Without Kaytech’s state-of-the-art geotextiles and drainage systems, construction costs for a massive new parking area (30 000 m2, 3 levels – ground, B1, B2) at Pretoria’s Loftus Versveld Stadium would have soared dramatically.
Preparing the basement layerworks
Over the past 80+ years, as the popularity of rugby grew, Loftus Versveld evolved into the famous venue it is today, hosting not only international rugby and soccer matches, but also huge music festivals attracting up to 80 000 people. Unfortunately this phenomenal growth in spectatorship resulted in a dearth of parking space.
To alleviate the problem, Abland Property Developers conceived the idea of an extensive, multi-level underground parking facility for approximately 1 600 vehicles. Upon inspection of the site, however, consultants from Aurecon discovered an excessively high groundwater table that would require effective drainage. The proposed solution was to install a blanket drain consisting of two different grades of bidim geotextile in conjunction with multiple, deep subsoil drains using Flo-Pipe.
Bidim lines the subsoil drain
A-grade bidim is manufactured at Kaytech’s ISO 9001 registered production facility in Atlantis, Cape Town where high grade polyester from discarded plastic cooldrink bottles is converted into eco-friendly, polyester geotextiles that meet the most stringent civil engineering and industrial specifications. As such, bidim offers distinct advantages over other man-made fibres including better modulus of deformation, better plastic yield stability and a higher breaking strength, to name a few.
Danie Herbst, Kaytech’s Technical Consultant for the project pointed out, “For this project alone, where over 40 000 m2 of bidim was installed, approximately 112 000 PET cooldrink bottles were processed. The needlepunching method in the manufacture of nonwoven bidim provides further advantages including appreciable thickness, high porosity and a high drainage capacity.”
The bidim blanket drain separates the in situ and gravel of the platform which will also assist in lowering the water table
Installed by Pentagon Civils, the drainage system design comprised drainage trenches filled with a layer of G7 natural gravel compacted to 93% Modified AASHTO Density. The G7 was subsequently covered with 35 000 m2 of bidim A3 to act as filtration between a 150 mm top layer of washed stone (19 mm) into which 1 348 m of Flo-Pipe was embedded.
Kaytech’s Flo-Pipe, manufactured from the highest quality HDPE, is optimally slotted to provide maximum infiltration with minimal blockage. The smooth inner wall ensures high flow velocity while the corrugated outer wall is capable of withstanding massive confining pressures.The twin wall sandwich design of Flo-Pipe provides strength and flexibility which, combined with its convenient length and lightweight construction, greatly facilitates transportation and installation.
Finishing off the layerworks – Loftus Versveld parking
Each subsoil drain was subsequently covered with a slipsheet and a 125mm surface bed separated by a layer of bidim A2 (5 400 m2 in total). Experiments have shown that up to 50% fill material is required when using bidim as a separation layer. Compared to using the conventional method of installing huge layers of rock for drainage in this project, the quick and easy installation of bidim allowed for substantial cost savings and will guarantee a flood-free basement.
The convenience of having such a vast parking facility will not only please many thousands of previously frustrated fans visiting Loftus Versveld Stadium, but will also alleviate the inconvenience suffered by residents in the surrounding area.
