Despite the gap, engineers “determined that the building is not at risk due to this movement, or any movement likely to occur before construction completion”, Hamburger said, and the gap is not expected to worsen. He has previously warned that the tower’s elevators and plumbing may no longer work if sinking continues at its current rate.
Engineers are working on a retrofit of the building and plan to install 18 steel piles to bedrock, relieving pressure on the foundation, to stop further tilting and sinking as well as possibly reverse some of the movement.
“Once the voluntary upgrade is complete, further settlement of the building at the northwest corner will be arrested, some rebound will occur, and slight additional settlement of the rest of the main tower will act to reverse the tilting that has occurred and close the gap between the elevator thresholds in the adjacent podium building that connects the main tower and mid-rise together,” Hamburger told the San Francisco Chronicle.
Previous efforts to reinforce the foundation of the downtown tower came to a halt last summer, when engineers found the building had sunk an inch in the months since the attempted repairs started.