Wetlands in the proposed mining area are generally of low conservation status and by their nature play no significant role in sustaining baseflows in the Rietspruit or promoting water quality in Cloudy Creek or the Vaal Barrage. Much of the former wet meadow area on the mining area has been ploughed and drained and colonised by weeds. Consequently, the loss of the wetlands on the site will have a LOW negative impact locally. However, the cumulative loss of wetlands on a national scale, to which this small local loss adds, is HIGH negative.
The majority of the wet meadow occurs to the west of the proposed mining area. Due to the nature of its soils and hydrology the impact of mining operations on this wetland will be LOW. Damming of water behind this southern extension of the berm will change the nature of the wetland slightly and is likely to enhance the heterogeneity of its habitats and increase its conservation value, having a LOW positive impact. The longer periods of inundation of the area will increase its sedge vegetation, having a MODERATE negative impact on the grazing value of the area on Rivierplaats.
The Rietspruit acts mainly as a channel to direct ephemeral flows into the Vaal River and plays no significant role in improving water quality flowing through it. Its diversion will have a LOW negative impact on water quality in Cloudy Creek or the Vaal Barrage.
During the construction phase of the berm and river diversion, impacts on surface water quality and catchment yields will be LOW negative. Water-make in the mine from the shallow and intermediate aquifers will be manageable with the implementation of the proposed water handling facilities and no discharges of poor quality water to the Vaal River will result from mining of these aquifers. NO IMPACT on surrounding boreholes should result from the dewatering of the shallow and intermediate aquifers. If boreholes are affected Sigma Colliery will supply the affected users with water of a quantity and quality equal to the water lost.
One outstanding question on ground water needs to be answered with greater certainty. This relates to the potential rate of inflow from the deep aquifer into the mine. Geohydrological work to date indicates that rates of inflow will be low to moderate. However, due to the known variability of dolomite, a cautious approach has been adopted and further drilling and long duration pump tests have been commissioned. Information obtained from this work will be included in the final Environmental Management Programme Report.
The construction of the berms will have NO IMPACT on water levels during 1:50 or 1:200 year floods. In the case of the latter, houses on the Gauteng side of the river will be 6-8m under water and the berms will have no additional negative effects.
Migration of polluted water from the mining area at closure will be prevented by the excavation of an in-pit evaporation facility which will draw down the groundwater level to below the level of the bed of the Vaal River and effectively act as a sink for pollutants.
HIGH to VERY HIGH negative impacts on the most sensitive receptors around the proposed NWSO site could result from total suspended particles if dust control is not managed effectively. A 90% dust control efficiency can be achieved through use of a combination of water and chemical binding agents on haul roads. These methods will reduce the negative impacts to LOW to MODERATE (below Department of Environmental Affairs and Tourism and US EPA guideline levels). During 24 hour storm events from the southwest, levels of total suspended particles at Boschenvaal will still be HIGH despite a 90% dust control efficiency on haul roads. Special operational procedures during these events, including cessation of mining during these storm events, will have to be considered to mitigate this impact. Dust fallout of heavier particles will be restricted to the mining area.
Blasting vibration will not affect any structure in the vicinity of the mine during the construction phase and during most of the operational phase. Impacts on Smaldeel farmhouse may, however, result in the last few years of mining. This house is within the 500 m blasting zone limits stipulated in the Minerals Act and special exemption will be required to blast within this area. Relocation of the caretaker family living in the farmhouse will be negotiated if the project proceeds.
Apart from impacts on fish, which are likely to be HIGH negative during the early years of mining, impacts on domestic animals are unknown due to the paucity of research in the field. Peak particle velocities reaching domestic animal farms in the vicinity of the proposed NWSO are very low and NO IMPACTS are expected but this prediction is uncertain. Vibration impacts on fish will abate as mining proceeds away from the Vaal River.
Due to the construction method of the berms and proposed mitigation of conveyor noise by a 2m high wall, noise impacts due to mining will be LOW to MODERATE negative. This equates to an increase in ambient noise levels of 2-5 dBA at which little community response with sporadic complaints would normally be expected according to SABS standards. However, the highly sensitive nature of the community around the mine and their complete opposition to the proposed mining operations could elicit an unpredictable response.
This assessment does not take into account, single sharp noisy events such as blasts or engine starts in exposed positions and a range of management measures are proposed to minimise these impacts. Prearranged blast times and stemming of blast holes are the most effective methods of mitigating blast noise. No blasting will occur over weekends. Blast noise impacts are likely to be HIGH negative but are of short duration and occur once a day.
The highest visual impacts of the mine will occur during the construction phase and will be experienced by residents on river properties opposite the mine. The time scale for the impact is estimated at about 9 years. Impacts over the period will vary from LOW to VERY HIGH negative during the various phases of berm construction. As the berms revegetate this impact will diminish until the berms begin to have a HIGH positive impact on the overall scenic value of the area by adding topographical variety to the existing flat landscape.
Once the berms are up negative visual impacts will reduce significantly to LOW to VERY LOW levels over the life of the mine for river property owners and Boschenvaal residents. Over the life of the mine negative visual impacts will progressively increase to HIGH to VERY HIGH levels for the southwestern sector, such as views from the Barrage road. These impacts can be mitigated by screening views from the realigned Barrage road using trees. The conveyor will have NO IMPACT on views from Boschenvaal and VERY LOW negative impacts on river property owners.
Macro-economic Impacts
In terms of direct economic impacts, the proposed NWSO would maintain the status quo at the regional and national level. At a local level there would be some short term (1-4 years) losses experienced by Sasolburg due to the reduction in employment levels. These losses would be Secunda's gain if the offer of re-employment was accepted by the retrenched mine workers. However, after five years, when the proposed NWSO was in full production and the loss-making underground operations were closed, the Gross Geographic Product (GGP) of the region should experience a small gain.
The combined indirect or spin-off effects of the downscaling of Sigma Colliery: Underground Operations and the development of the North West Strip Operation would generally maintain the status quo at a macro-economic level. The development of the NWSO would therefore have a major role to play in underpinning the economy of Sasolburg. The combined effects of downscaling of underground operations and upscaling of the NWSO would have NO IMPACT (either positive or negative) relative to current levels of economic activities at a macro-economic level. This is because intermediate purchasing and expected coal output at the NWSO would counterbalance the potentially significant negative effects of the cessation of underground operations. The NWSO could potentially induce additional benefits to the manufacturing sector of R16.2 million in 1997/98, R97.2 million in 1998/99 and R162 million in 1999/2000 and each year thereafter.
Cessation of Sigma Colliery's underground operations without the NWSO proceeding, might result in a VERY HIGH negative indirect impact on the economy of Sasolburg and the region, assuming an alternative source of affordable coal cannot be found. This would be due, in particular, to mining's strong forward linkages with the manufacturing sector which uses approximately 90% of coal mining's output.
Residential Impact
A number of riverfront properties in Vaal View, Ardenwold, Driefontein and Marlbank would experience HIGH negative impacts initially, primarily due to the visual intrusion of berm construction and site preparation. Once berm construction is completed, after about 9 years, the operation of the mine would have a LOW negative impact.
The potential diminution of the enjoyment value of riverfront properties would be reflected in a HIGH negative impact on the prices of these properties until berm construction and revegetation was complete. Estimates put this reduction in value at between 9 and 19% in the first ten years of operations and 2 and 6% for the remainder of the mine's life. After mining is completed there will be NO IMPACT on property prices.
Despite the proximity of Boschenvaal to the NWSO, the topography of the adjacent ridge would screen residents from most of the mine's impacts provided stringent control measures are implemented.
Properties which do not have direct river frontage would probably experience NO IMPACT from the NWSO, primarily because of their distance from the proposed mining operations.
Impacts on boating on the Vaal River will be LOW to VERY LOW negative in the short term while birdwatchers at Cloudy Creek and along the Rietspruit and fishing in the vicinity of the mine would experience VERY HIGH negative short to medium term impacts. If the proposed mitigatory measures are implemented, birdwatchers could experience a HIGH positive impact when the berms are completed.
Many of the attributes of the affected stretch of the Vaal River, which encapsulate its intrinsic value, cannot be rendered in discrete quantitative terms. For many residents the proposed NWSO represents an intrusion into an area which they value for its relative tranquillity, because they believe this intrusion would be absolute, it could not be mitigated against. Direct experience and the passage of time could lessen the perceived intrusion and thus perhaps offer some mitigation.
Agricultural Impact
The impact of the proposed NWSO on the agricultural economy of the Sasolburg region will be VERY LOW negative. For the three farms on which the proposed mining operation would take place, the estimated total economic impact on farmers, markets and input suppliers over the 20 year life of the NWSO is lost income of R65 million. The indirect economic impacts on adjacent agriculture enterprises cannot be quantified at this stage but are expected to be insignificant. Longer term impacts would depend on the success of the soil rehabilitation programme.
HIGH negative impacts will be experienced by the estimated 80 farmworkers and others currently living on the properties where mining is proposed. They face relocation, social dislocation and the possible loss of housing and jobs. These impacts could be mitigated through negotiation and support to assist them to find alternative accommodation and employment.
Post-mining topography over the mining area will emulate that of the pre-mining condition, except where an inpit evaporation facility is proposed and impacts will therefore be LOW negative. By adding topographical variety to the existing flat landscape, the construction of the berm will have a HIGH positive impact on the overall scenic value of the Vaal River from viewpoints across the river once it is completed and vegetation has established.
The site is generally marginal for agriculture. Provided soils are properly handled, ameliorated and rehabilitated after mining, impacts on soils and land capability will be LOW negative in the long term.
Mining will have a HIGH negative impact on current land uses for its duration. Currently Rietfontein is a private nature reserve and Uitkomst and Petronella are used for agriculture. The Vaal River Complex Guide Plan of 1982 does not regulate mining activities. Consequently, the nature area zoning over parts of the proposed site will not preclude the proposed mining activities.
Based on current knowledge the mine will have NO IMPACT on threatened plant taxa. A number of small populations of species protected under the Free State Nature Conservation Ordinance will be affected by the mine. Special permission may be required to relocate specimens.
The majority of the site (61%) has been disturbed and fragmented by agriculture. A large section of old lands on Rietfontein has been invaded by weedy species including former wetland areas which have been drained and ploughed. Notable exceptions to this overall picture are the bottomland grassland adjacent the Rietspruit and bushclump communities around the ridge in the east. Mining will completely remove the former while the latter will be peripherally affected.
The loss of some of the bushclump community will be more than compensated for by the revegetation of the berm with trees, grasses and shrubs. Some compensation for the bottomland community will be achieved through the judicious rehabilitation of the northern section of the river diversion. Due to the changed hydrology of the area after mining the bottomland grassland is unlikely to re-establish within the mined-out area. This negative impact is HIGH on a local scale and LOW on a regional and national scale.
During the construction period, bird communities in Cloudy Creek will experience a HIGH negative impact. Once the berms have been constructed, these impacts will abate to a significant extent. Careful manipulation of the connection of the river diversion to Cloudy Creek could result in habitats for the affected bird species being significantly enhanced with a HIGH positive impact for local populations.
Habitats for a number of threatened or near threatened species such as the Grass Owl will be reduced by the removal of the bottomland grassland which will have a HIGH negative impact locally but a LOW to VERY LOW impact nationally on populations of these species.
No endangered mammal, reptile, fish, amphibian or butterfly species will be affected by the proposed mining operations. A number of vulnerable species of mammals will lose some of their habitats temporarily. With a sound rehabilitation programme, habitats for the terrestrial species will be enhanced after mining.
Fish in Cloudy Creek and the Vaal River adjacent to the mining site will experience HIGH negative impacts due to silt movement during the establishment of the river diversion and blasting vibrations. Fishing in Cloudy Creek and piscivorous birds are likely to experience HIGH negative impacts during the construction phase. Once mining moves away from the river these impacts will abate significantly.
Provided effective mitigatory measures are implemented during the construction of the conveyor over an iron age site and the correct procedures are followed in the relocation of the two grave yards on the site, NO IMPACTS on cultural resources or the graves should occur.
Some of the potentially most severe impacts of the mine have been avoided in the mine design and proposed operational procedures. To ensure that the findings of the impact assessment sections of this report are realised, it is essential that the procedures for the proposed mining operations are strictly adhered to.
Many of the predicted impacts of the proposed NWSO will be high if not properly mitigated. A detailed rehabilitation plan and key management objectives have been developed to achieve the desired level of mitigation. The environmental management plan reduces most high impacts to a moderate to low level.
Consistent implementation of a high standard of environmental management will also be essential to ensure that mitigatory measures are effective. Although the Sigma Colliery: Wonderwater Operations have broken new ground in this respect it is recommended that an ISO 14001 management system be developed and implemented at the NWSO if it proceeds. This will provide an auditable system that will contribute to the maintenance of high environmental management standards on the mine. Independent annual audits of the system may also help to allay some of the fears of river property owners.
It is also recommended that all contracts relating to service provision or mining work on the NWSO site contain penalty clauses relating to environmental practice. Environmental awareness should be included in the site induction course for all Sigma and contract staff with refresher courses run on a regular basis.
An environmental control officer and assistant will be required at NWSO. This officer should report directly to the production manager. It may also be worth investigating the possibility of linking merit increases of all staff on the mine to environmental performance to provide an additional motivating factor for high standards of environmental performance.