© ronstik / stock.adobe.com

For over 100 years, Napa Recycling & Waste Services (NRWS)—a family-owned hauling, recycling and composting provider—has been a prevalent fixture for residents and businesses in Napa County, California.

With the company’s roots first dating back to 1920 when the original owners started a small hauling business, NRWS has grown significantly over the past century to meet the changing needs of its customers.

A major area of growth for the company has been organic waste handling, which NRWS began the year it was founded by collecting food waste and selling it as hog feed. According to Tim Dewey-Mattia, recycling and public education manager for NRWS, this extensive background in organic waste management set the groundwork for the company’s current organics operations, which have significantly evolved since the implementation of California bill AB-939.

Better known as the California Integrated Waste Management Act of 1989, the law required cities and counties to divert 25 percent of their solid waste from landfill disposal via source reduction, recycling or composting activities by Jan. 1, 1995 and to divert 50 percent of their solid waste after Jan. 1, 2000.

“[California AB-939] was actually what got a lot of yard waste programs going in [the state] because you can get a lot of diversion from yard waste, especially here in California where we have year-round yard waste,” says Dewey-Mattia. “So, in 1993 our company opened a site and was just doing dual-stream recycling at the time and yard waste composting.”

In addition, Dewey-Mattia notes that the wine industry in Napa Valley also played a role in the area’s surging composting industry.

“Because of the wine industry, there’s a lot of grape pomace (the remaining skins, pulp, seeds and stems of the grape), and the wineries and vineyards were having a hard time processing and composting all of it on-site. Before 1989, that didn’t require a permit, but under AB-939, it now requires a permit,” he says.

With a now steady organics waste stream and an already established composting site, NRWS slowly began emerging as the dominant player in Napa County’s organics recycling marketplace over the last couple of decades.

“[Our immersion into food waste] has kind of happened over the last 15 years,” says Dewey-Mattia. “We’ve expanded from just being yard waste and grape pomace to having all kinds of food waste and soiled paper. … We had a composting site already, so, it was easier for us to make these improvements to our facility in order for us to expand out to all the different organics.”

“Every time you open a pile and turn it, you could have potential emissions or odors, and you don’t have that when you have a static pile. Because the material is mechanically aerated all the time as it’s sitting there, it’s actually a lot more efficient.” – Tim Dewey-Mattia, recycling and public education manager, NRWS


To handle this new stream of materials—which included not only food waste, but the assorted packaging and additional contamination that can come with it—NRWS initiated a series of updates and improvements to its current facility.

These updates first began five years ago with the addition of a Bulk Handling Systems (BHS), Eugene, Oregon, preprocessing line, as well as the inclusion of conveyors, screens, presorting lines and electrified grinders. In 2018, NRWS received a grant from the California Department of Resources Recycling and Recovery (CalRecycle) to install a depackager to process food waste packaging and materials from commercial generators that contain plastic bags or other contaminants.

However, Dewey-Mattia says the biggest piece of NRWS’ composting operations has been the addition of its covered aerated static pile composting system (CASP), designed by Seattle-based Engineered Composting Services (ECS), in January 2020.

“Planning and permitting [of the CASP system] took a few years for a couples reasons,” says Dewey-Mattia. “First of all, with air permits and stormwater permits, our old composting system was not going to be able to be used forever. Especially given us adding food waste in, the permitting requirements necessitated us moving to a new technology where we were able to capture greenhouse gas (GHG) emissions and liquids.”

Prior to adopting this new composting technology, NRWS was using standard windrow composting, where feedstock is shredded, mixed and placed into windrows along a nonpermeable surface. The windrows are then turned on a regular basis to improve oxygen content, distribute heat to regulate temperature and to distribute moisture.

According to Dewey-Mattia, the introduction of the CASP system has since saved a significant amount of labor and equipment costs, as well as decreased the amount of emissions from the site.

“Every time you open a pile and turn it, you could have potential emissions or odors, and you don’t have that when you have a static pile,” he says. “Because the material is mechanically aerated all the time as it’s sitting there, it’s actually a lot more efficient.

“As the pile is sitting there with air blowing through it, it means the microbes are getting oxygen and it’s decomposing faster. So, we’re able to process it faster, and it’s a more uniform product because you don’t get little pockets of different amounts of decomposition.”

In addition to the CASP system, NRWS has also integrated a finished compost biofilter on top of the cover to remove additional emissions.

In recognition of these upgrades, NRWS was awarded the 2021 Dave Hardy Leadership in Organics Award by the California Resource Recovery Association (CRRA) for achievements in reusing materials, preventing waste and composting.

As reported by the Napa Valley Register, NRWS and the city of Napa have directly invested close to $20 million into the recycling and compost facility since 2014. These investments include the $2.3 million organics receiving building; $2.8 million organics preprocessing system; $3 million stormwater management system; the grant-funded $440,000 organics depackager, and the $11 million covered aerated static pile composting system.

According to a press release announcing the award, the facility upgrades have directly resulted in roughly 10 percent less residential trash being sent to the landfill and 22,000 more tons of waste being composted over the last seven years.

“Because of these upgrades, we have a really great state-of-the-art system that can handle all types of organics, which means we can divert all of this additional material from the landfill,” says Dewey-Mattia.

Photo courtesy of Napa Recycling & Waste Services
NRWS has been serving the waste needs of area citizens and businesses for more than 100 years.


Since becoming operational last year, NRWS’ completed composting system is processing roughly 100,000 tons of organics annually and has reduced overall air emissions of the facility by over 90 percent.

Of the organics the facility processes, Dewey-Mattia says NRWS produces roughly 20,000 tons of compost annually to be sold across the region.

“The markets are pretty diverse in our region. Some of it goes to agriculture—whether it’s wine grapes, trees or other fruits and vegetables—and cannabis is actually a buyer. However, our biggest market is commercial landscaping and home garden use,” he says. “We’re typically busy this time of year, right after the harvest [in the fall]. So, we sell out most years.”

Now that NRWS has been running its upgraded composting operations for almost two years and has proven the technology is effective, the company will soon have the opportunity to compost more on-site.

“We’re trying to get some more machinery to be able to screen our overs a little bit more, which is like the woody stuff that didn’t break down or any kind of garbage that might be in there,” says Dewey-Mattia. “We have realized that we could screen that material a little bit more and make some mulch products that are more wood-based. So, we’re constantly looking at additional markets to be able to make more product.”

NRWS is also currently building a similar composting system as in its Napa facility at the Yolo County Central Landfill in Woodland, California, that will handle material from the Sacramento Valley and surrounding regions.

The author is the assistant editor of Waste Today and can be reached at hrischar@gie.net.