SW3221001_Response To Comments_20230216

ROY COOPER
Governor
ELIZABETH S. BISER
Secretary
DOUGLAS R. ANSEL
Interim Director
Latham -Walters Engineering, Inc.
Attn: Carlos L. Ruano, PE
16507-A Northcross Drive
Huntersville, NC 28078
Niblock Homes, LLC
Attn: William Niblock, Member
759 Concord Parkway North, Suite 20
Concord, NC 28027
NORTH CAROLINA
Environmental Quality
December 15, 2022
Subject: Request for Additional Information
Stormwater Permit No. SW3221001
Brighton Park Subdivision
Cabarrus County
Dear Mr. Ruano and Mr. Niblock:
The Division of Energy, Mineral and Land Resources (DEMLR), received a Stormwater
Management Permit Application for the subject project on October 3, 2022. A review of that
information has determined that the application is not complete. The following information is
needed to continue the stormwater review:
1. Please QA/QC the submission. There were a number of inconsistencies noted in the
submission materials. The following items are not an exhaustive list of issues, but rather
demonstrative of the types of consistency issues noted during review. Please revise the
submittal items as needed.
a. The drainage area information shown in the Application (Section IV, 10) does not
correspond to the information shown in the Supplement-EZ Form. For example,
the total impervious area in the drainage area to SCM 1 is shown as 390,298 sf in
the Application and 390,257 sf. Tables were revised
b. The sum of the BUA allocated to the individual lots (178 lots @ 4,700 sf/lot =
836,600 sf) does not correspond to the value shown in the Supplement-EZ Form
(843,650 sf) for the entire site. Tables were revised
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c. The depth of the WQv for Sand Filter 1 is not calculated correctly. The WQv of
32,511 cf is interpolated between elevations 609 (cumulative volume of 0 cf @
609') 610 (cumulative volume of 16,488 cf @ 610'). Corrected
2. As designed, this project proposes new BUA that is not being captured & treated in
SCMs which is required in order to meet "Runoff Treatment" (15A NCAC
02H .1002(43)). Please either direct this untreated BUA to an SCM or, if that is not
practicable, you may permit the portions of the project area that do not drain to the SCMs
as low -density areas (provided that this area meets the low -density requirements). If
either of these options are not practicable, a variance can be sought in accordance with
15A NCAC 02H .1003(6). Location of new BUA was not identified in comment. However, storm was revised to catch additional
stormwater near the entrance. Calculations were also included to demonstrate improvements along the
existing storm network.
3. Please correct the following issues with the Application:
a. Section II, 4a — Please indicate that a 404/401 permit is required for this project.
Application was revised
b. Section IV, 6 — McAllister Creek appears to be partially located within the project
area. Please include this on -site surface water area in Section IV, 6 of the
Application, recalculate the Total Project Area (Section IV, 7), and the Project
Percent Impervious Area (Section IV, 8). Please revise as needed.
Application was revised
c. Section IV, 8 — Please do not forget to include the new BUA that does not drain to
the SCMs in this calculation. Please revise as needed. Ok
4. Please correct the following issues with the Supplement-EZ Form:
a. Cover Page:
i. Line 2 — Please remove the on -site surface water area (Line 4) from the
Project Area. Corrected
ii. Line 4 — This item (2.08 ac) does not correspond to the value in Section
IV,6 of the Application (0 ac). Please revise either as needed.
Corrected
b. Drainage Areas Page:
i. General:
1. See earlier comment with regard to the consistency of the drainage
area information as shown on this form, the Application, and the
calculations. Please revise as needed. Corrected
2. Line 19 — The design storm depth in this part of the State is 1.0 in.
Please revise. Corrected
3. Line 21 — "HydroCAD" is not an acceptable calculation method,
Please select either "Simple Method" or "Discrete NRCS Curve
Number Method" (The provided calculations appear to indicate
that the Simple Method was used). Corrected
ii. Entire Site Column:
1. General — The entire site column should be an accounting of the
entire project area, not just a summation of the other columns. New

BUA that does not drain to the SCMs should be accounted for in
this column. Please revise as needed. Ok
2. Lines 5 & 6 — Please ensure that the on -site surface water area is
not included in these items. Ok
3. Line 18 — This item should correspond to the value shown in
Section IV, 8 of the Application. Please revise as needed. Ok
c. Sand Filter Page:
i. Line 18 — Please include the SHWT elevations. If the SHWT elevation
was not encountered in the boring (or the SCM is being built in fill),
please indicate the lowest elevation that the absence of the SHWT is
known. For example, if a boring is done down to elevation 100 and the
SHWT was not encountered to that depth, use "<100" as the SHWT
elevation since the SHWT elevation is somewhere below that observed
elevation. Ok
ii. Lines 23, 26, 30, & 32 — See later comment with regard to Sand Filter
MDC 2. Corrected
iii. Line 31 — The bottom of the sand chamber refers to the top of the sand
layer. Corrected
iv. Line 33 — The physical depth of the sand chamber does not refer to the
depth of the sand layer that is provided, but rather the physical depth
provided above the sand layer (similar to Line 27 for the sediment
chamber). Ok
v. Lines 35 & 36 — The bypass device refers to the lowest weir/orifice that
allows stormwater runoff to bypass filtering through the sand layer. For
example, for Sand Filter 1, the lowest bypass device is the 6" orifice at
elevation 61 F as this allows stormwater runoff directly into the outlet
structure without first going through the sand layer. Corrected
vi. Line 39 — This item refers to the depth of the sand layer above the
underdrain pipe. Corrected
5. Please correct the following issues with the sand filter design:
a. General MDC 4 — Please provide calculations showing that the inlet and outlet
protection is adequate. Provided
b. Sand Filter MDC I — Please provide a map so that the soil borings provided in
the geotechnical report can be matched up with the proposed SCMs (The
geotechnical report references 7 SCMs while the final design only has 6 sand
filters). A BMP was eliminated & numbering was revised.
SHWT Report is updated. Map is provided.
c. Sand Filter MDC 2 — This MDC requires the sand chamber and sediment chamber
to have equivalent storage volume. For example, Sand Filter 1 shows a provided
sediment chamber volume of 18,600 sf and a provided sand chamber volume of
8,700 cf. Guidance in the Manual does allow the sediment chamber to be
oversized, however, you must still provide at least half of the design volume in
each chamber. For example, if the design volume is 2,000 cf, 1,000 cf must be

provided in both chambers, but the sediment chamber could be sized to provide
additional storage (say, 1,500 cf).
Ok, corrected
d. Sand Filter MDC 6 — Please include the sand media specification in the plans.
Labeled on plans ASTM C33
e. Sand Filter MDC 8 — The provided calculations assume that the sand media has a
permeability of 3.5 ft/day (1.75 in/hr). Please revise as needed to ensure sufficient
drawdown. Also, while not required, it is recommended that each underdrain line
have its own connection to the outlet structure, otherwise directing all of the
underdrain lines to a single pipe creates a chokepoint (Please refer to Part A-5 of
the Manual for more information). Drawdown was revised to 2in/hr as listed on
Sand Filter MDC 8
f. While not required, it is strongly recommended to limit the amount of impervious
area draining to the sand filters (each proposed sand filter has a drainage area with
a percent impervious cover of approximately 40%-50%) and to limit the drainage
areas to the sand filters to 5.0 acres or less. These design constraints are
recommended to limit the amount of fines entering the sand filters (fines cause the
sand filter to become clogged which necessitates more frequent maintenance to
bring the sand filters back into compliance).
6. 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:
Jim Farkas
512 N. Salisbury Street, Office 640E
Raleigh, NC 27604
ii. For LISPS:
Jim Farkas
1612 Mail Service Center
Raleigh, NC 27699-1612
iii. Hand Delivery:
Please reach out to me prior to hand delivering a submission to make
sure that I (or someone else in my group) will be able to receive the
submission. Do not leave the package in the foyer with the
security guard.
NOTE: Hard copies should not be sent to a Regional Office. Doing so
will delay the review process and the submission package may be lost
while being sent from the Regional Office to me in the Central Office.

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 January 14, 2023, 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 SW3221001 on all correspondence.
Extension was provided by Jim Farkas on 2/8/2023
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,
V"VI
Jim Farkas
Environmental Engineer
Stormwater Program
cc: Mooresville Regional Office