SW6230703_Response To Comments_20231030

c, 4Dsite
October 30, 2023 civil engineering I land surveying
NCDEQ Division of Water Quality
Attn: Brianna Holland
512 N. Salisbury Street
Raleigh, NC 27604
RE: Storm water resubmittal, Brayden Preserve Subdivision, Cumberland County, North
Carolina
Brianna;
We received the review comments dated October 3, 2023. The comments have been
addressed as noted below.
1. Drainage Area
a. For a low-density project like this, the "drainage area" of the low-density
area is equal to the project area and excludes the surface water area.
Please revise the Basin Information Table in Section IV, 10 of the
Application, Supplement-EZ Cover Line 2, and Supplement-EZ Drainage
Areas Lines 5-6 accordingly. See 15A NCAC 2H .1003(1)(c)(i). Updates
made is requested
2. Supplement-EZ
a. Drainage Areas, Line 18: Please provide.
3. Calculations
a. Outlets must be stable per 15A NCAC 02H .1003(5). Riprap calculations
were provided at discharge points with culverts, but stability must be
demonstrated at all stormwater outlets. Provide engineering calculations
exhibiting that where vegetated conveyance ends, the exit velocity for
the design flow is nonerosive for the existing field conditions. Guidance
for this can be found in the NC Erosion and Sediment Control Planning
and Design Manual Chapter 6.
https://www.deq.nc.gov/about/divisions/energy-mineral-andland-
resources/erosionand-sediment-control/erosion-and-sediment-control-
planning-anddesign-manual
i. There are 2 storm outlet locations for the development. These are
ditches 9 and 12. Calculations for both of these ditches were
included in the original submittal. Both ditches are lined with a
temporary erosion control matting. The velocity for Ditch #9 in
permanent state is 2.64 fps and the same velocity for Ditch #12 is
1.93 fps. The velocities are less than the maximum allowable
409 Chicago Drive, Suite 112,Fayetteville. NC 28306
office I 910-426-6777 fax [phone]
On time,every time. www.4Dsitesolutions.corn

velocity. Unless I am missing something, these outlet ditches are
stable and no additional work is required to satisfy this comment.
Please provide electronic copies of the USGS topographic map of the site, NRCS
soils map, the signed & sealed cover page for the calculations, the storm
drainage/hydraulic grade line calculations and the property deeds. These items
were provided in the hard copy submission but were not uploaded electronically.
Please ensure that the electronic repository is complete. Items have been
uploaded as requested
5. Provide PDFs of all revisions, 2 hardcopies of revised plan sheets, 1 hardcopy of
other documents, and a response to comments letter briefly describing how the
comments have been addressed. Done. No plan sheet modifications were
required based on responses to comments.
I look forward to working with you on this project. If you have any questions or
concerns, please contact me at your earliest convenience.
Sincerely,
4D Site Solutions, Inc
Scott Brown, PE
[e-mail]
Enclosure
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