SW5231101_Response To Comments_20240329

STOCKS
ENGINEERING
Designing the Future...Today!
March 28th, 2024
Brianna Holland
Environmental Engineering
DEMLR Post-Construction Stormwater Program
RE: Jewett Avenue Subdivision— Phase 1
This letter is written in response to the red-lines and comments dated March 15t, 2024
regarding the revised plan for E.Jewett Avenue Subdivision—Phase 1 in Franklin County,
NC. A reply or explanation for each comment issued by your office is provided below and
follows the original format of your memorandum.
1. As designed, this project does not meet Runoff Treatment (defined in 15A NCAC
02H .1002(43) and required per 15A NCAC 02H .1003(3)(a)). NOTE: 15A NCAC
02H .1003(3)(a) does also allow for a project to meet treatment requirements via
Runoff Volume Matching, however stormwater wetlands are not well suited for
meeting Runoff Volume Matching. Please note that the ability to consider a
project as having areas of both high and low-density is at the discretion of the
Division (per 15A NCAC 02H .1003(1)(d)). There does not appear to be sufficient
justification for permitting this site as proposed. The BUA that is currently
located in the "low-density area" of the project should be able to be captured
and treated in the SCM. Ditches and/or catch basins could be installed to direct
the currently untreated and bypassed BUA to the SCM. Note that the driveway
apron is considered part of this project, but is not clearly shown within the
project area or and the increase in BUA does not appear to be directed to the
SCM. Please revise as needed.
In order to include the townhome roof area that was previously bypassing the
SCM, additional storm drain is now designed and roof drains are shown in the
rear of units 1-10. The driveway apron has also been included as offsite
impervious area draining to the SCM. All calculations and forms have been
updated to reflect this change.

2. Please revise the following items on the Application:
a. Section IV, 1—There appears to be a typo, the sum of the impervious
areas listed in the table provided in Section IV, 10, is 33,633 SF but the
description indicates 36,633 SF. Please revise as needed for consistency.
Section IV. 1. Revised to 36,532 SF to match the new calculated impervious
area.
b. Section IV, 9—The table provided in Section IV, 10 lists 2 drainage areas.
The Supplement-EZ indicates that there are 2 drainage areas. Please
revise as needed for consistency depending on the drainage areas
provided in the revised package.
Only 1 drainage area is now listed since the project is no longer claiming
low density treatment area.
c. Section IV, 10— Per the deed restrictions, the maximum BUA per lot is
1,473 SF. There are 15 lots in the project area, 15 lots*1,473 SF/lot=
22,095 SF of BUA. The sum of the on-site buildings/lots in the drainage
areas is 22,096 SF. Please revise as needed for consistency.
The on-site building/lots has been updated to correctly show 22,095 SF in
the drainage areas chart.
3. Please revise the following items on the Supplement-EZ:
a. Cover Page, Line 2—The project area listed should match the project area
listed in the Application Section IV, 7.
The Project Area has been revised to match the project area in the
application IV,7.
b. Cover Page, Line 5 (if a mixed density permit is pursued)— Per the
Drainage Areas Page, there is a low density drainage area of the project.
Please revise to "Both High and Low Density." Once this is selected and
"Load Supplement Forms" is selected, the low density supplement page
will be generated, and will need to be submitted for review.
Mixed density project no longer utilized.
c. Stormwater Wetland Page, Line 18—The design volume for a wetland is
the volume that can be retained for a two to five-day period between the
temporary pool elevation (set by the elevation of the lowest bypass) and
the permanent pool elevation (set by the drawdown orifice) per C-4 of

the Manual. Please revise accordingly, as the minimum treatment volume
was provided. This value should be able to be confirmed within the
calculations.
Line 18 revised to match Hydraflow calculations showing design volume of
the volume between the permanent pool 252.0 and the temporary pool
253.25.
d. Stormwater Wetland Page, Line 24—Please indicate the peak attenuation
ponding elevation on the cross-sectional view of the SCM in the main set
of plans, as this value cannot be currently confirmed. This item is
required per 15A NCAC 02H .1042(2)(h)(i). If this item changes on the
Supplement-EZ, please revise Line 40.
Peak attenuation level now shown on the cross section of sheet CE-06
4. Please revise the following items on the plans:
a. A project phase boundary is provided, but please provide dimensioned
project or project phase boundary with bearings and distances, so that
the project area can be confirmed. (15A NCAC 02H.1042(2)(g)(ii))
The project area is now labeled with bearings and distances on sheet D-07.
b. Identify and delineate the surface area of the on-site surface water in the
main set of plans (Section VI, 8h). The surface area of a stream/river is
the area between the banks of the stream/river. The surface area of the
on-site surface water should be able to be determined from the plan
sheet (either as a callout or as a measurable area).
Surface area of on-site surface water in Phase 1 is now called out on the
plan on sheet CE-03.
c. It is noted that Zone 1 and Zone 3 buffers are shown on the plans, but
please label the required vegetated setbacks. Show the required
vegetated setbacks from the on-site surface waters in the main set of
plans (Section VI, 8p). Information on the required vegetated setbacks
can be found in 15A NCAC 02H .1017(10) and 15A NCAC 02H .1003(4).
(Notably, ensure that the width of a vegetated setback shall be measured
horizontally from the normal pool elevation of impounded structures,
from the top of bank of each side of streams or rivers, not from the
centerline.)
Vegetated buffer now labeled from top of bank on Sheet CE-03.

d. Clearly show and label the recorded easement on the main set of plans
(Section VI, 8n). Per General MDC 8 and 9: All SCMs and associated
maintenance accesses shall be located in permanent recorded
easements. The SCM shall be shown and labeled within the easement.
Maintenance accesses shall:
(a) have a minimum width of ten feet;
(b) not include lateral or incline slopes that exceed 3:1 (horizontal
to vertical); and
(c) extend to the nearest public right-of-way.
See 15A NCAC 02H .1050 (8) and (9) for additional information on
maintenance accesses and easements.
A permanent stormwater and maintenance easement is now shown on CE-03
& CE-05.
e. Label the bottom elevations on the Stormwater Wetland Profile and
provide SCM contour labels on the plan view detail per 15A NCAC 02H
.1042 (2) (h).
Wetland profile and plan view now have labeled bottom elevations.
f. Per the Supplement-EZ, the bottom of the shallow water zone is 251.25,
please show this on the plans so that it can be confirmed.
Shallow water bottom elevation now labeled on contours and on wetland
profile.
g. Per the Supplement-EZ, the deepest point of the bottom of the forebay
deep pool is 249.00 and the shallowest point is 250, please show this on
the plans so that it can be confirmed.
Forebay and deep pool bottom elevations now shown on the wetland profile
and the contour labels in the plan view.
5. The provided O&M Form is outdated and therefore incomplete. Please use the
most up to date form, which can be found on our website at the following
address: https://www.deq.nc.gov/about/divisions/energy-mineral-and-
landresources/stormwater/stormwater-program/stormwater-design-manual
(O&M EZ Form). NOTE: It is recommended to get a second copy of this form
signed & notarized for the Applicant's records (it will be helpful when they go to
record it with the Register of Deeds).
O&M has been updated. An original will be provided.

6. Per General MDC 4, the inlets of SCMs shall be designed to protect the SCM from
erosion resulting from stormwater discharges. The outlets of SCMs shall be
designed so that they do not cause erosion downslope of the discharge point
during the peak flow from the 10-year storm event as shown by engineering
calculations. Provide calculations demonstrating this requirement is met. If
inlet/outlet protection is needed, provide dimensions on the calculations that
matches the calculations.
Rip Rap sizing calculations are now provided for stormwater discharges into and
out of the SCM. Sizes are now labeled on sheet CE-06.
7. Per 15A NCAC 02H .1003 (5), stormwater outlets shall be designed so that they
do not cause erosion downslope of the discharge point during the peak flow
from the 10-year storm event as shown by engineering calculations. This
includes outlets from the site that are not treated by an SCM.
Per previous comment response, calculations are now included to demonstrate
meeting this criteria. All areas that are not channeled by storm drainage are
designed to sheet flow through the vegetated buffer and into the stream.
8. Per Stormwater Wetlands MDC 10, ensure that the design volume (see previous
comment) will be drawn down within 2-5 days per engineering calculations
(Stormwater Wetland MDC 10). It appears that the drawdown time is currently
insufficient per the provided calculations.
Wetland calculation form has been updated to reflect impervious changes and
design volume. Now shows 2.3 day draw down.
9. Please specify that non-clumping turf grass shall be provided on the dam
structure and perimeter fill slopes per Stormwater Wetlands MDC 15.
Note added to CE-06 to seed side slopes with centipede grass.
10. If the project is located on multiple USGS topographic maps, both maps must be
provided. It appears that there is additional surface water onsite shown on the
adjacent map. Note that the latest version of the USGS topographic map can be
accessed at no cost at https://ngmdb.usgs.gov/topoview/viewer/ (15A NCAC
02H .1042 (2) (d)).
An updated USGS map with the area of Phase 1 has been provided. The start of
stream was determined onsite and is reflected on the plan.

a. If additional on-site surface water is present per the latest USGS
topographic map, vegetated setbacks from such waters shall be required
per 15A NCAC 02H .1017 (10).
b. If additional on-site surface water is present, the total project area should
be revised to exclude the areas below the normal high water line, per
15A NCAC 02H .1003 (1)(c)(i).
11. Since this project drains to the Tar River (a Nutrient Sensitive Watershed), please
ensure that the project is also compliant with the Tar-Pamlico Nutrient Strategy
Rules 15A NCAC 02B .0731.
Updated Tar-Pam Nutrient worksheet has been provided showing the project is in
compliance with the nutrient strategy.
12. 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.
PDF's have been uploaded and hard copies mailed by FedEx.
a. PDFs must be uploaded using the form at:
https://edocs.deq.nc.gov/Forms/SW-Supplemental-Upload
Please ensure the electronic repository is complete. The following items
were noticed to be missing:
• Official documentation supporting the titles and positions held by the
persons listed in Contact Information, item la per 15A NCAC
2H.1003(e). (Required per Section VI, 11)
• Official documentation displaying the corporation is active and in
good standing with the NC Secretary of State. (Required per Section
VI, 11)
• Signed and notarized Deed Restrictions & Protective Covenants Form
b. Hard copies must be mailed or delivered to the following address:
i. For FedEx/UPS:
Brianna Holland
512 N. Salisbury Street, Office 625Y
Raleigh, NC 27604
ii. For USPS:
Brianna Holland
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.
While not required, the following is recommended:
- It is recommended to have a drainage area of at least two acres to provide year-
round hydration for wetland plants to grow and thrive.
If there are any further questions or concerns, please contact Stocks Engineering at
252.459.8196. Thanks!
Sincerely,
Stocks Engineering, P.A.
Ethan Averette