Why Did the Water Main Fail in Chevy Chase?

The massive 60-inch water main break that broke on March 18 on Connecticut Avenue in the Chevy Chase Lake neighborhood failed due to a combination of conditions, Washington Suburban Sanitary Commission officials said Monday morning:

First, the wires running through the concrete pipe section were not adequately pre-stressed at the time of the pipe’s manufacture.

Then, a slow leak from the gasket joining the main 60-inch main with a smaller, 24-inch pipe led to a chemically and physically weakened mortar joint, and the water leak corroded the wires and steel cylinder inside the concrete pipe, WSSC officials told Montgomery County Council’s Transportation, Infrastructure, Energy and Environment Committee on Monday.

WSSC has identified 234 similar pipe sections—70 percent of which are in Montgomery County—in its system, and will be inspecting them to see if they are likely to suffer the same fate as the Chevy Chase Lake section, Gary Gumm, WSSC’s chief of engineering and construction, said.

This is the first time that this type of pipe section has failed, Dave Burke, technical services group leader for WSSC, added.

The water main break in March created a massive geyser, and the loss of 60 million gallons of water led to mandatory water restrictions for nearly a week in Montgomery and Prince George’s counties. The geyser eroded an embankment in the area of the pipe section, which caused a traffic light pole to collapse. The entire embankment area had to be rebuilt once the pipe was fixed, Patch reported.