OHA Drinking Water Services
OHA Drinking Water Services
Contact Report Details

PWS ID: OR41 00149
Who Was Contacted: Leo Rainwater
Contact Phone: 530-650-5366 (Email address hidden)
Contact Date: 05/27/2021
Contacted By: DOWNS, KENT (DWP)
Contact Method/Location: Phone
Reasons: Other
Details: 05.27.21 - Leo contacted me to report an event that resulted in turbidity spikes entering the clearwell and distribution system.

At approximately 9:00 am Thursday morning, one of the operators was performing daily rounds at the city of Brookings Rainey collector. He performed a pump rotation from pump #2 to pump #3.

The operator mistakenly neglected to run the initial water pumped to waste and it resulted in a slug of water that was over 1 NTU turbidity being pumped to the Clearwell. 1 hour later the high turbidity alarm on the water leaving the clearwell was activated. Between 10:30 am and approximately 11:45 am there were 5 turbidity spikes over 1.0 NTU. Turbidity alarm is set to 0.250 NTU with a 5 minute delay. Only one of the turbidity spikes was over the 0.250 NTU more than 5 minutes. The alarm shut down the pumps that feed the 1.5 million gallon tank. The turbidity continued to be above 1.0 NTU after the pumps were offline. Leo instructed one of the operators to backwash one of the offline filters to pull some of the higher turbidity back through the filter plant to waste through the backwash into the backwash pond. With the pumps offline we flushed water out of the plant building. When the turbidity dropped below 0.30 NTU we restarted the effluent pumps. There were no additional spikes after the restart. By approximately 4:30 pm the turbidity leaving the plant was 0.220 NTU and had dropped to an average of 0.10 NTU by 5:30 pm.

The lowest chlorine residual leaving the clearwell was 0.86 mg/l for approximately 10 minutes with average chlorine residual at 1.25 mg/l throughout the event. On the morning of 05.28/21 turbidity is reported to be averaging 0.08 NTU this morning. No public advisory needed.

To prevent future turbidity events of this nature an SOP is being developed to include weekly pump rotations and a pumping to waste period prior to the pump being put into service supplying water to the system. Additional staff training will be conducted.

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