The results so far suggest that the shear zone was gradually blocked and increasingly fewer of the smaller fractures contributed to the flow field. Originally, the breakthrough curve was quite diffuse, due to transport in a wide range of water conducting features. The more recent breakthrough curves obtained show a much better defined peak and faster breakthrough times, suggesting focussing of the transport into a few larger fractures.

Graph of uranine (sodium fluoroscene dye) breakthrough since start of continuous high pH fluid injection

The evolution of injection pressure at constant rate pumping of 1 mL/min records a steady increase after the initial injection of high pH fluid. This pressure increase is a result of a gradual decrease in the overall transmissivity of the shear zone, presumably due to blocking of the smaller fractures (as noted above). A corresponding decrease in the passive outflow rate can be observed at the extraction site.