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Hünnebeck provides custom formwork solution for Tarniţa Embankment Dam

Custom formwork solution for Tarniţa Embankment Dam, Romania

Hünnebeck provides special construction concept for water extraction
tower

Cluj-Napoca, April 2009 - Extraordinary buildings require extraordinary measures: For the construction of a circular water extraction tower at the Tarniţa dam near the Romanian city of Cluj, the general contractor - Consortium Strabag and Hidroconstructia - relied on the technical know-how as well as the engineering experience of the formwork specialist Hünnebeck Romania. On the one hand, no standardized formwork panels could be applied because of the curvature of the outer wall. On the other hand, the little space available inside of the tower made the forming of the inner walls that separate the individual chambers, increasingly complicated.

Hünnebeck Romania developed a custom-engineered solution for this specific construction site as well as providing the necessary formwork material. The 97 meter high and 237 meter long Tarniţa embankment dam in the Gilau Mountains, ponds the flowing waters of the Someş Cald River into a lake that is approximately seven kilometers long. About 74 million cubic meters of water are held and contained in the lake reservoir, which is used to produce electricity through hydroelectric power production. Aside from that, the reservoir also acts as a fresh water reserve for the city of Cluj and the surrounding area. In order to attain different quality levels by means of mixing, the water has to be extracted from various depths of the lake. For this purpose, the water extraction tower was constructed. Several water intakes, which are positioned on top of each other, can thus guarantee the drinking water abstraction from different depths.

The 25 meter high circular tower has an external diameter of seven meters whilst the inside structure is divided into three equal chambers by partition walls. Whereas the outside wall has a thickness of 50 cm, the inside partition walls have a thickness of 30 cm. Moreover, the tower was erected in a total of ten concreting cycles. During the starting cycle, the concrete for the foundation platform was poured. Afterwards, nine further concreting cycles in increments of three meters took place, in which the latter cycle overlapped the previous.

For the forming of the outer walls, Hünnebeck Romania applied its robust, non-slip and shatter-proof H20 timber beam formwork system. The solid timber beams, which can also be nailed on the outside areas, are exceptionally suitable for custom requirements and site-bound tasks. Also for the construction of the water extraction tower, the timber beams were able to validate their great flexibility. To shape the circular outer wall to the exact curvature, the timber beams were combined with ring planks, onto which ultimately the form lining was nailed.

Given the narrow and little space available on the inside of the tower, the high-performance MANTO formwork system was able to demonstrate its full strength. Thanks to its large assortment of different panel sizes with various measurements, MANTO is able solve any formwork problem, at any height and with any layout. Since MANTO panels only permit a polygonal alignment, infills are fitted between the formwork panels and wedges attached onto which a second, curved form lining is nailed. To produce the buildings "rounded edges" that resulted from the circular design, custom forms were fabricated by Hünnebeck Romania using special parts.

The formwork elements on the outside were placed on a HG 180 suspended scaffold. On the inside, the formwork stands on special latch platforms secured with an additional beam. On the construction site of the Tarniţa dam, Hünnebeck was able to prove its strengths in service, engineering and flexibility. The construction supplier provided the formwork products by means of selling as well as rental. Consequently, economical as well as safe working conditions were assured for the contracting business.