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HomeMy WebLinkAboutSW3171002_NCDEQ Stormwater Report_20171020n;j STEWAR Storm Water Report For the proposed Classroom Building Waxhaw, North Carolina Prepared for Thales Academy Prepared By Stewart, Inc. October 19, 2017 QL Table of Contents EXECUTIVE SUMMARY ............................................. 1 Site Information..................................................... 1 Computations..........................................................2 STORMWATER REPORT THALES ACADEMY EXECUTIVE SUMMARY This report has been prepared specifically to address the Post Construction Stormwater requirements of the North Carolina Department of Environmental Quality (NCDEQ) for the development of a classroom building for Thales Academy. Site Information This project involves the construction of a classroom building. A swale will be constructed at the property line to divert offsite drainage to the ditch at New Town Rd. The site will be split into two drainage areas. The first drainage area consists of runoff from the building and parking lot. This runoff will be collected in Bio -retention Area #1. The remainder of runoff on the site will be collected in Bio - retention Area #2. The runoff from the site discharges directly into a FEMA regulated floodplain, therefore no detention required. The total proposed impervious area is 1.8 acres. The total drainage area for this site is 2.76 acres and is split into two watersheds. Drainage area #1 consists of 2.13 acres and is treated by Bio -retention area #1. Drainage area #2 consists of 0.63 acres and is treated by Bio -retention area #2. The latest version of the United States Department of Agriculture Soil Conservation Service Soil Survey of Mecklenburg County, North Carolina indicates that the soils at this area are primarily Tarrus Gravelly Silt Loam with 8-15% slopes, classified as Hydrologic Soil Group B. BMP routings for both Bioretention Area #1 and 2 are provided to determine whether the BMP's can withstand and release runoff from the 50 -year storm. No other routings are provided as there is no detention requirements for this site. Water quality calculations are also provided for both bioretention areas. Computations Storm Pipes Water Quality Calcs (Storm -EZ Spreadsheet) Rip Rap Apron Calcs 50 Year BMP Routings X17010 Thales 5/1/2017 ROOF DRAINS 1 2 0.95 7.56 0.08 STORM WATER (MANNINGS) 8 DRAINAGE 0.013 1.65 3.47 1.21 0.57 OK 2 3 From To C. 10 Yr. "i" Area To Inlet 10 Yr. Q Cumm. Q, Pipe Length Pipe Diamete r Pipe Slope Invert Elevatio n (From) Invert Elevatio n (To) Roughn ess Coeffici ant Actual Velocity Velocity Full Full Flow Capacit y Actual Flow PIPE SIZE CHECK 0.08 0.57 1.72 (in/hr) (acres) R3 sec R3 sec (f<) (inches) (%) ((t) ((t) 4 wsec) (ft/sec) R3 sec R3 sec 0.57 2.30 26 12 1.0 0.013 2.93 4.55 3.57 2.30 OK 5 6 0.95 7.56 0.08 0.57 2.87 23 #1 #2 0.95 7.56 0.18 1.29 1.29 117.38 15 1.46 613.46 611.75 0.013 1.05 6.37 7.81 1.29 OK #2 #3 0.95 7.56 0.62 4.45 5.75 31.10 15 5.63 611.75 610.00 0.013 4.68 12.51 15.35 5.75 OK 7.56 #4 #5 0.95 7.56 0.04 0.29 0.29 46.47 15 0.52 611.48 611.24 0.013 0.23 3.79 4.65 0.29 OK #5 #7 0.95 7.56 0.04 0.29 0.57 55.66 15 1.87 611.04 610.00 0.013 0.47 7.21 8.85 0.57 OK 7.56 #6 #7 0.95 1 7.56 0.13 0.93 1 0.93 103.49 15 0.50 610.52 610.00 0.013 0.76 3.74 4.59 0.93 OK 7.56 #10 #13 0.95 7.56 0.10 0.72 0.72 69.47 15 0.50 609.46 609.11 0.013 0.59 3.74 4.59 0.72 OK #11 #12 0.95 7.56 0.08 0.57 0.57 33 15 0.49 609.37 609.21 0.013 0.47 3.69 4.53 0.57 OK #12 #13 0.95 7.56 0.16 1.15 1.72 19 15 0.54 609.21 609.11 0.013 1.41 3.86 4.74 1.72 OK #13 #14 0.95 7.56 0.13 0.93 3.95 19 15 0.59 609.11 609.00 0.013 3.22 4.05 4.97 3.95 OK ROOF DRAINS 1 2 0.95 7.56 0.08 0.57 0.57 23 8 1.0 0.013 1.65 3.47 1.21 0.57 OK 2 3 0.95 7.56 0.08 0.57 1.15 25 8 1.0 0.013 3.29 3.47 1.21 1.15 OK 3 4 0.95 7.56 0.08 0.57 1.72 25 10 1.0 0.013 3.16 4.03 2.19 1.72 OK 4 5 0.95 7.56 0.08 0.57 2.30 26 12 1.0 0.013 2.93 4.55 3.57 2.30 OK 5 6 0.95 7.56 0.08 0.57 2.87 23 12 1.0 0.013 3.66 4.55 3.57 2.87 OK 6 HW #7 0.95 7.56 0.08 0.57 3.45 80 12 1.0 0.013 4.39 4.55 3.57 3.45 OK Thales Academy • Waxhaw, NC UNION County AA Catawba River Basin NCDENR Drainage Area # 1 of 1 POST -DEVELOPMENT LAND USE CALCULATIONS SCM # 500 Permeable Pavement: Green Roofs: DSD PAW Ds, Area Retrofit? Downstream Comments SCM # (in) (%) (in) (sf) (acres) SCM # 600 1.50 1 0.00 No Lot Area I Max Imp / Lot Woods I Lot I Open Space I Lot # of Lots % Imp. Avg Lot Size (sf.) (ac.) (sf) (sf) (sf) Land Use: Land -Use Permeable Pavement + BUA: Area Land Excluded, or Partially Excluded, from Volume Calculations: (sf.) ac. Surface Waters&Non-Coastal Wetlands: 0 0.00 Coastal Wetlands: 0 0.00 Total Site Area: 1 92,778 2.13 e aummary. Infiltration Total Has Orifice Orifice Down - HSG Pvmt T YPe Pavement Area Additional BUA Void Space Rate P Gravel Depth Synthetic Dia. Height stream Infiltration Detention -5,801 cf Liner? SCM Check Check (sf) (acres) (so (acres) (in/hr) (%) (in) (In) (in) -773 cf Total Runoff Reduction = -3.19 acre -inches = -11,597 cf 0.00 0.00 No Green Roofs: DSD PAW Ds, Area Retrofit? Downstream Comments SCM # (in) (%) (in) (sf) (acres) SCM # 600 1.50 1 0.00 No Lot Area I Max Imp / Lot Woods I Lot I Open Space I Lot # of Lots % Imp. Avg Lot Size (sf.) (ac.) (sf) (sf) (sf) Land Use: Land -Use Permeable Pavement + BUA: Area Land Excluded, or Partially Excluded, from Volume Calculations: (sf.) ac. Surface Waters&Non-Coastal Wetlands: 0 0.00 Coastal Wetlands: 0 0.00 Total Site Area: 1 92,778 2.13 e aummary. Rainfall Volume= 3.19 acre -inches = 11,597 of Runoff Reduction Components: Natural Infiltration & ET = -1.38 acre -inches = -5,023 cf Disconnected Impervious Surfaces = 0.00 acre -inches = 0 cf SCM Infiltration = -1.60 acre -inches = -5,801 cf Permeable Pavement Infiltration = 0.00 acre -inches = 0 cf Green Roof ET = 0.00 acre -inches = 0 cf Post Filtration Discharge = -0.21 acre -inches = -773 cf Total Runoff Reduction = -3.19 acre -inches = -11,597 cf STORM -EZ 7/2 712 01 7 Version 1.4 Post Development Page 1 of 2 Thales Academy e Waxhaw, NC UNION County ©M Catawba River Basin NCDENR Drainage Area # 1 of 1 POST -DEVELOPMENT LAND USE CALCULATIONS SCM Treatment., Treated SCM Outflow = 0.00 acm4nches = Untreated Surface Runoff= 0.00 acre -inches = 0 cf Pre -Development Runoff = 0.12 acre -inches = 420 cf Difference = -0.12 acre -inches = -420 Cf The Post -Development project area contains 61449 sf of built upon area, resulting in an overall density of 66.23%. STORM -EZ 7/27/2017 version 1.4 Post Development Page 2 of 2 Thales Academy o Waxhaw, NC UNION County of Catawba River Basin NCDENR Drainage Area # F1� of �1� PRE -DEVELOPMENT LAND USE CALCULATIONS Pre -Development Land Us Note: Enter BUA Draining to Permeable Pavement Below User Defined Drainage Areas: I Comp. II Area HSG Description CN Area (sf.) (ac.) Existing Permeable Pavement (Infiltration): SCM # Description 100 SCM # Existing Green Roofs: 0.00 778 HSG Pavement Area Soil Gravel Void Additional BUA Infiltratio n Rate Space Total Orifice Orifice Gravel Depth Dia. Height BUA % Has Synthetic D.S. Liner? BMP (sf) (sf) (in/hr) (%) (in) (in) (in) 0 0.00 acres Green Roofs : 0 0.00 acres Preserved Surface Waters & Non -Coastal Wetlands : 0.00 acre -inches = DSD PAW Dar I Area DS SCM # Notes I I 1.50 I 1 I I 0.00 I I I Pre -Development SCMs: Land Use Summary., Area at. 11,597 Drainage Area From Land Use Tables: 92,778 2.13 acres Permeable Pavement + Additional BUA: 0 0.00 acres Green Roofs : 0 0.00 acres Preserved Surface Waters & Non -Coastal Wetlands : 0.00 acre -inches = 0.00 acres Preserved Coastal Wetlands : 0.00 acre -inches = 0.00 acres Total Site Area: 92,778 2.13 acres SCM # 20( Load Rainfall Data Rainfall Volume = me W�Provided 11,597 Drainage Area Runoff Reduction Components: Im Oen s s Downstream SCM Type HSG 3935 88843 SCM 0.00 acre -inches = 0 cf SCM Infiltration = 0.00 acre -inches = Load Rainfall Data Rainfall Volume = 3.19 acre -inches = 11,597 cf Runoff Reduction Components: Natural Infiltration & ET = -3.08 acre -inches = -11,177 cf Disconnected Impervious Surfaces = 0.00 acre -inches = 0 cf SCM Infiltration = 0.00 acre -inches = 0 cf Permeable Pavement Infiltration = 0.00 acre -inches = 0 cf Green Roof ET = 0.00 acre -inches = 0 cf Post Filtration Discharge = 0.00 acre -inches = 0 cf Total Runoff Reduction = -3.08 acre -inches = -11,177 cf SCM Treatment: Treated SCM Outflow = 0.00 acre -inches = 0 cf Untreated Surface Runoff = 0.12 acre -inches = 420 cf The Pre -Development project area contains 3935 sf of built upon area, resulting in an overall density of 4.24%. STORM -EZ 7/27/2017 Version 1.4 Pre -Development Page 1 of 1 Thales Academy A� Waxhaw, NC UNION County 6 Catawba River Basin NCDENR RAINFALL & CALCULATION DATA Project County: UNION Project City: I Waxhaw Rainfall Source: I Charlotte Load Data Loaded Rainfall: Design Storm: First Flush / WQV Calculation Method Discrete SCS Method, Pre - Post (Minimum Design Storm = P90 for non -SA, 1 -yr, 24 -hr for SA) Storm Event Depth (inches) P90 1.50 #N/A P95 #N/A 1 -yr, 24 -hr #N/A 2 -yr, 24 -hr #N/A 10 -yr, 24 -hr #N/A 25 -yr, 24 -hr #N/A 50 -yr, 24 -hr #N/A 100 -yr, 24 -hr #N/A NOTE: Please use the Storm -EZ calculation sheets to document the stormwater design and create the O&M Agreement. Highlighted Storm is Design Storm I JL PROJECT INFORMATION Total Property Area 8.95 acres Total Coastal Wetlands Area 0.00 acres Total Surface Water Area 0.00 acres Complete the breakdown of impervious area for the project Basin Information Entire Site Receiving Stream name 0 Stream Class 0 Stream Index Number Total Drainage Area 92,778 On -Site Drainage Area (sf) 92,778 Offsite Drainage Areas 0 Proposed Impervious Area (sf) 61,449 % Impervious Area total 66% Impervious Surface Area Entire Site On -Site Buildings/Lots (sf) 15,984 On -Site Streets (sf) 6,157 On -Site Parking (sf) 35,071 On -Site Sidewalks (sf) 4,237 Other On -Site s Future sf Off-site s Existing BUA sf Total 61,449 Load Rainfall Data Total Impervious Area 1.41 1 acres Project % impervious area 66% ALL AREAS ARE IN SQUARE FEET Use Worksheet Data? Yes Data in italics is derived from application forms and land use data worksheets and cannot be changed by user. STORM -EZ 7/27/2017 Version 1.4 Project Data Page 1 of 1 Thales Academy Wa th—, NC UNION County AM, Catawba River Basin NCDENR Drainage Area # 1 of 1 PROPOSED SIPs & STRUCTURAL RUNOFF VOLUME CONTROLS Enter only runoff volume below that will be infiltrated or drawn down over 2 to 5 days. Additional volume provided in devices should not be entered in this worksheet. Drawdown time requirement applies to all storm events. Offsite Impervious 0 sf Area Treated STORMWATER CONTROL MEASURES Load Rainfall Data Storm Runoff Fate Summary: Rainfall Volume= 3.19 acre -inches = Drainage Total Runoff Reduction Components: Post Natural Infiltration & ET = -1.38 acre -inches = lmpemious Pervious /. ofTotal %of Total Storage Down- Area Inflow Inflow Infiltration& Filtration Treated %of SCM SCM Permeable Pavement Infiltration = 0.00 acm-inches = Impervious Pervious Volume stream SCM Volume Volume ET Outflow Outflow Volume a Name / Location Type of Devke HSG 61,449 31,329 Area Am (cf) 0 (cf) (Cf) (cf) (cf) (cf) Utilized 700 Pond Bicmlention w/ IWS B 61,449 31,329 100% 100% 4992 6575 6575 5801 773 0 77% cf 31329 sf open space entered IW% of total 10 o Difference = -0.12 acre -inches = -420 cf 61449 sf impervious area entered c compared to 31329 sf total impervious total compered to 61449 sf total impervious. open space. area. pervious Load Rainfall Data Storm Runoff Fate Summary: Rainfall Volume= 3.19 acre -inches = 11,597 of Runoff Reduction Components: Natural Infiltration & ET = -1.38 acre -inches = -5,023 cf Disconnected Impervious Area - 0.00 acre -inches = 0 cf SCM Infiltration = -1.60 acm-inches = -5,801 cf Permeable Pavement Infiltration = 0.00 acm-inches = 0 cf Green Roof ET = 0.00 acm-inches = 0 cf Post Filtration Discharge = -0.21 acre -inches = -773 cf Total Runoff Reduction = -3.19 acm-inchm - -11,597 cf SCM Treatment: Treated SCM Outflow = 0.00 acm-inches = 0 cf Untreated Surface Runoff= 0.00 acre-Inchm - 0 cf Pre -Development Runoff = 0.12. -inch. = 420 cf Difference = -0.12 acre -inches = -420 cf **VOLUME MATCHING ACHIEVED** The Post -Development project area contains 61449 at of built upon area, resulting in an overall density of 66.23%. Warnings: Note: Large storage devices such as wet/dry detention ponds, constructed wetlands, or Infiltration basins may require pond routing calculations. The routing calculations should be provided in addition to this spreadsheet. STORM -EZ 7/27/2017 Version 1.4 Stormwater Controls Page 1 of 1 • Waxhaw, NC UNION County AA Drainage Area # 1 of 1 NCDENR POST -DEVELOPMENT LAND USE CALCULATIONS SCM # 500 Permeable Pavement: Green Roofs: DSD PAW Ds, Area Retrofit? Downstream Comments SCM # (in) I%) (in) (sf) (acres) SCM # 600 1.50 0.00 No Lot Area I Max Imp / Lot Woods I Lot I Open Space I Lot # of Lots %Imp. Avg Lot Size (sf.) (ac.) (sf) (sf) (sf) Land Use: Land -Use Permeable Pavement + BUA: Area Land Excluded, or Partially Excluded, from Volume Calculations: (sf.) ac. Surface Waters&Non-Coastal Wetlands: 0 0.00 Coastal Wetlands: 0 0.00 Total Site Area: 1 27,442 0.63 e aummary. Infiltration Total Has Orifice Orifice Down - HSG Pvmt Type YP Pavement Area Additional BUA Void Space Rate P Gravel Depth Synthetic Dia. Height stream Infiltration Detention -1,931 cf Liner? SCM Check Check (sf) (acres) (so (acres) (in/hr) (%) (in) (In) (in) -257 cf Total Runoff Reduction = -0.94 acre -inches = -3,430 cf B PICP 0.00 0.00 No Green Roofs: DSD PAW Ds, Area Retrofit? Downstream Comments SCM # (in) I%) (in) (sf) (acres) SCM # 600 1.50 0.00 No Lot Area I Max Imp / Lot Woods I Lot I Open Space I Lot # of Lots %Imp. Avg Lot Size (sf.) (ac.) (sf) (sf) (sf) Land Use: Land -Use Permeable Pavement + BUA: Area Land Excluded, or Partially Excluded, from Volume Calculations: (sf.) ac. Surface Waters&Non-Coastal Wetlands: 0 0.00 Coastal Wetlands: 0 0.00 Total Site Area: 1 27,442 0.63 e aummary. Rainfall Volume= 0.94 acre -inches = 3,430 of Runoff Reduction Components: Natural Infiltration & ET = -0.34 acre -inches = -1,242 cf Disconnected Impervious Surfaces = 0.00 acre -inches = 0 cf SCM Infiltration = -0.53 acre -inches = -1,931 cf Permeable Pavement Infiltration = 0.00 acre -inches = 0 cf Green Roof ET = 0.00 acre -inches = 0 cf Post Filtration Discharge = -0.07 acre -inches = -257 cf Total Runoff Reduction = -0.94 acre -inches = -3,430 cf STORM -EZ 8/14/2017 Version 1.4 Post Development Page 1 of 2 e Waxhaw, NC UNION County ©'M Drainage Area # 1 of 1 NCDENR POST -DEVELOPMENT LAND USE CALCULATIONS SCM Treatment., Treated SCM Outflow = 0.00 acm4nches = Untreated Surface Runoff= 0.00 acre -inches = 0 cf Pre -Development Runoff = 0.03 acre -inches = 115 cf Difference = -0.03 acre -inches = -115 cf The Post -Development project area contains 20473 sf of built upon area, resulting in an overall density of 74.6%. STORM -EZ 8/14/2017 Version 1.4 Post Development Page 2 of 2 o Waxhaw, NC UNION County E Drainage Area #F 1 1 of F1 1 NCDENR PRE -DEVELOPMENT LAND USE CALCULATIONS Pre -Development Land Us Note: Enter BUA Draining to Permeable Pavement Below User Defined Drainage Areas: Comp. Area HSG Description CN Area (sf.) (ac.) F. 0 0.6.00 0.00% Subtotal: 27.442 3 3.38% Existing Permeable Pavement (Infiltration): SCM # Description 100 SCM # Existing Green Roofs: HSG Pavement Area Soil Gravel Void Additional BUA Infiltratio n Rate Space Total Orifice Orifice Gravel Depth Dia. Height BUA % Has Synthetic D.S. Liner? BMP (sf) (sf) (in/hr) (%) (in) (in) (in) 0 0.00 acres Green Roofs : 0 0.00 acres Preserved Surface Waters & Non -Coastal Wetlands : 0.00 acre -inches = DSD PAW Dy, I Area DS SCM # Notes 1 1 1.50 I I I I 0.00 I I I Pre -Development SCMs: Land Use Summary., Area at. 3,430 Drainage Area From Land Use Tables: 27,442 0.63 acres Permeable Pavement + Additional BUA: 0 0.00 acres Green Roofs : 0 0.00 acres Preserved Surface Waters & Non -Coastal Wetlands : 0.00 acre -inches = 0.00 acres Preserved Coastal Wetlands: 0.00 acre -inches = 0.00 acres Total Site Area: 27,442 0.63 1 acres SCM # 201 Load Rainfall Data Rainfall Volume = me 3,430 Drainage Area Runoff Reduction Components: Im Oen s s Downstream SCM Type �Provided HSG 927 26515 SCM 0.00 acre -inches = 0 cf SCM Infiltration = 0.00 acre -inches = Load Rainfall Data Rainfall Volume = 0.94 acre -inches = 3,430 cf Runoff Reduction Components: Natural Infiltration & ET = -0.91 acre -inches = -3,315 cf Disconnected Impervious Surfaces = 0.00 acre -inches = 0 cf SCM Infiltration = 0.00 acre -inches = 0 cf Permeable Pavement Infiltration = 0.00 acre -inches = 0 cf Green Roof ET = 0.00 acre -inches = 0 cf Post Filtration Discharge = 0.00 acre -inches = 0 cf Total Runoff Reduction = -0.91 acre -inches = -3,315 cf SCM Treatment: Treated SCM Outflow = 0.00 acre -inches = 0 cf Untreated Surface Runoff= 0.03 acre -inches = 115 cf The Pre -Development project area contains 927 sf of built upon area, resulting in an overall density of 3.38% STORM -EZ 8/14/2017 Version 1.4 Pre -Development Page 1 of 1 Waxhaw, NC UNION County 6 RAINFALL & CALCULATION DATA Project County: UNION Project City: Waxhaw Rainfall Source: Charlotte Load Data Loaded Rainfall: Design Storm: First Flush / WQV Calculation Method Discrete SCS Method, Pre -Post (Minimum Design Storm = P90 for non -SA, 1 -yr, 24 -hr for SA) Storm Event Depth (inches) P90 1.50 #N/A P95 #N/A 1 -yr, 24 -hr #N/A 2 -yr, 24 -hr #N/A 10 -yr, 24 -hr #N/A 25 -yr, 24 -hr #N/A 50 -yr, 24 -hr #N/A 100 -yr, 24 -hr #N/A NOTE: Please use the Storm -EZ calculation sheets to document the stormwater design and create the O&M Agreement. Highlighted Storm is Design Storm I JL PROJECT INFORMATION d Total Property Area 8.95 acres Total Coastal Wetlands Area 0.00 acres Total Surface Water Area 0.00 acres Complete the breakdown of impervious area for the project Basin Information Entire Site Receiving Stream name 0 Stream Class 0 Stream Index Number Total Drainage Area 27,442 On -Site Drainage Area (sf) 27,442 Offsite Drainage Areas 0 Proposed Impervious Area (sf) 20,473 % Impervious Area total 75% Impervious Surface Area Entire Site On -Site Buildings/Lots s 0 On -Site Streets (sf) 15,256 On -Site Parking (sf) 0 On -Site Sidewalks (sf) 5,217 Other On -Site s Future sf Off-site s Existing BUA sf Total 20,473 A NCDENR Load Rainfall Data Total Impervious Area 0.47 1 acres Project % impervious area 75% ALL AREAS ARE IN SQUARE FEET Use Worksheet Data? Yes Data in italics is derived from application forms and land use data worksheets and cannot be changed by user. STORM -EZ 8/14/2017 Version 1.4 Project Data Page 1 of 1 Wa thaw, NC UNION County AM, Drainage Area # 1 of 1 NCDENR PROPOSED SIPs & STRUCTURAL RUNOFF VOLUME CONTROL Enter only runoff volume below that will be infiltrated or drawn down over 2 to 5 days. Additional volume provided in devices should not be entered in this worksheet. Drawdown time requirement applies to all storm events. Offsite ous sf Area TreatedImpervi STORMWATER CONTROL MEASURES Load Rainfall Data Storm Runoff Fate Summary: Rainfall Volume= 0.94 acre -inches = Drainage Total Runoff Reduction Components: Post Natural Infiltration & ET = -0.34 acre -inches = Im a Pervlous /. ofTotal %of Total Storage Down- Area Inflow Inflow Infiltration& Filtration Treated %of SCM SCM Permeable Pavement Infiltration = 0.00 acre -inches = Impervious Pervious Volume stream SCM Volume Volume ET Outflow Outflow Volume # Name / Location Type of Devke HSG 20,473 6,969 Area Area (cf) #(d) (cf) (cf) (cf) (cf) Utilized 700 Bio'etentiol W IWS I B 20,473 6,969 100% 100% 2154 2188 2188 1931 257 0 60% cf 6969 sf open space entered f of to o Difference = -0.03 acre -inches = -115 cf 20473 s(impervious area enteretl c to 6969 sf total compared impervious total compared to 20473 of total impervious. open space. area. pervious Load Rainfall Data Storm Runoff Fate Summary: Rainfall Volume= 0.94 acre -inches = 3,430 of Runoff Reduction Components: Natural Infiltration & ET = -0.34 acre -inches = -1,242 cf Disconnected Impervious Area - 0.00 acre -inches = 0 cf SCM Infiltration = -0.53 acre -inches = -1,931 cf Permeable Pavement Infiltration = 0.00 acre -inches = 0 cf Green Roof ET = 0.00 acm-inches = 0 cf Post Filtration Discharge = -0.07 acm-inches = -257 cf Total Runoff Reduction = .0.94 acre -inches - -3,430 cf SCM Treatment: Treated SCM Outflow = 0.00 acm-inches = 0 cf Untreated Surface Runoff= 0.00 anm-inchtis - 0 cf Pre -Development Runoff = 0.03. -inch. = 115 cf Difference = -0.03 acre -inches = -115 cf **VOLUME MATCHING ACHIEVED** The Post -Development project area contains 20473 at of built upon area, resulting in an overall density of 74.6%. Warnings: STORM -EZ 8/14/2017 Version 1.4 Stormwater Controls Page 1 of 1 Outlets #3, #7, #14 and outfall at BMP #2 Dia =15" La=10'min. D50 = 0.2' min. = 2.5" Dmax=1.5x2.5"=3.75" Tmin=1.5x3.75"=5.625" I • 1, • � ' I I!l111 ■����■��! -.��IF/AIS 11 Illilllili!!!�1!1�111� �� �� Honor I 1•Ic 1110 1!' �I��N iwvmumwuna Inu �I�1+ I'dilllr 11111111111 III IIIII IIIF �:: 11 N� rll slit I l�sla��i�li,I�11Y�•IlJiel,lll,llllll l�llll� 1 Illn�ll�: � I dliilir ■ii r�r'jl,i�1""illl' i"G �(Ij I'p�I�I 1111111 �i1IIIII p111 1 h�� .i*( IIIII I■ II I M ■�� ,j1Y,C.11lllll� � MIRE! 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Figure 8.06a Design of outlet protection protcction from a round pipe flowing full, minimum tailwater condition (TW < 0.5 diameter) Rev.1193 8.06.3 Outlet #19 Dia = 30" La=16'min. D50=0.5'min. =6" Dmax=1.5x6"=9" Tmin=1.5x9"=13.5" 1 • 1, ru 1 I. IIII�IIIS ,� ■ Ij �{jj�uj��� Initltll IK 21 1111 1 I.ia�l�l�li�l!II�11 .•:r:;iil+!;A .�,I,�i 11!II!1111II !f%!!!!tii Nlllllllllliltllnllili+�;;+,n+Nt,;:N/-1101111111 IIIIIiiiiiiliiliifA11f1SliiiiiilAi"liiii� ii� • 'pMj'iiiilipM I IIn'iiiliil' �� MIIII IIIIII�IMfIII IIjpMp�1jj IIII IMMM 1I !� {nM�III �IiII111 IIS I i �/"��1 Ali •�j �/A�it 111111IIIIII IIIA � Iltlltil�lll l 111!III IIIII �!IIIIIIIIII►IIN I�II� • � � �� ,IRS ANI:Ii1� /111�PP- NIIIII �II q 'III SMII IIIII NIII I III r +i + ,��I!cI/�,II 11 ■ Ill�II;jjj!!I !G!� II III 1 tlll IIIII �;i�'' -i ��r if olio 111 II III II I IIM 1 itlI i1 Ill un Iuu m ■ I n .r,lilL.O,.k. I u■ iii II III 1111111 111 1 � • ,�r� �r NOUN! own 1 1 1 1 11 11 11 111 Discharge 2q Ti :13 Hill II IUII IIII III IIIII IIIA }} it1u111111I u1A IIIA III1tnl111IIIIA II (IIII IIIII IIIII IIIII IIIA 6 llltl 11111 III IIIII IIID n 11111 1111 III IIIII', ,In'1.0e1gvr)I I ll Curves may not be extrapolated. Figure 8.06a Design of outlet protection protection from a round pipe flowing full, minimum tailwater condition (Tw < 0.5 diameter). Rev. 12,93 8.06.3 Post -Development Rain Garden Subcat Reach Pon Link X17010-HydroCAD ModelWORKING - pond 1 Prepared by Microsoft Printed 8/16/2017 HydroCAD® 10.00-16 s/n 09358 @2015 HydroCAD Software Solutions LLC Page 2 Area Listing (selected nodes) Area CN Description (acres) (subcatchment-numbers) 0.720 61 >75% Grass cover, Good, HSG B (1S) 1.410 98 Paved parking, HSG B (1 S) X17010-HydroCAD ModelWORKING - pond 1 Prepared by Microsoft Printed 8/16/2017 HydroCAD® 10.00-16 s/n 09358 @2015 HydroCAD Software Solutions LLC Page 3 Soil Listing (selected nodes) Area Soil Subcatchment (acres) Group Numbers 0.000 HSG A 2.130 HSG B is 0.000 HSG C 0.000 HSG D 0.000 Other X17010-HydroCAD ModelWORKING - pond 1 Prepared by Microsoft Printed 8/16/2017 HydroCAD® 10.00-16 s/n 09358 @2015 HydroCAD Software Solutions LLC Page 4 Ground Covers (selected nodes) HSG -A HSG -B HSG -C HSG -D Other Total Ground Subcatchment (acres) (acres) (acres) (acres) (acres) (acres) Cover Numbers 0.000 0.720 0.000 0.000 0.000 0.720 >75% Grass cover, Good is 0.000 1.410 0.000 0.000 0.000 1.410 Paved parking is X17010-HydroCAD ModelWORKING - pond 1 Charlotte 6 -hr 1 -inch Rainfall=1.00" Prepared by Microsoft Printed 8/16/2017 HydroCADO 10.00-16 s/n 09358 © 2015 HydroCAD Software Solutions LLC Page 5 Summary for Subcatchment 1S: Post -Development Runoff = 0.72 cfs @ 3.19 hrs, Volume= 0.031 af, Depth= 0.17" Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs Charlotte 6 -hr 1 -inch Rainfall=1.00" Area (ac) CN Description 1.410 98 Paved parking, HSG B 0.720 61 >75% Grass cover, Good, HSG B 2.130 85 Weighted Average 0.720 33.80% Pervious Area 1.410 66.20% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment 1S: Post -Development 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 Time (hours) Hydrograph + -I- + � - I- + - I - t -1 - I- _� - I - + -I - �_ + - 0.8 -A 1 1 L_ I L 1 - 1 L 1 1 A I L I �_ _j ■Runoff 0.75 0.72 yrs I I I I I I I I I I I I I I I 17 I I I I I I I 1 1 1 1 1 1 1 1 1 1 1 1 1 i harlotfe 6 -hr l -inch 0.7 0.65 1F T1 1p1 i F� l I .h/�I„ 0.6 -4 - I- + -I - + + - I- + -I - + � - I- + -RUnbff 0.55 1 1 1 L-1 1 1 1 L-1 L L /','ate&2.1130-E1d- I L 1 L A I L 1 L L 0.5 1 1 1 1 Runoff 1Volume=10.031 of 0.45 1 1 1 1 1 1 1 1 1 I �L� SII f I��I 0. 7I�� O 3 0 4 o -1- T -1- 7 7 - 1- T -1- 7 -1 - 1- 7 i ' �T - r 1; Imo' -1- r -1 - 1- 1 1'c�J- -rh 11 M 0.35 -1 + I + + I + I I + I I I 4 I + gy+ 0.3 -1- 1 -1- 1 1 _ I_ 1 _1_ L J _ I_ 1 �++IAA''pp �� _1_ L _I _ I_ _L_I_ L CNr-QJ- 0.25 - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 0.2 0.15 F 1 1 0.1 1- + -1- -1- + -1- �_ + - 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 Time (hours) X17010-HydroCAD ModeIWORKING - pond 1 Charlotte 6 -hr 1 -inch Rainfall=1.00" Prepared by Microsoft Printed 8/16/2017 HydroCAD® 10.00-16 s/n 09358 @2015 HydroCAD Software Solutions LLC Page 6 Summary for Pond 2P: Rain Garden Inflow Area = 2.130 ac, 66.20% Impervious, Inflow Depth = 0.17" for 1 -inch event Inflow = 0.72 cfs @ 3.19 hrs, Volume= 0.031 of Outflow = 0.28 cfs @ 3.15 hrs, Volume= 0.031 af, Atten= 61%, Lag= 0.0 min Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Secondary = 0.28 cfs @ 3.15 hrs, Volume= 0.031 of Routing by Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs Peak Elev= 612.06'@ 3.40 hrs Surf.Area= 4,440 sf Storage= 283 cf Plug -Flow detention time= 8.7 min calculated for 0.031 of (100% of inflow) Center -of -Mass det. time= 8.7 min ( 239.6 - 230.9 ) Volume Invert Avail.Storage Storage Description #1 612.00' 7,899 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 612.00 4,358 0 0 613.00 5,626 4,992 4,992 613.50 6,000 2,907 7,899 Device Routinq Invert Outlet Devices #1 Primary 608.50' 30.0" Round Culvert L= 15.0' RCP, groove end projecting, Ke= 0.200 Inlet/ Outlet Invert= 608.50'/607.96' S=0.0360'/' Cc= 0.900 n= 0.013 Concrete pipe, bends & connections, Flow Area= 4.91 sf #2 Device 1 612.50' 44.0" x 52.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Secondary 610.00' Special & User -Defined Head (feet) 0.00 0.50 1.00 Disch. (cfs) 0.000 0.243 0.280 #4 Primary 613.00' 13.7' long x 5.0' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=612.00' (Free Discharge) T71 =Culvert (Passes 0.00 cfs of 42.25 cfs potential flow) L2=Orifice/Grate ( Controls 0.00 cfs) 4=Broad-Crested Rectangular Weir( Controls 0.00 cfs) Secondary OutFlow Max=0.28 cfs @ 3.15 hrs HW=612.02' (Free Discharge) L3=Special & User -Defined (Custom Controls 0.28 cfs) X17010-HydroCAD ModeIWORKING - pond 1 Charlotte 6 -hr 1 -inch Rainfall=1.00" Prepared by Microsoft Printed 8/16/2017 HydroCADO 10.00-16 s/n 09358 © 2015 HydroCAD Software Solutions LLC Page 7 N 3 0 LL 0.75 0.7 i 0.65 i i 0.6 i 0.55 i i 0.5� i 0.45 i i 0.4o.2a 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 Time (hours) Pond 2P: Rain Garden Hydrograph + + -r+-1——+ + —I — I— + -4 —1 — �- + -i —I — 1— —1 — 1— + -4 —1 — ■ Inflow — — I— I — 1— 4- -4 —1 — 1— � 4 —1 — I— -4 —1 — /� p 1 1P4�T2 04CW ■Outflow ■Primary WW—Ar �, ■ Secondary I P1eA-r=Fev=ra1L2�6'- L— I__ _I 1 I L�p-t I I I I I 1 1 1 1 1 1 1 �I +*L-1 r11 �Rtorage��D3 Cil _______ ------------- I — 1 1 —_ — — — 1 1 —I — II 1 1 1 1 1 1 1 I I I I I I I I I I I 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 Time (hours) X17010-HydroCAD ModelWORKING - pond 1 Charlotte 6 -hr 50 -yr Rainfall=4.92" Prepared by Microsoft Printed 8/16/2017 HydroCADO 10.00-16 s/n 09358 © 2015 HydroCAD Software Solutions LLC Page 8 Summary for Subcatchment 1S: Post -Development Runoff = 13.31 cfs @ 3.15 hrs, Volume= 0.585 af, Depth= 3.29" Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs Charlotte 6 -hr 50 -yr Rainfall=4.92" Area (ac) CN Description 1.410 98 Paved parking, HSG B 0.720 61 >75% Grass cover, Good, HSG B 2.130 85 Weighted Average 0.720 33.80% Pervious Area 1.410 66.20% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 Time (hours) ■Runoff Subcatchment 1S: Post -Development Hydrograph I l tL��tL�IftLI� 14 13.31 cfs 1 L 1 L-1 1 -1 L I L 1 L- 1 1 1 L 1 L 13 - I 1 1 1 1 1 1 1 1 1 1 1 1 1 1Charrlotte6ohr 507yr 12 p ofd—A 1 7 I L 1 F--1 I rt I L I fi 1 r--, Ra1ij q�i� F_ 11 1 � 1 1 � � 1 � 1 � 1 �Runbff Ares=1 1-3fl -aid 10 II I 1 I 1 1 1Runoff1 of 9 Y�rolrumleP0.585 Z.8 1 1i npff 1i p�h�3.�9� 0 7_: 1 1 1 I I I 1 11 i-V-5.0-Mih LL g11 11 1 G 5 5 I L I t 1 f - I t I 1- 1 t 4 1_ 1 I L J 1 1 1 L I L 1 L- 1 1 1 L 1 L 3 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1' 1 1 1 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 rt - I r-1 I I I L I fi 1 �_ I I I L 1 r - 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 Time (hours) ■Runoff X17010-HydroCAD ModeIWORKING - pond 1 Charlotte 6 -hr 50 -yr Rainfall=4.92" Prepared by Microsoft Printed 8/16/2017 HydroCAD® 10.00-16 s/n 09358 @2015 HydroCAD Software Solutions LLC Page 9 Summary for Pond 2P: Rain Garden Inflow Area = 2.130 ac, 66.20% Impervious, Inflow Depth = 3.29" for 50 -yr event Inflow = 13.31 cfs @ 3.15 hrs, Volume= 0.585 of Outflow = 12.40 cfs @ 3.18 hrs, Volume= 0.585 af, Atten= 7%, Lag= 2.0 min Primary = 12.12 cfs @ 3.18 hrs, Volume= 0.435 of Secondary = 0.28 cfs @ 2.25 hrs, Volume= 0.150 of Routing by Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs Peak Elev= 612.88'@ 3.18 hrs Surf.Area= 5,470 sf Storage= 4,311 cf Plug -Flow detention time= 28.3 min calculated for 0.585 of (100% of inflow) Center -of -Mass det. time= 28.3 min ( 237.1 - 208.8 ) Volume Invert Avail.Storage Storage Description #1 612.00' 7,899 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 612.00 4,358 0 0 613.00 5,626 4,992 4,992 613.50 6,000 2,907 7,899 Device Routinq Invert Outlet Devices #1 Primary 608.50' 30.0" Round Culvert L= 15.0' RCP, groove end projecting, Ke= 0.200 Inlet/ Outlet Invert= 608.50'/607.96' S=0.0360'/' Cc= 0.900 n= 0.013 Concrete pipe, bends & connections, Flow Area= 4.91 sf #2 Device 1 612.50' 44.0" x 52.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Secondary 610.00' Special & User -Defined Head (feet) 0.00 0.50 1.00 Disch. (cfs) 0.000 0.243 0.280 #4 Primary 613.00' 13.7' long x 5.0' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 Primary OutFlow Max=11.83 cfs @ 3.18 hrs HW=612.87' (Free Discharge) T71 =Culvert (Passes 11.83 cfs of 52.20 cfs potential flow) L2=Orifice/Grate (Weir Controls 11.83 cfs @ 1.99 fps) 4=Broad-Crested Rectangular Weir( Controls 0.00 cfs) Secondary OutFlow Max=0.28 cfs @ 2.25 hrs HW=612.02' (Free Discharge) L3=Special & User -Defined (Custom Controls 0.28 cfs) X17010-HydroCAD ModeIWORKING - pond 1 Charlotte 6 -hr 50 -yr Rainfall=4.92" Prepared by Microsoft Printed 8/16/2017 HydroCADO 10.00-16 s/n 09358 © 2015 HydroCAD Software Solutions LLC Page 10 Pond 2P: Rain Garden 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105110 115 120 Time (hours) Hydrograph I I I I I I I I I I I I I I I I I I I T-- T�L3 T1 1_� T cfs i —T1 --- t - t13.37 t t ---� — — Llnflolw W f12.40cfs 1 4 1 1 1 1 wWAr v jac Secondary ary 14 12.12 ds 1 � 13 - - - - --- - - 1121 tj"'f e:: -11-c 1 I 1 1�rh1 I 10-1 �1 I I I I I I I I I I I T-1-1-rT-1-1-Trt-1-1-r 9 N i --It�Ift�IIt = 8 - I 1 4- --1 -1- 4 1 1- 4 1 1 � _0 7 _1_ L 1 _1_I_ L- _I_I_ L U. 6 I_ 5 4 I I I - - V I I I I l l - - - - - I I I l l l i 1 1 1 1 - - - - - - - I I V I I I 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105110 115 120 Time (hours) Post -Development Rain Garden Subcat Reach Pon Link pond 2 weir Prepared by Microsoft Printed 8/14/2017 HydroCAD® 10.00-16 s/n 09358 @2015 HydroCAD Software Solutions LLC Page 2 Area Listing (selected nodes) Area CN Description (acres) (subcatchment-numbers) 0.160 61 >75% Grass cover, Good, HSG B (1S) 0.470 98 Paved parking, HSG B (1 S) pond 2 weir Prepared by Microsoft Printed 8/14/2017 HydroCAD® 10.00-16 s/n 09358 @2015 HydroCAD Software Solutions LLC Page 3 Soil Listing (selected nodes) Area Soil Subcatchment (acres) Group Numbers 0.000 HSG A 0.630 HSG B is 0.000 HSG C 0.000 HSG D 0.000 Other pond 2 weir Prepared by Microsoft Printed 8/14/2017 HydroCAD® 10.00-16 s/n 09358 @2015 HydroCAD Software Solutions LLC Page 4 Ground Covers (selected nodes) HSG -A HSG -B HSG -C HSG -D Other Total Ground Subcatchment (acres) (acres) (acres) (acres) (acres) (acres) Cover Numbers 0.000 0.160 0.000 0.000 0.000 0.160 >75% Grass cover, Good is 0.000 0.470 0.000 0.000 0.000 0.470 Paved parking is pond 2 weir Charlotte 6 -hr 1 -inch Rainfall=1.00" Prepared by Microsoft Printed 8/14/2017 HydroCADO 10.00-16 s/n 09358 © 2015 HydroCAD Software Solutions LLC Page 5 Summary for Subcatchment 1S: Post -Development Runoff = 0.40 cfs @ 3.17 hrs, Volume= 0.015 af, Depth= 0.28" Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs Charlotte 6 -hr 1 -inch Rainfall=1.00" Area (ac) CN Description 0.470 98 Paved parking, HSG B 0.160 61 >75% Grass cover, Good, HSG B 0.630 89 Weighted Average 0.160 25.40% Pervious Area 0.470 74.60% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment 1S: Post -Development 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 Time (hours) Hydrograph -4 1 T 1 L 1 T 1 - 1 -4 1 L I - 1 L 1 - 0.44 -4 - I- + -1 - � - I- + -1 - + - - 1- + -I- +_ -I - I- - I- + -1 - -4 ■Runoff 0.42 0.4o yrs t L T L rt L rt L rt arlotte-6—hrl4rtch- 0.38.38 0.36 M_I_.O_ I__� 0.34 I „P__ 0.32 -A I L I L L 1 I L-1 RdnbfAye,67-®.630-ab 0.3 - I T 1 I + 1 � 1 4 1 L1 1 4 II L 11� �--4 0.28 -1 I t 1 I T I L-� I 7tijnofF1`, o1ume—O.15 a H 0.26 v 0'24 -1 1 T I I I I T T I I T I I I L-1 I I I I T I 1� II _1 - II -11 Q�� 'I�U(""f" I""TI"`i" IA's 0.22I 0 02 I I I I I I I I I I I I I I I I I � -Tc� 0- rh i l u 0.18 L 1 LL 1 T I LJ L L I L 1 LA I L 0.16 -�-1-��-I-�-1-��-I-_-1-�-I-I-�-I-�CNr-89- �+HAA'LpL� 0.14 + I L+ I + I +-- --I 1 + I L 1 1 4 I + 1 + 0.12 _r I L I I T I L_1 I rt I L I 1 1 1 L I r- rt 0.1 I 1 0.08 0.06 _ 0.04 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 Time (hours) pond 2 weir Charlotte 6 -hr 1 -inch Rainfall=1.00" Prepared by Microsoft Printed 8/14/2017 HydroCAD® 10.00-16 s/n 09358 @2015 HydroCAD Software Solutions LLC Page 6 Summary for Pond 2P: Rain Garden Inflow Area = 0.630 ac, 74.60% Impervious, Inflow Depth = 0.28" for 1 -inch event Inflow = 0.40 cfs @ 3.17 hrs, Volume= 0.015 of Outflow = 0.08 cfs @ 3.56 hrs, Volume= 0.015 af, Atten= 80%, Lag= 23.5 min Primary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of Secondary = 0.08 cfs @ 3.56 hrs, Volume= 0.015 of Routing by Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs Peak Elev= 609.17'@ 3.56 hrs Surf.Area= 1,799 sf Storage= 287 cf Plug -Flow detention time= 57.8 min calculated for 0.015 of (100% of inflow) Center -of -Mass det. time= 57.6 min ( 281.0 - 223.4 ) Volume Invert Avail.Storage Storage Description #1 609.00' 4,997 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 609.00 1,620 0 0 610.00 2,687 2,154 2,154 611.00 3,000 2,844 4,997 Device Routing Invert Outlet Devices #1 Primary 610.00' 36.0' long x 5.0' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 #2 Secondary 609.00' Special & User -Defined Head (feet) 0.00 0.50 1.00 Disch. (cfs) 0.000 0.243 0.280 Primary OutFlow Max=0.00 cfs @ 0.00 hrs HW=609.00' (Free Discharge) 't--1 =Broad -Crested Rectangular Weir( Controls 0.00 cfs) Secondary OutFlow Max=0.08 cfs @ 3.56 hrs HW=609.17' (Free Discharge) L2=Special & User -Defined (Custom Controls 0.08 cfs) pond 2 weir Charlotte 6 -hr 1 -inch Rainfall=1.00" Prepared by Microsoft Printed 8/14/2017 HydroCADO 10.00-16 s/n 09358 © 2015 HydroCAD Software Solutions LLC Page 7 Pond 2P: Rain Garden 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 Time (hours) Hydrograph T--1—I— —I-1—+--1—— —I-1-4-4-1—I—T-4-1— i T -T —I — r- T -I —I — I— T rt —I — I— T rt —I — ■Inflow �0.40 cfs I I0I* � ■ Outflow ■prima 0.44 Secondary■ 0.42 0.4 iiia II II III�+IT'�Ip IIr 0.38 0.36 i i �i�� T 1 4- I T t I -- I Storage�267 E'iil 0.34 iii fi-1 I I fi-1 1 fi-1 1 fi-1 I I t - -t1 I t - -t1 0.32 i i 1 1 1 1 1 0.3 iii 0.28 ii�� J—I—LIJ—I—L1J—I—LLJ—I—I—LJ-1-1—L-1-1— w 0.26 ifi fi fi�t�IItomI 0.24 i i 0.22 i i J —I — L I J —I— — L J —I — L L J —I — I— L J —1 — 1— L -1 —1 _ 0.2 "0.18 0.16 iii TJ-1-1—TJ-1--TT—I—FTJ—I—I—TT-1-1—T7-1- 0.14 0.08 cry J—_—LJ_I—I_LJ_I_I_LJ_I--LJ_I--L� 0.12 _I — 0.1 0.08 ds I +- 4 1 1 +- -t 1 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 120 Time (hours) pond 2 weir Charlotte 6 -hr 50 -yr Rainfall=4.92" Prepared by Microsoft Printed 8/14/2017 HydroCADO 10.00-16 s/n 09358 © 2015 HydroCAD Software Solutions LLC Page 8 Summary for Subcatchment 1S: Post -Development Runoff = 4.31 cfs @ 3.15 hrs, Volume= 0.194 af, Depth= 3.70" Runoff by SCS TR -20 method, UH=SCS, Weighted -CN, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs Charlotte 6 -hr 50 -yr Rainfall=4.92" Area (ac) CN Description 0.470 98 Paved parking, HSG B 0.160 61 >75% Grass cover, Good, HSG B 0.630 89 Weighted Average 0.160 25.40% Pervious Area 0.470 74.60% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Subcatchment 1S: Post -Development Hydrograph I l l l l l l l i I I I 4.31 cfs - - -I - - - -Charlottes-&[T"0-yr 4 I I Rainfall=4. 21;' IRunbff Area=0.630 ad I- 3 1 1 1 Runoff lVolume=0.194 of Ou;nOff IlDepth=3JO" LL 2 �+I CN;:89 I I I I I I I I I I I I I I 0 5 10 15 iO 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105 110 115 124 ■Runoff pond 2 weir Charlotte 6 -hr 50 -yr Rainfall=4.92" Prepared by Microsoft Printed 8/14/2017 HydroCAD® 10.00-16 s/n 09358 @2015 HydroCAD Software Solutions LLC Page 9 Summary for Pond 2P: Rain Garden Inflow Area = 0.630 ac, 74.60% Impervious, Inflow Depth = 3.70" for 50 -yr event Inflow = 4.31 cfs @ 3.15 hrs, Volume= 0.194 of Outflow = 4.54 cfs @ 3.17 hrs, Volume= 0.194 af, Atten= 0%, Lag= 1.4 min Primary = 4.26 cfs @ 3.17 hrs, Volume= 0.081 of Secondary = 0.28 cfs @ 3.10 hrs, Volume= 0.113 of Routing by Stor-Ind method, Time Span= 0.00-120.00 hrs, dt= 0.05 hrs Peak Elev= 610.14'@ 3.17 hrs Surf.Area= 2,731 sf Storage= 2,535 cf Plug -Flow detention time= 58.7 min calculated for 0.194 of (100% of inflow) Center -of -Mass det. time= 58.9 min ( 264.3 - 205.4 ) Volume Invert Avail.Storage Storage Description #1 609.00' 4,997 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq -ft) (cubic -feet) (cubic -feet) 609.00 1,620 0 0 610.00 2,687 2,154 2,154 611.00 3,000 2,844 4,997 Device Routing Invert Outlet Devices #1 Primary 610.00' 36.0' long x 5.0' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00 2.50 3.00 3.50 4.00 4.50 5.00 5.50 Coef. (English) 2.34 2.50 2.70 2.68 2.68 2.66 2.65 2.65 2.65 2.65 2.67 2.66 2.68 2.70 2.74 2.79 2.88 #2 Secondary 609.00' Special & User -Defined Head (feet) 0.00 0.50 1.00 Disch. (cfs) 0.000 0.243 0.280 Primary OutFlow Max=3.77 cfs @ 3.17 hrs HW=610.13' (Free Discharge) 't--1 =Broad -Crested Rectangular Weir(Weir Controls 3.77 cfs @ 0.83 fps) Secondary OutFlow Max=0.28 cfs @ 3.10 hrs HW=610.01' (Free Discharge) L2=Special & User -Defined (Custom Controls 0.28 cfs) pond 2 weir Charlotte 6 -hr 50 -yr Rainfall=4.92" Prepared by Microsoft Printed 8/14/2017 HydroCAD® 10.00-16 s/n 09358 @2015 HydroCAD Software Solutions LLC Page 10 Pond 2P: Rain Garden 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105110 115 120 Time (hours) Hydrograph +11 +11++11+�11++1++I+ i i 4.54 cfs cfs r �+ O INInflow Prlmlaw y 5 _ _ I _ _I _ I_ _I _ I_ 1 - -- IA_r - 1o•_ - lar- -1 Secondary 425 cis P alk 14= 1 '14'' � I I I I I I I I I 1 1 1' 1 1—T I-•1 1 I I 1 ��+ 1 y,� 1' 1 StbrQ-0et2' 535 d 4 1 -1- I � 7 I I � 7 I I I I I I I I I I I T- -T I I -F -1 I 7 -1 I F I I I I I I I I I I I I y 3 w I -1 -1- I I I I I I I I I + 4 -1 - 1- 1- + -1 - 1- I I I I I I I I I I I I + -4 -1 - 1- + -4 -1- I- + + -1- + 3 I I I I I I I I I I I I I I I I I I I I I I 0 LL 2 I I I I I I I II I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I 1 I I I I I I I I I I I 0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100 105110 115 120 Time (hours)