Many are the voices that tell us we should let go of the past and concentrate on today and the future – but what happened decades ago still has the power to affect us and even endanger us.

And there’s no better example of that than what is currently happening to the M2 highway in Johannesburg.

When it was built, back when Johannesburg was still the centre of a gold mining powerhouse, engineers used sand recovered from gold dumps or tailing dams in the foundations of the civil works, such as bridge supports.

In those days, the sand would have been worth little because the gold it contained – along with myriad harmful chemicals – wasn’t worth the effort of reclaiming.

Now, however, the gold price is soaring and bands of illegal miners using primitive, but effective methods, are mining that sand to get the gold.

And, because they don’t care what damage they cause in the process, the very foundations of the M2 are under threat.

That’s the legacy of the mining industry in the apartheid years which no one wants to debate, according to mining expert and activist David van Wyk.

He also points out the zama zama illegal mining exacerbates the already serious problem of growing acid mine drainage in the mining voids under the southern parts of Johannesburg.

Our pictures today tell that worrying story. But, more than that, the imagery begs the question: why has nothing been done, other than the Joburg Roads Agency posting similar photos on social media?

This illegal mining didn’t happen overnight and, while we acknowledge that zama zamas are armed and dangerous, this situation is a direct threat to the community and the cops, along with the military, should have been deployed long before now to put an end to it.

Why do we have to wait for a tragedy before we act?