SW3221001_Response To Comments_20240411

PREPARED BY: Carlos Lee Ruano, P.E. Latham-Walters Engineering, Inc.
DATE:4/10/2024 16507-A Northcross Drive
LWE RESPONSE Huntersville, NC 28078
LWE REPONSE TO NCDEQ COMMENTS-3/20/2024
I was looking over the additional information you provided on December 21, 2023. Everything looks
good except for a few small issues:
Please correct the following:
- Original Comment 2—Please correct the following issues with the vegetated conveyances:
o Please revise the calculations to reflect the vegetated conveyance design as shown in
the plans.The plans indicate that both side slopes of the vegetated conveyances are 3:1
however,the calculations indicate that one side slope is 3:1 and the other side slope is
2:1.
• Calcs were revised to 3:1 slopes.
o NOTE: Side slopes steeper than 3:1 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. If you are doing this, please revise as
needed.
• LWE is not choosing this option. Side slopes were revised to 3:1
o Please revise the vegetated conveyance design information in the Supplement-EZ Form
so that it corresponds to the vegetated conveyance design information as shown in the
calculations. For example, for vegetated conveyance#1,the Supplement-EZ Form shows
a Vallowable of 6.0 fps (calculations show a Vallowable of 5.0 fps), a Vactual of 1.28 fps
(calculations show Vactual of 3.72 fps), and flow depth of 1.55 ft(calculations show 0.79
ft).
• Corrected
o NOTE: Per the earlier comment,the vegetated conveyance calculations will need to be
updated to reflect the actual design so these values may change from what is shown in
the example based on the new calculations. Please revise as needed.
• Side slopes revised to 3:1
- The following accounting issues were noted during review(we apologize that they were missed
on the prior review).These changes should not impact the design of the project, but should be
corrected (If the instructions are unclear, please provide me with the project area in square feet
and we can better assist you):
o Please correct the following issues with the Supplement-EZ Form, Drainage Areas Page:
• Entire Site Column:
• Line 5—The "total drainage area"for the entire site is equal to the sum
of Lines 6 & 7.
o Corrected
• Line 6—The "onsite drainage area"for the entire site is equal to the
project area (approximately 85.71 ac).This is because the low-density
area of the project is equal to the portions of the project area that does
not drain to the SCMs.
o Corrected

PREPARED BY: Carlos Lee Ruano, P.E. Latham-Walters Engineering, Inc.
DATE:4/10/2024 16507-A Northcross Drive
LWE RESPONSE Huntersville, NC 28078
• Line 7—Typically, there are no off-site components to the entire site
column (since the entire site column is an accounting of the project area
and off-site areas are not part of the project area).
o If no off-site components are entered in this cell,then Line 5
should equal to Line 6(from Comments above)
o Offsite drainage labeled 0
• Line 8—Please exclude the existing "off-site BUA"that was previously
included in this value (1,336,962 sf—47,418 sf= 1,289,544 sf).
o Corrected
• Line 11—Please exclude the existing"off-site BUA"that was previously
included in this value (47,418 sf—47,418 sf=0 sf).
o Corrected
• Line 15—Please exclude the existing"off-site BUA"that was previously
included in this value (47,418 sf—47,418 sf=0 sf).
o Corrected
• Line 18—Please recalculate this value.This value will be equal to Line 8
/ Line 5 (and should correspond to the value shown in Section IV, 8 of
the Application).
o Corrected
■ Low-Density Drainage Area Column:
• Please remove the second Low-Density Column. If the entire project
drains to a single surface water(McAllister Creek),then there would
only be a single low-density area, even if it is non-contiguous.
o Corrected
• Line 5—Equal to the sum of Lines 6 & 7
o Corrected
• Line 6—As mentioned earlier, the low-density area is equal to the
portions of the project area that do not drain to one of the SCMs (based
on the provided information,this value would be approximately 20.71
ac(85.71 ac—18.23 ac—10.33 ac—8.87 ac—9.56 ac—8.07 ac—9.94 ac
= 20.71 ac
o Previous calcs were based off the NCDOT R/W. If considering
remainder of the project site (that does not drain to SCM),
then value is much less than reported. Corrected.
• Line 7—Typically, there are no off-site components to low-density
areas, even if off-site areas drain onto the low-density area (see
guidance Section IV, 9 of the Application).
o Corrected
• Line 8—Please exclude the existing "off-site BUA"that was previously
included in this value. For this project, this value should be equal to Line
12, Roadway(see below).
o Corrected
• Line 11—Please exclude the existing"off-site BUA"that was previously
included in this value.
o Excluded

PREPARED BY: Carlos Lee Ruano, P.E. Latham-Walters Engineering, Inc.
DATE:4/10/2024 16507-A Northcross Drive
LWE RESPONSE Huntersville, NC 28078
• Line 12, Roadway—Please combine the values from the two previously
provided low-density columns (14,314 sf+7,559 sf=21,873 sf).
o Corrected
• Line 15—Please exclude the existing"off-site BUA"that was previously
included in this value.
o Excluded
• Line 18—Please recalculate this value. This value will be equal to Line 8
/Line 5.
o Corrected
o Please correct the following issues with the Application:
• Section IV, 8—Please revise this value if needed (see earlier comment).
• Section IV, 10, LD Column:
• Total Drainage Area—Revise to correspond with Line 5 of the Low-
Density Column on the Drainage Area Page of the Supplement-EZ Form.
o Corrected
• On-Site Drainage Area—Revise to correspond with Line 6 of the Low-
Density Column on the Drainage Area Page of the Supplement-EZ Form.
o Corrected
• Off-Site Drainage Area—Revise to correspond with Line 7 of the Low-
Density Column on the Drainage Area Page of the Supplement-EZ Form.
o Zero,according to comment above,Corrected
• % Impervious Area—Revise to correspond with Line 18 of the Low-
Density Column on the Drainage Area Page of the Supplement-EZ Form.
o Corrected
• Off-Site—Please exclude the existing "off-site BUA"that was previously
included in this value (corresponds to Line 11 of the LD Column).
o Zero, Corrected
• Total—Revise to correspond with Line 8 of the Low-Density Column on
the Drainage Area Page of the Supplement-EZ Form.
o Corrected
Please provide the following:
- 1x hard copy& 1x electronic copy of the revised pages of the Application Form.
- 1x hard copy& 1x electronic copy of the revised pages of the calculations.
- 1x hard copy& 1x electronic copy of the revised pages of the Supplement-EZ Form.
- 1x hard copy(2x hard copies for plans) & 1x electronic copy of any items needed to address
these comments.
Hard copies should be mailed to me at the following address:
For FedEx/UPS:
Jim Farkas
512 N. Salisbury Street, Office 640M
Raleigh, NC 27604

PREPARED BY: Carlos Lee Ruano, P.E. Latham-Walters Engineering, Inc.
DATE:4/10/2024 16507-A Northcross Drive
LWE RESPONSE Huntersville, NC 28078
Electronic copies should be uploaded at the following location:
https://edocs.deq.nc.gov/Forms/SW-Supplemental-Upload
The permit for this project has been drafted. Provided that everything is in order with the resubmission,
we can issue the permit soon after receiving the requested information. Let me know if you have any
questions.
Jim Farkas
State Storm water Engineer
North Carolina Department of Environmental Quality
Office: [phone]
[e-mail]