How clean does sand need to be for installation of a mound system? This question comes up very often and the answer has changed over the years since the first of what I would call the modern mounds were installed.
When I began designing mounds many years ago, the answer was the mound could have no more than 10% material finer than sand-sized particles — defined in the USDA Soil Classification System as particles between 0.05 and 2.0 millimeters. Anything finer than 0.05 millimeters would be clay- or silt-size particles and would be viewed as unacceptable if they exceeded 10% as
