Compost and Bioretention Soil
The City of Seattle has mandatory specifications for soil, including compost and bioretention soil, for all City-funded projects within city limits. See section 9-14 of the City Standard Plans and Specifications.
Consistent with "closed-loop" principles, City Council Resolutions 30990 and 31459 as well as the City's Sustainable Purchasing Policy, approved compost sources are products from permitted facilities that compost organic materials generated and collected within the city of Seattle limits. The compost products from these approved facilities must also meet the compost specifications under Section 9-14 of the City Standard Plans and Specifications.