SWA000217_Response To Comments_20231130

I I underfoot 1149 Executive Circle-Suite C-1 Cary, NC 27511
919.576.9733 I NCBELS C-3847
ENGINEERING
November 29, 2023
Via Email
Jim Farkas I State Stormwater Engineer
N.C. Department of Environmental Quality
512 H. Salisbury Street I Office 640M I Raleigh, NC 27604
Re: Lauder Parcel
Plan Review #2 Response Letter
To Whom It May Concern,
Please find comment responses to the review dated August 15, 2023 for the above reference
project. Staff comments from the staff reviews have been transcribed for ease of review.
Comments
Stormwater Jim Farkas I [e-mail]
1. Please correct the following issues with the Application:
a. Part E5-The Total Project Area (2,179,938 sf) is larger than the Total Property Area
(2,148,474 sf). Please either clarify (specifying the amount of the Total Project Area
that is "on-site" vs. "off-site") or revise so that the Total Project Area is equal to the
Total Property Area minus the Total Surface Water Area. Please revise as needed.
We just want to ensure that on-site surface waters are not included in the project
area.
Total Project and Total Property Area have been reviewed and revised to ensure
that the values indicated on the application are updated and accurate.The Total
Project Area now reflects update disturbed area and is less than Total Project Area.
b. Part E7-This project is located within 5 miles of Harnett Regional Jetport. NOTE: It
is noted that per the June 26, 2023 email from Kaitlin Peck, it was indicated that this
project is not within 5 miles of an airport, however this project is located within five
statute miles from the farthest edge of Harnett Regional Jetport's air operations
area. Please revise this item and consider utilizing SCMs that do not promote
standing water in accordance with G.S. 143-214.7(c3). Sorry for the confusion on
this item.
Application has been revised to now reflect in part E7 the project is within 5 miles
of Harnett Regional Jetport.
2. Please upload the electronic copies of the hard copy files previously provided as
indicated in the 7/17/23 email. Electronic copies of the submittal documents are
required in accordance with 15A NCAC 02H .1043(3). Please upload the documents at
the following address: https://edocs.dea.nc.gov/Forms/SW-Supplemental-Upload
Comment noted. Electronic copies of hard copy files previously submitted have now
been submitted through web address mentioned above.
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I I underfoot 1149 Executive Circle-Suite C-1
Cary, NC 27511
ENGINEERING 919.576.9733 I NCBELS C-3847
3. The Fast-Track ATC review is not an in-depth technical review of the stormwater controls
for the site, it is more of an administrative review of the project/a review to see if the
project has the potential to meet the design requirements/rules. The SCM design and
drainage area delineation are not required submission items at this point in the Fast-Track
submittal process so issues with the SCM design or drainage area delineation do not
prevent a project from getting Fast-Track ATC approval, but if the SCM design and
drainage area delineation are provided at this point in the review, we look at them to
see if the design appears to meet the rules and MDC. While not required for ATC
approval and based on a precursory look at the design, the following issues may arise
with the design:
a. The project does not appear to meet the requirement of Runoff Treatment (15A
NCAC 02H .1002(43)). In order for a project to meet Runoff Treatment, the net
increase in BUA must be captured and treated in one or more primary SCMs. Per
the provided calculations, the SCMs are only capturing and treating 588,866 sf of
BUA whereas the application indicates a total of 650,229 sf of BUA will be added
as part of this project. If it is not practicable to capture and treat all of the
required BUA, the bypassed areas can be permitted as a low-density area
(provided that the bypass area meets the low-density requirements).
Occasionally, there are situations where it is not practicable to capture all of the
required BUA in an SCM and it is not possible to permit the bypass areas as a low-
density area, however these situations require a variance/waiver which is not
allowed for projects permitted through the Fast-Track program (per 15A NCAC
02H .1043(1)(a)).
Runoff treatment of the Road widening has now been included in the stormwater
treatment for SCM 2, to ensure that maximum capacity of BUA is being captured
and treated accordingly. Drainage areas have been revised to ensure that BUA
and impervious area to be treated are equivalent.
b. Wet Pond #2 appears to be located in an area that is currently occupied by a
surface water. Please reach out to 401/Buffer Permitting Branch
(https://www.deq.nc.gov/a bout/divisions/water-resources/permitting/401-buffer-
permitting-branch)to see if any further permitting/design considerations must be
met in order to do this/impact the existing surface water.
AJD/ PJD Determination letter has been provided under a separate cover.
c. Wet Pond MDCs 1, 2, & 5a- Please note that these MDC refer to the main pool
which is separate from the forebay. Please ensure that only the main pool (and
not the entire permanent pool, including the forebay) is used for these
calculations. It is recommended to include stage-storage tables for the main pool
(below the permanent pool surface elevation), forebay (below the permanent
pool surface elevation), and temporary storage zone (above the permanent
pool) so that the sizing requirements can be verified.
Stage-storage tables for the main pool and the forebay are now provided in the
stormwater impact analysis report.
d. Wet Pond MDC 7- Please note that the temporary pool elevation is determined
by the invert of the lowest bypass weir/orifice (control orifice per the plans).
Forward Thinking. Grounded Design.
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I I underfoot 1149 Executive Circle-Suite C-1
Cary, NC 27511
ENGINEERING 919.576.9733 I NCBELS C-3847
Temporary pool elevation (NWL) and elevation of the lowest orifice have been
reviewed and revised to ensure that both values are equivalent.
e. NOTE: The project will need to comply with the rules/regulations before the Final
Approval (part 2 of the Fast-Track permitting process) is issued for the site and
before the E&SC permit is closed out.
Comment noted.
I am hopeful that your comments have been adequately addressed and approval of this project
is forthcoming. If you have questions or concerns, please contact our office at 919.576.9733.
Respectfully:
Mike Roselli, PE, PLA- Principal
Underfoot Engineering, Inc.
Forward Thinking. Grounded Design.
www.underfootengineering.com 3