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Home My WebLink AboutSDP200600109 Calculationsti ct lK f 9EA u ; " ; 1°. `,1 r=te rte, i T "... r' A . V t cirzvvE Short Version BMP Computations For worksheets 2 - 6 One Area Analysis Albemarle County Water Protection Ordinance: Modified Simple Method Westminster Canterbury Plan: 6 Duplex Replacement Water Resources Area: Upper Rivanna River Preparer: Kurt M. Gloeckner, P.E.R.L.S. Date: 25- Aug -06 Project Drainage Area Designation DA #1 L storm pollutant export in pounds, L = [P(Pj)Rv /12 ] [ C(A)2.72 ] Rv mean runoff coefficient, Rv = 0.05 + 0.009(1)Treat Total as Road Only Pj small storm correction factor, 0.9 for Ease of Analysis I percent imperviousness P annual precipitation, 43" in Albemarle A project area in acres in subject drainage area, A = 4.02 C pollutant concentration, mg /I or ppm target phosphorus Use Total Areas as Shown in f factor applied to RR Accompanying Sheets V required treatment volume in cy, 0.5' over imperv. area = A(I)43560(0.5/12)/27 RR required removal , L(post) - f x L(pre) RR removal efficiency, RR100 /L(post) Impervious Cover Computation (values in feet & square feet) Item pre - development Area post - development Area Roads Length Width subtotal Length Width subtotal 3207.6 22 70567.2 4059 22 89298 0 0 0 0 0 0 0 705671 0 89298 Driveways Length Width no. subtotal Length Width no. subtotal and walks 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 Parking Lots 1 2 3 4 1 2 3 4 0 0 0 0 1 0 0 Gravel areas Area Area 0 x0.70= 0 x0.70=0 Structures Area no. subtotal Area no. subtotal 0 0 0 0 0 0 0 0 0 0 0 0 0 Actively - grazed pasture & Area Area yards and cultivated turf x 0.08 = 0 x 0.08 =0 Active crop land Area Area 0 x0.25= 0 0 x0.25=0 Other Impervious Areas 0 0 Impervious Cover 40%51 % I(pre)I(post) Rv(post) V 0.51 137.8 New Development (For Development Areas, existing impervious cover <= 20 %) C f I (pre) * Rv(pre) L(pre) L(post) RR % RR Area Type 0.70 1.00 20% 0.41 10.18 12.56 2.38 19%Development Area 0.35 1.00 0% 0.41 5.09 6.28 1.19 19%Drinking Water Watersheds 0.40 1.00 1 % 0.41 5.82 7.18 1.36 19%Other Rural Land min. values Redevelopment (For Development Areas, existing impervious cover > 20 %) C f I (pre) * Rv(pre) L(pre) L(post) RR % RR Area Type 0.70 0.90 20% 0.41 10.18 12.56 3.39 27%Development Area 0.35 0.85 0% 0.41 5.09 6.28 1.95 31%Drinking Water Watersheds 0.40 0.85 1 % 0.41 5.82 7.18 2.23 31%Other Rural Land Interim Manual, Page 70 rev. 16 Feb 1998 GEB l , ya s ® C) S v ® o ® s + t r o6Nr t . a s 4 ® $/• aa gkA - 15, 7 5 & s A 45f 1p npMEN DRAINAGE AREA IMPERVIOUS AREA AND POROUS AREA i DUPLEX COTTAGE REPLACEME SOUTH EAST QUADRANT OF CAMPUS MINOR AMENDMEN DRAWINGNEWCOTT AGES2.DWG JOB NUMBER 9 - 7— C) 113-31 DA -1 3. 11 AC. 35. 807.5 t1 AC SO- FT- 39. 450.30 SQ. FT. 0. 81 AC. 701AL DRAINAGE AREA 175, 257,52 ACO. FT. DA -1 0. 91 AC. TOTAL DRAINAGE AREA 175, 257. 82 SOFT - 4. 02 AC. TOTAL IMPER' AOUS 70, 739. 27 SOFT. TOTAL POROU FT. 104. 51 2, 40 ACRES IMPER` ou 63. 774.34 SQ. FT, 1. 46 ACRES IMPERVIOUS 2, 661.34 SOFT. 0. 06 ACRES IMPERVIOUS 2, 493 CR6A 63, 77 .CRES IMPERVIOUS 2, 661.3 SO 0. 06 ACRES 1, 810.04 SQ. FT.2, 493.55 SQ• FT. 0. 04 ACRES 0. 06 ACRES 1. 610.04 SOFT. 0. 04 ACRES too 397 275Qa T 1. 62 ACRES TOTAL DRAINAGE AREA 175, 257. 82 SOFT - 4. 02 AC. TOTAL IMPER' AOUS 70, 739. 27 SOFT. TOTAL POROU FT.104. 51 2, 40 ACRES Short Version BMP Computations For wmrksheets 2 - 6 Two Area Analysis Albemarle County Water Protection Ordinance: Modified Simple Method Westminster Canterbury Plan: 6 Duplex Replacement Water Resources Area: Upper Rivanna River Preparer: Kurt M. Gloeckner, P. E., P. L.S. Date: 25- Aug -06 Project Drainage Area Designation DA #1 L storm pollutant export in pounds, L = [P(Pj)Rv /12 ] [ C(A)2.72 ] Rv mean runoff coefficient, Rv = 0.05 + 0.009(1)Treat Total as Road Only Pi small storm correction factor, 0.9 for Ease of Analysis I percent imperviousness P annual precipitation, 43" in Albemarle A project area in acres in subject drainage area, A = 3.71 C pollutant concentration, mg /I or ppm target phosphorus f factor applied to RR V required treatment volume in cy, 0.5" over imperv. area = A(1)43560(0.5/12)/27 RR required removal , L(post) - f x L(pre) RR removal efficiency, RR100 /L(post) Impervious Cover Computation (values in feet & square feet) Item pre - development Area post - development Area Roads Length Width subtotal Length Width subtotal 2791.8 22 61419.6 2910.6 22 64033.2 0 0 0 0 0 0 0 61419.6 0 64033.2 Driveways Length Width no. subtotal Length Width no, subtotal and walks 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 Parking Lots 1 2 3 4 1 2 3 4 0 0 0 0 1 0 0 Gravel areas Area Area 0 x0.70= 0 x0.70=0 Structures Area no. subtotal Area no. subtotal 0 0 0 0 0 0 0 0 0 0 0 0 0 Actively- grazed pasture & Area Area yards and cultivated turf x 0.08 = 0 x 0.08 =0 Active crop land Area Area 0 x0.25= 0 0 x0.25=0 Other Impervious Areas 0 0 Impervious Cover 38%40% I(pre)I(post) Rv(post) V 0.41 98.8 New Development (For Development Areas, existing impervious cover <= 20 %) C f I (pre) * Rv(pre) L(pre) L(post) RR % RR Area Type 0.70 1.00 20% 0.39 8.93 9.26 0.33 4%Development Area 0.35 1.00 0% 0.39 4.46 4.63 0.17 4%Drinking Water Watersheds 0.40 1.00 1 % 0.39 5.10 5.29 0.19 4%Other Rural Land min. values Redevelopment (For Development Areas, existing impervious cover > 20 %) C f I (pre) * Rv(pre) L(pre) L(post) RR % RR Area Type 0.70 0.90 20% 0.39 8.93 9.26 1.22 13%Development Area 0.35 0.85 0% 0.39 4.46 4.63 0.84 18%Drinking Water Watersheds 0.40 0.85 1 % 0.39 5.10 5.29 0.95 18%Other Rural Land Interim Manual, Page 70 rev. 16 Feb 1998 GEB Short Version BMP Computations For Worksheets 2 - 6 Two Area Analysis Albemarle County Water Protection Ordinance: Modified Simple Method Westminster Canterbury Plan: 6 Duplex Replacement Water Resources Area: Upper Rivanna River Preparer: Kurt M. Gloeckner, P.E.R.L.S. Date: 25- Aug -06 Project Drainage Area Designation DA #2 L storm pollutant export in pounds, L = [P(Pj)Rv /12 ] [ C(A)2.72 j Rv mean runoff coefficient, Rv = 0.05 + 0.009(1)Treat Total as Road Only Pj small storm correction factor, 0.9 for Ease of Analysis 1 percent imperviousness P annual precipitation, 43" in Albemarle A project area in acres in subject drainage area, A = 0.85 C pollutant concentration, mg /I or ppm target phosphorus f factor applied to RR V required treatment volume in cy, 0.5' over imperv. area = A(1)43560(0.5/12)/27 RR required removal , L(post) - f x L(pre) RR removal efficiency, RR100 /L(post) Impervious Cover Computation (values in feet & square feet) Item pre - development Area post - development Area Roads Length Width subtotal Length Width subtotal 415.8 22 9147.6 534.6 22 11761.2 0 0 0 0 0 0 0 9147.6 0 11761.2 Driveways Length Width no. subtotal Length Width no. subtotal and walks 0 0 0 0 0 0 0 0 1 0 0 0 0 0 0 Parking Lots 1 2 3 4 1 2 3 4 0 0 0 0 1 0 0 Gravel areas Area Area 0 x0.70= 0 x0.70= 0 Structures Area no. subtotal Area no. subtotal 0 0 0 0 0 0 0 0 0 0 0 0 0 Actively- grazed pasture & Area Area yards and cultivated turf x 0.08 = 0 x 0.08 = 0 Active crop land Area Area 0 x0.25= 0 0 x0.25= 0 Other Impervious Areas 0 0 Impervious Cover 25%320 /c pre)post) Rv(post) V 0.34 18.2 New Development (For Development Areas, existing impervious cover <= 20 %) C f I (pre) * Rv(pre) L(pre) L(post) RR % RR Area Type 0.70 1.00 20% 0.27 1.42 1.75 0.33 19%Development Area 0.35 1.00 0% 0.27 0.71 0.88 0.17 19%Drinking Water Watersheds 0.40 1.00 1 % 0.27 0.81 1.00 0.19 19%Other Rural Land min. values Redevelopment (For Development Areas, existing impervious cover > 20 %) C f I (pre) * Rv(pre) L(pre) L(post) RR % RR Area Type 0.70 0.90 20% 0.27 1.42 1.75 0.47 27%Development Area 0.35 0.85 0% 0.27 0.71 0.88 0.27 31%Drinking Water Watersheds 0.40 0.85 1% 0.27 0.81 1.00 0.31 31%Other Rural Land Interim Manual, Page 70 rev. 16 Feb 1998 GEB DRAINAGE AREA IMPERVIOUS AREA AND POROUS AREA PRE - DEVELOPMENT DUPLEX COTTAGE REPLACEMENT SOUTH EAST QUADRANT OF CAMPUS MINOR AMENDMENT DRAWING NEWCOTTAGES2.DWG JOB NUMBER 97- 018 -31 DA -II 0.91 AC. DRAINAGE AREA IMPERVIOUS AREA AND POROUS AREA POST DEVELOPMENT DUPLEX COTTAGE REPLACEMENT SOUTH EAST QUADRANT OF CAMPUS MINOR AMENDMENT DRAWING NEWCOTTAGES2.DWG PRE - DEVELOPMENT 39,450.30 SQ.FT 0.91 AC. 36,977.61 SQ.FT 0.85 AC. DA -II 0.85 AC. 39,450.30 SQ.FT. 0.91 AC. 30,761.79 SQ.FT. 0.70 ACRES IMPERVIOUS 8,688.51 SQ.FT. 0.21 AC. POST DEVELOPMENT 36,977.61 SQ.FT. 0.85 AC. 25,498.26 SQ.FT. 0.58 ACRES IMPERVIOUS 36,977.61 SQ.FT. 0.27 AC. JOB NUMBER 97- 018 -31 CC -F- I 3i v'` . i tom. t '' .,- . . 's P-1