The discovery of low-level radioactive waste 7 to 12 feet in the ground off DP Road last month prompted the state Environment Department to write a letter that ordered the agency to supply more information about the waste, how it got there and how the agency planned to avoid future incidents.

The state agency is “extremely concerned” about the contamination unearthed on a former Los Alamos National Laboratory site and “the potential threat to human health and the environment,” wrote Kevin Pierard, the department’s Hazardous Waste Bureau chief, in a Feb. 28 letter.

Pierard demanded Energy Department and lab officials submit data on the site and the sources of contamination, as well as tests and investigations that were conducted.

“We are currently investigating and characterizing the waste located at the site to determine the extent of the contamination,” Energy Department managers wrote in response.

The waste was placed in three drums and moved to another site for further analysis, the Energy Department said. Crews have fenced off the construction site, covered it with tarp and posted signs to keep people out, the letter said.

Then last week, the Energy Department delivered hundreds of pages of documents to the Hazardous Waste Bureau in response to Pierard’s order. The New Mexican has submitted a records request to the bureau to view some of the documents.

The contaminated site comprises 70 acres on which Ohio-based Bethel Development aims to build 72 units of affordable housing by the end of this year and 60 units of senior affordable housing next year.

In the late 1990s, then-U.S. Sen. Pete Domenici drafted legislation that enabled the federal government to transfer properties — including lab sites — at no cost to the county, which needed more land on the mesa to grow, County Manager Harry Burgess said.

In 2018, the county received the 70 acres now being developed.

The transfer also includes 100 acres of more severely contaminated land in Technical Area 21, where plutonium was processed in the 1950s.

Cleanup is scheduled to go until 2026 on the former plutonium site, which will then be given to the county, Burgess said. Plans call for developing that land at the end of DP Road for industrial and commercial use, he added.

Deeds say the Energy Department is responsible for cleaning up and disposing of all waste on the properties, Burgess said.

This land transfer falls under a 2005 consent order that requires the state to ensure all land conveyed to the county is clean and safe, Burgess said. That consent order was revised in 2016 under then-Gov. Susana Martinez to remove state oversight on the Energy Department’s land transfers, he said.

A watchdog group expressed concern about waste being discovered at a construction site that state and federal agencies had deemed clean.

“The waste is turning up on land that wasn’t supposed to have anything,” said Scott Kovac, research and operations director for Nuclear Watch New Mexico. “So what are the chances of the ex-plutonium site being cleaned up to standard?”

Within the former plutonium site are a couple of disposal areas for radioactive waste, including a one-acre spot where contaminants are so concentrated they would be difficult to remove, Kovac said. A developer might have to cap and cover that spot and build around it, which likely would limit what could be put there, he said.

Burgess said the county will look at the best options for dealing with the waste.

“I think the reality is, given the history, there may be places here that some might view as cheaper to leave it there as opposed to dig it up and take it away,” Burgess said.

Pierard said the state wants more data on the construction site where the waste was found to get a clearer idea of how it was missed.

The Energy Department presented historical studies of the site, which were based on monitoring that was done between five and 10 feet underground, Pierard said.

Apparently, they needed to probe deeper, he said.

“We were obviously very concerned about this,” Pierard said. “Our expectation is they’re going to do a little more study in that area.”