King County, Washington – Compost Procurement

King County, Washington, has long been recognized as a leader in environmental product procurement in the country. King County Code (KCC) § 10.14.050 mandates public agencies to purchase sustainable products and implement environmental strategies that meet specific stringent standards. The King County Sustainable Purchasing Program (SPP) (formerly called the Environmental Purchasing Program (EPP)) was first implemented in 1989 in an effort to reduce ozone depleting landfill waste and incentivize a sustainable local economy. In 2018, the Sustainable Purchasing Ordinance further codified requirements for the SPP in addition to mandates on a Green Building Program, Electric Vehicle Program, and Strategic Climate Action Plan.

The SPP requires all local government agencies to purchase “sustainable products and services that provide environmental, social, and economic benefits,” including compost and shredded wood waste, and complements the 2005 King County Post-Construction Soil Standard. The SPP policy became official regulation through the passage of legislation in 1995 (Document Code: CON-7-1-2 (AEP) (superseded by CON-7-1-3-EP). Today, King County Code and agency procurement policies continue to bolster a market for regional compost production through preferential purchasing of local compost.

King County’s Wastewater Treatment Division (WTD) and Roads Division, in particular, have been at the forefront of implementing compost procurement policies among the county’s public agencies. According to Karen Hamilton, the Environmental Purchasing Program Manager for King County’s Procurement and Contract Services, “the county’s three wastewater treatment plants produce lots of biosolids, some [of which] are turned into compost called Groco, since rebranded as Loop. Whenever WTD does a construction project, they use the biosolids compost.” Additionally, the Roads Division buys local yard waste compost from a company called Cedar Grove. “Because we buy compost in bulk,” says Hamilton, “it only makes sense to source a local product.” King County’s compost is produced by composting woody material with Loop (the organic material made by recycling food and human waste at their wastewater treatment plants.)


Evaluating Product Sustainability

Since the beginning of King County’s purchasing policy in 1989, the means of calculating an item or action’s environmental impact have come a long way. Toolkits for estimates of environmental impact now include environmental benefit calculators and sustainability certification processes. King County’s procurement program uses such tools and its website offers numerous resources on guidance materials for determining and quantifying the sustainability of a potential purchase.


Policy Language and Procurement Specifications

King County strives to choose compost-amended topsoil and biosolids-derived products while avoiding conventional soil with no compost additives. Accordingly, King County’s compost use and procurement is governed by several local and state policies, as follows:

  • King County’s Sustainable Purchasing Executive Policy (CON-7-22-EP):
“8. Agencies are required to purchase the specific goods and services below and use the following strategies:
28. Biosolids compost; (KC 28.86.090);”
  • King County Code 28.86 – Wastewater Treatment
“28.82.080  Biosolids.  Biosolids means primarily organic solid products produced by wastewater treatment processes that can be beneficially recycled. (Ord. 11034 § 3 (part), 1993).”
“28.86.090  Biosolids policies (BP). (formerly Ordinance #13680 from 1999)
1. Policies.
BP-1:  King County shall strive to achieve beneficial use of wastewater solids.  A beneficial use can be any use that proves to be environmentally safe, economically sound and utilizes the advantageous qualities of the material.
BP-2:  Biosolids-derived products should be used as a soil amendment in landscaping projects funded by King County.”
“GHG 5.7.2 Build markets for compost and other recycled content materials.”
“GHG 5.1.2 Deliver regional organics plan.”
“GHG 6.2.5 Explore compost benefits.” 
  • Washington State RCW 43.19A.120 – Use of Compost Products in Projects
“(1) When planning government-funded projects or soliciting and reviewing bids for such projects, all state agencies and local governments shall consider whether compost products can be utilized in the project.
(2) If compost products can be utilized in the project, the state agency or local government must use compost products”
E-457 King County agencies shall use recycled organic products, such as compost, whenever feasible and promote the application of organic material to compensate for historic losses of organic content in soil caused by development, agricultural practices, and resource extraction.”

King County strives to achieve zero waste by 2030, as established in King County Code 10.14.020 and in the 2020 Strategic Climate Action Plan (SCAP), and has, accordingly, recently renewed its focus on organics recycling and building sustainable compost markets through public procurement. In 2019, King County approved the Organics Market Development Plan, which intends to expand and enhance the regional market for compost produced within the county. In order to execute the expansion of compost use in government operations, King County established a technical assistance program called CompostWise that supports both County agencies and regional jurisdictions on projects that incorporate the use of compost. 

The Reducing Greenhouse Gas Emissions section in King County’s 2020 SCAP lists “Building markets for compost and other recycled contents” (GHG 5.7.2, p.150) as a priority action in their Sustainable Purchasing Category. This strategy also establishes King County’s use of compost in pilot projects starting in 2020 through 2025 and the establishment of a baseline measurement of compost’s carbon sequestration potential by 2021. 


Policy Outcomes

From an economic perspective, early successes were observed, indicating savings by turning away from conventional products and toward locally-sourced, environmentally-preferable products, such as compost. For example, in 2007, King County reported a total savings of $875,000 compared to the cost of conventional products; the most recently available Purchasing Program report from 2013 shows an increase to $2.6 million in savings. The same report stated a reduction of 1.3 million metric tons per year of greenhouse gas emissions.

In addition to greenhouse gas emissions savings from purchasing sustainable products, King County also encourages the application of Loop biosolids on farms and forested land. Using Loop compost as a soil amendment offsets the need for synthetic fertilizers while simultaneously fostering plant growth.

The County’s environmental purchases also serve to incentivize future development of a regional closed-loop composting infrastructure with increasing cost savings and environmental benefits for the county.


More Information

Original post from July 30, 2012
Updated August 17, 2021

Follow Brenda Platt:
Brenda Platt

Brenda Platt directs ILSR's Composting for Community project.

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Sophia Jones

Sophia Jones is an Intern with ILSR’s Composting for Community project. She is passionate about sustainability at all levels and has previously worked with the United Nations, the Government of Barbados, and Plant NOVA Natives on various sustainability-related projects.