Paper coffee cups are compostable in PEI.
It is true there is a very thin polyethylene liner on some cups. This plastic residue and other similar contaminants are screened out during compost production. The paper fibers are excellent sources of carbon (which is necessary to produce compost).
Islanders should be aware that our facilities may be quite different than some in other jurisdictions and sorting practices differ from place to place. We are an Island with only one landfill, therefore, diverting as many resources through composting and recycling helps to extend the life of our landfill. There are a lot of paper cups being disposed of on PEI, and it makes environmental sense to compost this resource, then transport only the residual screenings to landfill.
Some restaurants serve take-out beverages in cups with a clearly identifiable, bumpy, plastic outside layer. These types of cups are waste. Plastic lids with recycling symbols #1 through #5 are recyclable, and all other plastic lids are waste. Paper lids, new on the market, are also compostable.