The hole was only 14 inches across at the beginning, and grew larger as the flow eroded away the surrounding rock. I remember reading elsewhere that it took a f

The hole was only 14 inches across at the beginning, and grew larger as the flow eroded away the surrounding rock. I remember reading elsewhere that it took a few hours for the lake to drain. The drill had penetrated one of the lower levels that protruded further underneath the lake, not the top of the mine as one might assume. This gave workers on the upper levels more time to evacuate. The fact that it happened very early in the morning might also have helped.