Talking Compost with Napa's Public Education Manager Tim Dewey-Mattia

Talking Compost with Napa's Public Education Manager Tim Dewey-Mattia

Napa Recycling and Compost Facility, located in American Canyon near Napa, California, is a state-of-the-art facility with the most up to date technology for the composting sector. Composting began there in 1997 for the wine industry, mostly taking grape pomace, seeds and stems from vineyards as well as yard waste.

Over the years, Napa Recycling and Compost has expanded and most recently added an aerated static pile system, which uses a system of air tubes to aerate the compost which helps reduce emissions and allows for better odor control.

World Centric Zero Waste Manager Lauren Olson recently spoke with Tim Dewey-Mattia, the Public Education Manager at the Napa facility about their operations and the challenges of running a recycling and composting facility.

Quick Facts

  • The Napa facility began taking compostable yard waste mostly from valley wineries in 1997 and started accepting food waste and compostable packaging in 2014.
  • They take in 100,000 tons of organic material a year, and currently make and sell 30-40,000 cubic yards of compost.
  • Their compost is sold to soil yards, used for agriculture like vineyards, vegetables, almonds, and cannabis growers in the area as well as schools, community gardens, and individuals who buy compost for their home gardens.
  • One of their major challenges is contamination, from plastics, glass and chemicals. They work to educate customers, but also have processes in place to deal with contamination.
  • In order to cut down on contamination, they support universal labeling of compostable products.

Tell us about your background — how did you get involved with composting?

I’ve been composting from an early age. My mother had a big garden and compost pile where we composted yard waste and food scraps in rural New Jersey. In college, I worked on my college recycling program, picking up and sorting recycling from the dorms. After I graduated, I moved to San Francisco, did AmeriCorps, and worked for a few nonprofits focused on recycling and waste management. But I didn’t specifically work on composting until I joined Napa Recycling in 2005.

Can you tell us about the history of the Napa Recycling & Composting facility and what types of systems you use?

The Napa Recycling and Composting Facility has been in its current location in American Canyon, south of the city of Napa, since 1993. Composting started in 1997 with grape pomace (the seeds and stems from the wineries), as well as yard waste. In the last few decades, our composting operation expanded to include food scraps and compostable packaging. The City of Napa owns the facility, but we are a privately owned business, Napa Recycling and Waste Services, contracted to operate it as a public-private partnership. We previously used an open windrow system, and in early 2020 we opened our aerated static pile systems to process material using the highest and best technologies.

How much compost do you produce in a year, and what grades/certifications do you have?

In all, we are processing about 100,000 tons of organic material a year, and that figure includes wood – which is not composted. About 60,000 tons of material is composted, but about half of that is lost due to evaporation (due to high water content) and some screening of materials we cannot take. This year we are hoping to make and sell 30,000-40,000 cubic yards of compost. Our compost is sold in bulk and has the CDFA, OMRI, and US Composting Council’s STA certifications.

Who are your major customers?

Our compost ends up in a lot of different places. It goes to blenders that use it at soil yards, often for landscaping. Another big use is in agriculture – we have wine, vegetables, almonds, and cannabis growers in the area. We also have schools, community gardens, and individuals who come and buy compost for their home gardens. We are fortunate to have a good market for our compost.

"Compostable products help us get access to more food scraps, whether that is a compostable container or bag to collect material at a restaurant, party, concert, or a special event."
Tim Dewey-Mattia, Napa Recycling & Waste Services

What are some of the challenges with composting?

One of our biggest challenges for all composting operations is to get the necessary permits and have the proper environmental controls. We worked to expand our composting operation to our new aerated static pile system, and it was challenging to get the air permits, both in cost and to have the due diligence to get them.

The other major challenge is contamination, from plastics, glass, chemicals, and other strange things. We educate our customers, but also have processes in place to deal with contamination. We have a de-packager machine that removes organics from packaging and a sort line to remove items physically.

We’re always worried about plastic, glass, PFAS, herbicides, and other potentially persistent chemicals that would not break down. Some people put bricks, rocks, pipes, tennis balls, soccer balls – anything in their yard, into the yard waste bins. On the front-end, the more you can remove these items, the better the product is, and the less you are dealing with these types of contamination, the better the product.

We realize, especially when you are adding compostable products, there will be some confusion about additional plastics. If you grind in that plastic, it’s going to be really hard to remove. That’s why we do all we can to remove contaminants at the beginning of the process or not get them at all.

Is the main reason you had the de-packager unit for the power shutoffs in California?

Yes, partly because we deal with a lot of disasters, but we get materials from grocery stores regardless of power outages, as they have expired or spoiled products. We also get industrial food from manufacturers, such as entire batches of food that do not meet specifications, and can end up with loads of one type of product. We can recycle the package if it's rigid plastic, metal, or glass, such as beer, juice, or canned food. Otherwise, if it's a mixed plastic film, then you end up throwing away the residue packaging after you get the food scraps to the compost.

Are there challenges to supporting composting with your customers in the current pandemic? Have you seen a change in the materials coming into your facility?

We’ve seen a massive increase in residential yard waste, partly because it is spring, but also people are home working on their property. We have seen a huge decrease in commercial food waste because of all the restaurants, resorts, and hotels being shut down. We still see food from grocery stores at about the same rate. Operationally, it hasn’t really changed as we can mix in the food scraps from our residential program with the yard trimmings.

What keeps you going on composting – what do you see as the benefits of composting?

Recycling has been such a downer for the last few years. Recycling is still good to do, and we should keep doing it, it’s just been tough with China buying less material. There have been a lot of questions about plastics and which are actually recyclable, so in some ways, composting is a simpler message. Your carrot peels don’t have a number printed on them like plastic. If it was living, then it can go in the compost. Also, composting is closed-loop in the region, the compost is made here and then put back into the soil to grow more food. Composting also has incredible benefits for climate change by reducing greenhouse gas production from organics in landfills. The State of California has strong regulations about composting and it will be even more important in the next decades as a tool to fight climate change.

Does your facility accept World Centric compostable products? If so, how have you adapted your process to be able to accept them?

We didn’t have to adapt the process that much. I think what’s important is having a preprocessing system because you have to be able to size reduce or grind them up. This is for anything - you can’t accept a pizza box whole, it would take forever to compost. It’s the same for a fiber plate or any other compostable packaging product. Once it is ground up, you can mix it with high nitrogen material like food scraps.

The important thing is not to get plastic or non-compostable lookalike products. We have found that products that are certified compostable by the Biodegradable Products Institute (BPI) do break down in our system, that’s why the BPI certification is important to us. It also allows us to tell customers what to purchase.

Compostable products help us get more food scraps, whether that is a compostable bag to collect material at a restaurant, party, concert, or special events. At those locations, they can just put all the food scraps with the compostable products and divert organics from the landfill.

Is there anything that World Centric or our customers can do to help composting facilities such as yours?

We’re also trying to be sure that we don’t get contamination, so labeling is important. We would love to see universal labeling, not just with World Centric but the entire industry of compostable products. We know there are challenges, but it’s something that we’re always going to push for.

I think there is also the importance of regulations eventually at the national level that, if it’s not compostable or reusable, it shouldn’t be used for single-use packaging. Some items will probably always be recyclable like cardboard boxes, plastic bottles, and metal cans. But I’m more concerned about single-use plastic items like forks, film, and other plastics that are difficult to recycle.

What's the best way for people to advocate for commercial composting in their own city?

In California, universal composting access is required by 2022 - so if it’s not happening yet in your city, talk to your local haulers, facility operators and city staff to get a sense of when it will start. But even if you aren’t in California, composting access is extremely critical to your community. What I’d recommend is talking to your local haulers and city recycling/solid waste staff to get a sense of why it’s not happening, and what can be done to get it started. Then, work with community groups, businesses, residents, local environmental advocates, students, teachers, and local composting facilities and contact your elected officials to let them know why composting is important, and that you support local access. Composting offers a lot of simple, compelling benefits - GHG reductions, adding nutrients back into the soil to grow food, local green jobs, etc. - and educating your community on this knowledge is critical to your success!

Key Takeaways for the Consumer

  • Yard Waste Bin is for Organics Only: Many people throw away anything in their yard like concrete, rocks and sports equipment which have to be removed before composting.
  • Look for the BPI Logo for Compostable Products: There are many lookalikes in disposable packaging, so be sure to look for the BPI Certification before putting an item into the yard waste bin.
  • Composting Helps the Environment: Composting has incredible benefits for climate change by reducing greenhouse gas production from organics in landfills.
  • Use a Compostable Bag for Your Food Scraps: Plastic bags gum up the system and have to be removed.
  • For more information see this informational video produced by Napa Recycling and Compost Facility.


Written by

World Centric


Read time

11 minutes


Published on

May 5, 2020


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