Retaining Wall Earthwork in Salt Lake City, UT

Retaining wall earthwork is the excavation, base preparation, drainage and backfill behind a retaining wall. Salt Lake City's neighborhoods climb onto the old Lake Bonneville shoreline benches, from the Avenues to the East Bench and the foothills of Draper and Bountiful, so sloped yards and walls are everywhere. Most wall failures come from what is behind and under the wall: poor drainage, uncompacted fill, or a footing that was not deep enough.

Water pressure is the enemy

Clay-rich lake soils hold water. When saturated soil pushes on a wall, the pressure can be many times what the wall was built for. We place free-draining stone behind the wall, a perforated drain at the base with an outlet, and fabric to keep fines out of the stone.

Height and engineering

HomeGuide notes that walls 4 feet or taller usually need a structural engineer's design and that most cities require permits for walls over 3 to 4 feet. Walls holding up a driveway, a house or a steep slope above often need engineering even when shorter. We build the earthwork to the design and tell you when we think one is needed.

Cutting into a slope safely

Building a wall usually means cutting into the hillside first, which leaves a temporary steep face. We keep those cuts short-lived, avoid undercutting neighbors' yards, and plan the work so the wall goes up soon after the cut.

Replacing failed walls

Leaning timber walls and bulging block walls are common in older neighborhoods. Replacement starts with demolition, which HomeGuide puts at $15 to $30 per linear foot, then excavating to undisturbed soil for the new base.

Typical wall costs

HomeGuide lists block walls at $15 to $40 per square foot of face, poured concrete at $20 to $45 and natural stone at $20 to $95, with a 50-foot, 4-foot-tall wall at $7,000 to $13,000. Sloped yards can add 50 percent or more.

Neighbors above and below

Walls often sit near property lines. Before cutting, we confirm the line, look at the neighbor's slope and structures, and plan the cut so it does not undermine their yard. Soil from the cut is often reused as backfill behind the new wall when it is suitable, which cuts hauling costs.

Timing

Backfill and compaction behind a wall go best in dry weather. Saturated clay cannot be compacted properly, so major wall work is scheduled outside spring melt where possible.