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Study uncovers more underground mines than expected

HIBBING -- A study of former Iron Range underground mines has found far more subterranean works than expected.

The discovery could affect development in the area, where underground cavities might threaten the stability of new structures.

"A lot of what we've found is news to everybody,'' said Pete Clevenstine, Minnesota Department of Natural Resources Lands and Minerals Division manager of engineering. "Nobody realizes the extent of how many underground mines and shafts there were.''

A two- to three-year $304,000 DNR study, about halfway complete, is finding more mine shafts near Chisholm and Hibbing than originally believed.

John Suihkonen, chairman of the Central Iron Range Sanitary Sewer District, said the study will be used as a planning tool in developing a $20 million sewer system. The system, which could be under construction in 2008, would connect Chisholm, Buhl, Kinney, and Balkan and Great Scott townships to the Hibbing wastewater plant.

Of the $20 million needed for the sewer system, $8 million has been secured so far. The remaining $12 million is being sought from the federal government, Suihkonen said.

The DNR study will help sewer system planners pinpoint areas where the ground could subside because of abandoned underground mines.

"We will be using the study as a design tool," Suihkonen said. "We thought it would be important to not be designing new structures or facilities over those mine workings."

Shifting ground prompted a six-month closure in 2005 of Ironworld's Iron Range Interpretative Center, a 43,600-square-foot museum with exhibits on Iron Range history and a Gov. Rudy Perpich memorial. A study later determined the center was not in danger of collapsing.

A stretch of Highway 169 between driving lanes near Ironworld collapsed last month into an abandoned mine.

Among 50 underground mines so far identified in the study, 262 mine shafts have been pinpointed.

Some of the mines and shafts found in the study are part of current open-pit taconite operations. But many of the underground workings remain beneath Minnesota Highway 169 near Chisholm, Ironworld Discovery Center and the St. Louis County Fairground.

The massive Godfrey Mine -- beneath that area -- shipped 12.2 million tons of iron ore from 1926 to 1963, according to Skillings Mining Review. The Godfrey was the last operating underground mine on the Mesabi Range.

"We've found more than what was listed in the mining directory,'' said Dale Cartwright, DNR project coordinator.

The DNR study, paid for by the Central Iron Range Sanitary Sewer District, is aimed at identifying former underground mine workings near Chisholm and Hibbing. The district includes Balkan Township, Buhl, Chisholm, Great Scott Township and Hibbing.

From the late 1800s to about 1920, dozens of underground mines dotted Minnesota's Mesabi Range. Others operated on the Vermilion and Cuyuna ranges. The mines removed high-grade natural iron ore from the ground and shipped it to Upper Midwest mills to be turned into steel.

From 1940 to 1943, Iron Range mines shipped more than 350 million tons of iron ore. Much of the ore was turned into steel to build ships, airplanes and other military equipment for World War II.

For DNR staff, identifying the mines and individual shafts has become somewhat of a scavenger hunt.

"A lot of the actual maps are scattered all over the place,'' said Matt Oberhelman, a DNR geologist. "Some are held by mining companies, some by fee holders, at Ironworld and others just by people. It doesn't appear like anyone ever kept track of this and kept it together.''

By piecing together old maps, historical documents, microfilm records and detailed mining company drawings, a more-complete picture of underground mines and the shafts that took miners, air or wooden support timbers down into the mines is becoming clearer.

The DNR's goal is to organize the information by June 30, 2008, so it can be used by Chisholm, Hibbing, Buhl and Balkan Township for land planning.

"The primary purpose is to plan for the sewer line,'' Clevenstine said. "But it's good to understand it for other future development also.''

Government officials near Virginia and Biwabik are interested in developing the same information on former underground mines near their communities, Clevenstine said.

"People always knew there were underground mine workings,'' Oberhelman said. "But I don't think anybody has seen them all together like this.''