Public Works Director Patrick Wiemiller says the city hasn't been able to determine why the pipe broke. "We don't fully understand what the hydraulic event was that caused a pipe to burst."
Wiemiller notes the pipe that burst met city requirements when it was installed seven years ago, but is thinner than the current city standards. The pipe that burst is 14 inches in diameter, the walls are 5/8 of an inch think. A little over half an inch. The city currently uses the same diameter pipe that is 7/8 or just under and inch thick.
Wiemiller says it's not clear if the thinner walls were a factor. "We've had a couple of incidents of this thickness of pipe occur and we've had incidences of the thicker wall pipe burst as well, not enough of one over the other to make any statistically valid conclusions from that. "
Repairing this latest leak cost the city about $65 thousand and inconvenienced a lot of people. With tens of miles of this thinner walled pipe installed between roughly 1985 and 2005, Wiemiller says the city is taking a closer look at all of its past water main breaks to see if the thinner pipes installed by developers during the city's building boom are a cause for concern.
Weillmiller says replacing all that pipe would cost the city millions a cost he says the city can't afford, especially if problems appear to rare.
Action News contacted the pipe manufacturer, JM Eagle Company. A company spokesman said the company has had no problems with the pipes, and note they come with a 50 year guarantee. He said the company would be happy to investigate the damage if the city of Fresno wants to file a claim.
At this point the City of Fresno says while they made the move to thicker pipes there is not enough evidence to say the thinner walled pipes are any more likely to burst.