Here's a better idea--several times in the past few years our club (meaning ME!) set up a Flare Disposal/Demo Day. I picked a location on the bank of the Columbia River, set the date, notified the CG, local fire and police and printed up fliers to post in the boat stores and sporting goods stores. The fire dept even had an ambulance on standby at our location in case of an injury.
It was done in the day time and we had buckets of water to dispose of the flares that had been shot off.
Each of the Demo Days was attended by about 50-75 people and each time we shot off around 250 flares of all shapes, sizes and types. I kept track of the flare types that failed most often and it was the small, hand held flares where you pull the string to ignite it.
It's good PR for your club if you have a club and a good time was had by all who attended.