NC0024881_NOI2022LV_0467_0468_Response_20220718

RESPONSE TO NOV-2022-LV-0467 AND 0468 FOR PERMIT NUMBER NC0024881
Beginning in December 2021, lab analyses of the City of Reidsville's wastewater
treatment plant effluent revealed increasing concentrations of CBOD, ammonia, and
fecal coliform bacteria.
These concentrations continued building through January 2022 and eventually led to
non-compliance in all three parameters for February 2022 and for CBOD and ammonia
in March and April 2022.
The facility also reported non-compliance for CBOD for three weeks and the month for
May 2022. The facility will report non-compliance for CBOD for three weeks and the
month for June 2022. Ammonia has been largely below detection thresholds since
week 3 in April and fecal coliform bacteria's only excursion was in February.
All of these violations are a result of the plant kill described below as reported for the
response to NOV-2022-LV-0319.
The ultimate cause of these exceedances was an almost total kill of the facility's
biological treatment process. Contributing factors were:
• Equipment failures of both of the facility's primary wasting systems.
• Secondary wasting method inefficiency increased ammonia throughout the
facility due to excessive supernatant.
• Blockages in several diffusers significantly diminished air flow in the entry zone of
the aeration basin.
• Septicity throughout the entirety of the secondary treatment processes due to
significantly increased solids concentrations and age -related return pump
inefficiency.
• Excessive filamentous growth due to pumping septic liquid from an off-line
aeration basing into the active aeration basin.
The City of Reidsville has undertaken the following corrective actions:
• The primary wasting systems have been returned to service, and solids
concentrations have been drastically reduced.
• Lower solids concentrations have reduced the load on the return sludge train.
• A solid air flow has been re-established to the entry end of the aeration basin.
• Procured and incorporated biological compounds for short-term use to boost
treatment efficiency.

In plain language, the City of Reidsville lost the plant for approximately four to six
weeks. Recovery has been slow, however the facility is currently operating
efficiently.