Improvement of the functionality of geotextile filtration systems in hydraulic engineering in case of ochre clogging tendency

 

Description and goals

In the area of waterways, geotextile filters are installed beneath revetments as an economical and safe alternative to mineral grain filters in order to compensate changing water levels in a filter-stable manner and to prevent material transport. Under certain boundary conditions, ochre clogging can lead to the colmation of the filters, which impairs their hydraulic filtration efficiency and can lead to the built-up of water pressures. To date, ochre clogging in the filters cannot be reduced or reversed by technical measures. As there are no systematic studies available on the boundary conditions under which this process occurs in filters, ochre clogging and its effect on the service life of geotextiles is not dealt with in detail in the guidelines for the application of geotextiles.

Therefore, the aim of the project is to improve the understanding of the process of ochre clogging in geotextile and mineral filters in order to be able to make statements on the functional efficiency and service lifetime of the filters. Therewith measures for the reduction of ochre clogging shall be derived.

  Copyright: © IWW Experimental facility that was used to investigate ochre clogging in wells, which is modified within the project and used to investigate ochre clogging in filters under revetments

In order to achieve the project goals, the process of chemical ochre clogging is simulated in the laboratory under controlled conditions. The ochre clogging is generated in an accelerated manner under variable hydraulic and geochemical boundary conditions in a laboratory model representing a section of the embankment of a waterway. The effects will be described by determining the iron content and the relevant chemical parameters at several points in the model as well as by measuring the permeability in the soil and filter and analyzing the temporal change of these parameters during ochre clogging.

 

Partners and funding

The research project is carried out in cooperation with the Institute for Infrastructure, Water, Resources and Environment (IWARU) of the FH Münster University of Applied Sciences and is technically accompanied by the Federal Waterways Engineering and Research Institute and NAUE GmbH & Co. KG.

The project is funded by the Federal Waterways Engineering and Research Institute.