The “Nuovo Scillato” water pipe is one of the main supply lines of the Sicilian capital Palermo and the coastal communities east. Since the 1980s it has been supporting the old water supply system “Vecchio Canale Sciallato”, which has been in operation since the late 19th century. Every year, the 62-km-long steel pipeline transports around 22 million m³ of water to the Palermo region with a variable flow rate of between 500 and 1,000 l/s.
Since 2003, repeated and more frequent earth movements took their toll on a segment of pipeline. The result: Frequent interruptions in the water supply. Droughts in the past two years and problems at the Rosamarina Dam, from which Palermo receives approximately 30 million m³ of water every year, also significantly reduced the available water reserves.
Tailored relining solution for high pressure pipeline
A new route outside the sensitive area will remedy this situation in the future, but is still under construction. To secure the supply of drinking water until completion, the operator AMAP decided in January 2017 to set up a transitional solution at the “Nuovo Scillato” using a trenchless system. Using a georadar, Primus Line’s Italian installation partner Danphix first examined the affected sections of the DN 900 steel pipe and determined small shifts at some points. In addition, the aerial photographs from a drone provided orthophotomaps for an accurate picture of the environment. For the rehabilitation sections with lengths of 640, 520 and 510 m, Danphix developed a tailor-made relining solution based on trenchless Primus Line® technology, using this precise information, which has a flow rate of 400 - 500 l/s and thus achieves an annual volume of 15 million m³ of water.
Given its great flexibility and high stability, Primus Line® is ideally suited for this demanding application. Thanks to the compact transport drums, the Primus Liners were able to directly reach the excavation pits, which were difficult to access, and now enable the high pressure of 25 - 30 bar during operation.
Three Primus Liners installed in parallel in one go
In preparation for the rehabilitation work with Primus Line®, Danphix excavated and realigned the shifted pipe sections of the “Nuovo Scillato”. This made it possible to install the 3-in-1 solution, which required the parallel insertion of three Primus Line® DN 250 PN 30 and Primus Line® DN 300 PN 25 respectively. For this purpose, the installation team placed the transport drums one behind the other and connected the three flat liners to a secure bundle before entering the existing pipe with adhesive tape.
The transitions between the Primus Liners and the connectors and venting devices especially made for this application are reinforced by support structures made of structural steel, which are welded to the existing pipes. In the case of new earth movements, they protect the liners from direct contact with steel parts.
With the completion of the worldwide, to date unique, rehabilitation of a high-pressure water pipeline by the use of three parallel liners with a total length of around 1.7 km, the Sicilian city can be much more relaxed about the water supply situation next summer. At the inauguration, Palermo’s mayor Leoluca Orlando and AMAP president Maria Prestigiacomo were extremely pleased with the speedy completion within two months and praised the services of Danphix and Primus Line.
