On top of Waterkloof Hill sits Greenhill Estate, an eco-friendly and energy efficient residential estate that offers magnificent 360-degree views of the surrounding area and is the first green housing solution development in Pretoria. Technicrete were selected to supply their Enviro-Wall retaining wall blocks, Enviro-Wall base blocks and Keystone paving to the project.
Greenhill, developed by the Green Housing Company, comprises 39 exclusively designed units. The development started in August 2017 and is expected to be completed during the last quarter of 2018.
Technicrete were contracted to supply their Enviro-Wall retaining wall technology in order to form the multiple different platform levels and ensuring future prevention of soil erosion. Enviro-Wall is a versatile reversible block offering a variety of visual effects. It can be used with gaps for vegetation growth or as a solid engineering structure and as a gravity wall or one reinforced with structural geogrids.
“Technicrete’s Enviro-Wall technology was specified by the project consulting engineers” said Piet Pretorius of Piet Bok Construction, “The benefits gained from their Enviro-Wall technology were particularly relevant to the Greenhill project due to each stand being developed at different levels, thereby requiring good, sturdy and attractive retaining wall installations. Additionally, the Enviro-Wall offers the option for vegetation and plants to be placed into the gaps making it an attractive feature should owners choose to utilise the retaining wall in this manner” said Pretorius.
“We worked well with the Technicrete technical and sales teams. Justin Kretzmar, Infrastructure Specialist Group’s, (ISG) sales engineer, regularly visited the site to ensure that the retaining wall and base blocks were correctly installed and to attend to any questions pertaining to installation challenges. It was that attention to detail that we appreciated most on this project” added Pretorius.
“We worked on the designs of these walls with the engineers on the Greenhill Estate project long before commencement of bulk earthworks to show how the Enviro-Wall technology offered the best retaining wall solution to this multi-levelled project” said Justin Kretzmar. “Wall heights ranged from 1m up to 6m, requiring a single design philosophy that could be used across the board, keeping it simple whilst still remaining cost effective and within budget.”
“We provided factory samples for the project managers to have a hands-on exposure to the benefits of the retaining wall technology in creating multiple terraces with ease. For over 18 months we collaborated in order to supply a product that the engineers and developers were completely satisfied with – not only its performance, but also the final appearance of the retaining wall, which we supplied in their required tan colouring” he said.
“Once the Greenhill Estate entered the construction phase it was important for me to ensure that the system was installed according to specifications in order to maximise its overall effectiveness. To this end, I regularly inspected the site” Kretzmar commented.
“The Greenhill Estate, situated at the top of a ‘koppie’, has been the most complex site that I’ve ever seen from a platform perspective, with almost each of the 39 stands being at a completely different level. This has required many walls, at different levels, weaving in all directions and tying into each other as and where required. We opted for a wall design reinforced with horizontal structural geogrids and to this end, the Enviro-Wall block, due to its shape and interlocking pattern, offers the best ‘key’ to secure these geogrids from pull-out” Kretzmar added.
The Enviro-Wall is constructed from dry stacked interlocking, precast blocks. The simplicity of their design enables the blocks to be easily and quickly laid to form an effective retaining wall system. Opening or closing the spacing between the blocks enables the Enviro-Wall structure configuration to be altered so that in the open arrangement cavities between adjacent blocks can be filled with soil, promoting plant growth. It can also be installed as a solid engineering structure.
Kretzmar highlighted “The blocks are suitable for supporting a wide range of embankment heights, the wall is able to accommodate both concave and convex alignments down to a small radius of 2m. With the custom designed Base Block, the angle of the inclination of the wall is easily set out at 700, but can be varied should site conditions require something different”.
Technicrete’s Keystone paving was utilised for all of the estate’s main roads. The pavers
combine two distinctive shapes into one unit, making it an attractive option for driveways, parking areas and access roads.
Rocla, also part of ISG, supplied lids and cover slabs for the six manholes installed at Greenhill Estate.
Technicrete is part of ISG which also includes Rocla.