Digging Deeper Into Trenchless Technology

    Trenchless technology consists of a variety of methods, materials, and equipment for inspection, stabilization, rehabilitation, and replacement of existing culverts and installation of new culverts with a minimum of excavation from the ground surface. Trenchless methods minimize damage to the highway, cause little or no disruption to traffic, have less impact on the environment, and occasionally avoid or minimize the handling and disposal of contaminated soils. According to a study published in the International Journal of Scientific Research in Science, Engineering and Technology (ijsrset), trenchless methods can be cost-effective alternatives to the more conventional open excavation. 

    The cost is insensitive to depth of cover meaning that work under high fills will be more economical using trenchless technology. Many times the cost is not the main concern; factors such as safety, inconvenience to the motoring public, and environmental impacts outweigh the initial costs. The trenchless technology process starts with the identification of a problem such as a drainage structure that requires some sort of repair. It may need stabilization, rehabilitation, or replacement. The most applicable methods of trenchless pipe replacement are:

    “Trenchless applications have achieved a very high level of precision due to the progressive development of equipment and method technology”

    Pipe Bursting
    Using pneumatic, hydraulic expansion, or static pull systems techniques that fracture a pipe and displace the fragments outwards, allowing a new pipe to be drawn in to replace the old pipe.

    Pipe Implosion
    A technique that fractures the pipe inwards prior to the outward displacement of the pipe fragments.

    Pipe Splitting
    Used to split open existing ductile pipes to allow a new pipe to be drawn in to replace the old pipe.

    Pipe Eating
    Uses a specially-designed variant of a micro-tunneling machine that excavates the old pipe in fragments and removes them rather than displaces them - the new pipe is jacked into place as in a micro-tunneling operation.

    Pipe Reaming
    Uses a specially-designed variation of the reaming process used in horizontal directional drilling to excavate the old pipe in fragments and removes them rather than displaces them - the new pipe is pulled into position behind the reaming head.

    Pipe Ejection
    The old pipe is jacked out towards a receiving manhole or excavation where it is broken up and removed the new pipe is used to eject the old pipe. Trenchless applications have achieved a very high level of precision due to the progressive development of equipment and method technology and this has made the execution of practically all types of supply and disposal lines possible, irrespective of their sizes or the geological and hydro geological limiting conditions in an ecologically friendly and enclosed method of underground construction. Where employers have fully recognized and utilized the possibilities of this technology, they have not been slow in reaping the economic rewards. Crossings of major rivers for laying telecom cables and product pipelines for oil and gas across major rivers at breakneck speeds have yielded good economic results for such employers. One look at such rivers and one can understand the importance and relative benefits of trenchless technology over the conventional construction methods. By Using Trenchless Technology one can achieve reduction of disruptions to traffic and movement, danger to existing underground facilities while developing or managing networks, easement requirements, environmental impact of dust and noise, potential for settlement damage, potential of injuries due to open excavations and required time & time related costs. In cities and urban areas, water and sewage infrastructure and other utility services located underground in pipes or ducts are laid, repaired or replaced by the conventional trenching methods. The open cut trenching methods create road closures, traffic delays, noises and general disruption. This makes repair and rehabilitation of subsurface utilities difficult, particularly in areas congested with traffic and buildings. Lack of repair and rehabilitation of the pipeline for the water disruption and sewage systems lead to leakages and wastewater seepages, resulting in the contamination of water distribution system and groundwater. These problems often give rise to related health and environmental impacts. The demand for alternative technology leads to the emergence of trenchless technology, which includes a family of methods utilized for installing and rehabilitating underground utility systems with minimum ground surface disruption and destruction as compared to open cut excavation methods. Trenchless technologies and methods provide an effective, environmentally sound alternative for the installation, maintenance and repair of underground utility services. The appropriate application of trenchless technology for resolving both engineering and environmental problems can be viewed as environmentally sound technologies. In addressing urban sanitation problems, trenchless technologies have the potential to yield significant environmental and other benefits such as employment opportunities, reduced inconvenience to commuters, reduced fuel consumption, and improved traffic flow. The development of trenchless technology was initially undertaken to meet specific needs in different industries and in different parts of the world. For example, research into micro tunneling in Japan was in response to a government initiative aimed at increasing sewer services in large cities. Similarly, in Singapore, government regulations and the need to provide services in densely populated areas led to the promotion and use of micro-tunneling. In Europe, research into micro-tunneling was sponsored by the German government for use in large cities on the North German Plain were ground conditions were favorable. In the United Kingdom, where the large towns and cities had been built during the industrial revolution in the 19th Century, the principal need was to replace and rehabilitate ageing sewers, water pipes and cast iron gas mains. In addition, the use of natural gas at higher pressures encourages the development of pipe-bursting techniques. In North America, horizontal directional drilling, developed from vertical oil wells after the reservoir yield reduced, became widely used for constructing long pipelines for the oil industry.

    Sai Kumar Daddala
    Munasir Mohidin
    Indian Society of Trenchless Technology (INDSTT)
    Mewar University