Most tailings impoundments in South Africa are constructed by the upstream method. The dry climate, low seismic risk and availability of relatively flat ground ensure the continued use of such methods. However the centreline method of constructing tailings impoundments is advantageous if either
The terrain is steep or mountainous
Earthquakes may liquefy the tailings
Pollution control requires an impermeable core, or
Seepage control to preclude piping is desirable.
This paper describes the basic elements of the centerline construction of tailings impoundments. Centerline impoundments discussed in the literature and two recently designed by the authors are described in order to illustrate the main features of such impoundments. The following aspects investigated or evolved during the design of the two planned impoundments are discussed in some detail:
Stage curves in impoundment design
The mass balance of an impoundment
The static and dynamic stability of centerline embankments.
In 1847, the Regiment 73rd Foot, on reaching the vicinity of the mouth of the Buffalo River, where East London now lies, initiated the procurement of a fresh water supply for the area. The tiny camp relied for its entire water requirements on a small spring which was found and utilized on the slope below the present Hood Point Lighthouse. Captain William Baker of the Royal Engineers was attached to this infantry regiment and he is credited with having found the spring, which became known as Baker's Wells and was the chief source of supply for the settlement for many years.