20072163 Ver 2_Staff Comments_20110614

Lucas, Annette
From: Lucas, Annette
Sent: Tuesday, June 14, 2011 11:06 AM
To: Turlington, Chad
Cc: Lucas, Annette
Subject: 07-2163v2 Riverwoods Commons ADA Lillington Commercial
Attachments: 07-2163v2 Riverwood Commons - take 2.docx
Chad,
My comments are attached. Please let me know if you have questions.
Thanks,
Annette
Annette M. Lucas, PE
Environmental Engineer
NCDENR DWQ Wetlands and Stormwater Branch
1650 Mail Service Center, Raleigh, NC 27699-1650 (Mail)
512 N. Salisbury St, Raleigh, NC 27604 1 91h Floor (Location & Parcels)
Phone: [phone] Fax: [phone] Email: Annett.e.Lucas4ncdenr.
Website: http://portal.ncdenr.org/web/wcl /swp/ws/401
`# Before printing this email, please consider your budget and the environment.
E-mail correspondence to and from this address may be subject to the North Carolina Public Records Law and may be disclosed to
third parties.

07-2163v2 Riverwood Commons-take 2
AML comments
June 13, 2011
1. Please explain how the runoff from the driveway that passes over Wetland 3 is being treated. It
does not appear to be included in any of the drainage areas.
2. Please label the proposed one-foot contours for the proposed stormwater wetlands and please
insure that these contours match the cross-sections provide (for example, 3:1 side slopes shown
on both views).
3. The DWQ suggests providing one additional deep pool area in each of the proposed wetlands to
encourage population by Gambusia, natural predators of mosquitoes.
4. Please provide details of the outlet structures for the proposed wetlands as well as details for
anti-seep protection in the outlet barrels.
5. Please address the following two issues on Sheet L-1:
a. The Inspection and Maintenance Provisions shown pertain to Wet Detention Ponds
rather than Stormwater Wetlands.
b. Appropriate plant spacing should be added to the table.
6. Please provide a soils report that documents the level of the Seasonal High Water Table within
the footprint of each of the proposed BMPs.
7. Typically a bioretention cell cannot be placed directly adjacent to a natural wetland because the
required two-foot separation between the invert of the cell and the SHWT cannot be provided.
If that is the case at the proposed BMP site, then please provide a BMP that is appropriate for
high water tables (such as a stormwater wetland).