Tilting a Little to the Left

Here’s another reminder why that geotechnical report is so important.

The Millennium Tower, a 58-story apartment building in San Francisco, is slowly sinking—more on one side than the other, unfortunately, so it now has a distinctive tilt. The building is located in one of the many parts of the city built on land fill—that is, an area that’s been built up from dredged material, not on an actual closed municipal waste landfill.

Even before the building opened in 2009, engineers and the city inspector were aware that it had sunk more than 8 inches but felt that the situation was “under control.” It has continued to sink about an inch a year, and a geotechnical engineer currently investigating now believes it could sink as much as 31 inches altogether. Some walls in the five-story underground parking garage have floor-to-ceiling cracks. The building now tilts about 2 inches at the base and has a lean of 6 inches at the top. (For comparison, as this article points out, Italy’s Leaning Tower of Pisa—to which the inevitable comparisons have been made—leans about 16 feet.)

Some residents believe the problem is a design flaw; the building is not supported by piles that go down to bedrock, some 240 feet down, but rather by 60- to 90-foot piles driven into the land fill. A spokesman for the Millennium Group, which built the tower, insists the construction method was sound, and the building is safe. The sinking, he says, was caused by work on an adjacent construction site for a transit hub, where millions of gallons of groundwater have been pumped out, destabilizing the soil underneath the apartment tower. The public agency responsible for the transit hub denies that, however, and says the apartment building was already sinking before the agency’s own excavation work began.

Land fill or infill areas such as this are more susceptible to seismic activity than is bedrock, so many of the residents are worried about safety if—or rather when—the next earthquake strikes. They’re also worried about resale value. The building contains 419 pricey apartments, which initially sold for anywhere from a couple of million to $10 million for a penthouse unit.

StormCon 2017 Call for Papers Is Open

StormCon, the only North American event dedicated exclusively to stormwater and surface-water professionals, is seeking abstracts for presentation at StormCon 2017, which will take place in Seattle on August 27–31, 2017. The deadline for submitting abstracts is Wednesday, December 7, 2016.

We are accepting abstracts in six conference tracks: BMP Case Studies, Green Infrastructure, Stormwater Program Management, Water-Quality Monitoring, Industrial Stormwater Management, and Advanced Research Topics. For descriptions of the tracks and more information about submitting an abstract, please visit http://www.stormcon.com/pdf/SC2017_CallforPapers.pdf.