SW6210503_Add Info_20210928

ROY COOPER
Governor
DIONNE DELLI-GATTI
Secretary
BRIAN WRENN
Director
C. Scott Brown, PE
409 Chicago Drive, Suite 112
Fayetteville, NC 28306
NORTH CAROLINA
Environmental Quality
September 28, 2021
Subject: Second Request for Additional Information
Stormwater Permit No. SW6210503
Townsend Estates Subdivision
Hoke County
Dear Mr. Brown:
The Division of Energy, Mineral and Land Resources (DEMLR), received a Stormwater
Management Permit Application for the subject project on September 3, 2021. A review of that
information has determined that the application is not complete. The following information is
needed to continue the stormwater review:
Original Comment 3 — "The percent impervious area for drainage area 1 does not
appear to be calculated correctly (Section IV, 10). Please revise. " The percent
impervious are for a drainage area is calculated as the total impervious area within the
drainage area divided by the drainage area. The Required Storm Volume calculation page
indicates that this value is 43.4% whereas Section IV, 10 indicates 24%. Please revise as
needed. There also appears to be a discrepancy between the BUA within the drainage
area to the proposed wet pond as shown in the Application/SCS Curve Number
calculation (347,022 sf) and the Supplement-EZ Form/Required Storm Volume
calculation (319,423 sf). Please ensure that the BUA shown within the drainage area to
the proposed wet pond is consistent.
2. Original Comment 11— "...Please also ensure to include the cross-section at the
permanent pool elevation in the temporary storage stage -storage tables. " The temporary
pool stage -storage table was not updated to include the cross -sectional area of the
temporary pool at the permanent pool surface elevation (205.5 ft). The previously
provided calculations assume that cross -sectional area of the temporary pool at the
permanent pool elevation is zero sf based on the calculations (The calculations show a
cumulative storage between elevations 205.5 ft and 206.0 ft of 4,282 cf. The 4,282 cf
volume divided by the 0.5 ft depth results in an average cross -sectional area of 8,564 sf
which is exactly half of the cross -sectional area at elevation 206.0 ft, which implies the
surface area at elevation 205.5 ft is zero sf, which is incorrect). Please revise as needed.
D E Q�� North Carolina Department of Environmental Quality I Division of Energy, Mineral and Land Resources
512 North Salisbury Street 1 1612 Mail Service Center I Raleigh, North Carolina 27699-1612
NORTH CAROLINA _
oeaa"em or Euimameabai many 919.707.9200

3. Original Comment 13.b.i.1. — "The surface area of the proposed wet pond does not
need to be counted as impervious area. " The BUA calculations indicate that the surface
area of the permanent pool is 14,745 sf, however this is less than the sum of the forebay
and main pool surface areas at the permanent pool elevation (2,961 sf and 12,244 sf
respectively) as provided in the revised stage -storage tables. Please revise as needed for
consistency.
4. Original Comment 13.b.ii.1. — "The entire site column should be an accounting of the
entire site, not just the drainage area to the proposed SCM. If there is proposed BUA that
will be constructed within the project area but will not drain to the proposed SCM, it
should be reflected in this column (in addition to the on -site BUA within the SCM
drainage area). The `drainage area' for this column is the project area and should match
the information in the Application (as should the % BUA). " The information in this
column does not appear to be correct. The plans indicate that there are 61 lots that are
included in this project. If each lot is allocated 4,100 sf of BUA, there should be a total of
250,100 sf of BUA located within the subdivided lots, however, Line 9 of the Entire Site
Column only shows 226,000 sf of BUA located within the subdivided lots. Please ensure
that all of the BUA that will be located within the project area is accounted for in this
column.
5. Please clarify what the project area is for this project. Section IV, 7 and Line 5 of the
Entire Site Column on the Drainage Areas Page of the Supplement-EZ Form indicate that
the project area is 27.20 ac, however Line 6 of the Entire Site Column on the Drainage
Areas Page of the Supplement-EZ Form indicate that the on -site portion of the project
area is 26.51 ac. Please revise or clarify what this value is.
6. Please clarify some discrepancies in the SCS Curve Number calculations page:
a. Using 56.5 lots at 4,100 sf per lot results in 231,650 sf of BUA whereas 226,000
sf is shown in the calculations.
b. As mentioned earlier, adding up the BUA within the drainage area on this
calculation page results in 347,022 sf of BUA which is different than the amount
shown in the Supplement-EZ Form and Required Storm Volume calculation
(319,423 sf).
c. The pre -development condition table indicates that there is 60,588 sf of existing
BUA within the drainage area to the proposed wet pond, but the Supplement-EZ
Form only shows 54,000 sf worth of existing BUA.
7. 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.
a. PDFs must be uploaded using the form at:
https:.//edocs.deq.nc.gov/Forms/SW-Supplemental-Upload

b. Hard copies must be mailed or delivered to the following address:
i. For FedEx/UPS:
Suzanne McCoy
512 N. Salisbury Street, Office 640K
Raleigh, NC 27604
ii. For USPS:
Suzanne McCoy
1612 Mail Service Center
Raleigh, NC 27699-1612
Please note that this request for additional information is in response to a preliminary review.
The requested information should be received by this Office prior to October 28, 2021, or
the application will be returned as incomplete. The return of a project will necessitate
resubmittal of all required items, including the application fee. Please reference the State
assigned project number SW6210503 on all correspondence.
If you need additional time to submit the information, please submit your request for a time
extension to the Division at the contact below. The request must indicate the date by which you
expect to submit the required information. The Division is allowed 90 days from the receipt of
a completed application to issue the permit.
The construction of any impervious surfaces, other than a construction entrance under an
approved Sedimentation Erosion Control Plan, is a violation of NCGS 143-215.1 and is subject
to enforcement action pursuant to NCGS 143-215.6A.
If you have any questions concerning this matter please feel free to contact me at
[e-mail] or [phone].
Sincerely,
Jim Farkas
Environmental Engineer
Stormwater Program
cc: Fayetteville Regional Office