TERRA-JET DJ 20 drills 55 m for FTTH in Andebu, Norway
The Norwegian contractor Mikkelsen & Mikkelsen A/S from Stokke is specialized in FTTH-cable laying. For this project in Andebu / Vestfold a street crossing had to be realized and four pipes PE OD 40 mm needed to be installed under the street and the adjacent lawn. Mikkelsen & Mikkelsen A/S used their new horizontal directional drilling rig TERRA-JET TJ 2808 S to do this job. The TERRA-JET DJ 20 is equipped with an automatic drill rod changer with total 90 m (300 ft) drill rods on board as well as a mixing pump on board.
The total length of 55 m (180 ft) was riddled with some difficulties. Where the street has to be crossed, a narrow field was given to bore through between compacted gravel layer under the road surface, the bedrock surface on the bottom and the steep embankment behind the street. Apart from the first drill rod (3 m) the entire bore was steered altitudinal and laterally. Additionally there were numerous existing pipes and manholes along the bore path, which were to be avoided. As a result it took some time to pinpoint and mark all the existing lines and plan the bore path.
The pilot bore has been finished and arrived dead on target in the pit with the existing mainline. A 3-finger head was used as a drill head.
The pipes to pull in are prepared on a pipe decoiler hanging on the excavator in order to unroll smoothly during backreaming and pipe pulling in.
The 3-finger head and the sonde housing were disassembled and replaced with the backreamer with integrated swivel to pull in the pipe bundle.
Owner and drillmaster Henrik Mikkelsen is pulling the pipes further back by driving backwards after a smooth and fast uninter¬rupted back-ream¬ing with simultaneous pipe pull-in.
