That is horrible.
Vermin or not, in most places you still have to "kill" them in a relatively humane way. Throwing live animals into a compactor is far from humane, it is cruel and ultimately very very sick. I can't believe the workers there actually do that willingly!!
What do they do about the other "vermin" ie: birds, rats, etc? Do they get rid of them the same way?
I would def. contact someone about this. I cannot imagine it is legal.
I think the media route would also be a good way to go. I'm sure many a townspeople would be up in arms over this.