PORTLAND — In a nearly seven-hour meeting at Portland City Hall, members of the planning board gave developers the green light — in some cases begrudgingly — for the first phase of a four-tower, $150 million project in the city’s Bayside neighborhood.

The long-awaited vote on the project’s fate came more than a month later than expected, as planners put off the decision at their Dec. 10 meeting after nearly five hours of discussion that night.

Board member Jack Soley on Tuesday called the “Midtown” project a “sea of banality,” but said it was largely in compliance with zoning regulations and city planning guidelines.

“I’m not a fan of this project. The height feels too tall for this part of the city, the massing too great,” he said.

Fellow board member Bill Hall agreed, saying he worried that the Florida-based developers could leave the project unfinished after just the first phase — which consists of a single 165-foot-tall tower and a nearby parking garage — or sell it to another developer with a different vision.

“We’re rather constrained in our decision,” he said. “I think overall, it has some risk, it has some real risk, but unfortunately, we’re not going to be able to judge it based on those. From the beginning, I had some concerns about it and I still do.”

But other members said they believed the project would add vibrance to Bayside.

“It’s very hard to have diversity when everything is three to five stories,” said board member Carol Morrissette. “If you want to create a sense of place like what we’re trying to create in Portland, you need diversity.”

At the end of the night, the board voted to grant the project site plan, master development plan and subdivision approvals, complete with 13 pages of conditions and waivers. The board voted unanimously to approve the site plan and master development plan, and 5-2 to approve the subdivision, with chairman Stuart O’Brien and Hall opposed.

Sandra Guay — a Biddeford attorney representing the founders of Keep Portland Livable, a group formed in opposition to the project — said Tuesday the group remains undecided about whether they’ll file a legal challenge to the board’s decision.

The Midtown project has been at the center of a debate in Maine’s largest city for more than a year, the subject of numerous hours-long city meetings and workshops.

Developers from The Federated Cos. of Florida say the first phase will include 235 apartment units, 44,000 square feet for restaurants and shops on the first floor and more than 700 parking spaces in a 75-foot-tall garage nearby.

After two subsequent phases, which are proposed to be built over the next decade, the complex is slated to feature a total of four 165-foot-tall towers, 700,000 square feet of residential space, 100,000 square feet of retail and more than 1,100 garage parking spaces.

If permitted, the development would occupy the stretch of Somerset Street between Elm Street and what will be an extension of Pearl Street, bisected by Chestnut Street. The largely undeveloped city-owned area was formerly industrial scrapyards.

The developers already have City Council approval to exceed the 85-foot height limit to build the first of the four towers — the other three are proposed to stand in an abutting zone where 165-foot heights are conditionally allowed.

Like in past meetings, lines of supporters and opponents of the project traded barbs during the public comment portion of the meeting Tuesday night.

Foes criticized the development as too massive for Portland and in conflict with such guiding documents as the comprehensive plan and Bayside vision drafted in 2000.

“It is exactly the kind of development that will make Portland not livable,” said Jessica Moore of Edgeworth Avenue. “The lack of this kind of development is what makes the city … where people want to come and have their families and raise them here.”

Vaughan Street resident Penny Stevens said the project “belongs in Dallas, Atlanta, Phoenix, LA or Miami. Portland is a small city of 66,000.”

“It’s my opinion that it’s completely out of scale with the neighborhood and out of character with the city,” said Eastern Prom resident Benjamin Pollard.

But supporters of Midtown, such as Miss Portland Diner owner Tom Manning, said the development meets Bayside vision goals, by providing high-density residential, “walkable neighborhoods” and by cleaning up more than 3 acres that for years served as industrial scrapyards.

“It’s going to be really important toward controlling the city’s rates for market-rate housing,” said Christian MilNeil, who serves on the Portland Housing Authority board. “This being a free market, with supply and demand, the more we can add supply to the housing supply, the more we can reduce rents overall.”

MilNeil decried what he called “kneejerk reaction to any development” and said opposition to Midtown “mostly comes from relatively privileged people from the West End,” a comment which some project foes who spoke afterward took issue with.

In response to past criticisms, developers are offering to raise the nearby Bayside Trail — used by walkers, runners and bicyclists — to be level with the ground floor of the project.

Project architect David Hancock also addressed complaints that the towers would create too much wind in the neighborhood, among other arguments. Hancock said studies show winds around the project would range from 14 to 18 mph in the summer, and from 17 to 20 mph in the winter — with the 20 mph winds the only ones reaching a speed considered to be widely “uncomfortable” and those speeds appearing only in the corridor between the two buildings.