The main function of retaining walls is to stabilize hillsides and control erosion. When construction is necessary over rugged terrain with steep slopes, retaining walls can help to reduce the grades of a development and the land alongside the project area.
Some projects lack available land for the project location, requiring construction right along the toe of a slope. In these cases extensive grading may not be possible and retaining walls become necessary to allow for safe construction and acceptable slope conditions to meet the final design requirements.
Where soils are unstable, slopes are quite steep, or heavy runoff is present, retaining walls can help to limit soil migration and be utilized as a sediment erosion control structure. Excessive storm water runoff can undermine vehicle use areas and onsite structures, thus controlling sediment runoff is a major environmental, structural and water quality design criteria aspect for development projects.
In these situations, construction of retaining walls, rather than excessive onsite grading, protects the environment by reducing the amount of the existing vegetation removal and in turn reduces soil migration and erosion caused by storm water runoff. Lastly the preserved vegetation serves to stabilize the soil and filter out sediments and pollutants before they enter a storm water pond or a local municipal infrastructure system.