The effort to permanently seal the leaking gas well that fouled the air above Porter Ranch for 31/2 months reached a prosaic stage Saturday.
"We're waiting for the cement to dry," said Don Drysdale, a spokesman for the state Conservation Department, one of the agencies overseeing the operation.
Crews finally stopped the plumes of methane from escaping the Southern California Gas Co. well Thursday by injecting heavy fluids and mud into the well. That temporary plug is being replaced with layers of cement, which is being pumped through a relief well into the damaged one.
The seal should be in place within a couple of days, company spokesman Javier Mendoza said.
Next, the company and state regulators will conduct a series of tests to ensure that minute amounts of methane are not seeping through the cement bond.
In the meantime, ongoing monitoring for methane and other compounds in the air will continue, said Teresa Schilling, a Conservation Department spokeswoman. The tests are being conducted by the state Air Resources Board and the South Coast Air Quality Management District, Schilling said.
First reported by the gas company Oct. 23, the leak at the Aliso Canyon well prompted thousands of people in Porter Ranch and surrounding communities to leave their homes. Odorants added to the methane left many people with headaches, dizziness and nausea.
On Friday, Sen. Barbara Boxer (D-Calif.) said an independent air study should be conducted before residents return to their homes. A separate study was needed, she said, because of lingering distrust of the gas company and the Conservation Department's Division of Oil, Gas and Geothermal Resources, which regulates wells. Such a study could be performed by a private group or the U.S. Environmental Protection Agency, Boxer said.
But Schilling said residents should have confidence in the tests underway.
"There are multiple regulators witnessing and conducting these tests to be absolutely sure that the leak is sealed," she said. Results will be posted on the department's website.
The gas company faces investigations and lawsuits because of the leak. Among the allegations is that the well was poorly designed and constructed and that the utility had failed to properly inspect and oversee it.
On Saturday, the company said in a statement that it was "committed to cooperating with investigations and working with policy makers at all levels of government to ensure gas storage is safe and reliable."