Housing in Southern Africa February 2015

Infrastructure & Mixed Use

Specialist geotechnical engineers Melis & Du Plessis were tasked with sealing leaks at the Quion Rock Dam in Knorhoek Valley, between Stellenbosch and Paarl, Cape Town. Kaytech seals leaks

punched geotextile. With its simple installation, environmentally friendly bidim is extremely cost-effective and, due to its inert characteristics, will extend the life andmaintain the integ- rity of a liner system long after the re- quireddesign lifespanhas ended. Kay- techbegan incorporating recycledPET bottles into its nonwoven production in the mid-80s. Kaytech simply melts the granulated bottles, crystallises the polymer and spins it directly into filaments. The good properties built into the raw materials are retained and the resultant filaments have the strength and durability demanded by civil engineers. Over the past decade, Kaytech has converted and recycled more than 18 million kilograms of polyester (rPET) into bidim and other civils products. Power Construction, part of the national company Power Group, was awarded the contract to install EnviroFix X800 and by the end of the project, Dams A and B had been lined with 36 000 m 2 of the clay liner. In total, Power Construction installed 34 000m 2 of bidimA8 (750g/m 2 ) inside the dams, allowing sufficient reten- tion of soil underneath the riprap. Over 472 222 recycled PET cooldrink bottles were used in the manufacture of the 34 000 m 2 of bidim supplied to this project. For more information on Kay- tech products and systems, visit www.kaytech.co.za ■

T he geotechnical engineers specified Kaytech’s top quality Geosynthetic Clay Liner (GCL), EnviroFix X800 to solve the problem. The proudly South African manu- factured product, EnviroFix, is de- signed for lining water and waste containment sites. It is produced by needling a uniform layer of sodium bentonite, a naturally occurring clay mineral, between two durable outer layers of geotextile. When sodium bentonite, with a structure compris- ing charged platelets, comes into contact with moisture, it swells considerably. If this occurs under confinement, it forms a lining with a low permeability equivalent to that of approximately one metre of com- pacted clay. With these clay-constructed farm dams situated on the slopes of the imposing Simonsberg Mountain, their steep embankments posed a problem if the conventional layer- works approach was adopted. Since the consultants were already familiar

with the time-saving and easy instal- lation of EnviroFix, it was a simple choice to make. EnviroFixwas laid onto awell com- pacted, smooth surface and covered with Kaytech’s recommended mini- mum cover thickness of 300mm on the floor of the dams, and a 150 mm clay cover layer on the slopes of the dams. The additional confinement required on the slopes was made up with a layer of 200-250mmsize riprap, placed on top of the GCL/clay lined embankments for protection against erosion and wave action. Since this angular riprap had sharp edges, a specific protection geotextile was placed beneath it. Consultants had no hesitation in specifying Kaytech’s bidimA8, which is stronger andmore robust than bidim A7 but easier to install andmore economical than the heavier bidim A10. Manufactured by Kaytech from 100%recycledpolyester Polyethylene terephthalate (PET), bidim is a non- woven, continuous filament, needle

February 2015