This story is part of a collaborative journalism project between Boulder Reporting Lab and the Center for Environmental Journalism at the University of Colorado Boulder. Read the main story, Hidden hazard: Boulder’s million-ton coal ash problem has no local watchdog, and a summary of key takeaways.
Next year marks the 100th anniversary of Xcel Energy’s Valmont Power Station, the hulking facility that sprawls hundreds of acres on the eastern edge of the city. Growing alongside Boulder to provide its energy needs, the station also illustrates the larger story of coal burning in the United States.
From its beginnings in the 1920s, when coal burning was lauded for its generation of electricity and prosperity, to the 1970s, when Boulderites rebelled against the dark smoke rising from the smokestacks, Valmont helped Boulder transform from a tiny university town and vacation destination to a research behemoth and technology hub.
Today, the Valmont Power Station no longer burns coal. It has shifted to generating natural gas — another fossil fuel — along with a smattering of solar. Like power plants throughout the country, this transition away from coal was intended to promote cleaner energy options and emphasize the urgency of addressing climate change. But the coal phaseout has not yet triggered the abandonment of fossil fuels scientists say is necessary to avoid irreversible and catastrophic damage from climate change.
And similar to other plants across the nation, Valmont has a legacy of chemical waste called coal ash that it has to address. Until now, that ash has received little scrutiny in Boulder. In collaboration with the Center for Environmental Journalism at CU Boulder and several graduate student reporters, Boulder Reporting Lab has been examining this issue for months.
Read — Hidden hazard: Boulder’s million-ton coal ash problem has no local watchdog
It’s worth understanding the historical context of this waste, however, given how important coal was in propelling Boulder into modern life.
Steam over hydroelectric
In 1920, Boulder had a population roughly 10% of what it is today. Though the University of Colorado had been open for 43 years, it had just one building for much of that time. The Hotel Boulderado had also been around for more than a decade by then, hosting galas and visitors to Boulder who were perhaps related to CU’s scholars or attending lectures and films presented at Boulder’s Colorado Chautauqua.
In 1921, just after women gained the right to vote and prohibition took hold, the Public Service Company of Colorado — which would eventually fall under the control of Xcel through a series of mergers — began surveying to decide where to build a new steam power plant. Electricity demands in Boulder and Denver were increasing due to population growth and new electric appliances like refrigerators, leaving the state’s hydroelectric plants, like the one up Boulder Canyon at Barker Dam, strained.
In 1923, the same year Macky Auditorium at CU was built, Public Service hired engineers to decide whether to double down on hydroelectric plants or move into coal burning, according to a Daily Camera article from the time. “Their conclusion was that steam generation of electricity in this territory will be more economical than water power development for years to come.”
The 600-acre property in east Boulder that would eventually house Valmont had several advantages. One was its proximity to the coal fields of northern Colorado that offered coal in “almost inexhaustible quantities” via a relatively short railroad commute. The property was also centrally located within the Public Service Company’s service area that included Boulder, Denver and Fort Collins.
Finally, a steam-based power plant requires a considerable amount of water for both steam production and cooling purposes, which is why plants of that size were normally built along rivers where large volumes of water were available. And by expanding an existing body of water — then known as Boulder Lake and now comprising three reservoirs named Valmont, Leggett and Hillcrest — with an 80-foot high dam, the power plant would have the water available to evaporate 230,000 pounds of steam an hour.
At the Valmont plant’s inception, it consumed as much water each day “as a city the size of Denver,” according to the same article that listed its steam capacities.
Construction began in 1923, with the plant firing up on Nov. 30, 1924, when local residents were encouraged to “beware of the wires.” At the time it was “the largest steam generating station on an artificial body of water west of the Missouri river,” the Daily Camera wrote. The smokestack, a point of pride highlighted in newspaper articles, was the tallest in Colorado at 372 feet. The cost of construction to get the first turbine up and running came to roughly $5 million. Adjusted for inflation, the project would cost $89 million today.
When the plant first opened, its single turbine was able to produce 20,000 kilowatts a day. If operating at full capacity, it could burn through 480 tons of coal a day, but the expected average was less than half that. (By the 1960s, the plant was burning nearly 10 times that amount daily.)
In a small town newspaper feel rarely seen today, a news article listed the names of men working at the new plant, assuring readers that, “most of the operating staff are married and have located their families in Boulder.” While some men still lived in Lafayette “motoring back and forth each night,” the article continued that “it is thought that [the workers] will move to Boulder soon.” It seems there was a concern at the time about excessive commutes.
Throughout the 1920s, Public Service continued spending money on the plant, adding more boilers and increasing the amount of coal burned and energy produced as Boulder and the surrounding towns the plant served, including Denver, grew. In the late 1920s, newspaper articles boasted about Valmont setting records for burning coal. In 1930, a new boiler, one of “the largest in the country,” was installed that burned 20 tons of coal an hour all by itself. The remaining 1930s passed with the plant adding more generators — and the ability to burn natural gas — to provide power to a continually growing Front Range.
In September 1942, less than a year after Pearl Harbor and just after the U.S. invasion of Guadalcanal, armed guards were stationed at Valmont. Fearing the undermining of America’s energy production by international adversaries, a newspaper clip from Sept. 12 states that guards for the power plant were sworn into the army “as the U.S. Army took over the supervision of the guards of utility plants as well as defense factories over the nation.” The guards would go to basic training and receive instruction on “anti-sabotage work and shooting.”
In 1948, as the United States entered a stretch of post-war prosperity, a newspaper article said that in the previous year, an average of 1,100 tons of coal were burned daily at Valmont.
A year later marked 25 years since the plant turned on, and several newspaper articles celebrated the event, stating that in the past quarter-century, more than 5.5 million tons of coal were burned at the plant. And already by that time, almost 33 billion cubic feet of natural gas had been burned there.
Yet soon after this quarter-century celebration, criticism of the plant began to populate news clips.
Environmental concern begins
In the early 1950s, newspapers were still reporting when gardens around the Valmont plant were “at their prettiest.” And a newspaper clip from 1964 — by which time Valmont was known as “Grand Old Lady” to Public Service employees — reported with fanfare that a new coal burning unit, combined with the others already in place, would have an annual coal consumption of more than 500,000 tons, coming to a daily use of almost 1,400 tons.
Yet a couple years later, in 1966 — just after Rachel Carson’s Silent Spring illustrated some of the impact humans were having on the natural world — the Public Service company held open houses so the public could get a first-hand look at the “electrostatic precipitators” that executives falsely claimed eliminated air pollution from the plant “almost completely.” The same article also explains that carbon dioxide, sulfur oxides and carbon monoxides still escaped from the smokestacks.
In 1970 — the same year the Environmental Protection Agency was formed, the first Earth Day celebrated and the Clean Air Act passed — the Public Service Company started showing up in court asking for exceptions, or “variances,” to state pollution guidelines, according to clippings. At such hearings, children and adults paraded in the courthouse “with posters made by children bearing drawings of power plants emitting great black clouds of smoke and the caption ‘It stinks,’ and ‘my nose knows, does yours?’” Picketers outside the courthouse also sported signs that called the Public Service Company “a publicly owned futility.”
The hearings about Public Service earned a statement from the Colorado Department of Health that said testing of the fumes rising from Valmont had been inadequate, and that “it is evident to the state Health Department that [Public Service] has been, and remains, a major and substantial polluter of the atmosphere.”
The change in sentiment towards burning coal showed further in 1972, when Valmont had to fire up its previously retired, less-efficient coal-burning units. The Cherokee Power Plant, a behemoth that today generates almost five times the energy of Valmont, was built in 1968 to serve the needs of Denver. Cherokee went down for a spell in 1972, requiring Valmont to provide energy again for customers it had since passed on to Cherokee. “The thick, black smoke belching out of the smoke stacks” a picture caption in a news article reads “was coal dust, and it will be around for a while.”
That same year Public Service received multiple citations for “excessive pollution.”
To combat this pollution, a $2.5 million “scrubber” was activated at Valmont. But not 10 years passed before the equipment, meant to drastically reduce the amount of pollution put off by the plant, had become a “monthly problem.”
“There were a lot of shortcuts in the initial installation,” admitted the then-superintendent of the plant. Not long after, the director of environmental research and planning for Public Service was calling pollution guidelines “unrealistic.”
“Standards should be set,” he said, “but not just some number that sounded good to somebody at some time.”
Even with environmental concerns growing, in 1981, the plant was still burning upwards of 55,000 tons of coal a month, or 1,800 daily. The largest turbine, however, was the only one still running exclusively on coal. The older and smaller turbines had been converted to burn natural gas. Even then, those older turbines were only used when Front Range residents needed extra energy. Xcel built its Unit 5 generator that took over the entirety of coal burning at Valmont by 1986, when the four original units were retired.
Not many stories were written about the Valmont plant for a few decades. But in 2006, Hurricane Katrina happened and Al Gore’s An Inconvenient Truth came out raising the alarm about unabated climate change. A few years later, in 2009, hundreds of Boulderites voiced their displeasure about Valmont at the Boulder County courthouse and urged the state Air Quality Control Commission not to renew the power plant’s Title V air permit.
This did not persuade the Air Quality Control Commission, which approved Valmont’s permit. Yet in 2010, Xcel began contemplating an early closure of its coal-burning operations.
It’s fair to say that pushback from Boulderites — protests came in late 2009 and 2010, along with studies revealing the far-reaching impact of coal emissions on areas beyond the plant’s immediate vicinity — had an impact.
But the Clean Air – Clean Jobs Act, signed into law by Colorado Governor Bill Ritter in 2010, was the needed regulatory push. Valmont stopped burning coal in 2017, to comply with the law, which, among other things, required Xcel to cut its emissions of nitrogen oxides by 70% to 80% at its three coal-powered plants from 2008 levels.
Xcel’s website says Valmont currently has three working natural gas combustion turbines and two solar arrays. Valmont has also been relegated to a “peaker” plant, meaning it only turns on when other resources aren’t available. In 2022, for instance, it only produced electricity eight of 12 months. And in 2023, according to a data set that ended in September, it had only produced electricity in two of the nine included months.
Natural gas may not release black belching clouds from smokestacks, but it’s still warming the planet. A 2018 study found that the methane leaking from natural gas extraction sites and pipelines undermines the assertion that natural gas is a cleaner alternative to coal. In the short term, the leaking methane causes more warming than burning coal due to methane’s impressive heat-trapping effect.
And coal ash remains. Over decades, the ash — a byproduct of coal burning that contains toxic heavy metals — was disposed in several nearby landfills and storage ponds on the property. Some was sold to increase the strength of concrete, but not all of it. According to one article from 1930, some 7% of the coal consumed was left as ash. In a plant that burns tons of coal every hour, that’s a lot of ash leftover.
In 2018, Xcel removed all coal ash from its ash storage ponds, relocating it to a dry landfill that sits adjacent to three reservoirs, before following federal rules for closing the ponds. Chemicals from ash in the landfill are leaching into Boulder County’s groundwater, according to data reported by Xcel. The plant’s next chapter, of restoring Valmont to its pre-coal ash condition, now awaits.
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