In a 60,000-square-foot area of a warehouse under construction we have frost to a depth of 30 inches. Is there some way to thaw out the ground other than burning straw on the surface? The burning of materials such as straw isn't alto wed in our area.
A 30-inch depth of frost would take quite a bit of heat to thaw out. It could be done by covering the area with polyethylene with insulating blankets over the top and shooting steam underneath. The steam should go in slowly enough so that it condenses and doesn't leak out around the edges, so that a large part of the heat would be lost. To make a rough calculation of the theoretical amount of steam required you can figure that one pound of steam by weight contains enough heat to thaw about 7 pounds of ice. If you have any idea of the moisture content of the ground you might figure how much steam you would need, making a sizable allowance for heat losses and any other inefficiencies. You should also bear in mind that every pound of steam condensed will leave a new pound of water in the ground, so that will contribute to sogginess if you don't have some way of draining it away.