SW3231201_Response To Comments_20240424

A AMERICAN
Engineering
April 24, 2024
North Carolina Department of Environmental Quality
Division of Energy, Mineral & Land Resources
Stormwater Program
512 North Sailsbury Street
Office 625Y
Raleigh, NC 27699
Subject: Request for Additional Information
Stormwater Permit No. SW3231201
The Shops at Prescot Village, Wet Pond
Union County
Dear Ms. Holland,
Please find below the original review comments provided by the Engineering Department and
each subsequent response:
1. In accordance with 15A NCAC 02H .1003(3)(b), any off-site areas (areas located
outside of the project area) that drain to the SCM must be accounted for at their full
build-out potential. The full build-out potential is determined by either having the
property owners enter into a legal agreement limiting the amount of area and BUA
draining from the offsite area to the SCM or by assuming that the off-site area is 100%
BUA, its full build-out potential. Please see additional information at the end of this
letter.
Response: The current drainage area for PN06165441 is included in the calculation
but is not assumed to be 100%BUA. This offsite drainage area that drains into the
proposed SCM is accounted for in permit SW3200701, which is the pond north of
Kemble St. It has been noted on the pre and post development drainage area maps
that if this property is to be developed it shall have BUA directed to the pond north of
Kemble St per permit SW3200701. The calculations for SW3200701 have been
included with the submittal package for reference.
2. Please correct the following issues with the Supplement-EZ Form:
a. Cover Page:
i. Line 7, 8— Per 15A NCAC 02H .1017(10) the minimum required vegetated
American Engineering Associates—Southeast, PA
8008 Corporate Center Drive, Suite 110, Charlotte, NC 28226 •704-375-2438 •www.American-EA.com

setback width is 30 ft. While it is noted no surface water is on-site, please
revise.
Response: Lines 7& 8 have been revised on the Supplement-EZ cover
page.
3. Per Wet Pond MDC 2 and Wet Pond MDC 5, please label the entrance and exit
elevations of the bottom of the forebay so that it can be confirmed that the forebay
entrance is deeper than the forebay exit, and the minimum 6" sediment storage is
maintained.
Response: The entrance and exit elevations of the bottom of the forebay have been
labeled on the SCM plan, sheet C5.4
4. Provide the sizing and class for the riprap aprons on the plans to ensure compliance with
15A NCAC 02H .1003 (5) and 15A NCAC 02H .1050 (4). Please clarify if flow from
C3-FES 24 was included in the sizing calculations.
Response: The flow from C3-FES24 has been included in the sizing calculations. Riprap
sizing has been added to the plans.
5. Please revise the maintenance easement to include the outlet of the SCM per General
MDC 8 & 9. The entire footprint of the SCM system must be included in the access and
maintenance easement, plus an additional ten or more feet around the SCM to provide
enough room to complete maintenance tasks.
Response: The maintenance easement has been revised to include the outlet of the
SCM.
6. The temporary pool elevation is set by the elevation of the lowest bypass, which
appears to be 509.60 in the outlet structure details but is referenced as 509.51 in the
package. Please clarify.
Response: The temporary pool has been changed in the package as 509.60.
7. The design volume for a wet pond is the volume that can be retained for a two to five-
day period between the temporary pool elevation (set by the elevation of the lowest
bypass) and the permanent pool elevation (set by the drawdown orifice) per C-3 of the
Manual. This value should be able to be confirmed within the calculations, so it is
recommended to include the elevation at the temporary pool within the stage storage
tables. Please revise accordingly, as the water quality volume was utilized in the
American Engineering Associates—Southeast, PA
8008 Corporate Center Drive, Suite 110, Charlotte, NC 28226 •704-375-2438 •www.American-EA.com

drawdown calculations. Please note that due to the head decreasing as drawdown
occurs, it is recommended to use H/3, which H being the driving head from water
surface to centroid orifice.
Response: Elevation 509.60 has been added to the stage storage table in the pond
report. The water quality orifice draw down equation has been revised to use H/3.
8. Per Sheet C5.4, the bottom of sediment storage for the forebay is 502.5. Using this an
incremental volume in the stage storage table between this and the bottom of sediment
storage at 501.5 overestimates the volume that will be stored within the forebay. Please
revise.
Response: The storage has been revised in the SA/DA calculations.
9. Please clarify the lots referenced in the deed restrictions so that it can be verified that
the BUA shown on the plans corresponds to the allotment of BUA, and the SCM is sized
to accommodate all BUA.
Response: Page 3 of the signed deed restrictions show the lots color coded so that they
may be identified per the deed restriction.
Sincerely,
American Engineering Associates—Southeast, PA
Blake Estridge, PE
Project Engineer
[e-mail]
American Engineering Associates—Southeast, PA
8008 Corporate Center Drive, Suite 110, Charlotte, NC 28226 •704-375-2438 •www.American-EA.com