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HomeMy WebLinkAboutWPO201600006 Study WPO VSMP 2016-01-21 Hydrograph Summary Report Hydraflow Hydrographs by Intelisolve v9.2 Hyd. Hydrograph Peak Time Time to Hyd. Inflow Maximum Total Hydrograph No. type flow interval peak volume hyd(s) elevation strge used description (origin) (cfs) (min) (min) (cuft) (ft) (cuft) 1 Rational 1.980 1 5 793 ---- ----- Pre Development 2 Rational 1.802 1 5 722 ---- Post Development New.gpw Return Period: 1 Year Thursday, Jan 21, 2016 Hydrograph Re ort 2 Rep Hydraflow Hydrographs by Intelisolve v9.2 Thursday,Jan 21,2016 Hyd. No. 1 Pre Development Hydrograph type = Rational Peak discharge = 1.980 cfs Storm frequency = 1 yrs Time to peak = 0.08 hrs Time interval = 1 min Hyd. volume = 793 cuft Drainage area = 0.520 ac Runoff coeff. = 0.89* Intensity = 4.279 in/hr Tc by User = 5.00 min IDF Curve = Charlottesville 1 SW_Current.IDF Asc/Rec limb fact = 1/1.67 *Composite(Area/C)=[(0.010 x 0.30)+(0.510 x 0.90)]/0.520 Pre Development Q (cfs) Hyd. No. 1 -- 1 Year Q (cfs) 2.00 2.00 1.00 1.00 0.00 0.00 0.0 0.0 0.0 0.1 0.1 0.1 0.1 0.1 0.1 0.2 0.2 0.2 0.2 0.2 Time (hrs) - Hyd No. 1 ReHydrograph orf 3 p Hydraflow Hydrographs by Intelisolve v9.2 Thursday,Jan 21,2016 Hyd. No. 2 Post Development Hydrograph type = Rational Peak discharge = 1.802 cfs Storm frequency = 1 yrs Time to peak = 0.08 hrs Time interval = 1 min Hyd. volume = 722 cuft Drainage area = 0.520 ac Runoff coeff. = 0.81* Intensity = 4.279 in/hr Tc by User = 5.00 min IDF Curve = Charlottesville 1 SW_Current.IDF Asc/Rec limb fact = 1/1.67 *Composite(Area/C)=[(0.075 x 0.30)+(0.445 x 0.90)]/0.520 Post Development Q (cfs) Hyd. No. 2-- 1 Year Q (cfs) 2.00 2.00 1.00 1.00 0.00 0.00 0.0 0.0 0.0 0.1 0.1 0.1 0.1 0.1 0.1 0.2 0.2 0.2 0.2 0.2 Hyd No. 2 Time(hrs) VSMP Water Quantity Compliance Energy Balance Equation: Ql-yr-Developed<I.F.*Q1-yr-Pre-developed*(RV1-yr-Pre-Developed/RV1-yr-Developed) I.F. =Improvement Factor(0.8 for sites> 1 ac or 0.9 for sites< 1 acre) Q1-yr-Developed= 1-yr Post-Developed flow rate (cfs) Qi-yr-Pre-developed= 1-yr Pre-Developed flow rate (cfs) RVl-yr-Pre-Developed= Pre-Developed Runoff Volume(cf) RV1-yr-developed=Post-Developed Runoff Volume(cf) Ql-yr-Developed= 1.802 cfs Q1-yr-Pre-developed= 1.98 cfs RV1-yr-Pre-Developed= 793 cf RV1-yr-Developed= 722 cf Area= 0.52 ac I.F. = 0.9 Qi-yr-Developed 5 I.F.*Q1-yr-Pre-developed*(RV1-yr-Pre-Developed/RV1-yr-Developed) I 1.802 < 1.96 4,:i;rvio INIPIIiisof Virginia Runoff Reduction Method ReDevelopment Worksheet-v2.8-June 2014 To be used w/2011 BMP Standards and Specifications Site Data i Project Name: Sentara Martha Jefferson Helipad Date:1/21/16 data input cells l calculation cells -- constant values Post-ReDevelopment Project&Land Cover Information Total Disturbed Acreage Constants - - Annual Rainfall(inches) MWOr_ -- Target EMC)mg(nches) rr Target TaPhosphorus EMC s Taiq Nitrogen EMC(mWL). 1.88 �- p tget Load(tb/acre/yr) 0 41 Pl0 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 0.01 0.00 0.00 0.01 Impervious Cover(acres) 0.00 0.51 0.00 0.00 0.51 _ Total 0.52 Post-ReDevelopment Land Cover(acres) _ A sods B Sods 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 ' 0.08 0.00 0.00 0.08 Impervious Cover(acres) 000 .45 0.00 0.00 0.45 Total 0.52 Area Check Okay 4._. 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 ForesUOpen Space Forest/Open Space Cover(acres) 0.00 0.00 Cover(acres) 0.00 Composite Composite Rv(forest) 0.00 0.00 Rv(forest) 0.00 %Forest 0% 0% %Forest 0% Managed Turf Managed Turf Cover(acres) 0.01 0.01 Cover(acres) 0.08 Composite Rv(turf) 0.20 0.20, Composite Rv(turf) 0.20 %Managed Turf 2% 2% %Managed Turf 14% ReDev.Impervious Impervious Cover(acres) 0.51 0.51 Cover(acres) 0.45 _ New Impervious Cover(acres) 0.00 Rv(impervious) 0 95 0.95 Rv(impervious) 0.95 Rv(impervious) 0.95 %Impervious 98% 98% %Impervious 86% %Impervious Check Area Total ReDev.Site Total Site Area(acres) 0.52 0.52 Area(acres) 0.52 Total New Dev.Site Ansa(acres) 0.00 Site Rv 0.94 0.94 ReDev.Site Rv 0.84 New Dor-Site Rv 0.95 Post- ReDevelopment Treatment Volume Post-Development Treatment Pre-Development Treatment Volume(acre-ft) 0.0405 0.0405 (acre-ft) 0.0365 Volume(acre-ft) 0 0000 Post ReDevelopment Pre-Development Treatment Volume(cubic Treatment Volume Post-Development Treatment fes) 1,766 1,766 (cubic feet) 1.589 Volume(cubic feet) 0 ReDevelopment Pre-Development Load(TP)(lb/yr) 1.11 1.11 Load(TP)(Ib/yr) 1.00 Post-Development Load(TP)(Ib/yr) 0.00 'Adjusted Land Cover Summary reflects the pm redevelopment Maximum%Reduction Required Below land cover minus the pervious land cover(forest/open space or Pre-ReDevelopment Load 10% managed turf)acreage proposed for new impervious cover. The 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 reduction requnement for the new impervious cover to meet the new Pe Area(lb/yr) 0.00 New Impervious Area orb/yr) 0.00 development load limit is computed in Column I. l - - Total Load Reduction Required -_..._. (lb/yr) 0.00 Pm-Development Load(TN)(lb/yr) Post-Development Load(TN)(Ib/yr)J 7.14 Site Results D.A.A D.A.B D.A.C D.A.D D.A.E AREA CHECK IMPERVIOUS COVER 0.00 0.00 0.00 0.00 0.00 OK. IMPERVIOUS COVER TREATED 0.00 0.00 0.00 0.00 0.00 OK. TURF AREA 0.00 0 00 0.00 0.00 0.00 OK. TURF AREA TREATED 0.00 0.00 0.00 0.00 0.00 OK. AREA CHECK OK. OK. OK. OK. OK. Phosphorous TOTAL PHOSPHOROUS LOAD REDUCTION REQUIRED(LB/YEAR) 0.00 - - : RUNOFF REDUCTION(cf) 0 PHOSPHOROUS LOAD REDUCTION ACHIEVED(LB/YR) 0.00 — ADJUSTED POST-DEVELOPMENT PHOSPHOROUS LOAD(TP)(Ib/yr)J -- - REMAINING PHOSPHOROUS LOAD REDUCTION(LB/YR)NEEDED[CONGRATULATIONS!!YOU EXCEEDED THE TARGET REDUCTION BY 0 LB/YEARII Nitrogen(for information purposes) RUNOFF REDUCTION(cf) 0 NITROGEN LOAD REDUCTION ACHIEVED(LB/YR) 0.00 ADJUSTED POST-DEVELOPMENT NITROGEN LOAD(TP)(Ib/yr)] 7.14