Analysis of soil samples taken along the route of a planned toll road around the former Rocky Flats nuclear weapons plant show radioactivity levels well within regulatory limits, according to a report from the Colorado Department of Public Health and Environment (CDPHE).
The agency shared major findings of its 28-page study last month with entities such as the Jefferson Parkway Public Highway Authority and the Arvada City Council.
The regional Highway Authority is in charge of building a 10-mile toll road to improve traffic flow around metropolitan Denver and northern Colorado by connecting Interstate 25 and Interstate 70.
The study was prepared in response to an elevated sample reported by the parkway authority in August 2019, with 264 picocuries per gram (pCi/g) of plutonium – more than five times the 50-picocurie level typically considered safe.
All other sampling results were near or below previously detected levels, the CDPHE said in its report. Nonetheless, the single high result sparked concern over the potential radiation dose from plutonium that a construction worker or a nearby resident could receive during project construction.
The state agency had experts from Colorado State University analyze 467 soil samples from the parkway footprint, which passes through the Rocky Flats Plant’s former security buffer zone.
But even in a nearly worst-case scenario, the report found a construction worker would be exposed to 11.52 millirem per year. The highest calculated dose to a nearby resident was about 2.6 millirem per year, neither of which would pose an “undue hazard to public health from a radiologic hazard perspective,” the agency said. The scenario was based upon more of the very high level samples being present at the site.
With the positive report from the state agency, he Jefferson Parkway Public Highway Authority will use the coming weeks to determine its next steps, the authority said on its website. Two private partnership groups have previously been deemed by JPPHA as qualified to design, build, and operate the Jefferson Parkway.
From the 1950s until 1989, Rocky Flats manufactured fissile plutonium cores for nuclear weapons. The Energy Department certified it had completed the $7 billion remediation at the site in 2005, and it is now monitored by DOE’s Office of Legacy Management.
