Coal is mined at Landau Colliery from the No.1, 2, and 4 Seams of the Witbank Coal Field.

The eMalahleni area is underlain by the Karoo supergroup. The Karoo Supergroup comprises mainly a sedimentary succession of sandstone, siltstone, shale, mudstone, coal, diamictite and tillite. The Karoo Supergroup is lithostratigraphically subdivided into the Dwyka, Ecca and Beaufort groups, succeeded by the Molteno, Elliot and Clarens formations and the Drakensburg Formation. The Ecca Group comprises successions of formations which consists of sandstone, shale and coal and were developed within the Karoo basin locally. A number of intrusive dykes are known to occur within the study area. The positions of the dykes have been interpreted from geophysical surveys, but have mostly been delineated through mapping when intersected in the underground workings (Groundwater Complete, 2013).

The thickest portions of the Ecca Group were deposited in the southern Karoo basin in contrast to the relatively thin sequence which is now preserved in the East Rand. This succession of sedimentary rocks generally overly the well-consolidated conglomerates/diamictites of the Dwyka Formation, but in places the Ecca Group rocks rest directly on the felsites and granites of the pre-Karoo Basement rocks. Igneous intrusions of late Karoo Supergroup age in the form of dolerite dykes and sills also occur through the sedimentary succession. The sills usually precede the dykes, with the latter being emplaced during a later period of tensional forces within the earth’s crust. Tectonically, the Karoo sediments are practically undisturbed. Faults are rare. However, fractures are common in competent rocks such as sandstone and coal.

The sediments of the Vryheid Formation overlie an uneven Dwyka floor, which is controlled by the topography of the pre-Karoo platform upon which the Karoo sediments were deposited. The Vryheid Formation is present throughout the Witbank Area. At their thickest these sediments attain some 120 – 140m and can contain a number of coal seams of which four are considered to have economic potential. This area is known as the Witbank Coal fields.

The Navigation West Section is situated in the northern part of the Witbank coalfield. The coal measured forms part of the Vryheid formation of the Ecca group. All five coal seams, common to the Witbank coalfield, are present in the Navigation West Section area. The No. 4 Seam is suitable for mining by opencast methods. The No. 2 Seam is mostly thin and of moderate to low quality, as are the remaining No. 3, 4U and 4A Seams. The No. 5 Seam ‘sub-outcrops’ near the eastern boundary of the proposed mining area, and although of good quality, is not laterally extensive enough over the Navigation West Section to include in the mining plan.

The No. 4 Seam dips predominantly to the east, but also to the west (in the extreme west) as it is draped over a regional Pre-Karoo basement high. It is over the western part of the area that the No. 4 Seam is completely weathered as a result of its close proximity to surface. This ‘no coal’ area forms a major indent into the South Block and had a defining influence on the mining layout possibilities. The topography to the west, influenced by the upper reaches of the Grootspruit valley, dips fairly steeply towards the west, resulting in a sub-outcrop of the No. 4 Seam. To the east, the various seams dip at about 30 minutes towards the Greenside Colliery underground reserves, where all of the major seams have been preserved and mined to some extent.

Coal is mined at Landau Colliery from the No.1, 2, and 4 Seams of the Witbank Coal Field using opencast methods. Landau Colliery proposes to extend the Life of Mine at the Navigation Section by expanding the mining of the Navigation West: South Block opencast pit.

Mining at Navigation West Section is currently done at the North and South Block and coal is crushed and washed at the Ngwenya Plant within the boundary of the Navigation West Section.

There are two plants at Navigation Section where coal can be processed and both will be utilised for the proposed Navigation West – South Block Extension Project. The Ngwenya Plant is located within the boundary of the Navigation West Mini pit on Portion 2 of the farm Elandfontein 309 JS. The other plant is the main Navigation Beneficiation Plant located on Portion 23 of the farm Blaauwkrans 323 JS near the old Navigation dump.

ROM coal mined at the Navigation West Section is hauled to the Ngwenya Plant, where is offloaded at the ROM tip and is crushed and stockpiled before being transported to the domestic market(s). It is proposed that the existing crusher at the Navigation West section will be upgraded with a new secondary, reversible 1800 feeder (refer to Part 6 for the alternative option considered in terms of the crusher).