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HomeMy WebLinkAboutWPO202200026 Calculations 2022-06-21SHIMP ENGINEERING, P.C. Design Focused Engineering June 20, 2022 Engineering Review Albemarle County Department of Community Development 401 McIntire Road Charlottesville, VA 22902 No. 45183 6(20In Regarding: WPO 2022000XX Castalia Farm Equipment Facility VSMP—SWM Calculation Packet Dear Reviewer, Enclosed is the stormwater calculation packet for Castalia Farm Equipment Buildings. The development property has an area of 52.80 acres and a disturbed area of 3.12 acres. The project is a private development of a site. The proposed stormwater design meets water quality requirements set forth in 9VAC25-870-65 and water quantity requirements set forth in 9VAC25-870-66-B(3) and flood protection requirements. SWM Quality SWM Quality is satisfied by providing required nutrient treatment for the development. 9VAC25-870-65 requires that the total phosphorous (TP) nutrient load created by the site development be treated in accordance with the VRRM Redevelopment Spreadsheet reduction requirements. To achieve nutrient treatment, 1.44 Ibs/yr phosphorous credits will be purchased. This amount satisfies the nutrient treatment requirement. Treatment Required Total Phosphorous) ( Treatment Provided Total Phosphorous) Nutrient Credits Purchased 1.44lb/yr 0.00lb/yr 1.44lb/yr SWM Quantity SWM Quantity is satisfied by analyzing concentrated runoff from the development at 1 Point Of Analysis (POA 1) within a channel downstream of the development property. 9VAC25-870-66-B(3) requires that concentrated runoff from the development at each POA meets the energy balance equation. The runoff to POA I meets the energy balance equation. 9VAC25-870-66-C requires that the post-dev 10-year runoff at the POAs not exceed the pre-dev 10-yr runoff. This condition has also been satisfied. All other onsite runoff is released as sheet flow via a level spreader designed in accordance with VA DEQ Specification No. 2. Since all runoff is sheet flow, this area is not required to meet the energy balance equation and meets flood protection requirements. 912 E High 51. Charlottesville, VA 22902 1 434.227.5140 1 shimp engmeenng com POA 1: Energy Balance Equation Summary //n Castalia Farm (POA 1) Qdereloped25 I.F. *(Qpre-dev oped*RVPre De loped)/RVdeveloped Qdeveloped� (04orerted*RVforeAed)/RVdeve1oped Qpredeveloped = 0. RVPreDeveloped = Max Qdve,0.09 cfs RVDeeloped Achieved Post-Dev Max Runoff Qlyr = 0.09 cfs. Site complies with 9VAC25-870-66-(3)A Maximum Qfayr = 3.11 cfs (predev) Achieved Q10yr = 0.89 cfs If you have any questions about this calculation packet please do not hesitate to contact me at: chris&shimp- engineering com or by phone at 434-227-5140. Regards, Chris Marshall, EIT Shimp Engineering, PC Contents: Water Quality Calculations: Pre-Dev VRRM Land Cover Map Post-Dev VRRM Land Cover Map VRRM Redevelopment Spreadsheet Water Quantity Calculations: Pre-Dev Drainage Area Map Predev HydroCAD Report Post-Dev Drainage Area Map Postdev HydroCAD Report Energy Balance Equation TOC Calculations Outlet Drainage Protection Spreadsheet Independent Reports: NOAA Precipitation Report Excerpt from NRCS Soils Report CASTALIA FARM EQUIPMENT FACILITY PREDEV VRRM MAP ONSITE LAND COVER: DISTURBED AREA = 3.12 AC IMPERVIOUS = 0.76 AC MEADOW = 2.07 AC WOODS = 0.29 AC .�.. ... ....: •/ TYP 66-11D CASTAL(A-DBM4881 ONT PC asersrn uc\. f... .... a°a°II°II / / Yi aaaa0000000o aaaaaaao -J I 1 I / I \ \ \ \ \ \ ` / / / � \ l / / / / / . ,�../ l• .� a°�°a°���������II a°a°a°a°�����II _�i�.f ..> .. � \ I I (\ \ \ \ � \ � \\ \ 1 \ 11 r (` ^ � / � n � ' � / / � � / ✓. �.:' IIII°II°>3>3>3>3>3>3>3>3>3>3>� >3>3>3>3>3>3>� ; �l • •.f / ( ( I ' ( \ \\ \ \ � / / / / � f / 1 /^ ✓.- \ \ � � — —/ / —� r / / � � .` ,�= ...... aaaaaaaaaaaaaa p;.. (.. / ` 1 \ I \ \\ � _� ( / 1 \ /\ I r 1 — / ✓ ( ,, :.'.'.'.�.......... - - -- .....� /// // �/\lit �/\✓ � -, fjICJ ) / i / �/r/�/—\^ \ \ \ \\ ✓//I//(J / 1l` ��— j //�011\ ( i /\ \\ 10 '0 \10o �00 300 -- -� �1\ // I / / l / ✓ \mil/ / / / ` \ \\�\ \Ilk q q p q RIM\ // —/ / —1 j////I)\I\(I1\\ \ Scale�1 =100'� \\ \ \ \ \ \ \\\ CASTALIA FARM EQUIPMENT FACILITY POSTDEV VRRM MAP ONSITE LAND COVER: DISTURBED AREA = 3.12 AC IMPERVIOUS = 0.76 AC MEADOW = 2.36 AC WOODS = 0.00 AC ' �/ / / /� I� \ \\' 1 \ )ice t � �\�1�/= �� p \ y�..,..`� •.•.•..✓!.••/ // f i� / 1 /// �-�\��_�� �1\� \ Il\\�\\\\ l \I \ \ J f \ 1 \ \ III •.I;: .... /' / (I I ( / / TNP INVESTMENT CASTALlA-DB 4881 CISMONT PG aseraxT cm / 1 !'. /.' popppppppppopo '.'.'\. .. ... mx / pbbbbbbb bb . / v / �� „ / — � .i / / , � � / /• • l /• pbbbbbbb bbbbb .... j ... / / /• �. _ J ` — / / � . / / / p°p°p°p°p°p°p°p°p°p°p°p°p° p°p°p°p°p°p°p°p°pb • • / f / ( l 1 l ) I � 1 \ ) `"'' \ \\ � \\ \\ 1 1 1 � l (� � / � .� / / ^ \ / / — n � � / / / � � / /• / �: bpbpbpbpbpbpbpbpbpbpbpbpbpbpb bpbpbpbpbpbpbpbpbp • ;, `/ f / i -' \ I I \ ' (\ � \ \\\ \ \ I I ( \ I -. I \ /- � /� � f / J / � ` J , f ./. / pbpbpbpbbpbpbpbpbpbpbpbpbpbpb bbpbpbpbpbpbpbpbp . � •� • 7 • / / ) / \ \ \ I I � l ` � \ \ \\\\\\ \\\ \\\ �\\\ � / 1 I / J 1 � \ ✓ — — / � l / \ % • I.� ob°° - - - - - - bbb°b°b°b°bbbbb bbbpbpb _. F • •.f • ( / / I I r I 1 l ` \ \ \\ �........... ....i.' i ( / ('� \ \ \` \\ ✓ / 1 / ;' .'...�'..'.'.'.'.'.'.'.T.�.� / / l it 1 / � .% �- �'`��.� '� •�` •!�.'•'�'-�•':'•�%'�"•�• • _ �\\\ \� 1 \ l \ 1 I \ \\ \ '-\ \ \ 1 1\ \—��/ / /// JII < � �1�\,\\-�\\Jn fv�`% i j;ppc---../....1�:•i'l..-_—\\I\�� \ \\ \\\ \\\\ \\ \� \��\\\ \\�\l \ C� \I \\\\\ I`100 0\ \\ \i0a(\ \\ 00 \`— 300 \ \ �``,_ i� ✓ / I �/ /�(/ J I / �l�r-��- f / /,�// / 1 (( 11 ( ( / \ Scale: 1"L100' \ .EQ Y[gi—Runoff Retlu[fion.1h.d. Development (uWft— SgenEiM1eel - C Ysla 9W 5brmtlF atlapetlaebs 02023 ora 9Me stanearesaM Sp M=Ims pm7e[txme:1 Ustalla Farm 6gUipment Fatllity Oab: 6/71303E BMYOes9n spe[ifi[^[iwu List. . nos ants a.mrmiprcne:l 43 .waa MC a.m TM I ITPIE m[pEMC nx6 �m m+IFmcImW a.m is rgetm Wea 114/eve/yr� OA] X l��m[::m�maesmrl o.m 3.0 0. Site Results (Water Quality Compliance) Area Checks FOREST/OPEN SPACE (a[) D.A.A am D.A.B 0.00 D.A.0 0.00 DA.D 0.00 O.F.E O.W A.-CHEM OK. IMPERVIOUS COVER(a[) am 0.00 0.00 0.00 0.00 OK. IMPERV��GED TUEAAREA Ia[) 0.00 0.00 DOD 0.00 0.00 OK. MANAGED TURF AREA TREATED Ia[) 0.00 0.00 DOD 0.00 O.00 OK. AREA CHECK OK OK. OK. OK OK. Site Treatment Volume (ffs) n.BBa Runoff Reduction Volume and TP By Drainage Area D.A. A D.A. B D.A. C D.A. D O.A. E TOTAL RUNOFF RFDUOION VOLUME ACHIEVEDIW) 0 0 0 0 0 TP LOADAVAINBLE FOR REMOVAL Qb/yrI 0.00 O.W 0.00 0.00 O.M 0.00 TP IDAD REDUCTION ACHIEVED)Ib/yrl 0.00 O.W 0.00 0.00 O.W 0.00 TP LOAD REMAINING IIb/yr) 0.00 0.00 0.00 0.00 0.00 am NnROGEN IDAD REDUCTION ACHIEVED pb/yrl 0.00 O.W 0.00 0.00 O.W 0.00 Total Phosphorus FINAL POST-DEVELOPMENTTP LOAD Qb/yr) 2.72 TP LOAD REDUCTION REQUIRED pb/yrl I." TP WAD REDUCTION AOIIFVED lb/yrl 0.00 W WAD REMAINING Qb/yr): 2.72 REMAINING TP LOAD REDUCTION REQUIRED pb/yr): 1." Total Nitrogen (For Information Purposes) POST -DEVELOPMENT LOAD IIb/yr) 19A8 NITROGEN LOAD REDUCTION ACHIEVED (I ") a m REMAINING POST -DEVELOPMENT NITRWEN LOAD Pb/yrl 19A8 �o �o �o ®© �© CASTALIA FARM EQUIPMENT FACILITY PREDEV DRAINAGE AREA MAP T�65-1f\CASTALTA-CISMONT INVESTMENT LLC I 11 1 \ \\ DAI 100\� \ �\ �100�\ 20 ` 300 -Sale: DRAINAGE AREA 1: TOTAL AREA = 3.02 AC WOODS = 3.02 AC, HSG TYPE B TIME OF CONCENTRATION = 21.4 NOTE: ASSUMED ENTIRE AREA AS WOODS FOR EXISTING AREA ALREADY CONSTRUCTED. DRAINAGE AREA 2: TOTAL AREA = 1.55 AC WOODS = 1.55 AC MEADOW = 0.00 AC IMPERVIOUS = 0.00 AC NOTE: CONCENTRATED RUNOFF TO BE RELEASED AS SHEETFLOW IN POSTDEV CONDITION. 5S DA 1 1L POA 1 Subcat Reach on Link Drainage Diagram for PREDEV Prared by {enter your company name here}, Printed 6/6/2022 FHydpoCAD® 9.10 s/n 07054 0 2010 HydroCAD Software Solutions LLC Predev PREDEV Type/1 24-hr 1-YR Rainfall=2.91" Prepared by {enter your company name here} Printed 6/6/2022 HvdroCAD® 9.10 s/n 07054 ©2010 HvdroCAD Software Solutions LLC Paae 2 Time span=0.00-48.00 hrs, dt=0.03 hrs, 1601 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Link 1 L: POA 1 Inflow=0.14 cfs 0.043 of Primary=0.14 cfs 0.043 of Subcatchment5S: DA 1 Runoff Area=3.020 ac 0.00% Impervious Runoff Depth=0.17" Tc=21.4 min CN=55 Runoff=0.14 cfs 0.043 of Total Runoff Area = 3.020 ac Runoff Volume = 0.043 of Average Runoff Depth = 0.17" 100.00% Pervious = 3.020 ac 0.00% Impervious = 0.000 ac Predev PREDEV Type/1 24-hr 1-YR Rainfall=2.91" Prepared by {enter your company name here} Printed 6/6/2022 HvdroCAD® 9.10 s/n 07054 ©2010 HvdroCAD Software Solutions LLC Paae 3 Summary for Link 1 L: POA 1 Inflow Area = 3.020 ac, 0.00% Impervious, Inflow Depth = 0.17" for 1-YR event Inflow = 0.14 cfs @ 12.31 hrs, Volume= 0.043 of Primary = 0.14 cfs @ 12.31 hrs, Volume= 0.043 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.03 hrs Summary for Subcatchment 5S: DA 1 Runoff = 0.14 cfs @ 12.31 hrs, Volume= 0.043 af, Depth= 0.17" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.03 hrs Type II 24-hr 1-YR Rainfall=2.91" Area (ac) CN Description 3.020 55 Woods, Good, HSG B 3.020 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 21.4 Direct Entry, Predev PREDEV Type/1 24-hr 10-YR Rainfall=5.34" Prepared by {enter your company name here} Printed 6/6/2022 HvdroCAD® 9.10 s/n 07054 ©2010 HvdroCAD Software Solutions LLC Paae 4 Time span=0.00-48.00 hrs, dt=0.03 hrs, 1601 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Link 1 L: POA 1 Inflow=3.11 cfs 0.290 of Primary=3.11 cfs 0.290 of Subcatchment5S: DA 1 Runoff Area=3.020 ac 0.00% Impervious Runoff Depth=1.15" Tc=21.4 min CN=55 Runoff=3.11 cfs 0.290 of Total Runoff Area = 3.020 ac Runoff Volume = 0.290 of Average Runoff Depth = 1.15" 100.00% Pervious = 3.020 ac 0.00% Impervious = 0.000 ac Predev PREDEV Type/1 24-hr 10-YR Rainfall=5.34" Prepared by {enter your company name here} Printed 6/6/2022 HvdroCAD® 9.10 s/n 07054 ©2010 HvdroCAD Software Solutions LLC Paae 5 Summary for Link 1 L: POA 1 Inflow Area = 3.020 ac, 0.00% Impervious, Inflow Depth = 1.15" for 10-YR event Inflow = 3.11 cfs @ 12.17 hrs, Volume= 0.290 of Primary = 3.11 cfs @ 12.17 hrs, Volume= 0.290 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.03 hrs Summary for Subcatchment 5S: DA 1 Runoff = 3.11 cfs @ 12.17 hrs, Volume= 0.290 af, Depth= 1.15" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.03 hrs Type II 24-hr 10-YR Rainfall=5.34" Area (ac) CN Description 3.020 55 Woods, Good, HSG B 3.020 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 21.4 Direct Entry, Predev PREDEV Type/1 24-hr 100-YR Rainfall=8.77" Prepared by {enter your company name here} Printed 6/6/2022 HvdroCAD® 9.10 s/n 07054 ©2010 HvdroCAD Software Solutions LLC Paae 6 Time span=0.00-48.00 hrs, dt=0.03 hrs, 1601 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Link 1 L: POA 1 Inflow=10.42 cfs 0.836 of Primary=10.42 cfs 0.836 of Subcatchment5S: DA 1 Runoff Area=3.020 ac 0.00% Impervious Runoff Depth=3.32" Tc=21.4 min CN=55 Runoff=10.42 cfs 0.836 of Total Runoff Area = 3.020 ac Runoff Volume = 0.836 of Average Runoff Depth = 3.32" 100.00% Pervious = 3.020 ac 0.00% Impervious = 0.000 ac Predev PREDEV Type/1 24-hr 100-YR Rainfall=8.77" Prepared by {enter your company name here} Printed 6/6/2022 HvdroCAD® 9.10 s/n 07054 ©2010 HvdroCAD Software Solutions LLC Paae 7 Summary for Link 1 L: POA 1 Inflow Area = 3.020 ac, 0.00% Impervious, Inflow Depth = 3.32" for 100-YR event Inflow = 10.42 cfs @ 12.15 hrs, Volume= 0.836 of Primary = 10.42 cfs @ 12.15 hrs, Volume= 0.836 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.03 hrs Summary for Subcatchment 5S: DA 1 Runoff = 10.42 cfs @ 12.15 hrs, Volume= 0.836 af, Depth= 3.32" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.03 hrs Type II 24-hr 100-YR Rainfall=8.77" Area (ac) CN Description 3.020 55 Woods, Good, HSG B 3.020 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 21.4 Direct Entry, CASTALIA FARM EQUIPMENT FACILITY POSTDEV DRAINAGE AREA MAP DRAINAGE AREA 1: TOTAL AREA = 3.02 AC WOODS = 1.97 AC MEADOW = 0.82 AC IMPERVIOUS = 0.23 AC TIME OF CONCENTRATION = 5.0 MINUTES (ASSUMED) SKETFL® J 1 TYP 65-11D' CASTALra-CISt10e Ti INVESTMENT ccc 18 \\�\\\W\\\ \\ D� 00 Ilt,\ram J.. ✓� � /\ \ �i �\ � \ �\ \ \ / / ( \ \\\ �\ \ \ \ \ \\ � _ �` i \\ \\ -,Scale: 5S DA 1 NV 49p Detention Pond 6L POA 1 S4 Reach X 4on Llflk Postdev POSTDEV Type/1 24-hr 1-YR Rainfall=2.91" Prepared by {enter your company name here} Printed 6/7/2022 HvdroCAD® 9.10 s/n 07054 ©2010 HvdroCAD Software Solutions LLC Paae 2 Time span=0.00-48.00 hrs, dt=0.03 hrs, 1601 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment5S: DA 1 Runoff Area=3.020 ac 7.62% Impervious Runoff Depth=0.22" Tc=5.0 min UI Adjusted CN=57 Runoff=0.58 cfs 0.055 of Link 6L: PDA 1 Inflow=0.09 cfs 0.055 of Primary=0.09 cfs 0.055 of Pond 9P: Detention Pond Peak Elev=540.25' Storage=462 cf Inflow=0.58 cfs 0.055 of Outflow=0.09 cfs 0.055 of Total Runoff Area = 3.020 ac Runoff Volume = 0.055 of Average Runoff Depth = 0.22" 92.38% Pervious = 2.790 ac 7.62% Impervious = 0.230 ac Postdev POSTDEV Type/1 24-hr 1-YR Rainfall=2.91" Prepared by {enter your company name here) Printed 6/7/2022 HvdroCAD® 9.10 s/n 07054 ©2010 HvdroCAD Software Solutions LLC Paae 3 Summary for Subcatchment 5S: DA 1 Runoff = 0.58 cfs @ 12.01 hrs, Volume= 0.055 af, Depth= 0.22" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.03 hrs Type II 24-hr 1-YR Rainfall=2.91" Area (ac) CN Description 1.970 55 Woods, Good, HSG B 0.820 58 Meadow, non -grazed, HSG B 0.230 98 Unconnected roofs, HSG B 3.020 59 Weighted Average, UI Adjusted CN = 57 2.790 92.38% Pervious Area 0.230 7.62% Impervious Area 0.230 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Link 6L: POA 1 Inflow Area = 3.020 ac, 7.62% Impervious, Inflow Depth > 0.22" for 1-YR event Inflow = 0.09 cfs @ 13.33 hrs, Volume= 0.055 of Primary = 0.09 cfs @ 13.33 hrs, Volume= 0.055 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.03 hrs Summary for Pond 9P: Detention Pond Inflow Area = 3.020 ac, 7.62% Impervious, Inflow Depth = 0.22" for 1-YR event Inflow = 0.58 cfs @ 12.01 hrs, Volume= 0.055 of Outflow = 0.09 cfs @ 13.33 hrs, Volume= 0.055 af, Atten= 85%, Lag= 79.5 min Primary = 0.09 cfs @ 13.33 hrs, Volume= 0.055 of Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.03 hrs Peak Elev= 540.25' @ 13.33 hrs Surf.Area= 1,897 sf Storage= 462 cf Plug -Flow detention time= 111.7 min calculated for 0.055 of (100% of inflow) Center -of -Mass det. time= 112.1 min ( 1,070.8 - 958.8 ) Volume Invert Avail.Storage Storage Description #1 540.00' 12,302 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 540.00 1,734 0 0 542.00 3,016 4,750 4,750 544.00 4,536 7,552 12,302 Postdev POSTDEV Type/1 24-hr 1-YR Rainfall=2.91" Prepared by {enter your company name here} Printed 6/7/2022 HvdroCAD@ 9.10 s/n 07054 @ 2010 HvdroCAD Software Solutions LLC Paae 4 Device Routing Invert Outlet Devices #1 Primary 539.00' 15.0" Round Culvert L= 31.0' CMP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 539.00' / 538.00' S= 0.0323 '/' Cc= 0.900 n= 0.012 #2 Device 1 542.00' 24.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 540.00' 3.0" Vert. Orifice/Grate C= 0.600 #4 Primary 542.50' 16.0' long x 13.0' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.60 2.64 2.70 2.66 2.65 2.66 2.65 2.63 Primary OutFlow Max=0.09 cfs @ 13.33 hrs HW=540.25' (Free Discharge) 1=Culvert (Passes 0.09 cfs of 3.70 cfs potential flow) �2=Orifice/Grate ( Controls 0.00 cfs) 3=Orifice/Grate (Orifice Controls 0.09 cfs @ 1.73 fps) =Broad -Crested Rectangular Weir( Controls 0.00 cfs) Postdev POSTDEV Type/1 24-hr 10-YR Rainfall=5.34" Prepared by {enter your company name here} Printed 6/7/2022 HvdroCAD® 9.10 s/n 07054 ©2010 HvdroCAD Software Solutions LLC Paae 5 Time span=0.00-48.00 hrs, dt=0.03 hrs, 1601 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment5S: DA 1 Runoff Area=3.020 ac 7.62% Impervious Runoff Depth=1.29" Tc=5.0 min UI Adjusted CN=57 Runoff=6.90 cfs 0.325 of Link 6L: PDA 1 Inflow=0.89 cfs 0.325 of Primary=0.89 cfs 0.325 of Pond 9P: Detention Pond Peak Elev=542.09' Storage=5,024 cf Inflow=6.90 cfs 0.325 of Outflow=0.89 cfs 0.325 of Total Runoff Area = 3.020 ac Runoff Volume = 0.325 of Average Runoff Depth = 1.29" 92.38% Pervious = 2.790 ac 7.62% Impervious = 0.230 ac Postdev POSTDEV Type/1 24-hr 10-YR Rainfall=5.34" Prepared by {enter your company name here) Printed 6/7/2022 HvdroCAD® 9.10 s/n 07054 ©2010 HvdroCAD Software Solutions LLC Paae 6 Summary for Subcatchment 5S: DA 1 Runoff = 6.90 cfs @ 11.97 hrs, Volume= 0.325 af, Depth= 1.29" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.03 hrs Type II 24-hr 10-YR Rainfall=5.34" Area (ac) CN Description 1.970 55 Woods, Good, HSG B 0.820 58 Meadow, non -grazed, HSG B 0.230 98 Unconnected roofs, HSG B 3.020 59 Weighted Average, UI Adjusted CN = 57 2.790 92.38% Pervious Area 0.230 7.62% Impervious Area 0.230 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Link 6L: POA 1 Inflow Area = 3.020 ac, 7.62% Impervious, Inflow Depth > 1.29" for 10-YR event Inflow = 0.89 cfs @ 12.38 hrs, Volume= 0.325 of Primary = 0.89 cfs @ 12.38 hrs, Volume= 0.325 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.03 hrs Summary for Pond 9P: Detention Pond Inflow Area = 3.020 ac, 7.62% Impervious, Inflow Depth = 1.29" for 10-YR event Inflow = 6.90 cfs @ 11.97 hrs, Volume= 0.325 of Outflow = 0.89 cfs @ 12.38 hrs, Volume= 0.325 af, Atten= 87%, Lag= 24.3 min Primary = 0.89 cfs @ 12.38 hrs, Volume= 0.325 of Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.03 hrs Peak Elev= 542.09' @ 12.38 hrs Surf.Area= 3,084 sf Storage= 5,024 cf Plug -Flow detention time= 176.6 min calculated for 0.325 of (100% of inflow) Center -of -Mass det. time= 176.4 min ( 1,052.4 - 875.9 ) Volume Invert Avail.Storage Storage Description #1 540.00' 12,302 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 540.00 1,734 0 0 542.00 3,016 4,750 4,750 544.00 4,536 7,552 12,302 Postdev POSTDEV Type/1 24-hr 10-YR Rainfall=5.34" Prepared by {enter your company name here} Printed 6/7/2022 HvdroCAD@ 9.10 s/n 07054 @ 2010 HvdroCAD Software Solutions LLC Paae 7 Device Routing Invert Outlet Devices #1 Primary 539.00' 15.0" Round Culvert L= 31.0' CMP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 539.00' / 538.00' S= 0.0323 '/' Cc= 0.900 n= 0.012 #2 Device 1 542.00' 24.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 540.00' 3.0" Vert. Orifice/Grate C= 0.600 #4 Primary 542.50' 16.0' long x 13.0' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.60 2.64 2.70 2.66 2.65 2.66 2.65 2.63 Primary OutFlow Max=0.88 cfs @ 12.38 hrs HW=542.09' (Free Discharge) 1=Culvert (Passes 0.88 cfs of 7.32 cfs potential flow) �2=Orifice/Grate (Weir Controls 0.55 cfs @ 0.98 fps) 3=Orifice/Grate (Orifice Controls 0.33 cfs @ 6.75 fps) =Broad -Crested Rectangular Weir( Controls 0.00 cfs) Postdev POSTDEV Type ll24-hr25-YR Rainfall=2.91" Prepared by {enter your company name here} Printed 6/7/2022 HvdroCAD® 9.10 s/n 07054 ©2010 HvdroCAD Software Solutions LLC Paae 8 Time span=0.00-48.00 hrs, dt=0.03 hrs, 1601 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment5S: DA 1 Runoff Area=3.020 ac 7.62% Impervious Runoff Depth=0.22" Tc=5.0 min UI Adjusted CN=57 Runoff=0.58 cfs 0.055 of Link 6L: PDA 1 Inflow=0.09 cfs 0.055 of Primary=0.09 cfs 0.055 of Pond 9P: Detention Pond Peak Elev=540.25' Storage=462 cf Inflow=0.58 cfs 0.055 of Outflow=0.09 cfs 0.055 of Total Runoff Area = 3.020 ac Runoff Volume = 0.055 of Average Runoff Depth = 0.22" 92.38% Pervious = 2.790 ac 7.62% Impervious = 0.230 ac Postdev POSTDEV Type ll24-hr25-YR Rainfall=2.91" Prepared by {enter your company name here) Printed 6/7/2022 HvdroCAD® 9.10 s/n 07054 ©2010 HvdroCAD Software Solutions LLC Paae 9 Summary for Subcatchment 5S: DA 1 Runoff = 0.58 cfs @ 12.01 hrs, Volume= 0.055 af, Depth= 0.22" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.03 hrs Type II 24-hr 25-YR Rainfall=2.91" Area (ac) CN Description 1.970 55 Woods, Good, HSG B 0.820 58 Meadow, non -grazed, HSG B 0.230 98 Unconnected roofs, HSG B 3.020 59 Weighted Average, UI Adjusted CN = 57 2.790 92.38% Pervious Area 0.230 7.62% Impervious Area 0.230 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Link 6L: POA 1 Inflow Area = 3.020 ac, 7.62% Impervious, Inflow Depth > 0.22" for 25-YR event Inflow = 0.09 cfs @ 13.33 hrs, Volume= 0.055 of Primary = 0.09 cfs @ 13.33 hrs, Volume= 0.055 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.03 hrs Summary for Pond 9P: Detention Pond Inflow Area = 3.020 ac, 7.62% Impervious, Inflow Depth = 0.22" for 25-YR event Inflow = 0.58 cfs @ 12.01 hrs, Volume= 0.055 of Outflow = 0.09 cfs @ 13.33 hrs, Volume= 0.055 af, Atten= 85%, Lag= 79.5 min Primary = 0.09 cfs @ 13.33 hrs, Volume= 0.055 of Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.03 hrs Peak Elev= 540.25' @ 13.33 hrs Surf.Area= 1,897 sf Storage= 462 cf Plug -Flow detention time= 111.7 min calculated for 0.055 of (100% of inflow) Center -of -Mass det. time= 112.1 min ( 1,070.8 - 958.8 ) Volume Invert Avail.Storage Storage Description #1 540.00' 12,302 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 540.00 1,734 0 0 542.00 3,016 4,750 4,750 544.00 4,536 7,552 12,302 Postdev POSTDEV Type ll24-hr25-YR Rainfall=2.91" Prepared by {enter your company name here} Printed 6/7/2022 HvdroCAD@ 9.10 s/n 07054 @ 2010 HvdroCAD Software Solutions LLC Paae 10 Device Routing Invert Outlet Devices #1 Primary 539.00' 15.0" Round Culvert L= 31.0' CMP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 539.00' / 538.00' S= 0.0323 '/' Cc= 0.900 n= 0.012 #2 Device 1 542.00' 24.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 540.00' 3.0" Vert. Orifice/Grate C= 0.600 #4 Primary 542.50' 16.0' long x 13.0' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.60 2.64 2.70 2.66 2.65 2.66 2.65 2.63 Primary OutFlow Max=0.09 cfs @ 13.33 hrs HW=540.25' (Free Discharge) 1=Culvert (Passes 0.09 cfs of 3.70 cfs potential flow) �2=Orifice/Grate ( Controls 0.00 cfs) 3=Orifice/Grate (Orifice Controls 0.09 cfs @ 1.73 fps) =Broad -Crested Rectangular Weir( Controls 0.00 cfs) Postdev POSTDEV Type/1 24-hr 100-YR Rainfall=8.77" Prepared by {enter your company name here} Printed 6/7/2022 HvdroCAD® 9.10 s/n 07054 ©2010 HvdroCAD Software Solutions LLC Paae 11 Time span=0.00-48.00 hrs, dt=0.03 hrs, 1601 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment5S: DA 1 Runoff Area=3.020 ac 7.62% Impervious Runoff Depth=3.56" Tc=5.0 min UI Adjusted CN=57 Runoff=19.89 cfs 0.896 of Link 6L: PDA 1 Inflow=18.35 cfs 0.896 of Primary=18.35 cfs 0.896 of Pond 9P: Detention Pond Peak Elev=542.88' Storage=7,703 cf Inflow=19.89 cfs 0.896 of Outflow=18.35 cfs 0.896 of Total Runoff Area = 3.020 ac Runoff Volume = 0.896 of Average Runoff Depth = 3.56" 92.38% Pervious = 2.790 ac 7.62% Impervious = 0.230 ac Postdev POSTDEV Type/1 24-hr 100-YR Rainfall=8.77" Prepared by {enter your company name here) Printed 6/7/2022 HvdroCAD® 9.10 s/n 07054 ©2010 HvdroCAD Software Solutions LLC Paae 12 Summary for Subcatchment 5S: DA 1 Runoff = 19.89 cfs @ 11.96 hrs, Volume= 0.896 af, Depth= 3.56" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-48.00 hrs, dt= 0.03 hrs Type II 24-hr 100-YR Rainfall=8.77" Area (ac) CN Description 1.970 55 Woods, Good, HSG B 0.820 58 Meadow, non -grazed, HSG B 0.230 98 Unconnected roofs, HSG B 3.020 59 Weighted Average, UI Adjusted CN = 57 2.790 92.38% Pervious Area 0.230 7.62% Impervious Area 0.230 100.00% Unconnected Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Link 6L: POA 1 Inflow Area = 3.020 ac, 7.62% Impervious, Inflow Depth = 3.56" for 100-YR event Inflow = 18.35 cfs @ 11.99 hrs, Volume= 0.896 of Primary = 18.35 cfs @ 11.99 hrs, Volume= 0.896 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-48.00 hrs, dt= 0.03 hrs Summary for Pond 9P: Detention Pond Inflow Area = 3.020 ac, 7.62% Impervious, Inflow Depth = 3.56" for 100-YR event Inflow = 19.89 cfs @ 11.96 hrs, Volume= 0.896 of Outflow = 18.35 cfs @ 11.99 hrs, Volume= 0.896 af, Atten= 8%, Lag= 1.8 min Primary = 18.35 cfs @ 11.99 hrs, Volume= 0.896 of Routing by Stor-Ind method, Time Span= 0.00-48.00 hrs, dt= 0.03 hrs Peak Elev= 542.88' @ 11.99 hrs Surf.Area= 3,686 sf Storage= 7,703 cf Plug -Flow detention time= 103.2 min calculated for 0.896 of (100% of inflow) Center -of -Mass det. time= 103.0 min ( 946.6 - 843.6 ) Volume Invert Avail.Storage Storage Description #1 540.00' 12,302 cf Custom Stage Data (Prismatic)Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic -feet) (cubic -feet) 540.00 1,734 0 0 542.00 3,016 4,750 4,750 544.00 4,536 7,552 12,302 Postdev POSTDEV Type/1 24-hr 100-YR Rainfall=8.77" Prepared by {enter your company name here) Printed 6/7/2022 HvdroCAD@ 9.10 s/n 07054 @ 2010 HvdroCAD Software Solutions LLC Paae 13 Device Routing Invert Outlet Devices #1 Primary 539.00' 15.0" Round Culvert L= 31.0' CMP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 539.00' / 538.00' S= 0.0323 '/' Cc= 0.900 n= 0.012 #2 Device 1 542.00' 24.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 540.00' 3.0" Vert. Orifice/Grate C= 0.600 #4 Primary 542.50' 16.0' long x 13.0' breadth Broad -Crested Rectangular Weir Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 Coef. (English) 2.60 2.64 2.70 2.66 2.65 2.66 2.65 2.63 Primary OutFlow Max=18.09 cfs @ 11.99 hrs HW=542.87' (Free Discharge) 1=Culvert (Inlet Controls 8.41 cfs @ 6.85 fps) �2=Orifice/Grate (Passes < 14.15 cfs potential flow) 3=Orifice/Grate (Passes < 0.39 cfs potential flow) =Broad -Crested Rectangular Weir(Weir Controls 9.68 cfs @ 1.61 fps) Energy Balance Equation Summary Castalia Farm (POA 1) Qdeveloped� I.F. *(Qpre-developed*RVPre-Developed)/Rudeveloped Qdeveloped!5 (Qforested RVforested) Redeveloped Qpre-developed = 0.14 RVpre-Developed = 0.043 Max Qdevelr= 0.09 Cfs RVDeveloped Achieved Post-Dev Max Runoff Qlyr = 0.09 cfs. Site complies with 9VAC25-870-66-(3)A Maximum Q10yr= 3.11 cfs (predev) Achieved Q10yr= 0.89 cfs Castalia Farm Time of Concentration Calculations - Predev POA 7 100 ft overland flow 2.0% slope 0.35 C-value 13.3 min Seelye Chart 658 ft s. c. flow 7.0% slope 1.4 fps velocity 8.1 min. NEH Figure 15-4 swale height min. Kirpich Chart 21.4 min. Outlet Protection Calculations - Reference Nomograph 3.18-3 Pipe Outfall # La ft W ft Do in Do ft 3Do ft d50 ftd50 in Depth in AO 8 9.25 15 1.25 3.75 0.5 6 9 NOAA Atlas 14, Volume 2, Version 3r„,„, �.�' Location name: Keswick, Virginia, USA* y ]®= Latitude: 38.0624o, Longitude:-78.3298o Elevation: 567.07 ft** ' source: ESRI Maps A -- 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)1 Average recurrence interval (years) Duretion 1 2 5 10 25 50 1 100 00 200 500 1000 5-min (0.3116-0388) (0.3776-0.461) (0.4 940.58) (0.4940608) (0.5 5-0683) (0.601---0743) (0.643-0..799) (0.6819652) (0.724-0.919) (0.7600974) 1.39 10-min (0.040620) (0.601-0..737) (0.70 0862) (0.791---0972) (0.884-1.09) (0.957---1.18) (1.021527) (1.08--21335) (1. 5-3145) 1 (1.20-1..53) 1.74 15-min (0.630-0..775) (0.755-0926) 9 (0.'9--11.09) 00 (1.1.23) (1. 2-21538) (1.21-11.1..50) (1.29-1..9) (1.36-516.70) (1.4411.1..83) 1 (1.0- .93) 30-min (0.864--1.06) 1 (1.041528) 1 (1.26-1.5) 1 (1.45-1.78) 1 (1.66-2504) (1.832526) (1.98-2.46) (2.2-2.65) (2.302391) (2: 3-3.12) 4.11 60-min (1.8-1..32) (1.3A561) (1.62-11..99) (1.89-2.32) (2.21-2772) (2A7388) (27 3-3.38) (2.97-3.72) (3. 9�818) (365-4.55) 2.55 2-hr �96) (1.28- 62) (1.54 (1.922A4) (2:02.87) (2. 8-341) (393-3..88) (3.38-4.35) (3. 3-4384) (4.215353) (4.616513) 3-hr (1.38-1.79) (1.67-2916) (2.8-22..69) (2.443.16) (2. 9-3.76) (3.27-4.27) (3654.9) (4.045.35) (4.66.12) (4.99-6.78) 6-hr (17 5-2.5) (2. 0-2872) (2. 0 3536) (3.003.97) (36 5-4.76) (4. 65A5) (4.8-6.18) (5.226.98) (5.96-8.10) (6.609.10) 12-hr (29-2.83) :.02) (2.62-3.40 2 5 (3-4.22) (3.845.00) (4.8) 6 36 (5.32178 (6.048.05) (6. 09.17) (7. 9--110.9) (8.85- 2.4) 253 4-hr (2.62328) (3.137-3.97) 51 (4.045.8) 34 (47 600) (5.82--r�7.35) (6. 06751) 77 (7.609.79) (8.68- 1.2) (102- 3.3) (11,43 15.1) 2-day (3: 0-3.83) (37 5-4.64) (47 6-5.90) (5.6-6.93) (6. 5-8.41) (7.781 9065) (8. 3--111.0) (9.83-12.5) 1 (11 414.7) (12.0 6.5) 5.62 4.0 5.7 3-0ey (3.31-406) (4.0�z91) (5. 96.23) (5.97--67.32) (7.22-8.88) (8. 5--210.2) (9.34-11.6) (105- 3.2) (122- 5.5) (1315-17.4) 4-day -42 (3.538) (42 865.17) (5. 26.57) (6.307..70) (7. 9-�35) (8. 8- 0.7) (9.94- 2.2) 1 (112-13.9) (12.9- 6.3) (1413- 8.3) 12.2 13.8 7-day (4.124.93) (4.96-5.93) (6. 9 42) (7: 9-8.63) (8.61-1.4) (97 6-181.8) (11.0-13.4) (122- 5.1) (14.0-107.5) (155- 9.6) 10-day (47 0-5.55) (5.646.66) (6.96-86.21) (8.01 9348) (9: 9-11.3) (107- 2.7) (11.9-14.3) (13.2-15.9) (14.9- 8.3) (16.3- 0.3) 20 day (628- .23) (7. 06.62) (9.05-10.4) (102-11.8) (11.9-13.7) (1374 5.2) (14.4-6.8) (15.7-18.4) (173-20.5) (18.6-2.3) 30 day (77 5-8.82) (9. 910.5) (10.9- 2.4) (121- 3.8) (13.8-15.7) (15.0-17.1) (162- 8.5) (17.3- 9.9) (18?8-21.8) (19.8 3.2) 45-day (9.73-131.0) 1 (11 512.9) 1 (13.415.1) 1 (14.0 6.7) 1 (167- 8.8) 1 (1819 0.4) 1 (19.3-21.9) 1 (20?5- 3.4) (2A 5.3) (232526.7) 60-day 12.1 74-3 16.5 18.1 20.2 21.8 23.3 1 F-R7 26.4 27.7 (11.5-12.9) .5-15.1) (135.017.4) (1 (17.1-19.2) (19.1-21.4) (20.5-23.0) (21.8-24.6) (23.1-26.1) (24 8-29.5.7-28.0) (25.) 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 AOas 14 document for more information. Back to Top PF graphical .A. MAPLEGEND Area of Interest (A01) 0 Area of Interest A01) Solis Soil Rating Polygons 0 A Q AID o B Q BID o C 0 CID 0 D 0 Not rated or not available Soil Rating Lines . r A ,y AID rV B ram/ BID N C N CID i D . . Not rated or not available Soil Rating Points A Q AID Q B 0 BID Hydrologic Soil Group —Albemarle County, Virginia (Castalia Farm) 0 C CID D 13 Not rated or not available Water Features Streams and Canals Transportation µ� Rails N Interstate Highways ,y US Routes Major Roads Local Roads Background . Aerial Photography MAP INFORMATION The soil surveys that comprise your AOI were mapped at 1:15,800. Please rely on the bar scale on each map sheet for map measurements. Source of Map: Natural Resources Conservation Service Web Soil Survey URL: Coordinate System: Web Mercator (EPSG:3857) Maps from the Web Soil Survey are based on the Web Mercator projection, which preserves direction and shape but distorts distance and area. A projection that preserves area, such as the 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 15, Sep 13, 2021 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. USDA Natural Resources Web Soil Survey 1212212021 Conservation Service National Cooperative Soil Survey Page 2 of 5 Hydrologic Soil Group -Albemarle County, Virginia Castalia Farm Hydrologic Soil Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 13C Catoctin silt loam, 7 to B 11.9 1.0% 15 percent slopes, very stony 16 Codorus silt loam, 0 to 2 B/D 4.1 0.3% percent slopes, occasionally flooded 19B Minnieville loam, 2 to 7 B 31.3 2.5% percent slopes 19C Minnieville loam, 7 to 15 B 18.7 1.5% percent slopes 20C3 Minnieville clay loam, 7 B 7.2 0.6% to 15 percent slopes, severely eroded 23B Yadkin Gay loam, 2 to 7 B 26.4 2.1 % percent slopes 23C Yadkin Gay loam, 7 to B 37.9 3.0% 15 percent slopes 25B Dyke silt loam, 2 to 7 B 139.2 11.2% percent slopes 25C Dyke silt loam, 7 to 15 B 15.2 1.2% percent slopes 26C3 Dyke clay loam, 7 to 15 B 32.5 2.6% percent slopes, severely eroded 32B Orenda silt loam, 2 to 7 C 35.4 2.8% percent slopes 32C Orenda silt loam, 7 to 15 C 14.9 1.2% percent slopes 46B Grassland silt loam, 2 to D 19.7 1.6% 7 percent slopes 51 B Bugley channery silt D 10.5 0.8% loam, 2 to 7 percent slopes 51C Bugley channery silt D 18.5 1.5% loam, 7 to 15 percent slopes 51D Bugley channery silt D 5.5 0.4% loam, 15 to 25 percent slopes 57B Mount Lucas silt loam, 2 C/D 39.6 3.2% to 7 percent slopes 58B Myersville silt loam, 2 to B 9.3 0.7% 7 percent slopes 58C Myersville silt loam, 7 to B 8.3 0.7% 15 percent slopes wQNatural Resources Web Soil Survey 12/22/2021 Conservation Service National Cooperative Soil Survey Page 3 of 5 Hydrologic Soil Group -Albemarle County, Virginia Castalia Farm Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 58D Myersville silt loam, 15 B 4.6 0.4% to 25 percent slopes 59D Myersville very stony silt B 69.5 5.6% loam, 15 to 25 percent slopes 59E Myersville very stony silt B 170.1 13.7% loam, 25 to 45 percent slopes 62B Buffstat silt loam, 2 to 7 B 11.2 0.9% percent slopes 63B Orange silt loam, 2 to 7 C/D 13.0 1.0% percent slopes 71B Rabun clay loam, 2 to 7 B 11.7 0.9% percent slopes 71C Rabun clay loam, 7 to B 61.4 4.9% 15 percent slopes 71D Rabun clay loam, 15 to B 71.5 5.8% 25 percent slopes 71E Rabun clay loam, 25 to B 3.7 0.3% 45 percent slopes 72133 Rabun clay, 2 to 7 B 1.6 0.1 % percent slopes, severely eroded 72C3 Rabun clay, 7 to 15 B 39.0 3.1 % percent slopes, severely eroded 72D3 Rabun clay, 15 to 25 B 6.0 0.5% percent slopes, severely eroded 73C Rabun clay loam, 7 to B 16.6 1.3% 15 percent slopes, very stony 73D Rabun clay loam, 15 to B 32.4 2.6% 25 percent slopes, very stony 73E Rabun clay loam, 25 to B 40.8 3.3% 45 percent slopes, very stony 79B Meadowville silt loam, 2 B 51.8 4.2% to 7 percent slopes 89B Unison silt loam, 2 to 7 B 32.7 2.6% percent slopes 89C Unison silt loam, 7 to 15 B 1.3 0.1 % percent slopes 90C Unison very stony silt B 78.2 6.3% loam, 7 to 15 percent slopes 95 Hatboro silt loam, 0 to 2 B/D 36.4 2.9% percent slopes, occasionally flooded PaNatural Resources Web Soil Survey 12/22/2021 Conservation Service National Cooperative Soil Survey Page 4 of 5 Hydrologic Soil Group —Albemarle County, Virginia Castalia Farm Map unit symbol Map unit name Rating Acres in AOI Percent of AOI W Water 2.6 0.2% Totals for Area of Interest 1,242.0 100.0% Description Hydrologic soil groups are based on estimates of runoff potential. Soils are assigned to one of four groups according to the rate of water infiltration when the soils are not protected by vegetation, are thoroughly wet, and receive precipitation from long -duration storms. The soils in the United States are assigned to four groups (A, B, C, and D) and three dual classes (A/D, B/D, and C/D). The groups are defined as follows: Group A. Soils having a high infiltration rate (low runoff potential) when thoroughly wet. These consist mainly of deep, well drained to excessively drained sands or gravelly sands. These soils have a high rate of water transmission. Group B. Soils having a moderate infiltration rate when thoroughly wet. These consist chiefly of moderately deep or deep, moderately well drained or well drained soils that have moderately fine texture to moderately coarse texture. These soils have a moderate rate of water transmission. Group C. Soils having a slow infiltration rate when thoroughly wet. These consist chiefly of soils having a layer that impedes the downward movement of water or soils of moderately fine texture or fine texture. These soils have a slow rate of water transmission. Group D. Soils having a very slow infiltration rate (high runoff potential) when thoroughly wet. These consist chiefly of clays that have a high shrink -swell potential, soils that have a high water table, soils that have a claypan or clay layer at or near the surface, and soils that are shallow over nearly impervious material. These soils have a very slow rate of water transmission. If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes. Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff.- None Specified Tie -break Rule: Higher Natural Resources Web Soil Survey 12/22/2021 Conservation Service National Cooperative Soil Survey Page 5 of 5