San Francisco’s Stockton Tunnel near Union Square was closed to all vehicles Thursday as crews worked to repair a break to a 100-year-old water line in the area, a San Francisco Public Utilities Commission spokeswoman said.
A leak was reported just before noon on a 4-inch main near Stockton and Sutter streets, SFPUC spokeswoman Suzanne Gautier said.
Crews responded to the scene to stop the flow of water and repair the leak, she said.
No water service in the area had been interrupted, she said.
The 30-Stockton and 45-Union bus lines were rerouted around the closed tunnel, Muni spokesman Paul Rose said.
Water bubbled from under the street and crews assessed possible damage to the pavement near the tunnel, she said.
Gautier said the break is due to the old age of the pipe, which dates to 1914, and is not connected with construction on Muni’s Central Subway project.
A boring machine is located about 100 feet north of where the leak occurred. The machine is being used underground to carve out a tunnel for the new subway line that will eventually connect passengers from the Caltrain station to Chinatown, according to Rose.
The cause of the leak was under investigation, she said.