Insights on Desaturation Processes based on the Chemistry of Seepage Water from Boreholes in the Callovo-Oxfordian Argillaceous Rock

Seepage waters from boreholes were collected in the Meuse/Haute-Marne Underground Research Laboratory (NE France) in the Callovo-Oxfordian clay-rich host rock. Over the first months after the drilling of the boreholes, these waters were saltier than the waters collected later on, even in the boreholes that had been drilled without oxygen. These chemical composition variations give insights on the volume of rock affected by the loss of water around the boreholes. This data will help to characterize the desaturation processes in such a rock and the consequences with respect to the composition of the water that will fill the underground works after their closure.