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Waste Composition Study

Oregon Solid Waste Characterization and Composition Study

In 2023, DEQ conducted three interrelated waste and recycling composition studies.  

  • Disposed Waste Composition Study 
  • Inbound Commingled Recycling Study  
  • Outbound Commingled Recycling Study 

Each section below briefly describes each study and then gives a status update and results as published so far for that study.  As of June 2025, all results are preliminary and will be updated as further analysis is complete. 

The following document provides a description of each material category for all three studies:

Both the inbound and the outbound commingled recycling studies lump a number of the categories from the disposal site study together - particularly the categories of contaminants that are rare in commingled recycling. The inbound commingled recycling study also splits some categories from the disposal site study to take into account exemptions from the Recycling Modernization Act passed by the Oregon Legislature in 2021 such as the exemption for drug packaging.

Disposed Waste Composition Study 

This study collected 1,042 samples averaging more than 200 pounds each from 55 transfer stations and landfills throughout the state, and sorted them into 152 material categories. The study also included detailed analysis of the rigid plastics in 180 samples, removing contaminants to determine the clean, dry weight of rigid plastics disposed, and identifying each piece of plastic by resin and form. This is the ninth such study DEQ has conducted since 1992. Marion, Lane, and Deschutes Counties and Metro also contributed to the study by funding additional sample collection in their jurisdictions.

Current Status – Disposed Waste Composition (June 2025)

DEQ has completed analysis of the field data from sorts for all jurisdictions and waste streams within those jurisdictions, and the results are published in a series of Excel files linked below. DEQ has not yet completed the detailed analysis of the rigid plastic samples or has applied contamination correction factors from previous studies to the field data results. When that analysis is complete, the current Excel files below will be updated, but for now, be aware that the weights of material are the “dirty, wet" weights. For example, the cardboard weight will include not only the clean, dry cardboard, but also any water absorbed into the cardboard from rainwater or food waste.

The first sheet of each Excel file provides an explanation of what is in the other sheets. The second sheet gives the composition of the jurisdiction as a whole, and subsequent sheets give the composition of specific waste sources in that jurisdiction, such as “residential route trucks," “commercial route trucks," and “loose drop boxes."

The methodology used in the 2023 study is very close to the methodology described in the 2002 study except that in 2023, analysis to determine contamination correction factors was done only for rigid plastics. Final results when published will use averages of contamination correction factors developed in all previous studies from 1998 to 2016.

Inbound Commingled Recycling Study  

This study includes data from 379 samples averaging more than 200 pounds each from 36 recycling reload facilities or commingled recycling processing facilities and sorted them into 87 material categories. It was conducted to gather baseline information needed for rule development and implementation of the Recycling Modernization Act passed by the Oregon Legislature in 2021. Marion and Lane Counties and Metro all contributed by funding additional sample collection in their jurisdictions.

Current Status - Inbound Commingled Recycling (June 2025)

All field work for this study is complete. The first sheet of the results Excel file linked above provides an explanation of what is in the other sheets. The subsequent sheets give the composition of material categories across jurisdictions and specific waste sources.

The methodology used in the 2023 study is very close to the methodology described in the 2009/2010 study except that in 2023 all samples were collected directly from route trucks or other vehicles when they first unloaded, whereas in 2009/2010, samples from outside the Metro area were collected from transfer trailers, and so contained a mix of residential and commercial materials. DEQ is currently working on finalizing the report for the study.

Outbound Commingled Recycling Study 

This study was conducted at 8 commingled recycling processing facilities in Oregon to determine the composition and quantity of each commodity and residue stream produced by the facilities from sorting commingled recycling. The purpose was again for rule development and implementation of the Recycling Modernization Act, to provide baseline information on the contamination level in each of the outbound recycling commodity, and to determine the capture rate for each of the separate materials entering the facilities in the commingled recycling. “Capture Rate" as used here is the percentage of a material entering the facility in the commingled stream that leaves the facility in the appropriate commodity. Using plastic bottles as an example, it is the percentage of plastic bottles entering the facility that are properly sorted and leave the facility in plastic bales, as opposed to going out in the wrong commodity bales (such as mixed scrap paper) or disposed as sorting residue. This study updates a similar study conducted in 2009/2010, linked below. 

Current Status - Outbound Commingled Recycling (June 2025)

All field work for this study is complete. DEQ presented preliminary results for both the inbound and outbound commingled recycling studies at a session of the Association of Oregon Recyclers Conference on June 18, 2024. These results are in slides 25 through 55 of this document. DEQ is currently working on finalizing the analysis and the report for the study.

For all three studies:
  • Field work for the studies was conducted by Sky Valley Associates, with Cascadia Consulting Group and Stina as subcontractors. Cascadia Consulting Group conducted the field work for the Outbound Commingled Recycling Study and assisted in the other two studies. Stina assisted with resin identification for the rigid plastic analysis done as part of the disposed waste study. 
  • As has been true for all past waste and recycling composition studies, these studies were possible only through immense assistance from disposal sites, collection companies, and recycling processors who allowed us on their sites and gave us space for sorting, provided confidential data, and provided equipment and personnel to help us identify and capture samples.

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In May 2016, Oregon Department of Environmental Quality began field work on a year-long statewide waste composition study, with assistance from Metro, Marion County, Lane County, Washington County, and the cities of Portland and Beaverton. Field work for the study was conducted by Sky Valley Associates, and involved collecting and sorting 974 samples of solid waste weighing on average more than 200 pounds each, collected at 55 landfills, transfer stations, and mixed solid waste processing facilities throughout an entire calendar year. Samples were sorted into 138 material categories. All beverage containers in the samples were counted by beverage type and container material type. In all, 103.7 tons of solid waste were sorted, and 17,727 beverage containers were counted throughout Oregon.

The Excel tables below give detailed information on the composition of wastes disposed in different parts of the state. These tables were updated in July 2018 to include disposal of single-material loads such as shredded tires that were not included in the waste composition sampling, and to deduct estimates of materials salvaged from burner ash and from three transfer stations post-disposal. 

​How to read the report

The first sheet of each Excel file provides an explanation of what is in the other sheets. The second sheet gives the composition of the jurisdiction as a whole, and subsequent sheets give the composition of specific waste sources in that jurisdiction, such as “residential route trucks,” “commercial route trucks,” and “loose drop boxes.”

The methodology used in the 2016/17 study is very close to the methodology described in the 2002 study.  A description of each of the material categories is linked below:

This study, like previous DEQ waste composition studies, gives two values for the composition of each materials in the wastestream, “Field Results” (columns B and C of each sheet) and “Contamination Correction Results” (columns D and E of each sheet). “Field Results” are based on the weight of each material as sorted and weighed at the disposal site. However, many materials in the garbage are dirty and wet. For example, cardboard may have become wet from rain or from absorbing moisture from food in the garbage, and there may be materials inside of cardboard boxes or that adhere to the cardboard when sorted at the disposal site. This study cleaned and dried samples of the materials in the field to estimate “contamination correction factors” that can be used to estimate how much “clean, dry” material is present in the dirty, wet materials as sorted at the disposal site. Columns D and E show these “contamination-corrected” results. The methodology for this part of the study is explained in Appendix C of the 2002 study. For estimating the tons of each material disposed each year, it is best to use the contamination-corrected results. For comparing this study to studies in other jurisdictions though, it is best to use the field results as most waste composition studies do not attempt to estimate the cross-contamination of materials being sorted.

Each Excel file was updated in July 2018 to provide estimates and make adjustments to the overall waste composition for:

  • Shredded tires, gypsum wallboard, and medical waste that was disposed as a single material or stream that was not sampled as part of the waste composition study
  • Scrap metal recovered from ash from the Marion County Energy Recovery Facility in Brooks, Oregon, and
  • Material recovered from mixed waste from drop boxes and self-haul vehicles at three Metro-area transfer stations at a point after we had collected and sorted the solid waste samples at those facilities.

These estimates and adjustments were made only for the waste disposed overall in the jurisdictions included in the Excel file, and not for any of the individual waste substreams, as explained in the first tab of each Excel file.


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​Results of a year-long statewide waste composition study conducted by DEQ in 2009/2010, with assistance from Metro, Marion County, Lane County, the City of Eugene, and the City of Portland, are provided in the tables and Excel files linked below. Field work for the study was conducted by Sky Valley Associates. Results draw on data from 999 samples of solid waste collected at 58 landfills, transfer stations, and mixed solid waste processing facilities throughout the state. Results are presented for 130 material categories.
 
The table below gives the percentage of each material in the disposed wastestream statewide:
Detailed information on the composition of waste from different parts of the state for different sources is given in Excel spreadsheets that are downloadable at the following links:
The presentation below was presented at the Association of Oregon Recyclers conference in June 2011. It presents an overview of trends in solid waste disposal and recovery from 1993 through 2010, and integrates results from waste composition studies, disposal tonnage reports and the annual material recovery survey. It includes pictures showing the way that DEQ waste composition studies are carried out, and methodology for analysis.
 

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​In addition to looking at the composition of disposed solid waste in 2009/2010, DEQ also studied the composition of commingled recycling collected in Oregon, and also the composition of outgoing sorted material going to recycling markets:

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The two Marion County documents are based on the extra sampling of waste in Marion County funded by the County:

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​The methodology for the 2009/2010 study and the 2005/2006 study was similar to the methodology outlined in Appendices B and C of the 2002 study report.

Contact

Peter Spendelow
Waste Composition and Recycling
503-229-5253