SFPUC

Water pipeline snapped Nov. 25 at a poorly designed joint, flooding South San Francisco streets

San Francisco acknowledged Tuesday that its faulty design was responsible for a water main break that flooded homes and damaged cars in South San Francisco last month.

The agency said it failed to ask a contractor to install welds or similar restraints needed at a joint when it installed the new water line. The SFPUC discovered six similar design flaws for planned projects during a search of its records following the Nov. 25 flood, but not in any pipelines currently in use.

“There’s no excuse,” Steve Ritchie, water manager at the San Francisco Public Utilities Commission (SFPUC), which owns the reservoir and the pipeline, said during a press conference Tuesday. “It was human error that caused it.”

The joint broke on the Friday after Thanksgiving, just four days after water began flowing from Crystal Springs Reservoir through the new main. The SFPUC said it took crews more than three hours to shut down the 60-foot high jet of water that flooded Elm Court and nearby streets.

The Menlo Park-based firm Exponent Failure Analysis Associates, hired by the SFPUC to analyze the rupture, found that an SFPUC contractor failed to install harnesses, welds or other forms of “restraint” where parts of a new 12-inch section of pipeline were screwed together.

“It is well known in the waterworks industry that such couplings need separate means of restraint,” Exponent officials wrote in a 25-page preliminary report released Tuesday. “[The pipeline manufacturer] Smith-Blair warns accordingly in their product literature.”

Ritchie told The Bay Citizen that the blueprints the SFPUC prepared did not include the needed restraints. “The contractor is responsible for constructing what we design,” Ritchie said.

Ritchie said the agency has reviewed 35 similar joints that are being replaced or installed as part of the agency’s $4.6 billion Water System Improvement Program, which is designed to upgrade the network of pipes that delivers water from Yosemite National Park to the Bay Area.

Of those 35 joints, six were found to have similar flaws — and Ritchie said blueprints for those joints would be corrected before the parts are installed.

When asked why it took the SFPUC three hours to shut off the flow of water, Ritchie explained that shutting down water pipelines takes a long time, at least 45 minutes, but he said that lessons learned last month would reduce the agency's response time in the future.

“We will get to it faster next time,” Ritchies said.

The full cost of the flood is still not known, but Ritchie said six home owners and nine vehicle owners have filed claims with the city seeking damages. The city of South San Francisco is also planning to submit a bill for the damage it sustained and for clean-up costs, according to Ritchie.

James Hardy, a program manager with South San Francisco’s public works department, declined to comment on the report because it contained preliminary findings.

“Our concerns are going to be to make sure it doesn’t happen again,” Hardy said.

Watch video of the flood on Youtube: