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To better understand the types and quantities of municipal solid waste disposed, and to assess the City’s recycling potential, SPU has been conducting ongoing composition studies since 1988.
These studies provide information on the makeup of Seattle's residential, self-haul and commercial garbage, as well as construction, demolition and land clearing (CDL) waste. The overall success of Seattle’s programs, education/outreach efforts, and variable rate structure can be measured by how much is diverted from the landfill, and how much recyclable material remains in the garbage. Measuring these two indicators is a large undertaking, so the waste composition studies are only updated every few years.
CDL waste composition studies are used to plan and design targeted C&D waste prevention and recycling programs for this significant waste stream.
To help design and evaluate the citywide recycling can program, the City of Seattle conducted this study to determine the types and quantities of recyclable materials disposed within litter cans.
These studies are designed to determine the quantities and composition of recycling set out by both single- and multi-family residences within the City. Recycling composition estimates obtained from these studies are used to inform solid waste management planning and evaluation and to help determine a portion of the payment amounts from the City to the private company that processes Seattle’s residential recycling.
In 2012, Seattle conducted the first in-depth evaluation of the city’s organics stream to determine both the composition of Seattle’s combined organics stream as well as evaluate the accuracy of the sampling methodology given the variability in the amount and type of yard waste and food waste set out by residential and commercial customers that use plastic carts. Customers who use metal dumpsters or do not use City of Seattle contracted service were not included in this study.