About Solid Waste
As we live our lives, leftovers build up. What doesn't go into the sewer system we call solid waste. Solid waste is divided into several categories based on what it is and how it is handled and regulated:
- Municipal Solid Waste (MSW) - includes all the garbage, yard waste and recyclables that residents and businesses set out for collection or haul to a City Transfer station. It includes some materials and items that need special handling, such as old refrigerators and tires.
- Construction and Demolition Debris (C&D) - includes materials from construction and demolition activities such as wood, asphalt shingles, concrete, metal, rocks, brick, and drywall.
- Moderate Risk Wastes (MRW) - hazardous or toxic chemicals exempt from State hazardous waste regulation because they come from home uses or in specified small quantities from businesses, institutions, government agencies, and others. MRW includes used motor oil, pesticides, antifreeze, paint, and solvents. When households generate MRW, it's called Household Hazardous Waste (HHW). When businesses and others generate MRW, it's called Small Quantity Generator Waste (SQGW).
Biomedical waste is managed by the Seattle-King County Department of Public Health.
Solid Waste Composition Studies
To better understand the types and quantities of municipal solid waste disposed, and to assess the City's recycling potential, Seattle Public Utilities (SPU) has been conducting ongoing composition studies since 1988.
Using Spreadsheet Models for Estimating Collection Costs (PDF)
This 1999 paper details Seattle's journey from crisis to an international reputation as a leader in municipal recycling.
The Role of Full Cost Accounting in Solid Waste Management (PDF)
This paper describes two spreadsheet models developed by Seattle Public Utilities (SPU) to estimate collection costs. The models consider variations in collection frequency, truck types, material separation requirements, transfer points, and more for single-family, multi-family and commercial customers.
Who's making all this waste?
Waste is collected from businesses, single-family residences, multi-family buildings, and self-haulers (residents and businesses who bring wastes directly to transfer stations).
Looking at just residential waste, in 2020, 211,567 tons of garbage and recycling was collected from residents. Single-family households generated 60.6% of all residential waste, while multi-family households generated 39.4% of all residential waste.
How much is recycled or put in a landfill?
Of the 211,567 tons of waste generated in 2020, garbage accounted for 119,903 tons and recycling 91,664 tons.
In the residential garbage, we found that 63.1% of the materials could have potentially been recovered for recycling or composting, with 21.3% being able to be recycled curbside and 30.4% composted. The most common material by weight in Seattle’s residential garbage was packaged edible food scraps – 11,181 tons. That means we must work harder to get those materials in our compost.
What's in the recycling?
We are doing pretty well at reducing contamination in the recycling, with 94.5% of the material able to be recovered, or made into something new. The top two materials by weight in the recycling are paper products, accounting for 33.8%. You can check out more of what is in the recycling in our 2022 Residential Waste Composition Study.
Construction and Demolition Debris
A sizable portion of the City's waste consists of construction and demolition (C&D) debris. Historically, most C&D debris has been disposed of separately, although some construction waste materials are disposed of as MSW. C&D is separated because the requirements for landfilling this "inert" material are less stringent than for garbage. C&D is increasingly being recycled.
- From June 2013 to May 2014, nearly 100,000 tons of construction materials were hauled for disposal to three private transfer stations (Republic’s Third & Lander and Black River facilities, and Waste Management’s Eastmont transfer station)—and two railheads from construction and demolition (C&D) job sites in Seattle
- Overall, 386,000 tons of construction materials generated in 2013 with approximately 61% of the C&D generated recycled or salvaged and another 6% beneficially used as fuel end products
Check out more information on Construction and Demolition Waste Management or view the 2017 CDL Waste Composition Study.
Household Hazardous Waste
The Hazardous Waste Management Program (Program) is a coalition of local governments working together for a healthier and cleaner King County, of which Seattle Public Utilities is a member and on the Management Coordination Committee. The Program works jointly on policy, prevention, and safe disposal. In 2022, 3,231,240 pounds of hazardous waste was kept out of our waste stems and the environment.
The Washington State Department of Ecology estimates that over 50% of HHW is used motor oil. Other major hazard categories include: flammable liquids like fuels, solvents, and oil-based paint, yard and garden products like pesticides and herbicides, acids and caustics like household cleansers and hobby chemicals, antifreeze, and batteries..
Biomedical waste
Biomedical waste from medical, dental, and veterinary offices and hospitals is regulated by the State and King County health code. It must be collected and disposed by regulated companies. "Sharps" (hypodermic needles) are a type of biomedical waste that is accepted for proper disposal at City Recycling and Disposal Stations and at some pharmacies and doctors' offices. Read more about Sharps Disposal.
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