Colorado landfills have been illegally burying low-level radioactive waste from the oil and gas industry that they are not approved to handle, state health officials revealed this week.

State health regulators, confirming at a meeting with local governments the disposal of unknown amounts at ordinary landfills, are trying to prohibit the practice and buttress their oversight. Colorado’s booming oil and gas industry produces millions of tons of waste, some of it radioactive, and both waste producers and landfill operators are obligated to handle it properly.

“There is some of it that is just going to solid waste landfills. … It is probably, mostly, staying in state,” Colorado Department of Public Health and Environment hazardous materials and waste management director Gary Baughman said at the meeting Wednesday.

CDPHE regulators said they don’t know of any “imminent” threat to public health, noting that landfill operators must monitor water that leaches through waste.

But state officials asked cities and counties to help stop improper disposal of the industry’s so-called technologically enhanced naturally occurring radioactive materials (TENORM) — sludge from filter bags, pipelines and storage tanks, and possibly drill cuttings. Radioactive materials can cause cancer.

Landfills authorized to accept radioactive materials must use liners and other protective barriers to protect land and water. All landfill operators must ask waste haulers to characterize their loads, especially if they could hurt public health and the environment.

CDPHE environment programs director Martha Rudolph said lawmakers must help by fixing a glitch in state laws. A solid waste statute requires CDPHE to prohibit disposal of radioactive waste at landfills not designed and designated to handle it safely. CDPHE also is charged with regulating radioactive materials. But a provision in the radioactive materials statute says CDPHE cannot regulate disposal of those materials.

Lawmakers should give clarity by removing that last provision, Rudolph said, and CDPHE then would create a new rule for putting low-level radioactive waste in landfills after hearing from companies and Colorado residents.

Today, only two landfills are approved to accept low-level radioactive waste routinely. And a new, specialized Pawnee Waste facility east of Fort Collins is being built, with 350,000 cubic yards of dirt excavated so far, to dispose of up to 15 million tons of the oil and gas industry’s radioactive waste. Pawnee officials said they’ll open it in November and that plastic liners, clay barriers and electronic leak-detection sensors will protect land and groundwater.

Oil and gas companies in Colorado, extracting fossil fuels from more than 55,000 wells, generate roughly 500,000 tons of solid waste per year, including low-level radioactive waste.

“It is in the industry’s best interest to mitigate long-term risks. And it is in the public’s best interest. This radiation lasts for a long time,” Pawnee project manager Jane Witheridge said. “If we don’t treat it differently from municipal solid waste, we would not be serving either the industry or the environment as it should be in Colorado. This is being done in North Dakota. It is being done in Texas.”

The Pawnee landfill “will be a great place to send” radioactive waste “but it is probably not enough” to handle all the waste the industry is likely to produce in the future, said Joe Schieffelin, CDPHE’s solid waste program manager. “That’s one of the pieces of information we are trying to get from the oil and gas industry.”

CDPHE regulators don’t know how much low-level radioactive waste has been disposed of improperly at landfills, Schieffelin said. “We don’t have information on the concentrations, either,” he said.

Operators of existing landfills have raised questions about CDPHE’s push for “a rule-making” to govern disposal of low-level radioactive waste in landfills. State officials told Front Range local officials from Weld County and as far south as Trinidad that they view them as partners in making sure landfills are safe. Once CDPHE approves landfills, local governments issue permits that let the landfills receive waste.

Waste Management Inc. officials, who run seven landfills in Colorado, said Thursday that they are collaborating with CDPHE and others to clarify procedures related to disposal of naturally occurring radioactive material, which is present everywhere.

“Waste Management of Colorado does not accept low-level radioactive waste,” company spokeswoman Isha Cogborn said.

The Colorado Oil and Gas Association, a fossil fuels industry trade group, did not respond to questions, but it issued a statement indicating COGA doesn’t see disposal of low-level radioactive waste in landfills as a problem.

“While circumstances may be different in other states, there have been no indications this is an issue for oil and gas waste in Colorado,” reads the statement attributed to COGA president Dan Haley. “We have spoken with the state, with members of the waste industry, and others to begin exploring the realities of this matter.”

Some companies have approached Pawnee about using the new landfill.

It is unclear whether CDPHE is taking enforcement action in cases where radioactive waste was buried illegally in unapproved landfills.

A May 12 letter from Schieffelin to landfill operators alerted them that CDPHE “has become aware of a potential issue” of landfills accepting waste containing radioactive material. Landfills cannot accept such waste “unless a landfill is specifically designated for that purpose,” the letter said.

“By accepting TENORM in general and (industry) exploration and production TENORM waste in particular, your landfill could be in violation of the law. Many sites are not characterizing potential TENORM materials and, therefore, the department is concerned that many sites may be unknowingly in violation.”

Legal responsibility shifts from waste generators to landfill operators once waste is accepted. If improper waste hasn’t been characterized accurately, the landfill operator can seek remedies from waste generators.

Only Clean Harbors landfill in Adams County and the Southside Landfill in Pueblo County are approved to routinely handle low-level radioactive waste, CDPHE records show.

In 2016, Pawnee got approval from CDPHE and Weld County for its landfill designed to handle radioactive waste. Pawnee officials say it will protect groundwater against radioactive contamination with a high-density polyethylene synthetic liner and clay barriers. The waste would be buried in containers, with electronic sensors to detect leaks, all kept at least 20 feet away from groundwater.

Some landfills recently received case-by-case approvals from state or local authorities to dispose of oil and gas industry low-level radioactive waste, Baughman said.

“It has become clear that what we have out there is an un-level playing field at solid waste landfills,” he told local government officials.