SW1191201_Add Info_20210803

ROY COOPER
Governor
ELIZABETH S. BISER
Secretary
BRIAN WRENN
Director
Francis Slinsky, PE
5410 Trinity Road
Raleigh, NC 27607
NORTH CAROLINA
Environmental Quality
August 3, 2021
Subject: Request for Additional Information
Stormwater Permit No. SW1191201— Major Modification
NCNG Morganton Regional Readiness Center
Burke County
Dear Mr. Slinsky:
The Division of Energy, Mineral and Land Resources (DEMLR), received a Stormwater
Management Permit Modification Application for the subject project on July 19, 2021. A review
of that information has determined that the application is not complete. The following
information is needed to continue the stormwater review:
1. Since this Application is a modification of a previously issued permit, please provide an
original, signed Designer's Certification (Section II, lb). The Designer's Certification
was included as part of the originally issued permit (the last page).
2. Please update the stormwater treatment summary (Section IV, 1) to mention the second
wet pond as it currently only mentions a single wet pond.
3. Since there is more BUA being added to this project as a result of the major modification,
the percent imperviousness of the site should increase from what was shown in the
original application (46.7%). Please ensure that the percent impervious area (Section IV,
8) is calculated correctly for the revised BUA amount).
4. The Major Modification Application included in the calculation booklet does not include
the second wet pond drainage area information (Section IV, 9 & 10). This information is
however included in the loose hard copies of the Major Modification Application that
were provided. If you are providing a revised version of the calculation booklet as part of
the resubmittal, please update this item, otherwise, I can just remove this item from the
calculation booklet (There are also some other mismatches between the Major
Modification Application in the calculation booklet and the loose copies of the
Application so these inconsistencies should also be corrected if applicable).
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 _
oepm nt of EnvimnmwUl uwl ry 919.707.9200

5. Please provide original signatures on the Supplement-EZ Form and O&M Agreement
Form (Section VI,3).
6. The Application is not signed by the original signing official, Rodney Newton (Section
III,1 a & Section X). If you would like to change the Applicant from Rodney Newton to
Kenneth Cook Jr., you will need to complete the Permit Information Update Form
(htlps:Hdeq.nc. gov/about/divisions/energy-mineral-and-land-
resources/stormwater/stormwater-pro_rg aMZpost-construction). If Kenneth Cook Jr. has
delegated signature authority for Rodney Newton, you will need to provided official
documentation of that.
7. There are some noted discrepancies between the information from the original
application and this modification. For example, the original application stated that the
pre -development on -site BUA is 5.41 ac. while the major modification indicates that the
pre -development on -site BUA is 6.36 ac. (This example is demonstrative of the nature of
the inconsistencies, not an exhaustive list). Please ensure that all of the information
presented in the Major Modification is consistent with the information from the initial
Application as applicable.
8. The drainage area information for wet pond 1 shown in the Application does not match
the drainage area information shown in the Supplement-EZ Form, nor the drainage area
information shown in the plans. For example, the Application indicates that this drainage
area contains 570,010 sf of BUA, the Supplement-EZ Form indicates 593,666 sf of BUA,
and the plans indicate 563,666 sf (12.94 ac.). Please ensure that the drainage area
information is consistent throughout the submission. If the drainage area information for
wet pond 1 has changed from what was originally permitted, you will need to provide
updated design calculations for wet pond 1.
NOTE: The design of wet pond 1 was not reviewed for compliance with the MDCs since
it is unclear if the design of the wet pond will be altered as a part of this Major
Modification. If this wet pond will be modified (any change to the drainage area size,
drainage area composition, or grading/design of the wet pond) it needs to be stated in the
stormwater narrative and revised calculations demonstrating that the wet pond is still
compliant with all design requirements need to be provided. If this wet pond is not being
modified from what was initially approved, the submittal items must reflect this.
9. The drainage area information for wet pond 2 shown in the Application does not match
the drainage area information shown in the Supplement-EZ Form. For example, the
Application indicates that this drainage area contains 149,945 sf of BUA and the
Supplement-EZ Form indicates 163,786 sf of BUA (The breakdown of the proposed
BUA also does not match). Please ensure that the drainage area information is consistent
throughout the submission.
NOTE: The design of wet pond 2 was reviewed under the assumption that the
information in the plans is correct (Drainage area = 4.63 ac. & BUA = 3.76 ac.). If this
information is not correct, this wet pond will need to be re -reviewed for compliance with
the MDCs.

10. The volume of the main permanent pool of wet pond 2 appears to be calculated
incorrectly. The volume of the main pool should not include any portion of the sediment
storage zone (Plan sheet C8.17 indicates that the sediment storage elevation is at 1206.00,
the Supplement-EZ Form indicates this elevation to be at 1207.00, and the calculations
indicate this elevation to be at 1205.00). Please ensure that this volume is calculated
correctly, and revise the submission as needed for consistency.
NOTE: Generally, when dealing with inconsistencies in a submission, the information in
the plans supersede the calculations which supersede the supplement forms. Please ensure
that the information in the submission is consistent.
11. Using the information from plans and the calculations, the average depth of the main
pool of wet pond 2 is less than the required 3 foot minimum (Wet Pond MDC 2). The
surface area, 5,502 sf was taken from the stage -storage table and the volume of the main
pool was recalculated as approximately 14,860 cf. based on the sediment storage
elevation from the plans. Please revise as needed.
12. There is an insufficient amount of sediment storage depth provided in the forebay of wet
pond 2 (Wet Pond MDC 3). Plan sheet C8.17 indicates that the excavated bottom of the
forebay near the exit is at elevation 1206.00 and that the top of the sediment storage zone
is at elevation 1206.25. This results in a sediment storage depth of only 3 inches whereas
6 inches are required. Please revise.
13. The elevations provided in the stage -storage table in the calculations for the temporary
ponding portion of the wet pond appear to be incorrect (These elevations are above
2,000.0 ft whereas the site is at about elevation 1,200.0 ft).
14. The drawdown orifice for wet pond 2 is shown on plan sheet C8.17 as having a 3.5 in.
diameter. This results in a drawdown time of less than 2 days for the design volume,
which is not acceptable (Wet Pond MDC 7). Please revise. The outlet configuration is
also unusual in that there are drawdown orifices located both above and below the
permanent pool elevation (both endcaps on the tee are shown to have a drawdown
orifice). Please ensure that this is accounted for correctly in the drawdown calculations.
15. The following discrepancies were noted between the plans/calculations and the design of
wet pond 2 as shown in the Supplement-EZ Form (Wet Pond Page). Please revise as
needed:
a. Line 20 — The excavated bottom elevation of the main pool (1206.0 ft) is shown
as 1205.0 ft on plan sheet C8.17.
b. Line 21 — The top elevation of the sediment storage zone of the main pool (1207.0
ft) is shown as 1206.0 ft on plan sheet C8.17.

c. Line 25 — The temporary pool elevation (1206.25 ft) is lower than the permanent
pool elevation. This item should be the water surface elevation of the design
volume (slightly over 1212.0 ft).
d. Line 27 — As noted earlier, the volume of the main pool (19,358 cf) should be
closer to 14,860 cf (based on the sediment storage elevation (1206.0 ft) from the
plans and stage -storage table from the calculations).
e. Line 28 — As noted earlier, the average depth (3.52 ft) would be less than 3.0 ft if
the revised main pool volume is used in "Equation 2" to calculate the average
depth of the main pool.
f. the volume of the forebay (2,968 cf) should be closer to 2,814 cf (based on the
sediment storage elevation (1206.25 ft) from the plans and stage -storage table
from the calculations).
g. Line 34 — The cleanout depth (54 in) does not match the cleanout depth from plan
sheet C8.17 (51 in). The cleanout depth is the distance from the permanent pool
surface elevation (1210.5 ft) to the top elevation of the sediment storage zone
(1206.25 ft). 1210.5 ft — 1206.25 ft = 51 in.
h. Line 37 — The orifice diameter (1.5 in) is shown as 3.5 in on plan sheet C8.17.
i. Line 40 — As noted earlier, the temporary pool drawdown time (3.6 days) is
calculated as less than 2.0 days based on the drawdown orifice configuration
shown on plan sheet C8.17.
j. Line 44 — The depth of the forebay at the exit (51 in) is shown as 54 in. on plan
sheet C8.17 (The elevation of the forebay is shown at elevation 1206.0 ft and the
permanent pool is shown at elevation 1210.5 ft).
16. When uploading the electronic files, please ensure that each different type of file is
uploaded under its appropriate file type (For example, every file that was electronically
submitted for this submission was uploaded under the "Stormwater Report" file type
which led to most of the uploaded files being incorrectly named/classified in our
repository). Additional file types can be added to the upload form by clicking on the
"Add Another Post -Construction File Upload" link immediately following the file upload
section of the form.
17. Please do not upload copies of the review fee check through the electronic file upload
portal. These electronic files end up in our public online repository that can be accessed
by anyone with an internet connection (we do screen the uploads before releasing them to
the repository to prevent sensitive information from being posted, but it should still be
avoided).
18. 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 LISPS:
Suzanne McCoy
1612 Mail Service Center
Raleigh, NC 27699-1612
NOTE: We are located on the 6th floor of the Archdale Building, not the 9th floor.
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 September 1, 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 SW1191201 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,
)-6mj�
Jim Farkas
Environmental Engineer
Stormwater Program
cc: Asheville Regional Office