SOUTH SIOUX CITY -- Big Ox Energy has ceased all operations at its South Sioux City biofuels plant after its permit to discharge wastewater to Sioux City's treatment plant expired Tuesday.
The shutdown comes less than two weeks after the Wisconsin-based company announced it was temporarily suspending its biogas production operations, leaving only its wastewater treatment operations.
The City of South Sioux City closed valves into and out of the plant at 11:45 p.m. Tuesday.
"Essentially, the plant is now completely shut down," said Kevin Bradley, Big Ox director of business and economic development.
Bradley said Big Ox had hoped to negotiate an extension with Sioux City, but an agreement has not be reached.
In addition to wastewater from its own production process, in which the plant accepted organic waste from local food and beverage manufacturers and converted it to methane, Big Ox received wastewater from other South Sioux City industries, pretreated it and discharged it to Sioux City's regional wastewater treatment plant on the other side of the Missouri River. That wastewater is now bypassing Big Ox via a sewer main South Sioux City installed in 2017, Mayor Rod Koch said.
Wastewater will not flow through Big Ox until a new permit is issued by Sioux City, he said.
A number of issues must be resolved before that can happen, assistant city attorney Justin Vondrak said. Chief among them is more than $3 million Big Ox owes in unpaid wastewater treatment fees, fines and late charges.
"We have never said we will not reissue a new permit," Vondrak said. "What we have said is there are outstanding issues that need to be resolved before the city reissues a permit."
Big Ox is disputing Sioux City's charges, many of which resulted from the discharge of higher volumes of wastewater with high concentrations of pollutants and suspended solid waste late last year and early this year. Those discharges pushed Big Ox into a higher rate tier, resulting in higher bills from Sioux City.
Bradley said those charges are the key issue to the permit renewal. Prior to the April 19 shutdown, plant operations had stabilized and Big Ox had dropped out of the higher rate tier.
"The discharges over the last couple months have been well, well within our permit limits," Bradley said.
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City billing records show that Big Ox owes a balance of a little more than $3 million. Big Ox claims the city has not incurred all the costs it has charged the company.
Vondrak said the two sides will continue to work on a solution.
"The lines of communication are open," he said.
Meanwhile, South Sioux City has resumed the task of pumping wastewater from the Roth Industrial Park to Sioux City. Koch said industries in the park were aware the change was possible and their operations were not disrupted. The change will not affect South Sioux City utility rates or its residents, Kock said.
City manager Lance Hedquist said wastewater from the industrial park would not be discharged through a line beneath a neighborhood in which residents had experienced sewer backups and noxious fumes after Big Ox began operations in September 2016. Those emissions and odor issues have led to more than a dozen lawsuits filed against Big Ox and the city by homeowners in the plant's vicinity who claim its odors are a nuisance and, in some cases, have caused health issues and made their homes uninhabitable.
The plant has been cited nine times by state and federal regulators for environmental violations, most recently on April 2 after a Nebraska Department of Environmental Quality inspector cited the company for failing to control emissions after he noticed gases leaking from a damaged anaerobic digester structure. Big Ox has had problems with repeated venting of hydrogen sulfide gas into the atmosphere and solid waste spills.
When the company announced its plan to temporarily suspend its biogas production operations, Bradley said plant operators would empty the digesters in order to make repairs that the company hopes will solve the emissions and odor issues.
Bradley said Wednesday that the digesters should be empty this month. There is no time line on when the plant could again be operational, he said.
The resumption of operations also depends on getting a wastewater permit renewal from Sioux City.
State regulators will have a say as well. The NDEQ has called Big Ox to appear in Lincoln later this month to justify why its storm water and air quality permits shouldn't be revoked.
Bradley said it's hoped that Big Ox can resolve its disagreement with the city, repair its facility and resume operations.
"We really want this facility to find success in the long term and that continues to be our goal," he said.