Conduct Interim Treatment and Environmental Monitoring at the Tuba City, Arizona Disposal Site CX(s) Applied: B1.26, B3.1Date: 42537 Location(s): ArizonaOffices(s): Legacy Management
Office of NEPA Policy and Compliance
June 16, 2016
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Conduct Interim Treatment and Environmental Monitoring at the Tuba City, Arizona Disposal Site
CX(s) Applied: B1.26, B3.1
Date: 42537
Location(s): Arizona
Offices(s): Legacy Management
The Tuba City, Arizona, disposal cell is underlain by contaminated groundwater due to onsite uranium milling activity which occurred between 1956 and 1966. The groundwater contaminant plume, which consists primarily of uranium, nitrate, and sulfate, has not migrated substantially from the original site of mill buildings, tailings piles, and tailings ponds. Due to the need to idle the obsolete distillation treatment unit, an interim treatment action for contaminated groundwater was identified by LM and approved by the Nuclear Regulatory Commission. The interim groundwater treatment process consists of extracting contaminated groundwater and using the existing system of extraction well pumps and piping for evaporative treatment in the existing evaporation pond. Evaporative treatment returns clean water to the atmosphere as a vapor and segregates contamination in the sediment layer of the evaporation pond. The current interim process can treat approximately 7 gallons per minute (GPM) during the winter and 15 GPM during the summer. The maximum flow rate of treatment is substantially less than the 176 GPM limit of the applicable Categorical Exclusion (B1.26).