FOX, Alaska – In the forests of Fox, Alaska, carved into a frozen hillside is a unique manmade 350-meter long research tunnel. Situated on a 16-acre parcel near the confluence of Goldstream and Glenn Creeks, the U.S. Army Corps of Engineers Research and Development Center’s Cold Regions Research and Engineering Laboratory’s Permafrost Tunnel Research Facility was excavated deep into a large block of discontinuous permafrost that has been going through several recent periods of expansion.
The expansion project began back in 2011, taking advantage of the digging seasons when the ground is at its coldest, with an overall project goal of expanding the tunnel facility to better support ongoing and growing research and engineering needs. The most recent expansion effort, this year, has added 300-feet of new tunnel, improved 200 feet of the existing tunnel and added links between the old and new tunnel sections at several locations, to include at an interface between subsurface bedrock and overlying gravels.
“The expanded tunnel will be extremely impactful,” said Dr. Tom Douglas, a CRREL research chemist and a lead on the expansion project. “It will allow us to develop three dimensional blocks that we can use to measure geophysical and geotechnical properties of permafrost.”
Douglas has worked in the permafrost tunnel for 18 years. His research is focused on environmental characterization of snow, ice and permafrost, including hydrology, soil analyses, biogeochemical measurements, remote sensing and system science research.
The tunnel has been used for more than 50 years to study permafrost, geology, cryospheric science, microbial life in extreme environments, permafrost biogeochemistry, and mining and construction techniques specific to permafrost environments. It also provides an unprecedented continuous hundred-meter exposure of permafrost extending in time from the present to about 45,000 years in the past, with unusually complete sequences of paleo-environments preserved intact. The permafrost in the tunnel represents syngenetic, ice rich, high organic carbon soils.
“A key challenge in permafrost work is that ice content drives so much of the properties for construction, risk of thaw and biogeochemistry,” said Douglas. “The expanded tunnel will allow access to these large sections of permafrost we can use to quantify properties at a scale that could never be done anywhere else.”
The fact that the tunnel was not built to facilitate extensive research or outreach has limited the scope and breadth of activities that could be investigating. A motivation behind expanding the tunnel was to enhance permafrost research related to climate change, in particular to address long standing issues related to construction on and over permafrost. The expanded tunnel is envisioned as an open facility where U.S. and international researchers can come and study permafrost.
More than 70 technical papers have been based on research conducted within the permafrost tunnel and the surrounding property. Research topics included placer mining techniques in permafrost, civil engineering and geotechnical aspects of permafrost, geocryology, geology, paleontology, paleoclimatology, biogeochemistry, biology — including life in extreme environments and Mars studies.
Kevin Bjella, a CRREL research engineer and lead on the tunnel expansion project, says a lot of his permafrost research is dedicated to understanding the impacts resulting from a changing climate, how do we build on permafrost to account for climate change and how do we mitigate the risk associated with building on frozen ground.
“We keep finding evidence for really rapid changes in the permafrost terrain in the past. It’ll be interesting to see how those rapid changes play out for what we’re seeing today,” said Bjella. “When we excavate, we see old soil layers. We see areas where ice was emplaced, and we can tell how the geological process has changed over time. We can tell that at some point — in the past 20,000 years ago, 30,000 years ago — there were these short periods of either rapid warming or rapid cooling, and how does that equate to what’s going on today.”
One benefit of the permafrost tunnel’s expansion will be the ability to study how climate change can affect the construction of buildings. Bjella questions if a building is constructed in a location under the current climate scenario what happens to that infrastructure if it isn’t bolstered for a warmer climate?
“What we do — over the last ten years — is better characterizing the permafrost terrain,” he said. “Instead of pointing at a spot and saying my landing strip or hanger has to be there, we actually look at the terrain ahead of time and say if you avoid this area your construction costs will be much better — it’ll be much easier because the permafrost is not as sensitive as it is in this area you want to build in.”
By expanding the tunnel, what CRREL researchers and engineers are doing is creating a test bed for developing and improving ground and airborne, maybe even satellite based, ground ice sensing technologies that will provide a high resolution image of the subsurface terrain and accurately account for the presence and location of ground ice, specifically so that it can be avoided.
When scientists only had one tunnel, it was just one passageway that was one snap shot of a point in time captured in ice, from which hypothesis and theories were derived. With the tunnel expansion and excavation of the new tunnel structure, some of those hypothesis and theories have either been validated or debunked. Just by adding more passageways, CRREL scientist and engineers can now see how rapidly conditions may change and in just a few spatial meters.
“Science works on the best information at the moment,” said Bjella. “When they created the first tunnel, they had that chunk of information, and it was the best that they had. Now that we have another tunnel that’s 200 feet away, we have even more information and some of it debunks what was thought of before, but some of it absolutely bolsters what was derived before.”
With the current phase of the permafrost tunnel expansion complete, the way forward for the next phase of the tunnel expansion is set in place. The next phase plans to have an additional 500 feet of tunnel excavated and is scheduled to start in November 2020.
“We are providing a really good mural of the past climate change,” said Bjella, “We just need to allow scientists to apply their tools and techniques to decipher that story, so stay tuned.”