Loading...
HomeMy WebLinkAboutWPO201600018 Calculations 2016-05-05 PROJECT MANAGEMENT SHIMPCIVIL ENGINEERING LAND PLANNING ENGINEERING May 5, 2015 �. John Anderson Albemarle County Regarding: Castalia Pond Stormwater Management Dear Mr. Anderson, Enclosed are the calculations and details relating to stormwater treatment for Castalia Pond.Additional water quality controls do not need to be implemented because pollutant removal is achieved with the amount of open space within the 39.36 acre drainage area of the pond. This drainage area was used for water quality calculations in the VRRM spreadsheet attached. The 601.81 acre site is already subject to an easement with the Virginia Outdoors Foundation so no other easement is needed. The following energy balance equation for channel protection is satisfied for the 1 year, 24hr storm. The reduced flowrate is achieved by using a weir in the standpipe of the pond. 1.F.* (QpYe * RVpre) Qdev = RVdev The values of peak flow and runoff are shown in the table below, as well as in the attached HydroCAD storm report. Castalia Pond Q1(pre) 0.41 cfs Q1(post) 0.11 cfs RV1(pre) 0.198 a.f. RV1(post) 0.297 a.f. The peak flowrate of the 10 year, 24hr storm is decreased from pre-development to post-development for flood protection. The proposed dam structure in the pond is tall enough to adequately contain the 10 year storm. Flow Summary: Castalia Pond Q10(pre) 11.51 cfs Q1o(post) 7.49 cfs If you have any questions please do not hesitate to contact me at your earliest opportunity. I may be reached at: Justin a shimp-enqineering.com or by phone at 434-953-6116. Yours Truly, Justin Shimp, P.E. Contents: '" Pre-Development Stormwater Management Calculations: Pre-Development Drainage Map Pre-Development HydroCAD Analysis .. Post-Development Stormwater Management Calculations: Post-Development Drainage Map "' Virginia Runoff Removal Method Reports Post-Development HydroCAD Analysis a Independent Reports: Excerpt from NRCS Soils Report NOAA Precipitation Report a.. a S a i .. S a . .. a. Pre-Development Stormwater Management Calculations Pre-Development Drainage Map Pre-Development HydroCAD Analysis a. a a ar a aaa a. aa. a.. a aar CD -1-) O N C n O „5 , -,_,ff-- — --(0-‹ Li , < \--Az, v\-7,-Air' ii, o Lc) i -- L_ 1,-, 1/1 At _i__\//;i* lirr,,,41, * it, * 4 'S"-7 'II t I I I I I I GO CO 12\\\\\� \ \ "' i0X IJ. vim o \\\ \, O\ 0 0 i \ 011,E • 00 2 ■■ 0 71d .*.\'2 \ : \,,.XXv7\,,9\._7\_9 1 1 1 iaCIK(1 -: 7/\_9‘..2\70 / /I // // / / /1 ' f\*I)\'' \0041 4( q * lir 0 0 / / / /� tr; �� \ \ \ \ \ \ k\P 114/1-0 * * Pi * 10 10X 0 0 nr,_, x _;„_* o * * _ 4.i i p ,_,,_9\_,,„Y e x,_A 9 • `\ / ' ' ' ' / ' I / /' / /�/ // --- IV N '\/ ' 2/\' / -' V V V / /' / /, i - \ , - _\ _ '4K 7 * / K / * - / / / / ' / / ' / ` / / / / / / -- * \Y �\` \ S\/_lJ_I ` / / `fir '^_ '- / / / / / ' I / / // v4 \- ;Vqt---i - / / /' I // / / ' ' \ \ ' I 4X ; \/ I I \I 0 OP 0 0 . r-- /// i I 1 / / $ 1\rk 6,L\/\ 4c§\41 .Q_ '>'-/ k),\\ U,';',V, 10,A '' XerA707A7 Art / //1 1 \\ i /* k --'v� `v1 \ `-,lel*'1 4'T' `nom' / b�4x 4 _ \\\ \\* -, * 00/ / '\ -0x0'1 \O 1--\7 :" Thr 4 P 00 *A j*A' ,/-7 *-__10, "4K 0j,}1X6 0 *;\3/0/*/*FI Ve I'v- i * *q*/*i_ y_/\ ,,,-7Avi/oAr-)_ /0-0 ' ___ ... __ , _., , ,_, __ _ , ,_ -421.- -,, __,___., J ; CI ,.J; ,i. ./ )_-•\,f-/ 1o .:0_ , A,7 p 4r.r,_-< o o -')/h/'-u -oco 7# -------t----- .$4 ir _.„*._,O. 2_*/ 0/0 •-,--' * 57.v .'-* / ' \ */\ * 43/7q/0 /1 ,Q ,/0 / ;Q .K \' \\ 4 - / / e ' 0-* - \\\* oq /*\ f /- � o. /o/ \/ \ J o I-- ,-oia,5\, /o-,0 : \ \ 0 * \/o ,* I ':4'o; 0 4x 60 0 - ' 3 0'0'0 4 ' w fX CD u, 1-:-- \ 6.4.0 *-- \-0 0 /-/-\\-.)--- 1 I* I '-'-'0'--V----...-..A ./‘'.7LZ\ A - % < L._ ., ' 0 lir , ,t7A-,,,,_( Ch04., * ,0 q(if 4,,, * , _.\_,,,,7 At ki ,, _: ,,-. \ o,opp - \''Y',, t'.1 1,q,lo o,o- ‘,1- - 1 , 1 Qo = 0 0 Lu Jov* voco -,o-zbv / *olio * _o4_/) o * c,_ co ..< • ' o xe4 o\ *ok4x- Z1v,,,,,o/-a0iLk ly\_ LA_ _A_ __/\ lk � ` 1 \ 0c" ° 3 " ),/ �/q.,VX0X/ \-7_K —•— \r"-:. ✓\' C \/S� iii i,i i * i i iiii i i- -, r•., ..r ti�\ y i i i iii i ,K-::;,::K 's= r'.. ;,`.r'r,..YK f\ 1_ / / _ ' - e'''' 'V'A U/ * i i i i i� w" , "� - / / / IV /� V _ i��\-_ / i i i ii i iii i >J3,- ::::7,%\:':-..:7'-'"- -:?:: -J` _ / /// n0/, \/ p ' 0 4. 0-* �� //\-, i ii i ii i i1r!/C , .tetS -i". A Yy ,- — — _ _ / / --\ 4.• ♦ -A/ /jV0I . \4�Viiii i ii ii i . , ;•"_k,..,:.\ J i i i i 'X ` _---- -- N c"\---- \//^- i i i '' k .<< '.r 'i//}!-- I \ /'/ / -4. • V C _ _ \ \ • ,\���-_- n\ 11 I\\ \\ \\ \\ \ l / 4, / = /� / / NA r \* l I 1 -'� / - -----\ / \ \ \ \ \ \ \\\\ t / s \, / \ \ \ \ \ \ \ 1I \ I \\ \c' —\ __ \ / \\\\\\\ \\\ \\ \\ \ / / \1 \\ I �\ \ \ \ \ 1 \ \ \ _-_-tel 1 n --„ \ / I ) I I I I / , I / / \\ •,, \\ / I l I I I \I \\ \�J' I I I I I I I / I /' \ CastaliaPreDev Type 1124-hr 1-yr storm Rainfall=2.90" Prepared by Hewlett-Packard Company Printed 5/5/2016 HydroCADOO 9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 1 Summary for Subcatchment 1S: PreDevelopment Runoff = 0.41 cfs @ 14.28 hrs, Volume= 0.198 af, Depth> 0.06" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 1-yr storm Rainfall=2.90" Area (ac) CN Description 0.700 98 Water Surface, HSG C 34.400 48 Brush, Good, HSG B 4.300 65 Brush, Good, HSG C 39.400 51 Weighted Average 38.700 98.22% Pervious Area 0.700 1.78% Impervious Area I Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 72.6 2,911 0.0500 0.67 Lag/CN Method, ISubcatchment 1S: PreDevelopment Hydrograph I I I I I I I I 0.44 , �- 1----+----1--- 1----�I I 1 I 1 I I II ' 1 I _ 1 I I 1 i I ❑Runoff 0.42 I I I7 I I I I I T�/1 I��7 1� }/�I r 1 T 1 r 0.4 -i pelf-24,-- r-Y�-yr' storm I- J-- -i I 0.38 Q�.nlr 1 0.36 _Rii till=t.90' 1 1 I 1 I I 1 r r i --I----1--- r. I r 0.34 _ 1 I j� MI � I I �_/� 11�^ 1 1 I I I /!,. I I 0.32 F�Mi SFJ 1� ANefh39 4GO A\r r , i -4 - ---- 1 1 1 1 1 I 1 1 1 I 1 0 28 RUnof#_Vol une 0.198_af 1 � i -- 1 f I 1 1 I II U 0.26 ROI!'fO Dopff�>0.0$"-j----�-- --- --- --------T----I----I- �- 0.24 r 0.22 _ 1___ i L I L 1 I L I L ' -Flow ten kith , 1 1 I 1 1 1 I LL 0.2 Flow`� WJ�f. 1 Y r - T r 0.18 _a6„...„,'6.11`) 1 1 //N• 1 1 1 I 1 1 I 0.16 rrryry. �O Min T L 0.14 _J_���fi, lllln-;----;--------;- I---- --- --------;----;----;---- 0.12 i -- 1 1 r 1 0.1 I 1 I 7 1 r /� L L 1 I 1 I 1 1 L \ _ - I I 1 1 I I I I I 1 I I I 0.08 / _7C _•I ___T I T I I- y____r___y____I____T I Y 0.06 1 1 1 I 1 1 1 I I I I I I 1 1 1 I 1 1 I 1 1 I 1 1 I 1 1 0.04 J 1 1 I L 1 L _J L 1 1 1 I L I I I I I I 1 I 1 1 I I I 0.02 0 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) I I CastaliaPreDev Type 1124-hr 10-yr storm Rainfall=5.32" Prepared by Hewlett-Packard Company Printed 5/5/2016 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 2 Summary for Subcatchment 1S: PreDevelopment I. Runoff = 11.51 cfs @ 12.95 hrs, Volume= 2.423 af, Depth> 0.74" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr storm Rainfall=5.32" Area (ac) CN Description 0.700 98 Water Surface, HSG C 34.400 48 Brush, Good, HSG B 4.300 65 Brush, Good, HSG C 39.400 51 Weighted Average 38.700 98.22% Pervious Area I ■ 0.700 1.78% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 72.6 2,911 0.0500 0.67 Lag/CN Method, ISubcatchment 1S: PreDevelopment Hydrograph 1 I I I I I I I I II I I I - J L L L J L _ J _L ®Runoff I I I I I I I I 1 12� [11.51 c 1, TO -24--hri0-lir storm; J L Rainfall-61.32 ' ___J____L___J-___L___J__ _L_ _J_ J____L_ __1____L___J__ _L_ 9='' Runoff Area=39.400 ac ___-1____1____J____L___J____L___J J L L J t- i ■ 6f' Runoff Vdlurrie-2.423 of % J1 i---J____L___ ___-;7_ RtnotfDepth?0.74- - j - L-+ I 1 3 6 - I I 1 1 I I I 1 J __FJQw_den h#2 9J'I.1__L_-- I�� nI�/��yl I I I 5J 3�1'eJVY�, i I -I 1- - -- 4_ _-T 72.6-r�i-in- --- ----+--- --L---�- 1 11 2- I 1 I 1 I1 11 - k - + 1� I I I I I I I I I I 1 1 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Time (hours) I I I Post-Development Stormwater Management Calculations Post-Development Drainage Map Virginia Runoff Removal Method Reports Post-Development HydroCAD Analysis a.r ar air err arr arr a ar ar r- / \\\ r � / / I 1 I ', ( I \ III / \ ----, \\ // \\I \ \\ 1\ I . \\ \ \ \\ \ \ � \ \ \ \\ / \ \ i � j / \ \ N �\ I \\-- /� I, -•,- / 1 \\\\ \ \\\\.\ \\\ '\ ---/ L I I I \ 1 \ \\\\ \ \ \ \ \\\\ I\-\ // . Q// ` J \I `\\\\\\\\ ` \ \ 1 \ __--/ / i I \ \\ . per( / 1 , \� \\ \ \ \ 1 \ /_� / (v n,- N N. 10. 4Ri t ,.F.,'X,.�.$ ff ffff ff'fffE ffff ff 1 - ' J * ) ......0,' ]eh I // / / \)\\\ \\ \\ \\I I ,I/ '\\`� j i .r,%.,1�„f f f f f f f j✓\l� \/ ,2-4._„, ��(/ / l l 1 \ \\ \\ J Imo" Q `` '�` "'4 '�'� I. t\p f f f f f f f f f f f f f l/ <"\/ y - �•,: `.\j.' `�/ � / LL/ \ I -\--\\ `l r� f f f f f f f ^ /�)\ (L \�� / \ r ---.- \ �t( ttt f f f f f f f f f f f f f ] VV i' \ : L i 41 (� L J ' al'XO 1 \`�' // — — -— ",:.)?), ` �. „+ f f f ff f f ff f f f f ff f f ff� j \ �.. 0 70X/t4 ~ / //V , ' �/ I. /_ \ N D f O f CJ O - el'->. "- --- '' ,.jun 17` x..^�J ,.!\ \ N• ' /' I'/ / \`. z 000, 6 10 * 0 • 11 0 i-A7 0 0/0 . 0/0•40.0--.‘icil\-_,,. 0\04 *\,y/A 0 2_\\\,r. --1 — -s o -0 - *---0- 1 ,Ii\-,-K 2,11 21,:,(i6i-40,, ,,K., \ V__ (,.` ,K1'. 0:4- . (-D 0 cp Il .j.\--\ zoa\‘‘r,,,, \./.-2\1 x-\/-i\„\ii.\.7? . - ,... s,--A7 y'''-- \--.‘T/ --"--7 * viltrio .-A-- * K\,-__(-\- 7:\::x ,L x y:,.).-_p , \ )_, 0 . - I: * pi L‘,r,\L \\ 00 0-c' **i:/ 04)'0 'zA / \\\ \\\ \\N\ 0'0/0 — •-' /i P ' % l 0/ • \ \ / \ \ •' 0/0/f0t-3/ j\g/:*/ -'7i *A 7/04 4.1./* 0/11( t;0 * - \ \ \ \ ' 0.-:Z/ ...N.,Y,r. 0 V:2 /1741 "K -0.'0*//ft,6:2__ _ . , \ \ \\ ' 2 /' , ,/' *r , */ ?,‘X-ev.'‘ ' lop \ \\ ', IlviAr V�� N. Jx F; , _.,0/ f qP: 40 \ \ \ -- 0 9 • , , , \ \ 11 / II \\ \/i�4/0 Y Jffi"'�/ 0(1 ? ' /�/ /yiv_.1'''//\ \ / \ \ - \ „... ,..1-_-\;„,\_ /,,, . . „.,6 .- , \ c-YexotK4/*// ci - ,_\-7(* <-x-- 0 )\, \ \ _ , ,__ \, - :,.; , A. 'A '‘ \ I -- ---, mr \ \\� ,� lqlf z,:) % �r' 1 T Tj ,!. .._(,_.7 ,Y1 J�\�'� x`17 \ \ \\ 1 ''^ `_ �'��, `ice Aj i l \ i ,i� x`70 4 \i , 1 --- - \\ - '-0- Ks4-- 4 .}.\vi 45H L[ Q , ' 0 0 0 0 ,'.-'• *' t'. *sK\0\0, x , , , , , , / Krs-_ ., )--/ik--4 1---A--4,10rcAA / - V s * Y'1 :'* 2 \ 0 \ - _ , // / / L / l , Ii • 0 0 *i t ` . . /1'/_ ,/ / / / / / /' 0 r \ \\ .... \ �� *lAP ��" flV `,� t"a Y v' '\ V� ,', L/// /� ,/ �/ NN, / v � y\, 1 \"a, /�, /,i / L/ /L ,, �,/ / ,. ,,I co cm _ * � \1 / , ,/ ,/ , / // � . / / II \ �j C� -j L. C'. 1 I \ -.:.:•:.-.,.-'. \ \ \ \ \ \ \ \ \\` O 1\ v' `V v� v�' // �/�� � jam/ i , '/ \`�\ \ \\\\ \\ \ I �/ \--- ; 6-\?,..,l vj 1 , yv' \\> �I \\\\\\\\II\I�� I • \II\I0 vs, \ \ 7 Mf r,, ?I \ I \\ \ \\ \\\� 1 * * • \ ` - I \ 1 \ \\ ZV ,� \\I�-� \ ;` .� * '� // moi/ � -0,n/• ��'/ 1 I III %.: - e;,' � ,/ - � * I \ -u . -- */ 0, cin U OOOQ — r-+ X10 ,U , / CA O • o n Oo -oo CA -oQ CD CD . . CD CD rte- r-l- r-+ Virginia Runoff Reduction Method New Development Worksheet-v2.8-June 2014 To be used w/2011 BMP Standards and Specifications Site Data Project Name:Castalia Pond Date:4/29/16 data input cells calculation cells constant values ----- ------ 1.Post-Development Project&Land Cover Information _ Constants Annual Rainfall(inches) _ Target Rainfall Event(inches) 1.00 Phosphorus EMC(mg/L) 0.26 Nitrogen EMC(mg/L) 1.86 _ Target Phosphorus Target Load(Ib/acre/yr) 0.41 Pj 0.90 --- Land Cover (acres) A soils B Soils C Soils D Soils Totals Forest/Open Space(acres)--undisturbed, . protected forest/open space or reforested land *.*4 - .87 37.04 Managed Turf(acres)--disturbed,graded for yards or other turf to be mowed/managed 0.00 0.21 0.65 0.00 0.86 Impervious Cover(acres) 0.00 0.14 1.32 0.001.46 - --.total 39.36 Rv Coefficients A soils B Soils C Soils D Soils Forest/Open Space 0.02 0.03 0.04 0.05 Managed Turf 0.15 0.20 0.22 0.25 Impervious Cover 0.95 0.95 0.95 0.95 Land Cover Summary Forest/Open Space Cover(acres) 37.04 Weighted Rv(forest) 0.03 _ ok Forest 94% Managed Turf Cover(acres) 0.86 Weighted Rv(turf) 0.22 %Managed Turf 2% Impervious Cover(acres) 1.46 Rv(impervious) 0.95 %Impervious Total Site Area(acres) 39.36 Site Rv 0,Q -- Post-Development Treatment Volume(acre-ft) 0.23 Post-Development Treatment Volume(cubic feet) 10,062 Post_Development Load(TP)(Ib/yr) 6.32 Post_Development Load(TN)(Ib/yr)I 45.231 Total Load(TP)Reduction Required(Ib/yr) -9.82 Site Results D.A.A D.A.B D.A.C D.A.D D.A.E AREA CHECK IMPERVIOUS COVER 0.00 0.00 0.00 0 cotilltrOK. IMPERVIOUS COVER TREATED 0.00 0.00 0.00 000 OK. TURF AREA 0.00 0.00 0.00 000 OK. __. TURF AREA TREATED 0.00 0.00 0.00 000 OK. AREA CHECK OK. OK. OK. OK. OK. Phosphorus _._ _ __ --_----_.....----- TOTAL TREATMENT VOLUME(cf) i TOTAL PHOSPHORUS LOAD REDUCTION REQUIRED(LBIYEAR) 11 RUNOFF REDUCTION(cf) PHOSPHORUS LOAD REDUCTION ACHIEVED(LBIYR) 0. ADJUSTED POST-DEVELOPMENT PHOSPHORUS LOAD(TP)(Ib/yr)J 5.32 REMAINING PHOSPHORUS LOAD REDUCTION(LBIYR)NEEDED CONGRATULATIONS!!YOU EXCEEDED THE TARGET REDUCTOR BY 9.8 LB/YEAR!I Nitrogen(for information purposes) TOTAL TREATMENT VOLUME(cf) RUNOFF REDUCTION(cf)iH NITROGEN LOAD REDUCTION ACHIEVED(LBIYR) ADJUSTED POST-DEVELOPMENT NITROGEN LOAD(TN)(Ib/yr) Virginia Runoff Reduction Method Worksheet Virginia Runoff Reduction Method New Development Worksheet-v2.8-June 2014 Site Data Summary Total Rainfall= 43 inches Site Land Cover Summary A Soils B Soils C Soils D Soils Total %of Total Forest(acres) 0.00 28.17 8.87 0.00 37.04 94.11 Turf(acres) 0.00 0.21 0.65 0.00 0.86 2.18 Impervious(acres) 0.00 0.14 1.32 0.00 1,46 3.71 39.36 100.00 Site Rv 0.07 Post Development Treatment Volume(ft3) 10062 Post Development TP Load(Ib/yr) 6.32 Post Development TN Load(Ib/yr) 45.23 Total TP Load Reduction Required(lb/yr) -9.82 Total Runoff Volume Reduction(ft3) 0 Total TP Load Reduction Achieved(Ib/yr) 0 Total TN Load Reduction Achieved(Ib/yr) 0.00 Adjusted Post Development TP Load(Ib/yr) 6.32 Remaining Phosphorous Load Reduction(Lb/yr)Required 0.00 Drainage Area Summary D.A.A D.A.B D.A.C D.A.D D.A.E Total Forest(acres) 0.00 0.00 0.00 0.00 0.00 0.00 Turf(acres) 0.00 0.00 0.00 0.00 0.00 0.00 Impervious(acres) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 Drainage Area Compliance Summary D.A.A D.A.B D.A.C D.A.D D.A.E Total TP Load Red.(Ib/yr) 0.00 0.00 0.00 0.00 0.00 0.00 TN Load Red.(Ib/yr) 0.00 0.00 0.00 0.00 0.00 0.00 Summary Print Virginia Runoff Reduction Method Worksheet Channel and Flood Protection Weighted CN 1-year 2-year storm 10-year storm Adjusted CN storm Adjusted Adjusted r CN CN Target Rainfall Event(in) 0.00 0.00 0.00 D.A.A CN 0 100 100 100 D.A.B CN 0 100 100 100 D.A.C CN 0 100 100 100 ar D.A.D CN 0 100 100 100 D.A.E CN 0 100 100 100 a -ar a.e r are a ar .m. Summary Print 1 S \ \ / PostDevIopment /2 \1\\::)Pond Subcat Reach 'on. MI Drainage Diagram for CastaliaPostDev Prepared by Hewlett-Packard Company, Printed 5/5/2016 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC CastaliaPostDev Type 1124-hr 1-yr storm Rainfall=2.90" Prepared by Hewlett-Packard Company Printed 5/5/2016 HydroCAD®9.10 sin 07054 ©2011 HydroCAD Software Solutions LLC Page 2 Summary for Subcatchment 1 S: PostDevelopment Runoff = 0.70 cfs @ 13.57 hrs, Volume= 0.297 af, Depth> 0.09" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 1-yr storm Rainfall=2.90" Area (ac) CN Description 2.160 98 Water Surface, HSG C 33.150 48 Brush, Good, HSG B 3.150 65 Brush, Good, HSG C 0.860 74 Pasture/grassland/range, Good, HSG C 39.320 53 Weighted Average 37.160 94.51% Pervious Area 2.160 5.49% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 69.0 2,911 0.0500 0.70 Lag/CN Method, Summary for Pond 2P: Pond Inflow Area = 39.320 ac, 5.49% Impervious, Inflow Depth > 0.09" for 1-yr storm event Inflow = 0.70 cfs @ 13.57 hrs, Volume= 0.297 af Outflow = 0.11 cfs @ 20.00 hrs, Volume= 0.034 af, Atten= 84%, Lag= 385.8 min Primary = 0.11 cfs @ 20.00 hrs, Volume= 0.034 of Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 521.17' @ 20.00 hrs Surf.Area= 1.562 ac Storage= 0.263 af Plug-Flow detention time= 277.1 min calculated for 0.034 af (11% of inflow) Center-of-Mass det. time= 104.5 min ( 1,056.6 - 952.2 ) Volume Invert Avail.Storage Storage Description #1 521.00' 6.120 of Custom Stage Data(Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (acres) (acre-feet) (acre-feet) 521.00 1.500 0.000 0.000 524.00 2.580 6.120 6.120 Device Routing Invert Outlet Devices #1 Primary 517.20' 30.0" Round Culvert L= 50.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet/Outlet Invert= 517.20'/516.80' S= 0.0080 '/' Cc= 0.900 n= 0.012 Concrete pipe, finished #2 Device 1 521.25' 42.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 521.00' 0.5' long Sharp-Crested Rectangular Weir 2 End Contraction(s) Castel i a Post Dev Type 1124-hr 1-yr storm Rainfall=2.90" Prepared by Hewlett-Packard Company Printed 5/5/2016 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Page 3 Primary OutFlow Max=0.11 cfs @ 20.00 hrs HW=521.17' (Free Discharge) L =Culvert (Passes 0.11 cfs of 38.99 cfs potential flow) 2=Orifice/Grate ( Controls 0.00 cfs) 3=Sharp-Crested Rectangular Weir (Weir Controls 0.11 cfs @ 1.35 fps) CastaliaPostDev Type 1124-hr 10-yr storm Rainfall=5.32" Prepared by Hewlett-Packard Company Printed 5/5/2016 HydroCAD®9.10 sin 07054 ©2011 HydroCAD Software Solutions LLC Pane 4 Summary for Subcatchment 1S: PostDevelopment Runoff = 14.46 cfs @ 12.85 hrs, Volume= 2.796 af, Depth> 0.85" Runoff by SCS TR-20 method, UH=SCS, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Type II 24-hr 10-yr storm Rainfall=5.32" Area (ac) CN Description 2.160 98 Water Surface, HSG C 33.150 48 Brush, Good, HSG B 3.150 65 Brush, Good, HSG C 0.860 74 Pasture/grassland/range, Good, HSG C 39.320 53 Weighted Average 37.160 94.51% Pervious Area 2.160 5.49% Impervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 69.0 2,911 0.0500 0.70 Lag/CN Method, Summary for Pond 2P: Pond Inflow Area = 39.320 ac, 5.49% Impervious, Inflow Depth > 0.85" for 10-yr storm event Inflow = 14.46 cfs @ 12.85 hrs, Volume= 2.796 of Outflow = 7.50 cfs @ 13.72 hrs, Volume= 2.223 af, Atten=48%, Lag= 51.7 min Primary = 7.50 cfs @ 13.72 hrs, Volume= 2.223 of Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs Peak Elev= 521.58' @ 13.72 hrs Surf.Area= 1.710 ac Storage= 0.937 of Plug-Flow detention time= 111.3 min calculated for 2.223 of (79%of inflow) Center-of-Mass det. time= 57.4 min ( 933.2 - 875.8 ) Volume Invert Avail.Storage Storage Description #1 521.00' 6.120 of Custom Stage Data(Prismatic) Listed below (Recalc) Elevation Surf.Area Inc.Store Cum.Store (feet) (acres) (acre-feet) (acre-feet) 521.00 1.500 0.000 0.000 524.00 2.580 6.120 6.120 Device Routing Invert Outlet Devices #1 Primary 517.20' 30.0" Round Culvert L= 50.0' RCP, sq.cut end projecting, Ke= 0.500 Inlet/Outlet Invert= 517.20'/516.80' S= 0.0080 7' Cc= 0.900 n= 0.012 Concrete pipe, finished #2 Device 1 521.25' 42.0" Horiz. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 521.00' 0.5' long Sharp-Crested Rectangular Weir 2 End Contraction(s) CastaliaPostDev Type 1124-hr 10-yr storm Rainfall=5.32" Prepared by Hewlett-Packard Company Printed 5/5/2016 HydroCAD®9.10 s/n 07054 ©2011 HydroCAD Software Solutions LLC Pacie 5 Primary OutFlow Max=7.49 cfs @ 13.72 hrs HW=521.58' (Free Discharge) L1=Culvert (Passes 7.49 cfs of 41.84 cfs potential flow) f2=Orifice/Grate (Weir Controls 6.93 cfs @ 1.89 fps) 3=Sharp-Crested Rectangular Weir (Weir Controls 0.56 cfs @ 2.50 fps) Independent Reports Excerpt from NRCS Soils Report NOAA Precipitation Report Custom Soil Resource Report Soil Map k 733100 733400 733700 734000 734300 739600 734900 38°4'41"N g. 38°4'41"N . rsi- ,ate t > €, ,-r . 0 1 A O• '' i{ . }1 i�rA a w ,„ ael }i g t fit . r , v er 8 G v 8 N as a sr g 38°3'21"N V 38°3'21"N 733400 733700 734000 734300 734600 734900 3 ,,,� Map Scale:1:11,900 if Printed on A porha t(8.5"x 11")sflee. ^ m N 0 150 300 600 meters 900 0 500 1000 2000 3000 //" Map projectia c Web Mercator Comer coordinates:WGS84 Edge tks:UTM Zone 17N WGS84 8 ma Custom Soil Resource Report Map Unit Legend iiAlbemarle County,Virginia(VA003) Map Unit Symbol Map Unit Name Acres in AOI Percent of AOI 23B Davidson clay loam,2 to 7 11.0 2.2% iiiipercent slopes 23C Davidson clay loam,7 to 15 3.0 0.6% percent slopes 25B Dyke silt loam,2 to 7 percent 53.0 10.4% no slopes 25C Dyke silt loam,7 to 15 percent 0.8 0.1% slopes - 26C3 Dyke clay loam,7 to 15 percent 6.7 1.3% slopes,severely eroded 57B Mount Lucas silt loam,2 to 7 11.1 2.2% percent slopes Mb 58B Myersville silt loam,2 to 7 2.7 0.5% percent slopes ig' 58D Myersville silt loam,15 to 25 5.0 1.0% percent slopes 59C Myersville very stony silt loam,7 2.1 0.4% r to 15 percent slopes 59D Myersville very stony silt loam, 24.4 4.8% 15 to 25 percent slopes g 59E Myersville very stony silt loam, 80.6 15.8% i25 to 45 percent slopes 71B Rabun clay loam,2 to 7 percent 15.1 3.0% slopes 71C Rabun clay loam,7 to 15 percent 54.4 10.7% slopes 71D Rabun clay loam,15 to 25 60.8 11.9% . percent slopes di 71E Rabun clay loam,25 to 45 4.0 0.8% percent slopes 72C3 Rabun clay,7 to 15 percent 22.5 4.4% slopes,severely eroded a 72D3 Rabun clay,15 to 25 percent 6.1 1.2% slopes,severely eroded 73C Rabun very stony clay loam,7 to 8.0 1.6% w 15 percent slopes 73D Rabun very stony clay loam, 15 26.1 5.1% to 25 percent slopes 73E Rabun very stony clay loam,25 35.5 7.0% AM to 45 percent slopes 79B Starr silt loam,2 to 7 percent 19.8 3.9% slopes a 89B Unison silt loam,2 to 7 percent 8.9 1.7% slopes a 10 a Custom Soil Resource Report Albemarle County,Virginia(VA003) Map Unit Symbol Map Unit Name Acres in AOI Percent of AO1 89C Unison silt loam,7 to 15 percent 1.3 0.2% slopes 90C Unison very stony silt loam,7 to 47.6 9.3% 15 percent slopes Totals for Area of Interest 510.4 100.0% 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 MIN 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 A1110 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 41.11 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 401 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 landform segments that have similar use and management requirements. The delineation of such segments on the map provides sufficient information for the development of resource plans. If Aift intensive use of small areas is planned, however, onsite investigation is needed to define and locate the soils and miscellaneous areas. An identifying symbol precedes the map unit name in the map unit descriptions. Each description includes general facts about the unit and gives important soil properties and qualities. a 11 a NOAA Atlas 14,Volume 2, Version 3 �� A Location name: Keswick,Virginia, US* iu Latitude:38.0559°, Longitude: -78.3190° .,ffwar-hk' %. I Elevation:468 ft* : ° 0'3 'source:Google Maps 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) I Duration 1 2 5 10 2550 i 100 200 500 _ 1000 5-min j 0.350 0.415 0.4860.549 0.619 0.674 i 0.725 0.773 0.831 0.879 • (0.315-0.388)1(0.375-0.460) (0.438-0.538(0.494-0.607) (0.554-0.682) (0.601.0.742)1(0.643-0.798) (0.681-0.851) (0.724.0.918) (0.759-0.973) 10-min 0.559 0.664 0.779 0.878 0.986 1.07 1.15 1.23 ( 1.31 1.38 (0.504-0.619) (0.600-0.736) (0.702-0.861 0 790-0.971 I i) ���( )� (0.883-1.09)I (0.957-1.18) (1.02-1.27) � (1.08-1.35) iE(1.15-1.45) (1.20.1.53) 15-min 0.698 0.835 0.985 1.11 1.25 i 1.36 1.46 i 1.55 1.65 1.74 (0.629-0.774) (0.755-0.925) (0.888-1.09) (1.00-1.23) (1.12-1.38) (1.21-1.50) (1.29-1.60) (1.36-1.70) (1.44-1.83) (1.50-1.92) 30-min I 0.958 1.15 1.40 1.61 1.85 2.05 2.23 2.41 2.63 2.81 _J (0.863-1.06) (1.04-1.28) (1.26-1.55)] (1.45-1.78) L(1.66-2.04) (1.82-2.25) (1.98-2.46) (2.12-2.65) 2.29-2.91 ( (2.43-3.12) 1.45 1.79 2.10 2.46 I 2.77 , 3.07 3.38 3.78 ( 4.11 60-min ! 1.19 (1.08-1.32) (1.31.1.60) (1.62-1.99) (1.89-2.32) (2.21.2.72)i (2.47.3.05 2.72-3-38 C ( ) 1 (2.97-3.72) 11,(3.29-4.17) (3.55-4.55) 2-hr 1.43 1.74 2.16 2.55 3.04 I 3.45 3.88 4.32 4.93 5.44 (1.28-1.62) (1.54-1.96) , (1.92-2.44) JC(2.26-2.87) [p.68-3.41) (3.03-3.88) (3.38-4.34) (3.73-4.83) (4.21-5.52 J (4.60-6.12) 3-hr 1.56 1.89 2.35 2.77 3.31 3.77 4.23 4.72 5.38 1 5.96 (1.38-1.78) (167-2.15) L(2.07-2.68) (2.44-3.15) (2.89-3.75) (3.27-4.26) (3.65-4.79) (4.04-5.34) (4.55-6.11) (4.99-6.76 6-hr 1.97 2.38 2.94 3.48 4.18 4.80 5.44 6.14 7.12 7.99 1.75-2.25 � ( ) I^(2.10-2.71) (2.59-3.36) (3.05-3.96)j[3.64-4.75) (4.15-5.44) 1 (4.67-6.17) (5.20-6.96) (5.95-8.08) (6.59-9.08) I 12-hr 2.46 2.96 3.68 r 4.37 5.31 6.16 ! I (2.18-2.82) (2.62-3.39) (3.24-4.21 L € 7.08 8.08 9.54 10.9 ) (3.83-4.99) (4.62-6.05) 1 (5.31-7.00) (6.03-8.03) (6.79-9.15) ! (7.87-10.8) (8.82-12.3) 24-hr 2.90 3.52 4.49 5.32 6.54 I 7.58 8.74 10.0 11.9 13.5 (2.61-3.27) (3.16-3.96) (4.02-5.06) (4.75-5.97) (5.80-7.33) (6.68-8.48) i (7.63-9.76) (8.65-11.2) (10.1-13.3) L(11.4-15.1) 3.42 4.14 5.27 6.19 7.54 8.66 9.88 11.2 13.1 I 14.8 2-day 3 L 9I �( _OS 3.82) (3.74.4.63) (4.75-5.88) 5.56-6.90) � (6.73-8.38) (7.68-9.62).,.) (8.70-11.0) (9.80-12.5) (1L3.14.7) (12.6-16.5) 3�ay 3.64 4.41 5.60 1 6.58 8.00 9.19 10.5 11.9 13.9 15.6 (3.30-4.04)J (4.00-4.89) (5.07-6.21) (5.95-7.29) (7.19-8.85) : (8.21-10.2) (9.30-11.6) 10.5-13.1 ...1 ( ) (12.1-15.4) (13.4-17.3) 4-day3.86 4.67 5.93 6.97 8.47 9.73 11.1 12.6 14.7 16.5 (3.52-4.26) (4.26-5.15) (5.40-6.54) (6.33-7.67) , (7.66-9.31) (8.75-10.7) 1 (9.90-12.2) (11.1-13.8) (12.9-16.2) (14.3-18.2) play 4.48 5.39 6.74 7.85 9.44 10.8 I 12.2 1 13.7 15.9 17.7 (4.10.4.91) _(4.94-5_91) (6.17-7.39) (7.16-8.60) (8.57-10.3) (9.72-11.8) (10.9-13.3) (12.2-15.0) (14.0-17.5) (15.4-19.5) 10 day 5.09 6.10 7.53 8.70 10.3 I 11.7 13.1 14.6 16.7 18.5 (4.68-5.53)(5.62-6.63) (6.93-8.18) (7.98-9.44) (9.45-11.2) i (10.6-12.7) 1 (11.9-14.2) (13.1-15.9) (14.9-18.2) (16.3-20.2) 20 day 6.718.00 9.66 I 11.0 12.8 14.2 15.6 17.0 f 19.0 20.5 (6.26-7.21)_ (747-8.59) (9.01-10.4) (10.2-11.8) (11.8-13.7) 1 (13.1-15.2) (14.3-16.7) (15.6-18.3) i (17.3-20.5) (18.6-22.2), [30-clay8.23 9.76 11.5 12.9 14.7 16.0 17.3 18.6 20.3 21.6 1 (7.73-8.79) (9.16-10.4) (10.8-12.3) (12.1-13.8) (13.7-15.6 i (14.9-17.1) (16.1-18.5) (17.2-19.9) (18.7-21.7)(19.8-23.2) 10.3 12.2 14.2 15.8 17.7 1 19.2 20.6 22.0 23.7 25.0 145-day (g 70-10.9) (11.5-12.9) (13.4-15.1) (14.8-16.7) (16.7-18.8) ! (18.0-20.3) (19.3-21.9) (20.5-23.3) (22.0-25.2) (23.1-26.7) L J - __ -_� _ L._ _ 60-day , 12.1 14.2 16.4 I 18.1 20.2 21.7 23.2 24.6 'I 26.4 27.6 (11.4-12.8) (13.5-15.1) L(15.5-17.4) ( (17.1-19.1) (19.0-21.3) (20.4-23.0) .I (21.8-24.5) (23.0-26.0) (24.6-28.0) I (25.7-29.4)J 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)w ill 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(PAP)estimates and may be higher than currently valid PlvPvalues. Please refer to NOAA Atlas 14 document for more information. k' Back to Top____ PF graphical