BioCycle November 2005, Vol. 46, No. 11, p. 30
Study in the Portland, Oregon region assessed possible impacts of a residential yard debris/food scraps program on existing collection and composting system.
Steven Sherman

METRO, the regional government that serves more than 1.4 million residents in Clackamas, Multnomah, and Washington counties and the 24 cities in the Portland, Oregon metropolitan region, has set waste recovery goals of 62 percent by 2005 and 64 percent by 2009. Donation and diversion of commercial and residential food scraps is part of Metro’s plan to achieve those recovery goals. A recent article in BioCycle (“10 Lessons From 10 Years of Food Residuals Diversion Planning,” July 2005) provided an update on Metro’s and the City of Portland’s commercial organics diversion program. This article provides the results of a study released in September 2004 that focused on diversion of residential organics, in addition to the existing yard trimmings program.
The main purpose of the study, conducted by Applied Compost Consulting, Inc. and Bell & Associates, Inc., was to analyze the potential or likely impacts of a residential yard debris/food scraps program on the Metro region’s existing residential yard debris collection and composting system. Currently, no local composting facility serving the region’s yard debris haulers is permitted to accept all types of residential food scraps. If a residential organics system were implemented, the yard debris and food scraps collected together would have to be sent to a fully-permitted and operational organics composting facility. Aspects of the overall existing system that were considered for impacts included: collection, transfer, processing, end product markets and product marketing, cost, materials recovery, participation rates, collection and transfer vehicle miles traveled, and economic considerations (e.g., private sector revenues, job creation or retention, and system diversity).
Existing System
Over a quarter-million households in the Metro region receive yard debris collection at least twice a month (2003 data). Roughly 105,000 tons of residential yard debris were collected by franchised haulers in the Metro region in 2004 (preliminary Metro data). Collection is the largest component of the overall cost of recycling yard debris in the Metro region, typically comprising over three-quarters of the overall cost. Labor is the largest contributor, accounting for approximately 60 percent of collection costs, based on rate information obtained from the City of Portland.
Participation in yard debris collection programs is very seasonal, on account of seasonal variations in yard debris generation patterns. During April through November, participation can reach 70 to 80 percent. However, during December through March, participation can be as low as 10 to 20 percent. The average annual weight of source separated yard debris collected per customer varies across the Metro region. Portland has service every other week, and has the lowest yield per customer (358 pounds per year). At the other end of the spectrum, the urban portion of Clackamas County registers slightly over 900 pounds of collected source separated yard debris per customer per year, using a 60-gallon cart picked up weekly.
A majority of the yard debris collected by the franchised hauling companies is delivered directly (i.e., without the use of transfer stations or reload facilities) to permitted yard debris composting facilities in the Metro region. Most of the area’s population is located within a five-mile radius of either a compost facility or a reload facility.
There is a strongly competitive, well-established local processing infrastructure for yard debris. Six processors handle yard debris collected by franchised haulers within the Metro region. In 2003, tip fees charged in the Metro area for source separated yard debris ranged from $6 to $18/ton. For yard debris composting facilities located within a metropolitan area, these tip fees are at the low end of the national scale. In addition to the six compost facilities, there are 15 reload operations currently accepting residential yard debris from franchised haulers within the Metro area. It appears that the current system, in the aggregate, has or can develop sufficient capacity to handle any likely ongoing increase in source separated yard debris from the Metro region.
None of the yard debris processors within the Metro region has a permit to accept the broad range of food scraps (i.e., both vegetative and nonvegetative) generated by residents. Most of the facilities have residential neighbors nearby, and face the prospect of community resistance should they seek such a permit. None of the five compost facility owners interviewed was willing to incur the costs associated with obtaining such a permit (estimated by some to be as high as $200,000), and making the processing-related facility upgrades (e.g., paving, impervious liner, collection of water run-off, possibly a roof or an enclosed building, etc.) or other site improvements (e.g., access roads, lighting) that could be required by the State of Oregon Department of Environmental Quality (DEQ) or by local land-use planning departments. Estimates by interviewees for anticipated required site improvements ranged from $500,000 to $4.5 million. (DEQ currently is developing new compost rules that may place more stringent requirements on yard debris processors. The agency is in the advisory committee portion of the rulemaking, which may continue for another year. Once new rules are adopted, composters will be allowed several years to implement whatever new requirements become rule.)
A review of compost markets found a strong demand for organic soil amendments within the Metro region. Over 90 percent of the approximately 80,000 tons of organic soil amendments produced annually from municipally-generated yard debris from Metro area communities is sold locally within the year of production, and year-to-year inventories remain small relative to market demand. Most of the end products are sold, after basic processing, in 7.5 cubic yard increments at wholesale prices, predominantly to commercial landscapers.
Most residential food scraps are currently disposed at the Columbia Ridge Landfill, located approximately 180 miles from Portland. By contrast, residential yard debris that is reduced in size (via chipping or grinding) or composted at local facilities travels less than 15 miles on average from the point of generation.
It is estimated that local yard debris processors generate $8 to $10 million in annual revenues, and employ approximately 200 people (of which an estimated 75 are attributable to the residential yard debris brought by local franchised haulers). It is also estimated that the payroll and local taxes associated with these businesses exceed $1.2 million annually.
Modeling Program Changes
Methodology: The cost model used a standard rate setting methodology to estimate the future costs of a residential organics collection program that would be combined with existing local yard debris collection programs. Future costs were projected using inflation assumptions, route productivity, and data gathered from previous solid waste rate reviews as well as from prior studies on residential organics collection. Chris Bell of Bell & Associates, Inc. produced detailed cost models for the study. Collection costs were projected on a local level due to variances in service levels. Processing costs were projected using an estimated cost for the Metro region as a whole. Projected increases in costs due to the proposed program changes were based on data provided by the Cities of Portland and Gresham and by Clackamas and Washington Counties.
Assumptions: The model assumed that the collection system and frequency of collection of solid waste and recyclables currently in place remains constant, and organics collection (if not already collected weekly) was assumed to be increased to weekly service. Table 1 reviews those assumptions.
A range of anticipated participation and capture rates for residential food scraps collection was used in the model. Participation rate was defined in this study as the average number of participants in any given week divided by the total number of households with food scraps collection service. The participation rate used in the model was 31 to 50 percent. Capture rate per participating household was defined as the percentage (weight basis) of residential food scraps that is separated at the source by participating residents and placed correctly into the curbside organics container. The capture rate used in the model was 53 to 80 percent (4.4 lbs/week to 6.6 lbs/week, based on an assumption of 8.2 pounds of food scraps disposed by potential participating households per week). Overall capture rate was defined in this study as the percentage (weight basis) of residential food scraps collected for off-site composting divided by the sum of residential food scraps handled off-site, through either composting or disposal. An overall capture rate of 16.5 to 40 percent (1.4 lbs/week to 3.3 lbs/week) was used.
The best-case scenario uses an assumption of 50 percent participation. This figure is actually higher than any known participation rate in residential food scraps collection programs in the United States. (The assumptions for the lower end of the participation and capture rates used in the model are based on the upper limits of a survey of residential organics collection programs in Northern California.) For modeling purposes, a high capture rate per participating household is used to demonstrate the potential for diverted tons. With a capture rate of 80 percent per participating household, and a food scraps disposal rate of 8.2 pounds per household per week, the average participating household would divert approximately 6.6 pounds of food scraps per week, or a capture rate per participating household of slightly less than one pound per day.
Collection Containers: The number of additional carts assumed to be necessary for the collection of residential food scraps was computed using a two-step process. The first step was to determine the percentage of current customers without a hauler-furnished 60-gallon container. The percentage was then multiplied by $0.89, the estimated monthly cost of the container. It was also assumed that residential kitchen containers used to collect food scraps would be purchased at a cost of approximately $3.50 each.
Analyzing The Impacts
Adding residential food scraps to the existing residential source separated yard debris collection and processing system in the Metro region would affect various parts of the overall organics management system:
Collection: Shift to a uniform weekly, year-round curbside collection frequency for residential yard debris, even during seasonal periods of very low generation and participation.
Transfer: Greater usage of transfer stations. With local processor scenario, would be negligible change in vehicle miles traveled for yard debris. With distant processor scenario, would be greater vehicle miles traveled (VMTs) for yard debris (over 2 million additional VMTs per year).
Processing: Substitution of numerous local facilities that efficiently compost yard debris at a low cost per ton with fewer and possibly more distant facilities that can compost food scraps and yard debris, but at double to triple the cost per ton ($15/ton, existing system vs. $41-$48/ton, local or distant processor scenarios).
End Product Markets and Product Marketing: With local processor scenario, would be development of compost products with potentially higher nitrogen content (from food scraps). With the general trend toward increased product demand locally, the market is expected to absorb increased local supply with ease. The distant processor scenario would supplant well-established local distribution channels and known product type and quality with distant distribution channels and uncertain product type, quality and quantity returning to the Metro area.
Economic Development: Lower jobs created per public dollar expended on recycling programs, based on loss of local private sector yard debris composting industry jobs (75) and annual revenue ($5.6 million), due to a reduced amount of locally-processed yard debris, with partial offset of these figures under the local processor scenario.
In terms of diversion, the addition of residential food scraps to the yard debris collection program is projected to raise the overall recovery rate in the Metro wasteshed by 0.6 percent (60 basis points) to 1.5 percent (150 basis points). These figures are based on an increase in diversion of residential food scraps of between 13,400 tons/year and 32,400 tons/year.
In terms of costs, the modeling found that households in the Metro region (with significant differences by jurisdiction) are projected to face a rate increase of between 11 and 18 percent to cover the costs of the program. For various reasons – especially changes in frequency of collection, purchase of curbside organics carts, and substantially higher tip fee associated with processing a residential yard debris/food scraps mixture than with processing just residential yard debris – this projected rate increase may be higher than that of other communities which have added residential food scraps to their existing yard debris collection programs. (Without purchase of new curbside organics carts the overall rate increase was projected to be 10 to 12 percent.)
It should not be inferred that these findings mean that adding residential food scraps to existing residential source separated yard debris collection and composting systems is not cost-effective or advantageous elsewhere. Strong regional variations exist in terms of programs, frequency of collection, seasonality, existing collection and processing infrastructure, rate structures and related circumstances. While it appears not to be the case for Metro, it is quite possible that residential food scraps collection and composting is a logical and fairly straightforward next step programmatically for many communities that have regular curbside collection of yard trimmings.
Report Recommendations
Over the past few decades, Metro and Metro area jurisdictions have achieved rapid and substantial results in recycling and composting materials that otherwise would have been landfilled. It is well understood within the professional recycling community that moving from, say, a 33 percent recovery and waste reduction rate to one that approaches two-thirds of all municipal solid waste generated, will present more challenges than achieving the first 33 percent. Part of this challenge – and part of the maturing process for solid waste management programs – is to do so within the context of supporting other environmental benefits and goals.
Specific recommendations, given Metro’s particular set of circumstances, included: 1) Strive toward balancing the materials recovery imperative with other environmental benefits and goals that are within the public sector’s purview (such as solid waste reduction, energy and soil conservation, and reduced pollution), with recognition that new recycling initiatives do not necessarily fulfill environmental sustainability criteria; 2) Initiate and support efforts to recover food scraps and nonrecyclable paper in the commercial sector first, before committing significant resources to the roll-out of residential organics collection programs; 3) Continue to work with local composting facilities and regulators at the local and state levels, to help local processors to make the adjustments necessary to meet Metro’s long-term needs; 4) Conducting pilot programs for the recovery of residential food scraps and other organics should be included in Metro’s ten-year regional solid waste management plan, without a specific commitment to full-scale implementation. A series of pilot programs could be established to test variations in collection equipment and other program details, for factors such as: collection vehicle types; routing efficiency; curbside collection containers; in-home collection containers; frequency of collection of refuse (weekly, biweekly); participation rates; contamination rates; recovery rates; effect on rate of home composting; and others.
Since publication of this report in autumn 2004, Metro has made significant progress in fostering a commercial organics processing infrastructure. Earlier in 2005, Metro signed a processing contract with Cedar Grove Composting in Maple Valley, Washington. Initially, commercial organics are hauled to one of Cedar Grove’s facilities in Washington. Once quantities being diverted reach 10,000 tons/year, Cedar Grove has committed to building a facility within the Portland region. It is expected that when this facility is sited and operating, there will be greater competition for yard debris to use as a bulking agent with the commercial organics.
Steven Sherman, M.S. Resource Economics, is President of Applied Compost Consulting, Inc., based in Oakland, California. He is providing food scraps program planning and implementation assistance to several communities on the West Coast including San Francisco, San Mateo County (CA), Alameda County (CA) and Portland. You may contact him for more details at: (510) 985-8366; compost@LMI.net.