This is what has to be done to fix a plumbing problem under a home with a slab foundation. Found on a home inspection a few weeks ago.  The other side of the home had piles of sand about the same size.  I don't even want to think about the cost.  With a raised home, you could just crawl under there and do it yourself or pay a plumber $250 to fix a pipe.  I love raised homes!  That's why I live in one.