Dry Boring Calms Environmental Worries

Over the past few months works have been in progress in the Liguria region of Italy for the installation wide band, fibreoptic and other networks for Telecom, the Italian state-owned telecommunications company. Telecom, which is currently on the run-up to privatization, is expecting strong competition from both domestic and foreign companies entering the Italian market subsequent to the privatization of the industry. Because of this the company is installing the new networks to ensure the maintenance of its position as leader in the domestic market.

The Liguria region of Italy has been of specific interest recently with several such projects being planned and executed. The region has some special characteristics, being positioned between the sea and a range of high mountains, which led to many of the local authorities requesting that no-dig techniques be utilised for the installation works.

In Genova, the regions main town, some 1,000 m of Telecom cables have already been installed using trenchless techniques and for the region as a whole some 1,600 m had been completed by the end of 1997.

Further plans are in place for the installation of some 1,500 m of network using no-dig methods in the west of Liguria between Imperia and Pontedassio. Meanwhile to the east of Genova there are plans to install some 500 m of cable from Sestri Levante to Casarza Ligure, and 1,000 m at Avegno where specific ground and local environmental conditions require the use of trenchless systems.

In La Spezia, between mid October and mid November 1997, a total of 80 m of cable was installed using trenchless techniques as part of the Socrate I and II programmes. These fibre optic installation programmes are being completed using an SE 503 HY-D directional boring system manufactured by SE Tecnologie Avanzate of Ortona, Italy. The system operated using a Holman C100-D air compressor.

The drilling unit has a pullback and thrust capacity of 12,800 kg and 10,800 kg respectively and a torque of 530 kgm and is one of a wide range of boring systems manufactured by SE Tecnologie. The systems are claimed to be an innovative design for directional drilling in rock without the use of drilling mud. The use of such a system is currently a regular request and a preferred option in many Italian areas because of the perceived potential risks of using drilling muds such as pollution, environmental damage, and flooding.

Works in La Spezia were awarded to Alcatel Italia by Telecom. Alcatel then subcontracted the drilling work to Tunnelling Service of La Spezia with technical supervision being the responsibility of F.lli Esposito Srl of Nola, a company which is operating on another nine projects throughout Italy.

The 80 m of dry drilling installation was carried out successfully in just a few hours and is seen as a prelude to other works in the area using the same technique. This initial project has been followed with great interest by several parties with many visitors to the site including Mr Franco Roscini whose responsibilities cover the Telecom Italia network, Mr Francesco Porcu from Telecom Italia (Genova), Mr Roberto DAlessandro the local Alcatel Italia representative, Mr Giorgio Basso the head of Tunnelling Service, Mr Piero Berardi of SE Tecnologie Avanzate. There were two other observers on the project from U.K.based Powermole International Ltd. Mr Alan Keyes (Technical Director) and Mr Mike Hall (Area Sales Manager).

Boring System
The basis of operation of the SE Tecnologie boring system is the use of a directional boring head with a percussion system. The unit operates using compressed air to drive both thrust and pullback actions as well as rotation and percussion at the drill head. Spoil is removed by the compressed air flow through the bore hole. Tracking is achieved using similar techniques to systems using liquid drilling fluids but the electronic sonde in the head has to be fitted with a shock absorber to dampen the effects of the percussion system.

The manufacturer claims that the system can be used to drill all soil types and that further advantages include no requirement for a mud mixing plant, no bentonite requirement and therefore no fluid losses to the ground, a very small operational footprint is required for each set up, and yet a high performance during installation.

by Ian Clarke - NDI Editor