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Update on the saga of the “Leaning Tower of San Francisco”

Millenium Tower

Construction on San Francisco’s Millennium Tower in 2007. Photo credit to Kevin Armstrong and used through a Creative Commons license from Flickr. Copyright by Kevin Armstrong.

Last year, I reported on the claims swirling around the 58-story Millennium Tower in San Francisco that has sunk about 17 inches and tilted 14 inches to the west and 6 inches to the north since it opened in 2009. Not much has changed in a year; litigation is still on-going and the parties are still feuding, but the San Francisco Chronicle has reported that a fix has been proposed.

The proposed fix is unconventional and expensive. It recommends drilling piles down to bedrock to stabilize one side of the building while allowing the other side of the building to continue to sink until the building straightens itself out.

The building currently sits on a 10-foot thick mat foundation held in place by 950 reinforced concrete piles sunk 60 to 90 feet deep into clay and mud. The piles don’t, however, reach bedrock. The proposed fix recommends boring 275 to 300 steel and concrete “micro piles” down to bedrock. First, crews working inside the Millennium’s basement would drill half of the new piles on the west side of the building. Once it’s stabilized, the east side would be allowed to sink long enough for the building to straighten itself out. Then the rest of the piles would be drilled to bedrock to keep everything from sinking further.

The entire process could take 2 to 5 years and cost anywhere from $200 million to $500 million.

The attorney representing the HOA has stated that the general contractor and engineers are working with the city to obtain needed approvals and permits. Not all of the parties, however, are on board with this solution. One attorney who represents 265 owners said that the only real fix would be to demolish the building and rebuild it, possibly costing billions of dollars. Nevertheless, sidewalks are already being torn out and drilling equipment is expected to arrive shortly to bore a pair of holes deep into the ground to test the conditions of the soil and bedrock below.

Although Millennium Partners, the developer, is funding the soils testing, all of the feuding parties, including the Transbay Joint Powers Authority, the owners of Salesforce Tower, the City of San Francisco, and various engineering and design consultants, still have to work out an agreement to fund the repairs and compensate the homeowners.

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