Rehabilitating a Leaking Subaqueous Horizontal Directional Drill with an Innovative Trenchless Liner

Subaqueous horizontal directional drills (HDDs) require butt-fusion welding of the pipe joints to fuse the sections of piping together prior to pulling it into place. The fused joints are often stated by manufacturers to be stronger at these locations than the overall sections of piping, further reducing the potential of leaking at the joints. HDDs are typically pressure tested above ground but can also be pressure tested once pulled into place or pressured tested both times. Pressure testing of the HDDs should occur after the piping is pulled into place for final acceptance and assurances that no issues occurred during the installation process. What if an HDD passed the required pressure testing for clearance, was placed into operation, and subsequently was identified to be leaking? Further, what if this HDD was a subaqueous HDD for which the leaks could not readily be accessed due to the depth of installation and the inability to dig down and repair them with conventional open cut methods? This paper will discuss how an innovative trenchless liner was used to rehabilitate a leaking subaqueous HDD, present the construction considerations, and provide key items to review prior to project implementation.