Another sensible question again, yet another light bulb. The...

Another sensible question again, yet another light bulb.

The design and operation of :- Tailings dams, Tailings Storage Facilities or Containment Facilities is a highly complex process, that I have to admit I am no expert at, even though I have built several. The complexity required depends on numerous parameters, the nature of the materials to be contained and the local environment being paramount. Acid drainage has been one of the most discussed problem amongst Environmental managers over the last 30 years. Most mines up until the 90's thought a clay lined dam was all that was needed to confine process waste, they were wrong. Most mines contain Sulphides ~ Pyrites etc, which once exposed to Air and moisture produces Sulphuric acid ~ which over time will degrade any clay lining in a dam and lead yp potential wall ~ collapse. very expensive to remediate ~ just ask Vale !

Other considerations are climate and seismic stability, In many places even in Australia and probably Uganda, Rainfall exceeds precipitation so any containment structure may eventually top up and overflow, one good reason to cap the dam at the end of its life also to channel any surface run off waters away from it. The other big consideration is seismic activity, it does not take much of an earthquake (a scale 4 will do it) to liquify a seemingly dry dam, now dams are usually designed and built to withstand a scale 7+ event or even a scale 9 in areas of high seismic activity, which in theory is probably fine, unless that acid drainage has weekend it after 30-50 years

Now Makuuta should not have to contend with much acid drainage as there should be very little Sulphides in the already oxidised levels from which t they are mining the clay. However Uranium and Thorium present a totally new and somewhat different problem ~ they don't degrade,. they are still going to be where IXR leaves them in 1,000 years time. So any containment structure will have to withstand Earthquakes (in a high risk area) and be kept as dry as possible to prevent liquification for a very long time. Believe me when I say that design and construction of a large TSF to meet that specification is no just as simple as thickening the retaining wall !

Luckily plastic is almost as non degradable as U & Th so a fully lined (double/triple layers of clay and HDPE) and capped containment structure preferably at or slightly below surface level with minimal walls should suffice. Hence why I say "Properly Engineered" (by experts).

I have said all along, that if done properly, there should be no problem, but seeing as that EISA does not even consider the presence of U & Th in the clays, I doubt if anybody has bothered to analyse the problems they might create, yet alone address them.

And that statement they made about "No Legacy hazards" confirms that they are either deliberately misleading the Authorities or don't have a clue themselves !