Core samples were collected at the GTS for laboratory tests which examine the infiltration of hyperalkaline solutions through these cores. Tests were first carried out with normal Grimsel ground water to determine the hydraulic (e.g. transmissivity) and retardation properties of the core. The same sample was then subject to 6 months circulation of a hyperalkaline solution and changes to the hydraulic and retardation properties of the core were observed for the 6 month period in conjunction with monitoring the chemical composition of the outflowing water

The set up of the lab experiments can be seen below:

The rock core is approximately 30cm in length

Preliminary results of the core infiltration experiments

Although the core infiltration experiments are still ongoing, they have already provided some of the technical input for the in-situ experiment.

Results so far show a clear rise in both pH and electrical conductivity of the outflowing solution as the high pH solution penetrates the core.

Also, changes to the chemical composition of the outflowing solution can be observed and these studies have been complemented with modelling of these experiments.

Once the infiltration techniques are complete, the cores will be opened and subject to a mineralogical analysis to examine if any secondary minerals were produced from dissolution of primary minerals in the core.