HomeMy WebLinkAboutSDP200600112 Assessment - Groundwater 2006-10-09 5 P- btp 1I2
Short Version BMP Computations For Worksheets 2-6
Albemarle County Water Protection Ordinance: Modified Simple Method
Plan: DOMINION OFFICE PARK Water Resources Area: New Dev-Development Area
Prepare, TRM Date. 9-Oct-06
Project Drainage Area Designation DA-FILTERRA 2 RELOCATION
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=
C pollutant concentration,mg/I or ppm target phosphorus
f factor applied to RR
V 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. 3 0 01
0 0: 0'
Driveways Length Width no subtotal Length ,, Width no. subtotal
and walks � 3 i._.... ._..._.._._,_. ............_ ( 0
0 OJ Oi 0 0
i ....... ..._. L...._. _.!...... ._.._. 0 ............._0 01. 0 .... 0 0
Parking Lots 1 2 3..................._4 1 2 3 4
.
._.
8239..... 1._ 8239 8239 .. . .1517r........_............0 0 9756
Gravel areas Area Area
x070= 0 Ix0.70= 0
Structures Area no. subtotal Area no subtotal
0...._ 0 . _.0 1)-_......._............._0,
( 0 0 0 0 _ 0 0
0 0 0 01 0._.......... 0
Actively-grazed pasture& Area Area
yards and cultivated turf 1134 x 0 08= 4 90 72( 1134 x 0 08= 90 72
Active crop land Area 1 pA� rea
d
i x025= 0 x025= 0
Other Impervious Areas
0 0
Impervious Cover
l(pre) t3P4N. 214 l(post)
Rv(post) V
0 86 15.2
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 74 1.13 1 33 0.19 15% Development Area
0.35 1.00 0% 0.74 0 57 0 66 0.10 15% Drinking Water Watersheds
0.40 1.00 1% 0.74 0.65 0.76 0 11 15% Other Rural Land
*min.values
Redevelopment(For Development Areas,existing impervious cover>20%)
C f I. I(pre)* Rv(ore) L(pre) L(post) RR %RR Area Type „ ( /0
0.70 0.90 20% 0 74 1.13 1.33 0 31 2? o Development Area -15%
7 5
o
0.35 0.85 0% 0 74 0 57 0 66 0 18 27% Drinking Water Watersheds
0.40 0.85 1% 0.74 0 65 0 76 0 21 27% Other Rural Land
i
c . i 0 :::3
3
COMMUNITY DEVELOP ?Ei I