The US Pipeline and Hazardous Materials Safety Administration (PHMSA) is planning to issue first-time minimum federal standards for underground natural gas storage facilities, the agency's top regulator said today.

PHMSA administrator Marie Therese Dominguez offered no timeline for when the agency planned to move forward with those rules. The agency wants to craft minimum standards that would apply to underground natural gas storage facilities across the US, with the option for states to adopt more rigorous rules, she said.

The regulatory push comes after a nearly four-month-long leak at Sempra Energy gas storage facility in Aliso Canyon, California. Scientists estimate the leak released 107,000 short tons (97,000 metric tonnes) of methane, equivalent to about one day of US methane emissions. President Barack Obama's administration has since vowed to step up its oversight of gas storage facilities, which are typically regulated by states.

PHMSA last month first announced that it planned to "initiate regulatory actions" to help ensure the safety of natural gas storage facilities. Dominguez today said those regulatory actions would create minimum standards for all states and improve oversight over interstate storage facilities. The regulations would help assure the public about the safety of gas storage facilities, she said.

"Accidents are not an acceptable part of doing business to the American people, and nor should they be," she said at the think tank the Center for Strategic and International Studies.

The US Congress has been supportive of PHMSA's plans to increase oversight of gas storage facilities. PHMSA reauthorization bills being advanced in both chambers of Congress would direct the agency to set minimum safety standards for underground gas storage facilities within two years.

PHMSA has faced fresh criticism about its oversight of the oil and gas industry amid a series of pipeline incidents. TransCanada temporarily shut down its 590,000 b/d Keystone crude pipeline last month after finding it leaked about 400 bl in South Dakota. Spectra Energy's Texas Eastern Transmission gas pipeline exploded last week at a location in Pennsylvania, injuring one person.

Dominguez said PHMSA is still conducting a root cause analysis of the pipeline explosion to figure out what happened. But she said the agency needed to make its pipeline inspection process as "rigorous as possible" and leverage the data it collects to find potential areas of high risks that can be addressed.

"The bottom line is we are never going to have enough people to actually cover the miles that we need to," she said.

Dominguez noted that the PHMSA reauthorization bills in Congress would create a voluntary system letting oil and gas pipeline operators to share information on inspections and maintenance. This system would help the pipeline industry identify areas of emerging risks and trends, Dominguez said, while preserving proprietary business information.