Tilting Millennium Tower in San Francisco Faces New Plumbing Downside – NBC Bay Space
The designer of the problem solution for the sinking and tilting Millennium Tower recently informed city officials of a particularly nasty potential by-product of the building’s settlement – sewer stagnation, the NBC Bay Area investigative unit learned.
“The sewer pipes must be inclined (at least 1/8 inch per foot) to allow an efficient flow of materials,” said Ron Hamburger in an email to the city administration at the end of August. He identified endangered drains that are currently sloping south and east – contrary to the current northwest slope – and said that these lines “may experience reduced slope and become a problem.”
The sewer warning was part of an assessment of the “functionality” of the building, as the building tilted another five centimeters during the work on the so-called fix that began in May. This project is currently on hold, awaiting testing and analysis, which triggered the unexpected, accelerated turnaround.
Hamburger told city officials that experts are assessing the stress on the vertical pipes due to tilting, while engineers have found no signs of “stress” in the elevator system.
With the building now sloping 22 inches to the west, experts predict the sewer problem will worsen as the slope has flattened the angles of some drain lines by up to 25 percent.
“Some clogs” have already occurred in the drains in the owner’s lounge kitchen on the third floor, Hamburger said in his email summary to city officials, and now require “regular chemical flushing” to service them.
“It may be necessary to adjust these and other lines to restore the slope,” remarked Hamburger in a presentation to city officials.
“There’s a problem with too little or too much slope, problems can arise either way,” says Mark Savel, an architect and contractor with three decades of experience analyzing building failures like the balcony collapse in Berkeley in 2015 .
“You can expect a blockage or a backlog of the system – so the existing system should be inspected and monitored,” says Savel.
Meanwhile, given the health hazard associated with massive backups, residents risk losing entire wooden floors and walls, Savel says. The risk is particularly high when people use the system at the same time.
“On the days when the house is full of people, a public holiday or a special occasion is celebrated,” he says, “then you finally call Roto-Rooter. Because the system you have is being put to the ultimate test. “
Savel says facility managers should first commission a video inspection of all lines to identify immediate risks and long-term problems.
Any final correction that would involve adjusting the height of hundreds of pipes to allow proper flow should wait for the descending and tilting structure to fully stabilize.
