SIOUX CITY -- As the court case against one former Sioux City wastewater treatment plant worker begins, plant supervisors continue with new oversights and improvements aimed at preventing a repeat of the activities that resulted in numerous violations and potential state action against the city.
"I think we've got a lot of safeguards in place to keep people on their toes," city utilities director Mark Simms said.
Patrick Schwarte, a former shift supervisor, is expected to plead guilty Wednesday in U.S. District Court in Sioux City to criminal charges connected to his role in an alleged conspiracy to manipulate water sample test results and use fraudulent testing procedures to ensure the plant's discharges into the Missouri River met federal guidelines.
The Iowa Department of Natural Resources, which administers the plant's federal permit, was tipped off to the activity, believed to have happened from 2012 to June 2015.
Since the manipulation was discovered in June 2015, the DNR has issued the wastewater treatment plant 15 citations, none of them rising to the seriousness that led to the criminal charges, said Tom Roos, environmental specialist senior at the DNR's Spencer office.
"Looking at this list, it's not a recurring thing. Ninety-nine percent of the time they do a great job," Roos said, adding that he has no concerns with the plant's operation.
The DNR has not increased scrutiny of the Sioux City plant, Roos said. Like any wastewater treatment plant operator, Sioux City is required to sample wastewater once a day to test the levels of chlorine, ammonia, suspended solids, grease and numerous other chemicals and compounds and submit a monthly report to the DNR.
Simms was hired as utilities director in September 2015 and was not with the city when the violations at the center of the legal actions took place. For the first two months after his hiring, he said, samples were taken two or three times during each of the three shifts at the plant. Testing has since been reduced to once per shift, meaning the city is still testing three times a day, above the DNR's requirement of one daily sample.
Samples are tested by different workers rather than a single person, and once results are entered into a computer, a second worker reviews and verifies them, Simms said.
The city also has provided workers with additional training, and five or six plant workers have reached the DNR's highest licensing level. A recent engineering study has led to plans for upgrades to the plant's disinfection system, Simms said.
Treating wastewater is a complex process, Simms said, given the amount of industrial waste from food processors that Sioux City's plant receives. Built in 1961, the plant, located at 3100 S. Lewis Blvd., each day receives industrial, commercial and residential wastewater from Sioux City, Sergeant Bluff, South Sioux City, North Sioux City and Dakota Dunes. Cleaned and treated water is discharged into the Missouri River in accordance with state and federal regulations.
With a number of food processors and other industries in the metro area, Simms said the challenge is to maintain a consistent wastewater flow into the plant. If it's too high or too low, it can disrupt the naturally occurring bacteria that break down the waste, making it harder to treat and disinfect.
If one of the plant's larger wastewater contributors discharges a higher-than-normal amount of waste into the system, it can throw off the balance, making it hard for the bacteria to adjust and defeating workers' efforts to treat the waste to meet acceptable limits.
"With the volume of waste this facility receives and the number of industrial contributors and commercial contributors and the complexity of the system, it's a difficult job," Simms said.
The city's 15 violations in the past three and a half years include seven instances of high levels of chlorine, three of ammonia nitrogen, two of suspended solids and three for oil and grease.
Seven of the violations occurred in 2018, and Simms said the city identified the source leading to most of those violations. The city ultimately fined Big Ox, a South Sioux City industry that converts organic waste from local industries into methane gas, for numerous violations of its wastewater treatment agreement with the city.
Roos said other Iowa municipalities have violations occasionally, and he's not concerned with the number Sioux City's plant has been issued.
"Sioux City is pretty unique with the industries they have. They have to adjust for that, and wastewater doesn't adjust very fast," he said. "We always strive for zero violations, but things happen."
Simms said the city's additional steps have prevented a repeat of the actions of Schwarte, former plant superintendent Jay Niday and potentially others.
No other individuals have been charged, though court documents and a 2015 DNR investigation show that Niday and four other unnamed plant workers were involved. Simms said he did not know if those four workers were still at the plant, and he did not want to speculate on the actions that occurred before he was hired.
The DNR found that Schwarte and others were raising chlorine levels on days that samples were taken so that the city would meet permit guidelines and then lowered the chlorine to minimal levels on other days. Schwarte and Niday were fired, and both surrendered their state wastewater treatment licenses.
In June 2016, the Iowa Environmental Protection Commission referred the DNR's case against the city to the Iowa Attorney General's office for consideration of civil penalties higher than the DNR, whose penalties are capped by state law at $10,000.
The city's attorney has maintained that Schwarte's intent to plead guilty is not proof of wrongdoing by other city employees or officials, and it doesn't mean that the city could be subject to civil penalties handed down by the U.S. Environmental Protection Agency. Because of the ongoing partial federal government shutdown, the EPA and U.S. Attorney's Office have suspended media communications as nonessential functions and those offices could not comment on whether fines or criminal charges against other plant workers are anticipated.