Drilling Fluid/Mud

Water that may contain additives, including bentonite, polymers, soda ash, surfactants, or other materials, to enhance stability and excavatability. If the drilling fluid contains additives, it is considered to be engineered drilling fluid, whether specified by the engineer or selected by the contractor. Some additives may increase the effectiveness of the drilling fluid and reduce adhesion of the spoils (cuttings). The drilling fluid is used in a closed-loop system for transporting spoils and for counterbalancing earth and groundwater pressures during microtunneling.

Dripper

Applied to infiltration to quantify water dripping into a sewer in a non-continuous way through a defect or faulty joint.

Drive

Designation of the pipe installed from a jacking shaft to a reception shaft.

Drive Chuck

The female hex connector located within the casing pusher.

Drive Shaft

See Jacking ShaftExcavation from which trenchless technology equipment is launched for the installation of a pipeline. The jacking shaft may incorporate a thrust wall to spread reaction loads to the ground and an entry ring to control inflows of groundwater and soil at the portal..