2 minute read
MIXED PATTERN WALL DESIGN RETAINS STEEPS SLOPES, WITH EASY PLANTING
by IMESA
PROJECT TEAM
Client: Balwin Properties
Combining engineering with aesthetics, KCE Consulting Engineers created a Terraforce wall design to match the unique site characteristics of De Aanzicht – a new residential development constructed by Balwin Properties in Richwood, Cape Town.
Architect: DHK Cape Town
Engineers (civils & structural): KCE Consulting Engineers
Quantity surveyor: Balwin Properties
Main contractor: Balwin Properties
Sub-Contractor (civils & walling): PK Civils
Sub-Contractor (lateral support): Geociv Group
Terraforce installation: Decorton Retaining Systems
(Terraforce Recommended Contractor)
Terraforce block supplier: Klapmuts Concrete (Terraforce Licensed Manufacturer)
The design successfully interfaces with the environment by creating space for vegetation in the near vertical terraces and “shelves”, with plant pockets constructed by turning the round-faced side of selected Terraforce L12 blocks outwards at regular intervals. The system was installed by Terraforce Recommended Contractor, Decorton Retaining Systems.
Located in the north-eastern quadrant of the property development, the retaining wall acts as the buffer between the engineered platforms on the lower level and the protected nature conservation area to the east.
“The residential scheme nestles up against a large Rhenosterveld reserve. With slopes of up to 12 m high, which include soft rock outcrops, creating a ‘soft’ interface required the use of an undulating retaining system, combining access, planting, and stormwater management,” explains Nigel Barr at KCE Consulting Engineers.
This slope treatment is now gradually disappearing behind planting –hiding the “under the skin” engineering of soft soil anchors and tied back foundations, thanks to the clever use of the mixed pattern Terraforce block facings.
A two-part 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, while taking great care to avoid encroachment into the environmental buffers and restricted no-go zones around the conservation area,” Barr continues, elaborating on the design of the overall retaining system.
“A series of soil nailed terraces – the front faces stabilised with gunite shotcrete – were 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.”
As Barr explains, the Terraforce walls act as a cladding for the otherwise harsh and rustic finish of the lateral support system, while 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 aesthetic appeal of the rockface 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 1 620 m2 of Terraforce walling was installed, with planting of the wall completed early in 2023. The vegetation is now establishing well and already creating the effected envisaged in KCE Consulting Engineers’ initial design concept.
