Colorado’s largest compost manufacturer says there’s too much contamination in its organics stream. What does that mean for the future of Boulder’s curbside program?

Boulder is among a relatively small group of U.S. cities that require a subscription to a curbside compost service that accepts food waste and compostable packaging. Now, for the first time in the program’s 13-year history, its viability is being threatened by contamination in the organics stream. 

Composting is the process of recycling organic waste and turning it into a finished product that is used to fertilize soil. It’s a great way to reduce food waste — the equivalent of 33 million pizzas a year is wasted in Boulder each year, enough to feed nearly 20,000 people — and slash landfill methane emissions. In 2020, the city of Boulder collected about 11,500 tons of compostables, about a fifth of the city’s total waste. 

But even a few troublesome guests like a broken glass bottle or a rubber glove can spoil the bunch, compromising the quality of the compost or making it unsafe for consumer use. 

A1 Organics, Colorado’s largest compost manufacturer, says the current level of contamination in its organic recycling stream is unsustainable and it is threatening fines. As a result, Western Disposal, which hauls Boulder’s organics to A1 Organics’ facilities, is warning customers it may no longer accept overtly contaminated loads, and says the ongoing problem is “threatening the program’s very existence.” 

Western Disposal offers residential composting in the City of Boulder, the Town of Lyons and unincorporated Boulder County. Commercial composting is offered more widely across the county.

“Right now, we do need to start rejecting loads that have high levels of contamination,” Clinton Sander, A1 Organics’ marketing manager, told Boulder Reporting Lab. He said he did not have any figures on the degree of contamination in the loads. 

“If a load comes in with a smashed bottle and there’s a few other bottles smashed in, there’s 100 pieces of glass then. We’re going to have to reject that load.” Rejection would mean A1 Organics would charge Western Disposal to dump the load in a landfill instead. 

Closer examinations, and possible rejections, began on Aug. 4, according to Sander.

Contamination isn’t just a local problem. “This is a national conversation,” says Sander. As more municipalities across the country emphasize the importance of composting, there will be more of these conversations about how to keep the organics stream clean. 

A1 Organics’ warning prompted Western Disposal to release a stern message of its own for its Front Range customers, citing “compostables stream[s] coming from both residents and businesses, polluted with everything from household trash to disposable gloves and a dizzying array of plastics.”

Kathy Carroll, Western Disposal’s community relations manager, told Boulder Reporting Lab their drivers are now inspecting bins for clear signs of contamination upon pickup. This is a change from their previous policy, which only involved inspecting truckloads once they arrived at Western Disposal’s facility.

Carroll says a truck driver may contact their dispatch team if they notice a compost bin has too much visible contamination. The dispatch team will reach out to the customer to give them a chance to remove the contaminants. “The customer has the opportunity to clean up the stream. Or we can send a trash truck, which incurs a fee.” 

Carroll said fees will depend on service levels, but did not offer specific figures. “Contaminated compostables are charged as extra trash and the rate is calculated based on the level of service to which the customer subscribes and whether the material is commercial or residential waste,” she wrote in an email to Boulder Reporting Lab. 

So, what goes in the compost bin?

Western Disposal’s statement advised composters to err on the side of caution when determining what should go in the compost bin: “When in doubt, throw it out.”

Sander from A1 Organics also offered some composting counsel. “If it was alive in your lifetime, then it’s probably safe to put in the compost bin,” he says. “Remove food stickers [from fruit and vegetable scraps] … and don’t put any hard plastics in there.” 

In the wake of Western Disposal’s warning, the City of Boulder is reminding residents of its composting guide published in a news release earlier this year, emphasizing basic steps like not composting pet waste or plastic bags, and recycling milk and juice cartons. 

Though disposable packing may advertise itself to be “compostable” or “biodegradable,” it may not necessarily be compostable in many composting facilities. Residents should check A1 Organics’ list of acceptable compostable products to be sure a given plastic cup or straw can be composted by A1.

Though looking up brands of biodegradable products may not be how most people would choose to spend their time, Sander says composting is a vital ecological process. k“We call organics ‘green waste’ or ‘food waste,’” he said. “But really, it’s not a waste. It’s a natural resource.”

Correction: An earlier version of this story described curbside compost services in Boulder as being “municipally run.” The city does not provide municipal waste hauling and composting services. Instead, trash, compost and recycling services are offered by several local waste hauling companies, including Western Disposal.