The engineer in charge of the troublesome repair of the Millennium Tower admitted Thursday that the building has continued to slope at about 3 inches a year since work began.
He also revealed that his team had not given the fix contractor any instructions to prevent the tower sinking and tilting from getting worse from drilling and digging around two sides of the foundation.
City overseer Aaron Peskin appeared tired Thursday of holding multiple hearings over the past five years on the fate of the sinking and leaning tower, which is now sloping about 26 inches north and west on the corner of Fremont and Mission Streets.
Surveillance data shows that there was 10 inches of this dip and about 5 inches of subsidence while working on what is known as the fix last year.
“We’re starting this new year 2022 the way we ended it last year and many other years, with the Millennium Tower continuing to sink and topple,” said a clearly annoyed Peskin, before introducing fixed engineer Ron Hamburger to the hearing.
In his remarks, Hamburger admitted for the first time that his team had not given Shimmick Construction, the permanent contractor, any initial indications as to how the effects of the drilling and excavations for the installation of steel support piles could be limited.
“The procedures for laying piles were basically the prerogative of the contractor,” said Hamburger the city inspector. “We didn’t tell them how to install stakes. We have indicated that we need piles of a certain diameter and strength. And he basically created these as a design build to install the stakes in which he set out the methods he would use to install them. “
Peskin reached out to city officials, who assured him that this was standard practice on such projects.
“This is a 50-story building, very heavy, in the heart of downtown San Francisco,” countered Peskin. “I don’t think there’s much room here for learning in the workplace.”
Hamburger separately announced that the building continues to lean at a rate of three inches per year.
“The building continues to settle at a rate of about half an inch a year and lean at a rate of about three inches a year,” he said. “It does this regardless of whether we work on site or not. The building will remain secure, but while the building will remain secure, we believe the project must resume construction and complete this construction quickly. “
At the current speed, the tilt of the tower could reach its functional maximum of 40 inches – the point at which, according to Hamburger, the elevators and plumbing may stop working – in just a few years without the repair. Installing 18 steel piles in the bedrock is now the best way to stop the tipping and possibly reverse some of it, he told supervisors.
“It is in everyone’s interest that this project be completed as soon as possible,” he concluded.