The potential for sinkholes could pose problems along interstate gas pipeline routes through northwest Ohio, warns a report submitted to federal regulators last month.

At a minimum, the situation merits further study, according to the report’s authors, Robert Vincent and Charles Onasch of Bowling Green State University, and public advocate Leatra Harper of the FreshWater Accountability Project.

Current plans call for Spectra Energy’s Nexus Pipeline and Energy Transfer’s twin Rover pipelines to carry natural gas from Michigan through Ohio to points east.

An industry spokesman calls it “insulting” to suggest the pipeline developers might not factor the risk into their route planning and engineering.

Fracking of horizontal shale formations has led to a boom in natural gas production in much of the Midwest. The resulting jump in production has strained the current infrastructure for getting natural gas to its markets.

The new pipelines are part of the industry’s efforts to relieve that strain. Proposed routes for both projects will cross Wood County in northwest Ohio.

According to the report, both pipelines will cross the Bowling Green fault line as well as areas of karst geology.

Karst landscape forms in soluble carbonate rock formations, such as limestone and dolomite. “Water will dissolve both of those over time,” said Vincent. “Acid dissolves them much faster.”

Whether it happens quickly or slowly, dissolution of the county’s karst formations could form caverns, Vincent said. If the process goes on long enough, a cavern could collapse.

“Finally the roof of it will cave in, and you’ll have a big hole there called a sinkhole,” Vincent explained.

“These pipelines are supposed to last 100 years,” Vincent said. But that’s less likely “if they’re built across something that’s got a cavern under there to begin with [which] gets bigger over time.”

The chances of a problem are greater in Wood County, Vincent said, because of the area’s history of oil and gas production and the presence of the Bowling Green fault.

Oil or gas could escape upward through the fault, Vincent explained. If it mixed with water, he said, that process could produce sulfuric acid, which would dissolve the soluble rock more quickly.

And while other gas pipelines already cross parts of Wood County, each of the proposed pipelines is “bigger, and they’re carrying a lot more gas,” Vincent noted. “If you wreck it, it’s going to cost you a whole lot more, and there’s going to be a lot more environmental damage.”

More study needed

The report doesn’t rule out construction of the pipelines. But it does recommend additional research.

“I would do a study to see where there are evidences of faults that are crossing those pipelines from any angle,” Vincent said. Those areas would then get additional study.

“We don’t have to go down very deep,” maybe just 100 to 300 feet below the surface, Vincent said.

A route change or engineering might then address any potential problems, Vincent suggested.

For example, additional supports might “spread the weight out of the pipeline in that area,” he said, in the same way a snowshoe can keep its wearer from sinking into deep snow.

As an example of the potential for sinkhole formation, the report notes a 2014 incident from Kentucky.

In that case, a sinkhole measuring 30 feet deep and 40 feet across opened up beneath the National Corvette Museum in Bowling Green. A gas pipeline exploded the next day, roughly 80 miles away.

There’s no evidence that the sinkhole had anything to do with that pipeline explosion, noted Jimmy Stewart, president of the Ohio Gas Association.

“That’s the best they could come up with? Really?” Stewart said.

Nonetheless, advocates in Kentucky noted, if a pipeline had been near the sinkhole, the collapse could have caused an explosion.

“The Adair County example shows it is possible, but it may also be extremely rare,” said John Stoody of the Association of Oil Pipe Lines. “I have not heard of it happening anywhere else.”

Detailed review of data from the Pipeline and Hazardous Materials Safety Administration would be necessary to provide a substantive answer on whether a suggested risk is significant, Stoody suggested. That agency is part of the U.S. Department of Transportation.

“There are millions of miles of natural gas pipeline in the United States. And for over 100 years, we’ve had natural gas pipelines,” Stewart stressed.

“This is the safest means of transportation,” as well as the most efficient, he added. “If not by pipeline, then I guess my question is, how would they like it done?”

Survey work still being done

In any case, a final pipeline route has not yet been determined, said Arthur Diestel, manager of stakeholder outreach for the Nexus project.

“Nexus is currently conducting survey activities in order to fully understand the study corridor’s attributes and to determine the location for the pipeline that minimizes impacts on landowners and the environment,” Diestel noted. Nexus would then use the information to prepare draft environmental reports for the Federal Energy Regulatory Commission (FERC).

“The current route proposal utilizes over 85 percent agricultural areas and/or follows existing utility corridors in Ohio and Michigan in order to minimize environmental and local impacts,” Diestel added.

In any case, “Nexus will diligently assess any karst areas identified near the pipeline route through research, surveys, and geophysical and geotechnical studies,” Diestel continued. “Based on our survey results, the pipeline will be designed and constructed—or, if necessary, rerouted—for safe operation.”

“Pipelines successfully operate in areas of this type of terrain in Ohio, as well as other regions in the U.S.,” Diestel stressed.

More generally, for any natural gas pipeline, “you’re going to take into account a wide variety of ecological, geological, and scientific data,” Stewart said. “That would include, but would certainly not be limited to, the possibility of sinkholes.”

“Quite frankly, I think it’s insulting” to suggest that industry would put a pipeline in an unsafe location, Stewart added. “You’re saying that they’re too incompetent and not smart enough to safely design a natural gas transmission line.”

Nonetheless, the report was submitted to FERC as part of a process aimed at gathering preliminary input from citizens and other stakeholders.

Harper submitted the report last month at a scoping meeting on the Nexus project in Swanton, Ohio. She also filed the report separately in the agency’s case file for that project.

The report was not available when her group testified at an earlier meeting for the Rover pipeline, she said. “But the same concerns would apply all across this region.”

“These huge high pressure pipelines are being built, mostly for export, and mostly by huge multi-national investors for profit,” Harper noted. In her view, local, long-term concerns deserve greater consideration.

“Those running these projects certainly would not care more about pipeline impacts or know more about the unique characteristics of the region than the local citizenry who live and work in the area,” Harper said.