Sticks and Limbs

Organic waste is often considered the heaviest part of the waste stream, accounting for up to a third of municipal solid waste. As a result, many jurisdictions today collect green waste—yard trimmings, shrubs and trees—as part of their residential recycling programs.

"In California, most municipalities pick up residential green waste at the curb or are heading in that direction," says Joel Corona, recycling market area manager in California for Waste Management’s Recycle America Alliance. "That wasn’t the case five years ago," he adds.

Corona reports that most municipalities use a container system. The city of Sacramento however uses a "claw" system, whereby residents are encouraged to put their green waste along curbsides. Little wheel loaders scoop up the green waste and put it in the backs of trucks where it is composted.

"San Jose tried Sacramento’s system but went back to using containers," Corona says. "The claw system is less expensive. You don’t need to put a $30 container outside every home. On the other hand, you don’t have green waste blocking the gutters and washing into the sewers. The container system is much cleaner."

ORGANIC STEW. Defining green waste or determining what to include in the organics recycling stream can take some thought. Some innovative communities, Corona notes, are adding food scraps to green waste. "Pot roasts and turkey carcasses added to green waste, however, require a special and more complicated method of composting," he says.

Palo Alto, Calif., has been collecting green waste at its landfill site for almost 25 years. Last year, the city initiated a pilot project whereby green waste was included in Palo Alto’s curbside collection system. As of July 1, the pilot project has become a permanent arrangement.

"The amount of green waste we collected as a result of the curbside program last year was just slightly more than we collected only at the landfill the year before," reports Wendy Hediger, Palo Alto’s recycling coordinator.

She notes that people from outside the community continue to bring their yard wastes to the landfill. "We have more material coming in than we can process," Hediger says. "Some of it we have to ship off to be processed elsewhere."

Mike Saley, the manager of strategic planning and diversion for the city of Calgary in Alberta, Canada, reports that his city introduced a one-year pilot program April 1 in three residential areas where semi-automated trucks pick up yard wastes and other organic material regularly.

Tom McMurtrie, who is in charge of the Systems Planning Unit-Public Services for Ann Arbor, Mich., notes that the city collects about 14,000 to 15,000 tons of yard waste per year through its curbside recycling program and another 10,000 tons of leaves in the fall.

"The numbers have been stable for the past few years," he says, "but we expect to see some growth from neighboring communities bringing their waste to our site," McMurtrie reports.

Ann Arbor began its curbside program for green waste in 1989. McMurtrie notes that yard waste is collected weekly. Material can be no more than 6 inches in diameter and trees can be no taller than 4 feet. The yard waste can be bundled or put in a paper bag.

"We found it more cost effective to do all our own collecting and processing," he says. "We compost on our site. We just purchased a new tub grinder. We also have a windrow turner and a screener to screen the finished product."

In Florida, the city of West Palm Beach installed a new grinding and sorting system at its composting facility a couple of years ago. West Palm Beach Solid Waste Authority’s Patrick Carroll reports that yard waste was banned from Class I landfills several years ago in the Sunshine State.

"That provided the impetus for the large yard waste collection program we now have," he says. "We process about 150,000 tons of yard waste per year, which we collect through a curbside system. Although the number of households we collect from has remained steady over the past 10 years, the amount of material we are collecting is increasing."

Maine has a statewide approach to reusing green wastes. The Maine Resource Recovery Association is comprised of more than 200 towns and acts as a materials broker for 73 recycling centers statewide.

"Our goal is to encourage more composting," says Victor Horton, a spokesperson for the association.

The city of Winnipeg in Manitoba, Canada, and the town of Islip, N.Y., a suburban Long Island township, collect green waste seasonally. Both communities collect bagged leaves (curbside or drop off) in the fall and discarded holiday trees in January. Islip also collects yard waste during a five-week period in the spring.

Islip operates a 40-acre site dedicated to composting yard waste. "Commercial landscapers and residents also bring their clippings, leaf materials and prunings to our composting facility," says Eric Hofmeister, commissioner of the Department of Environmental Control for Islip.

MARKET CHANNELS. Dan Mc-Ginnis, Winnipeg’s manager of solid waste services, reports that the city has been selling backyard composters to Winnipeg residents for the past three years. "We’ve sold 20,000 so far," he says.

To compost additional organic material, the city of Winnipeg has a large shredding machine at one of its landfills that removes the plastic bags.

The city uses the composted material as landscape coverings for its landfills. Most other communities surveyed either sell their composted material or give it away to area residents.

Tom McMurtrie, for example, notes that Ann Arbor’s compost has gained wide acceptance. "Our major buyer is the Michigan Department of Transportation, which uses the material for roadside projects. Local residents and county drop-off sites also buy quite a bit of it."

Hofmeister says Islip composted 55,000 tons of yard wastel ast year. The compost is available to Islip residents for free—and to commercial customers, such as landscapers and golf courses for a fee.

Palo Alto is selling its compost to nurseries in the area, while Palm Beach finds several end markets. "We give some of the stuff back to the public in the form of mulch," Patrick Carroll says. He notes that 60,000 tons of material is used in Palm Beach’s biosolids composting facility, where it’s mixed with brush and sewage sludge. The remainder is used as boiler fuel in power plants and for landfill cover.

To process some of its organic waste, Calgary is experimenting with a bioreactor that will recover the gas in organic material and use it to generate electricity.

It is in the northeast that recycled green wastes—specifically wood chips from demolition and construction debris—are being used on a large scale as an energy source.

"We are one of the largest processors in America of wood chips," says Jonathon Hixon, co-founder and vice-president of ERRCO, Epping, N.H. "We process about 175,000 tons of material per year. We have recycled 1 million tons of material since we opened our commercial operation in 1995," he adds.

ERRCO has provided energy based on biomass fuel for clients throughout New England since 1988. The 22,000-square-foot plant has four different magnets, two separate picking lines, two shredders and a water flotation tank that separates wood from aggregate.

The company has a workforce of about 50 and operates two shifts per day. "There aren’t many companies around like ours," Hixon says.

He reports that ERRCO is planning to expand its recycling operations within the next year to include sheet rock and gypsum wallboard.

Montreal-based Boralex Inc. produces renewable green energy for customers in Quebec and the northeastern United States. "We use wood residue to supply power plants in New York and Maine," says Carole Villeneuve, communications director for Boralex. "In Quebec, we sell energy to Hydro Quebec."

Boralex was founded in the early 1980s. The company employs 43 at its two-year-old plant in Montreal and currently can process 60,000 tons of recycled wood products annually.

"We are considering expanding our processing center in the next few months to increase our capacity," Villeneuve says.

Corona also notes notes that clean, highly processed wood chips can be made into pressed board for cabinets and other furniture.