Frozen Pipes

Spring is the time to watch for freezing of buried water and sewer pipes. There is a lag between the months of coldest air temperature (December and January) and the time when the ground freezes deepest. The soil temperature at depth 18 feet reaches a minimum in May; below 20 feet the temperature is a nearly constant 26 F year-round in Fairbanks.

As soil freezes it extracts energy from the warmer soil below, causing its temperature to lower. By this process the freezing level moves slowly downward. In water-saturated gravel under a bare ground surface or one covered only by hard-packed snow, the freezing level can move downward as fast as three feet per month. But under a deep layer of loose snow, soil will freeze at a much slower rate. Therefore, to protect buried sewer and water pipes, do not walk or drive over them; better yet, pile loose snow on them.