Cable-Tool Drilling

The cable-tool method uses an impact bit that crushes the soil material and rock it encounters. Periodically, the bit is removed and the crushed material is removed by using a bailer.

The bailer is a section of pipe smaller in diameter than the casing, with a check valve at the bottom. As the bailer is lowered, the check valve is left open and it fills with the crushed material. As it is lifted, the check valve closes so that the material can be lifted to the surface and discarded.