SW3221001_Response To Comments_20230628

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ROY COOPER -
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ELIZABETH S.BISER L,za� �_
Secretary *�` ^D�°'*='
DOUGLAS R.ANSEL NORTH CAROLINA
Interim Director Environmental Quality
May 17, 2023
Latham-Walters Engineering, Inc.
Attn: Carlos L. Ruano, PE
16507-A Northcross Drive
Huntersville, NC 28078
AND
Niblock Homes, LLC
Attn: William Niblock, Member
759 Concord Parkway North, Suite 20
Concord, NC 28027
Subject: Second 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 February 16, 2023. A review of that
information has determined that the application is not complete. The following information is
needed to continue the stormwater review:
1. Prior Comment 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)." BUA is identified on plan sheet C 17.1 as being located
in untreated drainage areas (portions of Brennan Street and Oleander Street that drain
towards the ROW). 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). Please
revise as needed. Untreated BUA meets low-density requirements.
EZ Supplement form revised & updated.
2. Prior Comment 3.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." Per the
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provided information, a total of 1,289,544 sf(1,267,671 sf of BUA draining to the SCMs
plus 21,873 sf of BUA being untreated) of BUA is located in a project area of 85.71 ac
which results in a percent BUA of approximately 35%. Please clarify/revise as needed.
NOTE: Please also revise the %BUA for the entire site in the Supplement-EZ Form.
BUA& Low-Density were updated & revised.
3. Prior Comment 4.b.ii.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."
The 21,873 sf of BUA shown on plan sheet C17.1 as being untreated should be accounted
for in the entire site column since this BUA is located within the project area, even
though it does not drain to any of the SCMs. For Lines 5 & 6 of the Entire Site Column,
the total project area(85.71 ac, expressed in square feet) should be used for the "drainage
area". NOTE: The sum of the values in the SCM columns may not add up to the Entire
Site Column values. BUA& Low-Density were updated & revised.
4. Prior Comment 5.a.— "General MDC 4—Please provide calculations showing that the
inlet and outlet protection is adequate." It is noted that riprap sizing calculations for the
outlets were provided, however, the riprap sizing calculations for the inlets into the SCMs
do not appear to have been provided. Please provide these sizing/design calculations.
RipRap Apron Design included.
5. Sand Filter MDC la—Per the provided plans, the invert of the underdrain system (in the
outlet structure) is shown to be at a lower elevation than the excavated bottom of the sand
chamber. For example, for Sand Filter 1, the invert of the underdrain pipe, as it enters the
outlet structure, is shown to be at elevation 608.0' whereas the excavated bottom of sand
chamber is shown to be at elevation 609.0'. NOTE: The soil boring information for Sand
Filter 1 shows the SHWT at or below elevation 606.79' which is only 1.21' below 608.0'
(a similar situation exists for Sand Filters 2 & 3). Please revise/clarify as needed.
Inverts were revised & updated.
6. Please correct the following issues with the Supplement-EZ Form, Sand Filter Page:
a. SCM 1:
i. Lines 23 & 30—The volume provided in these chambers should be measured
from the bottom of the chamber (611.0') to the invert of the lowest bypass device
(613.0'). The sum of these volumes is 31,546 cf whereas interpolating the volume
between elevations 611.0' & 613.0' from the stage-storage table shows a
cumulative storage volume of about 36,000 cf. Inverts were revised & updated.
ii. Lines 26 & 32—The provided stage-storage table shows a cross-sectional area of
both the sand and sediment chambers of 15,196 sf whereas the sum of these Lines
of the Supplement-EZ Form only equals 9,643 sf. The provided value for Line 32
(2,640 sf) is smaller than the sand filter area as shown on the plans (4,044 sf).
NOTE: Line 32 should correspond to the cross-sectional area of the sand
chamber(not just the sand filter) at the bottom elevation of the sand filter (Line
31). Ok, revised & updated.
iii. Line 35 —The provided value, 612 ft, does not correspond to the invert of the
bypass orifice as shown in the plans, 613 ft.
Ok, revised & updated.
b. SCM 2:

i. Line 2—The provided value (11,371 cf) does not correspond to the value from the
calculations (12,253 cf). Ok, revised & updated.
ii. Lines 23 & 30—The sum of these items (33,411 cf) exceeds the cumulative
storage volume provided below the invert of the bypass orifice at elevation 634.0'
(25,930 cf). Ok, revised & updated.
iii. Lines 26 & 32—The provided stage-storage table shows a cross-sectional area of
both the sand and sediment chambers of 15,777 sf whereas the sum of these Lines
of the Supplement-EZ Form only equals 14,243 sf. Ok, revised & updated.
iv. Lines 27, 28, & 33 —The provided values (24") do not correspond to the
geometry of the sand filter (18"). Ok, revised & updated.
c. SCM 3:
i. Line 2—The provided value (11,125 cf) does not correspond to the value from the
calculations (10,860 cf). Ok, revised & updated.
ii. Lines 23 & 30—The sum of these volumes is 20,054 cf whereas the stage-storage
table shows a cumulative storage volume at elevation 630.0' of 21,147 cf. Ok, revised & updated.
iii. Lines 26 & 32—The provided stage-storage table shows a cross-sectional area of
both the sand and sediment chambers of 9,379 sf whereas the sum of these Lines
of the Supplement-EZ Form only equals 6,313 sf. The provided value for Line 32
(1,360 sf) is smaller than the sand filter area as shown on the plans (1,810 sf).
Ok, revised & updated.
d. SCM 4:
i. Line 2—The provided value (11,772 cf) does not correspond to the value from the
calculations (11,904 cf). Ok, revised & updated.
ii. Lines 23 & 30—The sum of these volumes is 22,242 cf whereas interpolating the
volume between elevations 631.0' & 633.0' from the stage-storage table shows a
cumulative storage volume of about 23,000 cf. Ok, revised & updated.
iii. Lines 26 & 32—The provided stage-storage table shows a cross-sectional area of
both the sand and sediment chambers of 10,175 sf whereas the sum of these Lines
of the Supplement-EZ Form only equals 8,932 sf. Ok, revised & updated.
e. SCM 5:
i. Lines 23 & 30—The sum of these volumes is 17,207 cf whereas interpolating the
volume between elevations 613.0' & 615.0' from the stage-storage table shows a
cumulative storage volume of about 18,000 cf. Ok, revised & updated.
ii. Lines 26 & 32—The provided stage-storage table shows a cross-sectional area of
both the sand and sediment chambers of 7,472 sf whereas the sum of these Lines
of the Supplement-EZ Form only equals 6,366 sf. Ok, revised & updated.
f. SCM 6:
i. Line 2—The provided value (12,603 cf) does not correspond to the value from the
calculations (12,074 cf). Ok, revised & updated.
ii. Lines 23 & 30—The sum of these volumes is 27,825 cf whereas the stage-storage
table shows a cumulative storage volume at elevation 620.0' of 28,742 cf. Ok, revised & updated.
iii. Lines 26 & 32—The provided stage-storage table shows a cross-sectional area of
both the sand and sediment chambers of 12,647 sf whereas the sum of these Lines
of the Supplement-EZ Form only equals 11,340 sf.
Ok, revised & updated.

7. 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 USPS:
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.
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.
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 June 16,2023,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.
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,
)- ---ilk
Jim Farkas
Environmental Engineer
Stormwater Program
cc: Mooresville Regional Office