Volume 105, Number 10 - March 13, 2008
brought to you online by Pinedale Online
Ozone strikes county again
While Sublette County residents were still talking about February’s ozone air pollution advisory, not only the first in the county but also the first in the state, the Air Quality Division (AQD) of the Department of Environmental Quality (DEQ) issued a second advisory on Monday, and a third on Tuesday. After the DEQ found the first advisory in February was unwarranted and followed by regular ozone levels, it will now issue pollution advisories one day in advance and that last only 24 hours.
“We don’t have confidence in our predictions much beyond tomorrow, because these predictions are based on weather forecasts, and they’re only as accurate as the weather forecasts,” said AQD administrator Dave Finley.
The advisories for Monday and Tuesday did accurately forecast high ozone levels, however. The DEQ monitoring station in Boulder recorded that eight-hour averages reached 81 parts per billion (ppb) on Monday and 117 ppb on Tuesday, disturbingly above the National Ambient Air Quality Standard of 80 ppb.
The eight-hour average in Boulder even reached 91 ppb on March 9, the day before the second advisory, demonstrating the DEQ’s difficulty in predicting ozone levels in time.
This is because high ozone levels are rare outside urban areas, and rare anywhere during the wintertime. Yet the DEQ has monitored ozone levels exceeding the national standard in the winters of ’05, ’06, and ’08 in Sublette County.
After conducting intensive winter air quality studies over the past three years, the DEQ believes the unusual ozone levels are caused by exceptional weather conditions. Specifically, snow on the ground allows sunshine to reflect back up and double the power of Ultra Violet (UV) rays that break up Nitrous Oxide (NOx) emissions, which combine with volatile organic compounds (VOC) to produce ozone.
Strong inversions and low wind ventilation keep the ozone stagnant, allowing it to build.
“Those net conditions are set up in spades this year,” Finley said. Thus ozone levels have rocketed in recent weeks to the highest the county has ever seen, with eight-hour averages reaching 122 ppb in mid February.
But that’s not just the weather’s fault, Finley admitted.
“You could have all of these perfect air quality conditions — sunlight, snow cover, slow winds, but if you had no VOCs or NOx, you wouldn’t create much ozone,” he said. “There’s a lot of different pollutant sources (in Sublette County), but principally it’s correct to say the big contributors of VOCs and NOx are activities associated with the drilling of natural gas up there.” Gas operators on the Pinedale Anticline repeat the same remedy they’ve offered for the past year.
If the Bureau of Land Management (BLM) allows them to develop an additional 4,000 wells with year-round drilling, they can obtain contracts for cleaner field technologies. Natural-gas-powered rigs would reduce NOx emissions by 80 percent, for instance, and a Liquids Gathering System for transporting production fluid would reduce VOCS, said Diana Hoff, Questar General Manager for the Pinedale Division.
“The DEQ supports the air mitigation in the SEIS proposal,” Hoff said, referring to the Supplemental Environmental Impact Statement for the expanded drilling project. But Linda Baker, grassroots coordinator for the conservation group the Upper Green River Valley Coalition, said that’s not good enough.
“I’ve seen that brown cloud developing in the southern end of the county for the past six years or so, but it’s what you can’t see that you have to be worried about,” Baker said, referring to the fact that ozone isn’t visible. As drilling continues, the air quality can only worsen, she said, which is why the state needs to require better emission-control technologies and a slower development pace immediately. “So far the DEQ’s done nothing but talk and study, talk and study,” Baker said. “Now it’s time for action.”
Finley said the DEQ feels the same urgency. “I can appreciate people saying to us, ‘you need to do something,’ and we’re trying to figure out what that is,” he said. Red tape is the main obstacle to immediate action.
Under the Clean Air Act, the state has authority to set emission standards for stationary emission sources, like gas field tanks or compressor stations.
The Wyoming DEQ has taken the responsibility seriously, establishing a permitting program for minor stationary sources in 1997. The DEQ has updated the program with more stringent emission requirements five times since, Finley said.
But the federal government has jurisdiction over mobile emission sources, including the trucks and semis that drive to the gas fields, as well as the drilling rigs themselves. Finley couldn’t say what the next step would be in coordinating state and federal methods to significantly reduce emissions on the gas fields in the near future.
“We’re not sure we’re entirely powerless to reduce emissions from drilling rig engines,” Finely said. “We’re looking at what our options are.”
The Environmental Protection Agency (EPA) does have the authority to take over regional mitigation methods in the case of an ozone violation, but that only occurs when ozone levels exceed the national standard multiple times over three consecutive years.
Even determining how to improve emission controls is tricky, Finley said. Because ozone is a secondary pollutant produced by a chemical reaction between VOCs and NOx, limiting either one too much can result in raising ozone levels even further. For now, the DEQ plans to turn over the data from its winter studies over the past three years to ambient air modelers, who will develop air quality models to better understand ozone in Sublette County, Finley said.
“We do understand that people are exposed to unhealthy air and may not be able to wait until we have scientifically quantifiable answers,” he said. “We understand that our primary purpose is not to study the problem to death while people are breathing unhealthy air. But if you asked me today what we’re going to do, I couldn’t tell you the answer.”
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