DWP Identifies Suspects in Attack on Fire Truck
We're looking at you, corroded pipes.
There's plenty of blame to go around when it comes to the city's water main breaks.
A report issued by the DWP cites corroded pipes, outdated construction methods, elevated reservoir levels and operation changes made in response to previous leaks.
The preliminary report was released Tuesday by the Los Angeles Department of Water and Power at the City Council's request. One of the ruptures created a sinkhole that swallowed the cab of a fire engine and forced its crew to scramble to safety.
The investigation drew no firm conclusions but said that in addition to the DWP's decision two years ago to increase the rate of water main replacement, better methods of prioritizing the mains
must be developed.
The report said examination of pipe samples removed by repair crews found rust, corrosion, microfractures and other problems. It said much of the failed pipe was installed 70 to 90 years ago with old-fashioned practices involving bedding material and backfill that created corrosive soil environments.
The report also noted that most of the summer leaks coincided with a rise in the elevation of the Lower Franklin Reservoir above Beverly Hills and an increase in pressure of about 4 pounds per square inch. The report said the reservoir's elevation was in the normal operating range but pipe leaks have previously occurred when elevations are raised after an extended period at a lower
elevation.
Most failures involved cast iron pipes, which often rupture in the form of a long split that makes the leaks larger and cause greater street damage, the report said.
The DWP said water main breaks that damaged Coldwater Canyon Avenue near Ventura Boulevard in Studio City on Sept. 5 and another Sept. 8 near Laurel Canyon Boulevard -- that's the one that created the sinkhole that swalloed the fire engine cab -- may have been related.
Both were located in the same service zone and involved significantly corroded pipes. The pipe under Laurel Canyon had localized corrosion that coincided with a tree root growing along the pipe.
"It cannot be stated definitively that the breaks were related, but there is a possibility that they were," the report states.
