Building Retaining Walls on Steep Slopes

A steep lakeside lot overlooking Okanagan Lake was transformed with five tiered retaining walls, creating usable backyard space for a pool, patio, and outdoor living area.

The Tocher residence sits on a small plot of land overlooking Okanagan Lake in West Kelowna, British Columbia. While the location offers beautiful views, the steep slopes and limited lot size left very little usable space in the backyard. The Tochers’ plan was to replace a small retaining wall near the house with a much larger wall closer to the property line, creating enough usable space to install a swimming pool.

Allan Block Construction on a Steep Slope

To achieve the desired backyard space, the walls needed to manage more than 40 ft (12.2 m) of elevation change from the back property line. Local ordinances allowed exposed wall heights of up to 8 ft (2.4 m), provided that tiered retaining walls were separated by at least 6 ft (1.8 m).

Meeting these requirements meant constructing five retaining walls. Four of the walls were built to a height of 10 ft (3 m) and one wall was 4 ft (1.2 m) tall. A slight slope between the walls ensured the exposed height of each wall remained within the 8 ft (2.4 m) limit set by local regulations.

Because of nearby rock outcroppings, the lowest wall had to be anchored directly to the rock face. This was accomplished using 1 in. (2.5 cm) stainless steel threaded rods inserted into drilled holes and secured with epoxy grout. The rods were connected to 3 in. (7.6 cm) schedule 40 galvanized pipe. Geogrid reinforcement extended from the wall, wrapped around the pipe, and then returned toward the wall to the next course above.

The second wall incorporated geogrid reinforcement extending up to 32 ft (9.8 m) where space permitted. In areas where clearance was limited due to rock, the wall was pinned directly to the rock face. The remaining upper walls were also reinforced with geogrid.

Contractor Sunnyslope blasted, jackhammered, and excavated sections of rock to create a stable, level ledge within the bedrock for construction. While blasting added extra work, it also produced high-quality granular material that was reused as backfill behind the walls. As a result, very little additional fill had to be brought to the site.

The Tochers’ small backyard—once limited to a few plantings, a small sitting area, and a narrow strip of grass—was transformed into a stunning outdoor living space. The new design includes a swimming pool, pool house, and an artificial putting green. A wraparound pool deck and patio now provide the Tocher family and their guests with a perfect place to relax while enjoying the sweeping views of the valley below.

For more information on this project, see the case study Terraced Walls – Okanagan Lake – West Kelowna, BC.