Enagas S.A. installed two offshore submarine pipelines - one 20" diameter pipe of approximately 123 km, defined as the West of Ibiza pipeline (WoI) between Denia (mainland Spain) and Ibiza, and the other a 20" diameter pipe of approximately 146 km defined as the East of Ibiza (EoI) pipeline between Ibiza and Mallorca. The main purpose of the pipelines is to supply the Balearic Islands of Ibiza and Mallorca with natural, sales quality gas. Tideway was responsible for dredging of the trench, constructing the landfalls, and protection and stabilisation of the pipeline.
At the Ibiza landfall at Punta de Cito Gracio, both WoI and the EoI pipeline were pulled ashore using a 300T linear winch and one 3.25" pulling wire. Both pipelines, when coming onshore passed a previously installed micro-tunnel, so no offshore dredging activities were executed.
Then at the Mallorca landfall in San Juan de Dios, the EoI pipeline was pulled to shore using a 500T linear winch. However, because of the limited amount of working area the linear winch could not be placed in line with the pipe. To overcome this problem Tideway used a horizontal deflection sheave to enable the winch to be placed at an angle with the pipeline and the designated work area. Furthermore, a trench was dredged to ensure a seamless pulling process and to create the required backfilling depth.
At the Denia landfall at Les Devesas, the WoI pipeline was pulled to shore using a 500T linear winch. A trench was dredged to ensure a seamless pulling process, as well as to create the required backfilling depth.
Tideway deployed a Backhoe Dredger and the Split Barge Trailing Suction Hopper Dredger and the DP Fallpipe Vessel Rollingstone. Tideway finally dredged 150,000 m3 of material and placed 20,000m3 rock at a depth of 987 meters.