It could be another few weeks before the Ontario Municipal Board (OMB) rules on the largest urban boundary expansion in Hamilton's history.

The OMB adjudicator is currently deliberating the two sides in the Airport Employment Growth District (AEGD) debate, otherwise known as the Aerotropolis. The hearing ended in late January, and while 80 per cent of OMB decisions are reached within two months, more complex ones can take a while, said communications consultant Karen Kotzen.

"There is no way of telling how long it will take."

The hearing is the latest step in a 10-year process to open up about 720 hectares around the John C. Munro Hamilton International Airport to long-term development.

Opponents to the plan say the expansion is unnecessary, and could have a negative impact on the environment and use up arable land.

The city says it will attract jobs, economic development and as much as $70 million per year in taxes by 2031.

Environment Hamilton — which led the OMB challenge with Hamiltonians for Progressive Development — is watching and waiting, said Don McLean, an Environment Hamilton director.

"When the hearing finished, the officer said it would take some time," he said. "There's a lot [of information] to go through and we're not making any predictions on when they will make the decision."

The seven-day hearing began Jan. 14. Once a decision is made, either side can request a review of the decision. They could also appeal to divisional court if they believe there is an error in the law.

Another local high-profile OMB decision is scheduled for a hearing on March 25. The city will argue against a proposal by Lynwood Charlton Centre. The centre wants to place an eight-bed home for teen girls with mental health issues at 121 Augusta St., home of its day treatment program and the site of a former mill.