The Leaning Tower of San Francisco 

  
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A new fix has been proposed to help stop San Francisco’s Millennium Tower from continuing to shift. Since the tower’s opening in April 2009, it has sunk 18 inches and tilted 14 inches to the west.

The new proposal reportedly will stop the sinking but will not correct the tower’s tilt.

What Happened

In April 2018, a fix was proposed that would cost nearly the same as the original cost to build the tower—$350 million.
 
According to the San Francisco Chronicle, the 58-story tower sits on a 10-foot-thick mat foundation, held in position by 950 reinforced concrete piles sunk 60 to 90 feet into clay and mud, which do not reach the bedrock. To fix the leaning issue, engineers suggested boring 275 to 300 steel and concrete “micro piles” down to bedrock, only on one side of the building at a time, starting with the west side.

Once the structure is stabilized, the east side would be allowed to sink until the building straightens itself. Then, micro piles would also be driven into that side, preventing the structure from sinking any further.
Those repairs would have taken two to five years, and the homeowners’ association was not happy with the suggestion.​​
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A new fix has been proposed to help stop San Francisco’s Millennium Tower from continuing to shift. Since the tower’s opening in April 2009, it has sunk 18 inches and tilted 14 inches to the west.


What Now

In November of 2108, however, the Chronicle reported a consensus on the horizon.


This plan calls for drilling piles into bedrock from the sidewalk on the building’s north and west sides, instead of the micro piles going into the bedrock through the concrete foundation.


Ronald Hamburger, a structural engineer for developer Millennium Partners, is behind the new plan, which he says will be less expensive, faster and with less disruption to the residents. ( VideoLink)

This idea will take several months to complete, according to officials, who note that nothing has actually been submitted to the city yet.