Why Piles? Because we are on a spoil heap. Our house will be built on the spoil heap of what was a clay and sandstone quarry.  We are here The ridge of trees 50m to the south stand on the top of what was the old quarry face. We had a soil survey done (have a look at it here) The bore hole location map is on page 47 and the profiles are detailed on the next pages. Here's how much it cost to get this done. (Feb 2015; desk study and geophysics). Our house will stand on the site of the old