A major water main serving the Washington, D.C., metro area broke on the morning of Dec. 23, disrupting service and stranding motorists along a busy suburban artery for several hours. A 66-in pre-stressed concrete cylinder pipe burst along a section that neighbors State Route 190 in the D.C. suburb of Bethesda, Md., at 8 a.m. Several commuters were traveling the four-lane highway during the morning rush hour when the pipe burst.

Photo: AP/Wideworld

Motorist stranded by water main break in Washington, D.C., suburbs Dec. 23.

The pipe, which carries 135-million gallons of water per minute, sent torrents rushing down a nearly half-mile section of the road, stranding more than a dozen vehicles. At least 15 people were plucked from their cars by rescue workers in boats and helicopters throughout the morning. Three people were sent to the hospital, according to a Montgomery County police spokesperson, but there were no major injuries reported.

Eight contractors were called in by the Washington Suburban Sanitary Commission to provide an emergency analysis of the break and bid on the project, said Lyn Riggins, spokesperson for WSSC. The cause of the break was undetermined at press time, but a contractor was expected to be awarded and begin work by 7 p.m., she said. The break happened as local temperatures dipped into the 20s for the first time this winter.

Although the break was first reported at 8 a.m., the four main valves that control flow to the pipes could not be accessed and turned off until 1:15 p.m. Each valve requires roughly 400 cranks to shut off, Riggins said. Service was restored to local customers at 2 p.m.

Along that section, the pipe is buried between 10 ft and 15 ft below ground. It was put into service in 1964 and has a roughly 75-year life expectancy, Riggins said.

“We’re looking into if there are any potential manufacturer issues with the pipe,” she said.

The flood of water heavily damaged portions of a nearly half-mile section of State Route 190, also known as River Road, said David Buck, a spokesperson with Maryland State Highway Administration. Large portions of the shoulder had washed away and portions of lanes had been substantially compromised, he said.

“There will need to be significant borings up and down that entire section of road,” he said.

WSSC is expected to contract out any necessary work for repairs to the highway and coordinate with SHA, Buck said. Nearly two miles of road were closed in response to the incident.