Engineers working on the retrofit to stabilize the building developed a plan with 18 piles instead of 52, as had been considered earlier.

There was no measurable settlement during the Dec. 1-3 drilling for the second permanent pilot pile installed at the northwest corner of the troubled Millennium Tower in San Francisco, says Ronald O. Hamburger, engineer-of-record for the perimeter pile upgrade designed to stem settlement of the 645-ft-tall residential condominium.

First test pile operation did not increase building settlement at troubled foundation fix of San Francisco's Millennium Tower.

By installing a pilot pile for the settling Millennium Tower's troubled foundation repair, Shimmick Construction hopes to prove the efficacy of revised construction methods so that work can continue without triggering accelerated building settlement.

The team working on the troubled foundation fix of the settling Millennium Tower has switched gears again due to equipment troubles.

Work on the nearly $100-million perimeter pile upgrade on the 645-ft-tall residential tower to prevent significant future settlement follows the resolution of litigation.

With the lengthy and complex permitting and approval process complete and almost all the other details worked out, construction could begin in mid-November on the estimated $100-million fix for San Francisco's 645-ft-tall Millennium Tower, which has settled more than 17 in. since its completion in 2009.