A comparison of test methods adopted for assessing geotextile tube dewatering performance

Geotextile tubes have successfully been used by virtually every industry today to dewater a variety of sediments, slurries, by-products, and wastes. Despite this, the dewatering industry currently lacks uniformity in regards to establishing testing standards and assessing dewatering performance. Prior to full-scale tube deployment, lab and/or field tests are typically performed to evaluate performance. Preliminary bench tests such as the falling head test (FHT) and pressure filtration test (PFT) are often used to evaluate candidate polymers and dewatering efficiency. The mid-scale hanging bag test (HBT) and geotextile tube dewatering test (GDT) may then be used to visualize the dewatering process and evaluate the selected polymer. There is currently no industry standard, however, and numerous variations in testing programs, methods, and data interpretation exist. Before advanced studies can be undertaken, a common framework for data interpretation must be created by standardizing testing programs. Using a fine grained, non-plastic soil and woven geotextiles, this study aims to examine and compare the bench-scale and mid-scale test methods adopted for assessing dewatering performance. In addition to standardized testing programs, the need exists for estimating geotextile tube dewatering rates. This study proposes a theoretical model using Darcy's law and the Kozeny-Carman equation which allows for an estimation of dewatering time.