HomeMy WebLinkAboutWPO201300023 Correspondence 2013-08-05Lexington
Wes Perkins, LS
Russ Orrison, PE, LS
Susan Perkins
Pierson Hotchkiss, LS
Dave Walsh
Gavin Worley, PE
August 5, 2013
County of Albemarle
Department of Community Development
Michael Koslow, PE
401 McIntire Road
Charlottesville, VA 22902
Re: Edenbrook Park Water Protection Plan — WP02013-00023
Page 1 of 2
Dear Mr. Koslow,
Lynchburg
Kenneth Knott, LS
Norman Walton, PE
Aaron Dooley, LS
The comments dated May 23, 2013 have been addressed and revised Water Protection Plans are transmitted herewith.
Response to the comments follows:
A. Application Information
1. Comment noted.
2. Please see the email from Vinny Pero attached to this letter.
3. Comment noted.
B. Title Information
1. Comment noted.
C. Proposed Plan View Information
1. Stormwater management easements are now proposed and labeled on the plans.
2. The drainage structures are labeled on the Grading Plan in the Site Plan. Please see the note referencing the
site plan for utility information on the Sheet 1.
D. Erosion & Sediment Control (ESC) Plan
1. The stone construction entrance detail was removed from the plan, and the legend was revised.
2. Dust control is now shown on the Phase I and Phase 11 E&S Plans.
3. Right-of-way diversions are now proposed where construction traffic will need to cross the proposed
diversions. A detail was also added to the plan.
4. The Old Trail development has satisfied the adequate channel calculation to the satisfaction of staff. This
development proposes a very clear and well -documented reduction in peak flows, as shown by conservative
calculations in compliance with Albemarle County standards. Brand new calculations of the hydrology of the
entire contributing watershed would almost assuredly not match precisely the calculations of an independent
engineer, and there seems to be no purpose served by re -performing approved calculations. No matter what
the approved calculations show, the reduction in flow proven with our submitted calculations will result in the
channel being that small amount more adequate. Lastly, due to the nature of the water quality measures that
we propose, flows from the most common storm events will be vastly reduced in soaking and migration
through the media mix; this attenuation is not credited in the calculations, but clearly reduces peak rates and
volumes of runoff. (Response written by Russ Orrison, PE, LS)
17 W. Nelson Street • P.O. Box 1567
Lexington, Virginia 24450
27 Green Hill Drive
Forest, Virginia 24551
�yv-4oy-yvvi rax: Z)4v-404-3uu9 434-525-5985 Fax: 434-525-5986
Email: pno@perkins-orrison.com
Re: Edenbrook Park Water Protectionl-#lan — WP02013-00023
Page 2 of 2
E. Stormwater Management Plan
1. Please see Sheet 10 for the Stormwater Management Pre -developed Drainage Divides Map.
2. Please see Sheet 10 for the Stormwater Management Post -developed Drainage Divides Map.
3. Please see Sheet 6 for the Bioretention Filter section details.
4. Please see Sheet 4 for the Forebay Weir locations and Sheet 6 for Weir Detail.
5. The Bio-filter area shown on the master plan has been removed.
6. The label has been revised.
7. The R-Tank Manufacturer Details are now shown on Sheet 7.
8. A 4' diameter manhole is proposed as the emergency spillway in the Bioretention Filters to allow inspection
access.
F. Mitigation Plan
1. Due to the new location of the offsite sewer connection, the mitigation plan and area has changed. The total
area in the stream buffer disturbed by this project has not increased, and the proposed mitigation area
increased slightly. The same numbers of plantings previously proposed are still proposed on this plan, just in
different locations.
Please let me know if you have any questions, comments, or concerns. Thank you for your input on this project.
Sincerely,
'7
Perkins & Orrison, Inc.
Gavin G. Worley, PE
CC: Edenbrook L.L.0
Winks-Snowa Architects
P&O File 1221
0:\2013\12221 WPO Comment RSPS 130802.doc
PERKINS & ORRISON
17 W. Nelson Street • P.O. Box 1567
Lexington, Virginia 24450
27 Green Hill Drive
Forest, Virginia 24551
MU-404-9uu1 Pax:340-464-5009 434-525-5985 Fax:434-525-5986
Email: pno@perkins-orrison.com