State Regulators Confirm Aliso Canyon Natural Gas Well is Permanently Sealed

News Release #2016-05
February 18, 2016

LOS ANGELES – After reviewing the results of multiple tests developed in consultation with independent experts, state regulators today confirmed that a leaking natural gas storage well has been permanently sealed.

The well, owned by Southern California Gas (SoCalGas) and located in the Aliso Canyon storage field near the Porter Ranch neighborhood of Los Angeles, had been leaking since October 23. A temporary seal of the leaking well was established on February 11 and a permanent cement seal was established February 17.

“After independently reviewing multiple tests on the leaking well — including temperature tests, noise tests and cement-bond test — we have confirmed that the Standard Sesnon 25 well at the Aliso Canyon Storage Field is no longer leaking and the well is sealed,” said Jason Marshall, chief deputy director of the California Department of Conservation (DOC). The Department houses the Division of Oil, Gas, and Geothermal Resources (DOGGR), which along with other regulatory agencies has overseen the work of SoCalGas and its contractors through the well closure process.

The testing process to confirm that the well is sealed was developed in consultation with independent technical experts from the Lawrence Berkeley, Livermore and Sandia National Laboratories. That process and DOGGR’s confirmation of the testing results can be found at

Investigators from DOGGR and the California Public Utilities Commission, as well as independentinvestigators, will continue to work at the Standard Sesnon 25 well site to determine the cause of the leak and whether violations of state regulations occurred.

The California Air Resources Board, working with the South Coast Air Quality Management District, has measured gas emissions from the leaking well since the well was initially sealed on February 11. Air measurements that have been collected using air flights, on-site observations, and monitors in the nearby communities all confirm that the leaking gas has diminished consistent with successfully controlling the leak. The Air Resources Board and the Air Quality Management District have also established objective criteria to determine when air quality in Porter Ranch and surrounding communities has returned to normal. Since
February 15, 2016 these criteria have been met. Thus, air quality has returned to normal for three consecutive days. Both agencies will continue to conduct to air quality monitoring in and around Porter Ranch for the foreseeable future with results posted here.

The Office of Environmental Health Hazard Assessment (OEHHA) has independently validated the criteria established by the Air Resources Board and Air Quality Management District and has determined that the residents of Porter Ranch and the surrounding communities should not experience adverse health impacts from air quality satisfying the criteria standards.

Currently, no new injection of gas is allowed into the Aliso Canyon facility. Under Governor Edmund G. Brown Jr.’s Emergency Order, SoCalGas must complete a comprehensive safety review of the Aliso Canyon facility and its wells before further injection is allowed. The criteria for that well-by-well review can be found at

Also under Governor Brown’s January order, all gas storage wells throughout the state are subject to new emergency regulations.

“We are implementing new rules and safeguards to ensure the safety of not only the Aliso Canyon facility, but all of California’s natural gas storage facilities,” said Marshall. “Each well at Aliso Canyon will have to pass a thorough a comprehensive battery of safety tests or be taken out of service. And statewide, each well within all of the state’s gas storage facilities must be monitored on a daily basis.”

State agencies remain committed to providing frequent public updates on regulatory activities related to Aliso Canyon. For more information, click here or go to

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