Homeowners at San Francisco's Millennium Tower have reached a tentative agreement with the building's developer and the Transbay Joint Powers Authority, settling more than 200 lawsuits over the sinking skyscraper.

The terms of the agreement aren't public yet, but homeowners at the 58-story luxury high-rise at Mission and Fremont streets — across the street from the Salesforce Tower — will be getting "significant payout," according to attorney Niall McCarthy, who represents residents of the building.

The preliminary deal, McCarthy said, was announced in San Francisco Superior Court Wednesday morning, marking the beginning of the end in the legal battle over the luxury tower, which has sunk more than 17 inches since it was completed in 2009. The tower is also tilting several inches to the northwest.

"It's a positive step forward," said Doug Elmets, a spokesman for the Millennium Tower Homeowners Association. "It’s the culmination of hard work by so many different parties."

The building's developer, Mission Street Development, is also pleased, according to a statement from spokesman P.J. Johnston.

"Mission Street Development has made clear from the beginning that its top priority has been to address and resolve the conditions that caused the building’s past problems," Johnston said. "The agreement announced today is consistent with that priority and assures that the building will continue to set the standard for urban living in San Francisco."

The deal is expected to be finalized in 90 days, according to McCarthy.

"The many parties to the Millennium Tower litigation are working on a settlement with the assistance of a mediation team," said the Transbay Joint Powers Authority's executive director, Mark Zabaneh, in a statement. "A settlement agreement has not been finalized."

A Plan to Fix the Tower

The tentative deal comes just after an independent group of experts endorsed a $100 million plan to fix the tower on Tuesday.

A four-person panel submitted a review to city officials, saying they "have no reason to withhold approval" of the project, which calls for more than 50 perimeter piles to be drilled into the ground beneath the sidewalk in order to provide greater support for the building.

Funding for that fix is included in the tentative agreement, according to attorney McCarthy and the homeowner association's Elmets.

Under the plan, developed by the engineering firm Simpson Gumpertz & Heger, approximately 52 2-foot-thick perimeter piles — or vertical structural supports — would be drilled 250 feet down to bedrock in order to shore up the building with a new, additional foundation that would be tied to the tower's existing foundation.

When it was originally constructed, Mission Street Development chose not to anchor the Millennium Tower to bedrock.

That much-criticized decision has been blamed since 2016 for the building's sinking and tilting. Mission Street Development in turn blamed the Transbay Joint Powers Authority, the agency responsible for the construction of the nearby Transbay Transit Center, saying excavation work on the center triggered the sinking.

According the new report, the proposed improvements aren't currently required by the San Francisco Existing Building Code, technically making them a "voluntary seismic retrofit." But, the panel says, if the retrofit isn't complete, the tower might continue tilting, which "may increase forces and deformations in the foundation," potentially triggering mandatory repairs in the future.

The proposal still faces a number of hurdles. The city's Planning Department has to finish a preliminary environmental review of the project, which is expected to be published in November.

After the environmental impact report, the proposal will have to go through permit approval related to construction outside of the tower's property line, under the sidewalks, according to the review panel's head, Stanford engineering professor Gregory Deierlein.

If all goes well, Deierlein said, construction could begin as early as the beginning of 2020. Construction itself is expected to last a little less than two years.