Two Herrenknecht TBMs for the Jucar-Vinalopo Water SchemeThe Jucar-Vinalopo aqueduct will transfer 80 million cubic metres of water a year from the Jucar river to the Upper and Medium Vinalopo, Alacanti and Baja Marina regions. The water of the Jucar river basin, west of Valencia will be transferred from Cortes-2 dam to the dry coastal regions around Murcia, Alicante and Benidorm in Alicante province. The Jucar river basin, with a surface of almost 22,500 sq km, is located in east Spain. The region has abundant groundwater resources and is one of the few Spanish regions where the water reserves exceed the local demand. The objective of the water transfer scheme is to alleviate the overuse of the water resources and solve the deficit in water supplied to the recipient areas, which have been historically affected by the lack of water. The Jucar-Vinalopo water transfer project has seven sections, four of which require tunnelling works. It is a 67 km water pipeline, of which 26 km run in tunnel and the remaining 41 km in buried pipes.Construction of section II 'Cuesta' has been awarded to a JV of OHL and Serrano Aznar Obras Publicas, for EUR41.9 million and a time frame of 34 months. This section includes a 12.3 km tunnel. Intecsa-Inarsa will manage the construction and control quality, for EUR865,200. Section III 'Los Machos' has been awarded to Necso for EUR33.7 million and a time frame of 31 months. There is a 11 km tunnel on this section. A EUR854,480 contract for the technical management and quality control was commissioned to Eptisa.To excavate these two sections, the builders have invested in two Herrenknecht 3.37 m-diameter double shield TBMs to start work in six weeks time. They will be used to drive the water duct in dolomites, limestone, siltstone and marls across Los Machos mountains and El Caroig massif. Herrenknecht R&D engineers specially designed the two 170 m-long machines to operate them in conventional or continuous mode depending on the ground conditions. They had to integrate the complex process technology of a double shield TBM into a microtunnelling machine design, a real challenge with a shield diameter of only 2.95 m. The advantage of the double shield technology is the versatility of adaptation to varying ground conditions. In solid rock, the machines can install the concrete segmental rings thanks to the special gripping process. When entering and passing through fault zones, the operating mode can be changed to conventional shield drive, providing maximum safety for the staff, the machines and the tunnel. To optimally prepare the cutterheads for the long drives in hard rock formations and to limit the number of cutter changes during excavation, the cutterheads have been equipped with large 17" cutters. Up to now, such powerful machines are unparalleled in this diameter range. The tunnel will be lined with five segments plus the key. A delivery ceremony of the machines was held on 22nd February, 2005 at Herrenknecht in Germany with representatives of the client and contractors. Visit www.herrenknecht.comThere will be other underground works, although not with TBMs, on sections I and IV. Section I has two raise boring structures and some length in tunnel. Its construction was awarded to Corsan-Corviam, Befesa and Romymar. Section IV 'Navalón' has been awarded to a JV between Ferrovial Agroman and Sedesa Obras y Servicios for EUR23.8 million and a time frame of 29 months. This section requires the execution of 2.5 km of cut-and-cover tunnel. A JV set up by Eyser and Inclam Ingenieria del Agua will be responsible for the work management and quality control, for EUR753,760. Visit www.aguas-jucar.es 09/05. Click to enlarge