Next summer, SugarHouse Casino wants to break ground on an expansion to almost double its gambling space and add a restaurant, meeting rooms, and a seven-story parking structure, an architect for the project told the Philadelphia City Planning Commission on Tuesday.

The casino also plans to link its site to Penn Treaty Park by extending a waterfront trail, said Ian Cope, a managing partner with Cope Linder Architects.

In a presentation Tuesday to commissioners, Cope said the revised plan calls for a lower and longer parking garage than was envisioned in 2009.

He said the new structure would have one floor of gaming space and six decks of parking. The earlier design would have had 10 decks of parking above a casino level.

The proposed garage would handle 1,500 cars instead of 3,200, which Cope said was "far more than we need."

The expansion "will have a much lower impact on the skyline," Cope said.

But to proceed with this plan, he said, SugarHouse needs to work with the Water Department to gain federal and state approvals to move a sewer outflow line that discharges into a channel on the northern edge of the property.

If it cannot relocate the outflow pipe and build over the channel, SugarHouse will have to revert to a higher parking structure, Cope said.

By increasing its gambling floor from 51,000 square feet to 90,000 square feet, SugarHouse plans to add a poker room, between 600 and 800 slot machines, and 35 to 40 table games. Cope said the project would take about 15 months to build.

SugarHouse, on a 22-acre parcel on the Delaware River waterfront in Fishtown and Northern Liberties, is the city's only casino.

Its opening last September ramped up competition among area casinos. In a report on the industry released Tuesday, the Pennsylvania Treasury Department warned that casinos are starting to cannibalize each other. The Treasury reported that SugarHouse had $98.6 million in slots revenue through July, but more than 40 percent of which came at the expense of nearby PARX in Bensalem and Harrah's Chester.In addition to city, state, and federal approvals for its plan, SugarHouse also needs the Pennsylvania Gaming Control Board to sign off on its expansion.

In 2009, the owners of SugarHouse got the gaming board's approval to open a smaller casino by promising to build a bigger facility when market conditions allowed.

The "interim" casino has 1,602 slot machines and 53 table games.

The timing and scope of the expansion could be complicated by a legal battle in Delaware among investors in the project.

Last June, a group of local partners, led by lawyer Richard A. Sprague and auto magnate Robert Potamkin, demanded that investors from Chicago give them more say in the business.

The Chicago investors include SugarHouse chief executive officer Greg Carlin and billionaire gaming veteran Neil G. Bluhm.

Sprague could not be reached for comment. In a statement, Carlin said there had been no change in the status of the lawsuit. "And to date there's been no impact on the planned expansion," he said.

"This expansion," he added, "brings the total investment in Philadelphia's first and only casino to more than $500 million."

Contact staff writer Jennifer Lin at 215-854-5659, jlin@phillynews.com or @j_linq on Twitter.