WSSC’s Water Main Inspection Program

WSSC’s large main inspection program and acoustic fiber optic monitoring system saved property and lives.  It detected a failing water main before it could break, preventing another “River Road.” A large main there broke three days before Christmas, turning Montgomery County’s River Road into a real river that required boats and heroics to rescue motorists caught in the flood. 
 

Our large mains are more than just pipe.  They have coats of steel, concrete, and high tensile pre-stressed wires to make the pipe stronger and last longer.  Over time, corrosion can cause the wires to fail.  In this case, our monitoring system heard telltale “pings” made by a few of those wires giving way.  This signaled the deterioration of one 16-foot section of a 96-inch main near Tuckerman Lane and Gainsborough Road in Potomac, MD. 
 

WSSC responded quickly to shut down a ¾-mile portion of the line and begin repairs.  The monitoring system, put in place during the main’s last inspection in 2007, proved its worth.
 

The monitoring system is part of WSSC’s large water main inspection program.  It covers 77 miles of mains 48-inches and larger.  It focuses on the larger mains because their capacity and pressure can cause serious damage if they fail.
 

The program uses visual inspection and three kinds of technology:

• A “smartball” microphone that listens for leaks as it floats through the operational main.
• When the main is dewatered for visual inspection, P-wave electromagnetic equipment checks for wire breaks.
• Then WSSC installs acoustical fiber optic monitoring (AFO) to continuously monitor for wire breaks after water flow is returned.

So far, about 28 miles of WSSC’s large mains are equipped with acoustic fiber optic monitoring, with another 8 miles being completed.