Home Energy Efficiency Team, via Standard YouTube License

This screen grab, from a video created by the Home Energy Efficiency Team, shows the scale of the methane leak. Home Energy Efficiency Team, via Standard YouTube License

Californians are increasingly worried about about the massive methane leak that’s been spewing from a natural gas well near Porter Ranch, a community in the San Fernando Valley to the northwest of Los Angeles. Last week, Gov. Jerry Brown declared an official state of emergency over the leak, which has driven thousands of residents from their homes.

But worriers are not likely to be comforted by the findings of University of California, Davis scientist Stephen Conley, who flew over the site in an airplane specially-equipped to detect pollution. He found that the leaky well is releasing 1,200 tons of methane per day, which works out to 100,000 pounds per hour.

Massive California Methane Leak Made Visible

“To put this into perspective, the leak effectively doubles the emission rate for the entire Los Angeles Basin,” Conley said in a press release. “On a global scale, this is big.”

Conley flew in a plane that belongs to his private research flight company, Scientific Aviation. The aircraft contains a greenhouse gas analyzer that measures methane plumes in real time.  It’s also equipped with a differential GPS system provides precise wind readings, which is vital for quantifying sources of methane and other emissions.

The California Energy Commission hired Conley to do the initial monitoring flights in November. He has continued to monitor the site, and his most recent fly-over was Dec. 23.

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The leaking well, Standard Sesnon No. 25, is used to send natural gas from transmission lines down more than 8,500 feet below the ground at Southern California Gas’s Aliso Canyon storage facility near Los Angeles.

The leak contains mostly methane, a greenhouse gas that is many times more potent than carbon dioxide. Porter Ranch residents downwind from the methane leak have complained of headaches, nausea, dizziness and nosebleeds. New Scientist reports that the leaking gas also contains benzene, a known carcinogen, and mercaptans, which are believed to be causing headaches and nausea. In November, measurements showed benzene air concentrations were six times higher than safe levels, the magazine said.

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The Los Angeles Daily News reports that Southern California Gas has been digging in an effort to plug the leak, but that the job may not be completed until March. The company reportedly has spent $50 million on measures to cope with the leak, including temporarily moving some residents and installing air purifiers in about 3,000 homes.

The Environmental Defense Fund warns that there are 400 other natural gas storage facilities around the country, similar to the one near Porter Ranch.

The Home Energy Efficiency Team has created this animation showing the scale of the leak.