Waste water bacteria gorged on grease, got out of control

May 10, 2017 GMT

The “gooey nightmare” that overwhelmed Butte-Silver Bow’s waste water treatment plant in early April overindulged on grease, possibly bacon grease.

The brown, sponge-like foam that bloomed so badly that the plant had to shut down for six hours is “uniquely good at eating” fatty oils and grease, said Matt Moore, treatment plant operator.

Bacon grease, he added, is a significant problem for Butte’s waste water treatment plant.

“It’s worse (here) than other cities,” he said.

County workers broke a “huge grease dam” around Montana Street and Josette Avenue on March 29 that had been plugging the sewer line. Once those chunks of grease made their way to the treatment plant on Centennial Avenue, the brown bacteria inside the plant engorged itself and bloomed out of control.

The foam grew so large workers opened the plant doors to let the bacteria, which looked like something out of the 1988 Hollywood horror movie “The Blob,” roll out.


The event led the treatment plant to release 550,000 gallons of partially treated waste water into Silver Bow Creek on April 6. Waste water still traveled through an ultra violet treatment, which eliminated E. coli bacteria, before it reached the creek. E. coli would have been the Department of Environmental Quality’s greatest concern, DEQ spokesperson Kristi Ponozzo said previously.

Moore said that now that county workers are aware of this new potential type of havoc, they will take greater care in trying to prevent grease from getting through the sewer line. Moore said the new waste water system is a “closed system,” so the bacteria, which exists in all such treatment plants, “now has no place to go” when it grows.

Schultz said county leaders will likely start talking about enacting a stricter ordinance which addresses what goes down the drain. Any such ordinance would need council approval, Schultz added.

While what residents drain can’t be enforced, what restaurants send down the waste pipe can.

Moore and Schultz said that other cities have stricter ordinances that prevent restaurants from sending fatty oils and grease down the drain. Restaurants need to have a grease trap, which is smaller than an individual septic system, said Schultz. But it captures a restaurant’s waste water, including the grease, before entering the county’s sewer system.