The Portland City Council on Monday voted to sell four parcels of land on the peninsula – a move that city officials believe will be transformational for a former industrial area that has struggled in recent years to become a modern, mixed-use neighborhood.

The sales agreement for the Bayside properties bounded by Portland, Parris, Hanover, Alder and Kennebec streets requires the buyers to execute the proposals for roughly 100 units of houses as well as associated retail, commercial, office and open spaces within certain time frames. If those conditions are not met, then the city can either repurchase the property or receive payments from the buyers.

City Councilor David Brenerman, who leads the Economic Development Committee, which spearheaded the process, said the sales of the properties, along with two others in the near future, will move Bayside closer to a vision outlined nearly 20 years ago.

“Tonight’s action by the council will be a milestone for Bayside,” Brenerman said. “We will be creating a new multi-use neighborhood in this part of Bayside with the potential to build more than 100 units of housing here in Bayside and in the Parkside neighborhood.”

The Bayside neighborhood is presently defined by a cluster of social services providers, including homeless shelters. Over the years neighborhood leaders have hoped to build a base of year-round residents. But it has frequently seen its hopes for redevelopment evaporate.

The most recent example is the so-called midtown project, which has been approved to build 180 housing units, 50,000 square feet of retail and an 850-vehicle parking garage. The developer, Federated Cos., of Florida, has yet to pull any permits for the project, despite closing on the property for $2.3 million in June 2016.

The project has had site approvals for over two years, but those will expire in March.

“We know that we’ve had problems that shall not be named that sit vacant for many years after closing,” said City Councilor Belinda Ray.

The city will receive nearly $4 million for the Bayside sites, which have been used for the city’s Public Works Department. The sale proceeds have been earmarked to help pay the ongoing costs of relocating public works out to Canco Road.

Developer Jack Soley will pay $175,000 for a 0.23-acre lot at 56 Parris St. He plans to build a four-story condo building aimed at middle-income earners called the Periscope Lofts. It would have at least 20 one-bedroom condos that would be sold for less than $200,000.

A 1.25-acre parcel at 82 Hanover St. went to Tom Watson & Co. LLC. Watson, who owns Port Property Management, plans to relocate his office from Parkside to Bayside, which would free up 104 Grant St. for redevelopment from a single-story building to a four-story building with 23 apartments.

In Bayside, Watson proposed adding retail space in the old General Store building, as well as rooftop decks and open spaces for public use.

Developer Nathan Szanton and Bayside landowner Ross Furman are being recommended to buy and develop a 0.22-acre parcel at 178 Kennebec St. for $250,000. That small parcel is surrounded by property Furman already owns.

They are planning to build 50 units of housing – a mix of studio, one-, two- and three-bedroom units – over ground level retail and/or artists’ space at 178 Kennebec St.

Thirty-five percent of the units would be market-rate, while 65 percent would be affordable to people making 60 percent of the area median income or less.

Barrett Made, a design and building firm, will purchase 65 Hanover St. for $1.1 million. The firm will move from Union Wharf to an existing brick building, while adding space for business incubators, including a 20-bench workshop called a makers’ space that would be available to members 24 hours a day.

The proposal includes solar panels on the roof and envisions a second phase that could add 25 units of housing on an adjacent lot.

Cedar Street resident Sarah Michniewicz said she was excited about future uses.

“I think it is going to herald a very beneficial change for Bayside in that area and hopefully across the whole neighborhood,” she said. “This (Barrett Made) project in particular feels like a very good fit for the neighborhood in general.”