20081121 Ver 2_Staff Comments_20091124

Lucas, Annette
From: Lucas, Annette
Sent: Tuesday, November 24, 2009 1:19 PM
To: Homewood, Sue
Cc: Lucas, Annette
Subject: 08-1121v2 Diamonds Keep Subdivision
Attachments: 08-1121v2 Diamonds Keep Subdivision.doc
10
Sue,
This last submittal was a big step in the right direction. There are a number of comments, but they are technical
comments on designs rather than big picture items. Let me know if you have Qs.
Thanks,
A
Annette Lucas, PE
NC Division of Water Quality - 401 Oversight/Express Unit
2321 Crabtree Boulevard, Suite 250
Raleigh, North Carolina 27604
Phone: [phone]
Fax: [phone]
Email correspondence to and from this address may be subject to the North Carolina Public Records Law and may be
disclosed to third parties.

08-112lv2 Diamonds Keep Subdivision
AML comments
November 24, 2009
1. Overall, the DWQ accepts your approach of treating offsite area in lieu of
providing stormwater treatment for drainage areas 7 and 8. However, please
describe the current and future uses of the land in the offsite drainage area as well
as an estimation of the current and future imperviousness of the offsite area.
2. For all proposed stormwater BMPs, please provide soils test that has been
conducted within the footprint of every proposed BMP to document the level of
the SHWT. This information should be attached. Also, the BMP Supplement
Forms and plan sheets should be updated to reflect the new information. The
DWQ will not approve these BMPs without a soils test that has been sealed by an
appropriately qualified individual.
3. For all proposed BMPs, please provide a construction sequence that explains how
the BMP will be protected during the project construction.
4. For all Wet Detention Ponds, please fill out the "Volume, temporary pool" blank
in the Supplement Forms.
5. Please show the level of the temporary pools on the wet detention pond profiles.
6. Please correct all discrepancies and errors in the Supplement Forms and plan
sheets. For example, for Basin 1, the size of the orifice on the Supplement Form
is stated to be 2 inches, but the plan sheet says 2.5 inches.
7. Please correct errors in the values of driving head that have been entered into the
Wet Detention Basin Supplement Forms. The driving head is equal to the
Temporary Pool elevation minus the Permanent Pool elevation.
8. For the sand filters, please provide specifications for the sand media material that
is to be used.