More than 20 tonnes of explosive has been detonated on a single dam by a group of demolition experts trying to help the Kruger National Park (KNP) achieve their goal of removing unnecessary waterpoints in the park.
However, the Wik-en-Weeg dam in the far north of the park is still partially standing, but it is expected that about 10 more tonnes of explosive may reduce it to a pile of rubble suitable for rehabilitating old gravel pits.
Built in the early 1970s by the KNP technical services as part of the park’s old Water for Game initiative, the dam wall was initially 460m in length. Of this, 80 metres was steel-reinforced concrete, and it is here that mushroom clouds of debris have risen over the veld as the plastic explosive charges have done their work.
The earth walls of the dam were broken in 1977 by floods, repaired, and then broken again in 1989. They were not repaired after 1989, and in light of the new water policy in the park the first blasting took place on the concrete part of the dam wall in 2001.
The dam was built solely for animals, and was never in public view. It is located on the Phugwane River, a tributary of the Mphongolo River, about 40km west of Shingwedzi Camp. Wik-en-Weeg is being destroyed in sections, with an initial large blast dropping sections of the wall about 10-20 metres in length. Once the wall has fallen, further charges are laid to break the concrete up into manageable pieces.
The dam was obviously built to last, as the demolition team were surprised when their first charges failed to do as much damage as expected. It appears that the large amount of steel reinforcing in the dam poses a bit of a challenge to the team.
It takes about three days worth of blasting to reduce the fallen wall to rubble. The amount of charge laid per explosion can be up to two tonnes, but frequently much smaller charges are used. The individuals responsible for triggering the charges sit about 300 metres away from the dam wall in an armoured car, which is bombarded with falling rubble. The rest of the team move about a kilometre away to avoid injury.
Before the first charge was laid, Kruger management spent some time discussing what method of dam demolition would have the least environmental impact, and concrete breaking machinery was ruled out.
Before the charges are detonated, a microlight circles the area to check for any animals in the immediate vicinity. Thunderflashes are also let off to scare smaller animals before the main charge is triggered.
None of the rubble has been removed yet from the dam site, but other dams in Kruger that have been de-commissioned have been used to help rehabilitate gravel pits. Rubble is carted to the pits until they are filled, and then a layer of soil covers everything to allow plants to once more reclaim the area.
Other earth-walled dams in the far north of the park have been more laboriously destroyed by a team of labourers with pick and shovel, and over one hundred boreholes have been shut down with the park’s revised water provision policy. At one stage, any random spot picked in the park would not be more than 5km from a source of surface water, natural or manmade.
Waterholes and dams were created initially to help animals survive drought, but now some experts believe that all the extra water is one of the factors that has helped the elephant population grow so rapidly. It is hoped that by reducing the number of artificial water sources, the biodiversity of the park will be positively affected.
Later this year the demolition team will return to Kruger to lay more charges on the last remaining section of the Wik-en-Weeg dam, and plans will be made to deal with the jumbled heap of concrete and steel sitting in the remote wilderness area.