The creation of South Africa’s first gigantic “green city” is the result of the largest mixed-use precinct ever to be built in Tshwane. With the construction of Menlyn Maine, the traditionally residential suburb of Menlyn in Pretoria East has undergone a dramatic transformation. Its buildings, which include office space, hotels, residential units and retail space, have been designed to receive ratings from the Green Building Council of South Africa.

It was here that engineered fabrics company Kaytech provided an effective structural drainage system for the Menlyn Maine Shopping Mall. To alleviate the accumulation of underground pore water pressure in the basement area of the mall, a drainage system consisting of a “bidim” liner A2 and fine stone, covered with plastic, was installed prior to the casting of concrete flooring. Kaytech’s technical sales representative Christiaan Van Wyk was on site to ensure installations ran smoothly.

Kaytech’s bidim product is manufactured in South Africa from 100% recycled polyester. It is a continuous filament, nonwoven, needlepunched geotextile that provides appreciable thickness, high porosity and a high drainage capacity both transverse and normal to the plane.

High stability

As a structural drainage system to increase the stability of the basement, Zip Core was installed on the walls with toe drains consisting of bidim and drainage pipes along the bottom. Zip Core is a high strength, pre-formed drainage system consisting of a horizontally aligned, single cuspated HDPE sheet. This lightweight, flexible sheeting is simple to install, simple to join, and provides high water-flow capacity, high compressive strength and requires no aggregate.

“The cause of failure of most earth retaining structures is excess water trapped behind the walls. A network of sub-soil drains was installed on the exterior to decrease the volume of underground water reaching the basement structure,” says Van Wyk.

Lowering the cost barrier

Upon completion of the project, contractor WBHO had installed 38 180m² of bidim A2 and 420m of Zip Core. Through the combination of Kaytech’s various high performance geotextiles, a cost-effective, easy-to-install drainage system was created. By eliminating the need for costly conventional drainage methods, Menlyn Maine Development Corporation was saved a significant amount of money.