NC0026611_More Information (Requested)_20230918

DocuSign Envelope ID: 31 FE7DB3-5717-42A9-9487-1 FADOB471 FE1
ROY COOPER
Governor
ELIZABETH S. BISER
Secretary
RICHARD E. ROGERS, JR.
Director
Daniel Williams, Public Services Director
Town of Morehead City
1100 Bridges Street
Morehead City, NC 28557
Dear Mr. Williams:
NORTH CAROLINA
Environmental Quality
9/18/2023
Subject: Review of CORMIX Modeling Plan
NPDES Permit No. NCO026611
Morehead City WWTP
Carteret County
The Division of Water Resources (DWR) reviewed the "Modeling Plan for Mixing Zone Analysis of
Calico Creek at Morehead City WWTP Outfall" submitted to the NPDES Permitting Branch on June
12, 2023. The report was submitted by Tetra Tech on behalf of the Town of Morehead City to
develop and apply a mixing zone model to evaluate the potential for a recalculation of permit limits
based on observed and modeled dilution at the point of discharge. Based on our review of the plan,
the Division has the following comments and requests for additional information:
1. Please provide additional clarity for the dilution calculations:
a. Identify what you believe will be the near -field? Circle and describe the possible near -
field on the EFDC model grid in Figure 2.
i. What distance upstream and downstream? What portion of the tidal cycle?
b. Further discuss how the EFDC model will be used to determine dilutions.
2. Further define deliverables.
a. Ensure that the final model provides dilutions for each cell in all three vertical layers.
b. How will the critical cell be determined?
Should you have any questions, please feel free to contact Kristin Litzenberger at [phone] /
kistin.litzenbergergdeq.nc.gov or Michael Montebello at [phone] / michael.montebellogdeq.nc.gov.
Respectfully,
Do''c''u..SignelId by, A,, h',,.'' `
C464531431644FE...
Michael Montebello
NPDES Program Branch Chief
North Carolina Department of Environmental Quality I Division of Water Resources
512 North Salisbury Street 1 1617 Mail Service Center I Raleigh, North Carolina 27699-1617
NORTH CARCLINA
919.707.9000

DocuSign Envelope ID: 31FE7DB3-5717-42A9-9487-lFADOB471FE1
ec: NPDES Files [Laserfiche]
Town of Morehead City / Chuck Falls [[e-mail]]; Nick Cunningham
[[e-mail]]; Brandi Thomas [[e-mail]]
Tetra Tech / Hillary Yonce [[e-mail]]; Ellie Kremer [ellie.kremer@tetratech]
Shealy Consulting / Laura Davis [[e-mail]]
McDavid Associates, Inc. / Trey Gurley [[e-mail]]; Tyndall Lewis [[e-mail]]
DWR / Nick Coco [[e-mail]]; Doug Dowden [[e-mail]]; Kristin Litzenberger
[[e-mail]]; Derek Denard [[e-mail]]
DWI / Trupti Desai [[e-mail]]
WiRO / Tom Tharrington [[e-mail]]
REQ5 North Carolina Department ofEnvironmental Quality I Division ofWater Resources
512 North Salisbury Street 1 1617 Mail Service Center I Raleigh, North Carolina 27699-1611
NORTH CAROLINA 919.707.9000
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