Dealing with
Icy Challenges

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It's just cold solid water. But the differences between building in ice and building in water of the unfrozen kind are extreme.

Say you're a big oil company with offshore rigs scattered here and there. Your geologists have located a pocket of oil somewhere in the arctic. You've secured the rights to it. The water's icy, yes, but essentially it's the same deal as anywhere else, right? Time to proceed.

Not quite.

"Ice is about 10 to 100 times more complicated than open water, and we have 10 to 100 times less experience, so we're about 1,000 times behind," says Walter Kuehnlein, the managing director of Sea2ice, a consulting engineering firm specializing in ice and cold-regions engineering.

Those that hire Kuehnlein looking for advice (or take one of his courses) will hear much about "design philosophies in ice." Philosophies, because when it comes to ice, the entire way we engineer comes into question.

"In open water you can start with a rectangular box and build around this," says Kuehnlein. "Engineers are used to building something which just stays there." Cars, electronics, the guts of buildings need maintenance, to be sure, but they are essentially designed to be complete, finished products. In ice, the degree to which human participation and decision-making needs to be incorporated changes the rules from the beginning.

"When you hear this for the first time, it sounds normal and not very important," says Kuehnlein. "But it's absolutely against everything we've done in the past 2,000 years. Even the pyramids have been able to stand without additional support."

Additional Support Is Essential

In ice, nothing gets done without constant ‘additional support,' and it's a must that such support be there at the start of any project slated for ice. "Everybody involved should sit at the same table," says Keuhnlein. "Talk about the environmental issues, the biological issues, the civic issues. Normally we try to divide everything into different disciplines. But we should hear from who wants to do it and who doesn't want to do it: Everyone together."

The need for total inclusion springs in part from the fact that the way to deal with ice in one icy corner of the world may have little to do with how it needs to be handled in a different icy corner. "In open water, you can shift a rig from one side of the world to another and still use it," he says. Those who design such rigs need only know two things about the water they're in: temperature and salinity. In ice, there are 20 such factors, all of which need to be fully understood.

Chief among those is the strength of the ice. Ice with "needles" that run through it vertically, for instance, is much stronger than ice with horizontal needles. The homogeneity of the ice is another crucial factor. Then there's the ice's cohesiveness, as well its brittleness. "If all parameters are the same, it still behaves differently depending on the temperature history the ice has seen in the last days and weeks," notes Keuhnlein.

The Challenges of Ice Structures

However well one might understand the ice in which they are building, it can still behave destructively. A structure in ice crushes the ice around it, but then the ice grows again and pushes back, and the structure crushes the ice again. In this back and forth, the ice seeks out the natural frequency of whatever object with which it is toying. "Everything starts shaking like hell—not nice for the people—but then the soil under it starts to liquefy and the structure goes down on one edge," says Keuhnlein.

There also are issues of accessibility for tankers, the difficulties of evacuation, and the devastation an oil spill would cause on ice, where booms are useless, among many other potential problems.

Such challenges might make one think that a simple suggestion to steer clear of ice altogether would be all a consultant would ever need to offer. But Keuhnlein just wants to make sure everyone knows what they're up against. "It's not so easy to know one thing about one part of the picture; better to know nothing about anything," he says. "Bring everybody into the picture, and start at an early stage. Don't have a base requirement. Re-think everything. Everything that is normal, rethink it."

Michael Abrams is an independent writer.

Ice is about 10 to 100 times more complicated than open water, and we have 10 to 100 times less experience, so we're about 1,000 times behind. Walter Kuehnlein, managing director, Sea2ice

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