HomeMy WebLinkAboutWPO200400093 Calculations 2004-08-26 (2) STORMWATER BMP CALCULATIONS
FOR
ADVANCE MILLS FARM SUBDIVISION
PHASE 1
July 6, 2002
REV: August 26, 2004
LOCATION:
Tax Map 20 Parcel 6A1
Whitehall District, Albemarle County, Virginia
OWNER:
Advance Mills Land Trust, LLC 40\- 11. `
P.O. Box 8147 o� Z
Charlottesville, VA 22911 • o -L7l/
TIMO Y RAY MILLER
DEVELOPER: • 0402 030542
•
C. W. Hurt ' 4y
195 Riverbend Road o, ".F `÷.w o
Charlottesville, VA 22906 s`SIONAI_V-1G
PREPARED BY:
Rivanna Engineering & Surveying, PLC
P. O. Box 7603
Charlottesville, VA 22906
434.984.1599
F: 434.984.8863
RESI@CSTONE.NET
The Stormwater Quality BMP's for this subdivision shall be a 200' Riparian Buffer
Easement along the North Fork Rivanna River.
• Sort Version BMP Computations For Worksheets 2 -6
Albemarle County Water Protection Ordinance: Modified Simple Method
Plan: Advance Mills Farm-Phase II Water Resources Area:
Preparer TRM Date: 25•Aug-04
-
Project Drainage Area Designation Rural Subdivision
L storm pollutant export in pounds, L=[P(Pj)Rv/12] [C(A)2.72]
Rv mean runoff coefficient, Rv=0.05+0.009(I)
P] 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'=_ 19so0`
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 _.._.. _....._. ._...___ ._..___... _.. ._..._.__. ... . .
;predevelopment Area post development_ Area
FRoads Length Width subtotal j Length Width subtotal
0 0 0 2600 18 46800,
1 . _ ._.{ . or a - . _ .. _0:.... .. P.
0. _ 0
.__.............._.._._....___..__......_.._.......i...----...J_._.__.__.—'___._. 0' of . - 0. 46800
Driveways
g1600� ____ 10; 1 15000; Length_ Width no. subtotal Dnvewa s Length Width no. subtotal , ___ ,,,__—__ _,.___.,_^,. ...,,,___
and
,___ '..,,, r--�_ ' 200! 10 1 2000
I ,
01 Oj 0 0; 0 0 0 0
..._ I. .... ...O
J 150001 ... .... .... .. 0 2000.
;Parking Lots 1 2 3 4 , 1 2 3 4:
0, ) ; 0:_ 16786 0. 16786'
'Gravel areas Area ; ;Area
tx0.70= ' 0; -x0.70= OI.
Structures Area no subtotal 1 Area no subtotal
i ._ .
I_ __B00 -... 0 0 8001 - 1 0 0
• 001 800 1 800,
0 0 80. l 1500 10 15000s
i -- .....
Actively-grazed pasture& Area j Area
-----�_.._._...._15800.
!yards and cultivated turf a 8 609 080;x 0.08= 688726.4! 8 543 494 x(Loa= 683479.52':.
{Active crop land Area Area
•i Ix 0 x0.25= 0;
;Other Impervious Areas I
; 0! 0
Impervious Cover —tx a .89'°1 1 9GM
l(pre) l(post)
L Rv(post)' V
New Development(For Development Areas,existing Impervious cover a 20%)
C f I re Rv re I L re L(post) RR , %RR Area Type
r "040 1 00 is *209'' 0 12 28507 76 90 3 89 ` F `'7796'� Development Area
r
57 157.79 121 78
s „ 4135 f€ 1•00 0 (; 0.12 I 75. _g :5%j Drinking Water Watersheds `,
i�y,n` .0.r�: ..,, 1 79 9017I 4,37( 5%' OtherRuralLand
*min.values
Redevelopment(For.Development Areas,existing Impervious cover>20%)
i C f 1(pre)* " Rv(pre) i L(pre) L(post) ! RR /°RR Area Type
7 j0 70 "' +
0 9D , 20%1 0.23 : 279.57 157.79 I -93.82 " 59% Development Area
i st 0 35 .. 0 85 , , �0%5 _0.12 I _75.07 78.90 I 15.09_ 19% Drinking Water W_a_tershed_s __ _
Lr „0 40 , oet ";: rim 0.121 85.79 90.17 i.. 17.24 j hPa`r19%: Other Rural Land -Interim Manual,Page 70 rev. 16 Feb 1998 GEB