BILLINGS — Montana has asked the federal Environmental Protection Agency to reconsider its intent to designate Yellowstone County as failing to meet sulfur dioxide standards.
The state Department of Environmental Quality backed up its request with more analysis showing the trend is for lower sulfur dioxide emissions.
The DEQ outlined its position in a letter April 3 formally responding to EPA’s intent to designate all of Yellowstone County as not meeting a new national hourly standard for sulfur dioxide. The state and public had until Monday to submit comments to EPA.
David Klemp, chief of DEQ’s Air Resources Management Bureau, said Monday that the agency continues to believe that information EPA used in its evaluation does not represent normal emissions and renewed its request for an “unclassifiable” designation, rather than "nonattainment," to allow for further review.
DEQ’s fallback position, Klemp said, is for EPA to consider designating only the Billings area as in “nonattainment” and to exclude the Laurel area, where the air quality monitor has not shown problems with the new standard.
EPA notified the state in February of its plan to apply the “nonattainment” classification.
A “nonattainment” designation would mean that sources responsible for the air quality violations may have to increase pollution controls, while new sources could face stricter regulations. The EPA could sanction the state by withholding highway funds.
Yellowstone Valley has seven main industrial sources of sulfur dioxide – three refineries, two power plants, a sugar beet plant and a sulfur-recovery plant. In 2010, EPA imposed a new, stricter hourly standard to better protect children, seniors and people with asthma from the gas, which is produced by burning fossil fuels such as coal and oil.
EPA’s proposal is based on a review of 2009-2011 information from the Coburn Road monitor, which is the valley’s oldest continuous air quality monitor. The Coburn Road monitor was installed atop Sacrifice Cliff in 1981. Compliance with the standard is based on three consecutive years of information.
The Coburn Road monitor exceeded the hourly standard three times in 2009, nine times in 2010 and three times in 2011. In addition, the monitor exceeded the standard six times in 2008 for a total of 21 times from 2008 to 2011.
EPA, Klemp said, maintains that 2010 emissions were representative of a normal year, “and that’s just not true.”
In 2010, emissions from the ExxonMobil refinery, in Lockwood, increased because the refinery was testing additives to control sulfur dioxide as required in a separate EPA enforcement settlement, Klemp said. And increased emissions in 2008 also were from additive testing, the state said.
Emissions in 2009, 2011 and 2012 represent “similar and consistent operating conditions, reflect future operations and clearly establish a trend maintaining” the national standard, DEQ’s response said.
The state also expects further sulfur dioxide reductions with PPL’s announced plan to mothball its Corette power plant in 2015, DEQ said.
Historically among the biggest sources of the valley’s pollution, Corette’s 2012 emissions of 1,884 tons were down 21 percent from 2,271 tons in 2010, making it the second biggest source behind Montana Sulphur & Chemical Co. MSCC’s sulfur dioxide emissions in 2012 were 1,935 tons.
EPA earlier rejected DEQ’s argument, saying there were violations in 2011, when ExxonMobil’s controls were working properly. The Coburn Road monitor violations appeared to be the result of emissions from all sources in the Billings/Laurel area and not just ExxonMobil, EPA said.
EPA intends to issue its final decision on “nonattainment” areas in early June.