Water Main Break

[49merc]

The picture on the attached link shows a section of 12" cast iron pipe that we had a break on recently. Any ideas on the cause? Most breaks caused by settlement are circular, this one is different. It was in a paved road, relatively light traffic, five feet of cover, no work going on nearby.

 

[tkall]

It looks like a split I saw once that was caused by a transient(water hammer). Are the air/vac valves all working?

 

[bimr]

Probably a water hammer. Could be a hydrant that was closed quickly or an immediate pump shutdown (caused by power failure).

The newer SCADA systems monitor the system pressure. Water hammers will show up as pressure spikes. I was at water supervisor's office and he showed me the evidence of a water main break. A graph showed when the fire department shut off a hydrant too quickly, causing a water hammer and then a short time later, a leak appeared.

 

[49merc]

tkall - there are only a couple of air release valves at some high points in our system, all appear to be working properly. We have four reservoirs, open to atmosphere,three with altitude valves, the fourth is fed from the filter plant and floats on the system. This main is somewhat in the middle of the grid of approx. 220 miles of mains.

 

[cvg]

even if they are working properly, air release valves may or may not be effective in eliminating water hammer. And hopefully they are combination air/vac valves, not just air release valves.