Corps extends Permafrost Tunnel and Mission

Published May 24, 2018
Corps extends Permafrost Tunnel and Mission

An excavator, outfitted with a cutter head, is photographed in the U.S. Army Engineer Research and Development Center’s Permafrost Tunnel near the intersection with the South Tunnel. Also in the photo are the ventilation bag and digging control lasers.

HANOVER, N.H. (May 4, 2018) -- In Fox, Alaska, lies hidden a unique scientific treasure, the Permafrost Tunnel Research Facility; a portal back in time to the Ice Age. Inside the tunnel, the walls are composed of frozen silt, gravel, vegetation and the bones of ice-age bison and mammoths. The tunnel, excavated into the hillside in the early 1960s, was first used by the U.S. Army Corps of Engineers to learn about excavating permafrost for underground military operations. Later in the 1960s, the Bureau of Mines used the tunnel to test permafrost mining techniques.

Situated in Interior Alaska, approximately 10 miles north of Fairbanks, the tunnel, since 1963, has been maintained and operated by the U.S. Army Cold Regions Research and Engineering Laboratory and provides engineers, scientists and students with a unique source of data in a natural laboratory. The tunnel is refrigerated year-round, preserving the site for long-term sampling and in situ research.

Referred to as the “Old Tunnel,” the initial construction began in 1963 and continued until approximately 1968 with two excavations.  The first was a horizontal passage, or adit, with total length of 360-ft. and 40-ft. below the ground surface. The second was a 150-ft.-long winze with a decline of 14 percent to the gold bearing gravel and bedrock at 55-ft. below the ground surface. 

The facility has undergone renewed expansion, also known as the “New Tunnel.” Phase I occurred in 2011 creating a new portal and entrance and 100-ft of horizontal passage, while Phase II occurred in 2014 and provided another 100-ft of horizontal passage. The latest phase was successfully concluded on March 9, after six weeks of digging. The project began with ambient temperatures in the minus 20’s (degrees Fahrenheit) and minus 30’s, which are ideal to counter heat generating excavating equipment. Unfortunately, the outdoor temperatures warmed in the next weeks requiring minimizing the time while excavating to ensure excessive thawing of permafrost features did not occur. 

“Despite the warming temperatures we managed to excavate a total of 176 ft., connecting the newer south tunnel with the older north tunnel,” said Kevin Bjella, a research engineer with CRREL’s Alaska Research Office in Fairbanks. “This phase of excavation connected the mid-points of the ‘Old’ and ‘New’ tunnels with more unique ice features being exposed and documented along the way with detailed high-resolution photo mosaics.” 

The expansion was hailed a great success, and the team looks forward to conducting the final phases pending future funding availability. The final phases will connect the back of the ‘Old’ and ‘New’ tunnels, requiring extending another 200-ft. of new excavation.

This latest effort will provide ground truth for developing stand-off ground ice detection methods; thereby, allowing higher resolution on the frequency and extent of massive ground ice in order to better understand permafrost terrains for engineering, military planning and science. Additionally, the expanded facility will provide better quantization of paleo-environmental parameters, such as sequestered carbon and paleo biological remnants and the study of climates of the past. 

The tunnel facility has renewed direct military application as a site for subterranean training. 

“CRREL’s Permafrost Tunnel now provides the Department of Defense with mission support in addition to its role as a 3-D test bed for research and education,” said Gary Larsen, the operations manager for CRREL’s Alaskan Research Office in Fairbanks. “Following successful tours of the tunnel, the U.S. Army Maneuver Center of Excellence and Asymmetric Warfare Group developed a plan to use the tunnel as their site for conducting subterranean operations training exercises in June. Additionally, the U.S. Army Alaska will use the tunnel for subterranean operations training five to six times per year, as well. In both situations, the Army seeks to use the tunnel to provide Soldiers a great opportunity to understand that subterranean facilities are common, even in Alaska, and present unique operational challenges.”