The Denver Broncos may build the team’s next stadium near a Superfund site.
Burnham Yard, a former train depot linked to the Broncos as a potential site for a new football stadium, is not part of the 46-year-old Denver Radium Superfund Site, but it sits across railroad tracks from at least one property with existing contamination.
And at least one nearby parcel purchased earlier this year by business entities connected to the Broncos was once part of the Superfund site, according to a 2014 report from the Denver Department of Public Health and Environment.
Santa Fe Yard, which will be the future home of the Denver Summit professional women’s soccer team, is in a similar situation. That site sits across Interstate 25 from land that has ongoing mitigation for radium contamination and is part of the Superfund site. But the former railyard does not have any known radium underground.
Environmental experts, however, say the proximity to a radium Superfund site would not be a danger to the teams or their fans. Radium is a radioactive element that is found in nature, including underground in Denver, and, if mishandled, it can cause human health problems, including cancer.
“I can say definitively people would be safe at Broncos games,” said Thomas Albrecht, a chemistry professor at the Colorado School of Mines.”No Spider-Mans or Hulks.
“If they plopped a stadium on the ground right now, even a permanent employee would be fine. I would not fear it at all.”
Radium is easy to detect and there are proven ways to remove it, Albrecht said. And multiple federal, state and local environmental agencies would be involved if any radium was detected where the Broncos might want to build.
“The beauty of radioactive elements is radiation can’t hide,” he said. “It’s extremely easy to detect and it’s easy to detect in high precision.”
Radium remediation is expensive because waste material must be hauled long distances to approved landfills. But figuring out who would be responsible for any contamination lingering around Burnham Yard is to be determined, especially since the Broncos have never confirmed they are eyeing the railyard as the team’s future home.
“They may decide they don’t want the expense,” Albrecht said. “That’s a completely different issue. They’re completely capable of putting the stadium there and cleaning it up.”
The Denver Radium Superfund Site was designated by the Environmental Protection Agency in 1979 after spoils from the National Radium Institute and other radium mining, processing and disposal sites that operated in Denver around the turn of the 20th century were found scattered around the city.
Once the EPA declares a site as a Superfund, the agency has the authority to clean up contamination and pursue reimbursement for that work.
“In the early part of the 1900s, they didn’t have environmental standards and just threw out the waste,” said Benjamin Rule, the EPA Region 8 remedial project manager for Denver Radium Superfund Site.
While those radium businesses were shuttered by the mid-1920s, their radioactive waste has lingered in the city for more than a century.
The main health risk associated with the former radium businesses is residue from radium-226, a radioactive element that breaks down to form radon gas, which causes lung cancer with long-term exposure, according to a 2023 EPA report about the Superfund site.
The Denver Radium Superfund Site is unusual in that it is not confined to one location within the city limits. Instead, it stretches from Cheesman Park near the city’s center to the Overland Golf Course in southwest Denver.
The site covers 65 individual properties that the EPA subdivided into 11 areas, known as operable units. That’s because the EPA broke the site into geographic areas that followed the South Platte River and the rail lines through Denver, Rule said.
Only one of those 11 operable units remains under direct EPA oversight — groundwater beneath the Overland Golf Course at 1801 S. Huron St., which is about a mile from Burnham Yard. It would not impact any development at the former train depot, said Branden Ingersoll, a spokesman for the Colorado Department of Public Health and Environment’s Hazardous Materials and Waste Management Division.
But two parcels near the potential stadium sites have designations that could limit development and land use. The EPA, as well as the city and state health departments, would be involved in any remediation and development decisions surrounding those properties with lingering contamination.
Atlas Metals & Iron, a scrap metal and recycling company at 1100 Umatilla St., sits directly west of Burnham Yard, separated by a set of railroad tracks. Between 1991 and 1993, 89,000 tons of contaminated material were removed from the property, but contaminated soil remains, Ingersoll said.
The radium in the soil is not dangerous to people as long as Atlas maintains its parking lot and its buildings’ floors, which serve as a cap to hold back the contamination, Rule said.
Atlas has a covenant with the EPA and the state health department to maintain the cap, and the site undergoes a review every five years.
In the most recent five-year report, published in 2023, the EPA noted that Atlas recorded increased radon levels in 2018 and 2020 after installing a new heating and cooling system, but those levels returned to normal after the company modified its system and repaired a radon-mitigation system.
Under the covenant, Atlas Metals must receive approval before seeking building permits or a change in land use. It also must notify the state if the property is sold to someone else, according to the covenant.
No ties have been established between the Broncos and Atlas Metals, but the scrapyard would be next door to any future stadium or entertainment district if the Broncos choose to relocate to Burnham Yard.
While Atlas Metals chief executive officer Mike Rosen declined to comment for this story, the EPA report noted that Rosen “is impressed by how his company has been able to succeed with a solid reuse of a Superfund site. He believes that there has been great collaboration with the CDPHE and the EPA throughout the cleanup process.”
The remarks illustrate how private businesses are able to work with government agencies to make land safe for people.
Patrick Smythe, a Broncos spokesman, said the team’s owners continue to study all stadium options, which include staying where Empower Field at Mile High is located and reviewing additional sites in Lone Tree and Aurora.
Another parcel acquired this year by a business entity linked to the Broncos — 1241 to 1245 Quivas St. — was part of the radium Superfund site but has been cleaned. There are no radium concerns on the property, Ingersoll said.
Burnham Yards also borders another area that was part of the Superfund cleanup — an alley between Mariposa and Lipan streets that runs from Fifth Avenue to Sixth Avenue. That site was remediated after 2,800 tons of soil were removed, according to online reports. There are no development restrictions, Ingersoll said.
There is no apparent connection between the Broncos and any addresses around that alley.
The property closest to the future National Women’s Soccer League stadium is the Home Depot at 500 S. Santa Fe Drive, which is across I-25 from where the stadium and associated entertainment venues will be built.
The Home Depot’s radium situation is almost identical to the one at Atlas Metals — as long as the parking lot remains paved and no one digs into the ground, the radium is contained, Rule said. The Home Depot also has a covenant with the EPA to contain the radium and undergoes an inspection every five years.
Still, Rule said he reached out to the new soccer team’s ownership once the stadium location was announced to explain the nearby Superfund sites and the EPA’s role.
“Santa Fe Yards are not technically on Superfund property and it’s not a direct concern,” he said. “But Home Depot is just north on I-25.”
Before a stadium can be built at either location, extensive environmental surveys will be conducted to make sure there is no radium or other contamination left behind from former industrial uses. Federal and state laws require it.
“The EPA carries a big stick,” said Andrew Ross, the Denver health department’s senior environmental administrator with environmental land use and planning.
Banks involved in financial loans tied to the properties also would want any contamination removed to avoid liability, Ross said.
“We’re here to help developers through these processes,” Ross said. “It’s on the developers to figure it out.”
The residents in the La Alma Lincoln Park neighborhood next to Burnham Yard are excited about potential redevelopment that would make good use of an old railyard, but they also are aware of all the potential environmental hazards surrounding the site, said Nolan Hahn, president of the neighborhood association.
“There’s always a concern that when you disturb the soil in the area that you can release toxic materials,” Hahn said. “We just want to make sure it is done in a way that doesn’t put us in more danger and respects the people of the neighborhood.”
Denver Post staff writer Jessica Alvarado Gamez contributed to this report.
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