Overburden drilling systems (rotary-percussive)
driven by hydraulic drifter

1. Drive drilling systems based on single casing with lost bits or wing bits. Suitable for grounds which can be displaced without flushing or which can be drilled (rotary-percussive) with flushing without the risk of creating caverns.

2. Overburden drilling systems based on duplex casings. Suitable for grounds including of hard rock, hard rock banks or gravel. Preferred flushing: water or water-air-mix.