Asphalt

King County promotes the use of recycled materials in asphalt, and Washington State requires local jurisdictions to use these materials and for contractors to report their use in public construction projects. WSDOT allows up to 20% Recycled Asphalt Pavement (RAP) and up to 20% Recycled Asphalt Shingles (RAS) in new pavement and also supports the use of Warm Mix Asphalt (WMA), which uses less fuel, cuts greenhouse gas emissions by about 24%, and costs less to produce than traditional hot mix asphalt (HMA). Each year, about 40,000 tons of asphalt shingles are disposed of in King County, and the Solid Waste Division is working to expand local recycling markets to keep more of this material out of the landfill.

Policy and Goals

King County’s Sustainable Purchasing Executive Policy (CON 7-22-1-EP)

• Reducing waste generation by choosing products that are durable, reusable, repairable, refillable, recyclable, compostable, salvageable, deconstructable, or made with recycled content or remanufactured parts
• Lowering embodied greenhouse gas (GHG) emissions associated with a product’s manufacture, transportation and use

2025 Strategic Climate Action Plan

• GHG 67. Reduce embodied carbon of materials used in King County capital projects

All agencies with capital programs are required to evaluate which capital programs and projects in their CIP use the largest volumes of high-embodied carbon materials such as concrete, asphalt, carpet, steel, gypsum, rebar, and wood and to identify which capital projects and programs will use lower embodied carbon contract specifications for the highest impact materials.

Washington State Department of Transportation -- Standard Specifications for Road, Bridge, and Municipal Construction

• Recycled materials are required under SHB 1695 (2016). Bidders must state the total percent of construction aggregate and concrete materials in the project that are recycled. These percentages must follow the limits in Section 9-03.21(1)E, Table on Maximum Allowable Percent of Recycled Material.