SW4211101_Add Info_20211215

ROY COOPER
Governor
ELIZABETH S. BISER
Secretary
BRIAN WRENN
Director
Jordan D. Young, PE
7A Wendy Court
Greensboro, NC 27409
AND
CYD — Barrow Farms, LLC
Attn: Brian Craven, Manager
7349 W. Friendly Avenue, Suite H
Greensboro, NC 27410
NORTH CAROLINA
Environmental Quality
December 15, 2021
Subject: Request for Additional Information
Stormwater Permit No. SW4211101
Barrow Farm — Phases 1 & 2
Forsyth County
Dear Mr. Young and Mr. Craven:
The Division of Energy, Mineral and Land Resources (DEMLR), received a Stormwater
Management Permit Application for the subject project on November 8, 2021. 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 currently proposed, the project does not meet all of the requirements to be considered
as a low -density project (15A NCAC 02H .1003(2)). Please address the following if you
would like the project to be considered as a low -density project or, alternatively, redesign
the project to meet the high -density requirements outlined in 15A NCAC 02H .1003(3).
While it is noted that the proposed pipe networks are provided in order to daylight the
stormwater within them, 15A NCAC 02H .1003(2)(c) requires low -density projects to
transport flow that cannot be released as dispersed flow to be transported via vegetated
conveyances (there are certain exceptions to this rule, but those are reserved for
driveway/roadway crossings and certain situations were erosion is a concern due to steep
slopes). It is recommended to place the proposed water main underneath the stormwater
pipes so that the stormwater piping does not need to be so deep and the stormwater road
crossings can be handled with culverts as opposed to pipe networks (similar to how STP-
7 is situated). Using this design approach, it appears as though pipes STP-2, STP-3, &
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 _
oepm nt of EnvimnmwUl uwl ry 919.707.9200

STP-6 can be set up as culverts and pipes STP-1, STP-4, STP-5 can be replaced with
swales (there should be sufficient room in the drainage easement to place these swales
and the grading should not be too severe since the culverts will be a lot closer to the
surface than the current pipe network). If it is impossible to reconfigure the site in this
manner, please state this in the stormwater narrative and make the following design
modifications:
a. Please add curb outlet swales or vegetated areas that meet the design requirements
outlined in 15A NCAC 02H .1003(2)(d) downstream of the pipe networks. While
the pipe networks do not collect runoff from curb and gutter systems, the
proposed systems are comparable to a curb and gutter system and should therefore
be treated as such. If the area downstream of the pipe discharge has
channelization or a concentration of flow, the swale requirements must be met, if
the area downstream of the pipe discharge is free of channels or concentration of
flow, the vegetated area requirements can be used instead. Please also provide
calculations showing that
b. Please reduce the length of STP-4 and, if possible, eliminate this pipe. There
appears to be sufficient room in the back of these lots to grade a swale to daylight
this pipe network closer to the source. This may require additional grading, but
15A NCAC 02H .1003(2)(c) requires flow to be transported by vegetated
conveyance (not just transported via vegetated conveyance when convenient to do
so).
2. The provided project coordinates (36' 11' 10.13" N, 80' 06' 32.02" W) does not
correspond to the project location, it is about 2,000 ft off (Section I, 4 of the Application).
Please revise.
3. Please specify which additional permits are required for this project (Section II, 4).
4. Since the Applicant is also the Property Owner, Section III, 2 of the Application is not
required to be filled out. Please revise as needed.
5. This project does not appear to have a vested right claim (Section IV, 2a). Please revise.
6. This project does not appear to be located within the Cape Fear River basin (Section IV,
3). Please revise.
7. There appears to be a calculation error in the percent impervious area calculation (Section
IV, 8). The percent impervious area shown in this part of the Application should be
consistent with the values Shown in Section IV, 10. Percent impervious area can be
calculated using the methodology outlined in 15A NCAC 02H .1003(1).
8. The project area does not appear to directly drain to Belew Creek (Section IV, 10). Please
revise. This information can be found (along with the river basin) at the following web
address:

https://ncdenr.maps.arcgis.coralgpps/webappviewer/index.html?id=6e 125ad7628f494694
e259c80dd64265
9. Please show the areas in the top half of the table in Section IV, 10 of the Application in
square feet instead of acres.
10. Since this project is being permitted as a low -density project, the "drainage area" for the
project is the total project area (as explained in Section IV, 9). Please adjust the Total
Drainage Area and Off -Site Drainage Area values to reflect this.
11. The On -Site Buildings/Lots value is the total amount of BUA allocated to the individual
lots. Per the deed restriction document, there are 33 lots that are each allocated 3,599 sf
which would result in an On -Site Buildings/Lots value in the table of 118,767 sf (and 0 sf
value for the On -Site Parking since this item would refer to any parking area in the
common areas).
12. Since there are no off -site areas for a low -density project (see earlier comment) Section
IV, 11 is not required.
13. The provided calculations are insufficient (Section VI,7):
a. Please provide a source for the 10-year rainfall intensity (i) values used in the
provided calculations. If you are using time of concentration (tc) values that are
greater than 5 minutes, please also provide calculations showing how these values
were determined.
b. Please provide the Manning's roughness coefficient (n) values used for these
calculations (back calculating the Manning's roughness coefficient for swale 1
based on the provided swale geometry, flow rate, normal depth, and velocity
results in a Manning's value of approximately 0.24 which seems much too high).
c. Please provide calculations for all proposed vegetated conveyances (see attached
map of excluded vegetated conveyances. It is unclear whether or not the swale
downstream of STP-7 is its own swale or if it is a separate swale).
NOTE: Swales or vegetated conveyances that discharge to wetlands should do so
at no more than 2.0 fps to be considered as non -erosive.
14. The provided details of the vegetated conveyances are insufficient (Section VI,81). Please
clearly show the bottom width of the vegetated conveyances on the detail (the
calculations show that the vegetated conveyances have a bottom width of 2 ft but the
detail shows a "V" shaped ditch) and please specify the grass type to be used in the
vegetated conveyances (This is required to determine the maximum allowable velocity
within the vegetated conveyance per the table in Part C-11 of the Design Manual).
15. Please delineate the drainage areas to the vegetated conveyances in the main set of plans
(Section VI, 8o).The provided drainage area delineation on plan sheet C-6.0 are

delineated for the yard inlets, not the vegetated conveyances (there is some overlap
between these, but they are not necessarily the same) and plan sheet C-3.0 (the plan sheet
with the vegetated conveyances labeled) does not contain drainage area delineations.
Please revise.
16. Since the Applicant is also the Property Owner, Section IX of the Application should not
be signed. With your permission, I can cross out the signature on the original signed hard
copy that I have and you can edit the electronic file. If that is not satisfactory, please
provide a revised signature page.
17. Please correct the following issues with the Supplement-EZ Form:
a. Drainage Areas Page:
i. Lines 5-7 — Please use square feet instead of acres for these values.
ii. Lines 9 & 10 — These items do not correspond to the values shown in the
table in Section IV of the Application. Please revise.
iii. Line 12 — Please include this item. This is a breakdown of the common
area BUA (Line 10) by type. The items in Line 12 should add up to Line
10.
iv. Please fill out the LD 1 column. For this project, it will be the same as the
entire site column.
b. Low Density Page:
i. Line 4 — Please include the maximum side slopes of the vegetated
conveyances. This line does not format properly so the information should
be entered in Line 15 (additional information).
ii. Lines 6-10 — Please complete these items if applicable.
iii. Please include all vegetated conveyances and swales in the swale table.
18. 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

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, 2022, 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 SW4211101 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
Environmental Engineer
Stormwater Program
cc: Winston-Salem Regional Office