NC0026051_nov-2023-dv-0181_20230530

Engineering and
Environmental Services
Utilities Division
May 26, 2023
RETURN RECEIPT REQUESTED
CERTIFIED MA11,#70080500000098652422
Mr. Scott Vinson
NCDEQ—Division of Water Resources
Attn: Raleigh Regional Office
1617 Mail Service Center
Raleigh, NC 27699-1617
RE: Notice of Violation, NOV-2023-DV-0181
Dear Mr. Vinson:
This is in response to the Notice of Violation dated May 5, 2023 and received by Durham County
on May 23, 2023. The Triangle Wastewater Treatment Plant (TWWTP) self-reported a bypass
incident on March 28, 2023, due to a loss of power for approximately one hour. An estimated
163,854 gallons was discharged into Northeast Creek only receiving partial treatment. TWWTP
has two power feeds that come into the back of the facility. There was a power disruption that
resulted in tripping a breaker in the BNR Mechanical Control Center (MCC) and a utility load
breaker in the Effluent MCC. Because only one utility feed line was lost, the generator did not
recognize the disruption in power and failed to start. This caused a loss of power that affected the
Biological Nutrient Removal (BNR) equipment, tertiary filters, and the Ultraviolet (UV) system
from operating.
The utility load breaker is located in the main utility power cabinet in the Effluent MCC which
requires qualified staff to perform the task. Qualified staff is required to have the appropriate
electrical training and the ability to don a 40 Cal arc-flash suit that specifically fits them. The
trained on-call maintenance staff was called in to complete the task. No sanitary sewer spill
occurred, and the extent of the bypass resulted in effluent being released without proper UV
disinfection.
Durham County TWWTP required each operator, maintenance personnel, and member of the
management team to attend NFPA 70E training in April 2023. We are currently researching the
purchase of some additional arc flash protective personnel equipment (PPE). An electrical
engineering firm has been contracted to conduct an extensive plant electrical evaluation to
determine how to eliminate these breakers from tripping during load testing and small power
disruptions.
5926 NC Highway 55 East,Durham,With Carolina 27713
[phone] ( Fax[phone] ( dconc.gov
Equal Employment/Affirmative Action Employer

To the best of my knowledge this is the first time TWWTP has had an issue with the generator not
responding to a power disruption. Based on the information provided and the action items already
occurring, I request that the Division of Water Resources not pursue further enforcement action.
Sincerely,
Stephanie Brixey
Deputy Director of E&ES/POTW Director
Cc: Dr. Kimberly Sowell, County Manager(via email)
Julio Delgado, Assistant County Manager(via email)
Jay Gibson, Director of E&ES (via email)
Wade Shaw, Utilities Superintendent/ORC (via email)