Development of an iron-ochre clogging-resistant filter complying to the European Market Requirements

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Subsurface drainage essentially consists in lowering the water table in a soil mass. This function is critical to protect man-made structures such as buildings against moisture-generated mold; to prevent losses of bearing capacity of roadways; as well as to remove excess moisture from the soil profile in agriculture, providing suitable conditions for crop production. Subsurface drainage pipes must remain open for water to flow. Beside the hydraulic capacity of the pipe, the design and maintenance of such structures focuses mainly on maintaining soil particles out of the core with the help of a filter, and avoiding clogging by roots or iron ochre. Achieving the filtration function is typically done using a geotextile filter in North America, and in particular knitted geotextiles. However, a different technology is used in Europe: instead of tubular knits, European pipes used in subsurface drainage applications are typically wrapped in a thick bundle of fibres, held together by a very open mesh.Replacing the fiber bundle currently used in Europe as a pipe-wrap by a knitted geotextile is a cost-effective solution. However, adoption of this technology is restrained by different issues, including a very conservative business environment reinforced by the fear that the knitted geotextile is more sensitive to iron-ochre clogging than a bundle of fibers. To introduce knitted geotextiles on the European Market, the product must meet specific needs, which are not relevant on the markets currently served by the industrial partner. First, the product must be defined according to European standards and considering European concerns, in particular with respect to the determination of the characteristic opening size. Second, the product should offer an enhanced resistance to iron-ochre formation.