An engineering firm hired by Yamhill County to study alternatives to expansion of McMinnville's Riverbend Landfill identified 12 of them, but found some degree of fault with all.

The firm urged the county to give Riverbend an extended lease while working with its three private sector partners, and the local business community and citizenry, on a compromise long-term solution. It suggested that solution perhaps be based on construction of a mass-burn waste-to-energy incineration plant resembling one that has long served Marion County, but is currently at capacity.

The firm urged the county to avoid what it termed the "either/or, lose/lose" approach of simply coming down for or against continued long-term use of Riverbend to landfill garbage and examine alternatives from a "positive and creative perspective," exploring incineration technology and perhaps other technologies as they continue to evolve.

In a report presented Wednesday to the county's Solid Waste Advisory Committee, Zia Engineering & Environmental Consultants identified four other regional landfills where local garbage could be hauled if Riverbend expansion was denied - Coffin Butte in Corvallis, Wasco County in The Dalles, Columbia Ridge in Arlington and Roosevelt Regional in Klickitat County, Wash. But it said that would mean residential rate increases of 28 percent to 38 percent and commercial rate increases of 23 to 31 percent for Western Oregon Waste customers.

In the report, Engineer Richard Hertzberg and accountant Chris Bell identified eight alternative disposal technologies - mass burn, derived fuel (RDF), aerobic digestion, anaerobic digestion, gasification, thermal depolymerization, hydrolysis and pyrolysis.

But they said only the first three are commercially viable at present, and only one of those - mass burn - is capable of handling the full range of municipal waste. They termed anaerobic digestion and gasification "emerging technologies" and the rest "experimental technologies."

The consultants said construction of an incineration a plant would require not only an investment of years of effort and millions of dollars, but also a guaranteed garbage supply - something Yamhill County lacks.

Three private firms control local collection and disposal of garbage - landfill operator Waste Management Inc. and garbage haulers Western Oregon Waste and Newberg Garbage & Recycling. They are free to haul and dispose of waste in whatever way proves most economical, whether Riverbend Landfill is expanded or simply allowed to reach capacity and close, the consultants noted.

What's more, Hertzberg and Bell said, without expansion, Riverbend is projected to reach capacity in 2014. And it would not be feasible to bring a mass burn plant online by then.

They said it would take at least eight years, when the county has only five. And they said it isn't realistic to assume the tonnage needed to justify an incinerator operation would ever return if diverted elsewhere following a Riverbend closure.

While they stopped short of making a formal recommendation, the two "encouraged" the county to give Riverbend an extended lease on life while actively pursuing alternatives with its constituency and private sector partners.

"We're not necessarily preferring this approach," Hetzberg said, "but we are suggesting there are opportunities here."

He said Waste Management, based in Houston, Texas, has built many incineration plants around the country. Yamhill County would be a viable location, given an assured waste stream of sufficient volume, he said.

While continuing landfilling at another location is technically viable, the resulting rate hikes projected by the consultants could prove a powerful political deterrent. That's especially true in the southern two-thirds of the county, served by Western Oregon Waste, as the company lacks the transfer station infrastructure of Newberg Garbage & Recycling.

For WOW, the consultants projected an increase in today's $29.83 monthly rate for 96-gallon residential service in McMinnville to $38.18 for Coffin Butte, $40.24 for Wasco County, $40.90 for Arlington and $41.06 for Roosevelt. For Newberg Garbage, now at $24.38, they projected increases to $26.89, $28.45, $28.94 and $29.08 respectively, which would be much more manageable.

Three-yard commercial service currently runs $229.68 in McMinnville, compared to a much lower $183.17 in Newberg. The consultants projected respective increases to $281.88, $294.72, $298.90 and $299.85 in McMinnville, compared to $198.97, $208.60, $211.65 and $212.55 in Newberg.

In addition, closure of the Riverbend Landfill would cost the county more than $800,000 a year in franchise and disposal fees, true whether local garbage were hauled elsewhere, incinerated to produce energy or disposed of via some other technology.

The final decision lies with Commissioners Leslie Lewis and Kathy George, as Commissioner Mary Stern's husband is an executive with Western Oregon Waste, leading her to recuse herself.

They are scheduled to reopen a long-delayed hearing on the expansion plan at 9 a.m. Oct. 14. They plan to spend the time between now and then studying the consultant report.