Officials vow 'tough questions' after odor release from Marathon refinery

Shawn D. Lewis
The Detroit News
According to state officials, Marathon plans to shut down the refinery "in the coming days to make repairs to the coker flare gas system."

Detroit — Residents impacted by the rotten odor emitting from the Marathon oil refinery drifting over southwest Detroit over the weekend were not in danger, according to state and city officials

“The levels indicated with handheld monitors and permanent stations were far below anything that would pose a health or safety risk,” said Paul Max of the city of Detroit’s Buildings, Safety Engineering and Environmental Department on Monday.

According to the Michigan Department of Environmental Quality, the sources of the odor created by a problem with the refinery's flare gas system are suspected to be hydrogen sulfide and mercaptan compounds. Both of these compounds have extremely low odor thresholds, meaning they can be smelled even at very low levels.

The DEQ issued a statement Monday, saying it “continues to coordinate with EPA and the City of Detroit on air monitoring and response activities related to the malfunction of the coker flare gas system and resulting odors from the Marathon refinery in Detroit.”

The DEQ, City of Detroit and federal Environmental Protection Agency staff met with Marathon personnel at the refinery Monday. They were briefed on steps taken to "reduce and reroute gas normally combusted by the flare system in an effort to reduce the rotten egg odors being emitted from the refinery."

Apart from the odor, neither EPA’s nor Marathon’s air quality sampling "have detected any exceedances of health thresholds,” the statement says. “DEQ’s Air Quality Division is reviewing monitoring data from DEQ’s own ambient air monitoring stations in the area in addition to reviewing the Marathon data.”

According to the DEQ, Marathon officials plan to shut down the refinery "in the coming days to make repairs to the coker flare gas system."

According to Marathon Petroleum Corp., owner of the site since 1959, the flares "are safety devices that allow (Marathon) to safely combust excess materials at the refinery," the company said. It is working to deactivate the flare "as quickly and safely as possible."

Steve Considine, a National Weather Service meteorologist, said that winds were blowing from the west on Sunday, about five to 15 mph hour. Odors would travel north and northeast of the source.

Meanwhile on Monday, Max responded to questions about the odor from members of the city's Public Health and Safety Standing Committee.

“Marathon sounded a siren, and they called Homeland Security, but I don’t know if they notified the surrounding area,” Max said.

But residents, he said, were not in danger.

Dale George, a spokesman for the Homeland Security & Emergency Management Division of the Michigan State Police, confirmed the department was contacted over the weekend concerning the flare at the refinery. 

"Marathon is making the necessary repairs and continues to monitor the air quality," he said. "Ongoing air monitoring has not detected dangerous levels of any substances."

The division, George said, "continues to monitor the situation," but "there have been no requests for state assistance at this time."

Councilman Scott Benson, the committee's chairman, who, along with other committee members, said he Monday was “satisfied our staff is monitoring the situation since we don’t have regulatory authority.”

He said this means the measurements were 1,000 times lower than measurements at a harmful level.

“It’s unfortunate this happened, and we’re looking forward to know how to keep this from happening again,” he said.

Benson said “tough questions” will be asked of the DEQ and the EPA during a 10 a.m. Tuesday meeting.

“We will be asking about notification measures, as well as what we are doing to ensure Marathon has the lowest negative impact on residents in the area.”