After years warning that far too little affordable housing is being created in the Twin Cities metro area, the Metropolitan Council is looking the other way while a 427-acre megaproject with heavy public backing threatens to become just another suburban real estate deal, according to a collection of social-justice groups.

Housing advocates said they were caught off guard by the Met Council's behind-the-scenes approval of plans they say provide no guarantee that the redevelopment of the Twin Cities Army Ammunition Plant (TCAAP) site in Arden Hills will provide homes for truly needy families.

On the contrary, they said they worry a flashy new development on the site will doom an affordable trailer park right next door that could suddenly become a developer's target.

Leaders of four advocacy groups wrote to Met Council members this week that the plans to provide affordable housing at TCAAP "have fallen woefully short."

Some of them turned up at the Met Council meeting on Wednesday to make the same plea. The result was a somber conversation among Met Council members.

"I don't think we've seen any kind of specificity around affordable units," Council Member Gail Dorfman said.

Adam Duininck, chairman of the Met Council, said he expects a council committee will take up the issue. "I look forward to hearing from [them on] where this goes next," he said.

Ramsey County Commissioner Janice Rettman expressed the same concern in December when TCAAP plans came before her board. If plans include "color palettes" for building materials, she said, "they can have a commitment to people in areas of concentrated poverty to have the option to live there. It would justify so much more the public dollars put into this project."

Rettman was told negotiations were still going on. But several Met Council members agreed Wednesday that they need to have a conversation about the issues raised by advocacy groups.

Monday's letter urging a careful review of "this once in a lifetime opportunity" was signed by leaders of the Housing Justice Center, the Alliance for Metropolitan Stability, the Sierra Club and All Parks Alliance for Change, a group that deals with mobile home park issues.

Sue Watlov Phillips, executive director of the Metropolitan Interfaith Council on Affordable Housing, added her voice on Wednesday, saying it's not just about Arden Hills.

"We're very concerned that as comprehensive plan amendments come forward, they are moving from higher to lower density and often seeing all the affordable housing in one part of a city, which we consider a concern in terms of the Fair Housing Act," she said.