'Great Pour' prepares sports center for ice

WASILLA -- The Wasilla Multi-Use Sports Complex took a huge step toward completion Thursday when a continuous pour operation covered the future ice rink with concrete.

"We've dubbed this the 'Great Pour,'" said Bruce Urban, director of the project. The day-long operation placed more than 300 cubic yards of concrete on the rink surface, a feat necessitating more than 30 trips out to the job site by Klondike Concrete, the company that provided the material.

For weeks leading up to the pouring project, crews labored to set 9.7 miles of plastic pipe on the bed of the ice rink. The process was complicated by the fact that the pipe can only hold a certain amount of weight, so no heavy machinery could be used.

So how do you get 300 cubic yards of concrete onto almost 10 miles of delicate pipe?

"Very carefully," said Urban. The concrete was delivered to the rink surface by a crane-suspended, manually guided hose. Workers spread the concrete by hand, using rakes and shovels, before the smoothing and leveling process began.

The concrete was leveled using a laser screed machine, the only machine of its kind in the state. The screed machine shines parallel lasers between two sensors positioned above its leveling edge. This machine makes the concrete more level more quickly than can be accomplished by hand. According to Ray Butler, owner of Flat Slabs LLC, who owns the machine, the laser screeder can level concrete over four times more quickly and three times more effectively than hand leveling, which usually involves dragging a weighted 2 by 4 plank over the surface of the concrete.

Fortunately, the laser screed machine only produces 4 pounds per square inch of pressure, and thus creates no more exertion on the pipes than a single person of average weight.

Butler said the sports center ice rink is one of only three rinks in the United States leveled using a laser screed machine. The increased flatness provided by this machine means a uniform ice depth on all parts of the rink.

The operation began at 6 o'clock in the morning, and was roughly halfway completed at 9:30 a.m. "Everything seems to be going pretty well," Urban said. "We've got a backup pump in case something goes wrong, but I haven't heard of any problems yet."

The pipes embedded in the rink contain glycol, a clear liquid used in antifreeze and deicing compounds. When the glycol is cooled using refrigeration machines in a nearby room, it brings the temperature of the surrounding concrete down, which in turn causes the water covering the concrete to freeze.

The next step in the process, according to Urban, is to let the concrete cure for 30 days before pouring ordinary water onto the surface. Soluble red, black, blue, and white paint in the water gives the ice its distinctive white color and provides lines for hockey games.