Sean C. Morgan
Of The New Era
The city of Sweet Home and OMI, Inc. are doing what they can to keep down the odor from the wastewater treatment plant.
Earlier this summer, after several complaints about odors, officials covered the wastewater plant’s “digester” with black plastic.
“It killed a lot of it,” OMI plant operator David Jendro said. “It made a 1,000-percent difference.”
The plastic, taped over the top of the digester, held for probably two or three weeks, he said, and then started coming apart.
About three weeks ago, OMI put a tarp over the digester and tied it down, Jendro said.
After determining that covering the digester would work, “we got something a little more substantive,” Operations Manager Doug Atkinson said. OMI also sprays deodorizers into the air around the plant.
The tarp doesn’t keep the odor down completely, Atkinson said, but “putting the tarp over it, as far as I’m concerned, it’s 10 times better than what it was.”
But about two weeks ago, the odor flared up again on several different days.
That week, the plant needed an emergency repair in the aerator, Atkinson said. The downtime for the repair caused more odor and threw the plant and its microbes, used in the treatment process, out of balance, also causing odor.
That said, the tarp over the digester doesn’t keep all of the odor down, he said. When the wind dies down, odor collects around the plant and then travels along the railroad tracks and areas close to the plant.
Atkinson regularly drives around to check the odor problem, he said. He has found that at different times it can be detected in different places at different strengths.
“We don’t have a lot more we can do,” Atkinson said. “We blow deodorizer toward the trees. Hopefully, it gets to town.”
In the meantime, the city has an engineer working on problems with the digester, he said. It is not meeting regulatory requirements, and the city has had to stop using the solid waste from the digester on farm lands as a result. Instead, it must send the solids left behind in the process to a landfill.
The engineer is working on that problem along with the odor problem, Atkinson said.
The digester is not properly a “digester,” he said. It is actually a “sludge-mixing tank.”
In the past, it had mechanical arms that rotated in the pool of water and sludge.
That created an invisible trap that held odors in check, Atkinson said. The city replaced that mixer with a sub-par aeration system, more of a diffuser, which pushes air through the sludge at the bottom of the tank and releasing odors.
“I want people to understand we’re not sitting here doing nothing about it,” he said. “We’re really doing what we can to keep the odors from getting out of here.”
OMI also anticipated Jamboree weekend and worked ahead of time to reduce the waste levels being treated in the plant to minimize odors during the event, Atkinson said.