"Innovations" Case Studies: Curbside Recycling, the Next Generation

General Information

• Overview
• Program Characteristics
• Automation, Blue Bag, and Wet/Dry Sorts

Overview

Curbside recycling has become as American as apple pie. More than 139 million Americans now have access to curbside collection of a myriad of recyclable materials. More Americans now recycle than vote.

California was an early leader in the tremendous growth in this sector of the recycling industry. Curbside recycling programs were developed in most communities in California after the passage of the Integrated Waste Management Act (AB 939, Sher, Chapter 1095, Statutes of 1989 as amended [IWMA]).

Hundreds of millions of dollars have been invested in recycling by both the public and private sector during the past decade. These investments include collection vehicles and processing facilities to make curbside recycling an everyday reality for most Californians. However, the programs that were developed in the late 1980s and early to mid-1990s have begun to be replaced by the next generation of curbside recycling programs.

The next generation of programs is striving to collect even more recyclable materials as efficiently as possible. That has led to a number of key developments, including the following:

• Pay-as-you-throw programs, which provide residents with incentives to recycle more and waste less.
• Larger, more sophisticated materials recovery facilities (MRF) that can process more materials with no more residues.
• Increased collection of materials, especially mixed paper, corrugated cardboard boxes, and more types of plastics (despite continuing marketing problems.)
• Commingling of recyclable materials to collect more materials more quickly.
• Co-collection of garbage, recyclables, and/or organics in the same truck, but in different compartments.
• Collection of food discards and food-soiled paper with yard trimmings.
• Automated and semi-automated collection.
• Collection from single-family, multifamily, and small businesses in one truck.

Program Characteristics

Curbside programs have grown dramatically over the last decade. BioCycle magazine’s annual “State of Garbage in America” series shows increases of more than 278 percent in California, and more than 375 percent nationally in population served since 1990. Programs and population covered in California reached a peak in 1996.

Studies completed for the Solid Waste Association of North America (SWANA) in California and nationally (see references) have produced data from hundreds of curbside recycling programs. These SWANA studies used statistical techniques to provide reliable information on the impacts of demographics, program designs, and financial features on the performance of curbside recycling programs.

The studies provide information on the impacts of program features-separate from the demographic differences in communities (for example, income, population, urban/rural) and other program features. The impact of commingled collection effectively holds the mix of materials accepted by programs constant.

The SWANA study results summarized in Table 2 are “additive.” If the community’s recycling rate is already 12 percent, the effect of moving to commingled collection (using the California results) would be to add 2 to 4 percentage points of recycling. The new recycling total would be 14 to 16 percent. Adding multiple changes together will yield results that are close to (but not exactly) what would be expected.

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Table 1: Number of Curbside Recycling Programs and Population Served-California and National

(Sources: “The State of Garbage in America,” (annual series in BioCycle magazine); Jim Glenn, March 1990, pp. 48–53 and April 1990, pp. 34–41; J. Glenn and David Riggle, April 1991, pp. 34–38 and May 1991, pp. 30–35; J. Glenn, April 1992, pp. 45–55 and May 1992, pp. 30–37; Robert Steuteville and Nora Goldstein, May 1993, pp. 42–50; R. Steuteville et al., June 1993, pp. 32–37; R. Steuteville, April 1994, pp. 45–52 and May 1994, pp. 30–36; R. Steuteville, April 1995, pp. 54–63 and May 1995, pp. 30–37; R. Steuteville, April 1996, pp. 54–61 and May 1996, pp. 35–41; N. Goldstein, April 1997, pp. 60–67; N. Goldstein and J. Glenn, May 1997, pp. 71–75; J. Glenn, April 1998, pp. 32–43 and May 1998, pp. 48–52; J. Glenn, April 1999, pp. 60–71.)

The California study also examined which program features were associated with higher and lower program costs. Table 3 summarizes which program changes might be most cost-effective for a community.

Those changes that add lots of tonnage (Table 2) and decrease costs-or cost very little (Table 3)-show the most promise for cost-effective programs in communities.

The combination of these findings suggest that the best ways for communities to increase tonnage most cost effectively would be to take the following actions:

Implement pay-as-you-throw rates.

This approach would provide the largest increase in tonnages for recycling, and the cost impacts are small. (Studies other than the referenced studies have shown no increased costs or decreases in costs when implementing pay-as-you-throw (or “variable rates” in most communities). Pay-as-you-throw rates also increase yard waste recycling tonnages, and they encourage residents to be more careful in what they buy so they can avoid creating wastes. Preventing waste is the cheapest waste management strategy.

Communities in California usually charge double for twice the service level (“a can is a can”). A few communities in the state charge even higher premiums, which could be more than twice the 30-gallon rate for 60 gallons of service.

Commingle collection.

Commingling results in extra recycling tonnages and lower costs. However, suitable processing facilities are required to make this work successfully.

In the early years of recycling, three-bin separated programs were quite common. Commingling was considered more problematic. Program managers encouraged customers to think of the materials as a resource, not just another garbage stream. In addition, contamination and materials quality were legitimate concerns, because processing facilities for commingled programs were generally not available.

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Table 2: Estimated Impacts of Program Design Options on Recycling Diversion

(Sources: Lisa Skumatz, “Nationwide Diversion Rate Study,” 1996”; and “Achieving 50% in California.,” 1999. SERA, Inc., used with permission of the author.)

In large part due to the IWMA, the public and private sectors in California have invested hundreds of millions of dollars to develop much greater processing capacity. In recent years, new processing capacity has been built with the capabilities of processing commingled recyclables without increasing the amount of residue from sorting those materials at a MRF.

The biggest concern about commingling has been the concern that materials recovered would be less valuable. In some instances, that has happened. However, with aggressive marketing and market development programs, this effect can be minimized.

One of the most powerful forces in favor of commingling has been the increased number of materials curbside recycling programs are able to collect (see below).

In addition, due in large part to concerns about worker injuries and costs of worker compensation, many communities have adopted automated collection programs. Automated commingled programs reduce costs and increase consumer convenience.

Table 3. Estimated Percentage Changes in Program Costs from Program Choices and Changes

(Sources: Lisa Skumatz, "Nationwide Diversion Rate Study" and "Achieving 50% in California." SERA, Inc., used with permission of the author.)

The combination of these factors has made commingled collection programs more attractive and cost-effective to many communities. Commingled programs fit very well with less frequent collection. This program (potentially combined with automation) can lead to very substantial reductions in the cost of providing service.

Commingled programs are moving toward pulling out one material (either paper or glass) and setting that alongside or on top of the recycling container. This minimizes the key contamination problem from commingled collection. The City of Seattle keeps the glass separate. Most of the programs in Massachusetts pull out the paper separately.

Every-other-week collection.

Lower frequency collection decreases costs dramatically, and it results in only small decreases in recycling tonnage. The tonnage decrease could be offset by other changes. The dramatic cost savings from this approach are due to the greater efficiency in collection. It is very inefficient for a truck to pick up nearly empty containers every week. Instead, every other week collection means houses put out more materials and/or more containers. This approach can be used for commingled or separated programs. Frequency changes require greater promotions work with residents to ensure that they know which weeks they are to recycle in their neighborhood.

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Add materials.

Adding more eligible materials to a recycling program will result in greater tonnages. When asked about program changes, more than 20 percent of communities (in a survey of more than 600 communities across the U.S.) indicated they had added materials during the previous two years. In decreasing order of frequency, the study found communities had added the following materials:

• Mixed paper
• Plastics (a variety)
• Cardboard
• Paper
• Glass
• Metal cans

Only about 5 percent indicated they had dropped materials (most commonly mixed paper, plastics, glass, and cardboard).

The results from Table 2 indicate that adding materials can lead to significant increases in the amount of recyclables recovered through collection programs, adding 2 to 5 percentage points. Adding materials makes programs more useful for residents and provides them additional savings on their garbage bills. However, this change can also increase program costs by 15 to 35 percent, depending on the system and material.

The types of materials added have to be carefully coordinated with collection vehicle capacities and processing capabilities. Because adding new materials to the collection program create increased costs, this approach is recommended when other changes are made that may offset the increased costs of new materials.

Automation, Blue Bag, and Wet/Dry Sorts

Recycling cost savings and efficiency improvements reflect changes in demand by local communities. These savings result from:

• Collecting more recycling materials per stop.
• Making quicker stops.
• Compiling larger loads between unloading.

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Table 4: Advantages of Commingled vs. Separated Recycling Collection

Certainly, commingled collection and decreasing frequency can help achieve these objectives, but other strategies are of interest. The California SWANA study examined the performance of a variety of modified collection systems for recycling. The study found some promising signs of increased efficiency, and in some cases they saw increased diversion from recycling collection. Program costs and diversion from these programs were compared with those from more “standard” programs in California.

Table 5: Comparison of Alternative Recycling Collection Systems

(Source: Lisa Skumatz, “Achieving 50% in California.” SERA, Inc., used with permission of the author.)

Unfortunately, few of the programs around the nation are able to provide cost and diversion data for these systems. This shortage of reliable data (beyond a few case studies in the literature) makes it hard to tell if any of the technologies will offer consistent performance in delivering increased diversion and reduced costs.

Blue bag programs seem to provide strong benefits, but some communities report contamination problems and poor or volatile performance. This indicates a need for a stronger track record for blue bag programs. The exception was wet/dry collection, demonstrated in Canada. That program provided high diversion at consistent costs.

Communities that pursue automated collection should follow these procedures:

1. Buy the best truck possible to minimize the amount of breakdowns and maintenance costs.
2. Assume a higher percentage of “backup” trucks than average because of maintenance issues.

Advantages and disadvantages, and the projected outlook for these alternate collection systems, are summarized in Table 5.

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Last updated: October 26, 2007