San Francisco has agreed to settle with several groups that sued to block the city’s rezoning of Central South of Market, clearing the way for $6 billion in new office and housing projects to move forward, one of the groups said Sunday.

One neighborhood nonprofit, one developer and condo owners had alleged that the city didn’t properly study the effects of the plan, which allows taller buildings on 230 acres next to downtown. Some of the opponents criticized the height of proposed buildings and feared the changes would spark more expensive housing costs and push out existing residents.

As part of the settlement, the city will conduct additional studies on the neighborhood’s needs for public facilities like fire stations and homeless housing, along with seismic risks in older buildings, said John Elberling, executive director of Todco Group, one of the opponents that is settling.

In an additional neighborhood concession, four developers — Tishman Speyer, Kilroy Realty, Boston Properties and Strada Investment Group — have each agreed to offer retail space at rents 40% below market rate for 30 years in their projects. The value of the rent reduction is an estimated $21 million over 30 years.

The district’s new projects are expected to accommodate 30,000 new jobs and 20,000 new residents by 2040.

Details of the other settlements were not immediately available. The other opponents include developer One Vassar LLC and local condo owners who opposed taller building heights. They couldn’t immediately be reached for comment.

The City Planning Department didn’t immediately respond to requests for comment.

The settlement is good news for growing companies seeking office space, said Robert Sammons, research director of real estate brokerage Cushman & Wakefield. With the city’s downtown vacancy rate under 5%, there are almost no large buildings to expand into for fast-growing tech companies. But projects probably won’t be finished until 2023 or later, Sammons said.

Editor’s note: An earlier version of this story gave incorrect information about the opponents who sought to block the project. Only one neighbhorhood nonprofit was among the groups that sued.

Roland Li is a Chronicle staff writer. Email: roland.li@sfchronicle.com Twitter: @rolandlisf