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Xcel Energy's Pawnee Generating Station is pictured among agricultural fields as seen from Interstate 76 on February 12, 2020, near Fort Morgan. (Andy Colwell, Special to The Colorado Sun)

Xcel Energy’s coal-fired Pawnee Generating Station near Fort Morgan is endangering local residents’ health by violating EPA sulfur dioxide emissions standards for hundreds of hours a year, a conservation coalition asking the state to sharply curtail plant air pollution permits said Friday.

The coalition used EPA pollution-monitoring data to support its claim that Pawnee often pumps out up to four times the hourly limits of SO2, which can cause asthma and other acute respiratory problems in people who live near power plants. The coalition also conducted its own modelling of Pawnee to claim that if actual EPA emissions data is used, the plant is likely violating hourly limits thousands of times each year. 

The conservation groups claim the state Air Pollution Control Division, which issues emission permits with set caps to companies like Xcel, created a rolling monthly average for Pawnee’s SO2 limits that violates EPA standards and which the EPA never approved. This allows Pawnee to release short-term pollution well above safe limits, during high energy demand or when pollution filters are not working, while still meeting monthly averages, the groups say. 

The state’s failure to model pollution properly or factor in actual past emissions data threatens “the health of the people of Colorado and violates the letter and the intent of the Clean Air Act” and other EPA rules, according to a letter to the state from the coalition. The group includes the Colorado Sierra Club, Green Latinos, WildEarth Guardians, the Center for Biological Diversity and Public Employees for Environmental Responsibility. 

The EPA’s system for monitoring actual emissions data reported by large polluters showed Pawnee violating the state’s “allowable” emissions rate for SO2 during 149 hours of 2019, and 200 hours in 2020, the coalition said. But because the state allows Pawnee to average out the emissions over longer periods, the spikes happened without “any consequence or any action taken by CDPHE to correct that situation,” the coalition’s letter to the state says. 

The coalition said the air pollution officials’ omissions in overseeing permits at Pawnee are part of a pattern, which includes allegations from state internal whistleblowers earlier this year claiming regulators favor the needs of industries over the health of residents. 

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This is the third major pollution source where the coalition has paid for its own emissions modelling that they believe follows EPA rules much more carefully than the state’s modelling has done, said Ramesh Bhatt, chair of the Colorado Sierra Club’s conservation committee. Previously, the coalition’s independent modelling claimed that the rebuilding of Interstate 70 through north Denver would result in more particulate pollution than the state health and transportation departments accounted for. More recently, the group modeled pollution at the Suncor refinery, and claimed it would exceed both state predictions and EPA limits. 

“These things are coming to the fore. People are understanding that we are being subject to pollution unnecessarily,” Bhatt said. “We’re hoping that the EPA will obviously work on each of these issues, but also look at it kind of holistically.” 

Xcel said it has updated SO2 reduction at Pawnee to be “state of the art” and that the company is in compliance with permits.

“Based on our analysis of emissions data and other information related to the operation of the plant, we disagree with the conclusions of the conservation organizations’ report,” said Xcel spokesperson Michelle Aguayo, in a statement. “We do not believe that Pawnee is causing or contributing to any national ambient air quality exceedance near the plant. We will of course work closely with the State of Colorado and EPA as they evaluate this and any other air quality issue in our region.”

State air pollution officials said in a statement  they had not yet seen the new modelling data from the coalition, but added, “In evaluating the modeling submitted for these facilities, we followed stringent EPA guidelines and modeling protocols for each facility. When the EPA updates guidelines, we update our protocols. As a result of actions taken at the state level and local level, sulfur dioxide emissions from these facilities have been declining steadily.” 

Xcel announced earlier this year it plans to convert Pawnee to cleaner natural gas fuel by 2029. 

In the meantime, the 505-megawatt Pawnee plant puts out the heavier pollutants and greenhouse gases from coal, including SO2. 

The EPA has “nonattainment areas” for pollutants in many states, including a nine-county area on the Front Range for ozone pollution, where companies and local governments controlling auto use are subject to extra rules meant to cut emissions. Morgan County, where the Pawnee plant is located, is not included in the Colorado nonattainment area.

There is no EPA nonattainment designated area, or the extra layer of rules that might come with it, for SO2 in Colorado. There are such areas in states with a higher concentration of power plants and other large SO2 emitters. The conservation coalition would like Pawnee and other power plants to be drawn as nonattainment areas for SO2. Failing that, they say they want the state’s annual SO2 report to accurately reflect how much Pawnee is polluting, and then to alter Xcel’s Pawnee permit to eliminate the dangerous short-term spikes in the toxic gas. 

The group also wants state air pollution regulators to clear their modeling and calculations with the EPA before finalizing future permits, arguing that Colorado is not allowed to make its own interpretations of Clean Air Act rules and toxic limits, or choose which time periods are most important. They cite a case in Wisconsin, where the state thought a power plant was underestimating SO2 emissions, and received explicit EPA approval for its alternative model with stricter standards.

Xcel has alternatives to sharply lower its Pawnee SO2 and other emissions, said Robert Ukeiley, Colorado counsel for the Center for Biological Diversity. It could switch to natural gas, or cleaner-burning coal, sooner than its announced plans. Xcel could add backup scrubbers, so that SO2 and other pollutants are not being spewed just because one set goes offline. State regulators in their permitting process have power to shape and alter plant operations or require cleaner equipment. 

Or, Ukeiley said, “they could shut down the plant. That would be the best choice.”

Until then, the state needs to take action, members of the coalition said. “Their job is to follow the science and provide people with the protection they need, which is clean air all the time, not just some of the time,” Ukeiley said.

Michael Booth is the Sun’s environment writer, and co-author of the Sun’s weekly climate and health newsletter The Temperature. He is co-author with Jennifer Brown of the Colorado Book Award-winning food safety investigation “Eating Dangerously.” Booth was part of teams that won two Pulitzer Prizes for breaking news. He also writes frequently about inexplicable obsessions that include tamarisk, black-footed ferrets and tire fires. Booth also serves as the underpaid driver for four children, and plans to eventually hike every inch of Colorado.