NC0020184_Correspondence_20220920

Strickland, Bev
From: Shellenbarger, David <[e-mail]>
Sent: Tuesday, September 20, 2022 5:16 PM
To: Tuvia, Ori A
Cc: Scheringer, Stephanie B; Martinez, Rene; Brothers, Mourice
Subject: [External] Internal Reuse Water Issue at Long Creek WWTP
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Ori:
As discussed today by phone, the Long Creek WWTP experienced a leak from the internal reuse water piping which
necessitated shutting the internal reuse water system down and resulted in the discharge of plant effluent that was not
fully disinfected.
Two Rivers Utilities' maintenance staff was replacing a check valve on the internal reuse water system. At 1305 on
9/19/2022, after the check valve was removed the pipe turned causing a leak in a mega lug joint which is common to
both pumps. An estimated 400 gallons of reuse water (chlorinated plant effluent) leaked onto the ground and partway
down rip -rap of a stormwater outfall. It did not reach surface water. The reuse water flow was turned off
approximately 5 minutes after the leak started.
The internal reuse water is used as carrier water to feed chlorine and sulfur dioxide for disinfection and
dechlorination. The chlorine contact basin will maintain chlorine residual for approximately an hour after chlorine feed
stops. No visible chlorine was detectable in the chlorine contact basin when checked at approximately 1500.
Maintenance staff worked diligently to straighten the pipe and get the new check valve in place. At 15:20 the internal
reuse system was back on line and chlorine was feeding. At 1525 chlorine was detected in the chlorine contact basin.
Based on the flow for the day and an estimate of 1.25 hours of discharge without chlorine in the contact basin, it is
believed that 275,000 gallons was discharged into the South Fork Catawba River without full disinfection.
Due to this event, fecal coliform sampling was conducted at the upstream and both downstream sampling
locations. Results are as follows:
Upstream sampled 9/19/22 at 1600 = 1074 cfu/100mL
Downstream D1 sampled 9/19/22 at 1613 = 1261 cfu/100mL
Downstream D2 sampled 9/19/22 at 1634 = 180 cfu/100mL
Staff is analyzing this incident and working to develop contingencies for similar issues. Please let us know if you would
like any additional information regarding this incident.
Thanks,
David Shellenbarger
Assistant Division Manager Compliance
Wastewater Treatment Division
Two Rivers Utilities / City of Gastonia
704-842-5106
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