At Melo dam, the topography of the rock is steep and it complicated the process of drilling the pile wall. When drilling the RD pile wall, a down-the-hole hammer was used, which operated on compressed air. Beside generating the percussion power, compressed air also lifts the drill cuttings up inside the pile pipe. The connectors attached to the piles have an injection channel, through which the annulus between the pile wall and the bedrock was filled with cement grout. In this way, the joint between the pile toe and the bedrock was made watertight. Finally, the dam was restored by cutting the piles about 0.5 meters below the ground level. The upper ends of the piles were protected by welding a 10 mm steel plate to them, after which the ends of the piles were covered with soil. The dam will serve as a pedestrian and bicycle lane once the repair work is completed.
The RD pile wall, which is installed by drilling from SSAB RD piles, is especially suitable for use in retaining wall structures in demanding soil conditions. Sites, where the structure is subjected not only to horizontal loads but also to vertical loads, are ideally suited for RD pile walls. The pile pipes are made from SSAB's own steel by spiral welding. The piles are available in several steel grades. By utilizing high-strength steel, the weight of the steel transported to the construction site can be significantly reduced. The same resistance is achieved with a smaller amount of steel.