Journal of Cold Regions Engineering

An evaluation was conducted on the use of geothermal energy in wastewater treatment in the Canadian Prairie Provinces. The assessment included an analysis of geothermal energy costs, an examination of the effects of using elevated temperatures in wastewater treatment, a selection of suitable uses of the low‐grade energy in wastewater treatment, and a preliminary assessment of costs and benefits. By heating the wastewater influent to 30° C on a year‐round basis, performance (as measured by BOD removal) of an activated sludge plant might be increased by 10–15%. There may be much less benefit in the case of long‐detention aerated lagoons. The benefit may be significant (approximately 30%) for trickling filter plants, but such systems are generally not considered for use in the harsh western Canadian climate. The economics of using geothermal energy to improve wastewater treatment‐plant efficiency is not particularly attractive. An additional investment of 33–50% of the cost of the treatment plant is generally required for the installation of a geothermal energy system so that any enhanced efficiency of the treatment plant is obtained.

A study to determine the amount of moisture that has accumulated in insulation systems in structures in cold regions is described and the data analyzed. The study region is interior Alaska. Moisture contents are found to be relatively low as an overall average (less that 2% by volume), but many individual structures have enough moisture in their insulation to raise the heat loss from the structure by as much as 300%. Moisture content is compared for north‐ and south‐facing walls and found to be approximately the same in both directions. Moisture content is also found to be independent of the location on the wall and the age of the structure. The effect of summer drying is also assessed and discussed. A significant summer drying effect was found, which reduced the moisture in the wall by 32–82% for some structures in this location.

The effects of adding wood as a binder material to snow is discussed in this paper. Wood/snow pavement test sections were constructed in the antarctic at two sites, McMurdo and Amundsen, Scott South Pole Stations. Temperature conditions at McMurdo Station were near freezing, while South Pole Station had constant subfreezing temperatures. Test sections were monitored during the austral summer of 1986–87 and again during the 1988 season. Rammsonde penetrometer, density, and temperature profiles were used to evalute material behavior. Results indicate how snow pavements depend upon temperature history, initial material properties, and construction‐processing techniques. Solar radiation affected the surface sections at McMurdo by causing melt to occur, since temperatures were near freezing. Satisfactory strengths, for supporting wheeled aircraft, were obtained at depths below 20 cm at both stations. Evidence shows that with an improved surface‐processing technique, such as heat processing, ample strength may be obtained to support wheeled aircraft landing in the antarctic.

In contrast to data available on strength and deformation characteristics of frozen soils, frozen gravels have received relatively little attention. This seems to be related to fewer geotechnical projects conducted in frozen gravels, the relatively higher stability of frozen gravels, and possibly greater difficulty in conducting mechanical measurements in or on frozen gravels. Findings presented in this paper came from a testing program conducted on artificial samples using gravels from Fox, Alaska. Main variables controlled during testing were strain (straining) rate, temperature, and size and shape of the tested samples. All tests were run in uniaxial compression. After preliminary testing of straining rate influence, all remaining tests were run at a constant strain rate of $10\mu \epsilon /s\text{.}$ Temperature at which tests were conducted and volume of samples were found to be the controlling variables. Their effect correlates well to exponential models, which describe gradual decrease of strength with temperatures approaching the thaw level and with decrease in sample volume. The data may find applications in analysis of stability of openings and foundations constructed in frozen gravels.