By Jack Caldwell - Mining Engineer - Robertson GeoConsultants

Sometimes tailings dam fail because of the poor quality of the construction. Sometimes mine geowaste facilities fail because of poor design. On the basis of today’s events, I conclude that they may fail because of poor concepts, poor understanding of the theory, and plain simple incompetence.

Here is a link to a posting on a civil engineering dam that could fail because of poor quality control during construction.

Actually the story appears to be of worse deeds than plain incompetence. One cannot but wonder if venality and criminality are rife on the site too. Here are a few quotes from the report that highlight the overall issues:

Inside information, which includes documents, photographs and videos, has been passed over to us by a former Quality Controller, who says concerns about sloppy procedures and cost-cutting measures were ignored by the bosses at Sinohydro.

The sensational video footage clearly shows workers hosing extra water into the cement mixers before it is pumped into the dam, which is visible in the background. Our information is that this forbidden practice was endemic on the project and that poor quality control procedures allowed it to happen.

The key problem, according to our informant, has been a total failure of the Quality Control measures, which are supposed to ensure the dam is built to proper specifications. He complains that there were “definitely not enough” Quality Controllers hired for the project and that therefore it was impossible to carry out adequate supervision across the many different work points on the enormous site.

The first real job I had after graduation was on the Hendrik Verwoerd dam construction. The dam now goes by another more African name, the Gariep Dam. I was one of three shift supervisors. Pouring of concrete was around the clock, twenty-four hours a day. One of us was in charge for eight hours, having relieved the fellow in charge of the site for the past eight hours, and in tune we were relieved after an eight hour shift.

The other two fellows were at least twice my age. I got the job because they had worked on the mines as shift bosses under my father. When they got wind of the coming of the son of their former boss (my father) they insisted that I join them and they took me under their wings.

I owe them everything. For they taught a green-horn for university how to be practical, how to make a construction site work, how toplace every type of concrete in every form conceivable.

I also learnt every trick in the book when it comes to altering the properties of concrete to make it more workable. And I learnt how to manage the French quality control engineers who were every where, all the time. I learnt to respect them and admire their persistence in demanding quality when my instinct and the instinct of all of those we managed was to compromise quality in the interests of an easy shift.

Recall we were placing up to 2,000 cubic yards of concrete per shift with four blondins, four cranes, pumps, trucks, you name it moving fresh concrete in the rising of the sun and the setting of the moon, in the cold of night and the blazing mid-day, midsummer, desert heat.

So I can understand but not countenancewhat happens at some dams, such as the one discussed in the link I provide above.

The real issues is once again to study this posting as yet another indiciaof how and why dams, both civil concrete and mining geowaste fail.