Flat Rock’s second chemical spill points to hazards of underground tanks

More than a week since anglers in the Huron River discovered Flat Rock’s second major chemical leak in less than a year, investigators believe they may have found a culprit: A nearly century-old underground storage tank located about 50 feet from the water.

Excavation crews uncovered the tank earlier this week, after a vent pipe and valves in the basement of a metal factory adjacent to the river tipped off EPA investigators to the presence of a long-forgotten fuel tank at the site.

An historical marker at the property lauds its former life as a lamp factory for Ford Motor Company. The underground storage tank likely dates back to those days, according to a federal regulator. 

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“It might have been put down there in the late 1920s,” said Sean Kane, an EPA scene coordinator in the Flat Rock investigation.

This is the second time in six months that a leak tied to an underground storage tank associated with Ford has befouled Flat Rock. Underground leaks are a persistent problem across the nation, where buried fuel tanks — many of them old, inoperative and forgotten until they cause a problem —are responsible for thousands of leaks every year.

Crews had been searching for the sheen’s source since Feb. 21, when anglers noticed an oily substance bubbling up to the surface on a Huron River back channel near downtown Flat Rock. 

Local fire crews quickly placed booms in the river to contain the leak. State and federal response crews have been working ever since to uncover the leak’s origins and find a way to stop it.

The leak continues, but vacuum trucks are onsite sucking the chemical out of the river to prevent further spread. Air monitoring in nearby neighborhoods has detected no volatile organic compounds or benzene gasses, Kane said.

Kane said the site’s current owner, Flat Rock Metal, is cooperating with the investigation and hired the crews that ultimately uncovered the storage tank, which had previously been unknown and unused. Company officials did not respond Wednesday to a phone message from Bridge Michigan. 

EPA officials have not ruled out the possibility of a leak from another source, Kane said, and have identified “multiple investigation plans” they will pursue if the Flat Rock Metal property turns out not to be the source.

But at the moment, that appears unlikely: The underground tank contained about 6,000 gallons of water and chemicals — a sign that it is not watertight. The soil surrounding the tank was oily, too. And the tank is located within 50 feet of the stretch of river where the sheen appeared.

“You can put two and two together there,” Kane said.

Investigators sent samples of the Huron River chemical and the storage tank’s contents to a U.S. Coast Guard lab, and are awaiting analysis that will reveal whether the substances are a chemical match, said Jill Greenberg, a spokesperson for the Michigan Department of Environment, Great Lakes and Energy (EGLE).

Results are expected this week.

Leaks from aging and abandoned underground storage tanks are a sizable problem across the country, often lying forgotten underground until they leak. 

The EPA began regulating underground storage tanks in the 1980s. But an unknown number of forgotten older tanks remain underground, many of them made of unlined steel susceptible to corrosion. 

Approximately 5,000 leaks from underground storage tanks annually have resulted in a nationwide backlog of more than 60,000 that have yet to be cleaned up. State and federal regulators have made a push in recent years to identify and remove them, EPA spokesperson Taylor Gillespie said, reaching the milestone of 500,000 cleanups in December.

The state Department of Licenses and Regulatory Affairs oversees underground storage tanks in Michigan. A LARA spokesperson could not be reached for comment Tuesday or Wednesday. 

A leak associated with another underground storage tank was the source of a gas leak last September that forced hundreds of Flat Rock residents to evacuate their homes for more than two weeks.

In that instance, fuel from a pipe leading to a fuel tank at the Ford Flat Rock Assembly plant leaked into city sewers, emitting hazardous fumes that prompted health officials to recommend evacuation of 1,100 homes.

Ford was slow to disclose the 1,400-gallon leak to state regulators, and the resulting evacuations strained relations between the company and Flat Rock residents. EGLE is still investigating what caused that leak, and has not decided whether Ford will face fines.

Once investigators have stopped the Huron River leak, state regulators will oversee river cleanup efforts. Greenberg, of EGLE, said the party or parties responsible for the leak will be expected to pay cleanup costs.