SIOUX CITY -- The city of Sioux City has cited Big Ox Energy for multiple violations of its permit to discharge sewage into the city's regional wastewater treatment plant.
Since issuing a compliance order in late June, the city has fined the South Sioux City biofuels plant $3,500 for exceeding its discharge limits and failing to reports all of its daily flows into the treatment plant, according to a notice of violation mailed Tuesday to the company.
The order dated Tuesday gives Big Ox 10 days to provide a written explanation of each violation and a plan for correcting the deficiencies. City officials said they also will contact the company to set up a meeting.
"Big Ox Energy continues to invest in upgrading its wastewater treatment capabilities and is operating in full compliance with its permit from Sioux City," company spokesman Kevin Bradley said in a statement Thursday night.
It's the latest legal troubles for the Big Ox plant, which converts organic waste from local industries into methane gas that's sold for commercial use.
The $30 million plant has been beset by problems since it opened in the fall of 2017. Soon afterwards, residents of a South Sioux City neighborhood began complaining of putrid odors entering their homes through a sewer line the neighborhood, at the time, shared with the plant and other industries in the Roth Industrial Park.
More recently, Big Ox has battled recycling digester issues that sent sludge spilling out the top of its digesters and onto neighboring property.
The Sioux City order issued Tuesday shows the city on July 13 issued a "cease and desist order" against Big Ox, requiring the plant to halt discharges no later than 5 p.m. July 18 due to ongoing violations of its Total Suspended Solids, or TSS, into the city's collection system.
On Aug. 2, the city issued a notice requiring the company to submit daily reports that include the plant's previous day's flow. Since that edict went into effect, the company allegedly has failed to issue 4 samples, resulting in a $500 daily fine for each violation, or a total of $1,500, according to the document. Future reporting violations will be increased to $1,000 per day for each violation.
On Sept. 3, Big Ox also allegedly failed to notify the city of a sludge discharge, resulting in an additional $1,000 penalty. The same day, the company allegedly discharged about 60,561 pounds of TSS, which exceed the maximum daily limit of 48,509 pounds, as agreed to in the compliance order dated June 29. That resulted in another $1,000 fine, bringing the current total to $3,500.
In August, the Nebraska Department of Environmental Quality sent the South Sioux City plant a letter, alleging it had failed to control emissions of hydrogen sulfide, properly operate and maintain anaerobic digesters, control dust from leaving the property and submit proper notifications. It was the third notice of violation issued to Big Ox since mid-June in relation to digester upsets and emissions issues at the facility.
The facility and the NDEQ entered into a consent order July 30 that will resolve the first notice of violation and an associated emergency complaint and order. Big Ox has agreed to use measures to cease the discharges at the facility and continue cleanup efforts, repair equipment and decrease the risk of future upsets.