Merriespruit Tailings Dam

Merriespruit is a suburb of Virginia in South Africa, and on the 22nd of February 1994 it suffered a terrible flood because of failure to the Merriespruit tailings dam. There had been heavy rainfall that day, and the dam could not hold the extra water. The damage was immense, destroying eighty homes and killing seventeen people.

The dam itself was for the deposit of gold tailings. After gold was removed from local rock, the materials left over were transported to the dam in order to settle during the day. During the night, slurry was processed. In the middle of the dam, there was a drain to get rid of excess water.

The dam was built in the town in 1978, and only just over three hundred metres away from one of the houses in Merriespruit, which contained around two hundred and fifty houses in total. The year before the disaster, a leak was reported, so all deposition was cancelled in to that particular compartment. Extra water was filtered into another compartment. Before the dam failed, the conditions were considered unsafe and unfit. The freeboard (which contained the extra water) did not have the ability to hold half a metre of extra water. But still, nothing was done.

On the day of the disaster, there were reports of a flurry of water coming from the dam into the town. However, this was not the first time a stream had escaped. Another eye witness saw a leak coming from over the top wall of the dam. The mining contractors arrived to assess the dam that evening. They assessed the damage, and were about to warn the local town. However, they had no time. A loud crash was heard coming from the dam, and a wave broke free, heading towards the locals.

The flood that was released was a mixture of water, sediment and slime from the gold tailing process. The volume of water that flowed out was six hundred thousand metres squared. By the time it reached the first house in Merriespruit, the wall of silt and water was two and a half metres high. The liquids travelled four kilometres before losing its momentum, but the damage had been done.

In the aftermath of the floods, investigations were undertaken to assess what exactly had happened. The Minister of Justice and the State looked at all the evidence, which included weather reports, lab reports from the owners of the dam, satellite reports, and statements from eye witnesses. In the end, the fault was down to the contractor and the mine who were responsible for the upkeep. Eight people were fined for negligence. As it transpired, there had been a drop in the number of employees at the dam in recent years. Certain members of staff had been promoted into jobs that they had not been trained for.

There was naturally an outrage from the community about the disaster. In response, the law subsequently changed so that no tailings dams can now be built within a kilometre of housing.

Sources: Wikipedia, Tailings

South Africa