Sonoma County today is set to extend interim deals with its two main solid waste contractors, a move meant to buy more time to hammer out a side agreement with cities that has stalled the long-term reopening of the county's central landfill.

Operation of the Mecham Road site west of Cotati was to be permanently privatized this summer under a 20-year deal worth an estimated $547 million. But execution of the agreement with Arizona-based Republic Services has been delayed by ongoing county-city negotiations over potential future liabilities associated with the landfill.

A lawsuit, meanwhile, by a group of neighbors and the county's largest labor union has sought to overturn the county decision that approved the outsourcing deal.

The county-city talks have bogged down on the issue of how to settle an estimated $50 million in closure and post-closure costs for the 42-year-old dump should Republic Services go out of business and fail to cover those future claims.

Cities have long wanted to erase that liability and their preferred approach is to have the county assume it should Republic fail. They would pay for that release through garbage rates over the next 20 years.

The key question at the bargaining table remains how much to charge at the landfill gate to cover the liability.

"What is reasonable to collect and set aside for that potential risk," said Susan Klassen, the county's transportation and public works director.

The negotiations between the county and its nine cities are the latest chapter for the embattled central landfill, which was reopened on a interim basis in late 2010 after a five-year closure triggered by water pollution concerns.

The liability charges would have the most direct effect on what commercial and self-haulers pay at the landfill. Landfill rates are a lesser factor in the bills for curbside customers.

The delayed settlement has postponed construction to open new areas for waste in the landfill — room that's needed if the county is to avoid hauling most to all of its garbage out of the area in the short term.

The delay also has run up against the Aug. 31 expiration of two contracts covering county solid waste services. One with Republic covers interim operation of the landfill; the other with the Ratto Group of Companies, the county's dominant waste hauler, is for operation of four of the county's five transfer stations.

The short-term contracts were to expire with the onset of the 20-year deal with Republic. The deal would keep the landfill in public ownership while outsourcing its operations. Going forward, the landfill's county-run transfer station would transition to Ratto, a subcontractor under the deal.

To buy more negotiating time with cities, the Board of Supervisors today is set to authorize a one-year extension of the interim contracts. Combined they are worth an estimated $12.9 million, with the slightly higher share, $6.5 million, going to Ratto.

Republic officials have found a small area of the landfill that they believe can be used to accommodate the dump's current waste stream through next September, when the interim contracts expire.

But county and city officials voiced hope the entire one-year extension would be unnecessary and that they would settle the liability talks by the end of this year, allowing the long-term deal and re-opening to proceed.

The hypothetical nature of future risk — assuming Republic's demise and any range of problems at the landfill — has made the negotiating task difficult, said Santa Rosa City Manager Kathy Millison.

"Thinking forward 30 to 50 years, it has its obvious challenges," she said.

The delay has pushed back the hiring by Republic of 15 of 26 affected county landfill workers. County operation of the central transfer station was to cease in mid-July. Layoff notices have since been extended by 60 days, Klassen said.

The lawsuit challenging the landfill deal is another ongoing hurdle.

It was filed jointly in May by a group called Renewed Efforts of Neighbors Against Landfill Expansion and the Service Employees International Union Local 1021.

The suit claims that the county's environmental review of the landfill's future — based on a 1998 document updated twice in recent years — does not account for several planned improvements, including a material sorting facility.

The neighbors pressing the case, residents of the nearby Happy Acres subdivision, have voiced concerns about impacts on water and air quality and traffic.

"We were told that this landfill was going to be closed," said Roger Larsen, a Happy Acres resident. "Now guess what, it's not going to be closed and is going to go on for another 22 years at least. That's a little alarming for us who live here."

SEIU Local 1021 has taken issue with the outsourcing, a move it claims would displace 26 skilled county workers. For those employees not hired by Republic, the county is seeking to fill open positions in public works and other divisions.

The Board of Supervisors item on the interim contracts today is on the consent agenda.