Having proved successful in two previous subsoil drainage projects on the busy N4 National Route, Kaytech’s Megaflo was the unrivalled choice of consultants for a third section upgrade. Operating under licence from SANRAL, Trans African Concessions (TRAC) manages the 600 km N4 Toll Route linking Tshwane in South Africa to Maputo in Mozambique East of Pretoria, where the N4 converges with the N12 at Emalahleni (formerly Witbank), SNA Civil and Structural Engineers recognised that the old subsoil drains were functioning below par and urgently needed replacing.
According to Kaytech’s Christiaan Van Wyk, “In comparison to installing a conventional subsoil drainage system, Megaflo was by far the more effective choice, saving the client time and money.”
Prefabricated Megaflo is a robust, easy-to-install geocomposite panel drain system consisting of an HDPE “flat-pipe” core completely wrapped in Kaytech’s bidim, a continuous filament, nonwoven, needle-punched geotextile manufactured from 100% recycled plastic. In this system, bidim provides the optimum filtering performance thus lowering the phreatic surface in the surrounding soils.
Since Megaflo can be installed in much narrower trenches than conventional drains, less excavation and reinstatement is required. This makes Megaflo drains ideal for retrofitting as very little disturbance is caused to the existing roadway. Once installed, Megaflo provides rapid response times thereby reducing the time moisture remains in the pavement.
Commencing in February 2017, civil engineering company, Raubex, ‘cut’ a one metre slot into the roadside using a chain trencher. A fine stone was placed at the base of the narrow trench as a bedding layer prior to the installation of 7 000 m of Megaflo 300. After filling the trench with fine stone to approximately 80 mm from the surface, a concrete plug was then placed above to seal off the installation.
The Megaflo panel
A formed invert at the base of the Megaflo panel prevents water loss into base soils, while an open, unrestricted waterway allows for greatly increased flow rates. With a high crush resistance, Megaflo will not buckle or ‘J’ during installation while its high vertical crush strength allows for reduced cover depths even under highway applications.
In seeking a fast and robust alternative to the long-winded conventional method of drainage, easy-to-install Megaflo once again proved to be the obvious and optimum solution.
For more information on Kaytech products and systems, visit www.kaytech.co.za