Fibertex SA has recently supplied a range of geosynthetic products for use in the construction of a large electrical substation in Cape Town. The new Eskom Pinotage Substation is located in Faure, near Somerset West.
“Fibertex SA – with vast geosynthetic solutions in construction and building works for separation, filtration, drainage, protection, erosion control and reinforcement – form an integral part of structural designs,” says Paul Baxter, Fibertex South Africa.
“The substation, which consists of a 400/132 kV high voltage yard gave the Eskom Engineers some initial challenges, including a large cut to fill operation necessary to create a level platform for the new transformers.
This necessitated the erection of a suitable peripheral precast segmental block retaining wall system.
“Because correct geosynthetic reinforcement and drainage design is key to the stability and safety of any retaining structure, rigid Secugrid geogrids were used in combination with a heavy duty precast concrete segmental block. Fibertex also supplied various components for an advanced subsoil drainage system.”
Approximately 46 550 m² of Fibertex’s PET (polyester) Secugrid 80/20 R6 uni-axial geogrid was installed. Secugrid, with its high residual strength at low strain, forms an integral part of the block wall by adding tensile resistance to the reinforced soil zone. The wall is approximately 700m in length with heights varying from 7m to 11m and was constructed by Terrafirma Retaining Walls.
Secugrid is designed to strengthen naturally unstable soil and subgrades so that the composite soil structure will be able to withstand the required loading conditions, through both an interlocking and frictional effect, with little or no movement in the overlying soil materials over the structure’s lifetime.
This robust reinforcement material is also highly resistant to biological and chemical degradation, as well as installation damage. Secugrid is supplied in rolls and is quick and efficient to install, with minimal demand on labour resources.
Flexidrain, an extruded high density Polyethylene (HDPE) geonet covered with a Fibertex F-25 Polypropylene (PP) non-woven geotextile jacket to form a 500mm wide wick-drain composite, was placed at 8m centres horizontally and 45˚ to the vertical, between the G7 fill material and the selected granular fill.
The subsoil water is then led to a front collector drain behind the toe of the retaining wall and discharged into Fibertex Drainex DN160 drainage pipes, which are also chemically inert.
Fibertex supplies a comprehensive range of other geosynthetic products into the civil engineering and mining industries. These products include nonwoven and woven geotextiles, gabions and mattresses, geosynthetic clay liners, composite cuspated drainage and leak detection systems, erosion control blankets and cellular confinement solutions.