This unplanned release is called "inadvertent return." The mud can sometimes surface elsewhere through natural cracks. Normally, the drilling mud stays in the tunnel, and around entry and exit points. Like anything, HDD is not 100 per cent risk-free. HDD is used to reduce or avoid environmental impact. Depending on the location, local, provincial or federal permits may be needed.Įnbridge plans and performs HDD crossings to exacting standards, and meets or exceeds NEB demands. Pipeline design and construction are regulated by the National Energy Board. Timetables can, of course, be affected by surprise conditions. There is an estimated completion time for any specific drill site. Sometimes, drilling is completed in just a few weeks. The drilling time depends on the distance, geology and pipeline diameter. Construction crews reduce noise by using structures that are designed to cut down sound levels. Whenever possible, companies such as Enbridge will restrict activity to daylight hours if the equipment is close to occupied buildings.
How Will Directional Drilling Affect You?ĭrilling equipment creates noise. And any land around the drill entry and exit will be restored to its pre-drill state. It reduces impact on the area above the drill. This is all done in a way that minimizes environmental and stakeholder impact.įor large rivers or sensitive crossings, directional drilling is often the ideal method. After completion, they replace the soil as a restoration process. Construction crews clear a route, dig a trench and lower in the welded sections of pipeline. Long-distance underground pipelines are built across open areas, like rural farmland. The two ends of the segment will then be welded together with the rest of the pipeline system. They have a first layer of coating to prevent corrosion, and a second scrape-resistant layer to protect the pipe during the pull. Once the tunnel is 30 cm (12 inches) wider than the diameter of the pipe, the pipeline segment can be pulled through.
This drilling mud coats the walls of the tunnel and removes drill cuttings. This ensures that the angle, depth, and exit point are precise.ĭuring drilling, the tunnel is lubricated with a natural, non-toxic substance that’s roughly 95 per cent water and five per cent bentonite clay. A drill head guides the drilling pipe electronically. The tunnel follows an arc from the entry point, down under the crossing area, and then comes up on the other side.
Horizontal Directional Drilling (HDD) is a construction technique in which a tunnel is drilled under a waterway or other area and a pipeline is pulled through it. HDD is often the best method for sensitive river crossings
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