SW3221001_Response To Comments_20231219

PREPARED BY: Carlos Lee Ruano, P.E. Latham-Walters Engineering, Inc.
DATE: 12/19/2023 16507-A Northcross Drive
LWE RESPONSE Huntersville, NC 28078
LWE REPONSE TO NCDEQ COMMENTS-12/18/2023
I was reviewing the additional information you provided on September 29, 2023.
The following items were not addressed from Jim's previous comments (below):
- An original O&M Agreement Form is required. A copy of the document was received. Please
mail the original, notarized O&M Agreement form.
- LWE: Original form provided.
- As stated in the previous comment,vegetated conveyances can have steeper slopes than 3:1
provided that it is demonstrated that the soil and vegetation will remain stable in perpetuity
based on engineering calculations and an on-site soil investigation (emphasis added). If you
would like to utilize slopes that are steeper than 3:1 for the vegetated conveyances,you will
need to provide an on-site soil investigation showing that these slopes will remain stable in
perpetuity(it is difficult to establish vegetation on slopes steeper than 3:1 and these slopes are
too steep to be cut by ride-on lawnmowers which makes maintenance more
difficult/expensive).
- LWE: Revised with 3:1 slopes
- The provided details of the vegetated conveyances are insufficient (Section V1,81). Please clearly
show the bottom width of the vegetated conveyances on the detail (the calculations show that
the vegetated conveyances have a bottom width of 2 ft) and please specify the grass type to be
used in the vegetated conveyances (This is required to determine the maximum allowable
velocity within the vegetated conveyance per the table in Part C-11 of the Design Manual).
- LWE: Detail revised to show 2' bottom width.Grass type specified.
- Bermuda Grass: 5.0 ft/sec
Brianna Holland
Environmental Engineer
North Carolina Department of Environmental Quality
Office: [phone]
[e-mail]
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
- For FedEx/UPS:
Jim Farkas
512 N. Salisbury Street, Office 640M
Raleigh, NC 27604