Concord Namibia (Plant & Crane Hire) has played a key role in the successful completion of the Neckartal Dam project, the largest water-storage dam in Namibia at about 960 million cubic metres. It supplied a 220 t and a 550 t crane to assist Italian contractor Salini Impregilo with construction of the 80-m-deep dam, with a crest length of 518 m.

This curved gravity dam on the Fish River near Berseba, about 40 km north-west of Keetmanshoop, began construction in 2013, and was finally completed in October 2018. It has almost three times the capacity of the Hardap Dam near Mariental in the Hardap region. The Neckartal Dam is expected to supply a 5 000 ha irrigation scheme in the region.

The 220 t mobile crane was supplied by Concord Namibia after having travelled all the way from Saldanha, explains CEO Francois Smith. The crane’s main function was to install trash racks and roof beams for the inlet tower facing the water side of the dam. Water enters the inlet tower through the dam wall into the turbine room, where it generates hydroelectricity.

The trash racks are essentially giant filters placed in front of the water inlets to prevent any debris from entering the system. These had to be installed by the crane that was perched on top of the dam wall. The trash racks eventually stacked up to 60 m in height.

While still inside the partially-completed inlet tower, complex rigging and lifting was required to position the 22 t concrete roof beams for the tower. With the final four beams directly on top of the crane, the crane had to be re-positioned outside the tower, on a narrow dam wall, and the beams lifted up and over the tower walls in order to place the remaining four beams.

Several computerised rigging studies were carried out to ensure a safe and successful lift of every beam. The 220 t crane was then relocated to the river or ‘dry’ side of the dam, where it was used to dismantle two tower cranes that had been deployed over the four-year construction period.

In addition, a 550 t crane was transported from Rustenburg to Keetmanshoop specifically for this project. This crane was used to dismantle an 8-m-high tower crane, and re-erect it on top of the dam wall. The 550 t crane was also responsible for dismantling the conveyor-belt systems supplying concrete from the batching plant to the dam wall.

These systems were installed by means of two big cranes operating in tandem so as to share the load. “However, we opted to supply one big crane to carry out the dismantling, based on the computerised rigging studies that simulated the lift. The study was submitted to Salini Impregilo engineers and their safety department. The single-crane solution was cost-effective, with a significant cost-saving for the client,” Smith comments.

In conjunction with providing a successful lifting solution, intensive planning had to be carried out in order to overcome the logistical challenges on-site. Construction roads and steep inclines can prove difficult for moving equipment around, and vehicles 20 m in length. “This is why we proposed a multi-axle crane with the ability to steer and negotiate tight corners with ease,” Smith reveals.

In order to protect the gravel road and the crane, a bulldozer was positioned in front of the 96 t crane to assist in removing the crane from the riverbed. This provided extra pulling power, and ensured a safe exit, with no damage to equipment, roads, or infrastructure.

A challenge that was always looming was the possibility of a flash flood in the Fish River. “Anytime it rained up north, water would suddenly come pouring down. This is not a dam with sluice gates. It fills up and overflows, and therefore having a crane on the riverbed on the dam side was a huge risk. The crane requires dismantling, extra extensions, removal of the booms and counterweights, and for the outriggers to be put back on all before it can be driven away,” Smith highlights. According to the required specification, crane assembly takes two days, with a day to dismantle it.

“We checked the weather forecasts constantly for any storm warnings from up north. Fortunately, we had no issues whatsoever. At the end of the day, we felt privileged to have been a part of this massive infrastructure project,” Smith adds. He concludes that, on the back of its successful work here, Concord Namibia is well-poised to follow Salini Impregilo elsewhere into Africa should they secure any more dam projects.

Smith is extremely proud of the fact that the team at Concord Namibia, under the leadership of Crane Manager Johann Greeff, was able to complete the project without any hiccups or delays.

“The fact that we got everything correct the first time was our proudest moment, as this was a testament to the extensive planning and preparation undertaken by the team. It was this outcome that secured us additional work on the project,” Smith concludes.