Article provided by Agri SA
South Africa is a water-stressed country, (Figure 1) currently ranking as the 30th driest nation in the world (CER, 2016). Water quality, quantity and poor sanitation leads to 30 000 deaths globally every day, with 80% of such cases taking place in rural areas (Ochieng et al., 2010). Considering the abovementioned, water needs to be managed in a sustainable way, ensuring equitable access for all.
As per Section 27 of the Constitution of the Republic of South Africa, 1996 (Act 108 of 1996), everyone has the right to adequate water supply. The main constraint on water resources is competition from different sectors. Fracking is one process that competes for water resources.
Agri SA is currently conducting a desktop study to inform the farming community of the potential risks and benefits associated with shale gas extraction, with a specific focus on the Karoo region of the Western Cape. This article focuses on fracking and its potential risks regarding water resources.
Water security in the Karoo is of major concern due to the region being particularly dry (DMR, 2012). Water supplies are under continuous stress as a result of pollution and depletion, while water demand is continuously rising owing to population growth, industrialisation, mechanisation and urbanisation.
These increases in water demand and scarcity affect social and economic development – and by extension poverty, hunger and disease (Ochieng et al., 2010). Shale gas development is a water-extensive process, and would increase pressure on the availability of sufficient water of an acceptable quality – almost certainly affecting supply in an already arid Karoo.
Volumes of water required
Shale gas development is water-intensive, with each well requiring between 10 000 and 25 000m3 of water to be fractured (DMR, 2012). The Department of Mineral Resources (DMR) recently suggested that as much as 24 000m3 may be necessary for fracking. To put this number in perspective, it is equivalent to the irrigation of 3ha of lucerne for one year (DMR, 2012).
Surface water availability is generally low, and the water available is already under stress and struggling to meet the demand of existing users. Potable groundwater availability for the demands of shale gas development is seriously constrained. There is potential to develop brackish or brack groundwater resources for this purpose. Except for hydraulic fracturing itself, several related activities will add to water quality and quantity concerns. These include road building, workforce accommodation etc. (CSIR, 2016).
Contamination of water sources
Pollution can take place in various ways due to potential exposure to extraneous chemicals used during fracking (ASSAf, 2016). Contamination pathways can be seen in Figure 2. The most likely source of water contamination is surface spills on site and along transport networks. Groundwater contamination is unlikely, (CSIR, 2016) as water extraction for human consumption is generally limited to depths of a few hundred meters while shale reservoirs usually lie as deep as 1 000m.
However, the dolerite and kimberlite intrusions in the western Karoo basin is non-uniform and their attributes that are deeper at 500m is unknown. Therefore, it is very difficult to foresee with certainty exactly what the real effects would be in each area. A cautious approach may thus be the best option. Consequently, a full understanding of the hydrogeological conditions is vital to prevent contamination of groundwater (DMR, 2012). The magnitude of the impact is dependent upon the proximity of the spill to water resources (CSIR, 2016).
Disposal of flowback
Water that ‘flows back’ during the fracking process is a mixture of fracking fluid and formation. Wastewater produced after hydraulic fracturing is highly saline (ASSAf, 2016) and the proportion of flowback varies from 0 to more than 100%, if flow from underground pockets of water is considered. Flowback is either treated and disposed of or reused.
The shale gas industry is a big proponent of water reuse. Experience in the United States (US) suggests that treatment facilities in South Africa do not have the capacity and expertise required, and must be purpose-built to accommodate this new type of wastewater (DMR, 2012).
Notwithstanding the best evidence and research, there are several factors that we simply know too little about at present.
- A comprehensive set of baseline information encompassing the following information is imperative:
- We need to determine the amount of reserves that are needed (wetlands, groundwater and surface water), to ensure water demands are met for both human and ecological requirements.
- Reliable information regarding water use, demand and quality in the Karoo is not available.
- A better understanding of the geology and hydrogeology of the area is needed: hydraulic properties, geological responses, the presence of potable groundwater at depth and interconnectivity of aquifers. Exploratory, specialised deep drilling is required to carry out a proper impact assessment.
- There is the need to improve the understanding of groundwater-surface water interaction to reduce risks to water resources.
- Monitoring of the abovementioned is important to ensure the protection of water resources.
- There is a lack of infrastructure and institutional capacity to ensure proper water management. Laboratories in South Africa are not equipped to analyse water quality parameters, and water treatment facilities lack the capacity and expertise to accommodate the wastes associated with shale gas development. There are few groundwater scientists and technicians in the country with the applicable experience associated with shale gas development. These structures need to be put in place before shale gas development can be considered.
The possibility of adverse consequences resulting from incorrect water management in relation to fracking in the Karoo is a high risk, due to a lack of institutional capacity and infrastructure. (CSIR, 2016). Concern of landowners over the negative impacts on domestic or stock water supplies is acknowledged.
Local landowners are mainly reliant on groundwater resources for domestic and stock water supplies. Uncertainties associated with the volumes of water available and the usage associated with fracking, limit the development of water and waste water management planning required to protect our water resources in the event of fracking taking place (CSIR, 2016).
The concerns surrounding shale gas development is very real, understandable and cannot be ignored. Water is a source of livelihood for the farming community and it is crucial to have a full understanding of possible future conflicts of interest. The overall recommendations made are to minimise any potential risks. – Agri SA