By Jonathan Hoffman

Say, “new copper mine” to Southern Arizonans and they will often visibly cringe. Many recall the tailings piles near Green Valley or the open pits seen shortly after takeoff from Tucson International Airport. They may also think of well-paying jobs. Some may recall working in the hard rock mines of the Magma Copper Company near San Manuel, which closed down years ago leaving the town's residents with considerable economic stress.

Perceptions vary, as do the types of mines. Copper mines fall into two operations categories. The open pit, where material is removed from the surface and working downward. The result is a huge bowl-shaped hole left in the ground in perpetuity, along with tailings piles. The other is the hard rock, or underground mine, which consists of large tunnels burrowed through the underground ore, bringing material to the surface after crushing, leaving tailings piles also.

Currently, two mines in Southern Arizona are at different stages of the permitting process. One is the proposed Rosemont Mine located in the Santa Rita Mountains, southeast of Tucson. The other is the Oracle Ridge Mine located on the north side of the Santa Catalina Mountains, north of Tucson.

The Rosemont project is a new large-scale, open pit mine, while the Oracle Ridge is the reopening of an old, hard rock mine. Both operations are subsidiaries of Canadian corporations.

While the two mines are quite different, both should be improvements to their predecessors due to advances in mining technology, particularly in the area of environmental protection. Both will use the “dry stack” method of forming tailings piles. The resulting tailings will have greatly reduced moisture content than conventional tailings, roughly 25% moisture compared to roughly 60% moisture using conventional techniques. Benefits of the dry stack method include the recycling of a larger quantity of water back into the processing system, more stable tailings piles that do not require dams to keep the material in place, and no seepage that could contaminate surrounding land and water. Both mines will be treat ore on site to produce a concentrate that will be trucked away.

The Rosemont Mine

Rosemont will be a large-scale operation, located in the Santa Rita Mountains on approximately 900 acres of private property. The mine will require over 3000 acres of US Forest Service land for the tailings piles. Company job creation estimates vary, projecting 400 direct jobs with average annual incomes of $59,000, 1,700 indirect jobs, $19 million annually in local tax revenue, and $700 million in local economic stimulus each year in a 2009 report prepared by Arizona State University, commissioned by Rosemont. The report also estimates that the mine will stimulate a total of $15 billion in new economic output in Southern Arizona over the life of the mine.

Objections raised to Rosemont Mine development cite damage to the environment and to the local tourist economy from a large mining operation in the Santa Rita Mountains. A large pit, tailings piles, and buildings will be added to the scenery. Many of the mine structures will be visible from Arizona State Route 83, a well-traveled, designated scenic route. 

There are other public concerns. Astronomers are worried about the night operations planned interfering with currently dark night skies. Native Americans have voiced concern about disturbance of sacred sites, while hunters and the Arizona Game and Fish Department are worried about destruction of wildlife habitat. The biggest concern is water.

Rosemont, which has bought, traded, and generally wheeled and dealed in water rights, plans to use ground water initially. The mine operators plan to phase out ground water use with a connection to the Central Arizona Project. Opponents fear this may result in water shortages for residents in the region and possible long-term water table contamination. The US Environmental Protection Agency recently delayed the process of issuing a US Forest Service Permit to Rosemont. Another major permit is required from the Army Corps of Engineers, and the EPA will once more play a major role. Potential lawsuits may cause even further delays.

The Oracle Ridge Mine

Oracle Ridge is an existing, totally contained mine, including tailings piles, on private property in the Santa Catalina Mountains. Originally opened in the late 1800s, it operated off and on until closing in 1996. The proposed reopening has drawn little public reaction. The mine is not visible from the town of Summerhaven, the Catalina Highway, or any other paved road. Forecasts call for the mine to employ 240 people, and produce up to 140 tons of copper concentrate each day. The mine will use a fraction of the water needed by Rosemont.

Far fewer permits are needed for the Oracle Ridge operation and are primarily required from local agencies. A recent public hearing on Mt. Lemmon drew no public opposition. Many of those opposing the Rosemont Mine have no objection to Oracle Ridge apparently, including at this time the Pima County Board of Supervisors, even though most workers will be drawn from neighboring communities of Oracle and San Manuel in Pinal County, giving a major boost to those stagnant economies.

Next Steps

Ultimately, mining activity is driven by the worldwide market. Demand and prices have been on the rise, making copper mining a profitable enterprise once again. Owners are finding old mines worth reopening, as in the Oracle Ridge Mine’s case. Virgin territory, the basis of the Rosemont Mine, was not worth the investment in the past, and now may well be worth exploiting.

In the court of public opinion, Oracle Ridge has the clear advantage. The mine is already there, with infrastructure in place, and there will be little visible change. Rosemont will transform a vast area of forest and grassland, most of it public land, into an industrial complex with a large hole as its hub. That is a much harder sell for many people.

Posted in: Regional News

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Dan Starr
# Dan Starr
Tuesday, June 12, 2012 4:17 PM
Nice article. As I tell folks - if it can't be grown, it must be mined. Of course, many of the people that live in this region are not big on that knowledge. I've lived here, hiked these mountains, for 60 years. I'm not some "Johnny Come Lately" fool who thinks this might spoil his/her view. Such folks have done a ton of damage to Tucson already. I've seen it. Wonder why there is no East-West freeway? Such people. There was a vote in the 70's for a thing called "The Butterfield" and it was roundly defeated. Now it's way more money to build such a thing.

Disclaimer: Worked at San Manuel underground. Studied geology and mining at UA. Like the products of mined materials (such as this computer.)

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