Posts are correct, & you want to put the pressure switch at the house. I've 5 years on about 250' of 1.5" schedule 40 PVC (20' lengths with 1 bell shaped end, glued) in sandy soil (no rocks) at 12" depth - but then I'm on the coast of South Carolina. Only problem I've had was when a cement truck parked over the pipeline while waiting to pump concrete into the floor mold for my garage/apartment. Broke the pipe, which was fixed in about 15 minutes with the usual materials. I've since driven over the entire pipe line (as I did multiple times after laying it) with my tractor and box bladed dirt into any depressions made. Should be tightly packed - I hope, but will find out the next time a cement truck chooses that exact location to park for an hour.