Regional air quality regulators on Tuesday filed a lawsuit in state Superior Court in Los Angeles against Sempra Energy’s Southern California Gas Co. (SoCalGas), alleging negligence by the nation’s largest gas-only utility in the handling of a three-month-old leaking natural gas storage well.

Neither the South Coast Air Quality Management District (SCAQMD) nor SoCalGas issued any statements on the legal action, which came within days of the air regulators ordering the utility to close the leaking well (SS-25) at the 3,600-acre Aliso Canyon underground storage facility in the San Fernando Valley (see Daily GPI, Jan. 26).

SCAQMD’s lawsuit alleges that SoCalGas was negligent in the design, construction, operation and inspection of the leaking well, one of 115 operated at the 86 Bcf capacity storage field, an old oilfield that dates back to the 1950s. The district filed a civil complaint citing six causes that collectively carry fines of up to $440,000/day/violation, with the largest being a possible $250,000/day fine for violating state health-safety codes.

According to the lawsuit, SoCalGas’ negligence has violated air quality regulations and state law. A utility spokesperson told local news media that SoCalGas would not comment on pending litigation. There are numerous legal actions from government and displaced residents in the Porter Ranch residential development a mile south of Aliso Canyon.

In December, the Los Angeles city attorney filed a lawsuit against SoCalGas for its handling of the then seven-week-old storage well leak (see Daily GPI, Dec. 8, 2015). That 13-page complaint alleged the utility engaged in unlawful business practices leading up to the incident.

SoCalGas announced earlier this week that it was in the fifth and final stage of drilling a relief well to plug the leak, seal the well, and prepare it for permanent closure. That is expected to happen next month if everything goes as now planned.

At the beginning of the new year, SoCalGas estimated the response to the leaking well had cost $50 million, including picking up the expenses for more than 2,000 relocated families from Porter Ranch. In a Securities and Exchange Commission filing, Sempra said that it carries insurance that could cover legal and other costs up to $1 billion.

Even without a determination of the root cause of the unprecedented storage well leak, the SoCalGas incident is expected to have far-reaching, long-term financial, regulatory and operational implications for the natural gas storage sector nationally.