![]() Instead, the geotechnical engineers chose to support the tower on a series of 950 precast concrete friction piles driven between 60 and 90 feet into the soft clays below. But due to the geology of the Millennium Tower’s site, end-bearing piles would have reached down over 200 feet before hitting competent rock. Many tall buildings in this area rest on foundation systems that extend all the way down to bedrock, on what are called end-bearing piles. Millennium Tower was built in South of Market, a neighborhood that mostly used to belong to San Francisco Bay. But the strata below our city streets can consist of anything from sand to clay to solid rock, and many cities, including San Francisco, have infilled former marshes and bays with soil in order to expand their coastlines and generate valuable real estate. While a one or two story wood-framed building can be built safely with a shallow foundation on crummy soil, a major skyscraper requires a foundation that can transfer extremely high loads into the earth. In foundation design, not all terra is firma. Millenium Tower located in San Francisco’s SOMA, near the Financial District. Millennium Tower happens to be a large enough project with a severe enough problem that the whole world can’t help but gawk. In most scenarios, these deflections are so minuscule that the occupants never even notice. Buildings sway in the wind, expand and contract in response to temperature changes, and shift with the land upon which they rest. ![]() Our office towers, apartment complexes, and single family homes move in response to loads applied by the environment. Since the foundation issues came to light in August 2016, the vertiginous ultra-luxury highrise has become the subject of outrage, ridicule, and at least two pieces of pending litigation. Since its completion in 2009, the 58-story, 645-foot tall residential building has settled 16 inches and tilted perhaps 2 inches to the northwest. Sellen said, “If the inspector finds a condition that he considers to be serious or a danger they actually have pretty broad authority to red tag or to lock an elevator out of service until what they deem to be a dangerous condition is correct it.San Francisco’s Millennium Tower is sinking. The inspector will have the final say if the repair work meets the code standards. “That's a highly unusual condition,” Sellen said, adding that the gap “needs to be maintained to be compliant with code and to prevent a tripping hazard.”Ī recent photo of the gap for one elevator shows it currently measures at, or just slightly over, the 1.25-inch clearance standard. John Sellen, a veteran elevator consultant and an advisor on the installation of the elevator system at the tower, says inspectors still must go to the site and verify that the gap is within the specified limit. In a separate statement, Hamburger said the ongoing retrofit – which involves shoring up the building on the west and north sides – would help “close the gap between the elevator thresholds in the adjacent podium building that connects the main tower and mid-rise together.” “Upon completion, this work was submitted to the State Elevator Inspector, approved, and both elevators are operating as they should without issue.” “Mitsubishi Elevators has remedied this gap by extending the thresholds to ensure code compliance,” said building manager James Zaratin, in a statement. NBC Bay Area's Raj Mathai spoke to Investigative Reporter Jaxon Van Derbeken, who has been in the forefront of the story from the beginning, about the latest Millennium Tower discovery. This month, Millennium officials submitted a compliance form to state elevator officials, indicating the problem had been “repaired.” Documents suggest the gap may have been as much as 2 inches. ![]() In September 2019, elevator officials issued an order prohibiting use of that elevator. An inspection of one of the two parking garage elevators found the elevator sill gap exceeded the 1.25-inch threshold specified by code. That would be good news for the problematic elevator system that links the garage to the tower, where the widening gap had prompted state elevator inspectors to issue a preliminary compliance order in May 2019. Once the work is completed, he said settlement will stop at the northeast corner and the fix should offset some of the tilt. Hamburger says he doesn’t think the gap will get worse during the ongoing work to stop the building from sinking. Millennium Tower Now Tilting 3 Inches Per Year, According to Fix EngineerĮngineers “fully considered” the safety implications and “determined that the building is not at risk due to this movement, or any movement likely to occur before construction completion,” he said. ![]()
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