Aliso Canyon gas blowout near Porter Ranch led to dangerous pollutants near site, UCLA study finds

LOS ANGELES – Air quality samples collected near the Aliso Canyon natural gas storage facility during the 2015 blowout that led to the largest-known human-caused release of methane in U.S. history showed elevated levels of pollutants known or suspected to be associated with serious health problems, according to a UCLA Fielding School of Public Health-led study.

The study, which appears in the latest issue of the peer-reviewed journal Environment International, raises concerns about the potential public health impacts resulting from the methane leak at the Southern California Gas Co. facility, which is located less than a mile from the residential community of Porter Ranch in the northwest San Fernando Valley, according to UCLA.

Although methane is a powerful greenhouse gas that can contribute to climate change, it does not have a federal-level actionable human health benchmark. But the high methane levels in Porter Ranch during the final weeks of the event coincided with — and likely influenced — a broad range of air pollutants known or suspected to cause certain cancers, as well as neurological and respiratory effects, according to the study.

The UCLA researchers also found evidence that the final attempts to plug the leak in the well at the Aliso Canyon facility were associated with particle emissions that likely came from the well site, and that the well and/or activities associated with attempts to mitigate the leak had a discernible effect on the indoor air environments of homes that were sampled.

“Our findings demonstrate that uncontrolled leaks or blowout events at natural gas storage facilities can release pollutants with the potential to cause not only environmental harm, but also adverse health consequences in surrounding communities,” said the study’s principal author, Diane A. Garcia- Gonzales, a postdoctoral scholar at the UCLA Fielding School of Public Health and UCLA Institute of Environment and Sustainability.

SoCalGas operators working at the Aliso Canyon facility first reported the leak on Oct. 23, 2015, and by the time state officials announced that it was permanently plugged, nearly four months later, about 97,100 metric tons of methane had been released into the atmosphere.

In a post-leak community survey, 63 percent of households reported that someone in their home had experienced symptoms persisting after the leak was plugged, including headaches, nausea, and gastrointestinal or respiratory problems, according to UCLA.

For its part, SoCal Gas, has consistently said that environmental tests from multiple agencies have come back showing no signs of a health hazard in the long term.

“Thousands of air, soil and dust samples were tested during the leak and for months afterwards by multiple public health agencies,” SoCal Gas spokesman Chris Gilbride said. “According to those health officials, all the data have shown that there was and is no long-term risk to public health or safety from the gas leak.”

But that hasn’t stopped legal action against the utility, which is owned by San Diego-based Sempra Energy.

Earlier this month, a longtime program manager overseeing the California Public Utilities Commission’s Safety Enforcement Division sued Sempra Energy and its SoCalGas subsidiary, alleging he came into contact with hazardous substances at the site of the Aliso Canyon leak that left him with a rare cancer.

Filed in Los Angeles County Superior Court on June 3, the complaint alleges the companies knowingly exposed Kenneth Bruno to dangerously high levels of cancer-causing chemicals when he was deployed to the Aliso Canyon natural gas storage facility to monitor the capping of the well that was the source of the blowout.

Bruno’s lawyers allege he was not properly advised on protective clothing to wear while at the well.

“Rather than fully prepare Mr. Bruno for exposure to known carcinogens such as benzene, radon, toluene and formaldehyde, Sempra told him to wear appropriate footwear and a hard hat,” according to Bruno’s attorneys.

The company also failed to instruct him to remove his contaminated clothes before returning to his car to go home to his family, causing him to acquire a rare blood cancer, hairy cell leukemia, a known risk of benzene exposure, the complaint alleges.

According to a report released on May 17, the Aliso Canyon gas leak was caused by microbial corrosion of a well casing, and SoCalGas did not conduct detailed follow-up inspections or analyses after previous leaks.

The report was conducted by Blade Energy Partners, which was tapped in 2016 by the CPUC and the state Department of Conservation’s Division of Oil, Gas, and Geothermal Resources to perform an independent analysis of the leak’s root cause.

Thousands of residents in the northwest San Fernando Valley were forced out of their homes for months due to the leak.

Limited operations resumed at the facility in late July 2017 with the blessing of state regulators. Efforts by Los Angeles County officials to block the resumed operations failed in court.

A judge in February approved a $119.5 million settlement to resolve claims by several government agencies stemming from the leak, but did not resolve a still-pending class-action lawsuit involving thousands of residents who said their health and property values were damaged as a result.

Staff writer Olga Grigoryants contributed to this report.