Utah looks to rein in US Magnesium emissions

Cox asks EPA to expand ozone “nonattainment” area to include Rowley plant, a major pollution “point source.”

(Trent Nelson | The Salt Lake Tribune) US Magnesium, seen across the Great Salt Lake from Stansbury Island on Saturday, March 26, 2022.

The US Magnesium plant on the southwest shore of Great Salt Lake may be a critical source of the nation’s magnesium, but it also contributes heavily to Utah’s air quality woes. Now state regulators are seeking greater latitude from federal authorities to force the plant to reduce emissions.

Utah Gov. Spencer Cox on Monday asked the Environmental Protection Agency (EPA) to expand the Northern Wasatch Front ozone nonattainment area to include the U.S. Magnesium’s Rowley plant in Tooele County.

For decades northern Utah has struggled with degraded air quality. Winter days are sometimes plagued with high levels of fine particulate, or PM2.5, and summers with ground-level ozone, and the Rowley plant contributes to both. Weather plays an important role in pollution levels, but emissions are the bigger factor.

“Utah has made significant strides in improving air quality over the past 10 years, but as our state continues to grow, we need to begin to look more strategically at opportunities to continue this trajectory,” Cox said in a statement. “This intentional approach gives us a focused range of tools that align with the outcome we all want - cleaner air and a better quality of life for Utahns.”

The Rowley plant processes magnesium and lithium extracted from brines, using a melt reactor and electrolytic process to separate magnesium from chlorine

Cox’s request came after an extensive analysis by state air-quality officials identifying strategies for reducing emissions of volatile organic compounds, VOCs, and for meeting Utah’s obligations under the Clean Air Act.

Processing magnesium emits large amounts of VOCs and nitrogen oxides, in addition to chlorine and other halogen gases, such as bromine, blamed for worsening Utah’s PM2.5 and ozone problems.

Expanding the nonattainment area boundary to include the plant would enable the Utah Division of Air Quality to impose emission reduction requirements on the facility, leading to air quality improvements, according to a letter Cox sent Monday to EPA’s regional administrator Kathleen Becker.

Last November, the EPA reclassified the Northern Wasatch Front nonattainment area from “marginal” to “moderate” for ozone, elevating the pressure on the state to take stronger action.

One of those requirements is to cut VOC emissions by 15%. In search of new places to cut emissions, the DAQ is now looking at industrial sources outside the nonattainment area, according to Cox’s letter. Topping that list is the Rowley plant whose permit allows it to emit up to 894 tons per year of VOCs, 1,261 tons of nitrogen oxides (NOx) and 8,522 tons of hazardous air pollutants (HAPs).

“These emissions make US Magnesium’s Rowley plant one of the largest point sources of VOCs and NOx in the greater Wasatch Front and the largest point source of HAPs in Utah,” states supporting documentation.

The plant was recently identified as a major emitter of bromine, a halogen gas that accelerates the photochemical reactions that recombine other pollutants into PM2.5. One study concluded the plant’s bromine emissions are responsible for 10 to 25% of Salt Lake City’s particulate pollution during winter inversions.

“These studies found that emissions from US Magnesium extend to nearly the entire Wasatch Front with plumes emitted from the plant observed across a wide sector of the populated regions of the valleys,” the supporting document states. “It is imperative that the state is able to control and reduce emissions from every source that impacts air quality while adequately accounting for those emission reductions.”