NC0069841_Sand Filter Bypass_20220622

Strickland, Bev
From: Jacob Allen <[e-mail]>
Sent: Wednesday, June 22, 2022 3:41 PM
To: Scheller, Roberto
Cc: Jonathan Jordan; Alex Laytham
Subject: [External] sand filter bypass for Crooked Creek NC0069841
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We spoke today 6-22-2022 @ 0940 about the contractor inadvertently closing RAS modulating valve for Clarifier #4
causing the sludge blanket to back up due to the modulating valve being closed by the contractors performing
construction upgrades. We had a grade 1 operator as our employee who was on call who responded to the SCADA call at
0130 on 6-22-2022 with a high level mud well for sand filters 3-6 at Crooked Creek NC0069841. He logged onto to the
laptop to check it out, the alarm cleared itself, and everything looked normal for the rest of the plant. About 20 minutes
after he received another call for a high alarm for sand filter 3. He came in to see all 6 sand filters were at high levels
along with both mud wells. He put the plant sand filters into bypass mode at 0242 and found Clarifier #4 was "puking"
due to zero flow moving through the RAS valve. He reset the switch for the flow meter back into local and it seemed to
fix the problem. After the sludge blanket went down a few feet he attempted to bring the filters out of bypass mode, but
the gate faulted and was stuck. He halted Effluent sampling and turned UV's to 100%. We will use this as a learning
experience as our operator who halted the sampling is only a Grade 1 Biological operator and is still learning. He has
been instructed to never stop the sampler regardless of what is happening. We will have operators following behind the
contractors to make sure the valves are in the right position at the end of each day. We took stream samples and the
downstream D.O.'s were higher than the upstream D.O. Stream had no visible adverse impacts. We will continue to
monitor the stream. I will follow up with a 5 day report when we put the sand filters back online.
Thanks,
Jacob Allen
Crooked Creek Supervisor I Department WRF
T
M 704.534.2143
[e-mail]
www.unioncountync.gov
LUNIOIPU1TY
WATER
Union County Government
4015 Sardis Church Road
Monroe, NC 28110
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