AMERICAN CANYON -- The garbage collector for Napa and unincorporated areas of southern Napa Valley is putting the finishing touches on a new master plan for its main recycling and composting facility at the end of Tower Road, adding reuse of water, conversion of waste to wattage and reduction of compost gas emissions.
[caption id="attachment_59063" align="alignright" width="405" caption="The food-waste composting program at Napa Recycling & Waste Services has been increasing in the past two years."][/caption]
Those projects are all part of intertwined efforts to hit city and state targets for reducing greenhouse, noxious and diesel engine emissions; trimming the tally of trash ending up in landfills and keep more rainwater and treated process waste water on site, according to Greg Kelley, general manager of Napa Recycling & Waste Services and Napa County Recycling & Waste Services (707-255-5200, naparecycling.com). The estimated cost for all the upgrades is about $20 million.
"After 18-plus years, things have changed and regulations have changed and (waste) processing has changed," he said. "It is costly, but it is a long-term investment, because we will always have yard waste."
The city of Napa hired engineering consulting firm CH2M Hill to evaluate what needs to be done to the 20-acre site to get it up to the latest air-and water-quality regulations. That report is due back to city officials shortly so the master plan can be completed in mid-August.
One change to the existing site master plan is different handling of stormwater. Currently, all rainwater and process waste water is collected in three basins that allow problematic particulates and other compounds to settle out to clean the water before it is discharged.
[caption id="attachment_59064" align="alignleft" width="350" caption="Part of the proposed project at the composting facility is to use a reverse-air system that would reduce emissions of volatile organic compounds."][/caption]
The latest state stormwater rules are still in draft form but have been trending toward keeping most rainwater on a property through various means.
Another planned change to the plant is designed to improve air quality during composting operations. As bacteria break down food and plant waste during composting, the microorganisms release greenhouse gases, volatile organic compounds (VOCs), reactive organic gases (ROGs), dust and ammonia into the air. Yet, composting also cuts down on the odor, pathogens and bulk of rotting organic material as well as locks carbon into the cell structure of the microbes, so composting can help the state meet its GHG-reduction goals, according to the California Air Resources Board.
So being considered for the plant upgrades are a reverse air circulation system that would suck air through the compost, pulling any gases into a pipe and filter, according to Mr. Kelley. The intent is to remove 95 percent of the VOCs emitted.
"Compost, in general, uses water and air to get heat to activate the bacteria," Mr. Kelley said. "We have blowers blowing air through the piles, so we don't have to turn them manually, like most compost operations. With current food-waste collection, forced air is the easiest to adapt to."
The combination of blowing air and covering the piles with finished compost helps trap odors in the piles, he said.
The operation has been experimenting with food-waste recycling for the past year and a half, but collection of such scraps from commercial customers is just getting started, according to Mr. Kelley. Currently, the company has more than 60 commercial food waste customers, but the service area could yield 300 to 400 commercial accounts.