The City of Napa’s contractor, Napa Recycling and Waste Services, had for years been composting mostly yard wastes using a simple static pile composting process. The City wanted to upgrade its compost facility to process more yard waste along with the addition of food waste and digestate. The system had to comply with the rigorous permit conditions required by the Bay Area Air Quality District and the California Water Board. The City wanted a robust system that would minimize fugitive odors and be capable of composting 50% additional feedstocks once their permitted amount was increased.
ECS, a Seattle based company, visited the zoo and worked with the zoo staff to design their new compost facility in an existing and irregular shaped area. The process design is a Covered Aerated Static Pile (CASP), with positive aeration, CompTroller aeration design and monitoring, and a Low Friction Trench (LFT) aeration floor. There are four (4) primary zones (~200 yd3 each) in a bunker-wall configuration with a 26-day retention; and three (3) secondary zones in a mass-bed configuration.
Biosolids and Yard waste
ECS Technologies Employed
Aerated Static Pile System
CompTroller™ Automated Control & Monitoring System
2004, CompTroller™ Upgrade in 2017
Port Angeles, WA