The badly deteriorated gravel access route between Sani Pass, on the border of South Africa, and the town of Mokhotlong, winding through the picturesque Black Mountain Pass in the mountainous north eastern part of Lesotho was in desperate need of upgrading to a surfaced, all weather road. The notorious Sani Pass is the only vehicle route and trade link over the Drakensberg escarpment connecting KwaZulu-Natal with the mountainous Kingdom of Lesotho. Kaytech’s subsoil drainage systems were recommended for this challenging project.
The contract to build the road to a highway standard was awarded by the Ministry of Public Works & Transport Lesotho to China Geo Engineering Corporation, with Aurecon Lesotho as consultants for the project. This project has resulted in the installation of 25 000m each of Kaytech’s Flo-Drain and Geopipe.
With the original design incorporating a conventional stone subsoil drainage system, it was soon realised that the poor quality, residual basalt subsoil, in conjunction with exorbitant transportation costs of stone to this remote site, called for an effective alternative. Engineers determined Flo-Drain and Geopipe M100R would be the ultimate solution.
Flo-Drain is a quality assured, prefabricated geocomposite drainage system that, together with Geopipe, is lightweight, flexible and easy to install. Manufactured from HDPE, Geopipe is ideally suited to fin drains like Flo-Drain as its 70% open area allows for a significant increase in the infiltration rate of water. In fact, no other drainage pipes have an infiltration rate equivalent to that of Geopipe. It easily accommodates high localised flows and can tolerate extremely high stresses of overburden. It is so flexible that even under extreme conditions it may deform but will regain shape without breaking.
Importantly for this project, located at an altitude of almost 3 000m where severe winter conditions prevail, Geopipe will not become brittle even at very low temperatures. The combination of these two Kaytech products is extremely effective in lowering the water table or intercepting seepage in a wide range of applications.
This top quality subsoil drainage system, which was considerably quicker to install than a conventional system would have been requiring narrower trench excavation, provided our neighbouring country of Lesotho with several benefits including a 10% cost saving, valuable time saving and, significantly – since no special skills are required for its installation – the contractor was able to employ local labour.