The cancer-causing chemical trichloroethene has been detected spreading from Cotter Corp.’s defunct Colorado uranium mill, contaminating groundwater at concentrations up to 360 times the federal health limit.

State regulators Friday confirmed this new element in the toxic and radioactive waste from the mill, adjacent to Cañon City, and said they’ve asked Cotter to investigate.

“It’s in the groundwater. It’s not in the public drinking water supply that we know of,” said Jeanine Natterman, a spokeswoman for the Colorado Department of Public Health and Environment.

Cañon City’s 16,000 residents, many of whose wells already are tainted, received no notification.

“Nothing surprises me anymore,” because the plant “is like an octopus with 20 arms,” said Sharyn Cunningham, 64, who lives 1 1/2 miles away and co-chairs Colorado Citizens Against Toxic Waste.

“This year, I’m not doing any gardening. They’ve been doing demolition out there, and I don’t trust the soils anymore.”

Cotter employees apparently detected the trichloroethene, used to remove polychlorinated biphenyls (PCBs) in the 1980s, in water samples taken in October, according to documents filed last week with state regulators.

Cotter officials declined to comment.

The documents indicate that Cotter, a subsidiary of San Diego-based General Atomics, tentatively plans to initiate groundwater sampling in May to determine the amount of trichloroethene and its spread.

They’ve accelerated dismantling of old structures and declared an intention to re-engineer and reopen the mill while also, at the end of March, submitting a required decommissioning plan. Last week, Cotter also disclosed sampling and monitoring errors from last year at its lab caused by equipment problems.

Starting in 1958, Cotter processed uranium for weapons and fuel at the mill. Liquid waste laced with radioactive material and heavy metals was discharged into 11 unlined ponds from 1958 to 1978. Those were replaced in 1982 with two lined impoundments. After well tests in Cañon City showed contamination, federal authorities placed the mill on a national list for Superfund cleanups.

The cleanup is slated for completion in 2027.

The chemical trichloroethene is known to cause damage to the liver, kidneys, nerves and circulatory systems if ingested or inhaled in large quantities. The federal Environmental Protection Agency has regulated the chemical since 1989 with water suppliers required to test for it and remove it from drinking water.

Cotter documents show that samples collected from four wells north of the mill in October, analyzed at outside labs, indicated trichloroethene concentrations of 1,800 parts per billion, 1,200 ppb, 490 ppb and 386 ppb. The EPA standard is 5 ppb.

“Vapors can seep up through the soil and get into homes. Then you have not only a drinking issue but an inhalation risk,” EPA spokeswoman Sonya Pennock said.

“We need to find out how much there is and where it is. Then you would make a decision as to whether people could be exposed to it.”

Some residents now are questioning the government’s ability to protect them.

“We wish the health department and the EPA would take the initiative to do more of their own sampling, as quality assurance, to make sure we’re getting correct analysis. Our community has asked and complained about that for years,” Cunningham said.

“We’d like to see Cotter be required to actually clean up the groundwater.”

Bruce Finley: 303-954-1700 or bfinley@denverpost.com