SW4210601_Response To Comments_20240405

KENNERLY
ENGINEERING&DESIGN,INC.
April 5, 2024
Jim Farkas
Environmental Engineer
Dept. of Environmental Quality
Division of Energy, Mineral &
Land Resources Stormwater Program
512 N. Salisbury Street
1612 Mail Service Center
Raleigh, NC 27699-1612
RE: Comments and Responses - Stormwater Permit Received Dec. 12t'', 2023
Stormwater Permit No. SW 4210601 Request for Additional Information
Wynnfall Subdivision — Phase One, Davidson County
Mr. Farkas,
Attached are Kennerly Engineering & Design, Inc. (KED) responses to emailed comments from
your review on December 12th, 2023.
The comments and responses are in the order of the letter received.
Should you have any questions, please do not hesitate to contact us at 336.775.2118.
Sincerely,
Timothy S. Ken erly, PE
Vice President/ Senior Engineer
Phone:[phone]
12133 N.HWY 150,Ste.F Winston-Salem,NC 27127 Fax:[phone]
www.kennerlyengineering.com

2 I P a g e WYNNFALL SUBDIVISION PHASE ONE STORMWATER PERMIT MOD
PERMIT#SW4210601 -REQUEST FOR ADDITIONAL INFORMATION
ADDRESS: HINKLE LANE, LEXINGTON, NC/DAVIDSON COUNTY
Review Comments
1. " Per the attached satellite imagery dated May 24, 2023, BUA(Painted Train, Cricket's Run,
and several of the lots) appears to have been constructed. Please note that 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, including the assessment of civil penalties of up to$25,000 per day per
offending property owner. This issue is being referred to inspectors in the Winston-Salem Regional
Office for enforcement action. Please cease any further construction of impervious surfaces on-site
until the site has received post-construction stormwater approval from our office."
#1:Response: The approved sedimentation erosion control permit was closed by the
Winston-Salem NCDEMLR Office in May of 2023. The erosion control permit
covered the grading and erosion control for the road, roadside ditches, and
culverts. The lots are permitted under individual permits with the NCDEMLR
for Lot Grading and not a part of the original erosion control permit.
2. "Per the Davidson County Register of Deeds, Lots 1, 2, 4, 5, 6, 7, 8, 9, 10, 16, 17, 22, 23, 29,
30, 31, 35, 36, 37, 38,40,41, 42, 43, &44 are no longer owned by Buel B. Barker,Jr.. In
accordance with 15A NCAC 02H .1042(2)(a)(ix)the property owner(s) name, address, and
contact information must be provided in Section 111,2 of the Application Form. In accordance with
15A NCAC 02H .1042(2)(c), please provide documentation (in the form of signed Section IX of the
Application) indicating that the applicant has obtained legal rights to submit a stormwater permit
application within the proposed project area. For your convenience, a page containing both Section
111,2 &Section IX of the Application has been provided as an attachment and should be completed
by each property owner that has not already completed these sections of the application. Since
there is no HOA planned for this subdivision, any further property sales in the covered project area
will require a permit transfer per 15A NCAC 02H .1045."
#2:Response: The Developer will be responsible for maintaining the road and roadside
ditches until the project is accepted into the NCDOT system for Maintenance.
According to the Davidson County Manager once the plat was approved and
accepted by the County the Right-of-Way no longer is the property of the
developer,it becomes property of the county.
3. "Original Comment 6—The Vactual for swale 22 (5.74 fps) exceeds the Vallowable for swale 22 (5.5
fps). Per 15A NCAC 02H .1003(2)(c)(ii), conveyances shall be designed so that they do not erode
during the 10-year 24-hour storm. We are unable to permit a swale with a Vactual in excess of
Vallowable as this demonstrates that this swale will be erosive during the 10-year 24-hour storm.
Please revise as needed."
#3:Response: Have revised calculation. This ditch is an existing drainage draw that is in a
natural state with no grading. The Manning's 'n'value has been calculated
using the NCDEMLR Estimating Roughness Coefficients spreadsheet. The
revised calculation average velocity is 3.30 ft/s which is below the Vallowable
of 5.5 fps.
K E N N E R LY 12133 N.NC FIIAlY 150,Ste.F Phone:[phone]
Fax:[phone]
ENGINEERING a DESIGN.INC. Winston-Salem,NC 27127 www.kennerlyengineering.com

3 I P a g e WYNNFALL SUBDIVISION PHASE ONE STORMWATER PERMIT MOD
PERMIT#SW4210601 -REQUEST FOR ADDITIONAL INFORMATION
ADDRESS: HINKLE LANE, LEXINGTON, NC/DAVIDSON COUNTY
4. "Prior Comment 3—There are some issues with the rainfall intensity/flow calculations. For example,
for swale 15 (based on the information entered into the Supplement-EZ Form), a "C" of 0.54, "i" of
6.87 in/hr, and an "A" of 1.89 ac would give a "Q" of 7.01 cfs whereas 6.43 cfs is provided.This issue
is also present in the other swales (such as swales 2, 7, 9, 10, 12, 14, 15, 17, & 20). Please recheck
the calculations for all of the swales and ensure that this issue is addressed."
#4:Response: Have revised all ditch calculation
5. "Prior Comment 5— Please specify on plan sheet C-702 which trapezoidal ditch cross section
corresponds to which swale,there is no indication of which swale (21 or 22) corresponds to the
swale with the 4 ft bottom width or the 8 ft bottom width). Please revise as needed."
#5:Response: Have labeled the trapezoidal ditch cross section for the swale it corresponds
with.
6. "There appear to be inconsistencies between the swale design information as shown in the
Supplement-EZ Form/calculations and as shown on plan sheet C-702. Please revise as needed:
a. The weighted rational coefficient("C")for swales 7, 9, 10, 12, 14, 15, 17, 20, & 21 differ
between the two.
b. The flowrate ("Q")for swales 21 & 22 differs between the two.
c. The longitudinal slope ("S")for swale 22 differs between the two.
d. The flow depth for swales 1-21 differs between the two."
#6:Response: Have revised swale information so that it is consistent between Plansheet C-702& the
Supplement EZ Form.
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
KENNERLY 12133 N.NC HWY 150,Ste.F Phone:[phone]Fax:[phone]
ENGINEERING s DESIGN.INC. Winston-Salem,NC 27127 www.kennerlyengineering.com

4 I P a g e WYNNFALL SUBDIVISION PHASE ONE STORMWATER PERMIT MOD
PERMIT#SW4210601 -REQUEST FOR ADDITIONAL INFORMATION
ADDRESS: HINKLE LANE, LEXINGTON, NC/DAVIDSON COUNTY
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."
#7:Response: Have uploaded and submitted the revised documents.
KE N N E RLY 12133 N.NC HWY 150,Ste.F Phone: [phone]
Fax:[phone]
ENGINEERING a DESIGN.INC. Winston-Salem,NC 27127 www.kennerlyengineering.com