Using frozen barriers for containment of contaminants

Abstract

In the summer of 2011, a full-scale test of a frozen soil barrier was deployed at the Cold Regions Research and Engineering Laboratory site in Fairbanks, AK. Hybrid thermosyphons, a more efficient cooling technology than conventional ground freezing, were used to create the frozen soil. The hybrid units were actively cooled by a 4.5 kilowatt refrigeration condensing unit for 62 days. A vertical frozen barrier of 9 meters (m) extending from a depth of 7 m below the surface to the ground surface was completed in 42 days, and the barrier was 1 m thick in 48 days. This frozen barrier installation has successfully shown that this technology can freeze the ground quickly. At the end of winter 2012, the barrier was approximately 3.8 m thick. This barrier thickness was maintained throughout the summer of 2012. The results showed only the top 0.5 m thawed even though the system was inactive for approximately a year. A cost analysis was performed to compare the cost of frozen barriers and slurry walls. It was concluded that construction and operating and maintenance costs of frozen barriers are on par with other barrier systems. DISCLAIMER: The contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. All product names and trademarks cited are the property of their respective owners. The findings of this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents.

Ground-Coupled Natural Circulating Devices (Thermosiphons): A Review of Modeling, Experimental and Development Studies

“…This means that it can operate as a passive system when the ambient temperature is sufficiently low and as an active system when the air temperature becomes too warm to condense the refrigerant, or when other system conditions necessitate additional ground cooling. According to Wagner [15], hybrid systems can either be used to increase the rate of ground freezing instantly after the installation of thermosiphons, particularly in the summer, or to offer a backup freezing source for eventual situations, when the thaw depth exceeds expectations, when rapid cooling is required for construction scheduling, orwhenthere is a risk of unexpected heat peaks. Originally, hybrid systems were used when more cooling was required to prevent permafrost thawing beneath civil constructions [11], but later, this practice was extended to other types of applications [16,17], with certain modifications such as the creation of artificial frozen barriers using hybrid thermosiphons.…”