NC0038377_Comments_20240105 (2)

From: Chernikov, Seroei
To: Tollie, Lori White; McDaniel, Kim Spence
Subject: RE: [External] RE: Duke Energy Mayo NPDES NCO038377
Date: Wednesday, November 29, 2023 8:52:33 AM
Lori,
Your understanding is correct.
Thank you!
Sergei
Sergei Chernikov, Ph.D.
Environmental Engineer III
Industrial NPDES Permitting Unit
NEW Tel. [phone]
1617 Mail Service Center, Raleigh, NC 27699-1617
Express Mail: 512 N. Salisbury St., Raleigh, NC 27604
NEW E-MAIL:[e-mail]
From: Tollie, Lori White <[e-mail]>
Sent: Wednesday, November 29, 2023 7:52 AM
To: Chernikov, Sergei <[e-mail]>; McDaniel, Kim Spence <Kim.MCDaniel@duke-
energy.com>
Subject: [External] RE: Duke Energy Mayo NPDES NCO038377
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Sergei,
Another question/comment came up after further review of the draft permit. Permit condition A(4).
is associated with internal Outfall 002A the lined retention basin, now has a toxicity sampling
requirement after ash basin dewatering is complete. Internal Outfall 002A comingles with other low
volume waterwater before final discharge into Mayo reservoir via Outfall 002. Outfall 002 will
continue to be the final discharge even after basin closure activities are complete. It's my
understanding that Outfall 002 would be the location for sampling to account for all wasterwater
flow leaving the Mayo Station. Please let me know if you have any questions about this or if you
would like to discuss further.

Thankyou
Lori W. Tollie
Duke Energy
Permitting & Compliance
500 Utility Drive
Lewisville, NC 27012
Cell: [phone]
Office: [phone]
From: Tollie, Lori White
Sent: Monday, November 27, 2023 1:16 PM
To: Chernikov, Sergei <sergei.chernikov(@deq.nc.gov>; McDaniel, Kim Spence <Kim.McDaniel (cDduke-
energy.com>
Subject: Duke Energy Mayo NPDES NC0038377
Sergei,
I wanted to send you the following comments on the Mayo NPDES draft permit and fact sheet. The
fact sheet incorrectly lists that ash basin dewatering began in October of 2023. Dewatering begin on
May 24, 2021. 1 have attached the email correspondence notifying the Division of commencement.
There is ample effluent data to support the reduction of sampling at Outfall 002 from weekly to
monthly and to return toxicity sampling to quarterly at Outfall 002.
Permit condition A(3). Also still has the nonstandard permit language concerning notification of any
exceedance of 85% of the allowable level of certain constituents.
The supplement to the permit cover sheet should not contain the language "upon completion of
construction" for the Lined Retention Basin. The LRB is complete.
Please let me know if you have additional questions or need additional information.
Thankyou
Lori W. Tollie
Duke Energy
Permitting & Compliance
500 Utility Drive
Lewisville, NC 27012
Cell: [phone]
Office: [phone]

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