Granite: our new mining opportunity

by Rolf Westgard — professional member, Geological Society of America

Several years ago there was a report that a driller had struck oil in southwestern Minnesota. Minnesota’s state geologist responded, simply asking whose pipeline they hit. Oil is rarely found in lands where basement rock is close to the surface, areas known in geology as shields. Minnesota is situated on the southern edge of the Canadian Shield.

Shields have relatively few layers of sedimentary rocks, like shale, from which came most of the earth’s oil and gas deposits. To our west, the basement rock dips down to form the Williston Basin, which includes the western Dakotas, eastern Montana and Saskatchewan. That basin’s deep sedimentary layers contain its large reservoir of fossil fuels.

As if to compensate for our lack of oil riches, nature provided Minnesota with substantial and useful mineral deposits, especially the world-class iron ore reservoir on the Iron Range. Most of that ore is gone, having supplied the steel that framed many of America’s buildings and machines.

Minnesota is well-endowed with another rock, not precious, but widely used for buildings, bridges, paving and countertops — granite. There is another potential use for granite: encapsulating nuclear waste. Thanks to some rigid and technically ignorant Nevada politicians and our nation’s annual need to store thousands of tons of spent nuclear fuel, our granite could become a multibillion dollar industry in northern Minnesota.

One tenth of a cent per kilowatt hour generated by our 104 nuclear power reactors is placed in a fund to provide geologic storage of the fuel waste generated by those reactors.

The geological storage fund now exceeds $25 billion. A part of it has already been spent for the more than $10 billion needed to build the long-planned storage facility in Nevada’s Yucca Mountain Ridge. Now pressure from Nevada officials has caused President Barack Obama to cancel the project and begin dismantling it.

Sandia National Laboratories was commissioned to study America’s geology for an alternate site. Sandia’s newly released report notes that granite’s properties as a chemically and physically stable rock with low permeability would “strongly inhibit” radiation from reaching the outside environment if waste canisters leaked. The National Academy of Sciences has also concluded that “geologic disposal remains the only scientifically and technically credible long-term solution available to meet safety needs.”

Three of the 12 promising U.S. granite sites identified in the Sandia report are in northern Minnesota. The Minnesota sites are especially effective because of low water content and our lack of seismic activity. The other good site is in Vermont’s granite, but Vermont officials have already vetoed the idea, stating that “it should be placed in the middle of nowhere.”

The concerns in Nevada and Vermont are apparently the result of radiation fear. The average U.S. resident receives approximately 300 millirems of radiation annually from natural sources like radon, cosmic rays, airline flights and eating foods like bananas and nuts which contain potassium. This radiation has occurred since humans have been on earth, and it doesn’t hurt us or humans would not exist. Persons who work in industries with higher radiation risk are allowed 5 rems per year, or more than 15 times the normal dose.

The individual-protection standard for geologic storage facilities sets an overall additional dose limit of 15 mrems per year for residents living in the vicinity of Yucca Mountain during and up to 10,000 years after the repository closes. Two round-trip domestic airline flights may result in a dose of 15 mrems. After 10,000 years through the period of geologic stability (out to 1 million years), the individual-protection standard is set at 100 mrems per year, a very safe level.

Opening a Yucca Mountain replacement facility in northern Minnesota is a multibillion dollar business opportunity with no significant risks to Minnesota’s people and environment. It’s an opportunity worth our consideration.