One method used was horizontal directional drilling (HDD), which is a steerable method of installing pipes that takes place underground, from one staging area to another, without disturbing the areas above ground. In the case of the Discovery Corridor pipeline, the technology was used to install a 16″ diameter pipeline across the Interstate 5 off-ramp without any traffic impacts.
Other trenchless techniques used on the DCWTS project included horizontal auger boring, commonly referred to as “jack and bore,” and pipe bursting.
Pipe bursting involves laying pipe by pulling a device that is slightly larger than the existing pipe through, breaking the existing pipe and expanding the opening. Along the way, a new larger diameter pipe is pulled through the opening. For the DCWTS project, pipe bursting was used in an arterial road along a busy retail corridor, which limited the impacts of construction on local businesses.