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HomeMy WebLinkAboutWPO201900040 Calculations 2019-07-02Yancey Lumber Yard VSMP ALBEMARLE COUNTY, VIRGINIA V SMP PLAN DESIGN CALCULATIONS & NARRATIVE JULY 1, 2019 TIMMONS GROUP YOUR VISION ACHiEVEO THROUGH OURS. Prepared by: Jonathan Showalter, PE Timmons Group 608 Preston Avenue, Suite 200 Charlottesville, VA 22903 434.327.1681 �.1TH.%N \i. SHOWLTGR y I.ic. No. 0402057151 ��O 7/1/19 �4� Table of Contents Section Title Project Narrative Pre- and Post -Developed HydroCAD Calculations Virginia Runoff Reduction Method ReDevelopment Worksheet Project Narrative: This project includes the grading of an asphalt roadway adjacent to an existing retaining wall to ensure grades are within the design height limits of the wall. The limits of disturbance are 0.55 acres. Water Quality: Currently there exists 0.00 acres of forest, 0.02 acres of managed turf and 0.53 acres of impervious cover within the site limits. In the proposed condition, there will be 0.00 acres of forest, 0.08 acres of managed turf and 0.47 acres of impervious cover. Per the Virginia Runoff Reduction Redevelopment Spreadsheet, the required removal is 0.03 lb/yr. This removal will be achieved with the purchase of offsite nutrient credits from a DEQ approved credit bank. Water Quantity: No new impervious surface is being added as part of this project. Pre -developed flows will be maintained or reduced. See plan sheet C6.1 and HydroCAD Routing Calculations. Pre -Developed Area Subcat Reach on Link (2S Post -Developed Area Yancey Pre Post Type 11 24-hr 1 Year Rainfall=3.05" Prepared by Timmons Group Printed 6/25/2019 HydroCAD® 10.00-20 s/n 10074 © 2017 HydroCAD Software Solutions LLC Page 2 Summary for Subcatchment 1 S: Pre -Developed Area Runoff = 2.24 cfs @ 11.96 hrs, Volume= 0.112 af, Depth> 2.43" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 1Year Rainfall=3.05" Area (ac) CN Description 0.529 98 Paved parking, HSG B 0.024 61 >75% Grass cover, Good, HSG B 0.553 96 Weighted Average 0.024 4.34% Pervious Area 0.529 95.66% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, N C1 3 0 LL Subcatchment 1 S: Pre -Developed Area Hydrograph 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) ❑ Runoff Yancey Pre Post Type/1 24-hr 1 Year Rainfall=3.05" Prepared by Timmons Group Printed 6/25/2019 HydroCAD® 10.00-20 s/n 10074 © 2017 HydroCAD Software Solutions LLC Page 3 Hydrograph for Subcatchment 1S: Pre -Developed Area Time Precip. Excess Runoff (hours) (inches) (inches) (cfs) 5.00 0.19 0.02 0.01 5.25 0.20 0.03 0.01 5.50 0.22 0.03 0.01 5.75 0.23 0.04 0.01 6.00 0.24 0.04 0.01 6.25 0.26 0.05 0.02 6.50 0.27 0.06 0.02 6.75 0.29 0.07 0.02 7.00 0.30 0.08 0.02 7.25 0.32 0.08 0.02 7.50 0.33 0.09 0.02 7.75 0.35 0.10 0.02 8.00 0.37 0.11 0.02 8.25 0.38 0.13 0.03 8.50 0.40 0.14 0.03 8.75 0.42 0.15 0.03 9.00 0.45 0.17 0.04 9.25 0.47 0.19 0.04 9.50 0.50 0.21 0.04 9.75 0.52 0.23 0.04 10.00 0.55 0.25 0.05 10.25 0.58 0.27 0.06 10.50 0.62 0.30 0.07 10.75 0.67 0.34 0.08 11.00 0.72 0.38 0.10 11.25 0.78 0.44 0.13 11.50 0.86 0.51 0.16 11.75 1.18 0.80 0.76 12.00 2.02 1.60 2.07 12.25 2.15 1.72 0.28 12.50 2.24 1.81 0.18 12.75 2.30 1.87 0.13 13.00 2.35 1.92 0.11 13.25 2.40 1.96 0.09 13.50 2.44 2.00 0.08 13.75 2.47 2.03 0.07 14.00 2.50 2.06 0.06 14.25 2.53 2.09 0.06 14.50 2.55 2.11 0.06 14.75 2.58 2.14 0.05 15.00 2.60 2.16 0.05 15.25 2.63 2.18 0.05 15.50 2.65 2.20 0.05 15.75 2.67 2.22 0.04 16.00 2.68 2.24 0.04 16.25 2.70 2.26 0.04 16.50 2.72 2.28 0.04 16.75 2.73 2.29 0.04 17.00 2.75 2.31 0.03 17.25 2.77 2.32 0.03 17.50 2.78 2.34 0.03 17.75 2.80 2.35 0.03 Time Precip. Excess Runoff hours) (inches) (inches) (cfs) 18.00 2.81 2.36 0.03 18.25 2.82 2.38 0.03 18.50 2.84 2.39 0.03 18.75 2.85 2.40 0.03 19.00 2.86 2.41 0.03 19.25 2.87 2.43 0.03 19.50 2.88 2.44 0.02 19.75 2.89 2.45 0.02 20.00 2.90 2.46 0.02 Yancey Pre Post Type 11 24-hr 1 Year Rainfall=3.05" Prepared by Timmons Group Printed 6/25/2019 HydroCAD® 10.00-20 s/n 10074 © 2017 HydroCAD Software Solutions LLC Page 4 Summary for Subcatchment 2S: Post -Developed Area Runoff = 2.07 cfs @ 11.96 hrs, Volume= 0.099 af, Depth> 2.16" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 1Year Rainfall=3.05" Area (ac) CN Description 0.476 98 Paved parking, HSG B 0.077 61 >75% Grass cover, Good, HSG B 0.553 93 Weighted Average 0.077 13.92% Pervious Area 0.476 86.08% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 2S: Post -Developed Area Hydrograph ❑ Runoff z.o 0 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Yancey Pre Post Type/1 24-hr 1 Year Rainfall=3.05" Prepared by Timmons Group Printed 6/25/2019 HydroCAD® 10.00-20 s/n 10074 © 2017 HydroCAD Software Solutions LLC Page 5 Hydrograph for Subcatchment 2S: Post -Developed Area Time Precip. Excess Runoff (hours) (inches) (inches) (cfs) 5.00 0.19 0.00 0.00 5.25 0.20 0.00 0.00 5.50 0.22 0.01 0.00 5.75 0.23 0.01 0.01 6.00 0.24 0.01 0.01 6.25 0.26 0.01 0.01 6.50 0.27 0.02 0.01 6.75 0.29 0.02 0.01 7.00 0.30 0.03 0.01 7.25 0.32 0.03 0.01 7.50 0.33 0.04 0.01 7.75 0.35 0.04 0.01 8.00 0.37 0.05 0.01 8.25 0.38 0.06 0.02 8.50 0.40 0.06 0.02 8.75 0.42 0.07 0.02 9.00 0.45 0.08 0.03 9.25 0.47 0.10 0.03 9.50 0.50 0.11 0.03 9.75 0.52 0.12 0.03 10.00 0.55 0.14 0.04 10.25 0.58 0.16 0.04 10.50 0.62 0.18 0.05 10.75 0.67 0.21 0.06 11.00 0.72 0.24 0.08 11.25 0.78 0.29 0.10 11.50 0.86 0.35 0.14 11.75 1.18 0.59 0.66 12.00 2.02 1.33 1.94 12.25 2.15 1.46 0.26 12.50 2.24 1.54 0.17 12.75 2.30 1.59 0.12 13.00 2.35 1.64 0.10 13.25 2.40 1.68 0.09 13.50 2.44 1.72 0.08 13.75 2.47 1.75 0.07 14.00 2.50 1.78 0.06 14.25 2.53 1.81 0.06 14.50 2.55 1.83 0.05 14.75 2.58 1.85 0.05 15.00 2.60 1.88 0.05 15.25 2.63 1.90 0.05 15.50 2.65 1.92 0.04 15.75 2.67 1.94 0.04 16.00 2.68 1.95 0.04 16.25 2.70 1.97 0.04 16.50 2.72 1.99 0.04 16.75 2.73 2.00 0.03 17.00 2.75 2.02 0.03 17.25 2.77 2.03 0.03 17.50 2.78 2.04 0.03 17.75 2.80 2.06 0.03 Time Precip. Excess Runoff hours) (inches) (inches) (cfs) 18.00 2.81 2.07 0.03 18.25 2.82 2.08 0.03 18.50 2.84 2.10 0.03 18.75 2.85 2.11 0.03 19.00 2.86 2.12 0.03 19.25 2.87 2.13 0.02 19.50 2.88 2.14 0.02 19.75 2.89 2.15 0.02 20.00 2.90 2.16 0.02 Yancey Pre Post Type 11 24-hr 2Year Rainfall=3.69" Prepared by Timmons Group Printed 6/25/2019 HydroCAD® 10.00-20 s/n 10074 © 2017 HydroCAD Software Solutions LLC Page 6 Summary for Subcatchment 1 S: Pre -Developed Area Runoff = 2.74 cfs @ 11.96 hrs, Volume= 0.139 af, Depth> 3.02" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2Year Rainfall=3.69" Area (ac) CN Description 0.529 98 Paved parking, HSG B 0.024 61 >75% Grass cover, Good, HSG B 0.553 96 Weighted Average 0.024 4.34% Pervious Area 0.529 95.66% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, N C1 3 0 LL 3 V, 0 5 Subcatchment 1 S: Pre -Developed Area Hydrograph 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) ❑ Runoff Yancey Pre Post Type 11 24-hr 2Year Rainfall=3.69" Prepared by Timmons Group Printed 6/25/2019 HydroCAD® 10.00-20 s/n 10074 © 2017 HydroCAD Software Solutions LLC Page 7 Hydrograph for Subcatchment 1S: Pre -Developed Area Time Precip. Excess Runoff (hours) (inches) (inches) (cfs) 5.00 0.23 0.04 0.01 5.25 0.25 0.05 0.02 5.50 0.26 0.05 0.02 5.75 0.28 0.06 0.02 6.00 0.30 0.07 0.02 6.25 0.31 0.08 0.02 6.50 0.33 0.09 0.02 6.75 0.35 0.10 0.02 7.00 0.37 0.11 0.03 7.25 0.38 0.13 0.03 7.50 0.40 0.14 0.03 7.75 0.42 0.15 0.03 8.00 0.44 0.17 0.03 8.25 0.46 0.18 0.03 8.50 0.49 0.20 0.04 8.75 0.51 0.22 0.04 9.00 0.54 0.24 0.05 9.25 0.57 0.26 0.05 9.50 0.60 0.29 0.05 9.75 0.63 0.31 0.06 10.00 0.67 0.34 0.07 10.25 0.71 0.37 0.08 10.50 0.75 0.41 0.09 10.75 0.81 0.46 0.10 11.00 0.87 0.51 0.12 11.25 0.94 0.58 0.16 11.50 1.04 0.67 0.21 11.75 1.43 1.03 0.94 12.00 2.45 2.01 2.54 12.25 2.61 2.16 0.34 12.50 2.71 2.27 0.22 12.75 2.79 2.34 0.16 13.00 2.85 2.40 0.13 13.25 2.90 2.46 0.11 13.50 2.95 2.50 0.10 13.75 2.99 2.54 0.09 14.00 3.03 2.58 0.08 14.25 3.06 2.61 0.07 14.50 3.09 2.64 0.07 14.75 3.12 2.67 0.07 15.00 3.15 2.70 0.06 15.25 3.18 2.73 0.06 15.50 3.20 2.75 0.06 15.75 3.23 2.77 0.05 16.00 3.25 2.80 0.05 16.25 3.27 2.82 0.05 16.50 3.29 2.84 0.04 16.75 3.31 2.86 0.04 17.00 3.33 2.87 0.04 17.25 3.35 2.89 0.04 17.50 3.36 2.91 0.04 17.75 3.38 2.93 0.04 Time Precip. Excess Runoff hours) (inches) (inches) (cfs) 18.00 3.40 2.95 0.04 18.25 3.41 2.96 0.04 18.50 3.43 2.98 0.03 18.75 3.45 2.99 0.03 19.00 3.46 3.01 0.03 19.25 3.47 3.02 0.03 19.50 3.49 3.03 0.03 19.75 3.50 3.05 0.03 20.00 3.51 3.06 0.03 Yancey Pre Post Type 11 24-hr 2Year Rainfall=3.69" Prepared by Timmons Group Printed 6/25/2019 HydroCAD® 10.00-20 s/n 10074 © 2017 HydroCAD Software Solutions LLC Page 8 Summary for Subcatchment 2S: Post -Developed Area Runoff = 2.59 cfs @ 11.96 hrs, Volume= 0.126 af, Depth> 2.74" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 2Year Rainfall=3.69" Area (ac) CN Description 0.476 98 Paved parking, HSG B 0.077 61 >75% Grass cover, Good, HSG B 0.553 93 Weighted Average 0.077 13.92% Pervious Area 0.476 86.08% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, N C1 3 0 LL Subcatchment 2S: Post -Developed Area Hydrograph K, 1 0 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Yancey Pre Post Type 11 24-hr 2Year Rainfall=3.69" Prepared by Timmons Group Printed 6/25/2019 HydroCAD® 10.00-20 s/n 10074 © 2017 HydroCAD Software Solutions LLC Page 9 Hydrograph for Subcatchment 2S: Post -Developed Area Time Precip. Excess Runoff (hours) (inches) (inches) (cfs) 5.00 0.23 0.01 0.01 5.25 0.25 0.01 0.01 5.50 0.26 0.01 0.01 5.75 0.28 0.02 0.01 6.00 0.30 0.02 0.01 6.25 0.31 0.03 0.01 6.50 0.33 0.03 0.01 6.75 0.35 0.04 0.01 7.00 0.37 0.05 0.02 7.25 0.38 0.06 0.02 7.50 0.40 0.06 0.02 7.75 0.42 0.07 0.02 8.00 0.44 0.08 0.02 8.25 0.46 0.09 0.02 8.50 0.49 0.10 0.03 8.75 0.51 0.12 0.03 9.00 0.54 0.13 0.04 9.25 0.57 0.15 0.04 9.50 0.60 0.17 0.04 9.75 0.63 0.19 0.04 10.00 0.67 0.21 0.05 10.25 0.71 0.24 0.06 10.50 0.75 0.27 0.07 10.75 0.81 0.30 0.08 11.00 0.87 0.35 0.10 11.25 0.94 0.41 0.14 11.50 1.04 0.49 0.18 11.75 1.43 0.80 0.85 12.00 2.45 1.73 2.41 12.25 2.61 1.88 0.33 12.50 2.71 1.98 0.21 12.75 2.79 2.05 0.15 13.00 2.85 2.11 0.13 13.25 2.90 2.16 0.11 13.50 2.95 2.20 0.10 13.75 2.99 2.24 0.09 14.00 3.03 2.28 0.08 14.25 3.06 2.31 0.07 14.50 3.09 2.34 0.07 14.75 3.12 2.37 0.06 15.00 3.15 2.40 0.06 15.25 3.18 2.42 0.06 15.50 3.20 2.45 0.05 15.75 3.23 2.47 0.05 16.00 3.25 2.49 0.05 16.25 3.27 2.51 0.04 16.50 3.29 2.53 0.04 16.75 3.31 2.55 0.04 17.00 3.33 2.57 0.04 17.25 3.35 2.59 0.04 17.50 3.36 2.60 0.04 17.75 3.38 2.62 0.04 Time Precip. Excess Runoff hours) (inches) (inches) (cfs) 18.00 3.40 2.64 0.04 18.25 3.41 2.65 0.03 18.50 3.43 2.67 0.03 18.75 3.45 2.68 0.03 19.00 3.46 2.70 0.03 19.25 3.47 2.71 0.03 19.50 3.49 2.72 0.03 19.75 3.50 2.74 0.03 20.00 3.51 2.75 0.03 Yancey Pre Post Type 1124-hr 10Year Rainfall=5.55" Prepared by Timmons Group Printed 6/25/2019 HydroCAD® 10.00-20 s/n 10074 © 2017 HydroCAD Software Solutions LLC Page 10 Summary for Subcatchment 1 S: Pre -Developed Area Runoff = 4.20 cfs @ 11.96 hrs, Volume= 0.217 af, Depth> 4.71" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10Year Rainfall=5.55" Area (ac) CN Description 0.529 98 Paved parking, HSG B 0.024 61 >75% Grass cover, Good, HSG B 0.553 96 Weighted Average 0.024 4.34% Pervious Area 0.529 95.66% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, 4 3 N C1 3 0 LL 2 1 0 5 Subcatchment 1 S: Pre -Developed Area Hydrograph 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) ❑ Runoff Yancey Pre Post Type/1 24-hr 10Year Rainfall=5.55" Prepared by Timmons Group Printed 6/25/2019 HydroCAD® 10.00-20 s/n 10074 © 2017 HydroCAD Software Solutions LLC Page 11 Hydrograph for Subcatchment 1S: Pre -Developed Area Time Precip. Excess Runoff (hours) (inches) (inches) (cfs) 5.00 0.35 0.10 0.03 5.25 0.37 0.12 0.03 5.50 0.40 0.13 0.03 5.75 0.42 0.15 0.04 6.00 0.44 0.17 0.04 6.25 0.47 0.19 0.04 6.50 0.50 0.20 0.04 6.75 0.52 0.23 0.05 7.00 0.55 0.25 0.05 7.25 0.58 0.27 0.05 7.50 0.61 0.29 0.05 7.75 0.64 0.31 0.05 8.00 0.67 0.34 0.06 8.25 0.70 0.37 0.06 8.50 0.73 0.40 0.07 8.75 0.77 0.43 0.08 9.00 0.82 0.47 0.08 9.25 0.86 0.51 0.09 9.50 0.90 0.54 0.09 9.75 0.95 0.59 0.10 10.00 1.00 0.63 0.11 10.25 1.06 0.69 0.12 10.50 1.13 0.75 0.14 10.75 1.21 0.82 0.17 11.00 1.30 0.91 0.20 11.25 1.42 1.02 0.25 11.50 1.57 1.16 0.33 11.75 2.15 1.72 1.47 12.00 3.68 3.22 3.88 12.25 3.92 3.46 0.52 12.50 4.08 3.62 0.33 12.75 4.19 3.73 0.24 13.00 4.28 3.82 0.20 13.25 4.36 3.90 0.17 13.50 4.43 3.97 0.15 13.75 4.50 4.03 0.13 14.00 4.55 4.09 0.12 14.25 4.60 4.14 0.11 14.50 4.65 4.18 0.10 14.75 4.69 4.23 0.10 15.00 4.74 4.27 0.09 15.25 4.78 4.31 0.09 15.50 4.82 4.35 0.08 15.75 4.85 4.38 0.08 16.00 4.88 4.42 0.07 16.25 4.92 4.45 0.07 16.50 4.95 4.48 0.07 16.75 4.98 4.51 0.07 17.00 5.00 4.54 0.06 17.25 5.03 4.57 0.06 17.50 5.06 4.59 0.06 17.75 5.09 4.62 0.06 Time Precip. Excess Runoff hours) (inches) (inches) (cfs) 18.00 5.11 4.64 0.06 18.25 5.14 4.67 0.05 18.50 5.16 4.69 0.05 18.75 5.18 4.71 0.05 19.00 5.20 4.74 0.05 19.25 5.23 4.76 0.05 19.50 5.25 4.78 0.04 19.75 5.27 4.80 0.04 20.00 5.28 4.81 0.04 Yancey Pre Post Type 1124-hr 10Year Rainfall=5.55" Prepared by Timmons Group Printed 6/25/2019 HydroCAD® 10.00-20 s/n 10074 © 2017 HydroCAD Software Solutions LLC Page 12 Summary for Subcatchment 2S: Post -Developed Area Runoff = 4.07 cfs @ 11.96 hrs, Volume= 0.204 af, Depth> 4.43" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10Year Rainfall=5.55" Area (ac) CN Description 0.476 98 Paved parking, HSG B 0.077 61 >75% Grass cover, Good, HSG B 0.553 93 Weighted Average 0.077 13.92% Pervious Area 0.476 86.08% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 2S: Post -Developed Area Hydrograph ❑ Runoff 4 Type II 240h r Mear Rainfall=5.55" Runoff -Area=0553 ac 311 Runoff Volume=0.204 of Runoff Depth>4.43" LL 2 Tc=6.0 m i n ,-@Eq3eky 1 0 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) Yancey Pre Post Type/1 24-hr 10Year Rainfall=5.55" Prepared by Timmons Group Printed 6/25/2019 HydroCAD® 10.00-20 s/n 10074 © 2017 HydroCAD Software Solutions LLC Page 13 Hydrograph for Subcatchment 2S: Post -Developed Area Time Precip. Excess Runoff (hours) (inches) (inches) (cfs) 5.00 0.35 0.04 0.02 5.25 0.37 0.05 0.02 5.50 0.40 0.06 0.02 5.75 0.42 0.07 0.02 6.00 0.44 0.08 0.03 6.25 0.47 0.09 0.03 6.50 0.50 0.11 0.03 6.75 0.52 0.12 0.03 7.00 0.55 0.14 0.03 7.25 0.58 0.15 0.04 7.50 0.61 0.17 0.04 7.75 0.64 0.19 0.04 8.00 0.67 0.21 0.04 8.25 0.70 0.23 0.05 8.50 0.73 0.25 0.05 8.75 0.77 0.28 0.06 9.00 0.82 0.31 0.07 9.25 0.86 0.34 0.07 9.50 0.90 0.38 0.07 9.75 0.95 0.41 0.08 10.00 1.00 0.45 0.09 10.25 1.06 0.50 0.11 10.50 1.13 0.56 0.12 10.75 1.21 0.62 0.15 11.00 1.30 0.70 0.18 11.25 1.42 0.80 0.23 11.50 1.57 0.93 0.30 11.75 2.15 1.45 1.38 12.00 3.68 2.91 3.78 12.25 3.92 3.14 0.51 12.50 4.08 3.30 0.33 12.75 4.19 3.41 0.24 13.00 4.28 3.50 0.20 13.25 4.36 3.58 0.17 13.50 4.43 3.64 0.15 13.75 4.50 3.70 0.13 14.00 4.55 3.76 0.12 14.25 4.60 3.81 0.11 14.50 4.65 3.85 0.10 14.75 4.69 3.90 0.10 15.00 4.74 3.94 0.09 15.25 4.78 3.98 0.09 15.50 4.82 4.02 0.08 15.75 4.85 4.05 0.08 16.00 4.88 4.08 0.07 16.25 4.92 4.11 0.07 16.50 4.95 4.14 0.07 16.75 4.98 4.17 0.06 17.00 5.00 4.20 0.06 17.25 5.03 4.23 0.06 17.50 5.06 4.26 0.06 17.75 5.09 4.28 0.06 Time Precip. Excess Runoff hours) (inches) (inches) (cfs) 18.00 5.11 4.31 0.06 18.25 5.14 4.33 0.05 18.50 5.16 4.35 0.05 18.75 5.18 4.38 0.05 19.00 5.20 4.40 0.05 19.25 5.23 4.42 0.05 19.50 5.25 4.44 0.04 19.75 5.27 4.46 0.04 20.00 5.28 4.48 0.04 data input cells Project Name: Date: Yancey Lumber Yard V5MP 6/25/2019 wnstant values Linear Development Project? No calculation cells Site Information Post -Development Project (Treatment Volume and Loads) Enter Total Disturbed Area (acres) 0.55 Check. r® BMP Design Specifications List. 2013 Draft Stds & Specs Linear project? No 0 . • r r Pre-ReDevelopment Land Cover (acres) Land cover areas entered correctly? Total disturbed area entered? �I A Soils B Soils C Soils D Soils Totals Forest/Open Space (acres) -- undisturbed forest/open space 0.00 Managed Turf (acres) -- disturbed, graded for yards or other turf to be mowed/managed 0.02 0.02 Impervious Cover (acres) 0.53 0.53 Post -Development Land Cover (acres) 0.55 A Soils B Soils C Soils D Soils Totals Forest/Open Space (acres) -- undisturbed, protected forest/open space or reforested land 0.00 Managed Turf (acres) -- disturbed, graded for vards or other turfto be mowed/managed 0.08 0.08 Impervious Cover (acres) 0.48 0.48 Area Check OK. OK. OK. OK. 0.55 Constants Runoff Coefficients (Rv) Annual Rainfall (inches) 43 A Soils B Soils C Soils D Soils Target Rainfall Event (inches) 1.00 Forest/Open Space 0.02 0.03 0.04 0.05 Total Phosphorus (TP) EMC (mg/L) 0.26 Managed Turf 0.15 0.20 0.22 0.25 Total Nitrogen (TN) EMC (mg/L) 1.86 Impervious Cover 0.95 0.95 0.95 0.95 Target TP Load (lb/acre/yr) 0.41 Pj (unitless correction factor) 0.90 COVERLAND • • • COVER SUMMARY POST•' Land Cover Summary -Pre Land Cover Summary -Post (Final) Land Cover Summary -Post Land Cover Summary -Post Pre-ReDevelopment Listed Adjusted' Post ReDev. & New Impervious Post-ReDevelopment Post -Development New Impervious Forest/Open Space Cover (acres) 0.00 0.00 Forest/Open Space Cover (acres) 0.00 Forest/Open Space Cover (acres) 0.00 Weighted Rv(forest) 0.00 0.00 Weighted Rv(forest) 0.00 Weighted Rv(forest) 0.00 %Forest 0% 0% %Forest 0% %Forest 0% Managed Turf Cover (acres) 0.02 0.02 Managed Turf Cover (acres) 008 Managed Turf Cover (acres) 0.08 Weighted Rv(turf) 0.20 0.20 Weighted Rv (turf) 0.20 Weighted Rv (turf) 0.20 %Managed Turf 4% 4% %Managed Turf 14% %Managed Turf 14% Impervious Cover (acres) 0.53 0.53 Impervious Cover (acres) 0.48 ReDev. Impervious Cover (acres) 0.48 New Impervious Cover 0.00 (acres) Rv(impervious) 0.95 0.95 Rv(impervious) 0.95 Rv(impervious) 0.95 Rv(impervious) -- %Impervious 96% 96% %Impervious 86% %Impervious 86% Total Site Area (acres) 0.55 0.55 Final Site Area (acres) 0.55 Total ReDev. Site Area (acres) 0.55 Site Rv 0.92 0.92 Final Post Dev Site Rv 0.85 ReDev Site Rv 0.85 Treatment Volume and Nutrient Load 0.0423 1,842 1.16 Treatment Volume and Nutrient Load -M Pre-ReDevelopment Treatment Volume (acre-ft) 0.0423 Final Post -Development Treatment Volume (acre-ft) 0.0390 Post-ReDevelopment Treatment Volume (acre-ft) 0.0390 1,697 FTee.tmst-Developmnt entVolume (acre-ft) Post -Development Treatment Volume (cubic feet) Post -Development TP Load (lb/yr) -- Pre-ReDevelopment Treatment Volume (cubic feet) 1,842 Final Post -Development Treatment Volume (cubic feet) 1,697 Post-ReDevelopment Treatment Volume (cubic feet) -- Pre-ReDevelopment TP Load (lb/yr) 1.16 Final Post- Development TP Load (lb/yr) 1.07 Post-ReDevelopment Load (TP) (lb/yr)* 1.07 Pre-ReDevelopment TP Load per acre (Ib/acre/yr) Final Post -Development TP Load per acre (lb/acre/yr) 1.93 Post-ReDevelopment TP Load per acre (lb/acre/yr) 1.93 Baseline TP Load (lb/yr) (0.41 Ibs/acre/yr applied to pre -redevelopment area excluding pervious land proposed for new impervious cover) Max. Reduction Required (Below Pre- ReDevelopment Load) 10% 'Ad usted Land Cover Summary., � y Pre ReDevelopment land cover minus pervious land cover (forest/open space or managed turf) acreage proposed for new impervious cover. Adjusted total acreage is consistent with Post-ReDevelopment acreage (minus acreage of new impervious cover). Column 1 shows load reduction requriement for new impervious cover (based on new development load limit 0.41 Ibs/acre/year). Post -Development R- quirement for Site Area TP Load Reduction Required (Ib/yr) 0.03 Nitrogen Loads (Informational Purposes Only) TP Load Reduction Required for Redeveloped Area p (Ib/yr) 0.03 TP Load Reduction Required for New Impervious Area (Ib/yr) 0 Pre-ReDevelopment TN Load (Ib/yr) 8.28 Final Post -Development TN Load (Post-ReDevelopment & New Impervious) (lb/yr) 7.63