People in the town of Greenfield woke up in June and found themselves surrounded by a sandmine. Connecticut-based Unimin, a major sand mining company, intends to build its biggest mine in just outside the tiny village of Tunnel City, Wis. It started quietly buying property under a different name--to keep competitors off their trail, not to disguise their intent from locals, it says. Right now the Tunnel City site covers 500 acres and Unimin is still buying property. The company's executives estimate the mine will produce one to two million tons of sand a year. It will be a 24x7 operation.

This isn't happening just here in Tunnel City. It's a gold rush that's happening throughout Wisconsin and in Minnesota. Sand mine operators produce sands used for "fracking," a controversial process (New York state had a one-year moratorium on the practice and other states have cracked down on frac mining, which can turn green hillsides into moonscapes) of extracting gas and oil from rock. It's a case of technology racing ahead of regulators. The Tunnel City site is attractive for three reasons: its sand, its proximity to railroad tracks and no zoning.