NC0024945_Correspondence_20221206

From: Sypolt, Shannon
To: Bell, Wes
Cc: Bolick, Jacob; Macomber, Maggie; DeWitt, Darrell; Lockler, Joseph; Pitner, Andrew
Subject: [External] CLTWater - Irwin Creek WWTP (NPDES NC0024945) Response to NOV/Recommendation for
Enforcement
Tuesday, December 6, 2022 8:36:00 AM
Date:
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Mr. Bell,
Please let this letter serve as Charlotte Water's (CLTWater's) formal response to the Notice of
Violation/Recommendation of Enforcement letter issued to Irwin Creek WWTP (Irwin Creek) and
received by CLTWater on Wednesday, November 23, 2022. CLTWater respectfully requests that
NCDWR-MRO accept this additional information regarding this incident:
1. This was an unforeseen/unanticipated event that was outside all reasonable control of
Irwin Creek/Charlotte Water.
The cause of this event was due to the unresponsiveness of a Programable Logic Controller
(PLC), equivalent to your desktop or laptop computer freezing up and becoming
unresponsive. CLTWater could not have reasonably anticipated this event. Therefore,
having the expectation that CLTWater could have, in some way, prevented this incident
from occurring is also unreasonable.
2. Irwin Creek maintained full compliance with all permitted effluent limitations.
Irwin Creek maintained full compliance with all effluent limitations for the month of
November. Irwin Creek has a daily maximum fecal coliform limit of 1000 cfu/100m1. The
fecal coliform result collected on November 1st was <1.0 cfu/100m1s.
3. This event had no human health or environmental impacts.
Since Irwin Creek was in full compliance with its effluent limitations it is reasonable to
conclude that there was no impact to public health or the environment because of this
happening. This event occurred in the early morning hours during a winter month
(November) as defined by our permit. It is highly unlikely that recreation or public contact
with the water in Irwin Creek occurred during this event.
4. Corrective action has been taken to minimize/prevent future occurrences.
Irwin Creek has installed electronic timers to monitor the internal clocks on each of the

plant's PLC's. In the future, if the clock stops moving, signifying a PLC has halted, this will
trigger an alarm on SCADA and on the operator phones. While there is no action that
could necessarily prevent this from occurring again in the future, this action will help to
reduce our response time.
5. History of Self Reporting Events.
CLTWater has a long history of open and honest communication with NCDEQ-DWR.
CLTWater promptly self -reports all events that occur at our facilities. CLTWater takes
environmental compliance very seriously and continuously seeks to improve all aspects of
our business.
6. Excellent Compliance Record.
Irwin Creek has won the National Association of Clean Water Agencies Peak Performance
Awards for exceptional compliance for eight straight years. Irwin Creek is also designated
as an exceptionally preforming facility by NCDEQ-DWR. This affords Irwin Creek a reduced
monitoring frequency for all conventional pollutants including fecal coliform. Although we
are only required to sample for fecal coliform twice a week, we still collect five days of
samples to demonstrate the effectiveness of our treatment process and our commitment
to the protection of public health and the environment.
CLTWater takes environmental compliance very seriously and we appreciate the opportunity to
provide additional information related to why we do not feel that further enforcement upon Irwin
Creek is appropriate or necessary. If you have any questions concerning the information contained
in this response, or if you need any additional information, please feel free to contact me directly at
704-634-6984.
Respectfully,
Shannon Sypolt
Water Quality Program Administrator
Environmental Management
CHARLOTTE W TER
4222 Westmont Drive / Charlotte, NC 28217
P: 704-336-4581 / C: 704-634-6984 / charlottewater.orq