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Critics Say Millennium Tower's Sinking Was Foretold by Earlier Project
http://www.nbcbayarea.com/news/loca...een-Avoided-New-Documents-Show-391468911.html
The now leaning and sinking Millennium Tower’s troubles may have been avoided had the city building officials heeded experts’ warnings that helped doom a similar project that was deemed at risk of sinking dramatically on Bay mud, an NBC Bay Area News investigation shows.
The 58-story Millennium was the heaviest and tallest concrete building on the West Coast when completed in 2009. But the tower at 301 Mission St. had sunk some ten inches soon after it was completed and is now leaning to the north and west.
It could ultimately sink nearly three feet, according to a study commissioned on behalf of condominium owners, who include the likes of 49ers legend Joe Montana. Owners have already started to file lawsuits stemming from the tower troubles.
At the corner of Mission and Fremont streets, signs that the tower is in trouble are everywhere. The sidewalk is cracked, the tower’s elegant stone facing is askew.
The problem is even evident at a distance, to a trained eye.
"You can even see it from the Bay Bridge, because the other buildings are plumb, and this one isn’t,’’ said Larry Karp, veteran soils engineer who said the Millennium Tower’s troubles are unique in his six decades of experience. "This is something new."
But an investigation by NBC Bay Area shows that the building troubles might have been avoided had the city’s building inspection officials heeded warnings on the similar project, slated to be built on land now occupied by the Transbay Terminal.
The warnings came in mid-2004, when Millennium was still on the drawing boards. That was when the Department of Building Inspection ordered construction halted on a 52-story project at nearby 80 Natoma St. in part because of a threat that it could sink into the watery clay and sand South of Market.
The then head of the building inspection department, Frank Y. Chiu, said in a legal declaration in October 2004 that he ordered a work stoppage in light of experts’ warnings that the 80 Natoma St. project could sink more geotechnical consultants estimated in the sandy, watery clay soils South of Market.
One of those experts, Massachusetts Institute of Technology geotechnical professor Charles Ladd, estimated that the 52-story planned Natoma Tower would likely sink at twice the extent predicted by the builder’s consultants of five inches.
Ladd expressed what he called "considerable concern’’ that such a building could sink "under the stresses imposed’’ on the old bay mud beneath it.
Ladd warned the building might sink some 11 inches and tilt due to uneven soil conditions.
In response, the city’s top building official took the extraordinary step of stopping the Natoma project in mid-2004.
The official, Chiu, explained his rationale in a deposition concerning the stop work order.
"Settlement of this magnitude" he said, "could cause cracking of the building, displace adjacent structures, and increase the risk of serious damage to the building in the event of an earthquake."
Source: Critics Say Millennium Tower's Sinking Was Foretold by Earlier Project
http://www.nbcbayarea.com/news/loca...een-Avoided-New-Documents-Show-391468911.html
The now leaning and sinking Millennium Tower’s troubles may have been avoided had the city building officials heeded experts’ warnings that helped doom a similar project that was deemed at risk of sinking dramatically on Bay mud, an NBC Bay Area News investigation shows.
The 58-story Millennium was the heaviest and tallest concrete building on the West Coast when completed in 2009. But the tower at 301 Mission St. had sunk some ten inches soon after it was completed and is now leaning to the north and west.
It could ultimately sink nearly three feet, according to a study commissioned on behalf of condominium owners, who include the likes of 49ers legend Joe Montana. Owners have already started to file lawsuits stemming from the tower troubles.
At the corner of Mission and Fremont streets, signs that the tower is in trouble are everywhere. The sidewalk is cracked, the tower’s elegant stone facing is askew.
The problem is even evident at a distance, to a trained eye.
"You can even see it from the Bay Bridge, because the other buildings are plumb, and this one isn’t,’’ said Larry Karp, veteran soils engineer who said the Millennium Tower’s troubles are unique in his six decades of experience. "This is something new."
But an investigation by NBC Bay Area shows that the building troubles might have been avoided had the city’s building inspection officials heeded warnings on the similar project, slated to be built on land now occupied by the Transbay Terminal.
The warnings came in mid-2004, when Millennium was still on the drawing boards. That was when the Department of Building Inspection ordered construction halted on a 52-story project at nearby 80 Natoma St. in part because of a threat that it could sink into the watery clay and sand South of Market.
The then head of the building inspection department, Frank Y. Chiu, said in a legal declaration in October 2004 that he ordered a work stoppage in light of experts’ warnings that the 80 Natoma St. project could sink more geotechnical consultants estimated in the sandy, watery clay soils South of Market.
One of those experts, Massachusetts Institute of Technology geotechnical professor Charles Ladd, estimated that the 52-story planned Natoma Tower would likely sink at twice the extent predicted by the builder’s consultants of five inches.
Ladd expressed what he called "considerable concern’’ that such a building could sink "under the stresses imposed’’ on the old bay mud beneath it.
Ladd warned the building might sink some 11 inches and tilt due to uneven soil conditions.
In response, the city’s top building official took the extraordinary step of stopping the Natoma project in mid-2004.
The official, Chiu, explained his rationale in a deposition concerning the stop work order.
"Settlement of this magnitude" he said, "could cause cracking of the building, displace adjacent structures, and increase the risk of serious damage to the building in the event of an earthquake."
Source: Critics Say Millennium Tower's Sinking Was Foretold by Earlier Project