Ramsey County has closed on a $28.5 million deal to buy and finish cleaning the 430-acre Twin Cities Army Ammunition Plant (TCAAP) site in Arden Hills.

Future use of the site, once proposed to be the home of a new Minnesota Vikings stadium, has yet to be determined.

But Heather Worthington, the county's deputy manager, said Tuesday that Carl Bolander & Sons of St. Paul is set to begin cleanup work this week.

A groundbreaking ceremony is expected next month, she said.

In November, the County Board approved the plan to purchase the TCAAP site, the state's largest Superfund site, from the federal government. The bulk of the cost — $22.6 million of the $28.5 million — will go to cleaning the last 30 acres of solvent-heavy soil.

Worthington said that Arden Hills is working on a master plan for the property in partnership with the county.

In 2011, the Vikings sought to build a new stadium on the TCAAP site before that project was steered to downtown Minneapolis.

Although the proposal fell through, county officials said last year that the attention created by the Vikings had led them to conclude that the site was too valuable to lose.

Congressional approval of the sale was required, and the deal was completed Monday afternoon, Worthington said.

"It wasn't like closing on a house — I can tell you that," she added.

Anthony Lonetree