King County, Washington – Compost Procurement

Date: 15 Aug 2016 | posted in: Composting, environment, waste - composting, Waste to Wealth | 0 Facebooktwitterredditmail

Surveying the local level of US politics, one finds that King County, Washington, has one of the best environmental product procurement programs 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 Environmental Purchasing Policy (EPP) was first implemented in 1989 in an effort to reduce ozone depleting landfill waste and incentivize a sustainable local economy.

The EPP requires all local government agencies to purchase “environmentally preferable products whenever practicable” including compost and shredded wood waste, and complements the 2005 King County Post-Construction Soil Standard. The EPP policy became official regulation through the passage of legislation in 1995 (Document Code: CON 7-1-2-AEP). 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 composting 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, recently 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.”


Policy Language and Procurement Specifications

King County Code 28.86.090 – Biosolids policies (BP), (formerly Ordinance #13680 from 1999):

A. Explanatory material. The biosolids policies are intended to guide the county to continue to produce and market class B biosolids. The county will also continue to evaluate alternative technologies so as to produce the highest quality marketable biosolids. This would include technologies that produce class A biosolids.

B. 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.

Furthermore, King County Contract specifications for many Solid Waste Division and wastewater treatment projects will mandate the use of 100% Groco, as noted in the following excerpt:

2.1 MATERIALS E. Compost

A maximum of 35 percent by volume of other approved organic waste and/or biosolids may be substituted for recycled plant waste.”


A. Compost for turf and groundcover: 1. 100 percent Groco, manufactured by Groco and distributed by Sawdust Supply, 15 S. Spokane Street, Seattle Washington, (206) 622- 5141.

B. Compost for pocket plantings 1. 100 percent Groco


Evaluating Product Sustainability

Since the beginnings 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 Outcomes

From an economic perspective, the county is saving money and even seeing annual savings growth by turning away from conventional products and toward locally sourced, environmentally preferable products, such as compost. In 2007, King County reported a total savings of $875,000 compared to the cost of conventional products; the County’s savings have since increased to $1.8 million in 2012 according to a Purchasing Program report from that year.

As anticipated, the EPP has been extremely effective from an environmental and public welfare standpoint as well. According to the 2011 Annual Sustainability Report on King County’s “Climate Change, Energy, Green Building, and Environmental Purchasing Programs,” a total of 832,000 tons of recyclable and compostable materials were diverted in 2010, which was up 2% from 2009. Using an EPA model, the county further reports that its recycling and composting practices reduce greenhouse gas emissions by approximately 1.62 million metric tons per year. The county’s environmental purchases also serve to incentivize future development of a regional closed-loop composting infrastructure with increasing of cost savings and environmental benefits for the county.

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. By using Loop as a soil amendment to offset the need for synthetic fertilizers while simultaneously fostering plant growth, the County estimates it achieved a reduction of around 39,000 metric tons of carbon dioxide equivalent of GHG emissions in 2013.


More Information

Original post from July 30, 2012
Updated August 15, 2016

Brenda Platt
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Brenda Platt

Brenda Platt directs ILSR's Composting for Community project.