Many people don’t appreciate the weight of soil. One cubic foot of soil weighs between 90 and 140 lbs. Just one cubic yard of soil (27 cubic ft), weighs between 2,430 and 3,780 lbs. The human body isn’t designed to accept the trauma of having that much weight fall on it. The deaths and injuries result from suffocation, crushing, drowning, loss of circulation and objects rolling or falling into the trench or excavation.