In 2015, AAI drilled two 330-foot vertical HQ (3.875-inch diameter) holes into the historical abandoned workings in the Allen Seam at Cline Mining Company’s New Elk Coal Mine located outside of Trinidad, Colorado, using AAI’s Ingetrol 75E electro-hydraulic drill rig. Both holes were drilled underground from the overlying Blue Seam workings. The holes were drilled as water drain holes. Ground conditions in the underlying Allen Seam were highly deteriorated, including numerous roof falls, broken roof strata, and rubbilized material filling entries in many locations. The bad ground was drilled successfully. The second hole was completed as a primary drain hole with 3.0-inch-diameter flush-joint polyvinyl chloride (PVC) casing.
Additionally, AAI’s technical staff managed a surface-based drilling program to intercept historical mine workings at the New Elk Mine simultaneous to the underground portion described above. Mine voids were intercepted as planned and used for containment of slurry from the coal preparation plant.