Kops II Hydro Nears Completion in AustriaIn west Austria, construction of the new 450 MW Kops II pumped storage power plant by Vorarlberger Illwerke, the project owner, is nearing completion and as built reports and plans are being prepared for the environmental impact assessment. The new facility is built in the catchment area of the Ill river in Vorarlberg. The upper reservoir is the existing Kops reservoir with a top storage water level of 1,811 metres and the tail water reservoir is the existing balancing Rifa reservoir with a top storage water level of 1,007 metres. Construction started in September 2004. The first hydroelectric set is expected to supply electricity to the grid at the end of 2007 and the last of the three hydroelectric sets is due to start operation during the first half of 2008. The Kops II plant will partner with the existing 247 MW Kops hydropower plant, commissioned in 1969. Click at/60. Visit www.kopswerk2.at/downloads/Folder_061006_englisch.pdfDescriptionAll components of the Kops II power plant are situated underground and consist of the following: intake structure in the Kops reservoir valve chamber with two butterfly valves and a bypass shaft for pump mode 5.5 km-long, 4.9 m-inner diameter pressure tunnel two-chamber surge tank consisting of a 235 m-long 6,2 m-inner diameter upper chamber with a capacity of 7,000 cubic metres, a 250 m-long 7 m-inner diameter lower chamber with a capacity of 11,000 cubic metres and a 185 m-deep 5,1 m-inner diameter inclined connecting shaft and a capacity of 4,000 cubic metres. Two connections designed as throttles are situated between the lower chamber and the pressure tunnel and a further throttle is located at the transition of the lower chamber to the inclined shaft. The lower chamber is steel lined, all other parts above the throttle at the toe of the inclined shaft are lined with in-situ concrete. 1,200 m-long, 3.8 m-inner diameter steel lined pressure shaft (penstock) high-head manifold piping 60.5 m-high, 30.5 m-wide and 88 m-long underground power house in cavern, with three hydroelectric sets consisting each of a turbine, a motor generator, a torque converter and a storage pump a tailwater system consisting of three compressed air surge tanks, two-chamber tailwater surge tank, tailrace to the balancing reservoir, manifold pipe to the pump. The tailrace tunnel runs underground as an inverted siphon. This inverted siphon crosses river alluvions under a street, the Ill river and an embankment of the Rifa balancing reservoir. Therefore, a special construction method was necessary in order to avoid ground settlements. combined outlet and inlet structure in the balancing Rifa reservoir a transformer cavern and a 220 kV SF6 switchyard. Lots 1 and 2Lots 1 and 2, which mainly includes the pressure tunnel, surge tank and pressure shaft, have been awarded to Swietelsky Tunnelbau / Torno Internazionale joint venture. Visit www.swietelsky.at and www.torno.comTo reduce construction costs and period to the minimum and to allow construction works during winter time at an altitude of 1,800 metres, it was decided to bore the 5.5 km-long pressure tunnel with TBM and line it with precast segments. Such a solution avoided the production of larger quantities of in-situ concrete during winter. Another factor in favour of the TBM solution is the assumption that the external water pressure in the rock water table was higher than the internal pressure in the headrace tunnel.A Robbins 5.54 m-diameter double shield TBM was used to bore the 5.5 km headrace tunnel. The machine completed its job on 20th July, 2006. The Robbins used 48.3 cm (face and gauge) back-loading cutters to bore through challenging and mixed geology. The TBM had previously been used on the successful Yellow River project in China, where it used 43.2 cm cutters. The large diameter 48.3 cm cutters used on the project proved to be a good choice, since the blockage percentage ratio was only 2% of the duration of the project, compared to the more typical rate of 10-15%. The TBM was one of the first machines to use a back-loading 48.3 cm cutterhead after the Karahnjukar hydro project in Iceland. Visit www.therobbinscompany.com Lot 3Lot 3 includes the machine chamber and transformer hall together with the supporting systems and underwater systems. Construction of lot 3 has been awarded to a JV of Jaeger, Beton- und Monierbau, Zueblin and Alpine Mayreder. Visit www.jaegerbau.com, www.bemo.co.at, www.zueblin-tunneling.com and www.alpine.at/de/nl/utb/suitb/kraftw/12796.htmlDuring construction the cavern, the extensive concrete work in the enormous machine hall has been performed with just one stationary BSA concrete pump from Putzmeister and one stationary concrete placing boom, operated alternatively on two tubular columns. Work is carried out around the clock in a three shift operation. The construction costs for the cavern power station and the underwater systems are estimated at approx. EUR30 million. Visit www.putzmeister.de The concrete pump BSA 1408 E is set up in the access tunnel and connected to both tubular columns of the MX boom via a delivery line measuring approx. 150 m Machine chamberThe impressive machine chamber, at 88 m in length, 60.5 m in height and 30.5 m in width, is located approx. 150 metres within the mountain and is accessible via an entrance tunnel from Silvretta highway between Gaschurn and Partenen. The blasting drive was started in January 2006 to excavate the enormous cavern, in one crown section and ten side wall sections. The crown section was excavated during this process with two wall headings and a core. Four layers of structural steel lattice and a coat of shotcrete measuring approx.10 cm thick per reinforcement provided safety during the excavation procedure. The long-term safety of the cavern is ensured by numerous prestressed strand anchors that are up to 32 m long. The three armoured turbine headrace tunnels of the high pressure distribution pipe flow into the machine chamber, through which the driving water passes via the pressure tunnel and the pressure shaft from a fall height of 800 metres and is driven onto the turbines' impeller blades. The PM stationary boom MX 28-4 with "Z" fold system, which is operated alternatively by two tubular columns, adapts easily to the space conditions in the huge chamber The construction of the six underground stories and the assembly level is performed using cast-in-place concrete. Altogether more than 39,000 cubic metres of concrete is poured in the machine chamber. The base of the enormous rock hall and individual ceilings are up to 4 metres thick and the walls which measure up to 8 metres in height are constructed in thicknesses ranging between 0.2 and four metres. The dimensions of the chamber mean that two stationary concrete booms would actually have been necessary for a uniform placement of concrete. After consulting engineers from Putzmeister, the consortium decided, however, to install just one MX 28-4 stationary boom, which is operated alternatively by two tubular columns. Due to the fact that the individual sections for each floor are never constructed at the same time, it hardly ever disrupts the work process. This is ensured if the arm assembly of the MX boom is removed from one of the tubular columns, raised from the gantry crane, transported to the other end of the chamber and then attached to the second tubular column. The entire procedure takes approx. 30 minutes, with the removal and connection of the delivery line likewise taking approximately half an hour to complete. Up to 360 cubic metres of concrete is used for each section.A striking feature of the unballasted MX 28-4 stationary concrete placing boom is not only the flexible Z fold system of the arm assembly, which can even be used to concrete individual base sections of the turbine headrace tunnels, but the overall length of the two tubular columns from which the boom is operated is also remarkable. By placing several tubular columns on top of one another (which are available in lengths of 4, 6 and 10 metres), they can be continually adapted to the building progress and reach an ultimate height of 40 metres in the final stage of the Kops II machine chamber. Two braces provide additional stability for the tubular columns, which are provided at a height of approx. 18 and 24 metres and anchored into the corresponding intermediate ceilings.The boom receives the concrete from a stationary PM concrete pump, which is connected to the MX boom and its two tubular columns via a 150 m-long delivery line (DN 125). The BSA 1408 E is actuated by a 75 kW electrical motor and it achieves a delivery rate of 79 cu m/h or 71 bar concrete pressure in rod side operation (full side: 53 cu m/h or 106 bar). By using less machinery, concrete can still be placed economically in a hall of this magnitude.Four operators for both the MX stationary boom and the BSA concrete pump have been instructed on how to operate the machines by Putzmeister's Austrian subsidiary. Transformer chamberThe neighbouring transformer chamber, measuring 35 m in length, 16 m in width and 20 m in height, also exhibits imposing dimensions. However it is clearly smaller than the machine hall. The placement of concrete for the foundations, wall formwork and ceilings was partly conducted with a Putzmeister truck-mounted concrete pump BRF 24-4.09 H, whose ZR fold boom had the necessary slip characteristics. The volume of concrete placed was approx. 2,200 cubic metres. Construction work for the shell in the transformer chamber was finished in November 2006.A concrete of stiffness class C25/30, which is manufactured on the construction site in its own mixing plant, is used as a standard formulation. Generally speaking a water/cement (w/c) value that is as low as possible is used to limit the hydration heat for the solid components, and in warmer seasons the ratio of cement to fly ash is changed from 230 kg:90 kg to 200 kg:120 kg per cubic metre.Visit www.peri.ro/ro/ro/pub/projects.cfm/fuseaction/showreference/reference_ID/1039/referencecategory_ID/15.cfm to read more on the concrete formwork concept for the project. 34/07.