted Land UseDrainage AreaGroup BCNGroup CCNWeighted CN CN % No. Acres Impervious (Onsite)32.7%9812.19885.998.032.0 0.85 Open space (Good Cond.)1.7567.3%617.57464.972.448.7 Tota100%80.8 2.60 l Composite Curve Number (CN): 81 T:\PROJECTS\2013 PROJECTS\13052\CALCS\BMP\13052-CN.xls Sheet: 1 of 1 Project: Waterford Ph. 4Prepared by: DDS DPR ASSOCIATES, INC DPR Job No.: 13052Checked by: HVN RUN-OFF CURVE NUMBER Location: KannapolisDate: 10-08-2014 (Charlotte-Meck Storm Water Design Manual Pre-Developed CN for BMP #2 Total Drain. Area (Ac.) 16.00 Percentage Site Soil TypeSoil Groupof Basin CeB, ChA27% B EnB, PoDC73% Hydrologic Soil Group Use d Percent of CN for WeightedCNWeightedTotalWeighted Land UseNo. AcresDrainage AreaGroup BCNGroup CCNWeighted CN CN % Grass land (Good Cond.)50.5%6116.57454.070.535.6 0 Wood (Good Cond.)1.549.5%5514.97051.166.032.6 100%68.2 Tota 1.5 l Composite Curve Number (CN): 68 Post-Developed CN for BMP #2 Total Drain. Area (Ac.) 15.00 Percentage Site Soil TypeSoil Groupof Basin CeB, ChA35% B EnB, PoDC66% Hydrologic Soil Group Used Percent of CN for WeightedCNWeightedTotalWeighted Land UseDrainage AreaGroup BCNGroup CCNWeighted CN CN % No. Acres Impervious (Onsite)39.0%9833.89864.298.038.2 5.85 Open space (Good Cond.)9.1561.0%6121.07448.569.542.4 Tota100%80.6 15.00 l Composite Curve Number (CN): 81 T:\PROJECTS\2013 PROJECTS\13052\CALCS\BMP\13052-CN.xlsSheet: 1 of 1 III. BMPDPD&C ETENTION OND ESIGN ALCULATIONS Project: Waterford Phs. 4 DPR ASSOCIATES, INC Prepared By: DDS Job No.: 13052Checked By: HVN DRY POND DESIGN Location: Kannapolis, NCDate: 6-24-14 Rev.10-14-14 DESIGN CRITERIA PER KANNAPOLIS BMP ORDINANCE * BMP PH 4 - DRY DETENTION POND #1 * Total Drainage Area (A) PHASE 4A:2.65ac 27.0% * Total Impervious Area "A imp" USED =0.72ac (See attached Impervious Calcs) * Total Water Quality Volume To Treat (First 1" of Rainfall): WQ = (P/12) (A) (R) (43560) = 2,819 cf vv (Simple Method, Schueler) P: Water Quality Design Storm, 1st Inch of Rainfall 1inch A: Drainage Area (Impervious Area Only)2.65ac. R: 0.05 + 0.009 (I) = 0.293 v I: % of Impervious Area27.0% * Estimated Storm Water Volume 1-yr, 6-hr Post-Dev: Qv = (P-0.2S)^2/ (P+0.8S) * A * (43560/12) = 6,123cf (SCS Method) 2.05inch P: Design Storm, 1-yr 6-hr Storm Rainfall depth 2.65ac. A: Drainage Area 2.35inch S = 1000/CN-10 = 81 CN: Curve Number * Estimated Storm Water Volume 10-yr, 6-hr Post-Dev: Qv = (P-0.2S)^2/ (P+0.8S) * A * (43560/12) = 18,365cf (SCS Method) 3.56inch P: Design Storm, 10-yr 6-hr Storm Rainfall depth 2.65ac. A: Drainage Area 2.05inch S = 1000/CN-10 = 83 CN: Curve Number BMP Storage Volume Provided: StageSurface AreaIncremental StorageTotal Storage (ft) (sf)(cf)(cf) Bottom of Pond 639.050000 640.01,5001,0001,000 Top of Dam 641.02,5002,0003,000 Static Water Quality Evelation @640.91ft * Orifice Calcs For Detawering Time 2 days (48 hrs) cf 2,819 1-in Storm Volume sf 1,476 Average Surface Area Area of Outlet Orifice (sf), a =(2)(A)h^(1/2))/(c)(t)(2g)^(1/2)) (NCDENR, Orifice Equation) 0.005 a =where: A= Resevoir Area, sf1,476 0.95 Max. Orifice Diameter (inch), d =h= Falling Head, ft1.91 c= Discharge Coefficient0.6 1.0t= Time (48 Hrs), sec. Orifice Diameter (inch) Used, d =172,800 g= Accelleration, ft/sq.sec32.2 a= Orifice Area (sf) d= Orifice Diameter (inch) printed 11/3/2014 T:\PROJECTS\2013 PROJECTS\13052\CALCS\BMP\13052-BMP WQ.xlspage 1 of 1 Project: Waterford Phs. 4 DPR ASSOCIATES, INC Prepared By: DDS Job No.: 13052Checked By: HVN DRY POND DESIGN Location: Kannapolis, NCDate: 6-24-14 Rev.10-14-14 DESIGN CRITERIA PER KANNAPOLIS BMP ORDINANCE * BMP PH 4 - DRY DETENTION POND #2 * Total Drainage Area (A) PHASE 4A:15.35ac 36.7% * Total Impervious Area "A imp" USED =5.63ac (See attached Impervious Calcs) * Total Water Quality Volume To Treat (First 1" of Rainfall): WQ = (P/12) (A) (R) (43560) = 21,191 cf vv (Simple Method, Schueler) P: Water Quality Design Storm, 1st Inch of Rainfall 1inch A: Drainage Area (Impervious Area Only)15.35ac. R: 0.05 + 0.009 (I) = 0.380 v I: % of Impervious Area36.7% * Estimated Storm Water Volume 1-yr, 6-hr Post-Dev: Qv = (P-0.2S)^2/ (P+0.8S) * A * (43560/12) = 35,464cf (SCS Method) 2.05inch P: Design Storm, 1-yr 6-hr Storm Rainfall depth 15.35ac. A: Drainage Area 2.35inch S = 1000/CN-10 = 81 CN: Curve Number * Estimated Storm Water Volume 10-yr, 6-hr Post-Dev: Qv = (P-0.2S)^2/ (P+0.8S) * A * (43560/12) = 106,378cf (SCS Method) 3.56inch P: Design Storm, 10-yr 6-hr Storm Rainfall depth 15.35ac. A: Drainage Area 2.05inch S = 1000/CN-10 = 83 CN: Curve Number BMP Storage Volume Provided: StageSurface AreaIncremental StorageTotal Storage (ft) (sf)(cf)(cf) Bottom of Pond 636.08,50000 637.010,5009,5009,500 Top of Pond 638.013,00011,75021,250 Static Water Quality Evelation @637.99ft * Orifice Calcs For Detawering Time 2 days (48 hrs) cf 21,191 1-in Storm Volume sf 10,622 Average Surface Area Area of Outlet Orifice (sf), a =(2)(A)h^(1/2))/(c)(t)(2g)^(1/2)) (NCDENR, Orifice Equation) 0.036 a =where: A= Resevoir Area, sf10,622 2.58 Max. Orifice Diameter (inch), d =h= Falling Head, ft1.99 c= Discharge Coefficient0.6 2.0t= Time (48 Hrs), sec. Orifice Diameter (inch) Used, d =172,800 g= Accelleration, ft/sq.sec32.2 a= Orifice Area (sf) d= Orifice Diameter (inch) T:\PROJECTS\2013 PROJECTS\13052\CALCS\BMP\13052-BMP WQ.xlspage 1 of 1 IV. BMPHA YDROGRAPH NALYSIS Hydrograph Summary Report Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2011 by Autodesk, Inc. v8 Hyd.HydrographPeakTimeTime toHyd.InflowMaximumTotalHydrograph No.typeflowintervalPeakvolumehyd(s)elevationstrge usedDescription (origin)(cfs)(min)(min)(cuft)(ft)(cuft) 2SCS Runoff0.0002n/a0------------------BMP #1, Pre-Developed, MARR 4SCS Runoff0.4921147972------------------BMP/Dry Det. Pond 1, Post Dev 1inch 5Reservoir0.02212929554639.81807BMP 1 Routed 1inch-6hr 10SCS Runoff0.0002n/a0------------------BMP #2, Pre-Developed, MARR 12SCS Runoff2.84811475,629------------------BMP/Dry Det. Pond 2, Post Dev 1inch 13Reservoir0.08912935,24512636.535,014BMP 2 Routed 1inch-6hr 13052-Hydraflow-BMPs-WQ.gpwReturn Period: 3 YearMonday, Nov 3, 2014 Pond Report Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2011 by Autodesk, Inc. v8Monday, Nov 3, 2014 Pond No. 1 - Dry Detention Pond #1 Pond Data Contours -User-defined contour areas. Average end area method used for volume calculation. Begining Elevation = 639.00 ft Stage / Storage Table Stage (ft)Elevation (ft)Contour area (sqft)Incr. Storage (cuft)Total storage (cuft) 0.00639.0050000 1.00640.001,5001,0001,000 2.00641.002,5002,0003,000 Culvert / Orifice StructuresWeir Structures [A][B][C][PrfRsr][A][B][C][D] = 4.001.000.000.00= 0.000.000.000.00 Rise (in)Crest Len (ft) = 4.001.000.000.00= 0.000.000.000.00 Span (in)Crest El. (ft) No. Barrels= 1100Weir Coeff.= 3.333.333.333.33 Invert El. (ft)= 639.00639.000.000.00Weir Type= ------------ = 20.000.500.000.00= NoNoNoNo Length (ft)Multi-Stage Slope (%)= 0.500.000.00n/a N-Value= .013.013.013n/a = 0.600.600.600.60= 0.000(by Contour) Orifice Coeff.Exfil.(in/hr) = n/aYesNoNo= 0.00 Multi-StageTW Elev. (ft) Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s). Stage / Storage / Discharge Table StageStorageElevationClv AClv BClv CPrfRsrWr AWr BWr CWr DExfilUserTotal ftcuftftcfscfscfscfscfscfscfscfscfscfscfs 0.000639.000.000.00------------------------0.000 0.10100639.100.01 ic0.01 ic------------------------0.006 0.20200639.200.01 ic0.01 ic------------------------0.010 0.30300639.300.01 ic0.01 ic------------------------0.013 0.40400639.400.02 oc0.01 ic------------------------0.015 0.50500639.500.02 oc0.02 ic------------------------0.017 0.60600639.600.02 oc0.02 ic------------------------0.019 0.70700639.700.02 oc0.02 ic------------------------0.020 0.80800639.800.02 oc0.02 ic------------------------0.022 0.90900639.900.02 oc0.02 ic------------------------0.023 1.001,000640.000.03 oc0.02 ic------------------------0.025 1.101,200640.100.03 oc0.03 ic------------------------0.026 1.201,400640.200.03 oc0.03 ic------------------------0.027 1.301,600640.300.03 oc0.03 ic------------------------0.029 1.401,800640.400.03 oc0.03 ic------------------------0.030 1.502,000640.500.03 oc0.03 ic------------------------0.031 1.602,200640.600.03 oc0.03 ic------------------------0.032 1.702,400640.700.03 oc0.03 ic------------------------0.033 1.802,600640.800.03 oc0.03 ic------------------------0.034 1.902,800640.900.04 oc0.03 ic------------------------0.035 2.003,000641.000.04 oc0.04 ic------------------------0.036 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2011 by Autodesk, Inc. v8Monday, Nov 3, 2014 Hyd. No. 2 BMP #1, Pre-Developed, MARR Hydrograph type= SCS RunoffPeak discharge= 0.000 cfs Storm frequency= 3 yrsTime to peak= n/a Time interval= 2 minHyd. volume= 0 cuft Drainage area= 1.550 acCurve number= 70 Basin Slope= 0.0 %Hydraulic length= 0 ft Tc method= UserTime of conc. (Tc)= 12.00 min Total precip.= 2.64 inDistribution= Synthetic Storm duration= 6.00 hrsShape factor= 484 BMP #1, Pre-Developed, MARR Q (cfs)Q (cfs) Hyd. No. 2 -- 3 Year 0.100.10 0.090.09 0.080.08 0.070.07 0.060.06 0.050.05 0.040.04 0.030.03 0.020.02 0.010.01 0.000.00 020406080100120 Time (min) Hyd No. 2 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2011 by Autodesk, Inc. v8Monday, Nov 3, 2014 Hyd. No. 4 BMP/Dry Det. Pond 1, Post Dev 1inch-6hr Storm Hydrograph type= SCS RunoffPeak discharge= 0.492 cfs Storm frequency= 3 yrsTime to peak= 147 min Time interval= 1 minHyd. volume= 972 cuft Drainage area= 2.650 acCurve number= 81 Basin Slope= 0.0 %Hydraulic length= 0 ft Tc method= UserTime of conc. (Tc)= 5.00 min Total precip.= 1.00 inDistribution= Custom Storm duration= Custom Storm.cdsShape factor= 484 BMP/Dry Det. Pond 1, Post Dev 1inch-6hr Storm Q (cfs)Q (cfs) Hyd. No. 4 -- 3 Year 0.500.50 0.450.45 0.400.40 0.350.35 0.300.30 0.250.25 0.200.20 0.150.15 0.100.10 0.050.05 0.000.00 0306090120150180210240270300 Time (min) Hyd No. 4 Precipitation Report Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2011 by Autodesk, Inc. v8Monday, Nov 3, 2014 Hyd. No. 4 BMP/Dry Det. Pond 1, Post Dev 1inch-6hr Storm Storm Frequency= 3 yrsTime interval= 1 min Total precip.= 1.0000 inDistribution= Custom Storm duration= Custom Storm.cds Incremental Rainfall Precipitation Precip (in)Precip (in) Hyd. No. 4 : BMP/Dry Det. Pond 1, Post Dev 1inch-6hr Storm - 3 Year 0.100.10 0.090.09 0.080.08 0.070.07 0.060.06 0.050.05 0.040.04 0.030.03 0.020.02 0.010.01 0.000.00 0306090120150180210240270300 Time (min) Custom Design Storm -- Custom Storm.cds Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2011 by Autodesk, Inc. v8Monday, Nov 3, 2014 Hyd. No. 5 BMP 1 Routed 1inch-6hr Hydrograph type= ReservoirPeak discharge= 0.022 cfs Storm frequency= 3 yrsTime to peak= 292 min Time interval= 1 minHyd. volume= 955 cuft Inflow hyd. No.= 4 - BMP/Dry Det. Pond 1, Post Dev 1inch-6hr StormMax. Elevation= 639.81 ft Reservoir name= Dry Detention Pond #1Max. Storage= 807 cuft Storage Indication method used. BMP 1 Routed 1inch-6hr Q (cfs)Q (cfs) Hyd. No. 5 -- 3 Year 0.500.50 0.450.45 0.400.40 0.350.35 0.300.30 0.250.25 0.200.20 0.150.15 0.100.10 0.050.05 0.000.00 018036054072090010801260144016201800 Time (min) Hyd No. 5Hyd No. 4Total storage used = 807 cuft Pond Report Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2011 by Autodesk, Inc. v8Monday, Nov 3, 2014 Pond No. 4 - BMP Dry Detention Pond #2 Pond Data Contours -User-defined contour areas. Average end area method used for volume calculation. Begining Elevation = 636.00 ft Stage / Storage Table Stage (ft)Elevation (ft)Contour area (sqft)Incr. Storage (cuft)Total storage (cuft) 0.00636.008,50000 1.00637.0010,5009,5009,500 2.00638.0013,00011,75021,250 Culvert / Orifice StructuresWeir Structures [A][B][C][PrfRsr][A][B][C][D] = 4.002.500.000.00= 0.000.000.000.00 Rise (in)Crest Len (ft) = 4.002.500.000.00= 0.000.000.000.00 Span (in)Crest El. (ft) No. Barrels= 1100Weir Coeff.= 3.333.333.333.33 Invert El. (ft)= 636.00636.000.000.00Weir Type= ------------ = 20.000.500.000.00= NoNoNoNo Length (ft)Multi-Stage Slope (%)= 0.500.000.00n/a N-Value= .013.013.013n/a = 0.600.600.600.60= 0.000(by Contour) Orifice Coeff.Exfil.(in/hr) = n/aYesNoNo= 0.00 Multi-StageTW Elev. (ft) Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s). Stage / Storage / Discharge Table StageStorageElevationClv AClv BClv CPrfRsrWr AWr BWr CWr DExfilUserTotal ftcuftftcfscfscfscfscfscfscfscfscfscfscfs 0.000636.000.000.00------------------------0.000 0.10950636.100.01 oc0.01 ic------------------------0.013 0.201,900636.200.04 oc0.04 ic------------------------0.040 0.302,850636.300.06 oc0.06 ic------------------------0.058 0.403,800636.400.07 oc0.07 ic------------------------0.073 0.504,750636.500.09 oc0.09 ic------------------------0.086 0.605,700636.600.10 oc0.10 ic------------------------0.097 0.706,650636.700.11 oc0.11 ic------------------------0.106 0.807,600636.800.11 oc0.11 ic------------------------0.111 0.908,550636.900.12 oc0.12 ic------------------------0.121 1.009,500637.000.13 oc0.13 ic------------------------0.130 1.1010,675637.100.14 oc0.14 ic------------------------0.138 1.2011,850637.200.15 oc0.15 ic------------------------0.146 1.3013,025637.300.15 oc0.15 ic------------------------0.153 1.4014,200637.400.16 oc0.16 ic------------------------0.160 1.5015,375637.500.17 oc0.17 ic------------------------0.167 1.6016,550637.600.17 oc0.17 ic------------------------0.173 1.7017,725637.700.18 oc0.18 ic------------------------0.179 1.8018,900637.800.19 oc0.19 ic------------------------0.185 1.9020,075637.900.19 oc0.19 ic------------------------0.191 2.0021,250638.000.20 oc0.20 ic------------------------0.197 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2011 by Autodesk, Inc. v8Monday, Nov 3, 2014 Hyd. No. 10 BMP #2, Pre-Developed, MARR Hydrograph type= SCS RunoffPeak discharge= 0.000 cfs Storm frequency= 3 yrsTime to peak= n/a Time interval= 2 minHyd. volume= 0 cuft Drainage area= 16.000 acCurve number= 68 Basin Slope= 0.0 %Hydraulic length= 0 ft Tc method= UserTime of conc. (Tc)= 22.00 min Total precip.= 2.64 inDistribution= Synthetic Storm duration= 6.00 hrsShape factor= 484 BMP #2, Pre-Developed, MARR Q (cfs)Q (cfs) Hyd. No. 10 -- 3 Year 0.100.10 0.090.09 0.080.08 0.070.07 0.060.06 0.050.05 0.040.04 0.030.03 0.020.02 0.010.01 0.000.00 020406080100120 Time (min) Hyd No. 10 Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2011 by Autodesk, Inc. v8Monday, Nov 3, 2014 Hyd. No. 12 BMP/Dry Det. Pond 2, Post Dev 1inch-6hr Storm Hydrograph type= SCS RunoffPeak discharge= 2.848 cfs Storm frequency= 3 yrsTime to peak= 147 min Time interval= 1 minHyd. volume= 5,629 cuft Drainage area= 15.350 acCurve number= 81 Basin Slope= 0.0 %Hydraulic length= 0 ft Tc method= UserTime of conc. (Tc)= 5.00 min Total precip.= 1.00 inDistribution= Custom Storm duration= Custom Storm.cdsShape factor= 484 BMP/Dry Det. Pond 2, Post Dev 1inch-6hr Storm Q (cfs)Q (cfs) Hyd. No. 12 -- 3 Year 3.003.00 2.002.00 1.001.00 0.000.00 0306090120150180210240270300 Time (min) Hyd No. 12 Precipitation Report Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2011 by Autodesk, Inc. v8Monday, Nov 3, 2014 Hyd. No. 12 BMP/Dry Det. Pond 2, Post Dev 1inch-6hr Storm Storm Frequency= 3 yrsTime interval= 1 min Total precip.= 1.0000 inDistribution= Custom Storm duration= Custom Storm.cds Incremental Rainfall Precipitation Precip (in)Precip (in) Hyd. No. 12 : BMP/Dry Det. Pond 2, Post Dev 1inch-6hr Storm - 3 Year 0.100.10 0.090.09 0.080.08 0.070.07 0.060.06 0.050.05 0.040.04 0.030.03 0.020.02 0.010.01 0.000.00 0306090120150180210240270300 Time (min) Custom Design Storm -- Custom Storm.cds Hydrograph Report Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2011 by Autodesk, Inc. v8Monday, Nov 3, 2014 Hyd. No. 13 BMP 2 Routed 1inch-6hr Hydrograph type= ReservoirPeak discharge= 0.089 cfs Storm frequency= 3 yrsTime to peak= 293 min Time interval= 1 minHyd. volume= 5,245 cuft Inflow hyd. No.= 12 - BMP/Dry Det. Pond 2, Post Dev 1inch-6hr StormMax. Elevation= 636.53 ft Reservoir name= BMP Dry Detention Pond #2Max. Storage= 5,014 cuft Storage Indication method used. BMP 2 Routed 1inch-6hr Q (cfs)Q (cfs) Hyd. No. 13 -- 3 Year 3.003.00 2.002.00 1.001.00 0.000.00 03006009001200150018002100240027003000 Time (min) Hyd No. 13Hyd No. 12Total storage used = 5,014 cuft V. BMPA PPENDIX HYDROLOGY CHAPTER 2 Table 2-12 1 Runoff Curve Numbers Curve numbers for ------------------------------Cover description -------------------------------- -----hydrologic soil group----- Average percent 2/ Cover type and hydrologic condition impervious area A B C D Fully developed urban areas (vegetation established) 3/ Open space (lawns, parks, golf courses, cemeteries, etc.) : Poor condition (grass cover < 50%) .................... 68 79 86 89 Fair condition (grass cover 50% to 75%) ............ 49 69 79 84 Good condition (grass cover > 75%) ................... 39 61 74 80 Impervious areas: Paved parking lots, roofs, driveways, etc. (excluding right-of-way) ..................................... 98 98 98 98 Streets and roads: Paved; curbs and storm sewers (excluding right-of-way) ....................................................... 98 98 98 98 Paved; open ditches (including right-of-way) .... 83 89 92 93 Gravel (including right-of-way) .......................... 76 85 89 91 Dirt (including right-of-way) .............................. 72 82 87 89 Urban districts: Commercial and business ............................................ 85 89 92 94 95 Industrial ..................................................................... 72 81 88 91 93 Residential districts by average lot size: 1/8 acre or less (town houses) ..................................... 65 77 85 90 92 1/4 acre ........................................................................ 38 61 75 83 87 1/3 acre ........................................................................ 30 57 72 81 86 1/2 acre ........................................................................ 25 54 70 80 85 1 acre ........................................................................... 20 51 68 79 84 2 acres ......................................................................... 12 46 65 77 82 Agricultural Lands Woods poor hydrologic condition ....................................... 45 66 77 83 fair hydrologic condition ......................................... 36 60 73 79 good hydrologic condition ...................................... 30 55 70 77 Developing urban areas Newly graded areas (pervious areas only, no vegetation) ........................... 77 86 91 94 1 Average runoff condition, and Ia = 0.2S. e CNÓs. Other assumptions are as follows: impervious areas 2 The average percent impervious area shown was used to develop the composit area directly connected to the drainage system, impervious areas have a CN of 98, and pervious areas are considered equivalent to open space in good hydrologic condition. CNÓs shown are equivalent to those of pasture. Composite CNÓs ma 3 Source: Source: 210-VI-TR-55, Second Edition, June 1986 2.4.5 Runoff Coefficient The runoff coefficient (C) is the variable of the rational method least susceptible to precise determination and requires judgment and understanding on the part of the design engineer. While engineering judgment will always be required in the selection of runoff coefficients, typical coefficients represent the integrated effects of many drainage basin parameters. Table 2-4 gives the recommended runoff coefficients for the Rational Method. Table 2-4 Recommended Runoff Coefficient Values Description of Area Runoff Coefficient (C) Lawns 0.30 Wooded 0.25 Streets 0.95 Gravel Areas 0.55 Drives, walks, roofs 0.95 Bare soils 0.45 Residential (including streets): Single-Family (Lot < 20,000 square feet - SF) 0.60 Single-Family (Lot > 20,000 square feet - SF) 0.50 Multi-family, Attached 0.70 Industrial: Light areas 0.70 Heavy areas 0.80 Office Parks 0.75 Shopping Centers 0.80 Note: The above runoff coefficients are valid for 2-year to 10-year storm frequencies only. Coefficients must be accompanied with a C factor when used for less frequent, f higher intensity storms.