The site of the former Bayside Expo Center in Dorchester looks like something out of a post-apocalyptic film, a sea of asphalt and overgrown weeds winding their way through a chain-link fence. Surrounding the site, office buildings and a hotel, the well-trod Harborwalk and low-rise brick apartments overlook the water and downtown skyline to the north.

Plans have long been in the works to transform this 36-acre swath on Columbia Point into a climate-resilient mini-city alongside the campus of UMass-Boston. And on Thursday, developer Accordia Partners took a big step toward that goal.

The Boston Planning and Development Agency board Thursday night approved a master plan for Dorchester Bay City, a $5 billion, 21-building mixed-use project along Mount Vernon Street and Morrissey Boulevard. Development plans call for 6.1 million square feet of office, research and development space, housing and potentially academic uses and 15.4 acres of open space. Some 20 percent of the planned 1,957 apartments will be designated affordable.

“The final master plan for Dorchester Bay City is a clear reflection of the extensive feedback we received from multiple community organizations, residents, and business owners,” the developers said in a statement. “We look forward to moving this project forward and assuring that our vision of economic opportunity and inclusivity for diverse audiences comes to life.”

The project will likely take 10 to 15 years to fully build, and approvals are still needed for individual building designs and development plans.

Accordia, a partnership between veteran Boston developers Kirk Sykes and Dick Galvin, and New York-based Ares Capital Corp. in early 2019 won approval from the University of Massachusetts board of trustees and building authority to develop what was then a 20-acre site. It has since expanded to include a 12-acre Santander Bank site next door along Morrissey Boulevard and a portion of the Boston Teachers Union headquarters.

The site sits on Dorchester Bay, amid five major floodplains, and resiliency measures were critical to protect both the project and the Dorchester and South Boston neighborhoods, the development team said. They include raising the whole site by about three feet, with a gentle slope toward higher points away from the water. A raised ridge along the water will tie in with flood-protection efforts by the adjoining state and city-owned land along the Harborwalk, Carson Beach and Moakley Park along with other waterfront improvements at the UMass Boston campus.

“There aren’t many legacy projects that tackle such difficult challenges as resiliency and infrastructure and inclusion,” Sykes said in a recent interview. “So to be able to do that here feels pretty good.”

Those resiliency measures include raising the Harborwalk in front of the Harbor Point apartments and installing a new stormwater management system. Accordia has committed to pursuing its mitigation efforts in the project’s first phase, a decision that has drawn praise from climate advocates.

“They’re doing what we’ve been asking other developers to do, which is to take a more regional approach and look not just at their parcel of land,” said Kathy Abbott, president and CEO of waterfront advocacy nonprofit Boston Harbor Now in an interview this week.

There has been some community pushback, particularly around the impact the huge, mostly-commercial project could have on housing costs in nearby parts of Dorchester. Ahead of Thursday’s hearing, housing advocates called on Boston Mayor Michelle Wu and BPDA Director Arthur Jemison to hold off on a vote until the developers completed what’s known as an Affirmatively Furthering Fair Housing (AFFH) assessment for the whole project, calling for deeper levels of affordability.

“The zoning code’s new AFFH requirements are a major tool for the City and community to work together to combat injustices toward BIPOC residents and families,” wrote Carolyn Chou, co-executive director of the Asian American Resource Workshop, in an email to Wu and Jemison. “I join many Dorchester residents and community members to call on you to enforce these requirements, and ensure that Dorchester Bay City includes more BIPOC residents and families rather than further the discrimination against them and fuel displacement.”

At Thursday’s hearing, multiple community members and housing advocates urged the BPDA board to delay until a broader housing assessment could be undertaken.

Vicki DiLorenzo, executive director of housing advocacy organization Right To The City Boston, urged deeper levels of affordability within the project, and said she was deeply concerned about a vote before a full AFFH designation.

”It makes the public question whether the city is really concerned about its own goals” of achieving equity and affordable housing, DiLorenzo said.

Sykes and BPDA staffer Caitlin Coppinger said that Dorchester Bay City’s master plan approval did not require an AFFH process for the overall project, but that the city would complete one during individual building reviews.

“We remain accountable ‘til the very last building — including the housing,” Sykes said in an interview earlier this week.

Accordia has committed $10 million toward a first-time homebuyer program from the Massachusetts Affordable Housing Alliance. Other commitments include a promised $62 million in transportation improvements within the site itself, such as reconstructing a portion of Mt. Vernon Street and building 3.7 miles of bike lanes. The team also plans $41.6 million in off-site improvements, including $5 million to help the MBTA redesign the JFK/UMass Red Line station and other funding aimed at improving nearby Kosciuszko Circle.

Those who spoke in support included City Councilor Michael Flaherty, who said he spoke on behalf of US Rep. Stephen Lynch and other local elected officials, as well as officials from the Black Economic Council of Massachusetts, youth nonprofit Artists for Humanity and Boston College High School. UMass Boston Chancellor Marcelo Suárez-Orozco applauded Dorchester Bay City’s investments in workforce training, transportation improvements, and climate resilience.

“As I think about the labs, and the research and development opportunities, I dream, I dream, of the internships, the mentorships … that my students, our students at UMass Boston would have the opportunity to access — opportunities that students across the river, at the other universities, take for granted,” Suárez-Orozco said.

With BPDA approval now in hand, Accordia will file its final environmental impact reports and pursue its Chapter 91 designation from state environmental officials.

Also on Thursday, the BPDA board granted tentative designation to the Asian Community Development Corp. and The Community Builders as joint venture redevelopers of 290 Tremont St., a BPDA-owned surface parking lot in Chinatown. Millennium Partners in late 2018 got approval to build a 30-story affordable housing tower on the site, but scrapped those plans after financing troubles at their luxury office and residential tower at Winthrop Center downtown. The Asian CDC and The Community Builders now plan to build an 11-story, 119-unit affordable apartment and condominium building. A majority of the property will be two- and three-bedroom units.

The board also approved City Realty’s request to switch its already approved six-building residential project along Cambridge Street and Harvard Ave. in Allston from 344 condominiums and multifamily apartments to all apartments, and increase affordability at the project. The swap to all apartments was necessary due to a deteriorated financing market for condo projects, said attorney Donald Wiest. The developers sought out more than 100 lenders and “couldn’t get anyone to bite,” he said. “We didn’t want this to remain fallow for several more years.”

The board also approved:

· A 13-unit apartment building at 86 St. Botolph St. in Back Bay

· A 41-unit apartment building at 970 Saratoga St. in East Boston

· A 41-unit apartment building at 1471 Blue Hill Ave. in Mattapan

· BioMed Realty’s proposed office-to-lab conversion project at 1000 Washington St. in the South End

· Issuing a request for proposals for five parking lots and an adjacent vacant parcel across Harrison Street from the Boston Water and Sewer Commission Department headquarters in Roxbury.