SW6231202_Response To Comments_20240321

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MCCLURE''
1700 Swift Street,Suite 100
North Kansas City,MO 64116
P 816.756.0444
www.mcclurevision.com
March 20, 2024
0
2 Jim Farkas
512 N. Salisbury Street, Office 640E
0 Raleigh, NC 27604
Re: SW6231202 Dunn, NC Petco review comments— Request for Additional Information
Dear Mr. Farkas:
U)
The purpose of this letter is to respond to the Request for Additional Information as provided on March 5, 2024.
Our comment responses are as follows:
a The following information is needed to continue the stormwater review:
1. Please provide SCM sizing calculations as it is unclear where the design volume of 3,046 cf came from.
h Calculations are required per 15A NCAC 02H .1042(2)(f).
RESPONSE: The SCM area has been expanded slightly and the revised volume is provided on sheet
C300.
0
2. There appears to be a discrepancy between the top elevation of the IWS as shown on the plans (@
elevation 168.5') and as shown on the Supplement-EZ Form (@ elevation 168.0'). Please revise as
needed.
cr) RESPONSE: The Supplement EZ form has been revised to match the plan detail.
3. Please provide the dimensions of the riprap apron downstream of the SCM in the main set of plans.
This is required per 15A NCAC 02H .1003(5), .1042(2)(h)(ii), & .1050(4).
RESPONSE: Sheet C400 has been revised to show the riprap dimensions.
4. Please provide a stage-storage table for the SCM. Per the provided grading plan sheet, the SCM does
not appear to be sufficiently sized to hold a design volume of 3,046 cf (NOTE: The actual design
volume of the SCM may vary, see earlier comment with regard to this value) between elevations 170.5'
& 171.5'. Based on measurements I took from the plans, the cross-sectional area of the SCM at
elevation 170.5' appears to be approximately 2,300 sf (NOTE: The Supplement-EZ Form indicates that
the bottom surface area of the SCM is 3,303 sf, which is significantly different than the value measured
from the plans) and the cross-sectional area at elevation 171.5' appears to be approximately 3,300 sf
4 (for a storage volume of approximately 2,800 cf). NOTE: Due to the geometric shape of the SCM, you
could alternatively provide dimensions for the bottom of the SCM on the plans (so that the area can be
computed).
o RESPONSE: Sheet C300 has been revised to include a stage storage table.
111

5. General MDC 4 — Please provide calculations showing that the inlets to the SCM (curb cuts with riprap)
are stable in accordance with this MDC.
RESPONSE: Calculations are provided with this submittal.
6. Bioretention MDC 2 — Please provide a bypass device to limit the ponding depth of the design
volume/temporary pool to no more than 12 inches above the planting plan (please refer to "Deign
Volume" information on page 1 of Part C-2 of the Manual). Per the design, the planting surface
elevation is at 170.5' and the invert of the lowest bypass device is at elevation 172.0' (in excess of 12"
above the planting surface).
RESPONSE: The detail on sheet C105 has been revised per this comment.
7. Please correct the following issues with the Application Form:
a. Section IV, 10— Please revise the Total Drainage Area and On-site Drainage Area values to
correspond to the area that drains to the SCM (63,957 sf).
b. Section IX—Since the Applicant is also the property owner, this section is not needed. With
your permission, we can cross-out the provided signature in Section IX on the hard copy that
we have however, you will need to modify the electronic copy of the file. If that is not
acceptable, please provide a corrected signature page of the Application Form.
RESPONSE: The Application form has been revised per these comments.
8. Please correct the following issues with the Supplement-EZ Form:
Drainage Areas Page:
Entire Site Column:
a. Lines 5 &6— Please revise these values to correspond to the total project area, 73,050 sf.
b. Drainage Area 1 Column:
c. Lines 5 &6— Please revise these values to correspond to the total drainage area to the
proposed SCM, 63,957 sf.
d. Please provide this value. This value is calculated as (Line 8/ Line 5).
RESPONSE: The Supplemental EZ form has been revised per these comments.
Bioretention Cell Page:
a. Line 2 — Please fill in this item.
b. Lines 21 &22 —See earlier comment with regard to a stage-storage table/SCM size. Please
revise as needed. NOTE: The design volume of the bioretention cell is the volume that can be
stored between the planting surface and invert of the lowest bypass device (max 12") whereas
the minimum required treatment volume is the volume determined based on the design storm
(1.0") and drainage area to the SCM (calculated using either the Simple Method or the
Discrete NRSC Curve Number Method). The design volume must be at least as large as the
minimum required treatment volume.
c. Line 29—See earlier comment with regard to the IWS discrepancy.
RESPONSE:The Supplemental EZ form has been revised per these comments.
9. Please correct the following issues with the O&M Agreement Form:
a. Please either remove the treatment swale (as it is not needed to meet treatment requirements)
or add a note to the cover page of the O&M Agreement stating that the treatment swale
operation and maintenance information ####################
RESPONSE:The O&M Agreement Form has been revised per this comment.

10. Please upload the electronic files associated with 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).
11. NOTE: Since this project has already been constructed, please ensure that the design, as shown in the
submission, reflects the as-built site conditions. Since the plans ultimately get approved and are
enforceable, any deviations in the real world from the approved plans either need to accounted for by
modifying the approved plans or corrected in the real world to reflect the approved plans (submitting
plans for approval for a site that is already built that do not reflect the actual site conditions results in
the site being out of compliance if approved and non-compliant sites can be subject to enforcement
action
RESPONSE: The bio pond has been surveyed and corrections are being made to ensure it is built per
plans. Once corrections are done a new survey will be performed and provided.
Thank you for the initial comments and please advise if any additional information is needed to complete the
review.
Sincerely,
Brian Kemp
Team Leader