[en] Basalt Waste Isolation Project (BWIP) borehole drilling and Exploratory Shaft Test Facility (ESTF) development involve minor localized impacts on the site hydrogeologic system. These impacts are in the form of voids created by the penetrations of the natural geologic site barriers and increases in the permeability of adjacent rock. Long-term impacts of borehole drilling and the ESTF can be minimized through carefully controlled siting, design specifications, construction techniques, and through the design of an effective borehole plugging system. 9 refs., 3 figs., 1 tab