Ämmä Hydropower Plant
Jylhämä was an important power plant in terms of the whole venture, of harnessing the hydroelectric power of the River Oulujoki. It is the first power plant in the river, that flows from Lake Oulujärvi to the Baltic Sea and because of this, functions as a regulating facility for Lake. The plant was designed by architect Aarne Ervi.
In 1946, only two power plants on the river Oulujoki were under construction. Finland was suffering from an electricity shortage following the war, so it was urgent to get new hydroelectric projects started. Niskakoski falls, in the municipality of Vaala, was going to be divided between two power plants. Jylhämä was going to be built upstream and Nuojua to the lower part of the rapids.
The construction started during the summer of 1946. The area did not have proper roads or housing so, the first 1.5 years was spent setting up a modern construction community. To provide enough timber, Oulujoki Power Company had bought the Vaala Sawmill that was located nearby.
The biggest obstacles in building Jylhämä had to do with earthmoving and excavating. Machines were not available because of the shortages following the war, so most of the work had to be carried out manually. The situation got better in 1948 and after this, most of the work could be done with machines.
A total of 1.5 million cubic metres of earth had to be removed, when building the earth fill dams and digging the canals. This meant that Jylhämä was, at the time, the second largest earth moving job in Finnish history. When at its busiest, over 2,000 men and dozens of machines worked at the construction site.
At the same time, the power house and the concrete dam were under construction. A concrete mixing plant had also been built on the south shore. The power house was built with an in-situ concrete frame, plastered brick façades and horizontal windows. Architecturally Jylhämä is Ervi’s “first generation” of power plants, meaning: distinctly modernist in its appearance and program but still incorporating some traditional features like plastered brick façades. Jylhämä also has a large regulating dam with two spillways that, located in the eastern side of the power plant.
In the interior of the power house, the coupling machinery is placed in the same volume as the generators and the large, almost cathedral-like space, is divided only by a colonnade. The machine hall opens in several directions through the large windows and glass doors while the office section has a beautiful lobby and an airy staircase. The high quality of concrete work is also a notable feature.
Jylhämä was connected to the power grid in the early 1950s, the first set of machinery on 19 June 1950, the second one on 3 December 1950 and the third on 30 December 1951. Today Jylhämä produces 55 megawatts of power.
Nearby Jylhämä hydropower plant also lies the Jylhämä residential area (link), also designed by Ervi.
Text: Samuli Paitsola