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WPO202100054 Calculations 2021-09-14
Keswick Hall Family Pool COUNTY OF ALBEMARLE, VIRGINIA VSMP DESIGN CALCULATIONS & NARRATIVE SEPTEMBER 10, 2021 .•'�s TIMMONS GROUP YOUR VISION ACHIEVED THROUGH OURS. Prepared by: Craig Kotarski, PE Timmons Group 608 Preston Ave, Suite 200 Charlottesville, VA 22903 434.327.1688 V CRAIGW. I KOTARSKI Lie. No. 0402048507 9/10/21 Table of Contents Section Title Project Narrative 2 Pipe and Inlet Computations Virginia Runoff Reduction Method Worksheet Summary 4 Pre -Developed HydroCAD Calculations 5 Post -Developed HydroCAD Calculations 6 Nutrient Credit Availability Letter FORM LD 200 STORMWATER INLET COMPUTATIONS SHEET OF ROUTE PROJECT O.W& FemiN Pod DESIGNER: J. Denko DATE S1S12321 CHECKED: UNITS'.NGLISH milli INLETSOFT BY ENSOFTEC DATE: U13 l STRM 100 STORM SEWER DESIGN COMPUTATIONS STORM FREQUENCY 10 PROJECT: LOCATION: COUNTY: Keswick Family Pool Albemarle County Designed by: Checked by: J. Denko C. Kotarski UNITS ENGLISH PIPE NO FROM POINT TO POINT DRAIN. AREA "A" AcreMinutes (3) RUNOFF COEFF. "C" (4) CA TOTAL INLET TIME (7) RAIN FALL In/Hr (8) RUNOFF Q CFS (9) INVERT ELEVATIONS LENGTH of Pipe Ft. (12) SLOPE Ft./Ft. (13) SIZE (Dia. Or Span/Rise) In. (14) SHAPE Capacity CFS (15) Friction Slope Ft./Ft. VEL Vn Ft/Sec (16) FLOW TIME Min. (17) REMARKS (18) 7ALAC ADDTL CA UPPER END (10) LOWER END (11) REFERENCE (1) STA. REFERENCE (2) STA. 107 108 106 0.110 0.860 0.095 1 0.095 0.000 6.000 6.230 0.589 434.000 433.723 14.694 0.019 12.000 Circular 5.301 0.000 4.461 0.055 105 106 104 0.050 0.570 0.029 0.190 0.067 6.055 6.214 1.178 433.620 433.154 45.438 0.010 12.000 Circular 3.909 1 0.001 1 4.366 1 0.173 103 104 102 0.060 0.530 0.032 0.240 0.019 6.228 6.164 1.482 433.050 426.927 57.484 0.107 15.000 Circular 22.833 1 0.000 1 10.498 0.091 101 102 100 0.140 0.370 0.052 0.330 0.038 6.320 6.138 2.027 426.827 425.990 83.733 0.010 15.000 Circular 6.996 1 0.001 1 4.946 10.282 201 1 202 1 1 200 1 1 0.000 1 0.000 1 0.000 1 0.372 1 0.372 1 0.000 1 8.901 1 3.315 1 427.000 1 418.000 1 156.194 1 0.058 1 15.000 1 Circular 1 16.794 1 0.002 1 10.667 0.244 UGD Outfall 305 306 304 0.120 0.500 0.060 0.098 0.038 6.000 6.230 0.611 429.620 429.265 70.909 0.005 12.000 Circular 2.728 0.000 2.806 0.421 303 304 302 0.140 0.740 0.104 0.202 0.000 6.421 6.109 1.232 429.170 428.962 41.657 0.005 12.000 Circular 2.728 0.001 3.392 0.205 307 308 302 0.080 0.730 0.058 0.058 0.000 6.000 6.230 0.364 434.110 431.395 90.501 0.030 12.000 Circular 6.683 0.000 4.558 0.331 301 302 300 0.310 1 0.870 0.270 0.568 0.038 8.700 5.537 3.143 428.860 1 428.562 29.774 0.010 15.000 Circular 1 6.996 0.002 1 5.561 0.089 403 404 402 0.780 0.390 0.304 0.304 0.000 8.900 5.492 1.671 431.867 431.656 21.095 0.010 12.000 Circular 3.858 0.002 4.747 0.074 401 402 400 0.000 0.000 0.000 0.304 0.000 8.974 5.476 1.666 431.560 430.652 78.937 0.012 12.000 Circular 4.139 0.002 4.996 0.263 503 504 502 0.360 0.600 0.216 0.216 0.000 6.000 6.230 1.346 431.460 431.165 29.453 0.010 12.000 Circular 3.858 0.001 4.483 0.109 501 502 500 0.000 0.000 0.000 0.216 0.000 6.109 6.198 1.339 431.070 430.889 18.057 0.010 12.000 Circular 3.858 0.001 4.477 0.067 STRM 100 HYDRAULIC GRADE LINE ANALYSIS INCIDENCE PROBABILITY 10 Year PROJECT: Keswick Family Pool DESIGNED BY: Checked inDZ ,Ire.. C. Kotarski INLET OR JUNCTION INLET STATION OUTLET WATER SURFACE ELEV. DIA. PIPE Do (In) DESIGN DISCH. Do (CFS) LENGTH PIPE Lo (Ft) FRICTION SLOPE, Sfo (FT/FT) FRICTION LOSS Hf (Ft) JUNCTION LOSS FINAL H (Ft) Inlet Water Surface Elevation Rim Elev Comments Vo Ho (Ft) Qi Vi QiVi Vi'2/2g Hi Angle H4 Ht 1.3 Ht 0.5 Ht 102 426.99 15 2.03 83.73 0.08% 0.07 4.95 0.09 1.48 10.5 15.56 1.71 0.6 12.21 0.22 0.92 0 TRUE 0.53 427.52 429.59 OK -2.07 104 427.93 15 1.48 57.48 0.04% 0.03 10.5 0.43 1.18 4.37 5.14 0.3 0.1 72.3 0.18 0.71 0 TRUE 0.38 428.31 436.29 OK -7.98 106 1 1 433.95 1 12 1 1.18 1 45.44 1 0.09% 1 0.04 1 4.37 0.07 0.59 4.46 2.63 0.31 0.11 40.95 0.13 0.31 0 TRUE 0.2 1 434.15 1 436.63 1 OK -2.48 108 1 1 434.52 1 12 1 0.59 1 14.69 1 0.02% 1 0 1 4.46 0.08 0 0 0 0 0 0 0 0.08 0.1 FALSE 0.1 1 434.63 1 437.21 1 OK -2.58 202 419 1 15 1 3.31 1156.191 0.22% 1 0.35 1 10.67 1 0.44 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0.44 1 0 1 FALSE 1 0.79 1 419.79 1 435.06 1 OK -15.26 302 432.89 15 3.14 29.77 0.20% 0.06 5.56 0.12 1.23 3.39 4.18 0.18 0.06 74.63 0.2 0.38 0.49 TRUE 0.31 433.2 435.76 OK -2.5-1 304 433.2 12 1.23 41.66 0.10% 0.04 3.39 0.04 0.61 2.81 1.71 0.12 0.04 45.64 0.06 0.15 0.19 TRUE 0.14 433.34 433.63 OK -0.29 306 433.34 12 0.61 70.91 0.03% 0.02 2.81 0.03 0 0 0 0 0 0 0 0.03 0.04 TRUE 0.04 433.37 433.66 OK -0.29 308 1 1 433.2 1 12 1 0.36 1 90.5 1 0.01% 1 0.01 1 4.56 1 0.08 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0.08 1 0.1 1 TRUE 1 0.06 1 433.26 1 437.16 1 OK -3.9 402 432.89 12 1.67 78.94 0.19% 0.15 5 0.1 1.67 4.75 7.93 0.35 0.12 35.09 0.15 0.37 0 FALSE 0.52 433.41 437.64 OK -4.24 404 433.41 12 1.67 21.09 0.19% 0.04 4.75 0.09 0 0 0 0 0 0 0 0.09 0.11 FALSE 0.15 433.56 436.37 OK -2.81 502 432.89 12 1.34 18.06 0.12% 0.02 4.48 0.08 1.35 4.48 6.03 0.31 0.11 39.93 0.13 0.32 0 TRUE 0.18 433.07 434.87 OK -1.8 504 433.07 12 1.35 29.45 0.12% 0.04 4.48 0.08 0 0 0 0 0 0 0 0.08 0.1 FALSE 0.14 433.21 434.96 OK -1.75 iite Information Name: Date: Project (Treatment Volume and Loads) Enter Total Disturbed Area (acres) Land Cover forert/o ns areas• " ••�•••�•�•� I I I 0.00 Managetl Tu nacres)-- disturber, graded for ands or other tryuff to be mowed/managed 0.66 0.66 Impeious cover (acre.) a o. 0.87 data input cells mnrtant Values calculation cells LfneorprojetYP No Land cover areas entered correctly? Total disturbed area entered? - protected forest/o en s or reforested land Managed Tuff(acres) tlirturbed,graded for ands or other tuff to be mowed/mane ed 0.47 OA7 Impervious cover (acres) 1.06 1.06 Area Check OK OK OK OK 1.53 Constants Runoff Coefficients Rv Annual Rainfall (inches) 43 ASoils BSoils CSoils DSOIN Target Rainfall Event (inures) 1.00 FEd/Open Spare 0.02 0.03 0.04 0.05 Tmal Phmphmm(TP)EMC Img/1) D.26 Manag¢tl Turf 0.15 0.20 0.22 0.25 Total Nitrogen (TN) EMC(myf'I1 1.86 1 Impetuous Cover 0.95 0.95 0.95 1 0.9, Target TP Load(lb/are/yr) D.41 Pj(uniness correRin factor) D.90 LAND COVER SUMMARY -- PRE -REDEVELOPMENT• COVER SUMMARY POST DEVELOPMENT Land Coversummary-Pre Load cover Summary Post(Final) Lmad Cover Summary -Post Lam(Cover Summary -Port Pre-ReDevelopment usual Adjusted Post ReDev. A New lmpevicus Pas[-ReDeveloPmeM post -Development New lnptl , ForesVOpen Space Cower (acres) 0.00 0.00Forest/Open Space Caner (acres) 0.00 Forest/Open Space Cover (Acres) 0.m Weighted "Front) 0.00 0.00Weighted Rv(fored) 0.D0 Weighted Rv(framan 0.00 %Forest 0% as; rest %Fo 0% %Forest 0% Managed TurfCover(acres) 0.65 0.47 Managed Turf Cover (acres) 047 Managed Turf Cover (acres) 047 Weighted Kilburn 0.25 0.25 Weighted Rv(lurf) 0.25 Weighted RV (turn 0.25 %Managed Turf Impervious Cover (aces) 43% 0_87 35% 087 %Managed Tud Impervious Cover (acres) 31% 106 %Managed Tuff Rele¢Imperil 0us cover (acres) 35% 087 Neu lmpervblN Carer (Bases) Rv(impervimn) %Impervious Total Site Area (Bass) 0.95 57% 1.53 0.95 65% 1.34 Rv(impendous) %Impervious Final Site Ares (acres) 0.95 69% 1.53 Rvlmpervicam) %Impervious Total ReDr.$be Area saes 0.95 65% 134 Mk She RV 0.65 0.T1 Final Port Der Site Rv 0.73 ReDwShe Rv 0.70 Treatment Volume and Nutrient Load Treatment Volume and Nutrient Load Pre-ReDevelopmeMTreMmen[ Volume• Treatment 0.0826 0.0787 �'• K •...r...•... Treatmers'Zome 0.093J (ant tame tt) Pre-ReDevelopment Treatment Volume Final Port -Development (cubit feet( 3,599 3,427 Treatment Volume 4,082 (cubic fret) Final Post- Pre-ReDeVelopment TP Load 226 2.15 Development TP Load 2.56 (lb/yr) (Ib/yr) Pre ReDeaclopmemWLoad peracm Nalftnt evelopmem TP ((/want) 1.°B 1.61 Wad per arm 1.68 ab/avend Raddine TP Load (Ib/yr) (teal lba/ave/yr applied! W pr,e levelopment area excluding pervious 0.55 land rearmed fir new impervious mmr) 'Adjusted Land Cover Summary: We ReDevelopment land cover minus pemous land rover (/oresr/open space or managed tuH) acre.,,mpmed)or new impervious rover. Adjusted total acreage is remittent with Post-ReDevelopment acreage (minus acreage a f rew impervious cover). Column Ichows load reduction requriement/or new impetuous rover (based on new development load limit, 0..4116s/arnJyearJ. TP Load Reduction Required (lb/yr) 1 0.76 Nitrogen Loads (Informational Purposes Only) Final Pozl-I Pre-RaD.elopmeMTN xed(lb/yr) 16.18 (Pose-0.e0evelo Port-ReDevelopment Treatment Volume 0.0787 (sere ft) Pod-ReDevelopment Treatment Volume 3,427 (nbicfeet) Pod-ReDevelopment Wad (TP) 2.15 (lb/yr)• POA-ReneuElapmem TP Load per acre (Ib/eve/yq Mae Reduction Required (Below Pre- ade ....,.Pman Wad) TP Wad Reduction R"Weadfor Redeveloped Area 043 IIb/yr) 18.35 Port -Development Tremmeatvolume 0.0150 (aae-ft) Port -Development eatment Volume (cubic 655 feet) Port -Development TP Loma (N/yrl TP Load Reduction Required for New 0.33 Impervious Area (lb/yr) Drainage Area A OraloageAera Alga cpry (ave) A. asap Cmm DSalb TmaB Tare Coeer Re :wesVor Aes'pres) MAD 0.00 Menepea Tudkees) 0.28 0.29 0.25 arOnem raw )saes) 0.53 0.53 0.95 Total 0.81 Stormwater Best Management Practices (RR = Runoff Reduction) _AdrawLmaqfimrsoasf. h.11, DAA Total Phosphorus Available for Removal in DA. A llb/yr) 1.31 Post Development Treatment Volume in D.A. A(a) L0112 -SeRrtfromtlmpcownlists- Runoff Managed Impervious Volumefrom Remaining Total amp phosphorusPnospnorus Eoatl Untreated Phosphorus Remaining practice Retlucdon Turf Credit Coeer Credit Runoff Upstream Run:B Volume Treatment Removal ham upstream Pbospboms Loatl Removed By maspbomstoad —nstream Praeticembe Reduction las) Employed Credit l%) Area (acres) Area lacers) Practice lRel (Rsl Volume insI Emdenryl%1 Prastrres (lb) mPnRice(lb) praRice(lb) (161 aVegetal Roof#1(Sessr as) f,P oLouuse 11, vegetewa Pmin lspecxp 0 0 0 n00 v.smpeDsmwamA mNesain D 2n. Shape Laos, nenton m M ral, 0 A v sulnmeneea Fee, Palnapw igwamlasting VDnllA( as) o 0 0 0 am Andnm .a. T. Ry well, f,enm Dam rl, m.lauaaon at )epee wl 0 0 0 0 and And Lou nm an, E,ma Dena,VI D-mwenitrm.,#2(Speeee) 0 0 0 0 am anp nm ,mn m, If. T. Ram rvo. 1(Spee el an 0 0 am D.menaz, el AD 0 m 3 hxio Ra nxrt Xenestln6lspe,p61 0 0 hmu, Z'Tonowi lateen Dear as,'in,s Dal .a. leak Paeanem #1 hipsc nl as pennnue Paawiert xz)epee xzl 11 0 0D ..Gone a.nrelq/95o21spetwll 0 0 nm hed�_�__ 17 as Dos cwnnlCM ulspw'a1 D A. a sscMne l,ntn comport nrerMei SYl, ets lea spar no raisa. It swakn )spat woo) 1,b. Dv swle xz(Seen all urb- B-st-ha n Ispenuw esl EL RloaDnron xz or MmmRloamnron xz epstar) 71. m8bateanm(spe " moraine Removal Emdenry(%) Nitrogen Load kom Upstream Proodies)Ibs) Untaded Nitrogen Loatlm Preface(lbs) Nitrogen RemowiPy hacdre Ilse) Remaining mtmgan Loatl )Ibs) 0 A.amAnd A. and Dm OLOO am am And ssOLOO am am And an am am one an 0am Mou nm se pan and am am n.D.,_comlmo a oopo TOTAL" COVERTRFRTFU(a[( 611 MG CHECK: OK TOTAL NAL4 01AREP TREATED (a[( 6DO AREA CHEM OK TOTAL R UHOFS REDO LTIOH I H DA. A(113( 1W TOTAL PHOSPHORUS AVAIL ABLE FOR REMOVAL IR OA.A(Ib/y[( 1.31 TOTAL PHOSPHORUS REMOVED WITH RUNOFF REDUCTION PRACTICES IX BA.A(Ib/yt( U.13 TOTAL PHOSPHORUS REMAINING AFTER APPLYING RUNOFF REDUCTION PRACTIQS IN D.A. A(Hb/yt( 1.17 SEE WATER QUALITY COMPLIANCE TAB FOR SITE COMPLIANCE CALCULATIONS & 1111"IeE Delentian land (RU 9. SFeeHlow to Filter/Open Space 9. SFeeHlow to Filter/Open Space (RR) TOTAL RUNOFF REDUCTION IN D.A. A(W) ]b5 NNROGEN REMOVED PATH RUNOFF REDUCTION PRACTICES IN DA. A(Ib/y[( O% SEE WATER QUALITYCOMPIMNCE TAB FOR SFM CALCULATIONS(InJpmdUwl Only( _ r Oonol— Speaww_h o®tTn Drainage Area B nr.a.... arse. a I.ndn.,.r f.—i A546 BW4 CSob 05mis Totals Lana CwerM perwal prnspee0ors) 0.00 OA0 aCna on Turf larrts) 0.67 0.07 o.ss Imenhourcoverlanel 0.53 0.59 0ffi TOW 0.60 Stormwater Best Management Practices (RR = Total Phosphorus Available for Removal in DA. B(lb/yr) 1.19 Port Development Treatment Volume in DA. B )k) 1 1,891 PM1ospheruz UMrexetl RYntio Mortareddl Impervious VDineen, Runol. 0.Rubduf Totalm PM1e=a, RM1aspM1der Remaining Loatl ham PhOzpM1orus Downstream Pnni¢to be Practice Reduction TUIt4etlk Doane' Credit Upstream ReduRlOn RunoR Treahneot Removal Removed By PM1ospM1orus Drcdit (%) Aree(eaes) Area(aaes) PrvcU¢(ka) (ha) Volume(k'a) Volume(ke) EMGensy(%) Upstream Load to P.&.(lb) Loed(Ib) Employed Practi¢s(Ib) Pnxl¢(lb) L a. VegepaelRm1p11Sp p5) OS 0 D 0 d 00] D.AI D.00 I. E. Ve(e[afetl Roofp2lSpe[Y51 ED 0 0 0 0 0.0] ON D.CO Rooftop 2.a. Simple Dlsmnnect". Io N."k 0 0 D 0SO 0 D.dl O.W D.AI D.CO 2u. Simple DixannMion mCMSwa ss 0 0 ll 0 0 O.dl orm O.AI not p 2c To Set Amended Fiber as So 0 0 0 0 0 O.m flop Am 6m sp ermanonz 1anlr�g 4D mil:l (spe<xe) 2.d. TO Dry well a Frenm Oran x; SOo 0 0 o ss not nm Om O.m MornimilrMIon A, IS tlBl 2.e. m Dry Wellor French Dralne2, m 0 0 0 0 25 O.m 0.m Ron O.m Mpm,lnmra[lonn M 2f. TO Rai....en.L an 0 0 0 0 25 notO.m Oso O.m MkmBldttendion pt (spa.) 2&TO Rain GaMen02, MkmBIde..pu. 2 5 p9 An 0 0 0 0 SO O.D. O.m p. O.m 2ls To Rainwater Harvesting RW AR) 0 0 0 ll 0 0 O.m one mp O.m 2.I. TO Stormwater Planer, b 0 0 0 0 25 O.m O.m mp O.m Urban.wrn,.tlon (Seera0, appendle a) 3. Permeable Pavement (RR) O. Grass Channel (RR) 5. Dry Swale (RR) tarot gy s VPPM PdrvCm�v`B_SpW1Y_Jf_ P1 Dae .,.a........�",.............�.................... Ibhan Bbreten[bn S cp9 w a D D a zs am am am am 6. b. 61ore[entlonpEot Ml[mabre[eMbn NE Is arRl m p p 0 0 5a a.m am am am E.a. InaNrz[bn rE (SPecpB) So 0 0 It 0 ES o.m Om a.m "Ad I.E. Infiltration rz ESpc NB) m a a 0 o ES o.m Um a.m o.m 8 Extended Detention Pond (RR) A'Fnrllspe<as) B a o p o Ss P., pm a.m o.m A, ,:Eisparts) IS p p p o 1s an, pm a.m om TOTAL IMPERVIOU5 COVER TREATED Ia[) O.M AREA CHECK: OR. TOTALTURFAREATRFATEO Ia[) 0.00 AREA CHECK: OK. TOTAL RUNOFF REDUCTION IN DA. B(k°) O50 TOTAL PHOSPHORUS AVAILABLE FOR REMOVAL IN D.A. B Qb/yrl 119 TOTAL PHOSPHORUS REMOVED WITH RUNOFF REDUCTION PRACTICES IN OA B IIb/yr) 03T TOTAL PHOSPHORUS REMAINING AFTER APPLYING RUNOFF REDUCTION PRACTICES IN DA.BQb/yr) 082 SEE WATER QUALITY COMPLIANCE TAB FOR SITE COMPLIANCE CALCULATIONS St Utp ].Infiltration RR) S. Extended Detention Pond (RR) 9. Sheetflow to Filter/Open Space (RR) TOTAL RUNOFF REDUCTION IN D.A. ITIN') 450 NITROGEN REMOVED WITH RUNOFF REDUCNON PRACTICES IN DA. B Qb/yr) 2.66 SEE WATER QUALITY COMPLIANCE TAB FOR SITE CtILCUUTNONS (Information Only) Site Results (Water Quality Compliance) Area Checks D.a a DA. B D.A. C D.A.0 D.& E n OEOK WREST/OPEN SPACEJac) a G.m 0,00 O.m 0.00 OIL IMPERVIOUS COVER Jac) 0.53 0.53 0.00 0.m 0.00 OIL IMPERVIOUSC&MRTRFATW(ac) 0.11 0.29 0.00 0.m 0.00 mL bVW1WEO TURF ARFA(ac) 0.28 NN 02 O.m 0.00 M MfWAGEOTURFARFATRFATEO(ac) OW O.W OAO Om OAO M ARFACNECK ML O. OK. OK. OK. Site Treatment Volume (fa) °� �7 Runoff Reduction volume and TP Ely Drainage Area D.A. A DA. B O.A. C D.A.0 O.A. E TOTAL RUNOFF REOUMN VOLUMEACNIEVW(N3) 165 450 0 0 0 615 W LOAOAVAIIABM MR REMDVAL(Ib/yr) 1.31 1 1.19 am 0.00 am 2.50 W LOAD RWUOION ACNIEVED(Ib/yr) 0.13 0.37 0.00 0.00 0.00 Q50 W LOAD REMAINING (Ib/yr) 1.17 082 0.00 000 0.00 1.99 MIROGENLDADREOUCTIONACNIEVED (lb/yr)II 0.96 11 2.64 0.00 0.00 0.00 3.60 Total Phosphorus RhXU-UMLObIENTWUMD(Ib/y) 1% W LOAD REDUCTION REQUIRE)(Ib/yr) an TP LOAD REWOION/ IEVW(Ib/yr) O50 TP LOAD REMAINING (Ib/yr): 106 REMAINING W LOAD REDUCDON REQUIRED(Ib/yr): M26 Total Nitrogen (For Information Purposes) WST-MWE MENr LOADpbhA MIROGFN LDAD RED"GRV ACHIEVED pb/yr) RMI MNING POST-DEVEWPMEW NOROGEN LMO (Ib/yn Runoff Volume and Curve Number Calculations Enter design storm rainfall depths lint: 1-rearstorry 2-yearstorm 30-yearstorry 292 3.54 5,15 We NOAA atlas la hab //nescnws nmu. yav/nnr/p/d+/l •Notes (see belowi: IIj The surre numbers and mmoRvdumes computed in this spriadsbre[ for each drainage area are limited in their appllcablllty for determining and remonstrating compliance with water quantity requiremei see VRRM User's Guide and Documentation for additional inhumation. pj RuinatiVolume (RV) for pre - and partArvelopment drainage areas must be in volumetric units le.g., acrei or cubic hMl when using the Energy Balance Equation. Runoff measured in watersbM- inches and shown in the spreadshre[ as RViwatersM6inch) can only be used in the Energy Balance Equation when the pareandpostdndopment drainage areas are equal. 0thewise RVlwatershN-inch) must be mukiplied by the drainage area. pj Adusted [Ns are based on mnoH reduction volumes as calculated in D.A. tahs. An altemative CN adjustment calculation far Vegetattl Roots is included in BMp specification No. S. Drainage Area Curve Numbers and Runoff Depths• Carve numbers (CN. CNadl) and rundi depths (RV o.wn 1 are camPated with and without reduction practkes. Drainage ArasA ASoils BSoils CSOiIs DSails Tall Area haul: 0.81 Forest/Open Space- undisWhed, laoteded forest/openspaceorrebrested land Area arcs) ON am 30 am 55 am 70 am ]] RumnReduadon Volume (ft): 10 Managed Tort- Bombed, gratletl for yanN or other lurf to be mowed/managed Areaares ON am 39 am 61 am 70 0.28 80 Impervias Comr Areaharms) O! 0.m 98 am Be am Be 0.53 98 CNDnA H 1-rear storm 2-year storm I"ar starry RVDwwloped (wodelMdlnM/ within RumR Reduction• 2m 2.60 "."B RV (wodersbed�OrM/ with Runoff Reduction• 2m 262 "i8 Adjusted CN• H 91 H •see Notes above Drainage gangs ASailz BSoilz C%Us DSDilg Toll Arco faaul: am ForesVOpen Space- undisturbed, protested Gucc pen space or rebrested land Areaharms) Cis ROD 30 0M 55 0.00 ID am A RuroRReOetla� Volpe 450 Managed Turf- disturbed, gratletl for pass or other turf m be mowed/managed Area ares U! 0.00 39 D.CO 61 O.Oo ]0 0.07 M Impervious Cover Area re a O.W 9B 0M 98 O.Oo 98 RS3 98 CN DA.R 1-year storm 2-year storm la- ear storm RVeM (wmelMd tmbl with m RUIpR Reduction* 2A] 3.00 4.88 RVD.wlead (wadershed imb) with human Reducton• 2.27 1 2.80 1 0.67 Adi.Wd CN" 1 9" 1 9" 1% •See Nudes above Orainage AreaC ASailz BSoilz CSoilz DSDih; Toll Area peresl: 0.00 Forest/Open Space- undisturbed, protected ftum pen space orrebrested land Area ares Q! am 30 O.CO 55 am ID am ]] Runoff Reduction Volume k': 0 Managed Turf-dirturhed,gmdedf-r Msor otherturf m be mowed/managed Area hamres) M am 39 O.CO 61 am 70 am 80 Impervious Cover Area ares U! am 98 am % 0.00 % O.CO M CN,.,, 0 1-rearstarm 2-rear:tarry 10-rear:mrm RVDavalepy (wodershed-InMI wits ao RUIpn Reduction• am am am RV (Rmdelhedln[b/ coded Runoff Reduction• 0.m am am Adiasted CN• 0 a 0 •gee Nodes above Drainage A.D ASailz BSoilzWIG�ar. Toll Am. (weed: 0.m Forest/Open Space- undisturbed, protected fmoy en space orrebrested land Area ares Q! am 30 am 55 RmpX Redumon Volume 0 Managed Turf- distuhed, gratletl W pass or Mher turf m be mowed/managed Area ares M am 39 am 61 Impernouc Cover Area home)am W 98 am BeBe 1-rearstarm 2-yearstoml RVDrsdwgg (Rmdelbed+m'b) wiM Ip RUIpR Reduction• RV (RmdelheMu[hl wiM Runoff Reduction- am I am 0.00 M 0.H on Adjusted CN' 1 0 1 0 1 0 'See Notes above Dminage Area ASails BSoils CSoils DSoils Total Arealacm.l: D.DD Porest/Open Space- undisturbed, protected brest/openspaceorrebrested land Area xres (N O.W Ow 30 55 O.W ID am J] RumX Reduction VOW— IR't: 0 MareolTW- disuhM, graded fm pMs or& her turf to be mo—oll—raged Area arcs M 0.00 Ow 39 61 O.W JO O.CO EO Imperviws Cover Area arcs w aw am % 9e am 9e am sa a p. R 1-Vear storm 2-yearsTorm 1Dryearstorm RVOM (wulersAedbttltl with lMr Rulpx Reduawn• RV (axopersAe{Auh/ with RuMReduction• 000 Q00 lAdas[ed Cx' eSee Notes "bore Virginia Runoff Reduction Method Wonsheel DEQ Virginia Runoff Reduction Method Re -Development Compliance Spreadsheet - Version 3.0 BMP Design Specifications List: 2013 Draft Stds & Specs Site Summary Project Title: Keswick Family Pool Date: 44448 Total Rainfall (in): 43 Total Disturbed Acreage: 1.63 Site Land Cover Summary Pre-ReDevelopment Land Cover (acres) A soils tails C Soils D Soils Totals %of Total Forest/Open (acres) 0.00 0.00 0.00 0.00 0.00 0 Managed Turf (acres) 1 0.00 0.00 0.00 D.66 0.66 43 Impervious Cover (acres) 1 0.00 0.00 0.00 D.87 0.87 57 1.53 100 Post-ReDevelopment Land Cover (acres) Asolls BSoils CSolls DSoils Totals %of Total Forest/Open (acres) 0.00 0.00 0.00 0.00 0.00 0 Managed Turf (acre') 1 0.00 0.00 0.00 0.47 0.47 31 Impervious Cover (acres) 0.00 0.00 0.00 1.06 1.06 69 1.53 100 Site Tv and Land Cover Nutrient Loads Final Post -Development Post Post- Adjusted Pre- (Post-ReDevelopment ReDevelopment Development ReDevelopment &New Impervious) (New Impervious) Site Rv 0.73 0.70 0.95 0.70 Treatment Volume(fts) 4,082 3,427 655 3,427 TP Load (lb/yr) 2.56 2.15 0.41 2.15 Total TP Load Reduction Required (lb/yr) 0.76 0.43 0.33 Final Post -Development Load (Post-ReDevelopment & New Impervious) Pre- ReDevelopment TN Load (Ib/yr) 18.35 16.18 Pre ReDevelopment Final Post -Development Port-ReDevelopment TP TP Load per acre TP Load per acre Load per acre (lb/acre/yr) (lb/acre/yr) Ib acrer 1.61 1.68 1.61 Summary Prim Virginia Runoff Reduction Method WoMsheel ----------------------------- _-_ ------ _-_ ------ _-_ _-_._.___._.._.___._.._.___._.._.___._.._.___._.._.___._.._.___._.._.___._.._.___._.._.___._.._.___- Site Compliance Summary Maximum %Reduction Required Below PrieReDevelopment Load 20% Total Runoff Volume Reduction (f[s) 615 Total TP Load Reduction Achieved (Ih/yr) 0.50 Total TN Load Reduction Achieved (Ih/yr) 3.60 Remaining Post Development TP Load 2.06 (lh/yr) Remaining TP Load Reduction(Ih/yr) 0.26 Required Summary Print Virginia Runoff Reduction Method WOMsheel ------------------------------------------------------------------------------------------------------------------------------------------------------ Drainage Area Summary D.A. A D.A. B D.A. C D.A. D D.A. E Total Forest/Open (acres( 0.00 0.00 0.00 0.00 0.00 0.00 Managed Turf (acres) 0.28 0.07 0.00 0.00 0.00 0.35 Impervious Cover (acres) 0.53 0.53 0.00 0.00 0.00 1.06 Total Area (acres) 0.81 0.60 0.00 0.00 0.00 1.41 Drainage Area Compliance Summary D.A. A D.A. B D.A. C D.A. D D.A. E Total TP Load Reduced (Ib/yr) 0.13 0.37 0.00 D.00 0.00 0.50 TN Load Reduced (lb/yr) 0.96 2.64 0.00 0.00 0.00 3.60 Summary Print Virginia Runoff Reduction Method WOMsheel Drainage Area A Summary Land Cover Summary A Soils B Soils C Soils D Soils Total %of Total Forest/Open (acres( 0.00 0.00 0.00 0.00 0.00 0 Managed Turf (acres) 0.00 0.00 0.00 0.28 0.28 35 Impervious Cover (acres( 0.00 0.00 0.00 0.53 0.53 65 0.81 BMP Selections Managed Turf Impervious Cover BMPTreatment TPLoad from Practice Credit Area Credit Area Volume(it'practices Upstream Unt reated TP Load [°Practice (Ibs) TP Removed (Ib/yr) TP Remaining (Ib/yr) Downstream Treatment to he Employed acres acres Ihs 3.a. Permeable Pavement #1 (Spec #T) 0.106016692 365.59 0.00 0.23 0.13 0.09 Total Impervious CoverTreated(acres( 0.11 Total Turf Area Treated (acres) 0.00 Total TP Load Reduction Achieved in D.A. h/ r 0.13 Total TN Load Reduction Achieved in D.A. h/ r 0.96 Summary PriM Virginia Runoff Reduction Method WOMsheel Drainage Area B Summary Land Cover Summary A Soils BSoils CSoils DSolls Total %of Total Forest/Open (acres( 0.00 0.00 0.00 0.00 0.00 0 Managed Turf (acres) 1 0.00 1 0.00 0.00 0.07 0.07 12 Impervious Cover (acres) 1 0.00 1 0.00 0.00 0.53 0.53 88 0.60 BMP Selections Managed Turf Impervious Cover BMPTreatment TPLoadfrom Untreated TP Load TP Removed TP Remaining Downstream TreatmentPractice Credit Area Credit Area a volume (k ( Upstream to Practice (Ibs) (Ib/yr) (Ih/yr) to he Employed acres acres practices Ihs 3.a. Permeable Pavement#1 (Spec #7) 0.29 1,000.07 0.00 0.63 0.37 0.26 Total Impervious Cover Treated (acres) 0.29 Total Turf Area Treated (acres) 0.00 Total TP Load Reduction Achieved in D.A. (lb/yr) 0.37 Total TN Load Reduction Achieved in D.A. (lb/yr) 2.64 Summary Print Virginia Runoff Reduction Method! WoMsheel Runoff Volume and CN Calculations ITarget Rainfall EVeot(in) 1 2.92 1 3.54 1 5.35 1 Drainage Areas RV&CN Drainage Area Drainage Area Drainage Area Drainage Area Drainage Area ON 92 96 0 0 0 RR (fta) 165 450 0 0 0 1-year return period RV wo RR(ws-in) 2.09 2.47 0.00 0.00 0.00 RVw RR (.sin) 2.03 2.27 0.00 0.00 0.00 CN adjusted 91 94 0 0 0 2-year return period RV wo RR(ws-in) 2.68 IN 0.00 0.00 0.00 RVw RR (wsn) 2.62 2.88 0.00 0.00 0.00 CN adjusted 91 94 0 0 0 10-year return period Re(ws-in) 4.43 4.88 OAO 0.00 0.00 PRk%wo:R�R(w�n) 4.38 4.67 0.00 0.00 0.00 CN adjusted 91 94 0 0 0 Summary Print 7S 8S 10S 11S Pre Area 1 nsite Pre Area 2 ( site) Pre A a 2 (Offsite) ( ) Pre re 1 (Offsite) 9L 12L Areas Combined (Prel On+Off-site) Subcat Reach Aon Llnk Area 2 Combined (Pre On+Off-site) Keswick Hall_PreDev NOAA 24-hr D 1-Year Rainfall=2.92" Prepared by Timmons Group Printed 9/9/2021 HVdroCADO 10.10-4a s/n 06538 © 2020 HVdroCAD Software Solutions LLC Paae 2 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 7S: Pre Areal (Onsite) Runoff Area=0.990 ac 0.00% Impervious Runoff Depth>1.91" Flow Length=280' Tc=6.2 min CN=90 Runoff=2.11 cfs 0.157 of Subcatchment 8S: Pre Areal (Offsite) Runoff Area=0.760 ac 0.00% Impervious Runoff Depth>1.31" Flow Length=435' Tc=8.9 min CN=82 Runoff=1.03 cfs 0.083 of Subcatchment 10S: Pre Area 2 (Onsite) Runoff Area=0.540 ac 0.00% Impervious Runoff Depth>1.91" Tc=6.0 min CN=90 Runoff=1.15 cfs 0.086 of Subcatchment 11S: Pre Area 2 (Offsite) Runoff Area=0.400 ac 0.00% Impervious Runoff Depth>1.38" Flow Length=454' Tc=10.5 min CN=83 Runoff=0.54 cfs 0.046 of Link 9L: Areas Combined (Prel On+Off-site) Inflow=3.10 cfs 0.241 of Primary=3.10 cfs 0.241 of Link 12L: Area 2 Combined (Pre On+Off-site) Inflow=1.64 cfs 0.132 of Primary=1.64 cfs 0.132 of Total Runoff Area = 2.690 ac Runoff Volume = 0.373 of Average Runoff Depth = 1.66" 100.00% Pervious = 2.690 ac 0.00% Impervious = 0.000 ac Keswick Hall_PreDev Prepared by Timmons G NOAA 24-hr D 1-Year Rainfall=2.92" Summary for Subcatchment 7S: Pre Area 1 (Onsite) Runoff = 2.11 cfs @ 12.13 hrs, Volume= 0.157 af, Depth> 1.91" Printed 9/9/2021 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs NOAA 24-hr D 1-Year Rainfall=2.92" Area (ac) CN 0.990 90 CN - VRRM Spreadsheet 0.990 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.4 59 0.0700 0.18 Sheet Flow, Grass: Dense n= 0.240 P2= 3.54" 0.3 96 0.1300 5.80 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 0.5 125 0.0070 4.40 5.40 Pipe Channel, 15.0" Round Area= 1.2 sf Perim= 3.9' r= 0.31' n= 0.013 6.2 280 Total N V Subcatchment 7S: Pre Areal (Onsite) Hydrograph Time (hours) ■ Rurwff Keswick Hall_PreDev Prepared by Timmons G NOAA 24-hr D 1-Year Rainfall=2.92" Summary for Subcatchment 8S: Pre Area 1 (Offsite) Runoff = 1.03 cfs @ 12.16 hrs, Volume= 0.083 af, Depth> 1.31" Printed 9/9/2021 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs NOAA 24-hr D 1-Year Rainfall=2.92" Area (ac) CN 0.760 82 >75% Grass cover, Good, HSG D 0.760 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.8 100 0.0800 0.21 Sheet Flow, Grass: Dense n= 0.240 P2= 3.54" 0.5 100 0.0500 3.60 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 0.5 135 0.0500 4.54 Shallow Concentrated Flow, Paved Kv= 20.3 fps 0.1 100 0.0500 11.77 14.44 Pipe Channel, 15.0" Round Area= 1.2 sf Perim= 3.9' r= 0.31' n= 0.013 8.9 435 Total Subcatchment 8S: Pre Areal (Offsite) Hydrograph ■ Rurwff 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) Keswick Hall_PreDev Prepared by Timmons G NOAA 24-hr D 1-Year Rainfall=2.92" Printed 9/9/2021 Summary for Subcatchment 10S: Pre Area 2 (Onsite) Runoff = 1.15 cfs @ 12.13 hrs, Volume= 0.086 af, Depth> 1.91" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs NOAA 24-hr D 1-Year Rainfall=2.92" Area (ac) CN Description 0.540 90 CN - VRRM Spreadsheet 0.540 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 10S: Pre Area 2 (Onsite) Hydrograph ■ Runoff 9 1 2 3 4 5 6 7 8 9 19 11 12 13 14 15 16 17 18 19 29 21 22 23 24 Time (hours) Keswick Hall_PreDev Prepared by Timmons G NOAA 24-hr D 1-Year Rainfall=2.92" Printed 9/9/2021 Summary for Subcatchment 11S: Pre Area 2 (Offsite) Runoff = 0.54 cfs @ 12.18 hrs, Volume= 0.046 af, Depth> 1.38" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs NOAA 24-hr D 1-Year Rainfall=2.92" Area (ac) CN Description 0.400 83 >75% Grass cover, Good, HSG D 0.400 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 9.2 100 0.0530 0.18 Sheet Flow, Grass: Dense n= 0.240 P2= 3.54" 0.1 26 0.2300 7.72 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 0.7 163 0.0350 3.80 Shallow Concentrated Flow, Paved Kv= 20.3 fps 0.5 165 0.1200 5.58 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 10.5 454 Total Subcatchment 11S: Pre Area 2 (Offsite) Hydrograph ❑ Runoff 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) Keswick Hall_PreDev Prepared by Timmons G NOAA 24-hr D 1-Year Rainfall=2.92" Printed 9/9/2021 Summary for Link 9L: Areas Combined (Pre1 On+Off-site) Inflow Area = 1.750 ac, 0.00% Impervious, Inflow Depth > 1.65" for 1-Year event Inflow = 3.10 cfs @ 12.14 hrs, Volume= 0.241 of Primary = 3.10 cfs @ 12.14 hrs, Volume= 0.241 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link 9L: Areas Combined (Pre1 On+Off-site) Hydrograph ■ InMov ■ Primary Time (hours) Keswick Hall_PreDev Prepared by Timmons G NOAA 24-hr D 1-Year Rainfall=2.92" Printed 9/9/2021 Summary for Link 12L: Area 2 Combined (Pre On+Off-site) Inflow Area = 0.940 ac, 0.00% Impervious, Inflow Depth > 1.68" for 1-Year event Inflow = 1.64 cfs @ 12.14 hrs, Volume= 0.132 of Primary = 1.64 cfs @ 12.14 hrs, Volume= 0.132 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link 12L: Area 2 Combined (Pre On+Off-site) Hydrograph ■ Inflow C Primary Time (hours) Keswick Hall_PreDev NOAA 24-hr D 2-Year Rainfall=3.54" Prepared by Timmons Group Printed 9/9/2021 HVdroCADO 10.10-4a s/n 06538 © 2020 HVdroCAD Software Solutions LLC Paae 9 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 7S: Pre Areal (Onsite) Runoff Area=0.990 ac 0.00% Impervious Runoff Depth>2.48" Flow Length=280' Tc=6.2 min CN=90 Runoff=2.71 cfs 0.205 of Subcatchment 8S: Pre Areal (Offsite) Runoff Area=0.760 ac 0.00% Impervious Runoff Depth>1.81" Flow Length=435' Tc=8.9 min CN=82 Runoff=1.43 cfs 0.115 of Subcatchment 10S: Pre Area 2 (Onsite) Runoff Area=0.540 ac 0.00% Impervious Runoff Depth>2.48" Tc=6.0 min CN=90 Runoff=1.48 cfs 0.112 of Subcatchment 11S: Pre Area 2 (Offsite) Runoff Area=0.400 ac 0.00% Impervious Runoff Depth>1.89" Flow Length=454' Tc=10.5 min CN=83 Runoff=0.74 cfs 0.063 of Link 9L: Areas Combined (Prel On+Off-site) Inflow=4.08 cfs 0.320 of Primary=4.08 cfs 0.320 of Link 12L: Area 2 Combined (Pre On+Off-site) Inflow=2.15 cfs 0.175 of Primary=2.15 cfs 0.175 of Total Runoff Area = 2.690 ac Runoff Volume = 0.494 of Average Runoff Depth = 2.20" 100.00% Pervious = 2.690 ac 0.00% Impervious = 0.000 ac Keswick Hall_PreDev Prepared by Timmons G NOAA 24-hr D 2-Year Rainfall=3.54" Printed 9/9/2021 Summary for Subcatchment 7S: Pre Area 1 (Onsite) Runoff = 2.71 cfs @ 12.13 hrs, Volume= 0.205 af, Depth> 2.48" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year Rainfall=3.54" Area (ac) CN Description 0.990 90 CN - VRRM Spreadsheet 0.990 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.4 59 0.0700 0.18 Sheet Flow, Grass: Dense n= 0.240 P2= 3.54" 0.3 96 0.1300 5.80 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 0.5 125 0.0070 4.40 5.40 Pipe Channel, 15.0" Round Area= 1.2 sf Perim= 3.9' r= 0.31' n= 0.013 6.2 280 Total Subcatchment 7S: Pre Areal (Onsite) Hydrograph ■ Rurwff 9 1 2 3 4 5 6 7 8 9 19 11 12 13 14 15 16 17 18 19 29 21 22 23 24 Time (hours) Keswick Hall_PreDev Prepared by Timmons G NOAA 24-hr D 2-Year Rainfall=3.54" Summary for Subcatchment 8S: Pre Area 1 (Offsite) Runoff = 1.43 cfs @ 12.16 hrs, Volume= 0.115 af, Depth> 1.81" Printed 9/9/2021 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year Rainfall=3.54" Area (ac) CN 0.760 82 >75% Grass cover, Good, HSG D 0.760 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.8 100 0.0800 0.21 Sheet Flow, Grass: Dense n= 0.240 P2= 3.54" 0.5 100 0.0500 3.60 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 0.5 135 0.0500 4.54 Shallow Concentrated Flow, Paved Kv= 20.3 fps 0.1 100 0.0500 11.77 14.44 Pipe Channel, 15.0" Round Area= 1.2 sf Perim= 3.9' r= 0.31' n= 0.013 8.9 435 Total Subcatchment 8S: Pre Areal (Offsite) Hydrograph ■ Rurwff 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) Keswick Hall_PreDev Prepared by Timmons G NOAA 24-hr D 2-Year Rainfall=3.54" Printed 9/9/2021 Summary for Subcatchment 10S: Pre Area 2 (Onsite) Runoff = 1.48 cfs @ 12.13 hrs, Volume= 0.112 af, Depth> 2.48" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year Rainfall=3.54" Area (ac) CN Description 0.540 90 CN - VRRM Spreadsheet 0.540 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 10S: Pre Area 2 (Onsite) Hydrograph 0 Runoff 9 1 2 3 4 5 6 7 8 9 19 11 12 13 14 15 16 17 18 19 29 21 22 23 24 Time (hours) Keswick Hall_PreDev Prepared by Timmons G NOAA 24-hr D 2-Year Rainfall=3.54" Printed 9/9/2021 Summary for Subcatchment 11S: Pre Area 2 (Offsite) Runoff = 0.74 cfs @ 12.18 hrs, Volume= 0.063 af, Depth> 1.89" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs NOAA 24-hr D 2-Year Rainfall=3.54" Area (ac) CN Description 0.400 83 >75% Grass cover, Good, HSG D 0.400 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 9.2 100 0.0530 0.18 Sheet Flow, Grass: Dense n= 0.240 P2= 3.54" 0.1 26 0.2300 7.72 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 0.7 163 0.0350 3.80 Shallow Concentrated Flow, Paved Kv= 20.3 fps 0.5 165 0.1200 5.58 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 10.5 454 Total 0,7 Subcatchment 11S: Pre Area 2 (Offsite) Hydrograph I :■ .......... .......... :::::::::: MIMEMEMEM ; 0..1..2..3.4.5..5..7..8.9.10.11 12.13.14 15.16,7.,3. 020 21 2223.2 24 Time (hours) ❑ Runoff Keswick Hall_PreDev Prepared by Timmons G NOAA 24-hr D 2-Year Rainfall=3.54" Printed 9/9/2021 Summary for Link 9L: Areas Combined (Prel On+Off-site) Inflow Area = 1.750 ac, 0.00% Impervious, Inflow Depth > 2.19" for 2-Year event Inflow = 4.08 cfs @ 12.14 hrs, Volume= 0.320 of Primary = 4.08 cfs @ 12.14 hrs, Volume= 0.320 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link 9L: Areas Combined (Prel On+Off-site) Hydrograph ■ hifim— ■ Primary Time (hours) Keswick Hall_PreDev Prepared by Timmons G NOAA 24-hr D 2-Year Rainfall=3.54" Printed 9/9/2021 Summary for Link 12L: Area 2 Combined (Pre On+Off-site) Inflow Area = 0.940 ac, 0.00% Impervious, Inflow Depth > 2.23" for 2-Year event Inflow = 2.15 cfs @ 12.14 hrs, Volume= 0.175 of Primary = 2.15 cfs @ 12.14 hrs, Volume= 0.175 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link 12L: Area 2 Combined (Pre On+Off-site) Hydrograph ■ InMov ■ Primary Time (hours) Keswick Hall_PreDev NOAA 24-hrD 10-Year Rainfall=5.35" Prepared by Timmons Group Printed 9/9/2021 HVdroCADO 10.10-4a s/n 06538 © 2020 HVdroCAD Software Solutions LLC Paoe 16 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 7S: Pre Areal (Onsite) Runoff Area=0.990 ac 0.00% Impervious Runoff Depth>4.21" Flow Length=280' Tc=6.2 min CN=90 Runoff=4.45 cfs 0.347 of Subcatchment 8S: Pre Areal (Offsite) Runoff Area=0.760 ac 0.00% Impervious Runoff Depth>3.39" Flow Length=435' Tc=8.9 min CN=82 Runoff=2.64 cfs 0.215 of Subcatchment 10S: Pre Area 2 (Onsite) Runoff Area=0.540 ac 0.00% Impervious Runoff Depth>4.21" Tc=6.0 min CN=90 Runoff=2.44 cfs 0.189 of Subcatchment 11S: Pre Area 2 (Offsite) Runoff Area=0.400 ac 0.00% Impervious Runoff Depth>3.49" Flow Length=454' Tc=10.5 min CN=83 Runoff=1.34 cfs 0.116 of Link 9L: Areas Combined (Prel On+Off-site) Inflow=7.01 cfs 0.562 of Primary=7.01 cfs 0.562 of Link 12L: Area 2 Combined (Pre On+Off-site) Inflow=3.68 cfs 0.306 of Primary=3.68 cfs 0.306 of Total Runoff Area = 2.690 ac Runoff Volume = 0.868 of Average Runoff Depth = 3.87" 100.00% Pervious = 2.690 ac 0.00% Impervious = 0.000 ac Keswick Hall_PreDev Prepared by Timmons G NOAA 24-hr D 10-Year Rainfall=5.35" Printed 9/9/2021 Summary for Subcatchment 7S: Pre Area 1 (Onsite) Runoff = 4.45 cfs @ 12.13 hrs, Volume= 0.347 af, Depth> 4.21" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year Rainfall=5.35" Area (ac) CN Description 0.990 90 CN - VRRM Spreadsheet 0.990 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 5.4 59 0.0700 0.18 Sheet Flow, Grass: Dense n= 0.240 P2= 3.54" 0.3 96 0.1300 5.80 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 0.5 125 0.0070 4.40 5.40 Pipe Channel, 15.0" Round Area= 1.2 sf Perim= 3.9' r= 0.31' n= 0.013 6.2 280 Total Subcatchment 7S: Pre Areal (Onsite) Hydrograph ■ Rurwff 9 1 2 3 4 5 6 7 8 9 19 11 12 13 14 15 16 17 18 19 29 21 22 23 24 Time (hours) Keswick Hall_PreDev Prepared by Timmons G NOAA 24-hr D 10-Year Rainfall=5.35" Summary for Subcatchment 8S: Pre Area 1 (Offsite) Runoff = 2.64 cfs @ 12.16 hrs, Volume= 0.215 af, Depth> 3.39" Printed 9/9/2021 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year Rainfall=5.35" Area (ac) CN 0.760 82 >75% Grass cover, Good, HSG D 0.760 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 7.8 100 0.0800 0.21 Sheet Flow, Grass: Dense n= 0.240 P2= 3.54" 0.5 100 0.0500 3.60 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 0.5 135 0.0500 4.54 Shallow Concentrated Flow, Paved Kv= 20.3 fps 0.1 100 0.0500 11.77 14.44 Pipe Channel, 15.0" Round Area= 1.2 sf Perim= 3.9' r= 0.31' n= 0.013 8.9 435 Total Subcatchment 8S: Pre Areal (Offsite) Hydrograph ■ Rurwff 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) Keswick Hall_PreDev Prepared by Timmons G NOAA 24-hr D 10-Year Rainfall=5.35" Printed 9/9/2021 Summary for Subcatchment 10S: Pre Area 2 (Onsite) Runoff = 2.44 cfs @ 12.13 hrs, Volume= 0.189 af, Depth> 4.21" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year Rainfall=5.35" Area (ac) CN Description 0.540 90 CN - VRRM Spreadsheet 0.540 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 10S: Pre Area 2 (Onsite) Hydrograph ■ Runoff 9 1 2 3 4 5 6 7 8 9 19 11 12 13 14 15 16 17 18 19 29 21 22 23 24 Time (hours) Keswick Hall_PreDev Prepared by Timmons G NOAA 24-hr D 10-Year Rainfall=5.35" Printed 9/9/2021 Summary for Subcatchment 11S: Pre Area 2 (Offsite) Runoff = 1.34 cfs @ 12.18 hrs, Volume= 0.116 af, Depth> 3.49" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs NOAA 24-hr D 10-Year Rainfall=5.35" Area (ac) CN Description 0.400 83 >75% Grass cover, Good, HSG D 0.400 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 9.2 100 0.0530 0.18 Sheet Flow, Grass: Dense n= 0.240 P2= 3.54" 0.1 26 0.2300 7.72 Shallow Concentrated Flow, Unpaved Kv= 16.1 fps 0.7 163 0.0350 3.80 Shallow Concentrated Flow, Paved Kv= 20.3 fps 0.5 165 0.1200 5.58 Shallow Concentrated Flow, Unpaved Kv= 16.1 fos 10.5 454 Total Subcatchment 11S: Pre Area 2 (Offsite) Hydrograph ■ Runoff 9 1 2 3 4 5 6 7 8 9 19 11 12 13 14 15 16 17 18 19 29 21 22 23 24 Time (hours) Keswick Hall_PreDev Prepared by Timmons G NOAA 24-hr D 10-Year Rainfall=5.35" Printed 9/9/2021 Summary for Link 9L: Areas Combined (Pre1 On+Off-site) Inflow Area = 1.750 ac, 0.00% Impervious, Inflow Depth > 3.85" for 10-Year event Inflow = 7.01 cfs @ 12.14 hrs, Volume= 0.562 of Primary = 7.01 cfs @ 12.14 hrs, Volume= 0.562 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs ■ 1WM— ■ Primary Keswick Hall_PreDev Prepared by Timmons G NOAA 24-hr D 10-Year Rainfall=5.35" Printed 9/9/2021 Summary for Link 12L: Area 2 Combined (Pre On+Off-site) Inflow Area = 0.940 ac, 0.00% Impervious, Inflow Depth > 3.90" for 10-Year event Inflow = 3.68 cfs @ 12.14 hrs, Volume= 0.306 of Primary = 3.68 cfs @ 12.14 hrs, Volume= 0.306 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link 12L: Area 2 Combined (Pre On+Off-site) Hydrograph ■ Inflow ■ Primary Time (hours) 1S Post Area 1 Total Post Area 1 Subcat Reach Aon Llnk 3S O 5S Post Area (Onsite, P t Area 2 (Ofisite) P tArea2b(Onslte, Data ad untletainetl) 6PL UGU 8L Total Post Area 2 Keswick Hall_PostDev Type 1124-hr 1-YR Rainfall=2.92" Prepared by Timmons Group Printed 9/9/2021 HydroCADO 10.10-4a s/n 06538 © 2020 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, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Post Area 1 (Onsite) Runoff Area=0.810 ac 0.00% Impervious Runoff Depth>1.99" Tc=6.0 min CN=91 Runoff=2.70 cfs 0.135 of Subcatchment 3S: Post Area 2a (Onsite, Runoff Area=0.600 ac 0.00% Impervious Runoff Depth>2.27" Tc=6.0 min CN=94 Runoff=2.20 cfs 0.114 of Subcatchment 4S: Post Area 2 (Offsite) Runoff Area=1.160 ac 0.00% Impervious Runoff Depth>1.38" Flow Length=126' Tc=9.3 min CN=83 Runoff=2.50 cfs 0.133 of Subcatchment 5S: Post Area 2b (Onsite, Runoff Area=0.120 ac 0.00% Impervious Runoff Depth>1.25" Tc=6.0 min CN=81 Runoff=0.26 cfs 0.013 of Pond 6P: UGD Peak Elev=429.94' Storage=0.079 of Inflow=4.58 cfs 0.247 of Outflow=1.03 cfs 0.246 of Link 7L: Total Post Area 1 Inflow=2.70 cfs 0.135 of Primary=2.70 cfs 0.135 of Link 8L: Total Post Area 2 Inflow=1.15 cfs 0.258 of Primary=1.15 cfs 0.258 of Total Runoff Area = 2.690 ac Runoff Volume = 0.394 of Average Runoff Depth = 1.76" 100.00% Pervious = 2.690 ac 0.00% Impervious = 0.000 ac Keswick Hall_PostDev Prepared by Timmons Gi Type 1124-hr 1-YR Rainfall=2.92" Printed 9/9/2021 Summary for Subcatchment 1S: Post Area 1 (Onsite) Runoff = 2.70 cfs @ 11.97 hrs, Volume= 0.135 af, Depth> 1.99" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 1-YR Rainfall=2.92" Area (ac) CN Description 0.810 91 CN - VRRM Spreadsheet 0.810 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 1S: Post Area 1 (Onsite) Hydrograph 3 z 70 d, Type II 24-hr 1-YR Rainfall=2.92" Runoff Area=0.810 ac 2 Runoff Volume=0.135 of Runoff Depth>1.99" Tc=6.0 min CN=91 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) ❑ RunoH Keswick Hall_PostDev Prepared by Timmons Gi Type 1124-hr 1-YR Rainfall=2.92" Printed 9/9/2021 Summary for Subcatchment 3S: Post Area 2a (Onsite, Detained) Runoff = 2.20 cfs @ 11.96 hrs, Volume= 0.114 af, Depth> 2.27" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 1-YR Rainfall=2.92" Area (ac) CN Description 0.600 94 CN - VRRM Spreadsheet 0.600 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 3S: Post Area 2a (Onsite, Detained) Hydrograph ❑ Runoff 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) Keswick Hall_PostDev Prepared by Timmons Gi Type 1124-hr 1-YR Rainfall=2.92" Summary for Subcatchment 4S: Post Area 2 (Offsite) Runoff = 2.50 cfs @ 12.01 hrs, Volume= 0.133 af, Depth> 1.38" Printed 9/9/2021 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 1-YR Rainfall=2.92" Area (ac) CN 1.160 83 >75% Grass cover, Good, HSG D 1.160 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 9.2 100 0.0530 0.18 Sheet Flow, Grass: Dense n= 0.240 P2= 3.54" 0.1 26 0.2300 7.72 Shallow Concentrated Flow, Unoaved Kv= 16.1 fos 9.3 126 Total L° u Subcatchment 4S: Post Area 2 (Offsite) Hydrograph Time (hours) O Runoff Keswick Hall_PostDev Prepared by Timmons Gi Type 1124-hr 1-YR Rainfall=2.92" Printed 9/9/2021 Summary for Subcatchment 5S: Post Area 2b (Onsite, undetained) Runoff = 0.26 cfs @ 11.98 hrs, Volume= 0.013 af, Depth> 1.25" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 1-YR Rainfall=2.92" Area (ac) CN Description 0.120 81 0.120 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 5S: Post Area 2b (Onsite, undetained) Hydrograph 1 1 1 1 1 1 1 1 1 1 1 1 1 /I 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) ■ Rurwff Keswick Hall_PostDev Prepared by Timmons Gi Summary for Pond 6P: UGD Type 1124-hr 1-YR Rainfall=2.92" Printed 9/9/2021 Inflow Area = 1.760 ac, 0.00% Impervious, Inflow Depth > 1.68" for 1-YR event Inflow = 4.58 cfs @ 11.99 hrs, Volume= 0.247 of Outflow = 1.03 cfs @ 12.20 hrs, Volume= 0.246 af, Atten= 77%, Lag= 12.9 min Primary = 1.03 cfs @ 12.20 hrs, Volume= 0.246 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 429.94' @ 12.20 hrs Surf.Area= 0.038 ac Storage= 0.079 of Plug -Flow detention time= 30.1 min calculated for 0.246 of (100% of inflow) Center -of -Mass det. time= 27.4 min ( 840.5 - 813.1 ) Volume Invert Avail.Storage Storage Description #1 427.25' 0.182 of 72.0" Round CMP Round 72" L= 280.0' Device Routing Invert Outlet Devices #1 Primary 427.25' 15.0" Round Culvert L= 158.3' CMP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 427.25' / 418.00' S= 0.0584 '/' Cc= 0.900 n= 0.010, Flow Area= 1.23 sf #2 Device 1 427.25' 5.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 430.00' 7.0" W x 4.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads MPrimary OutFlow Max=1.03 cfs @ 12.20 hrs HW=429.94' (Free Discharge) L1=Culvert (Passes 1.03 cfs of 6.70 cfs potential flow) �2=Orifice/Grate (Orifice Controls 1.03 cfs @ 7.58 fps) 3=Orifice/Grate ( Controls 0.00 cfs) Keswick Hall_PostDev Prepared by Timmons Gr Pond 6P: UGD Hydrograph Time (hours) Type 11 24-hr 1-YR Rainfall=2.92" Printed 9/9/2021 ❑ INlow ❑ Primary Keswick Hall_PostDev Prepared by Timmons Gi Type 1124-hr 1-YR Rainfall=2.92" Printed 9/9/2021 Summary for Link 7L: Total Post Area 1 Inflow Area = 0.810 ac, 0.00% Impervious, Inflow Depth > 1.99" for 1-YR event Inflow = 2.70 cfs @ 11.97 hrs, Volume= 0.135 of Primary = 2.70 cfs @ 11.97 hrs, Volume= 0.135 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link 7L: Total Post Area 1 Hydrograph ■ Inflow ■ Primary Time (hours) Keswick Hall_PostDev Prepared by Timmons GI Type 1124-hr 1-YR Rainfall=2.92" Printed 9/9/2021 Summary for Link 8L: Total Post Area 2 Inflow Area = 1.880 ac, 0.00% Impervious, Inflow Depth > 1.65" for 1-YR event Inflow = 1.15 cfs @ 12.02 hrs, Volume= 0.258 of Primary = 1.15 cfs @ 12.02 hrs, Volume= 0.258 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link 8L: Total Post Area 2 Hydrograph ■ Inflow ■ Primary Time (hours) Keswick Hall_PostDev Type/1 24-hr 2-YR Rainfall=3.54" Prepared by Timmons Group Printed 9/9/2021 HydroCADO 10.10-4a s/n 06538 © 2020 HydroCAD Software Solutions LLC Page 11 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Post Area 1 (Onsite) Runoff Area=0.810 ac 0.00% Impervious Runoff Depth>2.58" Tc=6.0 min CN=91 Runoff=3.43 cfs 0.174 of Subcatchment 3S: Post Area 2a (Onsite, Runoff Area=0.600 ac 0.00% Impervious Runoff Depth>2.87" Tc=6.0 min CN=94 Runoff=2.74 cfs 0.144 of Subcatchment 4S: Post Area 2 (Offsite) Runoff Area=1.160 ac 0.00% Impervious Runoff Depth>1.89" Flow Length=126' Tc=9.3 min CN=83 Runoff=3.41 cfs 0.183 of Subcatchment 5S: Post Area 2b (Onsite, Runoff Area=0.120 ac 0.00% Impervious Runoff Depth>1.74" Tc=6.0 min CN=81 Runoff=0.36 cfs 0.017 of Pond 6P: UGD Peak Elev=430.60' Storage=0.104 of Inflow=6.00 cfs 0.326 of Outflow=1.78 cfs 0.325 of Link 7L: Total Post Area 1 Inflow=3.43 cfs 0.174 of Primary=3.43 cfs 0.174 of Link 8L: Total Post Area 2 Inflow=1.85 cfs 0.342 of Primary=1.85 cfs 0.342 of Total Runoff Area = 2.690 ac Runoff Volume = 0.517 of Average Runoff Depth = 2.31" 100.00% Pervious = 2.690 ac 0.00% Impervious = 0.000 ac Keswick Hall_PostDev Prepared by Timmons Gi Type/1 24-hr 2-YR Rainfall=3.54" Printed 9/9/2021 Summary for Subcatchment 1S: Post Area 1 (Onsite) Runoff = 3.43 cfs @ 11.97 hrs, Volume= 0.174 af, Depth> 2.58" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 2-YR Rainfall=3.54" Area (ac) CN Description 0.810 91 CN - VRRM Spreadsheet 0.810 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 1S: Post Area 1 (Onsite) Hydrograph ❑ RunoH 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) Keswick Hall_PostDev Prepared by Timmons Gi Type/1 24-hr 2-YR Rainfall=3.54" Printed 9/9/2021 Summary for Subcatchment 3S: Post Area 2a (Onsite, Detained) Runoff = 2.74 cfs @ 11.96 hrs, Volume= 0.144 af, Depth> 2.87" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 2-YR Rainfall=3.54" Area (ac) CN Description 0.600 94 CN - VRRM Spreadsheet 0.600 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 3S: Post Area 2a (Onsite, Detained) Hydrograph ❑ Runoff 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) Keswick Hall_PostDev Prepared by Timmons Gi Type/1 24-hr 2-YR Rainfall=3.54" Printed 9/9/2021 Summary for Subcatchment 4S: Post Area 2 (Offsite) Runoff = 3.41 cfs @ 12.01 hrs, Volume= 0.183 af, Depth> 1.89" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 2-YR Rainfall=3.54" Area (ac) CN Description ' 1.160 83 >75% Grass cover, Good, HSG D 1.160 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 9.2 100 0.0530 0.18 Sheet Flow, Grass: Dense n= 0.240 P2= 3.54" 0.1 26 0.2300 7.72 Shallow Concentrated Flow, Unoaved Kv= 16.1 fos 9.3 126 Total 31 Subcatchment 4S: Post Area 2 (Offsite) Hydrograph I ' K 9 1 2 3 4 5 6 7 8 9 19 11 12 13 14 15 16 17 18 19 29 21 22 23 24 Time (hours) p Runoff Keswick Hall_PostDev Prepared by Timmons Gi Type/1 24-hr 2-YR Rainfall=3.54" Printed 9/9/2021 Summary for Subcatchment 5S: Post Area 2b (Onsite, undetained) Runoff = 0.36 cfs @ 11.97 hrs, Volume= 0.017 af, Depth> 1.74" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 2-YR Rainfall=3.54" Area (ac) CN Description 0.120 81 0.120 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 5S: Post Area 2b (Onsite, undetained) Hydrograph ■ Runoff 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) Keswick Hall_PostDev Prepared by Timmons Gi Summary for Pond 6P: UGD Type 1l 24-hr 2-YR Rainfall=3.54" Printed 9/9/2021 Inflow Area = 1.760 ac, 0.00% Impervious, Inflow Depth > 2.22" for 2-YR event Inflow = 6.00 cfs @ 11.99 hrs, Volume= 0.326 of Outflow = 1.78 cfs @ 12.16 hrs, Volume= 0.325 af, Atten= 70%, Lag= 10.5 min Primary = 1.78 cfs @ 12.16 hrs, Volume= 0.325 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 430.60' @ 12.16 hrs Surf.Area= 0.038 ac Storage= 0.104 of Plug -Flow detention time= 31.4 min calculated for 0.324 of (99% of inflow) Center -of -Mass det. time= 29.0 min ( 835.3 - 806.2 ) Volume Invert Avail.Storage Storage Description #1 427.25' 0.182 of 72.0" Round CMP Round 72" L= 280.0' Device Routing Invert Outlet Devices #1 Primary 427.25' 15.0" Round Culvert L= 158.3' CMP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 427.25' / 418.00' S= 0.0584 '/' Cc= 0.900 n= 0.010, Flow Area= 1.23 sf #2 Device 1 427.25' 5.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 430.00' 7.0" W x 4.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads MPrimary OutFlow Max=1.77 cfs @ 12.16 hrs HW=430.59' (Free Discharge) L1=Culvert (Passes 1.77 cfs of 7.69 cfs potential flow) �2=Orifice/Grate (Orifice Controls 1.16 cfs @ 8.53 fps) 3=Orifice/Grate (Orifice Controls 0.61 cfs @ 3.13 fps) Keswick Hall_PostDev Prepared by Timmons Gr Pond 6P: UGD Hydrograph Type 11 24-hr 2-YR Rainfall=3.54" Printed 9/9/2021 ■ Inflow Of Primary 111,1,111 111,1,111,1I 1'11"111111 1 11 ® 1'11„111111 �1��W111 r , Keswick Hall_PostDev Prepared by Timmons Gi Type/1 24-hr 2-YR Rainfall=3.54" Printed 9/9/2021 Summary for Link 7L: Total Post Area 1 Inflow Area = 0.810 ac, 0.00% Impervious, Inflow Depth > 2.58" for 2-YR event Inflow = 3.43 cfs @ 11.97 hrs, Volume= 0.174 of Primary = 3.43 cfs @ 11.97 hrs, Volume= 0.174 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link 7L: Total Post Area 1 Hydrograph ■ hifim— ■ Primary Time (hours) Keswick Hall_PostDev Prepared by Timmons GI Type/1 24-hr 2-YR Rainfall=3.54" Printed 9/9/2021 Summary for Link 8L: Total Post Area 2 Inflow Area = 1.880 ac, 0.00% Impervious, Inflow Depth > 2.19" for 2-YR event Inflow = 1.85 cfs @ 12.14 hrs, Volume= 0.342 of Primary = 1.85 cfs @ 12.14 hrs, Volume= 0.342 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link 8L: Total Post Area 2 Hydrograph ■ Inflow e Primary Time (hours) Keswick Hall_PostDev Type/1 24-hr 10-YR Rainfall=5.35" Prepared by Timmons Group Printed 9/9/2021 HydroCADO 10.10-4a s/n 06538 © 2020 HydroCAD Software Solutions LLC Page 20 Time span=0.00-24.00 hrs, dt=0.05 hrs, 481 points Runoff by SCS TR-20 method, UH=SCS, Weighted-CN Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method Subcatchment 1S: Post Area 1 (Onsite) Runoff Area=0.810 ac 0.00% Impervious Runoff Depth>4.32" Tc=6.0 min CN=91 Runoff=5.57 cfs 0.292 of Subcatchment 3S: Post Area 2a (Onsite, Runoff Area=0.600 ac 0.00% Impervious Runoff Depth>4.65" Tc=6.0 min CN=94 Runoff=4.30 cfs 0.232 of Subcatchment 4S: Post Area 2 (Offsite) Runoff Area=1.160 ac 0.00% Impervious Runoff Depth>3.49" Flow Length=126' Tc=9.3 min CN=83 Runoff=6.19 cfs 0.337 of Subcatchment 5S: Post Area 2b (Onsite, Runoff Area=0.120 ac 0.00% Impervious Runoff Depth>3.29" Tc=6.0 min CN=81 Runoff=0.67 cfs 0.033 of Pond 6P: UGD Peak Elev=433.15' Storage=0.181 of Inflow=10.27 cfs 0.569 of Outflow=3.18 cfs 0.564 of Link 7L: Total Post Area 1 Inflow=5.57 cfs 0.292 of Primary=5.57 cfs 0.292 of Link 8L: Total Post Area 2 Inflow=3.37 cfs 0.597 of Primary=3.37 cfs 0.597 of Total Runoff Area = 2.690 ac Runoff Volume = 0.894 of Average Runoff Depth = 3.99" 100.00% Pervious = 2.690 ac 0.00% Impervious = 0.000 ac Keswick Hall_PostDev Prepared by Timmons Gi Type/1 24-hr 10-YR Rainfall=5.35" Printed 9/9/2021 Summary for Subcatchment 1S: Post Area 1 (Onsite) Runoff = 5.57 cfs @ 11.96 hrs, Volume= 0.292 af, Depth> 4.32" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 10-YR Rainfall=5.35 Area (ac) CN Description 0.810 91 CN - VRRM Spreadsheet 0.810 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 1S: Post Area 1 (Onsite) Hydrograph ❑ RunoH 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) Keswick Hall_PostDev Prepared by Timmons Gi Type/1 24-hr 10-YR Rainfall=5.35" Printed 9/9/2021 Summary for Subcatchment 3S: Post Area 2a (Onsite, Detained) Runoff = 4.30 cfs @ 11.96 hrs, Volume= 0.232 af, Depth> 4.65" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 10-YR Rainfall=5.35 Area (ac) CN Description 0.600 94 CN - VRRM Spreadsheet 0.600 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Subcatchment 3S: Post Area 2a (Onsite, Detained) Hydrograph ❑ Runoff 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 Time (hours) Keswick Hall_PostDev Prepared by Timmons Gi Type/1 24-hr 10-YR Rainfall=5.35" Summary for Subcatchment 4S: Post Area 2 (Offsite) Runoff = 6.19 cfs @ 12.00 hrs, Volume= 0.337 af, Depth> 3.49" Printed 9/9/2021 Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 10-YR Rainfall=5.35 Area (ac) CN 1.160 83 >75% Grass cover, Good, HSG D 1.160 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 9.2 100 0.0530 0.18 Sheet Flow, Grass: Dense n= 0.240 P2= 3.54" 0.1 26 0.2300 7.72 Shallow Concentrated Flow, Unoaved Kv= 16.1 fos 9.3 126 Total Subcatchment 4S: Post Area 2 (Offsite) Hydrograph Time (hours) ■ Rurwff Keswick Hall_PostDev Prepared by Timmons Gi Type/1 24-hr 10-YR Rainfall=5.35" Printed 9/9/2021 Summary for Subcatchment 5S: Post Area 2b (Onsite, undetained) Runoff = 0.67 cfs @ 11.97 hrs, Volume= 0.033 af, Depth> 3.29" Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Type II 24-hr 10-YR Rainfall=5.35 Area (ac) CN Description ' 0.120 81 0.120 100.00% Pervious Area Tc Length Slope Velocity Capacity Description (min) (feet) (ft/ft) (ft/sec) (cfs) 6.0 Direct Entry, Q Subcatchment 5S: Post Area 2b (Onsite, undetained) Hydrograph ■■■■■■■ III■■ .■ • . 1 0 _ • • _ No ■■■■■■■■ "® ■■■■■■■■ , I �I, ■■■■■■■■ ■■■■■■■■ ■■■■■■■■ ■■■■■■■■ ■■■■■■■■ ■■■■■■■■■■ ■■■....■ .■■■■■■■■ ■■■.■■■■■..,,,.,,,,,,._... 0. 1. .2. 3. 4 .5. 5. .7. 8. 0 .10 .11 12 13 14 .15 .16 17 13. 1,0 20 .21 22 23. 24 Time (hours) ■ Runott Keswick Hall_PostDev Prepared by Timmons Gi Type/1 24-hr 10-YR Rainfall=5.35" Summary for Pond 6P: UGD Printed 9/9/2021 Inflow Area = 1.760 ac, 0.00% Impervious, Inflow Depth > 3.88" for 10-YR event Inflow = 10.27 cfs @ 11.99 hrs, Volume= 0.569 of Outflow = 3.18 cfs @ 12.14 hrs, Volume= 0.564 af, Atten= 69%, Lag= 9.0 min Primary = 3.18 cfs @ 12.14 hrs, Volume= 0.564 of Routing by Stor-Ind method, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs / 2 Peak Elev= 433.15' @ 12.14 hrs Surf.Area= 0.010 ac Storage= 0.181 of Plug -Flow detention time= 36.3 min calculated for 0.564 of (99% of inflow) Center -of -Mass det. time= 30.7 min ( 823.1 - 792.4 ) Volume Invert Avail.Storage Storage Description #1 427.25' 0.182 of 72.0" Round CMP Round 72" L= 280.0' Device Routing Invert Outlet Devices #1 Primary 427.25' 15.0" Round Culvert L= 158.3' CMP, projecting, no headwall, Ke= 0.900 Inlet / Outlet Invert= 427.25' / 418.00' S= 0.0584 '/' Cc= 0.900 n= 0.010, Flow Area= 1.23 sf #2 Device 1 427.25' 5.0" Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads #3 Device 1 430.00' 7.0" W x 4.0" H Vert. Orifice/Grate C= 0.600 Limited to weir flow at low heads MPrimary OutFlow Max=3.18 cfs @ 12.14 hrs HW=433.13' (Free Discharge) L1=Culvert (Passes 3.18 cfs of 10.70 cfs potential flow) �2=Orifice/Grate (Orifice Controls 1.56 cfs @ 11.47 fps) 3=Orifice/Grate (Orifice Controls 1.61 cfs @ 8.29 fps) Keswick Hall_PostDev Prepared by Timmons Gr Pond 6P: UGD Hydrograph Time (horns) Type 1124-hr 10-YR Rainfall=5.35" Printed 9/9/2021 ■ 1-flM— ■ Primary Keswick Hall_PostDev Prepared by Timmons GI Type/1 24-hr 10-YR Rainfall=5.35" Printed 9/9/2021 Summary for Link 7L: Total Post Area 1 Inflow Area = 0.810 ac, 0.00% Impervious, Inflow Depth > 4.32" for 10-YR event Inflow = 5.57 cfs @ 11.96 hrs, Volume= 0.292 of Primary = 5.57 cfs @ 11.96 hrs, Volume= 0.292 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link 7L: Total Post Area 1 Hydrograph ■ Inflow ■ Primary Time (hours) Keswick Hall_PostDev Prepared by Timmons Gi Type/1 24-hr 10-YR Rainfall=5.35" Printed 9/9/2021 Summary for Link 8L: Total Post Area 2 Inflow Area = 1.880 ac, 0.00% Impervious, Inflow Depth > 3.81" for 10-YR event Inflow = 3.37 cfs @ 12.11 hrs, Volume= 0.597 of Primary = 3.37 cfs @ 12.11 hrs, Volume= 0.597 af, Atten= 0%, Lag= 0.0 min Primary outflow = Inflow, Time Span= 0.00-24.00 hrs, dt= 0.05 hrs Link 8L: Total Post Area 2 Hydrograph ■ Inflow ■ Primary Time (hours) Project Narrative: This project includes the demolition of an existing parking spaces, pool building, and pool deck and the construction of new pool building, pool deck, parking and associated utilities. Erosion & Sediment Control Limits of Disturbance is 1.75. An area of 1.53 acres was used for water quality and quantity calculations. Water Quality Compliance: The disturbed area of 1.53 acres was used for the water quality analysis. In the proposed condition there will be 0.47 acres of managed turf, 1.07 acres of impervious cover. The required phosphorus removal is 0.76 lb/yr. Approximately 0.50 lb/yr of phosphorus shall be removed through the installation of permeable pavement. The remaining 0.26 lb/yr will be purchased from an offsite nutrient credit bank. Water Quantity Compliance: Stormwater Quantity requirements for analysis point 1 are met utilizing a reduction in area to comply with channel and flood protection requirements. Stormwater Quantity requirements for analysis point 2 are met utilizing a CMP detention system located within the parking area. Energy balance and channel projection for the analysis point are incompliance with all requirements.