WQCS00004_NOV2023DV0243_RESP_20230626

7.
Metropolitan Sewerage District
OF BUNCOMBE COUNTY NORTH CAROLI NA
June 26, 2023
Mr. G. Landon Davidson, Regional Supervisor
Water Quality Regional Operations Section
Asheville Regional Office
Division of Water Resources, NCDEQ
2090 U.S. Highway 70
Swannanoa, NC 28778
Subject: Notice of Violation
NOV-2023-DV-0243
Sanitary Sewer Overflow- May 2023
2020 Riverside Drive
Collection System Permit No. WQCS00004
Buncombe County
Dear Mr. Landon Davidson:
This letter is in response to the subject NOV at 2020 Riverside Drive issued in your letter
dated June 7, 2023.
On May 28, 2023, MSD's service area received a large amount of rain causing higher than
normal influent flows. MSD utilizes 3 high raw water influent pumps (35 MGD each), one
lead, one lag, and one as back-up standby. The pumps can be isolated and protected by
electronic valve actuators which will ultimately close during power outage to protect the
pumps from spinning in reverse. During this time, MSD had a lead and lag pump online due
to higher -than -normal flows. At approximately 1:45 PM Duke Energy's power grid
experienced a brief system fault. The brief power fault caused both lead and lag pumps to
shut down, and valve actuators to close. Power quickly returned to normal, pumps had to
reset, and valving had to open. The lead pump was back online at 1:50pm with the lag
pump back online shortly after. Due to increased flow during this time of the power fault,
the amount of time required to re -open electronic valve actuators, and the amount of time
to bring pumps back up to speed, MH # 51-15342 experienced a brief overflow.
MSD has 4MWs of standby generator capabilities, 2 separate power feeds from Duke
Energy with an automatic Transfer Switch if one fails, and 2.8-Kilowatt hydroelectric
power generation capabilities. In addition, MSD has two Godwin DPC 300 12" Dri-Prime
pumps placed at the head of treatment plant capable of assisting bypassing flow around the
influent pump station in times of need.

MSD staff reached out to Duke Energy to investigate the cause of the power failure. Duke
Energy was unable to determine the cause of the brief event, as the operation was short,
and the electrical fault cleared itself. Despite all the protective measures MSD has in place
to protect the operations from a power outage, this brief event was outside the control of
MSD.
If you have any additional questions regarding the brief overflow, please give me a call.
Respectfully,
a, )-,V
C. Kenneth Stines
Division Director
System Services Division
MSD of Buncombe County, NC
[e-mail]
[phone]
cc: Tom Hartye
Protecting Our Natural Resources-
2028 Riverside Drive ASHEVILLE, NORTH CAROLINA 28804 TELEPHONE: [phone] FAX: [phone] WEBSITE: www.msdbc.org