The sinking and leaning tower of our downtown skyline, the eight-year-old Millennium Tower, continues to sink and tilt, and new data released by an engineering firm that has been monitoring the tower's movement shows it tilting twice as fast this year to the north as it had been earlier. As NBC Bay Area reports, the ARUP engineering firm has been monitoring measurements from the building's roof, and finds the building tilting another two and a half inches in the last six months alone. Also, since the sinking problem was first revealed to the public last summer, the tower has sunk another inch into the mud, for a total of 17 inches since its 2009 completion.

City Assessor Carmen Chu announced Monday that 99 homeowners in the building would be getting property tax breaks of $3,000 for 2017, but that leaves the other 75 percent of homeowners with no breaks, because she argues that their units have appreciated considerably since they purchased them during the Great Recession. These homeowners packed a meeting of the city's assessment appeals board on Tuesday, all arguing that their units are worthless, but Chu maintains that many of them still have assessments based on their purchase prices that are far below their current market rate.

Engineers have said that the building remains safe and habitable despite the dramatic images of a tower sinking into the ground. Nonetheless, a fix will be necessary, drilling piles down to bedrock to shore up the foundation and stop the sinking — something most other buildings in the vicinity are now doing. The tilting, though, can cause cracks in walls, and can cause havoc with the building's elevators.

As the Chronicle's Matier & Ross report, that fix, involving 50 to 100 new piles drilled through the building's basement, may end up being far less expensive than originally feared. ARUP and another firm, LERA, who were hired by developer Millennium Partners and the Transbay Joint Powers Authority (TJPA), believe their retrofit solution will work to stabilize the building, and will cost $100 million to $150 million, not the billions that were feared.

Also, engineers believe that residents will be able to remain in the building while the fix takes place.

Millennium Partners has maintained from the beginning that the TJPA bears much of the responsibility for the building's "excess settlement" because of dewatering they performed on soils next door during the construction of the Transbay Salesforce Transit Center. A court will likely ultimately decide who was more at fault, but City Attorney Dennis Herrera already filed suit against the developer last fall claiming they knew their building was sinking more than normal in 2008, before construction on the transit center had even begun.

All previous coverage of the Millennium Tower debacle on SFist.