Acoustic monitors help DPW avert "catastrophic" water main break

Posted at 6:17 PM, Jun 29, 2017
and last updated 2017-06-29 18:17:41-04

You hear about the breaks, the sewage blocks, even explosions, but very rarely the opposite.

This past month, Baltimore City Department of Public Works prevented a potential water main catastrophe.

“You have a 54 inch pipe, essentially 4.5 foot wide pipe full of water, under high pressure, had that failed, the result could've been catastrophic,” said Jeffrey Raymond, chief of communications and community affairs with the Baltimore City Department of Public Works.

Raymond is referring to the Southwest Transmission Main that delivers water to thousands of people in Baltimore and three surrounding counties.

A section of the pipe in southwest Baltimore under Desoto Road showed signs of bursting. The wires wrapped around the concrete pipe started to snap.

“That indicates there is potentially an imminent failure,” said Raymond.

The wires were part of the pipe's design when it was installed back in 1970. They lend strength, and now they serve an additional purpose.

“Utilities noticed that these pipes had a tendency to fail, then there was the acoustic monitoring system developed to listen to those wires as they failed,” said Raymond.

That system was installed back in 2007. Ever since, anytime a wire snaps there's a ping that alerts engineers.

Beginning late last month, the monitoring system alerted DPW to 15 wire breaks in two weeks in one 16-foot-long segment of the pipe.

The pinging prompted crews to start work within days. Crews installed high strength post-tensioning tendon cables around the distressed section to provide extra security.

“We were able to make this fix for about $200,000. Had there been an emergency, had the pipe broken, water spilled, who knows what it could've cost,” said Raymond.

When a leaky sewer line caused several sinkholes last year around Mount Vernon, repairs totaled $20 million.

However, the acoustic fiber optic monitoring system couldn't have helped in that situation. It only applies to specific pipes outfitted with the wires.

And with aging infrastructure and 4,000 miles of water main to operate, DPW must prioritize what they monitor and replace.

“We do a minimum of 15 miles of water main repair and replacement every year here in this City,” said Raymond. “So, it's literally a 100-year replacement cycle that we're on right now.”

DPW prioritizes larger pipes that serve more people as well as ones that serve critical care customers such as hospitals or schools.

The agency also announced last year that there's been a dramatic decline in water main breaks since 2014.

In 2016, there were 798 water main breaks, the first time in recent memory that the agency had less than 1,000 water main breaks per year.

DPW attributes the reduction to their assessments and replacement program.