Civil and Building Engineering.

The use of wash borings is the most common method for advancing a boring because the technique is applicable to any soil, the depth is limited only by the equipment employed, samples can be taken with a variety of tools, and in situ tests can be performed as the borehole is advanced. A typical drilling
machine and its associated equipment are shown in Figure 4.2. The derrick is for handling the hollow drill pile that passes through a rotary table, powered by an engine with the necessary power. The hollow drill pipe carries an appropriate cutting tool. A surface casing is set with a T-section above the ground to direct the drilling water to a holding tank. A pump will drive water down the drill pile to raise the cuttings, which may be examined to gain an idea of the formation being drilled. The water is pumped from the top of the tank, with additional water provided as necessary. Drilling fluid can replace the water if caving occurs.

The system can be scaled up for drilling deeper holes and scaled down for hand operation. The Raymond Concrete Pile Company, now out of existence, distributed a movie for the classroom showing the use of a tripod, assembled on site, for raising and lowering the drill pipe by use of a pulley. A small gasoline engine rotated a capstan head used to apply tension to a rope that passed through the pulley to the drill pipe. A small gasoline pump picked up the drilling water from a tank or from an excavation on site. The entire system
could be transported with a light truck and assembled and operated by two workmen. The components of such a system are shown in Figure 4.3.