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Unused fireworks/flares - Keep out of Landfill via Special Program:
Do NOT place unused fireworks/flares in the trash or recycling bin
.  Fireworks and flares are extremely dangerous and must be disposed of properly. You must arrange for drop-off in advance by calling the Rhode Island State Fire Marshal's office (401) 889-5555.

- or - 

Used fireworks/flares - Trash:
After use, let it sit for 10 to 15 minutes before picking it up. Place used fireworks and flares in a 5 gallon bucket of water to soak for 24 hours. Put wet fireworks and flares in a bag. This item is then safe for disposal in your regular trash.