Since mid-January, OCHS Bohr GmbH has had its seventh SENNEBOGEN crane in its fleet, which includes another telecrane and five duty cycle cranes from the Straubing-based machine construction company: "We only use SENNEBOGEN machines in our well construction department, and even the older models still run excellently," says Jürgen Nedic, site manager at OCHS Bohr GmbH. As an owner-managed company now in its fifth generation, OCHS has almost 130 years of extensive experience in well construction, pipeline construction, sewer construction and rehabilitation measures.
Its first mission takes the mobile 16 t telecrane into the Wendelstein state forest. There it is used for the mechanical cleaning of drinking water wells according to the principle of "pistons and brushes". A well brush guided on the linkage with a precisely fitting piston disc above it is moved up and down in the areas of the filter pipes in a rotating manner in order to loosen undesired sediments, which are due to the well aging, from the filter slots. In this way, a well can be rehabilitated - with a certain moderate degree of contamination. The length of the rods, which can gradually penetrate to depths of more than 100 m, is 3 m.
Although the water pumped out of wells is mainly crystal clear, chemical processes usually take place in the fractures of the rock formations, which over the years lead to unpleasant deposits, so-called ochre deposits, and later cause an ever increasing drop in well performance. These processes are called "well ageing".
"Regenerations should be adapted to demand and carried out regularly", recommends Nedic. "In most cases, this means a cycle of five to eight years in our region. This well is sunk using the flush drilling method. The regeneration, which the SENNEBOGEN 613 E carries out here, is necessary because during the camera inspection prior to the cleaning measures, larger deposits were detected in the filter slots, which ensure the penetration of the ground water. As a result, the access route of the water to the well becomes increasingly narrow until the slits are gradually closed. The longer the waiting time, the more slits become blocked. In the present case, these are iron ions in the water, which - as soon as they come into contact with oxygen - flocculate, chemically rearrange themselves and harden. In many cases they can therefore no longer be dissolved purely mechanically.“
The encrustation thus caused by untimely cleaning intervals can no longer be removed mechanically with a brush. Often a chemical regeneration has to be added, which is expensive and neither
is still good for the environment and for the well. After the regeneration unit has been retracted into the well on the 3 m long boom and placed in position, well builder and crane operator Dieter Felleiter conveniently controls the 16 t crane outside the machine using radio remote control. This allows him to approach the well directly and communicate with his colleague Julian Meisinger.
Why OCHS Bohr GmbH decided to use a mobile SENNEBOGEN telescopic crane? For Jürgen Nedic, the advantages are obvious: "With a telescopic crane you can cover a larger working area and you are simply more flexible. The requirements for well regeneration: It must lift and lower, not carry out any impact work. At the same time, however, it must be compact and flexible and be able to move under load".
Sounds like an absolute prime example of the SENNEBOGEN 613 E, which offers a compact outrigger area with 4 m x 4.35 m in the mobile version. It scores points for its maximum mobility and off-road capability, even on uneven forest ground. For this project, Ochs company is working on a total of three wells, distributed over the entire forest and each about 1.5 km apart. As a mobile crane, the 613 E can flexibly move back and forth between the different locations. The team does not lose any time by moving and / or transporting.
For these reasons, after initial considerations towards a duty cycle crane, the decision was finally made in favour of the telescopic crawler crane, which offers considerably more flexibility to meet OCHS GmbH's requirements. "Compact, small, easy to transport and easy to handle". A special challenge at this construction site was the very narrow entrance. With its compact 2.55 m width, the 613 E fits through without having to dismantle any part of the fence. Thanks to its extremely small turning circle, it can also easily take the narrow access roads to the individual construction sites in the forest.
The two well constructors Dieter Felleiter and Julian Meisinger are also convinced of their new addition: "At first they had some respect for the new technology, but that quickly disappeared. Both are particularly enthusiastic about the sensitive control system, which is very important for this work. The same applies to the Maxcab, which can be raised by 1.75 m for an excellent overview. So we are completely satisfied with our SENNEBOGEN 613 E," concludes Nedic.