Permafrost and Homesites

Permafrost: A word that means little to many of us and a lot to some. Back in 1969, my wife and I began to lay the foundation for what was to become our house. This was in a location about 10 miles west of Fairbanks, near the community of Ester.

Although we knew about the dangers of what permafrost could do to dwellings, our building site was located on a south-facing slope situated on what appeared to be a very solid footing of Fairbanks loess, or wind deposited glacial flour (generally referred to in the area as "silt"). As a one-time geologist, this seemed safe enough to me.

Like so many people in Alaska, we were not able to complete the house in only one season, and it was not until two years later that we could afford to have a water well drilled. Imagine our consternation when the driller informed us that, only six feet down, our house was sitting on solid permafrost.

Ordinarily, this would have meant that, within a matter of years, the heat transmitted downward from the house into the soil would have begun to cause settling. This happens when ice-bonded permafrost and often-extensive solid ice lenses lying within it begin to melt. It is a familiar problem to many builders in the far north.

We were lucky. A neighbor's house only 200 yards downhill from us has been undergoing steady deformation for years, because of gradual melting and subsequent downhill flow of the material bordering and underlying it.

As it happened, the loess underlying our house has only a very small moisture content, and any thawing which has occurred has not produced noticeable settling. To other less fortunate residents around the state, foundation material is often found to contain a significant portion of solid ice or ice-rich material, which creates havoc as it melts.

Although we didn't know it when we started our construction, loess is particularly notorious in this respect.

The moral: check you footing before you build.