WSSC Says Monitoring System Didn’t Fail In Chevy Chase Water Main Break

Water main break at Connecticut Avenue and Chevy Chase Lake Drive, via WSSC

WSSC officials today said they still don’t know what caused the major water main break on Connecticut Avenue  last month, but that the fiber optic monitoring system meant to warn of breaks did not fail.

WSSC chief engineer Gary Gumm told the Montgomery County Council’s Transportation & Environment Committee that the acoustic fiber optic (AFO) monitoring system did not warn of the break because it only detects pings or snapping sounds of steel wires that support the system’s major water PCCP mains. Because the steel wires at the Connecticut Avenue break did not snap before the break, WSSC had no notice of what was coming.

“That is a distinction however that has very little comfort to our community because the purpose of the AFO system is to give us warning,” said Councilmember Roger Berliner (D-Bethesda-Potomac) who organized today’s hearing the day after the break. “That’s a source of great anxiety for our community.”

A resident did report a leak near the 60-inch main at 1 p.m., about seven hours before the March 18 break, which led to a geyser of water near the intersection of Connecticut Avenue and Chevy Chase Lake Drive in Chevy Chase. The damage left downed power lines, a torn-up lane of Chevy Chase Lake Drive, traffic problems on Connecticut Avenue and a mandatory water use restriction for the county.

Gumm said the crew that responded to the leak acted appropriately, determining it came from a valve that could be repaired the next morning.

The full forensic report is expected in June.

“We did not know that this type of pipe might fail without the wires breaking first,” Gumm said. “Water was seen bubbling out of a valve on Connecticut Avenue. In hindsight, a mistake was made there. …What I think we learned with this one is I think they did everything that they’re supposed to do. When these valves are in the vicinity of some of these larger pipes, again I think we need to take a little more time, put a little more effort to try and make sure we’ve isolated it to the valve and not to the PCCP line.”

Gumm indicated that the atypical shape of the pipe at the point where it broke might have had something to do with the break, which WSSC has categorized as a catastrophic failure. Gumm said 11 other large mains have been repaired or replaced since 2011 because the AFO system detected snapped wires. One other repair is scheduled to begin in May.

When pressed for more details on how atypical the pipe was, Gumm said only about three percent of WSSC’s large PCCP water mains are similar.

Berliner and Councilmember Hans Riemer (D-At large) also questioned WSSC general manager Jerry Johnson and Gumm about the agency’s inspection and repair schedule. The scheduled shutdown of several large water mains at the time of the March water main break, including a 96-inch main from WSSC’s Potomac filtration plant to Tuckerman Lane, ultimately led to the mandatory water restrictions. The 96-inch main has been closed since the fall.

“Perhaps we have learned in this exercise that we could have done a little better. Instead of waiting for the entirety of the report or recommendations for repairs, our contractor vehicles do allow us as we know things to get started on them,” Gumm said. “We could probably shave some time off the repair process by doing that.”

Berliner asked Johnson for a comparison of WSSC’s performance to systems in other jurisdictions. He also discussed WSSC’s request for 80-foot setbacks for all buildings near major water mains such as the one that broke in Chevy Chase and repaving work from WSSC contractors after standard neighborhood water main repairs.

The full report WSSC officials gave the Committee today will be published on Montgomery County’s website.

Photo via WSSC


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