Trenchless construction methods are becoming an increasingly popular option for pipeline installation projects due to their lower cost as well as reduced damage and disruption to sites.
The installation of pipes without trench excavation primarily employs a technique referred to as "pipe bursting," which involves the replacement of old pipelines with newer ones by means of destructive insertion.
The new replacement pipe enters the old pipe from one end at a launching or insertion pit. This new pipe is then dragged through the full length of the older pipe by means of a pulling cable and hydraulic winch situated at the other end of the pipeline route, in what is referred to as the reception pit.
As the new pipe makes its way through the line, a set of cutters slice and split open the old pipe, which is the source of the term "pipe bursting."
One of the main advantages of pipe bursting is that it dispenses with the need to excavate open trenches along the full length of the pipeline, a process which often requires the destruction of paved surfaces and creates major disruption to adjacent areas.
Some members of industry estimate that pipe bursting can reduce the cost of water or sewer pipe installation by as much a quarter, removing the need for the removal and replacement of asphalt paving which is so often a part of open-cut construction.
In North America, the method is increasingly being applied to larger-scale projects, with Vancouver Shipyards recently adopting it for the replacement of a large-diameter corrugated steel pipe with a length of 300 metres which had succumbed to corrosion and was filling with debris.
The project was divided into a trio of 100-metre sections, with relief pits excavated every 25 metres for the purpose of debris removal.
A Grundoburst Static Pipe Bursting System was then used to burst through the 900-millimetre diameter corrugated steel pipe, while simultaneously replacing it with a 1,050-millimetre diameter pipe made from high-density polyethylene.