The drilling to lay pipes are faster, cheaper and more environmentally friendly than shafts. Ground handling is reduced to a minimum. A technology could be in the works, but it lingers.
Click image for larger version. Graphics: Jonas Askergren
Sweden’s first maxi-rig drilling machines, with thrust of 150 tons. Previously, there was no rigging with thrust over 45 tons in the country.
Mats Otter Born.
Magnus Ting Beach.
Rolf drilled.
directional drilling, or HDD (Horizontal Directional Drilling), can be made under roads, waterways and existing wiring, or other places where it is difficult for excavators to access. In recent years, technology has begun to gain ground even for ordinary wiring.
But despite the advantages is it hard for the technology to break through in Sweden .
Perhaps it will change when the first Nordic rig drilling in the so-called maxi-Class is now in Gothenburg. The construction company BAB Rörtryckning in Gothenburg have bought into a towering, a German-built Herrenknecht which is 15 feet long and four feet high. Above all, a thrust of 150 tons, which is used to “pull home” tubes through the predrilled pilot hole.
Previously, there has not been HDD rigs with traction over 45 tonnes in Sweden, so BAB’s machine means a substantial capacity step up.
– Traditionally, drilling mostly been used for laying of cables and other jobs in smaller dimensions. But this machine can safely drill diameters of 1000 millimeters in length up to 1.5 km in the wet clay, says Magnus Ting Beach, resident engineer at BAB Rörtryckning.
The company has worked with horizontal drilling in about 15 years.
– When we began this so we drilled just where it was not possible to dig under a stream, for example, and put excavators rest. Today we often do the opposite: dig just where it is not possible to drill, says Magnus Ting Beach.
Controlled horizontal drilling often go faster than digging. But the big advantage is that drilling minimizes the amount of soil that is excavated and must be handled.
– There is no need for earth-moving and almost no land restoration . In this way it will be both cheaper and minimal interference with nature, says Magnus Ting Beach.
Controlled horizontal drilling has, however, also disadvantages compared with shafts. It requires a more thorough preliminary geotechnical investigation – it is coarser rock or very moraine in the substrate so excavator preferable.
But above all are significantly more expensive technology. Maxi rig in Gothenburg has cost around 25 million including drill rods, high pressure pump, mixer works and other peripherals. An excavator on the scale required to make the same moves cost 2-3 million. Magnus Ting Beach is difficult to estimate how long it will take to recoup the extra cost.
– The fixed costs of establishment and start-up are the same regardless of the length of the bore, so the operating cost per meter drilled falls in line with the increased length of the wiring. It is, so to speak, cheaper to drill the thousandth meter than the first one. So it is difficult to make general estimates of operating costs, he said.
The big market BAB Rörtryckning hope for is to be able to replace excavation at coarser VA draws.
Mats Otter Born, industry advisor to the trade organization Maskinentreprenörerna, sees that the demand for drilling is growing, but slowly.
– You might see it as a competing technology. That it means less excavation and earthmoving may sound good for everyone, except for those feeding on excavating and earthmoving. But it’s not a goal to run excavator, says Mats Otter Born.
According to Rolf drilled, Chairman of the drilling contractors’ trade association Geotec, there are three challenges of drilling in Sweden.
– Conservatism, fear and ignorance, the biggest challenge is ignorance. This technique is not included in either engineering or upper secondary schools machine driver program, but it’s in-house training for companies that apply.
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