CLEVELAND (AP) — Cleveland is ready to cite residents for improper recycling to address the growing problem of contaminated recyclables.

The city’s citation program begins Wednesday after several weeks of courtesy warnings.

Residents could face small fines for mixing trash with recycling, excess waste outside of recycling bins, and setting bins out too early and failing to retrieve them after recycling pickup has passed.

Cleveland.com reports plastic bags and disposable coffee cups are some of the improper items most frequently placed in recycling bins. The news site says plastic polyethylene lining in the cups makes them hard to recycle.

Containers with food residue and greasy pizza boxes also are prohibited, though the top of a pizza box can be torn off and recycled as long as it’s not greasy.