Council briefed on pipe electrolysis

March's Sinkhole Sunday was caused by a spike in water pressure that took advantage of weaknesses in the iron piping due to electrolysis.

  • May. 25, 2015 7:00 p.m.

Arne Petryshen

Back in March when Sinkhole Sunday caused havoc on many Cranbrook streets, the culprit was a spike in water pressure that took advantage of weaknesses in the iron piping due to a process called electrolysis.

The electrolysis is caused through electricity that is grounded in the pipes — and removes material through that process.

At the May 11 meeting, Eric Sharpe, Director of Engineering for the City of Cranbrook, updated council on the question of whether something could be done to prevent further electrolysis in Cranbrook’s pipes.

Sharpe explained that cast iron and ductile iron has been the pipe of choice for many years throughout the 20th century.

“One of the ways the pipe was sold was it is very heavy, very strong… that kind of thing,” Sharpe said. “You don’t have to worry about bedding it — using the proper bedding sand and that kind of thing — because it is so tough.”

Sharpe noted that since then, the degradation from electrolysis has become apparent.

He said one of the things that is recommended in soils that are especially conducive to the electrolysis process is installing a sacrificial zone or magnesium anode.

“So the electrolysis is done through the sacrificial anode instead of taking away from the pipe,” he said.  “The question was could we do this to our existing pipe? The issue with that is you pretty much have to expose the whole pipe, and if you’re going to expose the whole pipe, you’re tearing up the whole road. And once you’re at that point, you’re probably better off replacing it as we would through our capital replacement.”

Coun. Ron Popoff asked how many lines are currently not protected from electrolysis.

Sharpe said to his knowledge there aren’t any sacrificial anodes buried with Cranbrook pipes. He said one of the problems was that the pipe installation was all developer driven, and so the city doesn’t have the data on it.

“The ones that we have been back to and exposed, we found that there have not been,” he said.

Popoff asked whether it would be a practice going forward. Sharpe said the pipes that go in are now generally PVC pipe. If they do use steel, it can be coated to resist electrolysis.

Cranbrook Daily Townsman