By Jaxon Van Derbeken : msn – excerpt (NBC video link on youtube )
The Millennium Tower may be the most recognizable sinking building in the city, but one researcher says earth-based and space-based observations confirm the entire downtown area around it is sinking as well.
“I looked at every building in the Bay Area, so just under a million buildings,” said U.S Geological Survey research geophysicist Tom Parsons, who estimates that over the last century, 3.5 trillion pounds of development and human activity – including the subsidence tied to loss of groundwater — have led to an estimated settlement of three inches across the entire Bay Area.
“Clearly, the most density and the tallest buildings are centered in that downtown San Francisco area, and that’s where we see the most calculated cumulative settlement from all of those buildings together,” he said.
Turns out that at an estimated 686 million pounds, the Millennium Tower is the third heaviest building in the city. The top nine all weigh more than 300-million pounds, but the only one that’s leaning significantly is the Millennium. Groundwater loss from adjacent construction has been blamed for the problem by the tower’s developers, while geotechnical experts say the key is that its foundation is not rooted in bedrock…(more)
Too bad CEQA environmental reviews do not include a report on the foundations and that our local ordinances do not require that engineers who design foundations communicate with engineers who design the buildings they rest upon. Perhaps this is something our city authorities should consider doing as they build denser, higher and heavier buildings. The cumulative effects of the loss of ground water should concern them as well. Who among our city representatives will take it upon themselves to fix the problem in our seismically challenged city?