Superfund Site Profile
The US Magnesium Superfund site is located adjacent to the Great Salt Lake in Toole County, Utah, 33 miles to the north of Grantsville and 40 miles to the west of Salt Lake City. The sparsely populated, 4,525-acre site includes the US Magnesium facility and surrounding areas of waste disposal. The facility has been producing magnesium at the site since 1972. The production process involves isolating magnesium chloride salts from the Great Salt Lake and then extracting the magnesium by electrolysis. Facility operations and waste disposal practices contaminated soil, air, surface water and groundwater with hazardous chemicals. In addition to threatening the health of US Magnesium workers, the contamination poses a threat to birds and wildlife.
TOPICS IN FOCUS
During the summer and fall of 2015, environmental investigations work continued at US Magnesium. Though the Outer Preliminary Remedial Investigation Areas (PRIs) Findings Report is not yet final, the current draft report contains data for every sample point in the Outer PRIs for soils and sediments. In July 2015, US Magnesium, LLC contractors collected surface water samples and that data will be added to the report. Crews last summer also collected background samples to compare naturally occurring chemicals to the site concentrations. The Outer PRI Findings Report is expected to be finalized in the next few months.
EPA and the US Magnesium, LLC contractors came to agreement in 2015 on an appropriate sampling approach for the Inner PRIs, which includes areas such as the gypsum pile, ditches, and waste lagoons. Contractors began sampling inner PRI areas in July. Fourteen samples were collected in each Inner PRI. This work required trained crews to take soil, sediment, and surface water samples in sometimes difficult to access and highly contaminated areas. For highly-acid waste lagoons, helicopter-deployed clamshell diggers scooped water and sediment from above to avoid direct contact with the acid-contaminated ponds. All sampling activity in the Inner PRIs is being guided by the Phase 1A-B sampling plan, finalized in September 2015.
Air sampling conducted per the 2014 Air Sampling and Analysis Plan showed that chlorine and hydrochloric acid are the two chemicals that need to be evaluated in more detail. EPA and US Magnesium, LLC contractors are developing a new Air Sampling and Analysis Plan to accurately measure exposures to these two contaminants at the site.