The core reveals what a drilling method must achieve in highly fractured rock. The fracture surfaces and fracture fillings must be preserved, the core must not break into fragments, and the drilling fluid must not wash out fine material from the fractures. STUBORE® continuously casings the borehole, thereby supporting the fractured zones. The inner, non-rotating core tube decouples the core from the drilling motion, thereby protecting it from twisting and breakage. The core was extracted by rotation, with targeted air or water flushing as needed. The cores remained usable and assignable to the correct depth throughout the entire depth, even in the intensively fractured sections of the Devonian strata.

The boreholes were located within the active quarry site of Basalt AG, where rock extraction and landfill operations take place simultaneously. Two of the three boreholes were equipped with 2-inch groundwater monitoring wells and provide data on the water balance.