Pre-Construction Drillability Assessment for Horizontal Directional Drilling in Rock

This paper presents concepts that evolved through a research project sponsored by the Pipeline Research Council International (PRCI). The objective of the project was to investigate methods for the reduction of claims for extra compensation associated with horizontally directionally drilled (HDD) pipeline installations in rock. These claims result from HDD contractors' allegations that rock properties experienced during construction are significantly different from the properties on which the contractors' bids were based. The paper provides information and recommendations that improve exploration and testing methods for assessing the drillability of rock to be encountered on HDD pipeline installations. It is anticipated that these improvements will lead to a better understanding of rock drillability which will in turn lead to more accurate bid prices and more effective drilling plans, thereby reducing claims for extra compensation. The paper also addresses contractual and risk management considerations and alternate dispute resolution.