In order to rid your yard of moles, you need to know what it is that's ATTRACTING them to your yard.
The moles, for the most part, are feeding on Japanese Beetle Larva. The beetles lay their eggs just below the surfact of the lawn and the moles tunnel just below that and eat the larva. As long as there is a good supply of larva around, you'll have a good supply of moles too.
In the early Spring, you should apply a spread-coat of Grub-X. Grubs eat this stuff and from what I've heard, when it's injested, it swells their bodies so they bloat and explode. (I don't know how much of this is fact or myth but it kills them.) It's harmless to pretty much anything else. Anyway, you just can't do the area that the moles are in. You need to do the whole yard. If you don't, they'll tunnel around until they find an area you didn't cover with the Grub-X. When I had them this spring, I did my yard from fence to fence. I watched the moles frantically tunnel around until they hit the fence between my neighbor and me. He/they ran along the fence (underground) for 3-4 feet then found where they could cross under it into his yard. Now they're happy again!
You should only have to do this in the Spring when the larva and the moles are 'feeding'. Best to ya and happy trails (no pun intended.)
PS. There are contraptions to kill the moles but I suggest you try to kill what they're eating first. You know the moles are gone when you are no longer finding them 'pushing up' on the tunnels you crush with your feet.