SW3221005_Add Info_20230111

ROY COOPER
Governor
ELIZABETH S. BISER
Secretary
DOUGLAS R. ANSEL
Interim Director
NORTH CAROLINA
Environmental Quality
January 11, 2023
Dewberry Engineers Inc.
Attn: Brian LaFranchi, PE
9300 Harris Corners Parkway, Suite 220
Charlotte, NC 28269
AND
Boulder Run, LLC
Attn: Jason Shott, Registered Agent
131 Plantation Road
Mooresville, NC 28117
Subject: Request for Additional Information
Stormwater Permit No. SW3221005
Boulder Run
Cabarrus County
Dear Mr. LaFranchi and Mr. Show
The Division of Energy, Mineral and Land Resources (DEMLR), received a Stormwater
Management Permit Application for the subject project on October 14, 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. As designed, this project does not meet the design requirements to be considered as a
low -density development. Per 15A NCAC 02H .1003(2)(c), piping networks (such as
those throughout the project area) are not allowed. Pipes are only allowed in low -density
projects for unavoidable situations where a swale would not work (such as transporting
stormwater underneath a driveway) and in certain unavoidable situations where non-
erosively conveying stormwater via a swale is not practical. Please revise the submission
so that this project meets all of the low -density requirements or revise the submission so
that this project meets all of the high -density requirements. Please note that not all
projects are well suited to be low -density projects, even if the project density of the entire
site is less than what is required per statute since there are other factors, as mentioned
above, that must be incorporated for a project to be considered as low -density. The below
comments were made under the assumption that the project will be reconfigured to meet
the low -density requirements.
D E Q�� 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 _
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2. While not required, it is recommended to remove the level-spreader/filter-strips (LS/FS)
since either the pipes feeding the LS/FS will be removed to meet the low -density design
requirements or the project will require primary SCMs (LS/FS are secondary SCMs) to
meet the high -density treatment requirements.
a. If the LS/FS will remain, please do the following:
i. Please provide calculations showing how the LS/FS are sized.
ii. Please revise the design so that all of the MDCs (General and LS/FS) have been
met. The following MDCs do not appear to have been met based on the provided
information:
1. General MDCs:
a. MDCs 8 & 9 — Please provide a maintenance access and easement for the
SCMs. This access/easement should be indicated on the plans. It is noted
that there are grading easements proposed around the LS/FS areas, if these
easements will be used to meet the MDC, please indicate this on the plans.
2. LS/FS MDCs:
a. MDC 1 — The LS/FS appear to be too short. It is indicated in the
Supplement-EZ Form that no bypass devices have been provided, therefore
the design requirements of LS/FS MDC 3 would be in place (LS/FS length
sized for the 10-year design storm). Sizing calculations for the LS/FS have
not been provided nor have LS/FS lengths been indicated on the plans,
however, the LS/FS seem to be approximately an order of magnitude
shorter than they ought to be. For example, the drainage area to LS/FS 1 is
shown as 2.22 ac, the 10-year, 5-minute storm intensity is 7.12 in/hr, and
an approximate Rational Coefficient could be 0.45 (assumed for the point
of explanation, you will need to provide an actual Rational Coefficient),
resulting in a possible flowrate of 7.11 cfs (0.45 * 7.12 in/hr * 2.22 ac). Per
the MDC, 10 feet of LS/FS length is required per cfs of design flow so 72 ft
of LS/FS could be required (I I ft of provided LS/FS is listed in the
Supplement-EZ Form).
b. MDC 2 — A bypass device was not mentioned in the Supplement-EZ Form
but appears to be included in the plans. Please provide a detail of the
bypass device if being used, including elevations of the bypass weir and
elevations for the lip of the LS/FS.
c. MDC 4 — This item is required and does not appear to be provided. The
proposed Duraslot configuration is different enough from a standard LS/FS
that special approval would be needed (in accordance with 15A NCAC
02H .1003(6)).
d. MDCs 5, 7, 8, & 10 —Details for the LS/FS were not provided so these
MDC were unable to be verified.

iii. Please revise Section IV of the Application so that the drainage area for each
individual SCM is listed.
b. If the LS/FS will be removed, please do the following:
i. Please revise the submittal materials (Application, Section IV, 10, Supplement-EZ
Form, O&M Agreement Form, plans, etc...) to remove the references to the
LS/FS.
3. Please include the on -site surface waters on the plans and in the submittal materials (15A
NCAC 02H .1042(2)(g)(iii)). Surface waters are any blue line stream that show up on the
USGS topographic map. There appear to be multiple surface waters in or near the project
area (southern project boundary, western project boundary and one running north -south
through the project. Please ensure that the surface waters are clearly shown on the plans
(.1042(2)(g)(iii)), the required vegetated setback (.1003(4) & .1017(10)) is shown on the
plans (.1042(2)(g)(iii)), and that the surface water area is excluded from the project area
and project density calculation in the Application and Supplement-EZ Form. NOTE:
BUA is not allowed inside the vegetated setback except as permitted per 15A NCAC
02H .1003(4) & .1017(12).
4. Please verify that the scales shown on the plans are correct (Section VI, 8f of the
Application). For example, sheets C4.04-C4.06 all appear to be drawn at the same scale
however the scale labels are shown as 1" = 150', 1" = 30', & 1" = 60' respectively.
Please revise.
5. Per the provided submittal items, some of the side slopes of the vegetated conveyances
are steeper than 3:1 (15A NCAC 02H .1003(2)(c)(i)). If providing slopes in excess of 3:1
steepness, engineering calculations and an on -site soil investigation must be provided
demonstrating that the soil and vegetation will remain stable in perpetuity.
6. Please provide calculations indicating where the design flow values for the vegetated
conveyances came from (15A NCAC 02H .1042(2)(f)). NOTE: If using a time of
concentration greater than 5 minutes, please also provide calculations showing how these
values were determined.
7. The peak, 10-year flow velocities on some of the vegetated conveyances appear to be too
high (15A NCAC 02H . 1003 (2)(c)(ii)). Maximum non -erosive swale velocities are
provided in Part C-11 of the Manual (or can be provided from another source if you so
choose). NOTE: When determining the stability of the vegetated conveyances, please
ensure that the proposed design conditions are used, only include stabilization matting if
it is permanent.
8. Please revise the Deed Restriction documents to list the per lot BUA allocation (in square
feet). A table can be added to the Deed Restriction document if the table that was
provided under item 6 is insufficient.
9. Please correct the following issues with the Application:

a. Section IV, 6-8 — See earlier comment.
b. Section IV, 10 — This table should correspond to the table on the Drainage Areas Page
of the Supplement-EZ Form (except for the "Entire Site" column, that column is
unique to the Supplement-EZ Form). Each SCM (or the low -density area) should get
its own column.
10. Please correct the following issues with the Supplement-EZ Form:
a. Cover Page:
i. Line 4 — Include the on -site surface water area (also, revise Line 2 as needed to
exclude the on -site surface water area).
ii. Line 9 — See earlier comment.
b. Drainage Areas Page:
i. Entire Site Column — The entire site column should be an accounting of the entire
project area, not just a sum of the other columns. Any BUA proposed within the
project area (whether or not it is already included in one of the other columns)
should be included in this column. When this column asks for the "drainage area"
of the entire site, list the project area.
ii. NOTE: If no SCMs are proposed for a low -density project, a single low -density
drainage area is use that is identical to the entire site column.
Low -Density Page:
i. Line 4 — See earlier comment.
ii. Line 5 — See earlier comment.
iii. Line 14 — Please answer this item.
iv. Swale Table — Please enter the design information for the proposed vegetated
conveyances.
d. LS/FS Page:
i. Line, 2, 11, 18, 20-23, & 24 — See earlier comments.
ii. Line 25 — Please answer this item.
iii. Line 29 — This item is required per LS/FS MDC 7.
iv. Lines 30 & 31 — The transition zone does not appear to be shown on the plans.
v. Lines 36-40 — These items are required per LS/FS MDC 10.
11. 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 640M
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.
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 February 10, 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 SW3221005 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,
Jim Farkas
State Stormwater Engineer
DEMLR Post -Construction Stormwater Program
cc: Mooresville Regional Office