Repairs paused on sinking S.F. tower
Increased settling noted at Millennium high-rise
The $100 million fix meant to shore up San Francisco’s famously sinking and leaning Millennium Tower has been put on hold for up to a month while engineers try to figure out why the building has settled an additional inch during the current remedial construction.
In a statement, a spokesman for the Millennium’s homeowners association said that the latest monitoring of the building has “indicated an increased rate of settlement associated with pile installation.”
A pile is a column — steel, wood or concrete — driven into the soil below a building to provide foundation support.
“Out of an abundance of caution, we have placed a two- to four-week moratorium on pile installation while we try to understand better the mechanisms associated with the increased settlement rate and available means of mitigating this,” said Doug Elmets, spokesman for the building. “There has been no material harm to the building and it remains fully safe.”
The pause in construction was first reported by NBC Bay Area.
The 60-story luxury tower at 301 Mission St., completed in 2009, was the most expensive residential project in the city’s history and drew high-profile residents like former 49ers quarterback Joe Montana. But five years later the building became notorious for another reason: Engineers monitoring its settlement discovered it had sunk 18 inches and was leaning 14 inches to the west.
The shifting foundation — experts concluded that the building’s piles should have been driven to bedrock — sparked lawsuits from residents against the developer, Millennium Partners, as well as the architect and engineers who designed the concrete and glass building.
A 2020 confidential settlement not only compensated homeowners for value lost due to the construction issues but also included a $100 million fix: 52 concrete, 140,000-pound piles that will anchor the building to bedrock 250 feet below ground.
The two-year project was billed as a way to relieve stress on soils that have compressed beneath the building, contributing to its unwelcome and unanticipated sinking.
“This plan halts settlement along Fremont and Mission streets while allowing the building to level itself over time,” said project engineer Ronald Hamburger of Simpson Gumpertz & Heger, at the time construction started.
Hamburger didn’t immediately return a call seeking comment about the most recent settlement.
While the building has continued to sink during construction, Elmets said the outlook is still positive.
“Once pile installation is complete and load is transferred to the new piles, the building will experience substantial improvement and begin to recover some of the tilting that has occurred over the years,” he said.