Superfund Information Systems: Site Profile

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The 6,240-acre Rocky Flats Plant (USDOE) site is located about 16 miles northwest of Denver and 10 miles south of Boulder, Colorado. The Rocky Flats Plant operated from 1952 until 1989 as part of the United States’ nationwide nuclear weapons complex. The facility manufactured trigger mechanisms for nuclear weapons from various radioactive and hazardous materials. Manufacturing activities, accidental industrial fires and spills, support activities, and waste management practices contaminated soil, sediment, groundwater and surface water with hazardous chemicals and radioactive constituents. The greatest contamination and hazards were located within the 385-acre industrialized area at the center of the property, where the majority of the nearly 800 structures were located.

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What Has Been Done to Clean Up the Site?

The site is being addressed through federal actions.

EPA has conducted several five-year reviews of the site’s remedy. These reviews ensure that the remedies put in place protect public health and the environment, and function as intended by site decision documents. The most recent review concluded that response actions at the site are in accordance with the remedy selected by EPA and that the remedy continues to be protective of human health and the environment.

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What Is the Current Site Status?

The U.S. Department of Energy (DOE), EPA, and Colorado Department of Public Health and Environment (CDPHE) determined that the off-site area surrounding the site was not contaminated to levels requiring cleanup. This area consists of about 20,480 acres of open space, residential development and agricultural lands.

EPA divided the site into two separate areas, or operable units (OUs), to better address cleanup. The 1,308-acre Central OU, or OU1, includes 384 acres in the industrial area in the center of the facility. The 4,883-acre Peripheral OU, or OU2, includes a buffer zone area.

Accelerated cleanup actions focused on the industrial area in OU1 where most weapons manufacturing took place and where plutonium, uranium and americium contamination persists. The cleanup included decommissioning, decontamination, demolition and removal of more than 800 structures; removal of more than 500,000 cubic meters of low-level radioactive waste; and remediation of more than 360 potentially contaminated environmental sites.

The long-term remedy for OU1 included institutional controls, physical controls, monitoring and signage. Cleanup at Rocky Flats did not eliminate all contamination in the central part of OU1. Although all buildings were demolished and removed, some residual contamination remained in core production areas, settling ponds and two landfills. Remaining contamination includes low concentrations of radioactive materials, chemical solvents and heavy metal contaminants, generally below regulatory standards. Studies show that this contamination poses no threat to human health and the environment.

Ongoing monitoring and management by DOE are overseen by EPA and CDPHE.

In 2006, EPA determined that no further cleanup was required at OU2. Remedy construction took place between 1990 and 2006. Following cleanup, operation and maintenance activities are ongoing.

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