For West Park to remain operational throughout construction, EllisDon has spent several months re-routing underground service pipes for water, fire and sanitary lines that were running beneath the footprint of the new hospital. Now in the final stretches, construction crews are installing underground, sanitary and storm pipes between the Ruddy and Main Buildings, which requires a method called “directional drilling.”
Between the Ruddy and Main Buildings, an excavator was used to dig a pit (centre) and a directional drill rig was then lowered in by a crane.
So what is “directional drilling” and how does it work?
Directional drilling is a technique to drill at a non-vertical angle and commonly used to install underground utilities such as pipe, conduit or cables.
For most utility installations, an excavator is used to trench and then pipes are laid into the ground. But since there is a corridor that connects the Ruddy and Main Buildings, trenching would cause the corridor to collapse.
“An excavator can only dig vertically and we need a machine that can drill horizontally,” says LEGO Man, West Park’s mascot for construction. “So a directional drill is the best option. Plus it causes minimal disturbance to its environment, which is especially important since they’re drilling underneath buildings.”
According to Wikipedia, horizontal directional drilling is generally accomplished in three phases. First, a small diameter pilot hole is drilled along a directional path from one surface point to another. Secondly, the pilot hole is enlarged to a diameter that will facilitate installation of the pipeline. Lastly, the pipeline is pulled into the enlarged hole, thus creating a continuous segment of pipe underground.
In West Park’s case, the first and second steps occurred behind the Ruddy and Main Buildings where the Back Service Road has been closed. An excavator was used to dig a deep pit and a shoring box was installed to stabilize the soil. A crane was then brought onsite to lower the directional drill rig into the pit, so it can begin boring through to the other side. (Video Clip 1)
Then at the front of the Ruddy Building, construction crews connected a drill bit (the tip) to the pipe, so it can pull the pipe through the hole to the other side. (Video Clip 2 and 3)
Directional drilling has been around for many decades. But modern drilling techniques allow the use of drill bits that can bend with the use of hydraulic jets, which allow engineers to adjust the direction of drill and push through the dirt.
See the Action
Video Clip 1| Horizontal Directional Drilling behind Ruddy
Video Clip 2 | Connecting drill bit to pipe
Video Clip 3 | Connecting drill bit to pipe
About the Learn with LEGO Man Series
Want to know more about what's happening on the construction site? The Learn with LEGO Man (or Woman, when applicable) series will help explain the construction process throughout the build. Stay tuned for more...!