Dr. Stefan Niewerth – Active Geocomposite Barriers for Subaqueous Capping – October 2020

During this one hour webinar Dr. Stefan Niewerth will discuss Active geocomposite for subaqueous capping.

Webinar Description

Dr. Stefan Niewerth will discuss Active geocomposite for subaqueous capping in this webinar.

Subaqueous contamination in waterbodies close to former industrial sites pose a threat to the environment. The contaminants found at these sites have low solubility products and therefore stay in place, resulting in low but steady contamination of the water over a long period of time. To remediate these sites, there are different clean-up options. One is to dredge and dewater contaminated sediments. This technique is useful when the level of contamination is high. However, it is associated with high energy consumption for the dredger and also for dewatering. To reduce electrical energy and costs dewatering tubes are well established. Active in-situ capping can also be a suitable solution to deal with this problem. Sand and active materials, such as activated carbon, is used to cap the contaminants on site and isolate them from the water.

The problem with subaqueous installation of granular material is that it involves a high installation expenses, as the capping material slowly sediments to the ground and needs to be monitored for example by divers to check a proper placement. Also currents and underwater inclinations complicate the installation. Especially when using bulk active materials a high coefficient of safety needs to be applied to ensure a minimum active layer thickness throughout the entire cap. The combination of active materials and geotextiles can be an alternative solution for the treatment of subaqueous contaminated sites. The combination ensures easier installation and less needed material as a constant layer thickness can be guaranteed independently from water currents and inclinations. To protect the geocomposite a robust covering has to be installed over it. For this, concrete filled mattresses can be a feasible solution. Compared with a bulk protection layer it has similar advantages to a geocomposite.

Key takeaways

  • Different types of active geocomposites
  • Functions of active material
  • Design of subaqueous caps
  • Challenges in subaqueous capping
  • Installation process of active geocomposites exemplified


About the presenter

Stefan has a master and doctoral degree in civil engineering. He has worked on research projects in geotechnics and construction management. In his dissertation he developed an awarding model for public construction projects with which operational and environmental award criteria can – beside the price – be taken into account in a legally watertight manner. He then worked for a contractor and was involved in different construction projects.

At HUESKER Synthetic he has been working in Business Development for Environmental Engineering since January 2020. He takes care of the technical support in capping projects worldwide and the further development of active geocomposites.