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Rig drilling at a rocky drillsite in the norther parts of Sweden.
Casing advancing of a 40 mm tube with Wassara

Wassara has developed a completely new Single-step instrumentation casing system for dams. A 40 mm tube can now be installed in two hours instead of the two days required by traditional technologies.

Wassara Instrumentation Casing System

There are always safety concerns when drilling in dam structures. With Wassaras water-powered drilling technology, these concerns are minimal. The unique technology, which has been used in numerous dam rehabilitation projects over the years, greatly reduces the pressure applied to the rock formation.

By combining Wassaras DTH technology with a filter tube, installing instruments can be carried out much faster than with traditional methods. A traditional installation of a 40 mm tube usually requires up to two full working days. A Wassara installation of a 40 mm tube takes approximately two hours. This is up to eight times faster than comparable technologies.

The major difference is the ability to install a filter tube directly, without having to set a 100 mm tube first. The time used to fill the space between the two pipes with filter sand is also eliminated with Wassara and this is a major time savings. Another great advantage is the size of the drill rig, as the installation of a 40 mm tube needs a smaller rig than what a 100 mm tube requires.

The system comprises a Wassara hammer with 43 mm bit, filter tubes, drill rods (Ø 40mm), inner tube and an extractor tool to retrieve the inner tube after installation. The smallest internal diameter is 26 mm (the filter tube).


1. After drilling down to target depth, the inner flow tube is retrieved by an extractor tool.
2. The monitoring instrument can be installed by lowering it into the filter tube.

This video clip shows the high penetration rate