SW3210801_Response To Comments_20220128

H THOMAS & HUTTON
1020 EUCLID AVENUE
CHARLOTTE, NC 28203 1 980.201.5505
WWW.THO MASAN OH UTTON.COM
January 20, 2021
Attn: Jim Farkas
NCDEQ - Stormwater
512 N. Salisbury Street, Office 640K
Raleigh, NC 27604
Re: 1-85 Commerce Center
NCDEQ - Stormwater Review
Salisbury, NC
J-29101.0000
Mr. Farkas:
This letter serves as acknowledgement that we have revised the previously submitted package to
address all comments below as follows:
Original Comment 4 (Prior Comment 11- "The percent impervious cover of the project
area appears to be incorrectly calculated (Section IV, 8). The percent impervious
cover is calculated as follows: [To Impervious Cover] = [Total Proposed BUA] / [Project
Area]" The project percent impervious area appears to be calculated incorrectly in
Section IV, 8 of the Application. The total impervious area value used in the
calculation should be the total impervious area located within the project area
(1,282,035 sf or 29.43 ac) not the total amount of impervious area located within the
drainage area to the wet pond (1,296,852 sf or 29.77 ac) . This value should match Line
18 of the Entire Site Column on the Drainage Areas Page of the Supplement-EZ Form.
The impervious area was corrected to 29.43 ac within the calculation on the
Application. The updated percent impervious is 70.3% = (29.43/41.87) x 100. This was
simplified on the application to 70% to match the Supplement-EZ Form.
2. Original Comment 20 (Prior Comment 31- "Please correct the following issues with
the O&M Agreement Form..." Please provide an original signed copy of the O&M
Agreement. You will also need to revise the design summary page of this form to
match the information in the latest submission.
The design summary page of the O&M has been updated. The original signed copy
of the O&M form is included with this submittal.

3. Prior Comment 7 - There is still a discrepancy between the drainage area information
shown in the calculations and the value shown in the Application/Supplement-EZ Form.
For example, the water quality calculations page shows the drainage area to the SCM
as 39.20 ac (39.22 ac in the Application/Supplement-EZ Form), the impervious are within
the drainage area as 29.56 ac (29.77 ac in the Application/Supplement-EZ Form), and
the design volume as 130,687 cf (104,471 cf in the Application/Supplement-EZ Form).
Please revise as needed.
The drainage and impervious areas have been updated to 39.22 acres and 29.77 acres
in the water quality spreadsheet to match the EZ form and application. The design
volume has been updated to 104,377 in the EZ form and application to match the
water quality calculation spreadsheet.
4. Please correct the following issues with the Wet Pond Page of the Supplement-EZ Form:
a. Line 34 - The cleanout depth of the forebay is the distance from the permanent
pool elevation (764.0) to the top of the sediment storage zone (759.0) expressed
in inches (764.0 - 759.0 = 5' = 60").
Updated
b. Line 43 - The depth of the forebay at the entrance is the distance from the
permanent pool elevation (764.0) to the excavated bottom of the forebay near
the entrance (758.0) expressed in inches (764.0 - 758.0 = 6' = 72").
Updated.
c. Line 44 - The depth of the forebay at the exit is the distance from the permanent
pool elevation (764.0) to the excavated bottom of the forebay near the exit
(758.5) expressed in inches (764.0 - 758.5 = 5.5' = 66").
Updated.
d. Line 8* - Pond parts 2-4 appear to have emergency spillways which would
qualify as a type of overflow/bypass.
Updated.
e. Line 54* - The pond detail sheets include a planting plan for the wet pond
Updated.
Please provide the following:
1. I hard copy and I electronic copy of the revised page of the Application.
2. Ix original, signed, hard copy of the O&M Agreement Form and updated design
summary page.
3. 1x hard copy and I electronic copy of the revised calculations.
4. 1x hard copy and I electronic copy of the revised Supplement-EZ Form page.
5. 1 x hard copy (2x hard copies for plan sheets) and Ix electronic copy of anything else
needed to address the comments.

Hard copies should be mailed to me at the following address:
For FedEx/UPS:
Jim Farkas
512 N. Salisbury Street, Office 640E
Raleigh, NC 27604
For USPS:
Jim Farkas
1612 Mail Service Center
Raleigh, NC 27699-1612
Electronic copies should be uploaded at the following location:
https://edocs.deg.nc.gov/Forms/SW-Supplemental-Unload
We look forward to receiving the approved certification for the referenced project to
allow us to proceed. If you have any questions, comments, or desire additional information, please
contact our office at [phone].
Sincerely,
THOMAS & HUTTON
Brad Smith, PE, PMP
Project Manager III