The drilling technique we use is a Rotary Mud System. On larger diameter bores, a top starter casing will be cable tooled into place using a crane. This is to isolate upper ground materials/water from the main bore. The main bore drilling follows and the hole is held open with drilling mud. As the cuttings are pumped from the bore they travel across a shale shaker screen and the cutting material is recorded. This record is referred to as the bore log. When a water bearing aquifer is discovered, a sample of material is taken to determine the slot size of the well screen. Casing is installed down to the aquifer and the screen is lowered inside the casing and locked into place.