Solid-Nose and Coring Thermal Drills for Temperate Ice

A generalized description is given of several hot-point drills, both coring and solid nose, which have been developed at the University of Washington for use in temperate ice. Drilling equipment is lightweight and readily transportable by small plane and hand-drawn toboggan, and has been used in support of research programs on Blue, Nisqually, and South Cascade Glaciers.

A coring hot-point drill is discussed which has been used to obtain continuous cores of firn and ice to depths of 90 m. The core is 15 cm in diameter, in lengths of 1.7 m, and its in situ orientation is determined with a remote-reading inclinometer located in the drill barrel.

Also discussed are solid-nose hot-points of several outside diameters which feature an inexpensive industrial cartridge heater which can be readily replaced in the field in case of burn-out. These drills range from 2.5 to 5 cm in diameter and advance at 6-8 m/hr utilizing 1000 to 2200 W. Depths of 210m have been achieved. A tapered hot-point reamer has also been developed utilizing a 2200-W heater. This device has been used to control borehole refreezing, and as an aid in retrieving coring or drilling equipment which has become jammed in the hole.

Performance recommendations are given for solid-nose hot-points based on an optimized thermal efficiency.