The Cordova daily times., 1919-10-23
Thawing Auriferous Gravel in Alaska with Cold Water

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 The use of cold wateT-that is, water at the normal summer tempera- ture of ponds, ditches and creeks in thawing perpetually frozen muck and gravel is a recent development that promises to be of value to the placer miners of Alaska. The idea is perhaps not entirely new, but it's application to mining was not success fully demonstrated until the season of 1918. The method is far from being established, and much experimental work remains to be done before its real value and limitations are known. It promises to be an economic means of thawing ground for dredging and open-cut mining. The available data on the subject as given below is ab- stracted from report now in course of publication by the United States geological survey, department of the interior.
 Experiments with cold water, hot water and steam were made during the season of 1917 under the direction of John Miles for the Alaska Mines Corporation, on its ground near Nome, for the purpose of determining the most efficient and. economical means of thawing the deep Nome gravels for dredging. Superheated steam at tenn perature of 1000 degrees Fah., steam at boiler temperature, hot water at 15O to 1SO degrees Fah., and water at stream temperature of 52 degrees Fah. were used in the experiments.
 In the experiments in which steam and hot water were used three holes were drilled to bedrock at the points of an equilateral triangle twelve feet apart. and at point intermediate be- tween them a test hole was drilled, which was cased and kept open to de- termine when the ground had thaWed to the center Shafts were sunk Ill tbe thawed ground, and drifts were run to the limits of the thaWed area. in the tests in which hot water and steam at boiler temperature were used the thawed areas tended to come downward leaving hOrsts of unthaWed ground on bedrock. Superheated steam at 1000 degrees Fah. thaWed mass of gravel 66 feet deep, 32 rect in diameter at the bottom and 27 feet in diameter at the top. The thaWeo area was greatest on bedrock ana where a clay stratum was encountered the hole did not pinch.
 Two holes were thawed by the cold wafer method. both single holes with out the test holes used in the forego- ing experiments. One hole was 44312 feet and the other 50 feet deep. Both were six-inch holes drilled to bedrock with an Empire drill. A two-inch pipe was inserted to bedrock, and small gas engine developing not more than 30 pounds pressure was used to 1orce water down the pipe. The water was allowed to run from the bottom or the pipe and flow over the surface, the circulating water thaWing the ice out of the muck and gravel. As no test holes were used, it was not possible to tell how rapidly the thaWing prog ressed until the ground began to slough in at the surface. This required from five to six days. The shrlnkage in the thawed ground was about one third. which represents the volume or ice present in the muck and graVel. The temperature of the water issuing from the hole was not taken. A sha1t sunk in the thawed ground showed the holes to have passed through stratum of clay. The area thaWed was in cross-section like an hour glass, having a width of twenty-two feet on bedrock. pitching to six feet at the clay stratum, and widening to eighteen feet at the surface. It is to be noted that the thawing was most effective where it was most desired, on bed rock
 Sufficient work was not done nor were sufficient quantitative data col lected to warrant any extensive con- clusions, but the experiments are in teresting in that they demonstrate