A fire at an auto body and repair shop in Orr, Minn., could have had a significant effect on the city’s wastewater treatment facility and the water it discharges, if not for the two quick-thinking waterwater treatment operators.
Early in the morning of Sept. 23, 2019, fire engulfed an auto body and repair shop in Orr (pop. 282) in northern Minnesota. Firefighters arrived and were able to keep the flames from spreading to an adjacent motel, but the shop was a total loss. In the burned building, hundreds of gallons of used oil and firefighting foam and water ran into floor drains and into Orr's sanitary sewer system.
By 8 a.m., Paul Koch, Class B certified wastewater operator and maintenance supervisor, and Rocky Hoffman, assistant maintenance worker, had identified oil entering the Orr wastewater treatment plant. They shut off the main lift station pumps to reduce impacts to the plant, called the Minnesota Duty Officer to report the possible plant upset, and then contacted MPCA emergency response and wastewater staff to determine next steps.
Paul and Rocky knew that automorive oil in large amounts could overwhelm the wastewater plant processes. Wastewater treatment depends on microbes and biological processes to break down waste, and the oil could harm microbes and significantly disrupt treatment processes. It's possible the oil could have passed through the system and ended up fouling the plant's discharge.
By early afternoon, an environmental contractor had delivered a 20,000-gallon tank, called a frac tank, to the plant and a local septage hauler was on-site pumping liquid from the main lift station and skimming oil to the frac tank. Over the next two days, about 18,000 gallons was pumped to the frac tank. Absorbent booms capable of absorbing oil were placed within treatment components as well as at the plant’s outfall to a ditch to the Pelican River.
Firefighters had used a Class A fire suppressant foam that the manufacturer reported as having no PFAS (per- and polyfluoroalkyl substances) compounds. Sampling of wastewater in the frac tank showed that pollutant concentrations were acceptable for treatment at the wastewater treatment plant. Over a week-long period, the wastewater was discharged to the plant for treatment. The oil layer in the frac tank was pumped to six 250-gallon totes and one 55-gallon drum for incineration in Memphis, Tenn.
Koch and Hoffman conducted the monitoring required by their wastewater permit twice during the next two days following the fire. (They usually sample only once a week as required by the city’s permit). The results indicated no plant upset, with monitoring results just after the fire being similar to results prior to the fire. The plant reported no effluent limit violations for the month.
“The City of Orr, and especially its wastewater operator and maintenance worker, did commendable work responding to the incident and minimizing impacts,” said John Thomas, MPCA compliance officer.
This was especially true because Koch responded to the emergency while recovering from knee surgery. He coordinated the response while on crutches or from a wheelchair.
“This is another example of small town wastewater operators rising to the challenge of keeping systems operating, even in the worst of times,” Thomas said.