HomeMy WebLinkAboutSDP200900021 Calculations 2009-03-23Short Version BMP Computations For Worksheets 2 - 6
Albemarle County Water Protection Ordinance: Modified Simple Method
Plan: Byrom Park Water Resources Area:Rural Area
Preparer: David Anhold Date: March 23, 2009
Project Drainage Area Designation DA# 2 - Biofilter #2
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)
Pj small storm correction factor, 0.9
1 percent imperviousness
P annual precipitation, 43" in Albemarle
A project area in acres in subject drainage area,A =1.18
C pollutant concentration, mg /I or ppm target phosphorus
f factor applied to RR
required treatment volume in cy, 0.5" over impery 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
0 0 0 0
0 0 0 0 0 0
0 0 0 0
0 0 0 0
Driveways Length Width no.subtotal Length Width no.subtotal
and walks 0 0 0 0 65 6 1 390
0 0 0 0 0 0 0 0
0 0 0 390
Parking Lots 1 2 3 4 1 2 3 4
0 0 0 0 0
Gravel areas Area Area 18808
x0.70=0 0 x0.70=13165.6
Structures Area no.subtotal Area no.subtotal
0 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 32180 x 0.08 =2574.4
Active crop land Area Area
x0.25=0 x0.25=0
Other Impervious Areas
Impervious Cover 0%31%
l(pre)I(post)
Rv(post) V
0.33 24.9
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% 0.23 1.67 2.41 0.74 31% Development Area
0.35 1.00 0% 0.05 0.18 1.20 1.02 85% Drinking Water Watersheds
0.40 1.00 1% 0.06 0.24 1.38 1.13 82% 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% 0.23 1.67 2.41 0.91 38% Development Area
0.35 0.85 0% 0.05 0.18 1.20 1.05 87% Drinking Water Watersheds
0.40 0.85 1% 0.06 0.24 1.38 1.17 85% Other Rural Land
Interim Manual, Page 70 rev. 16 Feb 1998 GEB
Short Version BMP Computations For Worksheets 2 - 6
Albemarle County Water Protection Ordinance: Modified Simple Method
Plan: Byrom Park Water Resources Area:Rural Area
Preparer: David Anhold Date: March 23, 2009
Project Drainage Area Designation DA# 3
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)
Pj small storm correction factor, 0.9
I percent imperviousness
P annual precipitation, 43" in Albemarle
A project area in acres in subject drainage area,A =7.27
C pollutant concentration, mg /I or ppm target phosphorus
f factor applied to RR
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
0 0 0 0
0 0 0 0 0 0
0 0 0 0
0 0 0 0
Driveways Length Width no.subtotal Length Width no.subtotal
and walks 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0
Parking Lots 1 2 3 4 1 2 3 4
0 0 0 0 0
Gravel areas Area Area 7347
x0.70=0 0 x0.70=5142.9
Structures Area no.subtotal Area no.subtotal
0 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 19605 x 0.08 =1568.4
Active crop land Area Area
x0.25=0 x0.25=0
Other Impervious Areas
Impervious Cover 0%2%
l(pre)post)
Rv(post) V
0.07 10.4
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% 0.23 10.27 3.08 7.18 233% Development Area
0.35 1.00 0% 0.05 1.12 1.54 0.43 28% Drinking Water Watersheds
0.40 1.00 1% 0.06 1.50 1.76 0.26 15% 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% 0.23 10.27 3.08 6.16 200% Development Area
0.35 0.85 0% 0.05 1.12 1.54 0.59 38% Drinking Water Watersheds
0.40 0.85 1% 0.06 1.50 1 76 0.48 27% Other Rural Land
Interim Manual, Page 70 rev. 16 Feb 1998 GEB
Short Version BMP Computations For Worksheets 2 - 6
Albemarle County Water Protection Ordinance: Modified Simple Method
Plan: Byrom Park Water Resources Area:Rural Area
Preparer: David Anhold Date: March 23, 2009
Project Drainage Area Designation DA# 4
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)
Pj small storm correction factor, 0.9
I percent imperviousness
P annual precipitation, 43" in Albemarle
A project area in acres in subject drainage area,A =0.188
C pollutant concentration, mg /1 or ppm target phosphorus
f factor applied to RR
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
0 0 0 0
0 0 0 0 0 0
0 0 0 0
0 0 0 0
Driveways Length Width no.subtotal Length Width no.subtotal
and walks 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0
Parking Lots 1 2 3 4 1 2 3 4
0 0 0 0 0
Gravel areas Area 2015 Area 2548
x 0.70 =1410.5 0 x 0.70 =1783.6
Structures Area no.subtotal Area no.subtotal
0 0 0 0
0 0 0 0
0 0 0 0 0 0
Actively - grazed pasture &Area Area
yards and cultivated turf 1950 x 0.08 =156 5402 x 0.08 =432 16
Active crop land Area Area
x0.25=0 x0.25=0
Other Impervious Areas
Impervious Cover 19%27%
l(pre)post)
Rv(post) V
0.29 3.4
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% 0.23 0 27 0.34 0.07 22% Development Area
0.35 1.00 0% 0.22 0.13 0.17 0.04 24% Drinking Water Watersheds
0.40 1.00 1% 0.22 0.15 0.19 0.05 24% 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% 0.23 0.27 0.34 0.10 29% Development Area
0.35 0.85 0% 0.22 0.13 0.17 0.06 36% Drinking Water Watersheds
0.40 0.85 1% 0.22 0.15 0.19 0.07 36% Other Rural Land
Interim Manual, Page 70 rev. 16 Feb 1998 GEB
Short Version BMP Computations For Worksheets 2 - 6
Albemarle County Water Protection Ordinance: Modified Simple Method
Plan: Byrom Park Water Resources Area:Rural Area
Preparer: David Anhold Date: March 23, 2009
Project Drainage Area Designation DA# 5
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)
Pj small storm correction factor, 0.9
percent imperviousness
P annual precipitation, 43" in Albemarle
A project area in acres in subject drainage area,A =0.68
C pollutant concentration, mg /I or ppm target phosphorus
f factor applied to RR
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
0 0 0 0
0 0 0 0 0 0
0 0 0 0
0 0 0 0
Driveways Length Width no.subtotal Length Width no.subtotal
and walks 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0
Parking Lots 1 2 3 4 1 2 3 4
0 0 0 0 0
Gravel areas Area 2980 Area 3105
x 0.70 =2086 0 x 0.70 =2173.5
Structures Area no subtotal Area no.subtotal
0 0 0 0
0 0 0 0
0 0 0 0 0 0
Actively - grazed pasture &Area Area
yards and cultivated turf 4525 x 0.08 =362 13007 x 0.08 =1040.56
Active crop land Area Area
x0.25=0 x0.25=0
Other Impervious Areas
Impervious Cover 8%11%
l(pre)I(post)
Rv(post) V
0.15 5.0
New Development (For Development Areas, existing impervious cover <= 20 %)
C f I (pre) " Rv(pre) L(pre) L(post) RR RR Area Type
0/0 1.00 20% 0.23 0.96 0.62 0.34 56% Development Area
0.35 1.00 0% 0.12 0.26 0.31 0.05 16% Drinking Water Watersheds
0.40 1.00 1% 0.12 0.30 0.35 0.06 16% 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% 0.23 0.96 0.62 0.25 40% Development Area
0.35 0.85 0% 0.12 0.26 0.31 0.09 28% Drinking Water Watersheds
0.40 0.85 1% 0.12 0.30 0.35 0 10 28% Other Rural Land
Interim Manual, Page 70 rev. 16 Feb 1998 GEB
Short Version BMP Computations For Worksheets 2 - 6
Albemarle County Water Protection Ordinance: Modified Simple Method
Plan: Byrom Park Water Resources Area:Rural Area
Preparer: David Anhold Date: March 23, 2009
Project Drainage Area Designation DA# 6
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)
Pj small storm correction factor, 0.9
I percent imperviousness
P annual precipitation, 43" in Albemarle
A project area in acres in subject drainage area,A =0.019
C pollutant concentration, mg /I or ppm target phosphorus
f factor applied to RR
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
0 0 0 0
0 0 0 0 0 0
0 0 0 0
0 0 0 0
Driveways Length Width no.subtotal Length Width no.subtotal
and walks 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0
Parking Lots 1 2 3 4 1 2 3 4
0 0 0 0 0
Gravel areas Area Area 323
x 0.70 =0 0 x 0.70 =226.1
Structures Area no.subtotal Area no.subtotal
0 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 =0 500 x 0.08 =40
Active crop land Area Area
x0.25=0 x0.25=0
Other Impervious Areas
Impervious Cover 0%32%
l(pre)post)
Rv(post) V
0.34 0.4
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% 0.23 0.03 0.04 0.01 32% Development Area
0.35 1.00 0% 0.05 0.00 0.02 0.02 85% Drinking Water Watersheds
0.40 1.00 1% 0.06 0.00 0.02 0.02 83% 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% 0.23 0.03 0.04 0.02 39% Development Area
0.35 0.85 0% 0.05 0.00 0.02 0.02 87% Drinking Water Watersheds
0.40 0.85 1% 0.06 0.00 0.02 0.02 85% Other Rural Land
Interim Manual, Page 70 rev. 16 Feb 1998 GEB
Short Version BMP Computations For Worksheets 2 - 6
Albemarle County Water Protection Ordinance: Modified Simple Method
Plan: Byrom Park Water Resources Area:Rural Area
Preparer: David Anhold Date: March 23, 2009
Project Drainage Area Designation DA# 7
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)
Pj small storm correction factor, 0.9
percent imperviousness
P annual precipitation, 43" in Albemarle
A project area in acres in subject drainage area,A =0.031
C pollutant concentration, mg /I or ppm target phosphorus
f factor applied to RR
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
0 0 0 0
0 0 0 0 0 0
0 0 0 0
0 0 0 0
Driveways Length Width no.subtotal Length Width no.subtotal
and walks 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0
Parking Lots 1 2 3 4 1 2 3 4
0 0 0 0 0
Gravel areas Area 1025 Area 1395
x 0.70 =717.5 0 x 0.70 =976.5
Structures Area no.subtotal Area no.subtotal
0 0 0 0
0 0 0 0
0 0 0 0 0 0
Actively - grazed pasture &Area Area
yards and cultivated turf 350 x 0.08 =28 x 0.08 =0
Active crop land Area Area
x0.25=0 x0.25=0
Other Impervious Areas
Impervious Cover 55%72%
l(pre)post)
Rv(post) V
0.70 1.5
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% 0.55 0.10 0.13 0.03 22% Development Area
0.35 1.00 0% 0.55 0.05 0.07 0.01 22% Drinking Water Watersheds
0.40 1.00 1% 0.55 0.06 0.08 0.02 22% 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% 0.55 0.10 0.13 0.04 30% Development Area
0.35 0.85 0% 0.55 0.05 0.07 0.02 34% Drinking Water Watersheds
0.40 0.85 1% 0.55 0.06 0.08 0.03 34% Other Rural Land
Interim Manual, Page 70 rev. 16 Feb 1998 GEB
Short Version BMP Computations For Worksheets 2 - 6
Albemarle County Water Protection Ordinance: Modified Simple Method
Plan: Byrom Park Water Resources Area:Rural Area
Preparer: David Anhold Date: March 23, 2009
Project Drainage Area Designation DA# 8
L storm pollutant export in pounds, L = [P(Pj)Rv/121[ C(A)2.72 ]
Rv mean runoff coefficient, Rv = 0.05 + 0.009(1)
Pj small storm correction factor, 0.9
percent imperviousness
P annual precipitation, 43" in Albemarle
A project area in acres in subject drainage area,A =0.017
C pollutant concentration, mg /1 or ppm target phosphorus
f factor applied to RR
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
0 0 0 0
0 0 0 0 0 0
0 0 0 0
0 0 0 0
Driveways Length Width no.subtotal Length Width no.subtotal
and walks 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0
Parking Lots 1 2 3 4 1 2 3 4
0 0 0 0 0
Gravel areas Area Area 110
x 0.70 =0 0 x 0.70 =77
Structures Area no.subtotal Area no.subtotal
0 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 =0 660 x 0.08 =52.8
Active crop land Area Area
x0.25=0 x0.25=0
Other Impervious Areas
Impervious Cover 0%18%
l(pre)l(post)
Rv(post) V
0.21 0.2
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% 0.23 0.02 0.02 0.00 11% Development Area
0.35 1.00 0% 0.05 0.00 0.01 0.01 76% Drinking Water Watersheds
0.40 1.00 1% 0.06 0.00 0.01 0.01 72% 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% 0.23 0.02 0.02 0.00 0% Development Area
0.35 0.85 0% 0.05 0.00 0.01 0.01 80% Drinking Water Watersheds
0.40 0.85 1% 0.06 0.00 0.01 0.01 76% Other Rural Land
Interim Manual, Page 70 rev. 16 Feb 1998 GEB
Short Version BMP Computations For Worksheets 2 - 6
Albemarle County Water Protection Ordinance: Modified Simple Method
Plan: Byrom Park Water Resources Area:Rural Area
Preparer: David Anhold Date: March 23, 2009
Project Drainage Area Designation DA# 9
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)
Pj small storm correction factor, 0.9
1 percent imperviousness
P annual precipitation, 43" in Albemarle
A project area in acres in subject drainage area,A =0.095
C pollutant concentration, mg /I or ppm target phosphorus
f factor applied to RR
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
0 0 0 0
0 0 0 0 0 0
0 0 0 0
0 0 0 0
Driveways Length Width no.subtotal Length Width no.subtotal
and walks 0 0 0 0 0
0 0 0 0 0 0 0 0
0 0 0 0
Parking Lots 1 2 3 4 1 2 3 4
0 0 0 0 0
Gravel areas Area Area 1648
x 0.70 =0 0 x 0.70 =1153.6
Structures Area no.subtotal Area no.subtotal
0 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 2510 x 0.08 =200.8
Active crop land Area Area
x0.25=0 x0.25=0
Other Impervious Areas
Impervious Cover 0%33%
l(pre)I(post)
Rv(post) V
0.34 2.1
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% 0.23 0.13 0.20 0.07 33% Development Area
0.35 1.00 0% 0.05 0.01 0.10 0.09 85% Drinking Water Watersheds
0.40 1.00 1% 0.06 0.02 0.11 0.10 83% Other Rural Land
min. values
Redevelopment (For Development Areas, existing impervious cover > 20 %)
C f 1 (pre) * Rv(pre) L(pre) L(post) RR RR Area Type
0.70 0.90 20% 0.23 0.13 0.20 0.08 40% Development Area
0.35 0.85 0% 0.05 0.01 0.10 0.09 88% Drinking Water Watersheds
0.40 0.85 1% 0.06 0.02 0.11 0.10 85% Other Rural Land
Interim Manual, Page 70 rev. 16 Feb 1998 GEB