SW6200101_Add Info Request_20200211

ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
BRIAN WRENN
Acting Director
F. Michael Mayer, PE
Mason & Hanger
300 W. Vine Street, Suite 1300
Lexington, KY 40507
NORTH CAROLINA
Environmental Quality
February 11, 2020
Subject: Request for Additional Information
Stormwater Permit No. SW6200101
Special Operations Forces (SOF) Civil Affairs TEMF — PN69552
Cumberland County
Dear Mr. Mayer:
The Division of Energy, Mineral and Land Resources (DEMLR), received a Stormwater
Management Permit Application for the subject project on January 15, 2020. A review of that
information has determined that the application is not complete. The following information is
needed to continue the stormwater review:
Please submit full size plan sheets (minimum 22 inches by 34 inches) [I 5A NCAC
02H .1042(g)]. Only the following sheets are required:
a. V-101
b. CG101 — CG113
c. CG 750 & 751
d. LP 110 — LP 113
2. Please delineate all wetlands on site or add a note that none exist with the name and
qualifications of the person/entity making the determination [15A NCAC
02H .1042(g)(iii)].
3. The seasonal high water table elevation for the bioretention cell is provided as El. 230,
consistent with a 2016 boring (13-5) conducted by Froehling & Robertson, Inc. (according
to Appendix I of the submitted geotechnical report). However, according to the report
titled "Seasonal High Water Table Determination and Hydraulic Conductivity Testing"
by Three Oaks Engineer, dated March 27, 2019, borings B-5 and B-6, which are in the
area of the bioretention cell, show the seasonal high water table to be 72 and 40 inches
below the surface, respectively. Assuming that these depths from the existing ground
surface (approximately El. 242 or 243 based on the submitted existing grading plans), the
seasonal high water table is actually in the range of El. 236-240. This would not provide
the separation from the seasonal high water table required by Bioretention MDC 1. Please
provide justification for the use of the less conservative value.
D E QNorth Carolina Department of Environmental Quality Division of Energy, Mineral and Land Resources
512 North Salisbury Street 1 1612 Mail Service Center Raleigh, North Carolina 27699-1612
NoarH caaouNa �
D.panm.m of Environmental Quality/� 919.707.9200

4. Please specify that the sod used on the bioretention cell shall be a non -clumping, deep-
rooted species and that it shall not be grown in clay (Bioretention MDC 10).
5. Please address the following issues with regard to both wet ponds:
a. On the wet pond details, please specify that the slope of the vegetated shelf will
be no steeper than 6:1 (Wet Pond MDC 6). Please also specify the bottom and
top elevations of the vegetated shelf.
b. The drain time for the wet ponds was calculated for the maximum storage volume
in the wet ponds rather than the water quality volume. The drain time must be
between two and five days for the water quality volume only (Wet Pond MDC 7).
c. Not enough plants are specified for the vegetated shelf to meet the requirement of
50 plants per 200 square feet of shelf area (Wet Pond MDC 11).
6. The calculations for Wet Pond 1 use a contour area much smaller than that shown on the
plan for El. 240.
7. Please double check the scale bars on the plan sheets. It appears that the scale bars on at
least the grading sheets are incorrect.
8. Provide pdfs of all revisions, 2 hardcopies of revised plan sheets, and 1 bardcopy of other
documents. Pdfs must be uploaded using the form at:
hqps:Hedocs.deg.nc.gov/Fonns/SW ProjectSubmittal
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 March 12, 2020, 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 SW6200101 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
Corey. Anen(d),ncdenr. gov or [phone].
Sincerely,
6&t&� G_-
Corey Anen
Environmental Engineer
Stormwater Program
cc: Fayetteville Regional Office