Developers and Architects are often faced with the challenge of restricted or even no space at steep or small building sites. This is when retaining walls with the smallest possible footprint on the plan must be designed to make it all possible.
This was certainly the case at the Twickenham residential development in Victory Park, Johannesburg. Says Deon Grimbeek and site manager Hennie van der Merwe both from Renico Construction: “The property was on a relatively steep gradient, which demanded close attention to the design and construction of a series of retaining walls, designed by Silvio Ferraris of Remacon Products and built by Powergate Construction using the Terraforce retaining wall system.”
For this project, Ferraris specified the Terraforce L11 block, which is supplied by Remacon Products, Terraforce licensed manufacturer based in Gauteng. The installation features a series of near vertical walls measuring up to 3m in height with a solid look, yet textured block finish. This was achieved by turning the block with their flat face outwards during construction. The blocks were also cut to create a range of sharp corners, maximising every square inch of space for the apartment blocks and gardens, in particular, some old palm trees that needed to be preserved.
Says Ferraris: “As most walls are 85°, they are reinforced with Secugrid 40/40 Q1 polypropylene grids where piling through the grids is required (the polypropylene can be cut through by the piling augers without it being all gnarled up in the auger and ripped out), and where no piling was required the Rockgrid PC 50/50 polyester was used. Corners were reinforced with hooped Y12 steel and filled with concrete to prevent future movement and corner cracking.”
“Groundwater had to be dealt with by placing adequate drainage at the base of the walls, in some cases blanked drains at the base, in severe cases pilot dump rock was required, in all cases 100mm wick drains against the natural soil cut faces were used.”
As the drone images of the development show, the brief was carried out very successfully. The steep walls are precisely installed with superbly constructed corners, remaining unplanted for little future maintenance, as requested by the client.
Engineer: Silvio Ferraris, Remacon Products
Main Contractor: Renico Construction
Sub Contractor: Powergate Construction
Block Supplier: Remacon Products