May 2022, KCE Consulting Engineers planned a Terraforce wall design that allows successful interfacing with the environment, by creating space for vegetation in the near vertical terraces and “shelves” with plant pockets constructed by turning the L12 blocks round face outwards at regular intervals. Installed by Terraforce Recommended Contractor, Decorton Retaining Systems.
The project is located in the north-eastern quadrant of this new residential development by Balwin Properties in Richwood, Western Cape. The retaining wall acts as the buffer between the engineered platforms on the lower level and the protected nature conservation area to the east.
Says Nigel Barr, KCE Consulting Engineers: “The residential scheme of De Aanzicht in Atlantic Hills nestles up against a large Rhenosterveld reserve. With slopes of up to 12m high which included soft rock outcrop, creating a “soft” interface required the use of an undulating retaining system – Terraforce – combining access, planting and stormwater management. When finished this slope treatment will disappear behind planting – hiding the “under the skin” engineering of soft soil anchors, tied back foundations and the clever use of the mixed pattern Terraforce block facings.”
Barr elaborates on the design of the overall retaining system: “In order to create the embankment required within the restricted footprint area, KCE designed and detailed a two-part system to adequately secure the embankment whilst taking great care to avoid encroachment into the environmental buffers and restricted no go zones around the conservation area.”
“A series of soil nailed terraces with the front faces stabilized with a gunnite shotcrete was created as the initial lateral support system for the embankment, with a series of terraced Terraforce retaining structures constructed in front of the lateral support, providing the aesthetics and landscape friendly portions for the face of the embankment. The Terraforce walls act as a cladding for the otherwise harsh and rustic finish of the lateral support system whilst also providing planting pockets, accessible terraces and maintenance access routes throughout the embankment area.”
When asked why Terraforce was chosen, Barr highlighted that, “Terraforce is the “go to” block for almost all the gravity solutions throughout the region. The aesthetics appeal of the rock face finish blocks suited the overall environment and blends into the surrounding landscape with ease. The blocks are both familiar, proven and readily available making it the obvious choice for this job. The design and engineered flexibility the Terraforce system provides was also a huge plus – to suit the intricate nature and shapes of the terraced embankment.”
A total of 1620sq.m of Terraforce walling was installed, and planting of the wall was completed early 2023. The vegetation is establishing well and already creating the desired effect.
Client: Balwin Properties
Architect: DHK Cape Town
Engineer: KCE Consulting Engineers (Civil & Structural engineers on project)
Quantity Surveyor: Balwin Properties in house
Main Contractor: Balwin Properties
Sub-Contractor: PK Civils (Civils and walling contractor)
Sub-Contractor: Geociv Group (Lateral support contractor)
Installation by Terraforce Recommended Contractor: Decorton Retaining Systems
Blocks supplied by Terraforce licensed manufacturer: Klapmuts Concrete