Sanitary wipes suspected cause of $190K damage to water treatment plant

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By Nick Seebruch
Sanitary wipes suspected cause of $190K damage to water treatment plant
Photo from City of Cornwall staff report showing the damaged screen being lifted out of its spot at the Waste Waster Treatment Plant.

CORNWALL, Ontario – Cornwall City Council approved paying $187,273 from the Wastewater Works Reserve to cover damages to the Waste Water Treatment Plant (WWTP).

On Saturday, May 16, 2020 alarms notified staff at the WWTP that a traveling bar screen was not operating. The lower screen had been blocked and began to back up, which lead to an excess of 2,000 cubic meters of raw sewage spilling out into the St. Lawrence River.

The city quickly brought in pumps to divert the sewage and were able to access the blocked screen, which had been damaged and repairing the unit in place proved difficult.

“Removal of the bar screen proved extremely difficult as it was subsequently learned that the bar screen had been fastened within the lower portion of the guiderails well below the surface level of the raw sewage,” the staff report to Council reads. “This prevented the bar screen to slide upward out of the guide rails and out of the wet well. The removal  process was also problematic due to the twisted superstructure components of the bar screen jamming within the guiderails.”

Eventually, the city got a crane that could lift up to 20 tonnes.

“Numerous attempts were made before the bar screen finally broke free. The entire effort associated with repair attempts and removal occurred over a six-day period,” the report goes on to read.

The screen was then sent to the manufacturer for repairs and is expected back this week.

“In the meantime, WWTP staff manually clean a backup, non mechanized bar screen on a daily basis,” the administration report states.

City staff believe that the damage to the screen was caused by the large amount of sanitary wipes that had been flushed down the toilet.

Bill de Wit, the City’s General Manager, Infrastructure & Municipal Works said that all of the money being taken out of the Wastewater Works Reserve would go towards expenses like contracting the crane, contracting millwrights, and paying for the repairs to the screen rather than overtime pay to city staff.

“There was a significant amount of overtime, but that was carried in our operating budget. There were many hours of overtime,” de Wit explained.

Mayor Bernadette Clement praised the work of city staff.

“I remember Saturday morning getting a text from the CAO saying this occurred, that staff was on top of it, and that the Ministry had been informed,” Clement said, explaining that she chose to walk over to the WWTP.

“I was able to thank staff. Let me tell you, they were very proud that they were able to handle the magnitude of this problem,” said Clement. “I was really proud. It served as a reminder of the confidence we should have in our staff.”

As of September 2020 there was $3,842,312 in the Wastewater Works Reserve. The 2020 target of the reserve is $3,729,979.

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