SW3191204_Add Info_20200415

ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
S. DANIEL SMITH
Director
Steve Farmartino, PE
1927 South Tryon Street, Suite 310
Charlotte, NC 28203
NORTH CAROLINA
Environmental Quality
April 15, 2020
Subject: Request for Additional Information
Stormwater Permit No. SW3191204
Arka Heights
Union County
Dear Mr. Farmartino:
The Division of Energy, Mineral and Land Resources (DEMLR), received a Stormwater
Management Permit Application for the subject project on March 18, 2020. 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 4f — "Please include the existing BUA. " Based on the information
shown in the Application, there are 15,816 sf (10,333 sf + 5,483 sf) of existing BUA
located on site in existing conditions. In proposed conditions, there will be 267,401 sf
(133,961 sf + 109,625 sf + 15,265 sf + 8,550 sf) of BUA in proposed conditions. This
results in a net increase of 251,585 sf of BUA. The drainage area to the proposed SCM
only contains 243,586 sf (133,961 sf + 109,625 sf) of BUA. Per 15A NCAC
02H .1002(43) and 15A NCAC 02H .1003(3)(b), in order to meet the runoff -treatment
method, at least the net increase in built -upon area must be treated in the SCM(s). Please
ensure that the existing built -upon area is correctly shown. In order to eliminate some
confusion, BUA tables can be added to sheets C-405 & C-406.
2. Original Comment 5 —"Please delineate the wetlands on the plans or provide a note
stating that no wetlands exist. Provide documentation of the qualifications and identity of
the individual who made this determination (Section VI, 8m). " Please indicate where this
note was placed in the plan set (I could not find it, but I may have overlooked it).
3. Original Comment 8 — "Since the wet ponds are connected via a 0% slope equalizing
pipe and wet pond 2 does not have an outlet/riser structure, the two wet ponds should be
treated as a single wet pond in the Application and supporting documents... " Please
correct the following issues:
D EQ 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 _
o.PaWnamofEnvironmental Quality /� 919.707.9200

a. Application:
i. Section IV, 9 — This project should only have one drainage area since
there is only one proposed SCM.
ii. Section IV, 10 — Portions of the site that do not drain to the proposed SCM
(Drainage areas 3 & 4) do not need to be included in this table. Generally,
since there is only one SCM, there would only be one drainage area
column, but due to the nature of this facility, including the "east" and
"west" drainage areas is acceptable.
b. Calculations:
i. Ensure that the proposed wet pond meets all sizing MDCs (It appears that
the design meets all of the sizing requirements, you just needs to show that
the entire wet pond (not just the east and west portions individually) meets
the MDCs).
4. Original Comment 9cii — "Runoff from the forebay to STM B-EP short circuits the wet
pond (Wet Pond MDC 4). Please revise the design to avoid this. " Please provide a detail
for the proposed permanent baffle.
5. Original Comment 10b — "The percent impervious area for the drainage area to wet
pond I is shown as 63% in the Supplement-EZ Form, 70% in the Application, and 80% in
the calculations. " The percent impervious area for the drainage area to the wet pond is
shown as 60% in the Supplement-EZ Form, 62.5% in the Application ((133,961 sf +
109,625 sf)/(222,329 sf + 167,250 sf)), 62.5% in the calculations ((5.11 ac * 60% + 3.84
ac * 66%)/(5.11 ac + 3.84 ac)=62.5%), and 70.6% in the HydroCAD printout ((5.11 ac
66.54% + 3.84 ac * 76.04%)/(5.11 ac + 3.84 ac)=70.6%). Please revise for consistency.
6. It is recommended that the latest version of the Supplement-EZ Form be completed and
submitted. This file can be found at the following link:
https://deq.nc. gov/about/divisions/energy-mineral-land-resources/energy-mineral-land-
permit-guidance/stormwater-bmp-manual
7. If the updated Supplement-EZ Form will not be used, please correct the following issues
with the provided Supplement-EZ Form:
a. Proposed new BUA/Total BUA — Please include the 10,030 sf of future BUA into
this value.
b. Percent BUA of drainage area — Recalculate this value taking the prior comment
into consideration.
c. Surface area of the main permanent pool — This value (19,609 sf) does not match
the value from the provided stage -storage table (6,476 sf + 8,936 sf = 15,412 sf).
Please revise for consistency.
d. Volume of the main permanent pool — This value (52,038 cf) does not match the
value from the provided stage -storage table (52,117 cf). Please revise for
consistency.
e. Elevation of the bottom of the permanent pool - When entering information into
the form that is different for the east and west portions of the pond, you should
put a note in the note box explaining this and showing both values.

f. Volume of the forebay — This value (8,110 cf) does not match the value from the
provided stage -storage table (8,479 cf). Please revise for consistency.
g. Depth of the forebay at entrance/exit — The provided cross -sections in the plans
do not show this elevation change from the entrance to the exit. Please revise the
plans to show this. Also, ensure that at least six inches of sediment storage are
provided for both the entrance and exit of the forebay.
h. Clean -out depth for forebay — The cleanout depth is the distance from the
permanent pool surface elevation to the top of he sediment storage elevation.
i. Drawdown time for the temporary pool — This value (92.16 hrs = 3.84 days) does
not match the value from the provided in the calculations (3.98 days). Please
revise for consistency.
8. The Total Impervious Surface Area for Drainage Area 1 should be a summation of all of
the proposed BUA (On -site and Future) listed in the Drainage Area 1 column of the table
in Section IV, 10.
9. NOTE: Per Division policy, the next review of this application will be the final review.
Failure to provide the requested information will result in the project being returned as
incomplete. The return of a project will necessitate resubmittal of all required items,
including the application fee.
10. Provide pdfs of all revisions, 2 hardcopies of revised plan sheets, and 1 hardcopy of other
documents. Pdfs must be uploaded using the form at:
hgps://edocs.deq.nc.gov/Forms/SW Project Submittal
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 May 15, 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 SW3191204 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,

)elfM4�
Jim Farkas
Environmental Engineer
Stormwater Program
cc: Mooresville Regional Office