Capacity (TPY) Permitted
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 designed and supplied a 20 zone positively aerated, bio-layer covered aerated static pile system (CASP). The zones are arranged in four 5 zone “fan groups,” each of which is aerated with a single large, high efficiency fan. Sparger pipes are embedded below the concrete aeration floor to uniformly distribute air. In addition to controlling the airflow to each zone and logging comprehensive process data, the CompTrollerTM controls pile surface irrigation systems that further reduces emissions. ECS also provided extensive technical support throughout the long permitting process.
The City of Napa and Southern Unincoporated Napa county serve 30,000 households. A mandatory organics collection program directs both residential and commercial organics to the facility, which accept a range of green and yard waste, as food items (meat/bones, vegetables, dairy, food-soiled paper, coffee grounds, etc). Film plastics tend to represent the majority of the contamination rates.
The pre-processing line removes much of the contamination before it enters the process. A depackaging machine also handles high volumes of expired, spoiled or off-spec food and source separated organics. An electric shredder reduces large particle size.
The finished compost is OMRI listed, USCC STA Certified, and approved by the California Department of Food & Agriculture. NRWS sells the compost directly to the public and agriculture, and provides it to local community gardens. In addition to education programs and municipal partnerships – the ability to create a high quality finished product plays a key role in the operation’s success.
For the past ten years ECS has provided reliable, knowledgeable and professional services and equipment for Napa Recycling’s organic processing business. Greg Kelley Managing Member, Napa Recycling & Waste Services
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