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HomeMy WebLinkAboutWPO201200003 Certified Engineer's Report 2021-02-26Stormwater Compliance Summary Basins D, E, F for As -built Conditions Charlottesville Albemarle Airport February 26, 2021 Prepared By:_ Delta Airport Consultants 2700 Polo Parkway Midlothian, VA 23113 �ALTH OF Lf ° , , 0 . ° HN D. WRGIE y Lic. No. 049434 A 2021.02.26 rk 14:21:36-05'00' �q4' Stormwater Compliance Summary Basins D, E, F for As -built Conditions Charlottesville Albemarle Airport This document summarizes the changed conditions regarding the Charlottesville -Albemarle Airport Runway Extension program. Basins D, E, and F were designed and approved in 2010 under Albemarle County WPO# 2010-00016. The three basins detain runoff from the earthwork borrow site for the runway extension. These basins were constructed in accordance with the plans and specifications. Two minor changes in the scope of the overall project are noted to the drainage areas contributing to these basins: 1. Due to the nature of the "borrow site" needs for the project, the as -built grades vary slightly from the original design. 2. The final construction of the Airport Rescue and Fire Fighting (ARFF) training pad required concrete cover rather and gravel. The drainage area map and computations have been revised for these changes in as -built conditions. Computations for quantity and quality control have been revised for these conditions from the original design and are attached. The computations confirm that the as -built project meets all stormwater requirements of the original design. Water Quantity Control Compliance (Downstream Channels) Water quantity control compliance was designed at each outfall of the basin (basins were designed to outfall at the property line) with the following requirements (based on Virginia MS-19): • 2-Year Post Rate < 2-Year Existing Rate • 10-Year Post Rate < 2-Year Existing Rate Each basin was designed and modelled, using methodology from TR-55, to reduce the post development peak runoff rate within these parameters. As -built conditions were modelled for the three outfalls (2, 3, 4 correspond to Basins D, E, F respectively). The computations confirmed that the basin outflow rates meet the requirements for quantity control at each outfall. Please see Attachments 1 and 2 for these computations. Water Quality Compliance Water quality compliance was designed in accordance with the "performance -based" water quality design from the Virginia Stormwater Management Handbook (1999). Three bioretention filters were proposed and constructed. Each bioretention filter was designed to receive inflow through sediment forebays, and outflow was directed into the detention basins D, E, and F respectively. The removal rate efficiency required for each drainage area to the biofilters was 65% maximum. The Removal Rate Efficiency Computations have been revised to as -built conditions. Sizing of the biofilters was also recomputed using the as -built conditions. Each bioretention filter design was confirmed to be adequate for size and volume of contributing drainage areas. Please see Attachment 3 for these computations. Attachment 1: Stormwater Outfall Summary (TAB 7 in 2010 Report) Attachment 2: TR-55 Stormwater Routing Model (TAB 13 in 2010 Report) Attachment 3: Water Quality Computations (TAB 14 in 2010 Report) Removal Rate Efficiency Computations BMP Sizing Computations Attachment 4: Drainage Area Map (Asbuilt Conditions) 2/26/2021 2:00 PM Attachment 1 DESIGN STORM SUMMARY - ASBUILT CONDITIONS IMPROVE RUNWAY 21 EXTENDED RUNWAY SAFETY AREA EXTEND RUNWAY 21 - PHASE I B CHAR LOTTESVILLE-ALBEMARLE AIRPORT CHARLOTTESVILLE, VIRGINIA AIP PROJECT NO. PENDING STATE PROJECT NO. PENDING DELTA PROJECT NO. VA 08106 DATE: Feb-21 POINT OF INTEREST #1 Pre (CFS) Post Goals (CFS) Design Post(CFS) Asbuilt (CFS) Pass/ Fail 1 8.63 8.63 8.11 Pass 2 11.00 11.00 10.18 Pass 10 41.76 41.76 36.37 Pass 25 66.64 66.64 57.16 Pass 100 120.31 120.31 101.70 Pass Note: Developed Area is rerouted to a different Point of Interest. Goals meet Existing Conditions. POINT OF INTEREST #2 Pre CFS Post Goals CFS Design Post CFS Asbuilt CFS Pass/ Fail 1 3.26 3.26 1.15 1.08 Pass 2 4.11 4.11 1.22 1.34 Pass 10 15.62 4.11 1.82 1.98 Pass 25 24.96 24.96 2.15 2.24 Pass 100 45.35 45.35 19.52 3.78 Pass POINT OF INTEREST #3 Pre CFS Post Goals CFS Design Post CFS Asbuilt CFS Pass/ Fail 1 2.40 2.40 1.01 0.92 Pass 2 3.13 3.13 1.08 1.17 Pass 10 13.69 3.13 1.61 1.73 Pass 25 22.44 22.44 1.89 1.95 Pass 100 41.63 41.63 2.34 2.26 Pass N:\09008\03 Project Data\Calculations\CHO Design Storm Summary 1/2 2/26/2021 2:00 PM Attachment 1 POINT OF INTEREST #4 Pre CFS Post Goals CFS Design Post CFS Asbuilt CFS Pass/ Fail 1 1.03 1.03 0.33 0.33 Pass 2 1.38 1.38 0.35 0.39 Pass 10 6.54 1.38 0.51 0.55 Pass 25 10.95 10.95 0.66 1.64 Pass 100 20.65 20.65 8.70 8.54 Pass POINT OF INTEREST #5 Pre CFS Post Goals CFS Design Post CFS Asbuilt CFS Pass/ Fail 1 0.37 0.37 0.18 Pass 2 0.50 0.50 0.22 Pass 10 2.34 2.34 0.67 Pass 25 3.89 3.89 1.01 Pass 100 7.34 7.34 1.74 Pass Note: Developed Area is rerouted to a different Point of Interest. Goals meet Existing Conditions. POINT OF INTEREST #6 Pre (CFS) Post Goals (CFS) Design Post(CFS) Asbuilt (CFS) Pass/ Fail 1 3.38 3.38 0.63 Pass 2 4.47 4.47 0.84 Pass 10 18.52 4.47 3.93 Pass 25 30.14 30.14 6.58 Pass 100 55.37 55.37 12.43 Pass POINT OF INTEREST #7 Pre CFS Post Goals CFS Design Post CFS Asbuilt CFS Pass/ Fail 1 272.75 272.75 267.77 Pass 2 322.95 322.95 315.81 Pass 10 913.70 913.70 878.73 Pass 25 1350.82 1350.82 1293.85 Pass 100 2258.46 2258.46 2156.41 Pass DOWNSTREAM DESIGN POINT Pre CFS Post Goals CFS Design Post CFS Asbuilt CFS Pass/ Fail 1 345.12 345.12 322.53 Pass 2 412.13 412.13 383.53 Pass 10 1215.96 1215.96 1109.39 Pass 25 1825.69 1825.69 1689.05 Pass 100 3114.75 3114.75 2952.75 Pass " Virginia Regulatory Storms Note: Basins have been designed to attenuate up to and including the 100-year storm event N:\09008\03 Project Data\Calculations\CHO Design Storm Summary 2/2 Stormwater Management Computations 1-Year Storm Event Node Summary Attachment SIN Element Element Invert Ground/Rim Initial Surcharge Ponded Peak Max HGL Max Min Time of Total Total Time ID Type Elevation (Max) Water Elevation Area Inflow Elevation Surcharge Freeboard Peak Flooded Flooded Elevation Elevation Attained Depth Attained Flooding Volume Attained Occurrence (ft) (ft) (ft) (ft) OF) (cfs) (ft) (ft) (ft)(days hh:mm) (ac-in) (min) 1 Out-02 Outfall 0.00 1.08 0.00 2 Out-03 Outfall 482.00 0.92 482.00 3 Out-04 Outfall 468.50 0.33 468.50 4 BasinD Storage Node 494.00 503.89 0.00 0.00 7.44 495.48 0.00 0.00 5 BasinE Storage Node 486.00 496.05 486.00 0.00 4.44 487.14 0.00 0.00 6 BasinF Storage Node 477.13 486.07 477.00 0.00 4.00 479.08 0.00 0.00 Stormwater Management Computations 1-Year Storm Event Storage Nodes Attachment Storage Node : BasinD Input Data Invert Elevation (ft) ......... Max (Rim) Elevation (ft).. Max (Rim) Offset (ft) ....... Initial Water Elevation (ft) Initial Water Depth (tt) .... Forced Area (fly ............ Evaporation Loss ............ Outflow Weirs Outflow Orifices 494.00 503.89 9.89 0.00 -494.00 0.00 0.00 SIN Element Weir Flap Crest Crest Length Weir Total Discharge ID Type Gate Elevation Offset Height Coefficient (ft) (ft) (ft) 00 1 Weir-03 Trapezoidal No 501.14 7.14 15.70 1.00 3.33 SN Element Orifice Orifice Flap Circular Rectangular Rectangular Orifice Orifice ID Type Shape Gate Orifice Orifice Orifice Invert Coefficient Diameter Height Width Elevation (in) (in) (in) (ft) 1 BASIN D ORIFICE Side CIRCULAR No 6.00 494.00 0.61 Output Summary Results Peak Inflow (cfs)............................................................................. 7.44 Peak Lateral Inflow(cls)................................................................. 7.44 Peak Outflow (cfs)........................................................................... 1.07 Peak Exfillmtion Flow Rate (cfm).................................................... 0.00 Max HGL Elevation Attained (ft) ..................................................... 495.48 Max HGL Depth Attained (ft) ........................................................... 1.48 Average HGL Elevation Attained(ft) ............................................... 494.26 Average HGL Depth Attained (ft).................................................... 0.26 Time of Max HGL Occurrence (days hh:mm).................................. 0 16:03 Total Exhitration Volume (1000-fN)................................................. 0.000 Total Flooded Volume (ao-in) 0 Total Time Flooded (min) 0 Total Retention Time (sec).............................................................. 0.00 Stormwater Management Computations 1-Year Storm Event Storage Node : BasinE Attachment Input Data Invert Elevation (it) ......... Max (Rim) Elevation (it) .. Max (Rim) Offset (it) ....... Initial Water Elevation (it) Initial Water Depth (it).... Ponded Area (ft2) ------------ Evaporation Loss ............ Outflow Weirs Outflow Orifices 486.00 496.05 10.05 486.00 0.00 0.00 0.00 SIN Element Weir Flap Crest Crest Length Weir Total Discharge ID Type Gate Elevation Offset Height Coefficient (ff) (it) (ff) (ff) 1 BASIN E RISER Rectangular No 493.81 7.81 15.70 1.00 3.33 SIN Element Orifice Orifice Flap Circular Rectangular Rectangular Orifice Orifice ID Type Shape Gate Orifice Orifice Orifice Invert Coefficient Diameter Height Width Elevation (in) (in) (in) (ff) 1 BASIN E ORIFICE Side CIRCULAR No 6.00 486.00 0.61 Output Summary Results Peak Inflow (cis)............................................................................. 4.44 Peak Lateral Inflow (cls)................................................................. 4.44 Peak Outflow (cis)........................................................................... 0.91 Peak Exfil ration Flow Rate (cfm).................................................... 0.00 Max HGL Elevation Attained (it) ..................................................... 487.14 Max HGL Depth Attained (h)........................................................... 1.14 Average HGL Elevation Attained(it)............................................... 486.12 Average HGL Depth Attained (ft).................................................... 0.12 Time of Max HGL Occurrence (days hh:mm).................................. 0 13:47 Total Exhitrafion Volume (1000-fN)................................................. 0.000 Total Flooded Volume (ac-in) . 0 Total Time Flooded (min) 0 Total Retention Time (sec).............................................................. 0.00 Stormwater Management Computations 1-Year Storm Event Storage Node : BasinF Attachment Input Data Invert Elevation (it) ......... Max (Rim) Elevation (it) .. Max (Rim) Offset (it) ....... Initial Water Elevation (it) Initial Water Depth (it).... Ponded Area (ft2) ------------ Evaporation Loss ............ Outflow Weirs Outflow Orifices 477.13 486.07 8.94 477.00 -0.13 0.00 0.00 SIN Element Weir Flap Crest Crest Length Weir Total Discharge ID Type Gate Elevation Offset Height Coefficient (ff) (it) (ff) (ff) 1 BASIN F RISER Rectangular No 482.95 5.82 15.70 1.00 3.33 SIN Element Onfice Orifice Flap Circular Rectangular Rectangular Orifice Orifice ID Type Shape Gate Orifice Orifice Orifice Invert Coefficient Diameter Height Width Elevation (in) (in) (in) (ff) 1 BASIN F ORIFICE Side CIRCULAR No 3.00 477.13 0.61 Output Summary Results Peak Inflow (cis)............................................................................. 4.00 Peak Lateral Inflow (cls)................................................................. 4.00 Peak Outflow (cis)........................................................................... 0.33 Peak Efiiliration Flow Rate (cfm).................................................... 0.00 Max HGL Elevation Attained (it) ..................................................... 479.08 Max HGL Depth Attained (h)........................................................... 1.95 Average HGL Elevation Attained(it)............................................... 477.65 Average HGL Depth Attained (ft).................................................... 0.52 Time of Max HGL Occurrence (days hh:mm).................................. 0 17:50 Total Exhitrafion Volume (1000-fN)................................................. 0.000 Total Flooded Volume (ac-in) . 0 Total Time Flooded (min) 0 Total Retention Time (sec).............................................................. 0.00 Stormwater Management Computations 2-Year Storm Event Node Summary Attachment SIN Element Element Invert Ground/Rim Initial Surcharge Ponded Peak Max HGL Max Min Time of Total Total Time ID Type Elevation (Max) Water Elevation Area Inflow Elevation Surcharge Freeboard Peak Flooded Flooded Elevation Elevation Attained Depth Attained Flooding Volume Attained Occurrence (ft) (ft) (ft) (ft) OF) (cfs) (ft) (ft) (ft)(days hh:mm) (ac-in) (min) 1 Out-02 Outfall 0.00 1.34 0.00 2 Out-03 Outfall 482.00 1.17 482.00 3 Out-04 Outfall 468.50 0.39 468.50 4 BasinD Storage Node 494.00 503.89 0.00 0.00 14.35 496.14 0.00 0.00 5 BasinE Storage Node 486.00 496.05 486.00 0.00 7.96 487.68 0.00 0.00 6 BasinF Storage Node 477.13 486.07 477.00 0.00 7.61 479.84 0.00 0.00 Stormwater Management Computations 2-Year Storm Event Storage Nodes Attachment Storage Node : BasinD Input Data Invert Elevation (ft) ......... Max (Rim) Elevation (tt).. Max (Rim) Offset (ft) ....... Initial Water Elevation (ft) Initial Water Depth (tt) .... Forced Area (fly ............ Evaporation Loss ............ Outflow Weirs Outflow Orifices 494.00 503.89 9.89 0.00 -494.00 0.00 0.00 SIN Element Weir Flap Crest Crest Length Weir Total Discharge ID Type Gate Elevation Offset Height Coefficient (ft) (ft) (ft) 00 1 Weir-03 Trapezoidal No 501.14 7.14 15.70 1.00 3.33 SN Element Orifice Orifice Flap Circular Rectangular Rectangular Orifice Orifice ID Type Shape Gate Orifice Orifice Orifice Invert Coefficient Diameter Height Width Elevation (in) (in) (in) (ft) 1 BASIN D ORIFICE Side CIRCULAR No 6.00 494.00 0.61 Output Summary Results Peak Inflow (cfa)............................................................................. 14.35 Peak Lateral Inflow(cls)................................................................. 14.35 Peak Outflow (cfs)........................................................................... 1.33 Peak Exfillmtion Flow Rate (cfm).................................................... 0.00 Max HGL Elevation Attained (ft) ..................................................... 496.14 Max HGL Depth Attained (tt)........................................................... 2.14 Average HGL Elevation Attained(ft) ............................................... 494.49 Average HGL Depth Attained (ft).................................................... 0.49 Time of Max HGL Occurrence (days hh:mm).................................. 0 16:45 Total Exhitration Volume (1000-fN)................................................. 0.000 Total Flooded Volume (ao-in) 0 Total Time Flooded (min) 0 Total Retention Time (sec).............................................................. 0.00 Stormwater Management Computations 2-Year Storm Event Storage Node : BasinE Attachment Input Data Invert Elevation (it) ......... Max (Rim) Elevation (it) .. Max (Rim) Offset (it) ....... Initial Water Elevation (it) Initial Water Depth (it).... Ponded Area (ft2) ------------ Evaporation Loss ............ Outflow Weirs Outflow Orifices 486.00 496.05 10.05 486.00 0.00 0.00 0.00 SIN Element Weir Flap Crest Crest Length Weir Total Discharge ID Type Gate Elevation Offset Height Coefficient (ff) (it) (ff) (ff) 1 BASIN E RISER Rectangular No 493.81 7.81 15.70 1.00 3.33 SIN Element Orifice Orifice Flap Circular Rectangular Rectangular Orifice Orifice ID Type Shape Gate Orifice Orifice Orifice Invert Coefficient Diameter Height Width Elevation (in) (in) (in) (ff) 1 BASIN E ORIFICE Side CIRCULAR No 6.00 486.00 0.61 Output Summary Results Peak Inflow (cis)............................................................................. 7.96 Peak Lateral Inflow (cls)................................................................. 7.96 Peak Outflow (cis)........................................................................... 1.16 Peak Exfil ration Flow Rate (cfm).................................................... 0.00 Max HGL Elevation Attained (it) ..................................................... 487.68 Max HGL Depth Attained (h)........................................................... 1.68 Average HGL Elevation Attained(it)............................................... 486.21 Average HGL Depth Attained (ft).................................................... 0.21 Time of Max HGL Occurrence (days hh:mm).................................. 0 14:16 Total Exhitrafion Volume (1000-fN)................................................. 0.000 Total Flooded Volume (ac-in) . 0 Total Time Flooded (min) 0 Total Retention Time (sec).............................................................. 0.00 Stormwater Management Computations 2-Year Storm Event Storage Node : BasinF Attachment Input Data Invert Elevation (it) ......... Max (Rim) Elevation (it) .. Max (Rim) Offset (it) ....... Initial Water Elevation (it) Initial Water Depth (it).... Ponded Area (ft2) ------------ Evaporation Loss ............ Outflow Weirs Outflow Orifices 477.13 486.07 8.94 477.00 -0.13 0.00 0.00 SIN Element Weir Flap Crest Crest Length Weir Total Discharge ID Type Gate Elevation Offset Height Coefficient (ff) (it) (ff) (ff) 1 BASIN F RISER Rectangular No 482.95 5.82 15.70 1.00 3.33 SIN Element Onfice Orifice Flap Circular Rectangular Rectangular Orifice Orifice ID Type Shape Gate Orifice Orifice Orifice Invert Coefficient Diameter Height Width Elevation (in) (in) (in) (ff) 1 BASIN F ORIFICE Side CIRCULAR No 3.00 477.13 0.61 Output Summary Results Peak Inflow (cis)............................................................................. 7.61 Peak Lateral Inflow (cls)................................................................. 7.61 Peak Outflow (cis)........................................................................... 0.39 Peak Efiiliration Flow Rate (cfm).................................................... 0.00 Max HGL Elevation Attained (it) ..................................................... 479.84 Max HGL Depth Attained (h)........................................................... 2.71 Average HGL Elevation Attained(it)............................................... 478.10 Average HGL Depth Attained (ft).................................................... 0.97 Time of Max HGL Occurrence (days hh:mm).................................. 0 19:14 Total Exhitrafion Volume (1000-fN)................................................. 0.000 Total Flooded Volume (ac-in) . 0 Total Time Flooded (min) 0 Total Retention Time (sec).............................................................. 0.00 Stormwater Management Computations 10-Year Storm Event Node Summary Attachment SIN Element Element Invert Ground/Rim Initial Surcharge Ponded Peak Max HGL Max Min Time of Total Total Time ID Type Elevation (Max) Water Elevation Area Inflow Elevation Surcharge Freeboard Peak Flooded Flooded Elevation Elevation Attained Depth Attained Flooding Volume Attained Occurrence (ft) (ft) (ft) (ft) OF) (cfs) (ft) (ft) (ft)(days hh:mm) (ao-in) (min) 1 Out-02 Outfall 0.00 1.98 0.00 2 Out-03 Outfall 482.00 1.73 482.00 3 Out-04 Outfall 468.50 0.55 468.50 4 BasinD Storage Node 494.00 503.89 0.00 0.00 40.87 498.38 0.00 0.00 5 BasinE Storage Node 486.00 496.05 486.00 0.00 20.75 489.37 0.00 0.00 6 BasinF Storage Node 477.13 486.07 477.00 0.00 21.16 482.35 0.00 0.00 Stormwater Management Computations 10-Year Storm Event Storage Nodes Attachment Storage Node : BasinD Input Data Invert Elevation (ft) ......... Max (Rim) Elevation (ft).. Max (Rim) Offset (ft) ....... Initial Water Elevation (ft) Initial Water Depth (tt) .... Forced Area (fly ............ Evaporation Loss ............ Outflow Weirs Outflow Orifices 494.00 503.89 9.89 0.00 -494.00 0.00 0.00 SIN Element Weir Flap Crest Crest Length Weir Total Discharge ID Type Gate Elevation Offset Height Coefficient (ft) (ft) (ft) 00 1 Weir-03 Trapezoidal No 501.14 7.14 15.70 1.00 3.33 SN Element Orifice Orifice Flap Circular Rectangular Rectangular Orifice Orifice ID Type Shape Gate Orifice Orifice Orifice Invert Coefficient Diameter Height Width Elevation (in) (in) (in) (ft) 1 BASIN D ORIFICE Side CIRCULAR No 6.00 494.00 0.61 Output Summary Results Peak Inflow (cfs)............................................................................. 40.87 Peak Lateral Inflow(cls)................................................................. 40.87 Peak Outflow (cfs)........................................................................... 1.97 Peak Exfillmtion Flow Rate (cfm).................................................... 0.00 Max HGL Elevation Attained (ft) ..................................................... 498.38 Max HGL Depth Attained (tt)........................................................... 4.38 Average HGL Elevation Attained(ft) ............................................... 495.57 Average HGL Depth Attained (ft).................................................... 1.57 Time of Max HGL Occurrence (days hh:mm).................................. 0 18:10 Total Exhitration Volume (1000-fN)................................................. 0.000 Total Flooded Volume (ac-in) 0 Total Time Flooded (min) 0 Total Retention Time (sec).............................................................. 0.00 Stormwater Management Computations 10-Year Storm Event Storage Node : BasinE Attachment Input Data Invert Elevation (it) ......... Max (Rim) Elevation (it) .. Max (Rim) Offset (it) ....... Initial Water Elevation (it) Initial Water Depth (it).... Ponded Area (ft2) ------------ Evaporation Loss ............ Outflow Weirs Outflow Orifices 486.00 496.05 10.05 486.00 0.00 0.00 0.00 SIN Element Weir Flap Crest Crest Length Weir Total Discharge ID Type Gate Elevation Offset Height Coefficient (ff) (it) (ff) (ff) 1 BASIN E RISER Rectangular No 493.81 7.81 15.70 1.00 3.33 SIN Element Onfice Orifice Flap Circular Rectangular Rectangular Orifice Orifice ID Type Shape Gate Orifice Orifice Orifice Invert Coefficient Diameter Height Width Elevation (in) (in) (in) (ff) 1 BASIN E ORIFICE Side CIRCULAR No 6.00 486.00 0.61 Output Summary Results Peak Inflow (cis)............................................................................. 20.75 Peak Lateral Inflow (cls)................................................................. 20.75 Peak Outflow (cis)........................................................................... 1.71 Peak Exfil ration Flow Rate (cfm).................................................... 0.00 Max HGL Elevation Attained (it) ..................................................... 489.37 Max HGL Depth Attained (h)........................................................... 3.37 Average HGL Elevation Attained(it)............................................... 486.65 Average HGL Depth Attained (ft).................................................... 0.65 Time of Max HGL Occurrence (days hh:mm).................................. 0 15:31 Total Exhitrafion Volume (1000-fN)................................................. 0.000 Total Flooded Volume (ac-in) . 0 Total Time Flooded (min) 0 Total Retention Time (sec).............................................................. 0.00 Stormwater Management Computations 10-Year Storm Event Storage Node : BasinF Attachment Input Data Invert Elevation (it) ......... Max (Rim) Elevation (it) .. Max (Rim) Offset (it) ....... Initial Water Elevation (it) Initial Water Depth (it).... Ponded Area (ft2) ------------ Evaporation Loss ............ Outflow Weirs Outflow Orifices 477.13 486.07 8.94 477.00 -0.13 0.00 0.00 SIN Element Weir Flap Crest Crest Length Weir Total Discharge ID Type Gate Elevation Offset Height Coefficient (ff) (it) (ff) (ff) 1 BASIN F RISER Rectangular No 482.95 5.82 15.70 1.00 3.33 SIN Element Onfice Orifice Flap Circular Rectangular Rectangular Orifice Orifice ID Type Shape Gate Orifice Orifice Orifice Invert Coefficient Diameter Height Width Elevation (in) (in) (in) (ff) 1 BASIN F ORIFICE Side CIRCULAR No 3.00 477.13 0.61 Output Summary Results Peak Inflow (cis)............................................................................. 21.16 Peak Lateral Inflow (cls)................................................................. 21.16 Peak Outflow (cis)........................................................................... 0.55 Peak Efiiliration Flow Rate (cfm).................................................... 0.00 Max HGL Elevation Attained (it) ..................................................... 482.35 Max HGL Depth Attained (h)........................................................... 5.22 Average HGL Elevation Attained(it)............................................... 480.08 Average HGL Depth Attained (ft).................................................... 2.95 Time of Max HGL Occurrence (days hh:mm).................................. 0 22:55 Total Exhitrafion Volume (1000-fN)................................................. 0.000 Total Flooded Volume (ac-in) . 0 Total Time Flooded (min) 0 Total Retention Time (sec).............................................................. 0.00 Stormwater Management Computations 25-Year Storm Event Node Summary Attachment SIN Element Element Invert Ground/Rim Initial Surcharge Ponded Peak Max HGL Max Min Time of Total Total Time ID Type Elevation (Max) Water Elevation Area Inflow Elevation Surcharge Freeboard Peak Flooded Flooded Elevation Elevation Attained Depth Attained Flooding Volume Attained Occurrence (ft) (ft) (ft) (ft) OF) (cfs) (ft) (ft) (ft)(days hh:mm) (ao-in) (min) 1 Out-02 Outfall 0.00 2.24 0.00 2 Out-03 Outfall 482.00 1.95 482.00 3 Out-04 Outfall 468.50 1.64 468.50 4 BasinD Storage Node 494.00 503.89 0.00 0.00 75.71 499.54 0.00 0.00 5 BasinE Storage Node 486.00 496.05 486.00 0.00 38.95 490.25 0.00 0.00 6 BasinF Storage Node 477.13 486.07 477.00 0.00 40.81 483.02 0.00 0.00 Stormwater Management Computations 25-Year Storm Event Storage Nodes Attachment Storage Node : BasinD Input Data Invert Elevation (ft) ......... Max (Rim) Elevation (ft).. Max (Rim) Offset (ft) ....... Initial Water Elevation (ft) Initial Water Depth (tt) .... Forced Area (fly ............ Evaporation Loss ............ Outflow Weirs Outflow Orifices 494.00 503.89 9.89 0.00 -494.00 0.00 0.00 SIN Element Weir Flap Crest Crest Length Weir Total Discharge ID Type Gate Elevation Offset Height Coefficient (ft) (ft) (ft) 00 1 Weir-03 Trapezoidal No 501.14 7.14 15.70 1.00 3.33 SN Element Orifice Orifice Flap Circular Rectangular Rectangular Orifice Orifice ID Type Shape Gate Orifice Orifice Orifice Invert Coefficient Diameter Height Width Elevation (in) (in) (in) (ft) 1 BASIN D ORIFICE Side CIRCULAR No 6.00 494.00 0.61 Output Summary Results Peak Inflow (cfs)............................................................................. 75.71 Peak Lateral Inflow(cls)................................................................. 75.71 Peak Outflow (cfs)........................................................................... 2.23 Peak Exfillmtion Flow Rate (cfm).................................................... 0.00 Max HGL Elevation Attained (ft) ..................................................... 499.54 Max HGL Depth Attained (tt)........................................................... 5.54 Average HGL Elevation Attained(ft) ............................................... 496.33 Average HGL Depth Attained (ft).................................................... 2.33 Time of Max HGL Occurrence (days hh:mm).................................. 0 19:30 Total Exhitration Volume (1000-fN)................................................. 0.000 Total Flooded Volume (ac-in) 0 Total Time Flooded (min) 0 Total Retention Time (sec).............................................................. 0.00 Stormwater Management Computations 25-Year Storm Event Storage Node : BasinE Attachment Input Data Invert Elevation (it) ......... Max (Rim) Elevation (it) .. Max (Rim) Offset (it) ....... Initial Water Elevation (it) Initial Water Depth (it).... Ponded Area (ft2) ------------ Evaporation Loss ............ Outflow Weirs Outflow Orifices 486.00 496.05 10.05 486.00 0.00 0.00 0.00 SIN Element Weir Flap Crest Crest Length Weir Total Discharge ID Type Gate Elevation Offset Height Coefficient (ff) (it) (ff) (ff) 1 BASIN E RISER Rectangular No 493.81 7.81 15.70 1.00 3.33 SIN Element Onfice Orifice Flap Circular Rectangular Rectangular Orifice Orifice ID Type Shape Gate Orifice Orifice Orifice Invert Coefficient Diameter Height Width Elevation (in) (in) (in) (ff) 1 BASIN E ORIFICE Side CIRCULAR No 6.00 486.00 0.61 Output Summary Results Peak Inflow (cis)............................................................................. 38.95 Peak Lateral Inflow (cls)................................................................. 38.95 Peak Outflow (cis)........................................................................... 1.93 Peak Exfil ration Flow Rate (cfm).................................................... 0.00 Max HGL Elevation Attained (it) ..................................................... 490.25 Max HGL Depth Attained (h)........................................................... 4.25 Average HGL Elevation Attained(it) ............................................... 486.95 Average HGL Depth Attained (ft).................................................... 0.95 Time of Max HGL Occurrence (days hh:mm).................................. 0 15:01 Total Exhitrafion Volume (1000-fN)................................................. 0.000 Total Flooded Volume (ac-in) . 0 Total Time Flooded (min) 0 Total Retention Time (sec).............................................................. 0.00 Stormwater Management Computations 25-Year Storm Event Storage Node : BasinF Attachment Input Data Invert Elevation (it) ......... Max (Rim) Elevation (it) .. Max (Rim) Offset (it) ....... Initial Water Elevation (it) Initial Water Depth (it).... Ponded Area (ft2) ------------ Evaporation Loss ............ Outflow Weirs Outflow Orifices 477.13 486.07 8.94 477.00 -0.13 0.00 0.00 SIN Element Weir Flap Crest Crest Length Weir Total Discharge ID Type Gate Elevation Offset Height Coefficient (ff) (it) (ff) (ff) 1 BASIN F RISER Rectangular No 482.95 5.82 15.70 1.00 3.33 SIN Element Onfice Orifice Flap Circular Rectangular Rectangular Orifice Orifice ID Type Shape Gate Orifice Orifice Orifice Invert Coefficient Diameter Height Width Elevation (in) (in) (in) (ff) 1 BASIN F ORIFICE Side CIRCULAR No 3.00 477.13 0.61 Output Summary Results Peak Inflow (cis)............................................................................. 40.81 Peak Lateral Inflow (cls)................................................................. 40.81 Peak Outflow (cis)........................................................................... 1.63 Peak Efiiliration Flow Rate (cfm).................................................... 0.00 Max HGL Elevation Attained (it) ..................................................... 483.02 Max HGL Depth Attained (h)........................................................... 5.89 Average HGL Elevation Attained(it)............................................... 480.64 Average HGL Depth Attained (ft).................................................... 3.51 Time of Max HGL Occurrence (days hh:mm).................................. 0 15:59 Total Exhitrafion Volume (1000-fN)................................................. 0.000 Total Flooded Volume (ac-in) . 0 Total Time Flooded (min) 0 Total Retention Time (sec).............................................................. 0.00 Stormwater Management Computations 100-Year Storm Event Node Summary Attachment SIN Element Element Invert Ground/Rim Initial Surcharge Ponded Peak Max HGL Max Min Time of Total Total Time ID Type Elevation (Max) Water Elevation Area Inflow Elevation Surcharge Freeboard Peak Flooded Flooded Elevation Elevation Attained Depth Attained Flooding Volume Attained Occurrence (ft) (ft) (ft) (ft) OF) (cfs) (ft) (ft) (ft)(days hh:mm) (ac-in) (min) 1 Out-02 Outfall 0.00 3.78 0.00 2 Out-03 Outfall 482.00 2.26 482.00 3 Out-04 Outfall 468.50 8.60 468.50 4 BasinD Storage Node 494.00 503.89 0.00 0.00 108.49 501.22 0.00 0.00 5 BasinE Storage Node 486.00 496.05 486.00 0.00 54.93 491.58 0.00 0.00 6 BasinF Storage Node 477.13 486.07 477.00 0.00 58.35 483.24 0.00 0.00 Stormwater Management Computations 100-Year Storm Event Storage Nodes Attachment Storage Node : BasinD Input Data Invert Elevation (ft) ......... Max (Rim) Elevation (tt).. Max (Rim) Offset (ft) ....... Initial Water Elevation (ft) Initial Water Depth (tt) .... Forced Area (fly ............ Evaporation Loss ............ Outflow Weirs Outflow Orifices 494.00 503.89 9.89 0.00 -494.00 0.00 0.00 SIN Element Weir Flap Crest Crest Length Weir Total Discharge ID Type Gate Elevation Offset Height Coefficient (ft) (ft) (ft) 00 1 Weir-03 Trapezoidal No 501.14 7.14 15.70 1.00 3.33 SN Element Orifice Orifice Flap Circular Rectangular Rectangular Orifice Orifice ID Type Shape Gate Orifice Orifice Orifice Invert Coefficient Diameter Height Width Elevation (in) (in) (in) (ft) 1 BASIN D ORIFICE Side CIRCULAR No 6.00 494.00 0.61 Output Summary Results Peak Inflow (cfa)............................................................................. 108.49 Peak Lateral Inflow(cls)................................................................. 108.49 Peak Outflow (cfs)........................................................................... 3.75 Peak Exfillmtion Flow Rate (cfm).................................................... 0.00 Max HGL Elevation Attained (ft) ..................................................... 501.22 Max HGL Depth Attained (tt)........................................................... 7.22 Average HGL Elevation Attained(ft) ............................................... 497.53 Average HGL Depth Attained (ft).................................................... 3.53 Time of Max HGL Occurrence (days hh:mm).................................. 0 17:42 Total Exhitration Volume (1000-fN)................................................. 0.000 Total Flooded Volume (ao-in) 0 Total Time Flooded (min) 0 Total Retention Time (sec).............................................................. 0.00 Stormwater Management Computations 100-Year Storm Event Storage Node : BasinE Attachment Input Data Invert Elevation (it) ......... Max (Rim) Elevation (it) .. Max (Rim) Offset (it) ....... Initial Water Elevation (it) Initial Water Depth (it).... Forced Area (ft2) ------------ Evaporation Loss ............ Outflow Weirs Outflow Orifices 486.00 496.05 10.05 486.00 0.00 0.00 0.00 SIN Element Weir Flap Crest Crest Length Weir Total Discharge ID Type Gate Elevation Offset Height Coefficient (ff) (it) (ff) (ff) 1 BASIN E RISER Rectangular No 493.81 7.81 15.70 1.00 3.33 SIN Element Onfice Orifice Flap Circular Rectangular Rectangular Orifice Orifice ID Type Shape Gate Orifice Orifice Orifice Invert Coefficient Diameter Height Width Elevation (in) (in) (in) (ff) 1 BASIN E ORIFICE Side CIRCULAR No 6.00 486.00 0.61 Output Summary Results Peak Inflow (cis)............................................................................. 54.93 Peak Lateral Inflow (cls)................................................................. 54.93 Peak Outflow (cis)........................................................................... 2.23 Peak Exfil ration Flow Rate (cfm).................................................... 0.00 Max HGL Elevation Attained (it) ..................................................... 491.58 Max HGL Depth Attained (h)........................................................... 5.58 Average HGL Elevation Attained(it)............................................... 487.48 Average HGL Depth Attained (ft).................................................... 1.48 Time of Max HGL Occurrence (days hh:mm).................................. 0 15:38 Total Exhitrafion Volume (1000-fN)................................................. 0.000 Total Flooded Volume (ac-in) . 0 Total Time Flooded (min) 0 Total Retention Time (sec).............................................................. 0.00 Stormwater Management Computations 100-Year Storm Event Storage Node : BasinF Attachment Input Data Invert Elevation (it) ......... Max (Rim) Elevation (it) .. Max (Rim) Offset (it) ....... Initial Water Elevation (it) Initial Water Depth (it).... Forced Area (ft2) ------------ Evaporation Loss ............ Outflow Weirs Outflow Orifices 477.13 486.07 8.94 477.00 -0.13 0.00 0.00 SIN Element Weir Flap Crest Crest Length Weir Total Discharge ID Type Gate Elevation Offset Height Coefficient (ff) (it) (ff) (ff) 1 BASIN F RISER Rectangular No 482.95 5.82 15.70 1.00 3.33 SIN Element Onfice Orifice Flap Circular Rectangular Rectangular Orifice Orifice ID Type Shape Gate Orifice Orifice Orifice Invert Coefficient Diameter Height Width Elevation (in) (in) (in) (ff) 1 BASIN F ORIFICE Side CIRCULAR No 3.00 477.13 0.61 Output Summary Results Peak Inflow (cis)............................................................................. 58.35 Peak Lateral Inflow (cls)................................................................. 58.35 Peak Out"m (cis)........................................................................... 8.56 Peak Efiiliration Flow Rate (cfm).................................................... 0.00 Max HGL Elevation Attained (it) ..................................................... 483.24 Max HGL Depth Attained (h)........................................................... 6.11 Average HGL Elevation Attained(it) ............................................... 480.69 Average HGL Depth Attained (ft).................................................... 3.56 Time of Max HGL Occurrence (days hh:mm).................................. 0 12:47 Total Exhitrafion Volume (1000-fN)................................................. 0.000 Total Flooded Volume (ac-in) . 0 Total Time Flooded (min) 0 Total Retention Time (sec).............................................................. 0.00 Attachment 2/4/2021 2:13 PM REMOVAL RATE CALCULATIONS - ASBUILT CONDITIONS IMPROVE RUNWAY 21 EXTENDED RUNWAY SAFETY AREA EXTEND RUNWAY 21 - PHASE IB CHARLOTTESVILLE-ALBEMARLE AIRPORT CHARLOTTESVILLE, VIRGINIA AIP PROJECT NO. PENDING STATE PROJECT NO. PENDING DELTA PROJECT NO. VA 08106 DATE: Feb-21 Lpre = 8.77*(.05+.9*lpre)*Cw*A Lpost = 8.77*(.05+.9*lpost)*Cw*A RR = (Lpost-Lpre)*100/Lpost Cw (Drinking Watershed) = 0.35 TOTAL WATERSHED Impervious Cover: Pre -development Forest 0 398.53 0.00 Grass 8 207.40 16.59 Gravel 100 6.77 6.77 Pavement 100 20.52 20.52 Residential 10 597.32 59.73 Total = 1230.54 103.61 Lpre = 475.10 Ipre(watershed) = 0.08 Impervious Cover: Post -development Forest 0 317.71 0.00 Grass 8 279.30 22.34 Gravel 100 7.44 7.44 Pavement 100 31.05 31.05 Residential 10 597.32 59.73 Total = 1232.82 120.57 Lpost = 522.28 (post (watershed) = 0.10 RR = 9.0% N:\09008\03 Project Data\Calculations\CHO Removal Rates Asbuilt Page 1 Attachment 2/4/2021 2:13 PM REMOVAL RATE CALCULATIONS - ASBUILT CONDITIONS IMPROVE RUNWAY 21 EXTENDED RUNWAY SAFETY AREA EXTEND RUNWAY 21 - PHASE IB CHARLOTTESVILLE-ALBEMARLE AIRPORT CHARLOTTESVILLE, VIRGINIA AIP PROJECT NO. PENDING STATE PROJECT NO. PENDING DELTA PROJECT NO. VA 08106 DATE: Feb-21 Lpre = 8.77*(.05+.9*lpre)*Cw*A Lpost = 8.77*(.05+.9*lpost)*Cw*A RR = (1-post-Lpre)*100/1-post Cw (Drinking Watershed) = 0.35 PROJECT DEVELOPMENT SITE Impervious Cover: Pre -development Land Use Equivalent % Impervious Cover Contributing Area, A ac Impervious Area, A(imp)( ac Forest 0 28.96 0.00 Grass 8 9.56 0.76 Gravel 100 0.62 0.62 Pavement 100 0.00 0.00 Total = 39.14 1.38 Lpre = 9.83 Ipre = 0.04 Impervious Cover: Post -development Land Use Equivalent % Impervious Cover Contributing Area, A ac Impervious Area, A(Imp)( ac Forest 0 0.60 0.00 Grass 8 52.06 4.16 Gravel 100 0.89 0.89 Pavement 100 0.91 0.91 Total = 54.46 5.96 Lpost = 24.84 (post = 0.11 RR = 60.4% Compliant c 65.0 % Original RR = 58.3% , N:\09008\03 Project Data\Calculations\CHO Removal Rates Asbuilt Page 2 Attachment 2/4/2021 2:13 PM REMOVAL RATE CALCULATIONS - ASBUILT CONDITIONS IMPROVE RUNWAY 21 EXTENDED RUNWAY SAFETY AREA EXTEND RUNWAY 21 - PHASE IB CHARLOTTESVILLE-ALBEMARLE AIRPORT CHARLOTTESVILLE, VIRGINIA AIP PROJECT NO. PENDING STATE PROJECT NO. PENDING DELTA PROJECT NO. VA 08106 DATE: Fat1-21 Lpre = 8.77*(.05+.9*lpre)*Cw*A Lpost = 8.77*(.05+.9*lpost)*Cw*A RR = (1-post-Lpre)*100/1-post Cw (Drinking Watershed) = 0.35 Basin D - Area 2 Impervious Cover: Pre -development Land Use Equivalent % Impervious Cover Contributing Area, A ac Impervious Area, A(Imp)( ac Forest 0 9.92 0.00 Grass 8 6.09 0.49 Gravel 100 0.62 0.62 Pavement 100 0.00 0.00 Total = 16.63 1.11 Lpre = 5.61 Ipre = 0.07 Impervious Cover: Post -development Land Use Equivalent % Impervious Cover Contributing Area, A ac Impervious Area, A(Imp)( ac Forest 0 0.00 0.00 Grass 8 29.16 2.33 Gravel 100 0.20 0.20 Pavement 100 0.00 0.00 Total = 29.36 2.53 Lpost = 11.50 (post = 0.09 RR = 51.2% Compliant c 65.0 % Original RR = 51.1% N:\09008\03 Project Data\Calculations\CHO Removal Rates Asbuilt Page 3 Attachment 2/4/2021 2:13 PM REMOVAL RATE CALCULATIONS - ASBUILT CONDITIONS IMPROVE RUNWAY 21 EXTENDED RUNWAY SAFETY AREA EXTEND RUNWAY 21 - PHASE IB CHARLOTTESVILLE-ALBEMARLE AIRPORT CHARLOTTESVILLE, VIRGINIA AIP PROJECT NO. PENDING STATE PROJECT NO. PENDING DELTA PROJECT NO. VA 08106 DATE: Fab-21 Lpre = 8.77*(.05+.9*lpre)*Cw*A Lpost = 8.77*(.05+.9*lpost)*Cw*A RR = (1-post-Lpre)*100/1-post Cw (Drinking Watershed) = 0.35 Basin E - Area 3 Impervious Cover: Pre -development Land Use Equivalent % Impervious Cover Contributing Area, A ac Impervious Area, A(Imp)( ac Forest 0 12.63 0.00 Grass 8 3.47 0.28 Gravel 100 0.00 0.00 Pavement 100 0.00 0.00 Total = 16.10 0.28 Lpre = 3.24 Ipre = 0.02 Impervious Cover: Post -development Land Use Equivalent % Impervious Cover Contributing Area, A ac Impervious Area, A(imp)( ac Forest 0 0.00 0.00 Grass 8 11.42 0.91 Gravel 100 0.69 0.69 Pavement 100 0.91 0.91 Total = 13.02 2.51 Lpost = 8.94 (post = 0.19 RR = 63.8% Compliant c 65.0 % Original RR = 55.5% _ N:\09008\03 Project Data\Calculations\CHO Removal Rates Asbuilt Page 4 Attachment 2/4/2021 2:13 PM REMOVAL RATE CALCULATIONS - ASBUILT CONDITIONS IMPROVE RUNWAY 21 EXTENDED RUNWAY SAFETY AREA EXTEND RUNWAY 21 - PHASE IB CHARLOTTESVILLE-ALBEMARLE AIRPORT CHARLOTTESVILLE, VIRGINIA AIP PROJECT NO. PENDING STATE PROJECT NO. PENDING DELTA PROJECT NO. VA 08106 DATE: Feb-21 Basin F - Area 4 Lpre = 8.77*(.05+.9*lpre)*Cw*A Lpost = 8.77*(.05+.9*lpost)*Cw*A RR = (1-post-Lpre)*100/1-post Cw (Drinking Watershed) = 0.35 Impervious Cover: Pre -development Land Use Equivalent % Impervious Cover Contributing Area, A ac Impervious Area Forest 0 6.41 0.00 Grass 8 0.00 0.00 Gravel 100 0.00 0.00 Pavement 100 0.00 0.00 Total = 6.41 0.00 Lpre = 0.00 Ipre = 0.00 *' Note: Because no impervious cover is existing in this area, the average watershed cover is used, *' Please see VSMH reference attached. Lpre = 2.40 Ipre(watershed) = 0.08 Impervious Cover: Post -development Land Use Equivalent % Impervious Cover Contributing Area, A ac Impervious Area Forest 0 0.60 0.00 Grass 8 11.48 0.92 Gravel 100 0.00 0.00 Pavement 100 0.00 0.00 Total = 12.08 0.92 Lpost = 4.39 (post = 0.08 RR = 45.3 % Compliant < 65.0 % Original RR = 50.3% N:\09008\03 Project Data\Calculations\CHO Removal Rates Asbuilt Page 5 Attachment 2/4/2021 2:11 PM Water Quality Volume Computations - ASBUILT CONDTIONS IMPROVE RUNWAY 21 EXTENDED RUNWAY SAFETY AREA EXTEND RUNWAY 21 - PHASE I B CHARLOTTESVILLE-ALBEMARLE AIRPORT CHARLOTTESVILLE, VIRGINIA DELTA PROJECT NO. VA 08106 DATE: Jun-09 Vwq = Water Quality Volume Vwq = Impervious area x 1 in. / 12 in. BASIN D Gravel 100 0.20 0.20 Pavement 100 0.00 0.00 Forest 0 0.00 0.00 Total = 2.53 Vwq = 0.21 ac-ft BASIN E Gravel 100 0.69 0.69 Pavement 100 0.91 0.91 Forest 0 0.00 0.00 Total = 2.51 Vwq = 0.21 ac-ft BASIN F Gravel 100 0.00 0.00 Pavement 100 0.00 0.00 Forest 0 0.60 0.00 Total = 0.92 Vwq = 0.08 ac-ft N:\09008\03 Project Data\Calculations\CHO Water Quality Asbuilt Page 1 2/4/2021 2:11 PM Attachment IMPROVE RUNWAY 21 EXTENDED RUNWAY SAFETY AREA EXTEND RUNWAY 21 - PHASE IB CHARLOTTESVILLE-ALBEMARLE AIRPORT CHARLOTTESVILLE, VIRGINIA DELTA PROJECT NO. VA 08106 DATE: February 2, 2009 Basin D Forebay Volume Vwq 0.21 AC x FT Elevation of Vwq = 502.37 FT Elev Area (AC) Incr. Vol. AC x FT Vol. AC x FT) Water Quality Elev. 500 0.02 501 0.08 0.05 0.05 502 0.12 0.10 0.15 503 0.21 0.17 0.32 502.37 Basin E Forebay Volume Vwq 0.21 AC x FT Elevation of Vwq = 0.00 FT Elev Area AC Incr. Vol. Vol. AC x Water Qualit Elev. 493 0.02 494 0.08 0.05 0.05 495 0.17 0.13 0.18 Basin F Forebay Volume Vwq 0.08 AC x FT Elevation of Vwq = 501.27 FT Elev Area AC Incr. Vol. Vol. AC x Water Quality Elev. 500 0.02 501 0.08 0.05 0.05 502 0.12 0.10 0.15 501.27 503 0.21 0.17 0.32 N:\09008\03 Project Data\Calculations\CHO Water Quality Asbuilt 2/5 jdb Page 3 Attachment 3 2/4/2021 BIOFILTER BASIN DESIGN - ASBUILT CONDITIONS Charlottesville -Albemarle Airport Charlottesville, Virginia Delta Project No. VA 08106 Basin D Target Phosphorus Removal Efficiency = 651/6 Treatment Volume = 1"per contributing impervious acre Basin Surface Area = 5.0% (min) of contributing impervious area Ponding Depth = I'(max) Bfofilter Dimensions Area of Contributing Impervious Area= 2.53 ACRES 'See Water Quality Calculations Basin Surface Area Required = 0.13 ACRES Basin Volume Required = 021 AC -FT Basin Surface Area Provided = 0.20 ACRES Provided > Required Basin Volume Provided = 0.22 AC -FT Plantina Desian Planting Density = 400 stems/acre Plants Required = 80 Plants Provided = 100 Tree to Shurb Ratio = 31 Shrubs = 60 Trees = 20 Due to FAA restrictions on planting frees in airside development, required trees will be replaced with 2 shrubs each. Final Number of Shrubs Required= 100 FINAL PLANTING SCHEDULE COMMON NAME SCIENTIFIC NAME NUMBER PLANTING HIEGHT (FT) MATURE HEIGHT (ft) SYMBOL BRISTLY LOCUST Robinia fertilis 16 3-4 OR 18"-24" SPREAD 5-7 BL HORIZONTAL JUNIPER Juniperus spp 20 3-4 OR 18"-24"SPREAD 1-2 HJ SWEET FERN Comptonia peregrina 16 3A OR 18"-24" SPREAD 2-4 SF WINGED EUONYMOUS Euonymus alatus 16 3A OR 18"-24" SPREAD 5-7 WE COMMON JUNIPER Juniperus communis "cempressa" 16 3A OR 18"-24" SPREAD 3-6 CJ WITCH HAZEL Hamamelis virginiana 16 3A OR 18"-24" SPREAD 4-6 WH ENGLISH IVY Hedera helix GROUND COVER Note: Shrubs shall be planted at a maximum of 1Z apart. Ground cover shall be planted approximately 2' apart and away from shrubs. N:\09008\03 Project Data\Calculations\CHO Water Quality Asbuilt jdb Page 4 Attachment 3 2/4/2021 BIOFILTER BASIN DESIGN - ASBUILT CONDITIONS Charlottesville -Albemarle Airport Charlottesville, Virginia Delta Project No. VA 08106 Basin E Target Phosphorus Removal Efficiency = 65% Treatment Volume = 1" per contributing impervious acre Basin Surface Area = 5.0% (min) of contributing impervious area Ponding Depth = V (max) Biofllter Dimensions Area of Contributing Impervious Area= 2.51 ACRES 'See Water Quality Calculations Basin Surface Area Required = 0.13 ACRES Basin Volume Required = 0.21 AC -FT Basin Surface Area Provided = 0.14 ACRES Provided > Required Basin Volume Provided = 0.21 AC -FT Plantina Design Planting Density = 400 stems/acre Plants Required = 56 Plants Provided = 70 Tree to Shum Ratio = 3:1 Shrubs = 42 Trees = 14 Due to FAA restrictions on planting trees in airside development, required trees will be replaced with 2 shrubs each. Final Number of Shrubs Required= 70 COMMON NAME SCIENTIFIC NAME NUMBER PLANTING HIEGHT MATURE HEIGHT SYMBOL BRISTLY LOCUST Robinia fertilis 11 3-4 OR 18"-24" SPREAD 5-7 BL HORIZONTAL JUNIPER Juniperuss 15 3-4 OR 18"-24"SPREAD 1-2 HJ SWEET FERN Com Ionia peregrina 11 3-4 OR 18"-24" SPREAD 2-4 SF WINGED EUONYMOUS Euonymus alatus 11 3-4 OR 18"-24"SPREAD 5-7 WE COMMON JUNIPER Juniperus communis "com ressa" 11 3-4 OR 18"-24" SPREAD 3-6 CJ WITCH HAZEL Hamamelis viriniana 11 3-4 OR 18"-24"SPREAD 4-6 WH ENGLISH IVY Hedera helix GROUND COVER Note: Shrubs shall be planted at a maximum of 12' apart. Ground cover shall be planted approximately 2' apart and away from shrubs. N:\09008\03 Project Data\Calculations\CHO Water Quality Asbuilt jdb Page 5 Attachment 3 2/4/2021 BIOFILTER BASIN DESIGN - ASBUILT CONDITIONS Charlottesville -Albemarle Airport Charlottesville, Virginia Delta Project No. VA 08106 Basin F Target Phosphorus Removal Efficiency = 651/6 Treatment Volume = 1"per contributing impervious acre Basin Surface Area = 5.0% (min) of contributing impervious area Ponding Depth = I'(max) Bfofilter Dimensions Area of Contributing Impervious Area= 0.92 ACRES 'See Water Quality Calculations Basin Surface Area Required = 0.05 ACRES Basin Volume Required = 0.08 AC -FT Basin Surface Area Provided = 0.11 ACRES Provided > Required Basin Volume Provided = 0.13 AC -FT Plantina Desian Planting Density = 400 stems/acre Plants Required = 44 Plants Provided = 55 Tree to Shurb Ratio = 31 Shrubs = 33 Trees = 11 Due to FAA restrictions on planting frees in airside development, required trees will be replaced with 2 shrubs each. Final Number of Shrubs Required= 55 FINAL PLANTING SCHEDULE COMMON NAME SCIENTIFIC NAME NUMBER PLANTING HIEGHT (FT) MATURE HEIGHT (U) SYMBOL BRISTLY LOCUST Robinia fertilis 9 3-4 OR 18"-24" SPREAD 5-7 BL HORIZONTAL JUNIPER Juniperus spp 10 3-4 OR 18"-24"SPREAD 1-2 HJ SWEET FERN Comptonia peregrina 9 3-4 OR 18"-24" SPREAD 2-4 SF WINGED EUONYMOUS Euonymus alatus 9 3-4 OR 18"-24" SPREAD 5-7 WE COMMON JUNIPER Juniperus communis "cempressa" 9 3-4 OR 18"-24" SPREAD 3-6 CJ WITCH HAZEL Hamamelis virginiana 9 3-4 OR 18"-24"SPREAD 4-6 WH ENGLISH IVY Hedera helix GROUND COVER Note: Shrubs shall be planted at a maximum of 1Z apart. Ground cover shall be planted approximately 2' apart and away from shrubs. N:\09008\03 Project Data\Calculations\CHO Water Quality Asbuilt Attachment 4 J L `m 0 0. 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I I ( BASIN-C / / / / / /(;j) \ Wt `T$• \: 558 \SS3 \ 6' V t` l / l / __6051 �d�r If 562 554 BASIN-B 5�- f Sfie 0 570 g88 533 558 5 7G- 573-powwwl .4 C O o o- o 0 .0 1` 0� -- .Iii` / / .Q ' ° \''`, \ �Q�(�'9 L G p M .i ` / C/ �e00 O /_ O \y ��q \� / / //A// / \ _ / / // 5 ' 4 • . =o o C �� C / a =e \ �2� \ 0 0 . _\ -------------------- 'o-- - c - --- _ _ - _ - _ - - - - - - �75- - - - - - - - - - - - - - - �r�80- - - - _ �� - - _ _ - - _ _ _ _ _ - -535- \ \ \ \ e • \'' \ \ / / / / / / / I J /-/ / / /� / - -� �- ------ 09 65- __ _ 1 -,I I-�1E7�\ _ _ _ _ _ - / \ + oo \ o �So- ano - zo I! _ - 605- ------------=-605------ T f I 1\\ r - -- I / SCALE:}'=100' / F E 1 1 1 __� % OHST�FIG'T/6/��� ACREAGE - ES&C STAGE C ACREAGE - ULTIMATE CONDITIONS DESCRIPTION CN AREA LABEL DESCRIPTION CN AREA LABEL 1 2 2A 3 3A 4 4A SA 6 7 7A 8 9' 1 2 2A 3 3A 4 4A 5A 6 7 7A 8 9' GRASS, GOOD CONDITION 61 10.30 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 68.12 1.10 75.97 66.01 GRASS, GOOD CONDITION 61 10.30 29.16 0.24 11.42 0.12 11.48 0.09 0.36 3.83 68.12 1.10 75.97 66.01 IMPERVIOUS, GRAVEL 85 0.49 0.20 0.00 1.00 0.00 0.10 0.00 0.00 0.00 2.83 0.00 1.29 1.53 IMPERVIOUS, GRAVEL 85 0.49 0.20 0.00 0.69 0.00 0.00 0.00 0.00 0.00 2.83 0.00 1.29 1.53 IMPERVIOUS, PAVEMENT 98 1.11 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 12.28 0.00 1.33 16.33 IMPERVIOUS, PAVEMENT 98 1.11 0.00 0.00 0.91 0.00 0.00 0.00 0.00 0.00 12.28 0.00 1.33 16.33 FOREST, GOOD CONDITION 55 18.50 1 0.00 0.00 1 0.00 1 0.00 0.00 0.00 1 0.00 0.00 144.02 109.00 39.80 6.39 1 FOREST, GOOD CONDITION 55 18.50 0.00 0.00 0.00 0.00 0.60 1 0.00 0.00 0.00 144.02 109.00 39.80 6.39 RESIDENTIAL, 1 ACRE LOTS 68 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 541.75 55.57 0.00 0.00 RESIDENTIAL, 1 ACRE LOTS 68 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 541.75 55.57 0.00 0.00 DISTURBED SOIL 86 0.00 29.06 0.24 11.64 0.12 12.46 0.09 0.36 3.83 0.00 0.00 0.00 0.00 TOTAL ACREAGE= 30.40 29.36 0.24 13.02 0.12 12.08 0.09 0.36 3.83 769.00 165.67 118.39 90.26 WEIGHTED CN VALUES = S9 61 61 65 61 61 61 61 55 65 59 60 68 TOTAL ACREAGE = 30.40 29.26 0.24 12.64 0.12 12.56 0.09 0.36 3.83 769.00 165.67 118.39 90.26 TIME OF CONCENTRATION = 30 2S 8 20 8 19 S 17 25 55 54 38 NA WEIGHTED CN VALUES = 59 86 86 86 86 86 86 86 86 65 59 60 68 "SHALL BE MODELED AS A HYDROGRAPH FROM PREVIOUSLY APPROVED MODELS IN PHASE 1A OF THIS PROJECT (WPO 200800059) TIME OF CONCENTRATION = 30 1S 8 10 8 9 5 17 S S5 54 38 NA HYDROLOGIC SOIL GROUP WITHIN DRAINAGE AREAS BOUNDARY 4C ASHE LOAM, 7 TO 15% SLOPES, RATING B 36D HAYESVILLE LOAM, 15 TO 25% SLOPES, RATING B 4D ASHE LOAM, 15 TO 25% SLOPES, RATING B 37B3 HAYESVILLE CLAY LOAM, 2 TO 7% SLOPES, SEVERELY ERODED, RATING B 4E ASHE LOAM, 25 TO 45% SLOPES, RATING B 37C3 HAYESVILLE CLAY LOAM, 7 TO 15% SLOPES, SEVERELY ERODED, RATING B 14B CHESTER LOAM, 2 TO 7% SLOPES, RATING B 37133 HAYESVILLE CLAY LOAM, 15 TO 25% SLOPES, SEVERELY ERODED, RATING B 14C CHESTER LOAM, 7 TO 15% SLOPES, RATING B 56B MEADOWVILLE LOAM, 2 TO 7% SLOPES, RATING B 14D CHESTER LOAM, 15 TO 25% SLOPES, RATING B 65B LOUISBURG SANDY LOAM, 2 TO 7% SLOPES, RATING B 19B CULLEN LOAM, 2 TO 7% SLOPES, RATING C 77 RIVERVIEW-CHEWACLA COMPLEX, RATING B 20C3 CULLEN CLAY LOAM, 15 TO 25% SLOPES, SEVERELY ERODED, RATING C 83 TOCCOA FINE SANDY LOAM, RATING B 36B HAYESVILLE LOAM, 2 TO 7% SLOPES, RATING B 88 UDORTHENTS, LOAMY 36C HAYESVILLE LOAM, 7 TO 15% SLOPES, RATING B W WATER NOTE: HYDROLOGIC SOIL RATING C DESIGNATED AS SHOWN. ALL OTHER AREAS ARE RATING B. - LEGEND DRAINAGE AREA BOUNDARY LINE OF OVERLAND FLOW PATH - - + - - LINE OF SHALLOW FLOW PATH LINE OF CHANNELIZED FLOW PATH LINE OF FLOW OUTFALL LINE OF FLOW PATH SEPARATOR TC O TIME OF CONCENTRATION NUMBER QPOINT OF INTEREST IMPERVIOUS -ASPHALT IMPERVIOUS -GRAVEL POST DEVELOPMENT INSET "A" (BORROW AREA) CHARLOTTESVILLE-ALBEMARLE AIRPORT CHARLOTTESVILLE, VIRGINIA DELTA AIRPORT EXHIBIT 40&�h lowmmmmmmmmw CONSULTANTS, INC. D 3A www.deltaoirport.com DRAWN BY: RWW ISCALE: 1"=100' CHECKED BY: JDB DATE: MARCH 2010