Retaining Wall –What Are My Options?
Retaining wall are walls which retain soil or soil banks and are used to create usable space which cannot be done by sloping the ground surface because it will fail.
There is a wide variety of ways that retaining walls are constructed. The most common ones which are used are in general order of cost are reinforced Soil Sloped Walls, Steel Sheet Pile Walls, Concrete Modular Unit Gravity Walls, Soldier Pile, and Lagging Walls, Mechanically Stabilized Earth Walls, and Cast in-Place Reinforced Concrete Wall.
Concrete Modular Unit Gravity Walls
Photo Credit Redi Rock
Soldier Pile and Lagging Walls
Photo Credit: The Vasco Project by Contra Costa
Steel Sheet Pile Walls 
Cast In-Place Reinforced Concrete Walls
From the least to the most expensive wall type there is over a 5-fold difference in the installation costs. In addition to costs, the other factors that are considered include the wall systems workability with the site and the appearance of the wall. May be considered in the selection of the wall.
Example photos of these different types of walls. In the selection of the most appropriate retaining wall type for a project, a geotechnical engineer with sufficient experience in this area should be consulted. For more information on reinforced soil slope walls see Engineering Updates 39 and 42.
Mechanically Stabilized Earth Walls