01 April 2020
Land of Mountains (ATM labels)
Issued on: 2020-04-01
Size: 40 x 33 mm
Emission: ATM Labels
Perforation: Serpentine Die Cut14
Printing: Offset lithography
Possible face values: 85, 100, 135, 180, 210, 230, 275, 285, 430 €cent
The Kölnbrein Dam is an arch dam in the Hohe Tauern range within Carinthia, Austria. It was constructed between 1971 and 1979 and at 200 metres (660 ft) high, it is the tallest dam in Austria. The dam’s reservoir serves as the primary storage in a three-stage pumped-storage power system that consists of nine dams, four hydroelectric power plants and a series of pipeline and penstocks. The complex is owned by Verbund power company and is referred to as the Malta-Reisseck Power Plant Group. The installed capacity of the group is 1,028.5 MW and its annual generation is 1,216 gigawatt-hours (4,380 TJ).
While the dam’s reservoir was filling, several cracks appeared in the dam and it took more than a decade of repairs before the reservoir could operate at maximum levels. Currently, the Reisseck II pumped-storage power plant is under construction and will effectively connect both the Malta and Reisseck groups and add an additional 430 MW of production capacity.
Plans for the dam were already drafted in the late 1930s by the German AEG engineering company, when the Kaprun power plant was built north of the Alpine divide. The project was resumed by the Austrian authorities after World War II with extended exploratory drilling from 1957 onwards, nevertheless the construction of the Kölnbrein Dam did not begin until 1971.
Before cement and other construction materials could be moved on site, an access road had to be constructed. This proved difficult as the steep Malta Valley rises over 300 metres (980 ft) along a 14 kilometres (8.7 mi) stretch and at times has 13 percent gradients. To complete the road, six tunnels were excavated. In 1973, as superstructure construction progressed, cement was transported on site and mixed with aggregate from local sources. To reduce thermal expansion, concrete was poured 30 cubic metres (39 cu yd) at a time and pipes with circulating water were placed throughout the mass. The structure consisted of 30 columns with each joint grouted. Construction conditions high in the valley were not ideal as workers coped with snow and rain along with wind speeds of 80 kilometres per hour (50 mph; 43 kn).
By 1977, construction on the dam had reached an advanced stage where it could begin to impound its reservoir. While filling with water, cracks began to appear in the dam on its upstream heel when the reservoir level was 42 metres (138 ft) below its maximum operating level of 1,902 metres (6,240 ft) above sea level. Uplift pressure on the dam had unexpectedly increased as well and engineers worried that the structure’s grout curtain had been damaged. Because the dam is in a “U”-shaped valley instead of the usual “V”-shaped for arch dams, hydrostatic pressure is exceptionally strong on the center-bottom (heel) upstream portion of the dam. As excessive water leaked into lower areas of the dam, the water level was drawn down and engineers increased drainage.
In 1979, the grout curtain was strengthened and another full impoundment was unsuccessfully attempted. Between 1980 and 1981, a polyurethane resin grout was used to re-grout joints and they were frozen during the next impoundment attempt, allowing them to thaw naturally. As remedial works progressed, cracks near the abutments (flanks) of the dam formed as well; on the downstream side and in a horizontal direction. A plastic sheet-covered concrete blanket was laid on the upstream valley floor behind the dam between 1981 and 1983. In the next few years, the sheets had to be repaired and the grout curtain re-grouted. In 1984, the reservoir was able to reach 90 percent full. In 1979 and 1983, it had temporarily reached its maximum level as well but it could not be safely sustained. In 1984, the reservoir levels were limited to 15–20 m (49–66 ft) below maximum, and at those levels it was able to operate safely though at reduced capacities.
Notwithstanding these remedial actions, a long-term solution was required. This came in the form of a 70 m (230 ft) tall “thrust block” that had to be constructed at the downstream base of the dam in order to absorb load from the dam and pressure on its abutments. Its construction was approved in 1988 and executed between 1989 and 1992. Joining the dam and the block are over 600 special neoprene pads which adjust to forces from the reservoir rising and lowering. In addition, joints and fissures in the dam were re-grouted again but with a water-tight resin epoxy. The reservoir was able to operate at maximum levels and operate as normal in 1993.
The Kölnbrein Dam is the terminus of a 14.3 kilometres (8.9 mi) long scenic route through the Maltatal, the former construction site road, including a restaurant, a hotel and an exhibition on hydroelectricity. Verbund also offers tours of the power plant group and the dam. Tours on the dam are conducted daily while the road is open between 9 May and 26 October each year.
In 2010 a “skywalk”, a horseshoe-shaped cantilever bridge, was installed on top of the dam for visitors which is also a popular bungee jumping venue. The dam lies within the High Tauern National Park and is a destination for mountaineers as well. Moreover, the reservoir is used by rowers for altitude training.
The dam features in the 1978 film The Boys From Brazil, standing in for a location in Sweden. The movie was shot between late 1977 and early 1978 and shows the newly erected dam with a low reservoir level. In the film the character of the inspector of the local power company (and former SS Major) is thrown off the top of the snow-covered dam by an assassin sent by a fictional Josef Mengele. Various shots around and on top of the dam are shown in the 3 minute 15 second scene at approximately 55 minutes into the film.
The Schlegeis Alpenstrasse Alpine Road leads to a breathtaking high mountain region. Along the 13.3 km long route, waterfalls, natural stone tunnels and many a glacial view await. For true bikers, getting there is more than half the fun – and everyone else can look forward to the emerald green reservoir and a pure mountain experience at the destination.
The Schlegeis reservoir is surrounded by the High Alps Nature Park Zillertal Alps, which has shaped 397 km²of the Zillertal valley since 1991. Excellent routes and hiking trails as well as numerous shelter and pasture chalets make the region and its impressive backdrop the ideal point of departure for easy hikes, tours of moderate difficulty, lofty high-elevation trails and sporty summit tours. The area around the Schlegeis reservoir offers the perfect place for pleasure hikers and demanding alpinists.
The reservoir holds a total of 126.5 million m³ of water – the Schlegeissperre is VERBUND’s longest dam, with a length of 725 metres. You can explore its inner workings on the dam wall tour. There, you can learn interesting facts about electricity generation from hydropower, the features and history of the structure, as well as the unique fauna and flora. If you’d like to learn more about the Zillertal power plant group, then you’ll find what you want right next to the power plant in the town of Mayrhofen. The VERBUND information centre is located there. The exhibition offers interesting information about electricity generation and is open all year round with free admission.