CMA NEWS AND MEMBER ARTICLES

CMA News & Articles - The CMA is the precast concrete industry association of South Africa. Find our members on our website to source quality precast concrete products, professional built environment service(engineers, architects, contractors and more).

ECO-FRIENDLY DUNE REHABILITATION WITH TERRAFORCE

April 29, 2021 1554 1554

Nhoxani Beach (Peaceful Place), is a prime waterfront housing estate situated on the magnificent Santa Maria peninsula, which juts into the Bay of Maputo in Mozambique. Over the past four years, seven beach-front accommodation sites have been developed as part of the estate. These sites are situated on a 430m sand-laden strip that abuts an indigenous forest, carefully preserved by the owners of the concession property.

Caption: One of the retaining walls at Nhoxani Beach under construction.

High concentrations of sand-borne silicone on one of the sites meant that measures to prevent wind and water erosion was an urgent requirement. During the winter months, the erosion was further aggravated by local fishermen who sought refuge on the site and burnt brushwood to keep warm.

After some online research, Nhoxani developer and shareholder, Mike Braby, contacted Terraforce to discuss the environmental benefits of its earth retaining and erosion control systems.

Caption: The neatly terraced wall constructed with Terraforce blocks.

An agreement followed and as soon as a wall design was in place, Terraforce L11 retaining blocks were trucked to Maputo from EFS Construction - a Terraforce licensee manufacturer based in Mbabane, Eswatini. The blocks were then shipped by dhow to Santa Maria, under the supervision of Terraforce-recommended contractor, Ben van Schalkwyk, of BRW Projects, who designed the wall and managed its installation.

Van Schalkwyk explains installation proved no easy feat: “The wall itself covers 400m² and was designed with four three-meter-high interconnecting terraces, the highest point reaching 12,4 m. Getting the concrete foundations placed (each terrace had its own foundation) proved challenging, as the dune bank was constantly collapsing. An agri drain was placed behind the wall to prevent water build-up. We also placed Bidim behind the wall, as well as cement stabilised backfill – all the way to the top - to provide extra stability.”

Caption: Indigenous vegetation covers a section of the wall.

After completion, the retaining wall was painstakingly planted with indigenous vegetation by local labour. It took another couple of years for construction of the development to begin, during which the wall stood the test of time, without incident.

Braby adds that the overall result exceeded expectations: “The retaining wall design in consultation with engineers and environmentalists created an excellent solution, whilst also establishing a building footprint big enough for a medium-size house. This outcome was only possible thanks to the stabilisation of the dune using the Terraforce block. The building technology used for the house, employing robust stilted gum-pole foundations, facilitated elevated floors with stunning views. I am happy with how it all turned out.”