SW3240201_Response To Comments_20240603

jij THOMAS & HUTTON
1020 EUCLID AVENUE
CHARLOTTE, NC 28203 I 980.201.5505
WWW.THOMASAN DHUTTON.COM
May 30, 2024
Attn: Jim Farkas
NCDEQ- Post-Construction Stormwater
512 N. Salisbury Street, Office 640M
Raleigh, NC 27604
Re: Cresswind Wesley Chapel- Phase 5
Post-Construction Stormwater Review
Monroe, NC
J-27842.0005
To whom it may concern:
This letter serves as acknowledgement that we have revised the previously submitted package to
address all comments below as follows:
1. Please correct the following issues with the design of the SCM and calculations:
a. When calculating the volume provided in the main pool and forebay,please ensure
that the sediment storage zone is excluded from these volumes. For example,per the
plans, the top of the sediment storage zone for the main pool is shown to be at
elevation 578.5', any portion of the main pool provided below this elevation does not
count towards the volume of the main pool. Please revise as needed as this will
impact the main pool volume, the forebay volume, the percent sizing of the forebay
with relation to the main pool, average depth calculations, etc...
RESPONSE: The wet pond design has been revised so that the bottom elevation of
the main pool is now set at 577.50,which then lowers the sediment storage
elevation of the main pool to 578.00.
b. As designed, the wet pond has an insufficient design volume (per General MDC 1).
The design volume of a wet pond is the volume stored between the permanent pool
surface elevation (582.5') and the invert of the lowest bypass device (weir at
elevation 583.5'). Per the provided stage-storage table, the design volume of the SCM
is approximately 58,000 cf whereas the calculations indicate that the minimum
required treatment volume is approximately 65,000 cf(see later comment with regard to the
minimum required treatment volume). Please revise as needed.
RESPONSE: The elevation of the first weir has been raised from elevation 583.50
to elevation 584.00 to provide additional treatment volume. The wet pond is now
providing approximately 88,000 CF of design volume,which is sufficient to handle
the required design volume of approximately 65,000 CF.
c. Please clarify the amount of BUA that is draining to the proposed SCM. Per the
Application and Supplement-EZ Form, this amount is shown as 804,654 sf(18.47 ac)
and is shown in the calculations as 18.18 ac. Please revise as needed. NOTE: This
discrepancy may require the minimum required treatment volume to be recalculated.

RESPONSE: The correct BUA is 18.18 acres. The EZ-form and the application
have been revised to show the correct area.
d. Please provide calculations indicating that the inlets and outlets are stable in
accordance with General MDC 4. Please also ensure that the sizing of riprap
dissipators is indicated on the plans.
RESPONSE: Rip rap aprons have been designed to prevent erosion at all inlets and
outlets. Calculations showing the design for these rip rap aprons are provided at
the end of Appendix E in the revised stormwater report. The size of the rip rap
aprons has also been called out on the paving, grading, and drainage sheets within
the plan set(see sheet C3.2).
e. This project appears to be located within 5 miles of Monroe-Charlotte Executive
Airport. It is recommended to use SCMs that do not promote standing water in
accordance with G.S. 143-214.7(c3)_
https://www.ncleg.gov/EnactedLegislation/Statutes/PDF/BySection/Chapter 143/GS
_143-214.7.pdf. Alternative SCMs that are recommended to be used within the 5 mile
radius of a public airport are outlined in Part E-4 of the Manual
https://deq.nc.gov/media/9977/download. Please revise if needed.
RESPONSE: Noted. Other SCM options were evaluated at the onset of this project,
and a wet pond is our preferred option.
2. Please correct the following issues with the plans:
a. Please include the drainage area delineation to the SCM in the main set of plans.This
item is required per 15A NCAC 02H .1042(2)(g)(iv). NOTE: Impacts to adjacent
permit areas will necessitate modifications to those impacted permits.
RESPONSE: A BMP drainage area plan for Wet Pond 06 has been added to the
main set of plans. See Sheet C3.27—Wet Pond Drainage Area Plan.
b. Plan sheet C3.26 appears to indicate that the vegetated shelf around the wet pond
extends from elevation 582.5 ft(this contour is unlabeled but is between the 582 ft&
583 ft contours) and 584.0 ft(the other submittal items indicate that the shelf extends
from elevation 582 ft to 583 ft). Please revise as needed.
RESPONSE: The planting hatch for the littoral shelf has been revised to show the
correct elevations between elevations 582 and 583.
c. Plan sheet C3.26 lists two different types of plants for the vegetated shelfplanting
("Scarlett Rose Mallow" is duplicated)whereas Wet Pond MDC 1lb requires a
minimum of three different, diverse species. Please revise as needed.
RESPONSE: The plant schedule has been updated to specify three different plant
species.
3. Please correct the following issues with the Application:
a. Section IV, 10, On-site Parking/Sidewalk—These items refer to either parking areas
or sidewalk areas that will be located within the common areas of the project, i.e., not

located on the subdivided lots (please refer to the deed restriction language for
specific information about what is covered under the "per lot"BUA allocation).BUA
that is allocated to the individual lots should be included in the "On-site
Buildings/Lots" line and BUA that is allocated to the common areas should be
included on the other lines. Please revise as needed.
RESPONSE: The built-upon areas listed in this section have been revised as
described above.
4. Please correct the following issues with the Supplement-EZ Form:
a. Cover Page:
i. Line 2—Please use the project area, not the total property area for this item(this
item should correspond to Section IV, 7 of the Application).
RESPONSE: The project area on the EZ form has been updated to 37 acres,
which matches the project area listed on Section IV, 7 of the application
b. Drainage Areas Page:
i. Please ensure that the latest version of this form is used(available at the following
link: https://www.deq.nc.gov/about/divisions/energy-mineral-and-land-
resources/stormwater/stormwater-program/stormwater-design-manual) and that the
form has been properly loaded(The form uses macro to generate the needed
sections based on the information entered, please enable macros and click on the
"click to load form" link after the top part of the form has been filled out).
RESPONSE: The latest form is being used.
ii. Please fill out the entire site column (see prior comment). The entire site column is
an accounting of the entire project area(similar to how the drainage area column is
an accounting of the entire drainage area). BUA that is located within the project
area should be included within the entire site column, whether or not it drains to
the SCM. NOTE: In order for the project to meet Runoff Treatment, the net
increase in BUA needs to be captured and treated within the SCM. If it is not
practicable to capture and treat the net increase in BUA, the uncaptured project
area can be permitted as a low-density area(provided that all of the low-density
criteria is met in this portion of the project area). If it is not practicable to permit
this area as a low-density area, we can discuss further permitting options.
RESPONSE: The "Entire Site" column has been filled out per comment. Wet
Pond column has been added.
iii. Line 5 — See earlier comment with regard to consistency, revise if needed.
RESPONSE: The BUA area has been revised here. It is consistent with other
documents.
iv. Lines 6, 7, & 10— See earlier comment with regard to BUA allocated to individual
lots (only BUA that will be located within the common areas should be included
on Lines 7 & 10). NOTE: The total amount of BUA allocated to the individual lots
per the deed restriction form should be equal to Line 6 of the Entire Site Column.
RESPONSE: This area has been updated. We are assuming a max BUA of 5000
SF per lot, and there are 104 lots proposed. This amounts to a total of 520,000 SF for BUA

on subdivided lots.
v. Line 16—Please revise this calculation as needed (this value should correspond to
Section IV, 8 of the application for the Entire Site Column and to the value as
shown in Section IV, 10 for the Drainage Area 1 Column.
RESPONSE: The percent BUA has been revised.
vi. Line 17— See 15A NCAC 02H .1017(5).
RESPONSE: The design storm has been revised from 6" to 1".
vii. Line 18— See earlier comment with regard to the design volume of the SCM.
RESPONSE: The design volume has been updated to show the volume that
corresponds to the invert elevation of the lowest bypass device,which has been raised to
elevation 584. This design volume is now roughly 88,000 CF.
c. Wet Pond Page:
i. Line 2—NOTE: In the current version of this form, this line asks for the minimum
required treatment volume for the SCM. Please revise as needed.
RESPONSE: The required treatment volume has been entered here.
ii. Line 3 —Please provide an answer for this item(required per General MDC 1).
RESPONSE: An answer has been provided. Yes,the SCM has been sized to
treat the SW from all surfaces at build-out.
iii. Line 25 — See earlier comment with regard to the design volume of the SCM.This
value should correspond to the invert elevation of the lowest bypass device
(revised as needed).
RESPONSE: This line has been revised to correspond with the invert elevation
of the lowest bypass device.
iv. Lines 27 & 32— See earlier comment with regard to excluding the sediment
storage zone from volume calculations.
RESPONSE: Noted. The designed elevation of the excavated pond has been
lowered to 577.50, so the top of the sediment removal now starts at 578.00.
v. Line 28—Please recalculate as needed. NOTE: The calculated average depth(3.33
ft) does not match the value shown here (4.5 ft).
RESPONSE: The average depth listed on the EZ form here has revised to 3.33.
vi. Line 34—The cleanout depth of the forebay is measured from the permanent pool
surface to the top of the sediment storage zone (the top of the sediment storage
zone is typically flat and at least 6 inches of sediment storage needs to be provided
over the
RESPONSE: The cleanout depth listed on the EZ form here has been revised to

54".
vii. Line 35 — See earlier comment with regard to the drainage area BUA discrepancy.
Revise as needed.
RESPONSE: The design volume has been updated to show the volume that
corresponds to the invert elevation of the lowest bypass device,which has been
raised to elevation 584. This design volume is now roughly 88,000 CF.
viii. Line 40— See earlier comment with regard to the design volume. Revise as
needed.
RESPONSE: The drawdown time for the required water quality volume is
59.47 hours per our calculations,which equates to approximately 2.48 days.
5. Please revise the Wet Detention Pond Design Summary information on the O&M
Agreement Form in accordance with earlier comments.
RESPONSE: Revised per comment.
6. As indicated in the February 6, 2024 email,please upload the electronic files for this
project to the following link:https://edocs.deq.nc.gov/Forms/SW-Supplemental-Upload
Electronic files are required per 15A NCAC 02H .1042(2).
RESPONSE: Electronic files have been provided with this submittal.
7. Please provide a Response to Comments letter indicating, in a point-by-point manner,
how each of the above comments has been addressed. This item is required per 15A
NCAC 02H .1042(3)(b).
RESPONSE: A comment response letter has been provided with this submittal.
8. 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.
RESPONSE: PDFs, hardcopies of plans and supporting documentation, as well as
a response to comments letter have been provided with this submittal.
We look forward to receiving the approved certification for the referenced project to allow us to
proceed. If you have any questions, comments, or desire additional information, please contact
our office at [phone].
Sincerely,
Matthew S. Kiker, PE
Thomas & Hutton
1020 Euclid Avenue
Charlotte, NC 28203
[e-mail]