Toronto’s $220-million deal to buy the GreenLane Environmental landfill near St. Thomas has been finalized after the details were gone over in a recent meeting that lasted through the night.

Mayor David Miller says the purchase will provide secure disposal for the city’s garbage in the event the U.S.-Canada border ever closes. Toronto had been searching for a secure destination for its garbage once its contract with Republic Waste expires in 2010. (The waste is currently trucked to Republic’s Carleton Farms landfill in Michigan.)

The announcement that the deal is finalized was criticized by one city council member who says that too little information has been provided to judge the merits of the deal.

“There has been a deliberate initiative on behalf of staff and the mayor’s office to keep the details secret and to suppress the facts,” Denzil Minnan-Wong said. Without more details, he added, “no one can have a meaningful debate.”

The mayor insists that the landfill purchase is a fair deal, even though it will be financed by borrowing. The city currently pays about $60 a tonne to ship roughly 750,000 tonnes of garbage to Michigan. If the city had to extend the contract 15 years (the expected life of the GreenLane site) beyond 2010, that would cost the city $675-million.

The GreenLane facility is profitable. The city is contractually bound to send most of its waste to Republic’s Michigan landfill until 2010, so it will collect the tip fees between now and then. It has some security for the future, and the current contract does allow a small amount of waste to be sent to disposal sites other than the Michigan landfill. Toronto will also continue its aggressive waste diversion effort, in part to extend the life of the landfill that it now owns.

“It is such a valuable asset, you don’t want to fill it up,” Mayor Miller said. “The more you divert, the more you keep capacity for the future.”

The “purchase and sale” agreement between Toronto and GreenLane was signed in time to meet the previously agreed deadline of midnight Tuesday. A $10-million down payment will be held in trust until the deal closes by March 29.