Exeter Estate is situated in the upmarket suburb of Bishopscourt, Cape Town, where each home has unobstructed views of Table Mountain. When construction of the estate commenced in 2021, it became evident that the steep, heavily contoured ground required extensive earth retaining walls.

Each of the homes required raised building platforms to accommodate space for large gardens, backyards, pools, tennis courts and garages, and the Terraforce retaining system was specified as the best solution. This is because the block is versatile in application and elevation. The cut slopes were stabilised with Terraforce L12 blocks in charcoal, with the round face finish of the block facing outwards. In total, 30 000 blocks were installed. Selecting the round face finish is what allowed space for topsoil and ultimately the addition of ten different indigenous ground creepers, planted by Alan Dawson Gardens.

Jeremy Leighton of Decorton Retaining Walls says there were some complications with stormwater damage after the very strong storms in winter and, as specified by Terraforce, surface stormwater channels are a crucial part of the retaining wall installation to inhibit water ingress. This prevents heavy rainfall damaging the retaining walls.

He adds that the design parameters by the consulting engineers stipulated that each of the cut slopes was to be retained with three two-metre retaining walls at 70-degree angles, except for the walls running along the back boundary of the estate, and where mature trees had to be circumnavigated. The bottom third of each terraced wall is concrete-filled and some of the larger walls are reinforced with geogrid. Each wall is fitted with subsoil drainage and sand drainage layers running along the back of the cut embankments.

Landscaping and irrigation

The client asked landscaper Alan Dawson to cover and green the retaining walls, and Dawson’s design concept was to keep the planting as simple as possible using hardy, flowering, indigenous plant material that would cover the retaining blocks and create green walls throughout the estate. He says that preparing the planting spaces in the retaining walls was “challenging and time consuming, and the planting of the walls at such heights was also a challenge. Nevertheless, it was an incredible landscape job, and we timed our planting to have most of it done during the winter months, carefully considering plant choices.”

Irrigation is a combination of drip and mist irrigation, and borehole water is used. All excess runoff and rainwater are collected in an underground tank at the bottom of the estate.

Project Team

Client: KingsHill Group

Architects: Zeanne & Goss Designs

Consulting Engineers: Gadomski Consulting Engineers

Terraforce Recommended Contractor: Decorton Retaining Systems

Terraforce Licensed Block Manufacturer: Cape Retaining Systems

Landscaping: Alan Dawson Gardens