Drilling of a large diameter borehole (20’’, 17 ½’’ and final diameter 12 ¼’’ ) with down-the-hole-hammer technique for the installation of screens and casings for the dewatering of an open cast gold mine in Ghana (Westafrica)
Drilling of a large diameter borehole
(final diameter 20’’ ) in suction drilling technique for the installation of gravelpack screens for dewatering an open cast lignite mine in Serbia