Abstract: An earth contamination site groundwater testing well having a borehole which passes though subsurface soil zones of interest is provided with a probe assembly that is installed in the borehole, that has a core stem which carries spaced-apart flexible disc seals that divide the borehole into different borehole zones that correspond to the subsurface soil zones of interest, and that includes microporous sampler points in the different borehole zones. The groundwater testing well borehole may be formed with a well casing that is afterwards removed while retaining the probe assembly in position.