Pipes disturbed by nearby construction caused 25 percent of all breaks recently surveyed, a “significant percentage,” according to documents on file with the San Francisco Public Utilities Commission.
That marks a four-year high of potentially costly water main breaks stemming from building, according to documents.
While excavators are causing a portion of the damage, much of The City’s pipe infrastructure is at risk of rupturing at any time due to advanced age, documents show.
Cast-iron pipes installed between 1920 and 1950, such as the ones that popped near Joost Street last week and near Wawona Street last spring, are breaking with the most regularity: more than 90 percent of breaks last year were in pipes from that era, according to the SFPUC. Seventy-five percent of all The City’s pipes are 40 years of age or older.
More construction is afoot in San Francisco today, with the tech-fueled economic boom making a crane-crazed city skyline higher and higher.
But water officials say all the building and related digging — including gas and electrical work, as well as an ongoing sewer replacement project — isn’t an extra risk to busting open a water pipe.
Instead, the construction illustrates why a project to replace The City’s water infrastructure network is necessary, according to Tyrone Jue, a spokesman for the SFPUC.
“The breaks aren’t all from old pipes,” he said.
No data on which companies caused the most breaks — or how many were working on projects for The City — were available from the SFPUC.
The commission is planning to ramp up pipe replacement efforts, from 6 miles of new water mains laid per year to 15, according to Jue.
Over half of the SFPUC’s 1,241 miles of pipe are made of cast iron or made in the era from 1920 to 1950, which is even more likely to fail than other older or newer pipes, according to the SFPUC. Replacing the infrastructure “is positive for our public,” Jue said.
The City believes a contractor is to blame for the worst water main break in recent memory. Property owners have to date filed $1.3 million in claims after a large water main broke last spring and caused flooding damage to more than 70 homes at 15th Avenue and Wawona near West Portal, according to the City Attorney’s Office.
That water main ruptured after a construction firm contracted with The City to replace sewers dug up the area, according to the SFPUC, which Jue said is in the process of reaching a payment settlement with contractor Precision Engineering.
The SFPUC did not have information on the names of contractors or construction companies involved in other recent breaks.
The City can be held liable for damage to homes caused by water main breaks if city-contracted work led to the break.