Southern California Gas Co. (SoCalGas) on Thursday released the results of indoor air testing in homes nearest its Aliso Canyon underground gas storage field in Los Angeles and concluded methane levels are now "well below" environmental screening values. In addition, the homes were found to be free of the natural gas odorant mercaptan.
Independent testing firm Geosyntec Consultants Inc. did the testing. The Aliso Canyon well leak was sealed last month (see Daily GPI, Feb. 18).
The Sempra Energy gas-only utility announced a week ago the initiative to test indoor air quality following a request from Mike Antonovich, the Los Angeles County Board of Supervisors member whose district includes Aliso Canyon (see Daily GPI, March 14). According to Geosyntec, no further indoor testing is necessary.
Outdoor air in the area has returned to typical background levels, according to analysis of more than 3,500 outdoor air samples by independent agencies, according to SoCalGas officials, and confirmed by state and local authorities.
"Consistent with the thousands of air quality samples that have been collected outdoors, our indoor screening found that methane levels inside homes were within normal ranges, and any odorants that could be responsible for short-term [resident health] symptoms were not detected at all," said Gillian Wright, SoCalGas vice president for customer service. Wright acknowledged that some residents have asked for additional reassurances, and she hopes these latest results provide that for families still displaced.
The 70 homes tested are dispersed throughout the Porter Ranch development.
"All screenings for methane were found to be well below levels that would warrant further evaluation, and in addition, no natural gas odorants were detected in any sample," the spokesperson said, adding that hand-held flame ionization detectors were used to screen for methane, and individual air samples were collected for laboratory testing for any odorants or sulfide compounds.