Kennecott Smelter Stack

The Kennecott Copper Corporation smokestack is the tallest freestanding structure in the western United States - but do you know about its origins? Built in just 84 days, this structure replaced earlier smokestacks in response to the government’s Clean Air Acts.

The Kennecott Copper Corporation (KCC) smokestack is a monumental structure rising 1,215 ft above the Salt Lake Valley floor, making it the tallest free-standing structure west of the Mississippi River, the second highest smokestack in the United States, and the fourth highest stack in the world. The stack was built in 1974, in response to the 1970 federal Clean Air Act. Once operational, the stack replaced earlier smokestacks at the smelter, the tallest of which was 412 ft (Arave 2009; Salt Lake Times [SLT] 22 March 1974:4). Once the older stacks became obsolete, they were demolished* (Arave 2009). 

KCC smelting and refining operations 2006, Oquirrh Mountains in the background (Rio Tinto 2006).

Many were opposed (this included KCC, the state of Utah, some of KCC employees, and segments of the local communities) to the new clean-air regulations imposed upon KCC by the Environmental Protection Agency (EPA) as the new federal regulations were more stringent than the Utah state regulations. Utah state regulations required that 86 percent of the sulfur dioxide be removed from the smoke that escaped the stack, while the new federal regulations required that 95 percent of the sulfur dioxide be removed (Deseret News [DN] 22 October 1974:17, 31). KCC officials believed the state regulations were already too strict and they were “bitterly opposed” to the new clean-air standards, claiming they were impossible to meet (DN 11 December 1974:1, 6).  The state of Utah sided with KCC. Governor Calvin L. Rampton stated that the EPA’s proposal was “entirely unnecessary in the light of the state’s imminent regulations.” Salt Lake City Mayor Jake Garn said the plan was a “waste of money and energy” and that the EPA’s overruling of state regulations was “an affront to the power and ability of the state” (DN 11 December 1974:1, 6).  

Kennecott “Super” Stack (Arave 2009, Photograph by Jeffrey Allred 2009).

KCC’s solution to the problem was to construct a “super” smokestack at the smelter just west of Magna and south of State Route 201 (DN 22 October 1974:17, 31). Despite KCC’s proactive solution, the action was not approved by the EPA and a court ruled against KCC’s smokestack solution. EPA officials stated that the new KCC stack does not qualify as pollution control, with Christine Phillips, the lawyer for the EPA, commenting that the “Clean Air Act of 1970 specified emission control for air pollution; not stacks” (DN 11 December 1974:1, 6). A court decision earlier in the year supported Phillips claim, remarking that the stacks only dispersed the pollutants into the air and that the pollutants “must end up somewhere....” (DN 11 December 1974:1, 6); the somewhere being farther downwind. Regardless of the opposition from federal agencies, courts, and environmentalists, KCC proceeded with the construction of the stack.

Work on the base of the stack began on June 21, 1974 and crews began pouring the stack on August 26. The stack grew 20 ft each day (DN 22 October 1974:17, 31) as crews labored seven days a week, 24 hours a day (Arave 2009) to complete the stack before winter set-in. The stack has a hexagonal base that measures 177 ft across. The stack itself is 124 ft in diameter at the base and narrows to 40 ft at the top. At the base the concrete walls are 30 inches thick (12 ft thick according to Arave 2009) and narrows to 12 inches at the top (DN 22 October 1974:17, 31). The steel reinforced concrete smokestack tops out at 1,200 ft and a 15 ft fiberglass flue brings the total height to 1,215 ft. The interior of the stack contains an elevator, a lighting system, and gas monitoring stations at various levels. The stack was designed and constructed to withstand high winds and earthquakes (Arave 2009; DN 22 October 1974:17, 31; Salt Lake Times [SLT] 22 March 1974:4). The stack was completed in 84 days (with only one short break). More than 26,000 yards of concrete and 900 tons of steel were used in the construction of the stack (Arave 2009). At the time of construction, it was reported that the estimated cost of the stack would be $175 million; 35 years later, Arave reported the cost at $ 16.3 million (Arave 2009; DN. 22 October 1974:17, 31). The disparity between estimated cost and actual cost is huge, especially given the value of 1974 dollars versus 2009 dollars. Perhaps the cost was exaggerated to illustrate the exorbitant amount of money it would cost KCC to comply with the new federal mandate and at the same time garner support against the EPA from employees and the surrounding communities. On the other hand, maybe the reports got the figures wrong. 

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*Early smokestacks at Arthur/Magna mills, not stacks depicted in demolition video (KUC History Pictures from Line Crew, Image 86, courtesy Rio Tinto).
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Dashed lines show height of new “super” stack over earlier smokestacks at KCC (DN 22 October 1974:17).

As noted above, the construction of the “super” stack was extremely controversial. The most common complaint was that the taller stack was not the answer to the pollution problem. Although the taller stack was equipped with devices that removed some pollutants, the devices did not remove enough to comply with the new regulations and KCC stated that during certain weather conditions the only way to comply with clean-air standards would be to shut down. Those in opposition to taller stacks claimed that the taller stacks did not control pollution; they only distributed the pollution over a wider area. Even more concerning to the EPA and environmentalist was that the taller stacks tended to form stable clouds of toxic particles of sulfides and sulfuric dioxides that could result in acid rains and other hazards. The sulfides were especially hazardous since they are long-lived and can be transported over long distances. However, KCC contended, and the EPA agreed, that the studies on the health hazards of sulfides was not complete (The Salt Lake Tribune [SLTRIB] 12 August 1974:15).

Pollution in the Salt Lake Valley was a huge problem in the early 1970s and it was a concern for many, not only for KCC, environmentalists, and the state. In a letter to the editor of The Daily Utah Chronicle, a reader, John Dover, describes how from the Great Salt Lake he and friends were unable to see the Oquirrh Mountains due to all the pollution spewing from the KCC smelter smokestacks. In his letter, Dover pondered how KCC was allowed to get away with polluting the air unchallenged. On a lighter note, he did thank KCC for the beautiful sunsets (The Daily Utah Chronicle [DUC] 23 July 1974:5).

Another letter to the editor, by David J. Lee, came to the defense of KCC. Lee remarked that forcing KCC to comply with clean-air standards hit the consumer in the pocketbook, since KCC was liable for all expenditures related to any new EPA regulations and that this cost would be passed on to the consumer. He speculated that incentives, such as larger tax breaks for KCC, would allow them to make larger profits; thus, making KCC more willing to spend money on environmental cleanup. He argued that cooperation and compromise would achieve more than the continued bickering between both sides, both of whom were determined to push through their own agendas (DN 28 November 1974:4).

In addition to local readers, the local newspapers themselves were choosing sides during this debate. On December 6, 1974, The Daily Utah Chronicle (Chronicle) lambasted The Salt Lake Tribune (Tribune) for siding with KCC by stating that the EPA was a “monster” with unrealistic expectations. The Tribune was also accused of providing misinformation in their article by not vetting their sources and for claiming that the smelter was officially shutting down (it only threatened such action). At the same time, the Chronicle also stated that the threat of a shut-down was KCC’s go-to option whenever they were called out for infractions. KCC soon came into conflict with their employees when they sent out letters to their employees asking for their support in opposing the EPA, whose new regulations were a threat to their future job security. Some employee unions were quick to respond that KCC was trying to intimidate employees into opposing the EPA by threatening their livelihood. KCC denied these accusations, responding that they were only informing employees of their position in the conflict and asking for employee support (DUC 6 December 1974:3).

On November 24, 1974, KCC gave a slide presentation to the Magna Chamber of Commerce showing the results of KCC’s revegetation project in the Garfield smelter area. The revegetation program was part of KCC’s “Mining is Beautiful” advertising campaign. After conferring with company environmentalists and revegetation researchers Paul Rokich and Larry Jones, KCC teamed with high school and elementary school students and Boy Scout and Girl Scout groups to plant trees, shrubs, and grasses in Black Rock and Kessler canyons and at the smelter entrance. Verne Huser, the KCC presenter, stated that the stack would be complete the following week, and once it was online it would greatly reduce the sulfur emissions released from the smelter. Huser also remarked that the denuding of the vegetation surrounding the smelter was primarily the result of overgrazing, fires, and logging abuses and that the smelter emissions were not responsible for the stunting of plant growth (The Magna Times [MT] 25 November 1974:1). 

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Advertising campaign by KCC 1970s (Kefauver 1978).

In 1995, KCC constructed a new smelter with a new emissions control system that captures 99.9 percent of toxic gases. Leftover gases from the smelting process are piped into the smokestack and carried to the top of the stack. Only trace amounts of waste gas escape the stack and any discharge seen from the stack is only steam (Arave 2009; SLTRIB 21 May 2000:63, 68). Instead of being torn down and replaced by a new smokestack, the controversial “super” stack was incorporated into the new emissions control system. Although the “super” stack is two-thirds higher than it needs to be for the new system, the cost of razing the old stack and constructing a new 400 ft stack would have cost millions of dollars; therefore, it was more cost effective to refurbish the old stack, than to raze it. Monitoring equipment is at the 300 ft level and is accessed by the interior elevator. The elevator ride takes approximately three minutes to the 300 ft level and six to seven minutes to reach the top of the stack. Few ever take the trip to the top and those who do sign their names on the interior liner of the stack. At the top, a six-foot wide observation deck encircles the exterior of the stack, allowing for a fantastic view of the Great Salt Lake and the Salt Lake Valley. Since the renovations, only KCC electricians need to make the trip to the top when the warning lights burn out and need to be replaced (SLTRIB  21 May 2000:63, 68). Although controversial when first built, the improvements to the to the smelter and refinery components has made the KCC smelter one of the two cleanest smelters in the world (Arave 2009). The stack is a significant and recognizable element to the Salt Lake Valley skyline and commonly used as beacon by sailors on the Great Salt Lake to find their way back to the marina at the south end (Arave 2009; SLTRIB 21 May 2000:63, 68).

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How the “super” stack, stacked up as of 2000 (SLTRIB. 21 May 2000:68).

*Short video clips of “super” stack and demolition of old Kennecott stacks in New Mexico can be found here: My Spectroom: Video Library. Electronic document, Kennecott Smokestack | Spectroom, accessed December 6, 2022. 



Arave, Lynn. 2009 Holy Smokes: Kennecott Smelter, Utah’s Tallest Manmade Structure, Turns 35. Deseret News 16 November. Salt Lake City, Utah. Electronic document Holy smokes: Kennecott smelter, Utah's tallest man-made structure, to turn 35 - Deseret News, accessed December 5, 2022. 

Daily Utah Chronicle, The (DUC)

1974 Reader’s Right: Dense Town. 23 July:5. Salt Lake City, Utah.

1974 Valley Waits as Kennecott, EPA Argue Over Controls. 6 December:3. Salt Lake City, Utah.

Deseret News (DN)

1974 Tougher Limits Urged on KCC Emissions. 22 October:17, 31. Salt Lake City, Utah.  

1974 Forum: “Profits Play Vital Role.” 28 November:4, Salt Lake City, Utah.

1974 KCC Stack No Control EPA Says. 11 December:1, 6. Salt Lake City, Utah.

Kefauver, K. E. 1978 Kennecott Copper: “Mining is Beautiful.” In Sourcebook on Corporate Image and Corporate Advocacy Advertising. Subcommittee on Administrative Practice and Procedure of the Committee on the Judiciary of the United States Senate. U.S. Government Printing Office, Washington, DC. 

Magna Times, The (MT). 1974 Chamber Organizes Plans. 25 November:1. Magna, Utah.

My Spectroom nd Video Library. Electronic document, Kennecott Smokestack | Spectroom, accessed December 6, 2022. 

Rio Tinto. 2006 Kennecott Utah Cooper: Sulfuric Acid Environmental Profile: Life Cycle Assessment. Kennecott Copper, LLC.

Salt Lake Times (SLT). 1974 The Leased Grapevine. Blurb about KCC under heading. 22 March:4. Salt Lake City, Utah.

Salt Lake Tribune, The (SLTRIB)

1974 Taller Smokestacks Really No Solution. 12 August:15. Salt Lake City, Utah.

2000 On Top of Old Smokey. 21 May 2000:63, 68. Salt Lake City, Utah.