The engineer responsible for the troubled fix of the Millennium Tower acknowledged Thursday that the building is continuing to tilt about 3 inches a year since work began.
He also revealed that his team did not provide any instructions to the fix contractor on ways to prevent the tower’s sinking and tilting from getting worse from drilling and digging around two sides of the foundation.
City Supervisor Aaron Peskin appeared Thursday weary of holding multiple hearings over the last five years about the fate of the sinking and leaning tower, which is now tilting some 26 inches north and west at the corner of Fremont and Mission streets.
Monitoring data shows that 10 inches of that tilt and about 2 inches of settlement occurred during work on the so-called fix last year.
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“We start this new year 2022 as we ended last year and many other years, with the Millennium Tower continuing to sink and tilt,” a clearly exasperated Peskin said before introducing fix engineer Ron Hamburger at the hearing.
In his remarks, Hamburger acknowledged for the first time that his team did not provide any initial guidance to Shimmick Construction, the fix contractor, on ways to limit the impact of the drilling and digging to install steel support piles.
“The procedures for installing piles were basically the contractor’s prerogative,” Hamburger told city supervisors. “We did not tell them how to install piles. We specified that we needed piles of a given diameter and strength. And he basically did those as a design build to install the piles in which he determined the methods by which he would install them.”
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Peskin turned to city officials, who assured him that was standard practice for such projects.
“This is a 50-plus story building, very heavy, in the heart of downtown San Francisco,” Peskin countered. “I don’t think there’s a lot of room here for on-the-job learning.”
Hamburger separately revealed that the building continues to tilt at the rate of three inches per year.
“The building does continue to settle at a rate of about one half inch per year and to tilt at a rate of about three inches per year,” he said. “It is doing this whether we are conducting work at the site or not. The building remains safe, but although the building remains safe, we believe the project needs to resume construction and complete this construction quickly.”
At the current rate, the tower’s lean could reach the functional 40-inch maximum – the point Hamburger says the elevators and plumbing may not continue to operate – in just a few years without the fix. Installing 18 steel piles to bedrock now is the best way to stop the tilting and possibly reverse some of it, he told supervisors.
“It’s in everyone’s interest that this project is completed as quickly as possible,” he concluded.