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RonO's Ramblings

Dec. 11th, 2009 06:50 am Pondering -- Water Infrastructure Problems

This morning, one of the stories on the San Diego local morning news was about the third water main break in four days. The way the writer wrote the story (and the anchor read it) made it sound like they were surprised at this spate of water main breakage. We had a similar spate a month or so ago.

I'm suspicious that it is not coincidence that we've gotten multiple breaks in the past few days.

The reports say that the water infrastructure is old, cast iron, pipe and is due for replacement -- which is in progress. So having pipes break at all isn't all that surprising.

But I suspect that there may be a couple of reasons why they seem to come in bunches -- and not because of the old saying that "bad things happen in threes." I can think of two possible reasons for having them happen in bunches.

First, we had very heavy rain on Monday. This saturated the ground -- which is pretty sandy around here -- so some of the ground may have shifted, or washed out creating areas of higher strain or less support on the buried pipes. That wouldn't explain the spate several weeks ago when it had been dry for months.

But, my second thought might. I wonder if the San Diego city water infrastructure is sufficiently tied together that the act of shutting off water in one part of the city could cause enough extra pressure in the pipes to stress to the point of breaking (a day or two later) a week spot in pipes in a different part of the city. I've not looked at a map to see how closely bunched the breaks have been this time, or last, so I don't know how likely this explanation is. But I do wonder.

Of course, I'm not a water systems engineer, nor do I play one on TV or the Internet, so I'm probably just making guesses based on a dangerous amount of knowledge.

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