In a first test of Sonoma's new rules governing so-called formula stores, the city planning commission has narrowly rejected a use permit for Berkeley-based Peet's Coffee and Tea to open an outlet near the historic city plaza.

The city in June became one of the few in the nation to enact regulations on chain establishments, including a ban on large-scale restaurant chains with more than 250 outlets from opening on the plaza.

Peet's is proposing to open a store at 591 Broadway in what is now a vacant office building. The site is outside the area where the city's ban on formula restaurants applies. With 198 outlets, Peet's is below that threshold anyway.

Nevertheless, the Sonoma Planning Commission on Thursday voted 4-3 to deny the use permit. Peet's has until Sept. 28 to appeal the decision to the City Council.

A Peet's spokeswoman declined Friday to discuss the company's plans. "It is Peet's policy not to discuss matters relating to new store openings until a lease has been signed," said Elizabeth Sgarrella.

David Goodison, the city planning director, said a majority of commissioners said that Peet's could not meet one particular test of the city's new formula store ordinance, which is that the establishment promote diversity and variety and cater to both residents and visitors.

But Sonoma Mayor Joanne Sanders, who has steadfastly opposed the ordinance, on Friday said Peet's would be a good fit for the city.

"I think there are plenty of people in Sonoma who would go there, and do go there when they are in other places," she said.

Apart from a Peet's representative and the property owner, the only person to speak at Thursday's public hearing was David Mock, who owns a drive-through coffee business on Broadway.

He expressed concern that Peet's would adversely affect his business and diminish the uniqueness of Sonoma's downtown, according to Goodison.

Sonoma's consideration of an ordinance governing formula stores was sparked after Staples opened last year on West Napa Street in a 14,400-square-foot building that had been a Ford dealership.

An ad-hoc committee led by Councilman Steve Barbose spent weeks crafting proposed changes to the zoning ordinance. Other than through design review, the city did not regulate chain stores.

Under the ordinance, all formula businesses seeking to open at the plaza or in the city's historical district must get use permits. A formula business is defined as one with 10 or more outlets, excluding hotels, offices, financial institutions and other service businesses.

A formula business seeking to open in a space of 10,000 square feet or larger anywhere in the city also will be subject to use-permit review.

The site where Peet's wants to open is across the street from a vacant fire station where the company originally had intentions of locating once the station was redeveloped, a plan that never got off the ground with the collapse of redevelopment agencies across the state.