A mechanical failure at the sewer plant in Clatskanie has led to partially treated wastewater discharges into the Clatskanie River on the west side of town.
A statement released to the media by the City of Clatskanie Sunday, Sept. 1, said a sweep arm failed at the wastewater treatment plant and partially treated sewage is being intermittently discharged.
The Oregon Department of Environmental Quality (DEQ) was notified of the situation and is advising city officials to help address the problem. City Manager Greg Hinkelman said it was the first time the sewer plant had suffered a failure of this nature.
The breakdown in the secondary clarifier was discovered a few days prior to the statement’s release. A gearbox was initially suspected as the culprit and was replaced, but when the sweep arm was reactivated it still did not work. It’s now believed there was a gear failure related to the sweep arm’s worm drive.
As the plant neared wastewater capacity over the weekend, it was decided that a discharge of partially treated sewage was necessary. DEQ also issued emergency permits for the City of Clatskanie to dump treated sludge from the secondary clarifier in a field that is already approved for that purpose. And the smaller primary clarifier at the plant was reactivated to create additional capacity and for treatment purposes.
The company that built the sweep arm is being brought in to determine the exact problem and rebuild the sweep arm. A new unit has been ordered for when the rebuilt arm needs replacing, possibly in a few years. The company’s arrival is slightly delayed by hurricane response efforts on the East Coast, the city manager said.
Hinkelman said he expects another discharge to the river will be necessary in the coming days. He said it’s possible the discharge would be at or near compliance standards thanks to the relentless efforts of the public works director and crew at the wastewater treatment plant. He could not immediately say how much partially treated wastewater has been discharged.
DEQ has not taken any action against the City of Clatskanie regarding the mechanical failure. Hinkelman praised the agency for its understanding of the issue. He emphasized that the discharges were partially treated and were not raw sewage and were caused by a malfunction rather than any negligence.
During the Wednesday, Sept. 4, Clatskanie City Council meeting, Public Works Director Dave True said from Saturday through Monday there were intermittent discharges of effluent that did not meet permit standards. He said the broken-down clarifier was drained and inspected, and an alternate treatment method was temporarily established.
“That sweep arm is probably the most important piece of mechanical equipment out at the plant” True said. “We’re not redundant, and that’s a problem because we can’t switch to one side to work on them, we just have to set up an alternative treatment scenario that will probably have to be manned 24-7.”
The estimated cost to repair the mechanical failure is $60,000-$75,000. True said there are several funding options and suggested possibly dropping a paving improvement project or requesting a supplemental budget allotment.
True said discharges would likely resume later this week and hopefully they will meet permit requirements. True and Hinkelman spoke highly of the work done by the public works crew, who have been scrambling since the mechanical failure was discovered. True said it’s possible the plant would be back up and running by next Thursday.
Signage will be posted at the boat ramps in town to make the public aware of the potential health risk in the water. Exposure to sewage that has not been fully treated could cause a number of illnesses.