A chain of miscommunications resulted in the sulphur or rotting meat smell that has hung over Monett for the past week.
City officials were hopeful the odor issue, which began at the Tyson Foods plant, would dissipate in the near future.
The problem started Friday at the Tyson Foods feed mill in Aurora. A holding tank for the liquid feed product Alimet, added to help chickens absorb protein more effectively, developed a leak. Tyson personnel sealed the leak, mopped up the spill and decided to ship the spilled liquid to Monett for disposal at the wastewater pre-treatment plant.
In the first miscommunication, the feed mill failed to alert the Tyson pre-treatment plant of the shipment. Then, according to sources with the city, the truck driver delivering the Alimet misrepresented what he was hauling, telling the the pre-treatment plant operator that he had animal fat, a typical material for the plant to process. After about 20 minutes of unloading, the operator halted the process, realizing the material was not animal fat. He called Becky Thomas, Tyson's pretreatment operator, who ordered the rest of the load to go into storage for handling on Monday. By then, an unknown quantity of Alimet had entered the system.
In the third miscommunication, no one contacted the city waste treatment plant of "a chemical spill," the inflow of an unexpected substance into the sewer system. According to David Sims, chief wastewater operator for the city, industries as a matter of course are supposed to alert the city's plant of any unusual material. The plant can divert spills into the holding lagoon for separate treatment. Industrial discharges usually take about 20 minutes to reach the city treatment plant.
Some time later, the night operator at the city plant became aware of an odor, and began checking industries to discover what had happened. The search led to Tyson and ultimately the discovery of the chemical.
The Material Safety Data Sheet on Alimet indicated the compound has a very low pH balance. Sims worried the substance could kill off the bacteria colony that treats the city's effluent. Repeated checks throughout the week showed no damage to the biological integrity of the city's operation.
"So far, the plant is in compliance. We just stink," Sims said. "In 36 years here, this is a new one on me."
Skip Schaller, utilities superintendent, said, "Tyson has been working diligently on their end trying to add something with chlorine to control the odor. They've also been adding caustic material to get the pH up. We're making double and triple checks to make sure our plant is still working properly."
Sims checked with engineers at Allgeier, Martin and Associates, who designed the plant, who confirmed the city had done all it could to relieve the odor.
"I wish we could spray deodorant and clear it up," Sims said. "Unfortunately, we have millions of gallons of water at the plant. We just have to monitor it, make sure we're hanging in there and answer the phone."
Thomas spent Thursday at the Tyson feed mill in Aurora.
Worth Sparkman, public relations manager for Tyson Foods, said, "Our wastewater pre-treatment facility in Monett is working to treat a contained spill of a feed ingredient that occurred at our Aurora feed mill. After pre-treatment at our plant, the water then moves to the city of Monett's wastewater treatment facility. Once the water moves from our pre-treatment facility, the smell associated with the ingredient should dissipate; we're working with the city to process the water as quickly as possible to reduce odor.
"The ingredient has an odor that can be unpleasant, but it's not harmful to residents."