The traditional method of installing underground facilities like water lines, sewer lines, electrical cables and other utilities is to dig open trenches to the required levels, and then backfilling them after the work is completed. This process causes a complete disruption of the area and can lead to many problems for traffic, safety, and other aspects.
A trenchless method for construction of underground facilities, also known as micro tunneling helps to greatly reduce the inconvenience caused by open and deep trenches. A guided boring system uses a remote control to operate the boring machines. A guidance system is used to correctly position the utility in its required alignment, while the pipes are placed in position by jacking them into place. It is required to balance groundwater and earth pressures by exerting continuous pressure at the face of the excavation made for the machines.
In a guided boring system, the machinery is installed in a pit that is on the alignment of the required utility and at the correct depth. Guidance can be enabled by lasers or other techniques that ensure that the boring is carried out in the required alignment and depth. A pilot tube displaces soil as it is moved forward by augers that pull the tube into place. This method is suitable for soils that can be easily displaced. It is possible to install pipes up to a distance of 120 meters with this method. Inspection chambers or manholes are positioned at these distances and the same can also be used to extend the pipelines in the required direction. These spots can suitably be used for changing of direction or alignment.
Guided systems are useful for installing smaller diameter pipes where precision is important for the right grade, as in the case of sewer lines that operate by gravity. Pilot tubes are installed behind pilot heads and the drilling is continued to the exit point. A reaming head that has the required diameter, is then installed behind the pilot tubes. As the auger with the required pipes moves forward, a required section of the pilot tube is removed. The augers need to be of the same size as the outside diameter of the pipes that need to be installed. Pilot tubes help to install the final pipe in the correct alignment. These systems allow for very exacting tolerances which are demanded during the laying of sewers.