Cause of Pipe's Failure May Take Weeks to Find
Thursday, December 25, 2008
Experts said yesterday that they probably won't know for at least six weeks why a 66-inch water main burst beneath a Montgomery County road Tuesday, trapping commuters in a torrent of water and prompting rescue efforts that were broadcast around the world.
Among the possible causes, they said, was corrosion of metal support wires inside the concrete pipe, which passed its last inspection in 1998, or shifts in the ground beneath it.
"Something has happened in the last 10 years, and we hope to figure that out," said Gary Gumm, chief engineer for the Washington Suburban Sanitary Commission.
Maryland Gov. Martin O'Malley (D) and Montgomery County Executive Isiah Leggett (D) yesterday visited the 30-foot by 50-foot crater along Bethesda's River Road left by the pipe rupture. It was filled with muddy water.
"It looks like a bomb went off," O'Malley told a repair crew manager.
He and Leggett pledged to reopen a mile-long section of the vital commuter route as soon as it was safe, perhaps by rush hour Monday, and to try to secure federal funds to shore up the state's water supply system.
"It underscores the importance of investing in the things our parents and grandparents built for us," O'Malley said, referring to the pipe and broader infrastructure needs nationwide.
The WSSC, owner of the 44-year-old water main, plans to hire a consultant to examine it, a process the utility calls an "autopsy." Already, workers have collected pieces of the pipe and will use them to reconstruct its condition before it ruptured shortly before 8 a.m. Tuesday.
"It's sort of like piecing the skeleton together," said Dave Alexander, a manager in charge of the repair project.
At its peak Tuesday morning, the broken main was gushing 150,000 gallons of water a minute onto River Road near Fenway Drive, a short distance from Congressional Country Club. The break occurred above a sloped section of road that is bordered on both sides by embankments. The water had nowhere to go but along the road, and the torrent developed such force that even at 18 inches deep it was threatening to send stranded commuters and their vehicles hurtling downhill.
"The water was tunneled between the two side banks," said Master Firefighter Donnie Simmons. He and Battalion Fire Chief Jim Resnick compared the River Road chute to Mather Gorge in the Potomac River.
Rescuers reached the stranded motorists by truck, boat and helicopter. From the air, they had to lower a rescue basket between trees and power lines in an opening less than 40 feet across.