It could take as long as three months to stop the leak of natural gas from a storage well just north of Porter Ranch, an official with the Southern California Gas Company said Tuesday.
The already month-old leak from the Aliso Canyon facility has elicited hundreds of complaints from Porter Ranch residents complaining of noxious fumes and burning eyes.
Called to speak at a hearing before the Los Angeles County Board of Supervisors, SoCal Gas officials began with an apology.
"We're deeply sorry for how the leak has affected the community," said Gillian Wright, vice president for customer services.
"It is our top priority to safely and expeditiously stop the leak," said Jimmie Cho, the Gas Company's vice president for gas operations and systems integrity.
Cho told supervisors that for safety reasons the challenge has to be tackled in a series of steps, and that proven techniques for stopping well leaks — including flooding the well with fluid — have not worked in this case. He said the company will try additional options before resorting to drilling a new relief well, a process he estimated could take up to three months.
Supervisor Sheila Kuehl acknowledged the Gas Company's expertise, but added bluntly, "It does not seem to be working."
Cho said SoCalGas cannot say how much gas is escaping from the 8,500-foot deep well, but based on air quality measurements, the California Air Resources Board estimated a release into the air of as much as 50,000 kilograms — approximately 50 tons — an hour.
The South Coast Air Quality Management District has received more than 660 complaints, said Mohsen Nazemi, deputy executive officer. The AQMD has issued the Gas Company a notice of violation.
Since last week, the Gas Company has pledged to relocate any residents who want to leave the Porter Ranch area until the leak is fixed. The company has received requests from 259 households, and so far has relocated 57, with 118 more in process, said Wright.
Natural gas, predominantly composed of the hydrocarbon methane, is odorless. It is not considered toxic, but is highly combustible above a threshold concentration, above that which has been measured in Porter Ranch, but a concern near the well, where precautions are being taken to avoid accidental ignition.
So that there is awareness of a natural gas leak, an oderant is added, primarily the chemical mercaptan, with an unpleasant, sulfurous odor that the human nose can detect in small concentrations.
"The mercaptans are what are causing the symptoms," said Dr. Cyrus Rangan, the director of the toxics epidemiology program for the LA County heath department. Rangan said he would not expect to see long-term health effects, but that symptoms would recur so long as mercaptan is in the air.
"It is hard to believe there is no health effect while everyone is suffering," said Porter Ranch resident Kyoko Hibino. Monday night dozens from the community had gathered at a rally demanding the Gas Company shut down the well immediately.
Gas Company officials proposed attempting to minimize the smell by treating the escaping gas with another chemical that would neutralize the mercaptan. However, public health officials, County supervisors, and public speakers all raised concerns about efforts to mask the indicator.
After listening to the comments at the hearing, Cho said the Gas Company decided to hold off its plan to neutralize the oderant at least until it is discussed further at a neighborhood council meeting on Dec. 2.
"The community was very clear that they would like to be a part of the process, and also they have concerns about whatever measures we would take," Cho said. "They want to be involved."
Absent from Tuesday's hearing was California's Division of Oil, Gas & Geothermal Resources, known as DOGGR, which has regulatory authority over the wellfield. DOGGR oversees the steps being taken by the Gas Company, but does not direct them, said spokesman Don Drysdale.
The head of the board of supervisors, County Mayor Mike Antonovich, ordered Tuesday's testimony be sent to DOGGR, and requested a representative appear at the Board meeting next Tuesday.
Antonovich also requested a follow-up report from Public Health on health impacts of the leak.
The presence and strength of the odor varies with wind direction, said Matt Pakucko of the group "Save Porter Ranch," and was particularly strong during recent Santa Ana wind events, in which Porter Ranch is directly downwind from the Los Alisos facility.
The impact on Porter Ranch was the focus of the board hearing, but air quality agencies and environmental activists have raised broader concerns about the consequences for levels of greenhouse gases in the atmosphere. The estimated 50 tons an hour would amount to about one fourth of all the methane released into the air from all sources in California.
The Environmental Defense Fund (EDF) is using the adjectives "gigantic" and "monster" and "staggering" to describe the leak, and compared it to the amount of methane released into the atmosphere as a result of the energy use of three million homes, or approximately seven million cars.
EDF estimated the gas already escaped could be as much as two percent of all the gas stored in the well, described as the largest facility in the western United States.