Engineers from California’s Division of Oil, Gas and Geothermal Resources (DOGGR) on Thursday confirmed that the nearly four-month-old leaking natural gas storage well in Southern California has now been permanently sealed.

Sempra Energy and its Southern California Gas Co. (SoCalGas) utility now face a long regulatory and legal battle.

“After independently reviewing multiple tests on the leaking well — including temperature, noise and cement-bond tests — we have confirmed that the Standard Sesnon 25 [SS-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), under which DOGGR operates.

DOGGR, along with other regulatory agencies, has overseen the work of SoCalGas and its contractors through the well closure process.

SoCalGas on Thursday sent a letter to all residents in the nearby upscale Porter Ranch residential development in the far northern end of the Los Angeles San Fernando Valley, telling them that the leaking well has been permanently sealed and they can return home (see Daily GPI, Feb. 16).

The Sempra Energy gas only utility said it is working with state officials and an independent expert chosen by the California Public Utilities Commission (CPUC) to determine the cause of the leak.

The testing process to confirm that the well is sealed was developed in consultation with independent 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 CPUC, as well as independent investigators, will continue to work at the SS- 25 well site to determine the cause of the leak and whether violations of state regulations occurred, a DOGGR spokesperson said.

The California Air Resources Board (CARB), working with the South Coast Air Quality Management District (SCAQMD), has measured gas emissions from the leaking well since the well was initially sealed on Feb. 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 DOGGR spokesperson said.

CARB and SCAQMD have also established objective criteria to determine when air quality in Porter Ranch and surrounding communities has returned to normal. Since Feb. 15, 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 on their respective websites.

The Office of Environmental Health Hazard Assessment (OEHHA) has independently validated the criteria established by CARB and SCAQMD 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 a governor’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 were released by DOGGR on Wednesday this week (see related story).

Also under Gov. Jerry Brown’s January order, all gas storage wells throughout the state are subject to new emergency regulations (see Daily GPI, Jan.15).

“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,” Marshall said. “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, the DOGGR spokesperson said.

The well had been leaking since Oct. 23. A temporary seal of the leaking well was established on Feb. 11 and a permanent cement seal was established Feb. 17.

Separately, on Monday SoCalGas attorneys pleaded not guilty to four criminal charges concerning the storage well leak that forced thousands of residents from their homes (see Daily GPI, Feb. 17).SoCalGas was arraigned on four misdemeanor charges for failing to report the release of hazardous materials from Oct. 23-Oct. 26 and discharging air contaminants beginning on Oct. 23.

Los Angeles County prosecutor Jackie Lacey filed the charges on Feb. 2, the same day California Attorney General Kamala Harris also sued the company. SoCalGas also faces numerous private lawsuits filed on behalf of area residents (see Daily GPI, Feb. 3).