Geotextile containment for hydraulic and environmental engineering: Fid-Bau Portal

Geotextile containment for hydraulic and environmental engineering

Lawson, C.R.

Geotextile containment presents very interesting opportunities in the areas of hydraulic and marine engineering, and environmental engineering. The three basic containment units - tubes, containers and bags - can be applied to many applications. By containing sand and other similar materials geotextile tubes, containers and bags act as mass-gravity structures in hydraulic and marine applications. Sand, or like fill, is used for these applications because it does not undergo consolidation once installed and the units can maintain their existing shape and height. When installed in hydraulic and marine environments care is required especially if the geotextile containment structures are continually exposed over long periods of time. In these situations, aspects such as UV (ultraviolet) resistance, abrasion resistance and liquefaction of the sand fill need to be taken into account. Geotextile tubes and geotextile bags provide an efficient medium for the dewatering of waste streams and contaminated sediments. Their high contact surface area and good filtration characteristics, in addition to their simplicity, make them readily suited for this technique. The addition of chemical dewatering accelerants can enhance the rate of dewatering significantly and can trap contaminants within the dewatering waste. Other dewatering accelerant techniques, such as EKG (electrokinetic geosynthetics), offer interesting prospects in the future. To ensure success, the geotextile tube dewatering system needs to be designed hydraulically to ensure all components meet the capacity requirements. Also, the strengths and filling heights of the geotextile tubes must be closely controlled. Geotextile containers have demonstrated their ability to safely dispose of contaminated sediments in off-shore disposal facilities. This application is more severe on the geotextile container than the more conventional hydraulic and marine application because of the relative size of containers used, their dropping depth and the normally poor shear resistance of the contaminated fill. Ensuring the integrity of the geotextile container during installation requires the use of high strength geotextiles with high capacity seams, along with relatively small pore sizes to ensure negligible loss of fill.