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This piece of equipment was used to survey the
tunnel construction.
The iron industry had developed and the population grew to about 500 in 1764. Bastards and non confessionals etc. were not included in this number. The Hacke Family became very rich. The 2 wells, the house - own wells
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etc. did not supply enough water for daily use. One of Anton Ludwig Freiherr von Hacke`s sons, Franz Carl Josef F. v. H. took over its annexes after his father`s death.
In 1764 he had a castle and garden constructed in Barock style on his land. The gardens with their water fountains were to make the castle more attractive.
«««««Freiherr Carl Theodor von Hacke - Aquarelle from Wilhelm Kobell Original im Reissmuseum Mannheim / Ger.
The oldest tunnel construction in our history served the supply of water and in both the construction of King Hezekia`s tunnel ( 725 - 696 b. C.) for Jerusalem, as well as the tunnel built in
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6th century B. c. by Eupalinos for Polyrates on the Island of Samos, the COUNTER PROCEDURE was used - just as for our " Brunnenstollen"- also a genuine tunnel construction.
In Roman times all the water supply systems in Germany were constructed according to the QANAT PROCEDURE ( daylight shafts ). The planning and construction of these cultural
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monuments took a great deal of time and cost an enormous amount of money. Some rich architects lost their livings because of this.
As a result of our observations and the
surveying details we can assume the following hypothesis:
The diversion tunnel was to convey the water
from Quellbachtal to the existing water canal on Judenhuebel, thus saving a
second waterway.
The complete surface surveying with the
determination of the in-flow and out-flow heights and the profile must have been
carried out on this basis. The exact construction of the diversion tunnel
following this plan would have been up to 15m shorter.
The construction was carried out using the
COUNTER PROCEDURE i.e.tunnelling from two sides ( entrance in Quellbachtal and
exit on Judenhuebel). The propulsion work took its bearings most probably from
the rock strata and (as in ancient times) daylight had to be seen at all times
to ensure maintenance of the correct direction.
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open with the
assistance of controlled detonations.
The cross-sectional drawings show us that this
tunnel was constructed by skilled workers such as stone-masons , and was planned
and supervised by an engineer.
Triangula - iron - hole
The group working from the north side
(Quellbachtal) following the natural course of the strata corrected
its direction only once over a total length of 115.2m, whereas the group
working from the south side had to make nine corrections over a distance of
82.67m.
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We assume, therefore, that in spite of the
difficult construction conditions, very exact surveying and guidance plans were
available. This can be proved by surveying figures found on the walls of the
tunnel.
Controlled detonations on roof ( Judenhuebel ) Photo: Mr. Schacher, Geol. Institute Heidelberg / Ger.
The vertical sections from the Karlsruhe Cave
Research team, as well as our own expert surveying results, show that the
propulsion work from the north side was stopped at 115.2m and that from the
south side at 82.67m. According to the calculations and the chiseling marks in
the sandstone the two tunnels should have met here.
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The sections give us the clear impression that the ends of the two tunnels were only approx. 2 meters apart. At
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this point the workers were given new instructions ( four in all ) to connect the two tunnels. It is well known that such problems also occurred in 6 b.C. and also later in Roman times.
The skilled workers were able to join the tunnels successfully in spite of great “UNCERTAINTY”. Not, however, without disappointment, as it became clear that the
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floor of the north tunnel (Quellbachtal) lay one meter below that of the south side tunnel. As already mentioned, the plans and the longitudinal section of the tunnel show us that the floor height before the correction at the south side, had already been determined at the depth of the presently existing water supply system. Of course, the rock strata at floor- and roof –level played an important part, and additionally
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we must not forget the earth formations. The finishing tasks (e.g.
lowering the floor and extending the main collector) were no longer a problem
for the various skilled workers.
The extension of the main collectors in both directions and the superstructure of
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the water source locations were constructed
in open dry-wall form with arched roves.
After this a second waterway to the village, i.e. to the castle, became necessary.
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The distribution chamber (Hauptstr. 77),
the Lion Well, the School Well, the Castle Well the Castle kitchen (supplied by a
second distribution chamber) and also the Castle gardens were connected to the
mains (see plan made by P.C. Paul Kallenbach).
As previously mentioned the two tunnels differed from each other. The north side tunnel had a falling tendency, whereas the south side tunnel rose gradually. Hydrological engineering tests showed that it was not necessary to contain the water on the south side because of its rising tendency, but obviously the water on the north side had to be held back. This can be reconstructed as follows: as the entire source area was exposed, it was discovered that the most water came from the second source. Consequently, a few dams and ditches were made to prevent the water flowing into where propulsion
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work was being carried out.. This was confirmed by
measuring the amounts of water at this section of the tunnel.
The amounts of water measured
1991 – 1994 behind the source
at the entrance were the same as those measured at the North exit. * Dry
weather flow 0.2 liters per second, wet weather flow approx. 5.0 liters per
second. April 1998 8.0 l./sec.
From the cross- and longitudinal sections of the tunnel it is evident
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that work was carried out under dry conditions. Otherwise it would not have been possible to complete the tunnel. Photo: Mr. Schacher, Geol. Institute Heidelberg / Ger.
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