Study: Gas operations prime pollution source in Utah’s Uinta Basin
Oil and gas operations in Utah’s Uinta Basin are the prime source there of volatile organic compounds and nitrogen oxide, two key factors in ozone pollution, according to a new study of the problem of winter ozone in the basin.
The study also suggests that reductions in certain kinds of volatile organic compounds, including benzene and toluene, “could be particularly effective since they are not only a direct health concern but are more active in ozone production than many other” VOCs. Besides contributing to ozone formation, benzene is a carcinogen and toluene also is considered a hazardous pollutant.
The Utah Department of Environmental Quality has released a final report on a multi-agency 2011-12 ozone study for the basin, centered in northeastern Utah. Recently identified winter ozone problems there also have arisen in Rangely and western Rio Blanco County, on the basin’s eastern edge, and the Colorado ozone may be related to that in the Uinta Basin, the Environmental Protection Agency has said.
Ironically, ozone levels during the study season of winter 2011-12 were well below acceptable EPA standards, unlike the prior two winters. The basin had little snow cover and no persistent temperature inversions that trap colder air in valleys, both of which are linked to high ozone levels. The study notes that snow cover reflects sunlight, limiting daytime heating and further adding to inversions, and it estimates that the reflected sunlight nearly doubles ozone-creating chemical reactions involving VOCs and nitrogen oxide.
It said historical weather data suggests a severe ozone season in the basin will happen about once every four winters, with conditions conducive to ozone formation occurring on at least some days during about half of winters.
The study said the oil and gas industry is responsible for 98 to 99 percent of VOCs and 57 to 61 of nitrogen oxide, for sources within the basin considered in an emissions inventory. The coal-fired Bonanza Power Plant near Vernal emitted an estimated 33 to 36 percent of nitrogen oxide originating within the basin during the study.
The study didn’t specifically seek to quantify the possible role of pollutants coming in from outside the basin. But it said they aren’t likely a major contributor, for reasons such as higher concentrations of VOCs and nitrogen oxide inside the basin than outside.
Continuing study in the basin is occurring this winter, when weather conditions conducive to ozone formation have occurred and several ozone alerts have been issued.
The Department of Environmental Quality organized the study, with involvement from entities such as the Bureau of Land Management, the EPA and several universities. The Western Energy Alliance contributed more than $2 million, collected from several member energy companies.
Ozone can cause respiratory problems in sensitive populations such as children, the elderly and those with asthma, and even in healthy adults such as those exercising or doing manual labor outdoors.
Ozone is more commonly a summertime problem in urban areas. But high wintertime readings also have been detected in the rural western Wyoming gas development region around Pinedale.
Brock LeBaron, deputy director of Utah’s Division of Air Quality, said during a teleconference Tuesday that Utah Gov. Gary Herbert is “quite concerned” about the Uinta Basin ozone, “and what we can do to remedy the situation.”
But with more scientific study needed regarding the complex issue of ozone formation in the basin, no new regulatory requirements are being considered at this stage, he said.
A study author, Seth Lyman of Utah State University, said more study of sources of ozone precursors is required, and because of that and other uncertainties, researchers can’t provide specific recommendations of what types of emission controls might help.
The report offers its “best estimate” that VOC reduction will reduce ozone formation, but adds that “the overall effectiveness of this strategy is unknown.” Another approach may be to try to limit industrial operations where possible during times when weather conditions are ripe for ozone formation, the study says.
Kathleen Sgamma with the Western Energy Alliance notes that the EPA has imposed new national oil and gas pollution controls that will reduce VOC emissions. The study notes those controls’ targets include glycol dehydrators, a large source of so-called aromatic VOCs such as benzene and toluene.
Sgamma said energy companies have been proactively involved with the ozone issue for a number of years, and have been taking steps to reduce air pollution.
“There’s more study to be done,” she said, adding that the industry looks forward to learning how to mitigate emission problems in the best way, and also in an economical way that can allow it to continue to contribute to the local economy.
Uintah County, Utah, Commissioner Mike McKee said both air quality and the oil and gas industry are important to local communities. He said it’s important not to take a “shotgun approach” to the ozone problem and to make sure that any measures effectively address the issue.