What is reduced level excavation?

The ground which lies between the topsoil and earth's crust is known as the subsoil and comprises particles of weathered rock of various shapes and sizes. It is usually necessary to provide a level surface from which construction may take place, and this level may be lower than the top of the subsoil. In such cases, excavation into the subsoil is required to reduce the level of the ground. The volume of subsoil to be excavated, together with the nature of the material, will determine the type of machine and methods to be used.