Washington State University Aerated Static Pile (ASP) Composting SystemInstallation: July, 2007 Green Mountain Technologies installed a 12,000 ton per year Aerated Static Pile (ASP) composting system for Washington State University (WSU) in 2007. The 90’x120’ pad was added to reduce odors and expand capacity for their existing windrow operation. The pad is divided into 12 zones with 300 cubic yards of compost on each zone. The facility takes in Ag waste and food waste from the research farms and campus and composts it creating two products: sterile bedding and compost for landscaping.

The ASP process requires no turning and less land area than windrows. The feedstocks are blended in a stationary mixer and water added to create a compostable mix prior to loading on the ASP pad. Then the material is stacked on top of perforated pipe sucks air down through the pile to maintain aerobic conditions and blown through a biofilter to minimize odors. Air flow is regulated by computer controller and dampers to maintain sterilizing temperatures. The cost of the ASP equipment was less than $200,000 and was installed in 3 days.