Materials Management

Oregon Solid Waste Characterization and Composition Study

2016/2017 Study

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.

DEQ is still completing analysis of the data and preparing a final report, which will be available here when complete. The Excel tables below give preliminary detailed information on the composition of wastes disposed in different parts of the state.

​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.

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