Gulf Construction Online - Close the chapter on open trenching

Road Construction

Non-disruptive technology in focus … Powermole machinery in action on a project.

Close the chapter on open trenching

01 February 2000

No-dig technology can and should be more extensively used to restrict the use of the dated practice of open trenching, say experts Euro Iseki and Powermole International.

Digging up roads is outdated and sociably disruptive, and should not be the first method to crop up in the minds of contractors charged with laying pipe and cable, says Euro Iseki and Powermole International.

Chris Ratcliffe, PR and marketing co-ordinator of both the firms, elaborates: ''With directional drilling, impact moling, pipe ramming and bursting, there is a multiplicity of other technologies that can be used, in some cases much cheaper than digging a trench.

''However, open trenching appears to be still practised: in the UK, for instance, towards the end of 1999, there were a number of articles in the technical Press about the excessive use of open trenching . In particular, Kent County Council alleged that contractors installing fibre optic cable between London and the Continent were creating 'unacceptable delays and disruption to traffic as well as cutting through water mains, telephone lines and other utilities', in an article in the NCE issue of November 18.

''In an age where impact moling and directional drilling equipment have been in existence for the best part of three decades, nothing is being done to restrict the use of open trenching.

''In Germany, if a road would have to be closed to open trench, they directionally drill: for instance, in Cologne, Powermole International is using several dry horizontal directional drilling systems to install fibre optic cable on a major project.

''Generally, the Powermole/SE equipment is being used whenever conventional equipment has had difficulty in penetrating the ground. It is this sort of approach that should filter through into the market; at the moment there is enough no-dig technology available to avoid any road excavation.

''Digging up roads is not the only technique that directional drilling is helping to cut out. In Scotland, Powermole International has helped to keep an area of Aberdeenshire environmentally clean by using its dry system. The 903 was taken to Scotland at the end of 1998 to install an 18-mm high-density polyethylene pipe under the River Deveron at Turriff.

''Before the project began, the Scottish Environmental Agency was concerned that if the new pipeline were to go ahead using conventional bentonite systems, there could well be damage to the salmon, the river and the golf club.

''It was decided to use the Powermole/SE 903 system which uses compressed air with a small amount of biodegradable additive. This produces a filter cake and prevents the bore from collapsing.

''The system can go through ground with a compressive strength up to 250 MPa and has a pneumatic/percussive head which is automatically activated when in contact with hard rock.

''The pipeline, which was installed 44 miles from Aberdeen, was needed to replace the existing, fractured, cast iron main, lying on the river bed. In less than seven hours, the 903 had created a 180-m borehole underneath the river; during the rest of the week it opened up the bore large enough to install the polyethylene pipe.

''The total cost was considerably cheaper than other options, which included open trenching.''

Euro Iseki of the UK, which is part of the worldwide Iseki group, recently acquired Powermole International to boost its range of no-dig technologies (see GCM October, 1999).