Turning trash to cash: The green waste recycling story

George Gonzalez
Chief Forester
City of Los Angeles, California
Presenter, 2005 APWA Congress

If a tree falls in the forest and no one is around to hear it fall, does it make a sound?

This question has been asked for hundreds of years. And while I have a 50-50 chance of answering that question correctly, I can more accurately answer what happens to the tree after it hits the ground; it begins to decompose!

The decomposition process adds nutrients to the soil, which in turn improves the quality of the soil, which leads to healthy young seedlings, which will grow to be large trees that will eventually die and...well, you get the picture.

But, what happens when a tree falls in the city? Besides the damage it could cause to cars, homes, and people, it will be cut up and hauled to the dump. At the dump, it will take up valuable landfill space. As the tree decomposes, instead of creating valuable soil nutrients, it creates methane, a gas that must be vented from the dump (adding to the cost of operating a landfill).

In many cases, the urban forest trees that shade our city streets and parks, along with backyard trimmings such as grass clippings, fill our local landfills and become part of the municipal waste stream rather than being utilized as a valuable resource.

Once dumped, the potential for producing value-added products such as woodchips, mulch, compost, or lumber is lost, and our landfills become prematurely filled to capacity. On average, the "green waste" stream makes up about 33% of the overall municipal waste. If current waste-management practices continue as is, it is estimated that over half of the nation's 9,300 landfills will face closure in 10 years.

Fortunately, municipalities from Honolulu to Hartford, from Miami to Minneapolis, and from Los Angeles to Lansing are all jumping onto the green waste recycling bandwagon.

In Illinois, the municipalities of Urbana and Champaign have joined forces to recycle their green waste. In Portland, Oregon, the tri-county recycling program has been recycling green waste since 1980. In Austin, Texas, they recycle over 20,000 Christmas trees per year. And in Los Angeles, we are recycling almost 300 tons of green waste per day at just one of our three green waste recycling centers.

What has caused the interest in green waste recycling? Certainly, there are economic and environmental reasons for diverting our green waste out of the municipal solid waste stream. But in many cases, green waste recycling programs were started because of state or local legislation requiring municipalities to divert the green waste out of the landfills.

In 1998 the California Legislature passed Assembly Bill 939. The bill, known as the Integrated Waste Management Act, required that at least 25% of all green waste be diverted by 1995 and 50% by the year 2000.

Yard trimmings are mixed with tree trimmings at the Van Norman Green Waste Center.

In 1993, the Street Tree Division in the City of Los Angeles' Department of Public Works, Bureau of Street Services started the City's first in-house green waste recycling program. Initially, the program was very modest and we only processed the tree trimmings generated by the Street Tree Division's crews as part of our maintenance operations. To staff the program, we "borrowed" a Tree Surgeon Supervisor, an equipment operator, and a truck driver from existing crews, to make our first green waste recycling crew. That first year we recycled 8,000 tons of green waste, meeting our goal of recycling 100% of our tree trimmings. And after realizing a savings of $343,000 in tipping fees, we knew we were on the right track.

The biggest challenge we faced that year was finding a suitable site to process the green waste. The first green waste recycling site was the 2,500-square-foot parking lot of one of our service yards. The yard was too small from the start, plus it interrupted the day-to-day operations of the yard. A better solution had to be found.

The ideal recycling site needed to be away from residential areas, freeway accessible, and have adequate space to expand the program in the future. In addition, this ideal location would need to be acquired without any additional funds. As you can imagine, this was a tall order to fill!

Enter the City's Department of Water and Power (DWP). They control several reservoirs within the city limits that met all of our needs. However, convincing the Department to share their land was initially met with skepticism. It wasn't until we were able to show them how we could save them money by avoiding tipping fees that they finally agreed to start a partnership with our Bureau.

So in 1996, we moved the operation from the service yard parking lot to our current location, Van Norman Dam. The Van Norman Dam is the largest reservoir within the City of Los Angeles, and we were able to establish a 600,000-square-foot recycling center. In exchange for the use of their land, we recycled DWP's green waste generated by their line-clearance operations. The first year we recycled approximately 4,000 tons of DWP green waste and saved them $193,000.

  Ready-to-spread mulch

Shortly after that, we began recycling some of the tree trimmings produced by the Department of Recreation and Parks. But we still had not fully realized the potential of our green waste recycling operation. Our program was limited to recycling tree trimmings from three City Departments (Public Works, Water and Power, and Recreation and Parks) until 1998 when the Department of Public Works' Bureau of Sanitation, the City's largest recipient of yard trimmings, began using our recycling services.

As part of the City's curbside recycling program, the Bureau of Sanitation (BoS) collects approximately 1,500 tons of yard trimmings daily. Yard trimmings are primarily made up of grass clippings, leaves, and other assorted vegetation found around the home.

BoS was recycling their green waste using a private contractor at a cost of $16,000,000 annually. In the first year of our collaboration, we were able to save BoS $2,000,000.

With the help of BoS, we were able to increase our staffing from three to 36 employees. We were also able to upgrade our equipment from one small tub grinder to three large tub grinders and five truck tractors to haul our finished products to farmers and orchards throughout Southern California.

Our collaboration with BoS brought many benefits, but it also brought one sizable challenge. Before we started our partnership with BoS, all of the green waste we processed was relatively clean. That is, it did not have much contamination such as trash and debris. When we started processing yard trimmings for BoS, we quickly realized that homeowners were throwing everything into the green waste recycling bins, including the kitchen sink. We had to dedicate most of our staff at the Van Norman recycling center to remove contaminants from the yard trimmings.

Once we perfected the process of cleaning yard trimmings, we began producing a mulch material that was better than the woody mulch we produced from recycling just tree trimmings. By providing a 50-50 blend of yard and tree trimmings, we are able to produce a top-quality mulch material that is placed along the City's 300 acres of landscaped median islands and is highly sought out by farmers and orchard operators.

The benefits of our green waste program have been many. Along with saving the City millions of dollars annually on tipping fees, the diversion of green waste helps conserve rapidly dwindling landfill space, helps conserve significant amounts of water, and helps to improve the porosity and aeration of the soil resulting in healthier, more vigorous plants that will have a higher capacity for producing oxygen. Furthermore, mulch helps control erosion and serves as a barrier to weeds, reducing the necessity to buy, mix, and apply herbicides.

The manner in which you view and treat your green waste will determine whether it is trash or cash. The City's green waste recycling program has proved to be a winner for our citizens and the environment. So what happens when a tree falls in the City? We grind it up and put it back to work to improve our environment!

George Gonzalez will present an educational session on this topic at the 2005 APWA Congress in Minneapolis. The session is entitled "Improving the Environment through Green Waste Recycling" and takes place on Sunday, September 11, at 4:00. George will join the APWA Facilities and Grounds Technical Committee during the Minneapolis Congress. He can be reached at (213) 485-5675 or ggonzele@BSS.LACITY.ORG.