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Home My WebLink AboutWPO201900051 Correspondence 2021-07-02DEq Virginia Runoff Reduction Method Re -Development Compliance Spreadsheet -Version 3.0 02011 BMP Standards and Specifications 112013 Draft BMP Standards and Specifications Project Name: Scottsville Elementary School Addition dabinputaells ® Date: 9/5/2019 constunvalues Linear Development Project? No calculation cells Site Information Post -Development Project (Treatment Volume and Loads) Enter Total Disturbed Area (acres) 3.04 Check: BMP Design Specifications List: 2011 St & Specs Maximum reduction required F®'. Linear project? No The site's net increase in impervious cover (ac ts�Land cover areas entered correctly? Post-DevelopmentTotal disturbed area entered? Pre-ReDevelopment land Cover (acres) ASoils BSoils CSoils DSoils Totals Forest/Open Space (acres) -- undisturbetl D.10 forest/o enspace0.10 Managetl Tuff (acres) -- disturbed, graded for 2.47 rds or other turf to be mowed/man etl 2.47 Impervious Cover(acne) 047 0.47 3.04 Post -Development Land Cover (acres) ASoils BSoils cSoils DSoils Totals Forest/Open Space (acres) --undisturbed, 0.07 rotectetl forest/o space or reforeted land 0.07 Manned Tuff (acres) disturbed, graded for yards or other turf to be mowetl/man etl 1.68 Impervious Caver(acres) 1.29 Area Check OK. OK. OK. OK. • Forest/Opin Spare areas mustbe protected in accordance with the Virginia RunaRReduaian Method M�lls Constants Runoff Coefficients Rv Annual Rainfall (inches) 43 A Soils C Soils D Soils Target Rainfall Event(inches) 1.00 Forest/Open Space 0.02 0.D4 0.05 Total phosphorus(IT) EMC(mg/L) 0.26 Managed Tuff 0.15 0.22 0.25 Total Nitrogen (TN) EMC(mg/L) 1.86 Impervious Cover 0.95 0.95 0.95 ME Target TP Load (lb/acre/W) OAl Pj(unitless correction factor) 0.90 LAND COVER SUMMARY -- PRE -REDEVELOPMENT• COVER SUMMARY POST DEVELOPMENT Wnd Cover SummaOVPdA Post-ReDevelopment agagagal fond CoverSummory-Pre Land Cover Summary-Post(FinaO Lard Cover, summary -Post Pre-ReDevelopment Liven! Adjusted' Post ReDew. Is New Impervious Post -Development New lmperviaus pen pace (acres) Forest/Open s Cover 0.10 O.OJ Forest/Open Space 0.07 Forest/Open Space Cover acres Cover(acres)0.07 Weighted Rv(forion) ou 0.04 Weighted Rv(fimn s0 0.04 Weighted Rv(forest) 0.04 %Forest 3% 3% %Forest 2% %Forest 3% Managed Tuff Cover (acres) 2.47 168 Managed Tuff Cover 1.68 Managed TurfCover acre 168 Weighted Rv(turf) 0.22 0.22 Weighted Rv(turf) 0.22 Weighted Rv (turf) 0.22 %Managed Tuff 81% 76% %Managetl Tuff 55% %Managetl Tuff 76% Impervious Cover (acres) 0.47 0.47 ImperviousC r 129 ReDev. Impervious 047 New Impervious Cover 0.82 (acres) cover (acres) (acres) Rv(impervicus) 0.95 0.95 Rv(impervimo) 0.95 Rv(impervious) 0.95 Rv(impervious) 0.95 %lmperviaus 15% 21% %Impervious 42% %lmperviaus 21% Total She Area (acres) 3.04 2.22 Final Site Area (acres) 3.04 Total need. She Area acres 2M site Rv 0.33 0.37 Final Port Dew Site Rv 0.53 ReDev She Rv 037 Treatment Volume and Nutrient Load Treatment Volume and Nutrient Load Post -Development Final Post- Post-ReDevelopment Pre-ReDevelopment Treatment Volume 0.0828 0.0682 Development 0.1332 TrentmentVolume 0.0682 Treatment Volume 0.0649 (acre it) TreMmentVolume (acre -It) lacre-ft) (acre-h) Port-Development Final Port-ReDevelopment TreTreatmentPost- Pre-ReDevelopment Treatment Volume 3,608 2,873 Development 5,800 TreatmentVolume 2,973 Trentmert Volume (cubic 2,828 (cubic tent( TreMmeM Volume (cubic feet) feet) (cubic feet) mentT Pre-ReDevelopment TP Load Final Post- Port-ReDevelopment (Ib/yrl 227 1.87 Development TP Load 3.64 Load lTPl Lill d ad ( Wa Loatl lbMl 178 (lb/yr) (IbM)' PmArDevelopmwn TP Lead per acre Final Part ievelopment TP PostArDeveloparentlP (Ib/acre/yr) O75 a." Load per acre 1.20 Load per acre (lb/arre/yr) (lb/-m/yr) Baseline TP Load (IbM) Max. Reduction Required (BAl lbs/ave/yr applied to pre- redevelopment area ertluding pervious 0.91 (Below Pre- 20% land imposed for new impervious cosreQ ReDevelopment Load) 'Adjusted Land CoverSummary: TP Load Reduction TP Load Reduction Pre ReDevelopment landcoverminuspervious landcover Boresv pen sparem Required for 0.37 Required for New 1.44 managed for]) acreageproPasedfor new impervious cover. Redeveloped Area Impervious Area (ib/yr) (lb/yr) Adjustedunal acreage is consistent with PosbneDevelopmentarrimV (minus acreage of new impervious cover). Column I shows load reduction requdementfor new imyervloue cover (based on new development load limit 0.41 Ibs/acre/year). Post -Development TP Load Reduction Required (Ib/yr) 1.81 Nitrogen Loads (Informational Purposes Only) Final Post-Develapment TN Load Pre-ReDevelopment TN Load(lb/yr) 16.22 (Post-ReDevelopment&New 26.07 Impervious) (IbM) a�� sacra seems Site Results )Water quality Compliance) area a.n m.—PREEN, a—D.l a ay.l rtulsl m Col rtuly E. o. SIDE TMmmtt Volume lXal R. Runoff u. W.R. aM R By Onimp Nea vt m ale a rural Fnurynu ua naesirp "IDNEGETTTotal ox mnrx aamam IPorlmormarun vueryoseal I nmrvmseaee nme xemnem and xeemroepnne I I I Virginia Runoff Reduction Method Wora heel DEQ Virginia Runoff Reduction Method Re -Development Compliance Spreadsheet - Version 3.0 LIMP Design Specifications List: 2011 Stds & Specs Site Summary Project Title: Scottsville Elementary School Addition Date: 43713 Total Rainfall (in): 43 Total Disturbed Acreage: 3.04 Site Land Cover Summary Pre-ReDevelopment Land Cover (acres) Asoils BSoils CSolis DSoils Totals %of Total Forest/Open (acres) O. 0.00 0.10 0.00 0.10V'810so Managed Turf(acres) 0.00 0.00 2.47 0.00 2.47Impervious Cover(acres) 0.00 0.00 0.47 0.00 0.473.04 Post-ReDevelopment Land Cover (acres) Asoils !.Solis CSolis DSolis Totals %of Total Forest/Open (acres) 0.00 0.00 0.07 0.00 0.07 2 Managed Turf (acres) I coo 0.00 1.68 0.00 1.68 55 Impervious Cover (acres) 1 0.00 0.00 1.29 0.00 1.29 42 'Forest/Open Space areas must be protected in accordance with the Virginia Runoff Reduction Method 3.04 100 Site Tv and Land Cover Nutrient Loads Final Post -Development Post- Post Adjusted Pre- (Post-ReDevelopment Development & New Impervious) ReDevelopment NewImpervious) ReDevelopment Site Rv 0.53 0.37 0.95 0.37 Treatment Volume(ft) 5,800 2,973 2,828 2,973 TP Load (lb/yr) 3.64 1.87 1.78 1.87 Total TP Load Reduction Required (Ib/yr) 1.81 0.37 1.44 Final Post -Development Load (Post-ReDevelopment & New Impervious) Pre- ReDevelopment TN Load (lb/yr) 26.07 16.22 Pre- ReDevelopment Final Post -Development Post-ReDevelopment TP TP Load per acre TP Load per acre Load per acre b/acre/ r (Ib/acre/yr) (Ib/acre/yr) 0.84 1.20 0.84 Summary Print Virginia Runoff Reduction Method Worksheet Site Compliance Summary Maximum% Reduction Required Below 2M Pr ReDevelopment Load Total Runoff Volume Reduction (R) 2,705 Total TP Load Reduction Achieved (Ih/yr) 2.03 Total TN Load Reduction Achieved (Ih/yr) 15.49 Remaining Post Development TP Load (Ih/yr) 1.62 Remaining TP Load Reduction (Ih/yr) Required 0.00 '*TARGET TP REDUCTION EXCEEDED BY 0.21 LB/YEAR ** Summary Print Virginia Runoff RecJalion Method Woftheet ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ Drainage Area Summary D.A. A D.A. B DA. C DA. D D.A. E Total Forest/Open (acres) 0.02 0.05 0.00 0.00 0.00 0.07 Managed Turf(acros) 0.90 0.16 0.00 0.00 0.00 1.06 Impervious Corer(acres) 0.37 0.67 0.00 0.00 0.00 1.04 Total Area (acres) 1.29 0.88 0.00 0.00 0.00 2.17 Drainage Area Compliance Summary D.A. A DA. B DA. C D.A. D D.A. E Total TP Load Reduced Ib/ r 0.65 1.38 0.00 1 0.00 0.00 2.03 TN Load Reduced (lb/yr) 5.42 10.07 0.00 1 0.00 0.00 15.49 Summary Print Virginia Runotf Reduction Method Worksheet Runoff Volume and CN Calculations 1-yearrtorm 2-yearstorra 10-yearstorra Target Rainfall Event (in) 0.00 0.00 0.00 Drainage Areas RV&CN Drainage AreaA Drainage AreaB Drainage Ari Drainage Areal) Drainage AreaE CN 81 92 0 0 0 RR(fte) 7S 1,951 0 0 0 1-year return period RV was R0.(wzin) 0.00 0.00 0.00 0.00 0.00 RV w RR (ws-in) 0.00 0.00 0.00 0.00 0.00 M adjusted 100 100 0 0 0 2-year return period RVwo RR(wzin) 0.00 0.00 0.00 0.00 0.00 RV w RR (ws-in) 0.00 0.00 0.00 0.00 0.00 M adjustedl S00 100 0 0 0 10-year return period RVwo RR(wzin) 0.00 0.00 0.00 0.00 0.00 RV w RR (ws-in) 0.00 0.00 0.00 0.00 0.00 M adjusted 100 100 0 0 0 Summary Print