We were called to inspect a project that involves the construction of a new retaining wall in the backyard of a home in Orem, Utah. While much of the wall will only need to hold back approximately four feet of soil, there are some portions where the height of the wall will reach as high as eight feet. Because of these taller sections, the client requested an engineering review of the proposed design.
The wall is to be built with a footing three feet wide and one foot thick, including a 6-inch deep by 12-inch wide shear key to help resist sliding. The footing will be embedded at least a foot below grade to provide stability. From this footing, the wall will rise with a stem that begins at 12 inches thick at the base and tapers to 8 inches at the top. Reinforcement is provided by #4 rebar throughout: vertical bars placed at 12 inches on center and tied into the footing, and horizontal bars also at 12 inches on center, with proper placement near the top and bottom of the wall. The footing itself will be reinforced with a mat of steel, and dowels are specified where footing steps or cold joints occur.
Drainage and backfill are also addressed in the design. A 4-inch perforated pipe will be placed at the base and sloped to daylight or a sump. Behind the wall, a minimum of 12 inches of free-draining gravel will be installed, separated from native soil by filter fabric. Proper compaction of the backfill in lifts will help the wall bear its loads effectively over time. This assessment confirms that the wall, when built to these specifications, is properly designed to resist the pressures of retained soil and water while maintaining long-term durability.