Arsenic-free water from shallow wells
Clay layers can form a separation layer between arsenic-contaminated and arsenic-free aquifers. During the drilling of wells, the sequence of layers in the subsurface is usually determined and clay layers are also located. In Bangladesh, however, this documentation is rather uncommon. Moreover, the drilling methods used make it difficult to determine these depths accurately.
In contrast, a gamma log, a geophysical method, can be used to detect the structure of the subsurface in old wells. The method measures the natural radioactivity occurring in the clay layers. Sands and gravels, on the other hand, show significantly less radiation.
With the loan of equipment from the University of Tübingen, the method can be applied by the University of Heidelberg. With the support of local helpers from AGAPE Bangladesh and the University of Dhaka, all wells in a village are now to be measured. With the help of the University of Hamburg, the data can then be evaluated in three dimensions.
There are no comparable projects yet. That is astonishing, because from our point of view only in this way the underground can be understood and there is a chance to install usable wells for all with justifiable means. If our attempt succeeds, this method can contribute to that. We are happy to be able to support this concentrated research front as an association.
The project will start in spring 2022. We are also supported from the industry by IGM Ingenieurgesellschaft für Geophysikalische Messtechnik mbH (Überlingen) and by FONTUS Logging Service (Pleinfeld). (20.12.2021)