PlumeStop has little or no impact on groundwater velocity. The viscosity upon injection is very close to that of groundwater – any difference is negligible. Post application, the PlumeStop material coats the formation as a layer of micron-scale particles, and the impact on permeability of this in granular formation is negligible. Tests to date have detected no changes. Depending on the formation, we would nevertheless anticipate an eventual limit to this in certain cases, but the first of these would likely be fractured rock settings for example, rather than granular formations / alluvium etc.