Water, Sewage & Effluent March-April 2018 | Page 21

Case study by Kaytech the drain while water passes through, thus lowering the phreatic surface in the surrounding soil. Upon completion of the project in October 2017, contractors had installed 2 000 metres each of FloDrain 400mm and Geopipe M65R, resulting in the effective interception and control of subsurface water entering the new layer works. u process provides several benefits, including appreciable thickness, high porosity, and a significantly high drainage capacity in both the transverse and normal to the plane. Bidim performs two functions when incorporated in a subsoil drain: that of filtering and separating, and fine soil particles are prevented from entering B y February 2017, the development of the Bergenzicht Country Estate in the Simonsberg and Franschhoek mountains in Paarl had reached Phase 4. Unfortunately, a leaking dam situated upstream from the estate was causing a noticeable rise in the water table. The combination of this moisture and the iron-rich soil, for which the area is prone, resulted in the formation of ferric oxide that, in turn, can lead to a slimy gel forming, capable of blocking an entire drain and polluting groundwater. The backfill used in the drain was clean free-draining river sand. The engineering consultant on site recognised that conventional drains for the parking area were not a viable option; therefore, he specified easy-to- install FloDrain and Geopipe systems. These would not only act as cut-off drains, but importantly, would also reduce oxygen levels and thereby the formation of ferric oxide. A contractor in the Western Cape, who recently experienced difficulty installing conventional aggregate drains in waterlogged soil, chose to go with an innovative system. Two for the price of one Used for a wide variety of subsoil drainage problems, is Kaytech’s ready-made FloDrain and Geopipe system. The prefabricated FloDrain is a lightweight, flexible system that reduces the costs of transportation, excavation, and labour. It is installed vertically into a trench, with a Geopipe positioned and wrapped in the bidim filter jacket at the base of the fin. Manufactured from HDPE, the material is light and flexible and much easier to handle than other pipes; it easily accommodates high localised flows and can tolerate extremely high stresses. With its 70% perforated surface area, it allows for the highest infiltration rate of water compared to that of any other drainage pipes. FloDrain is supplied pre-wrapped in bidim — Kaytech’s continuous filament, nonwoven, needle-punched geotextile, manufactured from 100% recycled polyester. The needle-punching innovations The solution Red, orange staining is an indication of ferrous oxide occurring within the subsoil drain. Water Sewage & Effluent March/April 2018 19