As if the borough’s Public Works Department wasn’t busy enough last week with the damaged sewage outfall line, the crew was pressed into evening work to repair a broken water main on St. Michaels Street.
The ductile iron pipe on the hill above City Market probably was 40 to 50 years old, said Public Works Director Tom Wetor. “The stuff was supposed to last 60 years,” he said, but poor installation likely led to deterioration of the pipe and the break.
A lot of utility pipe was buried around town and throughout Alaska during the heavy flow of state oil dollars to communities in the 1970s and early 1980s, but best practices were not always followed to wrap the pipe or attach anodes to protect the iron from corrosion caused by electrolysis, Wetor said.
Low-level electrical current in the ground, aided by intrusion of salt water and acidic soil, creates a hazard for iron pipe. “It’s pretty hot downtown,” he said of the underground electrolysis, which is similar to the corrosive damage on piers and pilings in salt water.
The break occurred Sept. 5, and crews worked until about 11:30 p.m. making repairs.
The pipes generally are buried four to five feet below the surface.
In its repair and replacement work, the borough uses plastic pipe that is supposed to last 100 years, Wetor said. The high-density polyethylene pipe is often used to replace aging concrete or steel pipe.
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