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HomeMy WebLinkAboutWPO201900008 Calculations WPO VSMP 2019-08-09 S 1.1 IMp PROJECTMANAGEMENT ENGINEERING LAND PLANNING ENGINEERING (`," ) February 13, 2019 County of Albemarle Department of Community Development 401 McIntire Road Charlottesville, VA 22902 Regarding: Hendy Residence Stormwater Management Plan Dear Reviewer, The purpose of this project is to build a house and driveway on a currently vacant parcel. The stormwater management for this site is analyzed at two different points. The stormwater for Point of Analysis 1 will be addressed through the use of a detention pond. The energy balance equation is satisfied, and a summary of pre and post development flow rates is in the table below. For the remainder of the site, the stormwater is released as sheet flow. Hendy Residence Energy Balance Equation 24 Hr 1 year Storm: �1 �cdeveloped I•F• Qpre-developed RVPre-Developed) RVdeveloped Qdeveloped (Qforested*RVforested)/Redeveloped Qpre-developed = 0.28 RVpre-Developed = 0.033 MaxQdeveloped = 0.14 cfs RVDeveloped = 0.054 Qdeveloped = 0.10 cfs PreDevelopment PostDevelopment POA 1 10 yr 2.63 1.25 According to the VRRM spreadsheet included in this packet, the dedication of 1.58 acres to conserved open space will negate nutrient removal requirements. APPROVED by the Albemarle County CommUnY( v ►oom t Department Date Contents: Pre-Development Stormwater Management Calculations: Pre-Development Drainage Map Pre-Development HydroCAD Analysis Post-Development Stormwater Management Calculations: Post-Development Drainage Map Post-Development HydroCAD Analysis Time of Concentration Calculations: Pre-Development Time of Concentration Calculations Post-Development Time of Concentration Calculations Nomographs Stormwater Quality Calculations: VRRM New Development Spreadsheet Independent Reports: Excerpt from NRCS Soils Report NOAA Precipitation Report Pre-Development Stormwater Management Calculations Pre-Development Drainage Map Pre-Development HydroCAD Analysis hENDY RESIDENCE PRE—DEV DRAINAGE MAP ` \ \\ \ \\ \ \ \ \ \\ \ \ \ \ \\\ \ \ \ \ \ \ \ \ \ \ \ X \\\ \\ \ \ N �\ \\ \ 1 I IT 1 / / / � / r / / �/ /' /V , \\\\� \�\\\\;$\\\(`\'I`\\\ \ \\ \\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ �\ \ \�� \ I / / / // / // \\ \\ \\\ \ \ \ I 1 I \ \ 1 \ \ \ 1 1 \ \ \ \ \ \ \ \ \ \i I I I I I 1 I I 1 Ir I //// / // ////�/i/� / /� / /.-- \ \\\ \ I III `� ) 1 i \i \ \\ \I 1 \III 1 I I / / I . 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Link Drainage Diagram for PreDev �� Prepared by Shimp Engineering, Printed 2/11/2019 HydroCADe 9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC PreDev Type 1124-hr 1 yr, 24 hr Rainfall=3.06" Prepared by Shimp Engineering Printed 2/11/2019 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 2 Summary for Subcatchment 1 S: Pre Dev Pond DA Runoff = 0.28 cfs @ 12.11 hrs, Volume= 0.033 af, Depth> 0.29" Runoff by SCS TR-20 method, UH=SCS, Time Span=0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 1 yr, 24 hr Rainfall=3.06" Area (sf) CN Description 59,198 58 Woods/grass comb., Good, HSG B 59,198 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 13.0 Direct Entry, PreDev Type 1124-hr 10 yr, 24 hr Rainfall=5.59" Prepared by Shimp Engineering Printed 2/11/2019 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 3 Summary for Subcatchment 1 S: Pre Dev Pond DA Runoff = 2.63 cfs @ 12.06 hrs, Volume= 0.170 af, Depth> 1.50" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr, 24 hr Rainfall=5.59" Area (sf) CN Description 59,198 58 Woods/grass comb., Good, HSG B 59,198 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 13.0 Direct Entry, Post-Development Stormwater Management Calculations Post-Development Drainage Map Post-Development HydroCAD Analysis I-1ENDY RESIDENCE POST—DEV DRAINAGE MAP ��\��\� ��\ —\���� \ NNN\ NNN N ` \ \ \ \ \ \ \ \ • ,-. . . \ - N „ N \ ' Il i / / . / / � / \ \ \ \ \ \ \ N. \ \ \ �\ I / /\ \ \ \ \ � \ \ \ N \ L___ l / / i/ / \ \ 1 \ \ \ \ \ \ \ \ \ \ \ \ \ \ N / I / 1l I / / / / / / / / 7 \ \\ \ \\ \ \ \ �.\ \\\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ / I I / / / / / / i / / 7 / /: \\\� \\ \ ' \ \ 1\ \ \\\\ ‹...,,,,......\ y \ \ \ \ \ \\ \ \ \ \ \\ \ \ \ \\ \\ \ \\ \ \ \ 1 I 1 I I I / / / / / / / / / // �� �� \ \ \ \ \ . \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ 1 ( / / / // / / / , _ \\\\ \\\\\\� 1 \ \ I r \-!' \ \ \ \ \ \ \ \ \ \ \ \ \ \ 1 iI i I I I 1 1 1 1 1 1 1 / / / / / /// i '� -�' Aii \ \ 1 I I ; �I 1. a I I \_\ \ \ 1 \ \\\I 1 \I \1 \1 1 $ I I t I I I I I // / //// / / //// /' r� / / ) I111 I1 // -rI I I � , I � I �r-1 �1 \ \ 1 1 I I l 1 I 1 j I I I I I I I I I I I I I / / / / / � � 1 � ` / 1I11 I � 1 I\ ' I I 1 1 I ��� � I J \ 1 \ I / / / / / / / I I I I I I I I. 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Orifice/Grate C= 0.600 #3 Device 1 738.00' 6.0" Vert. Orifice/Grate C= 0.600 #4 Primary 739.60' 36.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads PostDev Type 1124-hr 1 yr, 24 hr Rainfall=3.06" Prepared by Shimp Engineering Printed 2/12/2019 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 3 Primary OutFlow Max=0.10 cfs @ 12.98 hrs HW=737.92' (Free Discharge) —1=Culvert (Passes 0.10 cfs of 2.97 cfs potential flow) t2=Orifice/Grate (Orifice Controls 0.10 cfs @ 4.41 fps) 3=Orifice/Grate ( Controls 0.00 cfs) —4=Orifice/Grate ( Controls 0.00 cfs) PostDev Type 1124-hr 10 yr, 24 hr Rainfall=5.59" Prepared by Shimp Engineering Printed 2/12/2019 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 4 Summary for Subcatchment 1 S: Post Dev Pond DA Runoff = 3.77 cfs @ 12.04 hrs, Volume= 0.223 af, Depth> 1.97" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 10 yr, 24 hr Rainfall=5.59" Area (sf) CN Description 5,120 58 Woods/grass comb., Good, HSG B 48,402 61 >75%Grass cover, Good, HSG B 5,676 98 59,198 64 Weighted Average 53,522 90.41% Pervious Area 5,676 9.59% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.8 Direct Entry, Summary for Pond 3P: Detention Pond Inflow Area= 1.359 ac, 9.59% Impervious, Inflow Depth > 1.97" for 10 yr, 24 hr event Inflow = 3.77 cfs @ 12.04 hrs, Volume= 0.223 af Outflow = 1.25 cfs @ 12.25 hrs, Volume= 0.214 af, Atten= 67%, Lag= 12.3 min Primary = 1.25 cfs @ 12.25 hrs, Volume= 0.214 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 739.57' @ 12.25 hrs Surf.Area= 1,674 sf Storage= 2,865 cf Plug-Flow detention time= 67.6 min calculated for 0.213 af (96%of inflow) Center-of-Mass det. time= 45.1 min ( 901.8 - 856.7 ) Volume Invert Avail.Storage Storage Description #1 737.00' 3,623 cf Custom Stage Data(Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 737.00 600 0 0 739.00 1,386 1,986 1,986 740.00 1,887 1,637 3,623 Device Routing Invert Outlet Devices #1 Primary 737.00' 15.0" Round Culvert L= 100.0' Ke= 0.600 Inlet/Outlet Invert= 737.00'/735.00' S= 0.0200 '/' Cc= 0.900 n= 0.012 #2 Device 1 737.00' 2.0" Veil. Orifice/Grate C= 0.600 #3 Device 1 738.00' 6.0" Vert. Orifice/Grate C= 0.600 #4 Primary 739.60' 36.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads PostDev Type 1124-hr 10 yr, 24 hr Rainfall=5.59" Prepared by Shimp Engineering Printed 2/12/2019 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 5 Primary OutFlow Max=1.25 cfs @ 12.25 hrs HW=739.57' (Free Discharge) —1=Culvert (Passes 1.25 cfs of 7.73 cfs potential flow) 4L2=Orifice/Grate (Orifice Controls 0.17 cfs @ 7.60 fps) 3=Orifice/Grate (Orifice Controls 1.09 cfs @ 5.54 fps) —4=Orifice/Grate ( Controls 0.00 cfs) PostDev Type 1124-hr 100 yr, 24 hr Rainfall=9.13" Prepared by Shimp Engineering Printed 2/12/2019 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 6 Summary for Subcatchment 1 S: Post Dev Pond DA Runoff = 9.13 cfs @ 12.04 hrs, Volume= 0.531 af, Depth> 4.69" Runoff by SCS TR-20 method, UH=SCS, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 100 yr, 24 hr Rainfall=9.13" Area (sf) CN Description 5,120 58 Woods/grass comb., Good, HSG B 48,402 61 >75%Grass cover, Good, HSG B 5,676 98 59,198 64 Weighted Average 53,522 90.41% Pervious Area 5,676 9.59% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 11.8 Direct Entry, Summary for Pond 3P: Detention Pond Inflow Area = 1.359 ac, 9.59% Impervious, Inflow Depth > 4.69" for 100 yr, 24 hr event Inflow = 9.13 cfs @ 12.04 hrs, Volume= 0.531 af Outflow = 8.98 cfs @ 12.06 hrs, Volume= 0.511 af, Atten= 2%, Lag= 1.0 min Primary = 8.98 cfs @ 12.06 hrs, Volume= 0.511 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 739.99' @ 12.06 hrs Surf.Area= 1,883 sf Storage= 3,606 cf Plug-Flow detention time= 39.8 min calculated for 0.511 af (96%of inflow) Center-of-Mass det. time= 18.6 min ( 850.3 - 831.6 ) Volume Invert Avail.Storage Storage Description #1 737.00' 3,623 cf Custom Stage Data (Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (sq-ft) (cubic-feet) (cubic-feet) 737.00 600 0 0 739.00 1,386 1,986 1,986 740.00 1,887 1,637 3,623 Device Routing Invert Outlet Devices #1 Primary 737.00' 15.0" Round Culvert L= 100.0' Ke= 0.600 Inlet/Outlet Invert= 737.00'/735.00' S= 0.0200 'I' Cc= 0.900 n= 0.012 #2 Device 1 737.00' 2.0"Vert. Orifice/Grate C= 0.600 #3 Device 1 738.00' 6.0" Vert. Orifice/Grate C= 0.600 #4 Primary 739.60' 36.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads PostDev Type 1124-hr 100 yr, 24 hr Rainfall=9.13" Prepared by Shimp Engineering Printed 2/12/2019 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 7 Primary OutFlow Max=8.88 cfs @ 12.06 hrs HW=739.99' (Free Discharge) —1=Culvert (Passes 1.43 cfs of 8.52 cfs potential flow) t2=Orifice/Grate (Orifice Controls 0.18 cfs @ 8.21 fps) 3=Orifice/Grate (Orifice Controls 1.25 cfs @ 6.35 fps) —4=Orifice/Grate (Weir Controls 7.46 cfs @ 2.04 fps) Time of Concentrations Calculations Pre-Development Time of Concentration Calculations Post-Development Time of Concentration Calculations Nomographs Hendy Residence Pre-Development Time of Concentration Calculations Pond Drainage Area (Red) 100 ft overland flow-woods 31.6% slope 0.20 C-value 9.0 min. Seelye Chart 321 ft s. c.flow-turf 30.6% slope 1.4 fps velocity 4.0 min. NEH Figure 15-4 13.0 min. Hendy Residence Post-Development Time of Concentration Calculations Pond Drainage Area (Blue) 100 ft overland flow-woods 31.6% slope 0.20 C-value 9.0 min. Seelye Chart 408 ft channelized flow 56 ft above outlet 2.8 min. Kirpich Chart TOC 11.8 min. Cl 0 LENGTH " L" OF STRIP IN FEET 2 I ► ► ► i , ► ► 1 ► 1 1 I 1 1 ► 1 ► I ' 1 ► 1 ' ► ► ► ►/1 -1Ti ► 1 i 0 — N W - N i . U► Q) -1 CO ► O O a 0 0 O O O 0 0 0 • O / O 0 !� N < U) C] 0 S.tri C 'CHARACTER� OF I GROUND rn ..: C"✓ALIT N /tr is u w `► pe a C'VALUB 05. fa ^ r / y � D / � Z M ( v 71 PIVOT LINE O \ —4 N — SP N — O 0 0 0 0 0 6 K I . luul ► i I a [milrn PERCENT SLOPE \ b \ a. - \- N N W W cn Cr) -4 aD • 0 U► 0 0 0 U► INLET CONCENTRATION TIME IN. MINUTES ,- .- ,-o00 P 0 © © 0 0 o 0 o m co --4 ob en 4 ca ND o GC,CC-4 0 cn a CO is :- 900'0 --�I MINI EMI vi flArs • 1 pv, L.., Q. le o 42 ,? GT �" a*S° Iti0 air - imow J 4 aI/ . r lIM T* LO 0 — 4I111 " N 80•0 MAi •s/L. o t 60'0 w /Ji 4 OT 0Mga Plip,J" l AIM, 0 er :.: _���_ �.o IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII OL'0 08'0 06'0 00'T TRAVEL TIME FOR CHANNEL FLOW (Kirpich Chart) H (feet) E 500 Tc (min.) —200 -100 100 L (feet) 10000 f = _- 50 Ex = c -_ 50 -5000 m • _ C L u - 4 C Note: w o c▪ — o _ v - a (1) For use with natural channels; at+ = a, c_= o 1, 10 ) For paved channels, multiply 2 = 1000 . _ 10 h — K _ E — S w ` 5 ._500 - 5 0 t .— rn _ 'y —100 - L— 1 I TIME OF CONCENTRATION OF SMALL DRAINAGE BASINS Source: VDOT Plate 5-3 Stormwater Quality Calculations VRRM New Development Spreadsheet Project Name: Hendy Residence Date: 2/B/2019039 ggrralarR valllag BMP Design Specifications List:2013 Draft Stds&Specs Site Information Post-Development Project(Treatment Volume and Loads) Land Cover(acres) A Soils s Soils C Soils 0 Soils Totals Forest/Open Space(acres)-undisturbed, 1.58 Protected forest/open space or reforested land 1.58 Managed Turf(acres)..disturbed,graded for yards or other turf to be mowed/managed 0.33 1.13 1d6 Impervious Cover(acres) 0.07 0.22 0.29 •Forest/Open Spore areas trust be prater t a,co,dro<.-wr.f,rr„ q p'nr,f/p,nucr„f4,.0.rd 3.33 Constants Runoff Coefficients(Rv) Annual Rainfall(inches) 43 A Soils II Soils C Soils D Soils Target Rainfall Event(inches) 1.00 Forest/Open Space 0.02 0.03 0.04 0.05 Total Phosphorus)TP)EMC Img/LI 0.26 _ Managed Turf 0.15 0.20 0.22 0.25 Total Nitrogen(TN)EMC(mg/L) 1.86 Impervious Cover 0.95 0.95 0.95 0.95 Target TP Load(lb/acre/yr) 0.41 Pj(unitless correction factor) 0.90 Post-Development Requirement for Site Area TP Load Reduction Required(lb/yr) 0.00 ** TP LOAD REDUCTION NOT REQUIRED LAND COVER SUMMARY--POST DEVELOPMENT Land Cover Summary Treatment Volume and Nutrient Loads Forest/Open Space Cover(acres) 1.58 Treatment(acre k)lume 00499 Weighted Re(forest) 003 Treatment Volume(cubic feet) 2,172 %Forest 47% TP Load(Ib/yr) 1.36 Managed Turf Cover(acres) 1.46 • 9.76 Weighted Re(turf) 0.19 %Managed Turf 44% Impervious Cover(acres) 0.29 Re(impervious) 0.95 %Impervious 9% Site Area(acres) 3.33 Site Results(Water Quality Compliance) Area Checks D.A.A D.A.B D.A.C D.A.D D.A.E AREA CHECK FOREST/OPEN SPACE(ac) 0.00 0.00 0.00 I 0.00 0.00 OK. IMPERVIOUS COVER(ac) 0.00 0.00 0.00 0.00 0.00 OK. IMPERVIOUS COVER TREATED(ac) 0.00 0.00 0.00 0.00 0.00 OK. MANAGED TURF AREA(ac) 0.00 0.00 0.00 0.00 0.00 OK. - MANAGED TURF AREA TREATED(ac( 0.00 0.00 0.00 0.00 0.00 OK. l AREA CHECK OK. OK. I OK. OK_ OK. e Site Treatment Volume(ft)) 2,172 d Runoff Reduction Volume and TP By Drainage Area D.A.A D.A.B I D.A.C D.A.D D.A.E TOTAL RUNOFF REDUCTION VOLUME ACHIEVED(ft) 0 0 0 - 0 0 0 1 TP LOAD AVAILABLE FOR REMOVAL(Ib/yr) 0.00 0.00 0.00 0.00 0.00 0.00 TP LOAD REDUCTION ACHIEVED(Ib/yr) 0.00 0.00 ' 0.00 0.00 0.00 0.00 TP LOAD REMAINING(Ib/yr) 0.00 0.00 0.00 0.00 0.00 1 0.00 NITROGEN LOAD REDUCTION ACHIEVED(Ib/yr) 0.00 0.00 0.00 1 0.00 i 0.00 0.00 Total Phosphorus FINAL POST-DEVELOPMENTTP LOAD(Ib/yr) 1.36 TP LOAD REDUCTION REQUIRED(Ib/yr) 0.00 TP LOAD REDUCTION ACHIEVED(Ib/yr) 0.00 TP LOAD REMAINING(Ib/yr): 1.36 REMAINING TP LOAD REDUCTION REQUIRED(Ib/yr):I 0.00 it. ."'No further TP load reduction required Total Nitrogen(For Information Purposes) POST-DEVELOPMENT LOAD(Ib/yr)1 9.76 NITROGEN LOAD REDUCTION ACHIEVED(Ib/yr) 0.00 REMAINING POST-DEVELOPMENT NITROGEN LOAD(lb/yr) 9.76 Virginia Runoff Reduction Method Worksheet DEQ Virginia Runoff Reduction Method New Development Compliance Spreadsheet -Version 3.0 BMP Design Specifications List: 2013 Draft Stds&Specs Site Summary Project Title:Hendy Residence Date:43504 Total Rainfall= 43 inches Site Land Cover Summary A soils B Soils C Soils D Soils Totals %of Total Forest/Open(acres) 0.00 1.58 0.00 0.00 1.58 47 Managed Turf(acres) 0.33 1.13 0.00 0.00 1.46 44 Impervious Cover(acres) 0.07 0.22 0.00 0.00 0.29 9 3.33 100 Site Tv and Land Cover Nutrient Loads Site Rv 0.18 Treatment Volume(ft) 2,172 TP Load(lb/yr) 1.36 TN Load(lb/yr) 9.76 Total TP Load Reduction Required(Ib/yr) 0.00 TP LOAD REDUCTION NOT REQUIRED Site Compliance Summary Total Runoff Volume Reduction(ft) 0 Total TP Load Reduction Achieved(Ib/yr) 0.00 Total TN Load Reduction Achieved(Ib/yr) 0.00 Remaining Post Development TP Load (Ib/yr) 1.36 • Remaining TP Load Reduction(Ib/yr) 0.00 **No further TP load reduction required Required Drainage Area Summary Summary Print Independent Reports Excerpt from NRCS Soils Report NOAA Precipitation Report Custom Soil Resource Report Soil Map 704000 704100 704200 704300 704400 704500 701610 704700 704E00 704900 7050)) 705100 37°58'28"N 37°58'28"N r It ..,,,,,,''''..... / 3 F'E:". /36C -� 4E 1 19B =- 1 C 41 / + 19D f s } c 36D 20D3 56C 36C\-,„\\,.........„\\ _ -, — ,... i w. , 25C 56C ' + � r� . c�. 25B 56C .► +1' • ti a l• v A n %;,20C3 �4101 . �d°F. • i 26D3� . _ , P 1 , y, , ft..' F 20M]Ntlp(IO tly not,C�ntll tiI this`s cdic. t ` '� '' .. 37 58 2"N G - 37°58'2"N 701000 704100 701200 704300 704400 704500 701600 704700 7045W 704900 705000 705100 705200 3 3 4 Map Scale:1.5,680 if printed on A landscape(11"x 8.5')Sheet Meters N 0 50 100 Z00 300 m Feet 0 150 500 Comer100D 1500 Map pr ojecBon:Web MenaQ7r Coer coordinates:W Edge tla Uf: M Zone 17N WG584 A Custom Soil Resource Report MAP LEGEND MAP INFORMATION Area of Interest(AOI) Spoil Area The soil surveys that comprise your AOI were mapped at n Area of Interest(AOI) Stony Spot 1:15,800. Soils — 63 Very Stony Spot Soil Map Unit Polygons Warning:Soil Map may not be valid at this scale. Wet Spot 0%y Soil Map Unit Lines Enlargement of maps beyond the scale of mapping can cause Other misunderstandingof the detail of mapping and accuracyof soil • Soil Map Unit Points PP 9 .. Special Line Features line placement.The maps do not show the small areas of Special Point Features contrasting soils that could have been shown at a more detailed V Blowout Water Features scale. Streams and Canals kg - Borrow Pit Transportation Please rely on the bar scale on each map sheet for map • Clay Spot 4-r t Rails measurements. © Closed Depression 04,/ Interstate Highways Gravel Pit Source of Map: Natural Resources Conservation Service 0,1,0 US Routes Web Soil Survey URL: Gravelly Spot Major Roads Coordinate System: Web Mercator(EPSG:3857) 4 Landfill Local Roads Maps from the Web Soil Survey are based on the Web Mercator k Lava Flow Background projection,which preserves direction and shape but distorts distance and area.A projection that preserves area,such as the Ali Marsh or swamp . Aerial Photography Albers equal-area conic projection,should be used if more 'R' Mine or Quarry accurate calculations of distance or area are required. O Miscellaneous Water This product is generated from the USDA-NRCS certified data as O Perennial Water of the version date(s)listed below. y Rock Outcrop Soil Survey Area: Albemarle County,Virginia + Saline Spot Survey Area Data: Version 12,Aug 29,2018 Sandy Spot Soil map units are labeled(as space allows)for map scales O Severely Eroded Spot 1:50,000 or larger. • Sinkhole Date(s)aerial images were photographed: Apr 22,2015—Mar 11, Slide or Slip 10,2017 • Sodic Spot 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. 10 Custom Soil Resource Report Map Unit Legend Map Unit Symbol Map Unit Name Acres In AOI Percent of AOI 4E Ashe loam,25 to 45 percent 18.5 28.1% slopes 19B Cullen loam,2 to 7 percent 0.6 0.9% slopes 19C Cullen loam,7 to 15 percent 4.2 6.4% slopes 19D Cullen loam, 15 to 25 percent 2.0 3.0% slopes 20C3 Cullen clay loam,7 to 15 2.5 3.8% percent slopes,severely eroded 20D3 Cullen clay loam, 15 to 25 3.8 5.8% percent slopes,severely eroded 25B Dyke silt loam,2 to 7 percent 0.0 0.1% slopes 25C Dyke silt loam,7 to 15 percent 0.6 1.0% slopes 26D3 Dyke clay loam, 15 to 25 1.4 2.1% percent slopes,severely eroded 36B Hayesville loam,2 to 7 percent 2.2 3.4% slopes 36C Hayesville loam,7 to 15 percent 7.6 11.6% slopes 36D Hayesville loam, 15 to 25 18.0 27.3% percent slopes 56C Meadowville loam,7 to 15 4.3 6.6% percent slopes Totals for Area of Interest 65.8 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas.A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. 11 2/8/2019 Precipitation Frequency Data Server NOAA Atlas 14,Volume 2,Version 3 Ntt '`" 4,, Location name: North Garden,Virginia,USA* ✓ 4.11 ' Latitude:37.9686°,Longitude:-78.6704° r nowt Elevation:849.5 ft** , p 'source:ESRI Maps y� "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 inchesjl Average recurrence interval(years) Duration 1 2 5 10 25 50 100 200 500 1000 0.343 0.408 0.480 0.542 0.612 0.666 0.716 0.764 0.821 0.868 5-min (0.310-0.379) (0.370-0.452) (0.434-0.530) (0.489-0.598) (0.549-0.674) (0.594-0.733) (0.635-0.790) (0.672-0.844) (0.713-0.910) (0.747-0.967) 10-min 0.548 0.653 0.769 0.867 0.975 1.06 1.14 1.21 1.30 1.37 (0.495-0.606) (0.591-0.723) (0.695-0.849) (0.782-0.957) (0.874-1.07) (0.946-1.17) (1.01-1.25) (1.07-1.34) (1.13-1.44) (1.18-1.52) 15-min 0.684 0.821 0.973 1.10 1.24 1.34 1.44 1.53 1.63 1.72 (0.618-0.758) (0.743-0.909) (0.879-1.07) (0.989-1.21) (1.11-1.36) (1.20-1.48) (1.28-1.59) (1.34-1.69) (1.42-1.81) (1.48-1.91) 30-min 0.938 1.13 1.38 1.59 1.83 2.02 2.20 2.38 2.60 2.78 (0.848-1.04) (1.03-1.25) (1.25-1.53) (1.43-1.75) (1.64-2.02) (1.80-2.23) (1.95-2.43) (2.09-2.63) (2.26-2.88) (2.39-3.09) 1.17 1.42 1.77 2.07 2.44 2.74 3.04 3.34 3.73 4.06 60-min (1.06-1.30) (1.29-1.58) (1.60-1.96) (1.87-2.28) (2.19-2.68) (2.44-3.02) (2.69-3.35) (2.94-3.68) (3.24-4.14) (3.49-4.52) 2-hr 1.40 1.70 2.13 2.51 2.99 3.39 3.80 4.23 4.81 5.31 (1.25-1.58) (1.51-1.91) (1.89-2.39) (2.23-2.81) (2.64-3.35) (2.98-3.80) (3.31-4.26) (3.65-4.74) (4.11-5.41) (4.47-5.99) 3-hr 1.54 1.86 2.33 2.74 3.27 3.72 4.17 4.65 5.30 5.86 (1.37-1.74) (1.65-2.11) (2.06-2.64) (2.42-3.10) (2.87-3.69) (3.25-4.19) (3.62-4.71) (4.00-5.25) (4.50-6.01) (4.91-6.66) 6-h r 1.99 2.41 2.99 3.52 4.23 4.86 5.51 6.21 7.21 8.10 (1.78-2.24) (2.15-2.71) (2.65-3.36) (3.12-3.96) (3.72-4.76) (4.23-5.45) (4.75-6.19) (5.30-7.00) (6.05-8.15) (6.69-9.18) 12-hr 2.53 3.05 3.80 4.51 5.48 6.36 7.30 8.34 9.88 11.3 (2.25-2.88) (2.72-3.48) (3.37-4.32) (3.98-5.12) (4.79-6.21) (5.49-7.20) (6.23-8.27) (7.01-9.46) (8.12-11.2) (9.11-12.9) - 24-hr 3.06 3.71 4.73 5.59 6.86 7.94 9.13 10.4 12.4 14.1 (2.75-3.44) (3.33-4.16) (4.24-5.31) (4.99-6.25) (6.08-7.65) (6.99-8.84) (7.97-10.2) (9.02-11.6) (10.5-13.8) (11.8-15.7) 3.61 4.38 5.56 6.53 7.93 9.11 10.4 11.8 13.8 15.5 2-day (3.25-4.03) (3.94-4.89) (4.99-6.20) (5.84-7.28) (7.05-8.83) (8.04-10.1) (9.10-11.5) (10.2-13.1) (11.8-15.4) (13.1-17.3) 3.85 4.66 5.91 6.94 8.42 9.66 11.0 12.4 14.6 16.3 3-day (3.48-4.27) (4.22-5.18) (5.34-6.56) (6.25-7.69) (7.55-9.32) (8.60-10.7) (9.72-12.2) (10.9-13.8) (12.6-16.2) (14.0-18.2) 4-day (3.72-4.51) 4.94 6.26 7.34 8.90 10.2 11.6 13.1 15.3 17.2 (3.72-4.51) (4.50-5.46) (5.70-6.92) (6.66-8.10) (8.04-9.82) (9.16-11.3) (10.4-12.8) (11.6-14.5) (13.4-17.0) (14.9-19.1) 4.73 5.70 7.12 8.28 9.93 11.3 12.8 14.3 16.6 18.5 7-day (4.34-5.18) (5.23-6.24) (6.52-7.79) (7.56-9.05) (9.02-10.9) (10.2-12.4) (11.4-14.0) (12.8-15.7) (14.6-18.2) (16.0-20.3) 10-day 5.37 6.45 7.95 9.16 10.8 12.2 13.7 15.2 17.3 19.1 (4.95-5.83) (5.94-7.00) (7.31-8.62) (8.40-9.93) (9.90-11.8) (11.1-13.2) (12.3-14.8) (13.6-16.5) (15.4-18.8) (16.8-20.8) 20-day 7.04 8.40 10.1 11.5 13.3 14.8 16.3 17.8 19.8 21.4 (6.57-7.58) (7.84-9.03) (9.44-10.9) (10.7-12.3) (12.4-14.3) (13.6-15.9) (15.0-17.5) (16.2-19.1) (18.0-21.4) (19.3-23.2) 8.65 10.2 12.1 13.5 15.4 16.8 18.1 19.5 21.2 22.6 30-day (8.11-9.24) (9.61-10.9) (11.3-12.9) (12.7-14.4) I (14.3-16.4) (15.6-17.9) (16.8-19.4) (18.0-20.9) (19.5-22.8) (20.7-24.3) 45-day 10.8 12.8 14.9 16.5 18.5 20.0 21.5 22.9 24.7 26.0 (10.2-11.5) (12.0-13.5) (14.0-15.8) (15.5-17.5) (17.4-19.6) (18.8-21.3) (20.1-22.8) (21.3-24.4) (22.9-26.4) (24.0-27.8) - 60-day 12.7 14.9 17.2 18.9 21.0 22.6 24.1 25.5 27.3 28.6 (12.0-13.4) (14.1-15.7) (16.2-18.1) (17.8-19.9) (19.8-22.2) (21.2-23.8) (22.6-25.4) (23.8-27.0) (25.4-28.9) (26.5-30.3) 1 Precipitation frequency(PF)estimates in this table are based on frequency analysis of partial duration series(PDS). Numbers in parenthesis are PF estimates at lower and upper bounds of the 90%confidence interval.The probability that precipitation frequency estimates(for a given duration and average recurrence interval)will be greater than the upper bound(or less than the lower bound)is 5%.Estimates at upper bounds are not checked against probable maximum precipitation(PMP)estimates and may be higher than currently valid PMP values. Please refer to NOAA Atlas 14 document for more information. sack to Top https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=37.9686&Ion=-78.6704&data=depth&units=english&series=pds 1/4