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Home My WebLink AboutWPO201500025 Calculations 2015-07-06 CMA PROPERTIES STORMWATER MANAGEMENT CALCULATIONS PACKET • Date of Calculations April 8, 2015 Revised on July 6, 2015 PREPARED BY: (c J COLLINS L6 PflVki . 200 GARRETT STREET,SUITE K CHARLOTTESVILLE,VA 22902 434.293.3719 PH 434.293.2813 FX www.collins-engineering.com SCS Method Calculations Soils Map (Source: NRCS Web Soil Survey Online Database) » . � 4' i . n�; N i.� ,...• 4,- ,,,,. ,, .:-.. ' i -it •.:— •A \idb. /,� c. , 14 :' �, w7 .40%. , - i ...N. :,......_:' afr ' . .... , :::, A;77, 7 4 Soils Table (Source: NRCS Web Soil Survey Online Database) Map Unit Legend Albemarle County,Virginia(VA003) Map Unit Map Unit Name Percent Symbol of AOI 27B Elioak loam, 2 to 7 44.0% percent slopes 27C Elioak loam, 7 to 15 48.1% percent slopes 39C Hazel loam, 7 to 15 7.8% percent slopes Totals for Area of Interest 100.0% Note: Soils' are predominantly composed of hydrologic soil type B. U.S.Department of Agriculture FL-ENG-21A Natural Resources Conservation Service 06/04 TR 55 Worksheet 2:Runoff Curve Number and Runoff Project: CMA Properties Designed By: FGM,PE Date: 7/6/2015 Location: Berkmar Drive Checked By:SRC,PE Date: 7/6/2015 Check One: Present X De X 1.Runoff curve Number(CN) Cover description Soil name and CN(weighted)= Drainage Area (Cover type,treatment,and hydrologic condition; Area Product of Calculated hydrologic group CN total product/ Description (Appendix A) percent impervious;unconnected/connected (Acres) CN x Area total area 'S'Value impervious area ratio) Impervious Areas 98 1.10 107.8 A B Woods in Good Condition 55 0.00 0.0 72.9 ' 3.71 (Present) Lawns in Good Condition(75%+Groundcover) 61 2.31 140.9 A Impervious Areas 98 0.94 92.1 (Phase I) B Woods in Good Condition 55 0.00 0.0 ' 71.2 4.05 Lawns in Good Condition(75%+Groundcover) 61 2.47 150.7 A Impervious Areas 98 2.44 239.1 (Phase I+ D Woods in Good Condition 55 0.00 0.0 87.5 1.43 Future Dev) Lawns in Good Condition(75%+Groundcover) 61 0.97 59.2 2.Runoff 1-Year Storm 2-Year Storm 10-Year Storm Drainage Area Description Frequency-years 1 2 10 n/a Rainfall,P(24 hour)-inches 3.5 3.7 5.6 n/a . Runoff,Q-inches 1.18 1.31 2.75 A (Present) Runoff,Q-inches 1.08 1.20 2.60 A(Phase I) Runoff,Q-inches 2.22 2.40 4.19 A(Phase I+Future Dev) U.S.Department of Agriculture FL-ENG-21A Natural Resources Conservation Service 06/04 TR 55 Worksheet 3:Time of Concentration(T J or Travel Time(T,) Project: CMA Properties Designed By: FGM,PE Date: 4/8/2015 Location: Berkmar Drive Checked By: FGM,PE Date: 4/8/2015 Check One: Present X Developed X Check One: T, X Tr Through subarea n/a A A A Segment ID: (Present) (Phase I) (Phase I+Future Dev) Sheet Flow:(Applicable to T ,only) Woods-Light Woods-Light Woods-Light 1 Surface description(Table 3-1) Underbrush Underbrush Underbrush 2 Manning's roughness coeff.,n(Table 3-1 0.4 0.4 0.4 3 Flow length,L(total L <100)(ft) 100 100 100 4 Two-year 24-hour rainfall,P 2(in.) 3.7 3.7 3.7 5 Land slope,s(ft/ft) 0.06 0.06 0.06 6 Compute T,=[0.007(0L)08]/P2's s°'0 0.214 I 0.214 I 0.214 1 I I I f I Shallow Concentrated Flow: 7 Surface description(paved or unpaved) Unpaved Unpaved 8 Flow Length,L(ft) 590 190 9 Watercourse slope,s(ft/ft) 0.06 0.03 10 Average velocity,V(Figure 3-1)(ft/s) 4 2.8 11 Tr=L/3600•V I 0.041 I 0.019 I I I I I I I Channel Flow: 12 doss sectional flow area,a(ft 2) • , cij T p N r 13 Wetted perimeter,P•,(ft) 5 N o m o 14 Hydraulic radius,r=a/P w(ft) € —.. m 3 �' o 2.13 w 15 Channel Slope,s(ft/ft) m a E `w 16 Manning's Roughness Coeff,n `o .. R `c a K 2/3 0 2 t N O 17 V=[1.49r s ]/n o 3 au • Cl 18 Flow length,L(ft) v c° a 19 Tr=L/3600•V I I 0.011 I 0.022 I I I I I I I 20 Watershed or subarea T,or T, (Add T,in steps 6,11 and 19) 0.255 0.244 0.237 U.S.Department of Agriculture FL-ENG-21C Natural Resources Conservation Service - 06/04 TR 55 Worksheet 4:Graphical Peak Discharge Method Project: CMA Properties Designed By: FGM,PE Date: 7/6/2015 Location: Berkmar Drive Checked By: FGM,PE Date: 7/6/2015 Check One: PresenX Developed X Drainage Area Drainage Area Drainage Area Drainage Area Drainage Area Drainage Area Drainage Area Drainage Area Drainage Area 1.Data Description Description Description Description Description Description Description Description Description A A A (Present) (Phase I) (Phase I+Future Dev) Drainage Area(Am)in miles'= 0.0053 0.0053 0.0053 Runoff curve number CN= _ 72.9 71.2 87.5 Time of concentration(Tc)= 0.26 0.24 0.24 _ Rainfall distribution type= II I I II - Pond and swamp areas spread 0 0 0 throughout the watershed= 2.Frequency-years 1 2 10 1 2 10 1 2 10 3.Rainfall,P(24 hour)-inches 3.5 3.7 5.6 3.5 3.7 5.6 3.5 3.7 5.6 4.Initial Abstraction,la-inches .0.742 0.742 0.742 0.809 0.809 0.809 0.286 0.286 0.286 5.Compute la/P 0.21 0.20 0.13 )0.23 0.22 0.14 0.08 0.08 0.05 6.Unit peak discharge,Qu-csm/in - 675 675 700 700 700 725 750 750 750 7.Runoff,Qfrom Worksheet 2-inches 1.18 1.31 2.75 1.08 1.20 2.60 2.22 2.40 4.19 8.Pond and Swamp adjustment factor,Fp 1 1 1 1 1 1 1 1 1 9.Peak Discharge,Qp-cfs Routed Through SWM Routed Through SWM where Qp=Qu Am Q Fp 4.23 4.72 10.27 Facility Facility Water Quality Calculations (For Phase I Only) Virginia Runoff Reduction Method ReDevelopment Worksheet-v2.8-June 2014 To be used wI2011 BMP Standards and Specifications Site Data Project Name:CMA Properties-Phase I of the Development Date:7/6/15 I • I data input cells , ____ _______- _ J calculation cells _ _ _ constant values Post-ReDevelopment Project&Land Cover Information Total Disturbed Acreage . 4.71 Constants Annual Rainfall(inches) 43_ Target Rainfall Event(inches) 1.00 ' Phosphorus EMC(mg/L) 0.26 Nitrogen EMC(mg/L) 1.86 Target Phosphorus Target Load(Ib/acre/yr) 0.41 Pj 0.90 Pre-ReDevelopment Land Cover(acres) _ A soils B Soils C Soils D Soils Totals Forest/Open Space(acres)-undisturbed, - . protected forest/open space or reforested land 0.00 . '0.00 - - • 0.00 0.00". 0.00 Managed Turf(acres)--disturbed,graded for _ - . - '. yards or other turf to be mowed/managed 0.00 ... ...3.61.- 0.00 0.00 3.61 Impervious Cover(acres) 0.00 1.10 0.00 0.00' 1.10 Total 4.71 , Post-ReDevelopment Land Cover(acres) A soils B Soils C Soils D Soils Totals Forest/Open Space(acres)-undisturbed, .-; ' • '" protected forest/open space or reforested land 0.00 c.- . . '0.19 0.00 • 0.00. " 0.19 Managed Turf(acres)-disturbed,graded for - .,- • , yards or other turf to be mowed/managed 0.00 • .�,• 2.79- ,. :0.00 - 0.00 2.79 Impervious Cover(acres) 0:00' 1.73 - 0.00 ' 0.00 1.73 • Total 4.71 , Area Check Okay Okay Okay Okay , Rv Coefficients A soils B Soils C Soils D Soils Forest/Open Space 0.02 0.03 0.04 0.05 Managed Turf 0.15 0.20 0.22 0.25 Impervious Cover 0.95 0.95 0.95 0.95 Land Cover Summary Listed Adjusted' Land Cover Summary Land Cover Summary Pre-ReDevelopment Post-ReDevelopment Post-ReDevelopment New Impervious Forest/Open Space ForestOpen Space Cover(acres) 0.00 0.00 Cover(acres) 0.19 Composite Composite Rv(forest) 0.00 0.00 Rv(forest) 0.03 %Forest 0% 0% %Forest 5% Managed Turf Managed Turf Cover(acres) 3.61 2.98 Cover(acres) 2.79 Composite Rv(turf) 0.20 0.20 Composite Rv(turf) 0.20 %Managed Turf 77% 73% /o Managed Turf 68% ReDev.Impervious Impervious Cover(acres) 1.10 1.10 Cover(acres) 1.10 New Impervious Cover(acres) 0.63 Rv(impervious) 0.05 0.95 Rv(impervious) 0.95 Rv(impervious) 0.95 %Impervious 23% 27% %Impervious 27% %Impervious 100% - Total ReDev.Site Total Site Area(acres) 4.71 4.08 Area(acres) 4.08 Total New Dev.Site Area(acres) 0.63 Site Rv 0.38 0.40 ReDev.Site Rv 0.39 New Dev.Site Rv 0.05 Post- ReDevelopment Treatment Volume Post-Development Treatment Pre-Development Treatment Volume(acre-ft) 0.1473 0.1368 (acre-ft) 0.1341 Volume(acre-ft) 0.0499 Post- -- - - ' ReDevelopment , Pre-Development Treatment Volume(cubic Treatment Volume Post-Development Treatment feet) 6,414 5,957 _(cubic feet) 5,840 Volume(cubic feet) 2,173 Post- ReDevelopment Pre-Development Load(TP)(lb/yr) 4.03 3.74 Load(TP)(lb/yr) 3.67 Post-Development Load(TP)(Ib/yr) 1.37 I 'Adjusted Land Cover Summary reflects the pre redevelopment Maximum%Reduction Required Below) land cover minus the pervious land cover(forest/open space or Pre-ReDevelopment Load 20% managed turf)acreage proposed for new impervious cover.The I • adjusted total acreage is consistent with the Post Redevelopment TP Load Reduction Required for TP Load Reduction Required for acreage(minus the acreage of new impervious cover).The load Redeveloped Area(Ib/yr) 0.87 New Impervious Area(lb/yr) 1.11 reduction requitement for the new impervious cover to meet the new development load limit is computed In Column I. Total Load Reduction Required (lb/yr) 1.78 Pre-Development Load(1 N)(lb/yr) 28"83 Post-Development Load(TN)(lb/yr) 38 0f • • •4a(r'reppPHo9JtlMYi9ViYl9tl�{a lRtlil•A.4P3,tl[VF4W1L�___ _ . 08,nnivP 3355111.033115 xofaoi3ax•nemoouiibno tl31 ' ICI Ill..�-ryn__t1V/3a/Iox�eiadPA___i _iiwa):jaw_xoya;11•1•0.33.1 1P,, rsa<Pao.y<oxe . ' xo ICI ` _ 0 0,(0.1083u ezn.moan..wool. • 051.1.1•:=10 10t no..em•=m 1 W. COO .0 MO 01 Il 0. me mo Imo me m - - - ma ma m0 me . 0 0 e ma 0�o ev..o•.c.w.0 w. 0„......_ - Im.O:lmsm.....0 o0 ac ma me ma 0 ...Zoe me "no o a e o me m o n MO om•w...< Im..........w.•®.0.0.0< COO ma m• m• a me m• ma 00 0 0 • s P 000 m0 .a.w,...we...va ....loom IS....1,1wm•n 01 10a10.310.04 wm.10.1.0.0 1•L.i m 11.•n r3 L..0 11 a W..w awn nw.w •.•a er 0W,a we•oy omen 1� en•fuw•wu w• m.11 ..n•r.m .._-f_T_ ur•n -'_ �_ . r•w• ewwmw -4._ bea8b ab.ulela 01Poo1luawdolan0Plsod 0 OWelon lu0mlemy eee0m,olaeaIPold u0IPn0a0YuuntlAl0db jon�-l.w+ Jwaem•wI eena no . , rS. L nwi w. S. Oto COO a Owla my 000 av 000 r i"� y eelb"'UPC! • • . •s••..".,•,...n„wo,3.,da .<o,.,3. L,wo2 .T.•13,eM„s . : 0 ,rew;r.o,w.somme..=,r.n.: 0 w lemma ammo oeno.q.a.nm see:mo..vu..eno..sow '0:fastnunxrsnt,nat lay.. osno to.. 00 w ................. WO me m. me w 11 III®®®®®®w+v.�•ww.o w.wwe�.w•++w ¢w>ess wv�nx.ww�•.. mmo me ma me a u me m. m. rc 11UIIhiIl1M ma ma mo ma sr uu..,�wQ�+wau..w•w awnlopyauny anp.y we oa mo elm. ennui.,uvt s.ono.+d Maav • Site Results • D.A.A D.A.B D.A.C D.A.D • D.A.E AREA CHECK IMPERVIOUS COVER: .rt r'S'_^;v0.04: " - C .10.00 ---C .5-'0.00 -..1.•.:,7.4_:v.0A0 Ar.XP.;:.m`. '0.00 OK. IMPERVIOUS COVER TREATED.'•:-'C'=[15`a,a10:04 -T,10.00'.::r._,3=7•-1`A0.00;� -: SE..1020.00 WM,ffiark1.12.1690.00 OK. TURF AREA.i".v 9..0.e2.28,T"• >wu d:-Ct0.00-;,= .'_.i?-•7:0.00 Y:'.."tf.;.ai0:00 410/D14.1147fcireat0.00 OK. TURF AREA TREATED.-,,r'.:I:.�-..i4.1L2.28 +:BF•.:`O.A.00 '^'.1"::0.00 :nzei.°r34::RY30:00 Mi..x=r5/ " sf:0:00 OK. AREA CHECK OK. OK. OK. OK. OK. • Phosphorous TOTAL PHOSPHOROUS LOAD REDUCTION REQUIRED(LB/YEAR)iN_r_4YS41.781 RUNOFF REDUCTION(et)PP eW C 3817 . PHOSPHOROUS LOAD REDUCTION ACHIEVED(LB/YR)LELDi::i&+.X112.77 • ADJUSTED POST-DEVELOPMENT PHOSPHOROUS LOAD(TP)(16/yr)1E4 =3,>aPz2.27I , , REMAINING PHOSPHOROUS LOAD REDUCTION(LB/YR)NEEDEDICONGRATULATIONSII YOU EXCEEDED THE TARGET REDUCTION BY 1 LB/YEARI Nitrogen(for information purposes) ' • • RUNOFF REDUCTION(0)• 71.:...EEC.3917 NITROGEN LOAD REDUCTION ACHIEVED(LB/YR)Y._'YB.._i`_J 20.23 ADJUSTED POST-DEVELOPMENT NITROGEN LOAD(TP)(16/yr)]nS, S QW.15.79) ' Virginia Runoff Reduction Method Worksheet Virginia Runoff Reduction Method ReDevelopment Worksheet-v2.8-June 2014 Site Data Summary Total Rainfall=43 inches Site Land Cover Summary A Soils B Soils C Soils D Soils Total %of Total Forest(acres) 0.00 0.19 0.00 0.00 0.19 4.03 Turf(acres) 0.00 2.79 0.00 0.00 2.79 59.24 Impervious(acres) 0.00 1.73 0.00 0.00 1.73 36.73 4.71 100.00 • Site Rv 0.47 Post Development Treatment Volume(ft) 8012 Post Development TP Load(Ib/yr) 5.03 Post Development TN Load(Ib/yr) 36.01 Total TP Load Reduction Required(Ib/yr) 1.78 Total Runoff Volume Reduction(ft') 3917 Total TP Load Reduction Achieved(Ib/yr) 3 Total TN Load Reduction Achieved(Ib/yr) 20.23 Adjusted Post Development TP Load(Ib/yr) 2.27 Remaining Phosphorous Load Reduction(Lb/yr)Required 0.00 Drainage Area Summary D.A.A D.A.B D.A.C D.A.D D.A.E Total Forest(acres) 0.19 0.00 0.00 0.00 0.00 0.19 Turf(acres) 2.28 0.00 0.00 0.00 0.00 2.28 Impervious(acres) 0.94 0.00 0.00 0.00 0.00 0.94 3.41 Drainage Area Compliance Summary D.A.A D.A.B D.A.C D.A.D D.A.E Total TP Load Red.(Ib/yr) 2.77 0.00 0.00 0.00 0.00 2.77 TN Load Red.(Ib/yr) 20.23 0.00 0.00 0.00 0.00 20.23 • • Summary Print Virginia Runoff Reduction Method Worksheet Drainage Area A Summary Land Cover Summary ASoils BSoils CSoils DSoils Total %of Total Forest(acres) 0.00 0.19 0.00 0.00 0.19 5.57 Turf(acres) 0.00 2.28 0.00 0.00 2.28 66.86 Impervious(acres) 0.00 0.94 0.00 0.00 0.94 27.57 • 3.41 BMP Selections Practice Credit Area(acres) Downstream Practice 6.b.Bioretention#2(Spec#9) Impervious: 0.94 None Turf(Pervious): 2.28 None Total Impervious Cover Treated(acres) 0.94 Total Turf Area Treated(acres) 2.28 Total TP Load Reduction Achieved in D.A.A(lb/yr) 2.77 Total TN Load Reduction Achieved in D.A.A(Ib/yr) 20.23 • Summary Print Routing Calculations (For Phase I Only) CMA Properties Biorentention Basin- Phase I BasinFlow printout INPUT: • Basin: CMA Properties- Bioretention Basin Phase I 8 Contour Areas Elevation(ft) Area(sf) Computed Vol . (cy) 484.00 10.00 0.0 486.00 260.00 7.9 488.00 783.00 44.8 490.00 1487.00 127.5 491.00 5757.00 253.1 492.00 6735.00 484.2 493.00 8921.00 773.1 494.00 10036.00 1124.0 Start_Elevation(ft) 484.00 Vol . (cy) 0.00 5 Outlet Structures Outlet structure 0 Orifice name: Low-Flow Orifice area (sf) 0.087 diameter or depth (in) 4.000 width for rect. (in) 0.000 coefficient 0.500 invert (ft) 484.000 • multiple 1 discharge into riser Outlet structure 1 Orifice name: Mid-Flow Orifices area (sf) 0.087 diameter or depth (in) 4.000 width for rect. (in) 0.000 coefficient 0.500 invert (ft) 488.000 multiple 3 discharge into riser outlet structure 2 Weir name: Riser diameter (in) 24.000 side angle 0.000 coefficient 3.300 invert (ft) 491.750 multiple 1 discharge into riser transition at (ft) 0.608 orifice coef. 0.500 orifice area (sf) 3.142 Outlet structure 3 weir name: Emergency Spillway length (ft) 25.000 side angle 0.000 coefficient 3.300 invert (ft) 492.750 multiple 1 discharge through dam Page 1 CMA Properties Biorentention Basin-, Phase I Outlet structure 4 Culvert name: Barrel multiple 1 discharge out of riser D (in) 15.000 h (in) 0.000 Length (ft) 276.000 Slope 0.005 Manning's n 0.013 Inlet coeff. Ke 0.500 Equation constant set 3 Invert (ft) 481.380 4 Inflow Hydrographs Hydrograph 0 SCS name: 1-yr 24 hr Peak SCS Method Storm Event Area (acres) 3.410 CN 71.200 Type 2 rainfall , P (in) 3.500 time of conc. (hrs) 0.2400 time increment (hrs) 0.0200 time limit (hrs) 30.000 fudge factor 1.00 routed true peak flow (cfs) 3.769 peak time (hrs) 12.002 volume (cy) 492.280 Hydrograph 1 SCS name: 2-yr 24 hr Peak SCS Method Storm Event Area (acres) 3.410 CN 71.200 Type 2 rainfall , P (in) 3.700 time of conc. (hrs) 0.2400 time increment (hrs) 0.0200 time limit (hrs) 30.000 fudge factor 1.00 routed true peak flow (cfs) 4.224 peak time (hrs) 12.002 volume (cy) 551.772 Hydrograph 2 SCS name: 10-yr 24 hr Peak SCS Method Storm Event Area (acres) 3.410 CN 71.200 Type 2 rainfall , P (in) 5.600 time of conc. (hrs) 0.2400 time increment (hrs) 0.0200 time limit (hrs) 30.000 fudge factor 1.00 routed true peak flow (cfs) 9.106 peak time (hrs) 12.002 volume (cy) 1189.521 Page 2 CMA Properties Biorentention Basin- Phase I Hydrograph 3 SCS name: 100-yr 24 hr Peak SCS Method Storm Event Area (acres) 3.410 CN 71.200 Type 2 rainfall , P (in) 9.100 time of conc. (hrs) 0.2400 time increment (hrs) 0.0200 time limit (hrs) 30.000 fudge factor 1.00 routed true peak flow (cfs) 19.534 peak time (hrs) 12.002 volume (cy) 2551.643 OUTPUT: Routing Method: storage-indication Hydrograph 0 Routing Summary of Peaks: 1-yr 24 hr Peak SCS Method Storm Event inflow (cfs) 3.767 at 12.00 (hrs) discharge (cfs) 2.028 at 12.16 (hrs) water level (ft) 489.513 at 12.16 (hrs) storage (cy) 102.430 Hydrograph 1 Routing Summary of Peaks: 2-yr 24 hr Peak SCS Method Storm Event inflow (cfs) 4.222 at 12.00 (hrs) discharge (cfs) 2.173 at 12.16 (hrs) water level (ft) 489.800 at 12.16 (hrs) storage (cy) 116.781 Hydrograph 2 Routing Summary of Peaks: 10-yr 24 hr Peak SCS Method Storm Event inflow (cfs) 9.102 at 12.00 (hrs) discharge (cfs) 2.794 at 12.24 (hrs) water level (ft) 491.303 at 12.24 (hrs) storage (cy) 319.206 Hydrograph 3 Routing Summary of Peaks: 100-yr 24 hr Peak SCS Method Storm Event inflow (cfs) 19.526 at 12.00 (hrs) discharge (cfs) 12.758 at 12.12 (hrs) water level (ft) 492.424 at 12.12 (hrs) storage (cy) 596.948 Mon Jul 06 12:54:42 EDT 2015 Page 3 Water Quality Calculations (For Phase I + 1.50ac. of Future Impervious Areas) Virginia Runoff Reduction Method ReDevelopment Worksheet-v2.8-June 2014 To be used w/2011 BMP Standards and Specifications Site Data Project Name:CMA Properties-Final Buildout Date:7/6/15 - ,data input cells _ __ _ ____ calculation cells _ constant values Post-ReDevelopment Project&Land Cover Information Total Disturbed Acreage 4.71 Constants Annual Rainfall(inches) •43 Target Rainfall Event(inches) 1.00 Phosphorus EMC(mg/L) 0.26 Nitrogen EMC(mg/L) 1.86 Target Phosphorus Target Load(Ib/acre/yr) 0.41 Pj 0.90 Pre-ReDevelopment Land Cover(acres) A soils B Soils C Soils D Soils Totals Forest/Open Space(acres)-undisturbed, protected foresVopen space or reforested land 0.00 0.00 0,00 0.00 0.00 Managed Turf(acres)-disturbed,graded for yards or other turf to be mowed/managed 0.00 3.61 .0.00 _ 0.00 3.61 Impervious Cover(acres) 0.00 - 1.10 _ - 0.00 0.00 1.10 Total 4.71 Post-ReDevelopment Land Cover(acres) A soils B Soils C Soils D Soils Totals ForestlOpen Space(acres)-undisturbed, ' - ,- - protectedforest/open space or reforested land 0.00 0.19 - 0,00 0.00 0.19 Managed Turf(acres)-disturbed,graded for 'Z yards or other turf to be mowed/managed '0,00 1.20 0.00' .. 0.00 - 1.29 Impervious Cover(acres) `0.00 - '3,23 0.00 - 0.00 3.23 Total 4.71 Area Check Okay Okay Okay Okay Rv Coefficients A soils B Soils C Soils D Soils Forest/Open Space 0.02 0.03 0.04 0.05 Managed Turf 0.15 0.20 0.22 0.25 Impervious Cover 0.95 0.95 0.95 0.95 Land Cover Summary Listed Adjusted' Land Cover Summary Land Cover Summary Pre-ReDevelopment Post-ReDevelopment Post-ReDevelopment New Impervious Forest/Open Space Forest/Open Space Cover(acres) 0.00 0.00 Cover(acres) 0.19 Composite Composite Rv(forest) 0.00 0.00 Rv(forest) 0.03 %Forest 0% 0% %Forest 7% Managed Turf Managed Turf Cover(acres) 3.61 1.48 Cover(acres) 1.29 Composite Rv(turf) 0.20 0.20 Composite Rv(turf) 0.20 %Managed Turf 77% 57% °Io Managed Turf 50% ReDev.Impervious Impervious Cover(acres) 1.10 1.10 Cover(acres) 1.10 New Impervious Cover(acres) 2.13 Rv(impervious) 0.05 0.95 Rv(impervious) 0.95 Rv(impervious) 0.95 %.Impervious 23% 43% %Impervious 43% %Impervious 100% Total ReDev.Site Total Site Area(acres) 4.71 2.58 Area(acres) 2.58 Total New Dev.Site Area(acres) 2.13 Site Rv 0.38 0.52 ReDev.Site Rv 0.51 New Dev.Site Rv 0.95 Post- ReDevelopment Treatment Volume Post-Development Treatment Pre-Development Treatment Volume(acre-ft) 0.1473 0.1118 (acre-ft) 0.1091 Volume(acre-ft) 0.1686 Post- ReDevelopment Pre-Development Treatment Volume(cubic Treatment Volume Post-Development Treatment feet) 6,414 4,868 (cubic feet) 4,751 Volume(cubic feet) 7,345 Post- ReDevelopment Pre-Development Load(TP)(lb/yr) 4.03 3.08 Load(TP)(Ib/yr) 2.98 Post-Development Load(TP)(Ib/yr) 4.62 'Adjusted Land Cover Summary reflects the pre redevelopment Maximum%Reduction Required Below land cover minus the pervious land cover(forest/open space or Pre-Redevelopment Load 20% managed turf)acreage proposed for new impervious cover.The I adjusted total acreage is consistent with the Post Redevelopment TP Load Reduction Required for TP Load Reduction Required for acreage(minus the acreage of new impervious cover).The load Redeveloped Area(Ib/yr) 0.54 New Impervious Area(lb/yr) 3.74 reduction requriement for the new impervious cover to meet the new development load limit Is computed in Column I. Total Load Reduction Required (Ib/yr) 4.28 Pre-Development Load(TN)(lb/yr) 29.83 Post-Development Load(TN)(lb/yr) 5470 ommoge areas I •i , uiie:4i:F[.e w.m,.m. t f re..r, e•er. our. e:Ga Lwh...A.. rwecoo oor•Im n-wwo.*madam*.ow.. m om poo oao 0 10 OM .1=5755•555-454.04.0.53 loom craw aloes ri pro om on o� __ mm _ __ _ w:.t a« oao « o ppp,i rt•ra 201 •uw•.pym.n n.umw ww,(ej • ApplVRonofl Roductlon Practices to Reduce Treat aPo ont Volume In eve&opmenl Load Drainage Area A , o ' n.W. u• w. m.cr.W xr.e• .n. rv.u<- ••a.rxn• vAm. �rpev.W . ,. ry rvmn,..i rbmwm w...n..•o,.•w.•rsr Emv a r e..,e.•eRm,mFe.•A mmorm.d r.fasn OM Om e e 0 0 ow •W e ow MO om Om 2015.ru up15 w,elf mseelmwoo OD no.,ay.w Baum rvl ow eW 0 n 0 0 om em am •W a eW om Om em tf 20T.Rr,a� ,.e•,m,..,em.mmmll,we w, On •ae om.r,m r•..r.e r MO f •m o 0 0 m Om oleo Om am m Ow ow •e ow xrTe.m...r.ri.i.M1nse.,ex.rwn11a0.•m rm m��e.�w..e v.s+m'rs..sa.Wle Om •m o e e n MO Om we am oe I am ow we ow W am coo eoe. ow II. 0 45 0 00 0 0 0 26 000 OM OW Om Nem 7177775. a•E..rwn.ma.M2 m., .�v.+.e.++•' nr rr.w.w.•.b.a en f OW a • • n two woo cow ow ocawocrwwwwwwwwwwws w cow.....sow pow m.o... an own*.aro.. o w etc o o o os ow see ow coo 70 0 00 ow ow ow • es wswwwwwwwW, "'".'"Ts..."' woo...wows o ea on o w 112 4 MO wor en ...N.. = Fa InOre00091 Rom., e."..n..r.n.mr,ns•.• "" °" me162.550.05550.5..0150ow - • e ]_ • ,r-I - .-__ • 4u..m r•«,.enm ..•..rnrsmr . 55.055550.0.7.05010 60,55.554,05.nonex..155 ow 0. tlul MCA 1115021501. . Paosixmus REMOVAL AM;UM 47:407umirtiicn2;=t14 •m __ Yolu�S,cFefFoJCN Nw 63:F' SEE WATER QUALITY eoupue11eEfAe Eon SITEeouceuxee utemnnpxs rm aar n€uavcT•suioasrr.TeeelwnramTewv.-.p15. s. • o • m,< w ..°w,=. n,.a°a . 3tl. a. 3aN. tl31 i 131.0110,1.. V iCal n irk/a allana......30 6.1.1.014.1' ... ": : :i l: "N,.. .I-e..tla.,,.,w,.atla m. r. �. o :moo .: .: : : 6 mo me COO .::s wdw..• , me mo s0 mo s. me me .0 WO ao 6 o roe me mo mow.. ...wr.�a....Po ...too m.n........a.. I.d�w r Wi..Ir�.m.ny o.mu. m• tl rr..> .w.an ..° owl .0.4 0.1900,e a mm r.w. an.sm. '.n.w m *co m.o..n°+ w w ..111.011 a, owm.tl � p n r. uo .v.un ....Idn.n tl•:i° e °w {I a Noa ltl9 elueln w.l°nuotltla.otlwae° oa..°w.a re.lsea...,Nddtl Site Results •• • D.A.A D.A.B D.A.C ' D.A.D D.A.E AREA CHECK IMPERVIOUS COVER -.•'2.44:",'..1,'a'$7.0.00:3"': =t 15:30.00Y�Y IA..VIi:i.0.00±:";�1�c:3"v'.if30.00 OK. IMPERVIOUS^COVER TREATED,+."__ T 2.44 •,".Z•4T: 0.00::ea+°!.•".r.11:0.00 _19119P0:00'M7o15..E AiRORS170.00 OK. TURF AREA 74.x 7.i0.78 .....T.,,:- 74'1,i;..^0.00 t%A:',S,E s90.00%5111110WirMIVI80.00 •_w.,JY EIENI0;00 OK. TURF AREA TREATED t:.-411i'.•':0.78 -:...y' S D., "S0.00;' :R1!Tj _10.00'fski:4•VIITCD4.10.00' ,n�:d_,; N0:00 OK. AREA CHECK OK. + OK. OK. OK. OK. • Phosphorous , TOTAL PHOSPHOROUS LOAD REDUCTION REQUIRED(LBIYEAR1I"SY.3➢1.1w.r^4.281 • RUNOFF REDUCTION(c/)f711, ;t'.t7184 , PHOSPHOROUS LOAD REDUCTION ACHIEVED(LB/YR) M'-v4 DA..T 5.07 ADJUSTED POST-DEVELOPMENT PHOSPHOROUS LOAD(TP)(Iblyr)l'=- TT2.53J • REMAINING PHOSPHOROUS LOAD REDUCTION(LBIYR)NEEDED'CONGRATULATIONSII YOU EXCEEDED THE TARGET REDUCTION BY 0.8 LBIYEAR,: • Nitrogen(for information purposes) • • RUNOFF REDUCTION(et)A-'"t'•_'.•,:7184 NITROGEN LOAD REDUCTION ACHIEVED(LB/YR)C„I,:`iatt_c37.09 ADJUSTED POST-DEVELOPMENT NITROGEN LOAD(TP)(Iblyr)IY:d n.Ki'.[3..17.271 Virginia Runoff Reduction Method Worksheet Virginia Runoff Reduction Method ReDevelopment Worksheet-v2.8-June 2014 Site Data Summary Total Rainfall=43 inches Site Land Cover Summary A Soils B Soils C Soils D Soils Total %of Total Forest(acres) 0.00 0.19 0.00 0.00 0.19 4.03 Turf(acres) 0.00 1.29 0.00 0.00 1.29 27.39 Impervious(acres) 0.00 3.23 0.00 0.00 3.23 68.58 4.71 100.00 Site Rv 0.71 Post Development Treatment Volume(ft') 12096 Post Development TP Load(Ib/yr) 7.60 Post Development TN Load(Ib/yr) 54.37 Total TP Load Reduction Required(Ib/yr) 4.28 'Total Runoff Volume Reduction(ft') 7184 Total TP Load Reduction Achieved(Ib/yr) 5 Total TN Load Reduction Achieved(Ib/yr) 37.09 Adjusted Post Development TP Load(Ib/yr) 2.53 Remaining Phosphorous Load Reduction(Lb/yr)Required 0.00 Drainage Area Summary D.A.A D.A.B D.A.C D.A.D D.A.E Total Forest(acres) 0.19 0.00 0.00 0.00 0.00 0.19 Turf(acres) 0.78 0.00 0.00 0.00 0.00 0.78 Impervious(acres) 2.44 0.00 0.00 0.00' 0.00 2.44 3.41 Drainage Area Compliance Summary D.A.A D.A.B D.A.C D.A.D D.A.E Total TP Load Red.(Ib/yr) 5.07 0.00 0.00 0.00 0.00 5.07 TN Load Red.(lb/yr) 37.09 0.00 0.00 0.00 0.00 37.09 Summary Print Virginia Runoff Reduction Method Worksheet Drainage Area A Summary Land Cover Summary A Soils B Soils C Soils D Soils Total %of Total Forest(acres) 0.00 0.19 0.00 0.00 0.19 5.57 Turf(acres) 0.00 0.78 0.00 0.00 0.78 22.87 Impervious(acres) 0.00 2.44 _ 0.00 0.00 2.44 71.55 3.41 BMP Selections Practice 'Credit Area(acres) Downstream Practice 6.b.Bioretention#2(Spec#9) Impervious: 2.44 None Turf(Pervious): 0.78,None Total Impervious Cover Treated(acres) 2.44 Total Turf Area Treated(acres) 0.78 Total TP Load Reduction Achieved in D.A.A(Ib/yr) 5.07 Total TN Load Reduction Achieved in D.A.A(Ib/yr) 37.09 Summary Print Routing Calculations (For Phase I + 1.50ac. of Future Impervious Areas) CMA Properties Biorentention Basin- Phase I and Fut Dev BasinFlow printout INPUT: Basin: CMA Properties- Bioretention Basin Phase I + Future Development 8 Contour Areas Elevation(ft) Area(sf) Computed vol . (cy) 484.00 10.00 0.0 486.00 260.00 7.9 488.00 783.00 44.8 490.00 1487.00 127.5 491.00 5757.00 253.1 492.00 6735.00 484.2 493.00 8921.00 773.1 494.00 10036.00 1124.0 Start_Elevation(ft) 484.00 Vol . (cy) 0.00 5 Outlet Structures Outlet structure 0 Orifice name: Low-Flow Orifice area (sf) 0.087 diameter or depth (in) 4.000 width for rect. (in) 0.000 coefficient 0.500 invert (ft) 484.000 multiple 1 discharge into riser Outlet structure 1 Orifice name: Mid-Flow Orifices area (sf) 0.087 diameter or depth (in) 4.000 width for rect. (in) 0.000 coefficient 0.500 invert (ft) 488.000 multiple 3 discharge into riser Outlet structure 2 Weir name: Riser - diameter (in) 24.000 side angle 0.000 coefficient 3.300 invert (ft) 491.750 multiple 1 discharge into riser transition at (ft) 0.608 orifice coef. 0. 500 orifice area (sf) 3.142 Outlet structure 3 Weir name: Emergency Spillway length (ft) 25.000 side angle 0.000 coefficient 3.300 invert (ft) 492.750 multiple 1 discharge through dam Page 1 CMA Properties Biorentention Basin- Phase I and Fut Dev Outlet structure 4 Culvert name: Barrel multiple 1 discharge out of riser D (in) 15.000 h (in) 0.000 Length (ft) 276.000 Slope 0.005 Manning's n 0.013 Inlet coeff. Ke 0.500 Equation constant set 3 Invert (ft) 481.380 4 Inflow Hydrographs Hydrograph 0 SCS name: 1-yr 24 hr Peak SCS Method Storm Event Area (acres) 3.410 CN 87.500 Type 2 rainfall , P (in) 3.500 time of conc. (hrs) 0.2400 time increment (hrs) 0.0200 time limit (hrs) 30.000 fudge factor 1.00 routed true peak flow (cfs) 7.801 peak time (hrs) 12.002 volume (cy) 1018.971 Hydrograph 1 SCS name: 2-yr 24 hr Peak SCS Method Storm Event Area (acres) 3.410 CN 87.500 Type 2 rainfall , P (in) 3.700 time of conc. (hrs) 0.2400 time increment (hrs) 0.0200 time limit (hrs) 30.000 fudge factor 1.00 routed true peak flow (cfs) 8.438 peak time (hrs) 12.002 volume (cy) 1102.234 Hydrograph 2 SCS name: 10-yr 24 hr Peak SCS Method Storm Event Area (acres) 3.410 CN 87.500 Type 2 rainfall , P (in) 5.600 time of conc. (hrs) 0.2400 time increment (hrs) 0.0200 time limit (hrs) 30.000 fudge factor 1.00 routed true peak flow (cfs) 14.682 peak time (hrs) 12.002 volume (cy) 1917.877 Page 2 CMA Properties Biorentention Basin- Phase I and Fut Dev Hydrograph 3 SCS name: 100-yr 24 hr Peak SCS Method Storm Event Area (acres) 3.410 CN 87.500 Type 2 rainfall , P (in) 9.100 time of conc. (hrs) 0.2400 time increment (hrs) 0.0200 time limit (hrs) 30.000 fudge factor 1.00 routed true peak flow (cfs) 26.589 peak time (hrs) 12.002 volume (cy) 3473.200 OUTPUT: Routing Method: storage-indication Hydrograph 0 Routing Summary of Peaks: 1-yr 24 hr Peak SCS Method Storm Event inflow (cfs) 7.797 at 12.00 (hrs) discharge (cfs) 2.693 at 12.22 (hrs) water level (ft) 491.028 at 12.22 (hrs) storage (cy) 259.125 Hydrograph 1 Routing Summary of Peaks: 2-yr 24 hr Peak SCS Method Storm Event inflow (cfs) 8.434 at 12.00 (hrs) discharge (cfs) 2.743 at 12.22 (hrs) water level (ft) 491.162 at 12.24 (hrs) storage (cy) 288.137 Hydrograph 2 Routing Summary of Peaks: 10-yr 24 hr Peak SCS Method Storm Event inflow (cfs) 14.676 at 12.00 (hrs) discharge (cfs) 7.449 at 12.16 (hrs) water level (ft) 492.105 at 12.16 (hrs) storage (cy) 510.681 Hydrograph 3 Routing Summary of Peaks: 100-yr 24 hr Peak SCS Method Storm Event inflow (cfs) 26.577 at 12.00 (hrs) discharge (cfs) 19.594 at 12.10 (hrs) water level (ft) 492.934 at 12.10 (hrs) storage (cy) 751.507 Mon Jul 06 12:53:09 EDT 2015 Page 3 Channel Protection Compliance 9 VAC .5 _$fr t) -66 WA:cc. Chu ctvwdEc_ 4.07EctIoN COPt? AAocc. Q.c tx-ciu eD iN x clieLe To CM/V.. oc it 'gsCA v“- 13 o(t 1.c"'rxa4 ( * ri Q rAu-S .nr.. A K0o ) VCf4.1+€0 `Ra-Q1PP ctw.wa 1/4Ar T"e/'1/4zAj'AT�s zNNMCO A'fcLY + (,c PST(L.�Arm OF A- mR.N toe C'HA►WuE:L. A ssocYi'?'ejo wart. 711K.- ,,d/�s�iz.�l�i�-t S�,JM FA cz L3 1. SECT 0,1 kVa (MwNMn�� 51-cookwAT J CoNvEYAaCE S4svei`•) si-For& xxJ svasECI*Oly MiwiA44E• STcsmvoi l'E•(L. coNveiANce S`IsVEM 51-1f1LL. CONY THE Peg('-b e.u8'1-0Pkt ivr �6At�Fcow Ram 'FROwk. C TWO^ YEA( a y-Howe. SNRM Outivr CAusaNG E(i05rc►i a Tf-€G S`ts1 � , DEiENTsQN QF S'Zia/twJVTE,Q CA. 1N-owNSTA.EAJ'-1 OvEM .iTs f'u t3 Z•Jco&Po to p AmA ) LApo- zsi-kitBza Cs• '1-v i y To jM tc,7 ,Tkss Czl-w ,,, ,, • Tom. ?wtPas WaN z,s,ca2roaA ls 0A) FAra L t i As PrS A- itm 4 4-z.Ne CitAwNEI-J t7Ac-Auto or THE 11/4+AN/4A41A, SVIK FA{T'Lz rt TtIG �Rb{�a �3 kt9 Lzi4G.0. CRANNcc. �s P si6neo To NoT- 5E. eo<•v "DvA TfiC 4-1-10,4 51.°QM s; gxtrNos To THE- UP9 K• LLmtrs (LI7a) • OF-.THE 'OOWNS<^t.Art GC.:51 rN $`WM F- zt-ar ? EASE 6 THE EX1S1's14 bo\NJJSt i;AAk tito..mA0E 4nJM rAc ni'l WAS ' RE\iarnv..sL_/ Ahepe)t 1)'-E2J' Co To BE ATEcsv"/znJ CoMPliMcE s Nay (PRQPo To 8€!. cecaNDA,vCE w FN G�NE�ILsJ,G1 5 ��vaR�iti!�c��. • SuMMA . PkoPOSh7 MANNA-s CMa 'JCL " Oa_ ° a.9H - fs 6J'i' oast CASs:. Sa.w.Ar:ta, 1$ �� tiNAL bum...N.)04e- tCouNEe.1'S egelkt,g0 FMALTry TO -%-sTv c 'FAcrLzT1) (Zas _ pvN n .o '4 , �k.aacFs d = p, 5rr . NicCE5:ci\u.cr-4cst.t kccrAsir FCfi CoA2F- 6APMEl. S S.o Accn&OANCE •'- -Th V ESCH 10 YEA, 0E7cn s5 .ALSO coNTA-rNED. a,o 0.21' Riprap Channel Complex Channnel- Riprap Channel Connecting Proposed SWM Facility to Existing SWM Facility Input: Slope 0.045 Flow (given) 2.740 line x y n 0 0.000 1.500 0.030 (first n value not used) 1 3.000 0.000 0.030 2 6.000 1.500 0.030 Output: Depth 0.570 (y) ( 0.570) Channel bed segment output: line Q V A P 1 1.37 4.22 0.32 1.27 2 1.37 4.22 0.32 1.27 Mon Jul 06 15:03:33 EDT 2015 J Page 1