The development of a pre-mining groundwater monitoring network for open pit mines in South Africa

English: After the discovery of minerals mining formed the backbone of the South African economy for more than a century. The contribution that mining had on the economy is probably best reflected when the country’s currency was changed to the Rand (which refers to the gold deposits of the Witwatersrand) in 1961. Although there have been a down scaling in production of some minerals over the last couple of decades the country is still a large producer of numerous commodities and dispose of mineral deposits matched by only a small number of countries. Without a doubt mining will still prevail as a pillar of the economy in the years to come. Although the mineral industry in South Africa consumes a relatively small quantity of groundwater abstracted (13 percent) the use of water at mining operations has the potential to affect the quality of surface as well as groundwater. The abstraction of groundwater to ensure safe mine activities at especially open pit mines have a negative impact on the surrounding water sources. Groundwater play an essential role in South Africa as two thirds of the country’s rural population is depended on groundwater for their domestic needs while it is also an important source of water for numerous towns. The management and protection of the country’s water resources cannot be stressed enough as South Africa is ranked as the 30th driest country in the world. The protection of the country’s water resources gain momentum in the late 1990’s when a number of Acts, the important ones from a water resource point being the National Environmental Management Act (NEMA); Act 107 of 1998 and the National Water Act, Act 36 of 1998 were promulgated that placed strong emphasis on equitable access for all residents to the country’s water resources. In the mining sector groundwater monitoring are usually done for two reasons, the one to obtain the necessary data/information needed to develop the water management and monitoring programmes for the mining operation to effective protect and manage the groundwater resources in the area they operate within and the other to comply with the environmental and water licence regulatory requirements. The literature review and in particular the first-hand experience as documented and described in the case study form the corner stone of the guideline developed for the set-up of a pre-mining groundwater monitoring network for open pit mines. The different phases for the set-up of the monitoring network is discussed in detail in the dissertation and can be summarized as follow: Monitoring objectives - For any monitoring programme to be successful clear objectives must be set on what exactly needs to be achieved with the focus on efficiency and practicality. A thorough understanding of the hydrogeological characteristics of the aquifers must be gained that informed decisions can be taken to effectively protect and manage the water resources.  Desktop study – A desktop study must be performed in order that all available geological and hydrogeological reports, data and information of the area are sourced that a conceptual model of the area can be formalized. This is vital in the planning of the fieldwork to obtain the necessary hydrogeological information needed to fully characterize the water resources in the study area.  Planning of hydrocensus – Evaluation of the data sourced during the desktop study will give guidance in demarcating the area that needed to be surveyed during the hydrocensus and also provide a good indication what to expect during the census. Effective and good communication with land owners regarding the hydrocensus is of cardinal importance as this will determine right from the start the success of the hydrocensus and the co-operation from the land owners.  Data acquisition during hydrocensus – During a hydrocensus not only water level data must be obtained but all available information regarding the boreholes for example the water strikes and depths, yield and usage, geology and water quality. Other data such as rainfall and information on the water infrastructure network and the number of stock dependant on a watering point is also important and must also be noted during the hydrocensus survey.  Set-up of a monitoring network - The exact number of monitoring points for a specific monitoring programme is always debateable. The monitoring objectives together with the hydrogeological conditions plays the major role in determining the number and position of the monitoring points while the site specific conditions (accessibility and topography) must also be taken into account when designing the monitoring programme.  Evaluation and analysing of data – Evaluation and analysing of the monitoring data is indispensable in understanding the hydrogeological characteristics of the aquifers in an area and to update and adjust the conceptual model as outlined during the desktop study. Interested and affected parties – The efficiency and success of a monitoring programme will greatly depend on the relationship between the mining company and the land owners. It is necessary that an Environmental Forum be established that can be used as a platform for communication between the parties to ensure that the environmental aspects of which water is usually the main discussing point can be administered and managed in an effective manner that will be beneficial to both parties.  Validation of monitoring network – The monitoring network needs to be validated on a continuous base to ensure that it still complies with the monitoring objectives as for example changes in the mine’s water usages or modifications in the environmental legislation will necessitate that the monitoring objectives be adjusted accordingly.  Review and update of monitoring network - The evaluation and analysing of the monitoring data will indicate areas where additional data is needed or where excessiveness of data is present. In data scarce areas it might be necessary for boreholes to be drilled or that the monitoring area be expanded to include boreholes from adjacent areas while in areas where there is excessive data the monitoring points can be decreased or the intervals between the monitoring periods can be lengthened. The set-up and development of a monitoring network is not a once off occasion but an iterative process that must be evaluated at least once a year and the necessary changes implemented where necessary to ensure that the monitoring programme give a true reflection on the behaviour of the groundwater resources that are monitored otherwise it will not be possible to protect and manage the groundwater resources in a responsible and effective way. Taking in account that every mining activity and its site conditions is unique it must be bear in mind that some of the guidelines described in the dissertation for the set-up of the monitoring network might not be practical or applicable and will need to be adjusted to fit the specific site conditions.