Ch. 14] WATER SUPPLY 265 



main frozen, serious consideration should be given to artificial freezing 

 in those places where permafrost must be utilized as a construction 

 material. Techniques that were used at Grand Coulee Dam or on 

 Hess Creek (Huttl, 1948) can be modified to fit the situation. It 

 should be borne in mind that the refrigerating equipment need be run 

 only for a matter of hours during the summer after the ground has been 

 refrozen and vegetation or other means of natural insulation have been 

 employed. Bad slides on roads and railroads, settling under expen- 

 sive buildings, loosening of the foundations of dams, bridges, towers, 

 and the like probably can be treated by refreezing artificially at less 

 cost than by any other method. In fact the day is probably not far 

 off when airfields of Pycrete (Perutz, 1948) or similar material will be 

 built in the Arctic where no construction materials are available. 



Where seasonal frost (active layer) is involved in construction, the 

 engineer is referred to the annotated bibliography of the Highway Re- 

 search Board (1948) and to such reports as that of the Corps of 

 Engineers (1945, 1946, 1947). 



Water Supply 



Throughout permafrost areas one of the main problems is a satis- 

 factory source of large amounts of water. Problems encountered in 

 keeping the water liquid during storage and distribution or in its 

 purification are beyond the scope of this report. Small amounts of 

 water can be obtained generally from melted ice or snow. However, a 

 large, satisfactory, annual water supply in areas of continuous perma- 

 frost is to be found only in deep lakes or large rivers that do not 

 freeze to the bottom. Even then the water tends to have considerable 

 mineral hardness and organic content. It is generally not economical 

 to drill through 1,000 to 2,000 feet of permafrost to tap ground-water 

 reservoirs beneath, although artesian supplies have been obtained 

 under 700 feet of permafrost (Dementiev and Tumel, 1946) and under 

 1,500 feet of permafrost (Obruchev, 1946). 



In areas of discontinuous permafrost, large annual ground-water 

 supplies are more common either in perched zones on top of permafrost 

 or in non-frozen zones within or below the permafrost (Cederstrom, 

 1948; Pewe, 1948b). 



Annual water supply in areas of sporadic permafrost bodies normally 

 is a problem only to individual householders and presents only a little 

 more difficulty than finding water in comparable areas in temperate 

 zones. 



Surface water as an alternate to ground water can be retained by 

 earthen dams in areas of permafrost (Huttl, 1948). 



