How to deal with moron teen who drinks to get drunk?

I would tell her you don't want her to come on the trip if she's gonna be drunk and make it clear that no one wants her to drink and no one else will be drinking. If she doesn't listen and she does get ahold of alcohol, dump it down the drain as soon as you see it. No matter how many times she gets ahold of more just keep dumping it. Is it too late to just kick her out of the trip and see if someone else wants to go in her place?