SW3221001_Response To Comments_20230929

PREPARED BY: Carlos Lee Ruano, P.E. Latham-Walters Engineering, Inc.
DATE: 9/26/2023 16507-A Northcross Drive
LWE RESPONSE Huntersville, NC 28078
LWE REPONSE TO NCDEQ COMMENTS-9/25/2023
I was looking over the additional information you provided on June 23, 2023. Everything looks good
except for a few small issues:
Please correct the following:
- Original Comment 2 (Prior Comment 1)—Please correct the following issues with regard to the
Low-density portion of the project:
o Please revise the O&M Agreement Form to include the low-density portion of the
project (the form will need to be re-signed and notarized). While not required, you may
wish to get a second original card copy signed and notarized for the Applicant (this will
be needed when recording the O&M Agreement form with the Register of Deeds).
o Ok, O&M Agreement revised to include low-density portion.
o Per 15A NCAC 02H .1003(2)(c)(i), side slopes of vegetated conveyances shall be 3:1 or
flatter(side slopes of 2:1 are shown in the calculations). Please revise as needed.
Steeper side slopes can be allowed, provided that it is demonstrated that the soils and
vegetation will remain stable in perpetuity based on engineering calculations and an on-
site soil investigation.
o Calculations were updated &stabilization were included.
o Please provide the detail/typical section for the vegetated conveyances. If this was
provided in a prior submittal, please direct the reviewer's attention to this.
o Typical section is provided on sheet C8.1. Details on erosion control provided on C4.13
o Please revise the percent BUA calculation for the low-density drainage areas. %BUA is
calculated as either [Total BUA] / [Total Drainage Area] or [Net Increase in BUA]/([Total
Drainage Area]— [Existing BUA]). For example,for low-density drainage area 1,the
supplement-EZ Form indicates a total drainage area of 116,740 sf, existing BUA of
35,666 sf, and new BUA of 14,314 sf(%BUA= 14,314 sf/ (116,740 sf—35,666 sf) =
17.7%).
o Corrected
o Please clarify where the Manning's n value of 0.15 came from as it seems high (typically,
the n value of a vegetated conveyance is closer to 0.035. Please revise as needed.
o N-Value of 0.035 was used. Calcs were updated.
- Prior Comment 6.a.i.—The sum of the items for Line 23 (19,697 cf) and Line 30 (16,115 cf) is
equal to 35,812 cf whereas the stage-storage table indicates a cumulative storage volume of
35,754 cf. Please revise as needed.
- EZ form remain the same. Sand filter spreadsheet calculation was revised.
Please provide the following:
- 1x original hard copy& 1x electronic copy of the revised O&M Agreement Form
- 1x hard copy& 1x electronic copy of the revised calculations (as needed)
- 1x hard copy& 1x electronic copy of the revised Supplement-EZ Form (as needed)
- 2x hard copies& 1x electronic copy of the revised plan sheets (as needed)
- 1x hard copy& 1x electronic copy of any other items needed in order to address the above
comments

PREPARED BY: Carlos Lee Ruano, P.E. Latham-Walters Engineering, Inc.
DATE: 9/26/2023 16507-A Northcross Drive
LWE RESPONSE Huntersville, NC 28078
- For FedEx/UPS:
- Jim Farkas
- 512 N. Salisbury Street, Office 640M
- Raleigh, NC 27604
- Since these are really minor things, once I get the hard copies, anything else that may have
changed from addressing these issues, and the documents are uploaded to Laserfiche (Provided
everything is still in order),we can issue the permit without doing another formal review.The
quickness of the next review for this project is dependent on reviewer availability.