Would-be gravel miners have been claiming that an impending gravel shortage threatens the Salt Lake area economy unless they are permitted to tear up the Wasatch wherever gravel deposits are found. Two recent studies conclude that this looming gravel shortage is a myth.
This past spring, developers who are determined to open a vast limestone mine in Parley’s Canyon pressured Utah legislators to insulate the mining of so-called critical infrastructure materials (sand, gravel and crushed rock) from local government control. Alarmed local governments pushed back causing the Legislature to require only a study of the future supply of and demand for CIM, together with an assessment of how CIM mining should be regulated.
Responsibility for the study and assessment was given to Stantec, an environmental consulting firm. Stantec won’t release the details of its study until the 2025 Legislature reconvenes, but it shared its initial findings with the Legislature on Nov. 20. Twelve days earlier, Stantec had released the results of its roughly parallel study that Salt Lake County had commissioned.
Stantec’s interim findings are a welcome surprise. It finds that there should be no shortage of CIM that would restrict Utah’s economic development through 2060. There are, it says, a whopping 6.5 trillion tons of potential CIM reserves across the state, which could supply our needs for 13,000 years.
Stantec’s county-focused study found that in the Salt Lake Valley, where shortages are likely to appear first, demand for CIM is not likely to exceed local supply until sometime after 2035. Even then, it notes, the Salt Lake area’s CIM shortages probably could be covered for 30 more years by tapping Tooele County’s extensive unexploited reserves. Stantec also concludes that CIM deposits on the western slopes of Salt Lake Valley could help cover the Valley’s post-2035 shortages incurring smaller increases in transportation costs.
Stantec’s studies, however, recognize that it probably underestimates future CIM supplies because they do not estimate the impact of using recycled concrete rubble or the many other effective substitutes for conventional CIM that are available, nor do they systematically examine the potential use of low-cost rail to import virgin CIM from more distant deposits. Utah’s CIM industry agrees that these alternative strategies are effective ways to overcome local CIM shortages.
Over the last decade, the world’s major cement makers have come under intense pressure to reduce their carbon footprint. Making cement from virgin limestone emits prodigious amounts of CO2, so carbon-reduction research focuses on ways to avoid using virgin limestone. Consequently, the list of commercially viable alternatives to using the virgin limestone that Granite Construction wants to extract from Parley’s Canyon is growing dramatically.
Currently, most of the cement used to make Utah’s concrete is produced by Holcim and CRH. These international corporations recently acquired technologies that make low-carbon cement and aggregate without the need for virgin limestone, and both have committed to scale them up globally. Likewise, Eco-Material Technologies, headquartered in West Jordan, has developed processes that can replace from 60% to 100% of the limestone needed to produce cement with fly ash waste from power plants. Terra CO2 Technology just received funding to build a plant in Magna that will replace up to 50% of the limestone needed to make conventional cement with the almost infinite supply of tailings from the nearby Kennecott mine.
These low-carbon, reduced-limestone cement and concrete production technologies are the wave of the future. Stantec didn’t have the time or resources to account for reduction in demand for conventional CIM that adopting such breakthrough technologies is likely to cause. Therefore, I believe it overestimates Utah’s future needs for conventional CIM.
Another strategy often used for overcoming local shortages of CIM is to access non-local deposits that are near existing railways. Shipping aggregates by rail rather than by truck can cut per-ton-mile shipping costs in half for deposits over 100 miles away. The USGS describes numerous markets that currently use this approach. Historically, many of Utah’s heavy industries imported limestone aggregate by rail and much of the infrastructure for doing so remains in place. Stantec’s finalized study should systematically examine the potential of reviving this approach. Stantec’s estimates of CIM supplies available to Utah’s heavily urbanized counties are probably understated, and their delivered costs overstated, because they do not systematically account for CIM deposits in rural counties that lie near existing rail lines.
Backers of the vast CIM mine proposed in Parley’s Canyon repeat the unsupported claim that the CIM supply in the Salt Lake Valley already is “not nearly keeping up with demand” and that mines like theirs must be approved wherever deposits are found or the Salt Lake area’s economy will suffer “serious consequences.” Stantec’s finding that Utah has an overwhelming long-term abundance of CIM supplies effectively rebuts these claims. Its initial assessment that local governments should still have a say in regulating gravel mines is well founded. Its twin studies together offer a sorely-needed factual basis for making informed decisions about how CIM mining should be regulated.
Malin Moench
Malin Moench spent 37 years performing legal and economic analysis of regulated industries at the federal level. Now retired, he volunteers for non-profit organizations focusing on environmental protection and public health.
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