Tuesday, November 20, 2018

MAYBE A FIX FOR THE LEANING TOWER OF SAN FRANCISCO

by Bob Walsh

There may be a fix in the works for the Millennium Tower in San Francisco. Neither the builder nor the city saw it to be necessary to sink the foundations to bedrock and now the 50+ story building in settling, unevenly, and is significantly out of plumb.

The most recent plan suggestion calls for running piles down to bedrock (good idea there) thru the sidewalk adjoining the building to stabilize the most tilted side of the building, then let the other side catch up over a few years.

An earlier plan called for drilling thru the current foundation to seat as many as 300 micro-pillars all the way down to bedrock. That plan would have cost as much as it cost to build the building in the first place, $350 million. It would have also substantially disrupted the 58 story building.

The building has sunk 18 inches and is now 15 inches out of plumb. The current foundation is a 10 foot thick pad with 950 reinforced concrete pillars sunk 90 feet, but they do not go down to bedrock. There is clay under them, or even mud.

The city is already on the hook for over $15 million in legal fees. There are currently 146 lawyers involved in lawsuits against the building in some fashion or other.

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