New Study Calls For Monitoring Old Oil & Gas Wells For Air Emissions

A new study on the hazardous gas emissions from the calamitous 2015 blowout of the Aliso Canyon natural gas storage facility, near Porter Ranch, CA, has found that apart from methane, a group of other hazardous pollutants escaped into the air, affecting many residents in the area. The study calls for air monitoring at underground gas storage facilities nationwide, potentially affecting thousands of sites around the country.

“Several of the gaseous pollutants measured are highly correlated with elevated methane and are associated with cancer or other serious health problems. HAPs measured include hexane, benzene and m/p-xylene,” say the authors of the study from UCLA’s Fielding School of Public Health’s Department of Environmental Health Sciences.

“Our findings demonstrate that uncontrolled leaks or blowout events at natural gas storage facilities can release pollutants with the potential to cause not only environmental harm, but also adverse health consequences in surrounding communities,” said study first author Diane A. Garcia-Gonzales, a postdoctoral scholar at the Institute.

Unknown Status wells in the United States. Source: Environmental Research Letters

The new study is entitled, “Associations among Particulate Matter, Hazardous Air Pollutants and Methane Emissions from the Aliso Canyon Natural Gas Storage Facility During the 2015 Blowout.” It is being published today in Environment International.

Porter Ranch is an affluent neighborhood in the northwest region of the San Fernando Valley region of Los Angeles, with a population of over 30,000. On October 23, 2015, Southern California Gas Company workers discovered a leak in one of the over 110 wells at the Aliso Canyon natural gas storage facility, about three miles north of homes in Porter Ranch, according to Wikipedia. 

The gas blowout began spewing 110,000 pounds of methane per hour, the online encyclopedia notes. The blowout involved gas stored under pressure in an underground reservoir; the stored gas included mercaptan (tert-Butylthiol), an odorant added to the odorless natural gas to produce a rotten egg smell for safety. The California Air Resources Board estimated that the leak increased California’s methane-gas emissions by 25%, Wiki says.

The new study survey of more than 100 indoor environments, including homes and schools, adjacent to the storage facility found elevated levels of several air toxins along with a fingerprint of metals in dust samples similar to those taken of samples at the blowout site, according to the authors. In a post-leak community survey, the authors found that “63% of households reported that someone in their home had experienced symptoms persisting after the leak was plugged, including headaches, nausea, and gastrointestinal or respiratory problems,” they said.

The UCLA team recommended that natural gas storage facilities be required to install equipment that collects air quality and meteorological data, and that closer environmental monitoring be required following severe off-normal operation events, according to a statement. 

“More than 300 natural gas storage fields within the United States use depleted oil wells, many of them aging, with very little oversight as to how they should be updated,” said Michael Jerrett, the study’s senior author, who is professor and chair of the UCLA Institute. 

The blowout at Aliso Canyon was the largest single accidental release of greenhouse gases in U.S. history, according to a 2017 study by Drew Michanowicz, et al., published in Environmental Research Letters. This study found identified 14,138 active underground storage (UGS) wells associated with 317 active UGS facilities in 29 states using regulatory and company data, according to the team led by Michanowicz, a researcher at the Center for Health and the Global Environment, Department of Environmental Health, within Harvard’s T. H. Chan School of Public Health in Boston. 

The 2017 study also found that state-level wellbore datasets contained “numerous reporting inconsistencies that limited data concatenation,” The authors identified 2,715 active UGS wells across 160 facilities that, “like the failed well at Aliso Canyon, predated the storage facility, and therefore were not originally designed for gas storage. The majority (88%) of these repurposed wells are located in OH, MI, PA, NY, and WV,” the authors said.

The 2017 study concluded that “99% of repurposed wells constructed prior to 1979 are particularly likely to exhibit certain design deficiencies including single passive barrier protection. An estimated 210 active repurposed wells were constructed before 1917 — before cement zonal isolation methods were utilized. These wells are located in PA, OH, NY, and WV and represent the highest priority related to potential design deficiencies that could lead to containment loss.” 

The UCLA Fielding School of Public Health, founded in 1961, is dedicated to enhancing the public’s health by conducting innovative research, training future leaders and health professionals from diverse backgrounds, translating research into policy and practice, and serving our local communities and the communities of the nation and the world, according to a statement. The school has 650 students from more than 35 nations engaged in carrying out the vision of building healthy futures in greater Los Angeles, California, the nation and the world, the statement says.