AWWA DSS92008

One form of trenchless construction is commonly referred to as directional drilling, or, more properly, directionally controlled horizontal drilling. This technology can be used to install pipelines beneath rivers or other obstructions without resorting to trenching or other excavations. This is a multistage process. The first step involves drilling a pilot hole from one side of the river to the other. After the pilot hole is completed, the bore is enlarged by pulling back a reamer or hole opener. Two or three passes with progressively larger reamers may be necessary. A mini directional driller can be used for small pipelines installed in short distances. Following details on the process of directional drilling and a comparison of direction and mini directional drilling, five very brief case studies are offered.