GEDA 1255 metres above sea level
GEDA 1500 Z/ZP Transport Platform at the Hongrin Dam – a challenge at dizzy heights
The Hongrin Dam is located at a height of 1255 metres near Col des Mosses in the Alps around Lake Geneva. The water in its huge basin is held for electricity generation. The Hongrin Dam was built at the end of the 1960s. It holds the melted snow and ice from nine water courses and is also supplied with water from Lake Geneva pumped through about 20 km of pipes.
The dam wall consists of two huge arch dams. The dam volume is a maximum of 52 million m³ over a depth of 105 metres and a surface of 160 hectares.
Repairs to the safety equipment
The two bottom outlet valves which are located 22 metres above the foot of the Hongrin Dam wall now have to be replaced due to their age before further repair works can be undertaken. The sticking point is that since there is no road leading to the foot of the dam wall, access is only possible from above from the dam crest. The scaffolding company Roth Echafaudages SA had the task of building a 180 m² working platform at the level of the bottom outlet valves.
GEDA 1500 Z/ZP along the curved wall
The GEDA 1500 Z/ZP transport platform has also been in use here since October 2011. It is used as the connection between the dam crest and the working platform built under the bottom outlet valves. GEDA's long-term Swiss partner, ALCLIC AG rented the transport platform to the company Hydro Exploitation SA Sion, so as to ensure the safe and effective upwards and downwards transportation of people and materials.
The biggest difficulty was to anchor the two masts of the GEDA 1500 Z/ZP along the curved dam wall where the distance between the lift tower and wall varies by up to 15 metres!
After looking at various possible solutions, Roth Echafaudages SA selected a tower scaffolding between the wall and the lift. The scaffolding is fastened with four cables and aluminium girders to the dam wall at distances eight metres apart. The actual anchorage drilling work for the tower scaffolding was carried out by a mountaineer working from ropes on the concave wall.
The GEDA 1500 Z/ZP has two separate control systems and can be used both as a pure material lift and also as a transport platform for people and materials. The transport platform control system has a speed of 12 m/min and this is activated for the transportation of people and materials. For the transportation of only building materials, it is switched to material lift mode with a speed of 30 m/min.
The GEDA 1500 Z/ZP is guided along two steel masts. The proven two mast system ensures the platform remains stable when travelling - even in strong down winds.
The customer has a range of platforms to choose from when selecting the most appropriate for each specific building site. The practical modular construction means that there are many different combination options. The BS-Platform which is 1.45 x 3.30 metres in size is used at the Hongrin Dam.
A GEDA COMFORT landing level safety gate has been installed at the two stop positions to ensure a safe passage from the platform to the unloading point. The combined 1500 Z/ZP device is naturally equipped with the usual safety equipment such as limit switches, speed-dependent safety gear, safety stop and overload protection.
The Col des Mosses region is well-known for heavy snow falls. Therefore comprehensive safety measures for the platform housing had to be undertaken. It was also necessary to protect the cable bin from filling with snow with a cover and to prevent the ventilators blocking the drive motors with freezing snow. Specifically for its use at the Hongrin Dam, the 1500 Z/ZP transport platform was also fitted with a protected roof 2.5 metres high and with additional lattice guard netting on three sides of the platform.
Hongrin Dam is a popular excursion site for tourists and an impressive location for walkers and fishermen. A look into the dizzying depths is worthwhile in any event, since the GEDA 1500 Z/ZP on an impressive scaffolding construction can be admired on the gigantic arch dam until the end of 2013.