Getting Rid of Garter Snakes?

I have a family of garter snakes living in my concrete patio off my family room. It has cracks in it and that's how they go in and out. They really wouldn't bother me at all if my little dog didn't think of them as toys. If I don't watch him every minute he's outside (which I can't because I need to use a doggy door when I'm out of the house for work), the next thing I know there's a dead (or mostly dead) garter snake or two in my family room.

I called someone who deals with things like this and all he said was I should pour bleach into the cracks. That this would either kill them or make them leave the area. So I did what he told me to do. I didn't see any snakes for 2 days, but now they're back! There has to be a better way. Please help.

By Susan S.