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400 FTTH house connections with GRUNDOMAT hammers
That was the question asked of Michael Depau on a daily basis by one of the US liaison officers at the Kelly Barracks in Stuttgart, Germany. Michael was in charge of a cable installation project for several weeks. In 2009 Michael Depau became self-employed and remembered this question when searching for a suitable company name. The company TRENCH-PROJECT GmbH & Co. KG was born. Today TRENCH-PROJECT has 7 employees and particularly specialises in house connections, but now mainly completed using trenchless techniques.
GRUNDOMAT soil displacement hammers for FTTH house connections
According to Michael Depau: “In Gravenbruch near Neu-Isenburg, Germany we are currently installing some 400 FTTH house connections for our partner company Klenk & Sons GmbH of Asbach. Blocks of houses with up to 20 apartments are being connected to the glass fibre network on behalf of the client, German Telecom. The length of the house connections from the main cable to the building varies and can be anything up to 70 m. The use of an open trench method is out of the question, even though the cables are only at a depth of 600 mm. This is much too expensive and takes far too long. That is why we work increasingly with trenchless methods and the GRUNDOMAT soil displacement hammer has become the most important tool for us."
Systematic installation FTTH service connections
Scepticism regarding the use of the soil displacement hammer method, which was apparent at the beginning of the work, has been turned into to enthusiasm. In December 2011 TRENCH-PROJECT invested in GRUNDOMAT N soil displacement hammers and utilised the 45 mm diameter unit to install over 1,000 m of cable pipes using this trenchless method.
According to a client representative: “We completed cable connections in Schwalben Street at houses 11 and 13. It became immediately apparent that TRENCH-PROJECT work systematically. Each worker knows exactly what he has to and when he has to do it. Everything runs smoothly and no further comments are necessary.“ The main glass fibre line had been installed 2 years previously in the paved footpath. On the project TRENCH-PROJECT is allowed to determine the connection points. The pavement is excavated at the required position for a 600 mm deep and only 500 mm wide small start pit with the pit itself being extracted by hand. The width of the pavement is exactly the same size as the length of the GRUNDOMAT soil displacement hammer, so it can be aligned and started from the inside the pit.
During the preparation work the shortest bore path is determined and the whereabouts of any possible adjacent service lines are also checked. Depending on the length of the bore, intermediate pits may be necessary, from where the soil displacement hammer would be re-started to maintain alignment if necessary. Other colleagues produce a wall entrance in the building at the same time. In doing this a hole is bored through the cellar wall of the building then the wall entrance is pushed through and sealed off with a special resin. By this time the GRUNDOMAT soil displacement hammer is already on its way and only a few minutes after launch it reaches the head hole in front of the cellar wall. On this particular run a distance of 16 m. In the sandy-loamy soil the bore hole is stable and will not collapse. After reversing the soil displacement hammer it is no problem at all to push the twin-cable pipe through the wall entrance without the need for any additional support. “If there is ever any problem during the push-in process, then the ‘garden eel’ will always do the trick.” said Michael Depau.
A perfect connection
Next on the agenda was to make the connection to the main glass fibre line according to the layout plan, where an exact description shows, which pipe colour belongs to which house number. Plug connections make the connection work much easier and this is also completed within just a few minutes. At the same time the drill for the next wall access can be heard working in the cellar of the next block of houses. Others in the workforce then fill in the pits and after only 2 hours no trace of the connection work can be seen. To date 150 house connections have been completed in the same way and 3 to 5 new house connections are added daily. After the installation, the pipes are accurately located with GPS and recorded in the inventory plans.
Independent to the installation work, about 600 m away, the glass fibre cables are blown into the pipe for Schwalben Street 11 and 13 with compressed air. Once this is completed the residents are able to enjoy using a powerful glass fibre network with up to 200 Mb/s for downloads and 100 Mb/s for uploads.
The contractor has also been very satisfied with the installations achieved. TRENCH-PROJECT has already got its eye on the next project and is looking to invest even further in bore technology.

Paul-Schmidt-Straße 2
57368 Lennestadt

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