Extracts from Environmental Impact Assessment Briefing Document issued by Sasol
This briefing document forms part of the first or scoping phase of the Environmental Impact Assessment (EIA) for the Sigma Colliery's proposed North West Strip mine (see map) near Sasolburg in the Freestate Province. It aims to provide information on the proposed project, explain the EIA process, explain how Interested and Affected Parties (IAPs) will be consulted, and invite AIPs to assist the EIA project team by raising their concerns about the project during the scoping phase.
The EIA will be undertaken by Walmsley Environment Consultants for Sigma Colliery. Communication with IAPs will be ongoing during the course of the project and include meetings, newsletters and review of the draft Environmental Management Programme Report.
The economic viability of Sasolburg is still very dependent on Sasol Chemical Industries (SCI). SCI requires 7 000 000 tons of coal every year to continue production of more than 100 chemicals and employment of approximately 3 000 people.
SCI's entire coal requirement was supplied by the Sigma Underground Mine from 1952 to 1992. In recent years increasingly difficult underground mining conditions, caused by unforeseen horizontal stresses in the geological strata of the remaining reserves, have resulted in progressively lower production from the mine. Despite the introduction f cutting machines with onboard roofbolters to try to prevent rooffalls, production remains very low while mining costs continue to rise. Production of only 3.4 million tons is forecast for 1995/96 and it is clear that the underground reserve has reached the end of its economic life.
In 1992 Wonderwater strip mine was established to partially replace the production capacity of the underground mine. Now a new source of coal is required to replace the remaining production from Sigma Underground Mine and ensure that SCI's coal requirements are met.
A number of alternative coal supply options were evaluated on technical and economic grounds and the North West Strip mine was considered the most viable option for further investigation.
During the construction phase boxcuts will be excavated using truck and shovel methods with blasting as required. Overburden will be stockpiled to form a berm between the mining area and the 1:50 year floodline of the Vaal River. The berm will be approximately 25 - 30 m high and 250 m wide at its base, except adjacent to the Rietspruit (see map), where it will be 10m high, initially. The primary purpose of the berm will be flood protection and screening of the mine for surrounding residents.
A conveyor will be constructed from the Uitkomst Shaft to the Boschbank shaft area. The access road to the Boschenvaal resort will have to be relocated off the mining area. In the long term the Barrage road will have to be relocated further southwest to skirt the mining area.
A section of the Rietspruit will have to be diverted to the east with the construction of a dam on the eastern perimeter of the mine. A canal will link the dam to the Vaal River. Electricity lines and an effluent pipeline across the site will have to be rerouted.
Approximately 100 workers will be employed during construction. Existing accommodation in Sasolburg and offices and workshops at the Uitkomst shaft will be utilised to house staff during the construction phase. No additional facilities are proposed.
During the operational phase draglines will be located in the boxcuts and the area will be mined in strips on the NNW-SSE axis progressing in a southwesterly direction. The mining plan is based on a requirement to maximise the strip length, avoid the dolerite cap that covers the southwestern section of the reserves for as long as possible, even out the ash content of coal reserves and befit the boxcut closest to the point at which the berm will be constructed.
During the operational phase the overburden will be removed using a dragline and coal will be mined using truck and shovel methods. During the first year the mine will produce about 400 000 tons increasing to 4 million tons per annum by the third year of operation.
The coal will be taken to the Uitkomst shaft for crushing and blending and onward transport to SCI by conveyor with Wonderwater coal.
As mining progresses, topsoil will be stripped and stockpiled or used for rehabilitation of mined out areas. During the first year of mining the 10m high berm around the Rietspruit will be built-up to a height of 30m. Revegetation of rehabilitated areas will occur after landscaping.
The operational mine will provide employment for 200 - 250 people. Use of existing facilities for accommodation and offices will continue as during the construction phase. Staff will be transported to the mine by bus or use private cars to get to work. No staff will be housed on the site.
The proposed mining area covers sections of the farms Rietfontein 123 and Uitkomst 413 in the Sasolburg District and lies adjacent to the Vaal River (see map).
Three coal seams occur in the area. The remaining geological strata consist of siltstoe, mudstone, sandstone and tillite overlying a dolomitic basement. A capping of dolerite covers the southwestern part of the site.
The area falls within the Highveld climatic zone where rainfall is mainly in summer in the form of convectional thunderstorms. The average annual rainfall for the area is 677mm.
In summer the wind blows most frequently from the southwest, westerly, northwesterly, northeasterly and easterly sectors. During the winter months winds from the southwesterly, westerly and northwesterly sectors are most prevalent.
The site is bounded in the southwest by the Barrage road at an altitude of 1440 metres above sea-level (masl) and gently descends to the Vaal River at 1423 masl on the eastern boundary. The highest point (1455 masl) is on low ridge which protrudes into the eastern corner of the site. The Rietspruit River runs through the site from its southern boundary to the Vaal River in the northern corner.
The majority of the soils over the area are deep (500 - 1200 mm) and include Lonlands, Kroonstad, Avalon, Fernwood, Glencoe, Clovelly soil classes. Shallower soils (300 - 900 mm) occur adjacent to the Rietspruit include Rensburg, Estcourt, Westleigh and Valsrivier soil classes.
The proposed mining area covers agricultural land of which roughly 51% uncultivated or fallow lands (408ha) and the remainder (392 ha) is used for grazing. A farm homestead (Uitkomst) is located on the low ridge in the eastern corner of the property. A homestead and farm labourers' houses (Rietfontein are situated on the southwestern boundary against the Barrage road.
Land used surrounding the site on the Freestate side of the Vaal River is mainly agricultural and mining. A housing development called Boschenvaal is located approximately 800m to the east of the mine perimeter, between the Vaal River and a ridge.
The Sigma underground mine lies to the southeast with the Uitkomst shaft adjacent to the site. The homestead and/or compounds of the farms Beginsel, Brakkuil Tweelingsfontein and Goeweneurskraal lie to the south of the mine perimeter. The homesteads of Petronella, Smaldeel, Rivierplaas and Fraaiuitzicht occur to the west of the mine perimeter (see map).
On the Gauteng side of the Vaal River, immediately across from the mining area, are located a large number of small holdings with cottages and residences. These include areas known as Vaalview, Stille Waters, Three Oaks, The Stables, Vaia Con Dios. Marlbank River is situated to the east of the mining area across the river from Boschenvaal.
The mine site falls within the northern variation of the Cymbopogon-Themeda Veld (Acocks Veld Type No 48) which is a sparse tufted veld type. Grass species such as Setaria flabellata, Themeda triandra, Heteropogon, contortus, Eragrostis racemasa and Cymbopogon plurinodis are common in this veld type. Trees such as Fire Thorn Rhus pyroides, Acacia's Acacia spp and Buffalo Thorn Ziziphus mucronata also occur on the site.
No threatened amphibians, reptiles or fish that are listed in the Red Data Book occur on or near the mine site. The following threatened bird and mammal species may occur in the area:
Grass Owl Tyto capensis Indeterminate
African Finfoot Podica senegalensis Indeterminate
Small spotted cat Felis nigripes Rare
Aardwolf Proteles cristatus Rare
African striped weasel Poecilogale albinucha Rare
South Africa Hedgehog Atelerix frontalis Rare
Antbear Orycteropus afer Vulnerable
White-tailed mouse Mystromys albicaudatus Vulnerable
The Vaal River forms the eastern boundary of the site while the Reitspruit stream flows diagonally across the site from south to north before joining the Vaal River. The Vaal River is one of South Africa's most important water resources, supplying water for industrial and domestic consumption to the industrial heartland of the country, Gauteng Province. Soon after passing the mine site the Vaal River flows into the Barrage which is one of the extraction points for water supply to Gauteng. Irrigation also occurs along the Vaal River.
Groundwater resources in the area are probably used primarily for domestic consumption and for limited irrigation.
Most pollution sources in the industrial areas of Sasolburg and Vanderbijlpark are situated a number of kilometres to the north and the southeast of the mining area. Regional air quality of the Vaal Triangle is generally considered to be poor as a result of the multitude of industrial pollution sources and dust from cultivated agricultural land.
In winter local air quality is likely to be affected by stable climatic conditions that hamper pollution dispersion and dry conditions that promote dust formation. Dust from agricultural lands is likely to be worst in August-November when farmers till the soil prior to planting.
The river is heavily utilised for skiing and motorboating on weekends.
The occurrence of archaeological sites in the mining area is unknown at present. However, a number of graves are likely to occur on the property.
Most of the mining area is visible from the Barrage Road, adjacent farmhouses and weekend residences immediately across the Vaal River. The views of the mining area from many of the latter may be obscured by trees growing around the houses or on the banks of the Vaal River. The mining area is obscured from houses further away from the eastern bank due to a combination of tall trees and relatively flat land. The most easterly boundary of the mining area is just visible from the higher lying houses in the Boschenvaal development.