City says sewer odor under control – for now

Sean C. Morgan

Of The New Era

New equipment at the Sweet Home wastewater treatment plant has been raising a stink around town since the weather started warming up this year.

In the last couple of weeks, the city has temporarily addressed the problem and will look at a more long-term solution.

The city has received complaints about the wastewater treatment plant smelling now and then at different parts of the year, Public Works Director Mike Adams said. Around April, city officials started getting more constant complaints from more people.

“As it got warmer, we started experiencing it more and more,” he said. “It became apparent that the (equipment) change-out was the primary cause.”

At the end of last summer, the city replaced the device used to aerate water and solid waste in what is called the “digester,” a tank that helps separate wastewater from solid matter. The device used to physically stir the water at the top of the pool. The new gear blows air through the water from below, giving better aeration throughout the digester.

The digester is a function later in the treatment process. Solid, granular, sand-like waste is settled out of the wastewater. The waste is then pressed, squeezing excess water from it before it is taken from the treatment site.

The Department of Environmental Quality approved the new equipment, and it was installed prior to OMI taking over management of the facility, Adams said.

The old “mixer” created a type of vacuum lock over the digester pool, Adams said, sort of like an invisible lid. The new aeration device, which injects air into the pool, does not. At the same time, the old equipment didn’t mix the pool as well the new equipment.

The smell started becoming noticeable when weather started warming up, he said. The city and OMI have tried different ways of keeping the smell down, including shutting down the digester temporarily and trying to find a good time to run it. But that only made the smell worse.

About a week and a half ago, they covered the digester with black plastic taped to a cabling system, Adams said. Since then, he has talked to neighbors and those who have had complaints or concerns, and it seems to have worked.

This is a temporary solution, he said. Long term, the city most likely will want to cover it permanently somehow.

The DEQ wants the city to make some changes to the digester for other reasons, Adams said. They may include structural changes. Once the city finds out exactly what the DEQ wants done to the digester, the city can figure out how to cover it.

At this point, the city does not have any estimates on a permanent cover, which also will depend at some level on what changes need to be made, he said.