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HomeMy WebLinkAboutWPO202200007 Correspondence 2022-02-28SHIMP ENGINEERING, P.C. Design Focused Engineering February 2151, 2022 Regarding: Borderline — SWM Calculation Packet Dear Reviewer, Enclosed is the stormwater calculation packet for the Borderline Site Plan in Greene County, VA. The purpose of this project is to construct a new public road to serve future commercial lots. This project will disturb a total area of 9.95 acres in total. The conditions of subsection F of 9VAC25-870-65 Water Quality have been met for this site. The VRRM considers the total limits of disturbance for the project when calculating the required load reductions for the development. Using the DEQ VRRM Re -Development Compliance Spreadsheet, the TP Load Reduction Required for this plan is 8.47 lb/yr. This requirement will be satisfied through the purchase of 8.47 nutrient credits. The proposed stormwater design meets the runoff requirements set forth in 9VAC25-870-66-B(3) Water Quantity for two drainage areas as follows. A point of analysis was considered for DA 1 at PDA 1. Drainage area to POA 1 makes up much of the project area and concentrates in an existing channel on the North-East comer of the property. Runoff released by the new detention pond will travel via a new ditch to the POA. Per DEQ specifications, the runoff from the site is released at rates below those required by the Energy Balance Equation. A summary of the 1-yr and 10-yr flows is provided in the table below. A point of analysis was considered for DA 2 at POA 2, located at the culvert below route 29. Area to PDA 2 is reduced post -development and much of the impervious area is removed. As a result the runoff is reduced post -development. Predev [cfs] Qmex [cfs] Poswev [cfs] POA 1-yr 10-yr 1-yr 1-yr 10-yr 1 1.41 19.06 0.37 0.35 15.31 2 1.74 9.50 0.59 0.33 2.53 If you have any questions please do not hesitate to contact me at: Justin@shimp-engineedng.com or by phone at 434-227-5140 ext. 3. Justin Shimp, P.E. Shimp Engineering, P.C. Contents: Pre -Development Runoff Quantity Calculations: Pre-Dev Drainage Map Pre-Dev HydroCAD Report Post-Dev Runoff Quantity Calculations: Post-Dev Drainage Map Energy Balance Equation Summary Post-Dev HydroCAD Report Runoff Quality Calculations: VRRM New Development Spreadsheet Summary Independent Reports: Excerpt from NRCS Soils Report NOAA Precipitation Report Pre -Development Runoff Quantity Calculations: Pre-Dev Drainage Map Pre-Dev HydroCAD Report op, 150 0 150 300 450 SCALE: 1"=150' ri v A------ ----- ol L z u P4 DA2 3.85 AC CN=64 PREDEV DRAINAGE MAP BORDERLINE REVISION DATE: 08/24/2021 Lu Lu z z Lu LAND PLANNING PROJECT MANAGEMENT 912 E HIGH STREET, CHARLOTTESVILLE VA22902 -434-227.5140 -JUSTIN @SHIM P-ENGINEER I NG.00M Borderline - Pre Dev PREDEV GREENE EDGE Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD® 9.10 s/n 07054 © 2010 HydroCAD Software Solutions LLC Paae 2 Area Listing (all nodes) Area (acres) CN Desaiption (subcatchment-numbers) 11.610 55 Woods, Good, HSG B (1 S, 3S) 4.830 61 >75%Grass cover, Good, HSG B (1S, 3S) 0.790 98 Impervious (1S, 3S) 17.230 TOTAL AREA Borderline - Pre Dev PREDEV GREENE EDGE Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD® 9.10 s/n 07054 © 2010 HydroCAD Software Solutions LLC Paae 3 Soil Listing (all nodes) Area Soil Subcatchment (acres) Group Numbers 0.000 HSG A 16.440 HSG B 1S, 3S 0.000 HSG C 0.000 HSG D 0.790 Other 1S, 3S 17.230 TOTAL AREA Borderline - Pre Dev PREDEV GREENE EDGE Type // 24-hr 1-yr Rainfall=2.94" Prepared by Shimp Engineering Printed 9/14/2021 HydroCADO 9.10 s/n 07054 © 2010 HydroCAD Software Solutions LLC Page 4 Time span=5.00-48.00 hrs, dt=0.05 hrs, 861 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment1S:DA1 Runoff Area=13.280ac 2.26%Impervious Runoff Depth=0.23" Tc=16.5 min CN=57 Runoff=1.41 cfs 0.253 of Subcatchment3S:DA2 Runoff Area=3.950ac 12.41%Impervious Runoff Depth=0.44" Tc=13.4 min CN=64 Runoff=1.74 cfs 0.146 of Link2L: POA1 Inflow=1.41 cfs 0.253 of Primary=1.41 cfs 0.253 of Link 4L: POA2 Inflow=1.74 cfs 0.146 of Primary=1.74 cfs 0.146 of Total Runoff Area=17.230 ac Runoff Volume = 0.398 of Average Runoff Depth = 0.28" 95.41% Pervious=16.440 ac 4.59% Impervious = 0.790 ac Borderline - Pre Dev PREDEV GREENE EDGE Type // 24-hr 1-yr Rainfa11=2.94" Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD@ 9.10 s/n 07054 @ 2010 HydroCAD Software Solutions LLC Page 5 Summary for Subcatchment 1S: DA1 Runoff = 1.41 cfs @ 12.17 hrs, Volume= 0.253 af, Depth= 0.23" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 1-yr Rainfall=2.94" 0.300 98 Impervious 2.730 61 >75%Grass cover, Good, HSG B 10.250 55 Woods, Good, HSG B 13.280 57 Weighted Average 12.980 97.74% Pervious Area 0.300 2.26% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (f1sec) (cfs) 16.5 Direct Entry, Summary for Subcatchment 3S: DA2 Runoff = 1.74 cfs @ 12.09 hrs, Volume-- 0.146 at Depth= 0.44" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 1-yr Rainfall=2.94" Area (ac) CN 0.490 98 Impervious 2.100 61 >75%Grass cover, Good, HSG B 1.360 55 Woods, Good, HSG B 3.950 64 Weighted Average 3.460 87.59% Pervious Area 0.490 12.41 % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 13.4 Direct Entry, Summary for Link 2L: POA1 Inflow Area = 13.280 ars 2.26%Impervious, Inflow Depth = 0.23" for 1-yr event Inflow = 1.41 cfs @ 12.17 hrs, Volume= 0.253 of Primary = 1.41 cfs @ 12.17 hrs, Volume= 0.253 at Atten= 01/q Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Borderline - Pre Dev PREDEV GREENE EDGE Type // 24-hr 1-yr Rainfa11=2.94" Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD® 9.10 s/n 07054 © 2010 HydroCAD Software Solutions LLC Page 6 Summary for Link 4L: POA2 Inflow Area = 3.950 ac 12.41%Imperviou4 Inflow Depth = 0.44" for 1-yr event Inflow = 1.74 cfs @ 12.09 hrs Volume= 0.146 of Primary = 1.74 cfs @ 12.09 hm Volume-- 0.146 af, A@en= 0% Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Borderline - Pre Dev PREDEV GREENE EDGE Type 1124-hr 10-yr Rainfall=5.37" Prepared by Shimp Engineering Printed 9/14/2021 HydroCADO 9.10 s/n 07054 © 2010 HydroCAD Software Solutions LLC Paoe 7 Time span=5.00-48.00 hrs, dt=0.05 hrs, 861 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment1S:DA1 Runoff Area= 13.280 ac 2.26%Impervious Runoff Depth=1.31" Tc=16.5 min CN=57 Runoff=19.06 cfs 1.447 of Subcatchment3S:DA2 Runoff Area=3.950ac 12.41%Impervious Runoff Depth=1.83" Tc=13.4 min CN=64 Runoff=9.50 cfs 0.601 of Link 2L: POA1 Inflow=19.06 cfs 1.447 of Primary=19.06 cfs 1.447 of Link 4L: POA2 Inflow=9.50 cfs 0.601 of Primary=9.50 cfs 0.601 of Total Runoff Area=17.230 ac Runoff Volume = 2.048 of Average Runoff Depth =1.43" 95.41% Pervious=16.440 ac 4.59% Impervious = 0.790 ac Borderline - Pre Dev PREDEV GREENE EDGE Type // 24-hr 10-yr Rainfall=-5.37" Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD@ 9.10 s/n 07054 @ 2010 HydroCAD Software Solutions LLC Page 8 Summary for Subcatchment 1S: DA1 Runoff = 19.06 cis@ 12.11 hrs, Volume= 1.447 af, Depth= 1.31" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr Rainfall=5.37" 0.300 98 Impervious 2.730 61 >75%Grass cover, Good, HSG B 10.250 55 Woods, Good, HSG B 13.280 57 Weighted Average 12.980 97.74% Pervious Area 0.300 2.26% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (f1sec) (cfs) 16.5 Direct Entry, Summary for Subcatchment 3S: DA2 Runoff = 9.50 cfs @ 12.06 hrs, Volume= 0.601 at Depth= 1.83" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr Rainfall=5.37" Area (ac) CN 0.490 98 Impervious 2.100 61 >75%Grass cover, Good, HSG B 1.360 55 Woods, Good, HSG B 3.950 64 Weighted Average 3.460 87.59% Pervious Area 0.490 12.41 % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 13.4 Direct Entry, Summary for Link 2L: POA1 Inflow Area = 13.280 ars 2.26%Impervious, Inflow Depth = 1.31" for 10-yr event Inflow = 19.06 cfs@ 12.11 hrs, Volume= 1.447 of Primary = 19.06 cis @ 12.11 hrs, Volume= 1.447 af, Aden= 0% Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Borderline - Pre Dev PREDEV GREENE EDGE Type // 24-hr 10-yr Rainfall=-5.37" Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD® 9.10 s/n 07054 © 2010 HydroCAD Software Solutions LLC Page 9 Summary for Link 4L: POA2 Inflow Area = 3.950 ac 12.41%Imperviou4 Inflow Depth = 1.83" for 10-yr event Inflow = 9.50 cfs @ 12.06 hrs Volume= 0.601 of Primary = 9.50 cfs @ 12.06 hm Volume-- 0.601 af, Atten= 0% Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Borderline - Pre Dev PREDEV GREENE EDGE Type // 24-hr 100-yr Rainfall=8.79" Prepared by Shimp Engineering Printed 9/14/2021 HydroCADO 9.10 s/n 07054 © 2010 HydroCAD Software Solutions LLC Page 10 Time span=5.00-48.00 hrs, dt=0.05 hrs, 861 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment1S:DA1 Runoff Area=13.280ac 2.26%Impervious Runoff Depth=3.58" Tc=16.5 min CN=57 Runoff=57.51 cfs 3.958 of Subcatchment3S:DA2 Runoff Area=3.950ac 12.41%Impervious Runoff Depth=4.42" Tc=13.4 min CN=64 Runoff=23.68 cfs 1.455 of Link2L: POA1 Inflow=57.51 cfs 3.958 of Primary=57.51 cfs 3.958 of Link 4L: POA2 Inflow=23.68 cfs 1.455 of Primary=23.68 cfs 1.455 of Total Runoff Area=17.230 ac Runoff Volume = 5.413 of Average Runoff Depth = 3.77" 95.41% Pervious=16.440 ac 4.59% Impervious = 0.790 ac Borderline - Pre Dev PREDEV GREENE EDGE Type 1124-hr 100-yr Rainfall=8.79" Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD@ 9.10 s/n 07054 @ 2010 HydroCAD Software Solutions LLC Page 11 Summary for Subcatchment 1S: DA1 Runoff = 57.51 cis@ 12.10 hrs, Volume= 3.958 af, Depth= 3.58" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100-yr Rainfall=8.79" 0.300 98 Impervious 2.730 61 >75%Grass cover, Good, HSG B 10.250 55 Woods, Good, HSG B 13.280 57 Weighted Average 12.980 97.74% Pervious Area 0.300 2.26% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (f1sec) (cfs) 16.5 Direct Entry, Summary for Subcatchment 3S: DA2 Runoff = 23.68 cfs@ 12.06 hrs, Volume= 1.455 at Depth= 4.42" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Type II 24-hr 100-yr Rainfall=8.79" Area (ac) CN 0.490 98 Impervious 2.100 61 >75%Grass cover, Good, HSG B 1.360 55 Woods, Good, HSG B 3.950 64 Weighted Average 3.460 87.59% Pervious Area 0.490 12.41 % Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cis) 13.4 Direct Entry, Summary for Link 2L: POA1 Inflow Area = 13.280 ars 2.26%Impervious, Inflow Depth = 3.58" for 100-yr event Inflow = 57.51 cis@ 12.10 hrs, Volume= 3.958 of Primary = 57.51 cis@ 12.10 hrs, Volume= 3.958 af, Atten= 0% Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Borderline - Pre Dev PREDEV GREENE EDGE Type 1124-hr 100-yr Rainfall=8.79" Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD® 9.10 s/n 07054 © 2010 HydroCAD Software Solutions LLC Page 12 Summary for Link 4L: POA2 Inflow Area = 3.950 ac 12.41%Imperviou4 Inflow Depth = 4.42" for 100-yr event Inflow = 23.68 cfs@ 12.06 hrs Volume= 1.455 of Primary = 23.68 cfs @ 12.06 hm Volume-- 1.455 af, Atten= 0% Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-48.00 hrs, dt= 0.05 hrs Post-Dev Runoff Quantity Calculations: Post-Dev Drainage Map Energy Balance Equation Summary Post-Dev HydroCAD Report A HSG B ✓/' :. It HSG Blt i / 1 S 1 1 Y 1 - 1 U . i / � sx I 1 � +\ ♦ I HSG A 150 r i II, ♦ I � �. , s� �� ; 141 �• � S ( Ilk• 1 w A 1 - . \ - i LU Lu LU POSTDEV DRAINAGE MAP = 30_ 0 450 BORDERLINE H REVISION DATE:09/14/2021 LAND PLANNING • PROJECT MANAGEMENT 912 E HIGH STREET, CHARLOTTESVILLE VA 22902 • 434-227.5140 • JUSTIN@SHIMR-ENGINEERING.COM e ft 150 0 150 300 450 LmLm M m m SCALE: 1 "= 150' ------ ------ ------ ------ H ,� �� , - - ----------- - ftt-j Di CH'S LU ui LU DITCH DRAINAGE MAP BORDERLINE REVISION DATE: 09114/2021 LAND PLANNING - PROJECT MANAGEMENT 912 E HIGH STREET, CHARLOTTESVILLE VA 22902 - 434-227-5140 - JUSTIN@SHIMP-ENGINEERING.COV Energy Balance Equation Summary Greene Edge (POA 1) Qdeveloped�5 I.F. (Qpre-developed RVPre-Developed) Rydeveloped Qdeveloped�5 Qforested RVforested Rydeveloped Qpre-developed = 1.41 "Pre -Developed = 0.253 Max Qde eh = 0.37 cfs RVDeveloped = 0.775 Achieved Post-Dev Max Runoff 01yr = 0.35cfs. Site complies with 9VAC25-870-66-(3)A Maximum Qioyr = 19.06cfs (predev) Achieved 010yr = 15.31cfs Energy Balance Equation Summary Greene Edge (POA 2) Qdeveloped!5 I.F. *(Qpre-developed*RVPre-Developed)/Rydeveloped Qdeveloped�5 Qforested RVforested Rydeveloped Qpre-developed = 1.740 "Pre -Developed = 0.146 Max Qdeveh = 0.59 cfs "Developed = 0.342 Achieved Post-Dev Max Runoff Qlyr = 0.33cfs. Site complies with 9VAC25-870-66-(3)A Maximum Qioyr = 9.50cfs (predev) Achieved 010yr = 2.53cfs Post Development HydroCAD Report Borderline 1S DA1 - FUL BUILD OUT 1P DA2 - FULL BUILD 2P DET PO N 2 FINAL DET PON 1 FINAL iL 3S 2L POA 1 OFFSITE POA 2 Subcat Reach Aon Link Borderline - Post Dev POSTDEV GREENE EDGE Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD® 9.10 s/n 07054 © 2010 HydroCAD Software Solutions LLC Paae 2 Area Listing (all nodes) Area CN Desaiption (acres) (subcatchment-numbers) 5.400 55 Woods, Good, HSG B (1 S, 3S) 9.700 61 >75%Grass cover, Good, HSG B (1S, 2S) 5.400 98 Impervious (1S, 2S) 20.500 TOTAL AREA Borderline - Post Dev POSTDEV GREENE EDGE Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD® 9.10 s/n 07054 © 2010 HydroCAD Software Solutions LLC Paae 3 Soil Listing (all nodes) Area Soil Subcatchment (acres) Group Numbers 0.000 HSG A 15.100 HSG B 1S, 2S, 3S 0.000 HSG C 0.000 HSG D 5.400 Other 1S, 2S 20.500 TOTAL AREA Borderline - Post Dev POSTDEV GREENE EDGE Type 1/ 24-hr 1-yr Rainfa11=2.94" Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD® 9.10 s/n 07054 © 2010 HydroCAD Software Solutions LLC Paae 4 Time span=5.00-64.00 hrs, dt=0.05 hrs, 1181 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment1S:DA1-FULL BUILD OUT Runoff Area=15.610ac 23.77%Impervious Runoff Depth=0.60" Subcatchment2S: DA2 - FULL BUILD OUT Subcatchment 3S: OFFSITE Pond 1P: DET POND 1 FINAL Pond 2P: DET POND 2 FINAL Link 1 L: POA 1 Link2L: POA 2 Tc=20.0 min CN=68 Runoff=8.44 cfs 0.775 of Runoff Area=3.980ac 42.46%Impervious Runoff Depth=1.03" Tc=15.1 min CN=77 Runoff=5.09 cfs 0.342 of Runoff Area=0.910 ac 0.00% Impervious Runoff Depth=0.18" Tc=8.0 min CN=55 Runoff=0.08 cfs 0.014 of Peak EIev=559.70' Storage=20,413 cf Inflow=8.44 cfs 0.775 of Outflow=0.34 cfs 0.774 of Peak EIev=559.45' Storage=7,395 cf Inflow=5.09 cfs 0.342 of Outflow=0.33 cfs 0.341 of Inflow=0.35 cfs 0.787 of Primary=0.35 cfs 0.787 of Inflow=0.33 cfs 0.341 of Primary=0.33 cfs 0.341 of Total Runoff Area = 20.500 ac Runoff Volume =1.130 of Average Runoff Depth = 0.66" 73.66% Pervious=15.100 ac 26.34% Impervious = 5.400 ac Borderline - Post Dev POSTDEV GREENE EDGE Type 1/ 24-hr 1-yr Rainfa11=2.94" Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD® 9.10 s/n 07054 © 2010 HydroCAD Software Solutions LLC Pace 5 Summary for Subcatchment 1S: DAt - FULL BUILD OUT Runoff = 8.44 cfs @ 12.16 hrs, Volume= 0.775 at Depth= 0.60" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-64.00 hrs, dt= 0.05 hrs Type II 24-hr 1-yr Rainfall=2.94" * 3.710 98 Impervious 7.410 61 >75%Grass cover, Good, HSG B 4.490 55 Woods, Good, HSG B 15.610 68 Weighted Average 11.900 76.23% Pervious Area 3.710 23.77% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (fUsec) (cfs) 20.0 Direct Entry, Summary for Subcatchment 2S: DA2 - FULL BUILD OUT Runoff = 5.09 cfs @ 12.08 hrs, Volume= 0.342 at Depth= 1.03" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-64.00 hrs, dt= 0.05 hrs Type II 24-hr 1-yr Rainfall=2.94" Area (ac) CN * 1.690 98 Impervious 2.290 61 >75%Grass cover, Good, HSG B 0.000 55 Woods, Good, HSG B 3.980 77 Weighted Average 2.290 57.54% Pervious Area 1.690 42.46% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 15.1 Direct Entry, Summary for Subcatchment 3S: OFFSITE Runoff = 0.08 cfs @ 12.06 hrs, Volume= 0.014 at Depth= 0.18" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-64.00 hrs, dt= 0.05 hrs Type 11 24-hr 1-yr Rainfall=2.94" Borderline - Post Dev POSTDEV GREENE EDGE Type/1 24-hr 1-yr Rainfalf=2.94" Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD® 9.10 s/n 07054 © 2010 HydroCAD Software Solutions LLC Page 6 0.000 98 Impervious 0.000 61 >75%Grass cover, Good, HSG B 0.910 55 Woods, Good, HSG B 0.910 55 Weighted Average 0.910 100.00% Pervious Area Tc Length Slope Velocity Capacity Description 8.0 Direct Entry, Summary for Pond 1 P: DET POND 1 FINAL Inflow Area = 15.610 aq 23.77%Impervious, Inflow Depth = 0.60" for 1-yr event Inflow = 8.44 cfs @ 12.16 hrs, Volume= 0.775 of Outflow = 0.34 cfs @ 19.45 hm Volume= 0.774 af, Atten= 96% Lag= 437.7 min Primary = 0.34 cfs @ 19.45 hrs, Volume= 0.774 of Routing by Stor-Ind method, Time Span= 5.00-64.00 hrs, dt= 0.05 hrs Peak Elev= 559.70'@ 19.45 hrs Surf.Area= 6,873 sf Storage= 20,413 cf Plug -Flow detention time=778.2 min calculated for 0.774 of (100%of inflow) Center -of -Mass det. time=777.0 min (1,678.0 - 900.9 ) Volume Invert Avail.Storage Storage Description #1 556.00' 108,550 cf Custom Stage Data (Prismatic)Listed below(Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 556.00 4,230 0 0 558.00 5,590 9,820 9,820 560.00 7,100 12,690 22,510 562.00 8,750 15,850 38,360 564.00 10,550 19,300 57,660 566.00 12,580 23,130 80,790 568.00 15,180 27,760 108,550 Device Routing Invert Outlet Devices #1 Primary 556.00' 24.0" Round Culvert L= 95.0' CPP, mitered to conform to fill, Ke= 0.700 Inlet / Outlet Invert= 556.00' / 554.00' S= 0.0211 'f Cc= 0.900 n= 0.013 Corrugated PE, smooth interior #2 Device 1 556.00' 2.6" Vert.1-yr Orifice C= 0.600 #3 Device 1 562.50' 48.0" Horiz. Standpipe C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=0.34 cis@ 19.45 hrs HW=559.70' (Free Discharge) Culvert (Passes 0.34 cis of 21.93 cfs potential flow) 2=1-yr Orifice (Orifice Controls 0.34 cfs @ 9.12 fps) 3=Standpipe ( Controls 0.00 cis) Borderline - Post Dev POSTDEV GREENE EDGE Type // 24-hr 1-yr RainfaU-2.94" Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD® 9.10 s/n 07054 © 2010 HydroCAD Software Solutions LLC Page 7 Summary for Pond 2P: DET POND 2 FINAL Inflow Area = 3.980 aq 42.46%Impervious, Inflow Depth = 1.03" for 1-yr event Inflow = 5.09 cfs @ 12.08 hrs, Volume= 0.342 of Outflow = 0.33 cfs @ 13.80 hrs, Volume= 0.341 af, Atten= 94% Lag=102.9 min Primary = 0.33 cfs @ 13.80 hrs, Volume= 0.341 of Routing by Stor-Ind method, Time Span= 5.00-64.00 hrs, dt= 0.05 hrs Peak Elev= 559.45'@ 13.80 hrs Surf.Area= 5,581 sf Storage= 7,395 cf Plug -Flow detention time=314.6 min calculated for 0.341 of (100%of inflow) Center -of -Mass det time=315.8 min (1,178.2 - 862.4) Volume Invert Avail.Storage Storage Description #1 558.00' 57,800 cf Custom Stage Data (Prismatic)Listed below(Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 558.00 4,650 0 0 566.00 9,800 57,800 57,800 Device Routing Invert Outlet Devices #1 Primary 558.00' 18.0" Round Culvert L= 49.9' CPP, mitered to conform to fill, Ke= 0.700 Inlet/Outlet Invert= 558.00'/ 557.72' S=0.0056'f Cc=0.900 n= 0.013 Corrugated PE, smooth interior #2 Device 1 558.00' 3.3" Vert. 1 •yr Orifice C= 0.600 #3 Device 1 561.50' 36.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=0.33 cis@ 13.80 hrs HW=559.45' (Free Discharge) Culvert (Passes 0.33 cis of 5.65 cfs potential flow) 2=1 •yr Orifice (Orifice Controls 0.33 cfs @ 5.51 fps) 3=Orifice/Grate ( Controls 0.00 cis) Summary for Link 1L: POA 1 Inflow Area = 16.520 aq 22.46%Impervious, Inflow Depth > 0.57" for 1-yr event Inflow = 0.35 cfs @ 18.55 hm Volume-- 0.787 of Primary = 0.35 cfs @ 18.55 hrs, Volume= 0.787 af, Aden= 01/c, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-64.00 hrs, dt= 0.05 hrs Summary for Link 2L: POA 2 Inflow Area = 3.980 ac 42.46%Impervious, Inflow Depth > 1.03" for 1-yr event Inflow = 0.33 cfs @ 13.80 hrs, Volume= 0.341 of Primary = 0.33 cfs @ 13.80 hrs, Volume= 0.341 af, Aden= 01/c, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-64.00 hrs, dt= 0.05 hrs Borderline - Post Dev POSTDEV GREENE EDGE Type // 24-hr 10-yr Rainfall=-5.37" Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD® 9.10 s/n 07054 © 2010 HydroCAD Software Solutions LLC Paae 8 Time span=5.00-64.00 hrs, dt=0.05 hrs, 1181 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment1S:DA1-FULL BUILD OUT Runoff Area=15.610ac 23.77%Impervious Runoff Depth=2.15" Subcatchment2S: DA2 - FULL BUILD OUT Subcatchment 3S: OFFSITE Pond 1P: DET POND 1 FINAL Pond 2P: DET POND 2 FINAL Link 1 L: POA 1 Link2L: POA 2 Tc=20.0 min CN=68 Runoff=36.31 cfs 2.793 of Runoff Area=3.980ac 42.46%Impervious Runoff Depth=2.94" Tc=15.1 min CN=77 Runoff=14.95 cfs 0.974 of Runoff Area=0.910 ac 0.00% Impervious Runoff Depth=1.17" Tc=8.0 min CN=55 Runoff=1.59 cfs 0.089 of Peak EIev=563.00' Storage=47,562 cf Inflow=36.31 cfs 2.793 of Outflow=15.06 cfs 2.759 of Peak EIev=561.66' Storage=21,323 cf Inflow=14.95 cfs 0.974 of Outflow=2.53 cfs 0.973 of Inflow=15.31 cfs 2.848 of Primary=15.31 cfs 2.848 of Inflow=2.53 cfs 0.973 of Primary=2.53 cfs 0.973 of Total Runoff Area = 20.500 ac Runoff Volume = 3.856 of Average Runoff Depth = 2.26" 73.66% Pervious=15.100 ac 26.34% Impervious = 5.400 ac Borderline - Post Dev POSTDEV GREENE EDGE Type // 24-hr 10-yr Rainfall=-5.37" Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD® 9.10 s/n 07054 © 2010 HydroCAD Software Solutions LLC Pace 9 Summary for Subcatchment 1S: DAt - FULL BUILD OUT Runoff = 36.31 cfs@ 12.14 hrs, Volume= 2.793 at Depth= 2.15" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-64.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr Rainfall=5.37" * 3.710 98 Impervious 7.410 61 >75%Grass cover, Good, HSG B 4.490 55 Woods, Good, HSG B 15.610 68 Weighted Average 11.900 76.23% Pervious Area 3.710 23.77% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (fUsec) (cfs) 20.0 Direct Entry, Summary for Subcatchment 2S: DA2 - FULL BUILD OUT Runoff = 14.95 cfs@ 12.07 hrs, Volume= 0.974 at Depth= 2.94" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-64.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr Rainfall=5.37" Area (ac) CN * 1.690 98 Impervious 2.290 61 >75%Grass cover, Good, HSG B 0.000 55 Woods, Good, HSG B 3.980 77 Weighted Average 2.290 57.54% Pervious Area 1.690 42.46% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 15.1 Direct Entry, Summary for Subcatchment 3S: OFFSITE Runoff = 1.59 cfs @ 12.01 hrs, Volume= 0.089 at Depth= 1.17" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-64.00 hrs, dt= 0.05 hrs Type 11 24-hr 10-yr Rainfall=5.37" Borderline - Post Dev POSTDEV GREENE EDGE Type // 24-hr 10-yr Rainfall=-5.37" Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD@ 9.10 s/n 07054 @ 2010 HydroCAD Software Solutions LLC Page 10 0.000 98 Impervious 0.000 61 >75%Grass cover, Good, HSG B 0.910 55 Woods, Good, HSG B 0.910 55 Weighted Average 0.910 100.00% Pervious Area Tc Length Slope Velocity Capacity Description 8.0 Direct Entry, Summary for Pond 1 P: DET POND 1 FINAL Inflow Area = 15.610 aq 23.77%Impervious, Inflow Depth = 2.15" for 10-yr event Inflow = 36.31 cfs@ 12.14 hrs, Volume= 2.793 of Outflow = 15.06 cfs@ 12.41 hrs, Volume= 2.759 af, Atten= 59% Lar 16.6 min Primary = 15.06 cfs@ 12.41 hrs, Volume= 2.759 of Routing by Stor-Ind method, Time Span= 5.00-64.00 hrs, dt= 0.05 hrs Peak Elev= 563.00'@ 12.41 hrs Surf.Area= 9,650 sf Storage= 47,562 cf Plug -Flow detention time=592.0 min calculated for 2.756 of (99% of inflow) Center -of -Mass det. time=586.2 min (1,444.7 - 858.5 ) Volume Invert Avail.Storage Storage Description #1 556.00' 108,550 cf Custom Stage Data (Prismatic)Listed below(Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 556.00 4,230 0 0 558.00 5,590 9,820 9,820 560.00 7,100 12,690 22,510 562.00 8,750 15,850 38,360 564.00 10,550 19,300 57,660 566.00 12,580 23,130 80,790 568.00 15,180 27,760 108,550 Device Routing Invert Outlet Devices #1 Primary 556.00' 24.0" Round Culvert L= 95.0' CPP, mitered to conform to fill, Ke= 0.700 Inlet / Outlet Invert= 556.00' / 554.00' S= 0.0211 'f Cc= 0.900 n= 0.013 Corrugated PE, smooth interior #2 Device 1 556.00' 2.6" Vert.1-yr Orifice C= 0.600 #3 Device 1 562.50' 48.0" Horiz. Standpipe C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=14.72 cfs@ 12.41 hrs HW=562.99' (Free Discharge) Culvert (Passes 14.72 cis of 32.68 cfs potential flow) 2=1-yr Orifice (Orifice Controls 0.47 cfs @ 12.63 fps) 3=Standpipe (Weir Controls 14.25 cfs @ 2.30 fps) Borderline - Post Dev POSTDEV GREENE EDGE Type // 24-hr 10-yr Rainfall=-5.37" Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD® 9.10 s/n 07054 © 2010 HydroCAD Software Solutions LLC Page 11 Summary for Pond 2P: DET POND 2 FINAL Inflow Area = 3.980 aq 42.46%Imperviou4 Inflow Depth = 2.94" for 10-yr event Inflow = 14.95 cfs@ 12.07 hrs Volume= 0.974 of Outflow = 2.53 cfs @ 12.52 hrs Volume= 0.973 af, Atten= 83% Lag= 27.1 min Primary = 2.53 cfs @ 12.52 hrs Volume= 0.973 of Routing by Stor-Ind method, Time Span= 5.00-64.00 hrs, dt= 0.05 hrs Peak Elev= 561.66'@ 12.52 hrs Surf.Area= 7,005 sf Storage= 21,323 cf Plug -Flow detention time=439.3 min calculated for 0.973 of (100%of inflow) Center -of -Mass det. time=438.9 min (1,270.7 - 831.8 ) Volume Invert Avail.Storage Storage Description #1 558.00' 57,800 cf Custom Stage Data (Prismatic)Listed below(Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 558.00 4,650 0 0 566.00 9,800 57,800 57,800 Device Routing Invert Outlet Devices #1 Primary 558.00' 18.0" Round Culvert L= 49.9' CPP, mitered to conform to fill, Ke= 0.700 Inlet/Outlet Invert= 558.00'/ 557.72' S=0.0056'f Cc=0.900 n= 0.013 Corrugated PE, smooth interior #2 Device 1 558.00' 3.3" Vert. 1 •yr Orifice C= 0.600 #3 Device 1 561.50' 36.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=2.46 cis@ 12.52 hrs HW=561.66' (Free Discharge) Culvert (Passes 2.46 cis of 12.80 cfs potential flow) 2=1 •yr Orifice (Orifice Controls 0.54 cfs @ 9.03 fps) 3=Orifice/Grate (Weir Controls 1.93 cfs @ 1.30 fps) Summary for Link 1L: POA 1 Inflow Area = 16.520 aq 22.46%Impervious Inflow Depth > 2.07" for 10-yr event Inflow = 15.31 cfs@ 12.41 hm Volume-- 2.848 of Primary = 15.31 cfs @ 12.41 hrs, Volume= 2.848 af, Aden= 01/c, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-64.00 hrs, dt= 0.05 hrs Summary for Link 2L: POA 2 Inflow Area = 3.980 aq 42.46%Impervious Inflow Depth > 2.93" for 10-yr event Inflow = 2.53 cfs @ 12.52 hrs Volume= 0.973 of Primary = 2.53 cfs @ 12.52 hrs Volume= 0.973 af, Atten= 01/c, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-64.00 hrs, dt= 0.05 hrs Borderline - Post Dev POSTDEV GREENE EDGE Type 1124-hr 100-yr Rainfall=8.79" Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD® 9.10 s/n 07054 © 2010 HydroCAD Software Solutions LLC Paoe 12 Time span=5.00-64.00 hrs, dt=0.05 hrs, 1181 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment1S:DA1-FULL BUILD OUT Runoff Area=15.610ac 23.77%Impervious Runoff Depth=4.91" Subcatchment2S: DA2 - FULL BUILD OUT Subcatchment 3S: OFFSITE Pond 1P: DET POND 1 FINAL Pond 2P: DET POND 2 FINAL Link 1 L: POA 1 Link2L: POA 2 Tc=20.0 min CN=68 Runoff=84.67 cfs 6.383 of Runoff Area=3.980ac 42.46%Impervious Runoff Depth=6.00" Tc=15.1 min CN=77 Runoff=30.13 cfs 1.991 of Runoff Area=0.910 ac 0.00% Impervious Runoff Depth=3.34" Tc=8.0 min CN=55 Runoff--4.95 cfs 0.253 of Peak Elev=566.38' Storage=85,723 cf Inflow=84.67 cfs 6.383 of Outflow=40.89 cfs 6.347 of Peak Elev=562.92' Storage=30,694 cf Inflow=30.13 cfs 1.991 of Outflow=15.34 cfs 1.991 of Inflow=41.61 cfs 6.601 of Primary-41.61 cfs 6.601 of Inflow=15.34 cfs 1.991 of Primary=15.34 cfs 1.991 of Total Runoff Area = 20.500 ac Runoff Volume = 8.627 of Average Runoff Depth = 5.05" 73.66% Pervious=15.100 ac 26.34% Impervious = 5.400 ac Borderline - Post Dev POSTDEV GREENE EDGE Type 1124-hr 100-yr Rainfall=8.79" Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD® 9.10 s/n 07054 © 2010 HydroCAD Software Solutions LLC Page 13 Summary for Subcatchment 1S: DAt - FULL BUILD OUT Runoff = 84.67 cfs@ 12.13 hrs, Volume= 6.383 at Depth= 4.91" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-64.00 hrs, dt= 0.05 hrs Type II 24-hr 100-yr Rainfall=8.79" * 3.710 98 Impervious 7.410 61 >75%Grass cover, Good, HSG B 4.490 55 Woods, Good, HSG B 15.610 68 Weighted Average 11.900 76.23% Pervious Area 3.710 23.77% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (fUsec) (cfs) 20.0 Direct Entry, Summary for Subcatchment 2S: DA2 - FULL BUILD OUT Runoff = 30.13 cfs@ 12.07 hrs, Volume-- 1.991 at Depth= 6.00" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-64.00 hrs, dt= 0.05 hrs Type II 24-hr 100-yr Rainfall=8.79" Area (ac) CN * 1.690 98 Impervious 2.290 61 >75%Grass cover, Good, HSG B 0.000 55 Woods, Good, HSG B 3.980 77 Weighted Average 2.290 57.54% Pervious Area 1.690 42.46% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 15.1 Direct Entry, Summary for Subcatchment 3S: OFFSITE Runoff = 4.95 cfs @ 12.00 hrs, Volume= 0.253 at Depth= 3.34" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-64.00 hrs, dt= 0.05 hrs Type 11 24-hr 100-yr Rainfall=8.79" Borderline - Post Dev POSTDEV GREENE EDGE Type 1124-hr 100-yr Rainfall=8.79" Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD@ 9.10 s/n 07054 @ 2010 HydroCAD Software Solutions LLC Page 14 0.000 98 Impervious 0.000 61 >75%Grass cover, Good, HSG B 0.910 55 Woods, Good, HSG B 0.910 55 Weighted Average 0.910 100.00% Pervious Area Tc Length Slope Velocity Capacity Description 8.0 Direct Entry, Summary for Pond 1 P: DET POND 1 FINAL Inflow Area = 15.610 aq 23.77%Impervious, Inflow Depth = 4.91" for 100-yr event Inflow = 84.67 cis@ 12.13 hrs, Volume= 6.383 of Outflow = 40.89 cfs @ 12.35 hrs, Volume= 6.347 af, Atten= 52% Lag=13.4 min Primary = 40.89 cfs@ 12.35 hrs, Volume= 6.347 of Routing by Stor-Ind method, Time Span= 5.00-64.00 hrs, dt= 0.05 hrs Peak Elev= 566.38'@ 12.35 hrs Surf.Area=13,080 sf Storage= 85,723 cf Plug -Flow detention time=270.9 min calculated for 6.347 of (99% of inflow) Center -of -Mass det. time=267.5 min (1,102.1 - 834.6 ) Volume Invert Avail.Storage Storage Description #1 556.00' 108,550 cf Custom Stage Data (Prismatic)Listed below(Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 556.00 4,230 0 0 558.00 5,590 9,820 9,820 560.00 7,100 12,690 22,510 562.00 8,750 15,850 38,360 564.00 10,550 19,300 57,660 566.00 12,580 23,130 80,790 568.00 15,180 27,760 108,550 Device Routing Invert Outlet Devices #1 Primary 556.00' 24.0" Round Culvert L= 95.0' CPP, mitered to conform to fill, Ke= 0.700 Inlet / Outlet Invert= 556.00' / 554.00' S= 0.0211 'f Cc= 0.900 n= 0.013 Corrugated PE, smooth interior #2 Device 1 556.00' 2.6" Vert.1-yr Orifice C= 0.600 #3 Device 1 562.50' 48.0" Horiz. Standpipe C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=40.89 cfs@ 12.35 hrs HW=566.38' (Free Discharge) Culvert (Inlet Controls 40.89 cfs @ 13.01 fps) 2=1-yr Orifice (Passes < 0.57 cis potential flow) 3=Standpipe (Passes < 119.24 cfs potential flow) Borderline - Post Dev POSTDEV GREENE EDGE Type 1124-hr 100-yr Rainfall=8.79" Prepared by Shimp Engineering Printed 9/14/2021 HydroCAD® 9.10 s/n 07054 © 2010 HydroCAD Software Solutions LLC Page 15 Summary for Pond 2P: DET POND 2 FINAL Inflow Area = 3.980 aq 42.46%Imperviou4 Inflow Depth = 6.00" for 100-yr event Inflow = 30.13 cfs@ 12.07 hrs Volume= 1.991 of Outflow = 15.34 cfs @ 12.23 hrs Volume= 1.991 af, Atten= 491/a Lag= 9.9 min Primary = 15.34 cfs@ 12.23 hrs Volume= 1.991 of Routing by Stor-Ind method, Time Span= 5.00-64.00 hrs, dt= 0.05 hrs Peak Elev= 562.92'@ 12.23 hrs Surf.Area= 7,819 sf Storage= 30,694 cf Plug -Flow detention time=268.2 min calculated for 1.989 of (100%of inflow) Center -of -Mass det time=269.5 min (1,080.9 - 811.4 ) Volume Invert Avail.Storage Storage Description #1 558.00' 57,800 cf Custom Stage Data (Prismatic)Listed below(Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 558.00 4,650 0 0 566.00 9,800 57,800 57,800 Device Routing Invert Outlet Devices #1 Primary 558.00' 18.0" Round Culvert L= 49.9' CPP, mitered to conform to fill, Ke= 0.700 Inlet/Outlet Invert= 558.00'/ 557.72' S=0.0056? Cc=0.900 n= 0.013 Corrugated PE, smooth interior #2 Device 1 558.00' 3.3" Vert.1-yr Orifice C= 0.600 #3 Device 1 561.50' 36.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads Primary OutFlow Max=15.32 cfs@ 12.23 hrs HW=562.91' (Free Discharge) Culvert (Inlet controls 15.32 cfs @ 8.67 fps) 2=1-yr Orifice (Passes < 0.62 cis potential flow) 3=Orifice/Grate (Passes <40.45 cfs potential flow) Summary for Link 1 L: POA 1 Inflow Area = 16.520 aq 22.46%Impervious Inflow Depth > 4.79" for 100-yr event Inflow = 41.61 cis@ 12.34 hrs Volume-- 6.601 of Primary = 41.61 cfs @ 12.34 hrs, Volume= 6.601 af, Aden= 01/c, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-64.00 hrs, dt= 0.05 hrs Summary for Link 2L: POA 2 Inflow Area = 3.980 aq 42.46%Impervious Inflow Depth = 6.00" for 100-yr event Inflow = 15.34 cfs@ 12.23 hrs Volume= 1.991 of Primary = 15.34 cfs @ 12.23 hrs, Volume= 1.991 af, Aden= 01/c, Lag= 0.0 min Primary outflow = Inflow, Time Span= 5.00-64.00 hrs, dt= 0.05 hrs Runoff Quality Calculations: VRRM Re -Development Spreadsheet Summary Virginia Runoff Reduction Method Worksheet DEC, Virginia Runoff Reduction Method Re -Development Compliance Spreadsheet - Version 3.0 BMP Design Specifications List: 2013 Draft Stds & Specs Site Summary Project Title: BORDERLINE Date: 44453 Total Rainfall (in): 43 Total Disturbed Acreage: 9.95 Site Land Cover Summary Pre-ReDevelopment Land Cover (acres) Asoils BSoils Lolls DSolis Totals %of Total torest'open lacres) 1.54 1.50 0.00 0.00 3.04 31 Managed Turf(acres) 0.38 6.06 0.00 0.00 6.44 65 Impervious Cover (acres) 1 0.00 0.47 0.00 0.00 0.47 5 9.95 100 Post-ReDevelopment Land Cover (acres) Asoils BSoils CSolls DSoils Totals %of Total Forest/Open (acres) 0.00 0.00 0.00 0.00 0.00 0 Managed Turf(acres) 0.98 4.13 0.00 0.00 5.11 51 Impervious Cover (acres) 0.94 3.90 0.00 0.00 4.84 49 9.95 100 Site TV and Land Cover Nutrient Loads Final Post -Development post- Post Adjusted Pre- (Post-ReDevelopment ReDevelopment Development ReDevelopment rvlous &New lm pe ) (New ImpeMous) Site Rv 0.56 0.25 0.95 0.24 Treatment Volume(ft) 20,223 5,153 15,070 4,870 TP Load (lb/yr) 12.71 3.24 9.47 3.06 Total TP Load Reduction Required (Ib/yr) 8.47 0.79 7.68 Final Post -Development Load (Post-ReDevelopment IS New Impervious) Pre- ReDevelopment TN Load (Ib/yrl 90.90 29.23 Pre- ReDevelopment Final Post -Development Post-ReDevelopment TP TP Load per acre TP Load per acre Load per acre (lb/acre/yr) (Ih/acre/yr) (Ib/acre/yr) 0.55 1.28 0.58 Summary Print Virginia Runoff Reduction Method Worksheet Site Compliance Summary Maximum% Reduction Required Below 20% Pre-ReDevelopment Load Total Runoff Volume Reduction (ft) 403 Total TP Load Reduction Achieved (lb/yr) 0.40 Total TN Load Reduction Achieved (lb/yr) 3.26 Remaining Post Development TP Load 12.30 (lb/yr) Remaining TP Load Reduction (lb/yr) 8.06 Required Summary Prot Virginia Runoff Reduction Method Worksheet Drainage Area Summary D.A. A D.A. B D.A. C D.A. D D.A. E Total Forest/Open (acres) 0.00 0.00 0.00 0.00 0.00 0.00 Managed Turf jams) 0.76 0.78 0.00 0.00 0.00 1.54 Impervious Cover (acres) 0.13 0.13 0.00 0.00 0.00 0.26 Total Area (acres) 0.89 0.91 0.00 0.00 0.00 1.80 Drainage Area Compliance Summary DA. A D.A. B DA. C D.A. D D.A. E Total TP Load Reduced (lb/yr) 0.20 0.20 0.00 1 0.00 0.00 0.40 TN Load Reduced (lb/yr) 1.62 1.64 0.00 1 0.00 0.00 3.26 Summary Print Virginia Runoff Reduction Method Worksheet Drainage Area A Summary Land Cover Summary Asoils Bsoils CSoils Dsoils Total %of Total Forest/Open (acres) 0.00 0.00 0.00 0.00 0.00 0 Mre anaged Turf(acz) 0.00 0.76 0.00 0.00 0.76 85 Impervious Cover (acres) 0.00 0.13 0.00 0.00 0.13 15 0.89 BMP Selections Managed Turf Impervious BMP Treatment TP Load from Untreated TP Load TP Removed TP Remaining Downstream Treatment Practice Credit [re [over Credit I s Volume (ft) Upstream to Practice (Ibs) (Ib/yr) (Ib/yr) to be Employed (acres) Area (acres) practices (Ihz) 4.a. Grass Channel A/B Soils (Spec#3) 0.76 0.13 1,000.07 0.00 0.63 0.20 0.43 Total Impervious Cover Treated(acres) 0.13 Total Turf Area Treated (acres) 0.76 Total TP Load Reduction Achieved in D.A. 0.20 (lb/yr) Total TN Load Reduction Achieved in D.A. 1.62 (lb/yr) Summary Print Virginia Runoff Reduction Method Worksheet Drainage Area B Summary Land Cover Summary A Solis C soil, D $oils Total % of Total Forest/Open (acres) 0.00 Will 0.00 0.00 0.00 0.00 0 Managed Turf(acres) 0.00 0.78 0.00 0.00 0.78 86 Impervious Cover (acres) 0.00 0.13 0.00 0.00 0.13 14 0.91 BMP Selections Managed Turf Impervious BMP Treatment TP Load from Untreated TP Load TP Removed TP Remaining Downstream Treatment Practice Credit Area Cover Credit I a Volume (ft) Upstream to Practice (Ibs) (lb/yr) (go, to be Employed (acres) Area (acres) Practices (Ibs) 4.a. Grass Channel A/B Soils (Spec ki) 0.78 0.13 1,014.59 0.00 1 0.64 0.20 0.43 Total Impervious Cover Treated(acres) 0.13 Total Turf Area Treated (acres) 0.78 Total TP Load Reduction Achieved in D.A. (lb/yr) 0.20 Total TN Load Reduction Achieved in D.A. (lb/yr) 1.64 Summary Print Virginia Runoff Reduction Method Worksheet ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Runoff Volume and CN Calculations 1-year storm 2-year storm 10-year storm Target Rainfall Event (in) 1 2.76 3.34 5.07 Drainage Areas RV & ON Drainage Area A Drainage Area B Drainage Area C Drainage Area D Drainage Area E CN 66 66 0 0 0 RR (ft') 200 203 0 0 0 1-year return period RVwo RR(wzin) 0.43 0.43 0.00 0.00 0.00 RV w RR(w"n) 0.37 0.37 0.00 0.00 0.00 CN adjusted 64 64 0 0 0 2-year return period RV wa RR(ws-in) 0.71 0.71 OAO 0.00 0.00 RV w as(wsin) 0.65 0.65 0.00 0.00 0.00 CR adjusted 65 65 0 0 0 10-year return period RV wa RR(wzin) 1.78 1.78 0.00 0.00 0.00 RV w RR(wsin) 1.71 1.71 0.00 0.00 0.00 [N adjun 65 65 0 0 0 Summary Print Independent Reports: Excerpt from NRCS Soils Report NOAA Precipitation Report 3 11' M' N 3 11'? -N Custom Soil Resource Report N Soil Map n M TCTAO ]Z]30l TZI400 7ZI5)0 TLIB]0 TP]00 ]T19A TCRXIO TA]IXl iffi100 ]?B3O Tffii]fl ]dN00 Tffi500 3 3 Map Smle: 1:6,590f printed m A lands pe(11"x 8.5')51� N Mets 0 50 100 200 370 A w 0 3� Map prcjediwi: Web Mermhx Cm mudinahs: WG584 Edge ta: UTM 7me 17N WG584 9 p8 M �qy8_ 11'22'N Custom Soil Resource Report Map Unit Legend Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 19B Minnieville loam, 2 to 7 percent slopes 0.3 0.4% 47D Philomont sandy loam, 15 to 25 percent slopes 5.5 5.9% 65B Fairview sandy loam, 2 to 7 percent slopes 0.0 0.0% 94B Toast sandy loam, 2 to 7 percent slopes 13.3 14.5% 94C Toast sandy loam, 7 to 15 percent slopes 17.0 18.4% Subtotals for Soil Survey Area 36.2 39.2% Totals for Area of Interest 92.2 100.0% Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI AsC Ashe sandy loam, 7 to 15 percent slopes 2.0 2.1% AsD Ashe sandy loam, 15 to 25 percent slopes 25.2 27.3% BuC Buckhall loam, 7 to 15 percent slopes 16.6 18.0% CgB Chatuge sandy loam, 1 to 4 percent slopes 5.3 5.7% EIC Elioak loam, 7 to 15 percent slopes 6.5 7.0% Ud Udorthents, smoothed 0.1 0.1% w Water 0.5 0.5% Subtotals for Soil Survey Area 56.0 60.8% Totals for Area of Interest 92.21 100.0°A 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 iv Custom Soil Resource Report Albemarle County, Virginia 1913—Minnieville loam, 2 to 7 percent slopes Map Unit Setting National map unit symbol: 2v7hq 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: All areas are prime farmland Map Unit Composition Minnieville and similar soils: 80 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Minnieville 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 acid and basic igneous rock Typical profile Ap - 0 to 8 inches: loam Bt - 8 to 60 inches: clay C - 60 to 67 inches: clay Cr- 67 to 79 inches: bedrock Properties and qualities Slope: 2 to 7 percent Depth to restrictive feature: 60 to 120 inches to paralithic bedrock Drainage class: Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat): Very low to moderately high (0.00 to 0.20 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water capacity: Moderate (about 7.6 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2e Hydrologic Soil Group: B Hydric soil rating: No 15 Custom Soil Resource Report 47D—Philomont sandy loam, 15 to 25 percent slopes Map Unit Setting National map unit symbol: 2v7jb 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 Philomont and similar soils: 75 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Philomont 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 granite and gneiss Typical profile Ap - 0 to 5 inches: sandy loam Bt - 5 to 79 inches: sandy loam Properties and qualities Slope: 15 to 25 percent Depth to restrictive feature: More than 80 inches Drainage class: Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat): High to very high (5.95 to 19.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water capacity: Moderate (about 6.6 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 7e Hydrologic Soil Group: A Hydric soil rating: No Custom Soil Resource Report 6513—Fairview sandy loam, 2 to 7 percent slopes Map Unit Setting National map unit symbol: 2v7jx 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: All areas are prime farmland Map Unit Composition Fairview and similar soils: 90 percent Estimates are based on observations, Description of Fairview descriptions, and transects of the mapunit. Setting Landform: lnterHuves 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 Typical profile Ap - 0 to 6 inches: sandy loam Bt - 6 to 32 inches: clay C - 32 to 79 inches: sandy clay loam Properties and qualities Slope: 2 to 7 percent Depth to restrictive feature: More than 80 inches Drainage class: Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat) (0.57 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water capacity: Moderate (about 7.6 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2e Hydrologic Soil Group: B Hydric soil rating: No Moderately high to high IVA Custom Soil Resource Report 9413—Toast sandy loam, 2 to 7 percent slopes Map Unit Setting National map unit symbol: 2v7k8 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: All areas are prime farmland Map Unit Composition Toast and similar soils: 90 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Toast Setting Landform: lnterHuves Landform position (two-dimensional): Summit Landform position (three-dimensional): Interfiuve Down -slope shape: Convex Across -slope shape: Convex Parent material: Residuum weathered from granite and gneiss Typical profile Ap - 0 to 7 inches: sandy loam BA - 7 to 11 inches: sandy clay loam Bt - 11 to 30 inches: clay C - 30 to 60 inches: sandy clay loam Properties and qualities Slope: 2 to 7 percent Depth to restrictive feature: More than 80 inches Drainage class: Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.57 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water capacity: Moderate (about 8.0 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 2e Hydrologic Soil Group: B Hydric soil rating: No M, Custom Soil Resource Report 94C—Toast sandy loam, 7 to 15 percent slopes Map Unit Setting National map unit symbol: 2v7k9 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: Farmland of statewide importance Map Unit Composition Toast and similar soils: 90 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Toast Setting Landform: Interfluves Landform position (two-dimensional): Backslope Landform position (three-dimensional): Interfluve Down -slope shape: Convex Across -slope shape: Convex Parent material: Residuum weathered from granite and gneiss Typical profile Ap - 0 to 7 inches: sandy loam BA - 7 to 11 inches: sandy clay loam Bt - 11 to 30 inches: clay C - 30 to 60 inches: sandy clay loam Properties and qualities Slope: 7 to 15 percent Depth to restrictive feature: More than 80 inches Drainage class: Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.57 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water capacity: Moderate (about 8.0 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 4e Hydrologic Soil Group: B Hydric soil rating: No 19 Custom Soil Resource Report Greene County, Virginia AsC—Ashe sandy loam, 7 to 15 percent slopes Map Unit Setting National map unit symbol: k1bv2 Elevation: 1,400 to 5,000 feet Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 55 to 59 degrees F Frost -free period: 180 to 210 days Farmland classification: Farmland of statewide importance Map Unit Composition Ashe and similar soils: 85 percent Estimates are based on observations, Description of Ashe descriptions, and transects of the mapunit. Setting Landform: Mountain slopes Landform position (two-dimensional): Shoulder Landform position (three-dimensional): Mountaintop Down -slope shape: Convex Across -slope shape: Convex Parent material: Colluvium over residuum Typical profile H1 - 0 to 5 inches: sandy loam H2 - 5 to 22 inches: sandy loam H3 - 22 to 38 inches: fine sandy loam H4 - 38 to 48 inches: bedrock Properties and qualities Slope: 7 to 15 percent Depth to restrictive feature: 20 to 40 inches to lithic bedrock Drainage class: Somewhat excessively drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat): Very low to high (0.00 to 5.95 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water capacity: Low (about 4.7 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 4e Hydrologic Soil Group: B Hydric soil rating: No 20 Custom Soil Resource Report AsD—Ashe sandy loam, 15 to 25 percent slopes Map Unit Setting National map unit symbol: k1bv3 Elevation: 1,400 to 5,000 feet Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 55 to 59 degrees F Frost -free period: 180 to 210 days Farmland classification: Farmland of statewide importance Map Unit Composition Ashe and similar soils: 85 percent Estimates are based on observations, Description of Ashe descriptions, and transects of the mapunit. Setting Landform: Mountain slopes Landform position (two-dimensional): Backslope Landform position (three-dimensional): Mountainflank Down -slope shape: Linear Across -slope shape: Convex Parent material: Colluvium over residuum Typical profile H1 - 0 to 5 inches: sandy loam H2 - 5 to 22 inches: sandy loam H3 - 22 to 38 inches: fine sandy loam H4 - 38 to 48 inches: bedrock Properties and qualities Slope: 15 to 25 percent Depth to restrictive feature: 20 to 40 inches to lithic bedrock 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 5.95 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water capacity: Low (about 4.7 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 6e Hydrologic Soil Group: B Hydric soil rating: No 21 Custom Soil Resource Report BuC—Buckhall loam, 7 to 15 percent slopes Map Unit Setting National map unit symbol: kbvc Elevation: 480 to 1,080 feet Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 55 to 59 degrees F Frost -free period: 180 to 210 days Farmland classification: Farmland of statewide importance Map Unit Composition Buckhall and similar soils: 85 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Buckhall Setting Landform: Mountain slopes Landform position (two-dimensional): Shoulder Landform position (three-dimensional): Mountaintop Down -slope shape: Convex Across -slope shape: Convex Parent material: Residuum weathered from granite and gneiss Typical profile H1 - 0 to 9 inches: loam H2 - 9 to 27 inches: clay H3 - 27 to 36 inches: loam H4 - 36 to 62 inches: loam Properties and qualities Slope: 7 to 15 percent Depth to restrictive feature: More than 80 inches Drainage class: Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat): Moderately high to high (0.57 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water capacity: High (about 10.1 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 3e Hydrologic Soil Group: B Hydric soil rating: No PA Custom Soil Resource Report CgB—Chatuge sandy loam, 1 to 4 percent slopes Map Unit Setting National map unit symbol: kbvh Elevation: 1,400 to 2,500 feet Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 55 to 59 degrees F Frost -free period: 180 to 210 days Farmland classification: Not prime farmland Map Unit Composition Chatuge and similar soils: 85 percent Estimates are based on observations, Description of Chatuge descriptions, and transects of the mapunit. Setting Landform: Drainageways Landform position (two-dimensional): Toeslope Landform position (three-dimensional): Mountaintop Down -slope shape: Convex Across -slope shape: Convex Parent material: Alluvium Typical profile H1 - 0 to 6 inches: sandy loam H2 - 6 to 41 inches: sandy clay loam H3 - 41 to 65 inches: sandy clay loam Properties and qualities Slope: 1 to 4 percent Depth to restrictive feature: More than 80 inches Drainage class: Poorly drained Runoff class: Very high Capacity of the most limiting layer to transmit water (Ksat) (0.57 to 1.98 in/hr) Depth to water table: About 0 to 12 inches Frequency of flooding: OccasionalNone Frequency of ponding: None Available water capacity: Moderate (about 7.0 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 4w Hydrologic Soil Group: B/D Hydric soil rating: Yes Moderately high to high 23 Custom Soil Resource Report EIC—Elioak loam, 7 to 15 percent slopes Map Unit Setting National map unit symbol: kbvv Elevation: 330 to 1,000 feet Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 55 to 59 degrees F Frost -free period: 180 to 210 days Farmland classification: Farmland of statewide importance Map Unit Composition Elioak and similar soils: 85 percent Estimates are based on observations, Description of Elioak descriptions, and transects of the mapunit. Setting Landform: Hillslopes Landform position (two-dimensional): Shoulder 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 6 inches: loam H2 - 6 to 49 inches: clay H3 - 49 to 72 inches: fine sandy loam Properties and qualities Slope: 7 to 15 percent Depth to restrictive feature: More than 80 inches Drainage class: Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water (Ksat) (0.57 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water capacity: High (about 9.4 inches) Interpretive groups Land capability classification (irrigated): None specified Land capability classification (nonirrigated): 3e Hydrologic Soil Group: B Hydric soil rating: No Moderately high to high 24 Custom Soil Resource Report Ud—Udorthents, smoothed Map Unit Setting National map unit symbol: kbwj Elevation: 440 to 1,280 feet Mean annual precipitation: 40 to 50 inches Mean annual air temperature: 55 to 59 degrees F Frost -free period: 180 to 210 days Farmland classification: Not prime farmland Map Unit Composition Udorthents and similar soils: 85 percent Estimates are based on observations, descriptions, and transacts of the mapunit. Description of Udorthents Properties and qualities Depth to restrictive feature: More than 80 inches Drainage class: Moderately well drained Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None W—Water Map Unit Setting National map unit symbol: 261 cr Frost -free period: 167 to 203 days Farmland classification: Not prime farmland Map Unit Composition Water: 100 percent Estimates are based on observations, descriptions, and transacts of the mapunit. 25 7/9/2021 Precipitation Frequency Data Server NOAA Atlas 14, Volume 2, Version 3 Location name: Barboursville, Virginia, USA*'`" Latitude: 38, Longitude:-78.3981° € Elevation: 557.98 ft** * source: ESRI Maps • . -- source: USGS POINT PRECIPITATION FREQUENCY ESTIMATES G.M. Bonnin, 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)1 Average recurrence interval (years) Duretlon 1 ������1 2 5 10 25 50 100 100 200 500 1000 5-min (0.31 0383) (0.3074OA58) (0.44.414 �538) (0494-060) (0.555-0683) (0.02-0..744) (0.646--0.802) (0.85-0.89) (0.7320931) (0769-0.991) 1.08 10-min (0499-0611) (0-5980731) (0.703-0.860) (00-0.968) : 9 (0-884L0) (0.958-1.18) (1.02127) (1.08-1.36) (1. 6-3t47) (1.214'56) F-OA 15-min (0.624-00..764) (0.751--0.918) (0. 89-1.09) (0.998-1.22) (1. 2-2138) (1.21--3160) (1.29--11..61) (1.375.71) (1. 5-0L85) (1.521696) 30-min (0-854- 05) (1-044527) (1.6�54) (1.44-1077) (1.662504) (1.82-2425) (1.98 235) (2.12 228) (2.31 2694) (2.46-3.16) 2.09 60-min (1.07130) (1.30-11-59) (1.621998) (1.8-2.31) (2.2�71) (2.a73705) (2.73339) (2.98-3.73) (3.31-421) (3.58-461) 1.41 1.72 2.15 2.53 3.03 3.44 3.87 4.32 4.96 5.50 2-hr (1.6-1.59) (1.53-1.93) (1.92-2.42) (2.25-2.84) (2.67-3.38) (3.02-3.8) (3.38-4.32) (3.744.8) 1 (4.24-5.55) (4.656.18) 3-hr (1.37-11..76) mfis--2813) (2.07- 67) (24 3-3.13) (2.893 73) (3.27424) (3.664378) 1 (4.06-5.36) 11 (4. 0-6.16) (5.066.8) 6 6-hr (1 4223) (2. 0 270) (2.60 3435) (305-3.94) (3.64-4.74) (4: 5-5.43) (4.67-6.16) (5.226.97) (5.99-8.14) (6.65-9718) 12-hr (2.12742..80) (2.62 338) (3. 64821) (3.844 97) (4.636A3) (5.31-6.99) (6.03 8803) (6.80-9.18) (7.91-610.9) (8.89- 2.5) 24fir (2.64-034.31) (3.94A1) (4.06-5.11) (479603) (5.84--739) (6.2854) (7.669982) (8.68-1.2) (102-3.3) (114315.2) 4.98 5.32 6.25 7.60 8.73 9.95 11 14.8 F2day3.46 2�ey (3.12-3.8) (3.784.67) (4.80-5.93) (5.626.96) 1 (6.78-8.44) (7.73-9.8) (8.76-11.0) (9.86-12.5) I (11A.4A-14.7) I (12.6-i6.6) 3-0ay (3.34-4..08) (4.05-44 ..94) (5. 3 627) (6.01-6735) 1 (7. 6 8892) (82 9- 02) (9.37--111.7) (10.5-13.2) 11 (12 2415.5) 1 (13.5-17.5) 4Fday4dey (3.56431) (4-315321) (5.466061) (6.40-7.75) (7.74-9..40) (8.84-10.8) (9.99- 2.3) (11 2213.9) (13.0-16.3) (14.4-18.4) 6.46 79 7�ey (4. 58.99) (5. 06.01) (6. 3�51) (7.2 8574) (8.650.5) (9.82- 2.0) (11.0-13.5) (12.3-15.2) (141617.7) (15.15-19.8) 10-0ey (4. 3561) 1 (5. 86.73) 1 (7.008330) 1 (8.06-9.57) 1 (9.5411.4) (f07- 2.8) (119-14.4) (132- 6.0) (15.0- 8.4) (16.4- 0.4) 20aay (6. 37830) (75 5-08..70) (9. 010.5) (10.3-1.9) (119-13.8) (132-15.3) (14536.9) (157-18.5) (1749 0.7) (18�22.4) 175 30-0ey (7. 08289) (9.25-810.5) (10.9- 2.5) (122--13.9) (13.8-15.8) (15.11--127.3) (16.3- 8.7) (17.4- 0.1) (189022.0) (20.0- 3.5) 454ay (979-ii.0) (116 3.0) (1355-15.2) (14.9-16.8) (16.8- 8.9) (18..1- 0.5) (194022.0) (20623.5) (2223 5.4) (2325 6.9) 12.2 14.4 16.6 18.2 20.3 21.8 23.3 24.7 26A 27.7 601iay (11.5-12.9) (13.6-15.2) (15.6-1Z5) (17.2-19.3) (19.1-21.5) (20.5-23.1) (21.9-24.7) (23.1-6.2) (24.6-28.1) (25.7-75) 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 Atias 14 document for more information. Back to Top hffps://hdsc.rlws.noaa.govlhdsctpfds/pfds_Printpage.html?lat=38.1936&Ion=-78.3981&data=depth&units=english&series=pds 1/4 BORDERLINE MASS GRADING PLAN Sediment Basin Design Worksheet Orange cells need input, white cells are calculations. Basin SB-1 SB-2 Step 1: Preliminary Design Top of Data 568.0 , 566.0 Barrel Invert IN 556.0 558.0 Barrel Invert OUT 554.0 557.7 Bartel length (ft) 99.0 49.9 Slope of principal spillway barrel (%) 2.02% 0.56 % Step 2: Calculate Runoff Ratuvad Method Drainage Area (ac) 15.61 398 C 0.30 0.30 li 3.6 3.6 Its 6.6 6.6 Qr (-fa) 16.7 4.3 Qn (cfs) 30.9 7.9 Step 3: Principal Spillway From Plate 3.14-8 Spillway Capacity with emergency spillway (cfs) 161 4.3 Riser Diameter (in) 48 36 Actual head (f) NO 1.00 Q,(max) 400 40.0 Step 4: Emergency Spillway From Table 3./4-C Required spillway capacity -9.1 -32.1 na Ofl 0.0 b- Bottom width (f) a 0 S - slope of exit channel (ft/fool) toll 0.00 X - minimum length of exit channel (B) o 0 Step 5: Grade Basin Design Parameters Maximum Top of wet Storage 566.0 564.0 Required Wet +Dry Stomp let) 56,477 14,400 Wet Storage Required Volume (cy) 1046 267 Required Volume (cf) 28,238 7,200 Minimum Standpipe Invert 556.0 558.0 Cleanout Required Volume (cy) 515 131 Cleanout Required V.I. let) 13,909 3,546 Design Elevation Area (at) Elevation Area"") 556.0 4,887 558.0 4,675 ("A") Bottom of Wet Storage 558.0 5,589 559.0 5,220 559.0 1 6,331 560.0 5,785 ("B") Clement Elevation 560.0 1 7,100 561.0 6,380 561.0 1 7,906 562.0 7,000 ("C') Top of Wet Storage Cleanout Volume (cf) 16A36 10,450 Wet Storage Volume (cf) 30,655 23,223 Wet Storage Volume (cy) 1135 860 Dry Storage Required Volume (cy) 10" 267 Required Volume (cf) 28,238 7,200 Maximum Top of Dry Storage 566.0 564.0 Design Elevation Area(at) Elevation Area(aft 561.0 7,906 5610 7,000 Bottom of Dry Stomp 562.0 ]0,521 563.0 7,640 564.0 11,459 564D 1 8,310 Top of Dry Storage 31,194 15,295 Dry Storage Volume (cf) Dry Storage Volume (cy) 1155 566 Step 6: Final Details Upstream Toe of Dam 5s60 558.0 Principle Spillway Elevation 56]3 562.5 Trash rack and anti-vorie , device From Table 3.14-D: Trash Rack Diameter (in) 72 54 Trash Rack Height (in) 21 17 From Retention Basin Design and Plate 3.14-8: Head on barrel (f0 8.5 4.8 Qe(max) 40 1s Barrel diameter (in) 24 18 Dewatering Orifice Design Riser Height 8.0 6.0 It (ft) 1.5 1.0 S let) 31,194 15,295 Q (cfs) 1.44 0.71 A(d) 0.245 0.147 d (ft) 0.559 0.433 Dewatering Orifice Diameter (in) 8 6 Flexible Tubing Diameter (in) 10 8 Baffle Calculation Length of Flow (L) (ft) Effective Width (W,) (ft) 115 50 1/W, 0.3 1.8 Baffles Required? yes yes 25-yr WSE 562.]? 16140 Borderline Sediment Trap Calculations Drainage Area= 2.71 Ac Trap POST Wet Volume Required= 181.4676 CY L w D1 D2 Dry Volume Required= 181.4676 CY Increment Total al Volume Volume Weir Width= Elevation Area (sf) (CY) (CY) 16.3 ft 558 2550 560 3055 207.6 207.6 H= 3 562 4176 267.8 475.4