The engineering design review team looking into revised plans to stabilize the Millennium Tower in San Francisco on behalf of the city’s Dept. of Building Inspection has OK’d an 18-pile upgrade plan in place of the earlier 52-pile design.

The retrofit proposal would avoid further settlement and tilt of the 645-ft-tall building until 2060—the project’s goal—members of the review team wrote in a letter detailing their findings June 15. Additionally, they estimated the design would recover 0.3 in. of settlement, 4.3 in. of westward tilt and 0.3 in. of northward tilt that has accumulated over time. The structural analyses looked at the building’s response under gravity loads and earthquakes.