Garbage In, Money Out

Thanks to composting, City Hall needn't be Tucson's only source of gas.

When the City Council meets Monday to discuss how to close a projected $45 million shortfall in the next fiscal year's budget, one item it won't be considering is an "environmental" fee. First unsuccessfully proposed a year ago by City Manager James Keene to raise $8.5 million annually to help defray the cost of garbage disposal, the $6-a-month charge quickly met with public outrage and political criticism. So this year Keene has shelved that idea and is tentatively suggesting across-the-board cuts from every department instead.

Despite that decision, the enormous cost of disposing of an ever-increasing amount of stuff along with remediating environmental problems at past landfill sites will continue to pile up. But there might be some encouraging news on the horizon: Selling methane gas produced by buried garbage is beginning to generate some sizable sums of money in other parts of the country. Critics, however, contend the city isn't being nearly aggressive enough in converting its solid waste into a revenue provider.

According to Eliseo Garza, director of Tucson's Solid Waste Department, the city's Los Reales landfill has a privately funded system that collects methane gas. This gas, which is sold to Tucson Electric Power Company, can generate electricity for 4,000 homes and has an estimated retail value of $3.8 million. But almost all the profit goes to the firm that installed the gas collection and distribution system.

While this methane gas system might be expanded in the future, thus producing additional money for the city, retired University of Arizona engineering professor Stuart Hoenig believes Tucson has been dragging its feet far too long in using its garbage to grow more income. Almost a decade ago he recommended to the City Council in vain that it develop an approach to treating landfills that would dramatically increase the amount of methane gas produced while vastly shortening the time required before the garbage pile shrank.

"The city has a pit, they dump stuff into it, but it doesn't destroy the material," Hoenig says of the existing situation. "It is a very, very slow process which needs bigger and bigger landfills. It just never ends."

Instead, Hoenig was proposing that Tucson use a process that would add liquid to a landfill was free of construction material, automobile parts and similar items in order to accelerate the breakdown of the garbage. When that is done anaerobically, or in the absence of oxygen, gases including methane are produced in greater quantities than with normal landfilling.

Hoenig's suggestion went nowhere. He says of the response, "When the council discovered they would have to work with Pima County on it, they lost interest. They must think it is easier to do things the same old way their grandfathers did."

An accelerated anaerobic process for garbage disposal, however, is now gaining popularity across the country. Don Augenstein of the Institute for Environmental Management states, "There have been a lot of tests done on this approach since the 1970s. Its advantages are an increased generation of gas and the disappearance of some of the landfill volume. [The process] is being embraced by the waste management industry."

Augenstein has been working with officials of Yolo County in north-central California on what they term an anaerobic "bioreactor" project. After the completion of a pilot phase of the program, the project is about to be expanded to a new, full-scale, 100,000-ton landfill site.

While he estimates the process is between $1 and $4 per ton more expensive than typical landfilling, and some others double that figure, Augenstein emphasizes, "You get your money back." Plus, he adds of the extra expense, "That is only a fraction of the total of solid waste costs."

Augenstein believes that if the process were used nationwide, methane gas from garbage piles could meet roughly 1 percent of the country's electrical needs. But an even bigger advantage, he says, comes from the space savings provided by the technique.

While current landfills shrink at a glacial pace, in its current test project Yolo County has seen a 25 percent reduction in three years, results that Augenstein labels "spectacular." That means a lot more garbage can be piled in the same amount of space.

"Saving space is a big monetary factor," he says. "It is worth a heck of a lot to have fewer landfills because of siting problems, less hassles with neighbors and other issues."

It is the availability of additional space at Los Reales landfill, however, that local officials cite as one reason Tucson hasn't pursued the anaerobic process. But, they say, it will probably be used sometime in the future.

In the meantime, the city is testing an aerobic (done in the presence of oxygen) composting method on old landfills along the Santa Cruz River near Sentinel Peak. The current pilot project is a 50-by-50-foot area doused with 400 gallons of water a day; eventually the process could be expanded to a surrounding 5-acre site.

The results from six months of tests, according to Ray Murray of the city's Environmental Management Department, have been encouraging, with the garbage pile settling one foot. Murray estimates it will require two years to fully degrade all the material in the test plot and lists two primary advantages of this approach. "First, it has created settlement [quickly]," he says, "and second, contractors won't [face] all the environmental problems they do now of building on a landfill site."

Those are important considerations for the city as it tries to encourage development for the downtown Rio Nuevo project near the Santa Cruz River. But it isn't very encouraging to Hoenig, who criticizes the city for not pursuing an accelerated anaerobic process with its garbage.

"The Chinese have been doing it for 3,000 years," he says in frustration, "but in Tucson people don't want to do anything new. I gave up trying to deal with the city years ago."