Fluorescent microspheres in particle migration studies during geotextile dewatering: Proof of concept

Understanding the mobility of small particles in geotextile dewatering applications is important when considering highly toxic sediments containing dioxins and furans. These contaminants are often strongly associated with organic matter that are colloidal in size. Microspheres have been used in the soil science research community for tracking the mobility of colloids through porous media for various applications (e.g., bacteria, virus). In this paper, the use of microspheres as a surrogate for small particles (2 mu m) in geotextile dewatering tests is investigate. Establishment of a reliable and repeatable method for microsphere visualization with a microscope is presented, both for detection and quantification. A simple geotextile dewatering test is conducted in which a soil filter cake is established and the microspheres are passed through the filter cake, followed by the passing of distilled water. It is shown that the microspheres in the effluent can help assist in better understanding the transport of small particles during dewatering which can help us better understand risk of particle transport in these types of tests.