California Department of Resources Recycling and Recovery (CalRecycle)

"Innovations" Case Studies: Organics Options

Yard Trimmings

Residential Yard Trimmings

In most communities in California, residential yard trimmings make up 15 to 30 percent of the total residential waste stream. Although some major seasonal fluctuations occur in most areas, this waste stream is produced year-round in most of California. Recognizing the significance of yard trimmings, 294 communities (56 percent of the total in the state) had implemented some type of yard trimmings recycling program. In 1994, another 28 (9 percent) had planned such programs.

Collection programs are typically provided weekly or biweekly to customers to obtain the maximum participation. Unlike curbside recycling materials, residents generate yard trimmings on a sporadic basis when they are able to tend to their gardens, lawns, and pruning. Residents who do not participate every week benefit from having more frequent service when they want it.

Residents are usually asked to set their yard trimmings out in the following containers:

  • Cans
  • Bags
  • Rolling carts
  • Unbundled, in the street

The least expensive system often uses existing garbage cans for yard trimmings collection (sometimes with a decal or a sticker to label the can provided by the community).

In Monterey Park, Calif., for example, yard trimmings must be set out in permanent containers marked with a special yard trimmings sticker or tied in bundles under 4 feet in length. Containers must be turned so stickers are visible to drivers.

Stickers can be obtained from the local waste hauler (Athens Services) or in person at city hall public counters. Yard trimmings are usually collected in the early afternoon, after the trucks have finished collecting refuse. Yard trimmings must not be contaminated with refuse or recyclables, or they are collected as trash.

Some communities allow residents to place yard trimmings at the curb in plastic or paper bags. Although plastic bags are a contaminant in processing at composting facilities, these communities have decided the convenience of this approach is worth the cost to separate the plastics. Other communities have experimented with providing biodegradable plastic or paper bags to residents. These approaches are generally more costly and have not been widely adopted.

The majority of the most successful programs are providing rolling carts or collection services unbundled on the street. Rolling carts have become more prevalent through the 1990s for the collection of yard trimmings.

Carts offer the advantage of collection with automated or semi-automated collection equipment. This decreases worker injuries and workers’ compensation claims for the haulers. Carts are also attractive to residents who do not have a lot of yard trimmings weekly, because the material is easily contained and rolled to the curb.

Carts have a significant additional attraction for the future. Carts lend themselves to the addition of discarded foods and food-contaminated paper. Carts are the best of all home storage containers for these additional organics to be collected together with yard trimmings. The examples below show how this can help communities increase organics recycling.

In San Jose, unbundled yard trimmings are collected with the “claw” attachment on a loader and placed in the back of a rear-loader packer truck. A major advantage of this approach is that residents do not have to cut yard trimmings into small pieces and don’t have to place yard trimmings into containers to recycle them. The results have proven very popular in San Jose, as in other communities that have used this approach.

In the City of Sacramento, the public actually voted two to one in a public referendum in the early 1990s to maintain the yard trimmings collection program there. That program operated for many years using the same collection approach as San Jose. People loved the convenience of the program for their gardening and yard work.

A typical example of yard trimmings collection programs are those provided by the City of Riverside. Unlike most communities in California, Riverside initiated its IWMA programs with its green waste collection program in 1992. The city focused on green waste first, because that was the major material identified in its waste characterization study.

Riverside shifted from twice-a-week collection of trash to once-a-week collection of trash and once-a-week collection of green waste. Green wastes are placed in a green automated collection container. The green waste is delivered and tipped at a $20-per-ton savings when compared to trash. For the 1998-99 fiscal year, the residential green waste collectors were able to divert 42 percent of the material collected from landfills. This resulted in a savings of $856,427 in disposal fees.

One of the early concerns about different program designs was ensuring that a quality product could be produced from yard trimmings collected broadly from residents. Experience during the 1990s has shown that all of the above collection programs have been able to produce quality compost feedstock.

The key to obtaining good feedstock is proper enforcement of good preparation requirements and monitoring of yard trimmings as they are collected on the street. In many communities, collectors leave behind improperly prepared material with a note to educate residents on proper preparation for the future.

Processing of residential yard trimmings is often done by local composting facilities or by shredding at landfill sites for alternative daily cover (ADC). Throughout the 1990s, the issue of ADC has been a concern to composters. If landfills accept yard trimmings for tipping fees that are lower than composting facilities in the area, communities are able to save money. However, by accepting yard trimmings for lower tipping fees, landfills make it much less economic for composters to operate.

The counting of ADC as “recycling” was originally adopted by the CalRecycle as an interim policy to assist communities until stronger markets could be developed (for example, in the agricultural sector).

Communities could contribute to expanding markets by buying compost and mulch products and by requiring public and private developments to use those products (see “community procurement” on page 13). However, Chapter 978, Statutes of 1996 (AB 1647, Bustamonte), codified the ADC credit into law as an ongoing option for diversion credit under the IWMA.

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Christmas Tree Recycling

Most communities collect Christmas trees after the holidays as part of their solid waste services. Most programs offer both curbside and drop-off locations. Drop-off locations are particularly well designed for Christmas trees, because it is often easier to drop off trees than to cut them up into smaller sizes needed to comply with yard trimmings collection programs.

Because most of these trees are uncontaminated (except those flocked or left covered with tinsel), many communities have found that they can recycle these trees into valuable compost and mulch products.

In San Diego, Christmas tree recycling has been operating since 1973, organized by I Love a Clean San Diego. Since 1982, the City of San Diego has supported the effort as well. In 2000, the city had 31 drop-off sites.

Hosts for the drop-off sites included shopping centers, parks, open spaces, vacant lots, community centers, schools, tree nurseries, and city facilities. The city also collected trees through its curbside yard trimmings recycling collection program.

More than 130,000 trees were collected from the drop-off sites and 11,000 from the curbside program, for a total of 141,800 trees. All of the trees were ground into mulch and compost at the city’s Miramar “Greenery” as soon as they arrived on-site. Curbside collected trees were put through a trommel before grinding to remove contamination (this was unnecessary for trees dropped off).

The trees not only enhance the smell of the mulch, but they also slightly increase the acidity. This makes the mulch very useful to residents in the area with alkaline soils, which are commonly found in San Diego. Mulch is distributed free to residents.

The City of San Diego diverted 84 percent of all Christmas trees from landfilling, disposing only of the flocked and tinseled trees. This was determined by actual tree counts, a curbside participation study, and tonnages from the Miramar Landfill. A conversion factor of 17 pounds per tree was used to convert tonnage data to the number of trees recycled.

The operational costs incurred for this program are part of the normal yard trimmings collection budget for residents. The only additional costs incurred are in advertising, including 70,000 flyers, 700 posters, production of a movie theater slide, and new signs and banners for drop-off sites.

In addition, the program included a media kickoff event, and coordinators produced 30-second video public service announcements (PSAs) for all TV stations in San Diego. They also provided radio interviews and radio PSAs. News releases went to church and business newsletters and to other media promoting Christmas tree recycling and how to have a no-waste holiday. Program staff operated a Christmas Tree Hotline that received 6,112 calls.

Commercial Yard Trimmings

Many developments with large landscaped areas are developing their own composting programs on-site. These include parks, golf courses, corporate campuses, colleges and universities, and large multifamily residential developments.

In areas where adequate space is available, chipping and mulching or windrow composting may be done on-site. In other areas that are more densely developed, new commercial on-site composting systems are being used (see examples below under commercial discarded food).

In many areas, independent landscapers are still responsible for maintaining the properties and collecting the yard trimmings. Landscapers take their materials to competitive composting facilities wherever they are available.

In San Jose, the Villages Golf and Country Club has been operating an outstanding yard trimmings composting program for many years. They collect grass clippings, weeds, and tree prunings from routine landscape maintenance activities. They grind these materials into particles 1 to1½ inches in size. They compost these materials in windrows, which take 90 to 120 days for a final product. This reduces the volume of incoming materials by 65 to 70 percent.

The Villages facility uses the end product as a soil conditioner, fertilizer, and a suppressor of soil-borne diseases (by increasing the biological activity in the soil). Compost is used as a top dressing for lawns, dug into garden beds for vegetables and flowers, spread as mulch around bushes and shrubs, backfilled in planting holes, and spread between rows of plants.

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Last updated: November 22, 2010
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