North American Society for Trenchless Technology Conference 2015
The utilization of adequate amount of drilling fluid is widely recognized as a critical factor in the successful completion of a HDD crossing. At the same time, the overall price tag is influenced by the volume of drilling fluid usage. With contractors under pressure to keep per foot cost as low as possible, the practice of constructing a borehole 1.3 to 1.5 times the diameter of the pipe product of 24 in. or less, should be re-examined. The research work reported in this paper aimed at development and testing a new method that can reduce drilling fluid usage during HDD installations by up to 33%. Five (5) full-scale HDD bores were constructed. Two of the bores followed traditional installation procedures while the remaining three bores utilized a newly developed partial compaction reamer. Data collected during the installations included in-situ soil characteristics, borehole geometry, pulling force, borehole pressure, required thrust and torque, changes in the in-situ soil pressure immediately outside of the bore path, and the characteristics of the drilling fluids and cuttings. The analyzed test data is presented in tabular and graphical formats, and discussed in the context of installation time, risk and cost. A demonstration project in the New Orleans area where this new reaming technology is currently been considered as a means to address the requirements of the USACE is also described.