Illegal dumping blamed for noxious odor at wastewater treatment plant; restoration work in progress

One of the damaged tanks shows the water color that indicates bacteria die-off.

Possible illegal dumping of an unknown substance into one of the city’s sewer manholes has damaged two of the sequencing batch reactors at the wastewater treatment plant.

The two tanks are being reseeded with bacteria to bring them back into balance. As of Aug. 3, the alkaline levels were beginning to fall.

According to Darrell Curtis, supervisor of the wastewater plant, that's one of the early signs the tanks are beginning to recover.

David Lindsey, plant foreman, said the color of the water in the tanks is an indicator of the unit's health.

“[The water in] this [healthy] digester is kind of a grayish, barely brown color,” said Lindsey. “This one over here [one of the damaged tanks] is like a dark chocolate color.”

The odor from the damaged tanks is noxious and the healthy one produces a more earthy smell. Slowly but surely, said Lindsey, the systems are coming back online.

“It takes time with these systems, sometimes weeks if not a month to get back fully to normal,” said Lindsey. “We are seeing some of our parameters [indicating tanks are coming back into balance] coming back around.”

Ed Brocksmith, a Tahlequah resident and Save The Illinois River Inc. founder, drove along Town Branch from the city park after smelling a bad odor. He reported he didn’t see any problem until he got to the plant.

“The creek below looks like raw sewage and the creek above looks clear,” said Brocksmith. “How many millions of gallons of raw sewage were released that makes its way to the river?”

No raw sewage has been released into the creek, said Lindsey.

“We’ve never had raw sludge come out. The basins that are sick will produce kind of a milky, slight tint to the water, but that’s not sewage,” said Lindsey. “Everything gets filtered and gets put through the UV for disinfection. So everything is treated. We want that river as clean as we can get it, just for the fact that we have our kids that swim in it."

The Oklahoma Department of Environmental Quality is being kept in the loop. In a letter to the department, Curtis informed them the systems are improving.

“We are still experiencing elevated results on our ammonia, coliform, and BOD [Biochemical Oxygen Demand], but they should begin to fall as we establish a health level of bacteria in the basins,” Curtis said.

Local law enforcement and city storm water system personnel have been asked to be on the lookout for anything or anyone suspicious around any of the sewer manholes. Residents are asked to call the police department if they see anyone who isn't a city employee accessing a sewer manhole . City employees will be in uniform and driving orange trucks.

Curtis said the same kind of incident happened back in April.

“We suspect it’s probably one of those grease trap recovery people who isn’t paying for proper disposal,” said Curtis. “It [bacteria die-off] happened so fast that it’s got to be a pesticide or petroleum product.”

The tanks can be turned off for days at a time and the bacteria doesn’t die, said Curtis. Even if the tanks were mismanaged, it would take months to die, not three days.

“This killed them [bacteria] in three or four days,” said Curtis.

Lindsey said there are so many manholes in the city it is almost impossible to trace where it came from.

“We are communicating with TPWA [Tahlequah Public Works Authority] and ODEQ is investigating and correcting the issues at the sewer plant,” said Taylor Tannehill, city administrator.

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