The Suffolk County Planning Commission voted unanimously Wednesday to recommend approval of the first phase of a $4 billion Heartland Town Square mixed-use redevelopment on the former Pilgrim State hospital property in Brentwood.

Members of the planning commission, who held the second part of its of public hearing on Heartland at the Suffolk County Legislative Auditorium in Riverhead, listened to a handful of speakers and then deliberated about conditions to the recommendation that included monitoring of wastewater and traffic at the project.

With the planning commission recommending approval, the fate of the project, one of the most ambitious ever for Long Island, now rests with the Town of Islip’s town board, which would have to rezone the property and then give the required site plan approval and building permits.

Caroline Smith, director of Islip’s office of communications and media relations, said via email that “the next step is for the town board to schedule a public hearing.”

Islip’s planning board voted in August to recommend that the first phase of the mega-project be approved. The project’s first phase is proposed to bring more than 3,000 apartments, 400,000 square feet of retail and 300,000 square feet of office space to about one-third of the 460-acre redevelopment site and could take up to 10 years to complete.

First pitched 15 years ago, after developer Gerald Wolkoff purchased the former Pilgrim State psychiatric hospital property from the state for $20.1 million, the Heartland redevelopment would eventually create 9,100 apartments, 1 million square feet of retail space and more than 3 million square feet of offices at the Brentwood site.

The developer says Heartland’s planned mix of rental apartments, shops, restaurants and offices will eventually generate about 23,000 permanent jobs and at least 1,500 construction jobs annually throughout its total build-out, which could stretch into three decades.

Most of the opponents who spoke at the contentious planning commission hearing in January were from other Suffolk communities, while many of those from Brentwood offered support for the Heartland project.

Many of the people who attended that hearing were members of Long Island’s building trades unions, whose leaders have asked for a project labor agreement and a law that would mandate that local construction workers get preference in the massive redevelopment.

Nassau-Suffolk Building Trades Council President Richard O’Kane has said that Wolkoff has been inflexible in previous meetings with the unions, which is why a PLA is important to secure. Wolkoff has previously asserted that Heartland will be constructed with mostly union workers, but the developer has also said he didn’t want to be handcuffed in hiring decisions.