Retaining walls contain soils and hold them in place behind the inside face of a vertical (wall) structure. Retaining walls are installed when a large shift in a site’s grade elevation is desired in a very short distance, in some cases for aesthetic reasons. Since the soils contained behind the wall are trapped at a nearly vertical angle, depending on the height of the wall and the soils there can be tremendous soil pressures present which must be carefully designed for. Additionally, any loads on top of the soils contained behind the wall (known as a surcharge), such as paving or other site improvements, will contribute to an even greater loading on a retaining wall structure. Moisture content and adequate drainage of the retained soils is also an important consideration.