Corrosion Protection Program for Calgary Water Mains by Anode Retrofit

ABove, is from a National Research Council paper in the 1990s, undoubtedly involving my old friends Yehuda Kleiner and Balvant Rajani in some way, that proved dispositively that attaching magnesium anodes to iron mains, at about ten-metre intervals (actually 8 metres for 200mm pipe, 12m for 150mm pipe), would protect them from corrosion so well that main breaks on the affected main would drop some 90% in a few years.

The Calgary Corrosion Technicians, all credit to Bill Ng, Brad James, Richard Roe, and Murray Hoines, who harried the engineers above them to listen to this and start a program to do it for much of the iron pipe in Calgary.

The early results are in this paper from over a dozen years back now: "A Report on the Anode Retrofit Program" (Microsoft Word document, sorry).

Around the same time, I was able to round up all the pipe that had been retrofitted, and count the breaks on all of it, with the "age" of how many months since retrofit: negative for before, positive for after. It looks remarkably like the Ottawa results from years earlier:

That's not much of a graph, not even axes, but the upshot was that by several years after that, I was doing graphs that modified the victory a bit: breaks had really "only" dropped by 80% from the treatment.

The huge win there is not just the cost saved from the breaks averted - that worked out to about 25 million or so, after 20 million dollars of retrofit. The huge win is how much main didn't have to be replaced for another 20 years - or more likely 40 or 60, since we are even now doing a second round of anode planted on mains first protected in 2000.

It's a pathetically underused strategy for infrastructure management. The graphs in the paper, from Ottawa, Durham, Edmonton, to NOT reflect major retrofit programs like Calgary's. Most cities except Winnipeg only did some experiments, and special case projects, compared to Calgary retrofitting 15-20km of main per year, until some 400km was done by 2017, when I left.

I'm aware that Winnipeg had a major program for some years, but when I called them again around 2015, it was terminated, the person who ran it had left, nobody knew much about it. I had heard that they didn't get a great reduction in breaks from their program.

I touted my own theory about that in presentations where I did brag about our pipeline inspection program, and my statistical, soil-resistivity-based, risk-calculation calculations for main replacement. I believe that Calgary's Anode Retrofit Program was so successful because we targeted mains for retrofit using the same risk calculations, soil-resistivity database, and pipeline-inspection knowledge that led our replacement program. My understanding is that Winnipeg just went up one street, and down the next, possibly protecting mains that were simply not at risk, diluting the effect.

For why corrosion-protection is so underused, particularly on the North American continent, one can't read a better story than "Rust", by Jonny Waldeman.