A dozen concerned citizens showed up to voice their opposition to a massive new nightclub in Toronto's Port Lands area.

The Ontario Licence Appeal Tribunal hearing looking at Powerhouse Corp.'s application for a nightclub that could hold more than 15,000 people — which would make it among the world's largest — began on Monday.

A decision is likely months away, but those who are worried about noise and other issues were keen to share their opinions. The city, liquor board and several developers hoping to build in the area are also set to deliver opening statements.

Ulla Colgrass, a member of the York Quay Neighbourhood Association and Waterfront for All, called the proposed club "completely out of scale," and warned it would "ruin the waterfront" if approved.

The owners of Rebel have a applied for a liquor license that would increase the club's capacity to 15,000 patrons. (CBC News)

Colgrass said it's not the first time development has threatened the waterfront's future, pointing to other nixed ideas like flying jets at Billy Bishop airport, or building a ferris wheel or casino on the water.

"We've fought them all and we've won every one of them," she told CBC Toronto.

"And I think we will definitely also win this case."

Powerhouse, which currently owns Rebel and an adjacent bar, Cabana, in the Port Lands, has applied for a new liquor licence for the same site, but with a much larger scope. The company will lay out its case before the tribunal today, as well.

Currently, the club's limited to 3,163 patrons indoors and 2,510 outside.

The new application calls for an indoor capacity of 7,584 people, with another 7,971 patrons allowed on patios.

A lawyer for the company previously told CBC Toronto that Powerhouse has no plans to use the extra capacity, even if it were granted.

The site was once home to the controversial Docks nightclub, which had its liquor licence revoked in 2006 after a battle with neighbourhood groups over the noise that emanated from both inside and outside the venue.

The tribunal is set to meet again Tuesday, and has also scheduled meetings for the end of March and mid-June.