By Lucy Nicholson
DIAMOND BAR, Calif. (Reuters) - Air quality regulators, meeting for the third time this month to address a huge natural gas leak that has forced thousands of Los Angeles residents from their homes, delayed action again on Wednesday on a proposal to curtail the escaping methane.
The five-member hearing board of the South Coast Air Quality Management District scheduled a fourth meeting for Jan. 23 to take more testimony on a plan to siphon off and incinerate methane that has been spewing into the air since October.
The stench of gas fumes has sickened scores of people and led to efforts to temporarily relocate of some 6,000 households from the Porter Ranch community of northern Los Angeles at the edge of the leaking Aliso Canyon underground gas storage field.
But local and state agencies have raised safety concerns with the proposal to capture and burn off some of the methane, as have engineers for Southern California Gas Co., owner of the crippled facility.
The proposed abatement order also calls for the utility to accelerate extraction of its remaining subterranean gas reserves so as to relieve pressure on the ruptured wellhead.
In its first three hearings this month to review the plan, including Wednesday, the board opted to merely hear public comment, much of it from disgruntled residents demanding the facility be shut down altogether.
The company has insisted the leak, while a major public nuisance, poses no immediate public safety threat because the gas dissipates outdoors. But health officials said long-term health effects remain unknown.
SoCal Gas, a division of San Diego-based Sempra Energy, has said the leak stems from a broken injection well pipe several hundred feet beneath the surface.
The company normally pumps surplus supplies of natural gas underground beneath the site in summer when energy demand is low and draws it back out in winter.
Several attempts to halt the leak have failed, and the company projects it may take until late February to plug the rupture through a relief well.
Methane, the prime component of natural gas and a far more potent greenhouse gas than carbon dioxide, has been seeping out of the site in amounts marking the largest such leak ever in California.
At one point, the California Air Resources Board estimated gas was escaping at the rate of 58 metric tons per hour, accounting for one-fourth of all methane emissions statewide, but the company said the flow has diminished by 60 percent.
(Writing and additional reporting by Steve Gorman in Los Angeles; Editing by Alistair Bell)