Major trenchless project on Sardinia realised with Primus Line®

The dimension of this 3-million-euro project has a signal effect: Trenchless technologies for the rehabilitation of pressure pipelines are quite suitable and useful as a complete solution for comprehensive reconstruction projects. Their performance is by no means exhausted with the rehabilitation of individual, smaller critical points in the course of a pipeline, such as the crossing of a traffic route.

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The initial situation

The ageing of the DN 500 water main led to frequent breaks with water leakages. The repairs repeatedly led to interruptions in the water supply to the municipality of Bosa with around 8,000 inhabitants and the surrounding region, which is also a tourist attraction. Since this is the only source of supply, the construction of a bypass was planned for the duration of the rehabilitation project.

The choice of the rehabilitation method and the implementation were also influenced by the nature of the pipe made of asbestos cement. In Italy, as in many countries, asbestos-cement pipes were used for the construction of water networks as of 1916. Especially between the 1950's and 1980's, their use continued steadily due to their "optimal" characteristics, unsuspected of the dangers of asbestos fibres. Its extension in Italy is estimated at about 125,000 kilometres with diameters ranging from 150 to 500 millimetres.

However, the decisive factor in the choice of the rehabilitation technology was ultimately the orography of the Temo river valley, through which the six kilometre long remediation section runs. The area between the start point, a bird watching area, and the end point at a dam is protected by numerous environmental regulations and has no public access roads.

Under these conditions, an open rehabilitation of the pipeline was impossible and ruled out from the start. But planning an intervention with trenchless technologies was also extremely difficult and quite daring. It took the high degree of specialisation and close cooperation of Benassi Srl and the manufacturer Rädlinger primus line GmbH for a smooth and high-quality execution of the project.