Depth and time of frost penetration are important design criteria that control or limit underground domestic water supply and waste disposal systems in any climate where winter temperatures cause soils to freeze. In Alaska, especially the Interior, these factors become important because of the extreme cold and the duration of below-freezing temperatures. Many areas of Interior Alaska are free of permafrost, but still experience deep seasonal freezing of soils. Near Fairbanks a range of low hills, mantled with silty soils, is becoming important for home sites and all these slopes with a southerly exposure are free of permafrost. On such sites it is important to know the seasonal depth of freezing because a frozen waste disposal system here poses a serious pollution problem that may be a significant health hazard. This temperature station was established because data on soil freezing were not readily available.