This sign at the southern end of SR82 in Nogales discourages commercial trucks from traveling through Patagonia and Sonoita. Vehicles associated
with the Hermosa Project would significantly increase truck traffic on this scenic road. Photo by Hal Arnest

The truck route proposed by South32 (S32) from its Hermosa Mine in the Patagonia Mountains to the Port of Tucson passes through landscapes unique to the state, even the country, that have been identified by the State of Arizona as a ‘Scenic Road’ and thus not recommended for trucks. This recommendation, of course, includes S32 trucks, especially when cargo is going to be hazardous. How such transports can affect the quality of life for area residents is going to be addressed below in a series of questions.

What is the additional truck traffic volume?

Assume, as per S32’s suggestion, that the quoted additional 200 trucks per day operate indeed “not 24 hours per day” and “mindful of commute hours,” but for about 16 hours per day, as the company suggested. A S32 vehicle would be passing by every 4.8 minutes. Total truck traffic would average a truck passing every 2.9 minutes. That is more than double the current volume of semi-trailers that ignore the “recommendation” and travel between Benson and Nogales at a rate of about one every seven minutes over a 24-hour period.

What is being transported?

S32 refers to “ore trucks” next to “construction and operational traffic.” Firstly, it is not “ore” that is being shipped out of the mine but concentrate. It is called this because it already has a much higher concentration of toxic metal compounds, a product ready for smelting into pure metals at some other place, probably Asia. From S32 documents it can be concluded that S32 plans to use so-called ContainertippTM containers that have a payload of 20 tons. Lowbed, 34-wheel trucks will be barreling down the mountain and driving, all on public roads, the 58 miles to the rail transfer station at Kolb Road in Tucson, and back.

The quoted need for transport of construction materials will also include explosives needed to blast mine tunnels in mountain sides. Transport of explosives typically is with 20-ton trucks and the compound used is called ammonium nitrate fuel oil. Only three tons of this chemical killed 169 people during the Oklahoma City bombing in 1995, not to forget the large scale devastation it caused in Tianjin in 2015 and Beirut in 2020.

Under the category of operational materials one can count the reagents, which is a euphemism for a plurality of process chemicals needed to extract metal compound concentrates from the mined ore and includes the very toxic leaching chemical sodium cyanide. Given the level of hazard (class 6.1, labeled as poison), residents may not want to wait for some “unexpected situation,” a phrase frequently used after a calamity has taken place, and move elsewhere. After all, this chemical is typically transported in 20-ton tanker trucks, hopefully only during daytime and under escort.

What about traffic accidents?

SR 82 already has a higher density of semi-trailers from/to Nogales than present on an average rural road in the U.S. U.S. statistics show that 52% of the deaths involving large trucks take place on rural roads like SR82, and of that number, 74% involves a second vehicle, the occupants of which account for 97% of the deaths. Most truck accidents are due to tire and brake defects, a scenario to avoid at all costs on mountain roads like SR82 and SR83. School buses, passenger cars, motorcycles and bicycles would all be forced to share the road with South32 truck traffic, as the chances for the number of fatal accidents will grow due to the increased number of trucks.

What about air pollution?

From EPA statistical data it can be calculated that an additional 200 trucks per day will put 350,000 tons of greenhouse gases in the immediate environment along the route over the estimated 30 years of operation of the project. To put this into perspective, households along the same route, and during the same time, can be estimated to contribute 45,000 tons. Across the U.S., the ratio between greenhouse gases from transportation and residential sources is about 4.5:1, while the ratio along the proposed truck route is 7.8:1. This means that those residents would be worse off than the average U.S. citizen, while without the additional trucks they are better off, consistent with the idea that rural life is healthier.

From Tucson to Guaymas?

One of the rail destinations mentioned is the Mexican maritime port of Guaymas, a city with 400,000 people and valuable industries, like tourism and cosmetics. To protect these other industries and its citizens, Guaymas has consistently been increasing environmental regulations to curb toxic dust generation from its concentrate transfer operations. It is surprising that, in 2020, Tucson is still welcoming similar operations in spite of its disadvantageous climate conditions and population vulnerability. It seems that Mexico is not hampered by antiquated mining laws when it comes to protecting its people.

If Guaymas is the final choice, then it is counterproductive and endangering more residents than needed by first going north to Tucson by truck, than going south via Nogales to Guaymas by rail. Nogales can be reached by rail by crossing the border a few miles east of Nogales and about 20 miles south of the Hermosa Mine. Yet it seems that the cheapest solution received priority.

Who is benefitting?

Modern mines in highly mineralized rock formations typically show a very high rate of return, explaining the eagerness to remove mountain tops or dig extensive tunnels even in unique and diverse ecosystems like the Patagonia Mountains. Returns are mainly paid out to executive management and stakeholders, while the average resident will not be compensated for any degradation in quality of life caused by just one foreign company. That is how it has been ever since the 1872 mining law gave extraction companies carte blanche over lands that belong to the people and unlimited access to public roads. Time is long overdue to stop such preferential treatments and realize that it is not in the interest of residents that a foreign company can ravage their environment and jeopardize their safety by extracting and exporting their minerals from their mountains using their public roads.

Editor’s note: Chris Workhoven, a Sonoita resident, is a retired executive from the semiconductor process industry. Werkhoven holds a doctorate in Physical Chemistry from the University of Amsterdam