NC0047597_NOV-2022-LV-0247 Response_20220623

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WATER MANAGEMENT
CITY OF DURHAM
June 23, 2022
Ms. Vanessa E. Manuel, Assistant Regional Supervisor
Water Quality Regional Operations Section
Raleigh Regional Office
Division of Water Resources, DEQ
RE: Notice of Violation & Intent to Assess Civil Penalty
NOV-2022-LV-0247; Permit No. NC0047597; South Durham WRF
Dear Ms. Manual,
On June 15, 2022, the City of Durham received the referenced Notice of Violation & Intent (NOV/I) to Assess Civil
Penalty. The City of Durham, Department of Water Management (DWM) respectfully requests a recension of
the NOV/I for Mercury loading exceedance based on the following information.
The letter references a review of the February 2022 Discharge Monitoring Report (DMR) for the South Durham
WRF which reported a total Mercury effluent value of 28.2 ng/I on 2/7/22. Further, the letter states that the
value is an exceedance of the annual load. The current NPDES permit for the South Durham WRF states that
total Mercury grab samples are to be collected and analyzed quarterly, with an annual average of 12 ng/I as the
permit limit. Three additional samples will have to be collected and analyzed to determine the annual average
has been exceeded for the calendar year 2022.
However, it is much more important to note that the initial total Mercury value reported for February was
incorrect. Upon receiving the February results from the reference lab, staff immediately reached out because
the total Mercury effluent and influent values appeared to be reversed. There were multiple exchanges by email
and phone with the reference lab regarding the results. Due to equipment malfunctions at the regular site, the
February samples had to be shipped to another one of their labs, which delayed the receipt of updated results.
In order to meet submittal deadlines, DWM processed and submitted the February DMR on 3/27/22. Corrected
total Mercury results, which confirmed that the influent and effluent results had been reported incorrectly
(switched), were received on 4/20/22. These updated results (0.506 ng/I — effluent total Mercury and 21.9 ng/I —
influent total Mercury) were entered into the eDMR platform by the ORC on 4/21/22, however, due to an
oversight on our part, the corrected report was not actually submitted until 6/16/22. The reports from Pace
Analytical (both initial and follow-up) are attached for your review.

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We apologize for our oversight in submitting the corrected report as soon as the results were received. This
would have prevented the issuance of the NOV/I. We will review our eDMR submittal process to prevent
further occurrences of these issues. Please feel free to reach out to Vicki Westbrook
([e-mail]) or Charles Cocker ([e-mail]) if you have any additional
questions or concerns.
Best regards,
Donald F. Greeley, Director
C: Alys Hannum, DEQ
Vicki Westbrook, DWM Assistant Director
Charles Cocker, ORC — South Durham WRF
WQS Raleigh Regional Office — Enforcement File