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WPO201800049 Calculations 2019-05-06
i PROJECT MANAGEMENT S I, ,:y CIVIL ENGINEERING LAND PLANNING ENGINEERINGa December 11, 20"18 County of Albemarle Department of Community Development APPROVED 401 McIntire Road by the Albemarle County Charlottesville, VA 22902 Communit elop er,t�epartment Date C,Regarding: Oak Hill Convenience Store File 7c k L • ��q 1 Stormwater Management Plan Dear Reviewer, The purpose of this project is to add a 6-pump gas canopy to an existing convenience store with barber shop on site. The site is zoned C1. The stormwater management for this site will be addressed through the use of a detention pipe. The energy balance equation is satisfied, and a summary of pre and post development flow rates is in the table below. Note that for Point of Analysis 2, a portion of the drainage area is offsite. The flow rate from the offsite area is subtracted from the flow rate at the point of analysis. The resulting flow rate is used to determine whether the energy balance equation is satisfied. Oak Hill Convenience Store Energy Balance Equation 24 Hr 1 year Storm: Qdeveloped I.F. *(Qpre-developed*RVpre-Developed)/RVdeveloped Qdeveloped (Qforested*RVforested)/Rudeveloped Point of Analysis 1 Point of Analysis 2 I Qpre-developed= 0.40 Qpre-developed= 1.19 RVpre-Developed= 0.021 �MaxQdeveloped= .47 cfs RVpre-Developed= 0.057 MaxQdeveloped= .61 cfs RVDeveloped= 0.016 vdeveloped= .32 cfs RVDeveloped= 0.1 Qdeveloped= .26 cfs PreDevelopment PostDevelopment POA 1 10 yr 0.75 0.66 POA 2 10 yr 3.15 2.92 According to the VRRM spreadsheet included in this packet, the target phosphorus load reduction is 0.32 lb/yr. This requirement will be met with the purchase of nutrient credits. Contents: Pre-Development Stormwater Management Calculations: Pre-Development SWM Map Pre-Development HydroCAD Analysis Post-Development Stormwater Management Calculations: Post-Development SWM 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 Redevelopment Spreadsheet Independent Reports: Excerpt from NRCS Soils Report NOAA Precipitation Report Pre-Development Stormwater Management Calculations Pre-Development SWM Map Pre-Development HydroCAD Analysis - _\------- Pre Development -44__/ - - SWM Ma p_ \ -- _ .1-•1♦?�►►:11i=1cevt1oii;1r1•tC.11-47:4�;=10�z1�� t;om �14;1;v �_•,►a;�`i • --- -- -..„....... _ I 1..*V11 ;111.1111��,t04.4►111111I1 , 111111fj111/111111 �*1111111111 ROAD 11i, 11� Ock - ill Store e n i e n c e • , , i 11111111111111111�• � 11 �11 � 4,140 SF *• 1 /1�111111/1111111•111111�• 111�11 so.% d,/ b11� 11�11111� 111j1 =11� .1-• �1�•. 4b111i �i111 1111�1111 � E / /1� // 11111� SI D A 11111111- Y' 1 /1 24,533 SF 1111111,/ � 1111 1111 �/ 111�11111111/11111111•" • /i . 14��4"•••1�� 1111111111�� 1 slit -- 1� 1 -- • • i. • • / �W ♦� j14W ►1� �11P 1IL ; , / / // ��► W ►1� W 111� o11114� sw. , -- -`----=L , TMP 76-52P /'l✓ •. 44 4fr* % I !! :I 4,„2 _.—-/-,--7/-1,-4 ' 1.�; o' .11j % t - . .9,-' / // . ' • ,HSQ,B / ���` ID ,M� jST 1 W--; • / )iJç , / '°'�W' / _ ��`j�/11� W , /,7 ,- _, - \ -, . . t I4 �1�,/y ��.I u. W *" /. /W•• i / i 1 l / \ / / -_ ' ��'` I . '----, • ft- 4- ,i-Vo•— — --- 4- 4 4, 4110101); / jf vim_ -_ �-� ' / / / 1 / / / 1 / / / / — -� -,ti •---- / / / I Time of Concentration: ,' ------------\\� — — — _ •~ '' /' /' i''�- \ // t ix ' i I 6.5 minutes / ' / // / /, - / it..4,4,....„12......sii `-- - / / i - / —••—••—••— Limits of Disturbance: / si �'� +s,_ ---- _-r/ �- .\ 0.66 acres - %W % ----' i / / 1 '/ r 2 7 ■ ■ Soil Divide _ _ C /�% J• +6p -- - I i , - I HSG B MvB -,:„/ ; I, HSG A li _?0 OPEN SPACE ----\--.\'S\ a'� 4�'� Total 0.00 acres a i: �• \ — "ROXIMATE LOCATION EXISTING ORaNfla , D . \ 2 • \ a MANAGED TURF I, B �\ ,� v. ` - TMP 76-52L r Total 0.30 acres I ���;�� •� IMPERVIOUS \ . Total 0.36 acres 11 • • sil• 40 0 40 80 120 L - - Scale: 1 "=40' • 1/ Roa DA Sit DA 3L Point of Analysis 1 Point of Analysis 2 Subcat Reach on. It Drainage Diagram for PreDevelopment Prepared by Shimp Engineering, Printed 6/18/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC PreDevelopment Type 1124-hr 1 yr, 24 hr Rainfall=3.05" Prepared by Shimp Engineering Printed 6/18/2018 HydroCAD®9.10 sin 07054 ©2011 HydroCAD Software Solutions LLC Page 2 Summary for Subcatchment 1 S: Road DA Runoff = 0.40 cfs @ 11.95 hrs, Volume= 0.021 af, Depth> 2.60" 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=3.05" Area (sf) CN Description 177 61 >75% Grass cover, Good, HSG B 3,963 98 4,140 96 Weighted Average 177 4.28% Pervious Area 3,963 95.72% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2S: Site DA Runoff = 1.19 cfs @ 11.98 hrs, Volume= 0.057 af, Depth> 1.22" 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=3.05" Area (sf) CN Description 12,923 61 >75% Grass cover, Good, HSG B 11,610 98 24,533 79 Weighted Average 12,923 52.68% Pervious Area 11,610 47.32% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.5 Direct Entry, Summary for Link 3L: Point of Analysis 1 Inflow Area = 0.095 ac, 95.72% Impervious, Inflow Depth > 2.60" for 1 yr, 24 hr event Inflow = 0.40 cfs @ 11.95 hrs, Volume= 0.021 af Primary = 0.40 cfs @ 11.95 hrs, Volume= 0.021 af, Atten= 0%, Lag= 0.0 min Primary outflow= Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs PreDevelopment Type 1124-hr 1 yr, 24 hr Rainfall=3.05" Prepared by Shimp Engineering Printed 6/18/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 3 Summary for Link 4L: Point of Analysis 2 Inflow Area= 0.563 ac, 47.32% Impervious, Inflow Depth > 1.22" for 1 yr, 24 hr event Inflow = 1.19 cfs @ 11.98 hrs, Volume= 0.057 af Primary = 1.19 cfs @ 11.98 hrs, Volume= 0.057 af, Atten= 0%, Lag= 0.0 min Primary outflow= Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs PreDevelopment Type 1124-hr 10 yr, 24 hr Rainfall=5.58" Prepared by Shimp Engineering Printed 6/18/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 4 Summary for Subcatchment 1S: Road DA Runoff = 0.75 cfs @ 11.95 hrs, Volume= 0.040 af, Depth> 5.11" 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=5.58" Area (sf) CN Description 177 61 >75% Grass cover, Good, HSG B 3,963 98 4,140 96 Weighted Average 177 4.28% Pervious Area 3,963 95.72% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2S: Site DA Runoff = 3.15 cfs @ 11.98 hrs, Volume= 0.155 af, Depth> 3.30" 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=5.58" Area (sf) CN Description 12,923 61 >75% Grass cover, Good, HSG B 11,610 98 24,533 79 Weighted Average 12,923 52.68% Pervious Area 11,610 47.32% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.5 Direct Entry, Summary for Link 3L: Point of Analysis 1 Inflow Area= 0.095 ac, 95.72% Impervious, Inflow Depth > 5.11" for 10 yr, 24 hr event Inflow = 0.75 cfs @ 11.95 hrs, Volume= 0.040 af Primary = 0.75 cfs @ 11.95 hrs, Volume= 0.040 af, Atten= 0%, Lag= 0.0 min Primary outflow= Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs PreDevelopment Type 1124-hr 10 yr, 24 hr Rainfall=5.58" Prepared by Shimp Engineering Printed 6/18/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 5 Summary for Link 4L: Point of Analysis 2 Inflow Area= 0.563 ac, 47.32% Impervious, Inflow Depth > 3.30" for 10 yr, 24 hr event Inflow = 3.15 cfs @ 11.98 hrs, Volume= 0.155 of Primary = 3.15 cfs @ 11.98 hrs, Volume= 0.155 af, Atten= 0%, Lag= 0.0 min Primary outflow= Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Post-Development Stormwater Management Calculations Post-Development SWM Map Post-Development HydroCAD Analysis ,, __ _, _.._ _ 5c4� Post Development __ / _ �" I--`-, -.... ----------------------- - S WtV Map 1 `\ • I FSITE D i -_ ' _. l Oak Hill Convenience : 1 . ' •A 1 l 1 �``- _ �-•4* - �•�•kv1•j�i►tillk..• tee". �`.•�1W1��i`i►1�=1 111 .►Q ,'� .._ > > • .1111• ►•'111.1 •1.111•.11.,1 _ , Store 1.1�♦1••• 1111 S1!• �► 1.1111e'^ 1 i / _ I�•111.1111111.11,�11���, ���'��1 3 S •1 i�111.1j11.111111111E i�1t� .n• �,,� W , OFFSITE DA SHOWN ' •♦�♦•••111••111�t�•1• � ., ► � w • / 4.*♦1♦1...1•.♦�.1•♦$4-01 \. W i NEXT PAGE ,F /' 7 410 .1111.1•�•,•••11�••1•�•�1 /11.1.- ii\\` i /ø:fDETENTION DA 111 ,, . FFS.,.� , -- 7 ' / d% ;i .♦♦♦♦♦♦111.11.•••....41....�, •d -- '' _ __ -i , / •", .4..1•♦•••••1.1•1•♦�*.••••• , . .... /�_, TMP 76-52P j1 •11••• •♦1.•.`� ••♦••, •. - ,�--1--_--/ i_7 - `-i,_ `i11••♦♦••1••♦•••/\0•••4 _ �` u�1•11��1•�1.1•1•I•�1• \1•j►• �►' �'' � � —r�/-r� ,. -„ ; �-- , ,p1• "A-.4 1•4 •.,A.....� $1,, * / / / ,J ,t� [NOT SHOWN] Time of Concentration: ,)•1•� '►.�`� e�•��•:•�"�♦ �•t►. i'-� ► / / ;,_ N. 5 minutes each DA ` �,-•.- -.e i �s�`���V.•*•1♦••0y1, f, ; i 4 7 \\ -a I''`.,, f .iI,- Alfr:�:jt /fr4'A;?/*1:��.1�Ai t * // // , -' / / i;-^`` �.r`�\ ' �..�..�..- Limits of Disturbance: .s. 1�•1�870,1•� �•1e1 , / I 0.66 acres '''- __°- -e..'* it,"..00'..•ei 14.q/ '// , / ,' /7 �"/ . `" y,1 ■ ■ ■ ■ Soil Divide -- �- ' Ili: , / < / , i / ��, . Note: Offsite drains a ores _, __ T -� �� ;/ , / /, - / used for detention pipe sizing io - g� _ONEl�- l- '�✓ ' �� ,i /-_,__ ' � / Icalculations only. Areas within ti _ 1 / / /�" / �,.,, limits of disturbance used for -- / / , ➢ stormwater quality and quantity -` ------ / / i !` �, s�_:,' analysis. -_ �/ / -7 ; '( ` i `-_ _-' r� 27D 2 —�_ ^ __ i -- \ si HSG B iSG B OPEN SPACE „, ,__ \ .s\ , Total 0.00 acres }I 'PRO7QMA1p IOCAnON EJOS""G oRfl 2 D v- MANAGED TURF Total 0.17 acres "//Y. V/ _.` ` 4�` TMP 76-52L • _'''`�'PGA--2_ I IMPERVIOUS �J `,�1`++e, • Total 0.49 acres ,3\tt't z.,,_ v • 40 0 40 80 120 , . . . . . . . . . Scale: 1 "=40' Post Development SWV Va3 2 Oak Hi ConStorevenience / N j ,, l _ 1 \ \ N N / N / , i - I� -----------------_____- ' /` EW 75'ACCESS / / / \ •FFSITE D• \ ` - 'EASEMENT / 12• __ _ 14111.1jerktrP÷lf"-1P-e— / — / ' / .♦♦..♦♦♦.,`�w�� ♦.1, T ... / / ♦♦. ..♦.♦��j�4►♦441►� 11.4�� � ►j ��� �' `�. �� TENON D• �•., j�1 1�� ►�/ / ` .... 18,347 SF .`:/.�O.�.....•.. E r • "..' .............%,.. ....4.4 4,...........4....4.4...4...... / i tf --..s*- *A 4.....t4.....4. ,, , , _ 14.....v..v................ i ,t,/ ./..44...........4.444....1 • / 7/ 4•:•: :•• b***1\t.•:•:tf . / ,/ 7 1 ........ ..... ...,+ .,.:,:...,4 . ,, ,#.•......•....4%,....tv.....4,.. / /. .... ................*.. 4 / / b♦V1 .4�! � / •! �� 0•4"i / /w / , 40 0 40 80 120 iiiimmi ■ ■ ommimm ■ ■■■■■■■ Scale: 1 "=40' 0 Offsite Dete tion DA (Not in Energ Balance) 2S 1 S 5S Site etention DA Roa DA Cre: Only DA 7P Detention X\ 6L 4L Point of Analysis 1 Point of Analysis 2 (Subca) Reach 'one 11111 Drainage Diagram for PostDevelopment W.Offsite Area Prepared by Shimp Engineering, Printed 12/7/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC PostDevelopment W. Offsite Area Type 1124-hr 1 yr, 24 hr Rainfall=3.05" Prepared by Shimp Engineering Printed 12/7/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 2 Summary for Subcatchment 1 S: Road DA Runoff = 0.32 cfs @ 11.95 hrs, Volume= 0.016 af, Depth> 2.12" 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=3.05" Area (sf) CN Description 770 61 >75% Grass cover, Good, HSG B 3,076 98 3,846 91 Weighted Average 770 20.02% Pervious Area 3,076 79.98% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2S: Site Detention DA Runoff = 1.81 cfs @ 11.95 hrs, Volume= 0.095 af, Depth> 2.71" 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=3.05" Area (sf) CN Description 17,988 98 359 61 >75% Grass cover, Good, HSG B 18,347 97 Weighted Average 359 1.96% Pervious Area 17,988 98.04% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 5S: Creek Only DA Runoff = 0.10 cfs @ 11.98 hrs, Volume= 0.006 af, Depth> 0.45" 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=3.05" Area (sf) CN Description 6,208 61 >75% Grass cover, Good, HSG B 272 98 6,480 63 Weighted Average 6,208 95.80% Pervious Area 272 4.20% Impervious Area PostDevelopment W. Offsite Area Type II 24-hr 1 yr, 24 hr Rainfall=3.05" Prepared by Shimp Engineering Printed 12/7/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 3 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 7S: Offsite Detention DA (Not in Energy Balance) Runoff = 0.52 cfs @ 11.96 hrs, Volume= 0.024 af, Depth> 1.56" 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=3.05" Area (sf) CN Description ' 4,980 98 3,140 61 >75% Grass cover, Good, HSG B 8,120 84 Weighted Average 3,140 38.67% Pervious Area 4,980 61.33% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Pond 7P: Detention Pipe Inflow Area = 0.608 ac, 86.78% Impervious, Inflow Depth > 2.35" for 1 yr, 24 hr event Inflow = 2.33 cfs @ 11.95 hrs, Volume= 0.119 af Outflow = 0.71 cfs @ 12.09 hrs, Volume= 0.119 af, Atten= 69%, Lag= 8.0 min Primary = 0.71 cfs @ 12.09 hrs, Volume= 0.119 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 472.03' @ 12.09 hrs Surf.Area= 0.012 ac Storage= 0.031 af Plug-Flow detention time= 15.3 min calculated for 0.119 af (100% of inflow) Center-of-Mass det. time= 13.9 min ( 789.3 - 775.4 ) Volume Invert Avail.Storage Storage Description #1 469.00' 0.050 af 60.0" D x 110.0'L Pipe Storage Device Routing Invert Outlet Devices #1 Primary 469.00' 15.0" Round Culvert L= 20.0' Ke= 0.600 Inlet/Outlet Invert= 469.00'/469.00' S= 0.0000 '/' Cc= 0.900 n= 0.010 #2 Device 1 469.00' 4.0"Vert. Orifice/Grate C= 0.600 #3 Device 1 472.05' 10.0"Vert. Orifice/Grate C= 0.600 #4 Primary 473.62' 48.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads PostDevelopment W. Offsite Area Type 1124-hr 1 yr, 24 hr Rainfall=3.05" Prepared by Shimp Engineering Printed 12/7/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 4 Primary OutFlow Max=0.71 cfs @ 12.09 hrs HW=472.02' (Free Discharge) —1=Culvert (Passes 0.71 cfs of 8.57 cfs potential flow) t-2=Orifice/Grate (Orifice Controls 0.71 cfs @ 8.13 fps) 3=Orifice/Grate ( Controls 0.00 cfs) —4=Orifice/Grate ( Controls 0.00 cfs) Summary for Link 4L: Point of Analysis 2 Inflow Area= 0.756 ac, 70.54% Impervious, Inflow Depth > 1.98" for 1 yr, 24 hr event Inflow = 0.78 cfs @ 12.02 hrs, Volume= 0.125 of Primary = 0.78 cfs @ 12.02 hrs, Volume= 0.125 af, Atten= 0%, Lag= 0.0 min Primary outflow= Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Link 6L: Point of Analysis 1 Inflow Area= 0.088 ac, 79.98% Impervious, Inflow Depth > 2.12" for 1 yr, 24 hr event Inflow = 0.32 cfs @ 11.95 hrs, Volume= 0.016 af Primary = 0.32 cfs @ 11.95 hrs, Volume= 0.016 af, Atten= 0%, Lag= 0.0 min Primary outflow= Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Oak Hill Convenience Store Energy Balance Equation 24 Hr 1 year Storm: n `•developed- I.F. Qpre-developed RVPre-Developed) Redeveloped Qdeveloped5- Qforested RVforested) Redeveloped Qpre-developed = 1.19 RVpre-Developed = 0.057 MaxQdeveloped = 0.61 cfs` RVDeveloped = 0.1 Qdeveloped = [0.26 cfs ( `Site Detention RV+ Creek Only RV= 0.095+0.006 =0.1 POA 2 Outflow-Offsite Detention Outflow=0.78-0.52 = 0.26 PostDevelopment W. Offsite Area Type 1124-hr 10 yr, 24 hr Rainfall=5.58" Prepared by Shimp Engineering Printed 12/7/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 5 Summary for Subcatchment 1 S: Road DA Runoff = 0.66 cfs @ 11.95 hrs, Volume= 0.033 af, Depth> 4.54" 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=5.58" Area (sf) CN Description 770 61 >75% Grass cover, Good, HSG B 3,076 98 3,846 91 Weighted Average 770 20.02% Pervious Area 3,076 79.98% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2S: Site Detention DA Runoff = 3.37 cfs @ 11.95 hrs, Volume= 0.183 af, Depth> 5.22" 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=5.58" Area (sf) CN Description 17,988 98 359 61 >75% Grass cover, Good, HSG B 18,347 97 Weighted Average 359 1.96% Pervious Area 17,988 98.04% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 5S: Creek Only DA Runoff = 0.50 cfs @ 11.96 hrs, Volume= 0.023 af, Depth> 1.89" 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=5.58" Area (sf) CN Description 6,208 61 >75% Grass cover, Good, HSG B 272 98 6,480 63 Weighted Average 6,208 95.80% Pervious Area 272 4.20% Impervious Area 1 IPostDevelopment W. Offsite Area Type 1124-hr 10 yr, 24 hr Rainfall=5.58" Prepared by Shimp Engineering Printed 12/7/2018 I HydroCADO 9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 6 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 7S: Offsite Detention DA (Not in Energy Balance) Runoff = 1.23 cfs @ 11.95 hrs, Volume= 0.059 af, Depth> 3.80" 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=5.58" Area (sf) CN Description * 4,980 98 3,140 61 >75% Grass cover, Good, HSG B 8,120 84 Weighted Average 3,140 38.67% Pervious Area 4,980 61.33% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Pond 7P: Detention Pipe Inflow Area= 0.608 ac, 86.78% Impervious, Inflow Depth > 4.79" for 10 yr, 24 hr event Inflow = 4.60 cfs @ 11.95 hrs, Volume= 0.242 af Outflow = 3.70 cfs @ 12.01 hrs, Volume= 0.242 af, Atten= 20%, Lag= 3.3 min Primary = 3.70 cfs @ 12.01 hrs, Volume= 0.242 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 473.61' @ 12.01 hrs Surf.Area= 0.007 ac Storage= 0.048 af Plug-Flow detention time= 13.1 min calculated for 0.242 of (100% of inflow) Center-of-Mass det. time= 12.1 min ( 773.4 - 761.3 ) Volume Invert Avail.Storage Storage Description #1 469.00' 0.050 af 60.0" D x 110.0'L Pipe Storage Device Routing Invert Outlet Devices #1 Primary 469.00' 15.0" Round Culvert L= 20.0' Ke= 0.600 Inlet/Outlet Invert= 469.00'/469.00' S= 0.0000 '/' Cc= 0.900 n= 0.010 #2 Device 1 469.00' 4.0"Veil. Orifice/Grate C= 0.600 #3 Device 1 472.05' 10.0"Vert. Orifice/Grate C= 0.600 #4 Primary 473.62' 48.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads I IPostDevelopment W. Offsite Area Type 1124-hr 10 yr, 24 hr Rainfall=5.58" Prepared by Shimp Engineering Printed 12/7/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 7 Erimary OutFlow Max=3.65 cfs @ 12.01 hrs HW=473.58' (Free Discharge) —1=Culvert (Passes 3.65 cfs of 11.01 cfs potential flow) - 2=Orifice/Grate (Orifice Controls 0.88 cfs @ 10.11 fps) 3=Orifice/Grate (Orifice Controls 2.77 cfs @ 5.07 fps) —4=Orifice/Grate ( Controls 0.00 cfs) Summary for Link 4L: Point of Analysis 2 Inflow Area= 0.756 ac, 70.54% Impervious, Inflow Depth > 4.21" for 10 yr, 24 hr event Inflow = 4.15 cfs @ 12.00 hrs, Volume= 0.265 af Primary = 4.15 cfs @ 12.00 hrs, Volume= 0.265 af, Atten= 0%, Lag= 0.0 min Primary outflow= Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Link 6L: Point of Analysis 1 Inflow Area= 0.088 ac, 79.98% Impervious, Inflow Depth > 4.54" for 10 yr, 24 hr event Inflow = 0.66 cfs @ 11.95 hrs, Volume= 0.033 af Primary = 0.66 cfs @ 11.95 hrs, Volume= 0.033 af, Atten= 0%, Lag= 0.0 min Primary outflow= Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs PostDevelopment W. Offsite Area Type 1124-hr 100 yr, 24 hr Rainfall=9.16" Prepared by Shimp Engineering Printed 12/7/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 8 Summary for Subcatchment 1 S: Road DA Runoff = 1.13 cfs @ 11.95 hrs, Volume= 0.059 af, Depth> 8.07" 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=9.16" Area (sf) CN Description 770 61 >75% Grass cover, Good, HSG B 3,076 98 3,846 91 Weighted Average 770 20.02% Pervious Area 3,076 79.98% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 2S: Site Detention DA Runoff = 5.56 cfs @ 11.95 hrs, Volume= 0.309 af, Depth> 8.79" 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=9.16" Area (sf) CN Description 17,988 98 359 61 >75% Grass cover, Good, HSG B 18,347 97 Weighted Average 359 1.96% Pervious Area 17,988 98.04% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 5S: Creek Only DA Runoff = 1.23 cfs @ 11.96 hrs, Volume= 0.057 af, Depth> 4.60" 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=9.16" Area (sf) CN Description 6,208 61 >75% Grass cover, Good, HSG B 272 98 6,480 63 Weighted Average 6,208 95.80% Pervious Area 272 4.20% Impervious Area PostDevelopment W. Offsite Area Type 1124-hr 100 yr, 24 hr Rainfall=9.16" Prepared by Shimp Engineering Printed 12/7/2018 HydroCADO 9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 9 Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Subcatchment 7S: Offsite Detention DA (Not in Energy Balance) Runoff = 2.25 cfs @ 11.95 hrs, Volume= 0.112 af, Depth> 7.21" 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=9.16" Area (sf) CN Description 4,980 98 --- 3,140 61 >75% Grass cover, Good, HSG B 8,120 84 Weighted Average 3,140 38.67% Pervious Area 4,980 61.33% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.0 Direct Entry, Summary for Pond 7P: Detention Pipe Inflow Area = 0.608 ac, 86.78% Impervious, Inflow Depth > 8.31" for 100 yr, 24 hr event Inflow = 7.81 cfs @ 11.95 hrs, Volume= 0.421 af Outflow = 8.00 cfs @ 11.95 hrs, Volume= 0.420 af, Atten= 0%, Lag= 0.1 min Primary = 8.00 cfs @ 11.95 hrs, Volume= 0.420 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 473.83' @ 11.95 hrs Surf.Area= 0.005 ac Storage= 0.049 af Plug-Flow detention time= 11.5 min calculated for 0.419 af (100% of inflow) Center-of-Mass det. time= 10.6 min ( 761.9 - 751.3 ) Volume Invert Avail.Storage Storage Description #1 469.00' 0.050 af 60.0" D x 110.0'L Pipe Storage Device Routing Invert Outlet Devices #1 Primary 469.00' 15.0" Round Culvert L= 20.0' Ke= 0.600 Inlet/Outlet Invert= 469.00'/469.00' S= 0.0000 '/' Cc= 0.900 n= 0.010 #2 Device 1 469.00' 4.0" Vert. Orifice/Grate C= 0.600 #3 Device 1 472.05' 10.0" Vert. Orifice/Grate C= 0.600 #4 Primary 473.62' 48.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads PostDevelopment W. Offsite Area Type 1124-hr 100 yr, 24 hr Rainfall=9.16" Prepared by Shimp Engineering Printed 12/7/2018 HydroCAD®9.10 sin 07054 ©2011 HydroCAD Software Solutions LLC Page 10 Primary OutFlow Max=7.89 cfs @ 11.95 hrs HW=473.83' (Free Discharge) —1=Culvert (Passes 3.97 cfs of 11.36 cfs potential flow) I2=Orifice/Grate (Orifice Controls 0.91 cfs @ 10.40 fps) 3=Orifice/Grate (Orifice Controls 3.06 cfs @ 5.62 fps) —4=Orifice/Grate (Weir Controls 3.92 cfs @ 1.49 fps) Summary for Link 4L: Point of Analysis 2 Inflow Area= 0.756 ac, 70.54% Impervious, Inflow Depth > 7.57" for 100 yr, 24 hr event Inflow = 9.23 cfs @ 11.95 hrs, Volume= 0.477 af Primary = 9.23 cfs @ 11.95 hrs, Volume= 0.477 af, Atten= 0%, Lag= 0.0 min Primary outflow= Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Summary for Link 6L: Point of Analysis 1 Inflow Area= 0.088 ac, 79.98% Impervious, Inflow Depth > 8.07" for 100 yr, 24 hr event Inflow = 1.13 cfs @ 11.95 hrs, Volume= 0.059 of Primary = 1.13 cfs @ 11.95 hrs, Volume= 0.059 af, Atten= 0%, Lag= 0.0 min Primary outflow= Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Time of Concentrations Calculations Pre-Development Time of Concentration Calculations Post-Development Time of Concentration Calculations Nomog raphs Oak Hill Convenience Store Pre-Development Time of Concentration Calculations Road DA 5 min Site DA (Red) 100 ft overland flow-impery 1.6% slope 0.90 C-value 5.0 min. Seelye Chart 199 ft s. c.flow-turf 11.0% slope 2.2 fps velocity 1.5 min. NEH Figure 15-4 6.5 min. Oak Hill Convenience Store Post-Development Time of Concentration Calculations Road DA TOC 5.0 min. Detention DA TOC 5.0 min. Creek Only DA TOC 5.0 min. °c LENGTH I" L" OF STRIP IN FEET el I I I I I 1 I 11 1 1 I I I ----, C7 I — ry w �' — N w (r CA cD O 0 0 O 0 0 0 0 0 0 000 / S 0 p c D I o"„ on o00 00o CAD 0 N to if) NN f0 VN1N (ADN � �(D a n O �' Crn " CI�ARACTE' OF GROUND 13 trl a T C"VALLi` n+ / {' V' J Oc o C VA ., r / 12 � D / m 4Z 11 00 / 5- r c PIVOT LINE O \ N - 0' N -O O O O O :34..................t KI I 11II11 I I 1 I 1 rl PERCEN OPE b \ AD u — \— N N W w cn dl -1 aD cD O CA 0 UI O UI '-' ` I 1 I 1 I I I I I I I 1 I 1I I 1 1 I 1 I I I I Lill HIM ' INLET CONCENTRATION TIME IN. MINUTES 1.00 0.90 0.80 0.70 0.60 0.60 __ 71/All I II 0.40 1 .=rAlE111I 0.30 _-M11`' - i' /! II 0.20 �I ,- /_:I,a iflI ■ r-. 0.10 L.. ,t, 141111_I y 0.08 -0.09 4 �,.��._' .�.�■■u�� v Cr°����i ����1u�= 0.07 .t4 M�I�II,a M�U•lU�� :y -- a' — 11111�� 0 0.06 b ,b' i AMININIIIIMMIMMMENIMMI 0.04 1 'e� A I h.A' 4) b' 1111 1 0.03 ,° �° / ° %P 1111 - 0.02 °� �� i z,4: I'I'-■ --- IM J,te - I'Ii 0.01 "AllrAYISz' so ilMini MN ...... EMU III 0.005 ' -, cl o w ca ti ao 00 co d. ua m ti co w o w o 0 0 0 0 0 o coo. _, .-, csi 2 Velocity(ft/s) Stormwater Quality Calculations VRRM Redevelopment Spreadsheet Project Names Oak Hill Convenience Store CI FAR ALL __ -data input tells 6/18/2013 constant values ..___ Linear Development Project? N0... calculation cells I I __ Site Information - --- --- --` Post Development Project(Treatment Volume and Loads) T Enter Total Disturbed Area(acres( � '}u',.0::,,,F, Check: i l MP Degn Specifications List:2013. Draft5tds&Sp Maximum reduction required:I 0 I _ Linear p o/ectt No _ r The sites net increase in impervious is- pemous cover(acres) 0.1323002]5_I_ Land cover areas feted correctly? ✓ Post-Development TP Load Reduction for Site(Ib/yr) 0.3I j Total disturbed area entered? V Pre-ReOevelopment Land Cover(acres) L. A 401b ill Soils C Soils DSails Totals Forest/Open Space(acres) undisturbed, 4 ', 0'� orotetted toresr/op n space or reforested land Managed Turf(acres)-disturbed,graded for 0.30 Yards or other turf to moved/managed b Impervious Cover tares) 0.36 I 0.66 1-___._.._.____ Post-Development Land Cover(acres) _-_..__.__._____._.__..._._ A Soils B Soils C Soils D Soils Total Forest/Open Space(acres(.-undisturbed, 0.00 protected forest/open space or reforested land Managed Turf(acres)--disturbed,eroded for 0.17 r_.._.._ yards or other turf to be mowed/managed 0.17 Impervious Cover(arm) ..___...._.. .._ ...._..__....._.__. 0.49 0.49 Area Check OK. OK. OK. OK. 0,66 -- - -Constants Runoff Coefficients(Rv) Annual Rain/all(inches) 43 ASoils 61oib CSab DSails arget Rainfall Event(Inches) 1.00 _ Forest/Open Space 0.02 0.03 0.04 0.05 'Total Phosphorus(TP)MC(mg/L) 0.26 Managed Turf 0.15 0.20 0.22 0.25 Total Nitrogen(TN)EMCing/LI 1.06 Impetuous Cover 0.95 0.95 0.95 0.95 Target TP Load(lb/acre/yr) 0.41 Pi(unitless correction lector) 090 LAND COVER SUMMARY--PRE-REDEVELOPMENT LAND COVER SUMMARY--POST DEVELOPMEIIT Land Cover Summary-Pre Land Cover Summary-Post(Final) Land Cover Summary-Post Land(gaWlFgnatvyPpFt PreaeOwelo pmnt caned Adjusted' Post ReWv.a New Impervious --` post-ReDevelapment Paa4tevelgman New bRPearleva Forest/Open swell ..__- Forest/Open SpazeCover(xres) 0.00 0.00 Forest/Open en Space ,sue: Cover noes) 0'� cover(acres) 0� 8n:. Weighted Ro(lorest) 0.00 0.00 Weighted Rv(forest) 0.00 - Weighted Rat/west) 0.00 j`' %Forest 0% 0% I %Forest 096 %Forest 0% Managed Turf Cover(acres) 0.30 0.17 Managed Turf Cover 0.17 Managed Turf Cover O17 " (acres) 4,. Weighted Rv(tur0 0.20 0.20 Weighted Rv(turf) 0.20 Weighted Ru Purl) 020 '?; %Managed Turf 46% 32% %Managed Turf 26% %Mnaged Turf 32% Impervious Cover(acres) 0.36 0.36 Impervious Cover(acres) 0.49 B.Ds.lr0 r"' .036 New lmpeMusO Cover 0.13 Cover(acres) (acres) 0.vllmpeMous) 0.95 0 95 Rv(ImpeMaus) 0.95 M(imperviout 095 1 Rv(�m' pus) 095 %Impervious 54% 68% XlmpeMaus 74% %ImpeM us 68% Total Sin Area(acres) 0.66 0.53 Final Site Area(acres) 0.66 Total loollev mB;Area 0.53 S ° " _ a'w'S '" `". ... Site Re 0.61 0.71 Anal Port Oev Site Pr 0.76 ReDw SiteM OTl ' Treatment Volume and Nutrient Load Treatment Volume and Nutrient Load pit Reoevdopment Treatment Volume Final Post-0 t ewlopmen PostReDevelopment Post-Development (aarc-hl 0.0333 0.0311 Treatment Volume 0.0416 Treatment Volume 00311 Treatment Vdume 0.0105 Iaae-itl (a�-WI ._ (anal Pre-Refrevelapment Treatment Volume Final PostDevelopment P55tA (0000elopmen Pat-0eaebpmen (cubit Feet) 1,451 1.355 Treatment Volume 1,811 Treatment Volume 1,355 Treatment Volume(cubic 456 (cubic feet) (cubic feet) (eery Pre-Renevelopment TP Load Final Post- -Post-eaO.sebpnmt post-Development TP Ob/rrl 0.91 0.85 Development TP Load 1.14 toad(TP) 0.85 loadllb/noel 029 Ilb/rr) (Ib/5r) Pr�aeone opmmtiP Load perave w Fora post-oreppmmttrPoo-Reoevebpment"P (b/acre/vn Load pe.acre k03 Load per acre 262 P Ib/aere/wt r Ilb/acre/yrl Baseline TP Load Ilb/rrl toMa.Reduction Re3Wrn (On taAoePPappl'ed pre-redevelopmentr I�a pennons o% la. on 0.22 prow Pre- S la Proposed.rc✓m us pnvio cover) ReMwmpment Lead) 1 'Admted Land CoverSummory TP Load Reduction TP Load Reduction Pre RCDevelopment land cover minus pervious land cover lfuresVopen space or Required For 0.09 Required for New 0.23 managed for)/acreage Proposed for new impervious cover Redeveloped Areaquire (lb/nor) Impervious Area Ilb/nor) Adjusted told ucreooe it consistent with post-Re0evelopment acreage(minus ocreag4 ' of neve impervious(aver( ' Column,shows Wad reduction requnementfor newimpenrous cover(based on new development loodllmit,0411 cre/yeprl i I• Post-Development Requirement for Site Area TP Load Reduction Required(Ib/ter) 0.32 Site Results(Water Quality Compliance) Area Checkst 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 0.00 0.00 I OK. I_ IMPERVIOUS COVER(ac) 0.00 0.00 0.00 0.00 0.00 I OK. -I 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 I OK. I AREA CHECK OK. II OK. II OK. II OK. OK. Site Treatment Volume(ft3) 1,811 Runoff Reduction Volume and TP By Drainage Area D.A.A D.A.B O.A.C 1 D.A.D D.A.E TOTAL RUNOFF REDUCTION VOLUME ACHIEVED(k') 0 0 0 0 0 0 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)I 0.00 0,00 0.00 0.00 _ 0.00 L 0.00 NITROGEN LOAD REDUCTION ACHIEVED(Ib/yr)I 0.00 0.00 0.00 I 0.00 I®i 0.00 Total Phosphorus FINAL POST-DEVELOPMENT TP LOAD(Ib/yr)® TP LOAD REDUCTION REQUIRED(Ib/yr)MIME TP LOAD REDUCTION ACHIEVED(Ib/yr) 0.00 TP LOAD REMAINING(Ib/yr): 1.14 REMAINING TP LOAD REDUCTION REQUIRED(Ib/yr): 0.32 Total Nitrogen(For Information Purposes) POST-DEVELOPMENT LOAD(Ib/yr)I 8.14 NITROGEN LOAD REDUCTION ACHIEVED(Ib/yr) 0.00 REMAINING POST-DEVELOPMENT NITROGEN LOAD(16/yr) 8.14 Virginia Runoff Reduction Method Worksheet Site Summary Total Rainfall(in): 43 Total Disturbed Acreage: 0.66 Site Land Cover Summary Pre-ReDevelopment Land Cover(acres) A soils B Soils C Soils D Soils Totals %of Total Forest/Open(acres) 0.00 0.00 0.00 0.00 0.00 0 Managed Turf(acres) 0.00 0.30 0.00 0.00 0.30 46 Impervious Cover(acres) 0.00 0.36 0.00 0.00 0.36 54 0.66 100 Post-ReDevelopment Land Cover(acres) A soils B Soils C Soils D Soils Totals %of Total Forest/Open(acres) 0.00 0.00 0.00 0.00 0.00 0 Managed Turf(acres) 0.00 0.17 0.00 0.00 0.17 26 Impervious Cover(acres) 0.00 0.49 0.00 0.00 0.49 74 0.66 100 Site Tv and Land Cover Nutrient Loads Pre- Final Post-Development Post- Final Post-Development Post-ReDevelopment TP (Post-ReDevelopment Post- Adjusted Pre- ReDevelopment ( pment ReDevelopment Development ReDevelopment TP Load per acre TP Load per acre Load per acre &New Impervious) (New Impervious) (lb/acre/yr) (Ib/acre/yr) (lb/acre/yr) Site Rv 0.76 0.71 0.95 0.71 1.62 1.73 1.62 Treatment Volume(ft') 1,811 1,355 456 1,355 TP Load(lb/yr) 1.14 0.85 0.29 0.85 Total TP Load Reduction Required(Ib/yr) 0.32 0.09 0.23 Final Post-Development Load Pre- (Post-ReDevelopment&New Impervious) ReDevelopment TN Load(Ib/yr) 8.14 6.52 Site Compliance Summary Maximum%Reduction Required Below Pre-ReDevelopment Load 10% Total Runoff Volume Reduction(fts) 0 Total TP Load Reduction Achieved(lb/yr) 0.00 Total TN Load Reduction Achieved(Ib/yr) 0.00 Remaining Post Development TP Load (Ib/yr) 1.14 Remaining TP Load Reduction(lb/yr) 0.32 Required Summary Print Independent Reports Excerpt from NRCS Soils Report NOAA Precipitation Report Custom Soil Resource Report Soil Map 7173E0 717400 717420 717440 717460 717480 717500 38°0'19"N 38°0'19"N Country Green Rd i 1 li i E .41 N t I 2 444410... , • i- O 1 w Joao[dap wavy nal hgt wild„tl t hll@>oale 38'0 13 N 38°0'13"N 717380 717400 717420 717440 717460 717480 717500 3 3 Map :1:896 if printed on A portrait(S.S'x 11")sheet Meters N 0 10 20 40 60 m Feet /V0 0 40 80 160 240 Map projection:Web Mercator Corner coordinates:WG584 Edge tics:WM Zone 17N WG584 9 Custom Soil Resource Report MAP LEGEND MAP INFORMATION Area of Interest(AOI) 14 Spoil Area The soil surveys that comprise your AOI were mapped at n Area of Interest(AOI) Stony Spot 1:15,800. Soils Very Stony Spot Soil Map Unit Polygons Warning:Soil Map may not be valid at this scale. V Wet Spot Soil Map Unit Lines Enlargement of maps beyond the scale of mapping can cause GL Other • Soil Map Unit Points misunderstanding of the detail of mapping and accuracy of soil 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 �p Blowout Water Features scale. Streams and Canals 13 Borrow Pit Transportation Please rely on the bar scale on each map sheet for map Clay Spot Rails measurements. © Closed Depression rq/ Interstate Highways Gravel Pit Source of Map: Natural Resources Conservation Service ,r%o US Routes Web Soil Survey URL: Gravelly Spot Major Roads Coordinate System: Web Mercator(EPSG:3857) 0 Landfill Local Roads Maps from the Web Soil Survey are based on the Web Mercator A. Lava Flow Background projection,which preserves direction and shape but distorts distance and area.A projection that preserves area,such as the ,4 Marsh or swamp . Aerial Photography Albers equal-area conic projection,should be used if more n i Mine or Quarry accurate calculations of distance or area are required. Miscellaneous Water This product is generated from the USDA-NRCS certified data as 0 Perennial Water of the version date(s)listed below. Rock Outcrop Soil Survey Area: Albemarle County,Virginia + Saline Spot Survey Area Data: Version 11,Oct 11,2017 Sandy Spot Soil map units are labeled(as space allows)for map scales Severely Eroded Spot 1:50,000 or larger. Sinkhole Date(s)aerial images were photographed: Apr 22,2015—Mar t 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 27B Elioak loam,2 to 7 percent 0.6 18.9% slopes 27C Elioak loam,7 to 15 percent 0.1 4.4% slopes 27D Elioak loam, 15 to 25 percent 2.2 76.7% slopes Totals for Area of Interest 2.9 100.0% Map Unit Descriptions The map units delineated on the detailed soil maps in a soil survey represent the soils or miscellaneous areas in the survey area. The map unit descriptions, along with the maps, can be used to determine the composition and properties of a unit. A map unit delineation on a soil map represents an area dominated by one or more major kinds of soil or miscellaneous areas. A map unit is identified and named according to the taxonomic classification of the dominant soils. Within a taxonomic class there are precisely defined limits for the properties of the soils. On the landscape, however, the soils are natural phenomena, and they have the characteristic variability of all natural phenomena. Thus, the range of some observed properties may extend beyond the limits defined for a taxonomic class. Areas of soils of a single taxonomic class rarely, if ever, can be mapped without including areas of other taxonomic classes. Consequently, every map unit is made up of the soils or miscellaneous areas for which it is named and some minor components that belong to taxonomic classes other than those of the major soils. Most minor soils have properties similar to those of the dominant soil or soils in the map unit, and thus they do not affect use and management. These are called noncontrasting, or similar, components. They may or may not be mentioned in a particular map unit description. Other minor components, however, have properties and behavioral characteristics divergent enough to affect use or to require different management. These are called contrasting, or dissimilar, components. They generally are in small areas and could not be mapped separately because of the scale used. Some small areas of strongly contrasting soils or miscellaneous areas are identified by a special symbol on the maps. If included in the database for a given area, the contrasting minor components are identified in the map unit descriptions along with some characteristics of each.A few areas of minor components may not have been observed, and consequently they are not mentioned in the descriptions, especially where the pattern was so complex that it was impractical to make enough observations to identify all the soils and miscellaneous areas on the landscape. The presence of minor components in a map unit in no way diminishes the usefulness or accuracy of the data. The objective of mapping is not to delineate pure taxonomic classes but rather to separate the landscape into landforms or 11 Custom Soil Resource Report Albemarle County, Virginia 27B—Elioak loam, 2 to 7 percent slopes Map Unit Setting National map unit symbol. kb8y 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 Elioak and similar soils: 80 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Elioak Setting Landform: Hillslopes Landform position (two-dimensional): Summit Landform position (three-dimensional): Interfluve Down-slope shape: Convex Across-slope shape: Convex Parent material: Residuum weathered from mica schist Typical profile H1 - 0 to 8 inches: loam H2- 8 to 39 inches: silty clay H3-39 to 79 inches: silt loam Properties and qualities Slope: 2 to 7 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water(Ksat): Moderately high to high (0.20 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Moderate (about 6.6 inches) Interpretive groups Land capability classification(irrigated): None specified Land capability classification(nonirrigated): 2e Hydrologic Soil Group: B Hydric soil rating: No 13 Custom Soil Resource Report 27C—Elioak loam, 7 to 15 percent slopes Map Unit Setting National map unit symbol: kb8z Mean annual precipitation: 25 to 65 inches Mean annual air temperature: 54 to 59 degrees F Frost-free period: 195 to 231 days Farmland classification: Farmland of statewide importance Map Unit Composition Elioak and similar soils: 80 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Elioak Setting Landform: Hillslopes Landform position (two-dimensional): Summit Landform position (three-dimensional): Interfluve Down-slope shape: Convex Across-slope shape: Convex Parent material: Residuum weathered from mica schist Typical profile H1 -0 to 8 inches: loam H2-8 to 39 inches: silty clay H3-39 to 79 inches: silt loam Properties and qualities Slope: 7 to 15 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Runoff class: Medium Capacity of the most limiting layer to transmit water(Ksat): Moderately high to high (0.20 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Moderate (about 6.6 inches) Interpretive groups Land capability classification(irrigated): None specified Land capability classification(nonirrigated): 3e Hydrologic Soil Group: B Hydric soil rating: No 14 Custom Soil Resource Report 27D—Elioak loam, 15 to 25 percent slopes Map Unit Setting National map unit symbol: kb90 Mean annual precipitation: 25 to 65 inches Mean annual air temperature: 54 to 59 degrees F Frost-free period: 195 to 231 days Farmland classification: Farmland of statewide importance Map Unit Composition Elioak and similar soils: 80 percent Estimates are based on observations, descriptions, and transects of the mapunit. Description of Elioak Setting Landform: Hillslopes Landform position (two-dimensional): Summit Landform position (three-dimensional): Interfluve Down-slope shape: Convex Across-slope shape: Convex Parent material: Residuum weathered from mica schist Typical profile H1 -0 to 8 inches: loam H2-8 to 39 inches: silty clay H3-39 to 79 inches: silt loam Properties and qualities Slope: 15 to 25 percent Depth to restrictive feature: More than 80 inches Natural drainage class: Well drained Runoff class: High Capacity of the most limiting layer to transmit water(Ksat): Moderately high to high (0.20 to 1.98 in/hr) Depth to water table: More than 80 inches Frequency of flooding: None Frequency of ponding: None Available water storage in profile: Moderate (about 6.6 inches) Interpretive groups Land capability classification(irrigated): None specified Land capability classification(nonirrigated): 4e Hydrologic Soil Group: B Hydric soil rating: No 15 5/10/2018 Precipitation Frequency Data Server NOAA Atlas 14,Volume 2,Version 3 �" 0.' °aka Location name:Charlottesville,Virginia,USA* is p Latitude:38.0054°,Longitude:-78.5224° none A. a ,,. I Elevation:484.55 ft** i Gs>ncs�'- *source:ESRI Maps .,k M n "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 Duration Average recurrence interval(years) 1 2 5 10 25 50 100 200 500 1000 0.352 0.418 0.491 0.552 0.621 0.675 0.724 0.771 0.827 0.872 5-min (0.317-0.391) (0.377-0.465) (0.441-0.544) (0.495-0.611) (0.555-0.685) (0.601-0.744) (0.641-0.799) (0.679-0.851) (0.720-0.914) (0.752-0.967) 10-min 0.562 0.669 0.786 0.882 0.990 1.08 1.15 1.22 1.31 1.37 (0.506-0.625) (0.604-0.744) (0.707-0.871) (0.792-0.977) (0.885-1.09) (0.957-1.19) (1.02-1.27) (1.08-1.35) (1.14-1.45) (1.19-1.52) 0.703 0.841 0.994 1.12 1.25 1.36 1.46 1.54 1.65 1.72 15-min (0.632-0.781) (0.759-0.935) (0.894-1.10) (1.00-1.24) (1.12-1.39) (1.21-1.50) (1.29-1.60) (1.36-1.70) (1.43-1.82) (1.49-1.91) 0.963 1.16 1.41 1.62 1.86 2.05 2.23 2.40 2.62 2.79 30-min (0.867-1.07) (1.05-1.29) (1.27-1.57) (1.45-1.79) (1.66-2.05) (1.82-2.26) (1.97-2.46) (2.11-2.65) (2.28-2.90) (2.41-3.10) 1.20 1.46 1.81 2.11 2.47 2.78 3.07 3.37 3.76 4.07 60-min (1.08-1.34) (1.32-1.62) (1.63-2.01) (1.89-2.33) (2.21-2.73) (2.47-3.06) (2.72-3.38) (2.96-3.71) (3.27-4.16) (3.52-4.52) 2-hr 1.44 1.75 2.18 2.57 3.06 3.46 3.88 4.32 4.92 5.41 (1.27-1.65) (1.53-1.99) (1.92-2.49) (2.25-2.92) (2.66-3.47) (3.01-3.93) (3.35-4.39) (3.69-4.88) (4.16-5.56) (4.53-6.15) 3-hr 1.58 1.91 2.39 2.80 3.34 3.79 4.25 4.73 5.39 5.95 (1.38-1.82) (1.67-2.20) (2.09-2.75) (2.44-3.21) (2.90-3.82) (3.27-4.33) (3.64-4.85) (4.02-5.40) (4.52-6.15) (4.94-6.80) 6-hr 2.02 2.44 3.03 3.57 4.28 4.91 5.57 6.28 7.27 8.15 (1.79-2.29) (2.15-2.76) (2.66-3.42) (3.13-4.03) (3.73-4.83) (4.25-5.53) (4.77-6.27) (5.32-7.07) (6.08-8.20) (6.72-9.20) 12-hr 2.54 3.07 3.82 4.53 5.51 6.39 7.33 8.36 9.89 11.3 (2.25-2.92) (2.71-3.51) (3.36-4.37) (3.97-5.17) (4.79-6.27) (5.49-7.25) (6.23-8.31) (7.01-9.47) (8.13-11.2) (9.11-12.8) 24-hr 3.05 3.69 4.71 5.58 6.85 7.95 9.16 10.5 12.5 14.2 (2.74-3.42) (3.32-4.14) (4.22-5.28) (4.98-6.22) (6.08-7.62) (7.00-8.82) (8.00-10.1) (9.07-11.6) (10.6-13.8) (11.9-15.7) 2-day 3.59 4.36 5.54 6.52 7.93 9.12 10.4 11.8 13.9 15.6 (3.22-4.01) (3.91-4.87) (4.96-6.19) (5.82-7.26) (7.03-8.82) (8.02-10.1) (9.09-11.6) (10.2-13.1) (11.8-15.5) (13.2-17.4) 3-day 3.82 4.64 5.89 6.92 8.42 9.68 11.0 12.5 14.7 16.5 (3.47-4.23) (4.21-5.13) (5.34-6.52) (6.26-7.64) (7.57-9.29) (8.64-10.7) (9.77-12.2) (11.0-13.8) (12.7-16.2) (14.1-18.3) 4.06 4.92 6.24 7.33 8.91 10.2 11.7 13.2 15.5 17.4 4-day (3.73-4.45) (4.51-5.39) (5.72-6.85) (6.70-8.03) (8.10-9.75) (9.25-11.2) (10.5-12.8) (11.8-14.5) (13.6-17.0) (15.1-19.1) 4.71 5.67 7.09 8.26 9.93 11.3 12.8 14.4 16.8 18.7 7-day (4.34-5.13) (5.23-6.17) (6.52-7.72) (7.57-8.98) (9.06-10.8) (10.3-12.3) (11.5-13.9) (12.9-15.7) (14.8-18.3) (16.3-20.5) 10-day 5.34 6.41 7.92 9.14 10.9 12.3 13.8 15.3 17.6 19.4 (4.94-5.77) (5.94-6.92) (7.32-8.55) (8.43-9.86) (9.97-11.7) (11.2-13.2) (12.5-14.9) (13.8-16.6) (15.7-19.1) (17.2-21.1) 20-day 7.01 8.36 10.1 11.5 13.3 14.8 16.3 17.8 19.9 21.5 (6.58-7.50) (7.85-8.94) (9.47-10.8) (10.7-12.3) (12.4-14.2) (13.7-15.8) (15.1-17.4) (16.4-19.1) (18.2-21.4) (19.5-23.2) 30-day 8.61 10.2 12.1 13.5 15.3 16.7 18.1 19.5 21.2 22.6 (8.11-9.15) (9.61-10.8) (11.4-12.8) (12.7-14.3) (14.4-16.3) (15.7-17.8) (16.9-19.3) (18.1-20.7) (19.6-22.7) (20.8-24.2) 45-day 10.7 12.7 14.8 16.4 18.5 20.0 21.5 22.9 24.7 26.1 (10.2-11.4) (12.0-13.4) (14.0-15.7) (15.5-17.4) (17.4-19.6) (18.8-21.2) (20.2-22.8) (21.4-24.3) (23.0-26.3) (24.2-27.8) 60-day 12.6 14.8 17.1 18.8 21.0 22.6 24.2 25.6 27.5 28.8 (12.0-13.3) (14.1-15.6) (16.2-18.1) (17.8-19.8) (19.9-22.1) (21.3-23.8) (22.7-25.5) (24.1-27.1) (25.7-29.1) (26.9-30.6) 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=38.0054&Ion=-78.5224&data=depth&units=english&series=pds 1/4