Auger boring is the preferred means of installation for on – grade gravity sewer and water lines, trenchless crossings of 600 feet or less, boring in consistent soil conditions, and when ground settlement of any kind is not permitted. By continuously supporting the excavated ground with steel casing pipe the possibility of lost ground is diminished. Boring in hard rock and granite ranging to 35,000 psi can also be accomplished with this method.
Turn – Key Tunneling performed a 470 linear foot bore of 36″ casing in rock for a sanitary sewer in Cincinnati, Oh. At the time of its completion, it was the longest known sanitary sewer bore utilizing a small boring unit.