The challenges of Arctic engineering: Alaska's extremities keep engineers on their toes.

• Author: Campbell, Melissa

Engineering in the Arctic conditions of Alaska creates special challenges, to say the least. There aren't many places in the world where one will find aboveground water pipes, ice-breaking footings on bridges and office buildings that sit on pilings.

Special precautions must be made because of the extreme conditions found here: areas where temperatures can range from 80 degrees above zero in the summer to 80 below in the winter months; cold that can cause steel and nails to go brittle; and soil conditions that are frozen solid through winter, but turn to a soggy glob the rest of the year.

"Alaska has such a harsh environment," said Dennis Nottingham, president of PND Inc. "We have everything here: ice, cold weather. We've got horrible winds. Everything is extreme."

Before any engineer or architect is licensed to work in Alaska, he or she must take an Arctic engineering course to learn how to best accommodate these extreme factors. Nottingham said that he and several practicing Alaska designers helped write the text and teach the courses offered at the University of Alaska.

"I made a whole bunch of mistakes up here when I first started," Nottingham said. "There's no reason young people should make the same mistakes."

To avoid such errors, engineers must take into consideration all of Alaska's extremities when designing the works for roads, buildings, bridges and other projects. To do their jobs right, they must know everything about the construction site, from below the ground, up.

THE GROUND AND BELOW

The earth we call Alaska is a fickle thing. It heaves, it jacks, it freezes hard as a rock, then thaws to mush in the summer sun.

To keep the doors and windows working properly, some buildings in the Lower Kuskokwim region, as well as other parts of the state, have to be adjusted twice a year, in the winter and in the spring, said USKH's Bruce Hopper.

Anyone who commutes on Alaska's roads is personally familiar with the bone-jarring frost heaves that tend to pop up out of nowhere in springtime.

These occurrences are examples of that paradoxical phenomenon that is permafrost gone bad. Permafrost is defined as soil or rock that remains at 32 degrees or colder for more than two years.

The trouble most often is finding it. In some parts of the state, mainly on the North Slope, engineers can count on the frozen soil covering every square inch for up to 2,000 feet below ground. Put down a protective insulation layer between the building and the ground, and things should work fairly well.

But the permafrost gets a bit patchier in other parts of the state, such as in the Yukon-Kuskokwim region.

"In Bethel, the permafrost is around 30 degrees," said Mike Rabe of CRW Engineering Group. "If you make even a slight topographical change there, it can have drastic results, turning into mush real fast."

The Southcentral area, including Anchorage, has what is...