CompostWise for Public Agencies

About the CompostWise program

Applying compost improves environmental outcomes for public projects. It aids stormwater management, supports waste reduction, and cultivates local green jobs.

King County’s CompostWise Program works to bolster the regional compost market. We do this by procuring and using food and yard waste compost. Additionally, we collaborate with other jurisdictions to encourage similar practices.

King County's Compost Procurement Ordinance (KCC 18.20)

Ordinance 19552, as required by the Washington Organics Management Law, defines "compost," mandates its use in county projects with certain exceptions, and establishes reporting requirements. This ordinance supports compost diversion and strengthens end markets.

CompostWise technical assistance program

The CompostWise program is here to help you and your teams. If you need assistance or have questions about compost, reach out to compost@kingcounty.gov.

King County's Universal Compost Contract (CPA #6549248)

Any King County agency can use this universal contract to access compost at $25/cy. The agency can contact the vendor directly and reference the CPA when purchasing. Regional public agencies with a cooperative purchasing agreement with King County can also use this contract.

Procuring and using compost

• Comprehensive Guides (Quick and Detailed), how to specify and use compost in landscapes, erosion control, and stormwater management
• Video: The Do's and Don'ts of Applying Compost
• King County Surface Water Design Manual, descriptions of approved applications of compost for stormwater management and filtration

Request technical sssistance

• Reviews of general and project specifications
• Presentations and demonstrations for design and engineering professionals
• Assistance with planning and evaluating innovative uses of compost in landscapes, stormwater applications, and agriculture

Specifying and procuring quality compost

• APWA format specification for compost and soil mixes
  PDF | Word
• CIS format specifications for compost and soil mixes, plus procedure for effective installation of soils
  PDF | Word
• Video: Common Senses: How to Tell if Compost is Good

Meeting soil improvement requirements

• Brochure: King County's Post Construction Soil Standard required for all new landscape construction
• King County Permits
• Compost and Topsoil Calculator, calculate volumes of compost and topsoil needed to meet the Post Construction Soil Standard
• Creating a Soil Management Plan and Calculations Required for Permit Applications
  Video | PowerPoint

Relevant policies for public agencies

• Washington State Law (RCW 43.19A)
  Use of compost products in projects (RCW 43.19A.120) and Cities and counties required to adopt a compost procurement ordinance – Report (RCW 43.19A.150)
• King County's Re+ Plan
  In the face of our current environmental challenges, we can't afford to continue wasting finite resources. A systemic shift is needed to transition from a linear "throwaway economy" to one that prevents waste and makes better use of valuable materials.
• King County's Organics Market Development Plan (2019)
  As requested by the King County Council, the plan submitted by the Executive to expand and enhance the regional market for compost that is produced using the county's organics stream.
• King County Strategic Climate Action Plan
  A five-year blueprint for County action to confront climate change, integrating climate change into all areas of County operations and its work in the community.
• King County Comprehensive Solid Waste Management Plan
  Sets strategies for managing solid waste in King County over the next six to 20 years. Recovering organic material is an essential part of reaching this plan.

Other resources

• King County's Value of Organic Amendments: Ecosystem Services (2024)
• King County's Organic Materials Management Report (2019)
• King County Loop Biosolids
• US EPA's Environmental Value of Applying Compost
• WA Department of Ecology's Compost 101
• Washington Organics Recycling Council (WORC)
• US Composting Council (USCC)