SW3191105_Millbridge Phase 7E Response to Comments Round 1_12/18/2019

90 �WK
DICKSON
1929-2019 community Infrastructure consultants
December 18, 2019
Corey Anen
North Carolina Department of Environmental Quality - Stormwater Program
512 North Salisbury Street 1 1612 Mail Service Center
Raleigh, North Carolina 27699-1612
RE: Millbridge Phase 7E
Stormwater Permit No. SW3191105
Union County, North Carolina
20170279.00.CL
Waxhaw Planning Division Comments
General
1. The deed restriction forms allow for far more BUA than listed on the application form for
"On -site Buildings/Lots." How is this BUA being accounted for in the design?
Response: BUA was originally accounting for future buildout of the property. All
BMP's have been designed for full capacity, including future phases stormwater. We
have adjusted the Deed Restrictions page to remove future lots and will resubmit for
these lots when the next phase goes to permitting. Is this acceptable to the state?
2. Please delineate all wetlands on site or add a note that none exist as well as the name of
the person/entity that made the determination [15A NCAC 02H .1042(2)(g)(iii)].
Response: One wetland existed on site. Delineation report provided by WEPG has
been provided in addition to a survey completed by Summit of the Carolinas to pick
up stakes placed by the wetland's consultant.
3. Please provide documentation from the NC Secretary of State or other official
documentation showing the titles and positions held by the person who signed the
application [15A NCAC 02H .1042(2)(b)(ii)].
1213 W. Morehead Street
Suite 300
Charlotte, NC 28208
Tel. [phone]
www.wkdickson.com Aviation 9 Water Resources 9 Community Development 9 Energy

NCDEQ — Stormwater Program
December 17, 2019
Page 2
Response: Both Secretary of State letters have been uploaded to the server. One is
for WSLD Millbridge which is the HOA and Landeavor who is the developer for the
project. Landeavor President, Adam Lorry, has signed the application and is listed as
such on the NC Secretary of State for Landeavor. Is this acceptable to the state?
4. Please provide a signed and sealed copy of the Supplement EZ form. Note that an updated
form of the Supplement EZ is available on the Stormwater Design Manual Website.
Response: Supplement EZ Form has been signed and sealed.
5. The drainage areas listed in the table on Page 3 of the SWU-101 application do not match
the drainage areas and BUA used in the calculations and Supplement EZ form.
Response: The drainage areas in the application have been updated to just reflect
Phase 7E impervious areas only. Permit Modification will be submitted to update
the permit when Phase 7F is designed. Ponds are designed for full buildout.
6. The storage areas used in the calculations to find the temporary ponding depth do not
match the stage -storage data in the adjacent table or the areas shown on the plans. Please
correct this discrepancy to recalculate the temporary pond elevation and drain times.
Response: The Interpolation is based on the Storage Volumes shown directly above
the Forebay Volume and Total Volume. These cumulative volumes are based on
Permanent Pool Storage Volumes to the Right. The header for Storage Area has
been changed to 'cubic feet' to accurately reflect the correct column the calculation
is based on. Is this acceptable to the state?
7. Please show the average depth calculation using either Equation 2 or Equation 3 from the
Wet Pond Chapter in the Stormwater Design Manual.
Response: Average depth Calculations have been added to the Calculations book.
Each pond's main page now has the calculation of each as well as stating which
equation is being used for that pond. Average depths have been rounded down to
the nearest 0.5'.
ICKSON

NCDEQ — Stormwater Program
December 17, 2019
Page 3
8. Please specify the sediment storage elevations in the wet pond on the detail sheets (Sheets
C9.7, C9.8, and C9.9).
Response: Sediment storage elevations have been added to the Wet Pond Detail
sheets. A 12" sediment storage is included below the bottom of the pond so that
pond will still function as designed. The Operations and Maintenance agreements
have been updated to reflect the correct elevations.
9. Please provide rip rap calculations for the outlet from Wet Pond #3.
Response: The print area has been updated to show the missing line for BMP #3.
10. The bottom elevations of Wet Pond 1 and Wet Pond 2 on the detail sheets (Sheets C9.7 and
C9.8) do not match the bottom elevations shown on the grading plan.
Response: The bottom elevations have been updated to match the grading
provided.
11. Please update the Supplement EZ form to reflect any changes made to the wed pond
designs.
Response: EZ Form has been updated to reflect any changes.
12. Provide pdfs of all revisions, 2 hardcopies of revised plan sheets, and 1 hardcopy of other
documents. PDF's uploaded at https://edocs.deg.nc.gov/Forms/SW Proiect Submittal.
Response: PDF's have been uploaded at the provided link. Two (2) Revised Plans
Sets and 1 Calculation Book has been provided in addition to all additional hardcopy
sheets that have changed.
Sincerely,
Connor Horn, EI.
W.K. Dickson & Co., Inc.
ICKSON