South African and tailings history are now richer as a result of a new book on Fraser Alexander. I have managed to obtain an e-copy of the entire book. I presume I am permitted to send you a copy if you cannot obtain a hard-copy. I am much indebted to those who arranged for me to get the e-copy. I will put you in touch with them if you email me.
When I first entered the world of South African tailings, Fraser F Alexander, or FFA as we referred to them, were the giants. Gary Rae was in charge and he was good, gracious, and kind to me. I owe him a great deal, for he taught me a great deal. He is retired now I am told and I have not seen him in decades. But what a fellow.
In 1978, I and my wife travelled with him and June, his wife, around the western USA. Fritz Wagener was with us too. We were looking at US tailings facilities; but along the way we saw so much that was new and had much fun. Gary and June were superb people: full of humor, laughter, and an appetite for life.
Mike Gowan, always a good friend, was at that time working for FFA as a civil and what we now call geotechnical engineer. He and I did many a slimes dam together. But both of us went to Gary for practical advice, courage to proceed, and new ideas that work. Mike is in a picture in the book–much younger than now but still with his flaming red beard.
The book tells a very different story from that which I heard in those early days about the very early days of the company—and for this we must be grateful, for Fraser Alexander truly deserves the credit the book gives him for a career well lived.
The book touches on the two great slimes dam failures that paved the way for so much change in the industry. I well recall the panics and work of the failure of the Impala Platinum Mine slimes dam. I eventually worked with Mike Gowan and Frasers to design and build the new dam which is still in operation. Here is something I wrote many years ago about the design of the new dam:
Carl Van Rensburg was a lead consulting civil engineer with Union Corporation. He loved meetings. He had overseen the Bafokeng slimes dam failure clean-up and was now in charge of building another to replace the one that failed. He had selected Oscar Steffen and me to do the design. We would prepare the drawings and take the short walk to the Union Corporation buildings. In accordance with security protocols, Carl had to come down to the foyer to collect you. He would march you up to the allotted conference room; where we would sit and talk for long hours to prepare the designs for the Bafokeng tailings impoundment .
The company Fraser Alexander founded still is a force in mining, both in South Africa and internationally. The fascinating bit is that Fraser Alexander is now owned by the Royal Bafokeng Nation. They are the folk in whose lands there are the platinum mines of the Rustenburg area. The introduction is signed by Kgosi Leruo Molotlegi, King of the Royal Bafokeng Nation. As the book puts it:
The Bafokeng number some 300 000 people with their own king, who ensures that their income is wisely invested in blue chip mining and manufacturing equities – prudent insurance in case platinum ever loses its gleam. In 2006 Royal Bafokeng acquired not just Absa’s shares in Fraser Alexander but all the others as well, proving it had confidence that the company’s best was yet to come.
Today, John Wates heads the tailings operations. As noted in the final part of the book:
Fraser Alexander Tailings, from 2011 led by John Wates, continued to operate in Chile and Australia and there were impressive projects in the rest of Africa. The division was eyeing Europe as well. It was highly satisfying that expertise perfected in the company’s home territories was being exported throughout the world. Nowhere was that expertise more valuable than in South Africa itself. The country had undergone radical change, and with it the mining industry. Never had there been a greater need for the innovative and reliable contributions that were Fraser Alexander’s hallmark. And never had the company been in a stronger position to fulfil the hopes of a demanding clientele.
In brief, this brief new book is full of information that adds to our knowledge of the history of tailings dams. We must thank those who put it together and put it out. Now let us urge others to do similar and expand the history of our profession. Here is a small contribution of something I wrote long ago—maybe it adds just a bit to the history that is so much richer than this one book can tell.
The Fraser F. Alexander gold mine slimes dam formula was used again and again with success on the gold mines. It was extended to the platinum mines. But there was a difference: the soils in the Bushveld are black clay a meter deep and have a plasticity index approaching fifty and cohesion of no more than 10 psi. These are weak soils because every season they expand and contract and move up and down and consequently are riddled with heave and shrink failure planes along which only a low residual strength operates. The platinum tailings are sandier than the gold tailings and do not “stick” together by negative pore pressure as effectively as the gold slimes.
The Bushveld is dry and water is at a premium. The top of the tailings impoundment was the cheapest place to store the water needed to operate the plant. One day the water pool at the Bafokeng Mine at Impala Platinum Mines came to close to the edge of the wall and a bulldozer was sent to rectify the situation. What happened next is conjecture in spite of many learned tomes. Some believe seepage occurred preferentially along a sandy layer and initiated piping. Some believe that the bulldozer sent to raise the perimeter wall initiated vibration-induced liquefaction. Some believe the bulldozer just squashed the soft sand too much and pushed the top of the dike down below the water level.
Regardless, the wall broke and the slimes flowed out inundating the shaft, killing thirteen, and spreading fifty miles downstream to clog the local dam.
Professor Jennings was asked to investigate the failure. As his student, I was sent to site to measure the failure zone, to describe the layers of sand and clay that he thought were the prime causes of the failure, and I did the donkey work in designing a rock over-flow dam to control further spread of the tailings which had flooded out of the center of the impoundment. Today that dam is called the Rockall dam and is still operative.
Then Oskar Steffen persuaded me to join SRK, for they had been retained by Carl Van Rensburg of Union Corporation to design a new impoundment. The replacement dam I designed for the Bafokeng Mine involved a series of smaller dams that in effect were taken no higher than practice had proven safe to create a series of stair steps around those parts of the perimeter that exceed 60 m in height.
This dam is still being used. It perimeter is longer than 12 kilometers. At its highest it is nearly 120-meters high. It is planned to go even higher. Over the years many have worked on the impoundment.
Rob McNeil in his first years with SRK worked at the site. There he met Ian Brackley who was the designer of record of the foundations and the first forty meters of the penstock towers which now rise to nearly ninety meters. Rob tells me they anticipated that solid rock for the penstock foundations would be available near the surface, just below the meter-thick layer of black clay that covers the site. By the time they had dug to nearly ten meters without finding the solid rock encountered everywhere else, they changed the design of the foundations—increase their area and reduce the stresses imposed on the underlying decomposed rock.
In Reno I chatted with Marija Jorcevic. She left Croatia in 1990 and went to South Africa and joined SRK. She worked many projects but the one that leaves me in awe is what she did at the Bafokeng impoundment: she went up the penstock pipes of the Bafokeng slimes dam on a self-powered trolley to inspect their condition. Many years ago, I had walked the length of the penstock pipes before and after installation. I knew the distance and the terrain. I had never been inside the pipes; and never will go into the pipes. More: she took charge of the monitoring and surveying of the dam, now rising to 120 meters. She is my heroine.
Gary Jones in the grand old man of SRK and for the past twenty years of the tailings group. He is now nearly seventy eight. Although he officially retired ten years ago, he still comes in two days a week to work on the Bafokeng project. Gary literally invented the piezocone—an achievement that earned him his PhD. He tells me of the innovative piezocone characterization of the Bafokeng dam he managed as part of a mid-life review of the facility. He and his piezocone had gather data about the layers and pore pressures in the dam that I could only dream of when we designed it.
Work is now under the direction of Adriaan Mentjes, who told me in early 2010: “We raised the height of the two penstocks from fifty meter to one hundred meters. The most difficult job I have ever undertaken was designing the causeway out over the soft tailings to create a dike capable of carrying the trucks needed to transport the concrete to over the beach and through the pond to the penstocks being raised. We succeeded by placing cyclone underflow in the pond to create a stable berm. I also take pride in correctly calculating the amount of settlement the slimes would undergo during penstock raising.
Currently Graham Howell is evaluating the relining of the penstocks. I admire his courage, but wish he would abandon those penstocks and do what we originally intended: grout them up and install a barge on a pool far from the higher parts of the perimeter.