The Nome nugget., 1920-02-14

by superheated steam must of course rest on grounds of economy.
 During the season of 1918 the cold. water method just outlined was used with some important notifications in several operations.
 Pierce and Johnson. in the Candle district, drilled 6-inch hole in 2i fes, of muck Ono graveD and introduced water by Il r inch pipe under Il head of 15 feet G pounds pressure.) The water entered the ground at 4s de grees Fahrenheit and left at 32 to Sij degrees Fahrenheit. The time of thaw was seven days. and the diam eter of the thaw area 8 feet. Steam had been tried under the conditions prevailing here and was not satisfac- tory. Water did the work well.
 The same company used cold water in thawing creek gravels preparatory to dredging. The ground thawed was 12 or 13 feet deep, and consisted of to feet of clay and muck. to , feet of gravel and 3 feet of soft blue clay bedrock. A battery of forty T | inch points Was used, the points spac- ed in squares feet apart. It was found by trial that 5-foot spacing ,re- quired IS hours to thaw, and that the thaw was perfect. whereas 10-foot spacing required 96 hours to thaw, and horsts of unthawed material were left on bedrock. The water entered the ground at 42 degrees Fahrenheit, and came from the thaw at 3S to 39 degrees Fahrenheit. Water under q head of 24 feet u0.4 pounds pressure) was used. The thawing took place first and was widest on bedrock. Shrinkage of as much as 3 feet was observed and was confined almost en-
 that 60 miners inches of water was
 used to run the 40 points continuously. Three men were employed, two on the Iday and one on the night shift. A Horsepower engine was used to kpump water to q reservoir 24 feet labove creek level and was run three fhours in each eight. In this opera
 tor ho'es were nit drIilnj .. The
 points were set with water and re-
 quhed only an occasional twist with d stilson to force them to bedrock as thawing progressed.
 From the tests made with cdld water near Nome. as described abdve. clay kwould seem to require special con- |sideration. Will increase in pressure Tor increase in time he more efficient in thawing such impervious strata? What is the most efficient spacing for various depths of gravel? In deep gravels the dead work necessary in Ehandling and connecting pipe will pro. Ebably justify fewer holes and longer operating time to each thaw than will
 be found efficient in shallow gravels. It is possible that the method may not he applicable under all conditions Depth of ground. character of ground, availability of water. and slowness of thaw may be factors that will limit its use. Even though there are lim- itations to it's application. the method will undoubtedly be useful in thawing shallow ground where water is easily 1available. and that is putting the max imum restriction upon its use
 Sufficient data are not available to make any general prediction concern- ing the time required in tliawing un- der various conditions, but the infor- nation at hand Is summarized below
 In the experimental work on the deep Nome gravels the volume ac- tually thawed amounted to about 50 cubic yards day for one point using a pressure of about 30 pounds and water at 52 degrees Fahrehheit, The test on muck in the Candle district shows voulme of about cubic yards