It is currently making its first pass down with a 12.5-inch diameter hole to the roof of the 50-square-meter (500-square-foot) refuge at Level 100 (100 meters above sea level).

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It is currently drilling a 17.5-inch diameter hole -- smaller than the 28 inches required to rescue the miners -- in an effort to realign after veering off course over the weekend.

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Drilling a 2 or 3 foot hole can be done with normal equipment, while drilling a ten, fifty, or one hundred foot diameter vertical hole would require an entirely new invention.

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Measurements taken early this week showed the hole measured 324 feet in diameter and is 50 feet deep, but in one corner it goes down 422 feet, said John Boudreaux, director of the Office of Homeland Security in Assumption Parish, about 30 miles south of Baton Rouge.

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Monster drills would cut a hole a yard or so in diameter down 2.5 miles into the Earth's crust, past the deepest groundwater into granite rock formations that have sat undisturbed for billions of years.

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The drill would use that hole as a pilot and widen the diameter to about 28 inches, which officials have said is wide enough for the miners to be hoisted through.

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The hole was originally reported to be 100 feet across, but that is the diameter of the safety zone surrounding it, Bracken said.

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The hole that was drilled is a little under two-thirds of an inch in diameter, and is two and a half inches deep.

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