There's a price to pay for a manicured lawn, a bountiful garden or a landscaped office complex: disposing the leftovers, also known as yard waste. But these leftovers are helping some communities reach waste diversion goals through aggressive yard waste collection and processing programs.
While yard waste typically comprises approximately 15 to 20 percent of the municipal solid waste stream, the amount varies depending on the climate, type of vegetation, yard size and amount of multi-family housing. Yard waste can be the largest MSW component during peak generation months, when grass often comprises more than 50 percent by weight. The density of compacted yard waste ranges from 250 to 500 pounds per cubic yard; the density of landfilled yard waste is 1,500 pounds per cubic yard.
Between 1990 and 2000, the amount of yard waste collected for recycling is expected to increase ten-fold. The California Integrated Waste Management Board estimates that only 8 percent of the state's yard waste was recovered in 1990. To meet its 50 percent waste diversion goals, 80 percent of the state's yard waste would have to be recycled, which would require a 5.5 million-ton increase in yard waste composting by the year 2000.
"The time is ripe for industry to invest heavily in composting in California," said Steven Sherman, co-chair for policy of the California Organic Recycling Council. Sherman believes that the growth is driven by a combination of state regulatory reforms for composting facilities, state waste diversion mandates, state support for composting markets (especially in agriculture) and the lack of public funds for capital projects.
Nationally, the Environmental Protection Agency estimates that 35 million tons of yard waste were generated in 1990. An additional 13.2 million tons of food wastes from residential and commercial sources are available for composting. More than 3,000 yard waste composting programs were operating in the United States in 1992, up from 651 in 1989, according to EPA's "Markets for Com-post" report.
Since 1988, an average of 470 new yard waste composting facilities have opened each year, making yard waste composting the fasting growing aspect of the rapidly expanding composting industry (see "Digging In the Dirt: Unearthing Potential," World Wastes, April 1994). Much of this growth has resulted from yard waste bans from landfills, adopted by 19 states and the District of Columbia.
Many communities encourage home composting and grasscycling by offering compost demonstration gardens, lectures on how to compost and free or discounted composting bins for residents who attend the composting lectures. Diversion rates vary by programs, but generally range from 500 to 750 pounds of yard materials per household per year. Resi-dents seem more likely to participate in a program if there is a variable rate structure for garbage collection since it provides a financial incentive.
To date, one of the most successful home composting programs has been established in Ontario, Canada. According to the Ministry of Environ-ment and Energy, the province had achieved a 20.5 percent participation rate by 1993. The Centre and South Hastings Blue Box 2000 project, however, achieved an 85 percent participation level among single-family households by distributing free home composting bins door-to-door.
Governments are promoting grasscycling to decrease the costs of yard waste collection programs and return nutrients to the soil. Grasscycling, in which grass clippings are left on the lawn after mowing, naturally recycles grass. If grass is mowed often enough, no more than one-third of the length of the grass blade will be cut in any one mowing.
Grasscycling is often coupled with deep, infrequent watering to produce an extensive root system and frequent application of smaller quantities of fertilizer. Grasscycling can reduce the amount of fertilizer needed by 15 to 20 percent because clippings return nitrogen to the soil. Many golf courses and parks have practiced grasscycling for years.
"Haulers are often paid a set fee per household per month for gar-bage or yard waste collection," said John Roulac of Harmonious Tech-nologies. "It is in their interest to en-courage programs like home composting and grasscycling and to fund the bin distribution, which will de-crease the haulers' collection, processing and marketing costs."
Roulac estimates that more than 750 cities and counties in North Am-erica have home composting bin distribution programs. "It is clearly the lowest cost option for managing yard clippings and is an opportunity for haulers to gain a competitive edge in proposing yard clippings services to local governments," he said (see chart on page 34).
Some cities are requiring that home composting programs are in-cluded in yard waste or garbage collection contracts. In Milpitas, Calif., the city required the local hauler to provide $20,000 to purchase and distribute home composting bins. Milpitas is buying 880 home composters and will distribute them to citizens, who will be asked to pay approximately half the cost.
Glendale, Calif., offers a chipping service for yard waste on Saturdays. Other cities have encouraged residents to rent or buy shredders to use for home composting.
The type of wastes generated and the climate determine a local government's approach to yard waste collection. In some areas, yard wastes are collected in dedicated rolling carts or existing garbage cans; in other areas, communities use paper or plastic bags.
Many areas of the country are collecting grass, leaves and tree prunings together in a comprehensive source separated yard waste program. San Jose, Calif., began a loose yard waste pilot program in Sep-tember 1991 which was expanded citywide the next year. The city collects yard waste weekly in an articulated loader with a claw attachment.
Source Separation The loose yard waste system does not require garbage bags, cans or carts - residents simply cut prunings to less than five-foot lengths and place them in a pile. San Jose requires that grass clippings and leaves are placed below prunings to help keep them in place. Any residue left in the street is collected monthly by street sweepers.
In July 1993, San Jose dramatically expanded its recycling and gar-bage collection system and revised its unlimited garbage rate structure to variable rates. Since the "Recy-cling Plus" system began, the total a-mount of yard waste collected has increased 45 percent, from 67,627 tons in 1992-93 to 98,319 tons in 1993-94.
Fremont, Calif., started a pilot yard waste collection program in February 1993 for about one-third of their 42,500 single-family households and a drop-off center at the yard waste processing facility. The 32-gallon cans tested an alternative in which residents would use their existing garbage cans with a sticker. During the pilot, Fremont collected 130 to 250 tons per month in the collection program and an additional 200 tons per month of yard wastes at the drop-off center.
Fremont residents preferred 64- or 96-gallon wheeled carts for yard waste collection. The city now offers residents a 20-, 32-, 64- or 96-gallon garbage cart for garbage and recycling. Customers also can choose be-tween a 64-gallon or 96-gallon, vented cart for yard waste. The ad- ditional cost for yard waste carts is $5.24 per household per month, which includes $1.11 per household per month for processing and $4.13 per household per month for collection.
The Fremont program includes a "Zero Generator" exemption from the additional charge for yard waste service. Residents can qualify by certifying that they compost at home; generating no yard waste due to a "hardscaped" lot without any landscaping; or having a gardener who removes all yard materials from the site.
Residents may request Zero Generator status at any time. By submitting the exemption form, residents also authorize the city of Fremont to inspect their trash for residual yard wastes. To date, only 500 of the 42,500 households have requested Zero Generator status.
Pasadena, Calif., started a yard waste collection program in 1991. Operated by municipal crews, the program was phased in to city-wide operations by mid-1993. Pasadena offers a 100-gallon, rolling cart for yard waste as an option to residents for an additional $5 per household per month. Residents may choose either a 60- or 100-gallon mixed waste container with a variable rate.
The city experienced a contamination problem that caused loads to be rejected at the processing facility. As a result, contaminated containers are tagged and left uncollected. After three tags, the city sends a letter to remind them of the program's guidelines. After three letters, the container is removed. Pasadena's program now has a 1 to 2 percent contamination rate.
Sacramento County, Calif., began a pilot program for 3,000 households in March 1993. Residents used 90-gallon carts for yard waste while a 60-gallon cart for garbage was provided at no extra charge. The county reports a $3.65 per household per month cost for its collection crews to service the program.
Approximately 50 percent of those in the pilot service area set out yard waste each week. One year before the pilot began, residents set out 66 pounds per week of garbage. During the pilot, each week residents set out 36.9 pounds of garbage and 32.5 pounds of yard waste. This represents a 46 percent reduction in the amount of wastes landfilled. The county plans to expand the pilot in March 1995 to another 4,000 ac-counts and the service area to all 160,000 households when a compost processing facility is sited.
Clovis, Calif., began a yard waste program in July 1994. The city's contractor provided a 101-gallon, wheeled cart to supplement an existing 101-gallon cart provided for garbage. The contractor charges $3.25 per household per month for the full yard waste collection and processing program. In each of the first six weeks, the residents averaged 37 pounds of yard waste per household. More than 90 percent of the residents are setting out their material weekly.
Leaf And Grass Collection In areas of the country where the predominant yard wastes consist of leaves and grass clippings all year, vacuum collection trucks and plastic and paper bags have been used for collection. In addition, drop-off programs have proven to be cost-effective for collection and composting in rural areas.
In Illinois, the landfill ban required using "first generation" biodegradable bags to collect yard wastes. However, because these bags were made of plastics held together by starch, they didn't break down completely. As a result, the state redefined "biodegradable" with regard to plastics and banned plastics from its composting programs.
Now, most Illinois communities use paper bags for yard waste, with stickers sold by cities and haulers to pay for collection and composting. Similar experiences have been re-ported in Massachusetts and other states with yard waste bans at landfills. But a second generation of plastics is being developed in which the plastic itself actually biodegrades.
In Fargo, N.D., where yard waste disposal is banned from May to Oc-tober, 14 drop-off centers were set up for yard wastes in 1989. Since the first pilot study, the total a-mount of residential waste collected at curbside was reduced by 27 percent through a combination of recycling and yard waste programs. From May 1990 to April 1994, the Fargo program composted more than 20,000 tons of yard waste.
Drop-off centers are on city-owned or leased sites, with ei-ther asphalt or concrete surfaces. They generally have two or three 20 cubic-yard roll-off containers and bins for other recyclable materials. The average site usually measures ap-proximately 1,200 square feet and is open 24 hours a day.
The commercial sector is beginning to incorporate composting into plans for better managing yard and food wastes. Restaurants and grocery stores are experimenting with a variety of composting programs for organic wastes. Land-scaped apartment complexes and corporate centers are beginning to compost yard waste on- and off-site.
The Grocery Industry Committee on Solid Waste in Washington, D.C., estimates that U.S. grocery stores generate 6.6 million tons of compostable food and paper wastes each year. Disposing these wastes in landfills or incinerators costs $482 million per year.
Several major fast-food chains have conducted pilot composting programs over the past two years. Fifteen McDonald's restaurants in the Albany, N.Y., region report that they are composting one-third of their total waste (primarily food and contaminated paper wastes). In Par-lin, N.J., American Soil Inc. collects discarded produce and paper from grocery stores, mixes it with yard waste and sells the product for $14 to $19 per cubic yard.
Hannaford Brothers, Scarbor-ough, Maine, operates more than 90 grocery stores in five Northeastern states. About one-third of the stores separate food and paper wastes from the produce and bakery departments, which are collected for composting by local firms. A grocery store in Oneida, N.Y., found that 69 percent of the 12.67 tons monitored were compostable, including soiled or waxed corrugated containers, su-gar and flour bags and produce wastes.
In Seattle, Larry's Markets began a food waste composting program in 1991. A rear-packer truck collects produce waste, waxed cardboard and floral waste in 90-gallon, wheeled carts and 1.5 cubic-yard steel dumpsters once a week. These wastes are combined with yard waste, stable waste and pulped pa-per in a windrow system. Approx-imately 500 tons of food waste were composted in 1993 or less than 5 percent of the mix in the composting facility.
Leisure World, a 22,000-resident retirement community on 765 landscaped acres in Laguna Hills, Calif., generates between 15 and 20 tons of yard waste daily. The yard waste is taken to an on-site tub grinder for shredding, then composted for 90 days in 150-foot windrows on-site. The material is used in the community for ornamental beds and is-lands, potting soil for nursery stock grown on-site, a growing media for sod production and general soil a-mendments.
Five years ago, the Villages Golf and Country Club in San Jose, Cal-if., developed an on-site composting program in response to the city's ag-gressive recycling goals. The complex covers 2,000 acres, with 200 acres of golf courses, 2,700 single-family houses, 9,000 trees and 100 acres of grassed common areas. The golf courses practice grasscycling by mowing daily. The rest of the complex is pruned and mowed all year, generating 40,000 cubic yards of yard waste annually. Since 1989, the materials have been collected and composted in 90 to 120 days on a one-acre site into 10,000 cubic yards of compost.
The club uses the compost for on-site landscaping. The cost of composting is about $2 to $3 per cubic yard, with a volume reduction of 65 to 70 percent.
Coordinating commercial pickups into a source-separated composting program is a challenge. Rather than being based on packer efficiency for garbage collection, commercial hauling routes must be revised to collect the least contaminated food and yard wastes for composting. Ulti-mately, the markets for the products derived from composting will drive the specifications of acceptable levels of contamination, as in any other recycling field.
Developing Markets Despite the dramatic increase in the amount of yard waste materials collected, unless the demand stays ahead of the supply, the revenues from sale of these materials will de-crease.
In a recent study prepared by Ba-telle for the Composting Council, the authors determined that total production potential of compost from municipal solid waste, sewage sludge (biosolids), horticultural/silvicultural wastes and agricultural residues would be approximately 100 million cubic yards per year (see chart on page 38).
The study also projected approximately one billion cubic yards per year of potential market uses, ten times greater than the potential supply.
For this reason, state and local a-gencies are reaching out to the agricultural communities as one of the largest future potential compost users. Developing this market re-quires methodical testing and evaluation of products produced, development of standards and specifications and a distribution and spreading system that meets individual application needs.
As yard waste programs are developed, careful attention must be paid to appropriate uses for the products produced and to the efficiencies of the collection system. One of the challenges ahead will be producing those products on a consistent and reliable basis to make a name for the products in the marketplace.