In-situ chemical osmosis experiment in boom clay at the underground research laboratory of Mol

Clay rich layers have traditionally been regarded as natural protective covers in regional aquifers because of their low permeability. In the absence of water conducting features, these deposits provide the low flow environment required for waste containment. Comprehensive understanding of the physical and chemical processes that control water and solute transport through low permeability argillaceous formations and to the environment is a key factor for assessing their suitability as host rocks. The Boom Clay, an over consolidated marine Oligocene deposit, is considered as a potential host rock for radioactive waste disposal. For more than two decades, extensive hydraulic and hydrochemical research has been carried out in the Boom Clay at the HADES Underground Research Laboratory (URL) in Mol (Belgium). The main objective of the experiments conducted at the HADES URL has been to characterize the in-situ hydrogeological conditions, to determine the hydraulic parameters, and to study the mechanisms controlling the chemistry and the composition of the Boom Clay pore water. (authors)