A proposed megaproject transforming a former munitions plant site in Arden Hills was approved unanimously Wednesday night by the city's planning commission.

No one opposing the plan for what was once the Twin Cities Army Ammunition Plant, known as TCAAP, got up to speak, and planning commission members were muted in their reactions, in contrast to a City Council that had some tense moments on the issue over several months' time.

Commissioner Brent Bartel did question the leap to 10 stories from closer to half of that in the city's original plans for some buildings, but mostly because so many people attending an open house in November commented on it.

"Why did this change?" he asked.

Developer Bob Lux said that new suburban condo projects have grown rare in recent years because of litigation against developers and contractors, but one way to ensure that problems don't develop with big multifamily buildings over time is to build them stoutly with concrete.

"Concrete construction costs more," he said, "so it doesn't become efficient for us to do unless there's a certain amount of height." And offering condos means a product that isn't being offered everywhere.

The public hearing and vote of the planning commission is the last major step for the project before the City Council takes a final vote on the master developer's plan for the 427-acre area. That vote should happen before the end of the year.

Based on its past comments, the council would be expected to approve the plans on a 4-to-1 vote — just enough for a project of this magnitude, which needs a supermajority to pass, but short of the unanimity sought by developer Alatus LLC and the city's mayor.

The plans for a new town center, with office space and stores surrounded by neighborhoods laced with parks and trails, have been the subject of intense negotiations.

Sticking points have included building heights, the hundreds of planned apartments, and an initial price tag for parks — later whittled back — that one council member dismissed as "way, way too high."

Planning Commissioner Chairwoman Roberta Thompson said she came to the meeting concerned about 10-story buildings, but was struck by what she heard in their defense, including the fact that some parts of taller buildings would be much less than 10 stories.

Other commissioners said they know that some people feel that the proposed town center isn't much like the rest of Arden Hills, but felt that was in some ways a strength, providing new options and a new setting, including for millennials wanting something more compact and walkable than previous waves of suburban development.

One big factor in the muted response Wednesday night seemed to be surveys returned from the open house in November, in which many respondents reacted favorably to the plans.

Voters in November chose for the City Council one sympathizer for the project and two skeptics, meaning that the posture of that body threatens to grow chillier in 2017.

The project is so massive that commissioners were reviewing 17 attachments, one of them 107 pages long.

The TCAAP site dates from the early 1940s, when the military threw up more than 300 buildings in what was then a rural township to make and test munitions for use in World War II.

David Peterson • 651-925-5039