Kennecott and Winter Inversions

February 21, 2012

Kennecott and Winter Inversions

By Cassady Kristensen

Senior Environmental Engineer, Kennecott Utah Copper

As Kennecott’s engineer responsible for air permitting, I want the community to know we are serious about the environment. My job is to minimize the negative environmental impacts from our operation. We agree that the “gunk” caused by fine particulate matter, or PM2.5 during wintertime inversions, is unhealthy. We applaud air quality advocates for doing an effective job of highlighting Utah’s air quality problems; however, we believe their focus on Kennecott is misdirected. Kennecott complies with air quality regulations all year but especially during the winter months when specific and preventative measures are in place to ensure our operations have zero impact on the inversion problem we all live with.

In an inversion, warm air forms a lid over cold air near the ground preventing valley air from mixing and trapping air pollution below the lid. With this lid and virtually no wind, Kennecott contributes little to the valley’s poor air quality during inversions. Four examples illustrate my point.

First, while permitted to do so, we shut down our power plant during winter months, eliminating emissions from the plant. Second, we halt the construction of the tailings impoundment in the winter. With no construction and no wind during an inversion, emissions from the impoundment are essentially nothing. Third, our smelter stack is 1,200 feet above ground level. When an inversion sets in, the limited smelter emissions are released above the inversion lid and do not contribute to the valley’s bad air. Fourth, the elevation of the mine’s ridge is also above the inversion. Due to its size, the mine forms its own inversion lid and prevents emissions from entering the valley.

Don’t take my word for it. I invite you to visit the Division of Environmental Quality’s (DEQ) website and look at the PM2.5 data.

The data will show that the closest air quality monitor to our operation, located in Magna, is the only monitor in the valley that averages below the PM2.5 standards. Two air quality monitors east of I-15 in Holladay and Salt Lake City consistently report the highest PM2.5 levels. The data also demonstrates that in the absence of wind, air quality impacts are primarily caused by low-level sources like cars, print shops, auto body repair shops and similar sources.

We recognize the nature of our business has an environmental impact. My job, along with my 2,400 co-workers, is to implement solutions that help our community breathe cleanerair. Though effective at calling attention to Utah’s air quality problem, we believe that these advocates are misdirected about Kennecott’s impact to air quality during inversions. I encourage you to take a closer look by visiting our website at “” and clicking on the link under Kennecott and Clean Air.

See .PDF, p. 53, Figure 15.