Please take a look at the attached photo. My neighbor's fence is caving in toward my side of the back yard. The ditch is the result of a construction dump that the builder used to put debris while building the houses back in 1987. I was informed about it when looking at the house, but didn't think it would be a big deal. At the time, it was rather harmless looking. The ditch looks like it's getting deeper. Who is responsible for fixing this? The builder? Or are both (or one) homeowners responsible? What would be the approximate cost to cure this?