Our garden, a dumping site!

While on a routine inspection of our grounds today, TPP came upon a pile, not a large pile, but nonetheless a pile of construction trash: pieces of concrete, polyurethane foam, plastic frame pieces, pieces of wood.  They were heaved over the fence from one of our five back yard neighbor's.  The neighbor is not a problem; he's a very nice fellow, but he's hired some dumbass redneck clod of a contractor who saw our yard as a convenient way to get rid of a pile of construction trash.  TPP does not know about you, but he finds this extremely annoying.  After photographing the trash pile, an attempt will be made to locate this class act contractor and have them clean up their mess.  The things you have to put up with when you have a large garden that tends to be ever so slightly wild around the edges.  For some reason spaces such as this seem to invite trespass.  What gives?  What do these people think?