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Marathon Petroleum, former St. Paul Park refinery owner, paid $700K penalty for benzene release

The former owner of the St. Paul Park oil refinery paid a $700,000 civil penalty for failing to properly treat wastewater containing the chemical benzene, the Minnesota Pollution Control Agency said Thursday.

Marathon Petroleum Co. illegally disposed of nearly 115 million gallons of wastewater containing benzene into an unprotected lagoon rather than removing the benzene at its wastewater treatment plant, the MPCA said. The lagoon is on refinery property near the Mississippi River.

The company said the wastewater contained the equivalent of 128 gallons of pure benzene. Marathon paid the $700,000 penalty in November as part of an agreement with the state agency.

"It is a high penalty and it reflects the fact that the agency had a number of concerns with Marathon Petroleum about how they were handling their hazardous waste," said Sam Brungardt of the MPCA. "And then Marathon Petroleum basically continued to dispose of it in a manner that is not legal."

The company failed to properly manage wastewater off and on for 65 days between mid-June and mid-October of 2010, according to the MPCA.

Marathon spokesman Shane Pochard said in an interview Thursday that the benzene release was the result of a power outage and "mechanical failures."

"After that happened, additional preventative controls were put in place," he said.

Brungardt said the refinery's wastewater treatment plant is supposed to contain micro-organisms that remove chemicals such as benzene before water is discharged. In this case, however, that was not occurring before the water containing benzene was disposed in the unlined lagoon, located near the Mississippi River.

"Their bugs died," Brungardt said of the micro-organisms.

It is not clear how much, if any, benzene leaked from the lagoon.

Benzene is a petroleum product, so it could have evaporated into the air or contaminated shallow groundwater, Brungardt said. The groundwater is "hydraulically connected to the river," according to the MPCA.

Pochard said routine company testing following the benzene release showed there was "no evidence of any impact outside the refinery itself," including in surrounding groundwater.

Marathon sold the refiner in December 2010 to Northern Tier Energy.

Check back for updates to this story.

Scott Wente

Scott Wente has been editor at the South Washington County Bulletin since 2011. He worked as a reporter at other Forum Communications newspapers from 2003 to 2011.

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