A portion of a major downtown street and Bay Bridge approach that was closed during Thursday’s evening rush hour has been re-opened this morning. All lanes of traffic opened on First Street as of 9 a.m., according to Tony Winnicker, spokesperson for the San Francisco Public Utilities Commission.
A water main break caused a massive sinkhole that forced the closure of First Street at Howard Street Thursday afternoon, just before the start of the evening commute, officials said.
Working through the night, crews repaired the main and repaved the street. The two easternmost lanes re-opened at about 6:45 a.m., Winnicker said. The two westernmost lanes are expected to re-open at about 9 a.m., after the new concrete dries, Winnicker said.
The break happened when a newly installed supply line serving two nearby buildings separated from the main, causing water to flood the ground under First Street, Winnicker said.
“Water has a lot of power. It essentially washed away everything under the street that wasn’t fixed. It undermines the street,” Winnicker said. With no dirt to hold it up, the surface of the street collapsed, he said.
“Last night they pulled out all the debris, which took some time. They had to be careful because there are many other utilities under that street,” Winnicker said. Water service to two buildings was restored at about 2:30 a.m.
The separation of the supply line from themain remains a mystery. “The new service line literally pulled apart from the main. Whether it had to do with the pipe itself or the way it was attached, that’s what we have to determine,” Winnicker said. He said the section of pipe that separated has been taken to the commission’s dispatch yard for inspection.
“We’ll see if there are any lessons to be learned fro this to make sure it doesn’t happen again,” Winnicker said.