The data presented below show the pressure at selected instruments in some of the layers and the water content of the buffer monitored by the TDRs versus time.

The layers showed a heterogeneous response with Layers 8-10 saturating much more quickly than the others. This is thought to be due to presence of the gas visualisation tracer (Pb(NO3)2) which appears to decrease the bentonite swelling capacity.

After saturation, pressure was maintained in the Upper Cavern and a set of water tests was performed to characterise the EBS prior to the gas injection. These tests include pumping from inside the silo, the upper cavern and the gravel layer in the base of the cavern. A first series of gas injections was then performed with the injection rate increasing in 5 steps (RGI1-RGI3b). After this a repeat water test was performed and a second series of gas injections using tracers was completed prior to depressurisation and careful excavation of the EBS.

Roll mouse over the graph for more details about each phase, click for more details: