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PE-1885 PRAIRIE ORCHARD DRAINAGE REVIEW SUBMITAL 1 (2) i~ - i • ~ E RMMqVpmnoo O~ ~uanOa for 'k aiRT-* w1mgm AUG ~ bpWe Orehards +~~~MUd I SFDK0.NE COUNTY EiVGIHEER MM SkMMN3 ki r~~ ~ ~I i DRAINAGE REPORT for - Prairie C)rchard , Spokane Cvunty,llVashingtorr Augustr 2002 CLc JOB #S020160 Fpla t~n improvements shown in this set af plansar~d calc~u'lativns confm~-m ta the e editia~ns of the 5pnkane Cfluroty Star~darcis for Ro~,d and Sevver tic~n and the Spoxane Cvurrty Craidelines for 5torm Water Masr~age~ner~t, ~►11 er~iations have t~e~:n appr'o►~ed ay the Spokane County Engir~eer. 1 apprave ns (calculations) fvr construGtion. This repart has been prepared by #he staff af CLC associates, Inc. under the directivn of the undersigned prvfessivnal engineer whase seaE and signature appear herevn. ~ RA'. W'4S ~ C/tr'riGs. David Randall, P.E. _I PR►41RfE C)RCHARD URAINA GE NA14RA TlVE G€NERAL This project is ora the Prairie Orchard preE[rninany plat. The site has an exisfing residential hvme ' orr 1at 7. The cemainder of the site is vacant with field gras5 as fhe predaminant land coaer and vegetation. The prvject site is Iocated an the narth side of 24t~' Avenue between Adams Road and Pragress Rvad in Spvkane County, Washingtan. PURPUSE The purpose of this repart is ta determine the extent of sfiam-r drainage facilities which will be required tv dispose of the increase in sfarmwater runvff created by the development of ihe PraiNe Orchard pfat. The storrrr drainage #acilities on this praject have been designed ta dispose of runoff frvrn a ten-year design storm, as required by the Spokane County Guidelrnes fvr Sformwater Marragement, {GSM}. Calcufaticrns are afs❑ incfuded #a illustrate the exfen# of cvntainment far the 10- and 50-year starm events. This develapmen# is within the Aquifer 5ensitive Area of Spvkane Cvunty and is therefare subject ta `208' requirements. For this project, the 10- and 50-year intensity curves from the Spokane, IVledical Lake, Reardan, Cheney, and Rockford areas were used, as well as the SC5 isa-pluvial rainfall curves ANALYSlS M'FTHVDl7LOGY Fer fhe GSM, the Eiational Method, which is recommended for basins Iess than ten acre$ in , size, was used to deterrnine the pEak discharges and runoff volumes for ali onsite basins. PRvJEcr DE$CRrPrroN The Prairie archard plat is a 2.34-acre develaprnen# of 7 single farniGy residential 9vts. Prairie Orchard is located in 5ectian 26, T. 25N., R. 44 E., W.M. within Spafcane Counry, Washington. - TC7POGRAPffY The site generalPy drains fo the southeasf at slapes ranging frvm 0 to 15 percent The Northwest corner of the site is extreme9y fla# and genera[iy drains ta fhe rtorth-northwesf at siapes under 2 percent. The runvff frnm this narthwesterly po6on of th€ site wifl be canveyed tfl a proposed pond on Lot 3 of the Prairie +archard final plat. The runaff fram the remainder of the prvject wi9l be conveyed to a proposed pand on'Lot 7 of the F'rairie Orchard final plat. ' SQlLS ' As can be seen fram the accomparrying sails map frerm the Spokane Caunty 5oils Survey as - periarrned by tlhe Soil Cvnserva4ian SerVice (SCS), thB 5lt2 CiJnSl5t5 of 5t31I5 WPth thO CIaSS B type. The sal type is described as foffQws: CLC Assaciates, Ine. 1 Prairie Orchard Gm8 - Garrisvn very gravelly laam, 0 fa 8 percent slvpes. Saifs within this type are , sornewhat excessively drained soiis formed ira grave1y glacial outwash rnateriaf from a variety af ignevus rQCk. Surface runvff is medium, and sgil halds Eess then 5 inches of wafier that plants ' can use. GSM indicats lhis lv be a Sail Graup Type B and pre-approVecl for drywell ins#aflativn. - Dl2A1N.4GE N.4F2RA TlVE C]ffsrte Based upon the general geographic tendencies surrounding this site, no affsite flows are expected. OnSite AN runofF within the deainage basin will be collected arrd treafed using fhe `208' runaff method as described in the G5M Frorrf high points in the proposed road improvements, designed inlet , facations and the assumed fat grading, the prcapased Prairie Orchard plat was d3vided intv fvve , basins (1, 2, 3, 4, and 5). Basira information is prav6ded ira Tabie 1. The contributing rumafF froon the impervious street area is designed to flow ta downstream porrds by placement ot curb pnlets, which divert runoff into the grassy `208' ponds for treatment. The runoff fcom each basin is directed to pands withm the pfat, with the exceptiern vf Basin 4. Developing Qasin 4 reduces the runoff caefFiCient frcam 0.32 ta 0.23. TU- run@ fr~MIM MEN~ 11 y~06^) 0 be dt inu a piR "ge_aaus ~.filhc de' reas - n ruravfj. The drainage basrns and pands are shvwn vrr the basin map at the back af this repart. Tab1e Rfo. I - RunofF Cnetficient 5umrotary Tut~! Area ~'atUrnperuiaus Run~rff ~veffcient ' ~asin ~SFlAC~ ►4rea ~SFj 1 I 34,206l0.79 ~ 16,950 I .52 2 ~ 19,49810.45 7,500-1 .44 ' 3 ~ 31,038110.71 6,200 ~ I .3e - 4 ~ 20,751/0.48 ~ 2,200 .23 i ~ 6,45710.15 I 6,457.J ~ ,90 Combined 2 and 5 ~ 22,51 010.52-) I 10,51 LA-, ~ .50 ' Cambined 3and 5 I 34,483!0.7 ~ 9,645 ~ .35 { Tatal fmpenrious 1~rea included paved roadway' ea, 3,400 s.f per r i, and 600 s.f. per dnVeway, Pand, and sidewalk areas. B °C" {impenrious area) = .90 `C° (landscape area) _ .15 CLC Associates, 1nc. 2 . Prairie Qrchard ~ _ . Drainage Ca1culaffons Sur,nmary I~ Bowstring caIculalions have been incfuded for individual hasins to determFne the extent of storm drainage facilities required fvr the 1 D-year storm event. Weighted "C" Ruraoff Cvefficients were calcufated far each basin of Iess than 10 aGres as required by the SpvEcane County +Guidefrrres fnr 5tvrmwater Management. Table 1 prouides the basin size, total irnpervious areas, and runaffi coefficien4s. Pravided storage vvlumes shvwn in the bouvstring calculativns were d'eterrnined using the pond bottam areas, 3:9 side sfopes and a ane-foot depth. '208' CajC1/IatlO1)S The '208' starage volume for each basin was designed to adequafeEy contain the runoff created by the first half-inch of rainfiall upan the s#reet impervious areas within the basin rt serves, `PM - p 't~h si.d;e-Xt a galarme . bt summarizes he reauiremen s and ra esigns vf #he pvnds by basirr. kql Table 2 - `2O8` Area and Volume Summary `2E18' M(S ' ~'ancfE~asinl lm°20~8' llvlurne Pe~uidecl Rnn{~5Pro►~ided ~~CF~ F.~ 3,51A 5,120 213 I 284 ~ 340 ~ 83.8 1JE ~ 12,000 500 583 ~ 750 ~ 119.7 2,5lC 6,220 259 ~ 277 ~ 340 I 74 "=208' Impervivus area cansists af street area and driveways at fiOQSF per cirivewaY- Tataf 5tarrnwater Stvrage Calcufafions In additian ta the `208' storage requirements, tYae tvtal stvrmwater s#orage for the 10-year design starm was aIso considered. Eaeh of the pands in Prairie archard will have the capacity to cvn#ain the required volume at the 16-year design storm. In additivn, the 50-year desigrr storm was alsv examiraed tv verify that the 50-year everrt caufd be stored in the pand as designed. This infarmativra is summadzed in Table 3. CLC Associates, Inc. 3 Prairie Orchard Table 3 - StQrmwater Storaqe Valume Summary _ ~ _ '~U-y~ar ana ~~~yea~ Stvra~~ 1lofum~ St~m~ar~y~ - - II 4Ad - ' ~~~`I4-year Volurri~ 5Q-Y~arI~vlume 'P~in~i plalume # vf aryvv~lls - Basin Pcanci ~~quire~l ~~,~F} ~~quired •~CF} ~rauidME ~~CF} Req~uiret~ 'k B 224 466 930 1 clouble ~ 2 and 5 C 251 412 451 ~ 3 and 5 A 64 231 466 1 dvuble ~ 'Volume Provided is based on 3.1 side slapes and 1' depth; {P'and Area}(fl + (Perimeter){1.5 ft2} INLET CALCULATlQNS Inlet calcufativns were performed in general accnrdance GSM and W.S.D.O.T. Hydraulic ~ Manual ta determine the runafF received and by-pass flows for each inlef. By-pass fiows calculated for the inEe#s on contmuvus grades were adcled to ihe foflowing downqrac#e i analysis shvws that pond `R' requires ❑ne 5' type 1 curb inlet, and ❑ne y eI curb inlet. Pond `C' requires two 6' type curb inlets anrf Pand `6' requkres one 4° e cur inlet, wnich is under sump conditians. FLC7DDEfl W1DTH CALCULATlONS Ftvvded width calculatiQns were performed in general accordance with GSM for pond `A' for - bath the 1 C]-year artd 50-year design storm. The pond is in aGcordance with GSiUI. CONCLUSION Rs demonstrated by the cafcufations and body af #his repart, the starm drainage facilities provided in this design will adequateEy remvve from the streets, stare and dispase af the stormwater fram the site far the 10-year design storm as required by 5pokane County. ° Galculatron warksheets for the 50-year stvrm event have been pr+avided to eValuate fhe perfQrmaRCe of the designed draEnage facilities. Additionally, the rerpuired `208' treatment area is prvvided for the runoff from the street impervivus areas. CLC Assvciates, Inc. 4 PrarTie Orchard I I I I APPENDIX - MAPa Vicinsty Map - Soils Map - DEII''ELQPED BOWSTRING CALCULATIC31V5 - 10-Year Design Storm i 50-Year Starm Event Inlet CalGUiativns Flvoded Width Calculations - - BASIN MAP `-~~--T- m Narrhwasr Map 5ervrea C IINS ~ Q~ H K COL'LIkS HOR~ ~ kERCLE~ 9 CF ~~l w CO ~l.IN wlcf E9T LN $ = H6UK ` 1 C Ll1Ns VERC R ~p~ p ~ m VERCCEA R~ i V~RCLER AG ~ i 4Eii • Iy VFRC W lE LE YIAGWIA x ~ YIR Sy P91 ,7,7i~~lAOUAA ~ 1L$ IA- N VIRGINIA 6Tl pL1WNGINIA A ' Q R f QSQC 5YH ° ~ ~ ' I x p p R ~ Wi ~001 45~f L • Wcd.~WM W(1~~L YM ~'o' Vi. en AROw agn a 8 roaaorr NOANOw W ~ t ow e -a owaL IF, a IDNI 'LO A R )AD 0 i Cu~kAL~➢ ~ e ^ati C A : A ~ C INTOte m C6tN'fON ~ a ~ - ~ S LINT01! ; I~3C m %ELLlF n m M~~ Y~. ~a ~ ~ m~ r m a ~ ~ =LIEi0i• McCABE hicCABE m rxc cA a } ~ = m m ~ ~ ~ ~ ~ I~ n ~ z f~ s4 x 6LAKE RO BL 7KF BLAKE RDAO ~ AVAtON PU ~ ~ flLt ICE AO I~ ^m.m•°~ ~ ~ vra~r {P~c y A LE17H~ C~ EATH LN ~ i I ~'1V $,~C fO S T' A ItlA~HC1i MAYXE / y. ~ ANC i s p µAuER.. ~ IAAIRER RQ ferl qp N& !R g7 µR1.1E9 S ROdp T."'TL ~A S F~ flAYiS Rp DaYIS wr ~ il~x EVEf GREfNR❑ ~.c?"'~e-_ l ~ EVFRGREEH ROAD m< ~'~i~ ud''; ~Y - e sv tv ~ ,ws , . r :v~-• ~ ~ c - w +0 ~ L vA I S~ 88LFViR ~ x ~ 0`~ye~ S~LNAR I~ E BO CA 140 BAXIT lQ0 ~ @ v Cr gA rygryci HAHNEN 8AN EH RD LN yry " BOLI AFl ~ 0RP NgN ~ R$ E BARLP PAwX u Ra SANN[N BANHEN ExAI! 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SClHiUBY CT P ~~e CFNTlIR En CffRU r NAY 'E TURT 'i - m ~ 5lJLLIVAN q ~ ~ x~ ~ SULLIYkN ORaAbU a ° d ~6 enekrL °ciowffeeLx I ~ FroME cr ~ ~ ro I V s k~ O y~ ~ ~ d ~ ~d~A9,p11 ^ n S'~~~ NE ~ xm ' 3~~'~~ ~ ~ O" N Sl'Q~d3~{Y~q=.p ,a ulK A+.Ob . ^by a .moreir+M~_ 9QHE~ L$ Ytl 'pT rSC~ A e3T~A ~ .y~ ~ •o e [ao Lp T . v 16V ,yty~ ~ a ~-~i~ ~+oAr~ s E ~ ~ s Cae7HERY Pp ~,a " N pA'dp qC 5' l# w ~'r ~y BEtEEFlLU a G ~ COxKLtN RO ElN COk1(LIH LLWAV ~ a a ra r~m i ~ ' ~ ~cAAqlxp `~FSr ~ [~~a HOLLYWGOLLX ~ 164 z ' 0 1dR0 ARNIN 8XA~SS 5HFA1R6C& ~ "..."CFTn ~anr a ~ PIGCEtlO~lN y. . ,a ~ ~ ~ ~ 17 aalA 9 r^ ~ a~ STEEN RD ~ BTEEHLN x 1 fi8 ~ ~ ` m ~ r ~ , a~. €ae r ~ ~ y ~~sev Y as CXAFNAN ~"''w~-`~'`_~~ ~ y~s r.~ s~~ ~v~R6~% 0dP"` + I `mw .w w.n .r r. w-~ r rrw r.. w, - 172, ~ R 45 E A ~C ■ C, s A k aR BE€L ~ 4I = BELL A.RC. [ H 6 VkAERLH 990 v w TaCr nLBY SUpN R L S NIR Yf! Jtw T-Ci I R] Q7 .4 r~ C77 ft7 0* $ ~ -F+ 0o Ea7 CJ7 i SOILS MAP ' Sheet 76 l7F 5CS 5C)fL SURVEY OF SP(3KANE CC7lJN7Y I BOWSTRING CALCULATIONS. I - - - - ' - - - - ' PEAK FLQW CALCULATInN PRt]JECT F?r~irie~[7rcli rd;}'~' BOWSTRING METHO❑ PROJECT, Prairie flrchard 10-Y@ar DBSign 5tOCITI ❑ETENTIC]N BA51hf DE51GN BASIN 1 ' DE5IGNERSKih~:~~r,::_ ' BASIN 1, C}ATE• 14-Rug-02 ~ Tot. ArBB i g~ ~;34 206~ 5F 0.79 ACres Imp. Area ~;i,~~1'S;954~ 5F `~ime Increment {rnm} 5 C ~ ~ 0.52 Lawns 0.15 Time of Conc (min) 549 Imp. 0.90 Dutflow(cfs) ❑esign Year Flow 10 CASE 1 Area (aeres) 079 Imperviaus Area (sq ft) 16950 ft. ❑verland Flow 'C' Factcar 0.52 Area ' C 0 410 Ct "20$" Imp Area , :12;000; L = 60 ft n= =3''~` ;~r0:40a Time Time Inc lntens. Q aevel, Vflf In Vol Out Storage S = a:;~,4,022t]j ' (mm) [sec) {inlhr) ccfs} (cu ft) {cu ft) [cu ft] 5.49 329 3 05 1 25 552 329 223 Tc = 3.17 min., by Equatiorr 3-2 of Guidefines 5 300 3.18 130 524 300 224 C== -''CWft, aitch tlow 10 600 224 092 653 600 53 95 90[} 1.77 073 734 900 -168 Z1 = 50.01 For ZZ 20 1240 1 45 059 779 1200 -421 Z2 _ V~ 5~0" Type 6=1.i] 25 15{}0 1.21 050 799 1500 -701 fl.~1 B1 Roliad = 3.5 3(} 18i7Q 1 04 ❑ 43 815 1800 -985 S= .L1~~9O 35 2100 091 0.37 825 21[]0 -1275 40 2400 0.82 034 844 2400 -1556 d= ft. Flow Width 6.6 ft. 45 2700 074 030 852 2700 -1848 , 50 3000 0,68 0.28 857 30[}0 -2133 55 3300 4 64 026 894 33(}0 -2406 A R Q Tc Tc totaf I Qc CO 3600 061 025 928 3804 -2572 0.87 0.07 1.25 2.31 5.49 3,05 1.25 65 3900 (}.50 025 988 3900 -2914 TQ 42[}0 0 58 024 1024 4204 -3175 Qpeak for Gase 1 = 1.25 c#s 75 4500 0 56 0 23 1058 4500 -3442 80 4804 0.53 0.22 1[]66 4800 -3734 85 5100 052 021 1110 5100 -3990 90 540[} 050 020 1129 5400 -4271 GASE 2 95 5700 0.49 4.20 1167 5700 -4533 100 6[]00 0.48 020 1202 6000 -1798 Case 2assurnes a Time af Cancentration less than 5 minutes so that the peak flow =.90(3.18)(Imp, Area) = 1.11 cfs "208"7RERTMENI" REQLIIREMENTS Minimum "208" Volume Required 500 cu ft Pravided Treatment Vvlume 7'~ ft 5a, the Peak law for the Basin is the greatar af the two ffows. 1.25 cfs 0 RYWEL'L REQIJIREMENTS -1D YEAR DESIGN ST[]RM hAinimum Storage Reqwred by Bowstring 224 cu fk PrpVided Storage Volume Ifa~,-1-111``~Y .s~~'.93Qtcu ft Number and Type of Orywells Specified 0 5ingia 1 Dau61e ~ i - , - , - - - - - ~ - ~ ~ - - PEAK FLOW CALCULATEQN PRO.fECT.,PrliBQWSTRING METHQD PRC7JECT• Pra3rie Drchard ~ ~ ~ 10-Year Design 5tarm DETENTIOIV BAS1N f}ESIGN BASIN, 2 DESIGNER,SKM BASI N ,;r2~ DATE 14-Aug-02 Tat. larea ~~~'V:" F£9S~' 4 45 Acres ~ Imp. Area i,~°"`r7;500~5F Time Increment (min) 5 C= 044 LawnS 0 15 Time pf Conc (min) 5.53 Imp 090 Outflaw (cfs) ° ':;~-13z Design Year Flow ' 10 CASE 1 Area {scres} 0 45 impervious Area (sq ft) 7500 8aIfit. Overland Flow 'C' Factor 0 44 Area ' C 019fi ' Cf = °208" Imp. Area yff L= 180 n n= Time Time Inc Intens. Q Devel Vol !n Vaf Out 5torage S = (min) (sec) (inlhr) (cfs) ;cu ft) (cu ft) {cu ft) 563 338 3.42 059 268 101 167 Tc = 5 29 rnin , by Equation 3-2 of Guidelines 5 300 3.18 62 251 90 361 5Mft Gutfer flaw 3 14 600 2.24 0.44 314 180 134 15 900 1.17 0 35 353 274 83 For Z2 20 1200 1.45 0 28 374 36{] 14 Z3 = Z2 = Type 6= 1.0 25 1500 1.21 024 384 450 -fiB n= 0 0 e16, Rolled=35 30 1$00 1,04 020 391 540 -948 S = ~C3.440 35 210f} 0.91 018 396 630 -234 40 2400 0.82 016 465 720 -315 . d= ft. FlowWidth 4.9ft. 45 2700 074 0.15 409 810 -401 • 50 3000 0.68 013 415 960 ,-484 55 3300 0.64 013 423 990 -561 A R Q Tc Tc tota! I Qc 60 3600 061 12 445 1080 -635 a.24 0.05 0.59 0.34 5.63 3 42 0.59 65 3900 060 012 473 1170 -897 70 4200 058 4 1l 491 1260 -769 Qpeak for Case 4= O 59 cfs 75 4540 0 55 O11 507 1350 -843 8u 4800 0.53 010 511 1440 -929 85 5140 052 410 532 1530 -998 90 5400 050 010 541 1520 -1(}79 CRSE 2 95 5700 049 010 559 1716 -1 151 100 6000 48 0.09 576 1800 -1224 Case 2 assumes a Time of Concentratian less than 5 minutes so that the peak flow = 90(3 98){fmp Area} _ {].49 c#s °208" TREATMENT F:EQLiiREMENTS Minimum "208" Vplume RequEred 134 cu ft Provided 7reatment Volume cu ft 5Q, the Peak flow for the 6asin +s the greater af the two fi[sws, 0.59 cfs DRYWEE.L REC]UIREMENTS - 10 YFAR OESIGN STCJRM Minimum Storage Required by 8owstring 167 cu ft Provfded Storage Vplume &22M cu ft Numher and Type af Orywells Specified 1 5ingle 0 ❑ouble ~ ' ~ - ' _ - , , - - ' ' - ~ PEAK F LOW CALC LILATION PRO,IEGT• ~Prairie~a;rcla~ard~n~~,, BOWSTRING METHfJD PROJECT• Prairie Orehard 10-Year mesign Storm ❑ETENTIqN BASIN ❑E54GN BASlN 3 DE5lGh7 EEt ,5F(M,;'•,~,,~~',,. • j" Y^v BASIN -~~"'Y--,~~ DATE• 14-Aug-O2 Tot. Area 3~i'Z 18 5F 0,71 Acres Imp. Area 6~200 SF 7ime Increment (min) 5 C= 4.30 Lawns 0 15 Time ot Conc (min) 5 96 Imp 0.30 Outflow (cfs) KR?f ~ "0'3~ ❑esign Year Flow 10 CAS E I Area (aGres ) 071 Impervious Area (sq ft) 6200 ft pverfand Flow 'C' Factor 030 Area ` C 0214 Ct "208" Imp Area 1';675, L = 220 ft n Time Time dnc Intens Q Devel. Vv! in Vol Qut Starage S w {min} {sec} {mlhr} (cfs) (cu ft)i (cu R) {cu ft) 596 358 2.93 063 300 107 193 Tc = 4,93 min., by Equation 3-2 of Guidelines 5 300 3 18 068 273 90 183 f4. Gutter flow 10 600 2,24 0 48 345 1$0 165 15 900 1 77 0 38 385 270 116 - Z1 = ~,50 0 For Z2 20 1200 145 031 449 360 49 Z2 = ~17yPe 8- 1 0 25 1500 1 21 [7,2~a 419 450 -31 n= 0 01,6 Ro{!ed = 3 5 34 1800 1 04 022 427 540 -113 5= 35 2100 031 019 432 630 -198 40 2400 [},82 018 442 720 -278 ~.-r-. d= '180~ft, Flaw Widti~ 5.9 ft. 45 2700 074 016 446 81{] -3C~ 50 3000 0.68 0.35 453 900 -447 55 3300 064 014 468 990 -522 A R Q 7c 1`c tvfai I Qc 50 3600 061 013 485 1080 -595 036 006 063 1 03 5 96 2 93 0.63 65 3900 060 013 515 1170 -655 70 4200 0.58 0.12 535 1260 -725 Qpeak for Case 7= 0.63 cfs 75 4506 0,56 0,12 553 1350 -797 80 4800 053 4 11 557 1440 -883 85 5100 0 52 4 11 580 1534 -950 90 5400 0.50 0.11 590 1620 -1 Q30 CASE2 95 5740 449 010 609 1710 -1101 100 6400 048 010 528 1800 -1172 Case 2 assumes a Time flf Concentration less fhan 5 mjnutes so thai the peak flow = 90(3.18){Imp, Area} = 0.41 cfs "208" 7REATMEN7 FiEQUIREMEN75 Minimum "208" Volume Reqwred 70 cu ft PfpVl[IEd TPBB(fflenf VpIUf1'1e da{s:°y , CIJ ft So, the Peak flaw for the Basin is the greater of the twp flows, 0.63 cfs DRYVVELL REQLiIREMENTS - 10 YEAR QESIGN STpRM Minimum Storage Etequired by Bowstring 193 cu ft ~ Prov3ded 5tarage Valume ,,~,~,V,•~~,~~,~.w b;~F.cu ft Number and Type of Drywells Specified 1 Single 0 Douhle . ' PEAK FLOW CALCULRTION PROJECT: S- - 1 D-Year Design Stvrrrr BA51 N: :4;PRE ~~s - Tvt. prea - ~2Q;751Y SF 0.48 Acces I mp, Area 800: 5F I C= 0.32 meadvw 0.30 - f rrtp. 0.90 ~ CAS E 1 0'ft. Overfarad Flaw ~ _ Ct - ; 4a3 015' L = 220 ft. ' n ¢0ti:40 S = --0,0ZBD Tc = 6.44 min., by Equatian 3-2 Qf GuideMines 64ft. GLlttEr flOW For Z2 Z1 = - :50.0 Z2 = Type B-1.D . t - n - 0:O'16 Ralled = 3.5 ; S d ~ 4'95~~ft. Flaw Width 2.5 ft. A R Q Tc Tc tatal I Qc 0.12 0.(]2 0.43 CY.(]0 6.44 2.81 0.43 Qpeak for Gase 1= 0.43 cfs CASE 2 Case 2 assumes a Time of Concentration Iess than 5 minutes so that the - pealc tlow =.90{3.18}(}mp. Area) _ ❑.05 cfs 5v, the Peak flow far the Basin is the greater af the two flvws, i ' 0.43 cfs N PROJECT:4°Prairie.'E]rclia ~r~-~: PEAK FLOW CALCULATfO ._,_._.:~..-._._.H . . 10 Year Design 5torm ~ BASIN:'~~_PC?5T-_~<:~ - ~t~ , Tot. Area 5F 0.48 Acres - 1mp. Area = VzSF C = 4.23 Lawns 0.15 - Imp. 0.90 , CA5 E 1 .°,220ft. OVerland Ffow Gt L = 220 ft. , n _ s = ' a7o`z'sa, Tc ! 6.44 min., by Equa#ion 3-2 of Guidelanes ft. C utter flow ' Z1 = For ZZ Z2 - ' 505:.15'i Type B = 1.43 ,~;~,:1.•~ .~~.s fl RoIled _ 3.5 ~s ~ o~~oao~ d - ft. Flow Wid#h 2.2 ft. A Fi Q TE Tc fatal I Qc 0.09 0.02 0.31 0.00 6.44 2.81 0.31 Qpeak far Gase 1= 0.31 cfs ; CAS E 2 Case 2assumes a Time of Cvncentration Iess than 5 minutes so that the peak flaw =.90(3.18)(1mp. Area) = 0.14 cfs 'Sv, the Peak flvw for the 6asin is the greater of the two fiows, 0.31 cfs ~ i - - , - , - - , - - PEAK FLOW CALCULATIDN PROJECT: Arairiej[]rch;ard~=~s~` BOWSTF:ING INETH(]❑ PROJEC7. Praine Orchard 10-Year design 5torm aETENTIaN BASIN DE51GIV BASIN: 5 i]ESICNFR`51(M~~~7` - BASIN• DRTE: 1 4-Aug-02 Tot. Area ,45~7~ 5F 0.15 Acras ~ ~ fmp Area 5F "Fime Incremenf min 5 C= 090 Lawns 0.15 Time of Canc (min) 500 , '67~j Irnp 0.90 Dutflow (cfs) Design Year Flow 10 CASE 1 Area {acres} 0.35 Imperviaus Area (sq Ft) 6457 ft. Overland Flow 'C' Factor 090 Area ` C 0 133 Ct = Eba1,51 "248" Imp. Area ;.,1,1 E. = 0 ft. n= ;"i~~4?`_4OU~ Time Time Inc intens Q Devel ~Jal In Vol.out 5torage S ~ "`0~02Q0 [mir~] 4sec} (iNhr) (cfs) [cu ft] (cu ~t) {cu ft~ 5.00 300 3.18 0 42 171 90 81 Te = 0.00 min., by Equation 3-2 of Guidehnes a 300 318 042 171 90 $1 ~~2Cl~ft. Gutterflc vv 34 600 2.24 0.34 210 180 30 15 900 9.77 0.24 237 270 •33 Zi = SC+I~~' For Z2 20 12[}0 1 45 4.19 252 360 -1 DS Z2 = Type 8 = 1.0 25 1500 1 21 016 259 450 -191 n = F`0C)l 6. Rolled =15 30 1800 104 014 264 540 -276 5= 445(1' 35 2100 091 012 267 630 -363 ~ wP 40 24170 082 17.11 274 720 -446 d= t~..~'rD~[1835~f t Flow'Width 4 2 ft. 45 2700 074 010 277 810 -533 ' 50 3000 058 009 284 900 -619 55 3300 0 64 0 09 290 990 -700 A R Q Tc Tc total I Qc 60 3800 0 51 0.08 301 1080 -779 0.18 004 0.42 2.26 500 3.18 0 42 65 3900 0,60 0.08 320 1170 -850 70 4200 058 008 333 9250 -927 Qpeak fpr Case 1= 0.42 cfs 75 4500 056 007 344 1350 -1006 80 480[] 0 53 0.07 347 1440 -1 093 85 5100 0.52 Q.07 351 153(} -1169 so 5400 0.50 0.07 367 1620 -1253 CASE 2 95 5700 0.49 007 375 1710 •3331 100 5400 0.48 006 391 1500 -1409 Case 2 assumes a 7ima of Concsntratian less than 5 minutes sa that the peak Flow = 94{3,18}{Imp. Area} = 0.42 cfs "208" TREATMEIVT FtEQl11REMENTS Niinimum "208" Volume Required 259 cu ft Provided Treatmenk Volume ~cu ft So, the Peak flow for the Basin is the greater vt the two flqws, 0.42 cfs DRYWELL REQUIREMENTS - 10 YEAR ❑FSIGN STt7RM Minimum 5torage Required by Sowstring 81 cu ft Provided 5torage VoEume cu #t Number and Type of []rywells 5pecified 1 SingEe 0 Clou4le i - , , - , - - - - ' - - ; - - - - - ~ P~AK FLOW CAL~LJLATION PR~J~C~: ~~?~airie~~rch~`'ard3 Bt~WSTRING METHC~❑ PRDJEGT Praine Drchard ~.~6~ as.,~ F 10-Year ❑esign 5tvrm DE'~ENTION BASIN ❑E51GN BR51N 2 2nd 5(Pand C) ❑ESIGNER':5F[M~~~'"`' BAS€N ~•2~_aiitl;5;{~'ond C] DATE° 14-Aug-OZ • To1. Area 22,51fl; SF 0.52 Acres !mp Area 5F TEme Encrement (rnin) 5 G= 0.50 Lawns 0 15 Time of Canc (min) 5 61 Imp 0 90 ❑utflaw {cfs} ' . _ `.70` 3i Design Year Flow 10 GASE 1 Area (acres) 0,52 Imparvious Area (sq ft) 14512 C]verland Flow 'C' Faetor 0,54 Area " C 4 259 Ct = 0.~15 "208" lmp AreB ~ ~'r6;22Q~ L = 180 ft. n= Time Time Inc Intens Q Qevsl. Val.ln Vo6,0ut 5tvrage 5 = :D3~Q {rnin} (sec) (indhr) (cfs) {cu ft} [cu ft] (cu f~) 561 336 302 078 352 101 251 Tc = 5 29 min , by Equation 3-2 af Guidelines 5 300 318 0.82 330 90 244 jr 50'. ft. Gutter flaw 10 640 2 24 4 58 ~314 180 234 15 900 1 77 0 46 454 270 194 Z4 = For Z2 20 1200 1.45 0 37 493 360 133 Z2 _ ' 1.C1 Type B ~ 1.0 25 1500 1 21 0 31 505 450 55 n= Ralled = 3 5 30 3800 1.04 0.27 515 540 -25 S w Q a~4t7a 35 2100 0 91 0,24 521 630 -109 40 2400 0 82 021 533 320 -187 d= , 0!41;0751ft Flqw Width 54 ft. 45 2700 0.74 0.19 538 810 -272 50 3000 0 68 0.18 547 900 -353 55 3300 4.54 017 565 99(} -425 A R A TC TC tofa6 I QC fifl 3690 0.61 016 5$5 1080 -494 0 29 0 05 0.78 032 5.61 302 0 78 65 3900 0.60 016 623 1170 -547 70 4200 0 58 015 647 1260 -613 {]peak far Case 1 = 0.78 cfs 75 4500 056 0 14 668 1354 -682 80 4800 053 0 14 673 1440 -767 85 5100 052 0 13 701 1530 -829 90 5400 050 Q 13 713 1620 •907 CASE 2 95 5700 0 49 0 13 736 3710 -974 100 6000 048 0,12 759 1800 -1 049 Case 2 assumes a Time of Concen#ration less than 5 m3nutes s❑ that the peak Flow -.94(3.18){Emp. Area) = Q 69 cfs °'208" TREATMENT REQUIREMENTS Miraimum "248" Volurne Required 259 cu ft Previded Treatment VolGme ~?77;cu ft So, the Peak flow for the Basin is the greater af the hwo fiows, 0.78 cfs C3RY1fVELL REC.2UIREMENTS - SQ YEAR OE51GN STQRM Minimum Storage Required hy Bawscring 251 cu ft Prowded 5tarage sJpfume 451`cu ft Number and Type of aryvuells Specifed 1 51ngEe 0 Dauble i ~ ~ - - , - - , , - , , - - - - , PF-AK FLLW CALCULA,71C7N PROJECT ~Prairie~[]r~chard,• BDW57RING METHOD PROJEGT Prairie Qrchard 10-Year DeSign StATxri DETENTION BR51N DESIGEV BRSIN, 3 and 5(Pand A) DESIGNEF: SKM~*, ' 6ASIN:E3jand~(~Pand A} DAYE 14-Aug-02 1'ot Area '~,34,483 5F 0 79 Acres tmp, Area SF Time Increment (min) 5 C= 36 Lawns 0.15 Time of Conc. (min) 5 89 Imp 0 90 Oulflow [cfs) • L]esign Year Flow 10 CASE 1 •.Area (acres) 4 79 ImpervEOUS Area {sq ft) 9645 ft. averland F low 'C° Factor 036 Area C 0 285 Ct "20$" Imp. ArE2 L - 22G ft - - n= •.•~i]:400 Time Time Inc Intens. 0 [7ev-eI, Vvl.ln Vvl Out Storage S = (min) (sec) {inlhr} (cfs) (cu ft) {cu ft) 4Gu M- 5 89 354 2.95 0.84 398 354 44 Tc = 4 93 min , by Equation 3-2 Qf Guidelines 5 300 318 ❑ 91 364 300 64 €1h1~]lf t. Gutter f[ow 10 600 2 24 C1 Fr4 459 600 -141 - 15 900 177 0.50 514 900 •386 For Z2 20 1200 1 45 041 545 120~7 -855 ~ ~ f Z2 :0 Type B= 1.0 25 1500 1,21 0 34 558 i 500 -942 n= :,~0 Rolled = 3.5 3C1 1800 1 04 030 569 1800 -1231 S= I~:;sz'~~D'SOa1180 35 2104 0 91 026 575 2100 -1525 40 2404 082 0.23 589 2400 -1819 d= ft. Flow Width 6.5 ft. 45 2700 0 74 021 594 2700 -2105 • 50 3000 0 68 0.19 504 3000 -2396 55 3300 0.64 0.18 523 3300 -2677 A R Q Tc Tc tvtal i Qc fia 3600 061 017 646 3500 -2954 044 007 0.84 0.98 5.88 2.95 0.84 E5 3900 0 60 017 687 3900 -3213 70 4200 058 017 714 4200 -3486 Qpeak for Case 1 = 0,84 cfs 75 4500 4 56 016 737 4500 -3753 80 4800 4.53 0.15 743 4800 -4[}57 $ 5 5100 052 0 15 773 5100 -4327 90 5400 0.50 0.14 785 5400 -4614 GA5E 2 95 5740 0 49 (J.14 812 57{}0 -4888 100 6000 048 014 837 6000 -5153 Case 2 assumes aTime of Cvncentratiqn Ies5 than 5 minuies srs that the peak flow =9Q{3.1$}(Imp, Area) = 0.63 cfs "208" 7REATMEN7 REQU1FdEMEN75 Minimum "208" Valurne Required 213 cu ft Provided Treatman# Valume cu ft 5o, the Peak Flow for the 6asin is the great$r af the iwo flawts, 0.84 c:fs C]RYWELL REQUIREMENTS -10 YERR QE51GN STORM Minirnum Starage Reqwred hy 8awstnng 64 cu ff Prawded 5torage Volume cu ff Numher arad Type of Drywefls Speci#ied O Single 1 E3DUt7Ee I - , - I ~ - - - I - I--- - - - - PEAK FL,OW CALCIJLATION RROJEGT.!PraiBCWSTRlNG INETHC}D PROJECT, Praine Orchard 50-Year Design Stflrm ~ DETENTIQN BASIN []E51GN 8A5lN 1 I]ESIGNER'SKM~;~ BASIN°j :-❑ATE 14-Aug-02 Tot. Area -'~34;•206~ SF 0 79 Acres Imp, Area 5F Time Increment {min} 5 Time of Canc (min) 5 28 G= 0,52 Lawns 0.15 Outflaw {efs} Imp, a 90 Design Year Flaw 50 CASE 1 Area (acres) 079 Irnperviaus Area (sq ft) 16954 °`,"?+SD~ff. L7verland Flow 'C' Fscfar 0 52 `'t n ArES' C 0.41(} ~ Ct = ~,.,~.15. "208" Imp. Araa L = 60 ft n= Time Time Inc Intens Q Devel, V❑1 In Vol Oui Storage 5 = {min} (sec) {inlhr} (cfs) dcu ft) [cu it) {cu ft} N 5 28 317 450 184 783 337 456 7c = 3.17 rnin, by Equatean 3-2 of Guidehnes 5 300 3 18 1 30 524 300 224 ❑itch flow 10 500 2 24 092 649 600 49 15 900 1 77 073 731 900 -159 Z1 = `~r•~ °SCfet7a ForZ2 20 1200 1.45 059 777 1200 -423 `"'~ti ,s s'5o o € ° zz = Type B _1a zs 1500 1.21 0.50 797 1500 aos n= j,. W„3~zk ~;0;1,61 Ralled = 3 5 30 1800 1,04 0.43 813 18t]a -987 S= ! QQ9D~ 35 2100 0.91 037 823 2100 -1277 40 2400 482 034 842 2400 -1558 g'•;v,,T,-.~_,arF I520,~f t . Flvw Width 7,5 ft 45 2700 0 74 030 851 2700 -1849 d = 50 3000 058 0,28 866 3000 -2134 55 3300 064 4 26 893 3300 -2407 A R ❑ Tc Tc tatal I Qc Ba 3600 061 0 25 926 3500 -2674 116 008 183 210 5 28 4 54 1 84 65 3900 0.60 025 385 39{]0 -2915 70 4200 058 4.24 1023 4200 -3177 Qpeak fqr Case 1= 9,84 cfs 75 4500 056 023 1057 4500 -3443 80 4800 0.53 0.22 1065 4800 -3735 85 5100 0.52 0.21 1109 5100 -3991 90 5400 0 50 0 20 1128 5404 -4212 GASE 2 95 5704 0.49 Q.20 1166 5700 -4534 1[]0 6000 Q.48 020 1201 6000 -4799 Case 2 assumes a Time vf Cvncentra#ion less than 5minutes so tha4 the peak flow = 90(4 58)(Imp. Area) = 1 60 cfs "208" TREATMENT REQLIIREMENTS Minimum "208" VolLme Required 504 cu ft Provided Trsatment Vo9ume cu ft Sv, the Peak f[ow for the 8asin is the greater of the iwo flows, 1.$4 cis DRYWELL REQUIRIEMENTS - 50 YEAR QESIGN STdRM Minimum Stvrage Required by Bcwstring 466 cu ft Pravideti Storage Valurne cuft Number and Type of ❑rywells Specified 4 Single 1 Dauhle ~ ' - - _ - ~ - - i- - - - - _ PEAK FLOW CALCULATIQN PROJEC7. PrAair~,ie O`~rcl~ardM~;',?~ BOWSTRIlVG METNOD PRpJECT Praine Orchard 50-Year Qesign 5#orrn [JETENTIpN BASIIV aESiGN 6AS11V, 2 ❑ESIGNER qSItM BASfN.~,~;-; QATE. i 44ug-02 Tot. Area 19~498I 5F 0.45 Acres Imp ,Area 7~5001 5 F Tirne lncrernent {min} 5 7ime af Conc (min) 560 C= 0 44 Lawns 0.15 Outfilow (cfs) p 3" Imp, 0.90 ❑esign Year Flow 50 GASE 1 Rrea {acres} C) 45 Impervious AreB {sq ft} 7500 VN8ajft CverlBnd Flvw 'C' Factvr 0 44 Area' C 0 196 Ct = Evmu p U6 "208° Imp Area L = 180 f#. n= Time Time Inc lntens QDevel. Vo6.ln llol,put 5iorage 5 = 60 (min) {sec) {inlhr} {Cfs} (cu ft) {cu ft} (cu ft) 5 60 336 4 41 087 390 101 289 7c = 5 29 min, by Equation 8-2 of Guidelines 5 300 3.38 0.62 251 90 161 5~; ft. Gutter flow 10 600 2 24 044 314 180 134 . 15 900 1.77 035 352 274 82 Z1 = 5Qf0~ ForZ2 ZO 1200 1.+15 0.28 374 350 14 Z2 = ~'•r.,;f sF°~,1~~~ 'i'ype B= 1 0 25 1500 1.21 0,24 3$3 450 -67 n- •."fyipl;~0~01`fi~ RalEed = 3.5 30 1800 1.04 020 391 540 -149 S= ~{1~64~i7~ 35 2100 91 018 395 630 -235 40 2400 0 82 016 405 720 -315 d= ~~^"~'O 40,2431 it. Ffow Width 5,6 ft. 45 2700 0.74 0.15 409 810 -441 50 3040 0.68 0,13 416 900 -484 55 3340 0 64 013 429 990 -561 E1 R Q Tc TC tafal I cc 60 3600 0 61 0 12 445 1080 •635 0 32 006 087 0.31 5.60 4.41 0.87 65 3800 0.6(} 0.12 473 1170 •697 70 4200 058 011 491 1260 -769 Qpeak for Case 7= 0 87 cfs 75 4500 056 0 11 507 1350 •843 84 4800 053 010 519 9440 -929 86 5100 052 010 532 1530 -998 90 5400 0.50 0.10 541 1620 -1078 CASE 2 95 5704 0 49 D 10 559 1710 -3 951 100 6000 048 009 576 1800 •1224 Case 2 assumes a Time of Concentration less than 5 minutes 5c7 tha4 fhe peak flow = 90{4.58}(Imp Area) = 0 71 cfs "ZOS" TREA7'MEN7 REQUIREMEfVT5 Minurium "208° Vaiume Required 134 cu ft Prov[ded Treatrnent Valume '~:'~,~~•Y'~N__;;~j cu tt So, the Peak flow for the Basin is the greater af the twd flows, 0.87 cfs [}RYWELL REGIUIF2E{v1ENY5 - 50 YEAR DE51GN STQFiM Minimum 5torage Required by Bawstring 289 cu ft Provided Storage Velume ``~;h;, cu ft hlumber arrd Typs of Drywef4s Specified 1 5ingfs 0 Double i - i- - - , ~ - ~ ~ i---~ - PEAK FLOW CALCLILATIDIV PRpJECT PFai~iehayrd~~~4 ~ 6OWSTRING METHC3D PRQJEGT- Prairie C7rcharrf 5fl-Year ~es3grl StArm DETENTION BRSIN DE51GN BA51N• 3 DES IGNER BA51NQF1TE: 14-Aug-Q2 T~t Area 38 5F Q 71 Acres Imp. Area 100 5F Time Encrement (m3n) 5 Time of Conc. (min) 5 87 Q, C= ~.30 Lawns ~ 15 Outflavv (cfs) ?mp 0 90 Design Year FEow 50 CASE i Area {acres} 0,71 impervibuS Area (sq ft) 6200 ft Over~and Flow 'C' FaGtor 0.30 Area`G 0214 "20$° I m p Area 1,575 Ci L = 22C3 fl, n _ ~r'ti;=, 0}40~ Time Tame Inc lntens ❑ Devel Vol In Vol aut Starage 5 = 45891 (min) {sec) {mlhr) {cfs} {cu ft} (cu ft) {cu ft) 5 87 352 d 34 ❑ 93 438 1 a6 332 Tc = 4.93 min., by Equation 3-2 of Guidelines 5 300 318 0 68 273 90 183 GutterFlow 30 600 2 24 048 344 180 164 _ . ._3.~.~ 15 90i7 1.77 038 386 270 116 Zi = ,~'<RQO, ForZ2 Pi] 1200 1.45 L1.31 409 350 49 ne B= 1.0 25 1500 1 21 0 25 419 450 -31 Z2 = ~ . a -i 1 wtl~ TYY ~,b V ~ r~ 0.~.Rolled = 3 5 30 1800 1.04 0,22 427 540 -113 S= fl~01~60 35 21(}0 0 91 0.19 432 630 -198 « 40 2440 0 82 018 441 720 -279 d= j,~~`0~1~865 ft. Flaw Widih 6 8 ft 45 2704 0 74 016 446 810 -364 • 50 3000 0.68 0.15 453 900 -447 55 3304 0 64 0 94 468 990 -522 A R Q 3c Tc tatal i Qc 50 3600 0.61 0.13 485 108(] -595 [}.48 0.07 0 93 0 94 5.87 4.34 0.93 65 3900 0.50 0.13 515 1170 •555 ; 70 4200 0.58 0.12 535 1260 -725 ❑peak far Case 1= 0 93 cfs 75 4500 055 012 553 1350 -797 80 4800 053 Oi1 557 1440 -883 85 5100 0.52 0.11 580 1530 -950 90 5~300 0.50 0.11 590 1620 -143(i ~ASE 2 95 5700 49 010 609 1710 -1101 100 600~ 0,48 Q.10 62$ 18~~ -1172 Case Z assumes a Tirne af Cpncentratifln less than 5 rninutes sc that the peak flvw = 90{4 58}(Imp Area) = 0.59 efs "208" TRERTMENT REQUIREMENTS Minimum "208" Vvlume Required 70 cu ft Provided Tre2tme~t Volume ft 5~0, the Peak flow for the Basin is the greafer of the twv flvwa, 0.93 cfs DRYWELL F~EQUIREMEiVTS - 50 YEAFt DESIGN STORM Minimum 54orage Requirect 6y Bowstring 332 cu ft Provided Storage Valume „cu ft Number and Type of [3rywells 5pscified 1 5ingle 0 oauble i' . ~ ...d ~'EAK FL~QW CALCULATIaN PRO,~ECT: Prai'rFe~€]~rchar~dt~k%q 50-Year aes'rgn Storm BASIN: 4PRE`-'-,- : ; . Tot. Area ~,20;~751~ S F 0.48 Acres I mp. Area S F C = 0,32 rneadow 0.30 , -Imp. 0.90 , CAS E 9 ft. Dverlanci Flow Ct ;15 i L = 220 ft. -n 5 -,*'0280 Tc W 6.44 min., by Equatian 3-2 of Guideliraes Gutter flow Z1 = For Z2 Z2 - Type B - 1.0 _ n - 0:01'6"' Rolled - 3.5 ~ih~" > ry.:1^' • S ~ :1 tL VLVV~ d= ft. Flow W idth 4.4 ft. A R Q Tc Tc total I Qc 0.39 0.04 0.64 0.00 6.44 4.18 0.64 Qpeak far Case 1 = 0.64 cfs - CAS E 2 ~ Case 2 assumes a Tirne af Cancentrativn less than 5 minutes so that the peak flow =.90(4.58)(Imp. Area) = 0.08 cfs Sa, the Peak flQw fvr the Basin is the greater of fhe twv flaws, ' 0.64 cfs ,i PEAK FLQW CALGULATION PROJECT::Prairie-~rchard~~, - 50Year Design 5torm gAS1N:,!4:-P~~ST~:,~_ 0.48 Acres I- Tvf. Area [];-?51, SF ~ ~ lrnp. Area 5F G ~ 0.23 Lawns 0.15 lmp. 0 90 GAS E 1 ~=---a,-~~ - fE. Overlarrd F6vw , . Cf , L _ .220 ft. n []:4[33 S = ~ ^ A _ Tc = 6.44 min., by Equatian 3-2 of Guidelines O~ ft. Gutter flow Z1 = Fnr Z2 Z2 = Type B = 1.0 n- Q16, Rofled = 3.5 _ S - d- ~ ft. Flow Width 3.9 ft. „ A R Q Tc Tc total I Qc 0.30 0.04 0.46 [].00 6.44 4.18 0.46 Qpeak for Case 1= 0.46 cfs CAS E 2 +Case 2 assurnes a Time of Goncen#ratian less than 5 minutes sa that the peak flow =.90(4.58)(Imp. Area) = 0.21 cfs Sa, the Peak flaw for the Basin is the greater of the twv flows, 0.46 cfs , ~ ' ' , - - , , ~ - ~ , - i - PEAK FLOW CALCULATIpN PR[].lECT• IPr e~~~rcFr'ar,d~~;~~*• ~s~,p 80iN5TRING METWD❑ PROJECT. Prair9e Orchard 50-Year Design 5tarm ' C1ETENTlON BASiN pE51GN BA51N, 5 QESIGNER ~k-M~"`?;_ BA51N 7J5~ DATE. 14-Aug-02 Tot. Area 0.15 Acres lrnp. Area 71 5F Time lncrement (mm) 5 Time of Conc {rnin} 5.00 =x-- C= 0.90 Lawns 0 15 ❑utflow (cfs) Omp. 0.90 ❑esign Year Flow 50 GASE 1 Area (acres) 015 Empervious Area (sq ft) 6457 ~:,01 ft vverland Flow 'C' Facfar 090 Area * C 4 133 Ct = ~,~^bar 10415~ "208" Imp. Area L = 4 fit. ' n= 0 ~~400 Tima Time Inc Intens. Q Deve€, Val.ln Vol,Dut 5torage ~iz~` ~•°••t. S = ~;'''~6~zfl4 (min) (sec) fmlhr] {cfs) icu ft] (cu ft) (cu ft) 5 00 300 4 58 4 61 24fi 90 ~56 Tc = 000 rnin„ by Equation 3-2 of Guidelines 5 300 3.18 042 171 90 81 ft. Gutter flow 10 BOD 2 24 0 30 210 180 30 15 940 1,77 0.24 237 270 -33 Z'1 = FvrZ2 20 1204 1 45 0 19 252 360 -108 s; FS~v 7-2 = TYpB B= 10 25 1500 1.21 0.16 259 450 -191 n_ Ro11ed = 3.5 30 18o0 1 04 0 14 264 540 -275 5= k ea.~5fl 35 2100 0 91 0.12 267 630 -363 40 2400 0.82 0.11 274 720 -445 d= •F wQ96flj ft Flow Width 4 8 ft 45 2700 074 010 277 810 -533 • 50 3000 0.68 0 09 281 900 -619 55 330[] 0.64 0.09 290 990 -700 A R Q Tc TC tDtal I Qc 60 3604 061 00$ 301 1080 -779 024 4.05 0.61 206 5 00 4.58 061 E5 3800 060 008 320 1170 -850 70 4200 0 58 008 333 1260 -927 Qpeak far Case 1= 4 81 cfs 75 4540 0 56 0 07 344 1350 -1008 80 4800 0.53 0.07 347 1440 -7093 85 5300 0 52 007 361 1530 -1169 90 5400 0.50 407 357 1520 -1253 CASE 2 95 5700 049 007 379 1710 -1331 100 6000 048 005 391 1800 -1409 Cass 2 assumes a Time of Ccmcentration Ee-.ss than 5 minutes s[a that the peak flow =,90(4.58)(Imp Area) = 0.61 cfs "208° TREATMENT REQUlF2EMEIVTS Minimum "208" Valume Requ3red 269 cu ft PraaEded Treatmen# VolGme cu ft ''..`i7.'.lt., ' •.'w. ;r.e.a 50, the Rea'k flnw for the Basin is the greater raf the two flvws, 0.61 cfs ❑RYWELL REQUiREMENTS - 50 YEAR DE51Ghl STQRM Minimum St4rage Required by 6owstring 156 cu ft a.r~•;.+-_. Provided Storage Volurne Num6er and Type of Drywe9is Specifed 1 5ingie 0 Double ~ i i - - - - - - - - - I , - - PROJEGT: PEAK FLDW CALCLIL~ITIQN P~tO,~ECT.?Prairie~~rchai~d.' 4 gOwsT~t9tvG METHOD Prairi~ Qrchard 50-Year Design 5t0E'rri DETEhiTION BASIN DESIGN BA51lv, 2 and 5(Pond C) DESIGfVER-ZKM . BASIN. i~ and_5,~~ahd C} DATE; 14-Aug-02 Tat, Area 2~,516,SF 0.52 Acres fmp Area 10,5_12-SF Time Increment (m3n) 5 Time aC Canc {rnirr} .556 C= 050 Lawns p 15 Outflow {cfs} D 3: Imp. 0.90 ❑esign Year Flow 50 . CASE `k Area (acres) 0.52 Imperviaus Area (sq ft) 10532 _':'~'~,~•1$Olft, Ovedand Flow 'C' Factar 050 Area * C 0 259 Ct = Nm0 1`5 "208" Imp Area L = 180 ft. ~ V ~ n= •'~p~4'CtQ Time Time Tnc, Intens, C~ Oevel, Voi In Vo . ut torage 5 = ~f"~wQ~360 (rnin) (sec) {inlhr) (cfs) [cu ft] (cu Ft) {cu ft) . 5.58 335 442 1.94 593 1[}0 412 Tc = 5.29 min., by EquafiQn 3-2 rsf Guide9ine5 5 300 3 18 0.82 330 90 240 •`~:`-5ni Tt. Gutfer flow 10 600 224 058 413 180 233 15 900 1.77 0.46 454 270 194 Z9= `;r,,' ~ 54EOW Far Z2 20 1200 4.45 037 492 360 132 Z2 = °1101 Type 8= 9.0 25 1500 1.21 0.31 505 450 55 n~ 16 RoIled = 3.5 30 18Qa 1.04 027 515 540 -25 i= 0Q 35 2100 0.91 0.24 521 63{] -109 Y . 40 2400 0 82 0 21 533 720 -187 d= &3 . f~.1~24'Q ft. Ffvw Width 5.2 ft. 45 2700 74 0.19 538 890 -272 • 50 3000 058 0 18 547 900 --353 55 3300 fi4 017 565 890 -425 A R a TC TC tDta'1 I QC 60 3600 0.51 0.15 586 1080 -494 039 006 1.14 029 5.58 442 1 14 65 3900 0.60 016 623 1170 -547 70 4200 0 58 015 647 1250 -613 Clpeak for Case 1= 1,14 cFs 75 4500 0.55 0.14 658 1350 -682 8(] 4800 053 014 673 1440 -767 85 5100 0.52 013 701 1534 •829 90 5400 050 0.13 713 1620 -907 CASE 2 95 5700 0 49 0.13 736 1790 -974 100 8000 048 012 759 1800 -1041 Casa 2 assumes a Time of Concenteatifln less ihan 5 mmutes so thafi the peak flvw =.90(4.5$)[Irnp, Area) = 6 99 cfs "208" TRERTMENT REQUIREMENTS Minimum "208" Vvlume RequEred 255 cu ft Provided Treafinent Valume yi2771 cu ft So, the Peak Tlow far the Basin is the greater oF the Ewo flows, 3.1+3 Gfs QRYWELL REQiJIREMENTS - 50 YEAR DESIGN 5Tf3RM Minimurn Storage Required by Bowstring 412 cu ft Provfded Storage Valume cu ft Nurnber and Type of Drywslls Specifiad I 5ingle 0 C]auble ~ - - , , - - - , ; , - ~ , , - - PEAK FLCJW CALCULAT]ON PRQJECT-~Prairi'eRQrchard'~E f~ BpWS~"RIIVG METFiO❑ PR{3JECT Prairie Orchard . u.50-Year Design Stvrm DE7ENT9DN BASIN DE51GhE BASIN, 3 and 5(Pand A) • •D~SIGNER:SKIIn',~~:~:`.;; . 6ASIN. ;3,an0,5 (PQnd A) DATE. 14-Aug-02 "'%~fs`934'4 a Tof.Area 5F 0.79 Acres Imp. A r e a 4583~~5F Time Increment {min} 5 . Time of Conc {min} 5.80 C = 0.36 Lawns 0.15 ' flutfi[rw {Cfs} . H ..f! Imp 0.90 ~ CJesign Year FIQw 50 CASE I Area {acres} 0.79 lmpervivus ArBa {Sq ft} 9645 ft. {]verland Flow 'C' Factor 0.36 Area * C 0 285 Gt= ~~'~~i!Lo A-51 "208"Imp Iarea L = 220 ft, n = ':0:466 Time TFme Inc intens. Q Devel VQI In Vol Out 5tarage fl.06,$0 (rnin) {sec] (anlhr) ;cfs) {cu ft) {eu ft) [cu ft] 5 86 348 4 36 1 24 579 348 231 Tc = 4.93 mm., hy Equation 3-2 of Guidehnes C== 5 300 3 16 091 354 300 64 Gutter fEaw 10 600 2 24 064 458 600 -142 15 900 1.77 0.50 513 800 -387 Z1 = For Z2 ' 20 1200 1,45 0.41 544 1200 -$5E Z2 = :~.Qt~ Type B= 1.0 25 1500 1.21 0.34 558 1500 -942 n= 01,6; Ralled = 3 5 30 1800 1 04 030 568 1800 -1232 5= 35 2100 0 91 25 575 2100 -1 525 44 2400 82 023 586 2400 -1812 d= ~~~'~~0 1eb20 f#. Fiow Width 76 ft, 45 2700 074 0.21 594 2700 -2106 • 50 3000 fi8 019 604 3[}00 -2396 55 3300 4 64 038 623 3300 -2677 A R Q Tc Tc tata! I qc 60 3600 4 61 a 17 645 3800 -2954 0.59 008 1.24 0.87 5.80 4.36 1.24 65 3900 0 50 0.17 687 3900 -3213 70 4200 0.58 0.17 713 4200 -3487 Qpeak for Cass 1 W 4 24 cfs 75 4500 0.56 0.16 737 4500 -3783 8Q 4800 053 015 742 4800 -4058 85 5100 052 015 773 5100 -4327 90 5400 050 014 788 5400 -4814 CASE 2 95 570[] 049 014 812 570(} -4888 100 6400 0.48 0.14 836 600[} -5164 Case 2 assurnes a Time raf Con6enfratiprt less than 5 minu#es so that the peak filow = 90(4 58)(Irnp Area) = 0.91 cfs "208" TREATMENT REQUiREMENTS _ Minimum "208" VQlume RequirerS 213 cu ft ' Pravided Treatmen tllolume sR'~~~'~;~$4'cu ft _..~.1 50, the Peak flvw fvr the Basin is #he greater of-#he iwo flvvas, 1.24 Cfs - DRYWELL REQUIREMENTS - 50 YERR DE51GN STQRIVI Minimum 5tvrage Required hy E3owstnng 231 cu ft Prflwded Storage 1folume M~46~cu ft hlumber and Type pf ❑rywells 5pecified 0 Single 1 Qouble ,I I~ INLET CALCULATIONS i - - - , , , Frairie Orchard S020160 apokane County+, Washington 08114l02 50-'1'ear r}esign 5torrrt Englneer: DNR CLTRB 1NLET CALCULATTQNS on Coniinuous Grade Curb Ynlet Ba.sin Bas~n + Gutter Raughness LlepCh T3ascharge rnlet By-Pass Pond Sireet and , Feak Flow By-Pass Slope Cross slope Coeff; 2 af Flow per Length Length Flaw . , Statian , (cfs) Q s 11Z n n d* Qa.lY..a** La Q -Qa 24TH AVE C 5ta 17+98.11 1.14 1.14 0.0552 00200 0.0160 3125 O11 0.076 5 0.68 24TH AVE C Sta 18+09 21 0.68 6.4552 0.02170 0.0150 3125 0.09 0063 G 031 24TH AVE A Sta 19+50.65 1 24 1.55 0.0167 0.0200 00160 3125 0 15 0.106 12 027 24TH AVE A Sta 19+77.80 0.27 0.0181 0.0200 00160 3125 0.08 0 055 5 -0.00 NDTE: TYPES 1& 2 CURB ZNLETS Curb Tnlet Depressinn = 2 rn. *Calculated per Ftguure 1$ of the Spokane Ccrunty Gufdedanes for Starrmwater Management Calculated per Figure 15 Qf che Spokane Cou»ty Guidelines for 5cormwater Managemcnt CurbDropC i - - - ; - , , - - - Praine C7rchard 5020134 Spakane Counry, Washingtan 08114102 54-Year Storm EVent Engineer• DNR CURB 17ROP FLOW CAPACITIES in Sump Canditions . Curh-Inlet. Easin Basin+ Inlet Maucianurn Maximum Sy-Pass B'asin, 5treet andX, , Inlet'f'ype t'eak Flow By-Fass* Length Flow IJepth" Discharge*** Flow ' • Station ' - - - (cfs) Q (f}) _ H Qa Q - Qa Burns cul-de-sac 1"YPE 2 1 Sia 1+81.82 CURB 184 1.84 4 00 0.50 4 37 -2.53 N{?TE' T7'PE i CL.1RB fNLET TYPE 2 CL.1RB INLE7' Qa = 3 0$7 * L* H^ 1.5 Curta Inlet Depression = 2 an. Curh Inlet Depression = 2 in. GVhere L= Length of Curb 13rop, H= Flow Depkh Nfaximum Inlet Height = 8 in. Curb Inlet Length = 4 ft Maximum Inlet Height = G in *By-Pass flaws from upseream inFets on continuous grades. Maximum Flaw Qepth is based om Inlet height Calculated per Secticsn 4-1 of the Spvkane County Guadelines , for Skormivater Managernent GurhDropS i - FLOODED WIDTH CALCULATION , , ,6' 7.6' FLow wfQTH ~ I TYPICAL ROAD CRC355-SECTIaN COLLECTOR AR1`EREAL, 2 LANE NON FL0ODE❑ ZLNE Wi[3TH (FT) 16.0 ,