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HomeMy WebLinkAboutWPO201800072 Calculations 2019-03-14 PROJECT MANAGEMENT c{* CIVIL ENGINEERING LAND PLANNING • March 14, 2019. rc' ` SAL rH •`h VSMP Plan Reviewer , Department of Community Development U JUST 401 McIntire Road M.SI Li..No.45183 Charlottesville, VA 22902474,6 :.. in rff. 2;s Regarding: St. Francis Ave SWM Calculation Packet Dear Reviewer, . Enclosed is the stormwater:calculation packet for St. Francis Ave: This project is a private road construction to serve four(4) new lots subdivided from the existing 15.89 acre parcel:: The disturbed area is 2.40 acres: :. . The proposed stormwater design meets the runoff requirements set forth in 9VAC25-870-66-B(3) and: 9VAC25-870-65 The energy balance equation was met using one(1) detention pond which outlets to an existing natural channel. This SWM facility releases runoff at rates are less:than the max imum allowable 1-yr and 10-yr flows dictated by the energy balance equation at the Point of Analysis. The remainder of the site runoff will exist.in sheetflow.condition. Since the existing downstream conditions are the same as'the pre-development, and since the:development will not:alter the current gentle slopes onsite, thus preserving sheetfiow conditions, we conclude that the downstream channel is not at risk from increased runoff from this. To determine nutrient treatment requirements, we entered the 2:40:acre area of disturbance, along with the future building area for each Of the four.(4) new lots, into the.VRRM spreadsheet. Additionally,the 4.00 acre forest area was:entered into the spreadsheet. The resulting nutrient total was-0.09:lbs of phosphorous. This property exceeds the:nutrient removal requirements and meets 9VAC25-870-65. Site Runoff Quantity Totals Storm Events and Associated Peak Runoff Rates .. Pre.Dev POA Post-Dev POA . 1-Year . 0.31 cfs 0.16 cfs 10-Year . . ..2.43 cfs 2.16 cfs . 100=Year 6.62 cfs 7.86 cfs . If you have any questions please do not hesitate to contact me at: Justin anshimp-engineerinq.com or by phone at 434-299-9843. t � Contents: Pre-Development Calculations: Pre-Dev Drainage Map Time of Concentration Calculations PreDev HydroCAD Report Energy Balance Equation Post-Dev Runoff Quantity Calculations: Post-Dev POA Drainage Map Post-Dev Ditch and Structure Drainage Map Post-Dev HydroCAD Report VDOT LD-229 Culvert Capacity VDOT LD-268 Ditch Capacity Post-Dev Runoff Quality Calculations: Post-Dev Land Cover Map VRRM New Development Spreadsheet Independent Reports:. Excerpt from NRCS Soils Report NOAA Precipitation Report t � Pre-Development Calculations: Pre-Dev Drainage Map Time of Concentration Calculations PreDev HydroCAD Report Energy Balance Equation ‘, \ ' A\ S T. F� A\ C S „ ,, , , . „ \�� \\\ \\\ i \\\ 1 \ \ PRE-DEV DRAINAGE MAP \ 1-4 ` \ 1 ,^ ` \ s. 1 t 11, \\\. \`\\ \\ \\\ \\\ \\\ \\ \ 1\ i `\\-�\ \\� It�ry\ . it • / ,• ', \\ a0 \ \ •\\ \ \ ',. �s. , �// / / \\ \\\I 1 / . \ \\ \'\ \ \\ \ /%' ��`� , / ' 1 \ • \ F --\\ / i/ 'II----___) 11 i„,- „.-- 1 •\\ '\ \\` \\\ \\ \ i�'`„ ```'� ') ) / \\\i \\--1 I -- ' I — �\ �. `mot \\`\`'`. // 1{ \� ‘.......... „,- ....-- „.-- -- \\ \\ • \\ .�% \ 1 1 �� \ —-620 — ———— \ N \1 �� ' -- J \ \ C \`\ \ 624 \ \ \ I I\ \ \ \ \ \ �/ ` / — ca // / '/ , 1 Cr, T. ,\ \ --/ _ �. ..,r, r �'' II //' /' / // -_.—� t\J T \ /_�, \ '' 1 / , / / - - ---- _ POA ( \i ci, ...-- --- ....4 . ) � ,\ , , i __,- I l` 1,,1 ,\I\\ i �1 ' ----- --��1 `\ '•I 289' S-c. raw 648i ' �' \\\`-P<, /) _ * �- T •� \\\\\\sL -J PREDEV DRAINAGE INFO • \\\ .N2 y� \ `•<`\ \ TO POA:_ ' 40 / / - _ ot /\\ `; ---\_,` ,A 2\ MANAGED?Vjr C \ c ,, --- t-'--- .I\ 't't \ WOODS, HGS B: 0.38 AC // / --- \--___ - - ,, „ '\\ IMPERVIOUS: 0.02 AC TOTAL AREA TO POA: 1.30 AC // ' Q) ' / \ — HYDROLOGIC DATA, POA i i 1 �`\ \ ''-644- i i \ \ / // /, \"‹-'.- \ 0 / �,� N ToC= 15.0 min , / 1 \ — s RVi_yR— 0.035 AC / I I '� = 0.31 cfs � ��----\ \ /' 1 s \� > Quo- = 2.43 cfs 1 i I \, Ii 1 ——_ Q100-YR= 6.62 cfs / f i-' I \ // ( I 1 I " _— I I 1 // / •i 1 N i i ' ^) '----- I 1 O1 ' `\ 1, N -- / / \- / I rn co \ i / N • / / // I i 0 I • \\`` \. /,^f j i • L —/ �/ , 1 • 1,\ \• \\\\ Jl %, r �'' / / 1 0) I , , 1 \ I , 0 I I ` I `. / , \ I I \\ I I\ 1 N — —-� _ a, i 1 \ -' / I I _`� 1 • 1 \\\ •-__� ,`I \ `` _ ---604 ------- \ - - ___ _----_- --') r ' 100 0 100 200 300 _ 600 - --, '\ L _ 1 Scale: 1"=100' . y v N m . 0 . c LENGTH " L" OF STRIP IN FEET o z N1 T T I r l l i I I l i I l l I I T i r �1 i I ___-'' r) n /1 O N O / N W N W . (r o -J W(D O O O C O 0 0 O O O O 00 O 0 D m b D N �' p c 0 NN a i. HQ ONO U)9. 0 13 --I HARACTER` OF I GROUND+ < 0 rri 1f C VALUE N /•lr - u 8 .1 m -0 C'VALUE ° D • / O i y a' D = 0 N � 0 / cPIVOT LINE (D v 1 c0 \ C '''A N — (r - O O O O 0 0 ui I . hi,' i I i IiiiiI rn PERCE \ SLOPE b co — N N (>J (A a) 1I m cD 0 (J'\ t 0 Ut 0 al I I I i I ' III 1 1 I Y A t i 1 I , i t I l t t i i I i i ► i l INLET CONCENTRATION TIME IN . MINUTE S Slope(ft/ft) 0 0 0 0 0 0 0 0000 0 0 0 0 0 000- a.lg • E. ���•o 0 0 0 8 8 08E8 0.2 Ibth II1 0.3 !!iil 0.4 11111WaSY° 47 IIIIIII1IIII •IIIIIIIIII1IllH ■■■lini 111111111111\.hea ■1■■■1111111111111MMINIMIN.■IIIII■■1■111111 O.b ■■■■111.. =M0� 41! ■■111111_�=.1•■�■■1■111111 • 0.6 ,,■•�illi1 b/fag, �����..a'y 1ull_____ •....u.luli 1 \■..�.-Rum a �im�a.■.o_ Pf. o�����mo••■..■u0.u. 0.7 NiV1 4/ mom.■■■■._ aria ���1.�..■■■■■■■■II �.. 1111' -ab �m..■...... ha omminemoommoasonomomonsomon 0.8 ■1:►I0 . ab-i co .......u... me � .2■..■....0 09 ■■...h' ono.,._ zi� ■.....�... . ap+ � m�em■.......0 1.0 MM mi AV, �� 4r oouo��RS ����...uouu ev Rim ii 111111111111111111011 IIIiiiJ " '1S: �d % iI! IIlIIII 2 ((kb". .► 111111111I\e 'tea j ag 4%.!11111�.1 ul1111111111I1 31111111111 ► ate, ee)1111"�I: igIIIIIIu1111oI iuuiinniii in��/o, o ii51111111111 11111111111 ��1. a; `1111111 fans ��1i�1111111 4 "1"11111 �.,,,1his `',' wrste'n so\■�■111111 5 ■■11■■��1�1_ ����NIM Ili"/U e•a►AuiuU11 6 iiiiiiriri__�_�__=immoi■■ ___. ,,�� • .•��•ommomiin g .■■■■■■■■■� ��"mm.■■■■■■■■■ a,i...r :iiii 7IIIIIIIIIIIIIMIMIIIIIIIIIIIIIIIIIMIIIMMIIIIMIIIIIIIIIIOIMIMIIMIIIIIIMIIIIIIIIIIIMIIIMIIIIIIIIUIIIIII _ 7% ■n !!15 ' 20 1 t TRAVEL TIME FOR CHANNEL FLOW (Kirpich Chart) H (feet) 500 Tc (min.) —200 —100 100 L (feet) —10000 f — —50 xamp le +� 50 = j — > > _ a3 _ O '0 C .O L C: Note: o C O U - a (1) For use with natural channels; _ w C o - 10 (2) For by paved channels, multiply _ 1000 E ._ 10 s _ E 1- a+ v1 - X O _ 5 Z .—.500 — 5 0 .0 Of y — — x �-100 1 1 TIME OF CONCENTRATION OF SMALL DRAINAGE BASINS • Source: VDOT Plate 5-3 • St. Francis Ave Time of Concentration Calculations PREDEV TOC: POA 100 ft overland flow 4.0% slope 0.35 C-value 11.0 min Seelye Chart 289 ft s. c. flow-woods 5.5% slope 1.2 fps velocity 4.0 min. NEH Figure 15-4 TOC= 15.0 min. POSTDEV TOC: POA 1 100 ft overland flow 4.0% slope 0.35 C-value 11.0 min Seelye Chart 222 ft s. c. flow-woods 5.0% slope 1.5 fps velocity 2.5 min. NEH Figure 15-4 00 ft Channel 4 ft height 0.0 min. Kirpich Chart TOC= 13.5 min. I . AREA TO POA 1 Subcat Reach on. Link Drainage Diagram for PREDEV RUNOFF Prepared by Shimp Engineering, P.C., Printed 9/13/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC PREDEV RUNOFF Type 1124-hr 1-YR Rainfall=2.97" Prepared by Shimp Engineering, P.C. Printed 9/13/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 2 Time span=1.00-24.00 hrs, dt=0.05 hrs, 461 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: AREA TO POA 1 Runoff Area=1.300 ac 1.54% Impervious Runoff Depth>0.32" Tc=15.0 min CN=60 Runoff=0.31 cfs 0.035 of Total Runoff Area = 1.300 ac Runoff Volume= 0.035 of Average Runoff Depth =0.32" 98.46%Pervious = 1.280 ac 1.54% Impervious = 0.020 ac PREDEV RUNOFF Type II 24-hr 1-YR Rainfall=2.97" Prepared by Shimp Engineering, P.C. Printed 9/13/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 3 Summary for Subcatchment 1 S: AREA TO POA 1 Runoff = 0.31 cfs @ 12.12 hrs, Volume= 0.035 af, Depth> 0.32" Runoff by SCS TR-20 method, UH=SCS, Time Span= 1.00-24.00 hrs, dt= 0.05 hrs Type 1124-hr 1-YR Rainfall=2.97" Area (ac) CN Description 0.900 61 >75% Grass cover, Good, HSG B 0.380 55 Woods, Good, HSG B * 0.020 98 Impervious, HSG B 1.300 60 Weighted Average 1.280 98.46% Pervious Area 0.020 1.54% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 15.0 Direct Entry, a PREDEV RUNOFF Type 1124-hr 10-YR Rainfall=5.42" Prepared by Shimp Engineering, P.C. Printed 9/13/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 4 Time span=1.00-24.00 hrs, dt=0.05 hrs, 461 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: AREA TO POA 1 Runoff Area=1.300 ac 1.54% Impervious Runoff Depth>1.55" Tc=15.0 min CN=60 Runoff=2.43 cfs 0.167 af Total Runoff Area = 1.300 ac Runoff Volume = 0.167 af Average Runoff Depth = 1.55" 98.46% Pervious = 1.280 ac 1.54% Impervious = 0.020 ac PREDEV RUNOFF Type 1124-hr 10-YR Rainfall=5.42" Prepared by Shimp Engineering, P.C. Printed 9/13/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Pale 5 Summary for Subcatchment 1 S: AREA TO POA 1 Runoff = 2.43 cfs @ 12.09 hrs, Volume= 0.167 af, Depth> 1.55" Runoff by SCS TR-20 method, UH=SCS, Time Span= 1.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 10-YR Rainfall=5.42" Area (ac) CN Description 0.900 61 >75% Grass cover, Good, HSG B 0.380 55 Woods, Good, HSG B * 0.020 98 Impervious, HSG B 1.300 60 Weighted Average 1.280 98.46% Pervious Area 0.020 1.54% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 15.0 Direct Entry, f PREDEV RUNOFF Type II 24-hr 100-YR Rainfall=8.86" Prepared by Shimp Engineering, P.C. Printed 9/13/2018 HydroCAD©9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 6 Time span=1.00-24.00 hrs, dt=0.05 hrs, 461 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: AREA TO POA 1 Runoff Area=1.300 ac 1.54% Impervious Runoff Depth>3.98" Tc=15.0 min CN=60 Runoff=6.62 cfs 0.431 of Total Runoff Area= 1.300 ac Runoff Volume=0.431 of Average Runoff Depth =3.98" 98.46% Pervious= 1.280 ac 1.54% Impervious = 0.020 ac PREDEV RUNOFF Type 1124-hr 100-YR Rainfall=8.86" Prepared by Shimp Engineering, P.C. Printed 9/13/2018 HydroCADO 9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 7 Summary for Subcatchment 1 S: AREA TO POA 1 Runoff = 6.62 cfs @ 12.08 hrs, Volume= 0.431 af, Depth> 3.98" Runoff by SCS TR-20 method, UH=SCS, Time Span= 1.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 100-YR Rainfall=8.86" Area (ac) CN Description 0.900 61 >75% Grass cover, Good, HSG B 0.380 55 Woods, Good, HSG B * 0.020 98 Impervious, HSG B 1.300 60 Weighted Average 1.280 98.46% Pervious Area 0.020 1.54% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 15.0 Direct Entry, Energy Balance Equation Summary St. Francis Ave 24 Hr 1 year Storm Comparison: Qdeveloped� �•F• *(Qpre-developed*RVPre-Developed)/RVdeveloped Qdeveloped Qforested RVforested) RVdeveloped POA 1: Qpre-develope,= 0.31 RVPre-Develol= 0.035 Max Qdevelc= 0.20 cfs RVDeveloped = 0.044 Achieved Post-Dev Max Runoff Qiyr= 0.16 cfs. Site complies with 9VAC25-870-66-(3)A Maximum Qioyr= 2.43 cfs (predev) Achieved Qioyr= 2.16 cfs Post-Dev Runoff Quantity Calculations: Post-Dev POA Drainage Map Post-Dev Ditch and Structure Drainage Map Post-Dev HydroCAD Report VDOT LD-229 Culvert Capacity VDOT LD-268 Ditch Capacity _ P ST. FRANC S ,..?, \ \\\, 1 ) I \\\ , POST-DEV POA DRAINAGE MAP l \\\ � / „ss • \` I \ ` \ \ •\ I / \` \ < ` � \ • I I I \ \ ` \ • ` ` �. \ •\ \ \ :\ N.` � \\ `\ \ \ ( \ `\• • \ \ ` \ I%. 1 \ \ \ \ \ I \ \ \ \ \ 1 Ate` \\ \ I 1 • \\II �\ \ •\ \ \\ \ \ \: t \\ \ \ \ »s \ \ I \` • \ ` `• \ \ ` \ r rr .ti i;�S ` \ \ i t� \ t\\ \ \ \\ \ •\ \ \\ \ \ \ r y- .\ / __--- - _) ss \ 1 \ \ \ \ \ ', Ty qry� j r ` ' ,O • \ I \I • -620— --_ `\ `' \\ \ 1 ,` u 1: rt \ \\\ ` ' POSTDEV DRAINAGE INFO ' � -----------------sza - ------------------ N \`\ \\, \\\ \\ \ k ` ,,; \\ , --\ \t, \ TO SWALE Sc POA: '- - /� ____ - ` ', 1 ` —' _ ,'= l,� MANAGED TURF, HSG B: 1.21 AC -- --__ - 1 0, —— • �/� �' � IMPERVIOUS: 0.12 AC ' -- ti TOTAL AREA TO POA: 1.33 AC ,� ,� (, �, i // - - _ -__' __ POA ,i��i j \yi \`. • J�R\P�o 652�' tv--�'� " • a 00 1 1 1 i' -- /' zss�S.C. nbw 648 ��� �v� ' y\ HYDROLOGIC DATA, POA I \\\ � \ ToC to S wale=13.5 min ' s :,/ RVl-YR= 0.044 AF ` � \ \ ' �/ N. -r \ \ \ / � � \ Q1-YR— 0.16 CfS` 1 \ \ ` ` \\ ' � r. \ \ • Q10-YR\ / / ` 2.16 CfS' 1 / � \ / i �� \.> - ' k± 1:\ �_ � 1 / < \/ / / ' ` 7.86 Cfs/ r / \ \ ___ �-- i t Q100-YR �„ti / '-- _ \\ \,\\ \�,, Note: Remainder of Site ' / �` ` ;' Runoff is Sheetflow. / / / t 040 , , to 1 \ i i / i /' \ I i 1 �' \ % / I \ I 1 -_-'\ I ., / I I CIA I N 5__,I \\\ •\\ ' I \'`_ -_— // ;/ r-' I N m \S / `` \ / ' '-'1 / � / / / \ 1 I `\�.•- i \\--- r' `) '..\ // /' / I I 1 �. —__________ \ • ' i / / / I I w I \\ i • \ \ / I I 1 �/ / / I , \ / • or I 1 ©— / 1 ,\ _ / j j j `\ I I \\ / / I 1 I \ • ' `�_ _III1_---- 1 1 `\ /__ -_ / I 1 1 \ `\\ - Of \ \\ J ' , I 1 I '\` _ -- _ c. , N. • N. _ .- 100 _ 0 100 200 300 ———; ( / \ \\ \\ L - - - - I \`, - — ------ ,' \� \\, \\`. ---------------- Scale: 1"=100' . R 4::: �t ST. FRANCISI� \ \ \, \\\ \\ \\ \\ \ \\ \\ I \\ \��-\ \\\ \\\ :::::�\ \ \ \ t;,::;;, POST—DEV DITCH & \ \ \ \\ \ \ \\ \ � \ \ ►'' :) \ \ \ ;;;;.,., INLET DRAINAGE MAP \ \ \ \\ \ I \ _ •:.•IA \ \ \ \ \ \ \ \ \ \ / �` \ ►'• :.* \ ......: ‘._td6,..„, \ \ \ \ \ \ \ \ \ \ \ / .. -- -.. • 1••••:':* \\ \\ \\ \\ \\ \\ \\ \\ \ 1 / / \\ �\ �.;.;.;: ,• \ \ _ ` -_ . \ - \ 1 \ \ \ \ \ \ � � / / / \ \ \ t \ �� \ 1 \\ 0 \ •\ •\\ \\ \ \ 1• `Jr� / ! / // \\ �� 1, f ta \ \ L" 4 1 I \ \' •.1 \\ ' \ \ F a, • "�'a / 1 � • i' / - _��� i \\ \ \ •\ \ \\ I \-/ -1 / \� \�1 •\\ • ------------- \ , \ \ T. � / / ----\ r G : ` \J \ \ \ \ ) ,.r; \ \ \\ \ r • ___ _ \ \ \ I \•.:•:•: �a 1` \ \ \ r-----628 --- ----_.____ _ ---� �\J `\ `\ / l f - �! mat " i ti a fyj ."' \ ice' • — -- ---- — cP `\ \\ TO DITCH 1 / /� � � \\ ��� —_— ..... + 6\ c,� \ 0.07 AC IMP\ , `''-- i �f -` •:• \'• �! — � '------ .... I Ul CP \ .;t,..- ;,;-'; \ / .....-'''' ———_....._,..,...._..,) \ --.'....:I Of; 1: ' \ 7. -... \ \ \ y�I v - \\ TO DITCH 2 & \.. \ \\ r f , \ EX. CULVERT \\ /,, ♦ \\ 1.13 AC TOT 1 / .:•.: :1� ���— — � � �� \\ 0.10 AC IMP / .: .•� c''''''''-‘\ s'''IC:\) '''''--."\)---- ------,- ,...V:. /\\ ... — — \ % •\ 3 1 \ \ 1 �, ter--- -` .� \ \ �'i 1\ /71. / / \\\ \\\ \ 60 0 60 120 180 \". -'i v ` v v Scale 1"=60' • AREA TO SWALE & POA 4P 3' RETWALL POND W .5' GRAVEL • Subcat Reach on. Drainage Diagram for POSTDEV RUNOFF Prepared by Shimp Engineering, P.C., Printed 9/13/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC POSTDEV RUNOFF Type 1124-hr 1-YR Rainfall=2.97" Prepared by Shimp Engineering, P.C. Printed 9/13/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 2 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: AREA TO SWALE & POA Runoff Area=1.330 ac 9.02% Impervious Runoff Depth>0.45" Tc=13.5 min CN=64 Runoff=0.61 cfs 0.050 of Pond 4P: 3' RETWALL POND W .5' GRAVEL Peak Elev=635.31' Storage=528 cf Inflow=0.61 cfs 0.050 of Outflow=0.16 cfs 0.044 of Total Runoff Area = 1.330 ac Runoff Volume = 0.050 of Average Runoff Depth =0.45" 90.98% Pervious = 1.210 ac 9.02% Impervious=0.120 ac POSTDEV RUNOFF Type 1124-hr 1-YR Rainfall=2.97" Prepared by Shimp Engineering, P.C. Printed 9/13/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 3 Summary for Subcatchment 1 S: AREA TO SWALE & POA Runoff = 0.61 cfs @ 12.09 hrs, Volume= 0.050 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 Rainfall=2.97" Area (ac) CN Description 1.210 61 >75% Grass cover, Good, HSG B * 0.120 98 Impervious 1.330 64 Weighted Average 1.210 90.98% Pervious Area 0.120 9.02% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 13.5 Direct Entry, Summary for Pond 4P: 3' RETWALL POND W .5' GRAVEL Inflow Area = 1.330 ac, 9.02% Impervious, Inflow Depth > 0.45" for 1-YR event Inflow = 0.61 cfs @ 12.09 hrs, Volume= 0.050 af Outflow = 0.16 cfs @ 12.48 hrs, Volume= 0.044 af, Atten= 74%, Lag= 23.6 min Primary = 0.16 cfs @ 12.48 hrs, Volume= 0.044 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 635.31' @ 12.48 hrs Surf.Area= 1,127 sf Storage= 528 cf Plug-Flow detention time= 108.3 min calculated for 0.044 af (87% of inflow) Center-of-Mass det. time= 46.2 min ( 956.5 - 910.2 ) Volume Invert Avail.Storage Storage Description #1 634.50' 4,818 cf POND STORAGE (Prismatic) Listed below (Recalc) Elevation Surf.Area Voids Inc.Store Cum.Store (feet) (sq-ft) (%) (cubic-feet) (cubic-feet) 634.50 990 0.0 0 0 635.00 990 40.0 198 198 636.00 1,430 100.0 1,210 1,408 638.00 1,980 100.0 3,410 4,818 Device Routing Invert Outlet Devices #1 Primary 634.00' 15.0" Round ST. E2A-E2 L= 10.0' Ke= 0.600 Inlet/ Outlet Invert= 634.00'/633.90' S= 0.0100 '/' Cc= 0.900 n= 0.013 #2 Device 1 635.00' 4.0" Vert. Orifice/Grate C= 0.600 #3 Device 1 636.45' 24.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads POSTDEV RUNOFF Type 1124-hr 1-YR Rainfall=2.97" Prepared by Shimp Engineering, P.C. Printed 9/13/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 4 Primary OutFlow Max=0.16 cfs @ 12.48 hrs HW=635.31' (Free Discharge) 4-1=ST. E2A-E2 (Passes 0.16 cfs of 4.07 cfs potential flow) 4L2=Orifice/Grate (Orifice Controls 0.16 cfs @ 1.90 fps) 3=Orifice/Grate ( Controls 0.00 cfs) POSTDEV RUNOFF Type 1124-hr 10-YR Rainfall=5.42" Prepared by Shimp Engineering, P.C. Printed 9/13/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 5 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: AREA TO SWALE & POA Runoff Area=1.330 ac 9.02% Impervious Runoff Depth>1.85" Tc=13.5 min CN=64 Runoff=3.25 cfs 0.205 af Pond 4P: 3' RETWALL POND W .5' GRAVEL Peak Elev=636.64' Storage=2,374 cf Inflow=3.25 cfs 0.205 af Outflow=2.16 cfs 0.197 af Total Runoff Area = 1.330 ac Runoff Volume=0.205 of Average Runoff Depth = 1.85" 90.98% Pervious= 1.210 ac 9.02% Impervious=0.120 ac POSTDEV RUNOFF Type II 24-hr 10-YR Rainfall=5.42" Prepared by Shimp Engineering, P.C. Printed 9/13/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 6 Summary for Subcatchment 1 S: AREA TO SWALE & POA Runoff = 3.25 cfs @ 12.06 hrs, Volume= 0.205 af, Depth> 1.85" 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 Rainfall=5.42" Area (ac) CN Description 1.210 61 >75% Grass cover, Good, HSG B * 0.120 98 Impervious 1.330 64 Weighted Average 1.210 90.98% Pervious Area 0.120 9.02% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 13.5 Direct Entry, Summary for Pond 4P: 3' RETWALL POND W .5' GRAVEL Inflow Area = 1.330 ac, 9.02% Impervious, Inflow Depth > 1.85" for 10-YR event Inflow = 3.25 cfs @ 12.06 hrs, Volume= 0.205 af Outflow = 2.16 cfs @ 12.18 hrs, Volume= 0.197 af, Atten= 34%, Lag= 6.8 min Primary = 2.16 cfs @ 12.18 hrs, Volume= 0.197 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 636.64' @ 12.18 hrs Surf.Area= 1,605 sf Storage= 2,374 cf Plug-Flow detention time= 58.1 min calculated for 0.197 af (96% of inflow) Center-of-Mass det. time= 36.1 min ( 895.9 - 859.8 ) Volume Invert Avail.Storage Storage Description #1 634.50' 4,818 cf POND STORAGE (Prismatic) Listed below (Recalc) Elevation Surf.Area Voids Inc.Store Cum.Store (feet) (sq-ft) (%) (cubic-feet) (cubic-feet) 634.50 990 0.0 0 0 635.00 990 40.0 198 198 636.00 1,430 100.0 1,210 1,408 638.00 1,980 100.0 3,410 4,818 Device Routing Invert Outlet Devices #1 Primary 634.00' 15.0" Round ST. E2A-E2 L= 10.0' Ke= 0.600 Inlet/ Outlet Invert= 634.00'/ 633.90' S= 0.0100 '/' Cc= 0.900 n= 0.013 #2 Device 1 635.00' 4.0" Vert. Orifice/Grate C= 0.600 #3 Device 1 636.45' 24.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads POSTDEV RUNOFF Type 1124-hr 10-YR Rainfall=5.42" Prepared by Shimp Engineering, P.C. Printed 9/13/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 7 Primary OutFlow Max=2.10 cfs @ 12.18 hrs HW=636.63' (Free Discharge) L1=ST. E2A-E2 (Passes 2.10 cfs of 7.85 cfs potential flow) L2=Orifice/Grate (Orifice Controls 0.51 cfs @ 5.83 fps) 3=Orifice/Grate (Weir Controls 1.59 cfs @ 1.39 fps) POSTDEV RUNOFF Type 1124-hr 100-YR Rainfall=8.86" Prepared by Shimp Engineering, P.C. Printed 9/13/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 8 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: AREA TO SWALE& POA Runoff Area=1.330 ac 9.02% Impervious Runoff Depth>4.46" Tc=13.5 min CN=64 Runoff=8.05 cfs 0.495 af Pond 4P: 3' RETWALL POND W .5' GRAVEL Peak Elev=636.95' Storage=2,894 cf Inflow=8.05 cfs 0.495 af Outflow=7.86 cfs 0.484 af Total Runoff Area = 1.330 ac Runoff Volume = 0.495 of Average Runoff Depth = 4.46" 90.98% Pervious = 1.210 ac 9.02% Impervious=0.120 ac . POSTDEV RUNOFF Type 1124-hr 100-YR Rainfall=8.86" Prepared by Shimp Engineering, P.C. Printed 9/13/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 9 Summary for Subcatchment 1 S: AREA TO SWALE & POA Runoff = 8.05 cfs @ 12.06 hrs, Volume= 0.495 af, Depth> 4.46" 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 Rainfall=8.86" Area (ac) CN Description 1.210 61 >75% Grass cover, Good, HSG B * 0.120 98 Impervious 1.330 64 Weighted Average 1.210 90.98% Pervious Area 0.120 9.02% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 13.5 Direct Entry, Summary for Pond 4P: 3' RETWALL POND W .5' GRAVEL Inflow Area = 1.330 ac, 9.02% Impervious, Inflow Depth > 4.46" for 100-YR event Inflow = 8.05 cfs @ 12.06 hrs, Volume= 0.495 of Outflow = 7.86 cfs @ 12.08 hrs, Volume= 0.484 af, Atten= 2%, Lag= 1.4 min Primary = 7.86 cfs @ 12.08 hrs, Volume= 0.484 af Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Peak Elev= 636.95' @ 12.08 hrs Surf.Area= 1,692 sf Storage= 2,894 cf Plug-Flow detention time= 37.8 min calculated for 0.484 af (98% of inflow) Center-of-Mass det. time= 25.8 min ( 860.1 - 834.3 ) Volume Invert Avail.Storage Storage Description #1 634.50' 4,818 cf POND STORAGE (Prismatic) Listed below (Recalc) Elevation Surf.Area Voids Inc.Store Cum.Store (feet) (sq-ft) (%) (cubic-feet) (cubic-feet) 634.50 990 0.0 0 0 635.00 990 40.0 198 198 636.00 1,430 100.0 1,210 1,408 638.00 1,980 100.0 3,410 4,818 Device Routing Invert Outlet Devices #1 Primary 634.00' 15.0" Round ST. E2A-E2 L= 10.0' Ke= 0.600 Inlet/Outlet Invert= 634.00' /633.90' S= 0.0100 '/' Cc= 0.900 n= 0.013 #2 Device 1 635.00' 4.0" Vert. Orifice/Grate C= 0.600 #3 Device 1 636.45' 24.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads • POSTDEV RUNOFF Type 11 24-hr 100-YR Rainfall=8.86" Prepared by Shimp Engineering, P.C. Printed 9/13/2018 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 10 Primary OutFlow Max=7.70 cfs @ 12.08 hrs HW=636.94' (Free Discharge) 1-1=ST. E2A-E2 (Passes 7.70 cfs of 8.44 cfs potential flow) 4L2=Orifice/Grate (Orifice Controls 0.56 cfs @ 6.42 fps) 3=Orifice/Grate (Weir Controls 7.14 cfs @ 2.30 fps) LD-229 Storm Drain Design Computations . St. Francis Ave From To Point Catch Runoff Inc Accum Tot Tot Tot Up Dn Pipe Inv Pipe Pipe Velocity Flow time Point A Coef AC AC Tc Int Flow Inv Inv Len S Dim Cap Inc (ac) (min) (in/hr) (cfs) El El (ft) % (in) (cfs) (ft/s) (min) 1 2 3 5 6 7 8 9 10 11 12 13 14 15 16 17 Ex. Up Ex. Down 1.13 0.36 0.40 0.40 13.5 5.25 2.11 638.1 637.4 25.2 2.70% 18 17.26 6.6 0.06 St. Francis Ave _ Modified LD-268 Roadside and Median Ditch Design Form Side Slope Min. Max Earth Protective Lining Ditch C A CA Tc 110 010 1 L :1 R Slope Slope Allowable n=.03 EC-2:n=.05 EC-3:n=.15 Ft/Ft Ft/Ft Velocity VeL` On I Velocity I Depth On I Depth 1 0.58 0.14 0.08 5.0 7.05 0.58 3 3 0.03 0.14 4.0 0.03 2.19 0.26 2 0.36 1.13 0.40 13.5 5.25 2.11 3 3 0.05 0.10 4.0 0.11 2.94 0.46 c . Post-Dev Runoff Quality Calculations: Post-Dev Land Cover Map VRRM New Development Spreadsheet ST. FRANCIS \ \ POST-DEV LAND COVER MAP , 1. \\\ t 1\ \ / r \I ;i�� 4�'� / // \ `\fit ' 1 � E , / 1\0 NOTE: VRRM AREA INCLUDES �i ',►-� 2.40 ACRE DISTURBED AREA, / I 4.00 ACRE SWM FOREST/OPEN ✓' ''N \ .. SPACE EASEMENT, AND 2.75 4 t t\v�• .\ , �'\ ACRE FUTURE HOUSE SITES \ „ ^ \ \\ , \ (4 x 30,000 SF = 2.75 AC). \ \\ ` �'' - ; --a` ,% ALL AREAS ARE HSG B. �.i - ,; \ \\ - 14,836 SF i - NEW ROAD =0.34 AC IMP � ' i� \\� i �\ POSTDEV LAND COVER ��y 1 \ VRRM AREA = 2.40 AC \P ) i = - . \,<,� DISTURBED + 4.00 AC ,.-r ► , / \sue!____J FOREST +2.75 AC \ \ FUTURE HOUSE SITES \ ,', ' 2.06 AC TURF - � . _ - - - , '9 \o ! IN DISTURBED _ _ _ - - - - DISTURBED �,� TOTAL AREA: 9.15 AC '= AREA , - - - ,-'\ - AREA \\` SUM OF DISTURBED AREA: i i� \\\\`�_____ 2.06 AC TURF i 0.34 AC I M P \ SUM OF BUILDING SITES: i `\\ `\, 2.48 AC TURF 0.27 AC IMP \ II<"----- „„ \\\ ( TOTAL NEW MANAGED TURF, \ I 1 HSG B =4.54 AC \ ) - TOTAL NEW IMPERVIOUS: \ =0.61 AC \ \ NEW 30,000 SF BUILDING SITE. TYPICAL SITE INCLUDES: -A.zr777 <---- ...-"- ,-'„-- V:\ 27,000 SF TURF 2,000 SF IMP HOUSE 1,000 SF IMP DRIVEWAY/DECK ,, 4.00 ACRE SWM \\ FOREST/OPEN 100 0 100 200 300 \ SPACE EASEMENT ■ ■ ■ ■ ■ A Scale: 1"=100' • DEQ Virginia Runoff Reduction Method New Development Compliance Spreadsheet-Version 3.0 L:2011 BMP Standards and Specifications E'2013 Draft BMP Standards and Specifications Project Name: St.Francis Ave data input cells Date: 9/14/2018 constant values BMP Design Specifications List: 2013 Draft Stds&Specs calculation cells Site Information final results Post-Development Project (Treatment Volume and Loads) Land Cover (acres) A Soils B Soils C Soils D Soils Totals Forest/Open Space(acres)--undisturbed, j .rotected forest/o.en s.ace or reforested land 4.00 i 4.00 Managed Turf(acres)--disturbed,graded for 4.54 ards or other turf to be mowed/mane:ed 4.54 .11 Impervious Cover(acres) 0.61 0.61 •Forest/Open Space areas must be protected in accordance with the Virginia Runoff Reduction Method 9.15 Constants Runoff Coefficients(Rv) Annual Rainfall(inches) 43 A Soils B 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(mg/L) 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 i Post-Development Requirement for Site Area TP Load Reduction Required(Ib/yr) -0.09 ** TP LOAD REDUCTION NOT REQUIRED LAND COVER SUMMARY--POST DEVELOPMENT Land Cover Summary Treatment Volume and Nutrient Loads Forest/Open Space Cover(acres) 4.00 Treatment Volume 0.1340 (acre-ft) Weighted Rv(forest) 0.03 Treatment Volume(cubic feet) 5,835 %Forest 44% TP Load(lb/yr) 3.67 TN Load(lb/yr) Managed Turf Cover(acres) 4.54 ',informational Purposes Onlvl 26.23 Weighted Rv(turf) 0.20 %Managed Turf 50% Impervious Cover(acres) 0.61 Rv(impervious) 0.95 %Impervious 7% Site Area(acres) 9.15 Site Rv 0.18 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 ' 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. AREA CHECK OK. OK. OK. OK. [ OK. Site Treatment Volume(ft3) ss36 - Runoff Reduction Volume and TP By Drainage Area. D.A.A D.A.B D.A.C . D.A.D D.A.E TOTAL RUNOFF REDUCTION VOLUME ACHIEVED(ft3) 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 0.00 1 NITROGEN LOAD REDUCTION ACHIEVED(Ib/yr) 0.00 0.00 0.00 0.00 0.00 0.00 Total Phosphorus FINAL POST-DEVELOPMENT TP LOAD(Ib/yr) 3.67 TP LOAD REDUCTION REQUIRED(Ib/yr) -0.09 TP LOAD REDUCTION ACHIEVED (Ib/yr) 0.00 --- TP LOAD REMAINING(Ib/yr): 3.67 --- REMAINING TP LOAD REDUCTION REQUIRED(Ib/yr):, 0.00 k***TARGET TP REDUCTION EXCEEDED BY 0.09 LB/YEAR** - Total Nitrogen(For Information Purposes) --- . POST-DEVELOPMENT LOAD(Ib/yr) 26.23 NITROGEN LOAD REDUCTION ACHIEVED(Ib/yr) 0.00 --- REMAINING POST-DEVELOPMENT NITROGEN LOAD Ib/yr) 26.23 * a Independent Reports: Excerpt from NRCS Soils Report NOAA Precipitation Report A Q Z • '�N 4225770 4225840 4225910 4225060 4226050 4226120 4226190 �D 78°29'21"W 78°24 21"W z R 0 o z 6 O O A� � n C a a CD 8, 6 a F. S �} t r o cD n Q w '11l • . _ ` y ?b '• ' lb : c . - _` L . -� r 'llef _ - iiiiiph ., , 1111 - • , s 4 . _. si i,. ,M. r• .�_^le it, ••r• 'i h. c. '- _ : - j'S •� - • •�,A, / JF 40, * `� 4 ` • 0 .r, 4 . 4 ' ‘ . .1 t - •;it •• ? CL I 0 0 II47r•l}5f1 • � t+� 4 cn ow 2 o m u Z s. m. rf V . • +•., ` • III A 1.L ... 11N CD � N ._ 1 5� i i" I ;ice =='sue• • -011 ' r i. d ,- (O CD 0...„ •' O o 78°28'4%'W 1 78°28'49"W A 00 4225840 4225910 4225980 4226050 4226120 4226190 O A z Hydrologic Soil Group—Albemarle County,Virginia MAP LEGEND MAP INFORMATION Area of Interest(AOI) • C The soil surveys that comprise your AOI were mapped at n Area of Interest(AOI) C/D 1:15,800. •Soils • D Warning:Soil Map may not be valid at this scale. Soil Rating Polygons 0 A p Not rated or not available Enlargement of maps beyond the scale of mapping can cause misunderstanding of the detail of mapping and accuracy of soil hia A/D Water Features line placement.The maps do not show the small areas of Streams and Canals contrasting soils that could have been shown at a more detailed B scale. Transportation B/D a-r Rails Please rely on the bar scale on each map sheet for map C measurements. Interstate Highways C/D US Routes Source of Map: Natural Resources Conservation Service Li D Web Soil Survey URL: Major Roads Coordinate System: Web Mercator(EPSG:3857) 0 Not rated or not available Local Roads Maps from the Web Soil Survey are based on the Web Mercator Soil Rating Lines projection,which preserves direction and shape but distorts Background y A distance and area.A projection that preserves area,such as the Aerial Photography Albers equal-area conic projection,should be used if more A/D accurate calculations of distance or area are required. "*.0 B This product is generated from the USDA-NRCS certified data as B/D of the version date(s)listed below. C Soil Survey Area: Albemarle County,Virginia Survey Area Data: Version 11,Oct 11,2017 tV C/D Soil map units are labeled(as space allows)for map scales 0%0 D 1:50,000 or larger. . . Not rated or not available Date(s)aerial images were photographed: Apr 22,2015—Mar Soil Rating Points 10,2017 • A The orthophoto or other base map on which the soil lines were compiled and digitized probably differs from the background • A/D imagery displayed on these maps.As a result,some minor • g shifting of map unit boundaries may be evident. • B/D USDA Natural Resources Web Soil Survey 9/18/2018 Conservation Service National Cooperative Soil Survey Page 2 of 4 Hydrologic Soil Group—Albemarle County,Virginia Hydrologic Soil Group Map unit symbol Map unit name Rating Acres in AOI Percent of AOI 14B Chester loam,2 to 7 B 13.31 49.9% percent slopes 14C Chester loam,7 to 15 B 6.7 25.3% percent slopes 36B Hayesville loam,2 to 7 B 4.1 15.5% percent slopes 36C Hayesville loam,7 to 15 B 2.5 9.3% percent slopes Totals for Area of Interest 26.6 100.0% 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. USDA Natural Resources Web Soil Survey 9/18/2018 NM Conservation Service National Cooperative Soil Survey Page 3 of 4 Hydrologic Soil Group—Albemarle County,Virginia Rating Options Aggregation Method: Dominant Condition Component Percent Cutoff: None Specified Tie-break Rule: Higher USDA Natural Resources Web Soil Survey 9/18/2018 aai Conservation Service National Cooperative Soil Survey Page 4 of 4 NOAA Atlas 14,Volume 2,Version 3 "q Location name:Earlysville,Virginia,USA* Latitude:38.1554°,Longitude:-78.483° '°Hfr) Elevation:643.07 ft** ?co - *source:ESRI Maps '' .. **source:USGS POINT PRECIPITATION FREQUENCY ESTIMATES G.M.Bonnin,D.Martin,B.Lin,T.Parzybok,M.Yekta,and D.Riley NOAA,National Weather Service,Silver Spring,Maryland PF tabular I PF graphical I Maps & aerials PF tabular PDS-based point precipitation frequency estimates with 90%confidence intervals (in inches)1 Average recurrence interval(years) Duration 1 2 5 10 j 25 50 L 100 200 500 1000 5-min 0.345 0.413 0.486 0.547 0.617 0.672 0.725 0.774 0.836 0.886 1(0 312-0.382) (0.373-0.457) (0.438-0.537) (0.492-0.604)i(0.552-0.680) (0.599-0.740);(0.641-0.798) (0.680-0.853) (0.726-0.924) (0.762-0.983) 10-min 0.552 0.660 0.778 0.874 0.984 1.07 1.15 I 1.23 1.32 1.40 (0.498-0.611) (0.597-0.731) (0.702-0.860) (0.787-0.966)i (0.880-1.08) (0.954-1.18) (1.02-1.27) ' (1.08-1.35) (1.15-1.46) (1.20-1.55) 15-min . 0.690 0.830 0.984 1.11 1.25 1.36 I 1.46 1.55 I 1.66 1.75 )(0_623-0.763).(0 750-0.919) (0_888-1_09) (0.995-1.22)i (1.12-1.37)- (1.21-1.49) (1.29-1.60) (1.36-1.71) L(1.45-1.84) (1.51-1.94) 30-min 0.946 1.15 1.40 1.60 1.85 I 2.04 2.23 2.41 2.65 2.84 (0.854-1.05) (1.04-1.27) i(1.26-1.55) (1.44-1.77) (1.65-2.04) (1.82-2.25) (1.97-2.46) (2.12-2.66) (2.30-2.93) (2.44-3.15) 60-min 1.18 1.44 1.79 2.09 2.46 2.77 3.07 3.38 3.80 4.14 I (1.07-1.31) (1.30-1.59) (1.62-1.98) (1.88-2.31) (2.20-2.71) (2.46-3.05) (2.72-3.38) .. (2.97-3.73) (3.30-4.20) (3.56-4.59) 2-hr 1.42 1.72 I 2.16 2.54 3.03 3.44 3.86 4.31 4.94 5.47 1,(1.26-1.60) (1.53-1.94) (1.91-2.43) (2.25-2.85) (2.66-3.40) (3.01-3.86) (3.36-4.34) (3.72-4.84) (4.21-5.56) (4.61-6.18) 3-hr 1.55 1.88 2.35 2.76 I 3.30 3.76 1 4.23 4.73 5.42 6.02 4(1.37-1.77) (1.66-2.14)J (2.07-2.68) (2.43-3.14) 1 (2.88-3.74) (3.26-4.25) (3.65-4.79) (4.04-5.36) (4.58-6.16) (5.03-6.85) 6-hr 1.97 2.39 2.97 3.49 I 4.20 4.82 5.47 6.18 7.20 8.10 !(1.75-224) (2.12-2.71) (2.62-3.36) (3.0773.95) (3.67-4.74) (4.18-5.43) (4.70-6.17) (5.25-6.98) (6.03-8.14) (6.68-9.18) 12-hr 2.48 2.99 3.73 4.41 5.37 6.22 7.14 8.17 9.69 11.1 (2.20-2.83) I (2.65-3.41) (3.29-4.25) (3.88-5.02) (4.68-6.09) (5.36-7.05) (6.09-8.10) (6.87-9.26) (7.98-11.0) (8.96-12.6) 24-hr 2.97 3.59 4.59 5.42 6.65 7.70 8.86 10.1 12.0 13.7 (2.67-3.34) (3.23-4.04) (4.11-5.15) (4.84-6.07) (5.90-7.44) (6.78-8.59) (7.74-9.87) (8.76-11.3) (10.2-13.4) (11.5-15.2) 1 2-day 3.50 4.24 5.38 I 6.32 7.68 8.82 10.1 11.4 13.4 15.0 (3.15-3.91) (3.82-4.73) (4.84-6.00) L(5 67-7.04) (6.84-8.54) (7.80-9.79) (8.82-11.2) (9.92-12.7) I (11.5-14.9) (12.7-16.7) 3-day I 3.72 4.51 5.72 1 6.72 8.16 9.37 1 10.7 12.1 14.1 15.9 (3.38-4.13) (4.09-5.00) (5.19-6.34) (6.07-7.44) (7.34-9.02) (8.37-10.3) (9.46-11.8) (10.6-13.4) (12.3-15.7)� (13.6-17.6)i L4-day 3.95 4.78 I 6.07 7.12 8.65 I 9.92 11.3 12.8 14.9 I 16.8 (3.61-4.36) I (4.37-5.27) (5.53-6.69) (6.48-7.83) (7.84-9.51) (8.94-10.9) (10.1-12.4) (11.3-14.1) (13.1-16.5) (14.5-18.5) 7-day 4.59 5.53 6.90 8.03 9.65 11.0 12.4 14.0 16.2 18.0 1 (4.20-5.03) (5.06-6.05) (6.31-7.57) (7.33-8 80) (8.76-10.6) (9.93-12.0) (11.1-13.6) I (12.4-15.3) (14.2-17.8) (15.7-19.9)J 5.21 I 6.25 7.71 8.90 10.6 11.9 13.3 I 14.9 17.0 18.7 10-day (4.79-5.66) (5.76-6.79) (7.09-8.37) ,(8.16 9.65) (9.65-11.5) (10.8-12.9) (12.1_14.5) (13.3-16.1) (15.1-18.5) (16.5-20.5) 20-day 6.85 8.17 9.86 11.2 13.0 14.4 15.9 17.3 19.3 20.9 II (6.40-7.36) (7.64-8.78) (9.20-10.6) (10.4-12.0) (12.1-13.9) I (13.3-15.5) (14.6-17.0) (15.9-18.7) (17.6-20.9) (18.9-22.6) 30-day] 8.41 I 9.97 11.8 13.2 15.0 16.3 17.7 19.0 20.7 22.0 (7.90 8.98) 1 (9.37-10.6) (11.1-12.6) (12.3-14.0) (14.0-16.0) (15.2-17.4) (16.4-18.9) (17.6-20.3) (19.1-22.2) (20.2-23:6) j 45-day 10.5 12.4 14.5 16.0 18.0 19.5 20.9 22.3 24.1 25.4 (9.90-11.2) (11.7j13.2) (13.6-15.4) (15.1-17.0) (16.9-19.1) 1 (18.3-20.7) (19.6-22.2)_ (20.8-23.7) (22.3-25.7) (23.4-27.1) 60 day 12.3 14.5 16.7 18.4 20.5 22.1 23.5 24.9 26.7 28.0 (11.7-13.0) (13.7-15.3) I (15.8-17.7) (17.4-19.4) (19.3-21.6) (20.8-23.3) I (22.1-24.9) (23.4-26.4) (24.9-28.3) (26.0-29.7) 1 Precipitation frequency(PF)estimates in this table are based on frequency analysis of partial duration series(PDS). Numbers in parenthesis are PF estimates at lower and upper bounds of the 90%confidence interval.The probability that precipitation frequency estimates(for a given duration and average recurrence interval)will be greater than the upper bound(or less than the lower bound)is 5%.Estimates at upper bounds are not checked against probable maximum precipitation(PMP)estimates and may be higher than currently valid PMP values. Please refer to NOAA Atlas 14 document for more information. Back to Top PF graphical r J PDS-based depth-duration-frequency (DDF) curves Latitude: 38.1554°, Longitude: -78.4830° 30 i i I i i I 1 Average recurrence 25 interval (years) c 20 ..... ... ---- - •- 2 a — 5 -o 15 ...... .. — 10 O • — 25 p — 50 C, 10 — too o' • — 200 5 _ — 500 • — 1000 0 - E E E E E N Akb N a' -o v v H N N A 4 n 0 N D v v -2 vp N O '4-1 �o 8 n et Mg Duration 30 1 25 ..2L 20 Duration Cl.) 5-min — 2-day v • c 15 — 10-min — 3-day ^''� 15 mIn — 4-day a 30-min — 7-day 10 ..___ — 60-min — 10-day — 2fir — 20-day _ — 3fir — 30-day 6fir — 45-day — 60-day 12fir — y 1 a -, — 24-hr 1 2 5 10 25 50 100 200 500 1000 Average recurrence interval (years) NOAA Atlas 14,Volume 2,Version 3 Created(GMT):Wed Sep 12 19:33:24 2018 Back to Top Maps & aerials Small scale terrain II '' 1 0 , 0 ^. 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