Robbins TBM Digs Sewer Outfall in Northwest SpainThe project to clean up the Ferrol estuary represents an investment of EUR112 million, financed by the North of Spain water agency (85%) and Galicia's autonomous government (15%). It includes a wastewater treatment plant in Bens, a sea outfall, a crossing and conveyance system in La Malata, a pumping station and a land outfall in tunnel. The owner of the scheme is the Ministry of Environment, through the North of Spain water agency. The Cape Priorino wastewater treatment plant, awarded last July to Acciona Infraestructuras for a budget estimate of EUR54.5 million, is designed to treat water supplied to a population close to 156,000, which is the number predicted to be living in Ferrol, Naron and Neda in 2025. The WWTP will be located in Bens at the present location of the tunnel jobsite installations. The sea outfall, which is going to be put out to bid soon, will serve to convey sewer waters treated in the WWTP to an adequate point out at sea. For this, 1,000 metres of pipeline has been designed. The crossing and conveyance system in La Malata comprises a 1,159 m-long 1,800 mm pipeline and a pumping station with capacity for a volume of 6.5 cubic metres (or 6,500 litres/second) to lift the water 56 metres above to the entrance of the land outfall tunnel. The reinforced concrete pipeline has been designed to use gravity and will connect the pumping station with the chamber placed at the head of La Malata-Cape Priorino land outfall. The conveyance pipeline to the connection with the land outfall will span a total length of 89 metres. This pipeline consists basically of an open cut trench in which two 1,200 mm-diameter pipelines will be laid to transfer wastewater to the entrance mouth of the land outfall. From th at point, the wastewater will move by gravity along the outfall tunnel. The pumping station will be built on the right bank of La Malata. The works have been awarded to FCC. This project will have a cost of EUR18,645,456. Visit www.fcc.es Arrival of the Robbins TBM to the site Bolting The land outfall requires the construction of a tunnel, which will house the necessary hydraulic pipelines to transport by gravity sewage water fed by the pump in La Malata. The tunnel's length is 7,344 metres and will link up the La Malata station to the wastewater treatment plant. The land outfall contract also includes the construction of a ventilation shaft, approximately 200 m high and 1.8 m in diameter, located at chainage 4+136. The raise boring method is to be used. The contractor is Acciona Infraestructuras. Eptisa is responsible for the construction management. The investment for this project amounts to EUR37,158,983. Visit www.acciona-infraestructuras.es and www.eptisa.esThe tunnel actually in progress is bored with an open face TBM Robbins 1215-265. The outer diameter of the tunnel is 3.7 m and once lined with reinforced concrete, the tunnel diameter will be 3 m, since the lining has a thickness of 35 cm. The guidance system of the TBM has been supplied by PPS (Poltinger Precision Systems). Visit www.robbinstbm.com and www.pps-muc.de At the commencement of tunnelling of the outfall, resin bolts have been installed. The bolts, 1.3 m of length, were supplied by Tedesa and the resin by Minova-Codiv. At the moment, 1.5 m-long Swellex bolts supplied by Atlas Copco are being placed. Visit www.minova-ct.com, www.grupocodiv.com and www.swellex.comTH-16.5 steel arches, also supplied by Tedesa, are used together with metallic reinforcement rings, which shape a cladding similar to concrete segments placed by shield machines. These rings are supplied by Tunnel SpA of Italy. At the invert, a prefabricated segment produced by Prenava, based in Nava in Asturias, is installed. Very little shotcrete has been utilized in the tunnel. However, there is a shotcrete pump, a Tecnosol machine, while the mixer is a 6 cu m Schoema. In the centre of the tunnel, a conveyor belt gathers in containers the rock excavated by the machine. Crews use two 25-tonne Schoema locos with Schoema muck skips with bottom discharge for evacuation of the rock. Visit www.prenava.com and www.schoema-locos.de Miners work in 12-hour shifts, seven days in a row, then they rest for three days, get back to work for seven nights and rest for four days. Problems encountered during construction of the Cape Priorino wastewater tunnel have led to several stoppages that have obliged to reconsider the initial project and to work from both ends of the tunnel. This has implied a cost overrun of 20% compared with the original project.The length excavated as of 9th August, 2006 is 3,480.90 metres (47.4%), with 3,862.10 metres (52.6%) still to go. Tunnelling commenced on 26th August, 2004 and completion is scheduled for April 2007. Click here to read more. Read E-News Weekly 40/2003 & 17/2003. 38/06.