The hidden plastic problem in composting–and how to fix it.
Written by: Alexandra Cuschieri, Zero Waste Campaign Coordinator.
Composting has become second nature for many of us in Whistler, whether through Strata or dropping off food scraps at the Nester’s or Function Junction depots. But have you ever wondered what happens after those scraps leave your kitchen?
The journey leads to Sea to Sky Soils, where food scraps are transformed into high-quality compost through a carefully controlled process. Over time, the scraps break down into nutrient-rich soil, used to regenerate local agricultural lands and reduce dependence on synthetic fertilizers. It’s a closed-loop system—waste turned into a resource, keeping nutrients cycling within our local environment, and feeding the land that sustains us.
High-quality compost heap made from green waste
High-quality compost loading directly into a truck heading for a local organic farm
When done right, composting supports healthy soils, thriving farms, and a more sustainable Whistler. However, this success story is being compromised by an increasing problem: plastic contamination.
The hidden contaminants in our compost
Composting should be one of the simplest ways to reduce waste and regenerate soil. But a visit to Sea to Sky Soils reveals a troubling sight—plastic cups, food packaging, shredded plastic bags, and even a doll’s head. Compost piles are filling up with contaminants, potentially polluting the very soil that may one day grow our food.
Jon, Operations Manager at Sea to Sky Soils, points out a green plastic bag that can easily be mistaken for compostable material:
“People see green and assume compostable—it’s not.”
We may assume that if something is biodegradable or “looks compostable,” it belongs in the organics bin. But composting isn’t a magical process where food scraps vanish into rich, dark soil. It’s a biological process that only works when the right materials go in.
If we feed the system the wrong ingredients, we don’t just get compost—we get microplastics, chemical residues, and contamination that lingers in our environment.
Many of us are aware of the issues caused by plastic pollution. While we can’t control everything, we can control what we put in our compost bins.
“One of the most frustrating contaminants is produce stickers,” says Jon. “They shrivel up in the compost piles, slip through filters, and ultimately become part of the compost.”
Produce stickers seem harmless, but like all plastics, they don’t break down—they break up into smaller microplastics that remain in our soil for thousands of years.
And it’s not just plastic bags and stickers. Milk cartons, takeout containers, and food packaging are often thrown into compost bins still filled with food, perhaps under the assumption that it will be dealt with accordingly.
But that’s the thing about a closed-loop system: what we throw away doesn’t just disappear. The compost made from our organic waste is used in landscaping, parks, and even food production. What we put in, we get back out. When we contaminate our compost, we’re contaminating our own environment.
Compost isn’t a landfill – So why do we treat it like one?
Sea to Sky Soils works tirelessly to turn Whistler and Pemberton’s organic waste into high-quality compost, but plastic contamination makes the job difficult and resource-intensive. Pulling out a shriveled Philadelphia cream cheese package, still intact, Jon tells me:
“People think we can just pull the plastic out and recycle it. But by this point, it’s dirty, mixed with other plastics, and ultimately ends up in the landfill.”
Removing plastic from the system is a labor-intensive process that requires significant resources. Every non-compostable item that enters the system risks polluting the soil we depend on.
A temporary pause—But an opportunity to improve
For years, Sea to Sky Soils has transformed Whistler’s food waste into nutrient-rich compost, closing the loop on organic waste and supporting local agriculture. But right now, that process is on hold.
Due to contamination and necessary infrastructure upgrades, Sea to Sky Soils has temporarily paused accepting food waste. While this may seem like a setback, it’s actually an opportunity to reset our habits and ensure that going forward we are supporting, not sabotaging, the system.
Mindful choices can ensure that composting remains a powerful tool for regenerating our soils, supporting our community, and reducing waste—not another pathway for plastic pollution. A little extra effort now means a cleaner, healthier future for Whistler and beyond.
What you can do right now:
Continue using Whistler’s compost system as usual. Food waste is still being collected and composted—just at a different facility.
Before tossing something into the organic bin, take a moment: Does it contain plastic? If yes, leave it out.
Can you remove a contaminant? Take stickers off produce and avoid “compostable” packaging unless it’s BPI-certified.
These items can go in your compost bin:
✅ Any food items (dairy, fruit, vegetables, meat, seafood, bones, eggshells)
✅ Used coffee grounds and tea bags
✅ Food contaminated paper like a pizza box
✅ Small amounts of used cooking oils if soaked up with paper towels
✅ Compostable packaging if BPI or BNQ certified compostable to ASTM D6400 standard.
Please leave these out:
❌ Produce stickers, labels or twist-ties
❌ Plastic food packaging (butter/spread tubs, salad bags)
❌ Milk cartons
❌ Caddy liners made from anything other than BPI-certified compostable material
❌ Takeaway food packaging of any sort (unless specifically labelled BPI-certified compostable)
❌ Thin plastic wraps/cling film on items such as cucumbers or cheese
❌ “Biodegradable” packaging. This has no standard definition and does not mean it will compost.
As always: if in doubt, leave it out!
Good to know:
- Clean paper (like newspaper) should be recycled, not composted.
- Any compostable cups or packaging should be clearly identified as certified. The common standard for these is ASTM D6400, and the certifying bodies are BPI or BNQ.
- For readers in Squamish: no compostable packaging is accepted. Squamish food waste produces organic certified compost for use on organic farms, which cannot include compostable plastics.
- We will be distributing free BPI-certified compostable caddy liners and kitchen caddies at our workshop at Whistler Library on May 6th at 6 PM.
