Owners of a gas station in southeastern Minnesota ignored their leak detection alarm for more than a month as thousands of gallons of gasoline seeped into the soil, contaminating the city's water system and a nearby trout stream, according to a lawsuit filed this week by state investigators.

Minnesota Pollution Control Agency inspectors said Tejinder Singh and Gurek Inc., owners of a Cenex gas station, hit the alarm's reset button so often — every day for 41 days — that the site's detection equipment broke.

More than 10,000 gallons of gasoline leaked from the station's pipes between January and March 2022. It was discovered after a resident smelled gas from a sewer near the station. The state sued Singh and Gurek in Olmsted County District Court seeking to recoup the more than $1 million it has already spent cleaning and investigating the spill. The city will also need to replace damaged and contaminated water lines.

The size of the leak is significant, said Darin Broton, MPCA spokesman. And its location — in a karst region with porous soil — makes it particularly damaging, he said.

"This owner acted egregiously," he said.

Singh didn't return phone calls or emails seeking an interview.

The state began cleaning the site after the leak was discovered, excavating more than 3,000 tons of soil saturated with gasoline and installing monitoring wells.

The Cenex gas station had a leak detection system designed to automatically shut down pumps if they failed a test for 30 straight days, according to the complaint. The station's system shut down a pump Jan. 15, 2022, the complaint said.

Rather than investigate or report the potential leak, owners of the station reset the system each day to turn the pump back on, MPCA investigators said.

In October, after the cleanup process was already several months underway, a resident at an apartment across the street smelled gasoline coming from a faucet. The contamination plume had infiltrated the city water line that supplied the complex. The state provided the residents of the apartment and a nearby house bottled water for about a month, and recommended that those residents limit showers and keep their windows open when running water. In mid-November the state installed water filtration systems at both sites.

Gasoline from the spill was also found in a nearby trout stream, but no fish kills were reported.

The MPCA believes it has removed about half of the leaked gasoline — more than 4,500 gallons. The remaining plume of pollution is volatile, and could move or expand as groundwater levels fluctuate. Drinking and surface water is still at risk. Vapors could also rise from the leaked gasoline into basements and lower floors of nearby buildings, including the apartment complex and Elgin City Hall, which are across the street from the station, and six nearby homes.

In addition to reimbursement for cleaning and monitoring the site, MPCA officials are also seeking legal fees and penalties of up to $25,000 per day of alleged violations. City officials believe they will finish replacing contaminated water pipes by the end of the year.

Monitoring and further cleanup efforts are ongoing, Broton said.

"We know we're going to have to manage this site for years," he said.