After natural gas fires and explosions rocked the Merrimack Valley in September, lawmakers called for new federal regulations on the pipelines that caused the disaster. But those kinds of safety regulations have been in the works for years and haven't gone anywhere.

Sen. Ed Markey referenced the slow pace of new regulations back in November, when he participated in a hearing about the Merrimack Valley disaster in Lawrence. At the hearing, Markey laid much of the blame for the disaster on the agency charged with regulating the natural gas industry: the Pipeline and Hazardous Materials Safety Administration, or PHMSA.

"This agency often takes many years to issue required regulations, dragging its feet while our communities remain in danger," he said.

Members of Congress have been calling on PHMSA to pass new safety regulations since at least 2010, when eight people were killed and 35 homes were destroyed in San Bruno, Calif., when a gas transmission line ruptured. After that, the National Transportation Safety Board recommended that PHMSA enact a range of new rules.

Carl Weimer, the executive director of the nonprofit Pipeline Safety Trust, said that the plan is in place, but it’s waiting to be implemented.

"PHMSA, the federal regulators, came up with the ‘mega rule’, and included a whole bunch of those fixes like better leak detection, better automated valves, better risk assessments. They came out with the first draft of that rule in 2011 and they still haven't passed any of it yet," Weimer said.

The advisory committee that reviews newly proposed PHMSA regulations was supposed to meet this week to try to finally get some parts of that “mega rule” over the finish line. But now that’s on hold because of the government shutdown.

Even if they did meet, though, Weimer said the members of that committee who represent the industry are part of the problem.

"You know, they have a third of the seats at those tables to micromanage and discuss each little aspect of that rule, and that's where you start seeing lots of arguments about how something's too strong or it's too prescriptive and they need more flexibility in their regulations," Weimer said.

Those industry reps are armed with a usual tool to stop regulations, Weimer said. In 1994, the Republican Contract With America proposed adding new regulations only if it could be shown the cost was justified by the benefits. That part of the contract didn’t go anywhere — except in one place, said Sara Gosman, an associate professor of law at the University of Arkansas.

"They just were successful in a very specific area, which is pipeline safety laws," Gosman said.

That's because the cost-benefit requirement worked its way into the 1994 reauthorization of the National Gas Pipeline Safety Act. Gosman is on the committee that reviews and recommends new regulations to PHMSA.

"And because we have that requirement, people can sue on that requirement and challenge the rule,” Gosman said. “And therefore it really constrains what the agency can do."

Gosman said that, in her experience, the industry members on the committee have no problem coming up with the cost side of the equation.

"The tricky side is the benefits side," she said, adding that they can't really predict something rare, like the catastrophe that happened in Lawrence, Andover, and North Andover.

"We're really talking about avoided deaths, avoided injuries, avoided property damage,” she said. “All of this is based on what has happened in the past. And what I think Merrimack Valley shows you is that what happened in the past isn't necessarily what's going to happen in the future."

And even if new regulations were to pass, Gosman said, it might have other consequences, given an executive order from President Trump. Trump signed an executive order in January 2017 that for every one new regulation added, two regulations must be eliminated.

Gosman said she doesn't know how PHMSA would figure out what rules to get rid of.

Christina Sames, the vice president of operations and engineering for the American Gas Association, said the industry is actually supportive of new safety regulations.

"What I haven't seen in the Pipeline Advisory Committee meetings is industry saying, 'No, don't do this.' However, we have questioned, is it technically feasible to do what you're asking? Is there a more reasonable approach to meet the goal?'” Sames said.

She pointed out the costs of new regulations are ultimately paid for by gas customers.

"So one of the things that we try to do is, how do we meet the goal of pipeline safety at the lowest cost to customers possible?" Sames said.

And, Sames said, the cost-benefit requirement forces government to think through how to achieve that balance.

Of course, states also have a say over pipelines within their borders. After the Merrimack Valley catastrophe, Gov. Charlie Baker signed a bill into law on Dec. 31 that requires the approval of a professional engineer for gas infrastructure work. But more than eight years after the San Bruno explosion, as for passing new federal safety regulations, the question now is: Will anything going be different this time? Sara Gosman said no.

"No, not if Congress doesn't take it upon itself to change the statute that makes PHMSA's job so difficult," Gosman said.

There is one potential twist now, with Democrats running the House. A spokesman for the House Committee on Energy and Commerce says its new chairman plans to take a closer look at whether the cost-benefit requirement benefits industry over public safety, and whether it makes it too hard to protect the public from unsafe pipelines.