A unique Kaytech manufactured Geosynthetic Clay Liner saved hundreds of people in a township south east of Johannesburg from forced evacuations.
Frequent flooding of 59 properties in Thintwa, a residential suburb of Thokoza, initially led to the Ekurhuleni Municipality making the difficult decision to relocate the affected families.
When it was realized that relocations were not viable, the council sought a technical solution to eliminate flooding in the area. After investigations, a consultant from WSP designed a network of concrete lined open channels in conjunction with an attenuation dam and a new storm water outlet.
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The attenuation dam will store the water until it is released via the outlet.
Specifications
Specifications included lining the dam with Kaytech’s EnviroFix X800, a composite Geosynthetic Clay Liner (GCL) produced by needling a uniform layer of sodium bentonite between two durable geotextile outer layers.
A proprietary heat treating process, Thermal Lock, is used to modify and more permanently lock the needlepunched fibres into place. This procedure results in a completely uniform, reinforced GCL with unique properties including increased internal shear resistance and long term creep resistance.
Sodium bentonite, a naturally occurring clay mineral with a structure comprising charged platelets, swells considerably upon contact with moisture. When hydrated under confinement, a lining with a low permeability, equivalent to that of approximately one metre of compacted clay, is created.
The attenuation dam comprised a lining of EnviroFix X800 covered with a 100 mm layer of River sand followed by a 200 mm layer of topsoil. The topsoil was subsequently grassed thereby covering the entire dam area. Commencing in July 2016, Lekhotla Construction installed a total of 22 000 m2 of EnviroFix X800.
Kaytech EnviroFix
EnviroFix is easy to install and highly durable over a wide range of installation conditions; the needlepunched fibres holding the bentonite layer in place, greatly reduce the adverse effects of premature hydration during installation. Manufactured under an intensive quality control programme utilising the latest EN-ISO and ASTM procedures at the Kaytech factory in Atlantis, EnviroFix provides consistent high quality performance while the expensive and time consuming onsite quality assurance testing required for compacted clay liners, is minimised.
Compared to the conventional method of constructing a dam in which a certain percentage of clay is mixed into the soil, the use of EnviroFix for this project not only saved both time and money, but also saved many families from the indignity of forced evacuations.
