SW3190804_Add Info_20200210

ROY COOPER
Governor
MICHAEL S. REGAN
Secretary
BRIAN WRENN
Acting Director
Patrick Murphy, PE
127 Ben Casey Drive Suite 101
Fort Mill, SC 29708
NORTH CAROLINA
Environmental Quality
February 10, 2020
Subject: Request for Additional Information
Stormwater Permit No. SW3190804
Pine Forest II
Iredell County
Dear Mr. Murphy:
The Division of Energy, Mineral and Land Resources (DEMLR), received a Stormwater
Management Permit Application for the subject project on January 3, 2020. A review of that
information has determined that the application is not complete. The following information is
needed to continue the stormwater review:
1. Original Comment 5 "Please recalculate the `Project percent of impervious area' value
taking into account the prior comment (Section IV, 8). " — The percent impervious area
should be calculated as the total BUA in proposed conditions divided by the total project
area. Please ensure that this value is calculated correctly (344,344 sf / 28.96 ac # 30.8%).
2. Original Comment 11 "Since this project is subject to 15A NCAC 02H .1017, the
minimum vegetated setback from surface waters is 30 feet (Section VI, 8p). " Sheet SP-1
indicates that the vegetated buffer is 25 ft. Please revise.
3. Original Comment 15 "Please only fill this section out if Section III, 2 has been filled out
(Section IX). " It appears that the Applicant signed this section. With your permission, I
will cross out the signature on Section IX of the Application. If this is unsatisfactory,
please provide a corrected original hard copy of the Application.
4. A dry pond (dry detention) and a sand filter are two separate facilities (Section IV, 1).
Please refer to the latest version of the Stormwater Design Manual:
https://deq.nc. gov/about/divisions/energy-mineral-land-resources/energy-mineral-land-
permit-guidance/stormwater-bmp-manual. If you would like to create a treatment train of
a dry pond and a sand filter, you must provide a dry pond up/down stream of each
provided sand filter. Please revise this section if you are not providing a treatment train.
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 CAROUNA -
OaparOneMofEnWromnaMal0ua6ry\ r 919.707.9200

5. Please correct the following issues with the Supplement-EZ Form:
a. Drainage Area Sheet
i. Entire Site Column
1. Lines 8 & 9 — Do not include the off -site areas as part of the entire
site.
ii. Drainage Area Columns
1. Line 10 - Please include the "Other" BUA from the table in
Section IV, 10 of the Application. The items of line 10 should add
up to line 7.
2. Line 17 — The design storm is 1 in, not 5 in.
3. Line 18 — Please recalculate the design volume. The design volume
is based off of the design storm.
4. Line 19 — Please use the "Simple" or "NRCS Composite Curve
Number" method to calculate the design volume. More
information on these methods can be found in Part B of the
Manual.
b. Sand Filter Sheet
i. Line 2 - Please recalculate the design volume. The design volume is based
off of the design storm.
ii. Line 18 — Per the provided soils report, the SHWT was not encountered
for sand filter 1 and is approximately at elevation 781 for sand filter 2.
Please indicate that the SHWT Elevation is "< 786" for sand filter 1 and
"781" for sand filter 2.
iii. Line 24 — Per the provided plans, there appears to be a permanent pool in
the sediment chamber, provided by the upturned elbow on the underdrain
that connects the sediment chamber to the sand chamber.
iv. Line 27 — Physical depth of the sediment chamber should be measured
from the bottom of the sediment chamber to the lowest bypass
(weir/orifice) elevation.
v. Line 28 — Ponding depth of the sediment chamber should be measured
from the top of the permanent pool (Bottom of the sediment chamber if no
permanent pool present) to the lowest bypass (weir/orifice) elevation.
vi. Line 33 — Physical depth of the sand chamber should be measured from
the bottom of the sand chamber to the lowest bypass (weir/orifice)
elevation.
vii. Line 34 — Ponding depth of the sand chamber should be measured from
the top of the permanent pool (Bottom of the sand chamber if no
permanent pool present) to the lowest bypass (weir/orifice) elevation.
viii. Line 35 — This is the elevation of the lowest point of the lowest bypass
device. Per the plans, there appears to be a small bypass orifice in the side
of the riser structure at or slightly above the WQv (The elevation is
unlabeled but should be per Sand Filter MDC 3). This, not the top of slab,
should be used for the bypass elevation.
ix. Line 36 — Type of bypass device appears to be an orifice.
x. Line 37 — The forebay spillway does not evenly distribute flow over the
entire surface of the sand filter (Sand Filter MDC 5).

xi. Line 39 - The plans indicate that there are only 12 in of sand above the
underdrain pipe
6. Please provide stage storage tables for the sediment chamber and sand chamber of each
sand filter so that the provided volumes may be verified (Sand Filter MDC 2).
7. Per the Stormwater Design Manual, Part C-6, under MDC 6, the entire surface area of the
sand chamber must contain sand. Please revise.
8. 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 March 11, 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 SW3190804 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,
)-6A::l VI - jwt-�
Jim Farkas
Environmental Engineer
Stormwater Program
cc: Mooresville Regional Office