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HomeMy WebLinkAboutWPO202000033 Other 2020-08-19SHIMP ENGINEERING, P.C. Design Focused Engineering July 30, 2020 County of Albemarle Department of Community Development 401 McIntire Road Charlottesville, VA 22902 Regarding: Malloy Ford TMP 45.68A Stormwater Management Plan Dear Reviewer, The purpose of this project is to add a parking area to a site with an existing building and limited parking. Parking will be added where a portion of the existing building was removed. The total area of disturbance is 0.91 acres. Runoff from the site is analyzed at two points, labeled POA1 and POA2. Please see VSMP plan sheets C8 and C9 for the locations of these drainage areas and points of analysis. The drainage areas to points of analysis are separated into disturbed and undisturbed area, since the improvement factor is only applied to the disturbed portions continue to function as designed. Runoff to POA1 outlets to an existing stormwater pipe (labeled Al) while runoff to POA2 is released over land from the site and eventually picked up by a drop inlet down the road outside of Route 29. In both cases, the peak flow rates released at these points of analysis are less than in predevelopment conditions and conform with channel and flood protection requirements. Please see below for a summary of energy balance calculations. The first table shows 1 yr, 24 hr storm peak flow rates and runoff volume for drainage areas within the disturbed area. The improvement factor of 0.9 is applied to these values in the energy balance equation. The second table shows all values for drainage areas outside of the limits of disturbance, no improvement factor was applied to these values. The third table shows the final results, along with 10 yr, 24 hr storm peak flow rates of both pre and post development conditions. For further detail on these drainage areas and calculations, please see the HydroCAD reports included in this document. Note that time of concentration calculations are not included as all are assumed 5 minutes. Table 1. Values for DAs Within LOD - Energy Balance Equation PREDEV POSTDEV POA Q1 RV RV 1 2.39 0.115 0.102 2 0.67 0.031 0.027 Table 2. Values for DAs Outside LOD — Energy Balance Equation PREDEV POSTDEV POA Q1 RV RV 1 1.63 0.088 0.088 2 912 E. High Sr. Charlottesville, VA 22902 1434.227.5140 1 shimp-engineering.com Table 3. Summary of Results — Energy Balance Equation & Flood Protection Table 1 Table 2 Q1 Allowable=((Q1Pre(LOD)*RvPre(LOD)*I.F.)/RvPost(LOD)l+((Q1Pre*RVPre1 Or Q1 Pre, whichever is less POA Q1 ALLOWABLE (CFS) Q1 PROPOSED (CFS) Q10 PRE Q10 POST 1 4.03 3.79 7.91 7.71 2 0.67 0.61 1.62 1.53 According to the VRRM spreadsheet included in this packet, the target phosphorus load reduction is 0.01 lb/yr. Nutrient credits will be purchased to satisfy this requirement. Contents: Pre -Development Stormwater Management Calculations: Pre -Development Landuse Map Pre -Development HydroCAD Analysis Post -Development Stormwater Management Calculations: Post -Development Landuse Map Post -Development HydroCAD Analysis Stormwater Quality Calculations: VRRM Redevelopment Spreadsheet Independent Reports: Excerpt from NRCS Soils Report NOAA Precipitation Report Pre -Development Stormwater Management Calculations Pre -Development Landuse Map Pre -Development HydroCAD Analysis PRE -DEVELOPMENT LANDUSE MAP i T.M 45-112131 MALLOY PROPERTIES III C/O MALLOY COMPANIES LLC 1 DB 4863 PG 471 ZONED: HC CURRENT USE: VACANT 1 � 1 � a y � y 1 � --THIS AREA NOT INCLUDED LIMITS OF DISTURBANCE 1 0 AS NO CHANGE TO LANDUSE COVER & NO DISTURBANCE OF DIRT TURF IMPERVIOUS Scale: 1 "=30' MALLOY FORD HSG B HSG D 0.28 AC 0.63 AC 2S 3S 1S POA 1 DA (I LOD) PO DA (Outside LOD) POA 2 D (IN LOD) 5L 6L POA 1 POA 2 Subcat Reach on Link Drainage Diagram for Pre Dev Prared by {enter your company name here}, Printed 6/5/2020 FHYdpoCArD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC PreDev Pre Dev Type 11 24-hr 1 yr, 24 hr Rainfall=3. 01 " Prepared by {enter your company name here} Printed 6/5/2020 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 2 Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentlS: POA 2 DA (IN LOD) Runoff Area=11,140 sf 50.77% Impervious Runoff Depth=1.45' Tc=5.0 min CN=83 Runoff=0.67 cfs 0.031 of Subcatchment2S: POA 1 DA (IN LOD) Runoff Area=28,892 sf 76.44% Impervious Runoff Depth=2.08" Tc=5.0 min CN=91 Runoff=2.39 cfs 0.115 of Subcatchment3S: POA 1 DA (Outside Runoff Area=16,577 sf 100.00% Impervious Runoff Depth=2.78" Tc=5.0 min CN=98 Runoff=1.63 cfs 0.088 of Link 5L: POA 1 Inflow=4.03 cfs 0.203 of Primary=4.03 cfs 0.203 of Link 6L: POA 2 Inflow=0.67 cfs 0.031 of Primary=0.67 cfs 0.031 of Total Runoff Area = 1.300 ac Runoff Volume = 0.234 of Average Runoff Depth = 2.16" 21.71% Pervious = 0.282 ac 78.29% Impervious = 1.017 ac Pre Dev Prepared by {enter your company name here) PreDev Type 11 24-hr 1 yr, 24 hr Rainfall=3.01 " Printed 6/5/2020 Summary for Subcatchment 1S: POA 2 DA (IN LOD) Runoff = 0.67 cfs @ 11.96 hrs, Volume= 0.031 af, Depth= 1.45" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 1 yr, 24 hr Rainfall=3.01" Area (sf) CN Description 3,444 61 >75% Grass cover, Good, HSG B 2,040 80 >75% Grass cover, Good, HSG D 0 98 Impervious, HSG B 5.656 98 Impervious. HSG D 11,140 83 Weighted Average 5,484 49.23% Pervious Area 5,656 50.77% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2S: POA 1 DA (IN LOD) Runoff = 2.39 cfs @ 11.95 hrs, Volume= 0.115 af, Depth= 2.08" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 1 yr, 24 hr Rainfall=3.01" Area (sf) CN Description 2,544 80 >75% Grass cover, Good, HSG D 4,263 61 >75% Grass cover, Good, HSG B 15,501 98 HSG D Impery 6,584 98 HSG B Impery 28,892 91 Weighted Average 6,807 23.56% Pervious Area 22,085 76.44% Impervious Area Tc Length Slope Velocity Capacity Description 5.0 Direct Entry, Summary for Subcatchment 3S: POA 1 DA (Outside LOD) Runoff = 1.63 cfs @ 11.95 hrs, Volume= 0.088 af, Depth= 2.78" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type 11 24-hr 1 yr, 24 hr Rainfall=3.01" Pre Dev Prepared by {enter your company name here} Area (sf) CN Description 0 80 >75% Grass cover, Good, HSG D 0 61 >75% Grass cover, Good, HSG B 6,994 98 HSG D Impery 9,583 98 HSG B Impery 16,577 98 Weighted Average 16,577 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, PreDev Type 11 24-hr 1 yr, 24 hr Rainfall=3.01 " Printed 6/5/2020 Summary for Link 5L: POA 1 Inflow Area = 1.044 ac, 85.03% Impervious, Inflow Depth = 2.33" for 1 yr, 24 hr event Inflow = 4.03 cfs @ 11.95 hrs, Volume= 0.203 of Primary = 4.03 cfs @ 11.95 hrs, Volume= 0.203 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Summary for Link 6L: POA 2 Inflow Area = 0.256 ac, 50.77% Impervious, Inflow Depth = 1.45" for 1 yr, 24 hr event Inflow = 0.67 cfs @ 11.96 hrs, Volume= 0.031 of Primary = 0.67 cfs @ 11.96 hrs, Volume= 0.031 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs PreDev Pre Dev Type 11 24-hr 10 yr, 24 hr Rainfall=5.50" Prepared by {enter your company name here} Printed 6/5/2020 HydroCAD® 9.10 s/n 07054 © 2011 HydroCAD Software Solutions LLC Page 5 Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentlS: POA 2 DA (IN LOD) Runoff Area=11,140 sf 50.77% Impervious Runoff Depth=3.63" Tc=5.0 min CN=83 Runoff=1.62 cfs 0.077 of Subcatchment2S: POA 1 DA (IN LOD) Runoff Area=28,892 sf 76.44% Impervious Runoff Depth=4.47" Tc=5.0 min CN=91 Runoff=4.90 cfs 0.247 of Subcatchment3S: POA 1 DA (Outside Runoff Area=16,577 sf 100.00% Impervious Runoff Depth=5.26" Tc=5.0 min CN=98 Runoff=3.01 cfs 0.167 of Link 5L: POA 1 Inflow=7.91 cfs 0.414 of Primary=7.91 cfs 0.414 of Link 6L: POA 2 Inflow=1.62 cfs 0.077 of Primary=1.62 cfs 0.077 of Total Runoff Area = 1.300 ac Runoff Volume = 0.491 of Average Runoff Depth = 4.54" 21.71% Pervious = 0.282 ac 78.29% Impervious = 1.017 ac Pre Dev Prepared by {enter your company name here) PreDev Type 11 24-hr 10 yr, 24 hr Rainfall=5.50" Printed 6/5/2020 Summary for Subcatchment 1S: POA 2 DA (IN LOD) Runoff = 1.62 cfs @ 11.95 hrs, Volume= 0.077 af, Depth= 3.63" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr, 24 hr Rainfall=5.50" Area (sf) CN Description 3,444 61 >75% Grass cover, Good, HSG B 2,040 80 >75% Grass cover, Good, HSG D 0 98 Impervious, HSG B 5.656 98 Impervious. HSG D 11,140 83 Weighted Average 5,484 49.23% Pervious Area 5,656 50.77% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2S: POA 1 DA (IN LOD) Runoff = 4.90 cfs @ 11.95 hrs, Volume= 0.247 af, Depth= 4.47" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr, 24 hr Rainfall=5.50" Area (sf) CN Description 2,544 80 >75% Grass cover, Good, HSG D 4,263 61 >75% Grass cover, Good, HSG B 15,501 98 HSG D Impery 6,584 98 HSG B Impery 28,892 91 Weighted Average 6,807 23.56% Pervious Area 22,085 76.44% Impervious Area Tc Length Slope Velocity Capacity Description 5.0 Direct Entry, Summary for Subcatchment 3S: POA 1 DA (Outside LOD) Runoff = 3.01 cfs @ 11.95 hrs, Volume= 0.167 af, Depth= 5.26" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type 11 24-hr 10 yr, 24 hr Rainfall=5.50" Pre Dev Prepared by {enter your company name here} Area (sf) CN Description 0 80 >75% Grass cover, Good, HSG D 0 61 >75% Grass cover, Good, HSG B 6,994 98 HSG D Impery 9,583 98 HSG B Impery 16,577 98 Weighted Average 16,577 100.00% Impervious Area PreDev Type 11 24-hr 10 yr, 24 hr Rainfall=5.50" Printed 6/5/2020 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Link 5L: POA 1 Inflow Area = 1.044 ac, 85.03% Impervious, Inflow Depth = 4.76" for 10 yr, 24 hr event Inflow = 7.91 cfs @ 11.95 hrs, Volume= 0.414 of Primary = 7.91 cfs @ 11.95 hrs, Volume= 0.414 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Summary for Link 6L: POA 2 Inflow Area = 0.256 ac, 50.77% Impervious, Inflow Depth = 3.63" for 10 yr, 24 hr event Inflow = 1.62 cfs @ 11.95 hrs, Volume= 0.077 of Primary = 1.62 cfs @ 11.95 hrs, Volume= 0.077 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Post -Development Stormwater Management Calculations Post -Development Landuse Map Post -Development HydroCAD Analysis POST -DEVELOPMENT LANDUSE MAP \1 1 T.M 45-112131 MALLOY PROPERTIES III C/0 / MALLOY COMPANIES LLC 1 DB 4863 PG 471 ZONED: HC CURRENT USE: VACANT 1 1 --THIS AREA NOT INCLUDED LIMITS OF DISTURBANCE AS NO CHANGE TO LANDUSE COVER & NO DISTURBANCE OF DIRT TURF IMPERVIOUS s 30 � � 9 Scale: 1 "=30' MALLOY FORD HSG B HSG D 0.36 AC 0.55 AC 1S 12S POA 1 DA (I LOD) POA DA (Outside LOD) 11L POA 1 S4 Reach X 4on Llflk 5S 14S POA 2 DA (I LOD) POA 2 DA (Outside LOD) 4L POA 2 PostDev Post Dev Type 11 24-hr 1 yr, 24 hr Rainfall=3.01 " Prepared by {enter your company name here} Printed 6/5/2020 HVdroCAD® 9.10 s/n 07054 © 2011 HVdroCAD Software Solutions LLC Paoe 2 Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentlS: POA 1 DA (IN LOD) Runoff Area=29,104 sf 67.67% Impervious Runoff Depth=1.83" Tc=5.0 min CN=88 Runoff=2.16 cfs 0.102 of Subcatchment5S: POA 2 DA (IN LOD) Runoff Area=10,607 sf 39.29% Impervious Runoff Depth=1.32" Tc=5.0 min CN=81 Runoff=0.58 cfs 0.027 of Subcatchmentl2S: POA 1 DA (Outside Runoff Area=16,577 sf 100.00% Impervious Runoff Depth=2.78" Tc=5.0 min CN=98 Runoff=1.63 cfs 0.088 of Subcatchment 14S: POA 2 to DA (Outside Runoff Area=321 sf 100.00% Impervious Runoff Depth=2.78" Tc=5.0 min CN=98 Runoff=0.03 cfs 0.002 of Link 4L: POA 2 Inflow=0.61 cfs 0.029 of Primary=0.61 cfs 0.029 of Link 11 L: POA 1 Inflow=3.79 cfs 0.190 of Primary=3.79 cfs 0.190 of Total Runoff Area = 1.300 ac Runoff Volume = 0.218 of Average Runoff Depth = 2.02" 28.00% Pervious = 0.364 ac 72.00% Impervious = 0.936 ac Post Dev Prepared by {enter your company name here) PostDev Type 11 24-hr 1 yr, 24 hr Rainfall=3.01 " Printed 6/5/2020 Summary for Subcatchment 1S: POA 1 DA (IN LOD) Runoff = 2.16 cfs @ 11.96 hrs, Volume= 0.102 af, Depth= 1.83" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 1 yr, 24 hr Rainfall=3.01" Area (sf) CN Description 6,723 61 >75% Grass cover, Good, HSG B 2,687 80 >75% Grass cover, Good, HSG D 4,119 98 IMPERV B 15.575 98 IMPERV D 29,104 88 Weighted Average 9,410 32.33% Pervious Area 19,694 67.67% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 5S: POA 2 DA (IN LOD) Runoff = 0.58 cfs @ 11.96 hrs, Volume= 0.027 af, Depth= 1.32" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 1 yr, 24 hr Rainfall=3.01" Area (sf) CN Description 3,449 61 >75% Grass cover, Good, HSG B 2,990 80 >75% Grass cover, Good, HSG D 0 98 IMPERV B 4,168 98 IMPERV D 10,607 81 Weighted Average 6,439 60.71 % Pervious Area 4,168 39.29% Impervious Area Tc Length Slope Velocity Capacity Description 5.0 Direct Entry, Summary for Subcatchment 12S: POA 1 DA (Outside LOD) Runoff = 1.63 cfs @ 11.95 hrs, Volume= 0.088 af, Depth= 2.78" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type 11 24-hr 1 yr, 24 hr Rainfall=3.01" Post Dev Prepared by {enter your company name here) Area (sf) CN Description 0 61 >75% Grass cover, Good, HSG B 0 80 >75% Grass cover, Good, HSG D 9,583 98 IMPERV B 6,994 98 IMPERV D 16,577 98 Weighted Average 16,577 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, PostDev Type 11 24-hr 1 yr, 24 hr Rainfall=3.01 " Printed 6/5/2020 Summary for Subcatchment 14S: POA 2 to DA (Outside LOD) Runoff = 0.03 cfs @ 11.95 hrs, Volume= 0.002 af, Depth= 2.78" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 1 yr, 24 hr Rainfall=3.01" Area (sf) CN Description 321 98 321 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Link 4L: PDA 2 Inflow Area = 0.251 ac, 41.08% Impervious, Inflow Depth = 1.36" for 1 yr, 24 hr event Inflow = 0.61 cfs @ 11.96 hrs, Volume= 0.029 of Primary = 0.61 cfs @ 11.96 hrs, Volume= 0.029 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Summary for Link 11 L: POA 1 Inflow Area = 1.049 ac, 79.40% Impervious, Inflow Depth = 2.17" for 1 yr, 24 hr event Inflow = 3.79 cfs @ 11.95 hrs, Volume= 0.190 of Primary = 3.79 cfs @ 11.95 hrs, Volume= 0.190 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs PostDev Post Dev Type 11 24-hr 10 yr, 24 hr Rainfall=5.50" Prepared by {enter your company name here} Printed 6/5/2020 HVdroCAD® 9.10 s/n 07054 © 2011 HVdroCAD Software Solutions LLC Page 5 Time span=0.00-48.00 hrs, dt=0.05 hrs, 961 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method SubcatchmentlS: POA 1 DA (IN LOD) Runoff Area=29,104 sf 67.67% Impervious Runoff Depth=4.15" Tc=5.0 min CN=88 Runoff=4.70 cfs 0.231 of Subcatchment5S: POA 2 DA (IN LOD) Runoff Area=10,607 sf 39.29% Impervious Runoff Depth=3.43" Tc=5.0 min CN=81 Runoff=1.47 cfs 0.070 of Subcatchmentl2S: POA 1 DA (Outside Runoff Area=16,577 sf 100.00% Impervious Runoff Depth=5.26" Tc=5.0 min CN=98 Runoff=3.01 cfs 0.167 of Subcatchment 14S: POA 2 to DA (Outside Runoff Area=321 sf 100.00% Impervious Runoff Depth=5.26" Tc=5.0 min CN=98 Runoff=0.06 cfs 0.003 of Link 4L: POA 2 Inflow=1.53 cfs 0.073 of Primary=1.53 cfs 0.073 of Link 11 L: POA 1 Inflow=7.71 cfs 0.398 of Primary=7.71 cfs 0.398 of Total Runoff Area = 1.300 ac Runoff Volume = 0.471 of Average Runoff Depth = 4.35" 28.00% Pervious = 0.364 ac 72.00% Impervious = 0.936 ac Post Dev Prepared by {enter your company name here) PostDev Type 11 24-hr 10 yr, 24 hr Rainfall=5.50" Printed 6/5/2020 Summary for Subcatchment 1S: POA 1 DA (IN LOD) Runoff = 4.70 cfs @ 11.95 hrs, Volume= 0.231 af, Depth= 4.15" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr, 24 hr Rainfall=5.50" Area (sf) CN Description 6,723 61 >75% Grass cover, Good, HSG B 2,687 80 >75% Grass cover, Good, HSG D 4,119 98 IMPERV B 15.575 98 IMPERV D 29,104 88 Weighted Average 9,410 32.33% Pervious Area 19,694 67.67% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 5S: POA 2 DA (IN LOD) Runoff = 1.47 cfs @ 11.96 hrs, Volume= 0.070 af, Depth= 3.43" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr, 24 hr Rainfall=5.50" Area (sf) CN Description 3,449 61 >75% Grass cover, Good, HSG B 2,990 80 >75% Grass cover, Good, HSG D 0 98 IMPERV B 4,168 98 IMPERV D 10,607 81 Weighted Average 6,439 60.71 % Pervious Area 4,168 39.29% Impervious Area Tc Length Slope Velocity Capacity Description 5.0 Runoff = Direct Entry, Summary for Subcatchment 12S: POA 1 DA (Outside LOD) 3.01 cfs @ 11.95 hrs, Volume= 0.167 af, Depth= 5.26" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type 11 24-hr 10 yr, 24 hr Rainfall=5.50" Post Dev Prepared by {enter your company name here) Area (sf) CN Description 0 61 >75% Grass cover, Good, HSG B 0 80 >75% Grass cover, Good, HSG D 9,583 98 IMPERV B 6,994 98 IMPERV D 16,577 98 Weighted Average 16,577 100.00% Impervious Area PostDev Type 11 24-hr 10 yr, 24 hr Rainfall=5.50" Printed 6/5/2020 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 14S: POA 2 to DA (Outside LOD) Runoff = 0.06 cfs @ 11.95 hrs, Volume= 0.003 af, Depth= 5.26" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr, 24 hr Rainfall=5.50" Area (sf) CN Description 321 98 321 100.00% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Link 4L: PDA 2 Inflow Area = 0.251 ac, 41.08% Impervious, Inflow Depth = 3.48" for 10 yr, 24 hr event Inflow = 1.53 cfs @ 11.95 hrs, Volume= 0.073 of Primary = 1.53 cfs @ 11.95 hrs, Volume= 0.073 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Summary for Link 11 L: POA 1 Inflow Area = 1.049 ac, 79.40% Impervious, Inflow Depth = 4.55" for 10 yr, 24 hr event Inflow = 7.71 cfs @ 11.95 hrs, Volume= 0.398 of Primary = 7.71 cfs @ 11.95 hrs, Volume= 0.398 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.05 hrs Stormwater Quality Calculations VRRM Redevelopment Spreadsheet Pmlea Name pma our:tur Linear Development Proni,t? 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Dss ass agars, wxl Dss R.Omwssare Dss ----- andnpelbel %Impewux wF uea (oaten( area Pmxl 0.91 Trel11l 1.A ran D.e a nR Treatment Volume and NWrlent Load Treatment Volume and NWHe InBd .Peoare9 ercna va oma9 sum reammnvn�enr Dmae uarla.re-nll•m T m o e Dn99 mMema m t, layshl Pi .Pa—sai here —a mveame w . erevgmem -R r ui meal x,s95 ]2,�3 me reanaart Ve. x,174 ne arn,emeVo. Te 'ma rr me less,T1mU, kerl lmai lent ser(Fina Pre-BlCtuel., retuned t. P me r ullh/.I' PaLewMpnnnn UWr•1 Lad pmlentx 2.37 oerem ge/rdma ImaYlLsP "D - Ls/vd rre.ae IlvasW ,aR 1M ra, � -a re/tee enr -IIReheem L. Ua i Iles) as. Iwrlayana'. lmne..als-r' auauusam Pena all ma rans-ne—irraauxewee taenm rre� amen. wael vn • menamn re.pn,exynwnxwrere fiso01 en ledm. xe. D .it erlee ce, n elwm arrear P/M aura mm .,.e�acmasea rauwnmmr uaeyelm*m uaeye '.. - �l�e.smewsm ! I s.an rcwMnnaneM na..n'mmlmevm sae. brrzmlmunsxanleymry 1 iP load Re tlu[don Re Oulretl (Ib/yrl 0A1 Site Results (Water Quality Compliance) Area Checks O.A.A O.A.B O.A.0 A. D.A.E ARMEM FOREST/OVEN SPACE (a[) am O.M 0.M i0.00 O.W OK. I IMPEWnUSCOVERTRENTFDIa[ 0.00 O.M 0.00�M. OWOK. MANAGEDMRFARENIa[) 0.00 O.M 0.00 00.W OK. MANAGED TURF AREA TREATED (a[) am O.M 0.00 O.W OK. AREA CHECK OK OK. OK. OK. Site Treatment VOIUMe (ffa) 71. Runoff Reduction Volume and TP By Drainage Area O.A. A D.AD O.A. E TOTALRUNOFF REDUCNON VOLUME ACHIEVED pF) 0 0 0 TPLOADAVANIBLE FOR REMOVAL (b/1) 0.00 MM0 0.00 O.W 0.00TPID MDUCTIONAGVEVED (b/yr) 0.00 0.00am TP LOAD REMAINING (Ib/yr) 0.00 0.00 O.W am NMOGEN MD REDUCTION ACHIEVED (lb/yr) am O.W 0.00 0.00 O.W 0.00 Total Phosphorus FINALPOST-OEVELOPMENTTPLOADQb/yr) 1.3E TP LOAD REDUCTION REQUIRED pb/yrl 0.01 TP WAD REDUCTIONACHIEVED (b/yr) 0.00 W LOAD REMAINING (lb/N): 1.3E REMAINING TP LOAD REDUCTION REQUIRED pbM: 0.01 Total Nitrogen (For Information Purposes( POST-DEVEMPMEM WAD (Ib/yr) 9JE NMOGEN LOAD REDUCTION ACHIEVED )Ib/yrl 0.00 REMAINING POST-DEV M MEM NRRWEN LOAD )Ib/yrl 9JE Viyinia RurnB Reduction Method Worksbeel DEQ Virginia Runoff Reduction Method Re -Development Compliance Spreadsheet -Version 3.0 BMP Design Sperificotions Use W13 Draft St&&Specs Site Summary Project Title: Malloy Furniture Date: 43985 Total Rainfall (in): 43 Total Disturbed Acreage: 0.91 Site Land Cover Summary Pre-ReDevelopment Land Cover (acres) Asolls BSoils CSnlls OSoUs Totals %of Total Forest/Open (acres) OAO 0.00 0.00 0.00 OAO 0 Managed Tud(acres) I OAO 0.18 1 0.00 0.11 0.29 31 Impervious Cover (acres) I OAO 0.15 0.00 0." 0.63 69 0.91 100 Post-ReDevelopment Land Cover (acres) A soils BSollz CShcs OSolls Totals %ofTotal Forest/Open (acres) 0.00 0.00 0.0D 0.00 OAO 0 Managed Turf (acres) I OAO 0.23 0.00 0.13 0.36 40 Impervious cover (acres) I OAO 0.09 0.00 0.45 0.55 60 0.91 IDO Site Tv and Land Cover Nutrient Loads Final Post -Development Port- Pan.AdjustedPre- (&NewOeveloious) Development &New Impervious) ReDevelopment (Newlmpendous) ReDevelopment Site Rv 0.66 0.66 Treatment Volume(fts) 2,174 2,174 TP Load (lb/yr) 1.37 1.37 Total TP Load Reduction Required (Ib/yr) 0.01 0.01 0 Final Port -Development Load (Port-ReDevelopment&New Impervious) Pre- ReDevelopment TN Load (lb/yr) 19.72 10.76 Pre- Final Post -Development Post-ReDevelopment TP ReDevelopment TP load per acre Load per acre TP Loadperarre Ob/acre/yr) (lb/acre/yr) Ib acre r 1.65 1.50 1.50 Summery Print Virginia Runoff Reduction Method Mineheet Site Compliance Summary Maximum% Reduction Required Below 10% Pre-0.eDevelopmen<Loatl Total Rundown Volume Reduttion)f) 0 Total TP Load Redu lion Achieved )Ib/yr) 0.00 Total TN Load Redu dlon Achieved )Ib/yr) 0.00 Remaining Port Development TIP Load 1.3) )Ib/yr) Remaining TIP Load Reduction)Ib/yr) 0.01 Required Summery Print Uyinia RuroB Redud n Med 4VprkaM1eet ------------------------------------------------------------------------------------------------------------------------------------------------------------ Drainage Area Summary D.A A D.A B D.A C DA. D D.A E TOM Forest/Open (acres) 0.00 0.00 0.00 0.00 0.00 0.00 Managed Turf (acres) 0.00 0.00 0.00 0.00 0.00 0.00 Impervious Co r(acres) 0.00 0.00 0.00 0.00 0.00 0.00 Total Area (acres) 0.00 0.00 OAO 0.00 0.00 0.00 Summery Print Independent Reports Excerpt from NRCS Soils Report NOAA Precipitation Report �-5'3'N 3 53 N Custom Soil Resource Report 3 Soil Map 3 m m ]21BB� R19f0 Tt1910 ]213/D i12]Oa 3 Map Smle: 1:1,280 6 pdnbEd m A landsmpe (11" x 8.5') sheet. Mks N 0 15 30 60 90 AFeEt o 5D ,ao 2ao 300 Map pNojechm: Web Me bob Cm madinat s: WGS84 Edge ti¢: U1M Zme 17N WGS84 6 p 3 53@ N N 3 532' N ]Z1a30 ]JST�O TI1030 ]1212(1 T12150 3 m MAPLEGEND Area of Interest (AOQ O Area of Interest (AOI) Solis Soil Map Unit Polygons N Soil Map Unit Lines Soil Map Unit Points Special Point Features V Blowout ® Borrow Pit Clay Spot O Closed Depression Gravel Pit Gravelly Spot O Landfill A. Lava Flow Marsh or swamp Mine or Quarry O Miscellaneous Water O Perennial Water y Rock Outcrop + Saline Spot Sandy Spot Severely Eroded Spot Q Sinkhole Slide or Slip J, Sodic Spot Custom Soil Resource Report MAP INFORMATION g Spoil Area The soil surveys that comprise your AOI were mapped at 1:15,800. o Stony Spot W Very Stony Spot Warning: Soil Map may not be valid at this scale. wet Spot Enlargement of maps beyond the scale of mapping can cause Other misunderstanding of the detail of mapping and accuracy of soil Special Line Features line placement. The maps do not show the small areas of contrasting soils that could have been shown at a more detailed Water Features scale. Streams and Canals Transportation Please rely on the bar scale on each map sheet for map �..ry Rails measurements. N Interstate Highways Source of Map: Natural Resources Conservation Service ti US Routes Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Major Roads Local Roads Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts Background distance and area. A projection that preserves area, such as the . Aerial Photography Albers equal-area conic projection, should be used if more accurate calculations of distance or area are required. This product is generated from the USDA-NRCS certified data as of the version date(s) listed below. Soil Survey Area: Albemarle County, Virginia Survey Area Data: Version 13, Sep 17, 2019 Soil map units are labeled (as space allows) for map scales 1:50,000 or larger. Date(s) aerial images were photographed: May 20, 2019—Aug 1, 2019 The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background imagery displayed on these maps. As a result, some minor shifting of map unit boundaries may be evident. V1 Custom Soil Resource Report Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 27C Elioak loam, 7 to 15 percent slopes 1.8 43.2% 88 Udorthents, loamy, 2 to 25 percent slopes 1.5 41.1% 93D Watt channery silt loam, 15 to 25 percent slopes 0.6 15.7% Totals for Area of Interest 3.7 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each. A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or Ll Custom Soil Resource Report Albemarle County, Virginia 27C—Elioak loam, 7 to 15 percent slopes Map Unit Setting National map unit symbol: kb8z Mean annual precipitation: 25 to 65 inches Mean annual air temperature: 54 to 59 degrees F Frost -free period: 195 to 231 days Farmland classification: Farmland of statewide importance Map Unit Composition Elioak and similar soils: 80 percent Estimates are based on observations, descriptions, and transacts of the mapunit. Description of Elioak Setting Landform: Hillslopes Landform position (two-dimensional): Summit Landform position (three-dimensional): Interfluve Down -slope shape: Convex Across -slope shape: Convex Parent material: Residuum weathered from mica schist Typical profile H1 - 0 to 8 inches: loam H2 - 8 to 39 inches: silty clay H3 - 39 to 79 inches: silt loam Properties and qualities Slope: 7 to 15 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.20 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Moderate (about 6.6 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 3e Hydrologic Soil Group: B Hydric soil rating: No 10 Custom Soil Resource Report 88—Udorthents, loamy, 2 to 25 percent slopes Map Unit Setting National map unit symbol: 2xxz3 Elevation: 360 to 1,540 feet Mean annual precipitation: 25 to 65 inches Mean annual air temperature: 54 to 59 degrees F Frost -free period: 195 to 231 days Farmland classification: Not prime farmland Map Unit Composition Udorthents and similar soils: 85 percent Minor components: 5 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Udorthents Setting Landform: I nterfluves Landform position (two-dimensional): Summit Landform position (three-dimensional): Interfluve Down -slope shape: Convex Across -slope shape: Convex Parent material: Residuum weathered from granite and gneiss Properties and qualities Slope: 2 to 25 percent Depth to restrictive feature: More than 80 inches Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Minor Components Hatboro, occasionally flooded Percent of map unit: 5 percent Landform: Flood plains Down -slope shape: Linear Across -slope shape: Linear Hydric soil rating: Yes 93D—Watt channery silt loam, 15 to 25 percent slopes Map Unit Setting National map unit symbol: kbg8 11 Custom Soil Resource Report Mean annual precipitation: 25 to 65 inches Mean annual air temperature: 54 to 59 degrees F Frost -free period: 195 to 231 days Farmland classification: Not prime farmland Map Unit Composition Watt and similar soils: 80 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Watt Setting Landform: Hills Landform position (two-dimensional): Backslope Landform position (three-dimensional): Side slope Down -slope shape: Linear Across -slope shape: Convex Parent material: Residuum weathered from graphite schist Typical profile H1 - 0 to 10 inches: channery silt loam H2 - 10 to 18 inches: very channery silt loam H3 - 18 to 28 inches: very channery silt loam H4 - 28 to 79 inches: bedrock Properties and qualities Slope: 15 to 25 percent Depth to restrictive feature: 20 to 40 inches to paralithic bedrock Natural drainage class: Somewhat excessively drained Runoff class: High Capacity of the most limiting layer to transmit water (Ksat): Very low to high (0.00 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Very low (about 2.4 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 6e Hydrologic Soil Group: B Hydric soil rating: No 19 2/6/2020 Precipitation Frequency Data Server NOAA Atlas 14, Volume 2, Version 3 Location name: Charlottesville, Virginia, USA's.,,,,, Latitude: 36.0944°, Longitude:-76.4703° Elevation: 521.72 ft" g a "source: ESRI Maps 1A "" source: USGS��"""" POINT PRECIPITATION FREQUENCY ESTIMATES G.M. Bonin, D. Martin, B. Lin, T. Parzybok, M.Yekta, and D. Riley NOAA, National Weather Service, Silver Spring, Maryland PF tabular I PF graphical I Maps & aerials PF tabular PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)+ Average recurrence interval (years) Duretion + z s +o zs so +oo ���� zoo soo +000 5-min (0.3117-0.390) (0.3078-0.465) (0.443--0.55) (0.497---0 612) (0.557-0687) (0.604-0..747) (0.65-0.93) (0.684-0857) (0.728-0 925) (0.763-0.982) 0.561 0.788 +0-min (0.506-0.62) (0.605-0.0744) (0.7110-0872) (0.7950978) (0.886i10) (0.96-1.19) (1.03-1.28) (1.08-21336) (1. 5-3146) (1.20.i55) 1.46 +5-min (0.32-0778) (0.760-0935) (0. 98-11.10) (1.00.?24) (1: 3--21.39) (1.22--31751) (1.0-1..61) (1.37---1.72) (1. 5--01784) (1.511594) 30-min (0.696207) (1.051..29) (1.274257) (1.8- .79) (1.67-2706) (1. 3-2..27) (1.99-2.47) (2.23-2?67) (2.31 2593) (2.44-3.14) 1.20 4.14 60-min (1.08-1..33) (1.3�62) (1.64-2.01) (1.0-2.34) (2.2�74) (2.8-3..07) (2.74-3940) (2.993074) (3.31-421) (3.57-4.59) 2.19 3.07 3.91 2-hr 3893) (1.27-1.64) (1.54-1599) (19 3-2.49) (2.27 2?91) (2.3-3.47) (3. 3 (3.38-4.41) (3.74-4691) (4. 2--5.62) (4.62 623) 3-hr (1.39- .81) (1.662.19) (2. 02975) (2.453.21) (2.91-3.82) (3. 9�23) (3.67-4.87) (4.06-5.44) (4. 9-6.23) (5: 3-6.0) 6-hr (17 62.28) (2: 52375) (2. 6 3242) (3.131-4A2) (3. 2-4.82) (42 4--5..52) (47 66.26) (5.32-7707) (6.09�23) 8.19 (67 59.26) 3 84 11.2 +2-hr 2 (23-2.89) (2. -3.48) 9 (3.34-4.34) (3.94-5.12) (4.75-621) 73 (5-- 19) . 5 : 6 (68.25) (6.979.41) (8. 0 112) (9.08- 2.8) 24-hr (27 0-3.38) (3.27�09) (4. 65522) (4.91 6015) (5.0-7554) (6. 9 8372) (7.87--010.0) (8.91--131.5) 12.3 (10.4-13.6) (111415.5) 2-day (3: 9-3.97) (3.87-4081) (4. 0-6.10) (5. 4-7.16) (6.94-8.69) (7.92---9.97) (8.96-131.4) (10.1-12.9) (117 52) (13.0-137.1) 3-day (3.43-4.19) (4. 55807) (5.27-6.44) (6 6.633) (7_5 9.17) (8.51- 0.5) (9.63- 2.0) (10.8- 3.6) (125- 6.0) (13.9- 8.0) 4-day (3.67-442) (4.445.34) (5636.78) (6.60-7.95) (7.98 9065) (9. 1011.1) (10.3- 2.6) (11.6-14.3) (13.4-16.8) (14.9-18.9) 8.16 7-day (4.27509) (5: 56.13) (6. 2-07.66) (7.5-8.91) (8.9280.7) (10.1- 2.2) (114?13.8) (12745.6) (14.5-18.1) (16.0. 02) 10-dey (4.875973) (58 56.87) (7.21 8348) (8.31-978) (9.83- 1.6) (11.0-13.1) (12.3-14.7) (13.616.4) (15.4-18.9) (16.9-20.9) 0 20 dey (64 9-744) (77 58.87) (9.34-10.7) (1os- 2.2) (12.3-14.1) (135- 5.7) (14.9-17.3) (162- 8.9) (179-21.2) (19.2 2.9) 30 dey (8.01 9.08) (9.50-10.8) (11.2 2.7) (12.514.2) (142--16.2) (155-107.6) (167- 9.1) (17.9- 0.5) (19.4-2.5) (20.5-3.9) 46-day (10'0.161.3) 1 (11.8-13.3) 1 (13.8- 5.5) 1 (15.3-137.2) 1 (172$ 9.4) 1 (18.6-21.0) 1 (19.9- 2.5) (2121z24.0) (22426.0) (23.627.5) 60-day (11.8--13.2) (13.9-1-5.5) (16.0-107.9) (176 9.7) (196021.9) (2121z 3.6) I (22.4-32) J (237-26.8) I (252 3-28.7) 11 (26.5 02) 1 Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS). Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values. Please refer to NOAA Atlas 14 document for more information. Back to Top PF graphical hfps://hdsc.nws.noaa.govlhdsc/pfds/pfds_Printpage.html?lat=38.0944&Ion=-78.4703&data=depth&units=english&series=pds 1/4