Performance Assessment of Ongrade Horizontal Directional Drilling Method

Abstract

Horizontal Directional Drilling has been widely accepted and used for installing gas, water lines, telecommunication cables, etc. One area where HDD has achieved limited success is in the installation of gravity flow sewer lines. Primary reason is the difficulty with maintaining critical grades essential for gravity-flow sewer systems when using that conventional HDD tracking methods. Recently, advancements made in tracking systems, electronics, and operational techniques have made HDD technology a technically feasible and an economically attractive method for installing on-grade underground pipes. The newly developed technology illustrated in U.S. Patent 7,510,029 is one of representative techniques for accurate identification and tracking of the vertical location of drilling head. This study evaluates technical capabilities and the economic feasibilities of this new OnGrade HDD technology using actual project data. The accuracy in grade of installed pipe, operational cost, and user cost information associated with the project are compared to the open-cut method.