SW3191202_Northgate NCDEQ Stormwater Comment Response_2/11/2020

1318-e6 central ave. P 704.334.3303
charlotte, nc 28205 F 704.334.3305
urbandesignpartners.com
Date: February 11, 2020
To: Corey Anen
D E S I G N R B A N
NCDEQ Division of Energy, Mineral and Land Resources
PARTNERS
512 N. Salisbury Street
Raleigh, NC 27699
Re: The Residence at Northgate
UDP Project No: 19-039
Stormwater Permit No. SW3191202
Dear Corey,
Below is a summary of the comments and response of the stormwater submittal for the above
referenced project. The comments were dated 01/13/2020. Plans are being submitted to Iredell
County for re -review.
Environmental Engineer — Corey Anen (01/13/2020)
Review Comments
1. Please update Page 1 of the SWU-101 application to indicate that a sedimentation
and erosion permit will be required for this project with the area of disturbance.
4 Revised.
Please make the following updates to the Supplement EZ form:
a. On the "Drainage Areas" sheet, the calculation method (Field 19) should be
the calculation method used to calculate the runoff volume (Simple Method
or NRCS Method).
b. Please indicate the elevation of the seasonal high-water table.
c. Please indicate the type of bypass device (weir, orifice, etc.).
d. Please indicate the elevation of the bypass device.
e. Please indicate the mechanism for distributing flow over the sand surface
(riprap berm).
4 The supplement EZ form has been revised per the required revisions.
3. Please provide calculations to show that the underdrains are sufficiently sized to
drain the system. Guidance on these calculations can be found in Chapter A-5 of the
Stormwater Design Manual.
4 Underdrain calculations have been added to the Stormwater Report.
4. Please specify on the plans that the sand media shall meet the standards of ASTM
C33 or the equivalent (Sand Filter MDC 6). The entire bottom surface of the sand
chamber must consist of sand.
LANDSCAPE ARCHITECTURE + CIVIL ENGINEERING

4 The section view of the sand filter on C-5.1 has been revised per this comment.
Note 2 states that the sand media shall meet the standards of ASTM C33.
5. Provide pdfs of all revisions, 2 hardcopies of revised plan sheets, and 1 hardcopy of
other documents. Pdfs must be uploaded using the form at:
https:Hedocs.deg.nc.gov/Forms/SW Project Submittal
4 This resubmittal includes 2 hardcopies of the plans and one copy of all other
documents. Pdfs have been uploaded to the provided website.
I believe we have addressed all the comments sufficiently. If you have any further
questions/comments, please feel to give me a call.
Brian D. Smith, P.E.
Partner
Urban Design Partners