Rocky Flats workers inspect plutonium storage vault in building 707. They use the automated X-Y retriever to sort and retrieve plutonium metal from the storage vault for distribution to other processes in the building. Energy Department
A wildlife corridor plans to connect two Superfund sites at the former Rocky Flats plutonium plant and the Rocky Mountain Arsenal that once produced chemical weapons. Locals fear residual contamination could spread.
By John Abbotts March 14, 2025
n September, the city council of Westminster, Colorado voted not to fund a pedestrian bridge and underpass at the Rocky Flats site due to concerns about residual soil contamination from plutonium and other hazardous materials. In the process, the city council withdrew about $200,000 in financial support for the development of the project, known as the Rocky Mountain Greenway.
The US Fish and Wildlife Service proposed the greenway to connect wildlife refuges at the Rocky Mountain Arsenal through hiking trails via the Two Ponds refuge to Rocky Flats, with plans to eventually connect to the Rocky Mountain National Park. But the plan is controversial: Both Rocky Flats and the Arsenal are still on the US Environmental Protection Agency’s National Priorities List, identified since 1987 as “Superfund” cleanup sites that contain residual contamination.
The US Army established the Arsenal to produce chemical weapons to support World War II efforts, and in the 1990s, the federal government leased part of the Arsenal to Shell Chemical Co. to manufacture fertilizer and pesticides. In 1952, the Atomic Energy Commission began operations at Rocky Flats as a federal atomic weapons facility, producing plutonium triggers for hydrogen bombs. (A hydrogen bomb or H-bomb uses fission in the primary—uranium or plutonium—to trigger the secondary into a fusion reaction that combines two atomic nuclei to form a single heavier nucleus, releasing a much larger amount of energy.) Operations started largely in secret at Rocky Flats, located in a sparsely populated area 16 miles upwind and upslope of the city of Denver. But in the late 1970s, the public became more informed about plant operations, and the movement opposing atomic weapons began to focus on the facility, organizing protests and civil disobedience actions.
By the late 1980s, when the federal cleanup program at both sites had been initiated, work had already begun on the new Denver International Airport on Rocky Mountain Arsenal lands, and the Denver suburbs had steadily spread west toward Rocky Flats. Accordingly, there was consensus at each site that expedited cleanup would most effectively protect the metropolitan area, and cleanup standards were looser than “unrestricted use” to develop national wildlife refuges at each site. The consequences were residual contamination, especially at Rocky Flats, where there was no limit on how much plutonium remained below six feet of soil in an industrial area fenced off from the public and with the surrounding land converted to a wildlife refuge. This “cleanup on the cheap” at Rocky Flats, plus a record of cover-ups of accidents at the site, created continuing distrust and controversy over post-remediation uses near Rocky Flats. Cities and citizens opposed different proposals for re-use, even over the issue of public access to the refuge. Now there are concerns that the proposed greenway—a trail between the two tracts—may facilitate cross-contamination, taking radioactive material from the Rocky Flats site to the chemically hazardous Arsenal property, and vice versa.