WQCS00249_NOV-2019-DV-0348 Response_20190909

ONWASA
September 3, 2019
Tom Tharrington, Assistant Regional Supervisor
Water Quality Regional Operations Section
Division of Water Resources, NCDEQ
127 Cardinal Drive Extension
Wilmington, North Carolina 28405
RE: Notice of Violation
Tracking Number NOV-2019-DV-0348
Sanitary Sewer Overflows — July 2019
Permit No. WQCS00249
Onslow Water and Sewer Authority, Onslow County
Mr. Tharrington:
RFCEiti rt/:,i OF.N R/OWR
SIP 0 9 2019
Water duality ReEional
Operations Se�tien
This letter is sent in response to the August 22, 2019 Notice of Violation (NOV) issued by
your office for sanitary sewer overflow (SSO) incidents that occurred within the ONWASA
collection system during the month of July 2019.
While ONWASA does not dispute the occurrence of the two events listed in the NOV, as
they were self -reported, we offer the following information for your consideration in determining
whether further action (including civil penalties) is warranted:
Incident Number 201901235, Piney Green Pump Station — The SSO at this location was
caused by a combination of human and mechanical error. ONWASA staff working at this
pump station failed to reset operating controls for the pumps prior to leaving the site; this was
compounded by the failure of a level transducer that would have triggered an alarm prior to
overtopping of the pump station wet well. Once discovered by another employee visiting the
site, ONWASA personnel reset pump operation and cleaned up the site. Since the incident,
the level transducer has been replaced and staff have received both additional training and
updated standard operating procedures to help prevent a recurrence of this situation.
Incident Number 201901263, 368 West Corbett Avenue — The SSO at this location was
caused by failure of an existing 8-inch diameter truss -style gravity sewer line that was exposed
and damaged when a portion of an adjacent driveway embankment and an old wooden
retaining wall collapsed after a heavy rainfall event. Once reported, ONWASA personnel
immediately responded to the site to capture any further discharge and begin repair of the
damaged main. A private contractor was brought in to assist with the repair and worked
through the following night to replace the damaged section with ductile iron pipe, backfill the
excavated area and place additional steel plate shoring to protect the embankment. NCDOT
was also notified, given the site's location immediately adjacent to the road.
228 Georgetown Road • Jacksonville, NC 28540 • Tel [phone] • Fax [phone] • www.onwasa.com

Thank you for your consideration of this additional information. Pease contact me directly
at [phone] or dmohr(d)onwasa.com you have any questions or require more information.
Sincerely,
jj� .
l
David M. Mohr, P.E.
Engineering Director
Onslow Water and Sewer Authority
C: Jeff Hudson, Chief Executive Officer
Matthew Padgett, Distribution and Collections Superintendent