A citizens group has filed a lawsuit seeking to force the Cotati City Council to reverse its May decision to award the city's garbage contract to Redwood Empire Disposal.

The group is seeking a court order to force Cotati's City Clerk, Tami Taylor, to accept a referendum that would require the city to reopen the contract to bidding or put it before voters in a special election. A hearing on the lawsuit was set Tuesday for Dec. 11 in Sonoma County Superior Court.

Taylor had rejected the petition in May, saying the garbage contract wasn't attached to the petition.

"People were signing something without having the information that's legally required in order to circulate petitions," City Manager Dianne Thompson said on Tuesday.

The group, called Cotati Citizens for Open Market Competition, collected the signatures of 537 registered voters in Cotati, enough to place the issue on the ballot, according to the county registrar of voters.

Its lawsuit was spurred by the council's awarding of a new 10-year franchise agreement to its existing hauler, Redwood Empire Disposal, without calling for contract bids. That shut Industrial Carting of Santa Rosa out of the process, although it asked several times to submit a bid.

"The bottom line is, we offered to put up a bid. They could have taken it or not taken it, and they didn't even go that far," said Curtis Michelini, Sr., owner of Industrial Carting. "The city, I felt, did not do the citizens justice."

Thompson said Industrial Carting does not provide the full range of services that Cotati needed, and also that Redwood Empire Disposal had served the city well for 10 years.

"There were no other full-service providers. So there was no compelling reason to go out to bid," she said.

Michelini said his firm had decades of experience.

"Our company is 65 years old; we had a countywide licenses," he said. "I used to pick up garbage in Cotati in the '60s. So trash hauling is nothing new to me."

Mayor Mark Landman criticized the citizens group because its chairman, Greg Karraker, who also led last year's successful effort for a ballot measure to ban roundabouts in the city, lives outside Cotati, while its treasurer, Caroline Banuelos, is a Santa Rosa resident who received campaign donations from Michelini when she ran for the Santa Rosa City Council in 2012.

"I think that's relevant," Landman said.

Karraker said the group and the referendum it is pushing "is representing 537 registered voters."

Ba?elos said she is playing a role because she consults "lightly" for Industrial Carting on nonprofit-related issues and considers the Michelini family friends. The $500 contribution to her 2012 campaign from Michelini was not a factor, she said.

Michelini declined to say if he was paying for attorney's fees for the suit.

Karraker said city officials could easily dispose of the legal challenge "by saying, 'We'll do our job, we'll look at the bids.'"

Thompson said that with the exception of Windsor, most other local cities had renewed their garbage contracts the same way.

"Other cities in our region had undertaken a similar process with negotiating with them with a good outcome," she said.