The Performance of Artificial Frozen Barriers

Migration of aqueous phase contaminants from underground tanks, nuclear waste sites, and in situ waste treatment areas into the groundwater is of concern at many locations. There is a wide range of technologies to remediate contaminated sites. Some examples are: constructed wetlands, air sparging, bioremediation, and permeable reactive barriers. One technology that has not been widely used is frozen soil barriers. The barrier provides containment of liquid contaminants in order to prevent their migration to adjacent areas. This is a promising method that is environmentally friendly and offers a safe alternative to other methods. Frozen barriers can be formed using a series of subsurface freezing pipes or probes. The installation of frozen barriers disturbs the existing ground minimally and only existing in-situ material is used. An artificial frozen barrier using hybrid thermosyphons was installed in Fairbanks, Alaska using six thermosyphons placed at a distance of 1.5 m. The system ran actively for about 60 days and operated in a passive phase during the winter months. A detailed description of the thermal performance of the barrier in Fairbanks from March through September will be presented.