Sperberhai Dyke
The Sperberhai dam is an aqueduct of the Upper Harz Water Regale. It is used to direct the water of the dam across the valley of the trench hawk shark at the Clausthal plateau.
The Sperberhai dam was built to satisfy the rapidly increasing demand for power water for the water wheels of the Clausthal mines. The water crossed the dam in a running around on the dam crest. The trough is visible only at the western end today. Its hydraulic performance was at peak times up to 1000 liters per second.
History
According to the traditions had already been planned in 1656 to divert water from the mountain on the break Clausthal plateau and there, especially in the Upper House Herzberger Lake. At that time people began also with the construction of the Long trench building Herzberger from the upper pond with the usual slope of less than 1 ‰ was applied in the direction Bruchberg. Obviously you only noticed during construction or during the parallel held surveying that between the fraction mountain and the Clausthal plateau was a saddle that could not be overcome with this technique. Even then quickly came up with the idea, with a 23 m high and 2 km long dam on which the trench is then performed to overcome this sink. However, this dam had such enormous proportions that its realization seemed impossible.
The subsequent discussion of technical alternatives dragged on for nearly 100 years. The obstacle could be bridged with a Holzgefluder, but knew that this quickly weathered wood and also at the time was due to the massive wood demand of the mining and metallurgical works an extremely scarce resource. Even over a culvert, so a pipeline was discussed, but until then only had one experience with tubes up to about 50 mm in diameter and did not know how to dimension a pipeline with a capacity of about 100 liters per second. As an experiment, the project would have been too expensive decision.
About the alternative, to construct an aqueduct as a stone bridge, was never discussed. Presumably, it was discovered that there had been with the Altväterbrücke in Freiberg bad experience with a comparable structure. Among the Central European weather conditions ( frost) to Roman types have not proven much.
In the 1720s, the lack of water in the Clausthal mines worsened considerably. At the time, suggested the Bergmeister Andreas Leopold Hartzig to bridge the nearly 8 km long route between Sperberhai and Clausthal only with half of the usual gradient. By creating a new trench of Clausthal Sperberhai with half the slope is reached the Sperberhai to about 7 m lower level. Thus, the dam had only 16 m high piled and his dam was only 940 meters long. Such a construction was financed if it still cost a tremendous feat.
The reaction was conducted in the years 1732-1734. On average 200-300 workers were employed at peak times even 500 to 600 The commissioning took place in July 1734; in October 1734 a a kind of official opening ceremony attended by the main mountain man instead.
Accidents and optimizations
During the nearly 300 years of operation there were several times in damages to the mighty, but also sensitive structure: On the one hand was the infiltration of large quantities of water from the ditch in the dam body erosions or basic cause fractures; on the other hand could also spill over and cause similar at high water of the ditch on the dam crest. In both cases, significant earthworks were required to repair the damage. The first damage of this kind was still in the inauguration in 1734, the last in 1978.
Originally, the trench will have been framed on the dam crest in dry masonry; sealed left and right and under the sole with turf or clay. 1871, it was replaced by a ditch Betongerenne of 2 m width and 1 m in height; probably this was one of the first major stakes of Portland cement in the resin. Through this generous dimensions of the trench could cause a water volume of up to 1000 liters per second over the Sperberhai despite the very low gradient ( about 20 cm to 900 m in length ). The disaster of 1978 was probably due to leakage of this Betongerennes that received cracks due to settling of the dam.
1981 Sperberhai dam was cased with a pipe diameter of 500 mm AZ to rule out a repeat of the fault are from 1978 can. This dam not only lost its large hydraulic performance but also its Aquäduktcharakter.
To make the Aquäduktcharakter again, the Harzwasserwerke in 1992 on the last 300 m of the Sperberhai dam piping undone and the type trench restored in about that presumably led to the 1734 water over the dam.
Others
In order to lift some of the water in some higher-lying Upper Harz Ponds, ( about 3 km of the Sperberhai west dam ) was built on the pad Berger Hubhaus Polster.
At the eastern end of the dam is the former dam house. It was built in 1732 as a construction office, was then up to the 1970s property of the relevant grave keeper and is now a busy tourist cafe.