Hello, I need some help!

Thanks to the City I live in I now have Rats in my crawl space (long story).

Anyway... my house was built in the 30s, sits on pillars and has a dirt crawl space (it was at one time a cottage). My understanding is the best way to keep them out is to have a 3 foot deep footing (block or poured) dug around the house.

Any idea how much something like this would cost? Any idea who I could contact for an estimate?

At least they aren't dumb enough (or have not been yet) to come in my house (I have two rat terriers and 2 cats).

Any info you could provide would be very helpful!

Thanks