On Wednesday, the state agency asked the Ohio attorney general’s office to hold pipeline officials financially responsible for $2.3 million in fines related to numerous environmental violations which have occurred during the $4.2 billion underground natural gas pipeline’s construction. Rover’s parent company is Dallas-based Energy Transfer Partners.

An analysis last month found the 710-mile-long Rover project has already piled up 104 “noncompliance incidents” so far — more than any other interstate natural gas pipeline in the past two years.

Along its Ohio stretch, the pipeline razed a historic house, leaked 2 million gallons of drilling sludge into protected wetlands and dumped contaminated slurry in quarries near water wells used by the Canton Water Department and Aqua Ohio.

In May, the Federal Energy Regulatory Commission ordered a halt to new drilling activity along the troubled project.

Since then, the company has done its part to clean up the releases, install a groundwater monitoring network and develop plans to remediate impacted wetlands, Ohio EPA Director Craig Butler told reporters Wednesday. But the company refuses to pay the millions in civil penalties ordered by the state, he said.

“Negotiations just in general with Rover have been quite difficult … We’ve reached an impasse and have to ask for assistance,” he said. “We believe it’s fair that they owe the state of Ohio in compensation.”

Environmental groups applauded the agency’s move to refer the case to state Attorney General Mike DeWine.

“Simply put, when a mess is made, a penalty is appropriate. If the Rover Pipeline project followed the rules and respected Ohioans and our natural resources, these things wouldn’t happen,” said Heather Taylor-Miesle, executive director of the Ohio Environmental Council.

Butler said the dispute will come down to whether the company is relieved from the fines under a federal exemption.

“That really is the heart of the matter. It’s an important legal point to Rover and to us,” he said. “We may end up in federal court about this.”

Earlier this month, federal officials gave Rover permission to start pumping natural gas through completed sections of the pipeline. They also OK’d resumed activity at nine horizontal drilling sites this week.

Rover Pipeline spokeswoman Alexis Daniel did not comment on the pending order to pay civil penalties, but did say in an email statement that the company expects to place the full project into service in the end of the first quarter of 2018.

Butler said the ongoing struggles with Rover shaped the details of a permit granted this week by his agency for NEXUS Gas Transmission’s $2.1 billion natural gas pipeline. This time, he said, the agency required detailed, site-specific contingency plans along the project’s path.

“Rover had very generic contingency plans,” he said. “We kind of learned from our mistakes.”

mrenault@dispatch.com

@MarionRenault