Compost Feasibility Study


Zero Waste Vashon is pleased to announce that King County Solid Waste Division (SWD) will be conducting a composting facility feasibility study for Vashon. The following is a project overview provided by Morgan John, SWD project manager:
The King County Solid Waste Division is requesting proposals to study the feasibility of building and operating a compost facility on Vashon Island (publicly or privately owned and operated) to provide local, on-island composting of organics including yard waste and food waste. The project will illustrate costs and benefits of an on-island compost processing facility by considering available organics feedstock, potential composting technologies, co-located or coordinated anaerobic digestion, potential project sites, and expected markets for finished compost. SWD will collaborate with Zero Waste Vashon to develop a relevant scope of work and ensure meaningful results.

The feasibility study will present options for implementable strategies, with economic and greenhouse gas impacts, to manage organics differently from current SWD practices. Results of the study will benefit the Vashon-Maury community and may also serve as a model to other communities in and beyond King County for small-scale organics processing. The study will help the division determine if small-scale composting can support efficiencies in waste hauling and reduced climate impacts.

ZWV has been working for five years to bring a compost facility to the island. These efforts started by demonstrating to King County Solid Waste Division that there was enough volume to merit separate collection of yard waste. In 2016 King County started a yard waste program at the Vashon Recycling and Transfer Station.

The program has been a great success with volumes exceeding predictions. Currently, the yard waste is trucked to the Cedar Grove Compost facility in Maple Valley. That is better than landfilling tons of yard waste, but it is inefficient, costly ($200,000/yr.) and has high carbon emissions due to transportation (over 250 trips) to and from Cedar Grove. An island-based compost facility would eliminate the trips to haul organics off the island and then import them back as compost.  Zero Waste Vashon looks forward to working with King County Solid Waste Division as we continue exploring local composting solutions for Vashon.